CN104247073A - Organic electroluminescent element and method for manufacturing same - Google Patents

Abstract

To provide: (1) an organic-inorganic hybrid-type organic electroluminescent element having excellent light-emission characteristics in which even when a low-molecular compound layer is used as the layer constituting the organic electroluminescent element, crystallization of the low-molecular compounds is suppressed; (2) an organic-inorganic hybrid-type organic electroluminescent element having even better light-emission characteristics than conventional organic-inorganic hybrid-type organic electroluminescent elements; and (3) an organic electroluminescent element that is easy to manufacture and that has excellent light-emission efficiency and lifespan. The present invention is an organic electroluminescent element having a structure in which a plurality of layers are stacked, the organic electroluminescent element being characterized in having a metal oxide layer between a first electrode and a second electrode and having, on the metal oxide layer, a buffer layer formed from an organic compound.

Description

Organic electroluminescence element and its manufacturing method

technical field

The invention relates to an organic electroluminescence element and a manufacturing method thereof. More specifically, the present invention relates to an organic electroluminescent element that can be used as a display device such as a display unit of an electronic device, a lighting device, and the like, and a method for manufacturing the same.

Background technique

Organic electroluminescence elements (organic EL elements) are expected as new light-emitting elements that can be applied to display devices and lighting.

Organic electroluminescent elements are characterized by being thin, soft, and flexible, and when used as display devices, they have the ability to achieve high-brightness and high-resolution displays compared with liquid crystal display devices or plasma display devices that are currently mainstream. , Compared with liquid crystal display devices, it has excellent characteristics such as a wider viewing angle, so it is expected that organic electroluminescence elements will expand their use as displays for televisions and mobile phones in the future and as lighting devices.

An organic EL element has a structure in which one or more layers including a light-emitting layer containing a light-emitting organic compound are interposed between an anode and a cathode, and the holes injected from the anode and electrons injected from the cathode are regenerated. The energy at the time of bonding excites the light-emitting organic compound to obtain light emission. The organic EL element is a current-driven element, and various improvements have been made to the element structure in order to utilize the flowing current more efficiently, and various studies have also been conducted on the materials of the layers constituting the element.

An organic electroluminescent device has a structure in which two or more layers, such as an electron transport layer, a light emitting layer, and a hole transport layer, are stacked between a cathode and an anode, and research and development have been conducted on materials suitable for each layer. For example, a light emitting material containing a compound having a specific structure having a boron atom is disclosed (see Patent Document 1). Also, it is disclosed that a compound having a specific structure having a boron atom is suitable as a hole blocking layer of an organic electroluminescent element (see Patent Document 2).

In addition, for an organic electroluminescent element that emits light by exciting a light-emitting organic compound by utilizing the energy of recombination of holes injected from the anode and electrons injected from the cathode, it is important that the holes injected from the anode, from The electron injection of the cathode is carried out smoothly, so in order to make the hole injection and electron injection more smoothly, various researches have been carried out on the materials of the hole injection layer and the electron injection layer. Recently, a positive structure of positive structure has been reported. An electroluminescent element (see Non-Patent Documents 1 to 3) uses polyethyleneimine or a compound obtained by modifying polyethyleneimine as a material for a coatable electron injection layer.

However, an organic electroluminescence element in which all the layers between the cathode and anode are formed of organic compounds tends to be easily degraded by oxygen and water, and tight sealing is essential to prevent their intrusion. . This becomes the reason why the manufacturing process of the organic electroluminescence element becomes complicated. In response to this, an organic-inorganic hybrid electroluminescent element (HOILED element) in which a part of the layer between the cathode and the anode is formed of an inorganic oxide has been proposed (see Patent Document 3). In this element, by changing the hole transport layer and the electron transport layer to inorganic oxides, it is possible to use FTO or ITO as a conductive oxide electrode as a cathode and use gold as an anode. From the viewpoint of device driving, this means that the limitation on electrodes is eliminated. As a result, it becomes possible to emit light without tight sealing without using a metal having a small work function such as an alkali metal or an alkali metal compound. In addition, the HOILED device has the following characteristics: the cathode is located immediately above the substrate as standard, and the anode is moved to the upper electrode to form an inverted structure. With the development of oxide TFTs, in the study of applications to large-scale organic EL displays, organic ELs with reverse structures have attracted attention due to the characteristics of n-type oxide TFTs. This HOILED element is expected to be developed as an alternative to the reverse structure organic EL element.

As a conventional organic-inorganic hybrid organic electroluminescence element, an organic thin film light-emitting element is disclosed, which has an anode, a cathode, and one or more organic compound layers interposed between the anode and the cathode. , and at least one metal oxide thin film is provided between the anode and the organic compound layer and between the cathode and the organic compound layer (see Patent Document 4). In addition, an organic thin-film electroluminescent element is disclosed, which has an anode, a cathode, and one or more organic compound layers interposed between the anode and the cathode, and between the anode and the organic compound layer or between the cathode and the organic compound layer is disclosed. There is at least one metal oxide film between the compound layers, and there is one or more self-assembled monomolecular films between the layers, and the self-assembled monomolecular film forms an energy potential for the main carrier Barrier, no energy barrier is formed for reverse carriers (see Patent Document 5). In addition, an organic-inorganic hybrid type organic electroluminescent device having a structure in which a polyvinylcarbazole polymer added with an iridium compound as a dopant is laminated on a metal oxide layer is disclosed (see Non-Patent Document 4) , and an organic-inorganic hybrid organic electroluminescent device using poly(9,9-dioctylfluorenyl-2,7-diyl) added with an iridium compound as a light-emitting layer (see Non-Patent Document 5).

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2011-184430

Patent Document 2: International Publication No. 2005/062676

Patent Document 3: Japanese Unexamined Patent Publication No. 2009-70954

Patent Document 4: Japanese Patent Laid-Open No. 2007-53286

Patent Document 5: Japanese Patent Laid-Open No. 2012-4492

non-patent literature

Non-Patent Document 1: Tao Xiong and 3 others "Applied Physics Letters" vol. 93, 2008, pp123310-1

Non-Patent Document 2: Yinhua Zhou and 21 others "Science" No. 336, 2012, pp327

Non-Patent Document 3: Jianshan Chen and 6 others "Journal of Materials Chemistry" 2012, volume 22, pp5164

Non-Patent Document 4: Henk J.Bolink and 3 others "Advanced Materials", 2010, Vol. 22, p2198-2201

Non-Patent Document 5: "Chemistry of Materials" by Henk J.Bolink and 2 others, 2009, Vol. 21, p439-441

Contents of the invention

The problem to be solved by the invention

As described above, research and development have been conducted on organic electroluminescent elements in which each layer constituting the organic electroluminescent element is composed of organic substances and organic-inorganic hybrid organic electroluminescent elements.

The organic-inorganic hybrid organic electroluminescent element is considered to have both the flexibility and moldability of the organic component and the strength and durability of the inorganic component. Compared with light-emitting elements, the resistance to oxygen and water is higher, so there is less need to hermetically seal each layer inside the element, and there are advantages such as less time and effort required for manufacture, and its practical application is expected. On the other hand, compared with the organic electroluminescent element in which each layer of the organic electroluminescent element is composed of organic substances, the organic-inorganic hybrid organic electroluminescent element still has room for improvement in various characteristics such as light emission characteristics. Therefore, it is necessary to develop an organic-inorganic hybrid organic electroluminescent element that further improves properties such as luminescence characteristics.

In general, for an organic electroluminescence element in which each layer constituting an organic electroluminescence element is composed of an organic substance, a method of laminating two or more types of low-molecular compound layers by a method such as vacuum deposition or by making a guest molecule The method of doping the host molecule, etc. to obtain a device with high luminescence characteristics. On the other hand, in the constitution of the organic-inorganic hybrid type organic electroluminescence device studied so far, the constitution in which a polymer compound is coated and formed into a film as a light-emitting layer has become the mainstream. In this regard, in order to improve the light-emitting characteristics of organic-inorganic hybrid organic electroluminescent elements, the present inventors used low-molecular-weight compounds as materials for forming the light-emitting layer, the hole transport layer, etc., and laminated two kinds of materials by vacuum evaporation and the like. Various studies have been conducted on the above-mentioned low-molecular-weight compound layer and the method of doping guest molecules into host molecules. As a result of this, it was found that a new problem as follows: if the oxide layer formed on the cathode is in contact with the low-molecular compound layer, the low-molecular compound layer in contact with the oxide layer will cause Crystallization increases leakage current and lowers current efficiency, and in severe cases, crystallization may cause a disadvantage that uniform surface emission cannot be obtained. Although the above-mentioned situation has not been observed in an element having a coating-type polymer organic layer, it is considered to have adverse effects, and it is considered that solving this problem is very important for prolonging the life of organic-inorganic hybrid organic electroluminescent elements. important.

In addition, in organic-inorganic hybrid organic electroluminescent elements, there is a problem that the injection of electrons from the cathode is less than the injection of holes from the anode, and the holes injected from the anode cannot be fully utilized. to shine. In addition, it is difficult to achieve long-term good physical electrical contact between the inorganic layer and the organic layer, which leads to a short life of the device, which is an important issue.

Ease of manufacture is also an important factor for organic electroluminescent elements that are expected to be widely used in applications such as display devices and lighting devices, so organic-inorganic hybrid organic electroluminescent elements that do not require tight sealing are highly expected, and There is a need for a method of further improving the luminous efficiency and lifetime of an organic-inorganic hybrid organic electroluminescent device. In addition, in display applications, HOILED elements having an inverted structure are useful in circuits, and their development is expected.

The present invention has been accomplished in view of the above circumstances, and its object is (1) to provide an organic-inorganic hybrid organic electroluminescent element, even when a low-molecular compound layer is used as a layer constituting the organic electroluminescent element. Crystallization of low-molecular compounds can be suppressed, and the light-emitting characteristics are excellent; (2) an organic-inorganic hybrid organic electroluminescent element having better light-emitting characteristics than existing organic-inorganic hybrid organic electroluminescent elements is provided; and (3) ) provides an organic electroluminescence element which is easy to manufacture and is excellent in both luminous efficiency and lifetime.

means of solving problems

The inventors of the present invention have found that in an organic-inorganic hybrid organic electroluminescence element having a metal oxide layer between the first electrode and the second electrode, by providing a buffer layer made of an organic compound on the metal oxide layer, the solve the above problems. The so-called buffer layer here refers to a layer that solves the problems of the above-mentioned organic-inorganic hybrid organic electroluminescent element, that is, solves crystallization of organic layers such as the light-emitting layer, low electron injection ability, and long-term physical and chemical properties of the interface. layer of stability. Specifically, in order to prevent crystallization due to unevenness on the surface of the oxide, a higher molecular weight organic substance is preferable. In addition, in order to improve the electron injection ability, it is preferable to form the energy level up to the light-emitting layer into a step In addition, in order to make the energy pumping (pumping) (improving the level of energy (jump, uphill)) that exists as a problem unique to the reverse structure proceed smoothly, it is more preferable to increase the number of carriers by doping or the like. . In order to improve the electron injection ability, there is also a method of generating an interface dipole by distributing a large amount of nitrogen element on the surface, and this method is also preferable. And, in order to make them exist stably for a long period of time, it is preferable to prevent the presence of localized electric fields or to prepare chemical bonds that can withstand the presence of localized electric fields. The former is that the increase in the number of carriers achieved by doping and other methods leads to the formation of a large energy level change and a stepped well-balanced electronic energy level. The latter is the chemical bond between the buffer layer organic matter and the metal elements on the oxide surface. Specific examples are described below.

The inventors of the present invention conducted various studies on methods for improving the light-emitting characteristics of an organic-inorganic hybrid type organic electroluminescent element, discovered a new problem of crystallization of a low-molecular compound layer, and studied a solution, and found that, A buffer layer having a predetermined film thickness formed by coating an organic compound is arranged between the oxide layer formed on the cathode and a low molecular compound layer such as a light emitting layer, and a low molecular compound layer such as a light emitting layer is laminated on the buffer layer, With the above configuration, the crystallization of the low-molecular compound in the low-molecular compound layer is suppressed, so that even when an organic-inorganic hybrid organic electroluminescent element has a layer formed of a low-molecular compound as a light-emitting layer, etc. Suppressed leakage current and uniform surface emission can be obtained. In addition, the present inventors found that if a boron-containing compound or a boron-containing polymer having a specific structure is used as an organic compound for forming a buffer layer, the buffer layer formed of the organic compound can also exhibit an excellent function as an electron transport layer.

In addition, the inventors of the present invention have conducted various studies on methods for improving the light-emitting characteristics of an organic-inorganic hybrid organic electroluminescent element, and found that if a metal oxide layer is formed between the first electrode and the second electrode, the The metal oxide layer has an organic electroluminescent element composed of a buffer layer formed of an organic compound, and the buffer layer of the organic electroluminescent element contains a reducing agent, and the reducing agent acts as an n-type dopant for donating electrons. The organic electroluminescent element can be formed with light emitting characteristics superior to conventional organic-inorganic hybrid organic electroluminescent elements. In addition, it was found that the organic electroluminescent element formed has a first metal oxide layer, a buffer layer, and a low-voltage layer including a light-emitting layer stacked on the buffer layer in this order between the first electrode and the second electrode. When the molecular compound layer and the second metal oxide layer are used, and the buffer layer of the organic electroluminescent element contains a reducing agent, the organic electroluminescent element is preferable.

In addition, the present inventors conducted various studies on methods for further improving the luminous efficiency and lifetime of an organic-inorganic hybrid organic electroluminescent element that does not require tight sealing, and found that if the metal oxide between the anode and the cathode Forming a nitrogen-containing film with a predetermined thickness on the material layer improves the electron injection characteristics and prolongs the device life. Among them, it is also found that it is more preferable to have a nitrogen-containing film with a high ratio of nitrogen atoms in the atoms constituting the nitrogen-containing film and/or a nitrogen-containing film formed by decomposing a nitrogen-containing compound to form a nitrogen-containing film, and it is further found that it is more preferable A nitrogen-containing film formed by decomposing a nitrogen-containing compound and having a high ratio of nitrogen atoms among atoms constituting the nitrogen-containing film. When using the above-mentioned nitrogen-containing film as a layer constituting an organic-inorganic hybrid organic electroluminescent element, the present inventors found that the formed organic electroluminescent element not only has excellent luminous efficiency, but also has high driving stability and long driving life. The above-mentioned problems can be perfectly solved, and the present invention has been completed.

That is, the present invention is an organic electroluminescence element having a structure in which two or more layers are stacked, wherein the organic electroluminescence element is characterized in that the organic electroluminescence element is formed between the first electrode and the second electrode. A metal oxide layer is provided between the electrodes, and a buffer layer made of an organic compound is provided on the metal oxide layer.

In addition, a first preferred embodiment of the organic electroluminescent element of the present invention is an organic electroluminescent element having a structure in which two or more layers are laminated, wherein: The above-mentioned organic electroluminescent element has a first metal oxide layer, a buffer layer, a low-molecular compound layer including a light-emitting layer stacked on the buffer layer, and a second metal oxide layer in this order between the first electrode and the second electrode. layer, the buffer layer is a layer with an average thickness of 5 to 50 nm formed by coating a solution containing an organic compound.

In addition, a second preferred embodiment of the organic electroluminescent element of the present invention is an organic electroluminescent element having a structure in which two or more layers are stacked, wherein: The above-mentioned organic electroluminescent element has a first metal oxide layer, a buffer layer, a low-molecular compound layer including a light-emitting layer stacked on the buffer layer, and a second metal oxide layer in this order between the first electrode and the second electrode. layer, the above-mentioned buffer layer contains a reducing agent.

In addition, a third preferred embodiment of the organic electroluminescence element of the present invention is an organic electroluminescence element having a structure in which two or more layers are stacked between an anode and a cathode formed on a substrate The organic electroluminescent element, characterized in that the organic electroluminescent element has a metal oxide layer between the anode and the cathode, and has a nitrogen-containing film on the metal oxide layer with an average thickness of 3 to 150 nm. layer.

The present invention is described in detail below.

In addition, the aspect which combined two or more of the various preferable aspects of this invention described below is also a preferable aspect of this invention.

The organic electroluminescent element of the present invention is an organic electroluminescent element having a structure in which two or more layers are laminated, wherein a metal oxide layer is provided between the first electrode and the second electrode, and the metal oxide There is a buffer layer formed of an organic compound on the layer.

The first electrode is a cathode formed on the substrate, and has a metal oxide layer and a buffer layer made of an organic compound sequentially between the anode as the second electrode, which is a preferred embodiment of the organic electroluminescent element of the present invention.

In addition, the buffer layer is a layer having an average thickness of 3 nm or more formed by coating a solution containing an organic compound, and the buffer layer is formed adjacently on the metal oxide layer, which is also the organic electroluminescent element of the present invention. preferred method.

The organic electroluminescent device of the present invention has three preferred modes in which the layer configuration of the device and the buffer layer are different. These three preferred modes will be described in turn below. It should be noted that, those conforming to two or more of these three preferred forms are also preferred forms of the organic electroluminescence element of the present invention.

[Organic electroluminescence element of the first preferred embodiment of the present invention]

The organic electroluminescent element according to the first preferred mode of the present invention (hereinafter also referred to as the first organic electroluminescent element of the present invention) has a first metal oxide layer and a buffer layer in this order between the first electrode and the second electrode. , a low-molecular compound layer including a light-emitting layer, and a second metal oxide layer laminated on the buffer layer, and the buffer layer has an average thickness of 3 nm. In addition, it is preferable that the buffer layer has an average thickness of 5 to 50 nm. In addition, it is also preferable that the buffer layer has an electron energy level in which the order of electron energy levels of each layer from the electrode formed on the substrate to the light emitting layer is equal to the lamination order of these layers.

By having the above configuration, the first organic electroluminescent device of the present invention can suppress crystallization of the low molecular compound layer even when the layer constituting the organic electroluminescent device such as the light emitting layer is a low molecular compound layer. , can suppress leakage current and obtain uniform surface emission.

In organic-inorganic hybrid organic electroluminescent devices, the reason why the low-molecular compound layer crystallizes can be considered as follows.

In an organic-inorganic hybrid organic electroluminescent element, there are a first electrode and a first metal oxide layer disposed on a substrate such as glass, and a low-molecular compound layer including a light-emitting layer is formed thereon. Here, according to a conventional method, the first metal oxide layer is formed by a spray pyrolysis method, a sol-gel method, a sputtering method, etc., and the surface is not smooth but has unevenness. When a low-molecular compound layer including a light-emitting layer is formed on the first metal oxide layer by vacuum evaporation or the like, the irregularities on the surface of the first metal oxide layer become crystal nuclei, which promotes oxidation with the first metal oxide layer. Crystallization of the low-molecular compound layer in contact with the material layer. Therefore, even if the organic electroluminescent element is completed, a large leakage current flows, and the light emitting surface becomes non-uniform, so that a practically durable element cannot be obtained.

On the other hand, for an organic electroluminescent element of a so-called conventional structure that does not have a first metal oxide layer on the first electrode, it is possible to obtain an element in which the surface of the first electrode is polished sufficiently smooth, even at the 1. A low-molecular compound layer including a light-emitting layer is directly formed on the surface of the electrode, and problems such as crystallization are less likely to occur. Therefore, this crystallization is a problem unique to organic-inorganic hybrid organic electroluminescent elements, and the first organic electroluminescent element of the present invention can solve this organic-inorganic hybrid organic electroluminescent element by having the above-mentioned structure. unique issues of organic electroluminescent devices.

When the first organic electroluminescent element of the present invention has the above-mentioned preferred structure, it only needs to have the first metal oxide layer and the buffer layer with an average thickness of 5 to 50 nm formed by organic compounds in order between the first electrode and the second electrode. , the low-molecular compound layer including the light-emitting layer, and the second metal oxide layer laminated on the buffer layer may have layers other than these.

It should be noted that the low-molecular-weight compound in the present invention means a compound other than a high-molecular compound (polymer), and does not necessarily mean a compound with a low molecular weight.

The aforementioned low-molecular compound layer including a light-emitting layer means one layer made of a low-molecular compound, or two or more layers made of a low-molecular compound are laminated, and one of the layers is a light-emitting layer. That is, the low-molecular compound layer including the light-emitting layer refers to a light-emitting layer formed of a low-molecular compound, or a low-molecular compound layer in which a light-emitting layer formed of a low-molecular compound is laminated with another layer formed of a low-molecular compound. any kind. The other layer formed from the low molecular weight compound may be one layer or two or more layers. In addition, there is no particular limitation on the lamination order of the light emitting layer and other layers.

The above-mentioned other layer formed of a low-molecular compound is preferably a hole transport layer or an electron transport layer. That is, when the low molecular compound layer is composed of two or more layers, it is preferable to have a hole transport layer and/or an electron transport layer as layers other than the light emitting layer. Therefore, it is one of the preferred embodiments of the first organic electroluminescent element of the present invention that the organic electroluminescent element has the hole transport layer and/or the electron transport layer as an independent layer different from the light emitting layer.

When the first organic electroluminescent device of the present invention has a hole transport layer as an independent layer, it is preferable to have a hole transport layer between the light emitting layer and the second metal oxide layer. When the first organic electroluminescent device of the present invention has an electron transport layer as an independent layer, it is preferable to have an electron transport layer between the buffer layer formed of an organic compound and the light emitting layer.

When the first organic electroluminescent element of the present invention does not have the hole transport layer and the electron transport layer as independent layers, any one of the layers that are essential components of the first organic electroluminescent element of the present invention also has It has the functions of the above layers.

One of the preferred forms of the first organic electroluminescent element of the present invention is the following form: the organic electroluminescent element consists only of the first electrode, the first metal oxide layer, the buffer layer formed by the organic compound, the light emitting layer, the hole A transport layer, a second metal oxide layer, and a second electrode, any one of these layers also functions as an electron transport layer.

In addition, the following mode is also one of the preferred modes of the first organic electroluminescent element of the present invention: the organic electroluminescent element only consists of the first electrode, the first metal oxide layer, the buffer layer formed by the organic compound, the light emitting layer, The second metal oxide layer and the second electrode are constituted, and any one of these layers functions as a hole transport layer and an electron transport layer.

In the first organic electroluminescent element of the present invention, the first electrode is a cathode, and the second electrode is an anode. In the organic electroluminescent device of the present invention, known conductive materials can be used as appropriate for the anode and cathode, but at least one of them is preferably transparent for light extraction. Examples of known transparent conductive materials include ITO (tin-doped indium oxide), ATO (antimony-doped indium oxide), IZO (indium-doped zinc oxide), AZO (aluminum-doped zinc oxide), FTO (fluorine-doped indium oxide), In ₃ O ₃ , SnO ₂ , oxides such as SnO ₂ containing Sb, ZnO containing Al, etc. Examples of opaque conductive materials include calcium, magnesium, aluminum, tin, indium, copper, silver, gold, platinum, or alloys thereof.

As the cathode, among them, ITO, IZO, and FTO are preferable.

Examples of the anode include Au, Pt, Ag, Cu, Al, alloys containing these, and the like. Among these, Au, Ag, and Al are preferable.

As described above, since metals that are generally used for anodes can be used in the cathode and anode, it is also possible to easily realize the case where light is extracted from the upper electrode (in the case of a top emission structure), and the above-mentioned various electrodes can be selected. in their respective electrodes. For example, Al is used as the lower electrode, and ITO is used as the upper electrode.

The average thickness of the first electrode is not particularly limited, but is preferably 10 to 500 nm. More preferably, it is 100 to 200 nm. The average thickness of the first electrode can be measured with a stylus profiler or a spectroscopic ellipsometer.

The average thickness of the second electrode is not particularly limited, but is preferably 10 to 1000 nm. More preferably, it is 30 to 150 nm. Also, even when a non-light-transmitting material is used, for example, by setting the average thickness to about 10 to 30 nm, it can be used as an anode of a top emission type or a transparent type.

The average thickness of the second electrode can be measured at the time of film formation using a quartz vibrator film thickness meter.

The above-mentioned first metal oxide layer is a layer that functions as an electron injection layer or an electrode (cathode), and the second metal oxide layer is a layer that functions as a hole injection layer.

The first metal oxide layer is a layer composed of a single metal oxide film or a layer formed by laminating and/or mixing a single metal oxide or two or more metal oxides. Layers of semiconducting or insulator stacked films. Metal elements constituting the metal oxide are selected from magnesium, calcium, strontium, barium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, indium, gallium, iron, cobalt, nickel, copper , zinc, cadmium, aluminum, silicon, tin group. Among these, it is preferable that at least one of the metal elements constituting the laminated metal oxide layer or the mixed metal oxide layer is selected from the layer of magnesium, aluminum, calcium, zirconium, hafnium, silicon, titanium, zinc, tin, wherein If it is a single metal oxide, it preferably contains a metal oxide selected from the group consisting of magnesium oxide, tungsten oxide, niobium oxide, iron oxide, aluminum oxide, zirconium oxide, hafnium oxide, silicon oxide, titanium oxide, zinc oxide, and tin oxide. Metal oxide.

Examples of the layer formed by laminating and/or mixing a single metal oxide or two or more metal oxides include titanium oxide/zinc oxide, titanium oxide/magnesia, titanium oxide/zirconia , titanium oxide/alumina, titanium oxide/hafnium oxide, titanium oxide/silicon oxide, zinc oxide/magnesium oxide, zinc oxide/zirconia, zinc oxide/hafnium oxide, zinc oxide/silicon oxide, calcium oxide/alumina and other metals A layered and/or mixed layer of a combination of oxides; or titanium oxide/zinc oxide/magnesia, titanium oxide/zinc oxide/zirconia, titanium oxide/zinc oxide/alumina, titanium oxide/zinc oxide A combination of three metal oxides such as hafnium oxide, titanium oxide/zinc oxide/silicon oxide, indium oxide/gallium oxide/zinc oxide is laminated and/or mixed. Among these, IGZO, which is an oxide semiconductor exhibiting favorable characteristics with a special composition, and 12CaO·7Al ₂ O ₃ , which is an electride, may also be included.

It should be noted that, in the present invention, a substance with a sheet resistance lower than 100Ω/□ is classified as a conductor, and a substance with a sheet resistance higher than 100Ω/□ is classified as a semiconductor or an insulator. Therefore, ITO (tin-doped indium oxide), ATO (antimony-doped indium oxide), IZO (indium-doped zinc oxide), AZO (aluminum-doped zinc oxide), FTO (fluorine-doped Thin films such as heterogeneous indium oxide) are not included in the category of semiconductors or insulators due to their high conductivity, and therefore do not correspond to one layer constituting the first metal oxide layer of the present invention.

The second metal oxide layer is not particularly limited, and one or two of vanadium oxide (V ₂ O ₅ ), molybdenum oxide (MoO ₃ ), tungsten oxide (WO ₃ ), and ruthenium oxide (RuO ₂ ) can be used. more than one species. Among these, it is preferable to use vanadium oxide or molybdenum oxide as a main component. If the second metal oxide layer is composed of a substance mainly composed of vanadium oxide or molybdenum oxide, the second metal oxide layer acts as a hole that injects holes from the second electrode and transports them to the light-emitting layer or the hole transport layer. The function of the injection layer is more excellent. In addition, vanadium oxide or molybdenum oxide has an advantage of being able to appropriately prevent a decrease in the injection efficiency of holes from the second electrode to the light-emitting layer or the hole-transporting layer because of its high hole-transporting properties. More preferably, it consists of vanadium oxide and/or molybdenum oxide.

The average thickness of the above-mentioned first metal oxide layer can be allowed to range from 1 nm to several μm, and is not particularly limited, but is preferably 1 to 1000 nm from the viewpoint of forming an organic electroluminescence device that can be driven at a low voltage. More preferably, it is 2 to 100 nm.

The average thickness of the second metal oxide layer is not particularly limited, but is preferably 1 to 1000 nm. More preferably, it is 5 to 50 nm.

The average thickness of the first metal oxide layer can be measured by a stylus profiler or a spectroscopic ellipsometer.

The average thickness of the second metal oxide layer can be measured at the time of film formation using a quartz vibrator film thickness meter.

As the material of the light-emitting layer, any low-molecular compound generally used as a material of the light-emitting layer may be used, or they may be mixed for use.

Examples of low-molecular-weight substances include tricoordinate iridium complexes having 2,2'-bipyridine-4,4'-dicarboxylic acid in the ligand, tris(2-phenylpyridine)iridium (Ir(ppy) ₃ ), 8-hydroxyquinoline aluminum (Alq ₃ ), tris(4-methyl-8-hydroxyquinoline) aluminum (III) (Almq ₃ ), 8-hydroxyquinoline zinc (Znq ₂ ), (1,10-phenanthroline) tris[4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione]europium(III)(Eu(TTA) ₃ ( phen)), various metal complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphine platinum(II); distyrylbenzene ( DSB), diaminodistyrylbenzene (DADSB) and other benzene compounds; naphthalene compounds; phenanthrene compounds; chrysene compounds; perylene compounds; coronene compounds; anthracene compounds; pyrene compounds; pyrene compounds Acridine compounds; Stilbene compounds; Carbazole compounds; Thiophene compounds; Benzoxazole compounds; Benzimidazole compounds; Benzothiazole compounds; Butadiene compounds; Naphthalene compounds Amine-based compounds; Coumarin-based compounds; Viridone-based compounds; Oxadiazole-based compounds; Aldazine-based compounds; Cyclopentadiene-based compounds; Quinacridone-based compounds; , 7,7'-tetraphenyl-9,9'-spirobifluorene and other spiro compounds; metal or non-metallic phthalocyanine compounds; and JP-A-2009-155325, JP-A- No. 28273, Japanese Patent Application No. 2010-230995, and Japanese Patent Application No. 2011-6458, etc., can use one or more of them.

The above-mentioned light-emitting layer may contain a dopant. As a dopant, any compound that can generally be used as a dopant can also be used. Examples of compounds that can be used as dopants include iridium compounds; 4,4'-bis(9-ethyl-3-carbazole vinyl)-1,1'-biphenyl (BCzVBi) Molecular organic compounds and the like can use one or two or more of them.

When the above-mentioned light-emitting layer contains a dopant, the content of the dopant is preferably 0.5 to 20% by mass relative to 100% by mass of the material forming the light-emitting layer. If it is the above-mentioned content, it becomes possible to form the element which made light-emitting characteristic more favorable. More preferably, it is 0.5-10 mass %, More preferably, it is 1-6 mass %.

The average thickness of the light-emitting layer is not particularly limited, but is preferably 10 to 150 nm. More preferably, it is 20 to 100 nm. More preferably, it is 40 to 100 nm.

The average thickness of the light-emitting layer can be measured by a quartz vibrator film thickness meter in the case of a low-molecular compound, and can be measured by a contact profiler in the case of a high-molecular compound.

As the material of the above-mentioned hole transport layer, any low-molecular compound that can be generally used as a material of the hole transport layer can also be used, and they can also be used in combination.

Examples of low-molecular compounds include arylcycloalkane compounds, arylamine compounds, phenylenediamine compounds, carbazole compounds, stilbene compounds, oxazole compounds, triphenylmethane compounds, pyrazoline Compounds based on benzyne (cyclohexadiene) compounds, triazole compounds, imidazole compounds, oxadiazole compounds, anthracene compounds, fluorenone compounds, aniline compounds, silane compounds, pyrrole fluorene-based compounds, fluorene-based compounds, porphyrin-based compounds, quinacridone-based compounds, metal or non-metallic phthalocyanine-based compounds, metal or non-metallic naphthalocyanine-based compounds, benzidine-based compounds, etc., among which 1 or more than 2 types.

Among these, N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (α-NPD), TPTE Such arylamine compounds.

When the first organic electroluminescent device of the present invention has a hole transport layer as an independent layer, the average thickness of the hole transport layer is not particularly limited, but is preferably 10 to 150 nm. More preferably, it is 20-100 nm, More preferably, it is 40-100 nm.

The average thickness of the hole transport layer can be measured at the time of film formation using a quartz vibrator film thickness meter.

As the material of the above-mentioned electron transport layer, any low-molecular compound that can generally be used as a material of the electron transport layer can also be used, and they can also be used in admixture.

Examples of low-molecular compounds that can be used as materials for the electron transport layer include pyridine derivatives, quinoline derivatives, pyrimidine derivatives, pyrazine derivatives, and boron-containing compounds represented by the following formula (1). Derivatives, phenanthroline derivatives, triazine derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, aromatic ring tetracarboxylic anhydride; with (2-(4-methyl- Various metal complexes represented by 2-hydroxyphenyl)benzothiazole)zinc (Zn(BTZ) ₂ ), tris(8-hydroxyquinoline)aluminum (Alq ₃ ), etc.; represented by silole derivatives One kind or two or more kinds of organosilane derivatives etc. among them can be used.

Among these, metal complexes such as Alq ₃ and pyridine derivatives such as tris-1,3,5-(3'-(pyridin-3"-yl)phenyl)benzene (TmPyPhB) are preferable.

When the first organic electroluminescence device of the present invention has an electron transport layer as an independent layer, the average thickness of the electron transport layer is not particularly limited, but is preferably 10 to 150 nm. More preferably, it is 20-100 nm, More preferably, it is 40-100 nm.

The average thickness of the electron transport layer can be measured at the time of film formation using a quartz vibrator film thickness meter.

For the first organic electroluminescent element of the present invention, the method for forming the first and second metal oxide layers, the second electrode, the light emitting layer, the hole transport layer, and the electron transport layer is not particularly limited, and it can be used as a vapor phase Chemical vapor deposition methods (CVD) such as plasma CVD, thermal CVD, and laser CVD for film formation; dry plating methods such as vacuum evaporation, sputtering, and ion plating; thermal spraying methods; and liquid-phase film-forming methods Wet plating methods such as electrolytic plating, immersion plating, and electroless plating; sol/gel method, MOD method, spray pyrolysis method, doctor blade method using fine particle dispersion, spin coating method, inkjet method, screen A printing technique such as a printing method, an atomic layer deposition (ALD) method, or the like can be selected and used according to a material.

The buffer layer included in the first organic electroluminescent element of the present invention is a layer formed by applying a solution containing an organic compound. Forming a buffer layer with a predetermined thickness by coating can effectively suppress the crystallization of the low-molecular compound formed on the buffer layer.

The method for coating the above-mentioned solution containing an organic compound is not particularly limited, and spin coating, casting, micro-gravure coating, gravure coating, bar coating, roll coating, Various coating methods such as wire-bar coating, slit coating, dip coating, spray coating, screen printing, flexographic printing, offset printing, and inkjet printing. Among them, the spin coating method is preferable.

By forming the buffer layer by coating, the unevenness existing on the surface of the first metal oxide layer is smoothed, thereby suppressing the crystallization of the low-molecular compound subsequently formed on the buffer layer.

The solvent used to prepare the above-mentioned solution containing an organic compound is not particularly limited as long as it is a solvent capable of dissolving an organic compound, and examples thereof include nitric acid, sulfuric acid, ammonia, hydrogen peroxide, water, carbon disulfide, carbon tetrachloride, Inorganic solvents such as ethylene carbonate; ketone solvents; alcohol solvents; ether solvents; cellosolve solvents; aliphatic hydrocarbon solvents such as hexane, pentane, heptane, and cyclohexane; toluene, xylene, Aromatic hydrocarbon solvents such as benzene; aromatic heterocyclic compound solvents; amide solvents; halogen-containing compound solvents; ester solvents; sulfur-containing compound solvents; nitrile solvents; organic acid solvents and other organic solvents; or mixed solvents containing them, etc. Among these, THF, toluene, and chloroform are preferable.

The organic compound-containing solution preferably has a concentration of the organic compound in the solvent of 0.05 to 10% by mass. When it is the above-mentioned concentration, it is possible to suppress the occurrence of coating unevenness and unevenness during coating. The concentration of the organic compound in the solvent is more preferably 0.1 to 5% by mass, and still more preferably 0.1 to 3% by mass.

The above-mentioned buffer layer preferably has electron energy levels in which the order of electron energy levels of each layer from the electrodes formed on the substrate to the light-emitting layer is equal to the stacking order of these layers. The order of the electron energy level of each layer from the electrode (cathode) formed on the substrate to the light-emitting layer is the same as the stacking order, and the level of the electron energy level increases step by step from the electrode (cathode) to the light-emitting layer, thereby The movement of electrons from the electrode (cathode) to the light-emitting layer can be carried out relatively smoothly during the jump.

The above-mentioned buffer layer preferably has an average thickness of 5 to 50 nm. When the average thickness is within the above range, the effect of suppressing crystallization of the low molecular compound layer including the light emitting layer can be sufficiently exhibited. If the average thickness of the buffer layer is less than 5 nm, the unevenness existing on the surface of the first metal oxide cannot be sufficiently smoothed, and leakage current may increase, so that the effect of the present invention may not be sufficiently exhibited. In addition, when the average thickness of the buffer layer is thicker than 50 nm, the driving voltage will increase, which is not practically preferable. In addition, when a compound having a preferred structure in the present invention described later is used as the organic compound, the buffer layer can also sufficiently function as an electron transport layer. The average thickness of the buffer layer is more preferably 10 to 30 nm.

The average thickness of the buffer layer can be measured by a stylus profiler or a spectroscopic ellipsometer.

However, the above-mentioned Japanese Unexamined Patent Application Publication No. 2012-4492 (Patent Document 5) discloses an organic thin film electroluminescent device having an anode, a cathode, and one or more layers sandwiched between the anode and the cathode. An organic compound layer, and between the anode and the organic compound layer or between the cathode and the organic compound layer has at least one metal oxide thin film, and has one or two or more self-assembled monomolecular films between the above-mentioned layers, This self-assembled monomolecular film acts as an energy barrier for main carriers and does not form an energy barrier for reverse carriers. This patent document describes an organic-inorganic hybrid electroluminescence device as follows: a self-assembled monomolecular film having a specific energy level is formed (by a film-forming method including coating) on an oxide substrate. , whereby carriers opposite to the main carriers are injected as carriers due to the tunneling effect. In addition, it is described that carrier injection by tunneling is performed well when the self-assembled monomolecular film is a thin film of 2 nm or less (from the description in Patent Document 5, the average thickness of the organic compound layer is estimated to be 2 nm or less). On the other hand, in order to obtain a sufficient effect on the problem to be solved by the present invention as in Examples described later, the average thickness of the organic compound layer needs to be 5 nm or more.

Therefore, the problem to be solved and the solution means of the present invention and the invention disclosed in Patent Document 5 are essentially different, and the two should be clearly distinguished.

The first organic electroluminescence element of the present invention may be formed by laminating layers constituting the organic electroluminescence element on a substrate. When the respective layers are laminated on the substrate, it is preferable to form the respective layers on the first electrode formed on the substrate. In this case, the first organic electroluminescent element of the present invention may be a top emission type element that extracts light from the side opposite to the side where the substrate exists, or may be a bottom emission type element that extracts light from the side where the substrate exists. type components.

Examples of materials for the substrate include polyethylene terephthalate, polyethylene naphthalate, polypropylene, cycloolefin polymers, polyamide, polyethersulfone, polymethylmethacrylate, polycarbonate Resin materials such as ester and polyarylate; or glass materials such as quartz glass and soda-lime glass, etc., one or two or more of them can be used.

In addition, in the case of the top emission type, an opaque substrate can also be used, for example, a substrate made of a ceramic material such as alumina, or a metal substrate such as stainless steel with an oxide film (insulating film) formed on the surface can also be used. Substrates, substrates made of resin materials, etc.

The average thickness of the substrate is preferably 0.1 to 30 mm. More preferably, it is 0.1-10 mm.

The average thickness of the substrate can be measured using a digital multimeter and a vernier caliper.

The first organic electroluminescent element of the present invention has a structure in which a solution containing an organic compound is applied to form a buffer layer, and a low-molecular compound layer such as a light-emitting layer is laminated thereon, thereby solving the problem of crystallization of the low-molecular compound. The problem unique to the organic-inorganic hybrid organic electroluminescence element. Such a method for manufacturing an organic-inorganic hybrid organic electroluminescent element according to the first preferred mode of the present invention is also one of the present inventions, that is, an organic electroluminescent element having a structure in which two or more layers are laminated. The manufacturing method is characterized in that the manufacturing method comprises a first metal oxide layer, a buffer layer, and a light-emitting layer laminated on the buffer layer between the first electrode and the second electrode according to the organic electroluminescent element. A step of laminating each layer constituting an organic electroluminescence element by forming a low-molecular compound layer and a second metal oxide layer, the lamination step comprising applying a solution containing an organic compound to form a buffer layer having an average thickness of 3 nm or more process.

In the method for producing an organic electroluminescent device of the present invention, the step of applying a solution containing an organic compound to form a buffer layer is preferably a step of forming a buffer layer with an average thickness of 5 to 50 nm.

On the premise of including the above-mentioned steps, the method for manufacturing an organic electroluminescent element in the above-mentioned first preferred mode of the present invention may also include other steps, and may also include forming the first and second metal oxide layers, buffer layers, and including light emission. The process of layers other than the low-molecular compound layer of the layer. In addition, the material, formation method, organic compound, solvent used for preparing a solution containing the organic compound, and the thickness of each layer forming the organic electroluminescent element are the same as those of the first organic electroluminescent element of the present invention, preferably The scheme is also the same.

For the first organic electroluminescent element of the present invention, the organic compound forming the buffer layer is not particularly limited as long as it can form a layer of the organic compound by coating. Examples of the organic compound include trans polyacetylene, cis Polyacetylene compounds such as polyacetylene, poly(diphenylacetylene) (PDPA), poly(alkylphenylacetylene) (PAPA); polyparaphenylene vinylene compounds; polythiophene compounds; Polyfluorene-based compound; Poly-p-phenylene-based compound; Polycarbazole-based compound; Polysilane-based compound; Polyethyleneimine (PEI); Boron-containing compound represented by the following formula (1); will contain the following Boron-containing compounds such as boron-containing polymers obtained by polymerizing monomer components of boron-containing compounds represented by formula (2); or 3TPYMB: tris(2,4,6-trimethyl-3(pyridin-3-yl) Boron-containing electron transport materials such as phenyl)borane (Tris(2,4,6-triMethyl-3-(pyridin-3-yl)phenyl)borane). These may be used 1 type or 2 or more types.

In the first organic electroluminescent device of the present invention, the organic compound forming the buffer layer is preferably an organic compound having a boron atom. More preferably, the organic compound having a boron atom is a compound having a structure represented by the following formula (1) or a boron-containing polymer obtained by polymerizing a monomer component containing a boron-containing compound represented by the following formula (2).

That is, for the first organic electroluminescent element of the present invention, the organic compound having a boron atom forming the buffer layer is preferably a compound having a structure represented by the following formula (1) or will contain a compound represented by the following formula (2): A boron-containing polymer obtained by polymerizing monomer components of a boron-containing compound.

[chemical 1]

(In the above formula, the dotted line arc indicates that a ring structure is formed together with the skeleton part shown by the solid line. The dotted line part in the skeleton part shown by the solid line shows that a pair of atoms connected by the dotted line can be connected by a double bond. From the nitrogen atom The arrow pointing to the boron atom indicates that the nitrogen atom is coordinated to the boron atom. Q ¹ and Q ² are the same or different, and they are linking groups in the skeleton part represented by the solid line, at least partially form a ring structure together with the dotted line arc part, they With or without substituents. ^{X 1} , X ² , X ³ and X ⁴ are the same or different, representing a hydrogen atom or a monovalent substituent as a substituent on the ring structure, and the ring structure forming the dotted arc part can be Two or more X ¹ , X ² , X ³ , and X ⁴ are bonded. ^{n 1} represents an integer of 2 to 10. Y ¹ is a direct bond or a linking group with ¹ valency of n, which means that it is connected to the existing n ¹ Structural moieties other than Y ¹ are each independently bonded to any of the ring structures forming the dotted arc portion, Q ¹ , Q ² , X ¹ , X ² , X ³ , X ⁴ );

[Chem 2]

(In the above formula, the dotted arc indicates that a ring structure is formed with a part of the skeleton part connecting the boron atom and the nitrogen atom. The dotted line part in the skeleton part connecting the boron atom and the nitrogen atom represents that at least one pair of atoms is connected by a double bond, and the The double bond can form a conjugation with the ring structure. The arrow pointing from the nitrogen atom to the boron atom indicates that the nitrogen atom is coordinated to the boron atom. ^X5 and ^X6 are the same or different and represent a hydrogen atom or a monovalent substituent as a substituent on the ring structure , two or more X ⁵ and X ⁶ may be bonded to the ring structure forming the arc portion of the dotted line. R ¹ and R ² are the same or different, and represent a hydrogen atom or a monovalent substituent. X ⁵ , X ⁶ , R ¹ and At least one of R ² is a substituent having a reactive group).

In an organic-inorganic hybrid electroluminescent element, it is known that hole injection from the anode occurs more efficiently than electron injection from the cathode, and the light-emitting site exists in the cathode-side oxide (corresponding to the first metal oxide in the present invention) near the interface. In order to avoid light emission from the buffer layer in contact with the first metal oxide layer, it is preferable to select a compound having a lower HOMO level than that of the light-emitting compound contained in the light-emitting layer as the organic compound forming the buffer layer. Furthermore, in order to prevent the energy of the excitons generated in the light-emitting layer from moving to the compound in the buffer layer to emit light, as the organic compound forming the buffer layer, it is more preferable to select a compound having a HOMO-LUMO energy gap higher than that of the light-emitting compound contained in the light-emitting layer. Compounds with a wide HOMO-LUMO energy gap. The boron-containing compound represented by the above formula (1) and the boron-containing polymer obtained by polymerizing monomer components containing the boron-containing compound represented by the formula (2) have both a very low HOMO and a very wide HOMO-LUMO Energy gap, and it is a compound that can be applied, so it can effectively work on various light-emitting layers.

In addition, if the organic compound having a boron atom has the above-mentioned structure, the buffer layer formed of the organic compound also has an excellent function as an electron transport layer, and there is no need to provide an electron transport layer separately from the buffer layer.

Hereinafter, first, the boron-containing compound represented by the above formula (1) will be described, and then the boron-containing polymer obtained by polymerizing monomer components containing the boron-containing compound represented by the above formula (2) will be described. .

The boron-containing compound represented by the above formula (1) has the following various characteristics: (i) is a thermally stable compound; (ii) the energy levels of HOMO and LUMO are low; (iii) can make a good coating film, etc., It can be suitably used as a material of the first organic electroluminescent element of the present invention.

In the above-mentioned formula (1), the dotted line arc means that a part of the skeleton part connecting the boron atom and ^Q1 and the nitrogen atom or a part of the skeleton part connecting the boron atom and ^Q2 is formed with the skeleton part represented by the solid line. structure. This means: the compound represented by the above formula (1) has at least 4 ring structures in the structure, and the above formula (1) contains a skeleton part connecting a boron atom, ^Q1 and a nitrogen atom, and a skeleton connecting a boron atom and ^Q2 part as part of the ring structure. It should be noted that, in the ring structure to which ^X1 is bonded, the ring structure skeleton is composed of carbon atoms and does not contain atoms other than carbon atoms.

In the above formula (1), the skeleton part represented by the solid line, that is, the skeleton part connecting the boron atom and ^Q1 and the nitrogen atom, and the dotted line part in the skeleton part connecting the boron atom and ^Q2 are represented by dotted lines in the respective skeleton parts. The linked pair of atoms may be linked by a double bond.

In the above formula (1), an arrow pointing from a nitrogen atom to a boron atom indicates that the nitrogen atom is coordinated to the boron atom. Here, coordination means that the nitrogen atom acts on the boron atom like a ligand to exert a chemical influence, and may form a coordinate bond (covalent bond) or may not form a coordinate bond. Coordinate bond formation is preferred.

In the above formula (1), Q ¹ and Q ² are the same or different, they are linking groups in the skeleton part represented by the solid line, at least partially form a ring structure together with the dotted line arc part, and they have or do not have with substituents. This represents the incorporation of ^Q1 and ^Q2 respectively as part of the ring structure.

In the above formula (1), X ¹ , X ² , X ³ and X ⁴ are the same or different, and represent a hydrogen atom or a monovalent substituent as a substituent on the ring structure, and can be bonded to the ring structure forming the arc part of the dotted line There are two or more X ¹ , X ² , X ³ and X ⁴ . That is, when X ¹ , X ² , X ³ and X ⁴ are hydrogen atoms, in the structure of the compound represented by the above formula (1), four ring structures having X ¹ , X ² , X ³ and X ⁴ represent not Substituents; when any or all of X ¹ , X ² , X ³ and X ⁴ are monovalent substituents, any or all of the four ring structures have substituents. In this case, the number of substituents contained in one ring structure may be one or two or more.

In addition, the substituent in this specification refers to the group including the organic group which contains carbon, and the group which does not contain carbon, such as a halogen atom and a hydroxyl group.

In the above formula (1), n ¹ represents an integer of 2 to 10, and Y ¹ is a direct bond or an n ¹ -valent linking group. That is, in the compound represented by the above formula (1), Y ¹ is a direct bond, and it is ^{independently} bonded to the ring structure forming the arc portion of the dotted line, Q Any one of ¹ , Q ² , X ¹ , X ² , X ³ , X ⁴ ; or Y ¹ is an n ¹ -valent linking group, and there are 2 structural moieties other than Y ¹ in the above formula (1) Above, they are connected via ^Y1 as a linking group.

In the above-mentioned formula (1), when ^Y1 is a direct bond, the above-mentioned formula (1) represents: one of the two existing structural parts other than ^Y1 , the ring structure forming the dotted arc part, ^Q1 , Q ^2. The ring structure of any one of X ¹ , X ² , X ³ , X ⁴ and another structural part other than Y ¹ forming a dotted arc, Q ¹ , Q ² , X ¹ , X ² , Any one of X ³ and X ⁴ is directly bonded. The bonding position is not particularly limited, and it is preferred that the ring to which ^X1 or ^X2 of one of the structural parts other than Y1 is bonded is bonded to the ring to ^{which X1} of another structural part other than ^Y1 is bonded. The ring to which X2 is bonded or the ring to which ^X2 is bonded is directly bonded. More preferably, the ring to which ^X2 of one of the structural moieties other than ^Y1 is bonded is directly bonded to the ring to which ^X2 of the other structural moiety other than ^Y1 is bonded.

In this case, the structures of the two existing structural moieties other than ^Y1 may be the same or different.

In the above formula (1), when ^Y1 is an ^n1- valent linking group, and there are two or more structural moieties other than ^Y1 in the above formula (1), and they are connected via ^Y1 as a linking group, Such a structure in which two or more structural moieties other than Y ¹ exist in the above formula (1) are connected via Y ¹ as a linking group is more durable than a structure in which structural moieties other than Y ¹ are directly bonded. Oxidation also improves the film forming property, so it is more preferable.

It should be noted that when Y ¹ is an n ¹ -valent linking group, it is independently bonded to the existing n ¹ structural moieties other than Y ¹ in the ring structure forming the dotted arc portion, Q ¹ , Any one of Q ² , X ¹ , X ² , X ³ , X ⁴ , which refers to: the ring structure of the structure part other than Y ¹ forming the arc part of the dotted line, Q ¹ , Q ² , X ¹ , Any one of X ² , X ³ , and X ⁴ needs to be bonded to Y ¹ , and for the bonding sites to Y ¹ of structural parts other than Y ¹ , n ¹ existing ones other than Y ¹ The structural parts of each are independent, and all of them may be the same part, some of them may be the same part, or all of them may be different parts. There is no particular limitation on the bonding position, but it is preferable that all n ¹ structural moieties other than Y ¹ are bonded ^to Y 1 at the ring to which X ¹ is bonded or the ring to which X ² is bonded. It is more preferable that all n ¹ structural moieties other than Y ¹ are bonded to Y ¹ at the ring to which X ² is bonded.

In addition, the structures of n ¹ existing structural moieties other than Y ¹ may be all the same, some of them may be the same, or all of them may be different.

When ^Y in the above formula (1) is an ⁿ monovalent linking group, examples of the linking group include chain, branched or cyclic hydrocarbon groups with or without substituents; A heteroelement-containing group not having a substituent; an aryl group having a substituent or not; a heterocyclic group having a substituent or not. Among these, a group having an aromatic ring such as an aryl group which may have a substituent or a heterocyclic group which may have a substituent is preferable. That is, it is also one of the preferred embodiments of the present invention that Y ¹ in the above formula (1) is a group having an aromatic ring.

Furthermore, ^Y1 may be a linking group having a structure in which two or more of the above linking groups are combined.

As the chain, branched or cyclic hydrocarbon group, a group represented by any one of the following formulas (3-1) to (3-8) is preferable. Among these, the following formulas (3-1) and (3-7) are more preferable.

As the heteroelement-containing group, a group represented by any one of the following formulas (3-9) to (3-13) is preferable. Among these, the following formulas (3-12) and (3-13) are more preferable.

As the above-mentioned aryl group, a group represented by any one of the following formulas (3-14) to (3-20) is preferable. Among these, the following formulas (3-14) and (3-20) are more preferable.

As the heterocyclic group, a group represented by any one of the following formulas (3-21) to (3-27) is preferable. Among these, the following formulas (3-23) and (3-24) are more preferable.

[Chem 3]

Examples of the chain, branched or cyclic hydrocarbon group; heteroelement-containing group; aryl group; substituents of the heterocyclic group include halogen atoms; halogenated alkyl groups; those having 1 to 20 carbon atoms Straight-chain or branched-chain alkyl; cyclic alkyl with 5-7 carbon atoms; straight-chain or branched-chain alkoxy with 1-20 carbon atoms; nitro; cyano; Dialkylamino groups of alkyl groups with 1 to 10 atoms; diarylamino groups such as diphenylamino and carbazolyl groups; acyl groups; alkenyl groups with 2 to 30 carbon atoms; 2 to 30 carbon atoms Alkynyl; aryl substituted or unsubstituted by halogen atom, alkyl, alkoxy, alkenyl, alkynyl, etc.; substituted or unsubstituted by halogen atom, alkyl, alkoxy, alkenyl, alkynyl Substituted heterocyclyl; N,N-dialkylcarbamoyl; Dioxaborolanyl, stannyl, silyl, ester, formyl, thioether, epoxy groups, isocyanate groups, etc. It should be noted that these groups may be substituted by halogen atoms, hetero elements, alkyl groups, aromatic rings and the like.

Among these, as a chain, branched or cyclic hydrocarbon group; a heteroelement-containing group; an aryl group; a substituent of a heterocyclic group in ^Y1 , a halogen atom having 1 carbon atom is preferable. A linear or branched alkyl group of ∼20, a linear or branched alkoxy group having 1 to 20 carbon atoms, an aryl group, a heterocyclic group, or a diarylamino group. More preferred are alkyl groups, aryl groups, alkoxy groups, and diarylamino groups.

When the linear, branched or cyclic hydrocarbon group; heteroelement-containing group; aryl group; heterocyclic group in the above ^Y1 has a substituent, the position and number of substituents bonded are not particularly limited.

n ¹ in said formula (1) represents the integer of 2-10, Preferably it is 2-6. More preferably, it is an integer of 2-5, More preferably, it is an integer of 2-4, Especially preferably, it is 2 or 3 from the viewpoint of the solubility to a solvent. Most preferably 2. That is, the boron-containing compound represented by the above formula (1) is most preferably a dimer.

Examples of Q ¹ and Q ² in the above formula (1) include structures represented by the following formulas (4-1) to (4-8).

[chemical 4]

It should be noted that the above formula (4-2) is a structure in which 2 hydrogen atoms are bonded to a carbon atom and 3 atoms are bonded to a carbon atom, but the 3 atoms bonded to a carbon atom other than the hydrogen atom All are atoms other than hydrogen atoms. Among the above formulas (4-1) to (4-8), any one of (4-1), (4-7), and (4-8) is preferable. More preferred is (4-1). That is, Q ¹ and Q ² are the same or different and represent a linking group with 1 carbon atom, which is also one of the preferred embodiments of the present invention.

In the above formula (1), on the premise that the skeleton of the ring structure to which ^X1 is bonded is composed of carbon atoms, there is no ring structure formed by a dotted arc and a part of the skeleton part shown by a solid line as long as it is a ring structure special restrictions.

In the above formula (1), when Y ¹ is a direct bond and n ¹ is 2, the ring to which X ¹ is bonded includes, for example, a benzene ring, a naphthalene ring, an anthracene ring, a tetracene ring, and a pentacene ring. ring, benzo[9,10]phenanthrene ring, pyrene ring, fluorene ring, indene ring, thiophene ring, furan ring, pyrrole ring, benzothiophene ring, benzofuran ring, indole ring, dibenzothiophene ring, Dibenzofuran ring, carbazole ring, thiazole ring, benzothiazole ring, oxazole ring, benzoxazole ring, imidazole ring, pyrazole ring, benzimidazole ring, pyridine ring, pyrimidine ring, pyrazine ring, Pyridazine ring, quinoline ring, isoquinoline ring, quinoxaline ring, benzothiadiazole ring.

Among these, rings whose ring structure skeleton is composed of only carbon atoms are preferable, and benzene rings, naphthalene rings, anthracene rings, naphthacene rings, pentacene rings, benzo[9,10]phenanthrene rings, pyrene rings, Fluorene ring, indene ring. A benzene ring, a naphthalene ring, and a fluorene ring are more preferable, and a benzene ring is still more preferable.

In the above formula (1), when Y ¹ is a direct bond and n ¹ is 2, examples of rings to which X ² is bonded include rings represented by the following formulas (5-1) to (5-17): . It should be noted that the * marks in the following formulas (5-1) to (5-17) indicate that they constitute the ring to which X ¹ is bonded and constitute the connecting boron atom, Q ¹ and nitrogen in the above formula (1). A carbon atom of the atomic skeleton part is bonded to any one of the carbon atoms marked with *. In addition, it is possible to condense with other ring structures at positions other than carbon atoms marked with *. Among these, a pyridine ring, a pyrimidine ring, a quinoline ring, and a phenanthridine ring are preferable. More preferred are pyridine rings, pyrimidine rings, and quinoline rings. More preferably, it is a pyridine ring.

[chemical 5]

In addition, in the above formula (1), when ^Y1 is directly bonded and ⁿ¹ is 2, examples of the ring to which ^X3 is bonded and the ring to which ^X4 is bonded include those directly bonded to the above-mentioned ^Y1. And when n ¹ is 2, the ring to which X ¹ is bonded is the same ring. Among these, a benzene ring, a naphthalene ring, and a benzothiophene ring are preferable. More preferably, it is a benzene ring.

In the above formula (1), X ¹ , X ² , X ³ and X ⁴ are the same or different, and represent a hydrogen atom or a monovalent substituent as a substituent on a ring structure. There are no particular limitations on the monovalent substituent, and X ¹ , X ² , X ^{3 ,} and X ⁴ include, for example, a hydrogen atom, an aryl group with or without substituents, a heterocyclic group, an alkyl group, and an alkenyl group. , alkynyl, alkoxy, aryloxy, aralkoxy, silyl, hydroxyl, amino, halogen, carboxyl, mercapto, epoxy, acyl, oligomeric aryl with or without substituents ( oligoaryl), monovalent oligomeric heterocyclic group (Oligo ring group), alkylthio, arylthio, aralkyl, aralkyloxy, aralkylthio, azo, stannyl, phosphino , silyloxy, aryloxycarbonyl with or without substituent, alkoxycarbonyl with or without substituent, carbamoyl with or without substituent, arylcarbonyl with or without substituent, Alkylcarbonyl which may be substituted, arylsulfonyl which may be substituted, alkylsulfonyl which may be substituted, arylsulfinyl which may be substituted, arylsulfinyl which may be substituted, Alkylsulfinyl, formyl, cyano, nitro, arylsulfonyloxy, alkylsulfonyloxy with substituents; methanesulfonate, ethanesulfonate, trifluoromethanesulfonate Alkylsulfonate groups such as ester groups; Arylsulfonate groups such as benzenesulfonate groups and p-toluenesulfonate groups; Aralkylsulfonate groups such as benzylsulfonate groups, boryl groups , sulfonium methyl group, phosphonium methyl group, phosphonate methyl group, aryl sulfonate group, aldehyde group, acetonitrile group, etc.

Examples of the substituents for X ¹ , X ² , X ³ and X ⁴ above include halogen atoms; haloalkyl groups; straight-chain or branched-chain alkyl groups having 1 to 20 carbon atoms; and 5 carbon atoms. A cyclic alkyl group of ~7; a straight-chain or branched alkoxy group with a carbon number of 1 to 20; a hydroxyl group; a mercapto group; a nitro group; a cyano group; an amino group; an azo group; Monoalkylamino or dialkylamino of an alkyl group of 40; diphenylamino, carbazolyl and other amino groups; acyl groups; alkenyl groups with 2 to 20 carbon atoms; alkynyl groups with 2 to 20 carbon atoms ; alkenyloxy; alkynyloxy; aryloxy such as phenoxy, naphthyloxy, biphenyloxy, pyrenyloxy, etc.; perfluoroalkyl and longer chain perfluoroalkyl; boryl ; carbonyl; carbonyloxy; alkoxycarbonyl; sulfinyl; alkylsulfonyloxy; arylsulfonyloxy; phosphino; silyl; silyloxy; stannyl; , alkyl, alkoxy and other substituted or unsubstituted phenyl, 2,6-xylyl, mesityl, dul, biphenyl, terphenyl, naphthyl, anthracenyl, pyrenyl, toluene Aryl groups such as methoxybenzyl, fluorophenyl, diphenylaminophenyl, dimethylaminophenyl, diethylaminophenyl, phenanthrenyl; thienyl, furyl, silacyclopentadienyl, Oxazolyl, oxadiazolyl, thiazolyl, thiadiazolyl, acridinyl, quinolinyl, quinoxalinyl, phenanthrolinyl, benzothienyl, benzothiazolyl, indolyl, carba Azolyl, pyridyl, pyrrolyl, benzoxazolyl, pyrimidyl, imidazolyl and other heterocyclic groups; carboxyl; carboxylate; epoxy; isocyanate; cyanate; isocyanate; thiocyanate Ester group; Isothiocyanate group; Carbamoyl group; N,N-dialkylcarbamoyl group; Formyl group; Nitroso group; Formyloxy group; etc. It should be noted that these groups may be substituted by halogen atoms, alkyl groups, aryl groups, etc., and these groups may be bonded to each other at arbitrary positions to form a ring.

Among these, X ¹ , X ² , X ³ and X ⁴ are preferably hydrogen atoms; halogen atoms, carboxyl groups, hydroxyl groups, mercapto groups, epoxy groups, amino groups, azo groups, acyl groups, allyl groups, nitro groups, Reactive groups such as alkoxycarbonyl, formyl, cyano, silyl, stannyl, boryl, phosphino, siloxy, arylsulfonyloxy, alkylsulfonyloxy, etc. ; Straight-chain or branched-chain alkyl groups with 1-20 carbon atoms; Branched alkoxy, aryl, alkenyl with 2 to 8 carbon atoms, alkynyl with 2 to 8 carbon atoms or straight chain with 1 to 20 carbon atoms substituted by these reactive groups straight-chain or branched-chain alkyl; straight-chain or branched-chain alkoxy with 1 to 20 carbon atoms; straight-chain or branched-chain alkyl with 1 to 8 carbon atoms, 1 to 8 linear or branched alkoxy groups, aryl groups, alkenyl groups with 2 to 8 carbon atoms, alkynyl groups with 2 to 8 carbon atoms, or carbon atoms substituted by these reactive groups Straight-chain or branched-chain alkoxy groups with a number of 1 to 20; aryl groups; straight-chain or branched-chain alkyl groups with 1 to 8 carbon atoms, straight-chain chains with 1 to 8 carbon atoms Or branched alkoxy, aryl, alkenyl with 2 to 8 carbon atoms, alkynyl with 2 to 8 carbon atoms or aryl substituted by these reactive groups; oligomeric aryl; Straight-chain or branched-chain alkyl groups with 1-8 carbon atoms, straight-chain or branched-chain alkoxy groups with 1-8 carbon atoms, aryl groups, alkenes with 2-8 carbon atoms group, alkynyl group with 2 to 8 carbon atoms or oligomeric aryl group substituted by these reactive groups; monovalent heterocyclic group; linear or branched chain alkyl group with 1 to 8 carbon atoms, Straight-chain or branched alkoxy groups with 1 to 8 carbon atoms, aryl groups, alkenyl groups with 2 to 8 carbon atoms, alkynyl groups with 2 to 8 carbon atoms, or these reactive groups Substituted monovalent heterocyclic group; monovalent oligomeric heterocyclic group; linear or branched alkyl with 1 to 8 carbon atoms, linear or branched chain with 1 to 8 carbon atoms Alkoxy group, aryl group, alkenyl group with 2 to 8 carbon atoms, alkynyl group with 2 to 8 carbon atoms or monovalent oligomeric heterocyclic group substituted by these reactive groups; alkylthio group; aryl Oxygen group; arylthio group; aralkyl group; aralkyloxy group; aralkylthio group; alkenyl group; 8 linear or branched alkoxy groups, aryl groups, alkenyl groups with 2 to 8 carbon atoms, alkynyl groups with 2 to 8 carbon atoms, or alkenyl groups substituted by these reactive groups; Alkynyl; straight-chain or branched-chain alkyl with 1 to 8 carbon atoms, straight-chain or branched alkoxy with 1 to 8 carbon atoms, aryl, 2 to 8 carbon atoms 8 alkenyl groups, alkynyl groups having 2 to 8 carbon atoms, or alkynyl groups substituted by these reactive groups.

More preferably hydrogen atom, bromine atom, iodine atom, amino group, boryl group, alkynyl group, alkenyl group, formyl group, silyl group, stannyl group, phosphino group, aryl group substituted by these reactive groups group, oligomeric aryl group substituted by these reactive groups, monovalent heterocyclic group or monovalent heterocyclic group substituted by these reactive groups, monovalent oligomeric heterocyclic group substituted by these reactive groups , alkenyl or alkenyl substituted by these reactive groups, alkynyl or alkynyl substituted by these reactive groups. Among them, X ¹ and X ² are more preferably functional groups resistant to reduction such as hydrogen atoms, alkyl groups, aryl groups, nitrogen-containing heteroaryl groups, alkenyl groups, alkoxy groups, aryloxy groups, and silyl groups. Particularly preferred are hydrogen atoms, aryl groups, and nitrogen-containing heteroaryl groups. In addition, X ³ and X ⁴ are more preferably oxidation-resistant functional groups such as a hydrogen atom, carbazolyl, triphenylamino, thienyl, furyl, alkyl, aryl, and indolyl. Particularly preferred are a hydrogen atom, a carbazolyl group, a triphenylamino group, and a thienyl group. From this, it is considered that if X ¹ and X ² have reduction-resistant functional groups and X ³ and X ⁴ have oxidation-resistant functional groups, a boron-containing compound as a whole is further resistant to both reduction and oxidation.

It should be noted that in the above formula (1), when X ¹ , X ² , X ³ and X ⁴ are monovalent substituents, the binding positions of X ¹ , X ² , X ³ and X ⁴ to the ring structure, The number of bonds is not particularly limited.

In the above formula (1), when Y ¹ is an n ¹ -valent linking group and n ¹ is 2 to 10, as the ring to which X ¹ is bonded, it is directly bonded to Y ¹ in the above formula (1) and When n ¹ is 2, the ring to which X ¹ is bonded is the same. Among these rings, a benzene ring, a naphthalene ring, and a benzothiophene ring are preferable. More preferably, it is a benzene ring.

In the above formula (1), when Y ¹ is a linking group with n ¹ valency and n ¹ is 2 to 10, the ring to which X ² is bonded, the ring to which X ³ is bonded, and the ring to which X ⁴ is bonded , are the same as the rings listed as the ring to which X ² is bonded, the ring to which X ³ is ^bonded , and the ring to which X ⁴ is bonded when Y ¹ is a direct bond and n 1 is 2 in the above formula (1), respectively , and the preferred structure is also the same.

That is, when Y ¹ in the above formula (1) is a direct bond and n ¹ is 2, and when Y ¹ is an n ¹ -valent linking group and n ¹ is 2 to 10, the above formula It is also one of the preferred embodiments of the present invention that the boron-containing compound represented by (1) is a boron-containing compound represented by the following formula (6).

[chemical 6]

(In the formula, the arrow pointing from the nitrogen atom to the boron atom, X ¹ , X ² , X ³ , X ⁴ , n ¹ and Y ¹ are the same as the formula (1))

The boron-containing compound represented by the above formula (1) can be synthesized by using various common reactions such as Suzuki coupling reaction. In addition, it can also be synthesized by the method described in Journal of the American Chemical Society, 2009, volume 131, number 40, pages 14549-14559.

An example of the synthesis scheme of the boron-containing compound represented by the above formula (1) is shown in the following reaction formula. The following reaction formula (I) represents an example of a synthesis scheme of a boron-containing compound in which Y represented by the above formula ( ¹ ) is directly bonded and n is ² , and the following reaction formula (II) represents a compound obtained by the above formula ( 1) An example of a synthesis scheme of a boron-containing compound in which Y ¹ is an n ¹ -valent linking group and n ¹ is 2 to 10. However, the method for producing the boron-containing compound represented by the above formula (1) is not limited thereto.

It should be noted that, in the following schemes, the compound (a) as a raw material can be synthesized by, for example, the method described in Journal of Organic Chemistry, 2010, Vol. 75, No. 24, pages 8709-8712. In addition, the (b) compound as a raw material can be synthesized by subjecting the (a) compound to a borylation reaction represented by the following reaction formula (III).

[chemical 7]

[chemical 8]

[chemical 9]

Next, a boron-containing polymer obtained by polymerizing a monomer component containing a boron-containing compound represented by the above formula (2) will be described.

In the above formula (2), the dotted arc indicates that a ring structure is formed together with a part of the skeleton part connecting the boron atom and the nitrogen atom. That is, the boron-containing compound represented by the above-mentioned formula (2) has at least two ring structures in its structure, and the above-mentioned formula (2) contains a skeleton part connecting a boron atom and a nitrogen atom as a part of the ring structure.

In the above formula (2), the dotted line part in the skeleton part connecting the boron atom and the nitrogen atom indicates that at least one pair of atoms is connected by a double bond, indicating that the double bond can form a conjugated ring structure. Among the compounds represented by the formula (1), examples of the conjugated double bond and the ring structure include compounds having structures such as the following formulas (7-1) to (7-4).

[chemical 10]

In the above formula (2), the arrow pointing from the nitrogen atom to the boron atom indicates that the nitrogen atom is coordinated to the boron atom. Coordinated means the same as the nitrogen atom coordinated to the boron atom in the above formula (1).

In the above formula (2), X ⁵ and X ⁶ are the same or different, and represent a hydrogen atom or a monovalent substituent as a substituent on the ring structure, and two or more X ⁵ may be bonded to the ring structure forming the arc portion of the dotted line and ^x6 . That is, when X ⁵ and X ⁶ are hydrogen atoms, it means that the two ring structures having X ⁵ and X ⁶ in the structure of the boron-containing compound represented by formula (2) do not have substituents; X ⁵ and/or X ⁶ are In the case of a monovalent substituent, one of these two ring structures has a substituent or both have a substituent. In this case, the number of substituents contained in one ring structure may be one or two or more.

In the above formula (2), R ¹ and R ² are the same or different, and represent a hydrogen atom or a monovalent substituent. The R ¹ and R ² may be the same or different, preferably both are the same. The ^R and ^R are not particularly limited, and include, for example, a hydrogen atom, an aryl group with or without a substituent, a heterocyclic group, an alkyl group, an alkoxy group, an aralkyloxy group, a silyl group, a hydroxyl group, Boroxyl group, amino group, halogen atom, 2,2'-biphenyl group formed by bonding ^R1 and ^R2 , oligomeric aryl group with or without substituent, monovalent oligomeric heterocyclic group, Alkylthio, arylthio, aralkyl, aralkoxy, aralkylthio, azo, stannyl, phosphino, siloxy, arylsulfonyloxy, alkylsulfonyl Oxygen group; Alkylsulfonate group; Arylsulfonate group; Formulas (8-5) to (8-6) represent groups such as sulfonium methyl groups; groups represented by following formula (8-7) such as phosphonium methyl groups; groups represented by following formula (8-8) phosphonate methyl group; arylsulfonate group; aldehyde group; acetonitrile group; magnesium halide represented by the following formula (8-9), etc.

In addition, in the formula, Me represents a methyl group. Et represents ethyl. X represents a halogen atom. R' represents an alkyl group, an aryl group or an aralkyl group.

[chemical 11]

Examples of the aryl group include phenyl, biphenyl, naphthyl, tetrahydronaphthyl, indenyl, indanyl and the like. Among these, phenyl, biphenyl, and naphthyl are preferable.

Examples of the heterocyclic group include pyrrolyl, pyridyl, quinolinyl, piperidyl, piperidyl, furyl, thienyl and the like. Among these, pyridyl and thienyl are preferable.

Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and among these, a bromine atom and an iodine atom are preferable.

Examples of the alkyl group include linear or branched hydrocarbon groups having 1 to 30 carbon atoms and alicyclic hydrocarbon groups having 3 to 30 carbon atoms. That is, for the first organic electroluminescent element of the present invention, the following method is also one of the preferred embodiments of the present invention: the buffer layer is made of a monomer component containing a boron-containing compound represented by the above formula (2) And the obtained boron-containing polymer is formed, and in the boron-containing compound represented by formula (2), R ¹ and R ² are the same or different, and represent a straight-chain or branched-chain hydrocarbon group or carbon with 1 to 30 carbon atoms. An alicyclic hydrocarbon group having 3 to 30 atoms.

As the alkyl group, among the above, methyl, ethyl, isopropyl, isobutyl, and octyl are preferable. More preferred are methyl, ethyl, isobutyl and octyl.

Examples of the substituents in the above R ¹ and R ² include the same substituents as those in X ¹ to X ⁴ in the above formula (1).

Among these, as the substituents of the monovalent substituents in ^R1 and ^R2 above, a halogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, and a carbon number of 1 to 8 linear or branched alkoxy groups, aryl groups, and haloalkyl groups. More preferred are ethyl group, isopropyl group, octyl group, fluorine atom, bromine atom, vinyl group, ethynyl group, diphenylamino group, diphenylaminophenyl group, and trifluoromethyl group.

As the above-mentioned R ¹ and R ² , among the above-mentioned groups, hydrogen atom, bromine atom, methyl group, ethyl group, isopropyl group, isobutyl group, n-octyl group, phenyl group, 4-methoxy group are more preferable. Phenyl, 4-trifluoromethylphenyl, pentafluorophenyl, 4-bromophenyl, 2,2'-biphenyl, styryl, diphenylaminophenyl. More preferably bromine atom, methyl, ethyl, isopropyl, isobutyl, n-octyl, phenyl, 4-methoxyphenyl, 4-trifluoromethylphenyl, pentafluorophenyl, 4 -Bromophenyl, 2,2'-biphenyl, styryl, diphenylaminophenyl, particularly preferably bromine, isopropyl, isobutyl, n-octyl, phenyl, 4-triphenyl Fluoromethylphenyl, pentafluorophenyl, 4-bromophenyl, 2,2'-biphenyl, styryl, diphenylaminophenyl.

In the above formula (2), X ⁵ and X ⁶ are the same or different, and represent a hydrogen atom or a monovalent substituent as a substituent on a ring structure. The monovalent substituent is not particularly limited, and examples thereof include the same groups as those described above for R ¹ and R ² .

Among these, ^X5 and ^X6 are preferably hydrogen atom; halogen atom, carboxyl group, hydroxyl group, mercapto group, epoxy group, isocyanate group, amino group, azo group, acyl group, allyl group, nitro group, alkoxycarbonyl group , formyl, cyano, silyl, stannyl, boryl, phosphino, siloxy, arylsulfonyloxy, alkylsulfonyloxy and other reactive groups; number of carbon atoms A linear or branched alkyl group of 1 to 4 or a linear or branched alkyl group with 1 to 4 carbon atoms substituted by these reactive groups; a straight chain or branched alkyl group with a carbon number of 1 to 8 Chain or branched alkoxy groups or linear or branched alkoxy groups with 1 to 8 carbon atoms substituted by these reactive groups; aryl groups or aryl groups substituted by these reactive groups oligomeric aryl group or oligomeric aryl group substituted by these reactive groups; monovalent heterocyclic group or monovalent heterocyclic group substituted by these reactive groups; monovalent oligomeric heterocyclic group or substituted by these reactive groups Alkylthio; Aryloxy; Arylthio; Aralkyl; Aralkyloxy; Aralkylthio; Alkenyl or substituted by these reactive groups alkenyl; alkynyl or alkynyl substituted by these reactive groups. More preferably a hydrogen atom, a bromine atom, an iodine atom, a boryl group, an alkynyl group, an alkenyl group, a formyl group, a stannyl group, a phosphino group, an aryl group or an aryl group substituted by these reactive groups, Monovalent heterocyclic groups such as oligomeric aryl groups substituted by these reactive groups, amino groups such as diphenylamino groups, groups represented by the following formula (8-10), or monovalent heterocyclic groups substituted by these reactive groups A group, a monovalent oligomeric heterocyclic group substituted by these reactive groups, an alkenyl group or an alkenyl group substituted by these reactive groups, an alkynyl group or an alkynyl group substituted by these reactive groups.

[chemical 12]

At least one of X ⁵ , X ⁶ , R ¹ and R ² in the above formula (2) is a substituent having a reactive group. The substituent having a reactive group is preferably a halogen atom, carboxyl group, hydroxyl group, mercapto group, epoxy group, isocyanate group, amino group, azo group, acyl group, allyl group, nitro group, alkoxycarbonyl group, formyl group, Reactive groups such as cyano, silyl, stannyl, boryl, phosphino, siloxy, arylsulfonyloxy, alkylsulfonyloxy; these reactive groups Substituted straight-chain or branched-chain alkyl groups with 1 to 4 carbon atoms; straight-chain or branched-chain alkoxy groups with 1 to 8 carbon atoms substituted by these reactive groups; Aryl groups substituted by reactive groups; oligomeric aryl groups substituted by these reactive groups; monovalent heterocyclic groups substituted by these reactive groups; monovalent oligomeric heterocyclic groups substituted by these reactive groups ; alkenyl or alkenyl substituted by these reactive groups; alkynyl or alkynyl substituted by these reactive groups. More preferably bromine atom, iodine atom, boryl group, formyl group, stannyl group, phosphino group, aryl group substituted by these reactive groups, oligomeric aryl group substituted by these reactive groups, aryl group substituted by these reactive groups, Monovalent heterocyclic group substituted by these reactive groups, monovalent oligomeric heterocyclic group substituted by these reactive groups, alkenyl or alkenyl, alkynyl substituted by these reactive groups or substituted by these reactive groups Reactive group substituted alkynyl. More preferably bromine atom, boryl group, formyl group, stannyl group, phosphino group, aryl group substituted by these reactive groups, oligomeric aryl group substituted by these reactive groups, oligomeric aryl group substituted by these reactive groups, Group substituted monovalent heterocyclic group, monovalent oligomeric heterocyclic group substituted by these reactive groups, alkenyl or alkenyl, alkynyl substituted by these reactive groups, or substituted by these reactive groups Group substituted alkynyl.

When two of the above-mentioned X ⁵ , X ⁶ , R ¹ and R ² are substituents having reactive groups, the reactive groups of the two substituents are different to form a Boron-containing compounds are independently polycondensed in the form of a combination of reactive groups; or contain two or more boron-containing compounds represented by formula (2) so as to have a combination of reactive groups capable of copolymerizing these boron-containing compounds or have a combination of reactive groups capable of copolymerizing one or more boron-containing compounds represented by formula (2) with other compounds having at least one reactive group, thus being suitable for use in polymerization The raw material of things.

In the above formula (2), examples of the ring to which ^X5 is bonded include a benzene ring, a thiophene ring, a benzothiophene ring, a thiazole ring, an oxazole ring, a naphthalene ring, an anthracene ring, a tetracene ring, and a Five phenyl rings, imidazole rings, pyrazole rings, pyridine rings, pyridazine rings, pyrazine rings, pyrimidine rings, quinoline rings, and isoquinoline rings, which are represented by the following formulas (9-1) to (9-17) express. Among these, a benzene ring, a naphthalene ring, and a benzothiophene ring are preferable.

[chemical 13]

In addition, in the above-mentioned formula (2), as the ring to which ^X6 is bonded, for example, pyrrole ring, pyrazole ring, imidazole ring, pyridine ring, pyridazine ring, pyrazine ring, pyrimidine ring, indole ring, Isoindole ring, quinoline ring, isoquinoline ring, phenanthridine ring, thiazole ring, oxazole ring. These are represented by the following formulas (10-1) to (10-14), respectively. Among these, a pyridine ring, a pyrimidine ring, a quinoline ring, and a phenanthridine ring are preferable. More preferred are pyridine rings, pyrimidine rings, and quinoline rings.

[chemical 14]

In the boron-containing compound represented by the above formula (2), when X ⁵ and/or X ⁶ are monovalent substituents, the bonding position and the number of bonding of X ⁵ and/or X ⁶ to the ring structure are not particularly special. limit.

In addition, the following method is also one of the preferred embodiments of the present invention: at least two monovalent substituents are bonded to the ring structure as X ⁵ , and one of the monovalent substituents is methyl boron with or without substituents. An alkyl group, the other of the monovalent substituents is a pyridyl group which may or may not have a substituent, and the nitrogen atom of the pyridyl group is coordinated to the boron atom of the boryl group. That is, it is also one of the preferred embodiments of the present invention that, in the boron-containing compound represented by the above formula (2), there are two or more moieties in which the nitrogen atom is coordinated to the boron atom in the structure.

In the present invention, the following mode is also one of the preferred embodiments of the present invention: in the above-mentioned formula (2), at least one of ^X5 and ^X6 is a substituent having the following structure: having 2 atoms at the terminal A bond-linked structure is bonded to a ring structure forming a dotted-line arc portion via one of the two atoms. That is, the following mode is also one of the preferred embodiments of the present invention: the organic compound having a boron atom forming the buffer layer of the organic electroluminescent element is a boron-containing polymer, and the monomer component as the raw material of the boron-containing polymer is The boron-containing compound contained is a boron-containing compound having a boron atom and a double bond, and is characterized in that the boron-containing compound is represented by the following formula (2):

[chemical 15]

(In the above formula, the dotted arc indicates that a ring structure is formed with a part of the skeleton part connecting the boron atom and the nitrogen atom. The dotted line part in the skeleton part connecting the boron atom and the nitrogen atom represents that at least one pair of atoms is connected by a double bond, and the The double bond can form a conjugation with the ring structure. The arrow pointing from the nitrogen atom to the boron atom indicates that the nitrogen atom is coordinated to the boron atom. ^X5 and ^X6 are the same or different and represent a hydrogen atom or a monovalent substituent as a substituent on the ring structure , two or more X ⁵ and X ⁶ may be bonded to the ring structure forming the dotted arc part. R ¹ and R ² are the same or different, and represent a hydrogen atom or a monovalent substituent), and at least one of the above X ⁵ and X ⁶ One of them has a structure in which two atoms are connected by a double bond at the terminal, and one of the two atoms is bonded to a ring structure forming a dotted-line arc portion.

The above-mentioned structure having a structure in which two atoms are connected by a double bond at the end and one of the two atoms is bonded to the ring structure forming the arc portion of the dotted line means that, in the constitution of ^X5 and/or X Among the atomic groups of ⁶ , there are at least two terminal portions of each structure, and among the terminal portions, the terminal portion bonded to the ring structure forming the dotted-line arc portion in the above formula (2) has the following structure: The atom to which the ring structure of the arc portion is bonded is connected to the adjacent atom of the atom by a double bond. Examples of such substituents include structures represented by the following formulas (11-1) to (11-2).

In addition, in formula (11-1)-(11-2), * represents the atom bonded to the ring structure which forms the dotted-line arc part in formula (2). r ¹ , r ² , r ³ and r ⁴ are the same or different, and represent atoms capable of forming double bonds between r ¹ and r ² and between r ³ and r ⁴ , respectively. In formula (11-1), q ¹ represents a hydrogen atom or a monovalent organic group, and indicates that two or more q ¹ may be bonded to r ² corresponding to the atomic valence of r ² . In formula (11-2), the dotted arc indicates that a ring structure is formed together with the double bond moiety formed by ^r3 and ^r4 . q ² represents a hydrogen atom or a monovalent substituent as a substituent on the ring structure, and indicates that two or more q ² may be bonded to the ring structure forming the dotted arc in the formula (11-2).

[chemical 16]

In the above formulas (11-1) to (11-2), r ¹ , r ² , r ³ and r ⁴ are the same or different, indicating that they can be formed between r ¹ and r ² and between r ³ and r ⁴ respectively. The atom of the double bond is preferably a carbon atom, a nitrogen atom, a phosphorus atom, or a sulfur atom. More preferably, it is a carbon atom or a nitrogen atom.

In the above formula (11-1), q ¹ represents a hydrogen atom or a monovalent organic group, and represents that two or more q ¹ may be bonded to r ² corresponding to the atomic valence of r ² , which means, for example, When r ² is a nitrogen atom, one q ¹ is bonded to r ² ; when r ² is a carbon atom, two q ^1s are bonded to r ² . When two or more q ^1s are bonded to r ² , all q ^1s may be the same or different. The monovalent organic group is not particularly limited, and examples thereof include the same groups as R ¹ and R ² in the above formula (2).

Among these, ^q1 is preferably a hydrogen atom; a halogen atom, a carboxyl group, a hydroxyl group, a mercapto group, an epoxy group, an isocyanate group, an amino group, an azo group, an acyl group, an allyl group, a nitro group, an alkoxycarbonyl group, or a formyl group. , cyano, silyl, stannyl, boryl, phosphino, siloxy, arylsulfonyloxy, alkylsulfonyloxy and other reactive groups; the number of carbon atoms is 1 ~4 straight-chain or branched-chain alkyl groups or straight-chain or branched-chain alkyl groups with 1-4 carbon atoms substituted by these reactive groups; straight-chain or branched-chain alkyl groups with 1-8 carbon atoms Or a branched alkoxy group or a straight-chain or branched alkoxy group with 1 to 8 carbon atoms substituted by these reactive groups; an aryl group or an aryl group substituted by these reactive groups; low A polyaryl group or an oligomeric aryl group substituted by these reactive groups; a monovalent heterocyclic group or a monovalent heterocyclic group substituted by these reactive groups; a monovalent oligomeric heterocyclic group or a monovalent heterocyclic group substituted by these reactive groups Alkylthio; Aryloxy; Arylthio; Aralkyl; Aralkyloxy; Aralkylthio; Alkenyl or a chain substituted by these reactive groups alkenyl; alkynyl or alkynyl substituted by these reactive groups. More preferably hydrogen atom, bromine atom, iodine atom, boryl group, alkynyl group, alkenyl group, formyl group, stannyl group, phosphinoyl group, aryl group or aryl group substituted by these reactive groups, substituted by The oligomeric aryl group substituted by these reactive groups, the monovalent heterocyclic group substituted by these reactive groups, the monovalent oligomeric heterocyclic group substituted by these reactive groups, alkenyl or the oligomeric heterocyclic group substituted by these reactive groups Group substituted alkenyl, alkynyl or alkynyl substituted by these reactive groups.

In the above formula (11-2), ^q represents a hydrogen atom or a monovalent substituent as a substituent on the ring structure, which means that the ring structure forming the dotted arc portion in the formula (11-2) may also be bonded with 2 or more q ² .

That is, when ^q2 is a hydrogen atom, it means that the ring structure having ^q2 in the structure represented by formula (11-2) has no substituent; when ^q2 is a monovalent substituent, the ring structure has a substituent. In this case, the number of substituents that the ring structure has may be one or two or more.

Examples of the above-mentioned monovalent substituent include the same groups as ^X5 and ^X6 in the above-mentioned formula (2), and among them, groups represented by the above-mentioned formula (8-10), naphthyl , phenyl.

In the present invention, in addition, the following mode is also one of the preferred embodiments of the present invention: ^X5 and ^X6 in the above-mentioned formula (2) both have a structure having two atoms connected by a double bond at the end, and through this A substituent having a structure in which one of the two atoms is bonded to the ring structure forming the arc portion of the dotted line. That is, the following mode is also one of the preferred embodiments of the present invention: the organic compound having a boron atom forming the buffer layer of the organic electroluminescence element is a boron-containing polymer, and the monomer component contained as a raw material of the boron-containing polymer The boron-containing compound is a boron-containing compound having a boron atom and a double bond, and is characterized in that the boron-containing compound is represented by the following formula (2):

[chemical 17]

(In the formula, the dotted line arc indicates that a ring structure is formed together with a part of the skeleton part connecting the boron atom and the nitrogen atom. The dotted line part in the skeleton part connecting the boron atom and the nitrogen atom represents that at least one pair of atoms is connected by a double bond, and the double bond The bond can form a conjugation with the ring structure. The arrow pointing from the nitrogen atom to the boron atom indicates that the nitrogen atom is coordinated to the boron atom. ^X5 and ^X6 are the same or different, indicating a monovalent substituent as a substituent on the ring structure, forming a dotted circle There may be more than 2 monovalent substituents bonded to the ring structure of the arc part. ^R1 and ^R2 are the same or different, representing a hydrogen atom or a monovalent substituent), and the above-mentioned ^X5 and ^X6 all have the following structure: at the end The moiety has a structure in which two atoms are connected by a double bond, and one of the two atoms is bonded to the ring structure forming the dotted arc portion.

In the above formula (2), both ^X5 and ^X6 have a structure in which two atoms are connected by a double bond at the end, and one of the two atoms is bonded to the ring structure forming the arc portion of the dotted line. The boron-containing compound of structure generally can enumerate: the mode that the above-mentioned double bond part that forms the ring structure bonding atom that forms dotted line arc part in above-mentioned formula (2) does not constitute the mode of ring structure; And above-mentioned formula (2) ) in which the above-mentioned double bond portion constituted by atoms bonded to the ring structure forming the dotted arc portion constitutes a part of the ring structure, specifically, the following formulas (2'-1) to (2'- 4) way.

It should be noted that, in the formulas (2'-1) to (2'-4), the dotted line part in the skeleton part connecting the boron atom and the nitrogen atom, the arrow pointing from the nitrogen atom to the boron atom, and ^R1 and ^R2 and Equation (1) is the same. In the formula (2'-1), the dotted arc is the same as that of the formula (2). In the formulas (2'-2) to (2'-4), the dotted arc connected to a part of the skeleton part connecting the boron atom and the nitrogen atom represents the same as the formula (2) that connects the boron atom and the nitrogen atom. A part of the backbone part forms a ring structure together, and in addition, the dotted arc connected to the double bond part formed by ^r5 and ^r6 and/or the double bond part formed by ^r7 and ^r8 indicates that the corresponding double bond part Together they form a ring structure. r ⁵ to r ⁸ are the same or different, and are the same as r ¹ to r ⁴ in the above formulas (11-1) to (11-2). q ³ and q ⁴ are the same or different, and are the same as q ¹ in the above formula (11-1). q ⁵ and q ⁶ are the same or different, and are the same as q ² in the above formula (11-2). Wherein, when the boron-containing compound is a compound of formula (2'-4), at least one of q ⁵ and q ⁶ is a substituent having a reactive group.

[chemical 18]

Among these forms, it is preferable that none of the double bond moieties formed by the atoms bonded to the ring structure forming the dotted arc portion in the above formula (2) constitute a ring structure or all constitute a part of the ring structure. A sort of. That is, the forms of the above formulas (2'-1) and (2'-4) are preferable.

Such an organic compound having a boron atom forming a buffer layer of an organic electroluminescent element will contain a boron-containing compound represented by the above formula (2'-1) or a boron-containing compound represented by the above formula (2'-4). A boron-containing polymer obtained by polymerizing the monomer components of the compound is also one of the preferred embodiments of the present invention.

In the above formula (2'-1), the dotted line arc represents the same as the formula (1) to form a ring structure together with a part of the skeleton part connecting the boron atom and the nitrogen atom. In the above formula (2'-1), the dotted line The ring structure formed by the arc and a part of the skeleton part connecting the boron atom and the nitrogen atom is not particularly limited as long as it is a ring structure. As the ring to which the group having ^q3 in the formula (2'-1) is bonded, Examples thereof include the same rings as those to which X ⁵ in formula (2) is bonded. In addition, examples of the ring to which the group having q ⁴ in formula (2′-1) is bonded include the same rings as the ring to which X ⁶ in formula (2) is bonded.

In the above formulas (2'-2) to (2'-4), the dotted arc connected to a part of the skeleton part connecting the boron atom and the nitrogen atom represents the same as the formula (2) that connects the boron atom and the nitrogen atom. Parts of the backbone moieties together form a ring structure, and the dotted arc connecting the double bond portion formed by r ⁵ and r ⁶ and/or the double bond portion formed by r ⁷ and r ⁸ indicates that the corresponding double bond The parts together form a ring structure. That is, the boron-containing compound represented by the above formulas (2'-2) to (2'-3) means that it has at least three ring structures in the structure, and contains a skeleton part connecting a boron atom and a nitrogen atom and a double bond part as part of the ring structure. In addition, the boron-containing compound represented by the above-mentioned formula (2'-4) means that it has at least four ring structures in its structure, and includes a skeleton part connecting boron atom and nitrogen atom and two double bond parts as part of the ring structure.

In the above formulas (2'-2) to (2'-4), the dotted line arc connected to a part of the skeleton part connecting the boron atom and the nitrogen atom, and a part of the skeleton part connecting the boron atom and the nitrogen atom The formed ring structure is not particularly limited as long as it is a ring structure, and the ring bonded to the group containing the double bond portion formed by ^r5 and ^r6 includes the one bonded to ^X5 in the formula (2). The combined rings are the same rings. In addition, examples of the ring to which a group including a double bond portion formed by r ⁷ and r ⁸ is bonded include the same rings as the ring to which X ⁶ in formula (2) is bonded.

In addition, in the above formulas (2'-2) to (2'-4), as the double bond part formed by r5 ^{and r6} and/or the double bond part formed by ^r7 and ^r8 is connected The ring structure formed by the dotted arc and the corresponding double bond moiety, for example, the same ring as the ring to which ^X5 in the formula (2) is bonded and the ring to which ^X6 in the formula (2) is bonded . It should be noted that, in the above formula (2'-4), the dotted line arc connected with the double bond part formed by ^r5 and ^r6 and the double bond part formed by ^r7 and ^r8 and the double bond There are at least two partially formed ring structures, and they may be the same or different.

The method for producing the boron-containing compound represented by the above formula (2) is not particularly limited, and it can be produced, for example, by the method described in JP-A-2011-184430.

A boron-containing polymer obtained by polymerizing a monomer component containing a boron-containing compound represented by the above formula (2) has repeating units consisting of X ⁵ , X ⁶ , R ¹ and A repeating unit formed by polycondensation of at least 2 groups in R ² or polymerization of at least 1 group. That is, it is a boron-containing polymer having a repeating unit structure represented by the following formula (12),

[chemical 19]

(In the formula, the dotted line arc, the dotted line part in the skeleton part connecting the boron atom and the nitrogen atom, the arrow pointing to the boron atom from the nitrogen atom are the same as the formula (2). X ⁵ ', X ⁶ ', R ¹ ' and R ² ' are the same groups as X ⁵ , X ⁶ , R ¹ and R ² in the formula (2), respectively, and represent a divalent group, a trivalent group or a direct bond). The above formula (12) means that at least one of X ⁵ ′, X ⁶ ′, R ¹ ′, and R ^{2 ′} forms a bond as a part of the main chain of the polymer. When at least two groups of X ⁵ , X ⁶ , R ¹ and R ² in the above formula (2) are polycondensed to form a boron-containing polymer, X ⁵ ′, X ⁶ ′, R in the above formula (12) At least two of ¹ ' and R ² ' are divalent groups or direct bonds. When at least one of X ⁵ , X ⁶ , R ¹ and R ² in the above formula (2) is polymerized alone to form a boron-containing polymer, X ⁵ ′, X 6 ′, X ⁶ ′, At least one of R ^{1 ′} and R ² ′ is a trivalent group or a direct bond.

The boron-containing polymer having a repeating unit represented by the above formula (12) may consist of one structure represented by the above formula (12), or may contain two or more structures represented by the above formula (12). When two or more structures represented by the above formula (12) are contained, the two or more structures may be random polymers, block polymers, or graft polymers. In addition, it may be a case where the main chain of the polymer has branches to have three or more terminal parts, or a dendrimer.

Among the boron-containing polymers having a repeating unit structure represented by the above formula (12), R ¹ ' and R ² ' in the above formula (12) are preferably the same as R ¹ and R ² in the formula (2), respectively same group. Furthermore, R ^{1 ′} and R ² ′ in the above formula (12) are more preferably a linear or branched hydrocarbon group having 1 to 30 carbon atoms, or an alicyclic hydrocarbon group having 3 to 30 carbon atoms.

That is, the following method is also one of the preferred embodiments of the present invention: the organic compound having a boron atom forming the buffer layer of the organic electroluminescent element is obtained by polymerizing a monomer component containing a boron-containing compound represented by formula (2). The obtained boron-containing polymer, wherein ^R1 and ^R2 in the formula (2) are the same or different, and represent a linear or branched hydrocarbon group with 1 to 30 carbon atoms or a hydrocarbon group with 3 to 30 carbon atoms. Alicyclic hydrocarbon group.

Among specific examples of the structure of the repeating unit represented by the above formula (12), structures obtained by polycondensation include structures such as the following formulas (13-1) to (13-6). Among these, the structures of (13-1) and (13-6) are preferable. The structure of (13-1) is more preferable. That is, a boron-containing polymer obtained from a boron-containing compound having a structure represented by formula (2) in which X ⁵ and X ⁶ are substituents having reactive groups is also one of the present invention.

[Chem. 20-1]

[Chem. 20-2]

[Chem. 20-3]

The combination of the above-mentioned reactive groups that can be polycondensed is not particularly limited as long as it can be polymerized, and examples include carboxyl and hydroxyl, carboxyl and mercapto, carboxyl and amino, carboxylate and amino, carboxyl and epoxy, hydroxyl and Epoxy group, mercapto group and epoxy group, amino group and epoxy group, isocyanate group and hydroxyl group, isocyanate group and mercapto group, isocyanate group and amino group, hydroxyl group and halogen atom, mercapto group and halogen atom, boryl group and halogen atom, formazan Stannyl and halogen atom, aldehyde group and phosphonium methyl group, vinyl group and halogen atom, aldehyde group and phosphonate methyl group, haloalkyl group and haloalkyl group, sulfonium methyl group and sulfonium methyl group, aldehyde group and acetonitrile group, Aldehyde group and aldehyde group, halogen atom and boryl group, halogen atom and magnesium halide, halogen atom and halogen atom, etc.

Among these, a combination of a halogen atom and a boryl group, and a combination of a halogen atom and a halogen atom are preferable.

When at least two groups of X ⁵ , X ⁶ , R ¹ and R ² in the above formula (2) are polycondensed to form a boron-containing polymer, X ⁵ ′, X ⁶ ′, R in the above formula (12) At least two of ^{1 ′} and R ² ′ represent a divalent group representing a residue not detached by a polycondensation reaction between substituents having a reactive group, or a direct bond. When a substituent having a reactive group that forms a combination of the above-mentioned polycondensable reactive groups undergoes a polycondensation reaction, there are cases where residues remain in the polymer and cases where no residues remain, and in the former case , at least one of X ⁵ ′, X ⁶ ′, R ¹ ′ and R ² ′ represents a residue that has not been detached from the polycondensation reaction between substituents having reactive groups, and in the case of the latter, X ⁵ ′ At least one of , X ⁶ ′, R ¹ ′, and R ^{2 ′} represents a direct bond.

In addition, when two or more repeating units represented by the above formula (12) are continuous, for example, X ⁵ ', X ⁶ ', R ¹ such as -X ⁵ '-X ⁶ '- are formed between the two repeating units ' and R ² ', in which case either of the two is a direct bond.

As specific examples of the case where a substituent having a reactive group that forms a combination of the above-mentioned polycondensable reactive groups undergoes a polycondensation reaction and leaves a residue in the polymer, a substituent having a carboxyl group and a substituent having a carboxyl group can be mentioned. Combinations of substituents for hydroxyl groups. For example, when a -CH ₂ COOH group and a -CH ₂ CH ₂ OH group undergo a polycondensation reaction, the residue remaining in the polymer is a -CH ₂ (CO)-O-CH ₂ CH ₂ - group. In addition, for example, when the substituent having a reactive group is composed of only the reactive group like the reaction between the -COOH group and the -OH group, the residue remaining in the polymer is -(CO)-O -base.

Specific examples of the case where no residue remains in the polymer after the polycondensation reaction of the combination of the above polycondensable reactive groups include a boryl group and a halogen atom, or a combination of a halogen atom and a halogen atom.

Among specific examples of the structure of the repeating unit represented by the above formula (12), as a structure obtained by independently polymerizing at least one group of X ⁵ , X ⁶ , R ¹ and R ² in the above formula (2), For example, the structure obtained by polymerizing X ⁶ is a structure like the following formula (14). In this way, when X ⁶ in the formula (2) is a substituent having a reactive group that can be independently polymerized in the structure, X 6 ′ is a repeating unit of a structure in which X ⁶ ' is a trivalent group or a direct bond. Similarly, when any one of X ⁵ , X ⁶ , R ¹ or R ² in formula (2) is a substituent having a reactive group capable of independent polymerization in the structure, X ⁵ ′, X ⁶ ′ are formed respectively , R ¹ ', R ² ' are repeating units of a trivalent group or a directly bonded structure.

[chem 21]

Examples of the above-mentioned reactive group that can be independently polymerized include 3,5-dibromophenyl, alkenyl, alkynyl, epoxy, and halogen atoms. The boron-containing compound of the above-mentioned formula (2) has at least one of any of these groups, whereby the boron-containing compound of the above-mentioned formula (2) can be polymerized alone. Among these, an alkenyl group, an epoxy group, and a 3,5-dibromophenyl group are preferable.

Among X ⁵ , X ⁶ , R ¹ , and R ² in the above formula (2), the group undergoing polycondensation may be a substituent having the above-mentioned reactive group capable of polycondensation in the structure. Likewise, the homopolymerizable group may be a substituent having the above-mentioned reactive group capable of independent polymerization in its structure. Examples of such substituents include linear or branched alkyl groups having 1 to 4 carbon atoms, cyclic alkyl groups having 3 to 7 carbon atoms, and straight chain alkyl groups having 1 to 8 carbon atoms. A group in which the hydrogen atom of any group such as a straight or branched alkoxy group, an aryl group or a heterocyclic group is replaced by the above-mentioned reactive group capable of polycondensation or reactive group capable of independent polymerization. Among these, styryl and 3,5-dibromophenyl are preferred.

The boron-containing polymer of the present invention may contain other monomers in the monomer component as long as it is obtained from a monomer component containing the boron-containing compound represented by the above formula (2).

That is, a boron-containing polymer obtained by polymerizing a boron-containing compound represented by formula (2) and another monomer represented by the following formula (15) is also included in the boron-containing polymer in the present invention.

[chem 22]

X ⁷ -AX ⁸ (15)

(In the formula, A represents a divalent group. X ⁷ and X ⁸ are the same or different, represent a hydrogen atom or a monovalent substituent, and at least one group in X ⁷ and X ⁸ is a substituent with a reactive group )

A in the above formula (15) is not particularly limited as long as it is a divalent group. If the name of the compound corresponding to the structure is given, for example, benzene, naphthalene, anthracene, phenanthrene, 1,2-triphenylene, Rubrene, pyrene, perylene, indene, azulene, adamantane, fluorene, fluorenone, dibenzofuran, carbazole, dibenzothiophene, furan, pyrrole, pyrroline, pyrrolidine, thiophene, dioxolane, Pyrazole, pyrazoline, pyrazolidine, imidazole, oxazole, thiazole, oxadiazole, triazole, thiadiazole, pyran, pyridine, piperidine, dioxane, morpholine, pyridazine, pyrimidine, Pyrazine, piperazine, triazine, trithiane, norbornene, benzofuran, indole, benzothiophene, benzimidazole, benzoxazole, benzothiazole, benzothiadiazole, benzoxa Oxadiazole, purine, quinoline, isoquinoline, coumarin, cinnoline, quinoxaline, acridine, phenanthroline, phenothiazine, flavone, triphenylamine, acetylacetone, dibenzoylmethane, picolinic acid , metal complexes such as silole, porphyrin, and iridium, or derivatives thereof having substituents, polymers or oligomers having structures of these derivatives, and the like.

It should be noted that, as the above-mentioned substituents, the same groups as the substituents in the above-mentioned ^R1 and ^R2 can be used.

Examples of the above-mentioned A include, for example, structures of the following formulas (16-1) to (16-4) in addition to the above-mentioned groups.

[chem 23]

-Ar1- (16-1)

-Ar1-Z1-(Ar2-Z2)a-Ar3- (16-2)

-Ar1-Z2- (16-3)

-Z2- (16-4)

(In the formula, Ar1, Ar2, and Ar3 are the same or different, representing an arylene group, a divalent heterocyclic group, or a divalent group with a metal complex structure. Z1 represents -C≡C-, -N(Q3)- , -(SiQ4Q5)b- or direct bonding. Z2 represents -CQ1=CQ2-, -C≡C-, -N(Q3)-, -(SiQ4Q5)b- or direct bonding. Q1 and Q2 are the same or different , represents a hydrogen atom, an alkyl group, an aryl group, a monovalent heterocyclic group, a carboxyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an aryl alkoxycarbonyl group, a heteroaryloxycarbonyl group or a cyano group. Q3, Q4 and Q5 are the same or different , represents a hydrogen atom, an alkyl group, an aryl group, a monovalent heterocyclic group or an aralkyl group. a represents an integer from 0 to 1. b represents an integer from 1 to 12)

The above-mentioned arylene group refers to an atomic group obtained by removing two hydrogen atoms from an aromatic hydrocarbon, and the number of carbon atoms constituting the ring is usually about 6-60, preferably 6-20. The aromatic hydrocarbons also include aromatic hydrocarbons having condensed rings, and aromatic hydrocarbons in which two or more independent benzene rings or condensed rings are directly bonded or connected via groups such as vinylidene groups.

Examples of the above-mentioned arylene group include groups represented by the following formulas (17-1) to (17-23), and the like. Among these, phenylene, biphenylene, fluorenylene, and stilylene are preferable.

It should be noted that, in formulas (17-1) to (17-23), R is the same or different, representing a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an alkylthio group, an aryl group, an aryloxy group, an aryl group Thio, aralkyl, aralkoxy, aralkylthio, acyl, acyloxy, amido, imide, imide residue, amino, substituted amino, substituted silyl, substituted silyloxy group, substituted silylthio group, substituted silylamino group, monovalent heterocyclic group, heteroaryloxy group, heteroarylthio group, aryl alkenyl group, arylethynyl group, carboxyl group, alkoxycarbonyl group, aryloxycarbonyl group, Arylalkoxycarbonyl, heteroaryloxycarbonyl or cyano. In the formula (17-1), the line marked with the line represented by x-y crossing the ring structure means that the ring structure is directly bonded to the atom in the bonded part. That is, the formula (17-1) means that it is directly bonded to any one of the carbon atoms constituting the ring marked with the line indicated by x-y, and the bonding position in the ring structure is not limited. The line marked at the vertex of the ring structure, such as the line represented by z- in formula (17-10), means that the ring structure is directly bonded to the atom in the bonded part at this position. In addition, the line marked on R crossing the ring structure means that one R or two or more R may be bonded to the ring structure, and the bonding position is not limited.

In addition, in formulas (17-1)～(17-10) and (17-15)～(17-20), carbon atoms can be replaced by nitrogen atoms, oxygen atoms or sulfur atoms, and hydrogen atoms can be replaced by fluorine atom.

[Chem. 24-1]

[Chem. 24-2]

The aforementioned divalent heterocyclic group refers to an atomic group remaining after removing two hydrogen atoms from a heterocyclic compound, and the number of carbon atoms constituting the ring is usually about 3 to 60. As the heterocyclic compound, organic compounds having a ring structure include not only carbon atoms but also heteroatoms such as oxygen, sulfur, nitrogen, phosphorus, boron, and arsenic in the ring. of organic compounds.

As said divalent heterocyclic group, the heterocyclic group represented by following formula (18-1) - (18-38), etc. are mentioned, for example.

In addition, in formula (18-1) - (18-38), R is the same as R which the said arylene group has. Y represents O, S, SO, SO ₂ , Se or Te. The same applies to the lines marked intersecting the ring structure, the lines marked at the vertices of the ring structure, and the lines marked on R intersecting the ring structure, as in formulas (17-1) to (17-23).

In addition, in formulas (18-1) to (18-38), carbon atoms may be replaced by nitrogen atoms, oxygen atoms or sulfur atoms, and hydrogen atoms may be replaced by fluorine atoms.

[Chem. 25-1]

[Chem. 25-2]

The aforementioned divalent group having a metal complex structure refers to a divalent group remaining after removing two hydrogen atoms from an organic ligand of a metal complex having an organic ligand. The number of carbon atoms of the organic ligand is generally about 4 to 60, and examples thereof include 8-hydroxyquinoline and its derivatives, benzohydroxyquinoline and its derivatives, 2-phenyl-pyridine and its derivatives. substances, 2-phenyl-benzothiazole and its derivatives, 2-phenyl-benzoxazole and its derivatives, porphyrin and its derivatives, etc.

Examples of the central metal of the metal complexes include aluminum, zinc, beryllium, iridium, platinum, gold, europium, terbium, etc., and examples of the metal complexes having organic ligands include low-molecular Fluorescent materials and phosphorescent materials known as metal complexes, triplet light-emitting complexes, etc.

Specific examples of the divalent group having the metal complex structure include groups represented by the following formulas (19-1) to (19-7).

In addition, in formula (19-1) - (19-7), R is the same as R which the said arylene group has. The lines marked at the vertices of the ring structure mean direct bonding similarly to formulas (17-1) to (17-23).

In addition, in formulas (19-1) to (19-7), carbon atoms may be replaced by nitrogen atoms, oxygen atoms or sulfur atoms, and hydrogen atoms may be replaced by fluorine atoms.

[Chem. 26-1]

[Chem. 26-2]

Moreover, as a structure of A, the structure like following formula (16-5) can also be mentioned.

[chem 27]

(In the formula, Ar4, Ar5, Ar6 and Ar7 are identical or different, represent arylene or a divalent heterocyclic group. Ar8, Ar9 and Ar10 are identical or different, represent an aryl group or a monovalent heterocyclic group. o and p are identical or Different, means 0 or 1, and 0≤o+p≤1)

Specific examples of the structure represented by the above formula (16-5) include structures represented by the following formulas (20-1) to (20-8).

[Chem. 28-1]

[Chem. 28-2]

In addition, in formula (20-1) - (20-8), R is the same as R which the said arylene group has. The lines marked at the vertices of the ring structure mean direct bonding similarly to formulas (17-1) to (17-23). In the above formulas (20-1) to (20-8), there are two or more Rs in one structural formula, and these Rs may be the same or different groups. In order to improve the solubility in a solvent, it preferably has one or more atoms other than a hydrogen atom, and preferably has a substituent-containing structure with low shape symmetry. Furthermore, in the above-mentioned formulas (20-1) to (20-8), when R contains an aryl group or a heterocyclic group in a part thereof, these groups may have one or more substituents. In addition, when R is a substituent containing an alkyl chain, the alkyl chain may be any of linear, branched, or cyclic, or a combination thereof, and when it is not linear, examples include Isopentyl, 2-ethylhexyl, 3,7-dimethyloctyl, cyclohexyl, 4-C1-C12 alkylcyclohexyl, etc. In order to improve the solubility of the boron-containing copolymer of the present invention in a solvent, it is preferable that one or more Rs contain a cyclic or branched alkyl chain.

In addition, two or more Rs may be connected to form a ring. In addition, when R is a group containing an alkyl chain, the alkyl chain may be interrupted by a group containing a heteroatom. Examples of the hetero atom include an oxygen atom, a sulfur atom, and a nitrogen atom.

As the structure of the above-mentioned A, among the above-mentioned structures, formula (16-5), formula (17-9), formula (18-16), and formula (18-28) are preferable.

The above-mentioned boron-containing polymer has at least one group among X ⁵ , X ⁶ , R ¹ and R ² in formula (2) and at least one group among X ⁷ and X ⁸ in formula (15) polymerized to form repeating units. That is, a boron-containing polymer having a repeating unit structure represented by the following formula (21) is also included in the boron-containing polymer of the present invention.

[chem 29]

(In the formula, the dotted line arc, the dotted line part in the skeleton part connecting the boron atom and the nitrogen atom, the arrow pointing to the boron atom from the nitrogen atom are the same as the formula (2). X ⁵ ', X ⁶ ', R ¹ ' and R ² ' is the same as formula (12). A is the same or different, and represents a divalent group. X ⁷ ' and X ⁸ ' represent the same group, divalent group, and X ⁸ as X ⁷ and X 8 of formula (15), respectively. trivalent group or direct bond).

The above formula (21) means that any one or more of X ⁵ ′, X ⁶ ′, R ¹ ′, and R ² ′ forms a bond as a part of the main chain of the polymer, and any one of X ⁷ ′ and X ⁸ ′ One or more bonds form a part of the main chain of the polymer.

In the boron-containing polymer having the repeating unit represented by the above-mentioned formula (21), the repeating unit derived from the above-mentioned formula (2) and the repeating unit derived from the above-mentioned formula (15) may be a random polymer, or may be Block polymers may also be graft polymers. In addition, it may be a case where the main chain of the polymer is branched and has three or more terminal parts, or a dendrimer. In addition, it may be a polymer formed by polycondensation of the boron-containing compound represented by the above formula (2) and the compound represented by the above formula (15).

In addition, the boron-containing polymer having the repeating unit represented by the above formula (21) may contain one each of the repeating unit derived from the above formula (2) and the repeat unit derived from the above formula (15), or may contain two types above. When two or more repeating units are contained, the two or more structures may be random polymers, block polymers, or graft polymers. In addition, it may be a case where the main chain of the polymer is branched and has three or more terminal parts, or a dendrimer.

As the boron-containing polymer represented by the above formula (21), there is a case where (i) any two of X ⁵ , X ⁶ , R ¹ and R ² in the above formula (2) are the same as in the above formula (15) The case where X ⁷ and X ⁸ form a bond as part of the main chain of the polymer; (ii) any one of X ⁵ , X ⁶ , R ¹ and R ² in the above formula (2) and the above formula (15) In the case where any one of ^X7 and ^X8 forms a bond as a part of the main chain of the polymer. Specific examples of the structure of the repeating unit in the above case include structures such as the following formulas (22) and (23).

[chem 30]

(i) Any two of X ⁵ , X ⁶ , R ¹ and R ² in the above formula (2) form a bond with X ⁷ and X ⁸ in the above formula (15) as a part of the main chain of the polymer In the case of , it can be derived from the repeating unit of the above formula (2) or the repeating unit derived from the above formula (15) through random addition polymerization, or it can be formed by block addition polymerization, or it can be the above formula Any one of X ⁵ , X ⁶ , R ¹ and R ² in (2) is polycondensed with X ⁷ and/or X ⁸ in the above-mentioned formula (15), among them, as the above-mentioned formula ( An example of a polymer formed by polycondensation of any two groups of X ⁵ , X ⁶ , R ¹ and R ² in 2) and X ⁷ and/or X ⁸ in the above formula (15), the above formula ( The polycondensation of X ⁵ and X ⁶ in 2) and X ⁷ and X ⁸ in the above formula (15) is a polymer having a structure represented by the following formula (24) as a repeating unit.

[chem 31]

In the case of the above-mentioned structure (i), among the repeating units represented by the above-mentioned formula (21), as specific examples of the structural part derived from the above-mentioned formula (2), there are the above-mentioned formulas (13-1) to (13- 6) and the like structure. Among these, the structures of (13-1) and (13-6) are preferable. The structure of (13-1) is more preferable.

As a reactive group when any one of X ⁵ , X ⁶ , R ¹ and R ² in the above formula (2) is polycondensed with any one of X ⁷ and X ⁸ in the above formula (15) Combinations include the same combinations as the above-mentioned combinations of reactive groups. That is, when any one of X ⁵ , X ⁶ , R ¹ and R ² in the above formula (2) is polycondensed with any one of X ⁷ and X ⁸ in the above formula (15), the above formula Among X ⁷ and X ⁸ in (15), as the group to be polycondensed, any of the substituents having the above-mentioned reactive group capable of polycondensation in the structure is preferable.

In addition, when any one of ^X7 and ^X8 in the above formula (15) is a substituent having a reactive group that can be polymerized alone in the structure, the substituent is preferably the above-mentioned group that has a reactive group that can be polymerized alone in the structure. Any of the substituents of the reactive group.

The groups bonded to both ends of the boron-containing polymer of the present invention are not particularly limited, and may be the same or different. Examples of the groups bonded to both ends include a hydrogen atom, a halogen atom, an aryl group which may or may not have a substituent, an oligoaryl group, a monovalent heterocyclic group, a monovalent oligoheterocyclic group, Alkyl, alkoxy, alkylthio, aryloxy, arylthio, aralkyl, aralkoxy, aralkylthio, alkenyl, alkynyl, allyl, amino, azo, Carboxyl, acyl, alkoxycarbonyl, formyl, nitro, cyano, silyl, stannyl, boryl, phosphino, siloxy, arylsulfonyloxy, alkylsulfonyl Oxygen etc.

The weight average molecular weight of the boron-containing polymer in the present invention is preferably 10 ³ to 10 ⁸ . When the weight average molecular weight is within the above range, it can be favorably formed into a thin film. More preferably, it is 10 ³ to 10 ⁷ , and still more preferably, it is 10 ⁴ to 10 ⁶ .

The above-mentioned weight average molecular weight can be measured by polystyrene-equivalent gel permeation chromatography (GPC apparatus, developing solvent: chloroform) with the following apparatus and measurement conditions.

Efficient GPC device: HLC-8220GPC (manufactured by Tosoh Corporation)

Developing solvent Chloroform

Column TSK-gel GMHXL×2

Eluent flow 1ml/min

Column temperature 40℃

The boron-containing polymer in the present invention is produced by polymerizing a monomer component containing a boron-containing compound represented by the above formula (2). On the premise of containing the boron-containing compound represented by the above-mentioned formula (2), the monomer component may also contain other monomers, and it is preferable to contain 0.1 to 99.9% by mass of the above-mentioned formula ( 2) The boron-containing compound represented. More preferably, it is 10-90 mass %.

In addition, during the polymerization reaction, the solid content concentration of the monomer component can be appropriately set within the range of 0.01% by mass to the maximum soluble concentration. If it is too thin, the reaction efficiency will be poor, and if it is too thick, it may be difficult to control the reaction. Therefore, Preferably it is 0.1-20 mass %.

As the above-mentioned other monomer, a monomer having a structure represented by the above-mentioned formula (15) is preferable. In addition, the said monomer component may contain 1 type together with the boron-containing compound represented by said formula (2), and the compound represented by formula (15), and may contain 2 or more types.

When the other monomer contains a compound having a structure represented by the above formula (15), it is preferable to use 0.3 to 1 mole of the boron-containing compound represented by the above formula (2) contained in the monomer component. The compound having the structure represented by the above-mentioned formula (15) was contained in a ratio of 3 moles. More preferably, the ratio is 0.2 to 2 mol with respect to 1 mol of the boron-containing compound represented by the above formula (2).

In the compound represented by the above formula (15), X ⁷ and X ⁸ may use the same substituents as the substituents having reactive groups in the above X ⁵ and X ⁶ .

When the boron-containing polymer in the present invention is formed by polycondensation reaction, the method for producing the boron-containing polymer is not particularly limited, and can be produced, for example, by the production method described in JP-A-2011-184430.

Both the boron-containing compound represented by the above formula (1) and the boron-containing polymer obtained by polymerizing monomer components containing the boron-containing compound represented by the above formula (2) can be uniformly formed into a film by coating, and have Since it has low HOMO and LUMO energy levels, it can be suitably used as a material for the first organic electroluminescent element of the present invention.

[Organic electroluminescent element of the second preferred embodiment of the present invention]

In the organic electroluminescent element of the second preferred embodiment of the present invention (hereinafter also referred to as the second organic electroluminescent element of the present invention), the buffer layer contains a reducing agent.

In the organic electroluminescence device of the present invention, as described later, the first electrode is a cathode, the second electrode is an anode, and the buffer layer is a layer capable of functioning as an electron transport layer by selecting a material forming the buffer layer.

In an organic electroluminescent element, holes are supplied from the anode and electrons are supplied from the cathode, and they recombine in the light-emitting layer to emit light. A part of the holes supplied from the anode passes through the second metal oxide layer, the light-emitting layer, the buffer layer, the second 1 metal oxide layer to reach the cathode, which is considered to be one of the causes of the reduction in the efficiency of the organic electroluminescent element. By providing a buffer layer with a predetermined thickness, it is possible to suppress holes from reaching the cathode, so that the efficiency of the element can be improved. On the other hand, if the thickness of the buffer layer is increased, the movement of electrons from the cathode to the light-emitting layer is hindered, and electrons reach the light-emitting layer between the edge portion where the influence of the thickness of the buffer layer is relatively small and the portion other than the edge portion. There is a difference in proportion, which causes a phenomenon in which only the edge part emits light. On the other hand, if the buffer layer contains a reducing agent capable of donating electrons, sufficient electrons can be supplied to the light-emitting layer to efficiently recombine electrons and holes, and the driving voltage required for light emission is also reduced. Thereby, an organic electroluminescent device having remarkably excellent luminous efficiency can be formed.

The second organic electroluminescent element of the present invention preferably has a first metal oxide layer, a buffer layer, a low-molecular compound layer including a light-emitting layer laminated on the buffer layer in this order between the first electrode and the second electrode, and a second metal oxide layer, the buffer layer contains a reducing agent.

The second organic electroluminescence device of the present invention only needs to have the first metal oxide layer, the buffer layer, the low-molecular compound layer including the light-emitting layer laminated on the buffer layer, and The second metal oxide layer may have layers other than those described above. The meaning of the low molecular weight compound in this invention is as above-mentioned.

In the second organic electroluminescent element of the present invention, the buffer layer is preferably a layer having an average thickness of 5 to 100 nm formed by applying a solution containing an organic compound.

In the second organic electroluminescence device of the present invention, when the low-molecular compound layer including the light-emitting layer is laminated on the first metal oxide layer, crystallization occurs in the low-molecular compound layer in contact with the metal oxide layer. This may lead to an increase in leakage current and a decrease in current efficiency, and in severe cases, there may be a problem that uniform surface emission cannot be obtained due to crystallization. In the organic-inorganic hybrid organic electroluminescent device, the reason why the low-molecular compound layer crystallizes is as described above.

Such crystallization is a unique problem in organic-inorganic hybrid organic electroluminescent devices, and it is a new problem that arises when low-molecular-weight compounds are used as the main body of the light-emitting layer.

In view of the above problems, if a buffer layer with an average thickness of 5 to 100 nm formed by coating a solution containing an organic compound is provided between the first metal oxide layer and the low molecular compound layer including the light emitting layer, the low molecular compound The crystallization of the low-molecular compound in the layer is suppressed, thereby, even when an organic-inorganic hybrid organic electroluminescent element has a layer formed of a low-molecular compound as a light-emitting layer, the leakage current can be suppressed, and it can be suppressed. Uneven surface emission caused by leakage current.

As mentioned above, if the thickness of the buffer layer is thickened, compared with other parts, only the edge portion of the light-emitting layer is observed to have a strong light emission phenomenon. On the other hand, by containing a reducing agent in the buffer layer, this phenomenon can be suppressed. Only the edge portion emits light, and uniform surface emission can be obtained. Therefore, according to the present invention, good device characteristics can be obtained even if the buffer layer has an average thickness of 5 to 100 nm.

In this way, the second organic electroluminescent element of the present invention is formed by coating a buffer layer capable of functioning as an electron transport layer, and the buffer layer contains a reducing agent as an n-type dopant. By forming the above-mentioned structure, In this case, the light-emitting layer can also be formed using a low-molecular compound, and the light-emitting efficiency is also excellent.

The formation method, material, preferred thickness, and the like of the buffer layer will be described below.

The reducing agent contained in the buffer layer is not particularly limited as long as it is an electron-donating compound, but is preferably a hydride reducing agent capable of hydride reduction.

As the hydride reducing agent, 2,3-dihydrobenzo[d]imidazole compound; 2,3-dihydrobenzo[d]thiazole compound; 2,3-dihydrobenzo[d]oxazole compound can be used ; Triphenylmethane compound; Dihydropyridine compound, etc. 1 or 2 or more.

In this way, the following mode is also one of the preferred embodiments of the present invention: the hydride reducing agent is selected from 2,3-dihydrobenzo[d]imidazole compounds, 2,3-dihydrobenzo[d]thiazole compounds, 2 , at least one compound selected from the group consisting of 3-dihydrobenzo[d]oxazole compounds, triphenylmethane compounds and dihydropyridine compounds.

As the hydride reducing agent, among the above, 2,3-dihydrobenzo[d]imidazole compounds and dihydropyridine compounds are preferable. More preferably (4-(1,3-dimethyl-2,3-dihydro-1H-benzimidazol-2-yl)phenyl)dimethylamine (N-DMBI), or 2,6-di Diethyl methyl-1,4-dihydropyridine-3,5-dicarboxylate (Hantzsch ester).

The amount of the reducing agent contained in the buffer layer is preferably 0.1 to 15% by mass relative to 100% by mass of the organic compound forming the buffer layer. When the reducing agent is contained in the above ratio, the luminous efficiency of the organic electroluminescent device can be made sufficiently high. The amount of the reducing agent contained in the buffer layer is more preferably 0.5 to 10% by mass, and still more preferably 1 to 5% by mass, based on 100% by mass of the organic compound forming the buffer layer.

The second organic electroluminescent device of the present invention includes a low molecular compound layer including a light emitting layer laminated on a buffer layer, and the low molecular compound layer including a light emitting layer refers to a single layer formed of a low molecular compound, or a low molecular compound layer formed of a low molecular compound. Two or more layers formed are laminated and one of them is a light-emitting layer. That is, the low-molecular compound layer including a light-emitting layer refers to either a light-emitting layer made of a low-molecular compound or a layer in which a light-emitting layer made of a low-molecular compound is laminated with another layer made of a low-molecular compound. The other layer formed from a low-molecular compound may be one layer or two or more layers. In addition, there is no particular limitation on the lamination order of the light emitting layer and other layers.

The above-mentioned other layer formed of a low-molecular compound is preferably a hole transport layer or an electron transport layer. That is, when the low molecular compound layer is composed of two or more layers, it is preferable to have a hole transport layer and/or an electron transport layer as layers other than the light emitting layer. Thus, it is one of the preferred embodiments of the second organic electroluminescent element of the present invention that the organic electroluminescent element has the hole transport layer and/or the electron transport layer as an independent layer different from the light emitting layer.

When the second organic electroluminescent device of the present invention has a hole transport layer as an independent layer, it is preferable to have a hole transport layer between the light emitting layer and the second metal oxide layer. When the second organic electroluminescent element of the present invention has the electron transport layer as an independent layer, it is preferable to have the electron transport layer between the buffer layer and the light emitting layer.

When the second organic electroluminescent element of the present invention does not have the hole transport layer and/or the electron transport layer as independent layers, one of the layers included as an essential configuration of the second organic electroluminescent element of the present invention Some layers combine the functions of these layers.

One of the preferred forms of the second organic electroluminescent element of the present invention is as follows: the organic electroluminescent element only consists of the first electrode, the first metal oxide layer, the buffer layer, the light emitting layer, the hole transport layer, the second It consists of a metal oxide layer and a second electrode, and some of these layers also function as an electron transport layer.

In addition, the following mode is also one of the preferred modes of the second organic electroluminescent element of the present invention: the organic electroluminescent element is only composed of the first electrode, the first metal oxide layer, the buffer layer, the light emitting layer, the second metal oxide layer and the second electrode, and some of these layers have both the functions of the hole transport layer and the electron transport layer.

In the second organic electroluminescent element of the present invention, the first electrode is a cathode, and the second electrode is an anode. Compounds that can be used as the first electrode and the second electrode and preferred compounds among them are the same as those in the above-mentioned first organic electroluminescent element of the present invention.

In addition, preferable values of the average thicknesses of the first electrode and the second electrode are also the same as those of the above-mentioned first organic electroluminescent element of the present invention.

The above-mentioned first metal oxide layer functions as an electron injection layer, and the second metal oxide layer functions as a hole injection layer.

Specific examples of the compound forming the first metal oxide layer and the second metal oxide layer and preferred examples thereof are the same as those of the first organic electroluminescent element of the present invention described above.

The average thickness of the first metal oxide layer is not particularly limited, but is preferably 1 to 1000 nm. More preferably, it is 2 to 100 nm.

The average thickness of the second metal oxide layer is not particularly limited, but is preferably 1 to 1000 nm. More preferably, it is 5 to 50 nm.

The average thickness of the first metal oxide layer can be measured by a stylus profiler or a spectroscopic ellipsometer.

The average thickness of the second metal oxide layer can be measured at the time of film formation using a quartz vibrator film thickness meter.

As the material of the light-emitting layer, any low-molecular compound generally usable as a material of the light-emitting layer can be used, or they can be used in combination.

As the low-molecular-weight compound, the same compounds as the low-molecular-weight compound in the above-mentioned first organic electroluminescence device of the present invention can be used.

The above-mentioned light-emitting layer may contain a dopant. As the dopant, the same substance as the dopant in the above-mentioned first organic electroluminescent element of the present invention can be used, and the preferred range of the content of the dopant when the light-emitting layer contains the dopant is also the same as that of the above-mentioned present invention. The same applies to the case of the first organic electroluminescence element.

Among the above-mentioned light-emitting layers, the light-emitting layer of the second organic electroluminescent device of the present invention is preferably a light-emitting layer containing a phosphorescent light-emitting material. When the light-emitting layer contains a phosphorescent light-emitting material, the light-emitting efficiency of the organic electroluminescent device becomes more excellent.

When the light-emitting layer contains a phosphorescent light-emitting material, it is preferable to form the light-emitting layer from a material containing a phosphorescent light-emitting material as a guest material (dopant) in a host material. When the light-emitting layer is formed of the above materials, the content of the phosphorescent light-emitting material relative to the material forming the light-emitting layer is preferably the same as the content of the dopant relative to the material forming the light-emitting layer when the light-emitting layer contains a dopant.

As the above-mentioned phosphorescent emitting material, a compound represented by any one of the following formulas (25) and (26) can be suitably used as the phosphorescent emitting material.

[chem 32]

(In the formula (25), the dotted arc indicates that a ring structure is formed together with a part of the skeleton part composed of an oxygen atom and three carbon atoms, and the ring structure formed by including a nitrogen atom is a heterocyclic ring structure. X' and X" are the same Or differently, it represents a hydrogen atom or a monovalent substituent as a substituent on the ring structure, and two or more X', X" may be bonded to the ring structure forming the arc portion of the dotted line. X', X" may be bonded to A new ring structure is formed together with a part of the two ring structures indicated by the dotted arc. In addition, when n2 is ² or more, two or more X' or X" may be bonded together to form one substituent. A dotted line in a skeleton part composed of a nitrogen atom and 3 carbon atoms indicates that 2 atoms connected by a dotted line are bonded by a single bond or a double bond. M' indicates a metal atom. An arrow pointing from a nitrogen atom to M' indicates that a nitrogen atom is coordinated located in the M' atom. n ² represents the valence number of the metal atom M')

[chem 33]

(In the formula (26), the dotted arc indicates that a ring structure is formed together with a part of the skeleton part composed of an oxygen atom and three carbon atoms, and the ring structure formed by including a nitrogen atom is a heterocyclic structure. X' and X" are the same Or differently, it represents a hydrogen atom or a monovalent substituent as a substituent on the ring structure, and two or more X', X" may be bonded to the ring structure forming the arc portion of the dotted line. X', X" may be bonded to A new ring structure is formed together with a part of the two ring structures indicated by the dotted arc. The dotted line in the skeleton part composed of nitrogen atoms and three carbon atoms indicates that the two atoms connected by the dotted line are bonded by a single bond or a double bond M' represents a metal atom. The arrow pointing from the nitrogen atom to M' indicates that the nitrogen atom is coordinated to the M' atom. n ² represents the valence number of the metal atom M'. The solid arc connecting X ^a and X ^b represents X ^a and X ^b are connected via at least one other atom, and may form a ring structure together with X ^a and X ^b . X ^a and X ^b are the same or different, and represent any one of an oxygen atom, a nitrogen atom, and a carbon atom. From X The arrow ^b pointing to M' indicates that X ^b is coordinated to the M' atom. m' is a number from 1 to 3)

Examples of ring structures represented by dotted arcs in the above formulas (25) and (26) include aromatic rings or heterocyclic rings having 2 to 20 carbon atoms, such as benzene rings, naphthalene rings, and anthracene rings. Aromatic hydrocarbon rings such as; pyridine ring, pyrimidine ring, pyrazine ring, triazine ring, benzothiazole ring, benzothiol ring, benzoxazole ring, piperonyl ring, benzimidazole ring, quinoline ring, iso Quinoline ring, quinoxaline ring, and heterocyclic rings such as phenanthridine ring, thiophene ring, furan ring, benzothiophene ring, and benzofuran ring.

In the above-mentioned formula (25) and formula (26), as the substituents of the ring structure represented by X' and X", there can be mentioned a halogen atom with 1 to 20 carbon atoms (preferably 1 to 20 carbon atoms). 10) an alkyl group, an aralkyl group having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms), an alkenyl group having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms), Aryl group, arylamino group, cyano group, amino group, acyl group with 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms), aryl group with 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms) Alkoxycarbonyl, carboxyl, alkoxy having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms), alkylamino having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms), Dialkylamino groups with 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms), aralkylamino groups with 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms), and 1 to 20 (preferably 1 to 10 carbon atoms) halogenated alkyl groups, hydroxyl groups, aryloxy groups, carbazolyl groups, and the like.

It should be noted that when the substituents of the ring structures represented by X' and X" are aryl groups or arylamino groups, the aromatic rings contained in the aryl groups and arylamino groups may also have substituents. The following substituents include the same groups as the specific examples of the above-mentioned substituents represented by X' and X".

In the above formula (25) and formula (26), when the substituents represented by X' and X" are bonded to each other to form a new ring structure with a part of the two ring structures represented by the dotted line arcs, as a combination, the dotted line The ring structures formed by the two ring structures represented by circular arcs and the new ring structure include, for example, structures such as the following (27-1) and (27-2).

[chem 34]

In the above formula (25) and formula (26), examples of the metal atom represented by M' include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum and gold.

Examples of the structure represented by the above formula (26) include structures of the following formulas (28-1) and (28-2), and the like.

[chem 35]

(In formulas (28-1) and (28-2), R ³ to R ⁵ are the same or different, representing a hydrogen atom or a monovalent substituent. In formula (28-2), R ³ to R ⁵ are monovalent substituents The ring structure can have two or more monovalent substituents. The arrow pointing from the nitrogen atom to M' and the arrow pointing to M' from the oxygen atom indicate the nitrogen atom, and the oxygen atom is coordinated to the M' atom. The dotted arc, nitrogen Atoms and the dotted line, X', X", M', n ² , m' in the skeleton part composed of three carbon atoms are the same as in formula (26))

Examples of the monovalent substituents for R ³ to R ⁵ include the same substituents as the substituents in the ring structures represented by X' and X" in the above formulas (25) and (26).

Specific examples of the compound represented by the above formula (25) and formula (26) include compounds represented by the following formulas (29-1) to (29-30), and the like.

[Chemical 36-1]

[chem 36-2]

[chem 36-3]

[chem 36-4]

As the phosphorescent material in the present invention, one or more of the above-mentioned materials can be used, and among them, tris(2-phenylpyridine)iridium (Ir) represented by the above-mentioned formula (29-1) is preferable. (ppy) ₃ ), tris(1-phenylisoquinoline) iridium (Ir(piq) ₃ ) represented by the above formula (29-19), (acetylacetonate) represented by the above formula (29-27) Bis(2-methyldibenzo-[f,h]quinoxaline)iridium (Ir(MDQ) ₂ (acac)), tris[3-methyl-2 represented by the above formula (29-28) -Phenylpyridine]iridium (Ir(mpy) ₃ ) and the like.

Examples of the host material include metal complexes represented by the following formula (30), metal complexes represented by the following formula (31), and metal complexes represented by the following formula (32), and these can be used 1 or more of them.

[chem 37]

(In the formula (30), the dotted arc indicates that a ring structure is formed together with a part of the skeleton part connecting the oxygen atom and the nitrogen atom, and the ring structure formed by including ^Z1 and the nitrogen atom is a heterocyclic structure. X', X" are the same Or differently, it represents a hydrogen atom or a monovalent substituent as a substituent on the ring structure, and two or more X', X" may be bonded to the ring structure forming the arc portion of the dotted line. X', X" may be bonded to A new ring structure is formed together with a part of the two ring structures indicated by the dotted arc. The dotted line in the skeleton part connecting the oxygen atom and the nitrogen atom indicates that the two atoms connected by the dotted line are bonded with a single bond or a double bond. M Represents a metal atom. ^Z1 represents a carbon atom or a nitrogen atom. The arrow pointing to M from the nitrogen atom indicates that the nitrogen atom is coordinated to the M atom. ^R0 represents a monovalent substituent or a divalent linking group. m represents the number of ^R0 , its is the number of 0 or 1. n ³ represents the valence number of the metal atom M. r is the number of 1 or 2);

[chem 38]

(In the formula, X' and X" are the same or different, and represent a hydrogen atom or a monovalent substituent as a substituent on the quinoline ring structure, and more than two X' and X" can be bonded to the quinoline ring structure. M represents Metal atom. The arrow pointing from the nitrogen atom to M indicates that the nitrogen atom is coordinated to the M atom. ^{R 0} indicates a monovalent substituent or a divalent linking group. m indicates the number of R ⁰ , which is the number of 0 or 1. n ³ indicates The valence number of the metal atom M. r is the number of 1 or 2);

[chem 39]

(In the formula, the dotted arc indicates that a ring structure is formed with a part of the skeleton part connecting the oxygen atom and the nitrogen atom, and the ring structure formed by ^Z1 and the nitrogen atom is a heterocyclic structure. X', X "are the same or different, Represents a hydrogen atom or a monovalent substituent as a substituent on the ring structure, and two or more X', X" may be bonded to the ring structure forming the arc portion of the dotted line. X', X" may be bonded to the dotted line Parts of the two ring structures indicated by the arcs form a new ring structure together. The dotted line in the skeleton part connecting the oxygen atom and the nitrogen atom indicates that the two atoms connected by the dotted line are bonded with a single bond or a double bond. M indicates a metal atom Z ¹ represents a carbon atom or a nitrogen atom. The arrow pointing to M from the nitrogen atom indicates that the nitrogen atom is coordinated to the M atom. n ³ represents the valence number of the metal atom M. The solid line arc connecting X ^a and X ^b represents X ^a and X ^b is connected via at least one other atom, and may form a ring structure together with X ^a and X ^b . In addition, a coordination bond may be contained in the bond between X ^a and X ^b via at least one other atom. ^{X a} , X ^b is the same or different, and represents any of an oxygen atom, a nitrogen atom, and a carbon atom. An arrow pointing from X ^b to M indicates that X ^b is coordinated to an atom. m' is a number from 1 to 3)

In the above formula (30), when r is 1, a metal complex having 1 M atom in the structure is formed; when r is 2, a metal complex having 2 M atoms in the structure is formed. atomic metal complex represented by the following formula (33-2).

[chemical 40]

In the above formulas (30) and (32), the ring structure represented by the dotted arc may be a ring structure consisting of one ring or a ring structure consisting of two or more rings. Examples of such ring structures include aromatic rings or heterocyclic rings having 2 to 20 carbon atoms, aromatic rings such as benzene rings, naphthalene rings, and anthracene rings; diazole rings, thiazole rings, isothiazole rings, Azole ring, isoxazole ring, thiadiazole ring, oxadiazole ring, triazole ring, imidazole ring, imidazoline ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, diazine ring, triazine ring , benzimidazole ring, benzothiazole ring, benzoxazole ring, benzotriazole ring and other heterocycles.

Among these, benzene ring, thiazole ring, isothiazole ring, oxazole ring, isoxazole ring, thiadiazole ring, oxadiazole ring, triazole ring, imidazole ring, imidazoline ring, pyridine ring, pyridine ring, Oxyzine ring, pyrimidine ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, benzotriazole ring.

In the above formulas (30) to (32), the substituents of the ring structures represented by X' and X" include those represented by X' and X" in the above formulas (25) and (26). The same group as the substituents of the ring structure of .

In the above formula (30) and formula (32), the substituents in the ring structures represented by X' and X" are bonded to each other to form a new ring structure together with a part of the two ring structures represented by the dotted arcs. In this case, examples of the ring structure obtained by combining the two ring structures indicated by the dotted arcs and a new ring structure include structures such as (27-1) and (27-2) above.

In the above formulas (30) to (32), the metal atom represented by M is preferably a metal atom of Groups 1 to 3, Group 9, Group 10, Group 12 or Group 13 of the periodic table, preferably zinc, aluminum , gallium, platinum, rhodium, iridium, beryllium, magnesium in any one.

In the above formula (30) and formula (31), when R ⁰ is a monovalent substituent, the monovalent substituent is preferably any one of the following formulas (34-1) to (34-3).

[chem 41]

(In the formula, Ar ¹ to Ar ⁵ represent an aromatic ring with or without a substituent, a heterocyclic ring, or a structure in which two or more aromatic rings or heterocyclic rings are directly bonded, and Ar ³ to Ar ⁵ may have the same structure or different structures. structure. Q ⁰ represents a silicon atom or a germanium atom)

Specific examples of the aromatic ring or heterocyclic ring of Ar ¹ to Ar ⁵ include the same examples as the specific examples of the aromatic ring or heterocyclic ring of the ring structure represented by the dotted arc in the above formula (30), as two The structure in which the above-mentioned aromatic ring or heterocyclic ring is directly bonded includes a structure in which two or more of the ring structures listed as specific examples of the aromatic ring or heterocyclic ring are directly bonded. In this case, two or more directly bonded aromatic rings or heterocyclic rings may have the same ring structure or different ring structures.

Specific examples of the substituent of the aromatic ring or heterocyclic ring include the same groups as the specific examples of the substituent of the aromatic ring or heterocyclic ring of the ring structure represented by the dotted arc in the formula (30).

In the above formula (30) and formula (31), when R ⁰ is a divalent linking group, R ⁰ is preferably any of -O- and -CO-.

In the above formula (32), the structure formed by X ^a , X ^b and the solid-line arc connecting X ^a and X ^b may contain one or more ring structures. The ring structure may be formed including X ^a and X ^b , and examples of the ring structure in this case include the same ring structures as the ring structures represented by dotted arcs in the above-mentioned formula (30) and formula (32), or pyrazole ring. It is preferably a structure including X ^a and X ^b to form a pyrazole ring.

In the above formula (32), the solid-line arc connecting X ^a and X ^b may consist of only carbon atoms, or may contain other atoms. Examples of other atoms include boron atoms, nitrogen atoms, sulfur atoms, and the like.

And the solid-line arc connecting X ^a and X ^b may contain one or more than two ring structures other than the ring structure formed by including X ^a and X ^b . As the ring structure in this case, the above-mentioned A ring structure similar to the ring structure represented by a dotted arc in formula (30) and formula (32), or a pyrazole ring.

Examples of the structure represented by the above formula (32) include structures of the following formula (35), and the like.

[chem 42]

(In formula (35), R ³ to R ⁵ are the same or different, and represent a hydrogen atom or a monovalent substituent. The arrow pointing from the nitrogen atom to M and the arrow pointing from the oxygen atom to M indicate that the nitrogen atom and the oxygen atom are coordinated to the M atom The dotted line arc, the dotted line in the skeleton part connecting the oxygen atom and the nitrogen atom, X', X", M, Z ¹ , n ³ , m' are the same as formula (32))

Examples of the monovalent substituents for R ³ to R ⁵ in the formula (35) include the same substituents as the substituents of the ring structures represented by X' and X" in the above formulas (25) and (26) .

Specific examples of the compound represented by the above formula (30) include compounds having structures represented by the following formulas (36-1) to (36-40), and the like.

[Chem. 43-1]

[Chem. 43-2]

[Chem. 43-3]

[Chem. 43-4]

Specific examples of the compound represented by the above formula (31) include compounds having structures represented by the following formulas (37-1) to (37-3), and the like.

[chem 44]

Specific examples of the compound represented by the above formula (32) include compounds having structures represented by the following formulas (38-1) to (38-8), and the like.

[chem 45]

As the host material in the present invention, one or more of the above-mentioned materials can be used, and among them, bis[2-(2-benzothiazolyl)phenol represented by the above-mentioned formula (36-11) is preferable. ] zinc, bis(10-hydroxybenzo[h]quinoline) beryllium (Bebq ₂ ) represented by the above formula (36-34), bis(2-(2-hydroxyl) represented by the above formula (36-35) Phenyl)pyridine)beryllium (Bepp ₂ ).

The average thickness of the light-emitting layer is not particularly limited, but is preferably 10 to 150 nm. More preferably, it is 20 to 100 nm.

The average thickness of the light emitting layer can be measured at the time of film formation using a quartz vibrator film thickness meter.

As the material of the hole transport layer, the same material as that of the hole transport layer in the first organic electroluminescent element of the present invention can be used.

In addition, the preferred value of the average thickness of the hole transport layer is also the same as the case of the first organic electroluminescent element of the present invention described above.

As the material of the electron transport layer, the same material as that of the electron transport layer in the first organic electroluminescent element of the present invention can be used.

In addition, the preferred value of the average thickness of the electron transport layer is also the same as the case of the first organic electroluminescent element of the present invention described above.

For the organic electroluminescence element of the present invention, the method for forming the first and second metal oxide layers, the second electrode, the light-emitting layer, the hole transport layer, and the electron transport layer is also the same as that of the first organic electroluminescent element of the present invention. The method for forming these layers in the luminescence element is the same.

As described above, the buffer layer included in the organic electroluminescence element of the present invention is preferably a layer formed by applying a solution containing an organic compound. Forming a buffer layer with a predetermined thickness by coating can effectively suppress the crystallization of the low-molecular compound formed on the buffer layer.

The above-mentioned method of coating the solution containing the organic compound, the solvent used for preparing the solution containing the organic compound, and the concentration of the organic compound in the solvent are also similar to the above-mentioned method of coating the organic compound-containing element in the first organic electroluminescent element of the present invention. The method, solvent, and concentration when forming a buffer layer from a solution of the same.

The unevenness existing on the surface of the first metal oxide layer is smoothed by applying and forming the buffer layer, thereby suppressing the crystallization of the low-molecular compound subsequently formed on the buffer layer.

Such a buffer layer differs from the invention disclosed in JP 2012-4492 A (Patent Document 5) as described above.

The average thickness of the buffer layer is preferably 5 to 100 nm. When the average thickness is within the above-mentioned range, the effect of suppressing crystallization of the low molecular compound layer including the light-emitting layer can be sufficiently exhibited. If the average thickness of the buffer layer is less than 5 nm, the unevenness existing on the surface of the first metal oxide may not be sufficiently smoothed, and leakage current may increase, so that the effect of forming the buffer layer may not be sufficiently exhibited. In addition, when the average thickness of the buffer layer is thicker than 100 nm, the driving voltage will increase, which is not practically preferable. In addition, when a compound having a preferred structure in the present invention described below is used as the organic compound, the buffer layer can also sufficiently function as an electron transport layer. The average thickness of the buffer layer is more preferably 10 to 60 nm.

The average thickness of the buffer layer can be measured by a stylus profiler or a spectroscopic ellipsometer.

The second organic electroluminescent element of the present invention may be formed by laminating layers constituting the organic electroluminescent element on a substrate. When each layer is laminated on a substrate, each layer is preferably formed on the first electrode formed on the substrate. In this case, the organic electroluminescent element of the present invention may be a top emission type element that extracts light on the side opposite to the side where the substrate exists, or may be a bottom emission type element that extracts light on the side where the substrate exists. element.

The material of the substrate and the average thickness of the substrate are the same as the material of the substrate and the average thickness of the substrate in the above-mentioned first organic electroluminescent element of the present invention.

In the second organic electroluminescent element of the present invention, examples of the organic compound forming the buffer layer include the same organic compound as the organic compound forming the buffer layer in the above-mentioned first organic electroluminescent element of the present invention. compound.

In addition, in the second organic electroluminescent device of the present invention, the organic compound forming the buffer layer is preferably an organic compound having a boron atom, more preferably a boron-containing compound represented by the above formula (1). The reasons why boron-containing compounds of this structure are preferred are as described above.

Furthermore, the preferred structure of the boron-containing compound represented by formula (1) is also the same as that of the first organic electroluminescent device of the present invention.

The boron-containing compound represented by the above formula (1) can be uniformly formed into a film by coating and has low HOMO and LUMO energy levels, so it can be suitably used as a material for the second organic electroluminescent element of the present invention.

The second organic electroluminescent device of the present invention is the organic electroluminescent device of the present invention, and the buffer layer contains a reducing agent, thereby making the organic electroluminescent device excellent in light emission characteristics. In such a second organic electroluminescent element of the present invention, it is preferable to have a first metal oxide layer, a buffer layer, and a low-density layer including a light-emitting layer stacked on the buffer layer in this order between the first electrode and the second electrode. A molecular compound layer, and a second metal oxide layer, and the buffer layer contains a reducing agent.

Such a method for manufacturing an organic-inorganic hybrid organic electroluminescent element according to a second preferred embodiment of the present invention, that is, a method for manufacturing an organic electroluminescent element having a structure in which two or more layers are laminated, is characterized in that That is, the manufacturing method includes the following steps: according to the organic electroluminescent element, between the first electrode and the second electrode, there are in order a first metal oxide layer, a buffer layer containing a reducing agent, and a layer containing a light-emitting element layered on the buffer layer. A method for manufacturing an organic electroluminescence element according to the second preferred mode of the present invention is also one of the present invention. one.

The method for producing an organic electroluminescent element according to the second preferred aspect of the present invention preferably includes a step of applying a solution containing an organic compound to form a buffer layer having an average thickness of 5 to 100 nm.

The method for manufacturing an organic electroluminescent element according to the second preferred embodiment of the present invention may include other steps as well as the steps above, and may include forming the first and second metal oxide layers, buffer layers, light-emitting layers, etc. The process of layers other than the low molecular compound layer. In addition, the material, formation method, organic compound, solvent used for preparing a solution containing the organic compound, and the thickness of each layer forming the organic electroluminescent element are the same as the second organic electroluminescent element of the present invention, preferably The scheme is the same.

[Organic electroluminescence element of a third preferred embodiment of the present invention]

The organic light-emitting element of the 3rd preferred form of the present invention (hereinafter also referred to as the third organic electroluminescent element of the present invention) is: the buffer layer in the organic light-emitting element of the present invention is made of a nitrogen-containing film and has an average thickness of An organic light-emitting device with a layer of 3 to 150 nm.

In other words, the third organic electroluminescent element of the present invention is an organic electroluminescent element having a structure in which two or more layers are laminated between an anode and a cathode formed on a substrate, wherein the organic electroluminescent element A metal oxide layer is provided between the anode and the cathode, and a nitrogen-containing film is provided on the metal oxide layer with an average thickness of 3 to 150 nm.

The nitrogen-containing film is preferably a nitrogen-containing film that does not have electron transport properties. It should be noted that the non-electron transport referred to here refers to extremely low electron mobility. Specifically, it means that the electron mobility is less than 10 ^-6 cm ² /Vs or the electrical conductivity is less than 10 ^-6 S/m.

The third organic electroluminescent element of the present invention is an organic electroluminescent element having a reverse structure in which two or more layers are stacked between the anode and the cathode formed on the substrate, and between the anode and the cathode Has a metal oxide layer, and has a nitrogen-containing film on the metal oxide layer with an average thickness of 3 to 150 nm, as long as it is so, the number of other layers, the materials constituting the other layers, and the order of lamination are not critical. Particularly limited, it is preferred that the metal oxide layer and the nitrogen-containing compound layer be located between the cathode and the light-emitting layer. Nitrogen-containing compounds have excellent electron injection properties, and an organic electroluminescent device having such a layer configuration has high electron injection properties and is an device excellent in luminous efficiency.

The nitrogen-containing film used in the third organic electroluminescent element of the present invention has the following four types in total: (1) a nitrogen-containing film formed of a nitrogen-containing compound on a metal oxide layer; (2) a nitrogen-containing film formed on a metal oxide layer; A high nitrogen-containing film formed by a nitrogen-containing compound on the layer; (3) a nitrogen-containing film formed by decomposing a nitrogen-containing compound on a metal oxide layer; (4) by decomposing a nitrogen-containing compound on a metal oxide layer And the formation of high nitrogen-containing film.

The reason why the performance of the organic electroluminescence element is improved by forming such a film is presumed to be as follows.

First, when nitrogen atoms are present, their lone electron pairs tend to form bonds with metal atoms in the substrate. The polarization between the metal-nitrogen bonds exhibits strong electron injection properties. All the nitrogen-containing films of (1) to (4) above satisfy the above conditions. More preferably, the above (2) in which the proportion of nitrogen atoms having lone electron pairs is high is more suitable.

Regarding (3) and (4) above, it is expected to form a film in which nitrogen atoms are present at a high density on the substrate due to the decomposition phenomenon associated with film formation, and as a result, it is expected that abundant and various metal-nitrogen bonds will appear. And it is believed that there is a stronger metal-nitrogen bond than before. Further, depending on the state of decomposition, other components such as unnecessary carbon may disappear, thereby relatively increasing the nitrogen atomic fraction, and as a result, a more suitable environment is realized (4). In these nitrogen-containing films, since the main source of nitrogen is metal-nitrogen bonds, it is expected that nitrogen atoms will accumulate at a higher density than normal molecular physical adsorption. It is considered that for these reasons, by having such a nitrogen-containing film, the organic electroluminescence device is excellent in luminous efficiency, device driving stability, and device life. Actually, the phenomenon caused by the above-mentioned decomposition of nitrogen-containing compounds can be confirmed by X-ray photoelectron spectroscopy, which is one of surface analysis methods. The specific results are shown in the examples. Using a compound containing nitrogen and carbon as constituent elements as a nitrogen-containing compound, and performing a treatment to decompose the compound, it was observed that the carbon:nitrogen ratio (CN ratio) was from 2:1 To 1:1, forming a high nitrogen ratio. And at the same time, it was observed that the half-width of the spectrum of nitrogen increased through the above-mentioned treatment. This result shows the expansion of the chemical environment and also implies the emergence of stronger metal-nitrogen bonds.

Therefore, it is considered that the substrate of the nitrogen-containing film is a film containing a metal element, which greatly contributes to the expression of the above-mentioned effects exerted by the third organic electroluminescence device of the present invention.

The nitrogen-containing films of (1) and (2) above are films composed of nitrogen-containing compounds formed on the metal oxide layer, that is, the films are formed under the condition that the nitrogen-containing compounds do not decompose. The nitrogen-containing film of (2) above is formed using a compound having a high ratio of nitrogen atoms to the total number of atoms constituting the nitrogen-containing compound as the nitrogen-containing compound.

The method of forming the nitrogen-containing film of (1) and (2) above is not particularly limited, but a method of applying a solution of a nitrogen-containing compound on the metal oxide layer and then volatilizing the solvent is suitable.

The nitrogen-containing films of (3) and (4) above are films formed by decomposing a nitrogen-containing compound on the metal oxide layer, but a part of the undecomposed nitrogen-containing compound may remain. Preferably the nitrogen-containing compound is completely decomposed.

The method for forming the nitrogen-containing film of (3) and (4) above is not particularly limited, but a method of decomposing the nitrogen-containing compound after applying a solution of the nitrogen-containing compound on the metal oxide layer is suitable.

The nitrogen-containing film is preferably formed by a method including the step of applying a solution containing a nitrogen-containing compound on the metal oxide layer. By forming the nitrogen-containing film by the method including the above steps, the organic electroluminescent device having the metal oxide layer can suppress leakage current and obtain uniform surface emission.

The reason for this is the same as the reason why leakage current can be suppressed and uniform surface emission can be obtained by having a buffer layer formed by coating a solution containing an organic compound in the above-mentioned first organic light-emitting element of the present invention.

The above-mentioned nitrogen-containing film contains nitrogen element and carbon element as elements constituting the film, and the ratio of nitrogen atoms and carbon atoms constituting the film preferably satisfies the following relationship:

Number of nitrogen atoms/(number of nitrogen atoms+number of carbon atoms)>1/8.

Thus, if the ratio of the number of nitrogen atoms in the nitrogen-containing film is high, the total number of metal-nitrogen bonds increases, resulting in higher electron injection characteristics due to stronger polarization. The number of nitrogen atoms/(number of nitrogen atoms+number of carbon atoms) in the nitrogen-containing film is more preferably greater than 1/5.

The ratio of nitrogen and carbon in the nitrogen-containing film can be measured by photoelectron spectroscopy (XPS).

The nitrogen-containing films of (3) and (4) above are not particularly limited as long as they are formed by decomposing the nitrogen-containing compound on the metal oxide layer, and the method for decomposing the nitrogen-containing compound is not particularly limited. formed by decomposition.

When the nitrogen-containing compound is decomposed by heating, the bonding between the metal atoms and the nitrogen atoms in the metal oxide layer is strengthened, whereby the organic electroluminescence device exhibits high driving stability over a longer period of time.

Therefore, the above-mentioned nitrogen-containing film is most preferably formed by applying a solution containing a nitrogen-containing compound on the metal oxide layer and then decomposing the nitrogen-containing compound by heating. Leakage current and the effect of obtaining uniform surface emission, and the effect of making the organic electroluminescent element exhibit high driving stability for a longer period of time.

Such a method of manufacturing a HOILED element, that is, a method of manufacturing an organic electroluminescent element having a structure in which two or more layers are laminated between the anode and the cathode formed on the substrate, is characterized in that the above-mentioned manufacturing method The method comprises: a step of coating a solution containing a nitrogen-containing compound on a metal oxide layer; and a step of performing a heat treatment at a temperature at which the nitrogen-containing compound decomposes to produce a layer composed of a nitrogen-containing film of the present invention, the above-mentioned having A method for manufacturing an electroluminescent element is also one of the present inventions.

The aforementioned heat treatment for decomposing the nitrogen-containing compound is preferably performed in the air. By carrying out in the atmosphere, the decomposition of the nitrogen-containing compound can be sufficiently accelerated, and the organic electroluminescence device can exhibit higher driving stability over a long period of time.

The temperature of the heat treatment for decomposing the nitrogen-containing compound is preferably 80 to 200° C., and the time is preferably 1 to 30 minutes.

The temperature and time of the heat treatment can be appropriately set within the above range according to the type of nitrogen-containing compound. For example, when using the following polymer having a polyalkyleneimine structure in the main chain skeleton as a nitrogen-containing compound, the larger the molecular weight of the polymer, the higher the decomposition temperature. Therefore, the molecular weight of the polymer can be considered. The temperature and time of the heat treatment were appropriately set according to the heat treatment conditions in the Examples.

Whether or not the nitrogen-containing compound is decomposed can be confirmed by X-ray photoelectron spectroscopy (XPS) measurement.

For the above-mentioned nitrogen-containing film, after the process of decomposing the nitrogen-containing compound on the metal oxide layer, the process of cleaning the surface of the film with an organic solvent such as ethanol or methoxyethanol may be performed, thereby The above nitrogen-containing film is formed.

Examples of the nitrogen-containing compound include pyrrolidones such as polyvinylpyrrolidone, pyrroles such as polypyrrole, anilines such as polyaniline, or pyridines such as polyvinylpyridine. Compounds with nitrogen-containing heterocycles and amine compounds such as pyrrolidines, imidazoles, piperidines, pyrimidines, and triazines. Among them, a compound having a large nitrogen content is preferable, and a compound containing polyamines or a triazine ring is preferable.

Since the ratio of the number of nitrogen atoms to the total number of atoms constituting the compound is high, polyvalent amines are suitable from the viewpoint of imparting high electron injection and driving stability to the organic electroluminescent device.

The polyamines are preferably those capable of forming a layer by coating, and may be low-molecular-weight compounds or high-molecular-weight compounds. As the low-molecular compound, polyalkylene polyamines such as diethylenetriamine are preferably used, and as the high-molecular compound, polymers having a polyalkyleneimine structure are preferably used. Particularly preferred is polyethyleneimine.

In addition, the low-molecular-weight compound here means a compound other than a high-molecular compound (polymer), and does not necessarily mean a compound with a low molecular weight.

One of the preferred embodiments of the present invention is to use, among the above-mentioned polyvalent amines, a polymer having a linear structure having a polyalkyleneimine structure in the main chain skeleton.

Among polyamines, the use of polymers with such a structure makes device driving stability and device life more excellent. This is presumed to be because such a polymer having a polyalkyleneimine structure in the main chain skeleton is solid due to its linear structure, and thus stably exists in the device.

The nitrogen-containing film formed on the metal oxide layer from such a polymer having a linear structure having a polyalkyleneimine structure in the main chain skeleton is the nitrogen-containing film of (1) above.

It should be noted that the polymer having a linear structure of a polyalkyleneimine structure in the main chain skeleton is formed as long as most of the polyalkyleneimine structures forming the main chain skeleton are connected in a straight chain. What is necessary is enough, and a part may have a branched chain structure. Preferably, 80% or more of the polyalkyleneimine structures forming the main chain skeleton are connected in a linear chain, more preferably 90% or more are connected in a linear chain, and even more preferably 95% or more are connected in a linear chain , it is most preferable that 100% of the polyalkyleneimine structures forming the main chain skeleton are connected in a straight chain.

The polyalkyleneimine structure of the above-mentioned polymer having a polyalkyleneimine structure is preferably a structure formed of an alkyleneimine having 2 to 4 carbon atoms. More preferably, it is a structure formed of an alkyleneimine having 2 or 3 carbon atoms.

The above-mentioned polymer having a polyalkyleneimine structure may be a copolymer having a structure other than a polyalkyleneimine structure as long as it has a polyalkyleneimine structure in the main chain skeleton.

When the above-mentioned polymer having a polyalkyleneimine structure has a structure other than the polyalkyleneimine structure, examples of monomers that become raw materials for structures other than the polyalkyleneimine structure include ethylene, propylene , butene, acetylene, acrylic acid, styrene or vinyl carbazole, etc., one or two or more of them can be used. In addition, monomers having a structure in which hydrogen atoms bonded to carbon atoms of these monomers are substituted with other organic groups can also be suitably used. Examples of other organic groups that replace hydrogen atoms include hydrocarbon groups having 1 to 10 carbon atoms that may contain at least one atom selected from the group consisting of oxygen atoms, nitrogen atoms, and sulfur atoms.

In the above polymer having a polyalkyleneimine structure, it is preferable that monomers forming a polyalkyleneimine structure account for 50% by mass or more in 100% by mass of monomer components forming the main chain skeleton of the polymer. More preferably, it is 66 mass % or more, and it is still more preferable that it is 80 mass % or more. Most preferably, the monomer forming the polyalkyleneimine structure is 100% by mass, that is, the polymer having the polyalkyleneimine structure is a homopolymer of polyalkyleneimine.

It is preferable that the weight average molecular weight of the said polymer which has a polyalkyleneimine structure is 100000 or less. Using a polymer having a polyalkyleneimine structure having such a weight-average molecular weight and forming a layer by heat treatment at a temperature at which the polymer decomposes can further improve the driving stability of the organic electroluminescent device. More preferably, it is 10000 or less, and it is still more preferable that it is 100-1000.

Moreover, when the polymer which has a polyalkyleneimine structure is a polymer of the said linear structure, it is more preferable that the weight average molecular weight of a polymer is 250000 or less, and it is still more preferable that it is 10000-50000.

The weight average molecular weight can be determined by GPC (gel permeation chromatography) measurement under the following conditions.

Measuring equipment: Waters Alliance (2695) (trade name, manufactured by Waters Corporation)

Molecular weight column: TSKguard columnα, TSKgelα-3000, TSKgelα-4000, TSKgelα-5000 (all manufactured by Tosoh Corporation) connected in series

Eluent: Mix 96 g of 50 mM sodium hydroxide aqueous solution and 3600 g of acetonitrile in 14304 g of 100 mM boric acid aqueous solution

Standard substance for calibration curve: polyethylene glycol (manufactured by Tosoh Corporation)

Measuring method: The object to be measured was dissolved in the eluent so that the solid content was about 0.2% by mass, and the substance filtered with a filter was used as a measurement sample to measure the molecular weight.

As the triazine ring-containing compound, melamine or guanamine is suitable because it is a nitrogen-containing cyclic compound, has a high ratio of nitrogen atoms to the total number of atoms constituting the compound, and is rigid. When a film made of melamine or guanamines is formed on the metal oxide layer, the high nitrogen-containing film of (2) above is formed.

As the above-mentioned triazine ring-containing compound, in addition to guanamines such as melamine or benzomelamine/methylguanamine, methylolated melamine or guanamines, melamine resins/guanamine resins, and the like having melamine/guanamine can also be used. One or two or more compounds having a guanamine skeleton. Among these, melamine is preferable because the ratio of nitrogen atoms to all atoms constituting the compound is high.

Furthermore, as the above-mentioned compound having a nitrogen-containing heterocycle or an amine compound, a polymer having a repeating unit of a structure represented by the following formulas (39) to (47), or a triethylamine of the formula (48), Ethylenediamine of formula (49).

[Chemical 46-1]

[chem 46-2]

In addition, when these nitrogen-containing compounds are decomposed on the metal oxide layer, the nitrogen-containing film of (3) or the high-nitrogen-containing film of (4) above is formed. It is considered that by using, as the nitrogen-containing compound, a compound having a high ratio of nitrogen, such as a polyamine or a triazine ring-containing compound, the decomposition product of the nitrogen-containing compound can be more densely deposited on the metal oxide layer. The nitrogen-containing film on the metal oxide is also one of the inventions of this patent. For the nitrogen-containing thin film, further description will be made below.

The average thickness of the nitrogen-containing film in the present invention is 3 to 150 nm. When the nitrogen-containing film has the above-mentioned average thickness, the above-mentioned effect of having the nitrogen-containing film can be exhibited favorably. The average thickness of the nitrogen-containing film is preferably 5 to 100 nm. More preferably, it is 5 to 50 nm. Especially in the case of a nitrogen-containing film formed by decomposing a nitrogen-containing compound, it is preferably 5 to 100 nm, more preferably 5 to 50 nm.

The average thickness of the nitrogen-containing film can be measured during film formation using a contact profiler. The contact profiler greatly depends on the measurement environment when measuring extremely thin films, resulting in large deviations in measured values. Therefore, when measuring the average thickness in this patent, it is determined by the average value of 2 or more measurements.

The third organic electroluminescent element of the present invention preferably has an anode, a cathode, and one or more organic compound layers sandwiched between the anode and the cathode, and a metal oxide layer is formed between the cathode and the organic compound layer. layer, and a layer composed of the nitrogen-containing film of the present invention is provided between the metal oxide layer and the organic compound layer. The organic compound layer here is a layer that includes a light-emitting layer and, if necessary, an electron-transporting layer and a hole-transporting layer.

Among them, the third organic electroluminescent element of the present invention is preferably an organic-inorganic hybrid organic electroluminescent element in which a cathode is adjacently formed on a substrate and a metal oxide layer is provided between the anode and the cathode. , wherein, there is a light-emitting layer and an anode, an electron injection layer and an optional electron transport layer are provided between the cathode and the light-emitting layer, and a hole transport layer and/or a hole injection layer is provided between the anode and the light-emitting layer. The third organic electroluminescent device of the present invention may have other layers between the above-mentioned layers, but is preferably a device composed of only the above-mentioned layers. That is, it is preferably an element in which the cathode, the electron injection layer, the optional electron transport layer, the light emitting layer, the hole transport layer and/or the hole injection layer, and the anode are sequentially stacked adjacent to each other. In addition, each said layer may consist of 1 layer, and may consist of 2 or more layers.

As described above, the nitrogen-containing film is preferably used on the electron injection side, that is, the cathode side, because it has excellent electron injection characteristics. Furthermore, as will be described later, the metal oxide layer is preferably laminated as part of the cathode or one layer of the electron injection layer and/or laminated as part of the anode or one layer of the hole injection layer.

In the organic electric field device having the above configuration, when the device does not have an electron transport layer, the electron injection layer is adjacent to the light emitting layer. In addition, when the element has only any one of the hole transport layer and the hole injection layer, the layer is stacked adjacent to the light-emitting layer and the anode, and the element has both the hole transport layer and the hole injection layer. Alternatively, these layers are stacked adjacently in the order of the light emitting layer, the hole transport layer, the hole injection layer, and the anode.

In the 3rd organic electroluminescence element of the present invention, as the material that forms light-emitting layer, also can use any kind of compound in the material that can be used as light-emitting layer generally, can be low-molecular compound also can be high-molecular compound, also can use They can be mixed.

It should be noted that the low-molecular-weight material in the present invention refers to a material other than a high-molecular material (polymer), and does not necessarily refer to an organic compound with a low molecular weight.

Examples of the polymer material for forming the light-emitting layer include, for example, compounds other than polyethyleneimine (PEI) among the compounds described as examples of the organic compound for forming the buffer layer in the first organic light-emitting element of the present invention. compounds, and Japanese Patent Application No. 2010-230995, and the boron compound-based polymer materials described in Japanese Patent Application No. 2011-6457.

As the low-molecular-weight material for forming the light-emitting layer, for example, the same low-molecular compound as the low-molecular compound that can be used as a material of the light-emitting layer in the above-mentioned first organic light-emitting element of the present invention can be used.

The average thickness of the light-emitting layer is not particularly limited, but is preferably the same as the average thickness of the light-emitting layer of the above-mentioned first organic light-emitting element of the present invention.

When the third organic electroluminescent device of the present invention has an electron transport layer, any compound that can be generally used as a material for the electron transport layer may be used as the material thereof, or they may be used in combination.

Examples of the compound that can be used as a material for the electron transport layer include the same compounds as the low-molecular compound that can be used as a material for the electron transport layer in the above-mentioned first organic light-emitting element of the present invention, and the same is true for preferred compounds. of.

When the third organic electroluminescence device of the present invention has a hole transport layer, the hole transport organic material used as the hole transport layer can be used alone or in combination with various p-type polymer materials or various p-type low molecular materials. Material.

Examples of p-type polymer materials (organic polymers) include polyarylamine, fluorene-arylamine copolymer, fluorene-bisthiophene copolymer, poly(N-vinylcarbazole), polyvinylpyrene, poly Vinyl anthracene, polythiophene, polyalkylthiophene, polyhexylthiophene, poly(p-phenylene vinylene), polythienylene vinylene, pyrene formaldehyde resin, ethyl carbazole formaldehyde resin or its derivatives, etc. .

And these compounds can also be used in the form of a mixture with other compounds. As an example, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT/PSS) etc. are mentioned as a mixture containing polythiophene.

Examples of the above-mentioned p-type low-molecular-weight material include the same compounds as the low-molecular-weight compound that can be used as a material of the hole transport layer in the above-mentioned first organic light-emitting element of the present invention.

When the third organic electroluminescent element of the present invention has an electron transport layer and a hole transport layer, the average thickness of these layers is not particularly limited. The average thickness of the transport layer is the same.

The average thickness of the electron-transporting layer and the hole-transporting layer can be measured by a quartz vibrator film thickness meter in the case of a low-molecular compound, and can be measured by a contact profiler in the case of a high-molecular compound.

The third organic electroluminescent element of the present invention has a metal oxide layer at any one or both places between the cathode and the luminescent layer, and between the anode and the luminescent layer, preferably between the cathode and the luminescent layer and There are metal oxide layers between the light-emitting layer and the anode. If the metal oxide layer from the cathode to the luminescent layer is set as the first metal oxide layer, and the metal oxide layer from the anode to the luminescent layer is set as the second metal oxide layer, if the present invention is shown An example of the structure of a preferred element of the third organic electroluminescent element is shown as follows: a cathode, a first metal oxide layer, a layer composed of a nitrogen-containing film, a light-emitting layer, a hole transport layer, a second The metal oxide layer and the anode are sequentially stacked adjacent to each other. It should be noted that an electron-transporting layer may be provided between the layer composed of the nitrogen-containing film and the light-emitting layer as necessary. In terms of the importance of the metal oxide layer, the importance of the first metal oxide layer is higher, and the second metal oxide layer can be replaced by organic materials with extremely low lowest unoccupied molecular orbitals such as HATCN and F ₄ TCNQ .

The materials and layer configurations of the first metal oxide layer and the second metal oxide layer, and the average thickness of the layers are the same as those described in the first organic light-emitting element of the present invention.

In the third organic light-emitting element of the present invention, the materials and average thicknesses of the anode and the cathode are the same as described in the above-mentioned first organic light-emitting element of the present invention.

The 3rd organic electroluminescence element of the present invention is a kind of organic electroluminescence element of the present invention, wherein, buffer layer is the layer that the average thickness of 3～150nm is made of nitrogen-containing film, thereby, can make organic electroluminescence The luminous efficiency and lifetime of the light-emitting element are excellent.

Such a method for manufacturing an organic-inorganic hybrid organic electroluminescent element according to a third preferred embodiment of the present invention, that is, a method for manufacturing an organic electroluminescent element having a structure in which two or more layers are stacked, is characterized in that In that, the manufacturing method includes stacking such that the organic electroluminescent element has a metal oxide layer between the first electrode and the second electrode in this order, and a layer composed of a nitrogen-containing film stacked on the metal oxide layer. The step of forming each layer of the organic electroluminescence element, the lamination step includes the step of forming a nitrogen-containing film with an average thickness of 3 to 150 nm, and the method for manufacturing the organic electroluminescence element according to the third preferred embodiment of the present invention is also the present invention. One of the inventions.

The method for manufacturing an organic electroluminescence device according to the third preferred embodiment of the present invention may include other steps as long as the above-mentioned steps are included, and may include forming layers other than a metal oxide layer and a layer composed of a nitrogen-containing film. process. In addition, the material, formation method, organic compound, solvent used for preparing the solution containing the organic compound, and the thickness of each layer forming the layers of the organic electroluminescent element are the same as those of the third organic electroluminescent element of the present invention, preferably The scheme is the same.

For the organic electroluminescent element of the present invention, the film-forming method of the layer formed of the organic compound is not particularly limited, and various methods can be appropriately used according to the characteristics of the material. When it can be prepared as a solution and coated, it can be used The above-mentioned first organic light-emitting element of the present invention can be used to form a film by various coating methods when forming the buffer layer. Among them, the spin coating method and the slit coating method are preferable from the viewpoint of easier control of the film thickness. As an example suitable when no coating is performed or when the solvent solubility is low, a vacuum evaporation method or an ESDUS (Evaporative Spray Deposition from Ultra-dilute Solution) method, etc. are mentioned.

When applying an organic compound solution to form the above-mentioned layer composed of an organic compound, as a solvent for dissolving the organic compound, the same solvent as that used for preparing the solution containing the organic compound in the above-mentioned first organic light-emitting element of the present invention can be used. Among them, nonpolar solvents are more suitable as solvents, such as xylene, toluene, cyclohexylbenzene, dihydrobenzofuran, trimethylbenzene, tetramethylbenzene and other aromatic hydrocarbons Solvents; pyridine, pyrazine, furan, pyrrole, thiophene, methyl pyrrolidone and other aromatic heterocyclic compound solvents; hexane, pentane, heptane, cyclohexane and other aliphatic hydrocarbon solvents, etc., can be used alone or in combination they.

When polyvalent amines are used as the nitrogen-containing compound, water or a lower alcohol can be used as a solvent for the nitrogen-containing compound-containing solution. As the lower alcohol, an alcohol having 1 to 4 carbon atoms is preferably used, and methanol, ethanol, propanol, ethoxyethanol, methoxyethanol, etc. can be used alone or in combination.

The above-mentioned cathode, anode and oxide layer can be formed by the same method as the method for forming the first and second metal oxide layers, the second electrode, the light-emitting layer, the hole transport layer, and the electron transport layer in the above-mentioned first organic electroluminescence element. method formed. For forming an anode and a cathode, bonding of metal foils can also be used. These methods are preferably selected according to the characteristics of the materials of each layer, and the manufacturing methods of each layer may be different. Among the above-mentioned methods, it is more preferable to form the second metal oxide layer using a vapor phase film deposition method. The second metal oxide layer can be formed cleanly and in good contact with the anode without damaging the surface of the organic compound layer by the vapor phase film forming method, and as a result, the above-mentioned effects brought about by having the second metal oxide layer can be obtained. more significant.

For reasons such as further improving the characteristics of the third organic electroluminescent element of the present invention, for example, a hole blocking layer, an electronic element layer, and the like may be included as necessary. As materials for forming these layers, materials used for forming these layers are used, and layers can be formed by methods generally used for forming these layers.

Compared with an organic electroluminescent element in which all layers of the element are composed of organic compounds, the third organic electroluminescent element of the present invention does not need to be tightly sealed, but it may be sealed if necessary. As a sealing process, a conventional method can be used suitably. For example, a method of bonding a sealed container in an inert gas, a method of directly forming a sealing film on an organic EL element, and the like are mentioned. In addition to these methods, a method of sealing a water-absorbing material can also be used in combination.

The third organic electroluminescent element of the present invention is an organic electroluminescent element having a reverse structure in which cathodes are adjacently formed on a substrate. The third organic electroluminescent element of the present invention may be a top emission type element that extracts light from the side opposite to the side where the substrate is present, or may be a bottom emission type element that extracts light from the side where the substrate is present.

The material and average thickness of the substrate are the same as those of the first organic electroluminescence element.

As described above, the organic electroluminescent element of the present invention has a layer composed of a nitrogen-containing film on the metal oxide layer, thereby improving the electron injection characteristics so that the luminous efficiency is excellent, and at the same time, the driving stability of the element and the lifetime of the element are improved. excellent.

Such an effect of improving electron injection characteristics is not limited to organic electroluminescent elements, and is also an advantageous effect that contributes to performance improvement of other optoelectronic devices such as solar cells and organic semiconductors. Such a nitrogen-containing film that helps to improve the performance of optoelectronic devices, that is, a nitrogen-containing film, is characterized in that the film is formed on a metal-containing substrate and is formed by a solid nitrogen-containing compound; or contains nitrogen and Carbon element is used as an element constituting the film, and the ratio of nitrogen atoms and carbon atoms constituting the film satisfies the following relationship:

Number of nitrogen atoms/(number of nitrogen atoms + number of carbon atoms)>1/8,

Such a nitrogen-containing film is also one of the present invention.

A preferred embodiment and production method of the nitrogen-containing film of the present invention are the same as those of the layer composed of the nitrogen-containing film in the above-mentioned organic electroluminescence device of the present invention.

The electroluminescence element of the present invention can be made to emit light by applying a voltage (usually 15 volts or less) between the anode and the cathode. Usually a DC voltage is applied, but an AC component can also be included.

The organic electroluminescent element of the present invention is an organic-inorganic hybrid type element, but the crystallization of the low-molecular compound unique to the organic-inorganic hybrid type element is suppressed, and it is possible to realize suppression of leakage current and uniform surface emission, and can be used suitably. Materials for display devices or lighting devices. The organic electroluminescence element of the present invention can change the emission color by appropriately selecting the material of the organic compound layer, and can also obtain a desired emission color by using a color filter or the like in combination. Therefore, it can be suitably used as a light-emitting part of a display device or as a lighting device. In particular, due to characteristics such as an inverted structure, it is suitable for a display device combined with an oxide TFT.

Such a display device formed using the organic electroluminescent element of the present invention is also one of the present invention. A lighting device further using the organic electroluminescence element of the present invention is also one of the present invention.

Invention effect

The first organic electroluminescent element of the present invention has the above-mentioned structure, and can realize suppressed leakage current and uniform surface emission.

And the second organic electroluminescent element of the present invention has a buffer layer, thus compared with the existing organic-inorganic hybrid organic electroluminescent element, the luminous life is longer, and because the buffer layer contains a reducing agent, the luminous efficiency is excellent. . The organic-inorganic hybrid organic electroluminescent element has advantages in manufacturing such as reducing the necessity of sealing each layer tightly like the organic electroluminescent element in which each layer of the organic electroluminescent element is composed of organic substances. advantages and excellent luminous properties such as luminous lifetime and luminous efficiency.

Furthermore, the third organic electroluminescent element of the present invention is an organic electroluminescent element having an organic-inorganic hybrid reverse structure that does not need to be tightly sealed and has an excellent luminous efficiency and stable repeatability of luminescence. Excellent high drive stability and uniformity of light emission, and long device life.

The organic electroluminescent device of the present invention has the above-mentioned excellent characteristics, and can be suitably used as a material of a display device or a lighting device, or the like.

Description of drawings

FIG. 1 is an SEM photograph when a solution obtained by dissolving boron-containing compound 1 in THF is applied to an ITO-attached transparent glass substrate.

2 is a graph showing the voltage-current efficiency characteristics of the organic electroluminescent elements fabricated in Example 1 and Comparative Example 1. FIG.

3 is a graph showing the voltage-current efficiency characteristics of the organic electroluminescence elements fabricated in Examples 2 to 4 and Comparative Example 2. FIG.

4 is a graph showing the voltage-current efficiency characteristics of the organic electroluminescence elements fabricated in Example 5 and Comparative Example 2. FIG.

5 is a graph showing the voltage-current efficiency characteristics of the organic electroluminescence elements fabricated in Example 6 and Comparative Example 3. FIG.

FIG. 6 is a graph showing voltage-luminance characteristics of organic electroluminescence elements fabricated in Example 7 and Comparative Example 4. FIG.

7 is a graph showing the current density-current efficiency characteristics of the organic electroluminescence elements fabricated in Example 7 and Comparative Example 4. FIG.

8 is a graph showing the voltage-luminance characteristics of the organic electroluminescence elements fabricated in Example 8 and Comparative Example 5. FIG.

9 is a graph showing the current density-current efficiency characteristics of the organic electroluminescence elements fabricated in Example 8 and Comparative Example 5. FIG.

10 is a graph showing the voltage-luminance characteristics of the organic electroluminescence elements fabricated in Examples 9 and 10 and Comparative Example 6. FIG.

11 is a graph showing the current density-current efficiency characteristics of the organic electroluminescent elements fabricated in Examples 9 and 10 and Comparative Example 6. FIG.

12 is a graph showing the voltage-luminance characteristics of the organic electroluminescence elements fabricated in Example 11 and Comparative Example 7. FIG.

13 is a graph showing the current density-current efficiency characteristics of the organic electroluminescence elements fabricated in Example 11 and Comparative Example 7. FIG.

14 is a graph showing the voltage-luminance characteristics of the organic electroluminescence elements fabricated in Example 12 and Comparative Example 8. FIG.

15 is a graph showing the current density-current efficiency characteristics of the organic electroluminescence elements fabricated in Examples 12 and 13 and Comparative Example 8. FIG.

FIG. 16 is a schematic diagram showing an example of a layered structure of a third organic electroluminescent element shown in the present invention.

17-1 is a graph showing measurement results of (a) voltage-current density/brightness characteristics and (b) current density-current efficiency characteristics of the organic electroluminescent device produced in Example 14. FIG.

Fig. 17-2 shows the continuous driving characteristics of the organic electroluminescence element produced in Example 14 at (c-1) constant current density (corresponding to 100 cd/m ² ) and (c-2) constant current density (corresponding to 1000 cd/m ² ) graph of measurement results of continuous drive characteristics.

18 is a graph showing measurement results of (a) voltage-current density/brightness characteristics and (b) current density-current efficiency characteristics of the organic electroluminescent device produced in Comparative Example 9. FIG.

19-1 is a graph showing measurement results of (a) voltage-current density/brightness characteristics and (b) current density-current efficiency characteristics of the organic electroluminescent device produced in Example 15. FIG.

Fig. 19-2 is a graph showing the measurement results of the continuous driving characteristics of the organic electroluminescent element produced in Example 15 at a constant current density (c-2) (corresponding to 1000 cd/m ² ).

20-1 is a graph showing measurement results of (a) voltage-current density/brightness characteristics and (b) current density-current efficiency characteristics of the organic electroluminescent device produced in Example 16.

Fig. 20-2 is a graph showing the measurement results of the continuous driving characteristics of the organic electroluminescence element produced in Example 16 at a constant current density (c-2) (corresponding to 1000 cd/m ² ).

21 is a diagram showing (a) voltage-current density/brightness characteristics and (c-1) continuous driving characteristics at a constant current density (corresponding to 100 cd/m ² ) of the organic electroluminescence element produced in Example 17. A graph of the measurement results.

22-1 is a graph showing measurement results of (a) voltage-current density/brightness characteristics and (b) current density-current efficiency characteristics of the organic electroluminescent device produced in Example 18.

Fig. 22-2 is a graph showing the measurement results of the continuous driving characteristics of the organic electroluminescence element produced in Example 18 at a constant current density (c-1) (corresponding to 100 cd/m ² ).

23-1 is a graph showing measurement results of (a) voltage-current density/brightness characteristics and (b) current density-current efficiency characteristics of the organic electroluminescent device produced in Example 19.

23-2 is a graph showing the measurement results of the continuous driving characteristics of the organic electroluminescence element produced in Example 19 at a constant current density (c-1) (corresponding to 100 cd/m ² ).

24-1 is a graph showing measurement results of (a) voltage-current density/brightness characteristics and (b) current density-current efficiency characteristics of the organic electroluminescent device produced in Example 20.

Fig. 24-2 is a graph showing the measurement results of the continuous driving characteristics of the organic electroluminescence element produced in Example 20 at (c-2) constant current density (corresponding to 1000 cd/m ² ).

25-1 is a graph showing measurement results of (a) voltage-current density/brightness characteristics and (b) current density-current efficiency characteristics of the organic electroluminescent device produced in Example 21.

Fig. 25-2 is a graph showing the measurement results of the continuous driving characteristics of the organic electroluminescence element produced in Example 21 at (c-2) constant current density (corresponding to 1000 cd/m ² ).

26-1 is a graph showing measurement results of (a) voltage-current density/brightness characteristics and (b) current density-current efficiency characteristics of the organic electroluminescent device produced in Example 22.

Fig. 26-2 is a graph showing the measurement results of the continuous driving characteristics of the organic electroluminescence element produced in Example 22 at a constant current density (c-1) (corresponding to 100 cd/m ² ).

27-1 is a graph showing measurement results of (a) voltage-current density/brightness characteristics and (b) current density-current efficiency characteristics of the organic electroluminescent device produced in Example 23.

Fig. 27-2 is a graph showing the measurement results of the continuous driving characteristics of the organic electroluminescence element produced in Example 23 at (c-2) constant current density (corresponding to 1000 cd/m ² ).

FIG. 28 is a graph showing the results of photoelectron spectroscopy of the nitrogen-containing film produced in Production Example 1. FIG.

FIG. 29 is a graph showing the results of photoelectron spectroscopy of the nitrogen-containing film produced in Production Example 2. FIG.

FIG. 30 is a graph showing the results of photoelectron spectroscopy of the nitrogen-containing film produced in Production Example 3. FIG.

31 is a graph showing the results of photoelectron spectroscopy of the nitrogen-containing film produced in Production Example 4. FIG.

Fig. 32 is a graph showing measurement results of (a) voltage-current density/luminance characteristics and (b) current density-current efficiency characteristics of the organic electroluminescent device produced in Example 24-1.

Fig. 33 is a graph showing measurement results of (a) voltage-current density/luminance characteristics and (b) current density-current efficiency characteristics of the organic electroluminescent device produced in Example 24-2.

34 is a graph showing measurement results of (a) voltage-current density/brightness characteristics and (b) current density-current efficiency characteristics of the organic electroluminescent device produced in Example 25. FIG.

35 is a graph showing measurement results of (a) voltage-current density/brightness characteristics and (b) current density-current efficiency characteristics of the organic electroluminescent device produced in Comparative Example 10. FIG.

Detailed ways

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In addition, unless otherwise stated, "part" means "weight part", and "%" means "mass %".

In the following examples, various physical properties were measured as described below.

^<1H-NMR>

The obtained boron-containing compound was made into a deuterated chloroform solution, and measured using a high-resolution nuclear magnetic resonance apparatus (product name "Gemini 2000"; 300 MHz, manufactured by Varian, Inc.). Chemical shifts are reported in parts per million (ppm; δ values) on the downfield side of tetramethylsilane, referenced to the hydrogen nuclei of tetramethylsilane (δ 0.00).

^<13C-NMR>

The obtained boron-containing compound was made into a deuterated chloroform solution, and measured using a high-resolution nuclear magnetic resonance apparatus (product name "Gemini 2000"; 75 MHz, manufactured by Varian, Inc.). Chemical shifts are reported in parts per million (ppm; δ values) downfield from tetramethylsilane as carbon nuclei in NMR solvent (CDCl ₃ : δ=77.0, CD ₂ Cl ₂ : δ=53.1 , CD ₃ CN: δ=1.32, DMSO-d ₆ : δ=39.52) for reference.

^<11B-NMR>

The obtained boron-containing compound was made into a solution of deuterated chloroform, and it was measured using a high-resolution nuclear magnetic resonance apparatus (product name "Mercury-400"; 128 MHz, manufactured by Varian, Inc.). Chemical shifts are reported in parts per million (ppm; δ value) based on the boron nucleus (δ=0.00) of the boron trifluoride-diethyl ether complex.

<High Resolution Mass Spectrum>

Using a high-resolution mass spectrometer (product name "JMS-SX101A", "JMS-MS700", "JMS-BU250", manufactured by JEOL Ltd.), by electron ionization (EI) or high-speed electron bombardment (FAB) Determination.

<Weight average molecular weight>

The weight-average molecular weight was measured by polystyrene-equivalent gel permeation chromatography (GPC apparatus, developing solvent; chloroform) with the following apparatus and measurement conditions.

Efficient GPC device: HLC-8220GPC (manufactured by Tosoh Corporation)

Determination conditions:

Developing solvent Chloroform

Column TSK-gel GMHXL×2

Eluent flow 1ml/min

Column temperature 40℃

<The first organic electroluminescence element of the present invention>

(Synthesis Example 1)

(Synthesis of 2,7-bis(3-dibenzoborol-4-pyridylphenyl)-9,9'-spirobifluorene)

Add 2-(dibenzoborolylphenyl)-5-bromopyridine (2.6g, 6.5mmol), 2,7-bis(4,4,5, 5-Tetramethyl-1,3,2-dioxaborolanyl)-9,9'-spirobifluorene (1.5g, 2.7mmol), Pd(PtBu ₃ ) ₂ (170mg, 0.32mmol ), THF (65 mL) was added to the flask under a nitrogen atmosphere, followed by stirring.

A 2M tripotassium phosphate aqueous solution (11 mL, 22 mmol) was added thereto, and heated and stirred at 70° C. under reflux. After 12 hours, it was cooled to room temperature, the reaction solution was transferred to a separatory funnel, water was added, and ethyl acetate was used for extraction. The organic layer was washed with 3N hydrochloric acid, water, and saturated brine, and then dried with magnesium sulfate. The filtrate after filtration was concentrated, and the obtained solid was washed with methanol, thereby obtaining 2,7-bis(3-dibenzoborole-4-pyridylphenyl) in a yield of 47%. )-9,9'-spirobifluorene (boron-containing compound 1) (1.2 g, 1.3 mmol).

Its physical property values are as follows.

¹ H-NMR (CDCl ₃ ): δ6.67(d, J=7.6Hz, 2H), 6.75(d, J=1.2Hz, 2H), 6.82(d, J=7.2Hz, 4H), 6.97(dt ,J=7.2,1.2Hz,4H),7.09(dt,J=7.2,0.8Hz,2H),7.24-7.40(m,14H),7.74-7.77(m,6H),7.84-7.95(m,10H )

In addition, the reaction of Synthesis Example 1 is represented by the following reaction formula.

[chem 47]

Regarding the boron-containing compound 1 synthesized in Synthesis Example 1, the device physical properties shown below were evaluated.

<Coating Film Formability>

A smooth thin film can be obtained by applying a solution obtained by dissolving the boron-containing compound 1 in THF on an ITO-attached transparent glass substrate. The SEM (scanning electron microscope) photograph (magnification: 10000 times) is shown in FIG. 1 . From this result, it was verified that the boron-containing compound 1 is a low-molecular compound and can be coated into a film from a solution.

(Synthesis Example 2)

Under an argon atmosphere, ethyldiisopropylamine (39 mg, 0.30 mmol) was added to a dichloromethane solution (0.3 ml) containing 5-bromo-2-(4-bromophenyl) pyridine (94 mg, 0.30 mmol) , added boron tribromide (1.0M, 0.9ml, 0.9mmol) at 0°C, and stirred at room temperature for 9 hours. After cooling the reaction solution to 0° C., saturated potassium carbonate aqueous solution was added, and extraction was performed with chloroform. The organic layer was washed with brine, dried over magnesium sulfate and filtered. After concentrating the filtrate with a rotary evaporator, the resulting white solid was filtered out and washed with hexane to obtain a boron-containing compound 2 (40 mg, 0.082 mmol) represented by the following formula (50) in a yield of 28%. .

[chem 48]

Its physical property values are as follows.

¹ H-NMR (CDCl ₃ ): 7.57-7.59 (m, 2H), 7.80 (dd, J=8.4, 0.6Hz, 1H), 7.99 (s, 1H), 8.27 (dd, J=8.4, 2.1Hz, 1H), 9.01(d, J=1.5Hz, 1H);

(Synthesis Example 3)

Under a nitrogen atmosphere, the diethyl ether solution (1M, 61.2ml, 70.4mmol) of pentafluorophenylmagnesium bromide was cooled to 0°C, and a diethyl ether solution of zinc chloride (1M, 17ml, 17mmol). After completion of the dropwise addition, the mixture was stirred at room temperature for 1 hour. A toluene solution (80 ml) containing 5-bromo-2-(4-bromo-2-dibromoborylphenyl)pyridine (3.8 g, 8 mmol) represented by the above formula (26) was added thereto, at 80 ℃ heating and stirring for 15 hours. After cooling to room temperature, the reaction solution was added to ice water, and extracted with chloroform. The organic layer was washed with saturated brine, dried over sodium sulfate, and filtered. After concentrating the filtrate with a rotary evaporator, it was purified by silica gel chromatography (hexane:dichloromethane=1:1), thereby obtaining a boron-containing compound represented by the following formula (51) in a yield of 58%. 3 (2.2 g, 4.61 mmol).

[chem 49]

Its physical property values are as follows.

¹ H-NMR (CDCl ₃ ): δ7.16-7.26 (m, 10H), 7.45-7.48 (m, 1H), 7.69-7.71 (m, 1H), 7.81 (d, J=2.0Hz, 1H), 7.90(d,J=8.0Hz,1H),8.15-8.18(m,1H),8.56(d,J=2.0Hz,1H)

(Synthesis Example 4)

Dissolve BC6F5 dibromide (boron-containing compound 3) (337 mg, 0.51 mmol) represented by the above formula (51) and F8 boric acid diester (292 mg, 0.52 mmol) represented by the following formula (52) in toluene (3 ml) and THF (3 ml), stirred at room temperature for 10 minutes under an argon atmosphere. A mixed aqueous solution of Aliquat336 (21 mg), 25% by mass Et ₄ NOH aqueous solution (0.86 ml) and distilled water (0.75 ml) was added thereto, and further stirred at room temperature for 20 minutes under an argon atmosphere to complete degassing. Tetrakis(triphenylphosphine)palladium (8.9 mg, 0.007 mmol) was added thereto, followed by heating and stirring at 115°C for 48 hours under reflux. In order to block the terminal, bromobenzene (105 mg, 0.67 mmol) was added and stirred for 5 hours, and phenylboronic acid (294 mg, 2.41 mmol) was further added and stirred for 5 hours. After naturally cooling to room temperature, the reaction solution diluted with toluene was washed once with hydrochloric acid and twice with pure water, and the organic layer was concentrated to about several milliliters. The concentrate was added dropwise to 300 ml of methanol, stirred as it was for 10 minutes, and the obtained precipitate was filtered off. The same purification process was repeated a total of three times, and the solid was dried under reduced pressure to obtain a boron-containing polymer F8BC6F5 represented by the following formula (53). The weight average molecular weight of the boron-containing polymer F8BC6F5 is 126,000.

[chemical 50]

[Chemical 51]

(Manufacturing of organic electroluminescent elements)

In the following examples, the average thickness of the buffer layer was measured using a stylus profiler (product name "Alpha-StepIQ", manufactured by KLA TENCOR).

(Example 1)

[1] A commercially available transparent glass substrate with an ITO electrode layer having an average thickness of 0.7 mm was prepared. At this time, the ITO electrode (1st electrode) patterned by 2 mm width was used for the ITO electrode (1st electrode) of a board|substrate. The substrate was ultrasonically cleaned in acetone and isopropanol for 10 minutes, and then boiled in isopropanol for 5 minutes. This board|substrate was taken out from isopropanol, it was made to dry by nitrogen flow, and UV ozone cleaning was performed for 20 minutes.

[2] This substrate was fixed to a substrate holder of a facing target sputtering apparatus (Mirrortron Sputtering System) having a zinc metal target. After the pressure was reduced to about 1×10 ^-4 Pa, sputtering was performed with argon and oxygen introduced to form a zinc oxide layer with a film thickness of about 2 nm. At this time, in order to take out the electrode, a metal mask was used together so that zinc oxide would not be formed on a part of the ITO electrode.

[3] Prepare a mixed solution of 1% magnesium acetate in water-ethanol (1:3 by volume). The substrate produced in step [2] was cleaned again in the same manner as in step [1]. Place the cleaned substrate with the zinc oxide film on a spin coater. A magnesium acetate solution was dropped on this substrate, and it was rotated at 1300 rpm for 60 seconds. This was fired in the air for 2 hours on a hot plate set at 400° C., thereby forming a zinc oxide/magnesium oxide layer (first metal oxide layer).

[4] A 0.2% tetrahydrofuran solution of boron-containing compound 1 was prepared. The substrate with zinc oxide/magnesium oxide thin film produced in process [3] was placed in a spin coater. The boron-containing compound 1 solution was dropped onto the substrate, and rotated at 2000 rpm for 30 seconds, thereby forming a buffer layer composed of a boron-containing organic compound. The average thickness of the buffer layer was 5 nm.

[5] The substrate up to the formation of the boron-containing organic compound layer is fixed to the substrate holder of the vacuum deposition apparatus. 4,4'-bis[9-dicarbazolyl]-2,2'-biphenyl (CBP), tris(1-phenylisoquinoline) iridium (Ir(piq) ₃ ), N, N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (α-NPD) was added to the alumina crucible and placed in a steamer plating source. Reduce the pressure in the vacuum evaporation device to about 1×10 ^-5 Pa, and co-evaporate 35 nm with CBP as the main body and Ir(piq) ₃ as the dopant to form a light-emitting layer. At this time, the doping concentration was set to 6% by weight of Ir(piq) ₃ with respect to the entire light emitting layer. Next, 60 nm of α-NPD was evaporated to form a hole transport layer. Next, after purging nitrogen once, molybdenum trioxide and gold were added into the alumina crucible and placed in the evaporation source. The pressure in the vacuum deposition apparatus was reduced to about 1×10 ^-5 Pa, and molybdenum trioxide (second metal oxide layer) was deposited so as to form a film thickness of 10 nm. Next, gold (second electrode) was vapor-deposited so as to form a film thickness of 50 nm, thereby producing an organic electroluminescence element 1-1. When vapor-depositing the second electrode, it was performed so that the vapor-deposition surface was formed into a strip shape with a width of 2 mm using a vapor-deposition mask made of stainless steel. That is, the light-emitting area of the produced organic electroluminescence element was 4 mm ² .

(comparative example 1)

Except that the process [4] was omitted, it carried out similarly to Example 1, and produced the organic electroluminescence element 1-2.

(Example 2)

[1] A commercially available transparent glass substrate with an ITO electrode layer having an average thickness of 0.7 mm was prepared. At this time, the ITO electrode (1st electrode) patterned by 2 mm width was used for the ITO electrode (1st electrode) of a board|substrate. The substrate was ultrasonically cleaned in acetone and isopropanol for 10 minutes, and then boiled in isopropanol for 5 minutes. This board|substrate was taken out from isopropanol, it was made to dry by nitrogen flow, and UV ozone cleaning was performed for 20 minutes.

[2] The substrate was fixed to a substrate holder of a facing-target sputtering apparatus having a zinc metal target. After the pressure was reduced to about 1×10 ^-4 Pa, sputtering was performed with argon and oxygen introduced to form a zinc oxide layer (first metal oxide layer) with a film thickness of about 2 nm. At this time, in order to take out the electrode, a metal mask was used together so that zinc oxide would not be formed on a part of the ITO electrode.

[3] Prepare 0.2% THF solution of boron-containing polymer F8BC6F5. The substrate with the zinc oxide thin film produced in step [2] was placed in a spin coater. A boron-containing polymer F8BC6F5 solution was dropped onto the substrate, and rotated at 2000 rpm for 30 seconds to form a buffer layer made of a boron-containing organic compound. The average thickness of the buffer layer was 10 nm.

[4] The substrate until the boron-containing organic compound layer is formed is fixed to the substrate holder of the vacuum evaporation apparatus. Tris(8-hydroxyquinoline)aluminum (Alq ₃ ), N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4' - Diamine (α-NPD) was added to the alumina crucible and placed in the evaporation source. The vacuum evaporation apparatus was reduced to about 1×10 ⁻⁴ Pa, and 65 nm of Alq ₃ was co-deposited to form a light-emitting layer. Next, 60 nm of α-NPD was evaporated to form a hole transport layer. Next, after purging nitrogen once, molybdenum trioxide and gold were added into the alumina crucible and placed in the evaporation source. The vacuum vapor deposition apparatus was decompressed to about 1×10 ^-4 Pa, and molybdenum trioxide (second metal oxide layer) was vapor-deposited so as to form a film thickness of 10 nm. Next, gold (second electrode) was vapor-deposited so as to form a film thickness of 30 nm, and organic electroluminescent element 1-3 was produced. When vapor-depositing the 2nd electrode, it carried out so that a vapor-deposition surface may become a band shape with a width of 2 mm using the vapor-deposition mask made of stainless steel. That is, the light-emitting area of the produced organic electroluminescence element was 4 mm ² .

(Example 3)

The 0.2% tetrahydrofuran solution of the boron-containing polymer F8BC6F5 used in the procedure [3] in Example 2 was replaced with 0.2% of commercially available poly(dioctylfluorene-alternating-benzothiadiazole) (F8BT) Except for the toluene solution, the organic electroluminescence element 1-4 was produced in the same manner. The average thickness of the buffer layer was 10 nm.

(Example 4)

The 0.2% tetrahydrofuran solution of the boron-containing polymer F8BC6F5 used in the step [3] in Example 2 was replaced with a 0.2% commercially available poly(dioctylfluorene) (PFO) xylene solution, and the same procedure was performed except that Then, organic electroluminescent elements 1-5 were fabricated. The average thickness of the buffer layer was 10 nm.

(comparative example 2)

Except for omitting the step [3], it carried out similarly to Example 2, and produced the organic electroluminescence element 1-6.

(Example 5)

The tetrahydrofuran solution of 0.2% boron-containing polymer F8BC6F5 used in the process [3] in Example 2 was replaced with the ethanol solution of 1% polyethyleneimine SP-200 manufactured by Nippon Shokubai Co., Ltd., except that the same Then, organic electroluminescent elements 1-7 were fabricated. The average thickness of the buffer layer was 10 nm.

(Example 6)

[1] A commercially available transparent glass substrate with an ITO electrode layer having an average thickness of 0.7 mm was prepared. At this time, the ITO electrode (1st electrode) patterned by 2 mm width was used for the ITO electrode (1st electrode) of a board|substrate. The substrate was ultrasonically cleaned in acetone and isopropanol for 10 minutes, and then boiled in isopropanol for 5 minutes. This board|substrate was taken out from isopropanol, it was made to dry by nitrogen flow, and UV ozone cleaning was performed for 20 minutes.

[2] The substrate was fixed to a substrate holder of a facing-target sputtering apparatus having a titanium metal target. After the pressure was reduced to about 1×10 ^-4 Pa, sputtering was performed with argon and oxygen introduced to form a titanium oxide layer (first metal oxide layer) with a film thickness of about 2 nm. At this time, in order to take out the electrode, a metal mask was used together so that part of the ITO electrode would not be formed with titanium oxide.

[3] Prepare 0.2% THF solution of boron-containing polymer F8BC6F5. The substrate with the titanium oxide thin film produced in step [2] was placed in a spin coater. A boron-containing polymer F8BC6F5 solution was dropped onto the substrate, and rotated at 2000 rpm for 30 seconds to form a buffer layer made of a boron-containing organic compound. The average thickness of the buffer layer was 10 nm.

[4] The substrate until the boron-containing organic compound layer is formed is fixed to the substrate holder of the vacuum evaporation apparatus. Tris(8-hydroxyquinoline)aluminum (Alq ₃ ), N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4' - Diamine (α-NPD) was added to the alumina crucible and placed in the evaporation source. Reduce the pressure in the vacuum evaporation device to about 1×10 ^-4 Pa, and co-evaporate 65 nm of Alq ₃ to form a light-emitting layer. Next, 60 nm of α-NPD was evaporated to form a hole transport layer. Next, after purging nitrogen once, molybdenum trioxide and gold were added into the alumina crucible and placed in the evaporation source. The vacuum vapor deposition apparatus was decompressed to about 1×10 ^-4 Pa, and molybdenum trioxide (second metal oxide layer) was vapor-deposited so as to form a film thickness of 10 nm. Next, gold (second electrode) was vapor-deposited so as to form a film thickness of 30 nm, and organic electroluminescence element 1-8 was produced. When vapor-depositing the 2nd electrode, it carried out so that a vapor-deposition surface may become a band shape with a width of 2 mm using the vapor-deposition mask made of stainless steel. That is, the light-emitting area of the produced organic electroluminescence element was 4 mm ² .

(comparative example 3)

Except having carried out process [3b] instead of process [3], it carried out similarly to Example 6, and produced the organic electroluminescence element 1-9.

[3b] A solution in which F8TES, a material for self-assembled monomolecular membranes described in paragraphs [0064] to [0066] of JP 2012-4492 A (Patent Document 5) was diluted with ethanol to 1% was prepared. The substrate with the titanium oxide thin film produced in step [2] was placed in a spin coater. A F8TES solution, a material for a self-assembled monomolecular film, was dropped onto the substrate, and rotated at 2000 rpm for 30 seconds. Immediately thereafter, ethanol was used for rinsing, and ethanol was used for ultrasonic cleaning for 10 minutes. After rinsing, immobilization was performed on a hot plate at 90° C. for 10 minutes to form a self-assembled monomolecular film layer. The average thickness of the buffer layer was 2 nm. F8TES is a compound of the following formula (54).

[Chemical 52]

(Measurement of Luminescence Characteristics of Organic Electroluminescent Devices)

A voltage was applied to the element and a current was measured using a "2400-type Source Meter" manufactured by Keithley Corporation. The emission luminance was measured using "LS-100" manufactured by Konica Minolta Corporation. In addition, the uniformity of the light emitting surface was confirmed by visual inspection.

The voltage-current efficiency characteristics when a DC voltage of 4 V to 10 V is applied in an argon atmosphere to the organic electroluminescence elements produced in Example 1 and Comparative Example 1 are shown in FIG. 2 . It can be seen that the element produced in Comparative Example 1 has low current efficiency and large leakage current. On the other hand, it can be seen that the element produced in Example 1 has high current efficiency and suppressed leakage current. In addition, in the element produced in Example 1, very uniform light emission was confirmed by visual observation.

The voltage-current efficiency characteristics when a DC voltage of 4 V to 15 V is applied in an argon atmosphere to the organic electroluminescence elements produced in Examples 2 to 4 and Comparative Example 2 are shown in FIG. 3 . In addition, voltage-current efficiency characteristics when a DC voltage of 4 V to 15 V is applied in an argon atmosphere to the organic electroluminescent elements produced in Example 5 and Comparative Example 2 are shown in FIG. 4 . The element produced in Comparative Example 2 had a very large leakage current and did not emit light at all. On the other hand, it was found that the devices produced in Examples 2 to 5 had high current efficiency and suppressed leakage current. In addition, in the elements produced in Examples 2 to 5, very uniform light emission was confirmed by visual observation.

The voltage-current efficiency characteristics when a DC voltage of 4 V to 15 V is applied in an argon atmosphere to the organic electroluminescent elements produced in Example 6 and Comparative Example 3 are shown in FIG. 5 . The element produced in Comparative Example 3 had a very large leakage current, and immediately after emitting light for a moment, it did not emit light at all. On the other hand, it can be seen that the element fabricated in Example 6 has high current efficiency and suppressed leakage current. In addition, in the device produced in Example 6, very uniform light emission was confirmed by visual observation.

From the above, it has been confirmed that in an organic-inorganic hybrid organic electroluminescent device, a layer made of an organic compound can be coated and formed to achieve suppressed leakage current and uniform surface emission.

<Second organic electroluminescence element of the present invention>

In the following examples, the average thickness of each layer constituting the organic electroluminescent element was measured using a stylus profiler (product name "Alpha-Step IQ", manufactured by KLA TENCOR).

(Manufacturing of organic electroluminescent elements)

(Example 7)

[1] A commercially available transparent glass substrate with an ITO electrode layer having an average thickness of 0.7 mm was prepared. At this time, the ITO electrode (1st electrode) patterned by 2 mm width was used for the ITO electrode (1st electrode) of a board|substrate. The substrate was ultrasonically cleaned in acetone and isopropanol for 10 minutes, and then boiled in isopropanol for 5 minutes. This board|substrate was taken out from isopropanol, it was made to dry by nitrogen flow, and UV ozone cleaning was performed for 20 minutes.

[2] The substrate was fixed to a substrate holder of a facing-target sputtering apparatus having a zinc metal target. After the pressure was reduced to about 1×10 ^-4 Pa, sputtering was performed with argon and oxygen introduced to form a zinc oxide layer with a film thickness of about 2 nm. At this time, in order to take out the electrode, a metal mask was used together so that zinc oxide would not be formed on a part of the ITO electrode. This was fired in the air for 1 hour on a hot plate set at 400° C., whereby a zinc oxide layer (first metal oxide layer) was formed.

[3] The boron-containing compound 1 synthesized in the above synthesis example 1 was prepared as 0.2%, (4-(1,3-dimethyl-2,3-dihydro-1H-benzimidazol-2-yl)benzene Base) dimethylamine (N-DMBI) is a mixed solution of 0.002% 1,2-dichloroethane. The substrate with the zinc oxide thin film produced in step [2] was placed in a spin coater. The mixed solution of boron-containing compound 1 and N-DMBI was dropped onto the substrate, and rotated at 2000 rpm for 30 seconds to form a buffer layer containing a boron-containing organic compound. Furthermore, this was annealed for 1 hour in nitrogen atmosphere using the hotplate set to 100 degreeC. The average thickness of the buffer layer was 10 nm.

[4] The substrate until the boron-containing organic compound layer is formed is fixed to the substrate holder of the vacuum evaporation apparatus. Bis(10-hydroxybenzo[h]quinoline) beryllium (Bebq ₂ ), tris(1-phenylisoquinoline) iridium (Ir(piq) ₃ ), N,N'-bis(1- Naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (α-NPD) was added to the alumina crucible and placed in the evaporation source. The vacuum evaporation device was decompressed to about 1×10 ^-5 Pa, and Bebq ₂ was used as the main body and Ir(piq) ₃ was used as the dopant to co-evaporate 35 nm to form a light-emitting layer. At this time, the doping concentration was set so that Ir(piq) ₃ was 6% by weight relative to the entire light emitting layer. Next, 60 nm of α-NPD was evaporated to form a hole transport layer.

[5] Next, after purging nitrogen gas once, molybdenum trioxide and gold were added to the alumina crucible and placed in the evaporation source. The pressure in the vacuum deposition apparatus was reduced to about 1×10 ^-5 Pa, and molybdenum trioxide (second metal oxide layer) was deposited so as to form a film thickness of 10 nm. Next, gold (second electrode) was vapor-deposited so as to form a film thickness of 50 nm, thereby producing an organic electroluminescence element 2-1. When vapor-depositing the 2nd electrode, it carried out so that a vapor-deposition surface may become a band shape with a width of 2 mm using the vapor-deposition mask made of stainless steel. That is, the light emitting area of the produced organic electroluminescence element was set to 4 mm ² .

(comparative example 4)

In step [3], a 0.2% 1,2-dichloroethane solution of boron-containing compound 1 is used instead of a 1,2-dichloroethane mixed solution of 0.2% of boron-containing compound 1 and 0.002% of N-DMBI, Other than that, it carried out similarly to Example 7, and produced the organic electroluminescence element 2-2.

(Embodiment 8)

In step [3], use a 1,2-dichloroethane mixed solution containing 1% of boron-containing compound 1 and 0.01% of N-DMBI to replace 1,2-dichloroethane containing 0.2% of boron-containing compound 1 and 0.002% of N-DMBI, Except for the 2-dichloroethane mixed solution, the same procedure as in Example 7 was carried out to prepare the organic electroluminescence element 2-3. The average thickness of the buffer layer was 60 nm.

(comparative example 5)

In step [3], a 1% 1,2-dichloroethane solution of boron-containing compound 1 is used instead of a 1,2-dichloroethane mixed solution of 1% boron-containing compound 1 and 0.01% N-DMBI, Other than that, it carried out similarly to Example 8, and produced the organic electroluminescence element 2-4.

(Example 9)

Except having carried out process [4b] instead of process [4], it carried out similarly to Example 8, and produced the organic electroluminescence element 2-5.

[4b] The substrate after forming the boron-containing organic compound layer is fixed to the substrate holder of the vacuum deposition apparatus. Tris(8-hydroxyquinoline)aluminum (Alq ₃ ), N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4' - Diamine (α-NPD) is added to the alumina crucible and placed in the evaporation source. The vacuum evaporation apparatus was reduced to about 1×10 ^-4 Pa, and Alq ₃ was deposited with a thickness of 35 nm to form a light-emitting layer. Next, 60 nm of α-NPD was evaporated to form a hole transport layer.

(Example 10)

In step [3], instead of 1, 1% of boron-containing compound 1 and 0.01% of N-DMBI, a 1,2-dichloroethane mixed solution containing 1% of boron-containing compound 1 and 0.05% of N-DMBI is used, The 2-dichloroethane mixed solution was carried out in the same manner as in Example 7 except that, and organic electroluminescence element 2-6 was produced. The average thickness of the buffer layer was 60 nm.

(comparative example 6)

Except having carried out process [4b] instead of process [4], it carried out similarly to the comparative example 5, and produced the organic electroluminescence element 2-7.

(Example 11)

In step [3], a commercially available tetrahydrofuran mixed solution of 1% of poly(dioctylfluorene-alternating-benzothiadiazole) (F8BT) and 0.01% of N-DMBI was used instead of 1% of boron-containing compound 1 , and N-DMBI being 0.01% 1,2-dichloroethane mixed solution, it carried out similarly to Example 9, and obtained the organic electroluminescence element 2-8.

(comparative example 7)

In the step [3], the tetrahydrofuran solution of 1% F8BT was used instead of the tetrahydrofuran mixed solution of 1% F8BT and 0.01% N-DMBI, except that it was carried out in the same manner as in Example 10, and the organic electroluminescent element 2- 9.

(Example 12)

Except having carried out process [3b] instead of process [3], it carried out similarly to Example 9, and produced the organic electroluminescence element 2-10.

[3b] Prepare a mixed solution of 1,2-dichloroethane containing 1% of boron-containing compound 1 and 0.01% of leuco crystal violet. The substrate with the zinc oxide thin film produced in step [2] was placed in a spin coater. A mixed solution of boron-containing compound 1 and leuco crystal violet was dropped onto the substrate, and rotated at 2000 rpm for 30 seconds to form a buffer layer containing a boron-containing organic compound. Furthermore, this was annealed for 1 hour in nitrogen atmosphere using the hotplate set to 200 degreeC. The average thickness of the buffer layer was 60 nm.

(comparative example 8)

In step [3b], use 1% of boron-containing compound 1 in 1,2-dichloroethane instead of 1,2-dichloroethane mixed solution of boron-containing compound 1 and 0.01% leuco crystal violet , except that, it carried out similarly to Example 11, and produced the organic electroluminescence element 2-11.

(Example 13)

In step [3b], Hans ester (=2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate diethyl ester) was used instead of leuco crystal violet, and it was the same as the implementation Example 12 was carried out in the same manner, and organic electroluminescent element 2-12 was produced.

Table 1 shows a summary of the organic electroluminescent elements produced in Examples 7 to 13 and Comparative Examples 4 to 8. The weight % of the reducing agent is a ratio relative to the amount of the organic compound used in the buffer layer.

[Table 1]

(Measurement of Luminescence Characteristics of Organic Electroluminescent Devices)

A voltage was applied to the element and a current was measured using a "2400-type Source Meter" manufactured by Keithley Corporation. The emission luminance was measured using "LS-100" manufactured by Konica Minolta Corporation.

The voltage-brightness characteristics and current density-current efficiency characteristics when a DC voltage is applied in an argon atmosphere to the organic electroluminescence elements produced in Examples 7 to 13 and Comparative Examples 4 to 8 are shown in FIGS. 6 to 15 . It can be seen that in any case, the doped device produced in the example has higher luminance and current efficiency and excellent characteristics than the undoped device produced in the comparative example.

<The third organic electroluminescence element of the present invention>

(Manufacturing of organic electroluminescent elements)

(Example 14)

[1] A commercially available transparent glass substrate 1 with an ITO electrode layer having an average thickness of 0.7 mm was prepared. At this time, as the ITO electrode 2 of the substrate, an ITO electrode patterned with a width of 2 mm was used. The substrate was ultrasonically cleaned in acetone and isopropanol for 10 minutes, and then boiled in isopropanol for 5 minutes. This board|substrate was taken out from isopropanol, it was made to dry by nitrogen flow, and UV ozone cleaning was performed for 20 minutes.

[2] The substrate was fixed again to the substrate holder of the facing-target sputtering apparatus having a zinc metal target. After the pressure was reduced to about 1×10 ⁻⁴ Pa, sputtering was performed in a state where argon and oxygen were introduced to form a zinc oxide layer having a film thickness of about 2 nm as the first metal oxide layer 3 . At this time, in order to take out the electrode, a metal mask was used together so that zinc oxide would not be formed on a part of the ITO electrode.

[3] The substrate was subjected to the cleaning process of [1] again (after 10 minutes of ultrasonic cleaning in acetone and isopropanol, boiled in isopropanol for 5 minutes, and then dried with a nitrogen stream for 20 minutes. Minute UV ozone cleaning) followed by annealing on a hot plate at 400 °C for 1 h.

[4] Next, in order to form layer 4 of the nitrogen-containing film, polyethyleneimine (registered trademark: EPOMIN) manufactured by Nippon Shokubai Co., Ltd. was diluted to 0.5% by weight with ethanol, and then spin-coated at 2000 rpm for 30 seconds. .

The EPOMIN used here is sp003 with a molecular weight of 300.

[5] The thin film (substrate) prepared in [4] was annealed on a hot plate at 150° C. for 5 minutes in the atmosphere. The average thickness of the layer of the nitrogen-containing film measured after annealing was 5 nm.

[6] Next, the substrate processed in [5] is introduced into a vacuum device, and the pressure is reduced to 1×10 ^-4 Pa or less. As the organic compound layer 5 , 32.5 nm of Alq ₃ as a light-emitting layer and 60 nm of α-NPD as a hole transport layer were sequentially laminated by a vacuum evaporation method.

[7] Next, the second metal oxide layer 6 is formed on the organic compound layer 5 . Here, 10 nm of molybdenum oxide was formed by a vacuum deposition method which is a vapor phase film deposition method.

[8] Next, as a final step, the anode 7 is formed on the second metal oxide layer 6 . Here, an aluminum film of 150 nm was formed by a vacuum evaporation method.

[9] The characteristics of the organic electroluminescent element (voltage-current density/brightness characteristics, current density-current Efficiency characteristics, continuous drive characteristics at constant current density (corresponding to 100 cd/m ² , corresponding to 1000 cd/m ² )). The measurement results are shown in (a), (b), (c-1) and (c-2) of Figs. 17-1 and 17-2, respectively.

(Measurement of Luminescence Characteristics of Organic Electroluminescent Devices)

A voltage was applied to the element and a current was measured using a "2400-type Source Meter" manufactured by Keithley Corporation. The emission luminance was measured using "BM-7" manufactured by Topcon Corporation. Measurements were performed under an argon atmosphere.

(Measurement of Lifetime Characteristics of Organic Electroluminescent Devices)

Voltage application to the device and measurement of relative luminance were performed using an "organic EL lifetime measurement device" manufactured by System Engineers. In this device, the relative luminance is measured using a photodiode while automatically adjusting the voltage so that a constant current flows through the element. The current value was set for each element so that the luminance at the start of the measurement reached 100 cd/m ² and 1000 cd/m ² . These results in Examples and Comparative Examples are shown in (c-1) and (c-2).

It should be noted that the descriptions such as “t _1/2 = 200h@1000cd/m ² ” outside the columns of Figures (c-1) and (c-2) indicate the half-life. The brightness half-life when the current density corresponding to 1000 cd/m ² at the initial stage was continuously supplied was 200 hours.

(comparative example 9)

Steps [4] and [5] of Example 14 were omitted, and the organic electroluminescent element was produced in the same manner except that, and the voltage-current density/brightness characteristics and Current density-current efficiency characteristics. These results are shown in Fig. 18(a) and (b), respectively.

(Example 15)

The process of the process [4] of Example 14 was changed to the following [4-2], except that it was carried out in the same manner, an organic electroluminescent element was produced, and the organic electroluminescent element was measured in the same manner as in Example 14. The voltage-current density/brightness characteristics, current density-current efficiency characteristics, and continuous drive characteristics at a constant current density (corresponding to 1000 cd/m ² ) were obtained. These results are shown in (a), (b) and (c-2) of FIGS. 19-1 and 19-2, respectively. In addition, the average film thickness of the nitrogen-containing film layer was 6 nm.

[4-2] Next, in order to form the layer 4 of the nitrogen-containing film, dilute polyethyleneimine (registered trademark: EPOMIN) manufactured by Nippon Shokubai Co., Ltd. to 0.5% by weight with ethanol, and then set the temperature at 2000 rpm for 30 seconds. Perform spin coating. The EPOMIN used here is P1000 with a molecular weight of 70,000.

(Example 16)

The process of the process [4] [5] of Example 14 was changed to the following [4-3] [5-3], except that it was carried out in the same manner, and an organic electroluminescence element was produced, which was the same as in Example 14. The voltage-current density/luminance characteristics, current density-current efficiency characteristics, and continuous driving characteristics at a constant current density (corresponding to 1000 cd/m ² ) of the organic electroluminescent element were accurately measured. These results are shown in (a), (b) and (c-2) of FIGS. 20-1 and 20-2, respectively. In addition, the average film thickness of the nitrogen-containing film layer was 5 nm.

[4-3] Next, in order to form the layer 4 of the nitrogen-containing film, diethylenetriamine was diluted to 1.0% by weight with ethanol, and spin coating was performed at 2000 rpm for 30 seconds.

[5-3] The thin film (substrate) produced in [4-3] was annealed on a hot plate at 100° C. for 2 minutes in the atmosphere.

(Example 17)

The process [5] of Example 14 was omitted, and the organic electroluminescent element was produced in the same manner except that, and the voltage-current density/brightness characteristics and constant current density of the organic electroluminescent element were measured in the same manner as in Example 14. Continuous drive characteristics at lower (corresponding to 100cd/m ² ). These results are shown in Fig. 21(a) and (c-1), respectively. It should be noted that the film thickness of the nitrogen-containing film layer cannot be measured because the annealing is not performed, so the film is not cured, but according to the film thickness of the annealed nitrogen-containing film layer in Example 14 and known The film thickness is reduced by annealing in the atmosphere, so it is presumed to be about 10 nm.

(Example 18)

The process of the process [4] of Example 14 was changed to the above-mentioned [4-2], and the process of [5] was changed to the following [5-5], except that it was carried out in the same manner, and an organic electroluminescence For the device, the voltage-current density/brightness characteristics, current density-current efficiency characteristics, and continuous drive characteristics at a constant current density (corresponding to 100 cd/m ² ) of the organic electroluminescent device were measured in the same manner as in Example 14. These results are shown in (a), (b) and (c-1) of Figs. 22-1 and 22-2, respectively. In addition, the average film thickness of the nitrogen-containing film layer was 8 nm.

[5-5] The thin film (substrate) prepared in [4-2] was annealed on a hot plate at 100° C. for 10 minutes in the atmosphere.

(Example 19)

The process of the process [4] of Example 14 was changed to the above-mentioned [4-2], and the process of [5] was changed to the following [5-6], except that it was carried out in the same manner, and an organic electroluminescence For the device, the voltage-current density/brightness characteristics, current density-current efficiency characteristics, and continuous drive characteristics at a constant current density (corresponding to 100 cd/m ² ) of the organic electroluminescent device were measured in the same manner as in Example 14. These results are shown in (a), (b) and (c-1) of FIGS. 23-1 and 23-2, respectively. It should be noted that the average film thickness of the nitrogen-containing film layer was 7 nm.

[5-6] The thin film (substrate) prepared in [4-2] was annealed on a hot plate at 150° C. for 10 minutes in the atmosphere.

(Example 20)

The process of the process [4] of Example 14 was changed to the above-mentioned [4-2], and the process of [5] was changed to the following [5-7], except that it was carried out in the same manner, and an organic electroluminescence For the device, the voltage-current density/brightness characteristics, current density-current efficiency characteristics, and continuous drive characteristics at a constant current density (corresponding to 1000 cd/m ² ) of the organic electroluminescence device were measured in the same manner as in Example 14. These results are shown in (a), (b) and (c-2) of Figs. 24-1 and 24-2, respectively. In addition, the average film thickness of the nitrogen-containing film layer was 5 nm.

[5-7] The thin film (substrate) prepared in [4-2] was annealed on a hot plate at 150° C. for 30 minutes in the atmosphere.

(Example 21)

The process of the process [5] of Example 14 was changed to the following [5-8], except that it was carried out in the same manner, an organic electroluminescent element was produced, and the organic electroluminescent element was measured in the same manner as in Example 14. The voltage-current density/brightness characteristics, current density-current efficiency characteristics, and continuous driving characteristics at a constant current density (corresponding to 1000 cd/m ² ) were obtained. These results are shown in (a), (b) and (c-2) of Figs. 25-1 and 25-2, respectively. In addition, the average film thickness of the nitrogen-containing film layer was 5 nm.

[5-8] The thin film (substrate) produced in [4] was annealed on a hot plate at 100° C. for 30 minutes in the atmosphere.

(Example 22)

The process of the process [4] of Example 14 was changed to the above-mentioned [4-2], and the process of [5] was changed to the following [5-9], except that it was carried out in the same manner, and an organic electroluminescence For the device, the voltage-current density/brightness characteristics, current density-current efficiency characteristics, and continuous drive characteristics at a constant current density (corresponding to 100 cd/m ² ) of the organic electroluminescent device were measured in the same manner as in Example 14. These results are shown in (a), (b) and (c-1) of Figs. 26-1 and 26-2, respectively. In addition, the average film thickness of the nitrogen-containing film layer was 8 nm.

[5-9] The thin film (substrate) prepared in [4-2] was annealed on a hot plate at 150° C. for 10 minutes under nitrogen.

(Example 23)

The process of the process [5] of Example 14 was changed to the following [5-11], except that it was carried out in the same manner, an organic electroluminescent element was produced, and the organic electroluminescent element was measured in the same manner as in Example 14. The voltage-current density/brightness characteristics, current density-current efficiency characteristics, and continuous driving characteristics at a constant current density (corresponding to 1000 cd/m ² ) were obtained. These results are shown in (a), (b) and (c-2) of Figs. 27-1 and 27-2, respectively. In addition, the average film thickness of the nitrogen-containing film layer was 5 nm.

[5-11] The thin film (substrate) prepared in [4] was annealed on a hot plate at 150° C. for 5 minutes in the atmosphere. Then, it rinsed with ethanol.

(Manufacturing example 1)

The following photoelectron spectroscopy was performed on the nitrogen-containing film obtained by the operations of [1] to [5] in Example 14.

Quantitative analysis was performed by simultaneously measuring carbon 1S orbitals and nitrogen 1S orbitals.

These are shown in Fig. 28(d), (e).

(Measurement by X-ray photoelectron spectroscopy)

Measurement was carried out under the following conditions using a photoelectron spectrometer (JPS-9000MX) manufactured by JEOL Ltd.

X-ray source: MgKα

Beam output power (accelerating voltage-current): 10kV-10mA

Pass Energy: 10eV

Step size (Step): 0.1eV

(Manufacturing example 2)

The above-mentioned photoelectron spectroscopy measurement was performed on the nitrogen-containing film obtained by the operations of [1] to [4] in Example 14.

Quantitative analysis was performed by simultaneously measuring carbon 1S orbitals and nitrogen 1S orbitals.

These are shown in Fig. 29(d), (e).

(Manufacturing example 3)

The above-mentioned photoelectron spectroscopy was carried out on the nitrogen-containing film prepared by the steps [1] to [3] of Example 14 and the steps [4-12] and [5-12] below. In addition, the average film thickness of the nitrogen-containing film layer was 10 nm.

[4-12] Next, in order to form the layer 4 of the nitrogen-containing film, polyethyleneimine ethoxylate (molecular weight: 70000) manufactured by Aldrich was diluted to 0.4% by weight with ethoxyethanol and then heated at 5000rpm, 60 spin-coating in seconds.

[5-12] The thin film (substrate) prepared in [4-12] was annealed on a hot plate at 100° C. for 10 minutes in the atmosphere.

Quantitative analysis was performed by simultaneously measuring carbon 1S orbitals and nitrogen 1S orbitals.

These are shown in Fig. 30(d), (e).

(Manufacturing example 4)

The above-mentioned photoelectron spectroscopy measurement was carried out on the obtained nitrogen-containing film by sequentially performing the operations of [1] to [3] of Example 14, the following [4-13], and [5]. It should be noted that the film thickness of the nitrogen-containing film layer is such that the average film thickness cannot be estimated even through multiple measurements. From this, it is estimated that it is less than 3 nm.

[4-13] Next, in order to form the layer 4 of the nitrogen-containing film, polyethyleneimine (registered trademark: EPOMIN) manufactured by Nippon Shokubai Co., Ltd. was diluted to 0.125% by weight with ethanol and carried out at 2000 rpm for 30 seconds. spin coating. The EPOMIN used here is P1000 with a molecular weight of 70,000.

Quantitative analysis was performed by simultaneously measuring carbon 1S orbitals and nitrogen 1S orbitals.

These are shown in Fig. 31(d), (e).

(Example 24-1)

Change the steps [4] and [5] of Example 14 into the following [4-18] [5-18], except that it was carried out in the same manner, and an organic electroluminescent element was produced. The voltage-current density/brightness characteristics and current density-current efficiency characteristics of the organic electroluminescent element were measured in the same manner. These results are shown in Fig. 32(a) and (b), respectively. In addition, the average film thickness of the nitrogen-containing film layer was 10 nm.

[4-18] Next, in order to form the layer 4 of the nitrogen-containing film, linear polyethyleneimine (purchased from Polysciences, molecular weight: 25000) was diluted to 0.1% by weight with ethanol and then heated at 2000 rpm for 30 seconds. Spin coating under conditions.

[5-18] The thin film (substrate) prepared in [4-18] was annealed on a hot plate at 150° C. for 5 minutes in the atmosphere.

(Example 24-2)

The procedure [5-18] of Example 24-1 was omitted, and the organic electroluminescent element was produced in the same manner except that, and the voltage-current density/brightness of the organic electroluminescent element was measured in the same manner as in Example 14. characteristics, current density-current efficiency characteristics. These results are shown in Fig. 33(a) and (b), respectively. In addition, the average film thickness of the nitrogen-containing film layer was 12 nm.

(Example 25)

Change the steps [4] and [5] of Example 14 into the following [4-20] [5-20], except that it was carried out in the same manner, and an organic electroluminescent element was produced. The voltage-current density/brightness characteristics and current density-current efficiency characteristics of the organic electroluminescent element were measured in the same manner. These results are shown in Fig. 34(a) and (b), respectively. In addition, the average film thickness of the nitrogen-containing film layer was 10 nm.

[4-20] Next, in order to apply melamine resin as the nitrogen-containing compound for forming the layer 4 of the nitrogen-containing film, melamine and formaldehyde were mixed at a ratio of 1:3, and the mixed solution was dissolved in methanol:water at 0.1% by weight. = 1:1 mixed solvent and then spin-coated under the conditions of 2000 rpm and 30 seconds.

[5-20] The thin film (substrate) prepared in [4-20] was annealed on a hot plate at 80° C. for 60 minutes in the atmosphere.

(comparative example 10)

Change the steps [4] and [5] of Example 14 into the following [4-21] [5-21], except that it was carried out in the same manner, and an organic electroluminescent element was produced. The voltage-current density/brightness characteristics and current density-current efficiency characteristics of the organic electroluminescent element were measured in the same manner. These results are shown in Fig. 35(a) and (b), respectively.

[4-21] Next, a polystyrene film (10 nm) was formed by spin coating using toluene as an organic film not containing nitrogen, instead of layer 4 of the nitrogen-containing film.

[5-21] The thin film (substrate) prepared in [4-21] was annealed on a hot plate at 150° C. for 5 minutes in the atmosphere.

Regarding FIGS. 17 to 27 and FIGS. 32 to 35 , (a) to (c) respectively show the following contents.

(a) is the voltage-current density (black circle)/brightness (white circle) characteristic. First, the one with higher brightness is better. Second, those that can exhibit high brightness at a lower voltage are preferred.

(b) is the current density-current efficiency (black diamond) characteristic. First, it is desirable that the current efficiency (hereinafter expressed as "efficiency") be high. Second, it is also appropriate to keep it constant. Especially in the high current density region (high luminance region), it is preferable to be high and constant.

(c) shows the change with time of the voltage and the change of the relative luminance with time at a constant current (here, the current value at which the initial luminance reaches 1000 cd/m ² ). First, it is preferable that the relative luminance changes little with time (the initial luminance can be maintained for a long time) (hereinafter expressed as "long life"). Second, it is desirable that the voltage rise during the period be small, but this is related to the above-mentioned first.

The three elements of brightness, efficiency, and lifespan are all important, but practically speaking, lifespan should be the first priority.

On the premise of the above, the results of FIGS. 17 to 27 and 32 to 34 will be described.

Figure 17: It starts to emit light from a low voltage (about 2V), and reaches a high brightness of 3000cd/m ² at 6V. The overall efficiency is relatively high, more than 4cd/A. In addition, regarding the long-term change, it takes about 200 hours until the luminance is halved, and high reliability can be realized. Under another driving condition with an initial luminance of 100 cd/m ² , the half-life is estimated to be several thousand hours, so it can be seen that the reproducibility is also high.

FIG. 18 : FIG. 18 is a measurement result for an element having no layer between the metal oxide layer and the light emitting layer. It can be seen that both the luminance and the efficiency are less than 1/10 of those in FIG. 17 . In the measurement results below FIG. 19, since they are definitely superior to the values in FIG. 18, it is shown that the layer having the nitrogen-containing film is effective.

Figure 19: Although the efficiency is better than that of Figure 17 (the element of Example 14), the brightness drops sharply in the first few hours, and the result of Figure 17 is better in terms of lifetime. From this result, it is presumed that the element of Example 14 is superior in terms of stability under oxidation-reduction in the form of a film.

Figure 20: Brightness and efficiency are comparable to those shown in Figure 17 (components of Example 14). In terms of life, the transition up to about the first 10 hours is also the same as that in FIG. 17 . However, a result of rapid deterioration was obtained thereafter.

From the results shown in FIGS. 19 and 20 , even when polyethyleneimines with different molecular weights were used, there was no significant difference in the initial characteristics, and they were all superior to those without the nitrogen-containing film. However, divergent results were obtained in terms of long-term stability.

In Fig. 21 to Fig. 27 (Examples 17 to 23), the influence of the process (annealing conditions (temperature, time, atmosphere) and rinsing) on the device characteristics (process dependence) after coating a nitrogen-containing compound to form a film was confirmed. . In addition, the molecular weight dependence for them is shown.

FIG. 21 : shows the measurement results of device characteristics when liquid branched polyethyleneimine (low molecular weight) is used without annealing. Almost no light emission was observed, and it did not reach a level that could be called a characteristic.

Fig. 22 and Fig. 23: are the results of measuring the characteristics of devices obtained by using liquid branched polyethyleneimine (high molecular weight) and changing the annealing temperature. The device with high annealing temperature obtained good results in both brightness and efficiency. The effect of annealing temperature on lifetime is slightly significant, and the device annealed at high temperature has a good result that the half-life is more than doubled. It can be seen that the difference is due to the small decrease in brightness of the components annealed at high temperature at the initial stage. Including FIG. 21 , this suggests that annealing is effective for life extension, that is, long-term redox stability. Although not described here, when the annealing was performed at 200° C., the device was not measured because the color changed to brown. It is inferred from the above that there is an optimum value for the annealing temperature.

Fig. 24: Example 20 is the result of forming a nitrogen-containing film by changing the annealing time under the optimum value of the annealing temperature obtained from the results of Examples 17-19 (Figs. 21-23), that is, 150°C. Both brightness and efficiency are slightly lower than those in Fig. 23 (Example 19). In addition, regarding the life curve, it can be seen that the initial deterioration starts to appear a little stronger. It is inferred from the above that there is also an optimal value for the annealing time.

Figure 26: It is the result of studying the atmosphere for annealing under the above-mentioned optimum conditions. When the nitrogen-containing film was formed under nitrogen gas under the conditions shown in FIG. 23 (Example 19), there was no significant difference between the initial characteristics (brightness, efficiency) and FIG. 23 . It is inferred from the above that the effect of having a nitrogen-containing film here is the polarization between the metal-nitrogen in the case of physical adsorption (not the polarization between the metal-nitrogen in the case of chemical adsorption) and the polarization between the carbon-nitrogen in the molecule. The electron-withdrawing effect produced by polarization. It should be noted that the lifetime becomes extremely short in FIG. 26 . Based on the above, it is considered that the annealing process in the present invention that leads to a longer life is not only desolvation and a change in morphology, but is likely to be accompanied by a chemical change. (For what kind of chemical change, described below)

FIG. 25 : is the result of research based on the assumption that annealing conditions depend on the material, but also on the molecular weight of the material, based on the results of the above investigation.

For liquid branched polyethyleneimine (low molecular weight), annealing was carried out for a long time at a temperature lower than the optimum temperature. As a result, the brightness and efficiency of the initial characteristics were similar to those shown in Figure 17, but Higher values of current density were observed at the voltage before light emission as well as at reverse bias. This means that there is flow of useless current that does not contribute to light emission (hereinafter expressed as "leakage current"), and in many cases there is a problem in terms of long-term stability. Also this time, the luminance dropped sharply from the initial stage, and the lifetime was short, which is considered to be due to the above-mentioned leakage current.

From the above results, it was shown that the optimum value of the annealing condition also depends on the molecular weight of the material, although it certainly depends on the material. In addition, good properties cannot be obtained even if such annealing is performed for a long time at a temperature lower than the optimum temperature, which suggests that there is also a temperature threshold depending on the material and molecular weight.

Fig. 27: When the rinsing effect under the above optimal conditions (conditions of Example 14) is confirmed, the initial characteristics (brightness, efficiency) are approximately the same as those in Fig. 17 (Example 14), but the leakage current is slightly larger. It is considered that rinsing is the cause of deterioration in life characteristics compared with that in FIG. 17 (Example 14). However, although it does not appear in this figure, the characteristic unevenness among manufactured elements was reduced, and the reproducibility was improved. This is considered to be an important process from a practical viewpoint. It is believed that some improvement in lifespan can also be achieved by finding better rinsing conditions.

Figure 32 and Figure 33: are the results of using linear polyethyleneimine as the nitrogen-containing compound. Regardless of the presence or absence of annealing treatment, good initial characteristics (brightness, efficiency) were exhibited. The reason for this is considered to be that linear polyethyleneimine is solid, unlike branched polyethyleneimine. That is, the effects of annealing are presumed to be the following three points. (i) Allow it to cure. (ii) Provide strong bond types through rich and diverse metal-nitrogen bonds. (iii) Change the ratio of carbon element: nitrogen element to relatively increase the ratio of nitrogen element.

The effect of the above-mentioned annealing will be further described below.

Fig. 34: is the result of research on the application of melamine resin, which is a material with a high nitrogen ratio. Compared with FIG. 18 , favorable results were obtained, and it was confirmed that it is effective. Since there is also unevenness in light emission, it is considered that better results can be obtained if finer optimization conditions are found.

Figure 35: is the result of applying an organic membrane that does not contain nitrogen. In terms of initial characteristics, it can be seen that both brightness and efficiency are inferior to those in Fig. 19 . From this, it is considered that the organic film functions only as an insulating layer. In addition, the lifetime of this device is extremely short, a few minutes, and the mechanism of electron injection is expected to be caused by energy band bending of the light-emitting layer due to charge accumulation in the light-emitting layer. It is considered that the initial characteristics can be improved by studying the conditions in detail for polystyrene, but since the driving mechanism is as described above, it is considered that long-term reliable performance like the device of the present invention cannot be expected.

Next, FIGS. 28 to 31 (manufacturing examples 1 to 4) will be described.

In Production Examples 1 to 4, liquid branched polyethyleneimine could not be measured in all cases before the annealing of the nitrogen-containing film. On the other hand, it becomes possible to measure by annealing. This suggests that the annealing causes solidification by a certain effect (it cannot be concluded that it is decomposition only from this result) (the above-mentioned effect (i)).

The X-ray photoelectron spectroscopy measurement results (d) of the carbon 1s orbital and the X-ray photoelectron spectroscopy measurement results (e) of the nitrogen 1s orbital in FIGS. 28 to 31 are all measurement results after annealing. Before annealing, it was confirmed that C:N≈2:1 except in FIG. 30 . In Fig. 30, C: N ≈ 4: 1 before annealing. These ratios are values consistent with the stoichiometric ratios estimated from the chemical structures. The element abundance ratio was estimated from the ratio of the peak areas of the respective orbitals. In a comparison of FIG. 28 and FIG. 29 , it was confirmed that there are examples in which the ratio changes and examples in which the ratio does not change depending on the presence or absence of annealing. Due to annealing, the peak areas of both carbon and nitrogen decreased, but the reduction of the carbon peak was greater, resulting in a relative increase in the proportion of nitrogen elements. In FIG. 30 , there is no change after annealing compared to before annealing (stoichiometric ratio), so it can be seen that there is no significant chemical change. This suggests that the effects of thin films formed of polyethyleneimine and compounds obtained by modifying polyethyleneimine described in the above-mentioned Non-Patent Documents 1 to 3 are the same as those obtained by annealing in the present invention. The effect of changing the film of liquid branched polyethyleneimine (low molecular weight) was not equal. Fig. 31 is a result of performing the same annealing treatment by reducing liquid branched polyethyleneimine (high molecular weight) to a film equal to or higher than low molecular weight branched polyethyleneimine. In this result, the element abundance ratio of high-molecular-weight polyethyleneimine did not change, either. This suggests that the ratio of carbon element: nitrogen element will not change unless it is under a certain condition, for example, low molecular weight (the above-mentioned effect (iii)).

(f) of FIGS. 28 to 30 is a diagram showing the results of peak segmentation of the results of X-ray photoelectron spectroscopy measurement of nitrogen 1s orbitals. In this system, two types of bonds of nitrogen atoms are assumed to be carbon-nitrogen bonds and metal-nitrogen bonds. According to the existing literature, the peak on the lowest energy side is assigned to the metal-nitrogen bond. Furthermore, regarding the other peak, if it is assigned to a carbon-nitrogen bond, the energy difference between all two peaks is 0.6eV to 0.7eV, which is roughly the same, suggesting that the division and assignment of these peaks are correct.

It should be noted that, although not shown here, before annealing, in all the examples in FIGS. 28 to 30 , the half-peak widths are all 1.2 eV. From this, it is considered that in the case of FIG. 28 and FIG. 30 , the half-width increases, leading to a longer life (the aforementioned effect (ii)).

Based on the above considerations, in the example of FIG. 28 , all the effects of (i) to (iii) above are exhibited, and initial characteristics (luminance, efficiency) and long-term reliability (lifetime) can be realized. In FIG. 30 , it is presumed that the initial characteristics and a certain life can be realized due to (i) and (ii), and similarly, in FIG. 29 , it is presumed that the initial characteristics and a certain life can be realized due to the effect of (i). Although the above speculative content is not reflected in the results of X-ray photoelectron spectroscopy, the solid linear polyethyleneimine used in Figure 32 and Figure 33 is considered to be due to the realization of (i) without annealing effect but is also able to achieve a certain degree of longevity. The same is true in FIG. 34 .

From the above results, the following were revealed.

From comparison of FIG. 18 with other figures, it was confirmed that when the nitrogen-containing thin film is arranged on the oxide located on the lower cathode, the characteristics of the organic electroluminescent device such as luminance and efficiency are improved. Regarding the annealing treatment, it was confirmed from FIG. 33 that depending on the material, annealing may not be necessary, but annealing is not always necessary. However, it has been confirmed that by performing annealing, life characteristics corresponding to long-term reliability are improved in many cases. In addition, it has been confirmed that various nitrogen-containing compounds such as polyethyleneimine (different in molecular weight or different in shape <straight chain and branched>), diethylenetriamine, and melamine resin can be used as the materials used. In addition, it was also confirmed that they require selection of processes for materials, molecular weights, and shapes. In particular, linear polyethyleneimine is considered to exhibit an effect even without annealing because it is solid, unlike other polyethyleneimines. In addition, it was confirmed that rinsing after film formation is also effective.

Symbol Description

1: Substrate

2: Cathode

3: The first metal oxide layer

4: Nitrogen-containing film layer

5: Organic compound layer

6: The second metal oxide layer

7: anode

Claims (17)

1. an organic electroluminescent device, it is the organic electroluminescent device of the structure with the layer being laminated with more than 2 layers, it is characterized in that, this organic electroluminescent device has metal oxide layer between the 1st electrode and the 2nd electrode, and this metal oxide layer has the resilient coating formed by organic compound.

2. organic electroluminescent device as claimed in claim 1, it is characterized in that, described 1st electrode is the negative electrode formed on substrate, the resilient coating having metal oxide layer successively and formed by organic compound between the anode as described 2nd electrode.

3. organic electroluminescent device as claimed in claim 1 or 2, it is characterized in that, described resilient coating is that the average thickness formed is the layer of more than 3nm by being coated with the solution containing organic compound, and this resilient coating is formed on metal oxide layer in a neighboring manner.

4. the organic electroluminescent device according to any one of claims 1 to 3, is characterized in that, the layer of described resilient coating to be average thickness be 5nm ~ 50nm.

5. the organic electroluminescent device according to any one of Claims 1 to 4, is characterized in that, described organic compound is the organic compound with boron atom.

6. organic electroluminescent device as claimed in claim 5, it is characterized in that, described have the organic compound of boron atom for the boron-containing compound represented with following formula (1) or the boron polymer being carried out being polymerized by the monomer component containing the boron-containing compound represented with following formula (2) and obtain

[changing 1]

In formula (1), dotted line arc representation forms ring structure together with the skeleton part represented with solid line; Dotted portion in the skeleton part represented with solid line represent with dotted line connect 1 pair of atom with double bond connect or do not connect with double bond; The arrow pointing to boron atom from nitrogen-atoms represents that nitrogen-atoms is coordinated in boron atom; Q ¹and Q ²identical or different, they are the linking groups in the skeleton part represented with solid line, and at least local forms ring structure, their with or without substituting groups together with dotted line circular arc portion; X ¹, X ², X ³and X ⁴identical or different, represent hydrogen atom or as monovalent substituent substituent on ring structure, the ring structure of formation dotted line circular arc portion can be bonded with more than 2 X ¹, X ², X ³and X ⁴; n ¹represent the integer of 2 ~ 10; Y ¹for Direct Bonding or n ¹the linking group of valency, represents and existing n ¹individual except Y ¹structure division is in addition bonded in the ring structure, the Q that form dotted line circular arc portion independently of one another ¹, Q ², X ¹, X ², X ³, X ⁴in arbitrary place,

[changing 2]

In formula (2), dotted line arc representation forms ring structure with connection boron atom together with a part for the skeleton part of nitrogen-atoms; Connect boron atom and represent that at least 1 pair of atom is connected with double bond with the dotted portion in the skeleton part of nitrogen-atoms, this double bond and ring structure conjugation or non-conjugation; The arrow pointing to boron atom from nitrogen-atoms represents that nitrogen-atoms is coordinated in boron atom; X ⁵and X ⁶identical or different, represent hydrogen atom or as monovalent substituent substituent on ring structure, can bonding more than 2 X on the ring structure forming dotted line circular arc portion ⁵and X ⁶; R ¹and R ²identical or different, represent hydrogen atom or monovalent substituent; X ⁵, X ⁶, R ¹and R ²in at least one be the substituting group with reactive group.

7. the organic electroluminescent device according to any one of claims 1 to 3, is characterized in that, described resilient coating contains reducing agent.

8. organic electroluminescent device as claimed in claim 7, is characterized in that, described resilient coating is that the average thickness formed is the layer of 5nm ~ 100nm by being coated with the solution containing organic compound.

9. organic electroluminescent device as claimed in claim 7 or 8, it is characterized in that, described reducing agent is hydride reducer.

10. organic electroluminescent device as claimed in claim 9, it is characterized in that, described hydride reducer is for being selected from by 2,3-dihydrobenzo [d] imidazolium compounds, 2,3-dihydrobenzo [d] thiazolium compounds, 2,3-dihydrobenzos [at least one compound in the group of d] oxazole compounds, triphenylmethane compound and dihydropyridine compound composition.

11. organic electroluminescent devices according to any one of claims 1 to 3, it is characterized in that, described resilient coating is the average thickness be made up of nitrogenous film is the layer of 3nm ~ 150nm.

12. organic electroluminescent devices as claimed in claim 11, it is characterized in that, described nitrogenous film is formed by nitrogen-containing compound; Or containing nitrogen element and carbon as the element forming film, the ratio that exists of the nitrogen-atoms and carbon atom that form this film meets following relation:

Nitrogen-atoms number/(nitrogen-atoms number+carbon number) >1/8.

13. organic electroluminescent devices as described in claim 11 or 12, is characterized in that, by heating, nitrogen-containing compound are decomposed, form described nitrogenous film thus.

14. organic electroluminescent devices according to any one of claim 11 ~ 13, is characterized in that, described nitrogen-containing compound is polynary amine or the compound containing triazine ring.

15. 1 kinds of display unit, is characterized in that, it uses the organic electroluminescent device according to any one of claim 1 ~ 14 and is formed.

16. 1 kinds of lighting devices, is characterized in that, it uses the organic electroluminescent device according to any one of claim 1 ~ 14 and is formed.

The manufacture method of 17. 1 kinds of organic electroluminescent devices, it is the manufacture method of the organic electroluminescent device of the structure of the layer with lamination more than 2 layers, it is characterized in that, this manufacture method comprises and between the 1st electrode and the 2nd electrode, has the 1st metal oxide layer according to organic electroluminescent device successively, resilient coating, the low molecular compound layer comprising luminescent layer of lamination on this resilient coating, the operation of each layer of electro-luminescence element is configured with the mode lamination of the 2nd metal oxide layer, this lamination operation comprises coating and contains the solution of organic compound and form the operation that average thickness is the resilient coating of more than 3nm.