JP2009016579A - Organic electroluminescence device and manufacturing method - Google Patents

Abstract

An object of the present invention is to provide an organic EL element having high luminous efficiency and excellent driving durability and a manufacturing method thereof.
An organic electroluminescent element having an amorphous organic semiconductor thin film as at least a light emitting layer between a pair of electrodes, wherein the amorphous organic semiconductor thin film is measured in a measurement by a thermally stimulated current measurement method (TSC). It has a low temperature side peak in the region of temperatures from −200 ° C. to less than −100 ° C., and further has a high temperature side peak in the region of −100 ° C. to 50 ° C., and the intensity of the low temperature side peak is the intensity of the high temperature side peak An organic electroluminescent device characterized by being larger. The manufacturing method of the organic electroluminescent element which has the heat processing process of the said amorphous organic semiconductor thin film.
[Selection figure] None

Description

  The present invention relates to an organic electroluminescent device and a manufacturing method. In particular, the present invention relates to an organic electroluminescent element having high luminous efficiency and excellent durability and a manufacturing method.

  An organic electroluminescent element (hereinafter sometimes abbreviated as an organic EL element) is composed of a light emitting layer or a plurality of organic functional layers including a light emitting layer and a counter electrode sandwiching these layers. In the organic EL element, electrons injected from the cathode and holes injected from the anode are recombined in the light emitting layer, and the generated light from the excitons and energy transferred from at least one of the excitons are generated. It is an element for obtaining light emission utilizing light emission from excitons of molecules.

  Until now, organic EL elements have been developed with greatly improved brightness and element efficiency by using a laminated structure with separated functions. For example, a two-layer stacked device in which a hole transport layer and a light-emitting / electron transport layer are stacked, a three-layer stacked device in which a hole transport layer, a light-emitting layer, and an electron transport layer are stacked, a hole transport layer, and a light-emitting layer A four-layer stacked element in which a hole blocking layer and an electron transport layer are stacked is often used.

  However, many problems still remain in practical use of organic EL elements. The first is to achieve high luminous efficiency, and the second is to achieve high driving durability. In particular, quality degradation during continuous driving is the biggest problem.

It is known to heat-treat organic EL elements. For example, after manufacturing an organic EL element, it is disclosed that the driving voltage is reduced without changing the quantum efficiency by performing a heat treatment (see, for example, Patent Document 1). In a structure having a light-emitting region and a plurality of regions such as a hole-transport region and an electron-transport region adjacent to the light-emitting region between a pair of electrodes, the characteristics of each region are not uniformized by heat treatment. It is described that the factor that increased the drive voltage due to homogeneity is eliminated. This heating method does not improve the quantum efficiency of light emission. Alternatively, for example, it is disclosed that when a light emitting layer is provided by vacuum deposition and heat treatment is performed to cause aggregation of the light emitting material to form a microcrystalline aggregate structure, driving durability is improved (for example, patents). Reference 2). A material capable of forming an aggregate structure by heating is selected as the light emitting material, and heat treatment is performed at a temperature lower than the melting point of the light emitting material at 50 ° C. or higher. However, if the light emitting material forms an aggregated structure, the light emission efficiency decreases even if the durability is improved. Therefore, even if the driving durability is improved, the light emission efficiency is lowered. On the other hand, when the anode and the hole transport layer are formed on the substrate and then heat-treated at a temperature near the glass transition temperature of the hole transport material, the moisture permeability is lowered, and a failure called a dark spot may be improved. (For example, refer to Patent Document 3).
On the other hand, it is preferable that the organic semiconductor thin film of the organic EL element has a composition having substantially no localized level between the highest occupied level (HOMO) and the lowest unoccupied level (LUMO), and high charge mobility. It is disclosed that excellent luminous efficiency can be obtained. The absence of the localized level does not substantially show a peak current due to thermal stimulation in a temperature range of 100 K (−173 ° C.) to 200 K (−73 ° C.) as measured by a thermal stimulation current measurement method (TSC). (For example, refer to Patent Document 4).

To achieve both high external quantum efficiency and high driving durability is an extremely important issue in designing a practically useful organic EL device, and has always been a demand for improvement.
JP 2002-1000047 A JP-A-5-18264 Japanese Patent Laid-Open No. 9-266070 JP 2007-110094 A

  An object of the present invention is to provide an organic EL device having a high external quantum efficiency and a high driving durability and a manufacturing method thereof.

The above-described problems of the present invention have been solved by the following means.
<1> An organic electroluminescence device having an amorphous organic semiconductor thin film as at least a light emitting layer between a pair of electrodes, wherein the amorphous organic semiconductor thin film is measured at a temperature measured in a thermal stimulated current measurement method (TSC). It has a low temperature side peak in the region of −200 ° C. or more and less than −100 ° C., and further has a high temperature side peak in the region of −100 ° C. or more and 50 ° C. or less, and the intensity of the low temperature side peak is higher than the intensity of the high temperature side peak. An organic electroluminescent element characterized by being large.
<2> The organic electroluminescent element according to <1>, wherein the amorphous organic semiconductor thin film contains a host material and a light emitting material.
<3> The organic electroluminescent element according to <2>, wherein the light emitting material is a phosphorescent light emitting material.
<4> The relationship between the triplet lowest excitation level (T1 (H)) of the host material and the triplet lowest excitation level (T1 (G)) of the light emitting material is −2 Kcal / mol (−8.37 KJ / mol) ≦ T1 (H) −T1 (G) ≦ 5 Kcal / mol (20.9 KJ / mol), The organic electroluminescence device according to <2> or <3>.
<5> The organic electroluminescent element according to any one of <2> to <4>, wherein the light emitting material is a Pt complex.
<6> A method for producing an organic electroluminescent device having a light emitting layer containing at least an amorphous organic semiconductor thin film between a pair of electrodes, wherein at least one of constituent materials constituting the light emitting layer after the light emitting layer is formed A method for producing an organic electroluminescent device, comprising heat-treating at a temperature below the glass transition point of two constituent materials.
<7> The method according to <6>, wherein the amorphous organic semiconductor thin film contains a host material and a light emitting material.
<8> The method for producing an organic electroluminescent element according to <7>, wherein the temperature for the heat treatment is a temperature not higher than the glass transition point of the host material.
<9> The method for producing an organic electroluminescent element according to <7> or <8>, wherein the light emitting material is a phosphorescent light emitting material.
<10> The relationship between the triplet lowest excitation level (T1 (H)) of the host material and the triplet lowest excitation level (T1 (G)) of the light-emitting material is −2 Kcal / mol (−8.37 KJ / mol) ≦ T1 (H) −T1 (G) ≦ 5 Kcal / mol (20.9 KJ / mol), wherein the organic electroluminescent element according to any one of <7> to <9> Production method.
<11> The method for producing an organic electroluminescent element according to any one of <7> to <10>, wherein the light emitting material is a Pt complex.

  According to the present invention, an organic EL device and a manufacturing method can be provided. In particular, it is possible to provide an organic EL device having a high luminous efficiency and excellent driving durability and a manufacturing method.

The organic EL device of the present invention is an organic electroluminescent device having an amorphous organic semiconductor thin film as at least a light emitting layer between a pair of electrodes, and the amorphous organic semiconductor thin film is measured by a thermally stimulated current measurement method (TSC). In the measurement, the measurement temperature has a low temperature side peak in a region of −200 ° C. or more and less than −100 ° C., and further has a high temperature side peak in a region of −100 ° C. or more and 50 ° C. or less. It is characterized by being larger than the intensity of the side peak.
The present inventors have eagerly searched for a composition of a light emitting layer that achieves both high luminous efficiency and excellent driving durability characteristics. As a result, the TSC measurement shows two peak currents in different temperature regions, and the composition of which the peak current value in the low temperature region is higher than the peak current value in the high temperature region has both high luminous efficiency and excellent driving durability. I found out that Depending on the composition of the light emitting layer, there may be one that does not show any peak current, one that appears only one, two or more that appear, a low-temperature peak that appears strong at that time, or a high-temperature peak that appears strongly There are cases. Among them, the case where the intensity of the low temperature side peak is stronger than the intensity of the high temperature side peak is unique, and it was an unexpected discovery that the characteristics of both high luminous efficiency and excellent driving durability are compatible. It was. The case where the intensity of the low temperature side peak becomes stronger than the intensity of the high temperature side peak is preferably obtained when the organic semiconductor thin film is an amorphous organic semiconductor thin film and contains a host material and a light emitting material. More preferably, the light-emitting material is a phosphorescent light-emitting material, and the relationship between the triplet lowest excitation level (T1 (H)) of the host material and the triplet lowest excitation level (T1 (G)) of the light-emitting material is This is a case where −2 Kcal / mol (−8.37 KJ / mol) ≦ T1 (H) −T1 (G) ≦ 5 Kcal / mol (20.9 KJ / mol). Particularly preferably, the light emitting material is a Pt complex.

  Further, the method for producing an organic semiconductor thin film in which the intensity of the low temperature side peak is higher than the intensity of the high temperature side peak is a temperature below the glass transition point of at least one of the constituent materials constituting the thin film after the thin film is formed. Heat treatment is effective. Accordingly, the method for producing an organic electroluminescent device of the present invention is a method for producing an organic electroluminescent device having a luminescent layer containing at least an amorphous organic semiconductor thin film between a pair of electrodes, and after forming the luminescent layer. Heat treatment is performed at a temperature below the glass transition point of at least one constituent material of the constituent material constituting the light emitting layer. Preferably, the temperature for the heat treatment is a temperature below the glass transition point of the host material.

1. Thermally stimulated current measurement method (TSC)
The TSC method is a method in which a charge trapped in a localized level of an organic semiconductor thin film is released by heat, and the depth of the localized level is estimated from the charge emission temperature. The measurement process will be described below. FIG. 1 shows an energy level diagram of an organic semiconductor thin film. FIG. 2 shows a time-temperature profile (FIG. 2-a), a time-current profile (FIG. 2-b), a charge accumulation on a localized level, and an emission profile (FIG. 2-c) in each of the following processes. Is.

Process (a): A temperature lowering process. First, the temperature of the organic semiconductor thin film sample of the present invention is lowered from room temperature to 93 K (−180 ° C.) to suppress molecular motion in the organic thin film so that charges can be trapped at the localized levels.
Process (b): Light irradiation process. The light of a wavelength that can be absorbed by the organic semiconductor thin film sample of the present invention is irradiated, the material constituting the organic semiconductor thin film is excited, dissociated into holes and electrons, and a photocurrent flows. At this time, charges are trapped in the localized levels.
Process (c): Temperature rising process. When the temperature of the organic semiconductor thin film sample of the present invention is raised, electric charges are released from the localized levels and current flows. This current is measured.

At this time, the energy level (Ei) of the localized level is approximately obtained by the following formula (1).
Ei = K · Tm · ln (Tm ⁴ / a) Equation (1)
K: constant, 8.617 * 10 ⁻² [meV / K]
Tm: TSC peak temperature [K]
a: Rate of temperature increase [K / min]

  The organic semiconductor thin film according to the present invention has a low temperature side peak in a region where the measurement temperature is −200 ° C. or higher and lower than −100 ° C., and further has a high temperature side peak in a region where the temperature is −100 ° C. or higher and 50 ° C. or lower. The intensity of the low temperature side peak is greater than the intensity of the high temperature side peak. It is not clear what mechanism of the organic semiconductor film reflects the two energy levels. According to the analysis by the present inventors, it is presumed that the peak appearing at least in the low temperature region reflects the structure related to the stabilization of the light emitting material.

  The organic semiconductor thin film of the present invention can be measured by a thermally stimulated current measuring device TS-FETT manufactured by Rigaku Corporation. In the TSC measurement, the organic semiconductor thin film itself can be used as a sample, and measurement can be performed by using one of a pair of electrodes as a transparent electrode such as ITO. In TSC measurement, the rate of temperature rise is not particularly limited, but is preferably 1 K / min or more and 100 K / min, and more preferably 2 K / min or more and 50 K / min. If it is slower than this, the measurement is very time-consuming and inefficient. If it is earlier than this, the sample temperature does not follow the temperature rise, which is not preferable.

  In the above description, the photoexcitation method has been described as a method for trapping charges in the localized levels. However, in the present invention, an electric field is applied between the electrodes at 93 K (−180 ° C.), and charges are passed through the organic semiconductor thin film to localize the states. A charge may be trapped at a position. In this case, it is necessary to apply an electric field as long as the organic semiconductor thin film does not break down due to the electric field.

  FIG. 3 shows an example of a TSC curve of the amorphous organic semiconductor film according to the present invention. As detailed data shown in Example 1, a mixed film having a mass ratio of 13:87 of platinum complex Pt-1 as a light emitting material and 1,3-bis (N-carbazolyl) benzene (abbreviated as mCP) as a host material. It is. Two peak current values are given, the peak intensity on the low temperature side increases with heating, and the peak intensity on the high temperature side decreases conversely. The organic EL element using this thin film is improved in both light emission efficiency and driving durability by heat treatment.

  FIG. 4 shows an example of a TSC curve of a comparative amorphous organic semiconductor film. This behavior is observed in a mixed film having a mass ratio of 13:87 as an iridium complex B as a light emitting material and mCP as a host material. Only one current peak appears, and no substantial change is observed in the heat-stimulated current pattern even after heat treatment. Even if the organic EL element using this thin film is subjected to heat treatment, the light emission efficiency and the driving durability do not change.

  FIG. 5 shows an example of a TSC curve of another comparative amorphous organic semiconductor film. This is a behavior observed in a single film of tris (8-hydroxyquinolinate-hydroxyquino.nate) aluminum (abbreviated as Alq3). Only one current peak appears, and when the heat treatment is performed, the current peak shifts to the high temperature side. When the organic EL element using this thin film is subjected to heat treatment, the driving durability is improved, but the driving voltage is increased and the luminous efficiency is lowered.

2. Organic EL Element The organic EL element of the present invention has a pixel electrode and an upper electrode on a substrate, and an organic compound layer including an amorphous organic semiconductor thin film as a light emitting layer between both electrodes. In view of the properties of the light emitting element, at least one of the pixel electrode and the upper electrode is preferably transparent. One of the pixel electrode and the upper electrode is an anode, and the other is a cathode. Usually, the pixel electrode is an anode and the upper electrode is a cathode.

In the present invention, the organic compound layer is preferably laminated in the order of the hole transport layer, the light emitting layer, and the electron transport layer from the anode side. Further, a hole injection layer is provided between the hole transport layer and the anode, and / or an electron transporting intermediate layer is provided between the light emitting layer and the electron transport layer. Further, a hole transporting intermediate layer may be provided between the light emitting layer and the hole transport layer, and similarly, an electron injection layer may be provided between the cathode and the electron transport layer.
Each layer may be divided into a plurality of secondary layers.

  Each layer constituting the organic compound layer can be suitably formed by any of dry film forming methods such as vapor deposition and sputtering, transfer methods, printing methods, coating methods, ink jet methods, and spray methods.

  Next, elements constituting the light emitting device of the present invention will be described in detail.

(substrate)
The substrate used in the present invention is preferably a substrate that does not scatter or attenuate light emitted from the organic compound layer. Specific examples thereof include zirconia stabilized yttrium (YSZ), inorganic materials such as glass, polyesters such as polyethylene terephthalate, polybutylene phthalate, and polyethylene naphthalate, polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, and polycycloolefin. , Norbornene resins, and organic materials such as poly (chlorotrifluoroethylene).
For example, when glass is used as the substrate, alkali-free glass is preferably used as the material in order to reduce ions eluted from the glass. Moreover, when using soda-lime glass, it is preferable to use what gave barrier coatings, such as a silica. In the case of an organic material, it is preferable that it is excellent in heat resistance, dimensional stability, solvent resistance, electrical insulation, and workability.

  There is no restriction | limiting in particular about the shape of a board | substrate, a structure, a magnitude | size, It can select suitably according to the use, purpose, etc. of a light emitting element. In general, the shape of the substrate is preferably a plate shape. The substrate structure may be a single layer structure, a laminated structure, may be formed of a single member, or may be formed of two or more members.

  The substrate may be colorless and transparent or colored and transparent, but is preferably colorless and transparent in that it does not scatter or attenuate light emitted from the organic light emitting layer.

The substrate can be provided with a moisture permeation preventing layer (gas barrier layer) on the front surface or the back surface.
As a material for the moisture permeation preventive layer (gas barrier layer), inorganic materials such as silicon nitride and silicon oxide are preferably used. The moisture permeation preventing layer (gas barrier layer) can be formed by, for example, a high frequency sputtering method.
When a thermoplastic substrate is used, a hard coat layer, an undercoat layer, or the like may be further provided as necessary.

(anode)
The anode usually has a function as an electrode for supplying holes to the organic compound layer, and there is no particular limitation on the shape, structure, size, etc., depending on the use and purpose of the light-emitting element. , Can be appropriately selected from known electrode materials. As described above, the anode is usually provided as a transparent anode.

  Suitable examples of the material for the anode include metals, alloys, metal oxides, conductive compounds, and mixtures thereof. Specific examples of the anode material include conductive metals such as tin oxide doped with antimony and fluorine (ATO, FTO), tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO). Metals such as oxides, gold, silver, chromium, nickel, and mixtures or laminates of these metals and conductive metal oxides, inorganic conductive materials such as copper iodide and copper sulfide, polyaniline, polythiophene, polypyrrole, etc. Organic conductive materials, and a laminate of these and ITO. Among these, conductive metal oxides are preferable, and ITO is particularly preferable from the viewpoints of productivity, high conductivity, transparency, and the like.

  The anode is composed of, for example, a wet method such as a printing method and a coating method, a physical method such as a vacuum deposition method, a sputtering method, and an ion plating method, and a chemical method such as a CVD and a plasma CVD method. It can be formed on the substrate according to a method appropriately selected in consideration of suitability with the material to be processed. For example, when ITO is selected as the anode material, the anode can be formed according to a direct current or high frequency sputtering method, a vacuum deposition method, an ion plating method, or the like.

  In the organic electroluminescent element of the present invention, the formation position of the anode is not particularly limited and can be appropriately selected according to the use and purpose of the light emitting element. Is preferably formed on the substrate. In this case, the anode may be formed on the entire one surface of the substrate, or may be formed on a part thereof.

  The patterning for forming the anode may be performed by chemical etching such as photolithography, or may be performed by physical etching such as laser, or vacuum deposition or sputtering with a mask overlapped. It may be performed by a lift-off method or a printing method.

  The thickness of the anode can be appropriately selected depending on the material constituting the anode and cannot be generally defined, but is usually about 10 nm to 50 μm, and preferably 50 nm to 20 μm.

The resistance value of the anode is preferably 10 ³ Ω / □ or less, and more preferably 10 ² Ω / □ or less. When the anode is transparent, it may be colorless and transparent or colored and transparent. In order to take out light emission from the transparent anode side, the transmittance is preferably 60% or more, and more preferably 70% or more.

  Note that the transparent anode is described in detail in Yutaka Sawada's “New Development of Transparent Electrode Film” published by CMC (1999), and the matters described here can be applied to the present invention. In the case of using a plastic substrate having low heat resistance, a transparent anode formed using ITO or IZO at a low temperature of 150 ° C. or lower is preferable.

(cathode)
The cathode usually has a function as an electrode for injecting electrons into the organic compound layer, and there is no particular limitation on the shape, structure, size, etc., depending on the use and purpose of the light-emitting element, It can select suitably from well-known electrode materials.

  Examples of the material constituting the cathode include metals, alloys, metal oxides, electrically conductive compounds, and mixtures thereof. Specific examples include alkali metals (eg, Li, Na, K, Cs, etc.), alkaline earth metals (eg, Mg, Ca, etc.), gold, silver, lead, aluminum, sodium-potassium alloys, lithium-aluminum alloys, magnesium. -Rare earth metals such as silver alloys, indium and ytterbium. These may be used alone, but two or more can be suitably used in combination from the viewpoint of achieving both stability and electron injection.

Among these, as a material constituting the cathode, an alkali metal or an alkaline earth metal is preferable from the viewpoint of electron injecting property, and a material mainly composed of aluminum is preferable from the viewpoint of excellent storage stability.
The material mainly composed of aluminum is aluminum alone, an alloy of aluminum and 0.01% by mass to 10% by mass of alkali metal or alkaline earth metal, or a mixture thereof (for example, lithium-aluminum alloy, magnesium-aluminum alloy). Etc.).

  The materials for the cathode are described in detail in JP-A-2-15595 and JP-A-5-121172, and the materials described in these public relations can also be applied in the present invention.

  There is no restriction | limiting in particular about the formation method of a cathode, According to a well-known method, it can carry out. For example, the cathode described above is configured from a wet method such as a printing method or a coating method, a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method, or a chemical method such as CVD or plasma CVD method. It can be formed according to a method appropriately selected in consideration of suitability with the material. For example, when a metal or the like is selected as the cathode material, one or more of them can be simultaneously or sequentially performed according to a sputtering method or the like.

  Patterning when forming the cathode may be performed by chemical etching such as photolithography, physical etching by laser, or the like, or by vacuum deposition or sputtering with the mask overlaid. It may be performed by a lift-off method or a printing method.

In the present invention, the cathode formation position is not particularly limited, and may be formed on the entire organic compound layer or a part thereof.
Further, a dielectric layer made of an alkali metal or alkaline earth metal fluoride or oxide may be inserted between the cathode and the organic compound layer with a thickness of 0.1 nm to 5 nm. This dielectric layer can also be regarded as a kind of electron injection layer. The dielectric layer can be formed by, for example, a vacuum deposition method, a sputtering method, an ion plating method, or the like.

The thickness of the cathode can be appropriately selected depending on the material constituting the cathode and cannot be generally defined, but is usually about 10 nm to 5 μm, and preferably 50 nm to 1 μm.
Further, the cathode may be transparent or opaque. The transparent cathode can be formed by depositing a thin cathode material to a thickness of 1 nm to 10 nm and further laminating a transparent conductive material such as ITO or IZO.

(Organic compound layer)
The organic compound layer in the present invention will be described.
The organic EL device of the present invention has at least one organic compound layer including a light emitting layer, and as the organic compound layer other than the light emitting layer, as described above, a hole transport layer, an electron transport layer, a charge Examples of the layer include a block layer, a hole injection layer, and an electron injection layer.

  In the organic EL device of the present invention, each layer constituting the organic compound layer is preferably formed by any of dry film forming methods such as vapor deposition and sputtering, wet coating methods, transfer methods, printing methods, and ink jet methods. Can do.

(Light emitting layer)
The organic light emitting layer receives holes from the anode, the hole injection layer, or the hole transport layer when an electric field is applied, receives electrons from the cathode, the electron injection layer, or the electron transport layer, and recombines holes and electrons. It is a layer having a function of providing a field to emit light.
The light emitting layer in the present invention is a thin film containing an amorphous organic semiconductor.
The light emitting layer may be composed of only a light emitting material, but preferably has a mixed layer of a host material and a light emitting material (also referred to as a light emitting dopant).
The light emitting material may be a fluorescent light emitting material or a phosphorescent light emitting material, but is preferably a phosphorescent light emitting material.
The host material is preferably a charge transport material. The host material may be one type or two or more types, and examples thereof include a configuration in which an electron transporting host material and a hole transporting host material are mixed. Further, the light emitting layer may include a material that does not have charge transporting properties and does not emit light.
In the present invention, the relationship between the triplet lowest excitation level (T1 (H)) of the host material and the triplet lowest excitation level (T1 (G)) of the light-emitting material is −2 Kcal / mol (−8.37 KJ / mol). ≦ T1 (H) −T1 (G) ≦ 5 Kcal / mol (20.9 KJ / mol) is preferable.
If it is less than -2 Kcal / mol (-8.37 KJ / mol), it is not preferable in that the light emission efficiency is lowered, and if it exceeds 5 Kcal / mol (20.9 KJ / mol), the peak on the low temperature side becomes small in TSC, resulting in high efficiency. This is not preferable in that a highly durable element cannot be obtained.

  The light emitting layer in the present invention can contain two or more kinds of light emitting materials in order to improve the color purity and widen the light emission wavelength region. Further, the light emitting layer may be a single layer or two or more layers, and each layer may emit light in different emission colors.

《Phosphorescent dopant》
In general, examples of the phosphorescent light-emitting dopant include complexes containing a transition metal atom or a lanthanoid atom.
For example, the transition metal atom is not particularly limited, but preferably includes ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium, gold, silver, copper, and platinum, and more preferably rhenium, iridium. And platinum, more preferably iridium and platinum.
Examples of the lanthanoid atom include lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Among these lanthanoid atoms, neodymium, europium, and gadolinium are preferable.

Examples of the ligand of the complex include G.I. Wilkinson et al., Comprehensive Coordination Chemistry, Pergamon Press, 1987, H.C. Examples include ligands described in Yersin's "Photochemistry and Photophysics of Coordination Compounds" published by Springer-Verlag 1987, Akio Yamamoto "Organic Metal Chemistry-Fundamentals and Applications-" .
The specific ligand is preferably a halogen ligand (preferably a chlorine ligand) or an aromatic carbocyclic ligand (for example, preferably 5 to 30 carbon atoms, more preferably 6 to 6 carbon atoms). 30 and more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as cyclopentadienyl anion, benzene anion, or naphthyl anion), nitrogen-containing heterocyclic ligand (for example, preferably Has 5 to 30 carbon atoms, more preferably 6 to 30 carbon atoms, still more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, and phenylpyridine, benzoquinoline, quinolinol, bipyridyl, or phenanthroline. Etc.), diketone ligand (for example, acetylacetone, etc.), carboxylic acid ligand (for example, preferably 2-30 carbon atoms, and more) Preferably, it has 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, such as an acetic acid ligand), an alcoholate ligand (for example, preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms). More preferably, it has 6 to 20 carbon atoms, such as phenolate ligand), silyloxy ligand (for example, preferably 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, still more preferably 3 to 3 carbon atoms). 20 such as trimethylsilyloxy ligand, dimethyl-tert-butylsilyloxy ligand, triphenylsilyloxy ligand), carbon monoxide ligand, isonitrile ligand, cyano ligand, Phosphorus ligand (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, still more preferably 3 to 20 carbon atoms, and particularly preferably 6 to 20 carbon atoms. A rephenylphosphine ligand), a thiolato ligand (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, still more preferably 6 to 20 carbon atoms, such as a phenylthiolato ligand) ), A phosphine oxide ligand (preferably having 3 to 30 carbon atoms, more preferably 8 to 30 carbon atoms, still more preferably 18 to 30 carbon atoms, such as a triphenylphosphine oxide ligand). More preferably, it is a nitrogen-containing heterocyclic ligand.
The complex may have one transition metal atom in the compound, or may be a so-called binuclear complex having two or more. Different metal atoms may be contained at the same time.

  Among these, specific examples of the luminescent dopant include, for example, US6303238B1, US6097147, WO00 / 57676, WO00 / 70655, WO01 / 08230, WO01 / 39234A2, WO01 / 41512A1, WO02 / 02714A2, WO02 / 15645A1, WO02 / 44189A1. , WO 05/19373 A2, JP 2001-247859, JP 2002-302671, JP 2002-117978, JP 2003-133074, JP 2002-235076, JP 2003-123982, JP 2002-170684, EP 12112257, Special JP 2002-226495, JP 2002-234894, JP 2001247478, JP 2001-298470, JP 2002 73674, JP 2002-203678, JP 2002-203679, JP 2004-357799, JP 2006-256999, JP 2007-19462, JP 2007-84635, JP 2007-96259, and the like. Phosphorescent compounds and the like are mentioned. Among them, more preferable luminescent dopants include Ir complex, Pt complex, Cu complex, Re complex, W complex, Rh complex, Ru complex, Pd complex, Os complex, Eu complex, Tb complex. , Gd complex, Dy complex, and Ce complex. Particularly preferred is an Ir complex, a Pt complex, or a Re complex, among which an Ir complex or a Pt complex containing at least one coordination mode of a metal-carbon bond, a metal-nitrogen bond, a metal-oxygen bond, and a metal-sulfur bond. Or a Re complex. Furthermore, from the viewpoints of luminous efficiency, driving durability, chromaticity, etc., an Ir complex, a Pt complex, or a Re complex containing a tridentate or higher polydentate ligand is particularly preferable. Most preferred for the present invention is a Pt complex.

《Fluorescent luminescent dopant》
As the fluorescent light-emitting dopant, generally, benzoxazole, benzimidazole, benzothiazole, styrylbenzene, polyphenyl, diphenylbutadiene, tetraphenylbutadiene, naphthalimide, coumarin, pyran, perinone, oxadiazole, aldazine, Pyraridin, cyclopentadiene, bisstyrylanthracene, quinacridone, pyrrolopyridine, thiadiazolopyridine, cyclopentadiene, styrylamine, aromatic dimethylidin compounds, condensed polycyclic aromatic compounds (anthracene, phenanthroline, pyrene, perylene, rubrene, pentacene, etc. ), 8-quinolinol metal complexes, various metal complexes represented by pyromethene complexes and rare earth complexes, polythiophene, polyphenylene, polyphenylene Polymeric compounds such as vinylene, organic silane, and the like, and their derivatives.

  Among these, specific examples of the luminescent dopant include the following, but are not limited thereto.

  The light-emitting dopant in the light-emitting layer is contained in an amount of 0.1% by mass to 50% by mass with respect to the total compound mass generally forming the light-emitting layer in the light-emitting layer. To 1 mass% to 50 mass%, and more preferably 2 mass% to 40 mass%.

  Although the thickness of the light emitting layer is not particularly limited, it is usually preferably 2 nm to 500 nm, more preferably 3 nm to 200 nm, and more preferably 5 nm to 100 nm from the viewpoint of external quantum efficiency. More preferably.

<Host material>
As the host material used in the present invention, a hole-transporting host material excellent in hole-transporting property (sometimes referred to as a hole-transporting host) and an electron-transporting host material excellent in electron-transporting property (electron-transporting property) May be described as a host).

《Hole-transporting host》
Specific examples of the hole-transporting host used in the present invention include the following materials.
Pyrrole, indole, carbazole, azaindole, azacarbazole, triazole, oxazole, oxadiazole, pyrazole, imidazole, thiophene, polyarylalkane, pyrazoline, pyrazolone, phenylenediamine, arylamine, amino-substituted chalcone, styrylanthracene, fluorenone, hydrazone , Stilbene, silazane, aromatic tertiary amine compound, styrylamine compound, aromatic dimethylidin compound, porphyrin compound, polysilane compound, poly (N-vinylcarbazole), aniline copolymer, thiophene oligomer, polythiophene, etc. Conductive polymer oligomers, organic silanes, carbon films, and derivatives thereof.
Preferred are indole derivatives, carbazole derivatives, aromatic tertiary amine compounds, and thiophene derivatives, and more preferred are those having a carbazole group in the molecule.

《Electron transporting host》
The electron transporting host in the light emitting layer used in the present invention preferably has an electron affinity Ea of 2.5 eV or more and 3.5 eV or less from the viewpoint of improving durability and lowering driving voltage. More preferably, it is 0.4 eV or less, and further preferably 2.8 eV or more and 3.3 eV or less. Further, from the viewpoint of improving durability and reducing driving voltage, the ionization potential Ip is preferably 5.7 eV or more and 7.5 eV or less, more preferably 5.8 eV or more and 7.0 eV or less, and 5.9 eV or more. More preferably, it is 6.5 eV or less.

Specific examples of such an electron transporting host include the following materials.
Pyridine, pyrimidine, triazine, imidazole, pyrazole, triazole, oxazole, oxadiazol, fluorenone, anthraquinodimethane, anthrone, diphenylquinone, thiopyran dioxide, carbodiimide, fluorenylidenemethane, distyrylpyrazine, Fluorine-substituted aromatic compounds, heterocyclic tetracarboxylic anhydrides such as naphthaleneperylene, phthalocyanines, and derivatives thereof (may form condensed rings with other rings), metal complexes and metals of 8-quinolinol derivatives Examples thereof include various metal complexes represented by metal complexes having phthalocyanine, benzoxazole or benzothiazol as a ligand.

Preferred examples of the electron transporting host include metal complexes, azole derivatives (benzimidazole derivatives, imidazopyridine derivatives, etc.), and azine derivatives (pyridine derivatives, pyrimidine derivatives, triazine derivatives, etc.). To metal complex compounds are preferred. The metal complex compound (A) is more preferably a metal complex having a ligand having at least one nitrogen atom, oxygen atom or sulfur atom coordinated to the metal.
The metal ion in the metal complex is not particularly limited, but is preferably beryllium ion, magnesium ion, aluminum ion, gallium ion, zinc ion, indium ion, tin ion, platinum ion, or palladium ion, more preferably beryllium ion, Aluminum ion, gallium ion, zinc ion, platinum ion, or palladium ion, and more preferably aluminum ion, zinc ion, or palladium ion.

  There are various known ligands contained in the metal complex. For example, “Photochemistry and Photophysics of Coordination Compounds”, Springer-Verlag, H.C. Examples include the ligands described in Yersin, published in 1987, “Organometallic Chemistry: Fundamentals and Applications”, Sakai Hanafusa, Yamamoto Akio, published in 1982, and the like.

The ligand is preferably a nitrogen-containing heterocyclic ligand (preferably having 1 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 3 to 15 carbon atoms, and a monodentate ligand. Alternatively, it may be a bidentate or higher ligand, preferably a bidentate or higher and a hexadentate or lower ligand, or a bidentate or higher and lower 6 or lower ligand and a monodentate mixed ligand. preferable.
Examples of the ligand include an azine ligand (for example, pyridine ligand, bipyridyl ligand, terpyridine ligand, etc.), a hydroxyphenylazole ligand (for example, hydroxyphenylbenzimidazole coordination). And a hydroxyphenyl benzoxazole ligand, a hydroxyphenyl imidazole ligand, a hydroxyphenylimidazopyridine ligand, etc.), an alkoxy ligand (preferably having 1 to 30 carbon atoms, more preferably 1 carbon atom). To 20, particularly preferably 1 to 10 carbon atoms, such as methoxy, ethoxy, butoxy, 2-ethylhexyloxy), aryloxy ligands (preferably 6 to 30 carbon atoms, more preferably 6-20 carbon atoms, particularly preferably 6-12 carbon atoms, for example phenyl Carboxymethyl, 1-naphthyloxy, 2-naphthyloxy, 2,4,6-trimethylphenyl oxy, and 4-biphenyloxy and the like.),

Heteroaryloxy ligand (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include pyridyloxy, pyrazyloxy, pyrimidyloxy, and quinolyloxy. ), An alkylthio ligand (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio and ethylthio), arylthio ligands (Preferably 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio), heteroarylthio ligand (preferably 1 carbon atom) To 30, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as pyridylthio , 2-benzimidazolylthio, 2-benzoxazolylthio, 2-benzthiazolylthio, etc.), a siloxy ligand (preferably having 1 to 30 carbon atoms, more preferably 3 to 25 carbon atoms). Particularly preferably, it has 6 to 20 carbon atoms, and examples thereof include a triphenylsiloxy group, a triethoxysiloxy group, and a triisopropylsiloxy group.), An aromatic hydrocarbon anion ligand (preferably having 6 carbon atoms) To 30, more preferably 6 to 25 carbon atoms, particularly preferably 6 to 20 carbon atoms, such as a phenyl anion, a naphthyl anion, an anthranyl anion, etc.), an aromatic heterocyclic anion ligand (preferably Has 1 to 30 carbon atoms, more preferably 2 to 25 carbon atoms, and particularly preferably 2 to 20 carbon atoms. Pyrrole anion, pyrazole anion, pyrazole anion, triazole anion, oxazole anion, benzoxazole anion, thiazole anion, benzothiazole anion, thiophene anion, benzothiophene anion, etc.), indolenine anion ligand, etc. , Preferably a nitrogen-containing heterocyclic ligand, aryloxy ligand, heteroaryloxy group, or siloxy ligand, more preferably a nitrogen-containing heterocyclic ligand, aryloxy ligand, siloxy coordination Or an aromatic hydrocarbon anion ligand or an aromatic heterocyclic anion ligand.

  Examples of the metal complex electron transporting host are described in, for example, JP-A No. 2002-235076, JP-A No. 2004-214179, JP-A No. 2004-221106, JP-A No. 2004-221665, JP-A No. 2004-221068, JP-A No. 2004-327313, and the like. The compound of this is mentioned.

  Further, the content of the host material in the present invention is not particularly limited, but from the viewpoint of light emission efficiency and driving voltage, it is 15% by mass or more and 95% by mass or less based on the total compound mass forming the light emitting layer. Preferably there is.

  The host material used in the present invention preferably has a glass transition point of 50 ° C. or higher and 150 ° C. or lower. More preferably, the glass transition point is 60 ° C. or higher and 150 ° C. or lower. If the glass transition point of the host material is less than 50 ° C., it is not preferable in terms of the heat resistance of the device, and if it exceeds 150 ° C., it is not preferable in that heat treatment after film formation becomes difficult.

  Among these, specific examples of the host material in the present invention include the following, but are not limited thereto.

(Hole injection layer, hole transport layer)
The hole injection layer and the hole transport layer are layers having a function of receiving holes from the anode or the anode side and transporting them to the cathode side. The hole injection material and the hole transport material used for these layers may be a low molecular compound or a high molecular compound.
Specifically, pyrrole derivatives, carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styryl Anthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidin compounds, phthalocyanine compounds, porphyrin compounds, thiophene derivatives, organosilane derivatives, carbon, And the like.

  An electron-accepting dopant can be contained in the hole injection layer or the hole transport layer of the organic EL device of the present invention. As the electron-accepting dopant introduced into the hole-injecting layer or the hole-transporting layer, an inorganic compound or an organic compound can be used as long as it has an electron-accepting property and oxidizes an organic compound.

  Specifically, examples of the inorganic compound include metal halides such as ferric chloride, aluminum chloride, gallium chloride, indium chloride, and antimony pentachloride, metal oxides such as vanadium pentoxide, and molybdenum trioxide.

In the case of an organic compound, a compound having a nitro group, halogen, cyano group, trifluoromethyl group or the like as a substituent, a quinone compound, an acid anhydride compound, fullerene, or the like can be preferably used.
In addition, JP-A-6-212153, JP-A-11-111463, JP-A-11-251067, JP-A-2000-196140, JP-A-2000-286054, JP-A-2000-315580, JP-A-2001-102175, JP-A-2001-2001. -160493, JP2002-252085, JP2002-56985, JP2003-157981, JP2003-217862, JP2003-229278, JP2004-342614, JP2005-72012, JP20051666667 The compounds described in JP-A-2005-209643 and the like can be preferably used.

  Among these, hexacyanobutadiene, hexacyanobenzene, tetracyanoethylene, tetracyanoquinodimethane, tetrafluorotetracyanoquinodimethane, p-fluoranyl, p-chloranil, p-bromanyl, p-benzoquinone, 2,6-dichlorobenzoquinone, 2 , 5-dichlorobenzoquinone, 1,2,4,5-tetracyanobenzene, 1,4-dicyanotetrafluorobenzene, 2,3-dichloro-5,6-dicyanobenzoquinone, p-dinitrobenzene, m-dinitrobenzene, o-dinitrobenzene, 1,4-naphthoquinone, 2,3-dichloronaphthoquinone, 1,3-dinitronaphthalene, 1,5-dinitronaphthalene, 9,10-anthraquinone, 1,3,6,8-tetranitrocarbazole, 2,4,7-trinitro-9- Luenone, 2,3,5,6-tetracyanopyridine or fullerene C60 is preferred, and hexacyanobutadiene, hexacyanobenzene, tetracyanoethylene, tetracyanoquinodimethane, tetrafluorotetracyanoquinodimethane, p-fluoranyl, p- Chloranil, p-bromanyl, 2,6-dichlorobenzoquinone, 2,5-dichlorobenzoquinone, 2,3-dichloronaphthoquinone, 1,2,4,5-tetracyanobenzene, 2,3-dichloro-5,6-dicyano Benzoquinone or 2,3,5,6-tetracyanopyridine is more preferred, and tetrafluorotetracyanoquinodimethane is particularly preferred.

  These electron-accepting dopants may be used alone or in combination of two or more. Although the usage-amount of an electron-accepting dopant changes with kinds of material, it is preferable that it is 0.01 mass%-50 mass% with respect to hole transport layer material, and it is 0.05 mass%-20 mass%. It is further more preferable and it is especially preferable that it is 0.1 mass%-10 mass%.

The thicknesses of the hole injection layer and the hole transport layer are each preferably 500 nm or less from the viewpoint of lowering the driving voltage.
The thickness of the hole transport layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm. In addition, the thickness of the hole injection layer is preferably 0.1 nm to 200 nm, more preferably 0.5 nm to 100 nm, and still more preferably 1 nm to 100 nm.
The hole injection layer and the hole transport layer may have a single-layer structure composed of one or more of the materials described above, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions. .

(Electron injection layer, electron transport layer)
The electron injection layer and the electron transport layer are layers having a function of receiving electrons from the cathode or the cathode side and transporting them to the anode side. The electron injection material and the electron transport material used for these layers may be a low molecular compound or a high molecular compound.
Specifically, pyridine derivatives, quinoline derivatives, pyrimidine derivatives, pyrazine derivatives, phthalazine derivatives, phenanthroline derivatives, triazine derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, fluorenone derivatives, anthraquinodimethane derivatives, anthrone Derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, naphthalene, perylene and other aromatic ring tetracarboxylic acid anhydrides, phthalocyanine derivatives, 8-quinolinol derivative metal complexes, Metal phthalocyanines, various metal complexes represented by metal complexes with benzoxazole and benzothiazole as ligands, organosilane derivatives represented by siloles Body, or the like is preferably a layer containing.

The electron injection layer or the electron transport layer of the organic EL device of the present invention can contain an electron donating dopant. The electron donating dopant introduced into the electron injecting layer or the electron transporting layer only needs to have an electron donating property and a property of reducing an organic compound, such as an alkali metal such as Li or an alkaline earth metal such as Mg. Transition metals including rare earth metals and reducing organic compounds are preferably used. As the metal, a metal having a work function of 4.2 eV or less can be preferably used. Specifically, Li, Na, K, Be, Mg, Ca, Sr, Ba, Y, Cs, La, Sm, Gd , And Yb. Examples of the reducing organic compound include nitrogen-containing compounds, sulfur-containing compounds, and phosphorus-containing compounds.
In addition, materials described in JP-A-6-212153, JP-A-2000-196140, JP-A-2003-68468, JP-A-2003-229278, JP-A-2004-342614, and the like can be used.

  These electron donating dopants may be used alone or in combination of two or more. The amount of the electron donating dopant varies depending on the type of material, but is preferably 0.1% by mass to 99% by mass, and 1.0% by mass to 80% by mass with respect to the electron transport layer material. Is more preferable, and 2.0 mass% to 70 mass% is particularly preferable.

The thicknesses of the electron injection layer and the electron transport layer are each preferably 500 nm or less from the viewpoint of lowering the driving voltage.
The thickness of the electron transport layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm. In addition, the thickness of the electron injection layer is preferably 0.1 nm to 200 nm, more preferably 0.2 nm to 100 nm, and still more preferably 0.5 nm to 50 nm.
The electron injection layer and the electron transport layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

(Hole blocking layer)
The hole blocking layer is a layer having a function of preventing holes transported from the anode side to the light emitting layer from passing through to the cathode side. In the present invention, a hole blocking layer can be provided as an organic compound layer adjacent to the light emitting layer on the cathode side.
Examples of the compound constituting the hole blocking layer include aluminum complexes such as BAlq, triazole derivatives, phenanthroline derivatives such as BCP, and the like.
The thickness of the hole blocking layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm.
The hole blocking layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

(Electronic block layer)
The electron blocking layer is a layer having a function of preventing electrons transported from the cathode side to the light emitting layer from passing through to the anode side. In the present invention, an electron blocking layer can be provided as the organic compound layer adjacent to the light emitting layer on the anode side.
As examples of the compound constituting the electron blocking layer, for example, those mentioned as the hole transport material described above can be applied.
The thickness of the electron blocking layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and even more preferably 10 nm to 100 nm.
The hole blocking layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

(Protective layer)
In the present invention, the entire organic EL element may be protected by a protective layer.
As a material contained in the protective layer, any material may be used as long as it has a function of preventing materials that promote device deterioration such as moisture and oxygen from entering the device.
Specific examples thereof include metals such as In, Sn, Pb, Au, Cu, Ag, Al, Ti, and Ni, MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO, and Fe ₂ O. ₃ , metal oxides such as Y ₂ O ₃ , TiO ₂ , metal nitrides such as SiN _x , SiN _x O _y , metal fluorides such as MgF ₂ , LiF, AlF ₃ , CaF ₂ , polyethylene, polypropylene, polymethyl Monomer mixture containing methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene, tetrafluoroethylene and at least one comonomer Copolymer obtained by copolymerization, cyclic in the copolymer main chain Examples thereof include a fluorine-containing copolymer having a structure, a water-absorbing substance having a water absorption of 1% or more, and a moisture-proof substance having a water absorption of 0.1% or less.

  The method for forming the protective layer is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, MBE (molecular beam epitaxy), cluster ion beam, ion plating, plasma polymerization (high frequency) Excited ion plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method, printing method, transfer method can be applied.

(Sealing)
Furthermore, the organic electroluminescent element of this invention may seal the whole element using a sealing container.
Further, a moisture absorbent or an inert liquid may be sealed in a space between the sealing container and the light emitting element. Although it does not specifically limit as a moisture absorber, For example, barium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, calcium chloride, magnesium chloride, copper chloride Cesium fluoride, niobium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, magnesium oxide, and the like. The inert liquid is not particularly limited, and examples thereof include paraffins, liquid paraffins, fluorinated solvents such as perfluoroalkane, perfluoroamine, and perfluoroether, chlorinated solvents, and silicone oils. Can be mentioned.

Moreover, the method of sealing with the resin sealing layer shown below is also used suitably.
(Resin sealing layer)
The functional element of the present invention preferably suppresses deterioration of element performance due to oxygen or moisture by contact with the atmosphere by the resin sealing layer.
<Material>
The resin material for the resin sealing layer is not particularly limited, and an acrylic resin, an epoxy resin, a fluorine resin, a silicon resin, a rubber resin, an ester resin, or the like can be used. An epoxy resin is preferable from the viewpoint of the prevention function. Among the epoxy resins, a thermosetting epoxy resin or a photocurable epoxy resin is preferable.
<Production method>
The method for producing the resin sealing layer is not particularly limited, and examples thereof include a method of applying a resin solution, a method of pressure bonding or thermocompression bonding of a resin sheet, and a method of dry polymerization by vapor deposition or sputtering.
<Film thickness>
The thickness of the resin sealing layer is preferably 1 μm or more and 1 mm or less. More preferably, they are 5 micrometers or more and 100 micrometers or less, Most preferably, they are 10 micrometers or more and 50 micrometers or less. If it is thinner than this, the inorganic film may be damaged when the second substrate is mounted. On the other hand, if it is thicker than this, the thickness of the electroluminescent element itself is increased, and the thin film property that is characteristic of the organic electroluminescent element is impaired.

(Sealing adhesive)
The sealing adhesive used in the present invention has a function of preventing intrusion of moisture and oxygen from the end portion.
<Material>
As the material of the sealing adhesive, the same material as that used for the resin sealing layer can be used. Among these, epoxy adhesives are preferable from the viewpoint of moisture prevention, and among them, a photocurable adhesive or a thermosetting adhesive is preferable.

It is also preferable to add a filler to the above material.
The filler added to the sealant is preferably an inorganic material such as SiO ₂ , SiO (silicon oxide), SiON (silicon oxynitride) or SiN (silicon nitride). Addition of the filler increases the viscosity of the sealant, improves processing suitability, and improves moisture resistance.

<Prescription of sealing adhesive>
-Polymer composition, density | concentration It does not specifically limit as a sealing adhesive agent, The said thing can be used. For example, XNR5516 manufactured by Nagase Chemtech Co., Ltd. can be cited as a photo-curable epoxy adhesive.
-Thickness The coating thickness of the sealing adhesive is preferably 1 μm or more and 1 mm or less. If it is thinner than this, the sealing adhesive cannot be applied uniformly, which is not preferable. On the other hand, if it is thicker than this, the route through which moisture invades becomes wide, which is not preferable.
<Sealing method>
In the present invention, a functional element can be obtained by applying an arbitrary amount of the sealing adhesive with a dispenser or the like, and stacking and curing the second substrate after application.

(Drive)
The organic electroluminescence device of the present invention emits light by applying a direct current (which may include an alternating current component as necessary) voltage (usually 2 to 15 volts) or a direct current between the anode and the cathode. Obtainable.
The driving method of the organic electroluminescence device of the present invention is described in JP-A-2-148687, JP-A-6-301355, JP-A-5-29080, JP-A-7-134558, JP-A-8-234658, and JP-A-8-2441047. The driving method described in each publication, Japanese Patent No. 2784615, US Pat. Nos. 5,828,429, 6023308, and the like can be applied.

  The light-emitting element of the present invention can improve the light extraction efficiency by various known devices. For example, by processing the substrate surface shape (for example, forming a fine concavo-convex pattern), controlling the refractive index of the substrate / ITO layer / organic layer, controlling the film thickness of the substrate / ITO layer / organic layer, etc. It is possible to improve light extraction efficiency and external quantum efficiency.

  The light-emitting element of the present invention may be a so-called top emission type in which light emission is extracted from the anode side.

The organic EL device of the present invention can have a structure in which a charge generation layer is provided between a plurality of light emitting layers in order to improve luminous efficiency.
The charge generation layer is a layer having a function of generating charges (holes and electrons) when an electric field is applied and a function of injecting the generated charges into a layer adjacent to the charge generation layer.

The material for forming the charge generation layer may be any material having the above functions, and may be formed of a single compound or a plurality of compounds.
Specifically, it may be a conductive material, a semiconductive material such as a doped organic layer, or an electrically insulating material. 11-329748, Unexamined-Japanese-Patent No. 2003-272860, and the material of Unexamined-Japanese-Patent No. 2004-39617 are mentioned.
More specifically, transparent conductive materials such as ITO and IZO (indium zinc oxide), fullerenes such as C60, conductive organic materials such as oligothiophene, metal phthalocyanines, metal-free phthalocyanines, metal porphyrins, metal-free Conductive organic materials such as porphyrins, metal materials such as Ca, Ag, Al, Mg: Ag alloy, Al: Li alloy, Mg: Li alloy, hole conductive material, electron conductive material, and a mixture thereof May be used.
The hole conductive material is, for example, a material in which a hole transporting organic material such as 2-TNATA or NPD is doped with an oxidant having an electron withdrawing property such as F4-TCNQ, TCNQ, or FeCl ₃ , or a P-type conductive material. The electron conductive material includes an electron transporting organic material doped with a metal or a metal compound having a work function of less than 4.0 eV, an N type conductive polymer, N type Type semiconductors. Examples of the N-type semiconductor include N-type Si, N-type CdS, and N-type ZnS. Examples of the P-type semiconductor include P-type Si, P-type CdTe, and P-type CuO.
Further, an electrically insulating material such as V ₂ O ₅ can be used for the charge generation layer.

  The charge generation layer may be a single layer or a stack of a plurality of layers. A structure in which a plurality of layers are stacked includes a conductive material such as a transparent conductive material and a metal material and a hole conductive material, or a structure in which an electron conductive material is stacked, and the above hole conductive material and electron conductive And a layer having a structure in which a functional material is laminated.

In general, it is preferable to select a film thickness and a material for the charge generation layer so that the visible light transmittance is 50% or more. The film thickness is not particularly limited, but is preferably 0.5 nm to 200 nm, more preferably 1 nm to 100 nm, still more preferably 3 nm to 50 nm, and particularly preferably 5 to 30 nm.
The method for forming the charge generation layer is not particularly limited, and the above-described method for forming the organic compound layer can be used.

The charge generation layer is formed between the two or more light emitting layers. The charge generation layer may include a material having a function of injecting charges into adjacent layers on the anode side and the cathode side. In order to improve the electron injection property to the layer adjacent to the anode side, for example, an electron injection compound such as BaO, SrO, Li ₂ O, LiCl, LiF, MgF ₂ , MgO, and CaF _{2 is} added to the anode side of the charge generation layer. May be laminated.
In addition to the contents mentioned above, the material for the charge generation layer should be selected based on the descriptions in JP-A-2003-45676, US Pat. Nos. 6,337,492, 6,107,734, 6,872,472, and the like. Can do.

The organic EL element in the present invention may have a resonator structure. For example, a multilayer mirror made of a plurality of laminated films having different refractive indexes, a transparent or translucent electrode, a light emitting layer, and a metal electrode are superimposed on a transparent substrate. The light generated in the light emitting layer resonates repeatedly with the multilayer mirror and the metal electrode as a reflection plate.
In another preferred embodiment, a transparent or translucent electrode and a metal electrode each function as a reflector on a transparent substrate, and light generated in the light emitting layer repeats reflection and resonates between them.
In order to form a resonant structure, the optical path length determined from the effective refractive index of the two reflectors and the refractive index and thickness of each layer between the reflectors is adjusted to the optimum value to obtain the desired resonant wavelength. Is done. The calculation formula in the case of the first embodiment is described in JP-A-9-180883. The calculation formula in the case of the second aspect is described in Japanese Patent Application Laid-Open No. 2004-127795.

For example, as described in “Monthly Display”, September 2000, pages 33 to 37, a method for making an organic EL display of a full color type includes three primary colors (blue (B) and green). (G), red light (R)), a three-color light emitting method in which organic EL elements that emit light corresponding to red (R) are arranged on a substrate, and white light emitted by a white light emitting organic EL element into three primary colors through a color filter. And a color conversion method in which blue light emission by an organic EL element for blue light emission is converted into red (R) and green (G) through a fluorescent dye layer are known.
Moreover, the planar light source of a desired luminescent color can be obtained by using combining the organic EL element of the different luminescent color obtained by the said method. For example, a white light-emitting light source that combines blue and yellow light-emitting elements, a white light-emitting light source that combines blue, green, and red light-emitting elements.

(application)
The organic EL device and the manufacturing method of the present invention are used in a wide range of fields including a digital still camera display, a mobile phone display, a personal digital assistant (PDA), a computer display, an automobile information display, a TV monitor, or general lighting. Applied.

  Hereinafter, the organic EL device and the production method of the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Example 1
1. Measurement of amorphous organic semiconductor thin film by thermally stimulated current measurement method (TSC) 1) Amorphous light-emitting organic semiconductor thin film 1 according to the present invention
A glass substrate having a thickness of 0.5 mm and a square of 2.5 cm was placed in a cleaning container, subjected to ultrasonic cleaning in 2-propanol, and then subjected to UV-ozone treatment for 30 minutes.
On this glass substrate, mCP (T1 = 67 Kcal / mol (280 KJ / mol), Tg = 60 ° C.) as a host material and platinum complex Pt-1 (T1 = 65 Kcal / mol (272 KJ / mol)) as a light emitting material. Co-deposition was performed so that the platinum complex Pt-1 contained 13% by mass with respect to mCP. The thickness was 200 nm. Two vapor-deposited samples were produced under the same conditions, and one of them was heat-treated at 55 ° C. for 3 days. The heat-treated sample was designated as sample 1A, and the sample not subjected to the heat treatment was designated as sample 1B.

The obtained sample was measured by the thermally stimulated current measurement method (TSC) under the following conditions.
Measurement conditions: Temperature increase rate: 10 K / min

The obtained results are shown in FIG.
By the heat treatment, the peak intensity on the high temperature side decreased and the peak intensity on the low temperature side increased.

2) Preparation of comparative amorphous light-emitting organic semiconductor thin film 2 Similar to the preparation of amorphous light-emitting organic semiconductor thin film 1 according to the present invention, a thin film of Alq3 (Tg = 130 ° C.) alone on a glass substrate to a thickness of 200 nm. Vapor deposited. Two vapor-deposited samples were produced under the same conditions, and one of them was heat-treated at 80 ° C. for 3 hours. The heat-treated sample was designated as sample 2A, and the sample not subjected to the heat treatment was designated as sample 2B.
The obtained sample was similarly subjected to TSC measurement.
The obtained results are shown in FIG. One peak was observed and shifted to the high temperature side by heat treatment.

3) Amorphous organic semiconductor thin film 3 of the present invention
In the organic semiconductor thin film 1, TSC was measured by changing to the following materials, forming a film, and performing heat treatment (55 ° C., 3 days).
Host material: H-39 (T1 = 67 Kcal / mol (280 KJ / mol), Tg = 65 ° C.)
Luminescent material: Platinum complex Pt-1 (T1 = 65 Kcal / mol (272 KJ / mol))
TSC measurement method: measured by the same method as the amorphous semiconductor thin film 1 The results obtained are shown in FIG.

4) Amorphous organic semiconductor thin film 4 of the present invention
In the organic semiconductor thin film 1, TSC was measured by changing to the following materials, forming a film, and performing heat treatment (55 ° C., 3 days).
Host material: mCP (T1 = 67 Kcal / mol (280 KJ / mol))
Luminescent material: Platinum complex Pt-2 (T1 = 64 Kcal / mol (268 KJ / mol))
TSC measurement method: Measured by the same method as the amorphous semiconductor thin film The results obtained are shown in FIG.

5) Comparative amorphous organic semiconductor thin film 4
In the organic semiconductor thin film 1, TSC was measured by changing to the following materials, forming a film, and performing heat treatment (70 ° C., 3 days).
Host material: H-40 (T1 = 72 Kcal / mol (301 KJ / mol), Tg = 75 ° C.)
Luminescent material: Platinum complex Pt-1 (T1 = 65 Kcal / mol (272 KJ / mol))
TSC measurement method: measured by the same method as that for the amorphous semiconductor thin film The results obtained are shown in FIG.
In this comparative example, T1 (H) −T1 (G) = 7 Kcal / mol (29 KJ / mol), which is a large value, and only one peak could be observed with TSC.

2. Preparation of organic EL element 1) Preparation of organic EL element 1 A glass substrate having a 0.5 mm thickness and a 2.5 cm square ITO film (manufactured by Geomat Co., Ltd., surface resistance 10Ω / □) is placed in a cleaning container, and in 2-propanol After ultrasonic cleaning, UV-ozone treatment was performed for 30 minutes.
On the transparent anode (ITO film), the following layers were provided in order by vacuum deposition.

Hole injection layer: 2-TNATA and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (abbreviated as F4-TCNQ) and F4-TCNQ to 2-TNATA And co-evaporated to contain 1% by mass. The thickness was 160 nm.
Hole transport layer: α-NPD, thickness 3 nm.
Light-emitting layer: Co-deposited so as to contain 13 mass% of mCP and platinum complex Pt-1 with respect to mCP. The thickness was 60 nm.
Hole blocking layer: BAlq, thickness 40 nm.
Electron transport layer: Alq3, thickness 10 nm.
Electron injection layer: LiF, thickness 1 nm.
Cathode (upper electrode): Al, thickness 200 nm.

Sealing Step The obtained organic EL device was transferred into a nitrogen-substituted glove box and sealed with a glass sealing cap using an ultraviolet curable epoxy resin adhesive.

2) Production of Comparative Organic EL Element 2 In production of the organic EL element 1 of the present invention, the anode to the cathode were changed as follows.
Hole transport layer: α-NPD, thickness 60 nm.
Light-emitting layer: Alq3 was deposited to a thickness of 40 nm.
Electron injection layer: LiF, thickness 1 nm.

3) Preparation of the organic EL element 3 of the present invention The organic EL element 1 was prepared by the same method as the organic EL element 1 except that the material of the light emitting layer was changed as follows.
Host material: H-39 (T1 = 67 Kcal / mol (280 KJ / mol))
Luminescent material: Platinum complex Pt-1 (T1 = 65 Kcal / mol (272 KJ / mol))

4) Preparation of the organic EL element 4 of the present invention The organic EL element 1 was prepared by the same method as the organic EL element 1 except that the material of the light emitting layer was changed as follows.
Host material: mCP (T1 = 67 Kcal / mol (280 KJ / mol))
Luminescent material: Platinum complex Pt-2 (T1 = 64 Kcal / mol (268 KJ / mol))

5) Preparation of comparative organic EL element 5 In the said organic EL element 1, it produced with the same method as the organic EL element 1 except changing the material of a light emitting layer into the following. The heat treatment was changed to 70 ° C.
Host material: H-40 (T1 = 72 Kcal / mol (301 KJ / mol))
Luminescent material: Platinum complex Pt-1 (T1 = 65 Kcal / mol (272 KJ / mol))

  The structure of the material used in the examples is shown below.

2. Performance of organic EL device The obtained comparative organic EL device and the organic EL device of the present invention were measured for external quantum efficiency and driving durability by the following means under the same conditions.

<Measurement method of drive voltage>
A DC voltage was applied to each element, and the voltage reaching the light emission luminance of 360 cd / m ² was evaluated as a driving voltage.
<Method for measuring external quantum efficiency>
A direct voltage was applied to the light emitting element to emit light with a luminance of 360 cd / m ² using a source measure unit 2400 manufactured by KEITHLEY. The emission spectrum and the amount of light were measured using a luminance meter SR-3 manufactured by Topcon Corporation, and the external quantum efficiency was calculated from the emission spectrum, the amount of light and the current at the time of measurement.

<< Measurement method of driving durability ratio >>
A direct current voltage was applied to each element so as to have a luminance of 360 cd / m ^2, and the device was continuously driven to measure the luminance half time until the luminance reached 180 cd / m ² . This luminance half time was used as an index of driving durability.

The obtained results are shown in Table 1.
In the devices 1, 3, and 4 of the present invention, the external quantum efficiency was improved, the luminance half-life was doubled or more, and the driving durability was remarkably increased. On the other hand, although the comparative element 2 slightly increased in luminance half time, the driving voltage increased and the external quantum efficiency decreased. The comparative element 5 did not change the external quantum efficiency, but the driving durability decreased.

Conceptual diagram of energy levels of ITO / NPD / Al organic semiconductor thin film Conceptual diagram of thermal stimulation current TSC method Schematic diagram of TSC curve of amorphous organic semiconductor thin film of the present invention Conceptual diagram of TSC curve of comparative amorphous organic semiconductor thin film Conceptual diagram of TSC curve of comparative amorphous organic semiconductor thin film TSC curve of amorphous organic semiconductor thin film of the present invention TSC curve of comparative amorphous organic semiconductor thin film TSC curve of amorphous organic semiconductor thin film of the present invention TSC curve of amorphous organic semiconductor thin film of the present invention TSC curve of comparative amorphous organic semiconductor thin film

Explanation of symbols

1. NPD HOMO level
2. NPD LUMO level
3. Work function level of ITO
4, Al work function levels
5, Localized level of NPD thin film
6, Local level energy (Ei) of NPD

Claims (11)

  An organic electroluminescent device having an amorphous organic semiconductor thin film as at least a light emitting layer between a pair of electrodes, wherein the amorphous organic semiconductor thin film has a measurement temperature of −200 ° C. in measurement by a thermally stimulated current measurement method (TSC). It has a low temperature side peak in the region below −100 ° C. and a high temperature side peak in the region from −100 ° C. to 50 ° C., and the intensity of the low temperature side peak is greater than the intensity of the high temperature side peak. Organic electroluminescent element characterized.   The organic electroluminescent device according to claim 1, wherein the amorphous organic semiconductor thin film contains a host material and a light emitting material.   The organic electroluminescent element according to claim 2, wherein the light emitting material is a phosphorescent light emitting material.   The relationship between the triplet lowest excitation level (T1 (H)) of the host material and the triplet lowest excitation level (T1 (G)) of the light emitting material is −2 Kcal / mol (−8.37 KJ / mol) ≦ The organic electroluminescent element according to claim 2 or 3, wherein T1 (H) -T1 (G) ≤5Kcal / mol (20.9KJ / mol).   The organic light-emitting device according to claim 2, wherein the light-emitting material is a Pt complex.   A method for producing an organic electroluminescent device having a light emitting layer containing at least an amorphous organic semiconductor thin film between a pair of electrodes, wherein at least one constituent material of the constituent material constituting the light emitting layer after the light emitting layer is formed A method for producing an organic electroluminescent device, wherein the heat treatment is performed at a temperature below the glass transition temperature of the organic electroluminescent device.   The method of manufacturing an organic electroluminescent element according to claim 6, wherein the amorphous organic semiconductor thin film contains a host material and a light emitting material.   The method for producing an organic electroluminescent element according to claim 7, wherein the temperature for the heat treatment is a temperature not higher than a glass transition point of the host material.   9. The method for manufacturing an organic electroluminescent element according to claim 7, wherein the light emitting material is a phosphorescent light emitting material.   The relationship between the triplet lowest excitation level (T1 (H)) of the host material and the triplet lowest excitation level (T1 (G)) of the light emitting material is −2 Kcal / mol (−8.37 KJ / mol) ≦ It is T1 (H) -T1 (G) <= 5Kcal / mol (20.9KJ / mol), The manufacturing method of the organic electroluminescent element of any one of Claims 7-9 characterized by the above-mentioned.   The method for producing an organic electroluminescent element according to any one of claims 7 to 10, wherein the light emitting material is a Pt complex.

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