JP2009094327A - Organic electroluminescent element and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescent element which has a high efficiency and long service life, and to provide a manufacturing method thereof. <P>SOLUTION: The organic electroluminescent element 10 includes an anode 2, a cathode 7, and a laminate sandwiched between the anode 2 and the cathode 7 and having at least an electronic block layer 4 and an organic light emitting layer 5 laminated in order. The electronic block layer 4 contains a phosphorus-doped siloxane polymer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an organic electroluminescent element (organic EL element) and a display device.

  Since the electroluminescent element is a self-luminous type, the visibility is high, the display performance is excellent, the high-speed response is possible, and the thickness can be reduced. For this reason, electroluminescent elements are attracting attention as display elements such as flat panel displays.

  Among electroluminescent elements, an organic electroluminescent element using an organic compound as a light emitter can have a lower driving voltage than an inorganic electroluminescent element, can easily be increased in area, and has an appropriate luminescent material. By selecting, it has characteristics such that a desired emission color can be easily obtained. For this reason, organic electroluminescent elements are being actively developed as next-generation displays.

  From the viewpoint of the manufacturing process, organic electroluminescent elements are composed of a type in which a low molecular weight compound is formed by a dry process such as a vacuum deposition method and a so-called coating film forming method such as a spin coating method, a casting method, or an ink jet method. And the type that forms each layer.

An organic electroluminescent device (hereinafter referred to as a coated organic electroluminescent device) produced by a coating film forming method has the following advantages over an organic light emitting device produced by a dry process.
(A) Low cost (b) Easy large area (c) Excellent controllability of trace doping

  Hereinafter, a general configuration of a coating type organic electroluminescent element will be described with reference to the drawings. FIG. 6 is a cross-sectional view showing a general configuration of a coating type organic electroluminescent element. In the organic electroluminescent device 110 of FIG. 6, an anode 101, a hole injection layer 102, a light emitting layer 103, an electron injection layer 104, and a cathode 105 are sequentially provided on a substrate 100.

  In the organic electroluminescent device 110 of FIG. 6, the following PEDOT: PSS (mixture of polythiophene and polystyrene sulfonic acid) is generally used as a constituent material of the hole injection layer 102.

  PEDOT: PSS is formed by a coating film forming method such as spin coating. By the way, PEDOT: PSS is soluble in water and insoluble in nonpolar solvents. For this reason, even if the constituent material of the light emitting layer 103 is dissolved in a nonpolar solvent and the light emitting layer 103 is formed by a coating process, the PEDOT: PSS film is not eluted. Therefore, PEDOT: PSS is a suitable hole injection material in the coating type organic electroluminescence device.

  As a constituent material of the light emitting layer 103, for example, polyphenylene vinylene, polyfluorene, polyvinyl carbazole, and derivatives thereof are used. Here, the light emitting layer 103 is formed by spin coating or the like. Then, an electron injection layer 104 is formed on the light emitting layer 103 by vacuum deposition of lithium fluoride or the like, and then a metal electrode thin film to be the cathode 105 is formed and formed, whereby the organic electroluminescent element is completed.

  Here, the coating type organic electroluminescent element has an excellent feature that it can be produced by a simple process, and is expected to be applied to various uses. However, there are two problems to be improved, such as a point that a sufficiently large light emission intensity cannot be obtained and a point that the lifetime is not sufficient.

  Various speculations have been made about the cause of the decrease in the emission intensity, and the deterioration of PEDOT: PSS is considered as one of the main causes. This is because an ionic component such as a sulfur atom derived from a sulfone group, a hydrogen atom, or Na contained as an impurity diffuses into the light-emitting layer 103 when the element is energized, causing an undesirable effect. It is believed that.

  In order to solve this problem, an attempt has been made to provide an electron block layer made of an organosilicon compound between the PEDOT: PSS film and the anode (see Patent Document 1). In Patent Document 1, a thin film made of an organosilicon compound having a Si—O bond is formed on a PEDOT: PSS film by spin coating. Subsequently, a fluorene derivative film (light emitting layer), a calcium thin film, and a silver thin film are sequentially formed on the organosilicon compound thin film, thereby realizing an improvement in efficiency and a long life. It is considered that the efficiency is improved because the recombination probability between electrons and holes is increased by blocking the electrons that the organosilicon compound attempts to flow from the light emitting layer to PEDOT: PSS. On the other hand, it is considered that the reason why the lifetime is improved is that the organosilicon compound captures ions diffusing from PEDOT: PSS.

JP 2005-302443 A

  As described above, the organic electroluminescent element disclosed in Patent Document 1 uses an organosilicon compound as a constituent material of the electron block layer, thereby capturing ions in the electron block layer, thereby diffusing the ions. It is possible to slow down. However, in order to further extend the lifetime of the device, it is necessary to block ion diffusion by capturing ions more firmly.

  The present invention has been made in view of the above problems, and an object thereof is to provide a high-efficiency, long-life organic electroluminescence device and a method for producing the same.

  An organic electroluminescent element of the present invention comprises an anode, a cathode, and a laminate formed by sequentially laminating at least an electron blocking layer and an organic light emitting layer, sandwiched between the anode and the cathode, and The block layer contains a phosphorus-doped siloxane polymer.

  ADVANTAGE OF THE INVENTION According to this invention, a highly efficient and long life organic electroluminescent element and its manufacturing method can be provided.

  First, the organic electroluminescent element of the present invention will be described. The organic electroluminescent element of the present invention comprises an anode, a cathode, and a laminate formed by sequentially laminating at least an electron blocking layer and an organic light emitting layer, sandwiched between the anode and the cathode.

  Hereinafter, the organic electroluminescent element of the present invention will be described with reference to the drawings. However, this does not limit the present invention.

  FIG. 1 is a cross-sectional view showing an example of an embodiment of the organic electroluminescent element of the present invention. In the organic electroluminescent element 10 of FIG. 1, an anode 2, a hole injection layer 3, an electron blocking layer 4, an organic light emitting layer 5, an electron injection layer 6 and a cathode 7 are sequentially provided on a substrate 1.

  Further, in the organic electroluminescent element of the present invention, besides the configuration of FIG. 1, a configuration in which the electron blocking layer 5 is directly formed on the anode 2 can be exemplified, though not shown.

  Furthermore, the organic electroluminescent element of the present invention can include at least one of an electron transport layer and a hole transport layer in addition to the configuration of FIG.

  The organic electroluminescent element of the present invention is characterized in that the electron blocking layer 4 contains a phosphorus-doped siloxane polymer.

Since the siloxane polymer having a SiO _x unit has an insulating property, it can flow from the organic light emitting layer 5 to the anode 2 by using a constituent material of the electron blocking layer 4 provided between the anode 2 and the organic light emitting layer 5. Can be firmly blocked. Therefore, the efficiency of the element can be increased.

Here, the effect of doping siloxane polymer with phosphorus will be described. FIG. 2 is a conceptual diagram showing how the phosphorus-doped siloxane polymer traps ions. As shown in FIG. 2, phosphorus doped in the siloxane polymer is incorporated in the polymer molecular chain as a phosphoric acid derivative unit. Here, when ions (M ⁺ ) that become impurities exist in the electron blocking layer 4, as shown in FIG. 2, the oxygen atoms that are double-bonded to phosphorus atoms and the impurity ions are electrostatically bonded. To do. In this way, the phosphorus-doped siloxane polymer traps impurity ions. Accordingly, the impurity ions generated from the hole injection layer 3 and the like are difficult to diffuse in the electron blocking layer 4, so that the diffusion of the impurity ions to the organic light emitting layer 5 can be firmly blocked in the electron blocking layer 4. it can. From the above, the organic electroluminescent element of the present invention can prevent the diffusion of impurity ions into the organic light emitting layer 5 which is a cause of deterioration of the organic electroluminescent element, so that the lifetime of the element can be further extended. .

Next, a phosphorus-doped siloxane polymer that is a constituent material of the electron block layer 4 will be described. Examples of the phosphorus-doped siloxane polymer include a copolymer in which a phosphoric acid derivative unit is introduced into the main chain of a siloxane polymer composed of SiO _x units shown below.

  However, the phosphorus-doped siloxane polymer is not limited to the linear polymer described above, and includes a polymer containing a branched structure or a crosslinked structure.

As described above, the phosphorus-doped siloxane polymer that is a constituent material of the electron blocking layer 4 is a polymer composed of SiO _x units and phosphoric acid derivative units. Here, the value of x is preferably 1.5 to 2.5. The phosphorus atom content in the phosphorus-doped siloxane polymer is preferably 1 mol% to 50 mol%.

In the organic electroluminescent element of the present invention, preferably, a hole injection layer 3 is further provided between the anode 2 and the electron blocking layer 4. The work function of a siloxane polymer having a SiO _x bond is generally about 5.5 eV to 6.0 eV. This value is larger than that of a transparent conductive oxide such as ITO or a metal material generally used as the anode 2. For this reason, the energy barrier at the interface between the anode 2 and the electron blocking layer 4 becomes large, and the injection of holes may be suppressed. By suppressing the injection of holes, the driving voltage of the element increases or charges are accumulated inside the element, which may cause deterioration of the element. Therefore, in the organic electroluminescent element of the present invention, it is preferable to insert the hole injection layer 3 between the anode 2 and the electron blocking layer 4. By doing so, the hole injection property to the organic light emitting layer 5 can be improved, so that the drive voltage can be lowered and the life can be further extended.

In the organic electroluminescence device of the present invention, the hole injection layer 3 preferably contains a water-soluble polymer. When an organic electroluminescent element is produced by a coating process, an organic solvent is used when the organic light emitting layer 5 is formed. For this reason, it is common to use a water-soluble polymer insoluble in the nonpolar solvent for the hole injection layer 3. However, water-soluble polymers tend to take up alkali ions or alkaline earth ions such as Na ⁺ and Ca ²⁺ . In addition, when a sulfone group is introduced to give water solubility like PEDOT: PSS, the electrode may be dissolved by a sulfone group that is an acidic functional group. Thereby, the case where the metal element which comprises an electrode diffuses in the inside of an element in the state of an ion may arise. In addition, by introducing a sulfone group, H ⁺ and Na ^+, which are counter ions of the sulfone group, may also diffuse into the device. Therefore, when the constituent material of the hole injection layer 3 is a water-soluble polymer, an electron blocking layer 4 made of a phosphorus-doped siloxane polymer is provided to generate ions that can be generated in the hole injection layer 3 in the organic light emitting layer 5. It is necessary to prevent it from diffusing.

  The constituent material of the hole injection layer 3 may be anything as long as it has a hole transporting property. Here, in the case of a coating type organic electroluminescent element, a material that is insoluble or hardly soluble in a solvent that dissolves the organic light emitting layer 4 is preferable. As the constituent material of the hole injection layer 3, for example, phthalocyanine derivatives, naphthalocyanine derivatives, porphyrin derivatives, oxazole, oxadiazole, triazole, imidazole, imidazolone, pyrazoline, tetrahydroimidazole, polyarylalkane, butadiene, benzidine type triphenylamine , Styrylamine type triphenylamine, diamine type triphenylamine and the like and derivatives thereof, polymer materials such as polyvinylcarbazole, polysilane, conductive polymers such as PEDOT: PSS, etc., but are not limited to these Absent.

  Next, the other structural member of the organic electroluminescent element of this invention is demonstrated.

  The substrate 1 is not particularly limited, such as glass, ceramic, compound, metal, and plastic. However, when the element configuration is a bottom emission type, a transparent substrate such as glass is used. On the other hand, when the element configuration is a top emission type, a metal substrate is used to prevent light leakage to the lower part of the substrate, or a cathode material such as Ag is formed on a glass substrate or the like to form a mirror structure. . It is also possible to control the colored light by adding a color filter film, a fluorescent color conversion filter film, a dielectric reflection film, or the like to the substrate. In addition, a thin film transistor can be formed over a substrate and an element can be manufactured so as to be connected thereto.

  The material for the anode 2 should have a work function as large as possible. For example, simple metals such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, tungsten, chromium, or alloys thereof combined, tin oxide, zinc oxide, indium oxide, indium tin oxide, indium zinc oxide Further, metal oxides such as CuI and halides such as CuI can be used. In addition, conductive polymers such as polyaniline, polypyrrole, polythiophene, and polyphenylene sulfide can also be used. These electrode materials may be used alone or in combination of two or more. Moreover, the anode may be composed of a single layer or a plurality of layers.

  The constituent material of the organic light emitting layer 5 may be any light emitting organic compound that emits light when an electric field is applied. For example, if it is a low molecular weight system, anthracene, naphthalene, pyrene, tetracene, coronene, perylene, phthaloperylene, naphthaloperylene, diphenylbutadiene, tetraphenylbutadiene, coumarin, oxadiazole, bisbenzoxazoline, bisstyryl, cyclopentadiene, quinoline metal Complexes, aminoquinoline metal complexes, benzoquinoline metal complexes, pyran, quinacridone, rubrene and their derivatives. Furthermore, the phosphorescent metal complex represented by the iridium-phenylpyridine complex is also illustrated. On the other hand, in the case of a polymer system, polyvinyl carbazole, polyphenylene vinylene, polyfluorene, and derivatives thereof can be exemplified.

  The organic light emitting layer 5 may be composed of only the above-described light emitting organic compound, but may be composed of a host and a guest. Here, when the organic light emitting layer 5 is composed of a host and a guest, the combination of the host and the guest may be a combination of low molecules, a combination of a polymer and a low molecule, or a combination of polymers. A combination of these may be used.

The constituent material of the electron injection layer 6 may be anything as long as it is a compound having electron conductivity. For example, as exemplified by LiF, Cs ₂ CO ₃ , CaO and the like, alkali metal or alkaline earth metal fluorides, carbonate compounds, oxides, and the like can be given. In addition to the above materials, an organic compound having electron conductivity may be used. Examples include quinoline derivatives such as aluminum quinoline complex (Alq), oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, perylene derivatives, pyridine derivatives, pyrimidine derivatives, quinoxaline derivatives, diphenylquinone derivatives, nitro-substituted fluorene derivatives, and the like.

  The material for the cathode 7 is preferably a material having a small work function. For example, simple metals such as lithium, sodium, potassium, calcium, magnesium, aluminum, indium, ruthenium, titanium, manganese, yttrium, silver, lead, tin, and chromium can be used. An alloy formed by combining these metals alone can also be used. For example, lithium-indium, sodium-potassium, magnesium-silver, aluminum-lithium, aluminum-magnesium, magnesium-indium and the like can be used. A metal oxide such as indium tin oxide can also be used. These electrode materials may be used alone or in combination of two or more. Moreover, the cathode may be composed of a single layer or a plurality of layers.

  Moreover, it is desirable that either the anode or the cathode is transparent or translucent.

  When the electron transport layer is provided, the constituent material may be any material that transports electrons. For example, the electron transport material exemplified as the constituent material of the electron injection layer 6 can be used.

  Further, when the hole transport layer is provided, the constituent material thereof may be anything as long as it is a material that transports holes. For example, phthalocyanine derivative, naphthalocyanine derivative, porphyrin derivative, oxazole, oxadiazole, triazole, imidazole, imidazolone, pyrazoline, tetrahydroimidazole, polyarylalkane, butadiene, benzidine type triphenylamine, styrylamine type triphenylamine, diamine type Examples thereof include, but are not limited to, polymer materials such as triphenylamine and derivatives thereof, polyvinyl carbazole, polysilane, and conductive polymers.

  In the organic electroluminescent element of the present invention, a protective layer or a sealing layer can be provided for the purpose of preventing contact with oxygen, moisture or the like on the produced element. Examples of the protective layer include diamond thin films, inorganic material films such as metal oxides and metal nitrides, polymer films such as fluorine resin, polyparaxylene, polyethylene, silicone resin, and polystyrene resin, or photocurable resins. Further, it is possible to cover glass, a gas-impermeable film, a metal, etc., and to package the element itself with an appropriate sealing resin.

  Next, the manufacturing method of the organic electroluminescent element of this invention is demonstrated. In particular, the method for forming the electron block layer 4 will be mainly described.

The method of forming the electron block layer 4 is roughly classified into the following two.
1. A method of forming a thin film to be the electron block layer 4 using a polymer obtained by doping a siloxane polymer as a matrix with a phosphorus compound (hereinafter referred to as a first method).
2. A method in which a silane compound and a phosphate compound coexist, a thin film is formed by utilizing a dehydration condensation reaction of the silane compound, and a phosphorus compound unit is contained in the SiO _x unit (hereinafter referred to as a second method).

  First, the first method will be described. As a method for doping a siloxane polymer as a matrix with a phosphorus compound, for example, a method in which a siloxane polymer and a phosphorus compound having a hydroxyl group such as phosphoric acid are mixed and the phosphorus compound is contained in the siloxane matrix by a dehydration condensation reaction. is there. Further, it is possible to employ a method in which phosphorus ions are directly implanted into the matrix siloxane polymer by an ion beam.

  For example, siloxane polymers having various organic functional groups such as dimethylpolysiloxane, diphenylpolysiloxane, fluoropolysiloxane, styrylpolysiloxane, aminopolysiloxane, mercaptopolysiloxane, and epoxypolysiloxane are used as the matrix siloxane polymer. be able to. However, the present invention is not limited to these. The siloxane polymer used as a matrix may be one type or a mixture of two or more types. On the other hand, the structure of the siloxane polymer may be linear, or may have an organic functional group introduced in the side chain or terminal, and is not particularly limited.

  It is also possible to use a siloxane polymer that is cured by various external energies such as heat and ultraviolet rays. By curing the siloxane polymer, it becomes insoluble in an organic solvent, so that the organic light emitting layer 5 can be laminated on the electron block layer 4 by a coating process.

  A phosphine oxide compound can be mentioned as the phosphorus compound doped in the matrix (siloxane polymer). The phosphine oxide compound is a compound represented by the following general formula (I).

  In the formula (I), R is not particularly limited, and examples thereof include various elements such as hydrogen and oxygen, various functional groups such as hydroxyl group, phenyl group, alkyl group, amine group, and amino group, and π-conjugated substituents. Can be mentioned. R may be the same or different.

  Specific examples of the phosphine oxide compound include phosphoric acid, phosphonic acid, phosphinic acid, phosphine oxide, triphenylphosphine, trioctylphosphine oxide, tributylphosphine oxide, piperidylphosphine oxide and the like.

  When the electron blocking layer 4 is formed by the first method, a thin film that becomes the electron blocking layer 4 is formed by, for example, a sol-gel method.

  Next, the second method will be described. The silane compound used in the second method is, for example, tetraethoxylane, tetramethoxysilane, methyltrichlorosilane, methyltribromosilane, methyltriisopropoxysilane, ethyltrichlorosilane, ethyltribromosilane, ethyltrimethoxysilane. And ethyltriethoxysilane, ethyltriisopropoxysilane, propyltrimethoxysilane, phenyltrichlorosilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltridiphenyldimethoxysilane, and the like. However, the present invention is not limited to these. In addition to these compounds, partial hydrolysates of silane compounds, mixtures thereof, and the like can also be exemplified.

  When the electron blocking layer 4 is formed by the second method, a sol-gel method may be used as a specific method, or a vapor phase method such as an evaporation method, a sputtering method, or a CVD method may be used.

  In addition, in the organic electroluminescent element of this invention, you may form the electronic block layer 4 combining the method mentioned above.

  When the electron blocking layer 4 constituting the organic electroluminescent element of the present invention is formed from a siloxane compound, a silane compound, or the like by using a sol-gel method, it can be formed by coating using an alcohol solvent. Therefore, the electron blocking layer 4 is laminated on a film made of a water-soluble polymer that is hardly soluble in alcohol, such as PEDOT: PSS, which is often used as the hole injection layer 3 of the coating organic electroluminescence device. It is possible to form a film. In addition, after the film to be the electron blocking layer 4 is formed and cured, the electron blocking layer 4 is hardly soluble in a nonpolar solvent. Therefore, a thin film to be the organic light emitting layer 5 is formed on the electron blocking layer 4. A film can be formed by a coating method. Therefore, the electron block layer 4 can be provided between the hole injection layer 3 and the organic light emitting layer 5 by a consistent application process. In addition, since the diffusion of impurity ions from the hole injection layer 3 can be blocked by the electron blocking layer 4 with the above configuration, a longer-lifetime element is provided in the organic electroluminescence element manufactured by the coating process. It becomes possible to do. In addition, by forming each layer constituting the element by a coating process, it is possible to provide an organic electroluminescent element that can be easily reduced in area at low cost.

  The organic light emitting layer 5 is formed using a vacuum vapor deposition method or a coating method such as a spin coat / ink jet method. In addition, each layer other than the electron block layer 4 and the organic light emitting layer 5 is formed by a vacuum deposition method, a coating method, or the like.

  Next, the display device of the present invention will be described. The display device of the present invention comprises the organic electroluminescent element of the present invention. The organic electroluminescence device of the present invention can be applied to products that require energy saving and high luminance. Application examples include an image display device, a light source of a printer, an illumination device, a backlight of a liquid crystal display device, and the like.

  Examples of the image display device include energy-saving, high visibility, and lightweight flat panel displays.

  Moreover, as a light source of a printer, the laser light source part of the laser beam printer currently widely used can be replaced with the organic electroluminescent element of the present invention, for example. As a replacement method, for example, a method of arranging an organic electroluminescent element that can be independently addressed on the array can be mentioned. Even when the laser light source portion is replaced with the organic electroluminescent element of the present invention, image formation is not different from conventional methods by performing desired exposure on the photosensitive drum. Here, by using the organic electroluminescent element of the present invention, the volume of the apparatus can be greatly reduced.

  With respect to the illumination device and the backlight, an energy saving effect can be expected by using the organic electroluminescent element of the present invention.

  Next, a display device using the organic electroluminescent element of the present invention will be described. Hereinafter, the display device of the present invention will be described in detail with reference to the drawings, taking an active matrix system as an example.

  FIG. 3 is a diagram schematically illustrating a configuration example of a display device including the organic electroluminescence element of the present invention and a driving unit, which is an embodiment of the display device. 3 includes a scanning signal driver 21, an information signal driver 22, and a current supply source 23, which are connected to a gate selection line G, an information signal line I, and a current supply line C, respectively. A pixel circuit 24 is disposed at the intersection of the gate selection line G and the information signal line I. The scanning signal driver 21 sequentially selects the gate selection lines G1, G2, G3... Gn, and in synchronization therewith, any one of the information signal lines I1, I2, I3. The voltage is applied to the pixel circuit 24 via these.

Next, the operation of the pixel will be described. FIG. 4 is a circuit diagram illustrating a circuit constituting one pixel arranged in the display device of FIG. In the pixel circuit 30 of FIG. 4, when a selection signal is applied to the gate selection line Gi, the first thin film transistor (TFT1) 31 is turned on, the image signal Ii is supplied to the capacitor (C _add ) 32, The gate voltage of the second thin film transistor (TFT2) 33 is determined. A current is supplied to the organic electroluminescent element 34 from the current supply line Ci according to the gate voltage of the second thin film transistor (TFT2) (33). Here, the gate potential of the second thin film transistor (TFT2) 33 is held in the capacitor ( _Cadd ) 32 until the first thin film transistor (TFT1) 31 is next selected for scanning. Therefore, current continues to flow through the organic electroluminescent element 34 until the next scanning is performed. As a result, the organic electroluminescent element 34 can always emit light during one frame period.

  FIG. 5 is a schematic view showing an example of a cross-sectional structure of a TFT substrate used in the display device of FIG. Details of the structure will be described below while showing an example of the manufacturing process of the TFT substrate. When manufacturing the display device 40 of FIG. 5, a moisture-proof film 42 for protecting a member (TFT or organic layer) formed thereon is first coated on a substrate 41 such as glass. As a material constituting the moisture-proof film 42, silicon oxide or a composite of silicon oxide and silicon nitride is used. Next, a gate electrode 43 is formed by patterning a predetermined circuit shape by depositing a metal such as Cr by sputtering. Subsequently, silicon oxide or the like is formed by plasma CVD or catalytic chemical vapor deposition (cat-CVD) or the like, and patterned to form the gate insulating film 44. Next, a silicon film is formed by a plasma CVD method or the like (in some cases, annealed at a temperature of 290 ° C. or higher), and a semiconductor layer 45 is formed by patterning according to a circuit shape.

  Further, a drain electrode 46 and a source electrode 47 are provided on the semiconductor film 45 to produce a TFT element 48, thereby forming a circuit as shown in FIG. Next, an insulating film 49 is formed on the TFT element 48. Next, a contact hole (through hole) 50 is formed so that the anode 51 for the organic electroluminescence element made of metal and the source electrode 47 are connected.

  The display device 40 can be obtained by sequentially laminating a multilayer or single layer organic layer 52 and a cathode 53 on the anode 51. At this time, a first protective layer 54 and a second protective layer 55 may be provided in order to prevent deterioration of the organic electroluminescent element. By driving the display device using the organic electroluminescent element of the present invention, it is possible to display with good image quality and stable display for a long time.

  Note that the display device is not particularly limited to a switching element, and can be easily applied to a single crystal silicon substrate, an MIM element, an a-Si type, or the like.

  From the above description, a display device with high efficiency and long life can be provided by using the organic electroluminescent element of the present invention as a constituent device of a display device.

  Examples of the present invention will be described below.

<Example 1>
An organic electroluminescent element having the configuration shown in FIG. 2 was produced. In this example, the following compounds and the like were used as constituent materials of each layer constituting the element.

Substrate 1: Glass substrate Anode 2: Indium tin oxide (ITO)
Hole injection layer 3: PEDOT: PSS (Startron, Baytron-P VP AL4083)
Electronic blocking layer 4: Phosphorus-containing silicic acid polymer (Honeywell, P-5S)
Organic light emitting layer 5: oligofluorene compound (host) shown below

下記に示すＩｒ（Ｃ₈−ｐｉｑ）₃（ゲスト）

It is shown in the following Ir (C ₈ -piq) ₃ (guest)

電子注入層６：Ｃｓ₂ＣＯ₃
陰極７：Ａｌ

Electron injection layer 6: Cs ₂ CO ₃
Cathode 7: Al

Next, the manufacturing process of an organic electroluminescent element is shown. First, an anode 2 was formed by forming a film of ITO on the glass substrate (substrate 1) by sputtering. At this time, the film thickness of the anode 2 was about 100 nm. Next, PEDOT: PSS was formed on the anode 2 by spin coating to form the hole injection layer 3. At this time, the thickness of the hole injection layer 3 was set to 40 nm. Next, the phosphorus-containing silicic acid polymer was diluted with isopropyl alcohol to prepare a 1.5 wt% isopropyl alcohol solution (first preparation solution). Next, the 1st preparation liquid was dripped on the positive hole injection layer 3, and it formed into a film by the spin coat method, and formed the electronic block layer 4. FIG. At this time, the thickness of the electron block layer 4 was set to 20 nm. Next, an oligofluorene compound as a host and Ir (C ₈ -piq) _{3 as} a guest were dissolved in toluene to prepare a 1.0 wt% toluene solution (second preparation solution). In the second preparation liquid, the host and the guest are mixed at a weight concentration ratio of 99: 1. Next, the 2nd preparation liquid was dripped on the electronic block layer 4, and it formed into a film by spin-coating at 1000 rpm, and the organic light emitting layer 5 was formed. At this time, the film thickness of the organic light emitting layer 5 was about 80 nm. Next, Cs ₂ CO ₃ as the electron injection layer 6 was formed on the organic light emitting layer 5 by resistance heating vapor deposition to form the electron injection layer 6. At this time, the thickness of the electron injection layer 6 was 2.4 nm. Next, Al was formed on the electron injection layer 6 by resistance heating vapor deposition to form the cathode 7. At this time, the thickness of the cathode 7 was set to 80 nm. Finally, a protective glass plate was placed in a nitrogen atmosphere and sealed with an acrylic resin adhesive. An organic electroluminescent element was obtained as described above.

With respect to the obtained organic electroluminescence device, when a direct current voltage of 7.6 V was applied with the ITO electrode as the positive electrode and the Al electrode as the negative electrode, a current flowed through the device. The current density at this time was about 100 mA / cm ² , and red light emission with a luminance of 6600 cd / m ² was observed. Moreover, the chromaticity coordinate of the light which the organic electroluminescent element in a present Example emits was NTSC (X, Y) = (0.67,0.32).

<Comparative Example 1>
In Example 1, as a constituent material of the electronic block layer 4, a siloxane polymer containing no phosphorus (T-11, manufactured by Honeywell) was used instead of P-5S, and the same as in Example 1. An organic electroluminescent element was produced by the method. The obtained device was evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Comparative example 2>
In Example 1, an organic electroluminescent element was produced in the same manner as in Example 1 except that the electron block 4 layer was not provided. The obtained device was evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Example 2>
In Example 1, as a constituent material of the hole injection layer 3, the following sexithiophene (6T) was used instead of PEDOT: PSS, and this 6T was formed into a film by resistance heating vapor deposition. Layer 3 was formed. Other than this, an organic electroluminescent element was produced in the same manner as in Example 1. The obtained device was evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Comparative Example 3>
In Example 2, as a constituent material of the electron blocking layer 4, a siloxane polymer not containing phosphorus (T-11, manufactured by Honeywell) was used instead of P-5S, and the same as in Example 2. An organic electroluminescent element was produced by the method. The obtained device was evaluated in the same manner as in Example 2. The results are shown in Table 1.

<Comparative example 4>
In Example 2, an organic electroluminescent device was produced in the same manner as in Example 2 except that the four electron block layers were not provided. The obtained device was evaluated in the same manner as in Example 2. The results are shown in Table 1.

  From Table 1, the improvement of efficiency and lifetime was confirmed by providing an electronic block layer. This is because the electron blocking layer 4 blocks electrons that attempt to flow to the anode 2 or the hole injection layer 3 without recombining with holes in the organic light emitting layer 5, thereby recombining the holes and electrons. This is thought to be because the probability improved. Further, by using a phosphorus-doped siloxane polymer as a constituent material of the electron block layer 4, the lifetime of the device was further improved. As shown in FIG. 2, this is because oxygen atoms having double bonds with phosphorus in the phosphorus-doped siloxane polymer capture impurity ions diffusing from the outside of the light emitting layer and strengthen diffusion of the impurity ions. This is thought to be due to blocking. Moreover, in each Example, it was shown that an organic electroluminescent element can be produced using a coating process. For this reason, the present invention can provide an organic electroluminescent element that can be easily produced at low cost and with a large screen.

  As described above, the organic electroluminescent element of the present invention is a light-emitting element with high efficiency and long life, and can be easily manufactured and manufactured by a relatively inexpensive coating method. The organic electroluminescent element of the present invention can be used as a constituent material for display panels, display devices, and the like.

It is sectional drawing which shows an example of embodiment in the organic electroluminescent element of this invention. It is a conceptual diagram which shows a mode that a phosphorus dope siloxane polymer capture | acquires ion. It is a figure which shows typically the structural example of the display apparatus provided with the organic electroluminescent element and drive means of this invention which are one form of a display apparatus. FIG. 4 is a circuit diagram showing a circuit constituting one pixel arranged in the display device of FIG. 3. It is the schematic diagram which showed an example of the cross-section of the TFT substrate used with the display apparatus of FIG. It is sectional drawing which shows the general structure of a coating type organic electroluminescent element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Anode 3 Hole injection layer 4 Electron block layer 5 Organic light emitting layer 6 Electron injection layer 7 Cathode 10, 110, 34 Organic electroluminescent element 20, 40 Display device 21 Scan signal driver 22 Information signal driver 23 Current supply source 24 , 30 Pixel circuit 31 First thin film transistor (TFT1)
32 condenser (C _add )
33 Second thin film transistor (TFT2)
41 Substrate 42 Moisture-proof layer 43 Gate electrode 44 Gate insulating film 45 Semiconductor film 46 Drain electrode 47 Source electrode 48 TFT element 49 Insulating film 50 Contact hole (through hole)
51 Anode 52 Organic Layer 53 Cathode 54 First Protective Layer 55 Second Protective Layer 100 Substrate 101 Anode 102 Hole Injection Layer 103 Light-Emitting Layer 104 Electron Injection Layer 105 Cathode

Claims (4)

An anode and a cathode;
A laminate formed by sequentially laminating at least an electron blocking layer and an organic light emitting layer sandwiched between the anode and the cathode,
An organic electroluminescent device characterized in that the electron blocking layer contains a phosphorus-doped siloxane polymer.   The organic electroluminescent device according to claim 1, further comprising a hole injection layer between the anode and the electron blocking layer.   The organic electroluminescent device according to claim 2, wherein the hole injection layer contains a water-soluble polymer.   A display device comprising the organic electroluminescent element according to claim 1.

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