JP2007258526A - Organic electroluminescence element and display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescence element which has high luminance, high emission efficiency, is excellent in power consumption, and continuous driving life, and can pick up white light, and a white color back light which is excellent in reproductivity in combination with a color filter by using the element. <P>SOLUTION: In the organic electroluminescence element which is constituted of an anode, at least one organic layer, and a cathode on a substrate; at least one layer of the organic layers comprises electron acceptor. The volume concentration (%) of the electron acceptor in the organic layer is 0.1 to 30%, and an electron acceptor concentration region whose volume concentration differs at least 3% exists. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an organic electroluminescence element and an organic electroluminescence display.

  As a light-emitting electronic display device, there is an electroluminescence display (ELD). Examples of the constituent elements of ELD include inorganic electroluminescent elements (inorganic EL elements) and organic electroluminescent elements (hereinafter also referred to as organic EL elements). Inorganic electroluminescent elements have been used as planar light sources, but an alternating high voltage is required to drive the light emitting elements.

  An organic electroluminescence device has a structure in which a light-emitting layer containing a light-emitting compound is sandwiched between a cathode and an anode, and excitons (excitons) are generated by injecting electrons and holes into the light-emitting layer and recombining them. The device emits light using the emission of light (fluorescence / phosphorescence) when the exciton is deactivated, and can emit light at a voltage of about several V to several tens of V, and is self-luminous. Therefore, it has a wide viewing angle, high visibility, and since it is a thin-film type complete solid-state device, it has attracted attention from the viewpoints of space saving and portability.

  Since there is a high demand for reduction in power consumption, methods for reducing drive voltage have been disclosed. For example, if the organic layer is made thin, the driving voltage for allowing a constant current to flow can be further lowered, but the outflow of carriers increases and the light emission efficiency decreases. In view of this, there has been disclosed means for improving efficiency by incorporating a dopant into the charge transport layer adjacent to the electrode and optimizing the electrical characteristics between the adjacent organic layers (see, for example, Patent Document 1). This is the design utilization of a so-called n-type or p-type semiconductor layer. Furthermore, in order to improve the confinement of excitons, a method is disclosed in which a light emitting layer is sandwiched between a carrier transport layer containing an electron donor or an acceptor and a carrier suppression layer (see, for example, Patent Document 2). In addition, a method specialized for p-type semiconductor layers using a Lewis acid as an electron acceptor is also disclosed (for example, see Patent Document 3).

  However, market expectations for organic electroluminescence panels are high, and a significant improvement in power consumption is desired. That is, there is a demand for improvement in high luminous efficiency as the drive voltage is lowered. However, as compared with the n-type semiconductor layer, there is little knowledge about the p-type semiconductor layer, and there is room for improvement.

In view of such a situation, as a result of intensive studies, the present inventors have a great influence on a reduction in driving voltage and an improvement in luminous efficiency when the concentration of the electron acceptor in the p-type semiconductor layer is locally changed. Since the knowledge was obtained, the present invention was reached. In the above document, the concentration of the electron acceptor is all constant, and there is no description or suggestion that it is locally changed.
Japanese Patent Laid-Open No. 4-297076 JP 2000-196140 A Japanese Patent Laid-Open No. 2001-244079

  An object of the present invention is an organic electroluminescence device capable of extracting white light with high luminance, high luminous efficiency, excellent power consumption and continuous driving life, and excellent color reproducibility in combination with a color filter using the device. To provide a white backlight.

  The above object of the present invention is achieved by the following configurations.

  1. In an organic electroluminescent device comprising an anode, at least one organic layer and a cathode on a substrate, at least one of the organic layers contains an electron acceptor, and the volume concentration of the electron acceptor in the organic layer ( %) Is 0.1 to 30%, and there are electron acceptor concentration regions different by 3% or more, and the organic electroluminescence device.

  2. 2. The organic electroluminescence device according to 1 above, wherein the difference between the maximum concentration and the minimum concentration of the volume concentration (%) containing the electron acceptor is 1 to 30%.

  3. Each of the film thicknesses of the region containing the maximum concentration or the minimum concentration of the electron acceptor is 1/100 to 1/2 of the film thickness of the organic layer containing the electron acceptor. Or the organic electroluminescent element of 2.

  4). The electron acceptor is contained in a region where the distance between the organic layer containing the electron acceptor and the adjacent layer interface on the cathode side is within 1/3 of the film thickness of the organic layer containing the electron acceptor. 4. The organic electroluminescence device as described in any one of 1 to 3 above, wherein the volume concentration (%) is 1% or less.

  5. 5. The organic electroluminescence device according to any one of 1 to 4, wherein there are at least three electron acceptor concentration regions different by 3% or more.

  6). 6. The organic electroluminescent element according to any one of 1 to 5, wherein the organic layer containing the electron acceptor is in contact with the anode.

  7). 7. The organic electroluminescence device according to any one of 1 to 6, wherein the organic layer has a light emitting layer containing at least one light emitting dopant (phosphorescent compound).

  8). 7. The organic electroluminescence device according to any one of 1 to 6, wherein the organic layer has a light emitting layer containing a phosphorescent compound and a light emitting layer containing a fluorescent compound.

  9. 9. The organic electroluminescence device as described in 8 above, wherein the light emitting layer containing the fluorescent compound emits blue light.

  10. 10. The organic electroluminescence device according to any one of 1 to 9 above, which emits white light.

  11. 11. An organic electroluminescence display, wherein blue light, green light, and red light are obtained from white light extracted from the organic electroluminescence element described in 10 above through a blue filter, a green filter, and a red filter.

  According to the present invention, an organic electroluminescence device capable of extracting white light with high brightness, high luminous efficiency, power consumption, and continuous driving life, and a white background excellent in color reproducibility in combination with a color filter using the device. Could provide light.

  Hereinafter, details of each component according to the present invention will be sequentially described.

《Organic electroluminescence device》
The organic electroluminescence element of the present invention will be described. The organic electroluminescence device of the present invention is composed of a substrate, an electrode, and an organic layer, and the organic layer is composed of an organic layer containing at least a light emitting layer and an electron acceptor according to the present invention (also simply referred to as an acceptor).

《Light emission, front luminance, chromaticity of organic electroluminescence device》
The emission color of the organic electroluminescence device of the present invention and the compound related to the device is shown in FIG. 4.16 on page 108 of “New Color Science Handbook” (Edited by the Japan Color Society, University of Tokyo Press, 1985). It is determined by the color when the result measured with the total CS-1000 (manufactured by Konica Minolta Sensing) is applied to the CIE chromaticity coordinates. The white color in the organic electroluminescence device of the present invention means that the chromaticity of the CIE1931 color system is x = 0.33 ± 0.07, y = 0.33 when the 2 ° C. viewing angle front luminance is measured by the above method. It is characterized by being in the range of ± 0.07.

"Layer structure"
In order to extract white light, the light emitting layer which is a constituent layer of the organic electroluminescence device of the present invention has at least two emission spectra having emission maximum wavelengths in the range of 430 to 480 nm, 510 to 550 nm, and 600 to 640 nm, respectively. It includes at least three layers, preferably three or more layers.

  Although the preferable specific example of the layer structure in this invention is shown below, this invention is not limited to these.

(I) Anode / hole transport layer / electron blocking layer / light emitting layer unit / hole blocking layer / electron transport layer / cathode (ii) Anode / hole transport layer / electron blocking layer / light emitting layer unit / hole blocking layer / Electron transport layer / cathode buffer layer / cathode (iii) anode / anode buffer layer / hole transport layer / electron blocking layer / light emitting layer unit / hole blocking layer / electron transport layer / cathode (iv) anode / anode buffer layer / Hole transport layer / electron blocking layer / light emitting layer unit / hole blocking layer / electron transport layer / cathode buffer layer / cathode Here, the light emitting layer unit has a light emission maximum wavelength of 430 to 480 nm, 510 to 550 nm, respectively. A light emitting layer unit has at least two light emitting layers in the range of 600 to 640 nm. The unit preferably has a non-light emitting intermediate layer between the light emitting layers.

《Electron Acceptor》
The electron acceptor according to the present invention refers to an electron accepting compound. The organic layer is formed by mixing with a host as a dopant instead of a single substance. Since the host oxidized by the electron acceptor exists in a cation radical state, the hole barrier near the layer interface on the anode side is reduced, the hole supply density is increased, and the effect of lowering the voltage is recognized. A so-called p-type semiconductor layer is formed. The layer containing the electron acceptor may be a light emitting layer. The dopant in this case contains the carrier acceptor according to the present invention and a light emitting source. The emission source may be fluorescence or phosphorescence. The acceptor according to the present invention is preferably contained in the hole transport layer.

《Hole transport layer》
The hole transport layer used in the present invention is a so-called p-type semiconductor layer. The effect of lowering the driving voltage is recognized, and it is interpreted that the hole mobility is increased by doping with the carrier acceptor, the shallow HOMO level is formed, and the hole mobility by hopping is increased. Conventionally, as for the concentration of doped impurities, only a uniform concentration in the hole transport layer has been studied.

  As a result of the inventor's detailed examination of the impurity concentration dependency, the present invention has been achieved. In other words, when the impurity concentration is not uniform and is locally changed, in addition to the conventional low driving voltage, surprisingly, an effect of improving the light emission efficiency was recognized. In particular, a remarkable effect was observed when a high concentration region was provided locally than the average acceptor concentration. Although a slight tendency to increase the driving voltage was observed, it is advantageous in terms of power efficiency. The reason is not clear, but if the acceptor concentration is locally increased, the number of fixed electrons increases and the electron barrier becomes higher, so that electrons or excitons are confined in the light emitting layer. The hole transport layer according to the present invention can be provided as a single layer or a plurality of layers.

  Known materials can be used as the hole transport material. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers. The above-mentioned materials can be used as the hole transport material, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.

  Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ', N'-tetraphenyl-4,4'-diaminophenyl; N, N'-diphenyl-N, N'- Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N ' − (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadriphenyl; N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino- (2-diphenylvinyl) benzene; 3-methoxy-4′-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and also two of those described in US Pat. No. 5,061,569. Having a condensed aromatic ring in the molecule, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-3086 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 8 are linked in a starburst type ( MTDATA) etc. Further, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used. Inorganic compounds such as SiC can also be used.

  A known material can be used as the carrier acceptor material according to the present invention. For example, Jpn. Huang et. al. Authors (Applied Physics Letters 80 (2002), p. 139), JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, JP-A-2004-281371, J. Pat. Appl. Phys. 95, 5773 (2004), and the like. Moreover, general formula (1)-(7) in Unexamined-Japanese-Patent No. 2006-41020 is also used preferably.

  The hole transport material and the carrier acceptor can be formed by, for example, forming a thin film by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method.

  Although it cannot be specified depending on the type of the acceptor preferable concentration condition material of the acceptor, the acceptor-containing average volume concentration according to the present invention is 0.1 to 30%, and there is a region where the concentration differs by at least 3% from the average concentration. 0% is out of the gist of the present invention, and 100% is close to an insulator, so the effect of the present invention cannot be obtained. The difference between the highest concentration and the lowest concentration is 1-30%, preferably 1-20%. More preferably, it is 1 to 10%. The film thickness ratio in the highest density region is 1 to 50%, more preferably 2% to 45%. The film thickness is usually about 1 nm to 1 μm, preferably 5 to 200 nm. Within 5 nm from the interface between the hole transport layer according to the present invention and the organic layer adjacent to the cathode side, the carrier acceptor concentration is preferably as low as possible within the range not impairing conductivity, from the viewpoint of continuous drive life.

  In the present invention, if there are 3 or more regions where the acceptor volume concentration is 3% or more, the luminous efficiency may be further improved, but it is often 5 or less depending on the material.

《Electron transport layer》
The electron transport layer can be provided as a single layer or a plurality of layers. Conventionally, in the case of a single electron transport layer and a plurality of layers, an electron transport material (also serving as a hole blocking material) used for an electron transport layer adjacent to the light emitting layer on the cathode side is injected from the cathode. As long as it has a function of transferring electrons to the light-emitting layer, any material can be selected and used from among conventionally known compounds. For example, nitro-substituted fluorene derivatives, diphenylquinone derivatives Thiopyrandioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives and the like. Furthermore, in the oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron-withdrawing group can also be used as an electron transport material. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  In addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum. Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), and the like, and the central metals of these metal complexes are In, Mg, Metal complexes replaced with Cu, Ca, Sn, Ga or Pb can also be used as the electron transport material.

  In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material. In addition, the distyrylpyrazine derivative exemplified as the material of the light emitting layer can also be used as an electron transport material, and an inorganic semiconductor such as n-type-Si, n-type-SiC, etc. as in the case of the hole injection layer and the hole transport layer. Can also be used as an electron transporting material.

  The electron transport layer can be formed by thinning the electron transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, about 1 nm-1 micrometer, Preferably it is 5-200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

  In the present invention, an n-type electron transport layer doped with impurities is used. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, JP-A-2001-102175, J. Pat. Appl. Phys. 95, 5773 (2004), and the like. Moreover, general formula (8)-(10) in Unexamined-Japanese-Patent No. 2006-41020 is also preferably used. In the present invention, an element having low power consumption can be manufactured by using such an electron transport layer having a high n property together with the p property semiconductor layer of the present invention.

<< Injection layer: electron injection layer, hole injection layer >>
The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, it exists between the anode and the light emitting layer or the hole transport layer and between the cathode and the light emitting layer or the electron transport layer. May be. An injection layer is a layer provided between an electrode and an organic layer in order to reduce drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (issued by NTT Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).

  The details of the anode buffer layer (hole injection layer) are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like. As a specific example, copper phthalocyanine is used. Examples thereof include a phthalocyanine buffer layer represented by an oxide, an oxide buffer layer represented by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.

  The details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium, aluminum, etc. Metal buffer layer typified by lithium, alkali metal compound buffer layer typified by lithium fluoride, alkaline earth metal compound buffer layer typified by magnesium fluoride, oxide buffer layer typified by aluminum oxide, etc. . The buffer layer (injection layer) is preferably a very thin film, and the film thickness is preferably in the range of 0.1 nm to 5 μm although it depends on the material.

<Blocking layer: hole blocking layer, electron blocking layer>
The blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film as described above. For example, it is described in JP-A Nos. 11-204258, 11-204359, and “Organic EL elements and their forefront of industrialization” (issued by NTT, Inc. on November 30, 1998). There is a hole blocking (hole blocking) layer.

  The hole blocking layer has a function of an electron transport layer in a broad sense, and is composed of a hole blocking material that has a function of transporting electrons and has a very small ability to transport holes, and transports holes while transporting electrons. By blocking this, the recombination probability of electrons and holes can be improved. Moreover, the structure of the electron carrying layer mentioned later can be used as a hole-blocking layer concerning this invention as needed. The hole blocking layer of the organic EL device of the present invention is preferably provided adjacent to the light emitting layer.

  Further, in the present invention, a plurality of light emitting layers having different emission colors are provided. In such a case, it is preferable that the light emitting layer whose emission maximum wavelength is the shortest is the closest to the anode among all the light emitting layers. In such a case, it is preferable to additionally provide a hole blocking layer between the shortest wave layer and the light emitting layer next to the anode next to the layer. Further, it is preferable that 50% by mass or more of the compound contained in the hole blocking layer provided at the position has an ionization potential of 0.2 eV or more larger than the host compound of the shortest wave emitting layer.

  The ionization potential is defined by the energy required to emit an electron at the HOMO (highest occupied molecular orbital) level of the compound to the vacuum level, and can be obtained by the following method, for example.

(1) Using Gaussian 98 (Gaussian 98, Revision A.11.4, MJ Frisch, et al, Gaussian, Inc., Pittsburgh PA, 2002.), a molecular orbital calculation software manufactured by Gaussian, USA The ionization potential can be obtained as a value obtained by rounding off the second decimal place of a value (eV unit converted value) calculated by performing structural optimization using B3LYP / 6-31G ^* . This calculation value is effective because the correlation between the calculation value obtained by this method and the experimental value is high.

  (2) The ionization potential can also be obtained by a method of directly measuring by photoelectron spectroscopy. For example, a method known as ultraviolet photoelectron spectroscopy can be suitably used by using a low energy electron spectrometer “Model AC-1” manufactured by Riken Keiki Co., Ltd.

  On the other hand, the electron blocking layer has a function of a hole transport layer in a broad sense, and is made of a material that has a function of transporting holes and has an extremely small ability to transport electrons, and transports electrons while transporting holes. By blocking, the recombination probability of electrons and holes can be improved. Moreover, the structure of the positive hole transport layer mentioned later can be used as an electron blocking layer as needed. The film thickness of the hole blocking layer and the electron transport layer according to the present invention is preferably 3 to 100 nm, and more preferably 5 to 30 nm.

<Light emitting layer>
The light emitting layer according to the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and the light emitting portion is in the layer of the light emitting layer. May be the interface between the light emitting layer and the adjacent layer. The light emitting layer according to the present invention emits light of at least three colors: a blue light emitting layer having an emission maximum wavelength in the range of 430 to 480 nm, a green light emitting layer in the range of 510 to 550 nm, and a red light emitting layer in the range of 600 to 640 nm. It is preferable to have a layer, but a two-color configuration is also acceptable. For example, even if two colors are selected from the three categories, the color reproducibility is inferior to that of the three-color configuration, but white is obtained.

  In addition, when the number of light emitting layers is more than four, there may be a plurality of layers having an emission spectrum or emission maximum wavelength in the same section. There is no restriction | limiting in particular as a lamination order of a light emitting layer. It is preferable to have a non-light emitting intermediate layer between each light emitting layer.

  The total thickness of the light emitting layer is not particularly limited, but it is 2 from the viewpoints of film uniformity, prevention of unnecessary application of high voltage during light emission, and improvement in stability of emitted color with respect to driving current. It is preferable to adjust to the range of -30 nm, More preferably, it is the range of 5-25 nm.

  For the production of the light-emitting layer, a light-emitting dopant or a host compound, which will be described later, is formed and formed by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, or an ink-jet method. it can. The thickness of each light emitting layer may be arbitrary as long as it is in the above-described range. There is no particular limitation on the relationship between the thicknesses of the blue, green, and red light emitting layers, but the thickness of the light emitting layer having the lowest recombination probability is the largest in order to obtain white light. Moreover, in the range which maintains the said maximum wavelength, you may mix a several luminescent compound in each light emitting layer. For example, a blue light-emitting compound having a maximum wavelength of 430 to 480 nm and a green light-emitting compound having a maximum wavelength of 510 to 550 nm may be mixed and used in the blue light-emitting layer.

  Next, a host compound and a light emitting dopant (also referred to as a light emitting dopant compound) included in the light emitting layer will be described.

(Host compound)
The host compound contained in the light emitting layer of the organic EL device of the present invention is defined as a compound having a phosphorescence quantum yield of phosphorescence emission at room temperature (25 ° C.) of less than 0.1. Preferably the phosphorescence quantum yield is less than 0.01. Moreover, it is preferable that the mass ratio in the layer is 20% or more among the compounds contained in a light emitting layer. As the host compound, known host compounds may be used alone or in combination of two or more. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the efficiency of the organic EL element can be increased. Moreover, it becomes possible to mix different light emission by using multiple types of phosphorescent compounds etc. which are used as the light emission dopant mentioned later, Thereby, arbitrary luminescent colors can be obtained. It is possible to adjust the kind of phosphorescent compound and the amount of doping, and it can be applied to illumination and backlight.

  As a host compound concerning this invention, the compound represented by following General formula (1) is mentioned as an example of the compound used preferably. Moreover, the said compound is preferably used also for the adjacent layer (for example, hole-blocking layer etc.) of a light emitting layer.

In the formula, Z ₁ represents an aromatic heterocyclic ring which may have a substituent, Z ₂ represents an aromatic heterocyclic ring or an aromatic hydrocarbon ring which may have a substituent, and Z ₃ Represents a divalent linking group or a simple bond. R ₁₀₁ represents a hydrogen atom or a substituent.

In the general formula (1), examples of the aromatic heterocycle represented by Z ₁ and Z ₂ include a furan ring, a thiophene ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, a benzimidazole ring, Diazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, carbazole ring, carboline ring, carboline ring And a ring in which the carbon atom of the hydrocarbon ring is further substituted with a nitrogen atom. Furthermore, the aromatic heterocyclic ring may have a substituent represented by R ₁₀₁ described later.

Examples of the aromatic hydrocarbon ring represented by Z ₂ include a benzene ring, biphenyl ring, naphthalene ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, naphthacene ring, triphenylene ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphen ring, picene ring, pyrene ring, pyranthrene ring, anthraanthrene A ring etc. are mentioned. Furthermore, the aromatic hydrocarbon ring may have a substituent represented by R ₁₀₁ described later.

Examples of the substituent represented by R ₁₀₁ include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group). , Pentadecyl group etc.), cycloalkyl group (eg cyclopentyl group, cyclohexyl group etc.), alkenyl group (eg vinyl group, allyl group etc.), alkynyl group (eg ethynyl group, propargyl group etc.), aryl group (eg , Phenyl group, naphthyl group, etc.), aromatic heterocyclic group (for example, furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, Phthalazinyl group, etc.), heterocyclic group (eg, pyrrolidyl group, imi Dazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy group (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (for example, Cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), alkylthio group (eg, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dosylthio group) Etc.), a cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), an arylthio group (eg, phenylthio group, naphthylthio group, etc.), an alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyl) Oxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, methyl) Aminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc. ), Acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octyl group) Rucarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group) Group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2 -Ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), Rubamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group) , Phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido) Group naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfuric group) Nyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group) Cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group (eg, phenylsulfonyl group, naphthylsulfonyl, 2-pyridylsulfonyl group, etc.), amino group (eg, amino group, ethylamino group, Dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, etc.), halogen Atom (for example, fluorine atom, chlorine atom, bromine atom, etc.), fluorinated hydrocarbon group (for example, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.), cyano group, nitro group, Examples thereof include a hydroxy group, a mercapto group, and a silyl group (for example, a trimethylsilyl group, a triisopropylsilyl group, a triphenylsilyl group, a phenyldiethylsilyl group). These substituents may be further substituted with the above substituents. In addition, a plurality of these substituents may be bonded to each other to form a ring. Preferred substituents are an alkyl group, a cycloalkyl group, a fluorinated hydrocarbon group, an aryl group, and an aromatic heterocyclic group.

  The divalent linking group may be a hydrocarbon group such as alkylene, alkenylene, alkynylene, and arylene, and may contain a heteroatom, and may be a thiophene-2,5-diyl group or pyrazine-2,3. -It may be a divalent linking group derived from a compound having an aromatic heterocycle such as a diyl group (also referred to as a heteroaromatic compound), or may be a chalcogen atom such as oxygen or sulfur. Further, it may be a group such as an alkylimino group, a dialkylsilanediyl group, or a diarylgermandiyl group that connects and connects heteroatoms. A mere bond is a bond that directly connects the linking substituents together.

In the present invention, Z _{1 in the} general formula (1) is preferably a 6-membered ring. Thereby, luminous efficiency can be made higher. Furthermore, the lifetime can be further increased. In the present invention, it is preferable that the Z ₂ in the general formula (1) is a 6-membered ring. Thereby, luminous efficiency can be made higher. Furthermore, the lifetime can be further increased. Furthermore, it is preferable that Z ₁ and Z _{2 in} the general formula (1) are both 6-membered rings because the luminous efficiency can be further increased. Furthermore, it is preferable because the lifetime can be further increased. Hereinafter, although the specific example of a compound represented by General formula (1) based on this invention is shown, this invention is not limited to these.

The light emitting host used in the present invention may be a conventionally known low molecular compound or a high molecular compound having a repeating unit, and a low molecular compound having a polymerizable group such as a vinyl group or an epoxy group (deposition polymerization property). (Light emitting host). As the known host compound, a compound that has a hole transporting ability and an electron transporting ability, prevents the emission of light from being increased in wavelength, and has a high Tg (glass transition temperature) is preferable. Specific examples of known host compounds include compounds described in the following documents. For example, Japanese Patent Application Laid-Open Nos. 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860 Gazette, 2002-334787 gazette, 2002-15871 gazette, 2002-334788 gazette, 2002-43056 gazette, 2002-334789 gazette, 2002-75645 gazette, 2002-338579 gazette. No. 2002-105445, No. 2002-343568, No. 2002-141173, No. 2002-352957, No. 2002-203683, No. 2002-363227, No. 2002-231453. No. 2003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060. 2002-302516, 2002-305083, 2002-305084, 2002-308837, and the like.

  In the present invention, it has at least three light emitting layers of a light emitting layer having a light emission maximum wavelength in the range of 430 to 480 nm, a light emitting layer in the range of 510 to 550 nm, and a light emitting layer in the range of 600 to 640 nm. 50% by mass or more of the host compound of at least two layers of the three layers is preferably a compound having a phosphorescence emission energy of 2.9 eV or more and a Tg (glass transition point) of 90 ° C. or more, more preferably 100 ° C. These compounds. Among these, from the viewpoint of improving the storage stability of organic EL elements (also referred to as durability improvement) and reducing the uneven distribution of the compound at the light emitting layer interface, the molecular structure of the compound is particularly preferably the same. Here, the reason why it is preferable that the host compounds have the same physicochemical characteristics or the same molecular structure will be described in detail in the non-light emitting intermediate layer described later.

(Tg (glass transition point))
The organic compound of each layer constituting the organic electroluminescent element of the present invention is characterized by containing at least 80% by mass or more of each layer of a material having a Tg of 100 ° C. or higher.

  Here, the glass transition point (Tg) is a value obtained by a method based on JIS-K-7121 using DSC (Differential Scanning Colorimetry). By using a host compound having the same physical characteristics as described above, more preferably by using a host compound having the same molecular structure, the entire organic compound layer (also referred to as an organic layer) of the organic EL element is used. Homogeneous film properties can be obtained, and furthermore, adjusting the phosphorescence emission energy of the host compound to be 2.9 eV or more can effectively suppress energy transfer from the dopant and obtain high luminance.

(Phosphorescent energy)
The phosphorescent energy according to the present invention will be described. The phosphorescence emission energy according to the present invention refers to the peak energy of the 0-0 band of phosphorescence emission obtained when measuring the photoluminescence of a deposited film of 100 nm on a support substrate (which may be simply a substrate).

  First, a method for measuring a phosphorescence spectrum will be described. The luminescent host compound to be measured is dissolved in a well-deoxygenated mixed solvent of ethanol / methanol = 4/1 (volume / volume), put into a phosphorescence measurement cell, and then irradiated with excitation light at a liquid nitrogen temperature of 77 ° K. The emission spectrum at 100 ms after the excitation light irradiation is measured. Since phosphorescence has a longer emission lifetime than fluorescence, it can be considered that light remaining after 100 ms is almost phosphorescent.

  For compounds with a phosphorescence lifetime shorter than 100 ms, measurement may be performed with a short delay time. However, if the delay time is set so short that it cannot be distinguished from fluorescence, phosphorescence and fluorescence cannot be separated, which causes a problem. Therefore, it is necessary to select a delay time that can be separated. For the compound that cannot be dissolved in the solvent system, any solvent that can dissolve the compound may be used (substantially, the above-described measuring method has no problem because the solvent effect of phosphorescence wavelength is very small).

  Next, the 0-0 band is obtained. In the present invention, the emission maximum wavelength that appears on the shortest wavelength side in the phosphorescence spectrum chart obtained by the above measurement method is defined as the 0-0 band. Since the phosphorescence spectrum usually has a low intensity, when it is enlarged, it may be difficult to distinguish between noise and peak. In such a case, the emission spectrum during excitation light irradiation (for convenience, this is referred to as a steady light spectrum) is expanded and superimposed on the emission spectrum after 100 ms after excitation light irradiation (for convenience, this is referred to as a phosphorescence spectrum), and phosphorescence is obtained. It can be determined by reading the peak wavelength of the phosphorescence spectrum from the stationary light spectrum portion derived from the spectrum. In addition, by smoothing the phosphorescence spectrum, noise and peak can be separated and peak wavelength can be read. As the smoothing process, a smoothing method of Savitzky & Golay can be applied.

(Luminescent dopant)
The light emitting dopant according to the present invention will be described. As the light-emitting dopant according to the present invention, a fluorescent compound or a phosphorescent compound can be used. From the viewpoint of obtaining an organic EL element with higher luminous efficiency, the light-emitting layer and the light-emitting unit of the organic EL element of the present invention are used. The light-emitting dopant used (sometimes simply referred to as a light-emitting material) contains the above-mentioned host compound and at least one phosphorescent compound. When a fluorescent compound is used in combination, it is preferable to select blue.

(Phosphorescent compound)
The phosphorescent compound according to the present invention is a compound in which light emission from an excited triplet is observed. Specifically, the phosphorescent compound emits phosphorescence at room temperature (25 ° C.), and the phosphorescence quantum yield is 25 ° C. In this case, the phosphorescence quantum yield is preferably 0.1 or more. The phosphorescence quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of the Fourth Edition Experimental Chemistry Course 7. Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescent compound according to the present invention can achieve the phosphorescence quantum yield (0.01 or more) in any solvent. That's fine.

  There are two types of light emission of phosphorescent compounds in principle. One is the recombination of carriers on the host compound to which carriers are transported to generate an excited state of the host compound, and this energy is transferred to the phosphorescent compound. Energy transfer type to obtain light emission from the phosphorescent compound, and another one is that the phosphorescent compound becomes a carrier trap, carrier recombination occurs on the phosphorescent compound, and light emission from the phosphorescent compound is obtained. Although it is a trap type, in any case, it is a condition that the excited state energy of the phosphorescent compound is lower than the excited state energy of the host compound.

  The phosphorescent compound can be appropriately selected from known compounds used for the light emitting layer of the organic EL device. The phosphorescent compound according to the present invention is preferably a complex compound containing a group 8-10 metal in the periodic table of elements, more preferably an iridium compound, an osmium compound, or a platinum compound (platinum complex compound). Rare earth complexes, most preferably iridium compounds. Although the specific example of the compound used as a phosphorescent compound is shown below, this invention is not limited to these. These compounds are described, for example, in Inorg. Chem. 40, 1704-1711, and the like.

  Specific examples of the compound used as the phosphorescent compound include compounds described in paragraphs [0106] to [0109] of JP-A No. 2004-311410. The present invention is not limited to these.

(Fluorescent compound)
Representative examples of fluorescent compounds include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, perylene dyes. Stilbene dyes, polythiophene dyes, rare earth complex phosphors, and the like.

  In addition, conventionally known dopants can also be used in the present invention. For example, WO 00/70655 pamphlet, JP 2002-280178 A, JP 2001-181616 A, JP 2002-280179 A, JP 2001-181617 A, JP 2002-280180 A, JP 2001-247859 A, JP 2002-299060 A, JP 2001-313178 A, JP 2002-302671 A, JP JP 2001-345183 A, JP 2002-324679 A, WO 02/15645 Pamphlet, JP 2002-332291 A, JP 2002-50484 A, JP 2002-332292 A, JP 2002-2002 A. -83684 Publication, Special Table 2002 JP 40572, JP 2002-117978, JP 2002-338588, JP 2002-170684, JP 2002-352960, WO 01/93642, JP 2002-50483. JP, JP-A No. 2002-1000047, JP-A No. 2002-173684, JP-A No. 2002-359082, JP-A No. 2002-175854, JP-A No. 2002-363552, JP-A No. 2002-184582 JP, 2003-7469, JP 2002-525808, JP 2003-7471, JP 2002-525833, JP 2003-31366, JP 2002-226495, JP JP 2002-234894, JP No. 002-235076, JP 2002-241751, JP 2001-319779, JP 2001-319780, JP 2002-62824, JP 2002-1000047, JP 2002 No. 203679, JP-A No. 2002-343572, JP-A No. 2002-203678, and the like.

<Non-light emitting intermediate layer>
The non-light emitting intermediate layer according to the present invention will be described. The non-light-emitting intermediate layer according to the present invention means each light emission of the light-emitting layer unit having at least three light-emitting layers having emission maximum wavelengths in the range of 430 to 480 nm, 510 to 550 nm, and 600 to 640 nm, respectively. Between the layers.

  The film thickness of the non-light emitting intermediate layer is preferably in the range of 1 to 15 nm, and more preferably in the range of 3 to 10 nm to suppress interaction such as energy transfer between adjacent light emitting layers, and to the element current. This is preferable from the viewpoint of not applying a large load to the voltage characteristics.

  The material used for the non-light emitting intermediate layer may be the same as or different from the host compound of the light emitting layer, but may be the same as the host material of at least one of the adjacent light emitting layers. preferable.

  The non-light emitting intermediate layer may contain a compound common to the non-light emitting layers (for example, a host compound). Each of the common host materials (here, the common host material is used) means phosphorescence. In the case where the physicochemical characteristics such as energy and glass transition point are the same or the molecular structure of the host compound is the same, etc.), the injection barrier between the light emitting layer and the non-light emitting layer can be reduced. Thus, even if the voltage (current) is changed, the effect of easily maintaining the injection balance of holes and electrons can be obtained. It has also been found that the effect of improving the color shift when a voltage (current) is applied can be obtained. Furthermore, the use of a host material having the same physical characteristics or the same molecular structure as the host compound contained in each light-emitting layer in the undoped light-emitting layer makes it a major problem in the production of conventional organic EL devices. The complexity of production can also be eliminated.

  Furthermore, as described above, by using a material in which the lowest excited triplet energy level T1 of the common host material is higher than the lowest excited triplet energy level T2 of the phosphorescent compound, It was found that a highly efficient device can be obtained because triplet excitons are effectively confined in the light emitting layer. In addition, in the organic EL element of three colors of blue, green, and red, when a phosphorescent compound is used for each light emitting material, the excited triplet energy of the blue phosphorescent compound is the largest, A host material having an excited triplet energy larger than that of the phosphorescent compound may be included as a common host material in the light-emitting layer and the non-light-emitting intermediate layer.

  In the organic EL device of the present invention, the host material is preferably a material having a carrier transport capability since it assumes the carrier transport. Carrier mobility is used as a physical property representing carrier transport ability, but the carrier mobility of an organic material generally depends on the electric field strength. Since a material having a high electric field strength dependency easily breaks the balance of hole and electron injection / transport, it is preferable to use a material having a low electric field strength dependency of mobility for the intermediate layer material and the host material. On the other hand, in order to optimally adjust the injection balance of holes and electrons, it is also preferable that the non-light emitting intermediate layer functions as a blocking layer, that is, a hole blocking layer and an electron blocking layer.

  Hereinafter, the carrier transport layer and the carrier blocking layer according to the present invention will be described. Note that carriers refer to electrons or holes. In general, the hole transport layer is made of a material having the ability to transport holes, and includes a hole injection layer and an electron blocking layer in a broad sense. Similarly, the electron transport layer is made of a material having the ability to transport electrons, and includes an electron injection layer and a hole blocking layer in a broad sense.

《Support base》
The support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) according to the organic EL device of the present invention is not particularly limited in the type of glass, plastic, etc. There may be. In the case where light is extracted from the support base side, the support base is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable support base is a resin film capable of giving flexibility to the organic EL element.

  Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), Cellulose esters such as cellulose acetate phthalate (TAC) and cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones Cycloolefin resins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylate, Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Can be mentioned.

An inorganic or organic film or a hybrid film of both may be formed on the surface of the resin film, and the water vapor permeability measured by a method in accordance with JIS K 7129-1992 is 0.01 g / m ^2. It is preferably a barrier film of day / atm or less, and further has an oxygen permeability of 10 ⁻³ g / m ² / day or less and a water vapor permeability of 10 measured by a method according to JIS K 7126-1992. A high barrier film of ⁻³ g / m ² / day or less is preferred, and the water vapor permeability and oxygen permeability are more preferably 10 ⁻⁵ g / m ² / day or less.

  As a material for forming a barrier film formed on the surface of the resin film in order to obtain a high barrier film, any material may be used as long as it has a function of suppressing intrusion of an element such as moisture or oxygen that causes deterioration of the element. Silicon, silicon dioxide, silicon nitride, or the like can be used. Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and organic material layers. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.

<Method for forming barrier film>
The method for forming the barrier film is not particularly limited. For example, the vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma weight A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, and the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable. Examples of the opaque support base include metal plates / films such as aluminum and stainless steel, opaque resin substrates, ceramic substrates, and the like.

  The external extraction efficiency at room temperature of light emission of the organic EL device of the present invention is preferably 1% or more, more preferably 5% or more. Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element × 100. In addition, a hue improvement filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor.

  Here, an example of the layer structure of the transparent barrier film used for the support base according to the present invention will be described with reference to FIG. 8, and an example of an atmospheric pressure plasma discharge treatment apparatus preferably used for forming the barrier layer will be described with reference to FIG. I will explain.

  FIG. 8 is a schematic diagram showing an example of a layer configuration of a barrier film (also referred to as a gas barrier film) and a density profile thereof. The barrier film 201 (which may be transparent or opaque) has a configuration in which layers having different densities are stacked on the base material 202. In the present invention, the medium density layer 204 is provided between the low density layer 203 and the high density layer 205, and the medium density layer 204 is also provided on the high density layer 205. These low density layer, medium density layer, FIG. 8 shows an example in which a unit composed of a high-density layer and a medium-density layer is one unit, and two units are stacked. At this time, the density distribution in each density layer is uniform, and the density change between adjacent layers is stepped. In FIG. 8, the medium density layer 204 is shown as one layer, but a configuration of two or more layers may be adopted as necessary. In addition, as a layer structure of the barrier film (gas barrier film) according to the present invention, at least one layer among the three layers having different densities (a high density layer, a medium density layer, and a low density layer) may be provided. Preferably, it has two or three layers with different densities.

  Here, an atmospheric pressure plasma discharge treatment apparatus as shown in FIG. 9 is used as an example for forming the high density layer, the medium density layer, and the low density layer. Examples of the set values of the density of the high-density layer, medium-density layer, and low-density layer, materials used for forming each layer (for example, silicon oxide, silicon oxynitride, alumina oxide, etc.) and formation conditions are shown in the examples. Will be described in detail.

  FIG. 9 is a schematic view showing an example of an atmospheric pressure plasma discharge treatment apparatus for treating a substrate. The atmospheric pressure plasma discharge processing apparatus is an apparatus having at least a plasma discharge processing apparatus 230, an electric field applying means 240 having two power supplies, a gas supply means 250, and an electrode temperature adjusting means 260. FIG. 9 shows an interval (discharge space) 232 between the counter electrode between the roll rotating electrode (first electrode) 235 and the square tube fixed electrode group (second electrode) 236 (each electrode is also a square tube fixed electrode 236). The base material F is subjected to plasma discharge treatment to form a thin film. In FIG. 9, one electric field is formed by a pair of rectangular tube type fixed electrode group (second electrode) 236 and roll rotating electrode (first electrode) 235, and for example, a low density layer of this unit is formed. Form. FIG. 9 shows a configuration example including a total of five units having such a configuration, and by arbitrarily independently controlling the type of raw material supplied by each unit, the output voltage, and the like, A barrier film (also referred to as a transparent gas barrier layer) can be formed continuously.

  In the discharge space (between the counter electrodes) 232 between the roll rotating electrode (first electrode) 235 and the square tube type fixed electrode group (second electrode) 236, the roll rotating electrode (first electrode) 235 has a first power source. The first high-frequency electric field having the frequency ω1, the electric field intensity V1, and the current I1 from 241 and the frequency ω2, the electric field intensity V2 from the corresponding second power source 242 to the rectangular tube fixed electrode group (second electrode) 236, respectively. A second high-frequency electric field of current I2 is applied. A first filter 243 is installed between the roll rotation electrode (first electrode) 235 and the first power source 241. The first filter 243 easily passes a current from the first power source 241 to the first electrode. In addition, the current from the second power source 242 is grounded so that the current from the second power source 242 to the first power source is difficult to pass. In addition, a second filter 244 is installed between the square tube type fixed electrode group (second electrode) 236 and the second power source 242, and the second filter 244 is connected to the second electrode from the second power source 242. It is designed to facilitate the passage of current, ground the current from the first power supply 241 and make it difficult to pass the current from the first power supply 241 to the second power supply. The roll rotating electrode 235 may be the second electrode, and the square tube fixed electrode group 236 may be the first electrode. In any case, the first power source is connected to the first electrode, and the second power source is connected to the second electrode.

The first power source preferably applies a higher high-frequency electric field strength (V1> V2) than the second power source. Further, the frequency has the ability to satisfy ω1 <ω2. The current is preferably I1 <I2. The current I1 of the first high frequency electric field is preferably 0.3 to 20 mA / cm ² , more preferably 1.0 to 20 mA / cm ² . The current I2 of the second high frequency electric field is preferably 10 to 100 mA / cm ² , more preferably 20 to 100 mA / cm ² .

  The gas G generated by the gas generator 251 of the gas supply means 250 is introduced into the plasma discharge processing container 231 from the air supply port while controlling the flow rate. The base material F is unwound from the original winding (not shown) and is transported, or transported from the previous process, and air or the like accompanying the base material is blocked by the nip roll 265 via the guide roll 264. Then, while being wound while being in contact with the roll rotating electrode 235, it is transferred between the square tube fixed electrode group 236, the roll rotating electrode (first electrode) 235 and the square tube fixed electrode group (second electrode) 236, An electric field is applied from both sides to generate discharge plasma between the counter electrodes (discharge space) 232. The base material F forms a thin film with a gas in a plasma state while being wound while being in contact with the roll rotating electrode 235. The substrate F passes through the nip roll 266 and the guide roll 267, and is taken up by a winder (not shown) or transferred to the next step. The treated exhaust gas G ′ that has been discharged is discharged from the exhaust port 253. During the thin film formation, in order to heat or cool the roll rotating electrode (first electrode) 235 and the rectangular tube type fixed electrode group (second electrode) 236, the medium whose temperature is adjusted by the electrode temperature adjusting means 260 is supplied to the liquid feed pump P. Then, the pipe 261 is sent to both electrodes, and the temperature is adjusted from the inside of the electrodes. Reference numerals 268 and 269 denote partition plates that partition the plasma discharge processing vessel 231 and the outside.

<Sealing>
Examples of the sealing means used for sealing the organic EL element of the present invention include a method of bonding a sealing member, an electrode, and a support base with an adhesive. The sealing member may be disposed so as to cover the display area of the organic EL element, and may be concave or flat. Moreover, transparency and electrical insulation are not particularly limited. Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz.

  Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum. In the present invention, a polymer film and a metal film can be preferably used because the element can be thinned.

Furthermore, the polymer film preferably has an oxygen permeability of 10 ⁻³ g / m ² / day or less and a water vapor permeability of 10 ⁻⁵ g / m ² / day or less. The water vapor permeability and oxygen permeability are more preferably 10 ⁻⁵ g / m ² / day or less. For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.

  Specific examples of the adhesive include photocuring and thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylate. be able to. Moreover, the heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned. In addition, since an organic EL element may deteriorate by heat processing, what can be adhesive-hardened from room temperature to 80 degreeC is preferable. A desiccant may be dispersed in the adhesive. Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.

  In addition, it is also preferable that the electrode and the organic layer are coated on the outside of the electrode facing the support substrate with the organic layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film. . In this case, the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause deterioration of the element such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can. Furthermore, in order to improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials.

  The method for forming these films is not particularly limited. For example, vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma A polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used. In the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil can be injected in the gas phase and the liquid phase. preferable. A vacuum can also be used.

  Moreover, a hygroscopic compound can also be enclosed inside. Examples of the hygroscopic compound include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide etc.), perchloric acids (eg perchloric acid) Barium, magnesium perchlorate, and the like), and anhydrous salts are preferably used in sulfates, metal halides, and perchloric acids.

《Protective film, protective plate》
In order to increase the mechanical strength of the element, a protective film or a protective plate may be provided outside the sealing film on the side facing the support substrate with the organic layer interposed therebetween, or on the outside of the sealing film. In particular, when sealing is performed by the sealing film, it is preferable to provide such a protective film and a protective plate because the mechanical strength is not necessarily high. As a material that can be used for this, the same glass plate, polymer plate / film, metal plate / film, etc. used for the sealing can be used. It is preferable to use a film.

"anode"
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such electrode substances include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used. For the anode, these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when pattern accuracy is not so high (about 100 μm or more) A pattern may be formed through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material. Or when using the substance which can be apply | coated like an organic electroconductivity compound, wet film forming methods, such as a printing system and a coating system, can also be used. When light emission is extracted from the anode, it is desirable that the transmittance be greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm.

"cathode"
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Suitable are a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, a lithium / aluminum mixture, aluminum and the like.

  The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm. In order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.

  Moreover, after producing the said metal with a film thickness of 1-20 nm on a cathode, a transparent or semi-transparent cathode can be produced by producing the electroconductive transparent material quoted by description of the anode on it, By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

<< Light extraction and / or condensing sheet >>
In particular, in an organic EL element for a backlight, it is usually desirable that the brightness does not change even if light is emitted in all directions and the viewing angle changes. It is desirable to reduce the luminance at the viewing angle (angle observed from an oblique direction). Therefore, it is preferable that a diffusion plate, a prism sheet, and the like for controlling the radiation angle are combined on the organic EL element.

  Usually, in an organic EL device that emits light from a substrate (glass substrate, resin substrate, etc.), part of the light emitted from the light emitting layer undergoes total reflection at the interface between the substrate and air, causing loss of light. Problem occurs. In order to solve this problem, the prism surface or lens sheet is processed on the surface of the substrate, or the prism sheet or lens sheet is attached to the surface of the substrate, thereby suppressing total reflection and improving the light extraction efficiency. .

  Although the preferable form of a light extraction and / or a condensing sheet is demonstrated below, if it is in the range which does not impair the objective effect in this invention, light extraction efficiency can be improved using these.

(1) Configuration in which a diffuser plate and a prism sheet are placed on a glass substrate For example, in an organic EL element composed of a glass substrate / transparent conductive film / light emitting layer / electrode / sealing layer, the glass substrate is opposite to the light emitting layer. A first diffusion plate is placed in contact with the substrate surface. A first lens sheet (for example, 3M BEF II) is disposed so as to be in contact with the diffusion plate so that the lens surface faces the opposite side of the glass substrate, and the second lens sheet is formed with a stripe of the first lens. It is arranged so as to be orthogonal to the stripe of the lens and the lens surface thereof facing away from the glass substrate. Next, a second diffusion plate is disposed so as to be in contact with the second lens sheet. As the shape of the first and second lens sheets, a Δ-shaped stripe having an apex angle of 90 degrees and a pitch of 50 μm is formed of acrylic resin on a PET base material. A shape with a rounded apex (3M RBEF), a shape with a randomly changed pitch (3M BEF III), or other similar shapes may be used.

  As the first diffusion plate, a film in which beads for diffusing light are mixed is formed on a PET substrate of about 100 μm, and the transmittance is about 85% and the haze value is about 75%. As the second diffusion plate, a film in which beads for diffusing light are mixed is formed on a PET substrate of about 100 μm, and the transmittance is about 90% and the haze value is about 30%. The diffusion plate arranged in contact with the glass substrate may be bonded to the glass substrate via an optical adhesive. Further, a layer for diffusing light may be directly applied to the surface of the glass substrate, or a fine structure for diffusing light may be provided on the surface of the glass substrate. The glass substrate has been described above, but the substrate may be a resin substrate.

(2) When forming a microlens array on the surface of a substrate In an organic EL element comprising a glass substrate / transparent conductive film / light emitting layer / electrode / sealing layer, the side opposite to the surface on which the light emitting layer of the glass substrate is provided A microlens array sheet is affixed to the surface via an optical adhesive. Each microlens array sheet has a shape in which microlenses each having a square apex of 50 μm (pyramid shape) and an apex angle of 90 degrees are aligned at a pitch of 50 μm.

  The sheet is manufactured by injecting UV curable resin between a metal mold that is the mother mold of the microlens array and a glass plate placed between 0.5 mm spacers, and UV exposure from the glass substrate. By doing so, the resin is cured to obtain a microlens array sheet. Here, as the shape of each microlens, a conical shape, a triangular pyramid shape, a convex lens shape, or the like is applicable. Although described as a structure in which the microlens array sheet is attached to the glass substrate, the microlens array sheet may be attached to the resin substrate. Moreover, the structure of providing a transparent electrode / light emitting layer / electrode / sealing layer on the surface opposite to the surface provided with the microlens array of the microlens array sheet may be used.

(3) Structure for adhering the microlens array sheet downward to the surface of the substrate In an organic EL element comprising a glass substrate / transparent conductive film / light emitting layer / electrode / sealing layer, the surface of the glass substrate provided with the light emitting layer; Is affixed with a microlens array sheet on the opposite surface via an optical adhesive so that the concave and convex surface of the microlens faces the glass substrate side. The microlens array sheet has a shape in which microlenses having a structure in which the apexes of a rectangular shape each having a side of 50 μm are flat are arranged at a pitch of 50 μm. The flat top portion is adhered to the surface of the glass substrate. Here, as the shape of each microlens, a conical shape, a triangular pyramid shape, a convex lens shape, or the like is applicable. Although described as a structure in which the microlens array sheet is attached to the glass substrate, the microlens array sheet may be attached to the resin substrate.

  In order to further increase the light extraction efficiency, it is preferable to insert a low refractive index layer between the transparent electrode and the transparent substrate. When a medium having a low refractive index is formed between the transparent electrode and the transparent substrate with a thickness longer than the wavelength of light, the light extracted from the transparent electrode has a higher extraction efficiency to the outside as the refractive index of the medium is lower. Examples of the low refractive index layer include aerogel, porous silica, magnesium fluoride, and a fluorine-based polymer. Since the refractive index of the transparent substrate is generally about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Furthermore, it is preferable that it is 1.35 or less. The thickness of the low refractive index medium is preferably longer than the wavelength in the light medium, preferably twice or more. This is because the effect of the low refractive index layer is diminished when the thickness of the low refractive index medium is about the wavelength of light and the electromagnetic wave that has exuded by evanescent enters the substrate.

  Examples of the low refractive index layer according to the present invention will be described below. However, the present invention is not limited to these examples as long as the object effects are not impaired.

(A) Dispersion of hollow silica A method for producing a glass substrate having a low refractive index layer in which hollow silica is dispersed by a sol-gel method will be described. A low refractive index layer can be formed on a glass substrate by the following procedure.

Metal alkoxide (tetraethyl silicate Si (OC ₂ H ₅ ) ₄ [abbreviated TEOS]) as a raw material compound, ethanol as a solvent, acetic acid as a catalyst, and water necessary for hydrolysis are added to a preparation liquid having a low refractive index. A material (catalyst chemical industry, silica particles (refractive index: 1.35)) added to isopropyl alcohol is mixed, and kept at several tens of degrees C to cause hydrolysis and polycondensation reaction to produce a liquid sol. . When the prepared sol is applied on a glass substrate by spin coating and reacted, it is solidified as a gel. This is further dried in an atmosphere of 150 ° C. to obtain a dry gel, and the conditions of the solution preparation and spin coating are set so that the film thickness at that time becomes 0.5 μm. As a result, a low refractive index layer having a thickness of 0.5 μm and a refractive index of 1.37 is formed.

  Here, spin coating is described as the solution coating method, but any method that can obtain a uniform film thickness, such as dip coating, may be used. Although an example of a glass substrate is shown as the substrate, since the process temperature is 150 ° C. or less, it can be directly applied on the resin substrate. Further, further effects can be expected by selecting a lower refractive index as a raw material compound or a low refractive index material and setting the refractive index of the obtained low refractive index layer to 1.37 or less. The film thickness is preferably 0.5 μm or more, and more preferably 1 μm or more.

  Production of hollow silica is described in, for example, Japanese Patent Application Laid-Open Nos. 2001-167637, 2001-233611, and 2002-79616.

(B) In the case of silica airgel The transparent low refractive index layer is formed of silica airgel obtained by supercritical drying of a wet gel formed by a sol-gel reaction of silicon alkoxide. Silica airgel is a light-transmitting porous body having a uniform ultrafine structure. Liquid A was prepared by mixing tetramethoxysilane oligomer and methanol, and liquid B was prepared by mixing water, aqueous ammonia and methanol. An alkoxysilane solution obtained by mixing the A liquid and the B liquid is applied onto the substrate 2. After the alkoxysilane is gelled, it is immersed in a curing solution of water, aqueous ammonia, and methanol and cured at room temperature for one day. Next, the cured gel-like compound is immersed in an isopropanol solution of hexamethyldisilazane, hydrophobized, and then subjected to supercritical drying to form a silica airgel.

(C) In the case of porous silica As a low refractive index material, a film of a low relative dielectric constant material containing hexamethyldisiloxane or hexamethyldisilazane having water repellency is applied on a substrate to form a film. In addition to the water-repellent material such as hexamethyldisiloxane and hexamethyldisilazane, alcohol or butyl acetate may be added as an additive to the solution of the low dielectric constant material used here, if necessary. . Then, a low refractive index film made of a porous silica material is formed by evaporating the solvent, water, acid, alkali catalyst, surfactant, or the like in the solution of the low relative dielectric constant material by firing treatment or the like. This is washed to obtain a low refractive index film.

After forming a low refractive index film on the substrate in this way, an intermediate layer is formed on the low refractive index film directly or with a transparent insulating film made of a SiO ₂ film by, for example, RF sputtering, and then the intermediate layer is formed. An ITO film is formed on the layer by DC sputtering to form a substrate with a transparent electrode.

  In order to further increase the light extraction efficiency, for example, as described in Japanese Patent Application Laid-Open No. 11-283951, a method of introducing a diffraction grating into an interface or any medium that causes total reflection is used together. Is preferred. For example, a diffraction grating is formed on a glass substrate.

  This method is generated from the light emitting layer by utilizing the property that the diffraction grating can change the direction of light to a specific direction different from refraction by so-called Bragg diffraction such as first-order diffraction and second-order diffraction. Of the light, light that cannot go out due to total reflection between layers, etc., is diffracted by introducing a diffraction grating in any layer or medium (in the transparent substrate or transparent electrode) It tries to take out light.

  The introduced diffraction grating desirably has a two-dimensional periodic refractive index. This is because light emitted from the light-emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating having a periodic refractive index distribution only in a certain direction, only light traveling in a specific direction is diffracted. The light extraction efficiency does not increase so much.

  However, by making the refractive index distribution a two-dimensional distribution, light traveling in all directions is diffracted, and light extraction efficiency is increased. The position where the diffraction grating is introduced may be in any one of the layers or in the medium (in the transparent substrate or the transparent electrode) as described above, but is preferably in the vicinity of the light emitting layer where light is generated. At this time, the period of the diffraction grating is preferably about 1/2 to 3 times the wavelength of the light medium to be amplified. The arrangement of the diffraction grating is preferably two-dimensionally repeated such as a square lattice, a triangular lattice, or a honeycomb lattice.

  For example, in order to form a diffraction grating on a glass substrate, a positive resist is applied to the surface after cleaning the glass substrate. Next, two parallel lights having a wavelength λ that are coherent with each other are irradiated on the resist so as to face each other at an angle of θ degrees from the substrate vertical direction. At this time, interference fringes having a pitch d are formed in the resist. Here, d = λ / (2 cos θ). When an argon laser having a wavelength of 488 nm is used and a 300 nm pitch is formed as a photonic crystal, if both light beams are exposed at an angle of 35.6 degrees from a direction perpendicular to the substrate, a first interference fringe having a pitch of 300 nm is formed. Is done.

  Next, the substrate is rotated 90 degrees in the plane of the substrate to form a second interference fringe so as to be orthogonal to the first interference fringe. If the light beam to be exposed is maintained as it is, second interference fringes are formed at a pitch of 300 nm. Two interference fringes are superimposed on the resist and exposed to form a grid-like exposure pattern. By appropriately setting the exposure power and the development conditions, the development is performed so that the resist is removed only at the portion where the two interference fringes overlap and is strongly exposed. On the glass substrate, a pattern in which the resist is removed in a substantially circular shape is formed in a portion where the lattices having vertical and horizontal pitches of 300 nm overlap each other. The diameter of the circle is, for example, 220 nm.

  Next, dry etching is performed to form a hole having a depth of 200 nm in the portion where the range is removed. Thereafter, the resist is removed and the glass substrate is washed.

  As described above, a glass substrate in which holes having a depth of 200 nm and a diameter of 220 nm are arranged on the apexes of a square lattice having a pitch of 300 nm in length and width is formed on the surface. Next, an ITO film having a thickness of about 300 nm as measured from the bottom of the hole is formed by bias sputtering, and the surface unevenness can be flattened to 50 nm or less by appropriately controlling the bias sputtering conditions.

  By polishing the surface of the glass substrate with ITO produced as described above, a glass substrate with ITO for organic EL is formed. In addition to patterning by applying a photoresist to a glass substrate and etching the glass substrate, a glass mold is formed by a similar method, and a UV-curable resist is transferred onto the glass substrate by a nanoimprinting method. An etching method is also possible. In addition, the pattern formed on the glass substrate is transferred to a mold by a technique such as nickel electroforming, and the mold is transferred to a resin by a nanoimprint technique. Is possible.

  In the organic EL element using the light extraction and / or light collecting sheet as described above, the front luminance amplification factor is increased. The light extracted in this way has a chromaticity of CIE 1931 color system of x = 0.33 ± 0.07, y = 0.33 when the 2 ° C. viewing angle front luminance is measured by the above method. The so-called white light in the range of ± 0.07 is adjusted. Usually, the emission color is classified into blue light from 420 nm to less than 500 nm, blue light from 500 nm to less than 550 nm, and red light from 600 nm to less than 650 nm.

  Therefore, although depending on the material (substantially dopant) that emits light, in the present invention, the front luminance peak value of the organic EL element when there is no light extraction and / or condensing sheet is as compared to the case where the sheet is present. Qualitatively, blue is the smallest ratio.

  In the lifetime in continuous driving or the like, generally, the blue color is rate-determined. Therefore, when such a light extraction and / or condensing sheet is used, the organic EL element can have a longer lifetime. In addition, the driving voltage is limited by blue, which has the largest energy gap between HOMO and LUMO. Therefore, the organic EL element with improved light extraction has a design that requires less blue front luminance and reduces the driving voltage. Can be lowered.

  That is, since the blue light emitting layer can be made thin and the driving voltage can be lowered, the life can be increased compared with the case where there is no light extraction and / or condensing sheet. Can be.

  Here, the amplification factor of the front luminance by the light extraction and / or the condensing sheet is determined by using a spectral radiance meter (for example, CS-1000 (manufactured by Konica Minolta Sensing)) or the like, and the emission luminance from the front (2 ° C. field of view). Angle frontal brightness) is measured in the required visible light wavelength range with the optical axis of the spectral radiance meter aligned with the normal from the light emitting surface with and without light extraction and / or light collector sheet. Integrate and take the ratio.

<< Method for producing organic EL element >>
As an example of the method for producing the organic EL device of the present invention, a method for producing an organic EL device comprising an anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode will be described. First, a desired electrode material, for example, a thin film made of a material for an anode is formed on a suitable support base by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably 10 to 200 nm, thereby producing an anode. To do.

  Next, an organic compound thin film of a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, and an electron transport layer, which are organic EL element materials, is formed thereon. As a method for thinning the organic compound thin film, there are a vapor deposition method and a wet process (spin coating method, casting method, ink jet method, printing method) as described above, but it is easy to obtain a uniform film and a pinhole. From the point of being difficult to form, a vacuum deposition method, a spin coating method, an ink jet method, and a printing method are particularly preferable. Further, different film forming methods may be applied for each layer.

When a vapor deposition method is employed for film formation, the vapor deposition conditions vary depending on the type of compound used, but generally a boat heating temperature of 50 to 450 ° C., a vacuum degree of 10 to 10 ⁻² Pa, a vapor deposition rate of 0.01 to 50 nm / It is desirable to appropriately select the second, substrate temperature −50 to 300 ° C., film thickness 0.1 nm to 5 μm, preferably 5 to 200 nm.

  After these layers are formed, a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably 50 to 200 nm, and a cathode is provided. Thus, a desired organic EL element can be obtained. The organic EL element is preferably produced from the hole injection layer to the cathode consistently by a single evacuation, but may be taken out halfway and subjected to different film forming methods. At that time, it is necessary to consider that the work is performed in a dry inert gas atmosphere. In addition, it is also possible to reverse the production order and produce the cathode, the electron injection layer, the electron transport layer, the light emitting layer, the hole transport layer, the hole injection layer, and the anode in this order. When a DC voltage is applied to the multicolor display device thus obtained, light emission can be observed by applying a voltage of about 2 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. An alternating voltage may be applied. The alternating current waveform to be applied may be arbitrary.

<Application>
The organic electroluminescence element of the present invention can be used as a display device, a display, or various light sources. Examples of light sources include home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, and light sources for optical sensors. Although it is not limited to this, it can be effectively used especially as a backlight of a liquid crystal display device combined with a color filter and a light source for illumination. In the organic electroluminescence element of the present invention, patterning may be performed by a metal mask, an ink jet printing method, or the like at the time of film formation, if necessary. When patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire element layer may be patterned.

<Display device>
The display device of the present invention will be described. The display device of the present invention is used for a multicolor or white display device. In the case of a multicolor or white display device, a shadow mask is provided only at the time of forming a light emitting layer, and a film can be formed on one surface by a vapor deposition method, a cast method, a spin coating method, an ink jet method, a printing method, or the like. When patterning is performed only on the light-emitting layer, the method is not limited, but a vapor deposition method, an inkjet method, and a printing method are preferable. In the case of using a vapor deposition method, patterning using a shadow mask is preferable. Further, the order of preparation is reversed, and the cathode, the electron transport layer, the hole blocking layer, the light emitting layer unit (having at least three light emitting layers and having a non-light emitting intermediate layer between each light emitting layer) It is also possible to produce the hole transport layer and the anode in this order.

  When a DC voltage is applied to the multicolor or white display device thus obtained, light emission can be observed by applying a voltage of about 2 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. Further, even when a voltage is applied with the opposite polarity, no current flows and no light emission occurs. Further, when an AC voltage is applied, light is emitted only when the anode is in the + state and the cathode is in the-state. The alternating current waveform to be applied may be arbitrary. Light sources include home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, light sources for optical sensors, etc. Although it is mentioned, it is not limited to these.

《Lighting device》
The lighting device of the present invention will be described. The organic EL device of the present invention may be used as a kind of lamp such as an illumination or exposure light source, a projection device that projects an image, or a display device that directly recognizes a still image or a moving image. (Display) may be used. When used as a display device for reproducing moving images, the driving method may be either a simple matrix (passive matrix) method or an active matrix method. In the white organic electroluminescent element used for this invention, you may pattern by a metal mask, the inkjet printing method, etc. at the time of film forming as needed. When patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire element layer may be patterned. There is no restriction | limiting in particular as a luminescent material used for a light emitting layer, For example, if it is a backlight in a liquid crystal display element, the platinum complex which concerns on this invention so that it may correspond to the wavelength range corresponding to CF (color filter) characteristic, Any one of known light emitting materials may be selected and combined, or combined with the light extraction and / or light collecting sheet according to the present invention to be whitened.

  As described above, the white organic EL element used in the present invention is combined with CF (color filter), and the element and the driving transistor circuit are arranged in accordance with the CF (color filter) pattern. As described above, the white light extracted from the organic electroluminescence device is used as a backlight, and blue light, green light, and red light are obtained through a blue filter, a green filter, and a red filter, so that a long drive voltage can be obtained. A full-color organic electroluminescence display having a long life can be obtained, which is preferable.

  Further, in addition to these displays, various light-emitting light sources and lighting devices are usefully used in display devices such as backlights for liquid crystal display devices as household lamps, interior lighting, and a kind of lamp such as an exposure light source. . Others such as backlights for watches, signboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, light sources for optical sensors, etc. There are a wide range of uses such as household appliances.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.

Example 1
<< Preparation of organic EL elements 101 and 102 >>
Transparent support with this ITO transparent electrode after patterning on a substrate (also called support base) on which a 120 nm ITO (indium tin oxide) film is formed on a glass substrate of 30 mm × 30 mm and 0.4 mm thickness as an anode The substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes. This transparent support base was fixed to a substrate holder of a commercially available vacuum deposition apparatus.

  F4-TCNQ, m-MTDATA, BCzVBi, DPVBi, CBP, phosphorescence G, phosphorescence R, HB, BCP, and CsF were filled in the respective crucibles for vapor deposition in the vacuum deposition apparatus, respectively, in the optimum amounts for device fabrication. The evaporation crucible used was made of a resistance heating material made of molybdenum or tungsten.

Next, after reducing the vacuum to 4 × 10 ⁻⁴ Pa, the evaporation crucible containing F4-TCNQ and m-MTDATA is energized and heated so that the volume concentration of F4-TCNQ is uniformly 2%. Vapor deposition was performed on the ITO electrode side of the transparent support base at a total deposition rate of 0.1 nm / second, and a 40 nm hole injection / transport layer containing an acceptor was provided.

  Further, a current is applied to the crucible for deposition loaded with each material so that each layer is formed with the materials and mixing ratios shown in Table 1, and co-evaporation or single deposition is performed to form a hole transport / injection layer, light emitting layer 1 The intermediate layer 1, the light emitting layer 2, the intermediate layer, the light emitting layer 3, the hole blocking layer, and the electron injection / transport layer were formed.

  Finally, aluminum 110 nm was vapor-deposited to form a cathode, and an organic EL device 101 was produced.

  The organic EL element 102 was produced in the same manner as the organic EL element 101 except that the volume concentration of F4-TCNQ was uniformly 3%.

  1 and 2 show that the F4-TCNQ volume concentration in the hole injecting / transporting layer is uniformly 2% and 3%, respectively, depending on the film thickness from the anode toward the light emitting layer 1.

  Finally, the vapor deposition surface side was covered with a glass case, and the organic EL element 101 was carried out in a glove box under a nitrogen atmosphere (in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more) without being brought into contact with the atmosphere. 10 and 11 are schematic views and cross-sectional views of the lighting device. In FIG. 11, 15 is a cathode, 16 is an organic EL layer, and 17 is a glass substrate with a transparent electrode. The glass cover 12 is filled with nitrogen gas 18 and a water catching agent 19 is provided.

<< Production of Organic EL Elements 103 to 108 >>
As shown in FIGS. 3 to 7, the organic EL elements 103 to 107 change the F4-TCNQ volume concentration in the hole injection / transport layer according to the film thickness in the direction from the anode to the light emitting layer 1, Each structure in the injection / transport layer was prepared in the same manner as the organic EL element 101. Further, an organic EL element 108 was produced in the same manner as the organic EL element 106 except that the blue material of the organic EL element 106 was changed to Fir (pic) 3% and changed to all-color phosphorescence. The configuration of the organic EL element 108 in the hole injection / transport layer is the same as that of the organic EL element 106.

  Specifically, for example, for the organic EL element 103, the F4-TCNQ volume concentration is 18 nm from the anode side in the total film thickness of 40 nm of the hole injection / transport layer under the condition of the total deposition rate of 0.1 nm / second. Was 4%, 4 nm was 3%, and the remaining 18 nm was 2%. The organic EL elements 104 to 108 were produced in the same manner.

  Furthermore, sealing was performed in the same manner as in the organic EL element 101 to produce a lighting device.

  The numbers in parentheses in Table 1 represent mass%.

<< Evaluation of organic EL elements >>
The front luminance of each element produced as described above was evaluated. Here, all the elements have a chromaticity in the range of X = 0.33 ± 0.07 and Y = 0.33 ± 0.07 in the CIE1931 color system at 2 ° C. viewing angle front luminance of 1000 cd / m ^2. Yes, it was confirmed to be white. The light emission conditions of the element were measured at a constant luminance (1000 cd / cm ² ), and the obtained driving voltage results are shown in Table 2. Further, the luminance half-life at the initial luminance (1000 cd / cm ² ) was evaluated, and the results are shown in Table 2.

  From Table 2, the driving voltage slightly increases in the organic EL elements 103 to 105 of the present invention in which the high concentration region is locally provided at 4 nm near the center with respect to the film thickness of the hole injection and transport layer of 40 nm. Although there is a trend, it can be seen that the current efficiency is improved.

  Further, when comparing the organic EL elements 104 and 106 of the present invention, the degree of power saving was substantially the same, but an improvement over the uniform concentration was recognized. When the concentration on the cathode side was lowered as in the organic EL device 107 of the present invention, a power saving effect was recognized, and an improvement in driving life was recognized. This is a surprising effect that was unexpected.

It is a figure which shows F4-TCNQ volume concentration in the positive hole injection | pouring / transport layer of the organic EL element 101 according to the film thickness from the anode to the light emitting layer 1 direction. It is a figure which shows F4-TCNQ volume concentration in the positive hole injection | pouring / transport layer of the organic EL element 102 according to the film thickness from the anode to the light emitting layer 1 direction. It is a figure which shows F4-TCNQ volume concentration in the positive hole injection | pouring / transport layer of the organic EL element 103 according to the film thickness from an anode to the light emitting layer 1 direction. It is a figure which shows F4-TCNQ volume concentration in the positive hole injection | pouring / transport layer of the organic EL element 104 according to the film thickness from the anode to the light emitting layer 1 direction. It is a figure which shows F4-TCNQ volume concentration in the positive hole injection | pouring / transport layer of the organic EL element 105 according to the film thickness from the anode to the light emitting layer 1 direction. It is a figure which shows F4-TCNQ volume concentration in the positive hole injection | pouring / transport layer of the organic EL element 106 according to the film thickness from the anode to the light emitting layer 1 direction. It is a figure which shows F4-TCNQ volume concentration in the positive hole injection | pouring / transport layer of the organic EL element 107 according to the film thickness from the anode to the light emitting layer 1 direction. It is a schematic diagram which shows an example of the laminated constitution of a barrier film, and its density profile. It is the schematic which shows an example of the atmospheric pressure plasma discharge processing apparatus which processes a base material. It is the schematic of an illuminating device. It is sectional drawing of an illuminating device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Glass substrate 12 Glass case 15 Cathode 16 Organic EL layer 17 Transparent electrode 18 Nitrogen gas 19 Water trapping agent 201 Barrier film 202 Base material 203 Low density layer 204 Medium density layer 205 High density layer 230 Plasma discharge treatment apparatus 231 Plasma discharge treatment vessel 231 235 Roll rotation electrode 236 Square tube type fixed electrode group 240 Electric field application means 250 Gas supply means 251 Gas generator 253 Exhaust port 260 Electrode temperature adjustment means F Base material P Liquid feed pump 261 Piping 266 Nip roll 267 Guide roll 268, 269 Partition plate

Claims (11)

In an organic electroluminescent device comprising an anode, at least one organic layer and a cathode on a substrate, at least one of the organic layers contains an electron acceptor, and the volume concentration of the electron acceptor in the organic layer ( %) Is 0.1 to 30%, and there are electron acceptor concentration regions different by 3% or more, and the organic electroluminescence device. 2. The organic electroluminescence device according to claim 1, wherein the difference between the maximum concentration and the minimum concentration of the volume concentration (%) in which the electron acceptor is contained is 1 to 30%. The thickness of each of the regions containing the maximum concentration or the minimum concentration of the electron acceptor is 1/100 to 1/2 of the thickness of the organic layer containing the electron acceptor. 3. The organic electroluminescence device according to 1 or 2. The electron acceptor is contained in a region where the distance between the organic layer containing the electron acceptor and the adjacent layer interface on the cathode side is within 1/3 of the film thickness of the organic layer containing the electron acceptor. The organic electroluminescent element according to claim 1, wherein the volume concentration (%) is 1% or less. 5. The organic electroluminescence device according to claim 1, wherein there are at least three electron acceptor concentration regions different by 3% or more. 6. The organic electroluminescent element according to claim 1, wherein the organic layer containing the electron acceptor is in contact with the anode. The organic electroluminescent element according to claim 1, wherein the organic layer has a light emitting layer containing at least one light emitting dopant (phosphorescent compound). The organic electroluminescent element according to claim 1, wherein the organic layer includes a light emitting layer containing a phosphorescent compound and a light emitting layer containing a fluorescent compound. The organic electroluminescence device according to claim 8, wherein the light emitting layer containing the fluorescent compound emits blue light. It is white light emission, The organic electroluminescent element of any one of Claims 1-9 characterized by the above-mentioned. An organic electroluminescence display, wherein blue light, green light, and red light are obtained from white light extracted from the organic electroluminescence element according to claim 10 through a blue filter, a green filter, and a red filter.

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