JP2015064958A - Transparent electrode and organic electroluminescence device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent electrode capable of suppressing deterioration in surface smoothness of a transparent electrode due to ununiformity of the height of a transparent conductive layer, and an organic EL element including the transparent electrode.SOLUTION: In a transparent electrode, a transparent conductive layer (20) is formed on a formation region of the transparent electrode on a transparent base materia (10), the transparent electrode having a surface of the transparent base material (12) and a fine line structure portion (13). The fine line structure portion (13) has a reverse-tapered shape in a cross section. As a result, the height of the transparent conductive layer (20) can be uniformed.

Description

  The present invention relates to a transparent electrode and an organic electroluminescence device including the transparent electrode.

  In recent years, as a next-generation display device following a liquid crystal display element (LCD), a light-emitting element type display panel in which self-light-emitting elements such as organic electroluminescence elements (hereinafter abbreviated as “organic EL elements”) are two-dimensionally arranged is provided. Research and development of light emitting devices are underway.

  The organic EL element includes an anode, a cathode, and an organic EL layer (light emitting functional layer) formed between the pair of electrodes, for example, having an organic light emitting layer and a hole injection layer. In the organic EL element, light is emitted by energy generated by recombination of holes and electrons in the organic light emitting layer.

  The transparent electrode on the light extraction side of such an organic EL element is generally formed using tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), or the like. Is done. However, in order to obtain low resistance, it is necessary to form a thick and uniform film, which reduces the light transmittance, becomes expensive, and requires a high temperature treatment in the formation process. There is a limit to the above-described reduction in resistance (see, for example, Patent Document 1).

  Therefore, in recent years, a transparent electrode technique that does not use ITO has been proposed. For example, a conductive surface in which a thin wire structure portion of metal and / or alloy such as a uniform mesh shape, a comb shape or a grid shape is prepared, and a conductive polymer material is dissolved in an appropriate solvent on the conductive surface. There has been proposed a method of forming a transparent electrode by applying a dispersed ink using a coating method or a printing method to form a transparent conductive layer (for example, see Patent Documents 2 and 3).

Japanese Patent Application Laid-Open No. 10-162961 JP 2005-302508 A JP 2006-93123 A

  In the method for forming a transparent conductive layer described above, for example, when a conductive polymer material ink is applied using a coating method or a printing method, the solvent contained in the ink evaporates after being discharged or transferred onto the substrate. Although the film is dried and solidified, the conductive polymer material flows during the drying process of the ink because the film is affected by the shape of the fine wire structure of the metal and / or alloy placed under the film. The transparent conductive layer is formed in a bowl shape with a thick film near the fine line structure and a thin film at the central part, or a convex shape with a thin film thickness near the fine line structure and a thick film at the central part. There is a problem that the film thickness becomes non-uniform.

  If the surface shape of the transparent electrode becomes non-uniform, for example, when used as a transparent electrode of an organic EL element, the electric field strength applied to the organic EL layer becomes non-uniform. The wavelength of light emitted from the organic EL layer (that is, chromaticity at the time of light emission) deviates from the design value, so that a desired light emission color cannot be obtained, and the organic EL layer (organic EL element) is in a region where the electric field is concentrated. There has been a problem that the deterioration of the light emission becomes remarkable and the reliability and life of light emission are reduced.

  The present invention has been made in view of the above situation, and a transparent electrode capable of suppressing variations in the conductivity of the transparent electrode due to non-uniform film thickness of the transparent conductive layer in the region excluding the thin line structure portion forming region, An object of the present invention is to provide an organic EL device including the same.

In order to achieve the above object, a transparent electrode according to one aspect of the present invention covers a transparent base material, a fine wire structure portion that is disposed on the transparent base material and is formed of a conductive material, and covers the fine wire structure portion. In the transparent electrode having the transparent conductive layer arranged as described above, the fine wire structure portion has a reverse tapered shape in cross section.
The cross section is a cross section viewed from the axial direction of the thin wire structure portion. It suffices that the side surface of the fine wire structure portion faces the transparent substrate side. That is, the angle between the surface of the transparent substrate and the side surface of the fine wire structure is less than 90 degrees, preferably 60 degrees or less.
The transparent conductive layer may be formed using a wet coating method.
The transparent conductive layer may be present at a position lower than the height of the fine line structure portion in the region formed on the transparent substrate.
The transparent conductive layer may contain polythiophene, polythiophene derivatives, or a mixture of polythiophene and polythiophene derivatives.
The transparent conductive layer may contain polyaniline, a polyaniline derivative, or a mixture of polyaniline and a polyaniline derivative.
The organic electroluminescent element which is 1 aspect of this invention is equipped with the above-mentioned transparent electrode, It is characterized by the above-mentioned.

  In the transparent electrode of the aspect of the present invention, it is possible to make the transparent conductive layer film thickness uniform in the region excluding the fine line structure portion forming region by specifying the cross-sectional shape of the fine wire structure portion. Therefore, according to the aspect of the present invention, an organic electroluminescence element having high emission quality can be obtained.

It is a schematic plan view which shows the manufacturing method of a transparent electrode. It is process sectional drawing which illustrates the principal part specific of the manufacturing method of the transparent electrode which concerns on embodiment. It is process sectional drawing which illustrates the principal part specific example of the manufacturing method of the transparent electrode which concerns on a comparative example.

[Embodiment]
Hereinafter, a method for producing a transparent electrode, a transparent electrode, and an organic EL element including the same according to embodiments of the present invention will be described.

<Configuration of transparent electrode>
The transparent electrode of the present embodiment includes a transparent substrate 12, a fine wire structure portion 13 made of a metal and / or an alloy, and a transparent conductive layer 20 formed using a coating method or a printing method (FIG. 2 ( b)). A transparent electrode is normally provided on the transparent base material 12, and the thin wire | line structure part 13 and the transparent conductive layer 20 are produced in this order from the base material 12 side, and are comprised.

  From the viewpoint of improving luminance when the transparent electrode of the present embodiment is used in an organic EL element, the surface resistivity of the conductive surface of the transparent electrode is preferably 0.01Ω / □ or more and 100Ω / □ or less. More preferably, it is 0.1Ω / □ or more and 10Ω / □ or less.

  The transparent electrode of the present embodiment can be used for transparent electrodes such as LCDs, electroluminescence elements, plasma displays, electrochromic displays, solar cells, touch panels, electronic paper, electromagnetic wave shielding materials, etc. Since it is excellent and has high smoothness, it is preferably used for an organic EL device.

(Transparent substrate 12)
In the present embodiment, a plastic film, a plastic plate, glass, or the like can be used as the transparent substrate 12.

  Examples of raw materials for plastic films and plastic plates include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate, polyolefins such as polyethylene (PE), polypropylene (PP), polystyrene and EVA, polyvinyl chloride, poly Vinyl resins such as vinylidene chloride, polyether ether ketone (PEEK), polysulfone (PSF), polyether sulfone (PES), polycarbonate (PC), polyamide, polyimide, acrylic resin, triacetyl cellulose (TAC), etc. are used. be able to.

  The transparent substrate 12 is preferably excellent in surface smoothness. As for the smoothness of the surface, the arithmetic average roughness Ra is preferably 5 nm or less and the maximum height Ry is preferably 50 nm or less, more preferably Ra is 1 nm or less and Ry is 20 nm or less. The surface of the transparent substrate 12 may be smoothed by applying an undercoat layer such as a thermosetting resin, an ultraviolet curable resin, an electron beam curable resin, or a radiation curable resin, or may be smoothed by mechanical processing such as polishing. It can also be. Further, in order to improve the application and adhesion of the transparent conductive layer 20, surface treatment with corona, plasma, or UV / ozone may be performed. Here, the smoothness of the surface can be calculated from measurement using an atomic force microscope (AFM) or the like.

  In addition, it is preferable to provide a gas barrier layer for the purpose of blocking oxygen and moisture in the atmosphere. As a material for forming the gas barrier layer, metal oxides such as silicon oxide, silicon nitride, silicon oxynitride, aluminum nitride, and aluminum oxide, and metal nitrides can be used. These materials have an oxygen barrier function in addition to a water vapor barrier function. In particular, silicon nitride and silicon oxynitride having favorable barrier properties, solvent resistance, and transparency are preferable. Further, the gas barrier layer can have a multi-layer structure as necessary. In that case, you may comprise only an inorganic layer and may comprise an inorganic layer and an organic layer. As a method for forming the gas barrier layer, a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, or a sputtering method can be used depending on the material. Further, the thickness of the gas barrier layer is not particularly limited, but typically it is preferably in the range of 5 nm to 500 nm per layer, more preferably 10 nm to 200 nm per layer. The gas barrier layer is provided on at least one surface of the transparent substrate 12 and is preferably provided on both surfaces.

(Thin wire structure 13)
The thin wire structure portion 13 in this embodiment preferably has a low electric resistance, and a material having an electric conductivity of 10 ⁷ S / cm or more is usually used. Specific examples of such a conductive material include metals such as aluminum, silver, chromium, gold, copper, tantalum, and molybdenum and / or alloys thereof. Among these, aluminum, chromium, copper, silver and alloys thereof are preferable from the viewpoint of high electrical conductivity and ease of material handling.

  In the present embodiment, the conductive material described above is provided with a fine mesh structure 13 such as a uniform mesh shape, a comb shape, or a grid shape, and a conductive surface is produced to improve conductivity. The width of the thin wire of the metal or alloy is arbitrary, but is preferably between about 0.1 μm and 1000 μm. The fine wires of the metal or alloy are preferably arranged at a pitch of an interval selected from a range of 50 μm or more and 5 cm or less, and a pitch of an interval selected from a range of 100 μm or more and 1 cm or more is particularly preferable.

  By arranging the fine wire structure 13 of metal and / or its alloy, the light transmittance is reduced. Therefore, it is important that the reduction is as small as possible. The distance between the fine wires is too narrow or the fine wire width is increased. It is important to ensure a light transmittance of preferably 80% or more without taking too much. Regarding the relationship between the fine line width and the fine line interval, the fine line width may be determined according to the purpose on the plane arrangement, but is preferably 1 / 10,000 or more and 1/5 or less, more preferably 1/100 or more of the fine line interval. 1/10 or less.

  The height (thickness) of the thin wire structure portion 13 of the metal and / or its alloy is preferably 0.05 μm or more and 10 μm or less, more preferably 0.1 μm or more and 1 μm or less. As for the relationship between the fine line width and the fine line height, the fine line height may be determined according to the desired conductivity, but it is preferably used in the range of 1 / 10,000 or more and 10 times or less of the fine line width.

  The fine wire structure 13 of the metal and / or alloy thereof in the present embodiment preferably has an inversely tapered shape in which the left and right side surfaces have an angle of less than 90 degrees with respect to the surface of the transparent substrate 12, The angle is more preferably 60 degrees or less. As a result, when the transparent conductive layer 20 to be formed next is formed by using the wet coating method, the flatness of the transparent conductive layer 20 in the region 14 excluding the region where the fine line structure portion 13 is formed is improved. Is possible.

(Transparent conductive layer 20)
The solution used when forming the transparent conductive layer 20 by a coating method includes a material to be the transparent conductive layer 20 and a solvent. The transparent conductive layer 20 preferably contains a polymer compound exhibiting conductivity. The polymer compound may contain a dopant. The conductivity of the polymer compound is usually 10 ⁻⁵ S / cm or more and 10 ⁵ S / cm or less, and preferably 10 ⁻³ S / cm or more and 10 ⁵ S / cm or less in terms of conductivity. Moreover, it is preferable that the transparent conductive layer 20 is made of a polymer compound substantially exhibiting conductivity. Examples of the constituent material of the transparent conductive layer 20 include polyaniline and derivatives thereof, polythiophene and derivatives thereof, and the like. As the dopant, a known dopant can be used, and examples thereof include organic sulfonic acids such as polystyrene sulfonic acid and dodecylbenzene sulfonic acid, and Lewis acids such as PF ₅ , AsF ₅ , and SbF ₅ . Further, the polymer compound exhibiting conductivity may be a self-doped polymer compound in which a dopant is directly bonded to the polymer compound.

  The transparent conductive layer 20 is preferably composed of polythiophene and / or a polythiophene derivative, and is preferably substantially composed of polythiophene and / or a polythiophene derivative (the polythiophene and / or the polythiophene derivative contains a dopant). You may). Polythiophene, a derivative of polythiophene, or a mixture of polythiophene and a derivative of polythiophene is preferably used as a solute of a coating solution used in a coating method because it is easily dissolved or dispersed in an aqueous solvent such as water and alcohol. Moreover, these have high electroconductivity and are used suitably as an electrode material. Furthermore, these have a HOMO energy of about 5.0 eV, a difference from the HOMO energy of an organic light emitting layer used in a normal organic EL element is as low as about 1 eV, and holes are efficiently injected into the organic light emitting layer. In particular, it can be suitably used as an anode material. Further, it has high transparency and is suitably used as an electrode on the light emission extraction side of the organic EL element.

  The transparent conductive layer 20 preferably includes polyaniline and / or a polyaniline derivative, and is preferably substantially composed of polyaniline and / or a polyaniline derivative (the polyaniline and / or the polyaniline derivative contains a dopant). You may). Polyaniline and / or polyaniline derivatives are excellent in conductivity and stability, and are therefore preferably used as electrode materials. Further, it has high transparency and is suitably used as an electrode on the light emission extraction side of the organic EL element.

<Method for producing transparent electrode>
The manufacturing method of the transparent electrode which concerns on this embodiment is demonstrated. Usually, on the transparent base material 12, the thin wire | line structure part 13 and the transparent conductive layer 20 are produced and manufactured in this order from the transparent base material 12 side.

  In the method for producing a transparent electrode according to the present embodiment, first, the above-described fine wire structure portion 13 is formed in the transparent electrode forming region on the one surface side of the above-described transparent substrate 12.

  The method for forming the fine wire structure 13 is not particularly limited. For example, the constituent material of the fine wire structure 13 by a resistance heating vapor deposition method, an electron beam vapor deposition method, a sputtering method, or a laminating method in which a metal thin film is thermally compressed is used. There is a method of forming the above-described pattern by an etching method using a photoresist after the film is formed. After masking with a resist, it can be formed using a dry etching method represented by reactive ion beam etching, reactive gas etching, reactive ion etching, and the like. Further, a wet etching method using a liquid chemical having a property of being corroded and dissolved can be used. By changing the etching conditions, it is possible to adjust the angle of the side surface of the thin line structure portion 13 with respect to the surface of the transparent substrate 12. As a result, the fine wire structure 13 can be formed in an inversely tapered shape.

  Moreover, the film-forming from the solution containing the material used as the thin wire | line structure part 13 can be mentioned. The solvent used for film formation from a solution is not particularly limited as long as it dissolves the material that becomes the fine wire structure portion 13. Examples of film forming methods from solution include spin coating, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, and slit coating. Can be mentioned. A method of forming the above-described pattern by an etching method using a photoresist after drying and solidifying to form a film made of the constituent material of the fine line structure portion 13 can be mentioned. After masking with a resist, it can be formed using a dry etching method represented by reactive ion beam etching, reactive gas etching, reactive ion etching, and the like. Further, a wet etching method using a liquid chemical having a property of being corroded and dissolved can be used. By changing the etching conditions, it is possible to adjust the angle of the side surface of the thin line structure portion 13 with respect to the surface of the transparent substrate 12.

  Next, a transparent conductive layer 20 is formed by applying a coating conductive material to the transparent electrode forming region. Film formation methods include spin coating, casting, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, screen printing, flexographic printing. And an application method such as an offset printing method, a slit coating method, an ink jet printing method, and a nozzle printing method. In particular, since the transparent electrode forming region is formed over the entire surface, a uniform coating method is preferable, and can be selected as appropriate. A spin coating method, a bar coating method, a wire bar coating method, a dip coating can be used. A coating method such as a coating method, a spray coating method, a slit coating method, a casting method, a micro gravure coating method, a gravure coating method, or a roll coating method is suitable.

  Next, the transparent base material 12 on which the coating conductive material is coated on the entire surface where the transparent electrode is formed is heat-treated in a drying chamber at a temperature condition of, for example, 100 ° C. or higher. Thereby, the solvent contained in the applied conductive material solution is vaporized, and the applied conductive material is fixed on the transparent base material 12 and the fine wire structure portion 13, thereby forming the transparent conductive layer 20.

<Configuration of organic EL element>
The organic EL element in this embodiment has the transparent electrode described above. The organic EL element in the present embodiment uses the transparent electrode as an anode, and the organic light-emitting layer and the cathode can be made of any material and configuration generally used for organic EL elements. As an element structure of an organic EL element, the thing of the following various structures can be mentioned.
Anode / organic light emitting layer / cathode,
Anode / hole transport layer / organic light emitting layer / electron transport layer / cathode,
Anode / hole injection layer / hole transport layer / organic light emitting layer / electron transport layer / cathode,
Anode / hole injection layer / organic light emitting layer / electron transport layer / electron injection layer / cathode,
Anode / hole injection layer / organic light emitting layer / electron injection layer / cathode,
Here, the symbol “/” indicates that the layers sandwiching the symbol “/” are adjacently stacked. The same applies hereinafter.

The organic EL device of the present embodiment may have two or more organic light emitting layers, and examples of the organic EL device having two organic light emitting layers include the following layer configurations.
Anode / charge injection layer / hole transport layer / organic light emitting layer / electron transport layer / charge injection layer / charge generation layer / charge injection layer / hole transport layer / organic light emitting layer / electron transport layer / charge injection layer / cathode Specifically, as an organic EL device having three or more organic light emitting layers, (charge generation layer / charge injection layer / hole transport layer / organic light emission layer / electron transport layer / charge injection layer) is one Examples of the repeating unit include a layer structure including two or more repeating units described below.
Anode / charge injection layer / hole transport layer / organic light emitting layer / electron transport layer / charge injection layer / (the repeating unit) / (the repeating unit) /.../ cathode In the above layer structure, the anode, cathode, organic Each layer other than the light emitting layer can be deleted as necessary.
Here, the charge generation layer is a layer that generates holes and electrons by applying an electric field. Examples of the charge generation layer include a thin film made of vanadium oxide, ITO, molybdenum oxide, or the like.

  Hereinafter, the hole injection layer, the hole transport layer, the organic light emitting layer, the electron transport layer, the electron injection layer, and the cathode will be described.

(Layer provided between the anode and the organic light emitting layer)
Examples of the layer provided between the anode and the organic light emitting layer as needed include a hole injection layer, a hole transport layer, and an electron blocking layer. The hole injection layer is a layer having a function of improving the efficiency of hole injection from the anode, and the hole transport layer has a function of improving hole injection from the hole injection layer or a layer closer to the anode. Is a layer. When the hole injection layer or the hole transport layer has a function of blocking electron transport, these layers may be referred to as an electron block layer. Having the function of blocking electron transport, for example, it is possible to produce an element that allows only electron current to flow, and to check the effect of blocking by reducing the current value,
(Hole injection layer)
The hole injection layer can be provided between the anode and the hole transport layer or between the anode and the organic light emitting layer. As a material constituting the hole injection layer, a known material can be appropriately used, and there is no particular limitation. For example, phenylamine, starburst amine, phthalocyanine, hydrazone derivative, carbazole derivative, triazole derivative, imidazole derivative, oxadiazole derivative having amino group, oxide such as vanadium oxide, tantalum oxide, molybdenum oxide, amorphous Examples thereof include carbon, polyaniline, and polythiophene derivatives.

  As a film formation method of the hole injection layer, for example, film formation from a solution containing a material (hole injection material) that becomes the hole injection layer can be mentioned. The solvent used for film formation from a solution is not particularly limited as long as it dissolves the hole injection material. Chlorine solvents such as chloroform, methylene chloride and dichloroethane, ether solvents such as tetrahydrofuran, toluene, Mention may be made of aromatic hydrocarbon solvents such as xylene, ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as ethyl acetate, butyl acetate and ethyl cellosolve acetate, and water.

  As a film forming method from a solution, a spin coating method, a casting method, a micro gravure coating method, a gravure coating method, a bar coating method, a roll coating method, a wire bar coating method, a dip coating method, a spray coating method, a screen printing method, Examples of the coating method include a flexographic printing method, an offset printing method, a slit coating method, an ink jet printing method, and a nozzle printing method.

  The thickness of the hole injection layer is preferably 5 nm or more and 300 nm or less. If the thickness is less than 5 nm, the production tends to be difficult. On the other hand, if the thickness exceeds 300 nm, the driving voltage and the voltage applied to the hole injection layer tend to increase.

(Hole transport layer)
The material constituting the hole transport layer is not particularly limited. For example, N, N′-diphenyl-N, N′-di (3-methylphenyl) 4,4′-diaminobiphenyl (TPD), 4 , 4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPB) and other aromatic amine derivatives, polyvinylcarbazole or derivatives thereof, polysilane or derivatives thereof, aromatic amines in the side chain or main chain Polysiloxane derivative having pyrazole, pyrazoline derivative, arylamine derivative, stilbene derivative, triphenyldiamine derivative, polyaniline or derivative thereof, polythiophene or derivative thereof, polyarylamine or derivative thereof, polypyrrole or derivative thereof, poly (p-phenylene vinylene) Or its derivatives, or poly (2,5-thienylene vinylene) or a derivative thereof is exemplified.

  Among these, as the hole transport material used for the hole transport layer, polyvinyl carbazole or a derivative thereof, polysilane or a derivative thereof, a polysiloxane derivative having an aromatic amine in a side chain or a main chain, polyaniline or a derivative thereof, polythiophene or a derivative thereof Polymeric hole transport materials such as derivatives, polyarylamines or derivatives thereof, poly (p-phenylene vinylene) or derivatives thereof, or poly (2,5-thienylene vinylene) or derivatives thereof are preferred. In the case of a low-molecular hole transport material, it is preferably used by being dispersed in a polymer binder.

  The method for forming the hole transport layer is not particularly limited, but in the case of a low molecular hole transport material, film formation from a mixed solution containing a polymer binder and a hole transport material can be exemplified. Examples of molecular hole transport materials include film formation from a solution containing a hole transport material. The solvent used for film formation from a solution is not particularly limited as long as it can dissolve the hole transport material, and examples thereof include the solvents exemplified in the section of the hole injection layer. Examples of the film forming method from a solution include the same coating method as the above-described film forming method of the hole injection layer.

  The thickness of the hole transport layer is not particularly limited, but can be appropriately changed according to the intended design, and is preferably 1 nm or more and 1000 nm or less. If the thickness is less than the lower limit value, production tends to be difficult or the effect of hole transport is not sufficiently obtained. On the other hand, if the thickness exceeds the upper limit value, the driving voltage and the hole transport layer are increased. There is a tendency that the voltage applied to is increased. Therefore, the thickness of the hole transport layer is preferably 1 nm or more and 1000 nm or less, more preferably 2 nm or more and 500 nm or less, and further preferably 5 nm or more and 200 nm or less.

(Organic light emitting layer)
The organic light emitting layer has an organic substance (a low molecular compound and a high molecular compound) that mainly emits fluorescence or phosphorescence. Further, a dopant material may be further included. Examples of the material for forming the organic light emitting layer that can be used in the present embodiment include the following.

(Dye material)
Examples of the dye-based material include cyclopentamine derivatives, quinacudrine derivatives, coumarin derivatives, tetraphenylbutadiene derivative compounds, triphenylamine derivatives, oxadiazole derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, distyrylarylene derivatives, Examples include pyrrole derivatives, thiophene ring compounds, pyridine ring compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, oxadiazole dimers, and pyrazoline dimers.

(Metal complex materials)
Examples of the metal complex material include metal complexes that emit light from triplet excited states such as iridium complexes and platinum complexes, aluminum quinolinol complexes, benzoquinolinol beryllium complexes, benzoxazolyl zinc complexes, benzothiazole zinc complexes, azomethyls. Zinc complex, porphyrin zinc complex, europium complex, etc., which has Al, Zn, Be, etc. as the central metal or rare earth metal such as Tb, Eu, Dy, etc., and oxadiazole, thiadiazole, phenylpyridine, phenylbenzo as ligands Examples thereof include metal complexes having an imidazole or quinoline structure.

(Polymer material)
Polymeric materials include polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, and polymerized chromophores and metal complex light emitting materials. Etc.

Among the light emitting materials, examples of the material that emits blue light include distyrylarylene derivatives, oxadiazole derivatives, and polymers thereof, polyvinylcarbazole derivatives, polyparaphenylene derivatives, and polyfluorene derivatives.
Examples of materials that emit green light include quinacrine derivatives, coumarin derivatives, and polymers thereof, polyparaphenylene vinylene derivatives, polyfluorene derivatives, and the like.
Examples of materials that emit red light include coumarin derivatives, thiophene ring compounds, and polymers thereof, polyparaphenylene vinylene derivatives, polythiophene derivatives, and polyfluorene derivatives.

(Dopant material)
A dopant can be added in the organic light emitting layer for the purpose of improving the light emission efficiency and changing the light emission wavelength. Examples of such dopants include perylene derivatives, coumarin derivatives, rubrene derivatives, quinacdrine derivatives, squalium derivatives, porphyrin derivatives, styryl dyes, tetracene derivatives, pyrazolone derivatives, decacyclene, and phenoxazone. The thickness of the organic light emitting layer is usually about 2 to 200 nm.

  Examples of the method for forming the organic light emitting layer include film formation from a solution containing an organic light emitting material. The solvent used for film formation from a solution is not particularly limited as long as it dissolves an organic light-emitting material, and examples thereof include the solvents exemplified in the section of the hole injection layer. Examples of the film forming method from a solution include the same coating method as the above-described film forming method of the hole injection layer.

(Layer provided between the cathode and the light emitting layer)
Examples of the layer provided between the cathode and the organic light emitting layer as needed include an electron injection layer, an electron transport layer, and a hole blocking layer. When both the electron injection layer and the electron transport layer are provided between the cathode and the organic light emitting layer, a layer in contact with the cathode is referred to as an electron injection layer, and a layer excluding this electron injection layer is referred to as an electron transport layer.
The electron injection layer is a layer having a function of improving electron injection efficiency from the cathode. The electron transport layer is a layer having a function of improving electron injection from the cathode, the electron injection layer, or the electron transport layer closer to the cathode. The hole blocking layer is a layer having a function of blocking hole transport. In the case where the electron injection layer and / or the electron transport layer have a function of blocking hole transport, these layers may also serve as the hole blocking layer.

(Electron transport layer)
As the electron transport material constituting the electron transport layer, known materials can be used, such as oxadiazole derivatives, anthraquinodimethane or derivatives thereof, benzoquinone or derivatives thereof, naphthoquinone or derivatives thereof, anthraquinones or derivatives thereof, tetracyanoanthra Quinodimethane or derivatives thereof, fluorenone or derivatives thereof, diphenyldicyanoethylene or derivatives thereof, diphenoquinone derivatives, or metal complexes of 8-hydroxyquinoline or derivatives thereof, polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof, polyfluorene or derivatives thereof And so on.
Among these, as an electron transport material, an oxadiazole derivative, benzoquinone or a derivative thereof, anthraquinone or a derivative thereof, a metal complex of 8-hydroxyquinoline or a derivative thereof, polyquinoline or a derivative thereof, polyquinoxaline or a derivative thereof, polyfluorene or Derivatives thereof are preferred, and 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole, benzoquinone, anthraquinone, tris (8-quinolinol) aluminum, and polyquinoline are more preferred. .

  The method for forming the electron transport layer is not particularly limited, but in the case of a low molecular electron transport material, film formation from a mixed solution containing a polymer binder and an electron transport material can be exemplified. Examples of the transport material include film formation from a solution containing an electron transport material. The solvent used for film formation from a solution is not particularly limited as long as it dissolves an electron transport material, and examples thereof include the solvents exemplified in the section of the hole injection layer. Examples of the film forming method from a solution include the same coating method as the above-described film forming method of the hole injection layer.

  The thickness of the electron transport layer varies depending on the material used, and can be changed as appropriate according to the intended design. However, at least a thickness that does not cause pinholes is required. As a film thickness, it is preferable that it is 1 nm or more and 1000 nm or less, for example, More preferably, it is 2 nm or more and 500 nm or less, More preferably, it is 5 nm or more and 200 nm or less.

(Electron injection layer)
As a material constituting the electron injection layer, an optimal material is appropriately selected according to the type of the organic light emitting layer, and an alloy containing one or more of alkali metals, alkaline earth metals, alkali metals and alkaline earth metals, Alkali metal or alkaline earth metal oxides, halides, carbonates, mixtures of these substances, and the like can be given. Examples of alkali metals, alkali metal oxides, halides, and carbonates include lithium, sodium, potassium, rubidium, cesium, lithium oxide, lithium fluoride, sodium oxide, sodium fluoride, potassium oxide, potassium fluoride , Rubidium oxide, rubudium fluoride, cesium oxide, cesium fluoride, lithium carbonate, and the like. Examples of alkaline earth metals, alkaline earth metal oxides, halides, and carbonates include magnesium, calcium, barium, strontium, magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride, and barium oxide. , Barium fluoride, strontium oxide, strontium fluoride, magnesium carbonate and the like. The electron injection layer may be composed of a laminate in which two or more layers are laminated, and examples thereof include lithium fluoride / calcium. The electron injection layer is formed by various deposition methods, sputtering methods, various coating methods, and the like. The thickness of the electron injection layer is preferably 1 nm or more and 1000 nm or less.

(cathode)
As a material for the cathode, a material having a small work function and easy electron injection into the organic light emitting layer and / or a material having a high electric conductivity and / or a material having a high visible light reflectance are preferable. Specific examples of such a cathode material include metals, metal oxides, alloys, graphite or graphite intercalation compounds, and inorganic semiconductors such as zinc oxide.

  As the metal, an alkali metal, an alkaline earth metal, a transition metal, a Group III-b metal, or the like can be used. Specific examples of these metals include lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, tin, Aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbium, and the like can be given.

  Examples of the alloy include an alloy containing at least one of the above metals. Specifically, a magnesium-silver alloy, a magnesium-indium alloy, a magnesium-aluminum alloy, an indium-silver alloy, a lithium-aluminum alloy, Examples thereof include a lithium-magnesium alloy, a lithium-indium alloy, and a calcium-aluminum alloy.

  The cathode is a transparent electrode as necessary, but the materials thereof are conductive oxides such as indium oxide, zinc oxide, tin oxide, ITO, IZO, conductive materials such as polyaniline or derivatives thereof, polythiophene or derivatives thereof, and the like. Organic materials can be mentioned.

  Note that the cathode may have a laminated structure of two or more layers. Moreover, an electron injection layer may be used as a cathode.

  The film thickness of the cathode can be appropriately selected in consideration of electric conductivity and durability, but is, for example, 10 nm to 10,000 nm, preferably 20 nm to 1000 nm, and more preferably 50 nm to 500 nm. It is as follows.

  The organic EL element in this embodiment can be used for a self-luminous display, a liquid crystal backlight, illumination, and the like. Since the organic EL element of this embodiment can emit light uniformly and without unevenness, it is preferably used for illumination purposes.

<Effect>
Next, the effects of using the above-described configuration of the transparent electrode and the manufacturing method thereof will be described with reference to FIGS. 1 and 2 using Examples and Comparative Examples in which the effects have been confirmed.

  FIG. 1 is a schematic plan view showing a state in which up to the fine wire structure portion 13 is formed on the transparent substrate 12. In FIG. 1, although the example which has arrange | positioned the thin wire | line structure part 13 in the grid type | mold on the transparent base material 1211 is shown, it does not restrict | limit in particular. FIG. 2 is a process diagram showing a specific example of a main part in which the transparent base material 10 in which the thin wire structure portion 13 according to this embodiment is manufactured and the transparent conductive layer 20 is formed thereon.

First, as shown in FIG. 2A, the fine line structure 13 is formed on the transparent substrate 12.
1 is formed over the entire surface of the transparent electrode forming region 11 in FIG. 1 and the etching conditions are adjusted by an etching method using a photoresist on the surface of the transparent substrate 12. On the other hand, the fine wire structure 13 having an inversely tapered structure is formed.

  Next, as shown in FIG. 2B, a solution containing the material of the transparent conductive layer 20 on the transparent substrate 12 is applied to the entire surface of the transparent substrate 10 including the thin wire structure portion 13. FIG. 2B shows a state where a solution containing the material of the transparent conductive layer 20 is applied. The solution containing the material of the transparent conductive layer 20 enters the concave portion formed by the transparent base material 12 and the side surface of the fine wire structure portion 13, and the transparent conductive material located in the region 14 excluding the formation region of the fine wire structure portion 13 is flat. Turn into.

Thereafter, a heat treatment is performed to dry the solution containing the material of the transparent conductive layer 20 and vaporize the solvent, whereby the transparent conductive layer 20 is formed on the entire surface of the transparent substrate 10 including the fine wire structure portion 13, and the transparent electrode Is produced.
At this time, the thickness of the transparent conductive layer 20 is present at a position lower than the height of the thin wire structure portion 13.

Next, an organic EL element was produced using this transparent electrode. In this organic EL element, the entire light emitting layer formed on the region 14 excluding the region where the fine line structure portion 13 was formed emitted light, and high luminance was obtained.
Thus, in this embodiment, since the uniformity of the transparent conductive layer 20 is improved as compared with a comparative example described later (the state shown in FIG. 3B), it is possible to produce a transparent electrode with high surface smoothness. Yes (state shown in FIG. 2B).

[Comparative example]
Next, the structure of the transparent electrode which concerns on a comparative example, the manufacturing method of a transparent electrode, and the structure of an organic EL element are demonstrated.

<Method for producing transparent electrode>
The structure of the transparent electrode according to the comparative example, the method of manufacturing the transparent electrode, and the structure of the organic EL element are the same as the structure of the transparent electrode, the method of manufacturing the transparent electrode, and the structure of the organic EL element according to the above-described embodiment. It is. However, in the manufacturing method, the cross-sectional shape of the thin wire structure portion 13 is different. Therefore, with reference to FIG. 1 and FIG. 3, the manufacturing method of a transparent electrode is demonstrated and others are abbreviate | omitted.

First, as shown in FIG. 3A, the fine wire structure 13 is formed on the transparent substrate 12.
In the reverse taper structure with respect to the surface of the transparent substrate 12 by depositing a metal and / or an alloy thereof to be the fine wire structure portion 13 over the entire surface of the transparent electrode forming region 11 of FIG. 1 and etching using a photoresist. A thin wire structure portion 13 having a rectangular cross section is formed.
<Effect>

  Next, as shown in FIG. 3B, a solution containing the material of the transparent conductive layer 20 on the transparent substrate 12 is applied to the entire surface of the transparent substrate 10 including the fine wire structure portion 13. The solution containing the material of the transparent conductive layer 20 wets the side surface of the fine line structure portion 13, and the central portion of the region 14 excluding the formation region of the fine wire structure portion 13 has a thin film thickness, and the vicinity of the fine wire structure portion 13 has a thick film thickness. Be filmed.

Thereafter, a heat treatment is performed, the solution containing the material of the transparent conductive layer 20 is dried, and the solvent is vaporized, whereby the transparent conductive layer 20 is formed on one surface of the transparent substrate 10 including the fine wire structure portion 13 and is transparent. An electrode is produced. The formed transparent conductive layer 20 has a thin film thickness in the central portion of the region 14 excluding the formation region of the fine line structure portion 13, and a thick film thickness in the vicinity of the fine wire structure portion 13. .
At this time, the thickness of the transparent conductive layer 20 is present at a position lower than the height of the thin wire structure portion 13.

  Next, when an organic EL element is manufactured using this transparent electrode, among the light emitting layers formed on the region 14 excluding the region where the fine line structure portion 13 is formed, the central portion emits light, but the vicinity of the fine line structure portion 13 does not emit light. The luminance was lower than that of the first embodiment.

DESCRIPTION OF SYMBOLS 10 ... Transparent base material 11 with which fine wire structure part was arrange | positioned ... Transparent electrode formation area 12 ... Transparent base material 13 ... Fine wire structure part 14 ... Area | region 20 except the formation area of a thin wire structure part ... Transparent conductive layer

Claims (6)

In a transparent electrode having a transparent base material, a fine wire structure portion arranged on the transparent base material and formed of a conductive material, and a transparent conductive layer arranged so as to cover the fine wire structure portion,
The thin wire structure has a reverse tapered shape in cross section.   The transparent electrode according to claim 1, wherein the transparent conductive layer is formed using a wet coating method.   3. The transparent electrode according to claim 1, wherein the transparent conductive layer is present at a position lower than a height of the thin line structure portion in a region formed on the transparent substrate.   The transparent electrode according to any one of claims 1 to 3, wherein the transparent conductive layer includes polythiophene, a polythiophene derivative, or a mixture of polythiophene and a polythiophene derivative.   The transparent electrode according to any one of claims 1 to 3, wherein the transparent conductive layer includes polyaniline, a derivative of polyaniline, or a mixture of polyaniline and a derivative of polyaniline. An organic electroluminescence device comprising the transparent electrode according to claim 1.

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