JP2018045816A - Transparent electrode and organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent electrode capable of solving the problem on appearance inhibited by a metal layer by securing the required resistance value without using an electroconductive thin wire, and also to provide an organic EL element equipped with the transparent electrode.SOLUTION: On a transparent base material 2, a plurality of metal-covered spheres 3 formed by covering the surface of a spherical shaped core 6 with a metal layer 7 are arranged spaced apart from each other. The diameter of the metal-covered sphere 3 is equal or more than 0.01 μm. Furthermore, a transparent conductive layer 5 is formed on the transparent base material 2 so as to cover the metal-coated sphere 3, that is, be in a buried state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a transparent electrode and an organic electroluminescence light emitting device provided with the electrode.

In recent years, as a next-generation display device following a liquid crystal display (LCD), a light-emitting element type display panel in which self-light-emitting elements such as organic electroluminescence elements (hereinafter also abbreviated as “organic EL elements”) are two-dimensionally arranged is provided. Research and development of light emitting devices are underway.
The organic EL element is formed between an anode, a cathode, and a pair of these electrodes. The organic EL element includes an organic EL layer (light emitting functional layer) having, for example, an organic light emitting layer, a hole injection layer, and the like. In the organic EL element, light is emitted by energy generated by recombination of holes and electrons in the organic light emitting layer.

  Generally, the transparent electrode on the light extraction side of such an organic EL element has a transparent conductive layer using tin-doped indium oxide (ITO) or zinc-doped indium oxide (IZO). It is formed. These transparent conductive layers have the advantage of high light transmission and have the advantage of ensuring high brightness. However, in order to obtain a low resistance, this transparent electrode must form a thick and uniform film. For this reason, a decrease in light transmittance, an increase in price, a labor for high-temperature treatment in the formation process, and the like occur, and there is a limit to reducing the resistance on the film in particular (see, for example, Patent Document 1). .

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

  However, an organic EL element that employs a transparent electrode that combines a metal layer having a fine line structure and a transparent electrode layer needs to be patterned by a method such as photolithography or printing in order to form a fine line. For this reason, there is a risk that the number of processes increases, leading to an increase in cost and a decrease in yield. Depending on the size and shape of the metal layer, the fine metal wire is easily visible, which may hinder the appearance.

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

  The present invention has been made in view of the above-described circumstances, and ensures a necessary resistance value without using a conductive thin wire, and a transparent electrode capable of solving the problem in appearance that is obstructed by the metal layer, It aims at providing the organic electroluminescent light emitting element provided with the transparent electrode.

  In order to solve the problems, a transparent electrode of one embodiment of the present invention includes a transparent base material, a transparent conductive layer formed on the transparent base material, and a plurality of surfaces embedded in the transparent conductive layer and made of metal. The plurality of particles are arranged at intervals along the surface of the transparent substrate, and when the volume of the particles is converted to a sphere, the diameter of each particle is 0.01 μm or more. The transparent conductive layer is a conductive polymer including a π-conjugated conductive polymer and a polyanion.

  In one embodiment of the present invention, a plurality of particles each having a metal surface are disposed instead of a metal layer such as a thin metal wire. As a result, it is possible to reduce the process of patterning the fine metal wires, and it is possible to improve the appearance by selecting the particle size and the arrangement interval within a range in consideration of the human visual limit.

It is a conceptual diagram which shows the structure of the transparent electrode which concerns on embodiment based on this invention, (a) is a top view, (b) is sectional drawing of the A-A 'line in Fig.1 (a).

Embodiments of the present invention will be described below with reference to the drawings.
Here, the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Further, the embodiment shown here illustrates a concept for embodying the technical idea of the present invention, and the technical idea of the present invention is that the material, shape, structure, etc. of the constituent members are as follows. It is not specific. The technical idea of the present invention can be variously modified within the technical scope assumed by the claims described in the claims.

<Configuration of transparent electrode 1>
As shown in FIG. 1, the transparent electrode 1 of the present embodiment is disposed along the surface of the transparent substrate 2, the transparent conductive layer 5 formed on the transparent substrate 2, and the transparent substrate 2. And a plurality of metal-coated spheres 3 embedded in the transparent conductive layer 5 in a state.
From the viewpoint of improving luminance when the transparent electrode 1 is used in an organic EL element, the surface resistivity of the conductive surface of the transparent electrode 1 is preferably 0.01Ω / □ or more and 100Ω / □ or less, Preferably, it is 0.1Ω / □ or more and 10Ω / □ or less.

  The transparent electrode 1 can be used for transparent electrodes such as LCDs, electroluminescent elements, plasma displays, electrochromic displays, solar cells, touch panels, electronic papers, electromagnetic wave shielding materials, etc., but has excellent conductivity and transparency. Since smoothness is also high, it is preferable to use for an organic EL element.

(Transparent substrate 2)
As the transparent substrate 2, a plastic film, a plastic plate, glass or the like can be used.
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 2 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 2 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. Moreover, in order to improve the application | coating of a transparent conductive layer to the transparent base material 2, and the adhesiveness with respect to the surface of the transparent base material 2, you may surface-treat by corona, plasma, and UV / ozone. 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. When providing a gas barrier layer, the gas barrier layer is preferably provided on at least one surface of the transparent substrate, and is preferably provided on both surfaces.
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. Moreover, although it does not specifically limit regarding the thickness of a gas barrier layer, Typically, it is preferable to exist in the range of 5 nm-500 nm per layer, More preferably, it is 10 nm-200 nm per layer. The gas barrier layer is provided on at least one surface of the transparent substrate, and is preferably provided on both surfaces.

(Metal-coated sphere 3)
The metal-coated sphere 3 constitutes particles whose surface is made of metal.
The metal-coated sphere 3 includes a sphere-shaped core 6 and a metal layer 7 coated on the surface of the core 6.
The core 6 is made of at least one of an organic material and an inorganic material.

The reason why the organic material or the inorganic material is used for the core 6 is to reduce the weight, reduce the amount of metal used, and reduce the cost.
The metal layer 7 preferably has a low electric resistance. For example, a material having an electric conductivity of 10 ⁷ (10 7) S / cm or more is used. Specific examples of such a conductive material include metals such as aluminum, silver, chromium, gold, copper, tantalum, and molybdenum and / or alloys thereof. That is, in this specification, a metal includes not only a metal simple substance but also a metal alloy.

The diameter a of the metal-coated sphere 3 is preferably 0.01 μm or more, and more preferably 0.05 μm or more. The maximum diameter a is preferably 1 μm or less. The reason why the diameter a is defined in such a range is to ensure transparency while designing the transparent conductive layer 5 to have a predetermined conductivity.
The metal-coated spheres 3 are arranged along the surface of the transparent substrate 2 at intervals.

It is preferable that the arrangement | positioning space | interval b of the metal-coated sphere 3 opens the space | interval more than the diameter a. More preferably, the interval is a diameter a × 2 (= 2a) or more. Moreover, it is preferable that the upper limit of the arrangement | positioning space | interval b of the metal-coated sphere 3 is 10 mm or less.
By disposing a plurality of metal-coated spheres 3, the light transmittance of the transparent electrode 1 is reduced, but it is important to make the reduction as small as possible. The light transmittance is preferably 50% or more, more preferably 80% or more. For this reason, the arrangement interval b of the metal-coated spheres 3 is designed so that the light transmittance is 50% or more, preferably 80% or more in consideration of the conductivity set in the transparent conductive layer 5.
The arrangement pattern of the plurality of metal-coated spheres 3 is preferably random. By making it random arrangement, it becomes more difficult to visually recognize the metal-coated sphere 3.

(Configuration of transparent conductive layer 5)
The transparent conductive layer 5 is formed on the transparent substrate 2 with a plurality of metal-coated spheres 3 embedded therein. The transparent conductive layer 5 is made of a conductive polymer containing a π-conjugated conductive polymer and a polyanion.
Next, the detailed configuration of the transparent conductive layer 5 will be described.

The transparent conductive layer 5 is formed on the transparent substrate 2 by a coating method in which a solution for the transparent conductive layer is applied, for example.
The solution for forming the transparent conductive layer 5 includes a material that becomes the transparent conductive layer 5 and a solvent.
The material for forming the transparent conductive layer 5 preferably contains a polymer compound (π-conjugated conductive polymer) that exhibits conductivity. The polymer compound may contain a dopant. The conductivity of the polymer compound is 10 ^{−5 to} 10 ⁵ S / cm, preferably 10 ^{−3 to} 10 ⁵ S / cm in terms of conductivity. Moreover, it is preferable that the transparent conductive layer 5 consists of a high molecular compound which shows electroconductivity substantially.

As a material constituting such a transparent conductive layer 5, for example, polyaniline and derivatives thereof, polythiophene and derivatives thereof, and the like can be used. A known dopant can be used as the dopant, 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.

Further, the transparent conductive layer 5 is preferably configured to include at least one derivative of polythiophene and polythiophene, and is preferably substantially composed of at least one derivative of polythiophene and polythiophene. Note that at least one of the polythiophene and the polythiophene may contain a dopant.
A polythiophene, a polythiophene derivative, or a mixture of a polythiophene and a polythiophene derivative is easily dissolved or dispersed in an aqueous solvent such as water and alcohol, and thus is preferably used as a solute of a coating solution used in a coating method. 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 efficiently inject holes into the organic light emitting layer. Therefore, it can be suitably used as an anode material. Moreover, these have high transparency and are suitably used as an electrode on the light emission extraction side of the organic EL element.

Further, the transparent conductive layer 5 is preferably configured to include at least one derivative of polyaniline and polyaniline, and is preferably substantially composed of at least one derivative of polyaniline and polyaniline. Note that at least one derivative of polyaniline and polyaniline may contain a dopant.
Since at least one of polyaniline and polyaniline is excellent in conductivity and stability, it is preferably used as an electrode 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 film thickness may be determined according to the desired conductivity, but is preferably selected so that the transparent electrode 1 can obtain high smoothness. The reason for this is that when the transparent electrode 1 has an uneven surface shape, when combined with an organic EL element, there is a risk of uneven light emission and short-circuit defects with the cathode layer due to the influence of the uneven surface shape. Because. Therefore, as shown in FIG. 1B, the transparent conductive layer 5 is preferably thicker than or equal to the diameter of the metal-coated sphere 3.

<The manufacturing method of the transparent electrode 1>
Hereinafter, the manufacturing method of the transparent electrode 1 is demonstrated.
The transparent electrode 1 is manufactured by applying a mixed solution that forms a transparent conductive layer 5 in which the metal-coated sphere 3 is mixed on the transparent substrate 2. That is, it includes a step of mixing the metal-coated sphere 3 with a material for forming the transparent conductive layer 5 and a step of applying a mixed solution for the mixed transparent electrode 1.

In the method for manufacturing the transparent electrode 1 according to the present embodiment, first, the materials for forming the metal-coated sphere 3 and the transparent conductive layer 5 described above are mixed and stirred.
The method for mixing and stirring the material for forming the metal-coated sphere 3 and the transparent conductive layer 5 is not particularly limited, and is uniformly dispersed by, for example, a propeller stirrer, a rotary stirrer, a vibration stirrer, a roll mill, or the like. As a result, a mixed solution is formed. At this time, it is preferable that bubbles do not enter the mixed solution.

  As a method for forming a mixed 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 Examples of the coating method include a printing method, a flexographic printing method, an offset printing method, a slit coating method, an inkjet printing method, a nozzle printing method, and a slit coating method. In particular, in order to partially form the transparent conductive layer forming region 4 on the transparent substrate 2, a coating film forming method capable of patterning is preferable and can be appropriately selected. Coating methods such as a coating method, a slit coating method, a micro gravure coating method, and a gravure coating method are suitable.

Next, the transparent base material 2 on which the mixed solution is applied to the entire surface 4 of the transparent conductive layer forming region is heat-treated in a drying treatment chamber under a temperature condition of, for example, 100 ° C. As a result, the solvent contained in the mixed solution is vaporized, and the mixed solution in which the metal-coated spheres 3 are mixed is fixed to the transparent substrate 2 to form the transparent conductive layer 5.
Here, the transparent conductive layer is formed by applying a mixed solution for the transparent conductive layer in which the metal-coated sphere 3 is mixed, but since the metal-coated sphere 3 is stirred so as to be uniformly dispersed, A plurality of metal-coated spheres 3 are arranged along the surface of the transparent substrate 2 in a state where the metal-coated spheres 3 do not contact each other. Note that some metal-coated spheres 3 may be in contact with each other.
Further, by adjusting the number of the metal-coated spheres 3 mixed in the solution for the transparent conductive layer, the interval between the metal-coated spheres 3 can be set to be equal to or larger than the diameter of the metal-coated spheres 3, for example. In addition, it is preferable that the minimum value of the space | interval b of the metal coating sphere 3 is more than the diameter a, and the average space | interval b is more than twice the diameter a.

<Configuration of organic EL element>
The organic EL element in the present embodiment has a transparent electrode 1 based on the present invention. The organic EL element in the present embodiment uses the transparent electrode 1 of the present embodiment as an anode, and the organic light emitting layer, the cathode, and the sealing structure are arbitrarily selected from materials and configurations generally used in the organic EL element. Things can be used. The following layer structure can be illustrated as a layer structure of an organic EL element.
(A) Anode / organic light emitting layer / cathode,
(B) Anode / hole transport layer / organic light emitting layer / electron transport layer / cathode,
(C) Anode / hole injection layer / hole transport layer / organic light emitting layer / electron transport layer / cathode,
(D) Anode / hole injection layer / organic light emitting layer / electron transport layer / electron injection layer / cathode,
(E) Anode / hole injection layer / organic light emitting layer / electron injection layer / cathode,
Here, the symbol “/” shown in the above (A) to (E) indicates that the layers sandwiching the symbol “/” are laminated adjacently. The same applies to the following description.

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.
(F) 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 emission layer / electron transport layer / charge injection layer / Cathode Further, as an organic EL device having three or more organic light emitting layers, specifically, (charge generation layer / charge injection layer / hole transport layer / organic light emission layer / electron transport layer / charge injection layer) As one repeating unit, a layer structure including two or more repeating units shown below can be exemplified.
(G) Anode / charge injection layer / hole transport layer / organic light emitting layer / electron transport layer / charge injection layer / (the repeating unit) / (the repeating unit) /... / Cathode Each layer other than the cathode and the organic 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, a layer provided between the anode and the organic light emitting layer, a hole injection layer, a hole transport layer, an organic light emitting layer, a layer provided between the cathode and the light emitting layer, an electron transport layer, an electron injection layer, and a cathode Each layer 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 makes it possible, for example, to manufacture an element that allows only electron current to flow and to confirm the blocking effect 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 about 5 to 300 nm. 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 about 1 to 1000 nm. 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 to 1000 nm, more preferably 2 to 500 nm, and still more preferably 5 to 200 nm.

(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 a dye material, a metal complex material, and a polymer 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.

  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.

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 above light emitting materials (materials forming the organic light emitting layer), materials emitting blue light include distyrylarylene derivatives, oxadiazole derivatives, and polymers thereof, polyvinylcarbazole derivatives, polyparaphenylene derivatives, poly Fluorene derivatives and the like can be mentioned.

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.

  The dopant material can be added to 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 a 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, and at least a thickness that does not cause pinholes is required. As a film thickness, it is preferable that it is about 1-1000 nm, for example, More preferably, it is 2-500 nm, More preferably, it is 5-200 nm.

(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.
In addition, the electron injection layer may be comprised with the laminated body which laminated | stacked two or more layers, for example, lithium fluoride / calcium etc. can be mentioned. 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 about 1 to 1000 nm.

(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 IIIb 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 thickness of the cathode can be appropriately selected in consideration of electric conductivity and durability, but is, for example, 10 to 10,000 nm, preferably 20 to 1000 nm, and more preferably 50 to 500 nm. .
The organic EL element of this embodiment can be used for a self-luminous display, a liquid crystal backlight, illumination, and the like.
Here, in the above description, the case where the surface is composed of metal-coated spheres 3 as particles made of metal has been described. Moreover, the particle | grains which the surface consists of a metal have preferable a spherical shape of a true sphere.

<Effect>
Next, the configuration of the transparent electrode as described above and the operation and effect when the manufacturing method thereof is used will be described with reference to FIG.
As shown in FIG. 1, the transparent electrode 1 of this embodiment is arranged such that the interval b between the metal-coated spheres 3 is 10 μm or more, and the size (diameter) of the metal-coated spheres 3 is 0.01 μm or more. Is forming.

The core 6 of the metal-coated sphere 3 is formed in a sphere shape from an organic, inorganic, or organic / inorganic hybrid material, and the entire surface thereof is covered with a metal layer 7.
As shown in FIG. 1, a metal formed by photolithography or printing can be obtained by printing a transparent conductive layer 5 in which a metal-coated sphere 3 is mixed on a transparent substrate 2 with a thickness equal to or greater than the diameter of the metal-coated sphere 3. This has the effect of reducing the number of auxiliary wiring processes, increases the productivity through high throughput, and improves the yield.

DESCRIPTION OF SYMBOLS 1 ... Transparent electrode 2 ... Transparent base material 3 ... Metal-coated sphere (particle)
4 ... Transparent conductive layer forming region 5 ... Transparent conductive layer 6 ... Spherical core 7 ... Metal layer

Claims (8)

Comprising a transparent substrate, a transparent conductive layer formed on the transparent substrate, and a plurality of particles embedded in the transparent conductive layer and having a surface made of metal,
The plurality of particles are arranged at intervals along the surface of the transparent substrate, and when the volume of the particles is converted to a sphere, the diameter of each particle is 0.01 μm or more and 1.00 μm or less,
The transparent conductive layer, wherein the transparent conductive layer is a conductive polymer including a π-conjugated conductive polymer and a polyanion.   The transparent electrode according to claim 1, wherein the inside of the particle is composed of at least one of an organic material and an inorganic material.   3. The transparent electrode according to claim 1, wherein an interval between the adjacent particles is equal to or larger than a diameter of the particles.   The thickness of the said transparent conductive layer is more than the diameter of the said particle | grain, The transparent electrode described in any one of Claims 1-3 characterized by the above-mentioned.   The said particle | grain is arrange | positioned at random along the surface of the said transparent base material, The transparent electrode of any one of Claims 1-4 characterized by the above-mentioned.   The conductivity of the metal which comprises the surface of the said particle | grain is below the conductivity of the said transparent conductive layer, The transparent electrode of any one of Claims 1-5 characterized by the above-mentioned.   The transparent electrode according to any one of claims 1 to 6, wherein the transparent electrode has a light transmittance of 50% or more.   An organic electroluminescent element provided with the transparent electrode of any one of Claims 1-7.

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