JP2010118165A - Transparent electrode, its manufacturing method, and organic electroluminescent element using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent electrode excellent in surface smoothness, conductivity, and transparency, ant yet with high productivity as well as its manufacturing method. <P>SOLUTION: The transparent electrode with a conductive layer containing metal nanowire on a transparent support body is provided with a polymer layer made of at least either water-soluble polymer or aqueous polymer emulsion at an under-layer adjacent to the conductive layer, with at least a part of the metal nanowire embedded in the polymer layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a transparent electrode excellent in conductivity and transparency, a method for producing the same, and an organic electroluminescence device using the same.

  In recent years, with increasing demand for thin TVs, various types of display technologies such as liquid crystal, plasma, organic electroluminescence (hereinafter, organic EL), field emission, and the like have been developed. In any of these displays having different display methods, the transparent electrode is an essential constituent technology. In addition to televisions, transparent electrodes are an indispensable technical element in touch panels, mobile phones, electronic paper, various solar cells, and various electroluminescence light control elements.

Conventionally, as transparent electrodes, various metal thin films such as Au, Ag, Pt, Cu, indium oxide doped with tin or zinc (ITO, IZO), zinc oxide doped with aluminum or gallium (AZO, GZO), fluorine, Metal oxide thin films such as tin oxide doped with antimony (FTO, ATO), conductive nitride thin films such as TiN, ZrN, and HfN, and conductive boride thin films such as LaB ₆ are known and combinations thereof. Various electrodes such as Bi ₂ O ₃ / Au / Bi ₂ O ₃ and TiO ₂ / Ag / TiO ₂ are also known. In addition to inorganic materials, transparent electrodes using CNTs (carbon nanotubes) and conductive polymers have also been proposed (see, for example, Non-Patent Document 1).

  However, since the metal thin film, nitride thin film, boron thin film and conductive polymer thin film described above cannot have both light transmission properties and conductive properties, special technical fields such as electromagnetic shielding and the like are relatively high. It was used only in the touch panel field where resistance values are allowed.

  On the other hand, metal oxide thin films are becoming mainstream of transparent electrodes because they can achieve both light transmittance and conductivity and are excellent in durability. In particular, ITO is widely used as a transparent electrode for various optoelectronics because it has a good balance between light transmittance and conductivity and it is easy to form an electrode fine pattern by wet etching using an acid solution. However, the conductive oxide typified by the above ITO or the like forms a transparent conductive film on the substrate surface by a vacuum process such as sputtering or a liquid phase method such as sol-gel. In order to form a transparent conductive film by a vacuum process such as sputtering, expensive equipment is required.

  In order to solve such problems, a method of forming a transparent conductive film by applying a conductive oxide or a composition containing a conductive polymer has been proposed (for example, Patent Document 1). 2).

  However, it is difficult to obtain sufficient electrical conductivity by these methods, and it is difficult to achieve both light transmittance and electrical conductivity, particularly in applications such as organic EL elements and solar cells. Moreover, although the formation method of the conductive layer by various printing methods is described, the method of direct patterning is not described in detail.

  Examples of other transparent electrodes include transparent electrodes in which a mesh structure is formed by a metal pattern typified by an electromagnetic wave shielding film of a plasma display (see, for example, Patent Document 3), or a fine mesh using metal nanowires. A transparent electrode is disclosed (for example, see Patent Document 4). In particular, in a metal mesh using silver, both good conductivity and transparency can be achieved due to the inherent high conductivity of silver. However, these transparent electrodes have a defect that the electrode surface is rough as compared with the above-mentioned electrodes such as ITO. In particular, in the case of an organic EL element, since an ultra-thin film of an organic compound is formed on the electrode, the transparent electrode is required to have excellent surface smoothness. With such an electrode having low surface smoothness, the function of the element is deteriorated. Invite.

In order to improve surface smoothness, a method has been proposed in which a conductive layer is formed on a highly smooth support using metal nanowires and transferred to another support (see, for example, Patent Document 5). It is difficult to adjust the balance between the adhesive used for transfer and the adhesion between the support and the conductive layer and the peelability, and complete transfer is difficult. Furthermore, there are many steps of applying and curing the adhesive layer, laminating and peeling the supports, peeling, and processes, and there is a problem of cost increase. Further, a method for directly forming the conductive layer pattern by a printing method is not described in detail.
JP 2008-95015 A Japanese Patent Laid-Open No. 2008-4501 JP 2004-221564 A US Patent Application Publication No. 2007 / 0074316A1 JP 2006-236626 A "Technology of transparent conductive film", page 80 (Ohm Publishing Co.)

  An object of the present invention is to provide a transparent electrode that is excellent in surface smoothness, conductivity, and transparency and has high productivity, and a method for manufacturing the same.

  In particular, an object of the present invention is to provide a transparent electrode in which at least a part of metal nanowires contained in a conductive layer is buried in the polymer layer, and a method for producing the transparent electrode.

The above object of the present invention can be achieved by the following configuration.
1. A transparent electrode having a conductive layer containing metal nanowires on a transparent support, the transparent electrode being a polymer layer comprising at least one of a water-soluble polymer or an aqueous polymer emulsion in a lower layer adjacent to the conductive layer A transparent electrode characterized in that at least a part of the metal nanowire is embedded in the polymer layer.
2. In the method for producing a transparent electrode in which a polymer layer composed of at least one of a water-soluble polymer or an aqueous polymer emulsion and a conductive layer composed of metal nanowires are sequentially formed on a transparent support, A method for producing a transparent electrode, comprising: applying a conductive layer on a polymer layer in a state where a water content of the polymer layer is 100% or more after applying the molecular layer.
3. In the method for producing a transparent electrode, in which a polymer layer composed of at least one of a water-soluble polymer or an aqueous polymer emulsion and a conductive layer composed of metal nanowires are sequentially formed on a transparent support, the polymer layer and the conductive layer A method for producing a transparent electrode, characterized in that the layers are applied simultaneously in multiple layers.
4.2. The method for producing a transparent electrode according to 4.2, wherein patterning is performed when the conductive layer is applied on the polymer layer.
5. The method for producing a transparent electrode according to any one of claims 2 to 4, wherein after applying and drying the polymer layer and the conductive layer, water is applied to the conductive layer surface and dried as a post-treatment. A method for producing a transparent electrode.
The organic electroluminescent element characterized by including the transparent electrode manufactured by the transparent electrode of 6.1, or the manufacturing method of the transparent electrode of any one of 2-5.

  According to the present invention, a transparent electrode having excellent conductivity and transparency and high smoothness can be provided easily and inexpensively, and an organic electroluminescence element using the transparent electrode (hereinafter also referred to as organic EL). Can be provided easily.

  Hereinafter, the present invention and its components will be described in detail.

<Support>
In the present invention, a plastic film, a plastic plate, glass or the like can be used as the transparent support.

  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, and polychlorinated chloride. Use vinyl resins such as vinylidene, polyether ether ketone (PEEK), polysulfone (PSF), polyether sulfone (PES), polycarbonate (PC), polyamide, polyimide, acrylic resin, triacetyl cellulose (TAC), etc. Can do.

  In the method for producing a transparent electrode according to the present invention, the support is preferably excellent in surface smoothness. The smoothness of the surface is preferably an arithmetic average roughness Ra of 5 nm or less and a maximum height Ry of 50 nm or less, more preferably Ra of 2 nm or less and Ry of 30 nm or less, and still more preferably Ra of 1 nm or less. And Ry is 20 nm or less. The surface of the support 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. You can also. In order to improve the coating and adhesion of the polymer layer, a surface treatment using corona or plasma, or an easy adhesion layer may be formed. Here, the smoothness of the surface can be determined according to the surface roughness standard (JIS B 0601-2001) from measurement by 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. In addition, the barrier layer may have a multilayer structure as necessary. 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.

  The thickness of each inorganic layer constituting 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 support, and more preferably on both surfaces.

<Conductive layer>
The conductive layer in the present invention is composed of metal nanowires and preferably contains at least one of a conductive polymer and a metal oxide. Moreover, it is preferable that the conductive layer is directly patterned by an ink jet printing method, a spray printing method, or the like. Note that printing may be performed a plurality of times depending on the concentration of the coating liquid and the target conductivity.

  In the present invention, the conductive polymer and the metal oxide may be used by mixing in a dispersion containing metal nanowires, or may be applied to the upper layer after applying the metal nanowires. In addition to the conductivity due to the contact between the metal nanowires, the conductivity of the metal nanowire and the gap between the metal nanowires can be made uniform by introducing a conductive polymer and a metal oxide between the metal nanowires.

  The dispersion containing the metal nanowire, the conductive polymer, and the metal oxide of the present invention may contain a transparent binder material or additive as long as both conductivity and transparency can be achieved. The transparent binder material can be selected from a wide range of natural polymer resins or synthetic polymer resins. For example, transparent thermoplastic resin (eg, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polymethyl methacrylate, nitrocellulose, chlorinated polyethylene, chlorinated polypropylene, vinylidene fluoride), heat, light, electron beam A transparent curable resin that is cured by radiation (for example, melamine acrylate, urethane acrylate, epoxy resin, polyimide resin, silicon resin such as acrylic-modified silicate) can be used. Examples of the additive include plasticizers, stabilizers such as antioxidants and sulfurization inhibitors, surfactants, dissolution accelerators, polymerization inhibitors, and colorants such as dyes and pigments. Furthermore, from the viewpoint of improving workability such as coating properties, solvents (for example, water, organic solvents such as alcohols, glycols, cellosolves, ketones, esters, ethers, amides, hydrocarbons, etc.) are used. May be included.

<Polymer layer>
The polymer layer in the present invention is formed of at least one of a water-soluble polymer and an aqueous polymer emulsion, and is located in an adjacent lower layer of the conductive layer, and at least a part of the metal nanowire is buried. The polymer layer may contain a conductive polymer and a metal oxide. Further, the polymer layer may have a multilayer structure, and the concentration of the conductive polymer and the metal oxide may be gradually decreased from the layer adjacent to the conductive layer toward the support.

  The structure in which a part of the metal nanowire is buried in the polymer layer is a state in which the polymer layer made of water-soluble polymer or aqueous polymer emulsion is undried, and a conductive layer made of metal nanowire is provided on the polymer layer. Thus, the smoothness of the conductive layer can be improved. After the conductive layer is applied, it is considered that the metal nanowires constituting the conductive layer settle to the polymer layer and the polymer layer contracts as the drying proceeds, whereby the conductive layer is smoothed. The dry film thickness of the polymer layer is preferably 10 to 300%, more preferably 50 to 200% of the dry film thickness of the conductive layer. If it is less than 10%, the smoothing effect is small, and if it exceeds 300%, the conductive layer is excessively buried in the polymer layer and the surface conductivity is lowered.

  For such a smoothing effect, it is preferable to coat the conductive layer when the water content of the polymer layer is 100% or more, and more preferably 150% or more. If it is 100% or less, the amount of metal nanowires settled on the polymer layer and the amount of drying shrinkage of the polymer layer are small, and the smoothing effect is small. In addition, the conductive layer may be applied simultaneously with the application of the polymer layer using a multilayer coater, which is preferable from the viewpoint of forming an interface between the polymer layer and the conductive layer and productivity.

<Patterning>
In the present invention, the conductive layer can be patterned by a photolithography method or the like after coating the conductive layer on the polymer layer and drying or simultaneously coating and drying the conductive layer and the polymer layer. Further, when a conductive layer is applied to the polymer layer, direct patterning can be performed by an inkjet method or the like.

<Post-processing>
In the present invention, as a post-treatment, the polymer layer can be re-swelled and re-shrinked by applying water to the conductive layer or immersing it in water and drying, thereby improving the smoothness. In addition, the exposure of the surface metal nanowires is increased, and the surface resistance can be improved. For the application of water, a bar coater, a blade coater, a spray coater or the like can be used, and a solvent such as a surfactant or alcohol may be contained in order to promote water penetration into the coating film.

<Metal nanowires>
In general, the metal nanowire refers to a linear structure having a metal element as a main component. In particular, the metal nanowire in the present invention means a structure in which a large number of linear structures having a diameter from the atomic scale to the nm size are formed in a mesh shape.

  In order to form a long conductive path with one metal nanowire, the metal nanowire of the present invention preferably has an average length of 3 μm or more, more preferably 3 to 500 μm, particularly 3 to 300 μm. Is preferred. In addition, the relative standard deviation of the length is preferably 40% or less. Moreover, it is preferable that an average diameter is small from a transparency viewpoint, On the other hand, the larger one is preferable from an electroconductive viewpoint. In this invention, 10-300 nm is preferable as an average diameter of metal nanowire, and it is more preferable that it is 30-200 nm. In addition, the relative standard deviation of the diameter is preferably 20% or less.

  There is no restriction | limiting in particular as a metal composition of the metal nanowire which concerns on this invention, Although it can comprise from the 1 type or several metal of a noble metal element and a base metal element, noble metals (for example, gold, platinum, silver, palladium, rhodium, (Iridium, ruthenium, osmium, etc.) and at least one metal belonging to the group consisting of iron, cobalt, copper, and tin is preferable, and at least silver is more preferable from the viewpoint of conductivity. In order to achieve both conductivity and stability (sulfurization and oxidation resistance of metal nanowires and migration resistance), it is also preferable to include silver and at least one metal belonging to a noble metal other than silver. When the metal nanowire according to the present invention includes two or more kinds of metal elements, for example, the metal composition may be different between the inside and the surface of the metal nanowire, or the entire metal nanowire has the same metal composition. May be.

  In the present invention, the means for producing the metal nanowire is not particularly limited, and for example, known means such as a liquid phase method and a gas phase method can be used. Moreover, there is no restriction | limiting in particular in a specific manufacturing method, A well-known manufacturing method can be used. For example, as a method for producing Ag nanowires, Adv. Mater. , 2002, 14, 833-837; Chem. Mater. , 2002, 14, 4736-4745, etc. As a method for producing Co nanowires, a method for producing Au nanowires is disclosed in JP 2006-233252A, and a method for producing Cu nanowires is disclosed in JP 2002-266007 A, etc. Reference can be made to Japanese Unexamined Patent Publication No. 2004-149871. In particular, Adv. Mater. And Chem. Mater. The method for producing Ag nanowires reported in (1) can be easily produced in an aqueous system, and since the conductivity of silver is the highest among metals, it is preferable as the method for producing metal nanowires according to the present invention. Can be applied.

<Water-soluble polymer>
Examples of the water-soluble polymer of the present invention include natural polymers such as starch, gelatin and agar, semi-synthetic polymers such as carboxymethylcellulose (CMC), hydroxyethylcellulose (HEC), cellulose derivatives such as methylcellulose (MC), and synthetic polymers. Can be widely selected from polyvinyl alcohol (PVA), polyacrylic acid polymer, polyacrylamide (PAM), polyethylene oxide (PEO), polyvinylpyrrolidone (PVP), and the like.

<Aqueous polymer emulsion>
Examples of the aqueous polymer emulsion of the present invention include acrylic resins (acrylic silicone-modified resins, fluorine-modified acrylic resins, urethane-modified acrylic resins, epoxy-modified acrylic resins, etc.), polyester resins, urethane resins, vinyl acetate resins, etc. Can be widely selected and used.

<Conductive polymer>
The conductive polymer of the present invention is not particularly limited, and polypyrrole, polyindole, polycarbazole, polythiophene (including basic polythiophene, the same applies hereinafter) system, polyaniline system, polyacetylene system, polyfuran system, polyparaphenylene vinylene system Also, chain conductive polymers such as polyazulene, polyparaphenylene, polyparaphenylene sulfide, polyisothianaphthene, and polythiazyl, and polyacene conductive polymers can be used. Of these, polyethylene dioxythiophene (PEDOT) and polyaniline are preferable from the viewpoints of conductivity and transparency.

Moreover, in this invention, in order to raise the electroconductivity of the said conductive polymer more, it is preferable to perform a doping process. As a dopant for the conductive polymer, for example, a sulfonic acid having a hydrocarbon group having 6 to 30 carbon atoms (hereinafter also referred to as “long-chain sulfonic acid”) or a polymer thereof (for example, polystyrene sulfonic acid), halogen , Lewis acid, proton acid, transition metal halide, transition metal compound, alkali metal, alkaline earth metal, MClO ₄ (M = Li ⁺ , Na ⁺ ), (R) ₄ N ⁺ (R = CH ₃ , C ₄ H ₉ , C ₅₆ ), or (R) ₄ P ⁺ (R═CH ₃ , C ₄ H ₉ , C ₅₆ ), at least one selected from the group. Of these, the long-chain sulfonic acid is preferable.

Examples of the long chain sulfonic acid include dinonyl naphthalene disulfonic acid, dinonyl naphthalene sulfonic acid, and dodecylbenzene sulfonic acid. Examples of the halogen include Cl ₂ , Br ₂ , I ₂ , ICl ₃ , IBr, IF _{5 and the} like. Examples of the Lewis acid include PF ₅ , AsF ₅ , SbF ₅ , BF ₃ , BCl ₃ , BBr ₃ , SO ₃ , GaCl _{3 and the} like. Examples of the protonic acid include HF, HCl, HNO ₃ , H ₂ SO ₄ , HBF ₄ , HClO ₄ , FSO ₃ H, ClSO ₃ H, CF ₃ SO ₃ H, and the like. The transition metal _{halide, NbF 5, TaF 5, MoF} 5, WF 5, RuF 5, BiF 5, TiCl 4, ZrCl 4, MoCl 5, MoCl 3, WCl 5, FeCl 3, TeCl 4, SnCl 4, SeCl ₄ , FeBr ₃ , SnI _{5 and the} like. The transition metal _{compound, AgClO 4, AgBF 4, La} (NO 3) 3, Sm (NO 3) 3 and the like. Examples of the alkali metal include Li, Na, K, Rb, and Cs. Examples of the alkaline earth metal include Be, Mg, Ca, Sc, and Ba.

The dopant for the conductive polymer may be introduced into fullerenes such as hydrogenated fullerene, hydroxylated fullerene, and sulfonated fullerene. It is preferable that 0.001 mass part or more of the said dopant is contained with respect to 100 mass parts of conductive polymers. Furthermore, it is more preferable that 0.5 mass part or more is contained. In addition, the transparent conductive composition of the present embodiment is a long-chain sulfonic acid, a polymer of long-chain sulfonic acid (for example, polystyrene sulfonic acid), halogen, Lewis acid, proton acid, transition metal halide, transition metal compound, Both at least one dopant selected from the group consisting of alkali metals, alkaline earth metals, MClO ₄ , (R) ₄ N ⁺ , and (R) ₄ P ⁺ and fullerenes may be included.

  The conductive polymer of the present invention has 2nd. A water-soluble organic compound may be contained as a dopant. There is no restriction | limiting in particular in the water-soluble organic compound which can be used by this invention, It can select suitably from well-known things, For example, an oxygen containing compound is mentioned suitably. The oxygen-containing compound is not particularly limited as long as it contains oxygen, and examples thereof include a hydroxyl group-containing compound, a carbonyl group-containing compound, an ether group-containing compound, and a sulfoxide group-containing compound. Examples of the hydroxyl group-containing compound include ethylene glycol, diethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, and glycerin. Among these, ethylene glycol and diethylene glycol are preferable. Examples of the carbonyl group-containing compound include isophorone, propylene carbonate, cyclohexanone, and γ-butyrolactone. Examples of the ether group-containing compound include diethylene glycol monoethyl ether. Examples of the sulfoxide group-containing compound include dimethyl sulfoxide. These may be used alone or in combination of two or more, but it is particularly preferable to use at least one selected from dimethyl sulfoxide, ethylene glycol, and diethylene glycol.

  In the conductive polymer of the present invention, the 2nd. The content of the dopant is preferably 0.001 parts by mass or more, more preferably 0.01 to 50 parts by mass, and particularly preferably 0.01 to 10 parts by mass.

<Metal oxide>
As the metal oxide of the present invention, a known transparent metal oxide conductive material can be used. For example, tin, tellurium, cadmium, molybdenum, tungsten, fluorine, zinc, germanium, antimony, etc. added indium oxide, tin oxide, cadmium oxide, aluminum, germanium, etc. added as dopants such as zinc oxide, titanium oxide, etc. A metal oxide is mentioned.

  The metal oxide of the present invention preferably contains an oxide of a metal selected from indium, zinc, and tin. Specifically, ITO in which tin is doped into indium oxide, or aluminum or gallium is doped into zinc oxide. It is preferable to contain a metal oxide selected from ATO, GZO, and ATO or FTO in which tin oxide is doped with antimony or fluorine. The average particle diameter of the metal oxide is preferably 1 to 100 nm, and particularly preferably 3 to 50 nm.

  The dispersion containing the metal oxide fine particles may contain a transparent binder material or additive in addition to the metal oxide fine particles. The transparent binder material can be selected from a wide range of natural polymer resins or synthetic polymer resins. For example, transparent thermoplastic resin (eg, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polymethyl methacrylate, nitrocellulose, chlorinated polyethylene, chlorinated polypropylene, vinylidene fluoride), heat, light, electron beam A transparent curable resin that is cured by radiation (for example, melamine acrylate, urethane acrylate, epoxy resin, polyimide resin, silicon resin such as acrylic-modified silicate) can be used. Examples of the additive include plasticizers, stabilizers such as antioxidants and sulfurization inhibitors, surfactants, dissolution accelerators, polymerization inhibitors, and colorants such as dyes and pigments. Furthermore, from the viewpoint of improving workability such as coating properties, solvents (for example, water, organic solvents such as alcohols, glycols, cellosolves, ketones, esters, ethers, amides, hydrocarbons, etc.) are used. May be included.

<Transparent electrode>
In the transparent electrode of the present invention, the surface roughness of the conductive layer is preferably highly smooth because it affects the performance of the EL element or the like. Specifically, the arithmetic average roughness Ra is Ra ≦ 5 nm. Is preferable, Ra ≦ 3 nm is more preferable, and Ra ≦ 1 nm is further more preferable. The maximum height Ry is preferably Ry ≦ 50 nm, more preferably Ry ≦ 40 nm, and further preferably Ry ≦ 30 nm.

  In the transparent electrode of the present invention, the total light transmittance of the conductive layer containing metal nanowires is preferably 60% or more, preferably 70% or more, and particularly preferably 80% or more. The total light transmittance can be measured according to a known method using a spectrophotometer or the like.

In the transparent electrode of the present invention, the electrical resistance value of the conductive layer containing metal nanowires is preferably 10 ³ Ω / □ or less as the surface specific resistance, more preferably 10 ² Ω / □ or less, It is particularly preferably 10Ω / □ or less. The surface specific resistance can be measured, for example, according to JIS K6911, ASTM D257, etc., and can be easily measured using a commercially available surface resistivity meter. The surface specific resistance only needs to satisfy the surface specific resistance in the state of the metal nanowire alone, and the metal nanowire functions as a bus electrode. Therefore, even if the surface specific resistance of the conductive polymer is high, the metal nanowire-containing conductive layer Can be made uniform. The surface specific resistance of the conductive polymer is 10 ⁴ Ω / □ or more and 10 ⁹ Ω / □ or less, which can make the conductivity of the metal nanowire-containing conductive layer uniform without affecting current leakage between the metal nanowire-containing conductive layers. It is preferable that it is 10 ⁶ Ω / □ or more and 10 ⁹ Ω / □ or less.

  An anchor coat, a hard coat, etc. can also be provided to the transparent electrode of the present invention. If necessary, a conductive layer containing a conductive polymer or a metal oxide may be further provided.

  The transparent electrode of the present invention can be used for transparent electrodes such as LCDs, electroluminescent elements, plasma displays, electrochromic displays, solar cells, touch panels, electronic paper, and electromagnetic wave shielding materials, etc., but has excellent conductivity and transparency. In addition, since it has high smoothness, it is preferably used for an organic EL device.

<Organic EL device>
The organic EL element in the present invention has the transparent electrode of the present invention. The organic EL element in the present invention uses the transparent electrode of the present invention as an anode, and the organic light-emitting layer and the cathode can be made of any material and configuration generally used in organic EL elements. As an element configuration of the organic EL element,
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,
The thing of various structures, such as these, can be mentioned.

  In addition, as the light emitting material or doping material that can be used in the organic light emitting layer in the present invention, anthracene, naphthalene, pyrene, tetracene, coronene, perylene, phthaloperylene, naphthaloperylene, diphenylbutadiene, tetraphenylbutadiene, coumarin, oxadiazole, bisbenzo Xazoline, bisstyryl, cyclopentadiene, quinoline metal complex, tris (8-hydroxyquinolinato) aluminum complex, tris (4-methyl-8-quinolinato) aluminum complex, tris (5-phenyl-8-quinolinato) aluminum complex, Aminoquinoline metal complex, benzoquinoline metal complex, tri- (p-terphenyl-4-yl) amine, 1-aryl-2,5-di (2-thienyl) pyrrole derivative, pyran, quinacridone Rubrene, distyrylbenzene derivatives, di still arylene derivatives, and various fluorescent dyes and rare earth metal complex, there are phosphorescent materials, but is not limited thereto. It is also preferable to include 90 to 99.5 parts by mass of a light emitting material selected from these compounds and 0.5 to 10 parts by mass of a doping material. The organic light emitting layer is prepared by a known method using the above materials and the like, and examples thereof include vapor deposition, coating, and transfer. The thickness of the organic light emitting layer is preferably 0.5 to 500 nm, particularly preferably 0.5 to 200 nm.

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

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "%" is used in an Example, unless otherwise indicated, "mass%" is represented.

<< Preparation of transparent electrode >>
[Production of silver nanowires]
With reference to the method described in non-patent literature (Adv. Mater., 2002, 14, 833-837), silver nanowires were produced by the following method.

(Nucleation process)
While stirring 1000 ml of EG solution maintained at 170 ° C. in the reaction vessel, 100 ml of EG solution of silver nitrate (silver nitrate concentration: 1.5 × 10 ⁻⁴ mol / L) was added at a constant flow rate for 10 seconds. Thereafter, aging was carried out at 170 ° C. for 10 minutes to form silver core particles. The reaction solution after completion of ripening exhibited a yellow color derived from surface plasmon absorption of silver nanoparticles, and it was confirmed that silver ions were reduced and silver nanoparticles were formed.

(Particle growth process)
The reaction solution containing the core particles after completion of the ripening is maintained at 170 ° C. with stirring, and 1000 ml of an EG solution of silver nitrate (silver nitrate concentration: 1.0 × 10 ⁻¹ mol / L) and an EG solution of VP (VP) Concentration conversion: 5.0 × 10 ⁻¹ mol / L) 1000 ml was added at a constant flow rate for 100 minutes using the double jet method. When the reaction solution was sampled every 20 minutes in the particle growth process and confirmed with an electron microscope, the silver nanoparticles formed in the nucleation process grew mainly in the long axis direction of the nanowires over time. No new core particles were observed in the grain growth process.

(Washing process)
After completion of the particle growth step, the reaction solution was cooled to room temperature, filtered using a filter, and the silver nanowires separated by filtration were redispersed in ethanol. Filtration of silver nanowires with a filter and redispersion in ethanol were repeated 5 times, and finally an aqueous dispersion of silver nanowires was prepared to produce silver nanowires.

  When a small amount of the obtained dispersion was collected and confirmed with an electron microscope, it was confirmed that silver nanowires having an average diameter of 85 nm and an average length of 7.4 μm were formed.

[Preparation of polyester polymer solution-1]
Compound (UL-1) 0.01 g
Modified polyester A (solid content 18%) 3g
50g of water

(Synthesis of modified aqueous polyester A)
In a reaction vessel for polycondensation, 35.4 parts by mass of dimethyl terephthalate, 33.63 parts by mass of dimethyl isophthalate, 17.92 parts by mass of 5-sulfo-isophthalic acid dimethyl sodium salt, 62 parts by mass of ethylene glycol, calcium acetate monohydrate 0.065 parts by mass of salt and 0.022 parts by mass of manganese acetate tetrahydrate were added, and the ester exchange reaction was performed while distilling off methanol at 170 to 220 ° C. in a nitrogen stream. 04 parts by mass, 0.04 parts by mass of antimony trioxide as a polycondensation catalyst and 6.8 parts by mass of 1,4-cyclohexanedicarboxylic acid were added, and a theoretical amount of water was distilled off at a reaction temperature of 220 to 235 ° C. Esterification was performed. Thereafter, the reaction system was further depressurized and heated for about 1 hour, and finally subjected to polycondensation at 280 ° C. and 133 Pa or less for about 1 hour to obtain a modified aqueous polyester A precursor. The intrinsic viscosity of the precursor was 0.33.

  850 ml of pure water was put into a 2 L three-necked flask equipped with a stirring blade, a reflux condenser, and a thermometer, and 150 g of the precursor was gradually added while rotating the stirring blade. After stirring for 30 minutes at room temperature, the mixture was heated to an internal temperature of 98 ° C. over 1.5 hours, and heated and dissolved at this temperature for 3 hours. After completion of the heating, the mixture was cooled to room temperature over 1 hour and left overnight to prepare a solution having a solid content concentration of 15% by mass.

  1900 ml of the precursor solution was placed in a 3 L four-necked flask equipped with a stirring blade, a reflux condenser, a thermometer, and a dropping funnel, and the internal temperature was heated to 80 ° C. while rotating the stirring blade. To this, 6.52 ml of a 24% aqueous solution of ammonium persulfate was added, and a monomer mixture (28.5 g of glycidyl methacrylate, 21.4 g of ethyl acrylate, 21.4 g of methyl methacrylate) was dropped over 30 minutes. The reaction was continued for another 3 hours. Then, it cooled to 30 degrees C or less, and filtered, and prepared the solution of the modified aqueous polyester A whose solid content concentration is 18 mass% (polyester component / acrylic component = 80/20).

[Preparation of acrylic polymer emulsion-1]
Copolymer latex liquid of 20 parts by mass of styrene, 40 parts by mass of glycidyl methacrylate and 40 parts by mass of butyl acrylate (solid content: 30%) 10 g
Compound (UL-1) 0.01 g
30 g of water
[Preparation of Transparent Electrode 101; Comparative Example 1]
A polyethylene terephthalate film (hereinafter referred to as PET) having a thickness of 100 μm that has been subjected to corona discharge treatment is used as a support, and the prepared silver nanowire dispersion is used as a conductive layer so that the basis weight of the silver nanowire is 0.07 g / m ^2. As described above, it was applied using a spin coater and dried. This was cut into a 50 mm × 50 mm square to produce a transparent electrode 101.

[Preparation of Transparent Electrode 102; Comparative Example 2]
In preparation of the transparent electrode 101, the transparent electrode 102 was created by performing the same operation except that the silver nanowire was applied and dried, and then the calendar process was performed.

[Preparation of transparent electrode 103; Invention 1]
On a PET film support similar to the transparent electrode 101, a 2% gelatin aqueous solution was coated as a polymer layer with a wet film thickness of 8 μm using a doctor blade. Further, silver nanowires were coated on the polymer layer with a doctor blade so as to be 0.07 g / m ² , dried, and then cut to create a transparent electrode 103. The water content of the polymer layer when the silver nanowire was applied was 500%.

[Preparation of Transparent Electrode 104; Present Invention 2]
In the production of the transparent electrode 103, the same operation was performed except that the polymer layer 1 was used as the polymer layer and was coated with a doctor blade with a wet film thickness of 5 μm to produce the transparent electrode 104. . The water content of the polymer layer when the silver nanowire was applied was 250%.

[Preparation of transparent electrode 105; Invention 3]
In the production of the transparent electrode 103, a transparent electrode 105 was produced in the same manner as the polymer layer except that a 2% gelatin aqueous solution was coated with a doctor blade at a wet film thickness of 20 μm. The water content of the polymer layer when the silver nanowire was applied was 150%.

[Preparation of transparent electrode 106; Invention 4]
On the PET film, a 10% carboxymethyl cellulose (hereinafter referred to as CMC) solution was wet film thickness of 4 μm as a polymer layer, and a silver nanowire liquid was wet film thickness of 50 μm as a conductive layer, and simultaneous multilayer coating was performed using an applicator. After drying, a transparent electrode 106 was created.

[Preparation of transparent electrode 107; Invention 5]
In the production of the transparent electrode 103, a transparent electrode 107 was produced in the same manner as the polymer layer except that a 5% CMC aqueous solution was applied with a doctor blade at a wet film thickness of 5 μm. The water content of the polymer layer when the silver nanowire was applied was 150%.

[Preparation of Transparent Electrode 108; Present Invention 6]
On the PET film, water-soluble polymer EPOCROSS WS-700 (manufactured by Nippon Shokubai Co., Ltd.) with a wet film thickness of 2 μm as a polymer layer and silver nanowire liquid with a wet film thickness of 50 μm as a conductive layer are applied simultaneously with an applicator It was. After drying, a transparent electrode 108 was created.

[Preparation of Transparent Electrode 109; Present Invention 7]
In the production of the transparent electrode 103, the transparent electrode 109 was produced in the same manner as the polymer layer except that the acrylic polymer emulsion-1 was coated with a doctor blade at a wet film thickness of 5 μm. The water content of the polymer layer when the silver nanowires were applied was 230%.

[Preparation of transparent electrode 110; Invention 8]
In the production of the transparent electrode 103, 5% of dimethyl sulfoxide was added as a polymer layer to Baytron PH510 (manufactured by HC Starck) which is a dispersion of PEDOT: PSS (polystyrene sulfonic acid) = 1: 2.5. The transparent electrode 110 was prepared in the same manner as described above except that gelatin was added to this solution (hereinafter referred to as PEDOT dispersion), and a solution having a gelatin concentration of 10% was applied with a doctor blade to a wet film thickness of 3 μm. It was created. The water content of the polymer layer when the silver nanowire was applied was 300%.

[Preparation of Transparent Electrode 111; Present Invention 9]
On the PET film, a 10% CMC aqueous solution was coated as a polymer layer with a wet film thickness of 1 μm. Furthermore, a conductive polyaniline dispersion (ORMECON D1033, manufactured by Olmecon, Germany) containing a sulfonic acid dopant is added to the silver nanowire dispersion as a conductive layer, and the viscosity is adjusted to 40 mPa · s. The transparent electrode 111 was formed by coating and drying at 50 μm. The water content of the polymer layer when the silver nanowire was applied was 250%.

[Preparation of Transparent Electrode 112; Present Invention 10]
In the production of the transparent electrode 103, a 5% gelatin aqueous solution was applied as a polymer layer with a doctor blade with a wet film thickness of 6 μm. Further, a 10-mm stripe pattern was formed by an ink jet printer so that the silver nanowire dispersion liquid was 0.07 g / m ² as a conductive layer, and the transparent electrode 112 was formed. The water content of the polymer layer when the silver nanowire was applied was 150%.

[Preparation of transparent electrode 113; Invention 11]
On the PET film, a 5% gelatin aqueous solution was coated as a polymer layer with a wet film thickness of 8 μm. Furthermore, the conductive polyaniline-containing silver nanowire dispersion liquid used in the production of the transparent electrode 111 is formed with a 10 mm stripe pattern with an ink jet printer so that the basis weight of the silver nanowire is 0.07 g / m ² . A transparent electrode 113 was produced. The water content of the polymer layer when the silver nanowire was applied was 150%.

[Preparation of Transparent Electrode 114; Present Invention 12]
Using the transparent electrode 103, water was applied to the surface with a doctor blade at 1 μm and dried to form a transparent electrode 114.

[Preparation of transparent electrode 115; Invention 13]
The transparent electrode 107 was used, soaked in water for 0.5 seconds, and then dried to create a transparent electrode 115.

[Measurement]
The smoothness Ra, Ry, transmittance, and surface specific resistance of the transparent electrodes 101 to 115 were evaluated by the following methods.

(Surface roughness)
In the present invention, Ra and Ry representing the smoothness of the surface of the conductive layer mean Ra = arithmetic mean roughness and Ry = maximum height (the difference in height between the top and bottom of the surface), and JIS B601 (1994). It is a value according to the surface roughness specified in). In the present invention, for measurement of Ra and Ry, a commercially available atomic force microscope (AFM) can be used, and measurement was performed by the following method.

  Using an SPI 3800N probe station and SPA400 multifunctional unit manufactured by Seiko Instruments Inc. as the AFM, set the sample cut to a size of about 1 cm square on a horizontal sample stage on the piezo scanner, and place the cantilever on the sample surface. When approaching and reaching the region where the atomic force works, scanning is performed in the XY direction, and the unevenness of the sample at that time is captured by the displacement of the piezo in the Z direction. A piezo scanner that can scan XY 20 μm and Z 2 μm is used. The cantilever is a silicon cantilever SI-DF20 manufactured by Seiko Instruments Inc., which has a resonance frequency of 120 to 150 kHz and a spring constant of 12 to 20 N / m, and is measured in a DFM mode (Dynamic Force Mode). A measurement area of 80 × 80 μm is measured at a scanning frequency of 1 Hz.

(Transmittance)
The transmittance was determined by measuring the total light transmittance (%) of the conductive layer pattern portion by using AUTOMATIC ZEMETER (MODEL TC-HIIIDP) manufactured by Tokyo Denshoku Co., Ltd.

(Surface resistivity)
For the surface specific resistance, the surface specific resistance (Ω / □) of the conductive layer pattern portion was measured by a four-terminal method using a resistivity meter Loresta GP manufactured by Dia Instruments.

  The results of measurement and evaluation are shown in Table 1.

  Table 1 shows that the transparent electrode of this invention is excellent in electroconductivity (surface specific resistance) and transparency (transmittance), and has high smoothness (surface shape).

<< Production of organic EL element (organic EL element) >>
Using the produced transparent electrodes 101 to 115 as the first electrode, organic EL elements 201 to 215 were produced in the following procedure.

<Formation of hole transport layer>
On the first electrode, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), which is a hole transport material, was added to 1% by mass in 1,2-dichloroethane. The dissolved coating solution for forming a hole transport layer was applied by a spin coater and then dried at 80 ° C. for 60 minutes to form a hole transport layer having a thickness of 40 nm.

<Formation of light emitting layer>
On each film in which the hole transport layer is formed, the red dopant material Btp ₂ Ir (acac) is 1% by mass and the green dopant material Ir (ppy) ₃ is 2% with respect to polyvinylcarbazole (PVK) as the host material. %, Blue dopant material FIr (pic) is mixed so as to be 3% by mass, and the light emission is dissolved in 1,2-dichloroethane so that the total solid concentration of PVK and the three dopants is 1% by mass. The coating liquid for layer formation was applied with a spin coater and then dried at 100 ° C. for 10 minutes to form a light emitting layer having a thickness of 60 nm.

<Formation of electron transport layer>
On the formed light emitting layer, LiF was evaporated as a material for forming an electron transport layer under a vacuum of 5 × 10 ⁻⁴ Pa to form an electron transport layer having a thickness of 0.5 nm.

<Formation of second electrode>
On the formed electron carrying layer, Al was vapor-deposited as a 2nd electrode formation material under the vacuum of 5 * 10 <^-4> Pa, and the 2nd electrode with a thickness of 100 nm was formed.

<Formation of sealing film>
On the formed electron transport layer, a polyethylene terephthalate as a substrate, using a flexible sealing member which is deposited to a thickness 300nm of Al ₂ O _3. Apply the adhesive around the second electrode except for the end so that the external lead terminals of the first electrode and the second electrode can be formed, paste the flexible sealing member, and then cure the adhesive by heat treatment It was.

[Light emission brightness unevenness]
Using a source measure unit 2400 type manufactured by KEITHLEY, a direct current voltage was applied to the organic EL elements 201 to 215 produced, and light was emitted. About each organic EL element made to light-emit by 200cd / m < ² >, the light emission nonuniformity of the whole light emission surface at the time of lighting was evaluated on the following reference | standard by visual observation. The evaluation results are shown in Table 2.
◎: 90% or more uniformly emitted ◯: 80% or more emitted uniformly Δ: 70% or more emitted uniformly ×: Less than 70% emitted XX: Nothing Table 2 shows the evaluation results.

  As is clear from Table 2, when the transparent electrode of the present invention having excellent conductivity and transparency and high smoothness is used as an electrode of an organic electroluminescence element, it is understood that the organic electroluminescence element has little emission luminance unevenness. .

Claims (6)

A transparent electrode having a conductive layer containing metal nanowires on a transparent support, the transparent electrode being a polymer layer comprising at least one of a water-soluble polymer or an aqueous polymer emulsion in a lower layer adjacent to the conductive layer A transparent electrode characterized in that at least a part of the metal nanowire is embedded in the polymer layer. In the method for producing a transparent electrode in which a polymer layer composed of at least one of a water-soluble polymer or an aqueous polymer emulsion and a conductive layer composed of metal nanowires are sequentially formed on a transparent support, A method for producing a transparent electrode, comprising: applying a conductive layer on a polymer layer in a state where a water content of the polymer layer is 100% or more after applying the molecular layer. In the method for producing a transparent electrode, in which a polymer layer composed of at least one of a water-soluble polymer or an aqueous polymer emulsion and a conductive layer composed of metal nanowires are sequentially formed on a transparent support, the polymer layer and the conductive layer A method for producing a transparent electrode, characterized in that the layers are applied simultaneously in multiple layers. The method for producing a transparent electrode according to claim 2, wherein patterning is performed when the conductive layer is applied on the polymer layer. It is a manufacturing method of the transparent electrode of any one of Claims 2-4, Comprising: After apply | coating and drying the said polymer layer and the said conductive layer, water is apply | coated and dried to this conductive layer surface as a post-process. A method for producing a transparent electrode. An organic electroluminescence device comprising the transparent electrode according to claim 1 or the transparent electrode produced by the method for producing a transparent electrode according to any one of claims 2 to 5.