JP2003346925A - Photoelectric converting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric converting element having superior photoelectric converting characteristic. <P>SOLUTION: This photoelectric converting element uses at least one kind of pigment represented by formula (1) as a photoelectric converting material. In the formula (1), R<SB>1</SB>is H, alkyl, alkoxy, alkylchio or heterocyclic residue, respectively optionally having a substituent, R<SB>2</SB>is alkyl, optionally having a substituent, R<SB>3</SB>-R<SB>6</SB>are H, alkyl, alkoxy, alkylthio, aryl or heterocyclic residue, respectively optionally having a substituent, R<SB>7</SB>, R<SB>8</SB>are substituents having an acid group, A-part and B-part are heterocycle forming five-seven-membered rings with carbonyl and amino substituted for R<SB>7</SB>or R<SB>8</SB>, X<SB>1</SB>is O or S, X<SB>2</SB>is O, S, dicyanomethylene or cyano acetic acid, n is integer of 0-2, m is integer of 0-2, and carbon - carbon double bond may be E-type or Z-type. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a photoelectric conversion element using a dye represented by the general formula (1) as a photoelectric conversion material.

[0002]

_2. Description of the Related Art Global warming caused by an increase in the concentration of CO ₂ caused by the use of a large amount of fossil fuels and an increase in energy demand due to an increase in population are recognized as problems related to the survival of mankind. Therefore, in recent years, the use of sunlight that is infinite and does not generate harmful substances has been vigorously studied. As the clean energy source, the solar cell which is currently in practical use includes residential single crystal silicon, polycrystalline silicon, amorphous silicon, and inorganic solar cells such as cadmium telluride and indium copper selenide.

[0003] However, silicon used in these solar cells needs to be very high in purity, and of course, the purification process is complicated, the number of processes is large, and high production cost is required. As described above, the photovoltaic power generation using the inorganic material is disadvantageous in terms of cost and long payback to the user, and there is a problem in spreading the photovoltaic power generation.

On the other hand, many solar cells using an organic material have been proposed. As an organic solar cell, a Schottky type photoelectric conversion element for joining a p-type organic semiconductor and a metal having a small work function, a p-type organic semiconductor and an n-type inorganic semiconductor,
Alternatively, there is a heterojunction type photoelectric conversion element or the like that joins a p-type organic semiconductor and an electron-accepting organic compound, and the organic semiconductor to be used is a synthetic dye or pigment such as chlorophyll or perylene, a conductive polymer material such as polyacetylene, Or a composite material thereof. These are made into a thin film by a vacuum evaporation method, a casting method, a dipping method, or the like to form a battery material. Organic materials have advantages such as low cost and easy area enlargement, but many have low conversion efficiencies of 1% or less and have poor durability.

Under these circumstances, Nature (Vol. 353, P7
"Photoelectric conversion elements and solar cells using dye-sensitized semiconductor fine particles" reported in U.S. Pat. This document also discloses materials and manufacturing techniques required for battery fabrication. The proposed battery is a wet type solar cell called a Grettzel type, which uses a titanium oxide porous thin film spectrally sensitized with a ruthenium complex as a working electrode. The advantage of this method is that it is not necessary to purify inexpensive oxide semiconductors such as titanium oxide to a high degree of purity. Therefore, it is inexpensive, and the available light extends over a wide visible light range. The ability to convert light into electricity effectively.

On the other hand, a very expensive ruthenium complex is used, and improvement in cost is required. This problem can be solved if the expensive ruthenium complex can be changed to an inexpensive organic dye such as cyanine. The cyanine dyes studied as dyes for this battery include those described in
JP-A-238905, JP-A-11-214731, and JP-A-2001-52766. However, these cyanine dyes have low adsorption to titanium oxide and also have a problem in stability over time, so that at present, a high sensitizing effect has not been obtained.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-performance photoelectric conversion element.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, at least one of the dyes represented by the general formula (1) is used as a photoelectric conversion material. Things were done.

[0009]

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In the general formula (1), R ₁ is a hydrogen atom,
It represents an alkyl group, an aryl group, an alkoxy group, an alkylthio group, or a heterocyclic residue, each of which may have a substituent. R ₂ represents an alkyl group, which may have a substituent. R _{3 to} R _{6 each} represent a hydrogen atom, an alkyl group, an alkoxy group, an alkylthio group, an aryl group, or a heterocyclic residue, each of which may have a substituent. R ₇ and R ₈ each represent a substituent having an acidic group, and A and B parts represent a carbonyl group and a heterocyclic ring which forms a 5- to 7-membered ring together with an amino group which substitutes R ₇ or R ₈ . X ₁ represents an oxygen atom or a sulfur atom, and X ₂ represents an oxygen atom, a sulfur atom, a dicyanomethylene group, or a cyanoacetate group. n represents an integer of 0 to 2;
Represents an integer of 0 to 2. The carbon-carbon double bond is E-form,
Or, it may be any of Z type.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Here, specific examples of R ₁ include:
Hydrogen atom, methyl group, ethyl group, alkyl group such as isopropyl group, phenyl group, aryl group such as naphthyl group, methoxy group, alkoxy group such as ethoxy group, methylthio group, alkylthio group such as isopropylthio group, furyl group, Examples include heterocyclic residues such as a thienyl group and an indolyl group. R ₁ may have a substituent, and specific examples of the substituent include the above-described alkyl group,
The above-mentioned alkoxy group, chlorine, halogen atoms such as bromine, dimethylamino group, di-substituted amino group such as diphenylamino group, the above-mentioned aryl group, the above-mentioned heterocycle, carboxyl group, carboxyalkyl group such as carboxymethyl group, Examples include a sulfonylalkyl group such as a sulfonylpropyl group, an acidic group such as a phosphoric acid group and a hydroxamic acid group, and an electron-withdrawing group such as a cyano group, a nitro group, and a trifluoromethyl group. Specific examples of R ₂ include the above-described alkyl groups. Further, R ₂ may have a substituent, and specific examples of the substituent include the above-mentioned alkyl group, the above-mentioned alkoxy group, the above-mentioned aryl group, and the above-mentioned heterocyclic residue. . R ₃ ~
Specific examples of R ₆ include a hydrogen atom, the above-described alkyl group,
Examples include the above-described alkylthio groups such as the above-described alkoxy group, methylthio group, and isopropylthio group, the above-described aryl group, and the above-described heterocyclic group. R _{3 to} R ₆ may have a substituent, and specific examples of the substituent include the above-mentioned alkyl group, the above-mentioned alkoxy group, the above-mentioned alkylthio group, the above-mentioned halogen atom, and the above-mentioned di-substitution. Examples include an amino group, the above-mentioned aryl group, the above-mentioned heterocyclic ring, and the above-mentioned electron-withdrawing group. Specific examples of R ₇ and R ₈ include the above-mentioned acidic groups. Specific examples of X ₁ include an oxygen atom and a sulfur atom, and specific examples of X ₂ include an oxygen atom, a sulfur atom, a dicyanomethylene group,
A cyanoacetic acid group can be mentioned. Specific examples of Part A and Part B include the compounds shown in the following (2) to (5), and specific examples of R ₉ are the same as R ₇ and R ₈ . However, these specific examples are not limited.

[0012]

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Next, specific examples of the dye of the present invention will be described with reference to A-1 to A
-24, but is not limited thereto.

[0014]

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[0015]

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[0016]

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[0017]

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[0018]

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The photoelectric conversion element of the present invention comprises a conductive support,
It consists of a semiconductor layer sensitized by a dye placed on a conductive support, a charge transfer layer, and a counter electrode. The photosensitive layer may have a single-layer structure or a laminated structure, and is designed according to the purpose. Further, at the boundary of the element, such as the boundary between the conductive layer and the photosensitive layer of the conductive support, or the boundary between the photosensitive layer and the moving layer, the components of each layer may be mutually diffused or mixed.

As the conductive support, there can be used a support having a conductive property itself, such as a metal, or a glass or plastic support having a conductive layer containing a conductive agent on the surface. In the latter case, the conductive agent is platinum,
Metals such as gold, silver, copper, and aluminum, carbon, or indium-tin composite oxide (hereinafter abbreviated as “ITO”), and metal oxides such as tin oxide doped with fluorine (hereinafter abbreviated as “FTO”) And the like. The conductive support preferably has transparency of transmitting 10% or more of light, and more preferably transmits 50% or more of light. Among them, conductive glass in which a conductive layer made of ITO or FTO is deposited on glass is particularly preferable.

For the purpose of lowering the resistance of the transparent conductive substrate, metal leads may be used. The material of the metal lead wire is preferably a metal such as aluminum, copper, silver, gold, platinum, and nickel. The metal lead wire may be provided on a transparent substrate by vapor deposition, sputtering, or the like, and ITO or FTO may be provided thereon, or a metal lead wire may be provided on a transparent conductive layer.

As the semiconductor, in addition to a simple semiconductor such as silicon or germanium, a compound semiconductor represented by a metal chalcogenide, a compound having a perovskite structure, or the like can be used. Preferably, the metal chalcogenide is titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum,
Vanadium, niobium, or tantalum oxide, cadmium, zinc, lead, silver, antimony, bismuth sulfide, cadmium, lead selenide, cadmium telluride, and the like can be given. Other compound semiconductors include zinc,
Examples include phosphides such as gallium, indium and cadmium, gallium arsenide, copper-indium-selenide, copper-indium-sulfide and the like. Further, as the compound having a perovskite structure, strontium titanate,
Examples thereof include calcium titanate, sodium titanate, barium titanate, and potassium niobate.

The semiconductor used in the present invention may be single crystal or polycrystal. A single crystal is preferable as the conversion efficiency, but a polycrystal is preferable in terms of manufacturing cost, securing of raw materials, and the like, and the semiconductor preferably has a particle diameter of 4 nm or more and 1 μm or less.

As a method of forming a semiconductor layer on a conductive support, there are a method of applying a dispersion or colloid solution of semiconductor fine particles on the conductive support, a sol-gel method, and the like. As a method for preparing the dispersion, the above-mentioned sol-gel method, a method of mechanically pulverizing with a mortar, a method of dispersing while pulverizing using a mill, or precipitating as fine particles in a solvent when synthesizing a semiconductor. And then use it as it is.

A dispersion prepared by mechanical pulverization or pulverization using a mill is formed by dispersing at least semiconductor fine particles alone or semiconductor fine particles and a binder resin in water or an organic solvent. Examples of the binder resin used include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, acrylates, and methacrylates, silicone resins, phenoxy resins, polysulfone resins, polyvinyl butyral resins, polyvinyl formal resins, and polyesters. Resins, cellulose ester resins, cellulose ether resins, urethane resins, phenol resins, epoxy resins, polycarbonate resins, polyarylate resins, polyamide resins, polyimide resins, and the like can be used.

Preferred solvents are water, methanol,
Ethanol, alcohol solvents such as isopropyl alcohol, ketone solvents such as acetone, methyl ethyl ketone, or methyl isobutyl ketone, ester solvents such as ethyl formate, ethyl acetate, or n-butyl acetate, diethyl ether, dimethoxyethane, tetrahydrofuran, Ether solvents such as dioxolan or dioxane; N, N-dimethylformamide;
N-dimethylacetamide or N-methyl-2-
Amide solvents such as pyrrolidone, halogenated hydrocarbons such as dichloromethane, chloroform, bromoform, methyl iodide, dichloroethane, trichloroethane, trichloroethylene, chlorobenzene, o-dichlorobenzene, fluorobenzene, bromobenzene, iodobenzene, and 1-chloronaphthalene System solvent, n-pentane, n-hexane, n-octane, 1,5-hexadiene, cyclohexane, methylcyclohexane, cyclohexadiene, benzene, toluene, o-xylene, m-
Examples thereof include hydrocarbon solvents such as xylene, p-xylene, ethylbenzene, and cumene. These can be used alone or as a mixed solvent of two or more.

As a method of applying the obtained dispersion, a roller method, a dipping method, an air knife method, a blade method, a wire bar, a slide hopper method, an extrusion method,
A curtain method, a spin method, or a spray method is preferred.

Further, the semiconductor layer need not be limited to a single layer. It is also possible to apply a multi-layer coating of a dispersion of semiconductor fine particles having different particle diameters, or to apply a multi-layer coating of coating layers having different compositions of semiconductors, resins, and additives of different types. In addition, when the film thickness is insufficient by one application, the multi-layer application is an effective means.

In general, as the film thickness of the semiconductor layer increases, the amount of dye carried per unit projected area also increases, so that the light capture rate increases. However, the diffusion distance of generated electrons also increases, so that charge recombination occurs. Will also increase. Therefore, the thickness of the semiconductor layer is preferably 0.1 to 100 μm, and more preferably 1 to 30 μm.

The semiconductor fine particles may or may not be subjected to a heat treatment after being coated on the conductive support. However, from the viewpoint of improving the electronic contact between the particles and the coating strength and the adhesion to the support, Heat treatment is preferred. The heat treatment temperature at that time is preferably 40 to 700 ° C, and 100 to 60 ° C.
0 ° C. is more preferred. The heat treatment time is 5 minutes to 20 minutes.
Time is preferred, and 10 minutes to 10 hours is more preferred. However, the heat treatment needs to be performed at a temperature below the temperature at which the support is not damaged, and when a polymer film is used for the support, it is not preferable because it causes deterioration.

The semiconductor fine particles preferably have a large surface area so that many dyes can be adsorbed. Therefore, the surface area when the semiconductor layer is coated on the support is preferably at least 10 times, more preferably at least 100 times the projected area.

As the dye in the photoelectric conversion device of the present invention, a dye represented by the general formula (1) is used as a photoelectric conversion material.

As a method of adsorbing a dye on a semiconductor layer, a method of immersing a working electrode containing semiconductor fine particles in a dye solution or a dye dispersion, or applying a dye solution or a dispersion to the semiconductor layer and adsorbing the dye. Can be used. In the former case, dipping, dip, roller,
The air knife method can be used, and in the latter case,
A wire bar method, a slide hopper method, an extrusion method, a curtain method, a spin method, a spray method, and the like can be used.

When the dye is adsorbed, a condensing agent may be used in combination. The condensing agent may be one that acts as a catalyst, which seems to physically or chemically bind the dye to the inorganic surface, or one that acts stoichiometrically to shift the chemical equilibrium advantageously. Further, a thiol or a hydroxy compound may be added as a condensation aid.

Solvents for dissolving the dye include water, alcohol solvents such as methanol, ethanol and isopropyl alcohol, ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, ethyl formate, ethyl acetate and n-butyl acetate. An ester solvent such as diethyl ether, dimethoxyethane, tetrahydrofuran, dioxolan or dioxane; N, N-dimethylformamide;
N, N-dimethylacetamide or N-methyl-
Amide solvents such as 2-pyrrolidone, dichloromethane, chloroform, bromoform, methyl iodide, dichloroethane, trichloroethane, trichloroethylene, chlorobenzene, o-dichlorobenzene, fluorobenzene,
Bromobenzene, iodobenzene, or a halogenated hydrocarbon solvent such as 1-chloronaphthalene, n-pentane, n-hexane, n-octane, 1,5-hexadiene, cyclohexane, methylcyclohexane, cyclohexadiene, benzene, toluene, o-xylene, m-
Examples thereof include hydrocarbon solvents such as xylene, p-xylene, ethylbenzene, and cumene, and these can be used alone or as a mixture of two or more. Is preferred in the present invention.

The temperature at which the dye is adsorbed using these is preferably from -50 ° C to 200 ° C. This adsorption may be performed while stirring. Examples of the method of stirring include a stirrer, a ball mill, a paint conditioner, a sand mill, an attritor, a disperser, and an ultrasonic dispersion.
It is not limited to these. The time required for adsorption is preferably from 5 seconds to 1,000 hours, more preferably from 10 seconds to 500 hours, and more preferably from 1 minute to 150 hours.
Time is more preferred.

As the charge transfer layer of the present invention, an electrolyte in which a redox couple is dissolved in an organic solvent, a gel electrolyte in which a liquid in which a redox couple is dissolved in an organic solvent is impregnated in a polymer matrix, and a molten electrolyte containing a redox couple Salts, solid electrolytes, organic hole transport materials, and the like can be used.

The electrolyte used in the present invention is preferably composed of an electrolyte, a solvent, and additives. Preferred electrolytes include metal iodide-iodine combinations such as lithium iodide, sodium iodide, potassium iodide, cesium iodide and calcium iodide, and tetraalkylammonium iodides, pyridinium iodides and imidazolium iodides. Combination of iodine salt of quaternary ammonium compound-iodine, combination of metal bromide-bromine such as lithium bromide, sodium bromide, potassium bromide, cesium bromide, calcium bromide, and quaternary such as tetraalkylammonium bromide and pyridinium bromide Combination of bromine salt and bromine of ammonium compound, metal complex such as ferrocyanate-ferricyanate, ferrocene-ferricinium ion, sulfur compound such as sodium polysulfide, alkylthiol-alkyldisulfide, viologen Dye, hydroquinone - quinones, and the like. The above-mentioned electrolytes may be a single combination or a mixture. Further, a salt in a molten state at room temperature can be used as the electrolyte. When this molten salt is used, it is not necessary to use a solvent.

The electrolyte concentration in the electrolyte is 0.05 to
20M is preferable, and 0.1-15M is more preferable. Examples of the solvent used for the electrolytic solution include carbonate solvents such as ethylene carbonate and propylene carbonate, heterocyclic compounds such as 3-methyl-2-oxazolidinone, ether solvents such as dioxane, diethyl ether and ethylene glycol dialkyl ether, methanol, and ethanol. Preferred are alcohol solvents such as polypropylene glycol monoalkyl ether, nitrile solvents such as acetonitrile and benzonitrile, and aprotic polar solvents such as dimethyl sulfoxide and sulfolane. Also, t-
Basic compounds such as butylpyridine, 2-picoline and 2,6-lutidine can also be added.

In the present invention, the electrolyte may be gelled by a technique such as addition of a polymer, addition of an oil gelling agent, polymerization containing a polyfunctional monomer, or crosslinking reaction of the polymer. Preferable polymers when gelling by adding a polymer include polyacrylonitrile, polyvinylidene fluoride and the like. Preferred gelling agents when gelling by adding an oil gelling agent include:
Dibenzylden-D-sorbitol, cholesterol derivative, amino acid derivative, trans- (1R, 2R)-
Examples thereof include an alkylamide derivative of 1,2-cyclohexanediamine, an alkylurea derivative, N-octyl-D-gluconamide benzoate, a double-headed amino acid derivative, and a quaternary ammonium derivative.

When polymerizing with a polyfunctional monomer, preferred monomers include divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate,
Examples thereof include triethylene glycol dimethacrylate, pentaerythritol triacrylate, and trimethylolpropane triacrylate. Further, acrylic acid such as acrylamide and methyl acrylate and α-
Esters and amides derived from alkyl acrylic acid, esters derived from maleic acid and fumaric acid such as dimethyl maleate and diethyl fumarate, dienes such as butadiene and cyclopentadiene, styrene and p-
Aromatic vinyl compounds such as chlorostyrene and sodium styrene sulfonate, vinyl esters, acrylonitrile, methacrylonitrile, vinyl compounds having a nitrogen-containing heterocyclic ring, vinyl compounds having a quaternary ammonium salt, N
-Monofunctional monomers such as vinyl formamide, vinyl sulfonic acid, vinylidene fluoride, vinyl alkyl ethers, and N-phenylmaleimide may be contained. The polyfunctional monomer in the total amount of the monomer is 0.5 to 70.
% By mass is preferable, and 1.0 to 50% by mass is more preferable.

The above monomers can be polymerized by radical polymerization. The monomer for gel electrolyte that can be used in the present invention can be subjected to radical polymerization by heating, light, electron beam or electrochemically. The polymerization initiator used when the crosslinked polymer is formed by heating is 2,2.
'-Azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl-2,
An azo initiator such as 2'-azobis (2-methylpropionate) and a peroxide initiator such as benzoyl peroxide are preferred. The addition amount of these polymerization initiators is preferably 0.01 to 20% by mass based on the total amount of the monomers,
0.1-10 mass% is more preferable.

When the electrolyte is gelled by a crosslinking reaction of the polymer, it is desirable to use a polymer containing a reactive group necessary for the crosslinking reaction and a crosslinking agent together. Preferred examples of the crosslinkable reactive group include nitrogen-containing heterocycles such as pyridine, imidazole, thiazole, oxazole, triazole, morpholine, piperidine, and piperazine.Preferred crosslinking agents include alkyl halides and halogens. Bifunctional or more functional reagents capable of electrophilic reaction with nitrogen atoms, such as aralkyl fluoride, sulfonic acid ester, acid anhydride, acid chloride, and isocyanate.

When an inorganic solid compound is used instead of the electrolyte, copper iodide, copper thiocyanate, or the like can be introduced into the electrode by a method such as a casting method, a coating method, a spin coating method, an immersion method, and electrolytic plating. .

In the present invention, an organic charge transporting substance can be used instead of the electrolyte. The charge transport materials include a hole transport material and an electron transport material. As an example of the former,
For example, oxadiazoles disclosed in JP-B-34-5466, triphenylmethanes disclosed in JP-B-45-555, and JP-B-52-4188.
Pyrazolines shown in Japanese Patent Publication No. 55-4, for example,
Hydrazones disclosed in JP-A-2380, etc., oxadiazoles disclosed in JP-A-56-123544, etc., tetraarylbenzidines disclosed in JP-A-54-58445, and the like. 58-544
And stilbenes described in JP-A No. 0, JP-A-60-98437 and the like. Among them, examples of the charge transporting material used in the present invention include JP-A-60-24553, JP-A-2-96767, JP-A-2-183260, and JP-A-2-183260.
Hydrazones disclosed in JP-A-226160, JP-A-2-51162, and JP-A-3-7566
The stilbenes disclosed in Japanese Patent Publication No. 0 are particularly preferred.
These can be used alone or as a mixture of two or more.

On the other hand, examples of the electron transporting substance include chloranil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone,
2,4,5,7-tetranitro-9-fluorenone,
2,4,5,7-tetranitroxanthone, 2,4,8
-Trinitrothioxanthone, 1,3,7-trinitrodibenzothiophene, and 1,3,7-trinitrodibenzothiophene-5,5-dioxide. These electron transporting substances can be used alone or as a mixture of two or more.

Further, a certain kind of electron-withdrawing compound can be added as a sensitizer for further increasing the sensitizing effect. Examples of the electron-withdrawing compound include quinones such as 2,3-dichloro-1,4-naphthoquinone, 1-nitroanthraquinone, 1-chloro-5-nitroanthraquinone, 2-chloroanthraquinone, and phenanthrenequinone; Aldehydes such as benzaldehyde, 9
-Benzoylanthracene, indandione, 3,5-
Dinitrobenzophenone or 3,3 ', 5,5'
Ketones such as tetranitrobenzophenone, acid anhydrides such as phthalic anhydride and 4-chloronaphthalic anhydride, terephthalalmalononitrile, 9-anthrylmethylidenemalononitrile, 4-nitrobenzalmalonitrile, or 4- (P-nitrobenzoyloxy) cyano compound such as benzalmalononitrile, 3-benzalphthalide, 3- (α-cyano-p-nitrobenzal) phthalide, or 3- (α-cyano-p-nitrobenzal)
And phthalides such as -4,5,6,7-tetrachlorophthalide.

When a charge transfer layer is formed using these charge transporting materials, it is preferable to use a resin together, and a polystyrene resin, a polyvinyl acetal resin, a polysulfone resin, a polycarbonate resin, a polyester resin, a polyphenylene oxide resin, and a polyarylate resin are preferably used. Acryl resin, methacrylic resin, phenoxy resin and the like. Among them, polystyrene resin, polyvinyl acetal resin, polycarbonate resin, polyester resin and polyarylate resin are excellent. These resins can be used alone or as a mixture of two or more of them as a copolymer.

Among these resins, tension, bending,
Some have weak mechanical strength such as compression. To improve this property, substances which impart plasticity can be added. Specifically, phthalic acid esters (for example, DOP, DOP
BP, etc.), phosphate esters (eg, TCP, TOP
Etc.), sebacic esters, adipic esters, nitrile rubbers, chlorinated hydrocarbons and the like. If these substances are added more than necessary, the properties are adversely affected. Therefore, the ratio is preferably 20% or less based on the binder resin. In addition, an antioxidant, an anti-curl agent and the like can be added as needed.

The amount of the resin used is preferably from 0.001 to 20 parts by mass per 1 part by mass of the charge transporting material,
1 to 5 parts by mass or less is more preferable. If the ratio of the resin is too high, the sensitivity is lowered, and if the ratio of the resin is too low, the repetition characteristics may be deteriorated or the coating film may be damaged.

There are roughly two methods for forming the charge transfer layer. One is a method in which a counter electrode is first stuck on a semiconductor fine particle-containing layer carrying a sensitizing dye, and a liquid charge transfer layer is sandwiched in the gap. The other is a method in which a charge transfer layer is provided directly on the semiconductor fine particle-containing layer. In this case, the counter electrode will be newly provided thereafter.

In the former case, as a method of sandwiching the charge transfer layer, there are a normal pressure process utilizing a capillary phenomenon by immersion or the like and a vacuum process wherein the gas phase is replaced with a liquid phase at a pressure lower than the normal pressure. In the latter case, it is necessary to provide a counter electrode in the wet type charge transfer layer while keeping it undried to prevent the edge portion from leaking liquid. Further, in the case of a gel electrolyte, there is a method of applying the composition by a wet method and solidifying it by a method such as polymerization. In that case, a counter electrode may be provided after drying and fixing. In addition to the electrolytic solution, a method of applying a solution of an organic charge transporting material or a gel electrolyte includes a dipping method, a roller method, a dipping method, an air knife method, and an extrusion method, as in the case of applying a layer containing semiconductor fine particles and applying a dye. , Slide hopper method, wire bar method, spin method, spray method,
Examples include a casting method and various printing methods.

As the counter electrode, a support having a conductive layer can be used as in the case of the above-described conductive support. However, the support is not necessarily required in a configuration in which the strength and the sealing property are sufficiently maintained. . As a specific example of the material used for the counter electrode,
Examples include metals such as platinum, gold, silver, copper, aluminum, rhodium, and indium, and conductive metal oxides such as carbon, ITO, and FTO. There is no limitation on the thickness of the counter electrode.

In order for light to reach the photosensitive layer, at least one of the conductive support and the counter electrode described above must be substantially transparent. In the photoelectric conversion element of the present invention, a method in which the conductive support is transparent and sunlight is incident from the support side is preferable. In this case, a material that reflects light is preferably used for the counter electrode, and a metal, glass, plastic, or a metal thin film on which a conductive oxide is deposited is preferable.

As described above, the counter electrode is applied on the charge transfer layer in two ways, that is, on the semiconductor fine particle layer. In any case, depending on the type of the counter electrode material and the type of the charge transfer layer, the counter electrode material can be appropriately formed on the charge transfer layer or the semiconductor fine particle-containing layer by a method such as application, lamination, vapor deposition, and bonding. Also,
When the charge transfer layer is solid, the counter electrode can be formed directly on the charge transfer layer by a method such as coating, vapor deposition, or CVD.

[0056]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 3 g of titanium oxide (P-25 manufactured by Nippon Aerosil Co., Ltd.), 0.2 g of acetylacetone, and a surfactant (manufactured by Aldrich Co.)
0.3 g of Triton X-100) was dispersed with 6.5 g of water in a paint conditioner for 6 hours. This dispersion was coated on an FTO glass substrate using a wire bar to a film thickness of 10
It was applied to a thickness of μm. After the application, the coating was dried at 100 ° C. for 1 hour, and then baked in air at 450 ° C. for 30 minutes.

The dye 0.0 represented by the exemplified compound (A-3)
5 g was dissolved in 50 ml of ethanol. The semiconductor electrode prepared above was immersed in this solution at room temperature for 15 hours to perform an adsorption treatment.

As the electrolytic solution, a solution prepared by dissolving 0.03 M of iodine and 0.5 M of tetra-n-propylammonium iodide in a mixed solution of propylene carbonate / acetonitrile = 6/4 was used. For the counter electrode, a sputtered platinum on FTO was used.

An electrolyte was immersed between the two electrodes to produce a photoelectric conversion element. Here, light of 400 nm or less was cut from the working electrode side with a cut filter UV-39 made by Toshiba.
A xenon lamp having an intensity of 0 mW / cm ² was irradiated. As a result, the open circuit voltage was 0.62 V, and the short circuit current density was 6.5 mA / c.
m ² , a shape factor of 0.58, and a conversion efficiency of 2.34% were good values.

Examples 2 to 9 Except that the exemplified compound (A-3) was changed to the dyes shown in Table 1, devices were prepared and evaluated in the same manner as in Example 1. Table 1 shows the results.

[0062]

[Table 1]

As can be seen from the results shown in Table 1, the dyes of the present invention show good conversion efficiency.

[0064]

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Comparative Example 1 A device was prepared and evaluated in the same manner as in Example 1 except that the exemplified compound (A-3) was changed to the compound shown in (6). As a result, the open-circuit voltage was 0.48 V and the short-circuit current density was 2.
3 mA / cm ² , form factor 0.33, conversion efficiency 0.36
%.

[0066]

As is clear from the above, according to the present invention, a photoelectric conversion element having good conversion efficiency can be provided.

Claims (1)

[Claims] 1. A photoelectric conversion element characterized in that at least one dye represented by the following general formula (1) is used as a photoelectric conversion material. Embedded image (In the general formula (1), R ₁ represents a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an alkylthio group, or a heterocyclic residue, each of which may have a substituent.
R ₂ represents an alkyl group, which may have a substituent.
R _{3 to} R _{6 each} represent a hydrogen atom, an alkyl group, an alkoxy group, an alkylthio group, an aryl group, or a heterocyclic residue, each of which may have a substituent. R ₇ and R ₈ each represent a substituent having an acidic group. Part A and part B represent a carbonyl group and R ₇
Or showing a heterocyclic ring to form a 5- to 7-membered ring together with the amino group for substituting R _8. X ₁ represents an oxygen atom or a sulfur atom; X ₂ represents an oxygen atom, a sulfur atom, a dicyanomethylene group,
Shows a cyanoacetic acid group. n represents an integer of 0 to 2;
2 to 2. The carbon-carbon double bond may be either E-type or Z-type. )