JP2006134649A - Photoelectric conversion element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To develop an inexpensive photoelectric conversion element and a solar cell using semiconductor fine particles sensitized by dye and having high conversion efficiency. <P>SOLUTION: The photoelectric conversion element uses oxide semiconductor fine particles sensitized by mechine family dye represented by formula (1) or its salt. In the formula (1), n represents an integer of 1-7; X represents an oxygen atom, a sulfur atom, and a selenium atom; Y represents an aromatic residue which may have a substituent, or an organic metal complex residue which may have a substituent; and A<SB>1</SB>and A<SB>2</SB>independently represent a hydrogen atom, a hydroxyl group, a phosphoric group, a cyano group, a halogen atom, or the like. When n is 2 or more and A<SB>1</SB>and A<SB>2</SB>are plurally present, A<SB>1</SB>and A<SB>2</SB>may be the same or different. A<SB>1</SB>and A<SB>2</SB>in the number of n each are constituted with 2 or more A<SB>1</SB>and/or A<SB>2</SB>, and may form 1 or more rings which may have a substituent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photoelectric conversion element and a solar cell sensitized with an organic dye, and in particular, a photoelectric conversion element using oxide semiconductor fine particles sensitized with a dye having a specific skeleton, and the same It relates to solar cells.

  Solar cells that use sunlight as an energy resource to replace fossil fuels such as oil and coal are drawing attention. Currently, development studies such as high efficiency are being conducted on silicon solar cells using crystalline or amorphous silicon, or compound semiconductor solar cells using gallium, arsenic, or the like. However, there is a problem that they are difficult to use for general purposes because of the high energy and cost required for production. A photoelectric conversion element using semiconductor fine particles sensitized with a dye or a solar cell using the same is also known, and a material and a manufacturing technique for producing the photoelectric conversion element are disclosed. (Refer to Patent Document 1, Non-Patent Document 1, and Non-Patent Document 2) This photoelectric conversion element is manufactured using a relatively inexpensive oxide semiconductor such as titanium oxide, and compared with a conventional solar cell using silicon or the like. There is a possibility that a low-cost photoelectric conversion element can be obtained, and a colorful solar cell can be obtained. However, ruthenium-based complexes are used as sensitizing dyes in order to obtain devices with high conversion efficiency, and the cost of the dyes themselves is high, and problems still remain in their supply. Attempts have also been made to use organic dyes as sensitizing dyes, but the current situation is that conversion efficiency, stability and durability have not yet been put into practical use. Is desired (see Patent Document 2). In addition, examples of producing photoelectric conversion elements using methine dyes have been mentioned so far, and coumarin dyes (see Patent Document 3) and merocyanine dyes have relatively many studies (Patent Documents). 4, 5 and 6), further cost reduction, improvement in stability and conversion efficiency have been desired.

Japanese Patent No. 2664194 WO2002011213 JP 2002-164089 A JP-A-8-81222 JP-A-11-214731 JP 2001-52766 A B.O'Regan and M.Graetzel Nature, 353, 737 (1991) MKNazeeruddin, A. Kay, I. Rodicio, R. Humphry-Baker, E. Muller, P. Liska, N. Vlachopoulos, M. Graetzel, J. Am. Chem. Soc., 115, 6382 (1993 Year) W. Kubo, K. Murakoshi, T. Kitamura, K. Hanabusa, H. Shirai, and S. Yanagida, Chem. Lett., P. 1241 (1998)

  In photoelectric conversion elements using organic dye-sensitized semiconductors, development of photoelectric conversion elements that are inexpensive and have high stability, high conversion efficiency, and high practicality is demanded.

  As a result of diligent efforts to solve the above-mentioned problems, the present inventors have sensitized semiconductor fine particles using a specific dye and created a photoelectric conversion element to achieve stability (as a dye-sensitized photoelectric conversion element). The inventors have found that a photoelectric conversion element having excellent stability over time and high conversion efficiency can be obtained, and the present invention has been completed.

That is, the present invention provides (1) a photoelectric conversion element characterized by using oxide semiconductor fine particles sensitized with a methine dye represented by formula (1) or a salt thereof,

(In formula (1), n represents an integer of 1 to 7. X represents an oxygen atom, a sulfur atom or a selenium atom. Y represents an aromatic residue which may have a substituent, or a substituent. A ₁ and A ₂ each independently represents an aromatic residue which may have a hydrogen atom, a hydroxyl group, a phosphate group, a cyano group, a halogen atom or a substituent. Represents an aliphatic hydrocarbon residue which may have a substituent, a carboxyl group, a carbonamido group, an alkoxycarbonyl group, an arylcarbonyl group, a sulfonylbenzene group or an acyl group, wherein n is 2 or more and A ₁ and A _2. Are present, each A ₁ and each A ₂ may be the same or different from each other, and n present A ₁ and A ₂ are two or more A ₁ and / or A ₂ . 1 to 2 or more which may be configured and have a substituent It may form a ring.)
(2) The photoelectric conversion element according to (1), wherein Y in the formula (1) is a group represented by the following formula (2):

(In the formula (2), R ₁ and R ₂ are each a hydrogen atom, an aromatic residue optionally having a substituent, an aliphatic hydrocarbon residue optionally having a substituent, or an acyl group. R ₁ and R ₂ may be bonded to each other or a benzene ring A to form a ring which may have a substituent, and the benzene ring A is a halogen atom, an amide group, a hydroxyl group or a cyano group. Nitro group, alkoxyl group, carboxyl group, acyl group, alkoxycarbonyl group, substituted or unsubstituted amino group, aromatic residue optionally having substituent and aliphatic carbonization optionally having substituent It may have one or more substituents selected from the group consisting of hydrogen residues, and when there are a plurality of substituents, those substituents may be bonded to each other to have a substituent. A good ring may be formed.)
(3) The photoelectric conversion element according to (1) or (2), wherein X in formula (1) is an oxygen atom,
(4) The photoelectric conversion element according to any one of (1) to (3), wherein n in Formula (1) is 1 to 5.
(5) Use of oxide semiconductor fine particles sensitized with one or more methine dyes represented by the formula (1) or a salt thereof and a metal complex and / or an organic dye having a structure other than the formula (1). Photoelectric conversion element,
(6) The photoelectric conversion element according to any one of (1) to (5), wherein the oxide semiconductor fine particles contain titanium dioxide, zinc oxide, or tin oxide.
(7) An oxide semiconductor fine particle sensitized by a methine dye or a salt thereof is obtained by supporting a methine dye or a salt thereof represented by the formula (1) in the presence of an inclusion compound in the oxide semiconductor fine particle. The photoelectric conversion element according to any one of (1) to (6),
(8) Any one of (1) to (7), wherein the oxide semiconductor fine particles sensitized with a methine dye or a salt thereof are obtained by supporting the dye on a thin film of oxide semiconductor fine particles. The photoelectric conversion element according to
(9) A solar cell using the photoelectric conversion element according to any one of (1) to (8),
About

By using a dye having a specific partial structure in the dye-sensitized photoelectric conversion element of the present invention, a solar cell having high conversion efficiency and high temporal stability could be provided. Furthermore, the conversion efficiency was further improved by using oxide semiconductor fine particles sensitized by the combined use of two or more dyes.

The present invention is described in detail below. The photoelectric conversion element of the present invention uses an oxide semiconductor sensitized with a methine dye represented by the following formula (1) or a salt thereof.

N in Formula (1) represents an integer of 1 to 7, preferably 1 to 6, and particularly preferably 1 to 5.
X in Formula (1) represents an oxygen atom, a sulfur atom, and a selenium atom, and is preferably an oxygen atom.
Y in Formula (1) represents an aromatic residue which may have a substituent and an organometallic complex residue which may have a substituent.

  In the above, the aromatic group in the “aromatic residue optionally having a substituent” means a group obtained by removing one hydrogen atom from an aromatic ring, and examples of the aromatic ring include benzene, naphthalene, and anthracene. , Aromatic hydrocarbon rings such as phenanthrene, pyrene, perylene, terylene, indene, azulene, pyridine, pyrazine, pyrimidine, pyrazole, pyrazolidine, thiazolidine, oxazolidine, pyran, chromene, pyrrole, pyrrolidine, benzimidazole, imidazoline, imidazolidine, Imidazole, pyrazole, triazole, triazine, diazole, indoline, thiophene, thienothiophene, furan, oxazole, oxadiazole, thiazine, thiazole, indole, benzothiazole, benzothiadiazole, naphthothi Examples thereof include heterocyclic aromatic rings such as sol, benzoxazole, naphthoxazole, indolenine, benzoindolenine, pyrazine, quinoline, coumarin, and quinazoline, and condensed aromatic rings such as fluorene and carbazole. An aromatic residue having an aromatic ring (an aromatic ring and a condensed ring including an aromatic ring) is preferable.

In addition, in the above, the organometallic complex residue in the “optionally substituted organometallic complex residue” means a group obtained by removing one hydrogen atom from an organometallic complex. For example, a metal-containing porphyrin complex (iron-containing copper, aluminum, cobalt, nickel, ruthenium, iridium, metal-containing porphyrin mainly containing silver, titanium, and silicon), a phthalocyanine complex (iron, copper, aluminum, cobalt, nickel, ruthenium) Phthalocyanine having iridium, silver, titanium and silicon as central metals), bipyridyl complexes (ruthenium, oxonium, complexes of iridium and [2,2 ′] bipyridyl), ferrocene, ruthenocene, titanocene, zirconocene and the like.

The substituent in the “aromatic residue which may have a substituent” and the “organic metal complex residue which may have a substituent” is not particularly limited, but a sulfonic acid group, a sulfamoyl group , Cyano group, isocyano group, thiocyanato group, isothiocyanato group, nitro group, nitrosyl group, halogen atom, hydroxyl group, phosphate group, phosphate ester group, substituted or unsubstituted amino group, optionally substituted mercapto group, Amido group which may be substituted, alkoxy group which may have substituent, aryloxy group which may have substituent, carboxyl group, carbamoyl group, acyl group, aldehyde group, alkoxycarbonyl group, etc. A substituted carbonyl group, an aromatic residue which may have a substituent, an aliphatic hydrocarbon residue which may have a substituent, and the likeExamples of the halogen atom include atoms such as fluorine, chlorine, bromine and iodine. Examples of the phosphoric acid ester group include phosphoric acid (having 1 to 4 carbon atoms) alkyl ester groups. Examples of substituted or unsubstituted amino groups include amino groups, mono- or dimethylamino groups, mono- or diethylamino groups, alkyl-substituted amino groups such as mono- or dipropylamino groups, mono- or diphenylamino groups, mono- or dinaphthylamino groups, etc. Examples include an amino group or benzylamino group in which an alkyl group such as an aromatic substituted amino group and a monoalkylmonophenylamino group and an aromatic hydrocarbon residue are substituted one by one, an acetylamino group, and a phenylacetylamino group. Examples of the mercapto group which may be substituted include a mercapto group, an alkyl mercapto group, and a phenyl mercapto group. Examples of the amide group that may be substituted include an amide group, an alkylamide group, and an arylamide group. The alkoxy group means a group formed by the bond of the following aliphatic hydrocarbon residue and an oxygen atom, and examples thereof include a methoxy group, an ethoxy group, a butoxy group, a tert-butoxy group, and the like. Examples of the aryloxy group which may have a phenoxy group include a phenoxy group and a naphthoxy group, and these may have a phenyl group or a methyl group as a substituent. The substituent may be the same as that described in the section of the aromatic residue which may have a substituent. Examples of the acyl group include an alkylcarbonyl group having 1 to 10 carbon atoms, an arylcarbonyl group, and the like, and preferably an alkylcarbonyl group having 1 to 4 carbon atoms, specifically an acetyl group, a trifluoromethylcarbonyl group, a pentane group. A fluoroethylcarbonyl group, a propionyl group, etc. are mentioned. Examples of the alkoxycarbonyl group include an alkoxycarbonyl group having 1 to 10 carbon atoms. The aromatic residue which may have a substituent may be the same as described above.

In the above, the aliphatic hydrocarbon residue in the “optionally substituted aliphatic hydrocarbon residue” includes saturated and unsaturated linear, branched and cyclic alkyl groups, and carbon The number is preferably 1 to 36, more preferably one having 1 to 20 carbon atoms. Examples of cyclic compounds include cycloalkyl having 3 to 8 carbon atoms. Specific examples include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, ter-butyl group, octyl group, octadecyl group, isopropyl group, cyclohexyl group, propenyl. Group, pentynyl group, butenyl group, hexenyl group, hexadienyl group, isopropenyl group, isohexenyl group, cyclohexenyl group, cyclopentadienyl group, ethynyl group, propynyl group, pentynyl group, hexynyl group, isohexynyl Group, cyclohexynyl group and the like.

The substituent in the “aliphatic hydrocarbon residue which may have a substituent” is not particularly limited, but the above “aromatic residue which may have a substituent” and “having a substituent”. It may be the same as the substituent in the “organic metal complex residue that may be used”.
A ₁ and A ₂ in formula (1) each independently have an aromatic residue which may have a substituent, a hydroxyl group, a phosphate group, a cyano group, a hydrogen atom, a halogen atom, or a substituent. And may represent an aliphatic hydrocarbon residue, a carboxyl group, a carbonamido group, an alkoxycarbonyl group, an arylcarbonyl group, a sulfonylbenzene group or an acyl group. An aromatic residue optionally having a substituent, a halogen atom, an aliphatic hydrocarbon residue optionally having a substituent, an alkoxycarbonyl group, an arylcarbonyl group, and an acyl group, It may be the same as that shown in the section of the substituent in the “aromatic residue optionally having” and the “organic metal complex residue optionally having substituent”.

When n is 2 or more and a plurality of A ₁ and A ₂ are present, each A ₁ and each A ₂ may be the same or different from each other independently. Preferably, A ₁ and A ₂ are independently a hydrogen atom, a cyano group, an aliphatic hydrocarbon residue and a halogen atom. The aliphatic hydrocarbon residue and the halogen atom may be the same as described above. In addition, when A ₂ in formula (1), particularly n is 2 or more, A ₂ closest to Y is preferably an aromatic residue which may have a substituent. The aromatic residue may be the same as described above, and is preferably a residue such as benzene, naphthalene, anthracene, thiophene, pyrrole, furan or coumarin. These aromatic residues may have a substituent as described above. The substituent is not particularly limited, and may be the same as that described in the section of the aromatic residue which may have a substituent, and may have a substituted or unsubstituted amino group and a substituent. It is preferably an aromatic residue.

Further, n existing A ₁ and A ₂ may be composed of two or more A ₁ and / or A ₂ , and may form one or more rings which may have a substituent. In particular, when a plurality of A ₁ or A ₁ are present, each A ₁ and A ₂ or A ₂ is present when each A ₂ is a combination of A ₁ and A ₂ , It is preferable to form a ring which may have, and examples of the ring to be formed include an unsaturated hydrocarbon ring or a heterocyclic ring. Examples of the unsaturated hydrocarbon ring include a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, pyrene ring, indene ring, azulene ring, fluorene ring, cyclobutene ring, cyclohexene ring, cyclopentene ring, cyclohexadiene ring, and cyclopentadiene ring. The heterocyclic ring includes thiophene ring, pyrrole ring, pyridine ring, pyrazine ring, piperidine ring, indoline ring, furan ring, pyran ring, oxazole ring, thiazole ring, indole ring, benzothiazole ring, benzoxazole ring, quinoline ring , Carbazole ring, benzopyran ring and the like. Of these, preferred are a benzene ring, a cyclobutene ring, a cyclopentene ring, a cyclohexene ring, a pyran ring, and a furan ring. As mentioned above, these may have a substituent, and the substituent in the aromatic residue which may have the substituent and the organometallic complex residue which may have a substituent. It may be the same as described in the section of the substituent. Moreover, when it has a carbonyl group, a thiocarbonyl group, etc., a cyclic ketone or a cyclic thioketone may be formed, and these rings may also have a substituent. The substituent may be the same as that described in the section of the substituent in the above “aromatic residue optionally having substituent” and “organometallic complex residue optionally having substituent”. .

Furthermore, when the above-described Y is a heterocyclic aromatic ring having a nitrogen atom, a condensed aromatic ring and / or a heterocyclic ring formed of Y and A ₁ and A ₂ has a nitrogen atom, the nitrogen atom is quaternized. And may have a counter ion at that time. Although it does not specifically limit specifically, a normal anion may be sufficient. Specific examples of counter ions capable of forming a salt include F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , OH ⁻ , SO ₄ ²⁻ , CH ₃ SO ₄ ⁻ , N (CN) ²⁻ , N (SO ₂ CF ₃ ) ²⁻ , CF ₃ SO ₄ ⁻ , toluenesulfonic acid ion, and the like can be mentioned. Br ⁻ , I ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CH ₃ SO ₄ ⁻ , N (CN) ²⁻ , N (SO ₂ CF ₃ ) ²⁻ , CF ₃ SO ₄ ⁻ , toluenesulfonate ion, and the like are preferable. Moreover, you may neutralize by acidic groups, such as a carboxyl group in a molecule | numerator or between molecules instead of a counter ion.

In addition, the carboxyl group in the methine dye represented by the formula (1) or a salt thereof, and the heterocycle formed by Y and A ₁ and A ₂ is acidic such as hydroxyl group, phosphate group, sulfonate group and carboxyl group. Each having a group as a substituent, each may form a salt, for example, a salt with an alkali metal or alkaline earth metal such as lithium, sodium, potassium, magnesium, calcium, or an organic base such as Examples thereof include salts such as quaternary ammonium salts such as tetramethylammonium, tetrabutylammonium, pyridinium, imidazolium, piperazinium and piperidinium.

Moreover, it is preferable that Y in Formula (1) is group represented by following formula (2).

R ₁ and R ₂ in Formula (2) each represent a hydrogen atom, an aromatic residue that may have a substituent, an aliphatic hydrocarbon residue that may have a substituent, and an acyl group. The aromatic residue which may have a substituent and the aliphatic hydrocarbon residue which may have a substituent may be the same as described above. The acyl group may be the same as that shown in the section of the substituent in the above “aromatic residue optionally having substituent” and “organometallic complex residue optionally having substituent”. R ₁ and R ₂ may be bonded to each other or the benzene ring A to form a ring that may have a substituent. Examples of the ring formed by combining R ₁ and R ₂ include a morpholine ring, piperidine ring, piperazine ring, pyrrolidine ring, carbazole ring, and indole ring. Examples of the ring formed by combining R ₁ and R ₂ with the benzene ring A include an indole ring and a julolidine ring. These may have a substituent as described above. The substituent may be the same as described in the paragraph of the substituent in the aromatic residue which may have the substituent and the organometallic complex residue which may have a substituent.

Ring A in formula (2) has a halogen atom, an amide group, a hydroxyl group, a cyano group, a nitro group, an alkoxyl group, a carboxyl group, an acyl group, an alkoxycarbonyl group, a substituted or unsubstituted amino group, and a substituent. May have one or two or more substituents selected from the group consisting of an aromatic residue which may optionally be substituted and an aliphatic hydrocarbon residue which may have a substituent, and a plurality of substituents When present, these substituents may be bonded to each other to form a ring which may have a substituent. The ring which may have a substituent may be the same as those described as the examples of the unsaturated hydrocarbon ring or heterocyclic ring, such as benzene ring, naphthalene ring, oxazole ring, thiazole ring, thiophene ring, furan ring and pyrrole. A ring is preferred.

  The compound represented by the formula (1) may take a structural isomer such as a cis isomer, a trans isomer or a racemate, but is not particularly limited, and any isomer can be used favorably as a photosensitizing dye. is there.

The methine dye represented by the formula (1) can be produced by, for example, the reaction formula shown below. First, the aromatic ring and the organometallic complex in the above “aromatic residue optionally having substituent” and “organometallic complex residue optionally having substituent” represented by the formula (3) are butyl. After metallizing with a base such as lithium, compound (1) can be produced by a method of reacting an amide derivative such as dimethylformamide or a method of reacting with a Vilsmeier reagent in which phosphoryl chloride or the like is reacted with dimethylformamide or the like. The precursor compound (4) is obtained. When n is 2 or more, a method of Claisen condensation of a formyl group or the like, a method of using an amide derivative such as dimethylaminoacrolein or dimethylaminovinylacrolein, a formyl group or the like is converted into a vinyl group or the like by a Wittig reaction or a Grignard reaction, etc. Furthermore, it can be obtained as a propenal group, a pentadienal group, or the like by performing the formylation reaction or the like. Further, if necessary, the compound (4) and the compound (5) having active methylene, if necessary, in the presence of a basic catalyst such as caustic soda, sodium methylate, sodium acetate, diethylamine, triethylamine, piperidine, piperazine, diazabicycloundecene, In alcohols such as methanol, ethanol, isopropanol and butanol, aprotic polar solvents such as dimethylformamide and N-methylpyrrolidone, and solvents such as toluene and acetic anhydride, condensation is carried out at 20 to 180 ° C., preferably 50 to 150 ° C. By doing so, the methine dye of formula (1) is obtained. For those which are difficult to proceed with reaction, an active methylene compound having a carboxyl group as an alkoxycarbonyl group is reacted with the compound (4), and then the alkoxycarbonyl group is hydrolyzed to obtain a methine dye of the formula (1). It is also possible.
Further, as described above, the carboxyl group in the general formula (1) may form a salt with an alkali metal, an alkaline earth metal, an organic base, or the like. As a method for forming a salt, for example, a solution (A) in which a methine dye (free acid) represented by the general formula (1) is dissolved in an alcohol such as methanol or ethanol is prepared, and then an alkali metal or alkali is used. Aqueous solutions or organic bases in which earth metal halides (salts) are dissolved in water, such as tetramethylammonium, tetrabutylammonium, pyridinium, imidazolium, piperazinium, piperidinium halides (salts) Alternatively, a solution (B) dissolved in the same alcohol as described above is prepared. The solution (B) is added to the solution (A) and concentrated if necessary (as a carboxylate in which the hydrogen atom at the terminal of the carboxyl group and the alkali metal, alkaline earth metal or organic base are exchanged). It is possible to obtain a salt of a system dye as a crystal.

Specific examples of methine dyes or salts thereof that can be used in the present invention are shown below.
Specific examples of the dye represented by the following formula (6) are shown in Tables 1 and 2 as examples of the methine dye or the salt thereof represented by the formula (1) in the present invention. In Tables 1 and 2, the phenyl group is abbreviated as Ph.

  Specific examples of the dye represented by the following formula (7) are shown in Tables 3 to 4 as examples of the methine dye or the salt thereof represented by the formula (1) in the present invention. In Tables 3 to 4, the phenyl group is abbreviated as Ph.

  Other examples of the methine dye represented by the formula (1) or a salt thereof are shown below.

In the dye-sensitized photoelectric conversion element of the present invention, for example, a thin film of an oxide semiconductor is produced on a substrate using fine oxide semiconductor particles, and then the methine dye of formula (1) or a salt thereof is supported on the thin film. It is a thing.
In the present invention, the substrate on which the oxide semiconductor thin film is provided is preferably one having a conductive surface, but such a substrate is readily available in the market. Specifically, for example, conductive metal oxide such as tin oxide doped with indium, fluorine or antimony on the surface of glass or the surface of a transparent polymer material such as polyethylene terephthalate or polyether sulfone, copper, silver, etc. A film provided with a metal thin film such as gold can be used. The conductivity is usually 1000Ω or less, particularly preferably 100Ω or less.
The oxide semiconductor fine particles are preferably metal oxides, and specific examples thereof include oxides of titanium, tin, zinc, tungsten, zirconium, gallium, indium, yttrium, niobium, tantalum, vanadium, and the like. Of these, oxides such as titanium, tin, zinc, niobium, and indium are preferable, and among these, titanium oxide, zinc oxide, and tin oxide are most preferable. These oxide semiconductors can be used alone, but can also be used by mixing or coating the surface of the semiconductor. The average primary particle size of the oxide semiconductor fine particles is usually 1 to 500 nm, preferably 1 to 200 nm, and more preferably 1 to 100 nm. The oxide semiconductor fine particles may be mixed with a large particle size and a small particle size, or may be used in multiple layers.

  An oxide semiconductor thin film is a method in which oxide semiconductor fine particles are directly thinned on a substrate by spray spraying, a method of forming as a film of semiconductor fine particles such as a slurry of semiconductor fine particles or semiconductor alkoxide, and a semiconductor fine particle thin film electrically using the substrate as an electrode. The paste containing fine particles obtained by precipitating and hydrolyzing the precursor is coated on a substrate, and then dried, cured, or baked. In view of the performance of the oxide semiconductor electrode, a method using a slurry is preferable. In the case of this method, the average primary particle diameter of the slurry is usually 1 to 500 nm, preferably 1 to 200 nm, more preferably 1 to 100 nm in the dispersion medium of the oxide semiconductor fine particles that are secondary agglomerated by a conventional method. Thus, it is obtained by dispersing.

  The dispersion medium for dispersing the slurry may be anything as long as it can disperse the semiconductor fine particles. Water, alcohols such as ethanol, ketones such as acetone and acetylacetone, and hydrocarbons such as hexane are used. In addition, the use of water is preferable in terms of reducing the change in viscosity of the slurry. A dispersion stabilizer can be used for the purpose of stabilizing the dispersion state of the oxide semiconductor fine particles. Examples of the dispersion stabilizer that can be used include acids such as acetic acid, hydrochloric acid, and nitric acid, or acetylacetone, acrylic acid, polyethylene glycol, polyvinyl alcohol, and the like.

  The substrate coated with the slurry may be fired, and the firing temperature is usually 100 ° C. or higher, preferably 200 ° C. or higher, and the upper limit is generally lower than the melting point (softening point) of the base material. Yes, preferably 600 ° C. or lower. The firing time is not particularly limited but is preferably within 4 hours. The thickness of the thin film on a board | substrate is 1-200 micrometers normally, Preferably it is 1-50 micrometers.

  A secondary treatment may be performed on the oxide semiconductor thin film. That is, for example, the performance of the semiconductor thin film can be improved by immersing the thin film together with the substrate directly in a solution of the same metal alkoxide, chloride, nitride, sulfide, etc. as the semiconductor and drying or refiring. Examples of the metal alkoxide include titanium ethoxide, titanium isopropoxide, titanium t-butoxide, n-dibutyl-diacetyltin, and alcohol solutions thereof are used. Examples of the chloride include titanium tetrachloride, tin tetrachloride, zinc chloride and the like, and an aqueous solution thereof is used. The oxide semiconductor thin film thus obtained is composed of fine particles of an oxide semiconductor.

Next, a method for supporting a dye on an oxide semiconductor thin film will be described. As a method for supporting the methine dye of the above formula (1) or a salt thereof, a solution obtained by dissolving the dye in a solvent capable of dissolving the compound, or a dye having a low solubility is dispersed. The method of immersing the board | substrate with which the said oxide semiconductor thin film was provided in the disperse | distributed liquid obtained by mentioning. The concentration in the solution or dispersion is appropriately determined depending on the dye. The semiconductor thin film prepared on the substrate is immersed in the solution. The immersion time is generally from room temperature to the boiling point of the solvent, and the immersion time is about 1 minute to 48 hours. Specific examples of the solvent that can be used for dissolving the dye include methanol, ethanol, acetonitrile, dimethyl sulfoxide, dimethylformamide, acetone, t-butanol and the like. The dye concentration of the solution is usually 1 × 10 ⁻⁶ M to 1M, preferably 1 × 10 ⁻⁵ M to ¹ × 10 ⁻¹ M. Thus, the photoelectric conversion element of the present invention having the oxide semiconductor fine particle thin film sensitized with the dye is obtained.

  The methine dye of the formula (1) or a salt thereof carried on the oxide semiconductor fine particles may be one kind or a mixture of several kinds. Moreover, when mixing, the methine dye of the present invention or a salt thereof may be used, or other dyes or metal complex dyes may be mixed. In particular, by mixing pigments having different absorption wavelengths, a wide absorption wavelength can be used, and a solar cell with high conversion efficiency can be obtained. Examples of metal complex dyes that can be mixed are not particularly limited, but ruthenium complexes and quaternary salts thereof, phthalocyanines, porphyrins and the like shown in Non-Patent Document 2 are preferable, and metal-free phthalocyanines are used as organic dyes to be mixed and utilized. And methine dyes such as porphyrin, cyanine, merocyanine, oxonol, triphenylmethane, and acrylic acid dyes disclosed in Patent Document 2, and dyes such as xanthene, azo, anthraquinone, and perylene. Preferable examples include ruthenium complexes, merocyanines, acrylic acid-based methine dyes, and the like. When two or more dyes are used, the dyes may be sequentially adsorbed on the semiconductor thin film, or may be admixed and dissolved.

  The ratio of the dye to be mixed is not particularly limited, and is selected and optimized from the respective dyes. Generally, it is preferable to use about 10% mol or more per one dye from a mixture of equimolar amounts. When the dye is adsorbed to the oxide semiconductor fine particle thin film using a solution in which the mixed dye is mixed and dissolved or dispersed, the total concentration of the dye in the solution may be the same as when only one kind is supported. As the solvent in the case of using a mixture of dyes, the above-mentioned solvents can be used, and the solvents for the respective dyes to be used may be the same or different.

When the dye is supported on the thin film of oxide semiconductor fine particles, it is effective to support the dye in the presence of the inclusion compound in order to prevent the association between the dyes. Specific examples of inclusion compounds that can be used here include steroidal compounds such as cholic acid, crown ether, cyclodextrin, calixarene, polyethylene oxide, and the like, but preferred are deoxycholic acid, dehydrodeoxycholic acid, Examples include chenodeoxycholic acid, cholic acid methyl ester, cholic acids such as sodium cholate, polyethylene oxide and the like. Alternatively, after the dye is supported, the surface of the semiconductor electrode may be treated with an amine compound such as 4-t-butylpyridine. As a treatment method, for example, a method in which a substrate provided with a semiconductor fine particle thin film carrying a dye in an ethanol solution of amine is immersed. When using a clathrate, the concentration of the clathrate is 1M~1 × 10 ^-7 M to a solution of the dye, preferably from ^{1M~1 × 10 -6 M, 0.4M~1 ×} 10 - ⁵ M is particularly preferred.

  The solar cell of the present invention is composed of a photoelectric conversion element electrode having a dye supported on the oxide semiconductor thin film, a counter electrode, a redox electrolyte, a hole transport material, a p-type semiconductor, or the like. Examples of the redox electrolyte, hole transport material, and p-type semiconductor include liquids, solidified bodies (gel and gel), and solids. As liquids, redox electrolytes, molten salts, hole transport materials, p-type semiconductors, etc. dissolved in solvents and room temperature molten salts, etc. are solidified (gel and gel), these are polymers. Examples include a matrix and a low molecular gelling agent. As a solid material, a redox electrolyte, a molten salt, a hole transport material, a p-type semiconductor, or the like can be used. Examples of the hole transport material include amine derivatives, conductive polymers such as polyacetylene, polyaniline, and polythiophene, and materials using a discotic liquid crystal phase such as a triphenylene compound. Examples of the p-type semiconductor include CuI and CuSCN. The counter electrode is preferably conductive and has a catalytic action on the reduction reaction of the redox electrolyte. For example, glass, or a polymer film deposited with platinum, carbon, rhodium, ruthenium, or the like, or coated with conductive fine particles can be used.

The redox electrolyte used in the solar cell of the present invention is a halogen redox electrolyte composed of a halogen compound and a halogen molecule as a counter ion, ferrocyanate-ferricyanate, ferrocene-ferricinium ion, cobalt complex, etc. Metal redox electrolytes such as metal complexes, and organic redox electrolytes such as alkylthiol-alkyldisulfides, viologen dyes, hydroquinone-quinones, and the like, and halogen redox electrolytes are preferred. Examples of the halogen molecule in the halogen redox electrolyte comprising a halogen compound-halogen molecule include iodine molecule and bromine molecule, and iodine molecule is preferable. As the halogen compound having a halogen ion as a counter ion, for example LiBr, NaBr, KBr, LiI, NaI, KI, CsI, CaI 2, MgI 2, CuI and halogenated metal salt or tetraalkylammonium iodide, and imidazolium Examples include halogen organic quaternary ammonium salts such as rhodium iodide and pyridinium iodide, and salts having iodine ions as counter ions are preferred. Moreover, it is also preferable to use the electrolyte which uses imide ions, such as a bis (trifluoromethanesulfonyl) imide ion and a dicyano imide ion, as a counter ion other than the said iodine ion.

  When the redox electrolyte is formed in the form of a solution containing the redox electrolyte, an electrochemically inert solvent is used as the solvent. For example, acetonitrile, propylene carbonate, ethylene carbonate, 3-methoxypropionitrile, methoxyacetonitrile, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, γ-butyrolactone, dimethoxyethane, diethyl carbonate, diethyl ether, diethyl carbonate, dimethyl carbonate, 1,2-dimethoxyethane, dimethylformamide, dimethyl sulfoxide, 1,3-dioxolane, methyl formate, 2-methyltetrahydrofuran, 3-methoxy-oxaziridin-2-one, sulfolane, tetrahydrofuran, water and the like. Among these, in particular, acetonitrile, propylene carbonate, ethylene carbonate, 3-methoxypropyl Onitoriru, methoxy acetonitrile, ethylene glycol, 3-methoxy - oxaziridine-2-one, .gamma.-butyrolactone and the like are preferable. You may use these individually or in combination of 2 or more types. In the case of a gel electrolyte, an electrolyte or electrolyte solution contained in a matrix such as an oligomer or polymer, or a low molecular gelling agent described in Non-Patent Document 3 that also contains an electrolyte or electrolyte solution Etc. The concentration of the redox electrolyte is usually 0.01 to 99% by weight, preferably about 0.1 to 90% by weight.

  In the solar cell of the present invention, a counter electrode is disposed so as to sandwich an electrode of a photoelectric conversion element in which the methine dye of the color (1) or a salt thereof is supported on an oxide semiconductor thin film on a substrate. In the meantime, it is obtained by filling a solution containing a redox electrolyte.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In the examples, parts represent parts by weight unless otherwise specified.

Synthesis example 1
17.5 parts of N, N-dimethylaminocinnamaldehyde and 18.4 parts of phenylpyruvic acid are dissolved in 100 parts of ethanol, and 0.5 part of piperazine anhydride is added thereto. After reacting at reflux for 2 hours, the cooled orange crystals are filtered, washed with water and dried. The obtained crystals were purified by column chromatography and further recrystallized from toluene to obtain 19 parts of Compound (73) as orange crystals.
λmax = 432 nm (water: acetonitrile = 7: 3)

Example The dye was dissolved in EtOH to 3.2 × 10 ⁻⁴ M. In this solution, a porous substrate (semiconductor thin film electrode obtained by sintering porous titanium oxide on a transparent conductive glass electrode for 30 minutes at 450 ° C. for 30 minutes) is immersed at room temperature (25 ° C.) for 12 hours to carry a dye, And dried, and a dye-sensitized semiconductor thin film photoelectric conversion element was obtained. For Example 5, an EtOH solution was prepared so that each of the two types of dyes was 1.6 × 10 ⁻⁴ M, and a photoelectric conversion element was similarly obtained by supporting the two types of dyes. In Examples 2, 4 and 5, a 0.2M titanium tetrachloride aqueous solution was dropped onto the titanium oxide thin film portion of the semiconductor thin film electrode, allowed to stand at room temperature for 24 hours, washed with water, and again at 450 ° C. for 30 minutes. A dye was similarly supported using a titanium tetrachloride-treated semiconductor thin film electrode obtained by firing. Further, in Example 3, the above dye solution was prepared by adding cholic acid as an inclusion compound at the time of supporting the dye to 3 × 10 ⁻² M, and supported on a semiconductor thin film to prepare a cholic acid-treated dye-sensitized semiconductor. A thin film was obtained. A conductive glass whose surface was sputtered with platinum was fixed so as to sandwich it, and a solution containing an electrolyte was injected into the gap. The electrolyte was 3-methoxypropionitrile, iodine / lithium iodide / 1,2-dimethyl-3-n-propylimidazolium iodide / t-butylpyridine, 0.1M / 0.1M / 0.6M, respectively. A solution dissolved to 1 M was used.
The size of the battery to be measured was an effective part of 0.25 cm ² . A 500 W xenon lamp was used as the light source, and it was set to 100 mW / cm ² through an AM (air passing through the atmosphere) 1.5 filter. Short-circuit current, release voltage, and conversion efficiency were measured using a potentio galvanostat.

Table 5 shows that visible light can be effectively converted into electricity by using a photoelectric conversion element sensitized by the methine dye represented by formula (1).

Claims (9)

A photoelectric conversion element characterized by using oxide semiconductor fine particles sensitized with a methine dye represented by formula (1) or a salt thereof.

(In formula (1), n represents an integer of 1 to 7. X represents an oxygen atom, a sulfur atom or a selenium atom. Y represents an aromatic residue which may have a substituent, or a substituent. A ₁ and A ₂ each independently represents an aromatic residue which may have a hydrogen atom, a hydroxyl group, a phosphate group, a cyano group, a halogen atom or a substituent. Represents an aliphatic hydrocarbon residue which may have a substituent, a carboxyl group, a carbonamido group, an alkoxycarbonyl group, an arylcarbonyl group, a sulfonylbenzene group or an acyl group, wherein n is 2 or more and A ₁ and A _2. Are present, each A ₁ and each A ₂ may be the same or different from each other, and n present A ₁ and A ₂ are two or more A ₁ and / or A ₂ . 1 to 2 or more which may be configured and have a substituent It may form a ring.) The photoelectric conversion element according to claim 1, wherein Y in the formula (1) is a group represented by the following formula (2).

(In the formula (2), R ₁ and R ₂ are each a hydrogen atom, an aromatic residue optionally having a substituent, an aliphatic hydrocarbon residue optionally having a substituent, or an acyl group. R ₁ and R ₂ may be bonded to each other or a benzene ring A to form a ring which may have a substituent, and the benzene ring A is a halogen atom, an amide group, a hydroxyl group or a cyano group. Nitro group, alkoxyl group, carboxyl group, acyl group, alkoxycarbonyl group, substituted or unsubstituted amino group, aromatic residue optionally having substituent and aliphatic carbonization optionally having substituent It may have one or more substituents selected from the group consisting of hydrogen residues, and when there are a plurality of substituents, those substituents may be bonded to each other to have a substituent. A good ring may be formed.) The photoelectric conversion element according to claim 1, wherein X in Formula (1) is an oxygen atom. N in Formula (1) is 1 thru | or 5, The photoelectric conversion element as described in any one of Claims 1 thru | or 3. It is characterized by using oxide semiconductor fine particles sensitized by one or more methine dyes represented by formula (1) or a salt thereof and a metal complex and / or an organic dye having a structure other than formula (1). Photoelectric conversion element. The photoelectric conversion element according to any one of claims 1 to 5, wherein the oxide semiconductor fine particles contain titanium dioxide, zinc oxide, or tin oxide. The oxide semiconductor fine particles sensitized with a methine dye or a salt thereof are those obtained by supporting a methine dye or a salt thereof represented by the formula (1) in the presence of an inclusion compound in the oxide semiconductor fine particles. The photoelectric conversion element as described in any one of 1 to 6. The photoelectric conversion according to any one of claims 1 to 7, wherein the oxide semiconductor fine particles sensitized with a methine dye or a salt thereof are obtained by supporting the dye on a thin film of oxide semiconductor fine particles. element. A solar cell using the photoelectric conversion element according to any one of claims 1 to 8.