JP5700937B2 - Sensitizing dye for photoelectric conversion, photoelectric conversion element and dye-sensitized solar cell using the same - Google Patents

Description

  The present invention relates to a sensitizing dye used for a dye-sensitized photoelectric conversion element, a photoelectric conversion element using the same, and a solar cell.

In recent years, carbon dioxide generated from fossil fuels such as coal, oil, and natural gas has caused global warming and the resulting environmental destruction as a greenhouse gas. There is a concern that the environmental destruction in Japan will continue to progress. In such a situation, unlike fossil fuels, studies have been vigorously conducted on the use of solar energy that is not likely to be exhausted. The introduction of photovoltaic power generation makes it possible to prevent global warming and save on energy costs, and so solar energy development and use is rapidly progressing year by year, mainly in Europe and Japan.

As a means for photovoltaic power generation, solar cells using photoelectric conversion elements that convert sunlight energy into electrical energy have been attracting attention. As solar cells, inorganic solar cells such as single crystal, polycrystal, amorphous silicon, compound semiconductors such as gallium arsenide, cadmium sulfide, and indium copper selenide have been mainly researched and put into practical use for residential use. Some are. However, these inorganic solar cells have problems such as high manufacturing costs and difficulty in securing raw materials.

On the other hand, solar cells using organic materials are said to be advantageous in terms of manufacturing cost, increase in area, and securing raw materials. As an organic solar cell, a Schottky junction type using generation of an electromotive force at a contact interface between an organic semiconductor and a metal has been known, but it has been recognized that there is a limit in improving conversion efficiency. Therefore, a pn heterojunction type utilizing a contact interface between two kinds of organic semiconductors or a contact interface between an organic semiconductor and an inorganic semiconductor has been expected. However, there is a problem that the conversion efficiency is much lower than that of the inorganic solar cell and the durability is poor.

Under such circumstances, a dye-sensitized solar cell exhibiting high conversion efficiency was reported by Prof. Gretzel et al. Of Lausanne University of Technology in Switzerland (see, for example, Non-Patent Document 1). The proposed dye-sensitized solar cell is a wet solar cell composed of a titanium oxide porous thin film electrode, a ruthenium metal complex dye, and an electrolytic solution. Dye-sensitized solar cells have a simpler device structure than other solar cells, can be manufactured without large-scale manufacturing facilities, and have high conversion comparable to amorphous silicon solar cells already in practical use. Since it is expected to be efficient, it has been attracting attention as a next-generation solar cell in recent years.

As a sensitizing dye for dye-sensitized solar cells, ruthenium metal complexes are considered to be the most advantageous from the viewpoint of conversion efficiency, but ruthenium is a precious metal, which is disadvantageous in terms of manufacturing cost and has been put into practical use in large quantities of ruthenium. Resource constraints become a problem when complexes are needed. Therefore, a dye-sensitized solar cell using an organic dye containing no precious metal such as ruthenium as a sensitizing dye has been actively studied. As organic dyes not containing noble metals, coumarin dyes, cyanine dyes, merocyanine dyes, rhodacyanine dyes, phthalocyanine dyes, porphyrin dyes, xanthene dyes and the like have been reported (for example, Patent Documents 1 and 2). reference). Although these organic dyes have the advantages that they are inexpensive, have a large absorption coefficient, and the absorption characteristics can be controlled by the variety of structures, the conversion efficiency is significantly inferior to that of ruthenium complexes, and those that sufficiently satisfy the required characteristics. The current situation is that it has not been obtained.

Patent No. 4148374 JP 11-238905 A Nature (Vol. 353, 737-740, 1991)

An object of the present invention is to provide a sensitizing dye having a novel structure capable of efficiently extracting current, and further to provide a good photoelectric conversion element and a solar cell using the sensitizing dye.

As a result of intensive studies on improving the photoelectric conversion characteristics of the sensitizing dye, the present inventors have found that a highly efficient and highly durable photoelectric conversion element can be obtained by using a sensitizing dye having a specific structure. The configuration of the present invention is as follows.

[1]
A sensitizing dye for photoelectric conversion represented by the following general formula (1).

In general formula (1), R1 and R2 may be the same or different and each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted amino group. . R3 and R4 may be the same or different and each represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted alkenyl group, and when a plurality of R3 are present, each is different from each other It may be. Z represents an atomic group necessary for forming a nitrogen-containing heterocycle. r is an integer of 0-2. However, any one of R3, R4 or Z must contain an acidic group. D represents an electron donating atomic group. n is an integer of 2 or more.

[2]
In the said General formula (1), n is an integer of 2-4, The sensitizing dye for photoelectric conversion as described in [1] characterized by the above-mentioned.

[3]
The sensitizing dye for photoelectric conversion according to [1] or [2] represented by the following general formula (2).

In the general formula (2), R1, R2, and D have the same meaning as defined in [1]. R5 and R6 may be the same or different, and when a plurality of R5 are present, each may be different from each other, and each represents an acidic group, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, At least one of R5 and R6 must be an acidic group. n is an integer of 2-4. p and q are integers of 1 to 3, and r is an integer of 0 to 2.

[4]
The sensitizing dye for photoelectric conversion according to [3] represented by the following general formula (3).

In the general formula (3), R1 and R2 have the same meaning as defined in [1], and R5, R6, p, q and r have the same meaning as defined in [3]. R7 to R11 are a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, an amino group, a monosubstituted amino group or a disubstituted amino group, a substituted or unsubstituted alkylthio group, substituted or unsubstituted Represents a substituted arylthio group, a substituted or unsubstituted alkoxy group or a substituted or unsubstituted aryloxy group, and when R9 is a disubstituted amino group, when R7 is other than a hydrogen atom, R8, R10 and R11 are simultaneously hydrogen atoms; When R7 and R10 are other than hydrogen atoms, R8 and R11 are not hydrogen atoms at the same time. R7 and R8, R8 and R9, R9 and R10, and R10 and R11 may be bonded to each other to form a cyclic structure. n is an integer of 2-4.

[5]
The sensitizing dye for photoelectric conversion according to [3] represented by the following general formula (4).

In the general formula (4), R1 and R2 have the same meaning as defined in [1], and R5, R6, p, q and r have the same meaning as defined in [3]. R12 to R20 each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted amino group, or a substituted or unsubstituted alkoxy group. n is an integer of 2-4.

[6]
The sensitizing dye for photoelectric conversion according to [3] represented by the following general formula (5).

In the general formula (5), R1 and R2 have the same meaning as defined in [1], and R5, R6, p, q and r have the same meaning as defined in [3]. R21 to R27 each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted amino group, or a substituted or unsubstituted alkoxy group. n is an integer of 2-4.

[7]
The sensitizing dye for photoelectric conversion according to [3] represented by the following general formula (6).

In the general formula (6), R1 and R2 have the same meaning as defined in [1], and R5, R6, p, q and r have the same meaning as defined in [3]. R28 and R29 each represents a hydrogen atom, a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group. n is an integer of 2-4.

[8]
The sensitizing dye for photoelectric conversion according to [3] represented by the following general formula (7).

In the general formula (7), R1 and R2 have the same meaning as defined in [1], and R5, R6, p, q and r have the same meaning as defined in [3]. R30 to R33 each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted amino group, or a substituted or unsubstituted alkoxy group. n is an integer of 2-4.

[9]
A photoelectric conversion element comprising the sensitizing dye for photoelectric conversion according to any one of [1] to [8].

In the dye-sensitized solar cell in which at least a semiconductor layer and an electrolyte layer are provided between the counter electrodes, the semiconductor layer carries the photoelectric conversion sensitizing dye according to any one of [1] to [8]. A dye-sensitized solar cell obtained by the method.

  According to the present invention, it is possible to obtain a sensitizing dye for photoelectric conversion that can efficiently extract current. Further, by using this sensitizing dye for photoelectric conversion, a highly efficient and highly durable photoelectric conversion element and dye-sensitized solar cell can be obtained.

  The sensitizing dye for photoelectric conversion of the present invention is used as a sensitizer in a dye-sensitized photoelectric conversion element. In the photoelectric conversion element of the present invention, a photoelectrode obtained by adsorbing a dye to a semiconductor layer on a conductive support and a counter electrode are arranged to face each other with an electrolyte layer interposed therebetween.

  Below, the pigment | dye which has a structure of the said General formula (1)-(7) is demonstrated.

  In the general formula (1), specific examples of R1 and R2 include, for example, a hydrogen atom, a halogen atom such as fluorine, chlorine and bromine, a methyl group, an ethyl group, an n-propyl group, an n-butyl group and a t-butyl group. , An alkyl group such as a hexyl group, an aryl group such as a phenyl group and a naphthyl group, an amino group such as a dimethylamino group, a di-t-butylamino group and a diphenylamino group, a nitrogen-containing group such as a pyridyl group, a pyridazyl group and a pyrimidyl group A heterocyclic group can be mentioned. Specific examples of R3 and R4 include, for example, alkyl groups such as methyl group, ethyl group, n-propyl group, n-butyl group, t-butyl group and hexyl group, aryl groups such as phenyl group and naphthyl group, and vinyl groups. And alkenyl groups such as allyl group and methallyl group. At least one of R3, R4 or Z must contain an acidic group. Specific examples of the acidic group include a carboxyl group, a sulfonic acid group, a phosphoric acid group, a hydroxamic acid group, a phosphonic acid group, a boric acid group, a phosphinic acid group, and a carboxyalkyl group. The atoms and groups represented by R1 to R4 may further have a substituent. Specific examples thereof include halogen atoms such as fluorine, chlorine and bromine, amino groups such as dimethylamino group and diphenylamino group, Examples thereof include an alkoxy group such as a hydroxyl group, an optionally esterified carboxyl group, a cyano group, a methoxy group, an ethoxy group, and a propoxy group. D represents an atomic group having an electron-donating group, and specific examples include a naphthyl group, an anthracene group, a pyrene group, a dialkylamino group, a diarylamino group, and the like.

The sensitizing dye for photoelectric conversion represented by the general formula (1) of the present invention is a compound having two or more thiophene rings which may have a substituent. Since the thiophene ring contains a sulfur atom, the electron donating property is high, and the electron transfer to the semiconductor layer easily occurs. In addition, as the number of thiophene rings increases, the methine chain, which is a conjugated electron system, becomes longer, so that the absorption region spreads to the longer wavelength side and the photoelectric conversion characteristics are improved. When the number of thiophene rings is one, the absorption region becomes narrow and the photoelectric conversion characteristics are inferior. However, if there are two or more thiophene rings, high photoelectric conversion characteristics can be obtained. However, when the number of thiophene rings is 5 or more, the solubility in a solvent is lowered, and it is not easy to adsorb on the surface of the semiconductor layer, and the amount of adsorption decreases, so that the photoelectric conversion characteristics are degraded. Therefore, in the general formula (1), n is an integer of 2 or more, and n is particularly preferably an integer of 2 to 4.

  Although the specific example of the sensitizing dye for photoelectric conversion shown by General formula (1) of this invention is illustrated to the following (A-1)-(A-56), it is not limited to these.

（Ａ−１８）

(A-18)

（Ａ−２９）

(A-29)

（Ａ−３０）

(A-30)

（Ａ−３１）

(A-31)

（Ａ−５２）

(A-52)

（Ａ−５３）

(A-53)

  In the general formula (2), specific examples of R5 and R6 include alkyl groups such as methyl group, ethyl group, n-propyl group, n-butyl group, t-butyl group, hexyl group, phenyl group, and naphthyl group. And an acidic group such as aryl group, carboxyl group, sulfonic acid group, phosphoric acid group, hydroxamic acid group, phosphonic acid group, boric acid group, and phosphinic acid group. At least one of R5 and R6 must be an acidic group. The atoms and groups represented by R5 and R6 may further have a substituent. Specific examples thereof include halogen atoms such as fluorine, chlorine and bromine, amino groups such as dimethylamino group and diphenylamino group, Examples thereof include an alkoxy group such as a hydroxyl group, an optionally esterified carboxyl group, a cyano group, a methoxy group, an ethoxy group, and a propoxy group.

  Specific examples of the sensitizing dye for photoelectric conversion represented by the general formula (2) of the present invention are the exemplified compounds (A-1) to (A-47) and (A-54) to (A-56). However, it is not limited to these.

  In the general formula (3), specific examples of R7 to R11 include, for example, a hydrogen atom, a halogen atom such as fluorine, chlorine and bromine, a methyl group, an ethyl group, an n-propyl group, an n-butyl group and a t-butyl group. Alkyl group such as phenyl group, aryl group such as phenyl group, naphthyl group, amino group such as dimethylamino group, di-t-butylamino group, diphenylamino group, alkylthio group such as methylthio group, n-hexylthio group, phenylthio group, Examples thereof include arylthio groups such as naphthylthio group, alkoxy groups such as methoxy group, ethoxy group and propoxy group, and aryloxy groups such as phenyloxy group and naphthyloxy group. The atoms and groups represented by R7 to R11 may further have a substituent. Specific examples thereof include halogen atoms such as fluorine, chlorine and bromine, amino groups such as dimethylamino group and diphenylamino group, Examples thereof include an alkoxy group such as a hydroxyl group, an optionally esterified carboxyl group, a cyano group, a methoxy group, an ethoxy group, and a propoxy group. R7 and R8, R8 and R9, R9 and R10, and R10 and R11 may be bonded to each other to form a cyclic structure.

  Specific examples of the sensitizing dye for photoelectric conversion represented by the general formula (3) of the present invention are the exemplified compounds (A-17) to (A-24), (A26), (A32) to (A35), (A -46), (A-48), and (A-54), but are not limited thereto.

  In the general formula (4), specific examples of R12 to R20 include, for example, a hydrogen atom, a halogen atom such as fluorine, chlorine and bromine, a methyl group, an ethyl group, an n-propyl group, an n-butyl group and a t-butyl group. Alkyl groups such as phenyl groups, aryl groups such as phenyl groups and naphthyl groups, amino groups such as dimethylamino groups, di-t-butylamino groups and diphenylamino groups, and alkoxy groups such as methoxy groups, ethoxy groups and propoxy groups Can do. The atoms / groups represented by R12 to R20 may further have a substituent. Specific examples thereof include halogen atoms such as fluorine, chlorine and bromine, amino groups such as dimethylamino group and diphenylamino group, Examples thereof include an alkoxy group such as a hydroxyl group, an optionally esterified carboxyl group, a cyano group, a methoxy group, an ethoxy group, and a propoxy group.

  Specific examples of the sensitizing dye for photoelectric conversion represented by the general formula (4) of the present invention are the exemplified compounds (A-1) to (A-10), (A-49) to (A-51), (A -55) to (A-56), but is not limited thereto.

  In the general formula (5), specific examples of R21 to R27 include, for example, a hydrogen atom, a halogen atom such as fluorine, chlorine and bromine, a methyl group, an ethyl group, an n-propyl group, an n-butyl group and a t-butyl group. And an alkyl group such as a phenyl group and a naphthyl group, and an alkoxy group such as a methoxy group, an ethoxy group and a propoxy group. The atoms and groups represented by R21 to R27 may further have a substituent. Specific examples thereof include halogen atoms such as fluorine, chlorine and bromine, amino groups such as dimethylamino group and diphenylamino group, Examples thereof include an alkoxy group such as a hydroxyl group, an optionally esterified carboxyl group, a cyano group, a methoxy group, an ethoxy group, and a propoxy group.

  Specific examples of the sensitizing dye for photoelectric conversion represented by the general formula (5) of the present invention are the exemplified compounds (A-11) to (A-16), but are not limited thereto.

  In the general formula (6), specific examples of R28 and R29 include, for example, alkyl groups such as hydrogen atom, methyl group, ethyl group, n-propyl group, n-butyl group, t-butyl group, phenyl group, and naphthyl group. And aryl groups such as The atoms and groups represented by R28 and R29 may further have a substituent, and specific examples thereof include halogen atoms such as fluorine, chlorine and bromine, amino groups such as dimethylamino group and diphenylamino group, Examples thereof include an alkoxy group such as a hydroxyl group, an optionally esterified carboxyl group, a cyano group, a methoxy group, an ethoxy group, and a propoxy group.

  Specific examples of the sensitizing dye for photoelectric conversion represented by the general formula (6) of the present invention are the exemplified compounds (A-17) to (A-22), but are not limited thereto.

  In the general formula (7), specific examples of R30 to R33 include, for example, a hydrogen atom, a halogen atom such as fluorine, chlorine and bromine, a methyl group, an ethyl group, an n-propyl group, an n-butyl group and a t-butyl group. And an alkyl group such as a phenyl group and a naphthyl group, and an alkoxy group such as a methoxy group, an ethoxy group and a propoxy group. The atoms and groups represented by R30 to R33 may further have a substituent, and specific examples thereof include halogen atoms such as fluorine, chlorine and bromine, amino groups such as dimethylamino group and diphenylamino group, Examples thereof include an alkoxy group such as a hydroxyl group, an optionally esterified carboxyl group, a cyano group, a methoxy group, an ethoxy group, and a propoxy group.

  Specific examples of the sensitizing dye for photoelectric conversion represented by the general formula (7) of the present invention are the exemplified compounds (A-37) to (A-43), but are not limited thereto.

  The sensitizing dye for photoelectric conversion of the present invention may be used alone or in combination of two or more. The sensitizing dye for photoelectric conversion of the present invention can be used in combination with other sensitizing dyes. Specific examples of other sensitizing dyes include ruthenium complexes, coumarin dyes, cyanine dyes, merocyanine dyes, rhodacyanine dyes, phthalocyanine dyes, porphyrin dyes, xanthene dyes, the above general formulas (1) to ( Although sensitizing dyes other than 7) can be mentioned, it is not limited to these. When the sensitizing dye for photoelectric conversion of the present invention and these other sensitizing dyes are used in combination, the other sensitizing dye is preferably 10 to 200% by mass with respect to the sensitizing dye for photoelectric conversion of the present invention, 20-100 mass% is more preferable.

  The method for producing a dye-sensitized photoelectric conversion element in the present invention is not particularly limited, but a method of forming a semiconductor layer on a conductive support and adsorbing the sensitizing dye for photoelectric conversion of the present invention to the semiconductor layer. Is preferred. As a method for adsorbing the dye, a method of immersing the semiconductor layer in a solution obtained by dissolving the dye in a solvent is generally used. When two or more types of sensitizing dyes for photoelectric conversion of the present invention are used in combination or when the sensitizing dye for photoelectric conversion of the present invention is used in combination with other sensitizing dyes, a mixed solution of all the dyes to be used is prepared. The semiconductor layer may be immersed, or a separate solution may be prepared for each dye, and the semiconductor layer may be sequentially immersed in each solution.

In the present invention, a glass substrate or a plastic substrate provided with a conductive layer having a conductive material on the surface in addition to a metal plate can be used as the conductive support. Specific examples of the conductive material include metals such as gold, silver, copper, aluminum, and platinum, conductive transparent oxide semiconductors such as fluorine-doped tin oxide and indium-tin composite oxide, and carbon. . In the present invention, it is preferable to use a glass substrate coated with a fluorine-doped tin oxide thin film.

  Specific examples of the semiconductor forming the semiconductor layer in the present invention include metals such as titanium oxide, zinc oxide, tin oxide, indium oxide, zirconium oxide, tungsten oxide, tantalum oxide, iron oxide, gallium oxide, nickel oxide, and yttrium oxide. Oxides, titanium sulfide, zinc sulfide, zirconium sulfide, copper sulfide, tin sulfide, indium sulfide, tungsten sulfide, cadmium sulfide, silver sulfide and other metal sulfides, titanium selenide, zirconium selenide, indium selenide, tungsten selenide Metal selenides such as silicon, and simple semiconductors such as silicon and germanium. These semiconductors can be used alone or in combination of two or more. In the present invention, it is preferable to use titanium oxide, zinc oxide, or tin oxide as the semiconductor.

  Although the aspect of the semiconductor layer in the present invention is not particularly limited, it is preferably a thin film having a porous structure composed of fine particles. When the substantial surface area of the semiconductor layer increases due to the porous structure and the like, and the amount of dye adsorbed on the semiconductor layer increases, a highly efficient photoelectric conversion element can be obtained. The semiconductor particle diameter is preferably 5 to 500 nm, and more preferably 10 to 100 nm. The film thickness of the semiconductor layer is usually 2 to 100 μm, more preferably 5 to 20 μm. As a method for forming a semiconductor layer, a paste containing semiconductor fine particles is applied onto a conductive substrate by a wet coating method such as a spin coating method, a doctor blade method, a squeegee method, or a screen printing method, and then a solvent or additive is baked. Examples thereof include a method of removing and forming a film, and a method of forming a film by sputtering, vapor deposition, electrodeposition, electrodeposition, microwave irradiation, and the like, but are not limited thereto.

  In the present invention, the paste containing semiconductor fine particles may be a commercially available product, or a paste prepared by dispersing a commercially available semiconductor fine powder in a solvent. Specific examples of the solvent used in preparing the paste include alcohol solvents such as water, methanol, ethanol, isopropyl alcohol, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, n-hexane, cyclohexane, benzene, Hydrocarbon solvents such as toluene can be mentioned, but are not limited thereto. These solvents can be used alone or as a mixed solvent of two or more.

In the present invention, when dispersing the semiconductor fine powder in the solvent, it may be ground in a mortar or the like, or a dispersing machine such as a ball mill, paint conditioner, vertical bead mill, horizontal bead mill, or attritor may be used. . When preparing the paste, it is preferable to add a surfactant or the like in order to prevent aggregation of the semiconductor fine particles, and it is preferable to add a thickener such as polyethylene glycol to increase the viscosity.

  Adsorption of the sensitizing dye for photoelectric conversion of the present invention onto the surface of the semiconductor layer is performed by immersing the semiconductor layer in the dye solution and leaving it at room temperature for 30 minutes to 100 hours or under heating conditions for 10 minutes to 24 hours. By doing. Preferred conditions are standing at room temperature for 10-20 hours. The dye concentration in the dye solution is preferably 10 to 2000 μM, more preferably 50 to 500 μM.

  Specific examples of the solvent used when adsorbing the sensitizing dye for photoelectric conversion of the present invention on the surface of the semiconductor layer include alcohol solvents such as methanol, ethanol and isopropyl alcohol, and ketone systems such as acetone, methyl ethyl ketone and methyl isobutyl ketone. Solvents, ester solvents such as ethyl formate, ethyl acetate, n-butyl acetate, ether solvents such as diethyl ether, 1,2-dimethoxyethane, tetrahydrofuran, 1,3-dioxolane, N, N-dimethylformamide, N, Amide solvents such as N-dimethylacetamide and N-methyl-2-pyrrolidone, nitrile solvents such as acetonitrile, methoxyacetonitrile and propionitrile, halogenated hydrocarbon solvents such as dichloromethane, chloroform, bromoform and o-dichlorobenzene , N-hex Down, cyclohexane, benzene, there may be mentioned a hydrocarbon solvent such as toluene, but are not limited to. These solvents are used alone or as a mixed solvent of two or more. Among these solvents, methanol, ethanol, acetone, methyl ethyl ketone, tetrahydrofuran, acetonitrile, and N, N-dimethylformamide are preferable.

When adsorbing the sensitizing dye for photoelectric conversion of the present invention on the surface of the semiconductor layer, a cholic acid derivative such as cholic acid or deoxycholic acid, chenodeoxycholic acid, lysocholic acid, and dehydrocholic acid is dissolved in the dye solution, It may be co-adsorbed with the dye. By using cholic acid or a cholic acid derivative, association between the dyes can be prevented, so that electrons can be efficiently injected from the dye to the semiconductor layer in the photoelectric conversion element. When cholic acid or cholic acid derivatives are used, their concentration in the dye solution is preferably from 0.1 to 100 mM, more preferably from 1 to 10 mM.

  The counter electrode used in the photoelectric conversion element of the present invention is not particularly limited as long as it has conductivity, but in order to promote the redox ion oxidation-reduction reaction, a conductive material having catalytic ability is used. preferable. Specific examples of the conductive material include, but are not limited to, platinum, rhodium, ruthenium, carbon, and the like. In the present invention, it is particularly preferable to use as a counter electrode a platinum thin film formed on a conductive support. As a method for forming a conductive thin film, a paste containing a conductive material is applied onto a conductive substrate by a wet coating method such as a spin coating method, a doctor blade method, a squeegee method, or a screen printing method, and then baked to form a solvent. And a method of forming a film by removing additives and a method of forming a film by a sputtering method, a vapor deposition method, an electrodeposition method, an electrodeposition method, a microwave irradiation method, and the like, but are not limited thereto.

  In the photoelectric conversion element of the present invention, an electrolyte is filled between the counter electrodes to form an electrolyte layer. A redox electrolyte is preferably used as the electrolyte. Examples of redox electrolytes include, but are not limited to, redox ion pairs such as iodine, bromine, tin, iron, chromium, and anthraquinone. Among these, iodine-based electrolytes and bromine-based electrolytes are preferable. In the case of an iodine-based electrolyte, for example, a mixture of potassium iodide, lithium iodide or the like and iodine is used. In the case of a bromine-based electrolyte, for example, a mixture of potassium bromide, lithium bromide and the like and bromine is used. In the present invention, it is preferable to use an electrolytic solution obtained by dissolving these electrolytes in a solvent. The concentration of the electrolyte in the electrolytic solution is preferably 0.05 to 5M, and more preferably 0.1 to 0.5M.

  Solvents for dissolving the electrolyte include nitrile solvents such as acetonitrile, methoxyacetonitrile, propionitrile, 3-methoxypropionitrile, benzonitrile, ether solvents such as diethyl ether, 1,2-dimethoxyethane, tetrahydrofuran, N Amide solvents such as N, N-dimethylformamide and N, N-dimethylacetamide, and carbonate solvents such as ethylene carbonate and propylene carbonate, but are not limited thereto. These solvents are used alone or as a mixed solvent of two or more. Of these solvents, nitrile solvents are preferred.

In the present invention, 4-tert-butylpyridine, 4-methylpyridine, 2-vinylpyridine, N, N-dimethyl-4-aminopyridine, N, N-dimethylaniline, N-methylbenzimidazole, etc. An amine compound may be contained. The concentration of the amine compound in the electrolytic solution is preferably 0.05 to 5M, and more preferably 0.2 to 1M. The inclusion of an amine compound in the electrolytic solution is particularly preferable because the open-circuit voltage and fill factor of the dye-sensitized photoelectric conversion element are increased.

  In the present invention, a gel electrolyte obtained by adding a gelling agent, a polymer or the like to the electrolytic solution may be used. Further, a solid electrolyte using a polymer such as a polyethylene oxide derivative may be used instead of the electrolytic solution containing the redox electrolyte. By using a gel electrolyte or a solid electrolyte, volatilization of the electrolytic solution can be reduced.

  In the photoelectric conversion element of the present invention, a solid charge transport layer may be formed between the counter electrodes instead of the electrolyte. The charge transport material contained in the solid charge transport layer is preferably a hole transport material. Specific examples of the charge transport material include inorganic hole transport materials such as copper iodide, copper bromide and copper thiocyanide, polypyrrole, polythiophene, poly-p-phenylene vinylene, polyvinyl carbazole, polyaniline, oxadiazole derivatives, tri Examples include, but are not limited to, organic hole transport materials such as phenylamine derivatives, pyrazoline derivatives, fluorenone derivatives, hydrazone compounds, and stilbene compounds.

  In the present invention, when a solid charge transport layer is formed using an organic hole transport material, it is preferable to use a film-forming binder resin in combination. Specific examples of the film-forming binder resin include polystyrene resin, polyvinyl acetal resin, polycarbonate resin, polysulfone resin, polyester resin, polyphenylene oxide resin, polyarylate resin, alkyd resin, acrylic resin, and phenoxy resin. However, it is not limited to these. These resins can be used alone or as a copolymer in combination of one or more. 20-1000 mass% is preferable and, as for the quantity with respect to the organic hole transport material of these binder resin, 50-500 mass% is more preferable.

  The photoelectric conversion element of the present invention can be applied to a dye-sensitized solar cell, various optical sensors, and the like. The dye-sensitized solar cell of the present invention is obtained by modularizing photoelectric conversion elements containing the sensitizing dyes represented by the general formulas (1) to (7) and providing predetermined electric wiring.

In the dye-sensitized solar cell of the present invention, the photoelectrode formed by adsorbing the sensitizing dye to the semiconductor layer serves as an anode, and the counter electrode serves as a cathode. Light such as sunlight may be irradiated from either the photoelectrode side or the counter electrode side, but irradiation from the photoelectrode side is preferable. The dye absorbs light by irradiation with sunlight or the like and is excited to emit electrons. The electrons flow to the outside via the semiconductor layer and move to the counter electrode. On the other hand, the dye that has been in an oxidized state by emitting electrons returns to the original state by receiving the electrons supplied from the counter electrode via the ions in the electrolyte. By this cycle, current flows and functions as a solar cell.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

[Example 1] Synthesis of sensitizing dye for photoelectric conversion (A-5) In 30 ml of toluene, 0.6 g of the following compound (B-1), 0.3 g of rhodanine-3-acetic acid, and 0.4 g of piperidine were added. The mixture was heated and stirred for 6 hours. After cooling to room temperature, the solid was collected by filtration, dispersed in an aqueous acetic acid solution and stirred for a while, and then the crystals were collected by filtration. The obtained crystals were 0.3 g and the yield was 76%.

Example 2 Synthesis of Sensitizing Dye (A-7) for Photoelectric Conversion 2.0 g of 1-pyreneboronic acid and 5 ″ -bromo- [2,2 ′; 5 ′, 2 ″] terthiophene-5 Carbaldehyde 2.4 g was reacted in a DMSO solvent in the presence of palladium acetate, butyldi-1-adamantylphosphine, and potassium acetate. After post-treatment, 1.3 g of the following compound (B-2) was obtained.

In 100 ml of ethanol, 0.2 g of the compound (B-2), 0.1 g of rhodanine-3-acetic acid and 0.1 g of piperidine were added and stirred with heating for 5 hours. After cooling to room temperature, the solid was collected by filtration, dispersed in an aqueous acetic acid solution and stirred for a while, and then the crystals were collected by filtration. The obtained crystals were 0.2 g and the yield was 73%.

[Example 3] Synthesis of sensitizing dye for photoelectric conversion (A-8) In 100 ml of ethanol, 1.0 g of the following compound (B-3), 0.5 g of rhodanine-3-acetic acid and 0.5 g of piperidine were added. The mixture was heated and stirred for 5 hours. After cooling to room temperature, the solid was collected by filtration, dispersed in an acetic acid aqueous solution and stirred for a while, and then the crystals were collected by filtration. The obtained crystals were 1.3 g and the yield was 93%.

[Example 4]
A titanium oxide paste (Ti-Nanoxide T manufactured by Solaronix) was applied to a glass substrate coated with a fluorine-doped tin oxide thin film by a squeegee method. After drying at 110 ° C. for 1 hour, baking was performed at 450 ° C. for 30 minutes to obtain a titanium oxide thin film having a thickness of 6 μm. Next, sensitizing dye (A-5) is dissolved in methanol to prepare 50 ml of a solution having a concentration of 100 μM, and a glass substrate coated with titanium oxide is immersed in this solution for 15 hours at room temperature. It was made to adsorb | suck and was set as the photoelectrode.

A platinum thin film having a thickness of 15 nm was formed on a glass substrate coated with a fluorine-doped tin oxide thin film by a sputtering method using an auto fine coater (JFC-1600 manufactured by JEOL Ltd.) as a counter electrode. Next, a 60 μm thick heat-sealing film was sandwiched between the photoelectrode and the counter electrode, and an electrolytic solution was injected into the gap to produce a photoelectric conversion element. As the electrolytic solution, a 3-methoxypropionitrile solution of lithium iodide 0.75M, iodine 0.05M, 4-tert-butylpyridine 0.5M was used.

From the photoelectrode side of the photoelectric conversion element, light generated by a pseudo-sunlight irradiation device (OTENTO-SUN III type manufactured by Spectrometer Co., Ltd.) is irradiated, and current-voltage characteristics are measured with a source meter (Model 2400 General- manufactured by KEITHLEY). Measured with Purpose SourceMeter. The intensity of light was adjusted to 100 mW / cm2. The results are shown in Table 1. Furthermore, the characteristic change after 20 hours of light irradiation was also measured. The results are shown in Table 2.

[Examples 5 to 7, 11 and Reference Examples 8 to 10, 12]
As a sensitizing dye for photoelectric conversion, a sensitizing dye shown in Table 1 was used instead of (A-5) used in Example 4, and a photoelectric conversion element was prepared in the same manner as in Example 4 except that. Characteristics were measured. The results are shown in Tables 1 and 2.

[Comparative Examples 1-4]
As the sensitizing dye for photoelectric conversion, the dyes shown in the following (C-1) to (C-4) are used in place of (A-5) used in Example 4, and the others are the same as in Example 4. Then, a photoelectric conversion element was produced and the characteristics were measured. The results are shown in Tables 1 and 2.

From these results, by using the sensitizing dye for photoelectric conversion of the present invention, it is possible to obtain a photoelectric conversion element that has high photoelectric conversion efficiency and maintains high photoelectric conversion efficiency even if light irradiation is continued for a long time. found. Among Examples, photoelectric conversion efficiency is particularly excellent in Examples 4 to 7 using the sensitizing dye represented by the general formula (4) or (5) . Moreover, also in Example 11 using the sensitizing dye represented by the general formula (7), the photoelectric conversion efficiency was relatively good.

The solar cell using the sensitizing dye for photoelectric conversion of the present invention is useful as a dye-sensitized solar cell that can efficiently convert sunlight energy into electric energy, and can provide clean energy.

Claims (5)

Following general formula (4) represented Ru photoelectric conversion sensitizing dye.

(In the formula, R ₁ and R ₂ may be the same or different and each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted amino group. R ₅ and R ₆ may be the same or different, and when a plurality of R ₅ are present, they may be different from each other, and may be an acidic group, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. And at least one of R ₅ and R ₆ must be an acidic group, n is an integer of 2 to 4, p and q are integers of 1 to 3, and r is an integer of 0 to 2. . R ₁₂ to R ₂₀ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl Motoma other represents a substituted or unsubstituted alkoxy group.) Following general formula (5) represented Ru photoelectric conversion sensitizing dye.

(In the formula, R ₁ and R ₂ may be the same or different and each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted amino group. R ₅ and R ₆ may be the same or different, and when a plurality of R ₅ are present, they may be different from each other, and may be an acidic group, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. And at least one of R ₅ and R ₆ must be an acidic group, n is an integer of 2 to 4, p and q are integers of 1 to 3, and r is an integer of 0 to 2. . R ₂₁ to R ₂₇ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl Motoma other represents a substituted or unsubstituted alkoxy group.) Following general formula (7) represented Ru photoelectric conversion sensitizing dye.

(In the formula, R ₁ and R ₂ may be the same or different and each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted amino group. R ₅ and R ₆ may be the same or different, and when a plurality of R ₅ are present, they may be different from each other, and may be an acidic group, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. And at least one of R ₅ and R ₆ must be an acidic group, n is an integer of 2 to 4, p and q are integers of 1 to 3, and r is an integer of 0 to 2. . R ₃₀ to R ₃₃ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl Motoma other represents a substituted or unsubstituted alkoxy group.) A photoelectric conversion element comprising the sensitizing dye for photoelectric conversion according to any one of claims 1 to 3 . In the dye-sensitized solar cell in which at least the semiconductor layer and the electrolyte layer are provided between the counter electrodes, the photoelectric conversion sensitizing dye according to any one of claims 1 to 3 is supported on the semiconductor layer. A dye-sensitized solar cell obtained by the method.