JP5096673B2 - Semiconductor electrode and photoelectric conversion element - Google Patents

Description

The present invention comprises a substrate having conductivity on the surface, a semiconductor layer coated on the conductive surface,
The present invention relates to a semiconductor electrode composed of two or more dyes adsorbed on the surface of the semiconductor layer, and a photoelectric conversion element using the semiconductor electrode.

Global warming due to the increase in CO ₂ concentration caused by the use of a large amount of fossil fuel, and the increase in energy demand accompanying population increase are recognized as problems related to the existence of human beings. For this reason, in recent years, the use of sunlight that is infinite and does not generate harmful substances has been energetically studied. What is currently put into practical use as sunlight, which is a clean energy source, includes residential single crystal silicon, polycrystalline silicon, amorphous silicon, and inorganic solar cells such as cadmium telluride and indium copper selenide.

  However, these inorganic solar cells also have drawbacks. For example, a silicon system is required to have a very high purity. Naturally, the purification process is complicated, the number of processes is large, and the manufacturing cost is high. In addition, there is a demand for weight reduction and the like, and in particular, it is disadvantageous in that payback to the user is long, and there is a problem in the spread.

  On the other hand, many solar cells using organic materials have been proposed. As an organic solar cell, a Schottky photoelectric conversion element that joins a p-type organic semiconductor and a metal having a low work function, a p-type organic semiconductor and an n-type inorganic semiconductor, or a p-type organic semiconductor and an electron-accepting organic compound are joined. There are heterojunction photoelectric conversion elements and the like, and organic semiconductors used are synthetic dyes and pigments such as chlorophyll and perylene, conductive polymer materials such as polyacetylene, or composite materials thereof. These are thinned by a vacuum deposition method, a casting method, a dipping method, or the like to form a battery material. The organic material has advantages such as low cost and easy area enlargement, but there are many problems that the conversion efficiency is as low as 1% or less and the durability is poor.

  Under such circumstances, a solar cell exhibiting good characteristics has been reported by Dr. Gretzell of Switzerland (see Non-Patent Document 1). This document also discloses materials and manufacturing techniques necessary for battery fabrication. The proposed battery is called a dye-sensitized solar cell or a Gretzel solar cell, and is a wet solar cell using 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 inexpensive because it is not necessary to purify an inexpensive oxide semiconductor such as titanium oxide to a high purity. Further, the available light extends to the visible light region, and the sun is rich in visible light components. It is that light can be effectively converted into electricity.

However, dye-sensitized solar cells still have problems to be solved for practical use. For example, in a dye-sensitized solar cell using not only a ruthenium complex but generally a single organic dye and an organometallic complex dye, the wavelength range of light that can be used for photoelectric conversion by these dyes is sunlight or fluorescent lamps. Since the wavelength range of the light used as the light source is narrower, the wavelength component of the light source is not necessarily fully utilized. Therefore, for example, such a problem may be solved by adsorbing two or more dyes on the surface of a semiconductor such as titanium oxide. In addition, since the ruthenium complex uses a rare metal ruthenium, there are limitations in terms of resources, and a dye is very expensive. Therefore, in dye-sensitized solar cells using ruthenium complexes, it is possible to solve these problems by replacing some of the ruthenium complexes with organic dyes that have high quantum efficiency and are advantageous in terms of resource constraints. There is sex. As organic dyes for dye-sensitized solar cells, merocyanine dyes, cyanine dyes, 9-phenylxanthene dyes and the like have been reported (for example, see Patent Documents 1 to 3). However, even if at least two or more selected from these organic dyes are adsorbed on the surface of the semiconductor layer, or at least one selected from these organic dyes and a ruthenium complex dye or the like are adsorbed on the surface of the semiconductor layer such as titanium oxide. Even in this case, there are almost no cases where the photoelectric conversion performance is synergistically improved by two or more kinds of dyes adsorbed on the surface of the semiconductor layer, and the above-mentioned problems have not been sufficiently solved.
JP 11-238905 A JP 2001-76773 A Japanese Patent Laid-Open No. 10-92477 Nature, 353, 737 (1991)

  The objective of this invention is providing the photoelectric conversion element excellent in the photoelectric conversion characteristic.

  As a result of intensive studies on various sensitizing dyes to achieve the above object, the present inventors have achieved the object by the following measures.

A substrate having an electrically conductive (i) surface in the semiconductor layer and a semiconductor electrode comprising consist supported more dyes on the surface of the semiconductor layer covering the electrically conductive surface, at least one of the dye The seed is a dye having a maximum absorption wavelength of an absorption spectrum in a solution dissolved in an organic solvent at 350 nm or more and 500 nm or less, and at least one of the other dyes has a maximum absorption wavelength at 500 nm or more and 700 nm or less. A semiconductor electrode characterized by being a dye.

Organic solvent dissolved a maximum absorption wavelength of the absorption spectrum in the liquid 500nm or more, semi-conductor electrode dye Ru der ruthenium complex having the 700nm below.

The maximum absorption wavelength of the absorption spectrum in dissolved in organic solvent liquid 350nm or more, dyes having a 500nm or less is at least one selected from dyes represented de following general formula (1) General formula (2) der Ru semi conductor electrode.

(In General Formula (1), R ₁ represents an aryl group and may have a substituent. R ₂ forms a ring structure by bonding to a nitrogen atom and a benzene ring adjacent to the nitrogen atom. the linking group which indicates, cyclic structure is a five-membered ring .R ₃ is shown to .l hydrogen atom is 0 carbon -. carbon double bonds, be either E, Z-shaped which may be .R ₄ is shown to .R ₅ hydrogen atom a substituent oxygen atom, a water MotoHara child.)

In (formula (2), R ₆ and R ₁₀ is a nitrogen atom, bonded to the benzene ring adjacent to the nitrogen atom indicates a linking group which forms a cyclic structure, the cyclic structure is a 5-membered ring. R ₇ and _{R 11} is 0 is shown to .m and n hydrogen atom carbon -. carbon double bond, E, good .R ₈ and _{R 12} be either a Z-type hydrogen atoms the shown to .Ar ₁ and Ar ₂ child indicates 1,4-phenylene group, _{L 4} represents a divalent linking group represented by -SCH ₂ CH ₂ S-, p is an .R ₉ showing a 1 R ₁₃ is a substituent of an oxygen atom, a water MotoHara child.)

( B ) The semiconductor is selected from titanium, tin, zinc, iron, copper, tungsten, zirconium, hafnium, niobium, tantalum, cadmium, lead, silver, antimony, bismuth, molybdenum, aluminum, gallium, chromium, cobalt, nickel (a) above Symbol mounting of the semiconductor electrode to be metal chalcogenides comprising at least one kind.

( C ) A photoelectric conversion element using the semiconductor electrode described in (a) or (b) above.

  In the semiconductor electrode composed of two or more kinds of dyes adsorbed on the surface of the semiconductor layer, at least one kind of dye selected from the compounds represented by the general formula (1) or the general formula (2) used in the present invention is used. By using, the photoelectric conversion element which shows the photoelectric conversion efficiency superior to the case where each pigment | dye is used independently can be obtained. Furthermore, by using a semiconductor electrode using a dye selected from the compound represented by the general formula (1) or the general formula (2) and a ruthenium complex dye, a photoelectric conversion element having further excellent conversion efficiency is obtained. Was made. The details of the mechanism by which such a synergistic effect is obtained by using two or more dyes have not been elucidated. However, the present inventors can firstly mention the complementarity of the absorption spectra of two or more dyes as the cause of the synergistic effect. From the relationship with the semiconductor band gap, it is known that dyes having good photoelectric conversion efficiency are generally those having a maximum absorption wavelength of an absorption spectrum in a liquid dissolved in an organic solvent in the range of 500 nm to 700 nm. ing. The absorption intensity of these dyes at 350 nm to 500 nm is relatively weak compared to the maximum absorption region, and by combining these dyes with a dye having an absorption maximum at 350 nm to 500 nm, it is efficient over a wide wavelength range of 350 nm to 700 nm. It can be easily analogized that a semiconductor electrode capable of photoelectric conversion can be manufactured. However, when multiple dyes with different maximum absorption wavelengths are used in combination, inhibition of adsorption to semiconductors between different types of dyes, or generation of dye aggregates on the semiconductor surface with low photoelectric conversion efficiency by using different types of dyes together For this reason, there are very few practical examples of a plurality of dyes that can achieve excellent photoelectric conversion efficiency. The present inventors use a semiconductor electrode capable of efficiently performing photoelectric conversion over a wide wavelength region of 350 nm to 700 nm by using at least one dye selected from the compounds represented by the general formula (1) or the general formula (2). It has been found that

  Furthermore, the present inventors can add the following points as causes of the synergistic effects.

  (A) The dye used in the present invention is excellent in the ability to cover the surface of a semiconductor layer having non-uniform chemical or physical properties in a minute region. The basis for this is that when the dye represented by the general formula (1) or the general formula (2) is adsorbed on the surface of the semiconductor layer, a J aggregate is formed as a form of a molecular assembly to form the surface of the semiconductor layer. And the phenomenon of dense adsorption. The J aggregate represents an aggregate in which at least four or more dye molecules are regularly aligned. In general, the maximum absorption wavelength of the absorption spectrum of the dye J aggregate is approximately 50 nm to 100 nm longer than the maximum absorption wavelength of the absorption spectrum of a single molecule of the dye.

  (B) The surface portion of the semiconductor layer that is not adsorbed to the dye, which is generated when the dye (for example, ruthenium complex dye) used in combination with the dye represented by the general formula (1) or (2) is adsorbed on the surface of the semiconductor layer. Can be coated using the dye represented by the general formula (1) or the general formula (2), which has an excellent ability to coat the surface of the semiconductor layer.

The compound represented by the general formula (1) used in the present invention will be described in more detail. Specific examples of R ₁ of the compound represented by the general formula (1) include alkyl groups such as methyl group, ethyl group and isopropyl group, aralkyl groups such as benzyl group and 1-naphthylmethyl group, vinyl group, cyclohexane Examples include alkenyl groups such as hexenyl groups, aryl groups such as phenyl groups and naphthyl groups, and heterocyclic residues such as furyl groups, thienyl groups, and indolyl groups. In the present invention, R ₁ is an aryl group. The R ₁ group may have a substituent. Specific examples of the substituent include the same alkyl group as R ₁ , an alkoxy group such as a methoxy group, an ethoxy group, and an n-hexyloxy group, methylthio Group, alkylthio group such as n-hexylthio group, aryloxy group such as phenoxy group and 1-naphthyloxy group, arylthio group such as phenylthio group, halogen atom such as chlorine and bromine, dimethylamino group and diphenylamino group substituted amino group, the same aryl group as R _1, the same heterocycle with R _1, carboxyl group, carboxyalkyl carboxyalkyl group such as methyl group, sulfonyl propylsulfonyl alkyl groups such as groups, phosphate groups, hydroxamic acid And an electron-withdrawing group such as a cyano group, a nitro group, and a trifluoromethyl group. R ₂ is a linking group that forms a cyclic structure by combining with a nitrogen atom and a benzene ring adjacent to the nitrogen atom, and is further cyclic between R ₁ and R ₂ , R ₁ and the benzene ring adjacent to the nitrogen atom. A structure may be formed. Specific examples thereof can be mentioned in formulas (3) to (19) . In the present invention, R ₂ is a linking group that forms a cyclic structure by bonding to a nitrogen atom and a benzene ring adjacent to the nitrogen atom. And the cyclic structure is a 5-membered ring . R ₃ is a hydrogen atom, the same alkyl group as R _1, the same alkoxy group as R _1, shows the same halogen atom and R _1, which may have a substituent. Specific examples of the substituent include the same alkyl group as R ₁ , an alkoxy group such as a methoxy group, an ethoxy group and an n-hexyloxy group, an alkylthio group such as a methylthio group and an n-hexylthio group, a phenoxy group, 1- Similarly aryloxy group such as naphthyloxy group, an arylthio group such as phenylthio group, a chlorine, a halogen atom such as bromine, dimethylamino group, disubstituted amino groups such as diphenylamino group, same aryl group as R _1, and R ₁ Heterocycle, carboxyl group such as carboxyl group and carboxymethyl group, sulfonylalkyl group such as sulfonylpropyl group, acidic group such as phosphoric acid group and hydroxamic acid, electron withdrawing such as cyano group, nitro group and trifluoromethyl group Sex groups can be mentioned. The acidic group may be in the form of a quaternary ammonium salt, metal salt, ester or amide. In the present invention, R ₃ is a hydrogen atom. Specific examples of L ₁ include alkenylene groups such as 1,2-vinylene group and 1,4-butadienylene group, arylene groups such as 1,4-phenylene group and 1,4-naphthylene group, and 2,5-thienylene group. And divalent aromatic heterocyclic residues having one or more heterocyclic rings. In the present invention, l is 0. R ₄ is a hydrogen atom, the same alkyl group as R _1, the same aralkyl groups as R _1, showed a similar heterocyclic residue and R _1, which may have a substituent. Specific examples of the substituent include the same alkyl group as R ₁ , an alkoxy group such as a methoxy group, an ethoxy group and an n-hexyloxy group, an alkylthio group such as a methylthio group and an n-hexylthio group, a phenoxy group, 1- Similarly aryloxy group such as naphthyloxy group, an arylthio group such as phenylthio group, a chlorine, a halogen atom such as bromine, dimethylamino group, disubstituted amino groups such as diphenylamino group, same aryl group as R _1, and R ₁ Heterocycle, carboxyl group such as carboxyl group and carboxymethyl group, sulfonylalkyl group such as sulfonylpropyl group, acidic group such as phosphoric acid group and hydroxamic acid, electron withdrawing such as cyano group, nitro group and trifluoromethyl group Sex groups can be mentioned. The acidic group may be in the form of a quaternary ammonium salt, metal salt, ester or amide. In the present invention, R ₄ is a hydrogen atom. Specific examples of R ₅ include, in addition to hydrogen atoms, alkyl groups such as methyl group and ethyl group, and quaternary ammonium salts such as ammonium ion, tetraethylammonium ion and tetrabutylammonium ion . R ₅ is a hydrogen atom .

The compound represented by the general formula (2) used in the present invention will be described in more detail. R ₆ and R ₁₀ of the compound represented by the general formula (2) are a linking group that forms a cyclic structure by bonding with a nitrogen atom and a benzene ring adjacent to the nitrogen atom. Specific examples thereof can be given in (20) to (36) . In the present invention, R ₆ and R ₁₀ are bonded to a nitrogen atom and a benzene ring adjacent to the nitrogen atom to form a cyclic structure. A linking group is shown, and the cyclic structure is a 5-membered ring . The substituent Ar in the specific examples (20) to (36) means Ar ₁ or Ar ₂ in the general formula (2). R ₇ and R ₁₁ represent a hydrogen atom, an alkyl group such as a methyl group, an ethyl group and an isopropyl group, an alkoxy group such as a methoxy group, an ethoxy group and an n-hexyloxy group, and a halogen atom such as chlorine and bromine. These may further have a substituent. Specific examples of the _substituent, an alkyl group similar to R _{7, R 11,} same alkoxy group as R _{7, R 11,} methylthio group, n- hexylthio alkylthio group such as a group, a phenoxy group, 1-naphthyloxy Aryloxy groups such as phenylthio groups, arylthio groups such as phenylthio groups, halogen atoms such as chlorine and bromine, disubstituted amino groups such as dimethylamino groups and diphenylamino groups, aryl groups similar to R ₇ and R ₁₁ , furyl groups, thienyl group, a heterocyclic, carboxyl group such as an indolyl group, carboxyalkyl carboxyalkyl group such as a methyl group, sulfonyl propylsulfonyl alkyl group such as a group, phosphoric acid group, an acidic group such as a hydroxamic acid, a cyano group, a nitro group, a tri Mention may be made of electron-withdrawing groups such as fluoromethyl groups. The acidic group may be in the form of a quaternary ammonium salt, metal salt, ester or amide. In the present invention, R ₇ and R ₁₁ are hydrogen atoms. Specific examples of L ₂ and L ₃ include alkenylene groups such as 1,2-vinylene group and 1,4-butadienylene group, arylene groups such as 1,4-phenylene group and 1,4-naphthylene group, 2,5 -The divalent aromatic heterocyclic residue which has 1 or more heterocyclic rings, such as a thienylene group, can be mentioned. In the present invention, m and n are 0. R ₈ and _{R 12} is a hydrogen _atom, the same alkyl group as _{R 7, R 11, R 7} , R 11 and similar aralkyl group, a furyl group, a thienyl group, a heterocyclic residue such as an indolyl group, a substituted group You may have. Specific examples of the substituent include alkyl groups similar to R ₇ and R ₁₁ , alkoxy groups such as methoxy group, ethoxy group and n-hexyloxy group, alkylthio groups such as methylthio group and n-hexylthio group, and phenoxy groups. Aryloxy groups such as 1-naphthyloxy group, arylthio groups such as phenylthio group, halogen atoms such as chlorine and bromine, disubstituted amino groups such as dimethylamino group and diphenylamino group, aryl groups such as phenyl group and naphthyl group , Furyl group, thienyl group, indolyl group and other heterocycles, carboxyl group, carboxyalkyl group such as carboxymethyl group, sulfonylalkyl group such as sulfonylpropyl group, acidic group such as phosphate group, hydroxamic acid, cyano group, nitro group And an electron withdrawing group such as a trifluoromethyl group. The acidic group may be in the form of a quaternary ammonium salt, metal salt, ester or amide. In the present invention, R ₈ and R ₁₂ are hydrogen atoms. Specific examples of R ₉ and R ₁₃ are, in addition to the hydrogen atom, an alkyl group such as methyl group and ethyl group, an ammonium ion, tetraethyl ammonium ion, although quaternary ammonium salts such as tetrabutylammonium ion and the like, and the present In the invention, R ₉ and R ₁₃ are hydrogen atoms . Ar ₁ and Ar ₂ are divalent aromatics having one or more hetero rings such as 1,4-phenylene group, 1,3-phenylene group, arylene group such as 2,6-naphthylene group and 2,5-thienylene group. In the present invention, Ar ₁ and Ar ₂ are 1,4-phenylene groups . L ₄ is a divalent linking group, and specific examples thereof include linking groups as shown in (37) to (48) . In the present invention, L ₄ is —SCH ₂ CH ₂ S—. There is .

Specific examples of the compound represented by the general formula (1) according to the present invention are shown in (A-1) to (A-18). (A-2) to (A-4), (A-16), and (A-17) are reference examples.

Specific examples of the compound represented by the general formula (2) according to the present invention are shown in (B-1) to (B-14). (B-1) to (B-6) and (B-8) to (B-14) are reference examples.

  In the present invention, the dye used in combination with the dye represented by formula (1) or formula (2) will be described. The absorption maximum wavelength of the dye represented by the general formula (1) or (2) and the dye used in combination may be the same or different. However, the incident light wavelength dependency of the quantum efficiency of a photoelectric conversion element using a semiconductor electrode using a dye used in combination with the dye represented by the general formula (1) or (2) as a working electrode is expressed by the general formula ( It is more preferable that the relationship is complementary to the incident light wavelength dependency of the quantum efficiency of a photoelectric conversion element having a semiconductor electrode using a dye represented by 1) or the general formula (2) as a working electrode. More specifically, the dye represented by the general formula (1) or the general formula (2) has a maximum absorption wavelength of an absorption spectrum in a liquid dissolved in an organic medium in a range of 350 nm to 500 nm. The maximum absorption wavelength of the absorption spectrum in the organic medium of the dye used in combination with the dye represented by the general formula (1) or (2) is preferably at a wavelength exceeding 500 nm.

  Specific examples of the dye used in combination with the dye represented by the general formula (1) or the general formula (2) include a cyanine dye, a merocyanine dye, a 9-arylxanthene compound, a triarylmethane compound, a coumarin compound, and an acridine compound. Azo compounds, phthalocyanine compounds, porphyrin compounds, organometallic complex compounds, and the like. Specific examples are given in (C-1) to (C-23). However, the dye used in combination with the dye represented by the general formula (1) or the general formula (2) of the present invention is not limited to these exemplified compounds.

Among these dyes, the present invention can be obtained ruthenium complex dye represented by the general formula (1) or use a combination of a dye represented by formula (2) Iteori, more preferred photoelectric conversion characteristics. Specific examples of the ruthenium complex dye are listed in (D-1) to (D-10). However, the ruthenium complex dye used in combination with the dye represented by the general formula (1) or the general formula (2) of the present invention is not limited to these exemplified compounds.

  Regarding the absorption spectrum of the dye according to the present invention, only the dye is dissolved in methanol or N, N-dimethylformamide, and the sample solution is placed in a quartz cell having a cell length of 1 cm, and a visible / ultraviolet spectrophotometer (manufactured by JASCO). V-570) was used to measure the wavelength range from 350 nm to 700 nm. The dye concentration was measured by setting the concentration at which the absorbance at the maximum absorption wavelength was 1.0 according to the molar extinction coefficient of the dye itself.

  The photoelectric conversion element of the present invention comprises a conductive substrate, a semiconductor layer sensitized by a dye placed on the conductive substrate, a charge transfer layer, and a counter electrode. The semiconductor layer may be a single layer structure or a stacked structure, and is designed according to the purpose. In addition, at the boundary of this element such as the boundary between the conductive layer and the semiconductor layer of the conductive support, the boundary between the semiconductor layer and the charge transfer layer, the constituent components of each layer may be diffused or mixed with each other.

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

  A metal lead wire may be used for the purpose of reducing the resistance of the transparent conductive substrate. Examples of the material of the metal lead wire include metals such as aluminum, copper, silver, gold, platinum, and nickel. A metal lead wire is installed on a transparent substrate by vapor deposition, sputtering, pressure bonding, or the like, and a method of providing ITO or FTO thereon or a metal lead wire on a transparent conductive layer.

  As the semiconductor, a single semiconductor such as silicon or germanium, a compound semiconductor typified by a metal chalcogenide, a compound having a perovskite structure, or the like can be used. Metal chalcogenides include titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium, or tantalum oxides, cadmium, zinc, lead, silver, antimony, bismuth. Sulfide, cadmium, lead selenide, cadmium telluride and the like. Other compound semiconductors are preferably phosphides such as zinc, gallium, indium, cadmium, gallium arsenide, copper-indium-selenide, copper-indium-sulfide, and the like. As the compound having a perovskite structure, strontium titanate, calcium titanate, sodium titanate, barium titanate, potassium niobate and the like are preferable.

  The semiconductor used in the present invention may be single crystal or polycrystalline. As the conversion efficiency, a single crystal is preferable, but a polycrystal is preferable in terms of manufacturing cost, securing raw materials, and the like, and the particle size of the semiconductor is preferably 2 nm or more and 1 μm or less.

  Examples of a method for forming a semiconductor layer on a conductive support include a method in which a dispersion or colloidal solution of semiconductor fine particles is applied on a conductive support, a sol-gel method, and the like. The dispersion can be prepared by the above-mentioned sol-gel method, a method of mechanically pulverizing with a mortar, etc., a method of dispersing while pulverizing using a mill, or a fine particle in a solvent when synthesizing a semiconductor. And a method of using it as it is.

  In the case of a dispersion prepared by mechanical pulverization or pulverization using a mill, it is formed by dispersing at least semiconductor fine particles alone or a mixture of semiconductor fine particles and a resin in water or an organic solvent. Resins used include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, acrylic acid esters, methacrylic acid esters, silicone resins, phenoxy resins, polysulfone resins, polyvinyl butyral resins, polyvinyl formal resins, polyester resins. , Cellulose ester resin, cellulose ether resin, urethane resin, phenol resin, epoxy resin, polycarbonate resin, polyarylate resin, polyamide resin, polyimide resin and the like.

  Solvents for dispersing the semiconductor fine particles include alcohol solvents such as water, 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. Ester solvents, diethyl ether, dimethoxyethane, tetrahydrofuran, dioxolane, or ether solvents such as dioxane, N, N-dimethylformamide, N, N-dimethylacetamide, or amide solvents such as N-methyl-2-pyrrolidone , Dichloromethane, chloroform, bromoform, methyl iodide, dichloroethane, trichloroethane, trichloroethylene, chlorobenzene, o-dichlorobenzene, fluorobenzene, bromobenzene, iodine Halogenated hydrocarbon solvents such as debenzene or 1-chloronaphthalene, n-pentane, n-hexane, n-octane, 1,5-hexadiene, cyclohexane, methylcyclohexane, cyclohexadiene, benzene, toluene, o-xylene, Examples thereof include hydrocarbon solvents such as m-xylene, p-xylene, ethylbenzene, and cumene. These can be used alone or as a mixed solvent of two or more.

Examples of the method for applying the obtained dispersion include a roller method, a dip method, an air knife method, a blade method, a wire bar method , a slide hopper method, an extrusion method, a curtain method, a spin method, and a spray method.

  Furthermore, the semiconductor layer may be a single layer or multiple layers. In the case of multiple layers, a dispersion of semiconductor fine particles having different particle diameters can be applied in multiple layers, or different types of semiconductors, and application layers having different compositions of resins and additives can be applied in multiple layers. In addition, when the film thickness is insufficient with a single coating, the multilayer coating is an effective means.

  In general, as the thickness of the semiconductor layer increases, the amount of supported dye increases per unit projected area and the light capture rate increases. However, the diffusion distance of the generated electrons also increases, and the recombination of charges also increases. End up. Therefore, the film thickness of the semiconductor layer is preferably 0.1 to 100 μm, and more preferably 1 to 30 μm.

The semiconductor fine particles may be heat-treated after being coated on the conductive support, but from the viewpoint of improving the electronic contact between the particles and the strength of the coating film and the adhesion with the support, Microwave irradiation, press treatment, or electron beam irradiation may be performed, and these treatments may be performed alone or in combination of two or more. In the heat treatment, the heating temperature is preferably 40 to 700 ° C, more preferably 80 to 600 ° C. The heating time is preferably 5 minutes to 50 hours, and more preferably 10 minutes to 20 hours. The microwave irradiation may be performed from the semiconductor layer forming side of the semiconductor electrode or from the back side. Although there is no restriction | limiting in particular in irradiation time, It is preferable to carry out within 1 hour. The press treatment is preferably 100 kg / cm ² or more, more preferably 1000 kg / cm ² . There is no particular limitation on the pressing time, but it is preferably performed within 1 hour.

  The semiconductor fine particles preferably have a large surface area so that many dyes can be adsorbed. For this reason, it is preferable that the surface area in the state which coated the semiconductor layer on the support body is 10 times or more with respect to a projection area, and it is more preferable that it is 100 times or more.

  As a method of adsorbing the dye to the semiconductor layer, a method of immersing a working electrode containing semiconductor fine particles in a dye solution or a dye dispersion, or a method of applying a dye solution or a dispersion to the semiconductor layer and adsorbing it is used. Can do. In the former case, dipping method, dipping method, roller method, air knife method, etc. can be used, and in the latter case, wire bar method, slide hopper method, extrusion method, curtain method, spin method, spray method, etc. Can be used. However, the immersion method using a solution is the best method for reliably achieving the adsorption equilibrium of the dye.

  In the present invention, as a procedure for adsorbing two or more kinds of dyes on the surface of the semiconductor layer, two or more kinds of mixed solutions may be adsorbed simultaneously, or individual solutions of two or more kinds of dyes may be used. Alternatively, they may be alternately adsorbed. The concentration of the dye solution can be arbitrarily prepared and used in the range of 0.01 to 10.0 mM, whether it is a mixture of two or more dyes or individual solutions. More preferably, it is 0.0 mM. Moreover, when adsorb | sucking 2 or more types of pigment | dyes alternately, the order of the pigment | dye to adsorb | suck can be set arbitrarily.

  In the case of dye adsorption, a condensing agent may be used in combination. The condensing agent may be either a catalyst that physically or chemically binds the dye to the inorganic surface or a substance that reacts stoichiometrically. Furthermore, a thiol or a hydroxy compound may be added as a condensation aid.

  Solvents that dissolve or disperse the dye are alcohol solvents such as water, methanol, ethanol, and isopropyl alcohol, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, and nitriles such as acetonitrile and 3-methoxypropionitrile. Solvents, ester solvents such as ethyl formate, ethyl acetate, or n-butyl acetate, ether solvents such as diethyl ether, dimethoxyethane, tetrahydrofuran, dioxolane, or dioxane, N, N-dimethylformamide, N, N-dimethyl Amide solvents such as acetamide or N-methyl-2-pyrrolidone, dichloromethane, chloroform, bromoform, methyl iodide, dichloroethane, trichloroethane, trichloroethylene, chloroben , O-dichlorobenzene, fluorobenzene, bromobenzene, iodobenzene, or halogenated hydrocarbon solvents such as 1-chloronaphthalene, n-pentane, n-hexane, n-octane, 1,5-hexadiene, cyclohexane, Examples include hydrocarbon solvents such as methylcyclohexane, cyclohexadiene, benzene, toluene, o-xylene, m-xylene, p-xylene, ethylbenzene, and cumene, and these are used alone or as a mixture of two or more. be able to.

  As temperature at the time of adsorb | sucking a pigment | dye, -50 degreeC or more and 200 degrees C or less are preferable. At this time, the dye solution may be stirred. Examples of the stirring method include, but are not limited to, a stirrer, a ball mill, a paint conditioner, a sand mill, an attritor, a disperser, and ultrasonic dispersion. The time required for adsorption is preferably 5 seconds or more and 1000 hours or less, more preferably 10 seconds or more and 500 hours or less, and further preferably 1 minute or more and 150 hours or less.

  In the present invention, a surfactant may be used in combination when adsorbing the dye. As the surfactant, steroidal compounds, particularly cholic acid derivatives, are preferable, and specific examples thereof include those shown in (E-1) to (E-10). 0.01-1000 mass parts is preferable with respect to 1 mass part of pigment | dyes, and, as for the quantity of a steroid type compound, 0.1-100 mass parts is more preferable.

  The charge transfer layer of the photoelectric conversion element of the present invention contains an electrolytic solution in which a redox couple is dissolved in an organic solvent, a gel electrolyte in which a liquid in which the redox couple is dissolved in an organic solvent is impregnated in a polymer matrix, and a redox couple Molten salts, solid electrolytes, organic hole transport materials, and the like can be used.

  The electrolytic solution used in the present invention is preferably composed of an electrolyte, a solvent, and an additive. Preferred electrolytes include metal iodide-iodine combinations such as lithium iodide, sodium iodide, potassium iodide, cesium iodide, and calcium iodide, tetraalkylammonium iodide, pyridinium iodide, imidazolium iodide, and the like. Iodine salts of quaternary ammonium compounds-iodine combinations, metal bromides such as lithium bromide, sodium bromide, potassium bromide, cesium bromide, calcium bromide-bromine combinations, quaternary compounds such as tetraalkylammonium bromide, pyridinium bromide Bromine-bromine combinations of ammonium compounds, metal complexes such as ferrocyanate-ferricyanate, ferrocene-ferricinium ion, sulfur compounds 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 molten salt in a molten state at room temperature can also be used as the electrolyte. When this molten salt is used, it is not necessary to use a solvent.

  The electrolyte concentration in the electrolytic solution is preferably 0.05 to 20M, and more preferably 0.1 to 15M. Solvents used for the electrolyte 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, ethanol Alcohol solvents such as polypropylene glycol monoalkyl ether, nitrile solvents such as acetonitrile, 3-methoxypropionitrile and benzonitrile, and aprotic polar solvents such as dimethyl sulfoxide and sulfolane are preferred. Further, basic compounds such as t-butylpyridine, 2-picoline, and 2,6-lutidine may be used in combination.

  In the present invention, the electrolyte can be gelled by a technique such as addition of a polymer, addition of an oil gelling agent, polymerization including polyfunctional monomers, or a crosslinking reaction of the polymer. Preferable polymers in the case of gelation by polymer addition include polyacrylonitrile, polyvinylidene fluoride and the like. Preferred gelling agents for gelation by adding an oil gelling agent include dibenzylden-D-sorbitol, cholesterol derivatives, amino acid derivatives, alkylamide derivatives of trans- (1R, 2R) -1,2-cyclohexanediamine, alkylureas Derivatives, N-octyl-D-gluconamide benzoate, double-headed amino acid derivatives, quaternary ammonium derivatives and the like can be mentioned.

Preferred monomers when polymerized by polyfunctional monomer include divinylbenzene, Echirengu recall dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate be able to. Furthermore, esters and amides derived from acrylic acid such as acrylamide and methyl acrylate and α-alkyl acrylic acid, esters derived from maleic acid and fumaric acid such as dimethyl maleate and diethyl fumarate, butadiene, cyclohexane and the like. Dienes such as pentadiene, aromatic vinyl compounds such as styrene, p-chlorostyrene and sodium styrene sulfonate, vinyl esters, acrylonitrile, methacrylonitrile, vinyl compounds having a nitrogen-containing heterocyclic ring, vinyl having a quaternary ammonium salt A monofunctional monomer such as a compound, N-vinylformamide, vinylsulfonic acid, vinylidene fluoride, vinyl alkyl ethers, N-phenylmaleimide may be contained. 0.5-70 mass% is preferable and the polyfunctional monomer which occupies for the monomer whole quantity has more preferable 1.0-50 mass%.

  The above-mentioned monomers can be polymerized by radical polymerization. The monomer for gel electrolyte that can be used in the present invention can be radically polymerized by heating, light, electron beam or electrochemical. The polymerization initiator used when the crosslinked polymer is formed by heating is 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl-2. Azo initiators such as 2,2′-azobis (2-methylpropionate) and peroxide initiators such as benzoyl peroxide are preferable. The addition amount of these polymerization initiators is preferably 0.01 to 20% by mass and more preferably 0.1 to 10% by mass with respect to the total amount of monomers.

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

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

  In the present invention, an organic charge transport material can be used instead of the electrolyte. Charge transport materials include hole transport materials and electron transport materials. Examples of the former include, for example, oxadiazoles disclosed in Japanese Patent Publication No. 34-5466, triphenylmethanes disclosed in Japanese Patent Publication No. 45-555, and Japanese Patent Publication No. 52-4188. Pyrazolines shown in the above, hydrazones shown in JP-B-55-42380, oxadiazoles shown in JP-A-56-123544, etc., JP-A-54-58445 And tetrasylbenzidines disclosed in JP-A No. 58-65440, and stilbenes disclosed in JP-A No. 60-98437. Among them, examples of the charge transport material used in the present invention are shown in JP-A-60-24553, JP-A-2-96767, JP-A-2-183260, and JP-A-2-226160. Particularly preferred are the hydrazones described, and the stilbenes shown in JP-A-2-51162 and JP-A-3-75660. Moreover, these can be used individually or in mixture of 2 or more types.

  On the other hand, examples of the electron transport material 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, 1,3,7-trinitrodibenzothiophene-5,5-dioxide, etc. . These electron transport materials can be used alone or as a mixture of two or more.

  Further, as a sensitizer that further increases the sensitizing effect, a certain kind of electron-withdrawing compound can be added. 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, 4-nitro Aldehydes such as benzaldehyde, ketones such as 9-benzoylanthracene, indandione, 3,5-dinitrobenzophenone, or 3,3 ', 5,5'-tetranitrobenzophenone, phthalic anhydride, 4-chloronaphthalic anhydride Acid anhydrides such as terephthalalmalononitrile, 9-anthrylmethylidenemalononitrile, 4-nitrobenzalmalononitrile, or cyano compounds such as 4- (p-nitrobenzoyloxy) benzalmalononitrile, 3-benzalphthalide , 3- (α-cyano- - Nitorobenzaru) phthalide, or 3- (alpha-cyano -p- Nitorobenzaru) -4,5,6,7 can be mentioned phthalides such as tetrachloro phthalide like.

  When forming a charge transfer layer using these charge transport materials, a resin may be used in combination. When resin is used in combination, polystyrene resin, polyvinyl acetal resin, polysulfone resin, polycarbonate resin, polyester resin, polyphenylene oxide resin, polyarylate resin, acrylic resin, methacrylic resin, phenoxy resin and the like can be mentioned. Among these, polystyrene resin, polyvinyl acetal resin, polycarbonate resin, polyester resin, and polyarylate resin are preferable. These resins may be used alone or as a copolymer in combination of two or more.

  There are two main methods for forming the charge transfer layer. One is a method in which a counter electrode is first pasted on a semiconductor fine particle-containing layer carrying a sensitizing dye, and a liquid charge transfer layer is sandwiched between the opposite electrodes. This is a method of providing a moving layer. In the latter case, the counter electrode is newly added thereafter.

  In the former case, examples of the method for sandwiching the charge transfer layer include a normal pressure process using a capillary phenomenon due to immersion and a vacuum process in which the gas phase is replaced with a liquid phase at a pressure lower than normal pressure. In the latter case, in the wet charge transfer layer, it is necessary to provide a counter electrode without being dried to prevent liquid leakage at the edge portion. In the case of a gel electrolyte, there is a method in which it is applied in a wet manner and solidified by a method such as polymerization. In that case, you may provide a counter electrode after drying and fixing. In addition to the electrolyte solution, the organic charge transport material solution and the gel electrolyte can be applied in the same manner as the semiconductor fine particle-containing layer and the dye, as in the immersion method, roller method, dipping method, air knife method, and extrusion method. , Slide hopper method, wire bar method, spin method, spray method, casting method, various printing methods, and the like.

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

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

  As described above, there are two types of coating of the counter electrode: when applied on the charge transfer layer and when applied on the semiconductor fine particle layer. In any case, the counter electrode material can be appropriately formed on the charge transfer layer or the semiconductor fine particle-containing layer by a technique such as coating, laminating, vapor deposition, or bonding depending on the type of the counter electrode material or the type of the charge transfer layer. When the charge transfer layer is solid, the counter electrode can be formed directly on the charge transfer layer by a technique such as coating, vapor deposition, or CVD.

(Example)
Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to these examples. In addition, all the parts and percentages in the examples are based on mass.

Synthesis Example 1 Synthesis of Exemplified Compound (A- 8 ) Compound (F-1) (1.0 g), cyanoacetic acid (0.40 g) and ammonium acetate (0.13 g) were dissolved in 4.7 g of acetic acid, and 120 ° C. Stir with heat. After 30 minutes, solidify as soon as heating is stopped. After cooling to room temperature, water (50 ml) was added and stirred, and the crystals were collected by filtration. The crystals were transferred to a beaker and washed twice with water (100 ml) and then twice with 2-propanol (50 ml) to give the crude product. This was purified by silica gel column chromatography using chloroform / methanol = 10/1 (volume ratio) to obtain Illustrative Compound (A- 8 ). Absorption spectrum data in methanol: λmax (absorption maximum wavelength) = 425 nm, ε (molar absorption coefficient) = 5.0 × 10 ⁴ mol ⁻¹ · cm ⁻¹

Synthesis Example 2 Synthesis of Exemplary Compound (B-7) Compound (F-2) (1.5 g), cyanoacetic acid (1.1 g), and piperidine (0.5 g) were dissolved in 200 ml of acetonitrile, and the mixture was heated at 82 ° C. for 70 hours. Stir with heating. After cooling the reaction solution to room temperature, the precipitated oil was taken out and washed with 20 ml of acetonitrile. This was purified by silica gel column chromatography using chloroform / methanol = 5/1 (volume ratio) to obtain a piperidine salt of exemplary compound (B-7). Further, this was dissolved in 300 ml of chloroform, washed twice with 100 ml of 1% hydrochloric acid, then washed three times with 100 ml of water, dried over anhydrous magnesium sulfate, and then chloroform was distilled off under reduced pressure to give Example Compound (B-7). Obtained. Absorption spectrum data in DMF: λmax (absorption maximum wavelength) = 390 nm, ε (molar absorption coefficient) = 7.1 × 10 ⁴ mol ⁻¹ · cm ⁻¹

Preparation of Titanium Oxide Film Paint Conditioner (Red Devil) 2 g of titanium oxide (P-25 manufactured by Nippon Aerosil Co., Ltd.), 0.2 g of acetylacetone, and 0.3 g of surfactant (Triton X-100 manufactured by Aldrich) together with 6.5 g of water For 6 hours. Further, 0.2 g of concentrated nitric acid, 0.4 ml of ethanol, and 1.2 g of polyethylene glycol (# 20,000) were added to 4.0 g of this dispersion to prepare a paste. This paste was applied on an FTO glass substrate so as to have a film thickness of 5 μm, dried at room temperature, and then baked at 100 ° C. for 1 hour and further at 500 ° C. for 1 hour to produce a titanium oxide film.

Preparation of Dye Solution 1 Exemplified Compound (A- 8 ) is dissolved in a mixed solution of t-butyl alcohol / acetonitrile (1/1) to prepare Dye Solution 1 having a concentration of Exemplified Compound (A- 8 ) of 0.5 mM. did.

Preparation of dye solution 2 Exemplified compounds (D-1) and (E-1) were dissolved in a mixed solution of t-butyl alcohol / acetonitrile (1/1), and the concentration of the exemplified compound (D-1) was 0.5 mM. A dye solution 2 having a concentration of exemplary compound (E-1) of 1.0 mM was prepared.

The previously prepared titanium oxide film was immersed in the dye solution 1 at room temperature for 90 minutes to perform adsorption treatment of the exemplary compound (A- 8 ). Next, the titanium oxide film on which the exemplified compound (A- 8 ) is adsorbed is immersed in the dye solution 2 at room temperature for 90 minutes to adsorb the exemplified compound (D-1), thereby obtaining two or more kinds of dyes. The semiconductor electrode which adsorb | sucked was produced.

An electrolytic solution was injected into a gap in which a semiconductor electrode adsorbing a dye and a counter electrode were arranged to face each other, to produce a photoelectric conversion element using the semiconductor electrode as a working electrode. The counter electrode is a platinum film formed on a titanium plate by sputtering, and the electrolyte solution is 0.1M lithium iodide, 0.05M iodine, 1,2-dimethyl-3-n-propylimidazolium iodide,. using 3-methoxy propionic nitrile solution 5M. This photoelectric conversion element was irradiated with simulated sunlight (AM1.5, irradiation intensity: 100 mW / cm ² ) from a solar simulator light source (manufactured by Toyo Technica; Solartron SI-1280B) from the working electrode side. The photoelectric conversion characteristics obtained as a result are shown in Table 1. Moreover, this photoelectric conversion element was irradiated with monochromatic light having a wavelength of 300 to 900 nm from the working electrode side in increments of 5 nm, and the dependence of the quantum efficiency on the incident light wavelength was measured. The results are shown in FIG.

The titanium oxide film produced by the same method as in Example 1 was immersed in the dye solution 2 at room temperature for 90 minutes to perform the adsorption treatment of the exemplary compound (D-1). Next, the titanium oxide film on which the exemplary compound (D-1) is adsorbed is immersed in the dye solution 1 at room temperature for 90 minutes to adsorb the exemplary compound (A- 8 ), and two or more types of dyes are absorbed. The semiconductor electrode which adsorb | sucked was produced. Using this semiconductor electrode as a working electrode, a photoelectric conversion element was produced in the same manner as in Example 1, and the photoelectric conversion characteristics were measured. The photoelectric conversion characteristics obtained as a result are shown in Table 1.

Preparation of dye solution 3 Exemplified compound (A- 8 ), exemplified compound (D-1) and exemplified compound (E-1) were dissolved in a mixed solution of t-butyl alcohol / acetonitrile (1/1), and exemplified compound ( A dye solution 3 having a concentration of A- 8 ) of 0.5 mM, a concentration of exemplary compound (D-1) of 0.5 mM, and a concentration of exemplary compound (E-1) of 1.0 mM was prepared.

The titanium oxide film produced by the same method as in Example 1 was immersed in the dye solution 3 at room temperature for 3 hours to adsorb the exemplified compound (A- 8 ) and the exemplified compound (D-1), A semiconductor electrode adsorbing two or more dyes was prepared. Using this semiconductor electrode as a working electrode, a photoelectric conversion element was produced in the same manner as in Example 1, and the photoelectric conversion characteristics were measured. The photoelectric conversion characteristics obtained as a result are shown in Table 1.

(Comparative Example 1)
The titanium oxide film produced by the same method as in Example 1 was immersed in the dye solution 1 at room temperature for 3 hours to perform the adsorption treatment of the exemplified compound (A- 8 ) to produce a semiconductor electrode adsorbing the dye. . Using this semiconductor electrode as a working electrode, a photoelectric conversion element was produced in the same manner as in Example 1, and the photoelectric conversion characteristics were measured. The photoelectric conversion characteristics obtained as a result are shown in Table 1. Moreover, this photoelectric conversion element was irradiated with monochromatic light having a wavelength of 300 to 900 nm from the working electrode side in increments of 5 nm, and the dependence of the quantum efficiency on the incident light wavelength was measured. The results are shown in FIG.

(Comparative Example 2)
A titanium oxide film produced by the same method as in Example 1 was immersed in the dye solution 2 at room temperature for 3 hours to adsorb the exemplified compound (D-1) to produce a semiconductor electrode adsorbed with the dye. did. Using this semiconductor electrode as a working electrode, a photoelectric conversion element was produced in the same manner as in Example 1, and the photoelectric conversion characteristics were measured. The photoelectric conversion characteristics obtained as a result are shown in Table 1. Moreover, this photoelectric conversion element was irradiated with monochromatic light having a wavelength of 300 to 900 nm from the working electrode side in increments of 5 nm, and the dependence of the quantum efficiency on the incident light wavelength was measured. The results are shown in FIG.

Preparation of Dye Solution 4 Exemplified Compound (B-7) is dissolved in a mixed solution of t-butyl alcohol / acetonitrile (1/1) to prepare Dye Solution 4 having a concentration of Exemplified Compound (B-7) of 0.5 mM. did.

Preparation of Dye Solution 5 Exemplary compound (D-3) and (E-1) are dissolved in a mixed solution of t-butyl alcohol / acetonitrile (1/1), and the concentration of exemplary compound (D-3) is 0.5 mM. A dye solution 2 having a concentration of exemplary compound (E-1) of 1.0 mM was prepared.

  The previously prepared titanium oxide film was immersed in the dye solution 4 at room temperature for 90 minutes to perform adsorption treatment of the exemplary compound (B-7). Next, the titanium oxide film on which the exemplified compound (B-7) is adsorbed is immersed in the dye solution 5 at room temperature for 90 minutes to adsorb the exemplified compound (D-3), and then two or more kinds of dyes are adsorbed. The semiconductor electrode which adsorb | sucked was produced.

An electrolytic solution was injected into a gap in which a semiconductor electrode adsorbing a dye and a counter electrode were arranged to face each other, to produce a photoelectric conversion element using the semiconductor electrode as a working electrode. The counter electrode is a platinum film formed on a titanium plate by sputtering, and the electrolyte solution is 0.1M lithium iodide, 0.05M iodine, 1,2-dimethyl-3-n-propylimidazolium iodide,. using 3-methoxy propionic nitrile solution 5M. This photoelectric conversion element was irradiated with artificial sunlight (AM1.5, irradiation intensity 100 mW / cm ² ) from a solar simulator light source from the working electrode side. The photoelectric conversion characteristics obtained as a result are shown in Table 2.

  The titanium oxide film produced by the same method as in Example 1 was immersed in the dye solution 5 at room temperature for 90 minutes to perform the adsorption treatment of the exemplary compound (D-3). Next, the titanium oxide film on which the exemplified compound (D-3) is adsorbed is immersed in the dye solution 4 at room temperature for 90 minutes to adsorb the exemplified compound (B-7), and two or more kinds of dyes The semiconductor electrode which adsorb | sucked was produced. Using this semiconductor electrode as a working electrode, a photoelectric conversion element was produced in the same manner as in Example 1, and the photoelectric conversion characteristics were measured. The photoelectric conversion characteristics obtained as a result are shown in Table 2.

Preparation of dye solution 6 Exemplified compound (B-7), exemplified compound (D-3) and exemplified compound (E-1) were dissolved in a mixed solution of t-butyl alcohol / acetonitrile (1/1), and exemplified compound ( A dye solution 6 having a concentration of B-7) of 0.5 mM, an exemplary compound (D-3) of 0.5 mM, and an exemplary compound (E-1) of 1.0 mM was prepared.

  The titanium oxide film produced by the same method as in Example 1 was immersed in the dye solution 6 at room temperature for 3 hours to adsorb the exemplified compound (B-7) and the exemplified compound (D-3), A semiconductor electrode adsorbing two or more dyes was prepared. Using this semiconductor electrode as a working electrode, a photoelectric conversion element was produced in the same manner as in Example 1, and the photoelectric conversion characteristics were measured. The photoelectric conversion characteristics obtained as a result are shown in Table 2.

(Comparative Example 3)
The titanium oxide film produced by the same method as in Example 1 was immersed in the dye solution 4 at room temperature for 3 hours to perform adsorption treatment of the exemplified compound (B-7) to produce a semiconductor electrode adsorbing the dye. . Using this semiconductor electrode as a working electrode, a photoelectric conversion element was produced in the same manner as in Example 1, and the photoelectric conversion characteristics were measured. The photoelectric conversion characteristics obtained as a result are shown in Table 2.

(Comparative Example 4)
A titanium oxide film produced in the same manner as in Example 1 was immersed in the dye solution 5 at room temperature for 3 hours to adsorb the exemplified compound (D-3) to produce a semiconductor electrode adsorbed with the dye. did. Using this semiconductor electrode as a working electrode, a photoelectric conversion element was produced in the same manner as in Example 1, and the photoelectric conversion characteristics were measured. The photoelectric conversion characteristics obtained as a result are shown in Table 2.

(Comparative Example 5)
Preparation of Dye Solution 7 Exemplified Compound (C-22) was dissolved in a mixed solution of t-butyl alcohol / acetonitrile (1/1) to prepare Dye Solution 7 with a concentration of Exemplified Compound (C-22) of 0.5 mM. did.

  The titanium oxide film produced by the same method as in Example 1 was immersed in the dye solution 7 at room temperature for 90 minutes to perform the adsorption treatment of the exemplary compound (C-22). Next, the titanium oxide film on which the exemplary compound (C-22) is adsorbed is immersed in the dye solution 2 at room temperature for 90 minutes to adsorb the exemplary compound (D-1), thereby obtaining two or more types of dyes. The semiconductor electrode which adsorb | sucked was produced. Using this semiconductor electrode as a working electrode, a photoelectric conversion element was produced in the same manner as in Example 1, and the photoelectric conversion characteristics were measured. The photoelectric conversion characteristics obtained as a result are shown in Table 3.

  (Comparative Example 6)

Preparation of dye solution 8 Exemplified compound (C-22), exemplified compound (D-1) and exemplified compound (E-1) were dissolved in a mixed solution of t-butyl alcohol / acetonitrile (1/1), and exemplified compound ( A dye solution 8 having a concentration of C-22) of 0.5 mM, a concentration of exemplary compound (D-1) of 0.5 mM, and a concentration of exemplary compound (E-1) of 1.0 mM was prepared.

  The titanium oxide film produced by the same method as in Example 1 was immersed in the dye solution 8 at room temperature for 3 hours to adsorb the exemplified compound (C-22) and the exemplified compound (D-1). A semiconductor electrode adsorbing two or more dyes was prepared. Using this semiconductor electrode as a working electrode, a photoelectric conversion element was produced in the same manner as in Example 1, and the photoelectric conversion characteristics were measured. The photoelectric conversion characteristics obtained as a result are shown in Table 3.

(Comparative Example 7)
The titanium oxide film produced by the same method as in Example 1 was immersed in the dye solution 7 at room temperature for 3 hours to perform the adsorption treatment of the exemplified compound (C-22) to produce a semiconductor electrode adsorbing the dye. . Using this semiconductor electrode as a working electrode, a photoelectric conversion element was produced in the same manner as in Example 1, and the photoelectric conversion characteristics were measured. The photoelectric conversion characteristics obtained as a result are shown in Table 3.

  In addition, the maximum absorption wavelength of the absorption spectrum in methanol of exemplary compound (C-22) was 532 nm.

  As shown in Tables 1 and 2, at least one of the two or more dyes adsorbed on the surface of the semiconductor layer coated on the conductive substrate is represented by General Formula (1) or General Formula (2). A photoelectric conversion element using a semiconductor film composed of a compound showed better photoelectric conversion characteristics than a photoelectric conversion element using a semiconductor film in which each compound was adsorbed alone. The synergistic effect of the combined use of two or more dyes of the present invention is clear. According to the present invention, it has become possible to provide a high-efficiency photoelectric conversion element excellent in the incident light wavelength dependency of quantum efficiency.

  As shown in Table 3, a photoelectric conversion element using a semiconductor film composed of a combination of dyes other than those described in the present invention is more photoelectrical than a photoelectric conversion element using a semiconductor film adsorbing each compound alone. It is clear that the conversion efficiency is inferior.

   As an application example of the present invention, a dye-sensitized solar cell excellent in photoelectric conversion efficiency can be mentioned.

The figure which showed the incident light wavelength dependence of the quantum yield of the photoelectric conversion element obtained in Example 1, the comparative example 1, and the comparative example 2. FIG.

Claims (3)

In a semiconductor electrode composed of a substrate having conductivity on the surface, a semiconductor layer covering the conductive surface, and two or more dyes carried on the surface of the semiconductor layer, at least one of the dyes is: It is a dye having a maximum absorption wavelength of an absorption spectrum in a solution dissolved in an organic medium at 350 nm or more and 500 nm or less, and at least one of the other dyes is a dye having a maximum absorption wavelength at 500 nm or more and 700 nm or less. The dye having a maximum absorption wavelength of 350 nm or more and 500 nm or less is at least one selected from the dyes represented by the following general formula (1) and general formula (2), and the maximum absorption wavelength is 500 nm or more and 700 nm or less. A semiconductor electrode, wherein the dye having a ruthenium complex.

(In the general formula (1), R ₁ represents an aryl group and may have a substituent. R ₂ is a linkage that forms a cyclic structure by bonding to a nitrogen atom and a benzene ring adjacent to the nitrogen atom. indicates group, cyclic structure is a five-membered ring .R ₃ is shown to .l hydrogen atom is 0 carbon -. carbon double bond, E, be any one of Z-type good .R ₄ is shown to .R ₅ hydrogen atom is a substituent of an oxygen atom, a water MotoHara child.)

In (formula (2), R ₆ and R ₁₀ is a nitrogen atom, bonded to the benzene ring adjacent to the nitrogen atom indicates a linking group which forms a cyclic structure, the cyclic structure is a 5-membered ring. R ₇ and _{R 11} is 0 is shown to .m and n hydrogen atom carbon -. carbon double bond, E, good .R ₈ and _{R 12} be either a Z-type hydrogen atoms the shown to .Ar ₁ and Ar ₂ child indicates 1,4-phenylene group, _{L 4} represents a divalent linking group represented by -SCH ₂ CH ₂ S-, p is an .R ₉ showing a 1 R ₁₃ is a substituent of an oxygen atom, a water MotoHara child.) Metal chalcogenide whose semiconductor is selected from titanium, tin, zinc, iron, copper, tungsten, zirconium, hafnium, niobium, tantalum, cadmium, lead, silver, antimony, bismuth, molybdenum, aluminum, gallium, chromium, cobalt, nickel The semiconductor electrode according to claim 1, comprising at least one of the above. A photoelectric conversion element comprising the semiconductor electrode according to claim 1.

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