JP2005093370A - Photosensitized solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitized solar cell using a gelled electrolyte layer, capable of easily gelling and having high photoelectric conversion characteristics. <P>SOLUTION: The photosensitized solar cell is equipped with a semiconductor electrode carrying pigment on the surface; facing substrates separately faced in the semiconductor electrode and having a conductive layer on the surface: and an electrolyte layer interposed between the semiconductor electrode and the conductive layer and comprising iodine molecules, a molten salt of iodide, a carboxylic acid compound, and a gelling agent. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photosensitized solar cell.

  As a general photosensitized solar cell, an electrode (semiconductor electrode) composed of a semiconductor layer made of fine metal oxide particles having a dye supported thereon, a transparent electrode facing this electrode, 2 Some have a liquid electrolyte layer interposed between two electrodes. Such a solar cell is called a wet photosensitized solar cell because the electrolyte layer is liquid.

  The photosensitized solar cell as described above operates through the following process. That is, the light incident from the transparent electrode side reaches the dye carried on the surface of the semiconductor layer and excites this dye. The excited dye quickly passes electrons to the semiconductor layer. On the other hand, the positively charged dye by losing electrons is electrically neutralized by receiving electrons from ions diffused from the electrolyte layer. The ions that have passed the electrons diffuse to the transparent electrode and receive the electrons. The wet photosensitized solar cell operates by using the semiconductor electrode and the transparent electrode facing the semiconductor electrode as a negative electrode and a positive electrode, respectively.

  In wet photosensitized solar cells, the surface of the semiconductor layer is treated with a basic compound to suppress the backflow of electrons transferred into the semiconductor layer made of titanium oxide, thereby increasing the open-circuit voltage and improving the photoelectric conversion efficiency. A method has been proposed (see, for example, Patent Document 1).

  In addition, as a method for increasing the current density of a wet photosensitized solar cell, it has been proposed to add acetic acid as an acidic substance to an organic solvent-based electrolyte layer of acetonitrile (see, for example, Non-Patent Document 1). .

  By the way, a low-molecular solvent is used in the wet photosensitized solar cell, and it is necessary to strictly shield in order to prevent the solvent from leaking. However, it is difficult to maintain a shield for many years, and there is a concern about deterioration of device functions and environmental influences due to solvent evaporation due to evaporation of solvent molecules and liquid leakage. For this reason, it has been proposed to use an electrolyte layer containing a liquid electrolyte (molten salt) containing an imidazolium salt in place of the liquid electrolyte layer (see, for example, Patent Document 2). By using such a solar cell, there is no problem such as volatilization of the organic solvent, so that an effect of high long-term stability can be obtained.

Furthermore, by gelling the electrolyte layer of the photosensitized solar cell containing the above-described molten salt, long-term stability is further increased because it traps volatile iodine. However, when the electrolyte layer is gelled using a conventional material, there is a problem that gelation is difficult. This has led to a deterioration in the characteristics of the entire solar cell.
Japanese Patent Laid-Open No. 2002-93476 (page 3-7, FIG. 1) J. Electrochem. Soc., 147, 3049 (2000) JP 2002-289268 A (page 3-14, FIG. 1)

  As described above, there is a problem that gelation of the electrolyte layer of the photosensitized solar cell is difficult.

  In view of this problem, an object of the present invention is to provide a photosensitized solar cell using a gel electrolyte layer that can be easily gelled and has high photoelectric conversion characteristics.

  Therefore, the present invention provides a semiconductor electrode having a dye supported on the surface, a counter substrate that is disposed opposite to the semiconductor electrode and has a conductive layer on the surface, and is sandwiched between the semiconductor electrode and the conductive layer. Provided is a photosensitized solar cell comprising an electrolyte layer comprising a molten salt of iodide, a carboxylic acid compound, and a gelling agent.

  In the present invention, the carboxylic acid compound may be at least one selected from acetic acid and benzoic acid.

  In the present invention, the electrolyte layer may further contain an amine compound having a pka value of 4 or less. Furthermore, in the present invention, the amine compound may be a heteroaromatic compound.

  In the present invention, the electrolyte layer may further contain water.

  According to the present invention, it is possible to provide a photosensitized solar cell using a gel electrolyte layer that can be easily gelled and has high photoelectric conversion characteristics.

  Hereinafter, embodiments of the present invention will be described in detail.

  The photosensitized solar cell of the embodiment of the present invention includes iodine molecules, a molten salt of iodide, a carboxylic acid compound, and a gelling agent in the electrolyte layer. The reason why the photosensitized solar cell of the embodiment of the present invention needs to be composed of these is shown below.

  As described above, although the photosensitized solar cell using the electrolyte layer containing a molten salt has high long-term stability, there is a problem that gelation is difficult when gelling. The present inventors have found that this problem is because LiI contained in the electrolyte for forming the ionic component forms a complex with the gelling agent to inhibit gelation. Therefore, as a result of investigating the photoelectric conversion efficiency and the gelation state using various materials, it was found that when the carboxylic acid compound was added, the ionic component could be supplied without inhibiting the gelation. It was.

  Further, when an amine compound having a pka value of 4 or less is added in addition to the carboxylic acid compound, the following effects can be obtained. That is, as described above, acetic acid also has the effect of increasing the current density, but when only acetic acid is added, the open circuit voltage decreases. In addition, when an amine compound having a pka value of 4 or less is added, the amine compound is adsorbed on the surface of the semiconductor electrode to which no dye is adsorbed, whereby electrons once injected into the semiconductor are absorbed in the electrolyte layer. The reverse electron reaction that leaks into the substrate can be prevented, but the current density decreases. However, when both a carboxylic acid compound and an amine compound having a pka value of 4 or less are added, an increase in current density can be obtained without lowering the open circuit voltage. Moreover, since the amine compound whose pka value is 4 or less does not inhibit gelation like the carboxylic acid compound, it can be preferably applied to this embodiment.

  Next, the electrolyte layer used in the photosensitized solar cell according to the embodiment of the present invention will be described in detail.

The electrolyte used in the embodiment of the present invention contains iodine (I) and includes a reversible redox pair consisting of I ⁻ and I ₃ ⁻ . The reversible redox _couple can be supplied from a mixture of iodine molecules (I ₂ ) and a molten salt of iodide.

  The redox couple as described above desirably exhibits a redox potential smaller by about 0.1 to 0.6 V than the oxidation potential of the dye described later. In the redox pair showing a redox potential 0.1 to 0.6 V lower than the oxidation potential of the dye, for example, a reducing species such as I- can receive holes from the oxidized dye. By containing such a redox pair in the electrolyte, the speed of charge transport between the semiconductor electrode and the conductive layer can be increased, and the open-circuit voltage can be increased.

  Examples of the molten salt of iodide include iodides of heterocyclic nitrogen-containing compounds such as imidazolium salts, pyridinium salts, quaternary ammonium salts, pyrrolidinium salts, pyrazolidium salts, isothiazolidinium salts, isoxazolidinium salts, etc. Can be used.

  Examples of the molten salt of iodide include 1-methyl-3-propylimidazolium iodide, 1,3-dimethylimidazolium iodide, 1-methyl-3-ethylimidazolium iodide, 1-methyl-3- Pentylimidazolium iodide, 1-methyl-3-isopentylimidazolium iodide, 1-methyl-3-hexylimidazolium iodide, 1,2-dimethyl-3-propylimidazole iodide, 1-ethyl-3- Isopropylimidazolium iodide, 1-propyl-3-propylimidazolium iodide, pyrrolidinium iodide, ethylpyridinium iodide, butylpyridinium iodide, hexylpyridinium iodide, trihexylmethylammonium eye And the like can be given iodide. Such a molten salt of iodide can be used alone or in combination of two or more selected from the aforementioned types. Among these, 1-methyl-3-propylimidazolium iodide is preferably used because of its low viscosity and high hole diffusion rate.

  The electrolyte phase according to the embodiment of the present invention includes a carboxylic acid compound and a gelling agent in addition to such a molten salt of iodine molecules and iodide.

First, carboxylic acid compounds include formic acid, acetic acid, chloroacetic acid, dichloroacetic acid, fluoroacetic acid, trimethylacetic acid, methoxyacetic acid, mercaptoacetic acid, trichloroacetic acid, 1,3-phenylenediacetic acid, 1,4-phenylenediacetic acid, 4 -Carboxyphenylacetic acid, 2,5-dihydroxy-1,4-benzenediacetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, palmitic Acid, myristic acid, stearic acid, ascorbic acid, abietic acid, adamantane carboxylic acid, 1-adamantane carboxylic acid, isovaleric acid, pipecolic acid, pyruvic acid, glyoxylic acid, thioglycolic acid, lauric acid, lactic acid, mandelic acid, mercapto Acetic acid, glycolic acid, phenylacetic acid, cyclo Aliphatic saturated carboxylic acids such as xanthcarboxylic acid and oxalic acid, acrylic acid, methacrylic acid, acetylenedicarboxylic acid, abscisic acid, oleic acid, crotonic acid, sorbic acid, propiolic acid, linolenic acid, oleic acid, ascorbic acid, linoleic acid , Aliphatic unsaturated carboxylic acids such as undecylenic acid, natural unsaturated fatty acids such as linseed oil, soybean oil, adipic acid, aspartic acid, glutamic acid, acetone dicarboxylic acid, malic acid, tartaric acid, oxalic acid, 1,4-butanedicarboxylic acid Acid, 1,6-hexanedicarboxylic acid, 1,8-octanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,10-decanedicarboxylic acid, malonic acid, phenylmalonic acid, benzyl Malonic acid, maleic acid, butylmalonic acid, citramalic acid, glutamic acid Aliphatic saturated dicarboxylic acids such as phosphoric acid, phenylglutaric acid, suberic acid, sebacic acid, citric acid (3), aliphatic unsaturated dicarboxylic acids such as succinic acid, citraconic acid, fumaric acid, benzoic acid, 3, 3 '-Methylene dibenzoic acid, 4,4'-methylene dibenzoic acid, 4,4'-oxydibenzoic acid, 4,4'-thiodibenzoic acid, 3,3'-carbonyl dibenzoic acid, 4,4 '-Carbonyldibenzoic acid, 4,4'-sulfonyldibenzoic acid, o-chlorobenzoic acid, m-chlorobenzoic acid, p-chlorobenzoic acid, o-bromobenzoic acid, m-bromobenzoic acid, p-bromo Benzoic acid, o-nitrobenzoic acid, m-nitrobenzoic acid, p-nitrobenzoic acid, 2-acetylbenzoic acid, methoxybenzoic acid, p-hydroxybenzoic acid, anthranilic acid, m-aminobenzoic acid, p-aminobenzoic acid acid o-methoxybenzoic acid, m-methoxybenzoic acid, p-methoxybenzoic acid, o-aminobenzoic acid, o-toluic acid, m-toluic acid, p-toluic acid N-acetylanthranilic acid, salicylic acid, cinnamic acid, Hippuric acid, penicillic acid, indole-2-carboxylic acid, 3-indoleacetic acid, 3-indolebutyric acid, 3-indoleacrylic acid, indole-3-propionic acid, citrazic acid, nicotinic acid, picolinic acid, benzylic acid, gallic acid Aromatic carboxylic acids such as isonicotinic acid and salicylic acid, phthalic acid, isophthalic acid, terephthalic acid, homophthalic acid, 2-hydroxyterephthalic acid, 5-hydroxyisophthalic acid, 4-hydroxyisophthalic acid, 2-hydroxyisophthalic acid, 4 , 6-Dihydroxyisophthalic acid, 1,2,4-benzenetricarboxylic acid Examples include acids, aromatic dicarboxylic acids such as 4,4′-biphenyldicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid. It is not limited. In addition, these may be used alone or in combination. Of these, acetic acid and benzoic acid can be particularly preferably used because of their small molecular size.

  As the gelling agent, for example, a compound having two or more nitrogen-containing heterocyclic groups and a compound containing two or more halogen-containing groups capable of forming an onium salt can be used.

  By using two or more halogen-containing groups capable of forming an onium salt, an onium salt-type cross-linked structure can be formed between compounds having two or more nitrogen-containing heterocyclic groups. The electrolyte composition can be gelled by the onium salt.

As the compound containing two or more halogen-containing groups capable of forming an onium salt, an organic halide is preferable. Organic halides are preferred because they easily form onium salts and can be crosslinked to increase the crosslinking density. The halogen-containing compound preferably has 2 or more halogen atoms per molecule. In such a compound, different halogen atoms may be present in one molecule and the total number of halogen atoms may be 2 or more, but two or more of one kind of halogen atom may be present in one molecule. When the number of halogen atoms per molecule is one, the degree of polymerization of the polymer obtained from the element A-containing compound and the halogen-containing compound described above may be low, and gelation of the electrolyte composition may be difficult. There is. The number of halogen atoms per molecule is more preferably 2 or more and 1,000,000 or less. Examples of the halogen-containing compound having 2 or more halogen atoms per molecule include dibromomethane, dibromoethane, dibromopropane, dibromobutane, dibromopentane, dibromohexane, dibromoheptane, dibromooctane, dibromononane, dibromodecane, Dibromoundecane, dibromododecane, dibromotridecane, dichloromethane, dichloroethane, dichloropropane, dichlorobutane, dichloropentane, dichlorohexane, dichloroheptane, dichlorooctane, dichlorononane, dichlorodecane, dichloroundecane, dichlorododecane, dichlorotridecane, diiodomethane, Diiodoethane, diiodopropane, diiodobutane, diiodopentane, diiodohexane, diiodoheptane, diiodoocta , Diiodononane, diiododecane, diiodoundecane, diiodododecane, diiodotridecane, 1,2,4,5-tetrakisbromomethylbenzene, epichlorohydrin oligomer, epibromohydrin oligomer, hexabromocyclododecane, tris ( 3,3-dibromo-2-bromopropyl) isocyanuric acid, 1,2,3-tribromopropane, diiodobarfluoroethane, diiodoperfluoropropane, diiodoperfluorohexane, polyepichlorohydrin, polyepichlorohydrin and polyethylene ether And polyfunctional halides such as polyepibromohydrin and polyvinyl chloride. These halides can be used alone or in combination of two or more.

The skeleton of the main chain of the compound having two or more nitrogen-containing heterocyclic groups is not particularly limited, and is a divalent having at least one atom selected from the group consisting of a carbon atom, an oxygen atom, a sulfur atom, and an oxygen atom. Any organic group may be used, and examples thereof include an alkylene group, an arylene group, a carbonyl group, an ether group, an ester group and the like, or an organic group composed of a combination of these organic groups. As the alkylene group, — (CH ₂ ) _n — (n = 1 to an integer of 1 to 10), —CH ₂ CH (CH ₃ ) —, —CH (CH ₃ ) CH (CH ₃ ) —, —CH ₂ CH ( Examples thereof include a linear or branched alkylene group having 1 to 10 carbon atoms, such as CH ₃ ) CH ₂ —. Arylene groups include phenylene, butylene, anthracenylene, biphenylene, triphenylene, stilbenylene, naphenylene, and aromatic ring substituents such as alkyl groups (methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl), alkoxy groups ( Methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, t-butoxy), halogen atoms (F, Cl, Br, I), nitro, cyano, hydroxy and the like. Further examples include polymers such as polyethylene, polyester, polycarbonate, polymethyl methacrylate, polyacrylonitrile, polyamide, and polyethylene terephthalate.

  Examples of the nitrogen-containing heterocyclic substituent include a pyroyl group, an imidazolyl group, a pyrazoyl group, an isothiazoyl group, an isoxazoyl group, a pyridyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an indolizinyl group, an isoindoyyl group, an indoyl group, and an isoazoyl group. , Purinyl group, quinolinidinyl group, isoquinoyl group, quinoyl group, phthalazinyl group, naphthyridinyl group, quinoxaquinidyl group, quinoxaxolinyl group, sininoyl group, ferridinyl group, carbazole group, carbolinyl group, phenanthridinyl group, actinyl group, perimidyl Group, phenanthryl group, phenazinyl group, phenothiazinyl group, firazanyl group, phenoxazinyl group, pyrrolidinyl group, pyrrolinyl group, imidazolidinyl group, imidazolinyl group, pyrarizo Examples thereof include a dinyl group, a pyrazolinyl group, a piperidyl group, a piperazinyl group, an indolinyl group, an isoindolinyl group, a quinuclidinyl group, a morpholinyl group, a 1-methylimidazolyl group, a 1-ethylimidazolyl group, and a 1-propylimidazolyl group. . In addition, as the substituent, a spiro ring composed of one or more nitrogen-containing heterocyclic substituents selected from the aforementioned types, and two or more nitrogen-containing heterocyclic substitutions selected from the aforementioned types An aggregate of groups (heterocyclic aggregate) or the like may be used.

  Examples of the compound having two or more nitrogen-containing heterocyclic groups include polyvinylimidazole, poly (4-vinylpyridine), polybenzimidazole, bipyridyl, terpyridyl, polyvinylpyrrole, 1,4-di (4-pyridyl) butane. , 2- (4-pyridyl) ethyl ether, compounds (a) to (e) shown in the following (Chemical Formula 1), and the like.

  In the embodiment of the present invention, the electrolyte may further contain an amine compound having a pka value of 4 or less.

  As an amine compound having a pka value of 4 or less, an aliphatic or alicyclic heteroparaffin compound, an aromatic, heteroaromatic, polyether, or polyamide amine compound is used. I can do it.

For example, secondary or tertiary aliphatic polyamines such as ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, 3-diaminocyclohexane, 1,4-diaminocyclohexane, bis (4- Aminocyclohexyl) methane, bis (4-amino-3-methylcyclohexyl) methane, isophoronediamine, norbornanediamine and other secondary or tertiary alicyclic polyamines, diaminodiphenylmethane, m-phenylenediamine, m-xylylenediamine Secondary or tertiary aromatic polyamines such as secondary, tertiary polyetheramines such as polyoxypropylenediamine and polyoxypropylenetriamine, and amino groups at the molecular ends of the polyamide. Secondary or tertiary polyamidoamines, aniline, N-methylaniline, N, N'-dimethylaniline, methyl substituted aniline in any of o, m, p positions, any of o, m, p positions In addition to primary to tertiary aromatic amines represented by aniline compounds such as hydroxy-substituted aniline, pyridine, methyl-substituted pyridine at any of the 2,3,4 positions, benzopyridine, iso-benzopyridine, 2- Fluoropyridine, 3
-Fluoropyridine, 2-chloropyridine, 3-chloropyridine, 2-bromopyridine, 3-bromopyridine, 2-iodopyridine, 3-iodopyridine, 2,6-di-t-butylpyridine, 3-acetylpyridine, etc. Pyridine derivatives such as pyridine derivatives, quinoline derivatives such as 3-chloroquinoline, 4-chloroquinoline, 7-chloroquinoline and 8-aminoquinoline, isoquinoline derivatives such as 1-methoxyisoquinoline, 9-methoxyphenanthridine and the like 6-membered aromatic heterocyclic compounds containing one hetero nitrogen atom typified by phenanthridine derivatives, pyridazines such as pyridazine, 3-methylpyridazine, 4-methylpyridazine, 3-methoxypyridazine, 4-methoxypyridazine Derivatives, pyrimidine, 4-methylpyrimidine, 2-amino Pyrimidine derivatives such as rimidine, 2-dimethylaminopyrimidine, 5-aminopyrimidine, 4-methoxypyrimidine, pyrazine, 2-methylpyrazine, 2,3,5,6-tetramethylpyrazine, 2-aminopyrazine, 2-methoxy Pyrazine derivatives such as pyrazine, phthalazine derivatives, quinazoline derivatives, quinoxaline derivatives, phenazine, phenanthroline, 6-membered aromatic heterocyclic compounds containing two hetero nitrogen atoms, 1,4,5-triazanaphthalene, 1,4,4 6-Triazanaphthalene and other aromatic heterocycles containing three hetero nitrogen atoms typified by triazanaphthalene derivatives, pyrrole, 2- and 3-position substituted methyl pyrrole, hetero- typified by iso-pyrrole, etc. 5-membered aromatic heterocyclic compounds containing one nitrogen atom, 2-imidazoline, 3-i Imidazoles such as dazoline, 4-imidazoline, pyrazole, imidazole, 2-methylimidazole, 1,2-dimethylimidazole, 2-methyl-4-methylimidazole, 2-ethyl-4-ethylimidazole, 2-phenylimidazole ) 5-membered aromatic heterocyclic compounds containing 2 heteronitrogen atoms typified by compounds, indazole compounds, etc., 5-heterocyclic heterocyclization of 2 heteronitrogen atoms typified by imidazolidine, etc. Heteroaromatic compounds such as compounds and purine compounds can be exemplified, but the invention is not limited thereto. In addition, these may be used alone or in combination. Of these, heteroaromatic compounds having a pKa in the range of 4 or less can be particularly preferably used because they are easily dissolved in the molten salt electrolyte.

  Moreover, in embodiment of this invention, you may contain water further in the electrolyte layer containing molten salt, a carboxylic acid compound, and a gelatinizer. The electrolyte containing water can increase the energy conversion efficiency of the photosensitized solar cell.

  The content of water in the electrolyte layer is preferably 10% by weight or less when the total amount of the molten salt of iodide and water is 100% by weight because the hydrolysis reaction of the dye does not occur. . The more preferable range of the water content is 0.01% by weight or more and 10% by weight or less when the total amount of the molten salt of iodide and water is 100% by weight, and the most preferable range is 100% by weight. It is 0.5 weight% or more and 5 weight% or less with respect to weight%.

Furthermore, in the embodiment of the present invention, a dye adsorbed on the surface of the semiconductor electrode may be added and dissolved in the electrolyte layer. The solubility of the dye is preferably about the saturation solubility. However, since the dye is generally difficult to dissolve in the electrolyte solution, it may be less than the saturation solubility, and the dissolution concentration is 5 × 10 ⁻⁶ mol / L or more, and further 5 × 10. If it is set to ^-5 mol / L or more, it is preferable that the dye attached to the semiconductor electrode hardly dissolves into the electrolyte layer. If the concentration of the dye in the electrolyte layer is too large, light may not be used effectively, which is not preferable.

  Next, an embodiment of a photosensitized solar cell using this electrolyte layer will be described.

In this embodiment, a substrate having a light receiving surface, a transparent conductive layer formed on one surface of the substrate, a semiconductor electrode formed on the transparent conductive layer and having a dye adsorbed on the surface, and a semiconductor electrode And a conductive layer (opposite electrode) formed on the surface of the counter substrate facing the semiconductor electrode, between the conductive layer and the semiconductor electrode, iodine molecules, molten salt of iodide, carvone It has an electrolyte having an acid compound and a gelling agent, and has a structure in which sunlight enters from a substrate.

  Note that the counter substrate and the counter electrode can have a structure in which sunlight is incident from the counter electrode side by using a transparent material with little visible light region absorption.

Hereinafter, the transparent conductive layer, the semiconductor electrode, the dye, the counter substrate, and the conductive layer will be described.
(A) Transparent conductive layer It is preferable that the transparent conductive layer has little absorption in the visible light region and has conductivity. The transparent conductive layer is preferably a tin oxide film doped with fluorine or indium, or a zinc oxide film doped with fluorine or indium. Further, from the viewpoint of improving conductivity and preventing an increase in resistance, it is desirable to wire a low-resistance metal matrix in combination with the transparent conductive layer.
(A) Semiconductor electrode The semiconductor electrode is preferably composed of a transparent semiconductor with little absorption in the visible light region. As such a semiconductor, a metal oxide semiconductor is preferable. Specifically, oxides of transition metals such as titanium, zirconium, hafnium, strontium, zinc, indium, yttrium, lanthanum, vanadium, niobium, tantalum, chromium, molybdenum or tungsten, SrTiO ₃ , CaTiO ₃ , BaTiO ₃ , MgTiO _{3 3} , perovskites such as SrNb ₂ O ₆ , composite oxides or mixtures of these oxides, and GaN.
(C) Dye As the dye adsorbed on the surface of the semiconductor electrode, for example, ruthenium-tris transition metal complex, ruthenium-bis transition metal complex, osmium-tris transition metal complex, osmium-bis type Examples include transition metal complexes, ruthenium-cis-diaqua-bipyridyl complexes, phthalocyanines, porphyrins, and the like.
(D) Counter substrate The counter substrate preferably has little absorption in the visible light region and has conductivity. The counter substrate is preferably a tin oxide film or a zinc oxide film.
(E) Conductive layer This conductive layer can be formed from metals, such as platinum, gold | metal | money, and silver, for example. By reducing the thickness of these conductive layers, a transparent conductive layer with little absorption in the visible light region can be obtained.

  You may manufacture the photosensitized solar cell of embodiment of this invention by the method demonstrated below, for example.

  First, a substrate having a light receiving surface is prepared, and a transparent conductive layer and a semiconductor electrode are sequentially formed on one surface thereof. Then, a dye and a carboxylic acid compound are sequentially adsorbed on the surface of the semiconductor electrode. On the other hand, a counter substrate having a conductive layer provided on the surface is prepared, and the battery unit is assembled by disposing the conductive layer and the above-described semiconductor electrode so as to face each other.

  Next, an electrolyte is injected into the gap between the semiconductor electrode and the conductive layer to form an electrolyte layer. Moreover, since this embodiment makes it a gel-like electrolyte layer, an electrolyte precursor is gelatinized. Subsequently, the photosensitized solar cell of the embodiment of the present invention is obtained by sealing the battery unit.

In order to obtain a gel electrolyte layer, it is preferable to heat the battery unit when the electrolyte precursor is gelled. It is preferable that the temperature of heat processing shall be in the range of 50-200 degreeC. This is due to the following reason. That is, when the heat treatment temperature is lower than 50 ° C., the degree of polymerization of the gel is lowered, and it may be difficult to form a gel. On the other hand, when heat treatment is performed at a high temperature exceeding 200 ° C., the decomposition of the dye is likely to occur. More preferably, the heat treatment temperature is 70 to 150 ° C.

Hereinafter, specific examples will be described in more detail with reference to the drawings.
(Example 1)
As a material for the n-type semiconductor electrode, nitric acid was added to high-purity titanium oxide (anatase) powder having an average primary particle size of 30 nm, and then kneaded with pure water and further stabilized with a surfactant.

  As shown in FIG. 1 (a), a fluorine-doped tin oxide conductive film 2 (transparent conductive film 2) is provided on a glass substrate 1, and this paste is printed by screen printing on the glass substrate 1, and heat treated at a temperature of 450 ° C. As a result, an n-type semiconductor electrode 4 having a thickness of 2 μm made of titanium oxide (anatase) particles was formed.

  This screen printing and heat treatment are repeated a plurality of times, and finally an n-type semiconductor electrode 4 including titanium oxide particles 3 made of anatase phase having a thickness of 8 μm is formed on the fluorine-doped tin oxide conductive film 2 (transparent conductive film 2). did. The roughness factor of the n-type semiconductor electrode 4 was 1500. The roughness factor was obtained from the nitrogen adsorption amount with respect to the projected area of the substrate.

Next, a 3 × 10 ⁻⁴ M dry ethanol solution of cis-bis (ciocyanato) -N, N-bis (2,2′-dipyridyl-4,4′-dicarboxylic acid) -ruthenium (II) dihydrate) After being immersed in (temperature of about 80 ° C.) for 4 hours, the surface of the n-type semiconductor electrode 4 was supported with a ruthenium complex as a pigment by pulling it up in an argon stream.

  Further, a glass substrate 6 (counter electrode 6) on which a fluorine-doped tin oxide electrode 5 (conductive film 5) with platinum is formed is used as a substrate on which the above-described n-type semiconductor electrode 4 is produced using a spacer having a diameter of 30 μm. 1 was installed, and the periphery was fixed with epoxy resin 7 while leaving the electrolyte injection port.

  Through the above operation, a photoelectric conversion element unit as shown in FIG. 1A was obtained.

  The electrolyte was prepared as follows. In 1 g of 1-methyl-3-propylimidazolium iodide, 0.05 g of water, 0.05 g of iodine, 0.1 g of pyrazine, and 0.01 g of acetic acid were dissolved to prepare an electrolyte. To this electrolyte, 0.02 g of polyvinylpyridine (molecular weight 60,000) and 0.023 g of 1,6-dibrohexane were added as gelling agents to obtain an electrolyte composition.

  Subsequently, as shown in FIG.1 (b), the electrolyte composition 9 was inject | poured into the opening part of the photoelectric conversion unit from the injection port 8. FIG. As shown in FIG. 1C, the electrolyte 9 penetrated the n-type semiconductor electrode 4 and was also injected between the n-type semiconductor electrode 4 and the tin oxide electrode 5 (conductive layer 5).

  Subsequently, as shown in FIG. 1 (d), after the opening of the photoelectric conversion unit is sealed with the epoxy resin 10, it is heated on a hot plate at 60 ° C. for 30 minutes, whereby the photoelectric conversion element, that is, photosensitization. Type solar cells were manufactured. A cross-sectional view of the obtained solar cell is shown in FIG.

As shown in FIG. 2, a transparent conductive layer 2 and a transparent n-type semiconductor electrode 4 are sequentially formed on the glass substrate 1. Since the n-type semiconductor electrode 4 is formed from an aggregate of the fine particles 3, the surface area is extremely large. Further, a single molecule is adsorbed on the surface of the n-type semiconductor electrode 4. A portion of the surface of the n-type semiconductor electrode 4 where no pigment is formed is covered with pyrazine. One counter substrate 6 includes a glass substrate 6 and a conductive layer 5 formed on the surface of the glass substrate 6 on the n-type semiconductor electrode 4 side. In such a photosensitized solar cell, the light 11 incident from the glass substrate 1 side is absorbed by the dye adsorbed on the surface of the n-type semiconductor electrode 4, and then the dye supplies electrons to the n-type semiconductor electrode 4. At the same time, the dye passes holes to the gel electrolyte 9 to perform photoelectric conversion.
(Example 2)
A dye-sensitized solar cell having the same configuration as that described in Example 1 was manufactured except that pyrimidine was used instead of pyrazine.
Example 3
Except for using pyridazine instead of pyrazine, a dye-sensitized solar cell having the same structure as described in Example 1 was manufactured.
Example 4
Except for using pyrazole instead of pyrazine, a dye-sensitized solar cell having the same configuration as that described in Example 1 was manufactured.
(Example 5)
A dye-sensitized solar cell having the same configuration as that described in Example 1 was produced except that 3-fluoropyridine was used instead of pyrazine.
(Example 6)
A dye-sensitized solar cell having the same structure as that described in Example 1 was produced except that 1,2,4,5-tetrakis (bromomethyl) was used instead of 1,6-dibromohexane.
(Example 7)
A dye-sensitized solar cell having the same configuration as that described in Example 6 was produced except that benzoic acid was used instead of acetic acid.
(Example 8)
Except for using pyrimidine instead of pyrazine, a dye-sensitized solar cell having the same configuration as that described in Example 6 was manufactured.
Example 9
A dye-sensitized solar cell having the same structure as that described in Example 8 was produced except that benzoic acid was used instead of acetic acid.
(Example 10)
A dye-sensitized solar cell having the same configuration as that described in Example 8 was prepared except that fluoroacetic acid was used instead of acetic acid.
(Example 11)
A dye-sensitized solar cell having the same configuration as that described in Example 8 was produced except that butanoic acid was used instead of acetic acid.
(Example 12)
A dye-sensitized solar cell having the same configuration as that described in Example 8 was produced except that adipic acid was used instead of acetic acid.
(Example 13)
A dye-sensitized solar cell having the same configuration as that described in Example 1 was manufactured except that salicylic acid was used instead of acetic acid.
(Example 14)
A dye-sensitized solar cell having the same configuration as that described in Example 6 was manufactured except that water was not added.
(Example 15)
A dye-sensitized solar cell having the same configuration as that described in Example 9 was prepared except that water was not added.
(Example 16)
A dye-sensitized solar cell having the same configuration as that described in Example 8 was prepared except that pyrimidine was not added.
(Comparative Example 1)
A dye-sensitized solar cell having the same structure as that described in Example 1 was produced except that 0.02 g of t-butylpyridine was used instead of pyrazine.
(Comparative Example 2)
Except for not adding acetic acid, a dye-sensitized solar cell having the same structure as described in Example 1 was manufactured.
(Comparative Example 3)
A dye-sensitized solar cell having the same configuration as that described in Example 9 was prepared except that benzoic acid was not added.
(Comparative Example 4)
Lithium iodide 0.5M and iodine 0.05M were dissolved in propylene carbonate to prepare an electrolyte. A dye-sensitized solar cell having the same configuration as that described in Example 1 was obtained except that 0.1 g of pyrazine and 0.01 g of acetic acid were added to 1 g of this electrolyte to obtain an electrolyte composition. Manufactured.
(Comparative Example 5)
A dye-sensitized solar cell having the same configuration as that described in Comparative Example 3 was manufactured except that lithium iodide was added.

About the solar cell of Examples 1-16 and Comparative Examples 1-5, the energy conversion efficiency at the time of irradiating pseudo sunlight with the intensity | strength of 100 mW / cm < ² > was calculated | required, and the result is shown in (Table 1). Next, after storing the solar cells of Examples 1 to 16 and Comparative Examples 1 to 5 at 100 ° C. for one month, the energy conversion efficiency when irradiating simulated sunlight with an intensity of 100 mW / cm ² was obtained. Compared with the energy conversion efficiency before storage, the reduction rate was obtained. Moreover, the case where it gelatinized is set as (circle), the case where it did not do is set as x, and these are also shown in (Table 1). Furthermore, the battery characteristic test was measured under the condition of AM1.5 (100 mW / cm ² ) using a solar simulator with a xenon lamp (WXS-R50S-1.5, manufactured by Maki Seisakusho). Then, the current-voltage characteristics were measured using an IV tester, and the open circuit voltage (Voc / V) and the short circuit current (Isc / mA · cm −2) were obtained. The results obtained for the open circuit voltage and short circuit current of No. 4 are shown in Table 2.

  As shown in (Table 1), the dye-sensitized solar cell of each example according to the embodiment of the present invention has long gel characteristics because it has higher gel characteristics than the dye-sensitized solar cell of each comparative example. Stability increases and photoelectric conversion efficiency is also high. For example, in Comparative Example 1, since t-butylpyridine is used, the pka value exceeds 4, so that it reacts with the cross-linking agent. The effect of increasing the photoelectric conversion efficiency of the compound is also reduced. Moreover, in Comparative Examples 2 and 3, since no carboxylic acid compound is used, the ionic component cannot be supplied, and the photoelectric conversion efficiency decreases. Furthermore, in Comparative Example 4, since a wet photosensitized solar cell using an organic solvent is used, although the initial photoelectric conversion efficiency is high, the reduction rate is very large and difficult to use. Moreover, in the comparative example 5, in order to supply an ionic component, since the conventional lithium iodide is used without using a carboxylic acid compound, gelation is inhibited and long-term stability falls.

  On the other hand, in each Example, since a gel characteristic is high, long-term stability increases and photoelectric conversion efficiency is also high. Among the examples, from Examples 1, 2, 3, 4, 5, 16, etc., it is more photoelectric conversion efficiency to use an amine compound having a pka value of 4 or less, and among them, pyrimidine is particularly photoelectric conversion efficiency. It can be seen that it is preferable to increase Further, Examples 1, 7, 9, 10, 11, 12, 13 and the like show that benzoic acid is most preferable among the carboxylic acid compounds in order to increase the photoelectric conversion efficiency. In addition, Examples 1, 6, 8 and the like show that among the gelling agents, 1,2,4,5-tetrakis (bromomethyl) has high gel characteristics and excellent long-term stability. Furthermore, it can be seen from Examples 1, 14, 15 and the like that the photoelectric conversion efficiency can be increased by adding water.

It is sectional drawing which shows an example of the manufacturing process of the dye-sensitized solar cell which concerns on embodiment of this invention. It is sectional drawing which shows an example of the dye-sensitized solar cell which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Glass substrate 2 ... Transparent electrically conductive film 3 ... Titanium oxide fine particle 4 ... Semiconductor electrode 5 ... Conductive film 6 ... Opposite substrate 7, 10 ... Epoxy resin 8 ... Injection nozzle 9 ... Electrolyte composition 11 ... Incident light

Claims (5)

A semiconductor electrode having a dye supported on the surface;
A counter substrate that is disposed to be opposed to the semiconductor electrode and has a conductive layer on the surface;
A photosensitized solar cell, comprising an electrolyte layer sandwiched between the semiconductor electrode and the conductive layer and comprising iodine molecules, a molten salt of iodide, a carboxylic acid compound, and a gelling agent. The photosensitized solar cell according to claim 1, wherein the carboxylic acid compound is at least one selected from acetic acid and benzoic acid. The photosensitized solar cell according to claim 1, further comprising an amine compound having a pka value of 4 or less in the electrolyte layer. The photosensitized solar cell according to claim 3, wherein the amine compound is a heteroaromatic compound. The photosensitized solar cell according to claim 1, further comprising water in the electrolyte layer.

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