JP2007149652A - Photoelectrochemical battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectrochemical battery, in which the charge transport layer such as an electrolyte and a solvent or the like contained in the charge transport layer will not be lost, and which has superior durability, even if it is stored at a high temperature. <P>SOLUTION: A conductive substrate, semiconductor particulates with photosensitive coloring elements absorbed, and a laminate containing a charge transport layer and a counter electrode, are sealed by a sealing compound, to make the photoelectrochemical battery. The sealing compound contains resin, containing a hydroxyl group, such as ethylene-vinyl alcohol copolymer, partially saponified polyvinyl alcohol, or fully saponified polyvinyl alcohol. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photoelectrochemical cell such as a solar cell.

In recent years, in order to prevent global warming, reduction of CO ₂ released into the atmosphere has been demanded. As an effective means for reducing CO ₂ , for example, promotion of utilization of a solar system using a photoelectrochemical cell such as a pn junction type silicon solar cell that can be installed on a roof of a house has been proposed. However, the single crystal, polycrystal and amorphous silicon used in the silicon photoelectrochemical cell have a problem of high cost because high temperature and high vacuum conditions are required in the production process.
On the other hand, Non-Patent Document 1 proposes a photoelectrochemical cell including a photoelectric conversion element in which a thin film of titanium oxide having a photosensitizing dye adsorbed on its surface is laminated on a conductive substrate, a charge transfer layer, and a counter electrode. Yes. Compared to conventional silicon-based solar cells, the photoelectrochemical cell is expected to be cheaper because many of the materials used are inexpensive and high-temperature high-vacuum conditions are not required in the manufacturing process. .
By the way, the charge transfer layer proposed in Non-Patent Document 1 uses iodine / iodide as an electrolyte and a volatile solvent such as acetonitrile as a solvent. A sealant is used so that the layer does not volatilize.
For example, Non-Patent Document 2 proposes a photoelectrochemical cell using BYNEL (registered trademark, DuPont), which is an adhesive of polyethylene resin, as a sealant.

Nature (pages 737-740, 353, 1991) Nature materials (Page 406, lower left column, 2nd line, 2nd volume, 2003)

When the present inventors stored a photoelectrochemical cell using iodine / iodide as an electrolyte contained in the charge transfer layer, acetonitrile as a solvent, and the adhesive as a sealant at 85 ° C., iodine was used. Disappeared and it became clear that the durability was not sufficient.
An object of the present invention is to provide a photoelectrochemical cell excellent in durability without losing a charge transfer layer such as an electrolyte or a solvent contained in the charge transfer layer even when stored at a high temperature.

When the present inventors examined the sealing agent of a photoelectrochemical cell, it discovered that the photoelectrochemical cell obtained using the sealing agent containing a certain kind of resin was excellent in durability, and this book Completed the invention.
That is, the present invention provides a sealing agent in a photoelectrochemical cell comprising a laminate including a conductive substrate, semiconductor fine particles adsorbed with a photosensitizing dye, a charge transfer layer and a counter electrode, sealed with the sealing agent. Contains a resin containing a hydroxyl group.

  The photoelectrochemical cell of the present invention is excellent in durability because it is sealed with a sealant capable of preventing volatilization of an electrolyte such as iodine and a volatile solvent such as acetonitrile.

Hereinafter, the present invention will be described in detail.
The photoelectrochemical cell of the present invention is a photoelectrochemical cell formed by sealing a laminate including a conductive substrate, semiconductor fine particles adsorbing a photosensitizing dye, a charge transfer layer, and a counter electrode with a sealant. .
In a wet photoelectrochemical cell, an electrolytic solution is filled between a conductive substrate in contact with a layer of semiconductor fine particles adsorbed with a photosensitizing dye (hereinafter sometimes referred to as a dye-adsorbing semiconductor particle layer) and a counter electrode. .
In the dry photoelectrochemical cell, the conductive substrate and the counter electrode are stacked via a solid hole transport material, and the semiconductor fine particles adsorbing the photosensitizing dye are contained in the solid hole transport material. Contained.

The wet photoelectrochemical cell of the present invention will be described below as an example. A specific example is shown in FIG. A conductive substrate (8), a counter electrode (9) facing the conductive substrate (8), and a semiconductor fine particle layer (3) on which the photosensitizing dye (4) is adsorbed exist between these. In the case of a wet photoelectrochemical cell, the semiconductor particle layer (3) (with the dye adsorbed) is sealed with a sealing material (10) in a state filled with the electrolytic solution (5).
The conductive substrate (8) is composed of a substrate (1) and a conductive layer (2) in order from the top. The counter electrode (9) is composed of a substrate (7) and a conductive layer (6) in order from the bottom.

The lower the electrical resistance of the conductive layer (the conductive substrate (2) and the counter electrode (6)) in the conductive substrate (8) and the counter electrode (9) used in the photoelectrochemical cell of the present invention is preferred. In addition, the conductive layer (2) of the conductive substrate preferably has a high transmittance in a high wavelength region, specifically a region longer than 350 nm, specifically a transmittance of 80% or more. .
Examples of the conductive substance used for the conductive layer include metals such as iron, nickel, chromium, titanium, aluminum, platinum, gold, silver, cobalt, palladium, copper, tantalum, ruthenium, tungsten, zinc, and tin; Alloys; conductive metal oxides such as indium-tin composite oxide (ITO), tin oxide doped with fluorine; conductive polymers such as carbon, polyethylenedioxythiophene (PEDOT), polyaniline, etc. . The conductive polymer is usually doped with paratoluenesulfonic acid or the like.
Specific examples of the conductive layer include a conductive substance itself or a nonconductive substrate surface formed by vapor deposition, sputtering, adhesion, or the like on a nonconductive substrate surface.
The conductive substrate (8) preferably has a texture structure on the surface of the conductive material in order to confine incident light and effectively use it.

Examples of the non-conductive substrate ((1) as the conductive substrate and (7) as the counter electrode) in the conductive substrate (8) and the counter electrode (9) include glass or plastic.
Examples of the plastic include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polycarbonate (PC), polypropylene (PP), polyimide (PI), triacetyl cellulose (TAC), syndiotactic polystyrene ( SPS), polyarylate (PAR); Arton (registered trademark of JSR), ZEONEX (registered trademark of ZEON), ZEONOR (registered trademark of ZEON), Apel (registered trademark of Mitsui Chemicals) and Topas (registered by Ticona) Examples thereof include cyclic polyolefin (COP) such as trademark); polyethersulfone (PES), polyetherimide (PEI), polysulfone (PSF), polyamide (PA), and the like.

  As the conductive substrate (8) and the counter electrode (9), a glass or plastic coated with a conductive metal oxide is preferable. Among these, conductive glass with a conductive layer made of tin dioxide doped with fluorine and conductive PET with a conductive layer made of indium-tin composite oxide (ITO) have low electrical resistance and light transmittance. It is particularly preferable because it is excellent and easily available.

  The semiconductor fine particles used in the present invention are fine particles having a semiconductor characteristic with a primary particle size of about 1 to 5000 nm, preferably about 5 to 500 nm. For the purpose of improving photoelectric conversion efficiency by reflection, semiconductor fine particles having different primary particle diameters may be mixed. Tubes and hollow fine particles may be used.

Examples of the material of the semiconductor fine particles (2) include titanium oxide, tin oxide, zinc oxide, iron oxide, tungsten oxide, zirconium oxide, hafnium oxide, strontium oxide, indium oxide, cerium oxide, yttrium oxide, lanthanum oxide, and vanadium oxide. , Niobium oxide, tantalum oxide, gallium oxide, nickel oxide, strontium titanate, barium titanate, potassium niobate, sodium tantalate, etc .; silver iodide, silver bromide, copper iodide, copper bromide, etc. Metal halides of: metal sulfides such as zinc sulfide, titanium sulfide, indium sulfide, bismuth sulfide, cadmium sulfide, zirconium sulfide, tantalum sulfide, molybdenum sulfide, silver sulfide, copper sulfide, tin sulfide, tungsten sulfide, and antimony sulfide; selenium Cadmium iodide, zirconium selenide Metal selenides such as zinc selenide, titanium selenide, indium selenide, tungsten selenide, molybdenum selenide, bismuth selenide, lead selenide; cadmium telluride, tungsten telluride, molybdenum telluride, zinc telluride, Metal tellurides such as bismuth telluride; metal phosphides such as zinc phosphide, gallium phosphide, indium phosphide, cadmium phosphide; gallium arsenide, copper-indium-selenide, copper-indium-sulfide, silicon, germanium Etc. Further, it may be a mixture of two or more of zinc oxide / tin oxide and tin oxide / titanium oxide.
Among them, titanium oxide, tin oxide, zinc oxide, iron oxide, tungsten oxide, zirconium oxide, hafnium oxide, strontium oxide, indium oxide, cerium oxide, yttrium oxide, lanthanum oxide, vanadium oxide, niobium oxide, tantalum oxide, gallium oxide, Metal oxides such as nickel oxide, strontium titanate, barium titanate, potassium niobate, sodium tantalate, zinc oxide / tin oxide, tin oxide / titanium oxide are relatively inexpensive and readily available, and photosensitizing dyes Titanium oxide is particularly preferable because it is easily adsorbed.

The surface of the semiconductor fine particles may be subjected to chemical plating using a titanium tetrachloride aqueous solution or electrochemical plating using a titanium trichloride aqueous solution. This increases the surface area of the semiconductor fine particles, increases the purity in the vicinity of the semiconductor fine particles, masks impurities such as iron existing on the surface of the semiconductor fine particles, or increases the connectivity and bonding properties of the semiconductor fine particles. can do.
The semiconductor fine particles preferably have a large surface area so that many photosensitizing dyes can be adsorbed. For this reason, the surface area of the semiconductor fine particle (2) applied on the substrate is preferably 10 times or more, more preferably 100 times or more the projected area. This upper limit is usually about 1000 times.
The layer of semiconductor fine particles (2) may be a single layer of semiconductor fine particles, but is usually a layer composed of a plurality of semiconductor fine particles and a plurality of semiconductor fine particles having different particle diameters.

In the case of a wet photoelectrochemical cell, a semiconductor fine particle layer is usually formed on a conductive substrate, and then a photosensitizing dye is adsorbed on the fine particles of the layer.
As a method for forming a semiconductor fine particle layer on a conductive substrate, a method in which semiconductor fine particles are directly formed as a thin film on a conductive substrate by spraying or the like; a semiconductor fine particle thin film is electrically deposited using a conductive substrate as an electrode Method: A method in which a slurry of semiconductor fine particles is applied on a conductive substrate and then dried, cured, or baked is exemplified.

The method for applying the semiconductor fine particle slurry onto the conductive substrate will be described in more detail. Examples thereof include a doctor blade, squeegee, spin coating, dip coating, and screen printing. In these methods, the average particle size in the dispersed state of the semiconductor fine particles in the slurry is preferably 0.01 nm to 100 μm.
The dispersion medium for dispersing the slurry is not particularly limited as long as it can disperse the semiconductor fine particles. Water or an alcohol solvent such as ethanol, isopropanol, t-butanol or terpineol; an organic solvent such as a ketone solvent such as acetone. Is used. These water and organic solvent may be a mixture. The dispersion may contain a polymer such as polyethylene glycol; a surfactant such as Triton-X; an organic acid or inorganic acid such as acetic acid, formic acid, nitric acid or hydrochloric acid; and a chelating agent such as acetylacetone.
It is preferable to form the semiconductor fine particle layer by firing the conductive substrate coated with the semiconductor fine particle slurry. The firing temperature is usually lower than the melting point of the conductive layer or substrate, and the upper limit of the firing temperature is 1200 ° C., preferably 600 ° C. or less. The firing time is usually within 10 hours. The thickness of the semiconductor fine particle layer on the conductive substrate is usually from 0.1 to 200 μm, preferably from 1 to 50 μm.

  As another method for forming a semiconductor fine particle layer on a conductive substrate at a relatively low temperature, a hydrothermal method in which a porous semiconductor fine particle layer is formed by hydrothermal treatment (a dye-sensitized photoelectrochemical cell for practical use). 2nd lecture (Hideki Kajiura) pp. 63-65, published by NTS (2003)), electrophoretic electrodeposition method (T. Miyasaka et al., Chem.) Of electrodepositing a dispersion of dispersed semiconductor particles on a substrate. Lett., 1250 (2002)), a method of applying a semiconductor paste to a substrate, pressing after drying (a dye-sensitized photoelectrochemical cell for practical use, 12th lecture (Takehiko Tsuji), pages 312 to 313, NTS Issue (2003)).

  The photosensitizing dye used in the present invention has absorption in the visible light region and / or the infrared light region, and one or more of various metal complexes and organic dyes can be used. A photosensitizing dye having a functional group such as a carboxyl group, a hydroxyalkyl group, a hydroxyl group, a sulfone group, or a carboxyalkyl group in the molecule of the photosensitizing dye is preferred because it tends to be adsorbed to a semiconductor quickly. Moreover, since it is excellent in photoelectric conversion efficiency and durability, a metal complex is preferable. As the metal complex, metal phthalocyanines such as copper phthalocyanine and titanyl phthalocyanine, chlorophyll, hemin, and ruthenium, osmium, iron, and zinc complexes described in JP-A-1-220380 and JP-A-5-504023 are used. Can do.

  More detailed examples of ruthenium complexes include cis-bis (isothiocyanate) bis (2,2'-bipyridyl-4,4'-dicarboxylate) -ruthenium (II) bis-tetrabutylammonium, cis-bis (iso Thiocyanate) bis (2,2'-bipyridyl-4,4'-dicarboxylate) -ruthenium (II), tris (isothiocyanate) -ruthenium (II) -2,2 ': 6', 2 "-thepyridine- Tris-tetrabutylammonium 4,4 ', 4 "-tricarboxylate, cis-bis (isothiocyanate) (2,2'-bipyridyl-4,4'-dicarboxylate) (2,2'-bipyridyl-4, 4'-dinonyl) ruthenium (II) and the like.

Examples of the organic dye include metal-free phthalocyanine, cyanine dye, merocyanine dye, xanthene dye, triphenylmethane dye, squarylium dye, and the like. Specific examples of cyanine dyes include NK1194 and NK3422 (both manufactured by Nippon Photosensitive Dye Research Laboratories). Specific examples of merocyanine dyes include NK2426 and NK2501 (both manufactured by Nippon Photosensitivity Laboratories). Examples of xanthene dyes include uranin, eosin, rose bengal, rhodamine B, dibromofluorescein and the like. Examples of the triphenylmethane dye include malachite green and crystal violet.
Examples of the coumarin dye include NKX-2777 (manufactured by Hayashibara Biochemical Laboratories) (see the following structural formula).
Examples of organic dyes such as indoline include D149 (manufactured by Mitsubishi Paper Industries) (see the following structural formula).

As a method for adsorbing a photosensitizing dye to semiconductor fine particles laminated on a conductive substrate, for example, a laminate comprising a well-dried semiconductor fine particle layer and a conductive substrate in a solution containing the photosensitizing dye of the present invention For several hours. Adsorption of the photosensitizing dye may be performed at room temperature (25 ° C.), may be performed under heating, or may be performed while refluxing a solution containing the photosensitizing dye.
The photosensitizing dye can be adsorbed before the semiconductor fine particle layer is formed on the conductive substrate, or the semiconductor fine particles and the photosensitizing dye may be applied to the conductive substrate at the same time. A method of adsorbing the photosensitizing dye to the formed semiconductor fine particle layer is more preferable. When the semiconductor fine particle layer is heat-treated, the photosensitizing dye adsorption is preferably performed after the heat treatment, and a method of adsorbing the photosensitizing dye after the heat treatment and before water is adsorbed on the surface of the semiconductor fine particle layer is particularly preferable. preferable.

In order to suppress the reduction of the sensitizing effect due to floating of the photosensitizing dye not attached to the semiconductor fine particles, it is desirable to remove the unadsorbed photosensitizing dye by washing.
The photosensitizing dye to be adsorbed may be one kind or a mixture of several kinds. When the application is a photoelectrochemical cell, it is preferable to select a photosensitizing dye to be mixed so that the wavelength range of photoelectric conversion of irradiation light such as sunlight is as wide as possible. Further, the adsorption amount of the photosensitizing dye to the semiconductor fine particles is preferably 0.01 to 1 mmol per 1 g of the semiconductor fine particles. Such a dye amount is preferable because the sensitizing effect in the semiconductor fine particles can be sufficiently obtained and the reduction of the sensitizing effect due to floating of the dye not attached to the semiconductor fine particles tends to be suppressed.
Further, the photosensitizing dyes adsorbed on the semiconductor fine particles (2) may be the same or different. For example, a 300-500 nm photosensitizing dye is adsorbed on the first layer, a 500-700 nm photosensitizing dye is adsorbed on the second layer, and a 700-900 nm photosensitizing dye is adsorbed on the third layer. Photosensitizing dyes having different absorption wavelengths may be adsorbed on each layer, such as adsorbing.

  A colorless compound may be co-adsorbed for the purpose of suppressing interaction such as association and aggregation between photosensitizing dyes. Examples of the hydrophobic compound to be co-adsorbed include a steroid compound having a carboxyl group (for example, chenodeoxycholic acid). Further, for the purpose of accelerating the removal of excess dye, the surface of the semiconductor fine particles may be treated with amines after adsorbing the dye. Examples of preferable amines include pyridine, 4-tert-butylpyridine, and polyvinylpyridine. When these are liquids, they may be used as they are, or when they are solids, they may be dissolved in an organic solvent.

Examples of the electrolyte contained in the charge transfer layer of the present invention include a combination of I ₂ and various iodides, a combination of Br ₂ and various bromides, a combination of ferrocyanate-ferricyanate metal complexes, Examples include combinations of metal complexes of ferrocene-ferricinium ions, combinations of sulfur compounds of alkyl thiol-alkyl disulfides, combinations of alkyl viologens and reduced forms thereof, combinations of polyhydroxybenzenes and oxidized forms thereof.
Here, examples of the iodide that can be combined with I ₂ include metal iodides such as LiI, NaI, KI, CsI, and CaI ₂ ; 1-propyl-3-methylimidazolium iodide, 1-propyl-2,3 -Iodine salts of quaternary imidazolium compounds such as dimethyl imidazolium idide; iodine salts of quaternary pyridinium compounds; iodine salts of tetraalkylammonium compounds.
Examples of iodides that can be combined with Br ₂ include metal bromides such as LiBr, NaBr, KBr, CsBr, and CaBr ₂ ; bromine salts of quaternary ammonium compounds such as tetraalkylammonium bromide and pyridinium bromide, and the like.
Examples of alkyl viologen include methyl viologen chloride, hexyl viologen bromide, and benzyl viologen tetrafluoroborate. Examples of polyhydroxybenzenes include hydroquinone and naphthohydroquinone.
Among them, the electrolyte is preferably a combination of I ₂ and iodide, and in particular, from metal iodide, iodine salt of quaternary imidazolium compound, iodine salt of quaternary pyridinium compound, and iodine salt of tetraalkylammonium compound. A combination of at least one iodide selected from the group and I ₂ is preferred.

When the photoelectrochemical cell of the present invention is wet, the charge transfer layer contains an electrolyte. Examples of the electrolytic solution include water and an organic solvent that dissolves the electrolyte.
Examples of the organic solvent include nitrile solvents such as acetonitrile, methoxyacetonitrile, and propionitrile; carbonate solvents such as ethylene carbonate and propylene carbonate; lactone solvents such as γ-butyrolactone; amides such as N, N-dimethylformamide Ionic liquids such as 1-methyl-3-propylimidazolium iodide and 1-methyl-3-hexylimidazolium iodide; 1-ethyl-3-methylimidazolium-bis (trifluoromethanesulfonic acid) imide Is mentioned.
The electrolytic solution may be gelled with a polyacrylonitrile, polyvinylidene fluoride, poly-4-vinylpyridine, or a low-molecular gelling agent shown in Chemistry Letters, 1241 (1998).

When the photoelectrochemical cell of the present invention is dry, a solid electrolytic layer such as a solid hole transport material is used for the charge transfer layer.
Examples of solid hole transport materials include those made of p-type inorganic semiconductors containing monovalent copper such as CuI and CuSCN, and those shown in Synthetic Metal, 89 , 215 (1997) and Nature, 395 , 583 (1998). Aromatic amines; Polythiophene and its derivatives; Polypyrrole and its derivatives; Polyaniline and its derivatives; Poly (p-phenylene) and its derivatives; Conductive polymers such as poly (p-phenylene vinylene) and its derivatives Etc.

The sealant used in the present invention contains a resin containing a hydroxyl group, and when the resin is used as a sealant, when a volatile solvent such as acetonitrile or iodine is used as an electrolyte, they are In particular, since it is difficult to volatilize at high temperatures, the durability is remarkably improved.
As the resin containing a hydroxyl group, a thermoplastic resin is preferable because of easy handling.
Specific examples of the resin containing a hydroxyl group include an ethylene-vinyl alcohol copolymer obtained by hydrolyzing an acetate ester of an ethylene-vinyl acetate copolymer, and a partially saponified polyvinyl alcohol obtained by partially hydrolyzing an acetate ester of polyvinyl acetate. Examples thereof include those containing a structural unit obtained by hydrolyzing a vinyl ester which is a structural unit of a resin, such as alcohol and a fully saponified polyvinyl alcohol obtained by hydrolyzing about 98 mol% or more of polyvinyl acetate.
The resin containing a hydroxyl group can be used as a film, and when used as a film, the film may be used after being stretched.

Among the resins containing a hydroxyl group, an ethylene-vinyl alcohol copolymer is preferably used from the viewpoint of easy sealing by thermocompression bonding using an electrothermal press or the like.
Examples of the ethylene-vinyl alcohol copolymer include Eval (registered trademark) manufactured by Kuraray Co., Ltd., Soarnol (registered trademark) manufactured by Nippon Gosei Kagaku Co., Ltd., and Soarite (registered trademark). As EVAL, any grade in the EVAL RESIN & FILM catalog (issued in May 2006) can be used. For example, all grades of L, F, T, J, H, E, E, and G with different ethylene polymerization ratios can be used. Can be used. Further, these films may contain a lubricant.
In addition, ethylene-vinyl alcohol copolymer, partially saponified polyvinyl alcohol, and fully saponified polyvinyl alcohol are polyethylene terephthalate (PET), polyamide (PA), polyethylene (PE), polypropylene (PP), aluminum, SiO ₂ film, etc. A multilayer structure may be formed.
Examples of the polyvinyl alcohol include Kuraray Co., Ltd., Kuraray Poval, Nippon Synthetic Chemical Co., Ltd. Gohsenol, Nippon Vinegar Bipoval Co., Ltd., J-Poval, Denki Poval Co., Ltd., Unitika Co., Ltd., etc. The poval may contain a plasticizer.
These resins include spacers for keeping the distance between the conductive substrate (8) and the counter electrode (9) constant, and volatile solvents such as acetonitrile and SiO ₂ , TiO ₂ , Al to further suppress evaporation of iodine. A filler such as ₂ O ₃ may be mixed.
The sealing agent of the present invention includes ionomer resins such as Himiran (registered trademark, manufactured by Mitsui DuPont Polychemical); glass frit; hot melt adhesives such as SX1170 (manufactured by Solaronix); and Amosil 4 (manufactured by Solaronix). Adhesive: Anhydrous-modified LLDPE (linear low density polyethylene modified with acid anhydride such as maleic anhydride) such as BYNEL (manufactured by DuPont) or an epoxy adhesive may be used in combination.

Examples of the shape of the sealant include those formed in advance into a shape to be sealed, such as a film and a sheet, and those that are in a liquid state containing water before sealing and are dried at the time of sealing. From the viewpoint of ease of handling, it is preferable to pre-form the film, sheet, or the like into a sealed shape.
The thickness of the film is usually about 1 μm to 1 mm.
As a method of sealing using the molded sealing agent, there is a method in which the sealing agent is sandwiched between the working electrode and the counter electrode and bonded together by an electric heating press. The bonding temperature may be set at a temperature higher than the temperature at which the resin melts, but is usually performed at 50 to 300 ° C.
The sealing material portion can be locally heated and melted and bonded using laser light or the like. When sealing a cell in which a pigment has already been installed, it is preferable to adjust the heating time within a range where the pigment does not deteriorate with heat.

  EXAMPLES Next, although an Example etc. are given and this invention is demonstrated further in detail, this invention is not limited by these examples.

Example 1
Ti-Nanoxide T (trade name, manufactured by Solaronix), a titanium oxide dispersion, on the conductive surface of a conductive glass with a tin oxide film doped with fluorine (manufactured by Nippon Sheet Glass, 10Ω / □), which is a conductive substrate. After applying using a doctor blade, it was baked at 500 ° C., the glass was cooled, and a semiconductor fine particle layer was formed on the conductive substrate. Subsequently, a solution of cis-bis (isothiocyanate) bis (2,2′-bipyridyl-4,4′-dicarboxylate) -ruthenium (II) bis-tetrabutylammonium (concentration is 0.0003 mol / liter, The solvent was immersed in a mixed solvent of t-butyl alcohol / acetonitrile = 1/1) for 16 hours, taken out from the solution, washed with acetonitrile, and then naturally dried to adsorb the conductive substrate and the photosensitizing dye. A laminate of fine particle layers (the area of the titanium oxide electrode was 7 cm ² ) was obtained. Next, a 50 μm-thick ethylene-vinyl alcohol copolymer resin (EVAL (registered trademark of Kuraray Co., Ltd.) F101) film as a sealant is placed around the layer, followed by fluorine-doped tin oxide film, platinum A pre-drilled conductive glass was superposed on the vapor-deposited conductive glass. After thermocompression bonding with an electrothermal press machine, the electrolyte solution (solvent is acetonitrile; iodine concentration in the solvent is 0.05 mol / liter, and lithium iodide concentration is 0.1 mol / liter). The 4-t-butylpyridine concentration was 0.5 mol / liter, and the 1-propyl-2,3-dimethylimidazolium iodide concentration was 0.6 mol / liter). Then, an ethylene-vinyl alcohol copolymer resin (EVAL (registered trademark of Kuraray Co., Ltd.) F101) film and a glass plate were placed on the hole to seal the hole, and then sealed by thermocompression bonding with an electric heating press. An electrochemical cell was obtained.
The photoelectrochemical cell produced in this way is placed in a xenon weathering tester and irradiated with light (light intensity: 0.48W / m2 (340nm), black panel temperature: 83 ° C, humidity: 50% RH, no rain) The change in conversion efficiency over time was observed. The conversion efficiency was measured using a solar simulator manufactured by Yamashita Denso.
Table 1 shows the conversion efficiency retention after 350 hours when the initial efficiency is 1.

(Comparative Example 1)
A photoelectrochemical cell was obtained in the same manner as in Example 1 except that BYNEL (registered trademark, manufactured by DuPont), which is an anhydride-modified LLDPE, was used as the sealant. Next, the change with time in photoelectric conversion efficiency was measured in the same manner as in Example 1. The results are shown in Table 1.

(Example 2)
A 50 μm thick ethylene-vinyl alcohol copolymer resin (EVAL (registered trademark of Kuraray Co., Ltd.) F101) film is placed around the glass plate as a sealant, and a glass plate with holes drilled in advance is placed on top of it. It was. After thermocompression bonding with an electric heat press, the electrolyte solution (solvent is acetonitrile; iodine concentration in the solvent is 0.05 mol / liter, lithium iodide concentration is 0.1 mol / liter, The 4-t-butylpyridine concentration was 0.5 mol / liter, and the 1-propyl-2,3-dimethylimidazolium iodide concentration was 0.6 mol / liter). Thereafter, an ethylene-vinyl alcohol copolymer resin (EVAL (registered trademark of Kuraray Co., Ltd.) F101) film and a glass plate were placed on the hole to seal the hole, and then sealed by thermocompression using an electric heating press.
The glass plate in which the electrolytic solution was sealed was aged in an oven at 85 ° C., and the change over time in the amount of iodine was measured at an absorbance of 362 nm. Table 2 shows the absorbance retention when the initial absorbance is 1. It means that the higher the absorbance, the higher the retention rate of iodine encapsulated in the photoelectrochemical cell.
(Example 3)
The same procedure as in Example 2 was performed except that a polyvinyl alcohol resin (Poval (registered trademark of Kuraray Co., Ltd.) VL-F) having a thickness of 40 μm was used as the sealant.

(Comparative Example 2)
A glass plate enclosing an electrolyte solution was obtained in the same manner as in Example 2 except that BYNEL (registered trademark, manufactured by DuPont), which is an anhydride-modified LLDPE, was used as the sealant. Next, the change in absorbance with time was measured in the same manner as in Example 2. The results are shown in Table 2.

  In the photoelectrochemical cell of the present invention, the disappearance of electrolytes such as iodine and volatile solvents is remarkably reduced even when used at a high temperature or for a long period of time compared to the case where a conventional sealant is used. Therefore, it has excellent durability. Because of such excellent characteristics, it can be used in solar cells using sunlight, photoelectrochemical cells using artificial light in tunnels and indoors. In addition, the photoelectrochemical cell of the present invention can be used as an optical sensor because a current flows when irradiated with light.

It is a cross-sectional schematic diagram of the wet photoelectrochemistry of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Conductive layer 3 Semiconductor particle layer 4 Photosensitizing dye 5 Electrolyte 6 Conductive layer 7 Substrate 8 Conductive substrate 9 Counter electrode 10 Sealant

Claims (5)

  In a photoelectrochemical cell in which a laminate including a conductive substrate, semiconductor fine particles adsorbed with a photosensitizing dye, a charge transfer layer, and a counter electrode is sealed with a sealant, the sealant includes a resin containing a hydroxyl group. A photoelectrochemical cell comprising:   The light according to claim 1, wherein the resin containing a hydroxyl group is at least one resin selected from the group consisting of an ethylene-vinyl alcohol copolymer, a partially saponified polyvinyl alcohol, and a fully saponified polyvinyl alcohol. Electrochemical battery.   3. The photoelectrochemical cell according to claim 1, wherein the semiconductor fine particles are titanium oxide. The photoelectrochemical cell according to claim 1, wherein the charge transfer layer is a combination of I ₂ and iodide.   An encapsulant for a photoelectrochemical cell comprising a resin containing at least one hydroxyl group selected from the group consisting of an ethylene-vinyl alcohol copolymer, a partially saponified polyvinyl alcohol, and a fully saponified polyvinyl alcohol.

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