JP4849844B2 - Dye-sensitized solar cell - Google Patents

Description

  The present invention relates to a dye-sensitized solar cell having a novel configuration.

Since the dye-sensitized solar cell has been proposed by Gretzel et al., It can be manufactured by an inexpensive material and a simple process. (Refer literature 1 and patent documents 1 and 2.).
In addition, in order to achieve high conversion efficiency of solar cells, optimization of structural members has been studied. In particular, in order to improve the utilization factor of sunlight, it has been proposed to dispose an antireflection film on the incident surface of the titania electrode substrate in order to reduce reflection loss on the substrate surface. Generally, in order to form a titania layer on a glass with a transparent conductive film, it is necessary to perform baking. However, when the antireflection film is heated near the titania baking temperature of 500 ° C., there is a problem that the antireflection performance is lowered. Therefore, it is necessary to form the antireflection film after the titania layer is formed and fired, and it is a problem to suppress performance degradation due to the contamination of the titania layer. Furthermore, even if the reflectance on the air side of the titania electrode is reduced, it is virtually impossible to suppress the reflection at the transparent conductive film / titania interface.
JP 2003-123859 A International Publication No. 01/48833 Pamphlet B. O'Regan, M. Gratzel, “Nature” (UK), 1991, 353, p. 737

  The present invention has been made in view of such a situation, and an object thereof is to provide a dye-sensitized solar cell capable of remarkably improving the utilization factor of sunlight.

As a result of intensive studies on the above problems, the present inventors have completed the present invention.
That is, the present invention provides an electrode having a semiconductor layer modified with a sensitizer on a conductive substrate, an electrolyte layer containing a substance exhibiting at least reversible electrochemical redox characteristics, and the reversible electrochemical oxidation. A substrate surface comprising at least a counter electrode in which a metal mesh coated with a substance having a catalytic action on a substance exhibiting a reduction property is in contact with a transparent substrate, and at least a side of the transparent substrate opposite to the electrolyte layer side The antireflective film composed of an alternating laminated film of a high refractive index film having a refractive index exceeding 1.55 and a low refractive index film having a refractive index of 1.55 or less is formed on the uppermost film as the film farthest from the transparent substrate is a low refractive index film. it is formed to be about a dye-sensitized solar cell according to claim.

The present invention also relates to the dye-sensitized solar cell as described above, wherein antireflection films are formed on the substrate surfaces on both sides of the transparent substrate.
The present invention also relates to the dye-sensitized solar cell described above, wherein a metal mesh is fixed to a transparent substrate.
The present invention also relates to the dye-sensitized solar cell as described above, wherein the metal mesh has a configuration in which a metal wire is woven.
The present invention also relates to the dye-sensitized solar cell as described above, wherein the semiconductor layer is titanium oxide produced by anodizing titanium.

Hereinafter, the present invention will be described in detail.
In the present invention, an electrode having a semiconductor layer modified with a sensitizer on a conductive substrate is used as the photoelectric conversion electrode.
The conductive substrate is not particularly limited as to whether it is flexible, and examples of the material include titanium, chromium, tungsten, molybdenum, platinum, tantalum, niobium, zirconium, zinc, various stainless steels, and alloys thereof. Preferably, titanium, chromium, tungsten, various stainless steels and alloys thereof are desirable.
The thickness of the conductive substrate varies depending on the presence or absence of flexibility and the material, but is, for example, in the range of 5 μm to 1 mm, preferably 10 μm to 0.5 mm, and more preferably 20 μm to 0.2 mm.

No particular limitation is imposed on the semiconductor layer used in the present invention, for _{example, Bi 2 S 3, CdS,} CdSe, CdTe, CuInS 2, CuInSe 2, Fe 2 O 3, GaP, GaAs, InP, Nb 2 O 5, PbS , Si, SnO ₂ , TiO ₂ , WO ₃ , ZnO, ZnS and the like, preferably CdS, CdSe, CuInS ₂ , CuInSe ₂ , Fe ₂ O ₃ , GaAs, InP, Nb ₂ O ₅ , PbS, SnO _2. , TiO ₂ , WO ₃ , ZnO, or a plurality of combinations. Particularly preferred are TiO ₂ , ZnO, SnO ₂ , Nb ₂ O ₅ and combinations thereof, and most preferred are TiO ₂ , ZnO, SnO ₂ and combinations thereof.
The semiconductor used in the present invention may be single crystal or polycrystalline. As the crystal system, for example, in the case of titanium oxide, anatase type, rutile type, brookite type and the like are mainly used, but anatase type is preferable.

  The thickness of the semiconductor layer is arbitrary, but is usually 0.05 μm or more and 100 μm or less, preferably 0.5 μm or more and 50 μm or less, and more preferably 1 μm or more and 30 μm or less.

  The semiconductor layer can be formed by applying the semiconductor nanoparticle dispersion, sol solution, or the like on the conductive substrate by a known method. The coating method in this case is not particularly limited, and examples include a method of obtaining a thin film by a casting method, a spin coating method, a dip coating method, a bar coating method, and various printing methods including a screen printing method. it can. Alternatively, the semiconductor material or a precursor material thereof can be used to form the conductive substrate on the conductive substrate by vacuum deposition, ion plating, CVD, sputtering, or the like. Further, it can be formed by anodic oxidation of a metal material used as a precursor of the semiconductor layer. Here, the anodic oxidation is a metal material that is a precursor of the semiconductor layer in the electrolyte, for example, a metal selected from titanium, niobium, tantalum, zirconium and alloys containing them as an anode, and an arbitrary metal as a cathode. This is a technique for forming an oxide on the surface of the metal on the anode side by applying an electric field, and it is sufficient that the state that these metals are anodes during the anodic oxidation treatment, and the anodes and cathodes are alternated. This includes the case where it is implemented.

  As the metal material used for anodization, titanium or an alloy containing titanium (hereinafter referred to as a titanium alloy) is most preferable. As titanium or titanium alloy used in the present invention, industrial pure titanium whose material is adjusted with oxygen, iron, nitrogen, hydrogen, or a low alloy titanium alloy having a certain degree of press formability can be used. 2 types, 3 types, 4 types of industrial pure titanium, alloys with improved corrosion resistance by adding nickel, ruthenium, tantalum, palladium, etc., aluminum, vanadium, molybdenum, tin, iron, chromium, niobium, etc. One example is an added alloy. In the present invention, the titanium alloy means an alloy containing 50% or more of titanium.

  Regarding the shape, in addition to various shapes such as titanium or titanium alloy plate, rod, mesh, etc., titanium or titanium alloy was grown as a film on the surface of different conductive materials such as plate, rod, mesh, etc. Examples thereof include, but are not limited to, semiconductors having a shape such as an object, a plate, a rod, and a mesh, or a material in which titanium or a titanium alloy is grown as a film on the surface of an insulating material. Regarding the surface smoothness, in the anodizing step, it is possible to grow titania even if the surface structure has a complicated shape, and the smoothness is not limited.

Examples of the electrolyte solution used for anodization include phosphoric acid, sulfuric acid or a mixed acid thereof, an aqueous solution in which glycerophosphate and metal acetate are dissolved, or an electrolyte solution containing ions containing halogen atoms.
In particular, in the present invention, it is preferable to use an electrolyte solution containing ions containing halogen atoms. By using such an electrolytic solution, a semiconductor layer made of titania having a tube shape with a high aspect ratio can be obtained. The ion containing a halogen atom here is an ion containing any one atom of fluorine, chlorine, bromine and iodine, specifically, fluoride ion, chloride ion, bromide ion, iodide ion. , Perchlorate ion, perbromate ion, periodate ion, chlorate ion, bromate ion, iodate ion, chlorite ion, bromite ion, hypochlorite ion, hypobromite ion, Examples include hypoiodite ions. These ions may be used alone or as a mixture of two or more.

Specifically, as the electrolyte solution containing these ions, an aqueous solution of an acid or salt that forms these ions is used. The concentration of the acid or salt is preferably 0.001 to 50% by volume, more preferably 0.005 to 10% by volume, and still more preferably 0.01 to 5% by volume.
As such an electrolyte solution containing a halogen atom, a perchloric acid aqueous solution is particularly suitable.

The electrolyte solution may contain a water-soluble titanium compound. Since a water-soluble titanium compound is generally hydrolyzed in an aqueous solution to produce titania, by including this, titania is further produced by hydrolysis on the surface of titania produced by anodization. It is possible to prevent the redissolution of titania in the electrolyte solution and increase the titania aspect ratio.
Examples of such water-soluble titanium compounds include titanium alkoxides such as titanium isopropoxide, titanium trichloride, titanium tetrachloride, titanium fluoride, ammonium tetrafluorotitanate, titanium sulfate, and titanyl sulfate. Is not to be done. The concentration is preferably 0.001 to 1000, more preferably 0.01 to 50, and still more preferably 0.04 to 5 in terms of molar ratio to the halogen atom-containing ions.

Further, the electrolyte solution may contain an acidic compound different from the acid or salt that forms ions containing halogen atoms. By containing an acidic compound, the reaction rate such as promoting or suppressing the anodic oxidation rate can be controlled.
Examples of such acidic compounds include sulfuric acid, nitric acid, acetic acid, hydrogen peroxide, oxalic acid, phosphoric acid, chromic acid, glycerophosphoric acid and the like in addition to the above-mentioned halide or acid of its oxidant ion. Is not to be done. The concentration is preferably 0.001 to 1000, more preferably 0.01 to 50, and still more preferably 0.04 to 5 in terms of molar ratio to the halogen atom-containing ions.

The electrolyte solution may contain titania fine particles. By containing titania fine particles, the produced titania can be prevented from redissolving in the electrolyte solution, and the titania aspect ratio can be increased.
Such titania fine particles preferably have a particle size of 0.5 to 100 nm, more preferably 2 to 30 nm. Specific examples include those prepared from titanium ore by a liquid phase method and those synthesized by a vapor phase method, a sol-gel method, and a liquid phase growth method. Here, the gas phase method is a method for producing titania by baking hydrous titanium oxide obtained by heating and hydrolyzing titanium ore with a strong acid such as sulfuric acid at 800 ° C. to 850 ° C. The liquid phase method is a method for producing titania by bringing oxygen and hydrogen into contact with titanium chloride. In the sol-gel method, titanium alkoxide is hydrolyzed in an alcohol aqueous solution to form a sol, and further, a hydrolysis catalyst is added to the sol, left to gel, and the gelled product is baked to titania. It is a method of manufacturing. The liquid phase growth method is a method for obtaining titania by hydrolysis of titanium fluoride, ammonium tetrafluorotitanate, titanyl sulfate or the like.

Anodization is usually performed at an applied voltage of 5 to 200 V, preferably 10 to 100 V, and a current density of 0.2 to 500 mA / cm ² , preferably 0.5 to 100 mA / cm ² for 1 minute to 24 hours. , Preferably 5 minutes to 10 hours. At this time, the applied voltage and current density can be changed in a pulse manner. Although it does not specifically limit as a period of the pulse in this case, 0.001 Hz-1 MHz, Preferably it is 0.01 Hz-10000 Hz, More preferably, 0.1 Hz-1000 Hz is mentioned. The amplitude of the pulse is not particularly limited as long as it is within the range of the applied voltage and current density described above, and examples thereof include ON-OFF type pulses and anode-cathode inverted type pulses.
Moreover, 0-50 degreeC is preferable and, as for the temperature of the electrolyte aqueous solution at the time of anodizing, More preferably, it is 0-40 degreeC.

By the above method, a titanium metal or a titanium alloy can be anodized to obtain a semiconductor layer composed of nanotube-shaped titania having a high aspect ratio. The aspect ratio is a ratio of length to diameter, and is composed of nanotube-shaped titania having an aspect ratio of 6 or more, preferably 10 or more, more preferably 20 or more, and even more preferably 30 or more by using the above method. A semiconductor layer can be obtained.
The diameter of the nanotube-shaped titania obtained by the above method is usually 5 nm to 500 nm, preferably 10 nm to 300 nm, although it varies depending on the production conditions. The length also varies depending on the production conditions and the like, but is usually 0.1 μm to 100 μm, preferably 1 μm to 50 μm.

  Further, the above-described semiconductor nanoparticle dispersion, sol solution, or the like may be further applied to the semiconductor layer produced by the above-described anodic oxidation method by a known method.

  If necessary, the semiconductor layer formed by the above method can be subjected to post-treatment such as heat treatment, water vapor treatment, ultraviolet irradiation, and microwave irradiation. Thereby, in the case of titania, for example, its crystal structure (anatase, rutile, brookite, and mixed crystals thereof) can be grown. For example, in the case of heat treatment, the crystallinity of titania is improved by performing the treatment at a temperature of 100 ° C. to 1200 ° C. for 10 minutes to 500 minutes, preferably at a temperature of 300 ° C. to 800 ° C. for 30 minutes to 160 minutes. I can expect that. With these treatments, the tube shape does not collapse.

Next, the sensitizer for modifying (adsorbing, adhering, etc.) the semiconductor layer in the present invention will be described.
Examples of the sensitizer include dyes such as metal complex dyes, organic dyes, and natural dyes. Those having a functional group such as carboxyl group, hydroxyl group, sulfonyl group, phosphonyl group, carboxylalkyl group, hydroxyalkyl group, sulfonylalkyl group, phosphonylalkyl group in the molecule of the dye are preferably used.

  As the metal complex dye, a complex of ruthenium, osmium, iron, cobalt, zinc, mercury (for example, mellicle chrome), metal phthalocyanine, chlorophyll, or the like can be used. Examples of the metal complex dye used in the present invention are as follows.

(Dye 1)

Here, X ₁ represents a monovalent anion, but each X ₁ may be independent or cross-linked. For example, the following is exemplified.

(Dye 2)

Here, X ₁ is the same as X ₁ described above. X ₂ represents a monovalent anion, and examples thereof include the following.

Y is a monovalent anion, which is a halogen ion, SCN ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) _{2 ^{N -, PF 6 -, AsF}} 6 -, CH 3 COO -, CH 3 (C 6 H 4) SO 3 -, and _{(C 2 F 5 SO 2)} 3 C - , and the like.

(Dye 3)

Here, Z is an atomic group having an unshared electron pair, and the two Zs may be independent or bridged. For example, the following is exemplified.

Y is a monovalent anion, which is a halogen ion, SCN ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) _{2 ^{N -, PF 6 -, AsF}} 6 -, CH 3 COO -, CH 3 (C 6 H 4) SO 3 -, and _{(C 2 F 5 SO 2)} 3 C - , and the like.

(Dye 4)

  Examples of organic dyes include, but are not limited to, cyanine dyes, hemicyanine dyes, merocyanine dyes, xanthene dyes, triphenylmethane dyes, metal-free phthalocyanine dyes, and the like. Examples of the organic dye used in the present invention are as follows.

（Ｘ_１は窒素または硫黄を表し、ｎは１０〜５，０００を表す。）

(X ₁ represents nitrogen or sulfur, and n represents 10 to 5,000.)

As a semiconductor that can be used as a dye, an amorphous semiconductor having a large i-type light absorption coefficient, a direct transition semiconductor, or a fine particle semiconductor that exhibits a quantum size effect and efficiently absorbs visible light is preferable.
Moreover, in order to make the wavelength range of photoelectric conversion as wide as possible and increase the conversion efficiency, it is possible to mix one or more of the various semiconductors, metal complex dyes and organic dyes described above. Moreover, the sensitizer to mix and its ratio can be selected so that it may match the wavelength range and intensity distribution of the target light source.

  As a method of attaching the sensitizer to the semiconductor layer, a solution in which the sensitizer is dissolved in a solvent is applied by spray coating or spin coating on the semiconductor layer and then dried. it can. In this case, the substrate may be heated to an appropriate temperature. Alternatively, a method in which a semiconductor layer is immersed in a solution and adsorbed can be used. The immersion time is not particularly limited as long as the dye is sufficiently adsorbed, but is preferably 10 minutes to 30 hours, particularly preferably 10 minutes to 20 hours. Moreover, you may heat a solvent and a board | substrate when immersing as needed. The concentration of the dye in the case of a solution is preferably about 1 to 1000 mmol / L, preferably about 10 to 500 mmol / L.

  The solvent to be used is not particularly limited, but water and an organic solvent are preferably used. Examples of the organic solvent include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and t-butanol, acetonitrile, propionitrile, methoxypropionitrile, and glutaronitrile. Nitrile solvents, benzene, toluene, o-xylene, m-xylene, p-xylene, pentane, heptane, hexane, cyclohexane, heptane, acetone, methyl ethyl ketone, diethyl ketone, 2-butanone and other ketones, diethyl ether, tetrahydrofuran, ethylene Carbonate, propylene carbonate, nitromethane, dimethylformamide, dimethyl sulfoxide, hexamethylphosphoamide, dimethoxyethane, γ-butyrolactone, γ-valerolactone, sulfo Holane, dimethoxyethane, adiponitrile, methoxyacetonitrile, dimethylacetamide, methylpyrrolidinone, dimethyl sulfoxide, dioxolane, sulfolane, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, ethyl dimethyl phosphate, tributyl phosphate, tripentyl phosphate, phosphorus Trihexyl acid, triheptyl phosphate, trioctyl phosphate, trinonyl phosphate, tridecyl phosphate, tris phosphate (trifluoromethyl), tris phosphate (pentafluoroethyl), triphenyl polyethylene glycol, polyethylene glycol, etc. It can be used.

Next, the electrolyte used in the present invention will be described.
The electrolyte is required to contain a substance exhibiting reversible electrochemical redox characteristics, and may be either a liquid system or a solid system.
Further, the ionic conductivity of the electrolyte is usually 1 × 10 ⁻⁷ S / cm or more at room temperature, preferably 1 × 10 ⁻⁶ S / cm or more, more preferably 1 × 10 ⁻⁵ S / cm or more. desirable. The ionic conductivity can be obtained by a general method such as a complex impedance method.
In the electrolyte of the present invention, the diffusion coefficient of an oxidant of a substance that exhibits reversible electrochemical redox characteristics is 1 × 10 ⁻⁹ cm ² / s or more, preferably 1 × 10 ⁻⁸ cm ² / s. As described above, more preferably 1 × 10 ⁻⁷ cm ² / s or more is desirable. The diffusion coefficient is an index indicating ion conductivity, and can be obtained by a general method such as constant potential current characteristic measurement or cyclic voltammogram measurement.
The thickness of the electrolyte layer is not particularly limited, but is preferably 1 μm or more, more preferably 10 μm or more, and preferably 3 mm or less, more preferably 1 mm or less.

  The liquid electrolyte is not particularly limited. Usually, a solvent, a substance exhibiting reversible electrochemical redox characteristics (soluble in a solvent), and, if necessary, a supporting electrolyte as a basic component Composed. In addition to these, other optional components such as an ultraviolet absorber and an amine compound may be further contained as desired.

  Any solvent can be used as long as it is generally used in electrochemical cells and batteries. Specifically, acetic anhydride, methanol, ethanol, tetrahydrofuran, propylene carbonate, nitromethane, acetonitrile, 3-methyl-2-oxazolidinone, dimethylformamide, dimethyl sulfoxide, hexamethylphosphoamide, ethylene carbonate, dimethoxyethane, γ-butyrolactone, γ-valerolactone, sulfolane, 3-methylsulfolane, dimethoxyethane, propiononitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, dimethylacetamide, methylpyrrolidinone, dioxolane, trimethyl phosphate, triethyl phosphate, Tripropyl phosphate, ethyl dimethyl phosphate, tributyl phosphate, tripentyl phosphate, trihexyl phosphate, trihexyl phosphate Ptyl, trioctyl phosphate, trinonyl phosphate, tridecyl phosphate, tris phosphate (trifluoromethyl), tris phosphate (pentafluoroethyl), triphenyl polyethylene glycol phosphate, polyethylene glycol, and the like can be used. In particular, propylene carbonate, ethylene carbonate, dimethyl sulfoxide, dimethoxyethane, acetonitrile, 3-methyl-2-oxazolidinone, γ-butyrolactone, sulfolane, 3-methylsulfolane, dioxolane, dimethylformamide, dimethoxyethane, tetrahydrofuran, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, dimethylacetamide, methylpyrrolidinone, trimethyl phosphate and triethyl phosphate are preferred. Also, room temperature molten salts can be used. Here, the room temperature molten salt is a salt composed of an ion pair that is melted at room temperature (that is, in a liquid state) and usually has a melting point of 20 ° C. or lower and is a liquid at a temperature exceeding 20 ° C. Is a salt.

Examples of the room temperature molten salt include the following.

(Here, R represents an alkyl group having 2 to 20 carbon atoms, preferably 2 to 10 carbon atoms, and X ⁻ represents a halogen ion, SCN ⁻ , SeCN ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , CF ₃ SO ₃ ⁻ , ( CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , CH ₃ COO ⁻ , CH ₃ (C ₆ H ₄ ) SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) ₃ C ⁻ , dicyandiamide ion, tricyanomethane ion or thiocyanate.)

(Wherein R ¹ and R ² are each an alkyl group having 1 to 10 carbon atoms (preferably a methyl group or an ethyl group), or an aralkyl group having 7 to 20 carbon atoms, preferably 7 to 13 carbon atoms (preferably a benzyl group). X ⁻ represents a halogen ion, SCN ⁻ , SeCN ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ^−. , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , CH ₃ COO ⁻ , CH ₃ (C ₆ H ₄ ) SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) ₃ C ⁻ , (Indicates dicyandiamide ion, tricyanomethane ion or thiocyanate.)

(Here, R ¹ , R ² , R ³ and R ⁴ are each an alkyl group having 1 or more carbon atoms, preferably an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms (such as a phenyl group), or methoxy. Represents a methyl group, and may be the same or different from each other, and X ⁻ represents a halogen ion, SCN ⁻ , SeCN ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , CH ₃ COO ⁻ , CH ₃ (C ₆ H ₄ ) SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) ₃ C ⁻ , Dicyandiamide ion, tricyanomethane ion or thiocyanate ion.)

  One of these solvents may be used alone, or two or more thereof may be mixed and used.

In addition, a substance exhibiting reversible electrochemical redox characteristics is usually referred to as a so-called redox material, but the type is not particularly limited. Examples of such substances include ferrocene, p-benzoquinone, 7,7,8,8-tetracyanoquinodimethane, N, N, N ′, N′-tetramethyl-p-phenylenediamine, tetrathiafulvalene, thi Examples include complex salts such as anthracene, p-toluylamine, ferrocyanic acid-ferricyanate, sodium polysulfide, alkylthiol-alkyldisulfide, hydroquinone-quinone, and viologen dye. Further, salts having a counter anion (X ⁻ ) selected from halogen ions, SCN ⁻ and SeCN ⁻ are also preferably used. Examples of salts having these anions include alkali metal salts, alkaline earth metal salts, quaternary ammonium salts, quaternary phosphonium salts, imidazolium salts, and guanidinium salts. Specific examples of the alkali metal salt and alkaline earth metal salt include LiX, NaX, KX, CeX, MgX ₂ , and CaX ₂ .

等が挙げられる。 Specific examples of the quaternary ammonium salt include (CH ₃ ) ₄ N ⁺ X ⁻ , (C ₂ H ₅ ) ₄ N ⁺ X ⁻ , (nC ₄ H ₉ ) ₄ N ⁺ X ⁻ , Moreover,

Etc.

等が挙げられる。 Specific examples of the quaternary phosphonium salt include (CH ₃ ) ₄ P ⁺ X ⁻ , (C ₂ H ₅ ) ₄ P ⁺ X ⁻ , (C ₃ H ₇ ) ₄ P ⁺ X ⁻ , (C ₄ H ₉ ) ₄ P ⁺ X ⁻ ,

Etc.

Examples of the imidazolium salt include those represented by the following general formula.

Here, R ¹ and R ² each represent an alkyl group having 1 to 10 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, preferably 7 to 13 carbon atoms, and may be the same or different. R ^{3 to} R ⁵ each represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms, preferably 7 to 13 carbon atoms, and may be the same or different. X ⁻ represents a halogen ion, SCN ⁻ or SeCN ⁻ .

  Specific examples of such imidazolium salts include 1-propyl-2,3-dimethyl-imidazolium salt, 1-propyl-3-methylimidazolium salt, 1-ethyl-3-methylimidazolium salt, Examples include hexyl-3-methylimidazolium salt.

  Specific examples of the guanidinium salt include guanidinium hydrochloride, guanidinium thiocyanate, and guanidinium nitrate.

  Of course, a mixture of these can also be used suitably.

In addition, redox room temperature molten salts can also be used as substances exhibiting reversible electrochemical redox properties. Here, the redox room temperature molten salt is a salt composed of an ion pair melted at room temperature (that is, in a liquid state), and usually has a melting point of 20 ° C. or lower and is a liquid at a temperature exceeding 20 ° C. A salt consisting of a pair is shown, and a reversible electrochemical redox reaction can be performed. When redox room temperature molten salts are used as the substance exhibiting reversible electrochemical redox properties, the solvent may be used or may not be used.
The redox room temperature molten salt can be used alone or in combination of two or more.
Examples of the redox ordinary-temperature molten salt, for example, of the room temperature molten salt as described above, X ^- halogen ions, SCN ^- or SeCN ^- include those of.

As the redox material, only one of an oxidant and a reductant may be used, or the oxidant and the reductant may be mixed and added at an appropriate molar ratio. Further, these redox pairs may be added so as to show electrochemical responsiveness. Materials exhibiting such properties include halogen ions, SCN ⁻ , SeCN ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , and (C ₂ F ₅ SO _2. ) Ferrocenium having a counter anion selected from ₂ N ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , CH ₃ COO ⁻ , CH ₃ (C ₆ H ₄ ) SO ₃ ⁻ , and (C ₂ F ₅ SO ₂ ) ₃ C ⁻ In addition to metallocenium salts such as, halogens such as iodine, bromine, and chlorine can also be used.

  The amount of the substance exhibiting reversible electrochemical oxidation-reduction characteristics is not particularly limited as long as it does not cause defects such as precipitation in the electrolyte. However, the concentration in the electrolyte is usually 0.001 to 10 mol / L, preferably 0.01 to 1 mol / L. However, this is not the case when redox room temperature molten salts are used alone.

  Further, as the supporting electrolyte added as necessary, salts, acids, alkalis, and room temperature molten salts that are usually used in the field of electrochemistry or the field of batteries can be used.

  The salt is not particularly limited, and examples thereof include inorganic ion salts such as alkali metal salts and alkaline earth metal salts, quaternary ammonium salts, cyclic quaternary ammonium salts, quaternary phosphonium salts, cyclic quaternary phosphonium salts, and imidazolium. Salts, guanidinium salts and the like can be used.

Specific examples of the salts include ClO ₄ ⁻ , BF ₄ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , PF ₆ ⁻ and AsF ₆ ^−. , CH ₃ COO ⁻ , CH ₃ (C ₆ H ₄ ) SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) ₃ C ⁻ , and an alkali metal salt having a counter anion selected from dicyandiamide ion (DCA ⁻ ), alkaline earth Examples thereof include metal salts, quaternary ammonium salts, cyclic quaternary ammonium salts, quaternary phosphonium salts, cyclic quaternary phosphonium salts, imidazolium salts, and guanidinium salts.

Specific examples of the alkali metal salt and alkaline earth metal salt include LiClO ₄ , LiBF ₄ , LiPF ₆ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N , CH ₃ COOLi, CH ₃ (C ₆ H ₄ ) SO ₃ Li, Li (C ₂ F ₅ SO ₂ ) ₃ C, LiDCA, Mg (ClO ₄ ) ₂ , Mg (BF ₄ ) ₂ , Mg (PF ₆ ) ₂ , Mg (CF ₃ SO ₃ ) ₂ , Mg [(CF ₃ SO ₂ ) ₂ N] ₂ , Mg [(C ₂ F ₅ SO ₂ ) ₂ N] ₂ , Mg (CH ₃ COO) ₂ , Mg [CH ₃ (C ₆ H ₄ ) SO ₃ ] ₂ , Mg [(C ₂ F ₅ SO ₂ ) ₃ C] ₂ , Mg (DCA) _{2 and the} like.

等が挙げられる。 Specific examples of the quaternary ammonium salt and the cyclic quaternary ammonium salt include (CH ₃ ) ₄ N ⁺ BF ₄ ⁻ , (C ₂ H ₅ ) ₄ N ⁺ BF ₄ ⁻ , and (n—C ₄ H ₉ ) ₄ N. ^{_{+ BF 4 -, (C 2}} H 5) 4 n + Br -, (C 2 H 5) 4 n + ClO 4 -, (n-C 4 H 9) 4 n + ClO 4 -, CH 3 (C 2 H ₅ ) ₃ N ⁺ BF ₄ ⁻ , (CH ₃ ) ₂ (C ₂ H ₅ ) ₂ N ⁺ BF ₄ ⁻ , (CH ₃ ) ₄ N ⁺ SO ₃ CF ₃ ⁻ , (C ₂ H ₅ ) ₄ N ⁺ SO ₃ CF ₃ ⁻ , (nC ₄ H ₉ ) ₄ NSO ₃ CF ₃ ⁻ ,

Etc.

等が挙げられる。 Specific examples of the quaternary phosphonium salt and the cyclic quaternary phosphonium salt include (CH ₃ ) ₄ P ⁺ BF ₄ ⁻ , (C ₂ H ₅ ) ₄ P ⁺ BF ₄ ⁻ , (C ₃ H ₇ ) ₄ P ^+. BF ₄ ⁻ , (C ₄ H ₉ ) ₄ P ⁺ BF ₄ ⁻ ,

Etc.

  Specific examples of imidazolium salts include 1-propyl-2,3-dimethyl-imidazolium tetrafluoroborate, 1-propyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetra Examples thereof include fluoroborate and 1-hexyl-3-methylimidazolium tetrafluoroborate.

  Specific examples of the guanidinium salt include guanidinium hydrochloride, guanidinium thiocyanate, and guanidinium nitrate.

  Moreover, these mixtures can also be used suitably.

The acids are not particularly limited, and inorganic acids and organic acids can be used. Specifically, sulfuric acid, hydrochloric acid, phosphoric acids, sulfonic acids, carboxylic acids and the like can be used.
The alkalis are not particularly limited, and any of sodium hydroxide, potassium hydroxide, lithium hydroxide and the like can be used.
As the room temperature molten salts, the aforementioned compounds are used.

  There is no restriction | limiting in particular about the usage-amount of the above supporting electrolyte, Usually, it is 0.01-10 mol / L as a density | concentration in electrolyte, Preferably it is made to contain about 0.05-1 mol / L. it can.

Next, optional components to be added as desired will be described.
Examples of optional components include ultraviolet absorbers and amine compounds. Although it does not specifically limit as a ultraviolet absorber which can be used, Organic UV absorbers, such as a compound which has a benzotriazole skeleton and a compound which has a benzophenone skeleton, are mentioned as a typical thing.

As the compound having a benzotriazole skeleton, for example, a compound represented by the following general formula (1) is preferably exemplified.

In the general formula (1), R ¹ represents a hydrogen atom, a halogen atom or an alkyl group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms. Examples of the halogen atom include fluorine, chlorine, bromine and iodine. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an i-propyl group, a butyl group, a t-butyl group, and a cyclohexyl group. The substitution position of R ¹ is the 4-position or 5-position of the benzotriazole skeleton, but the halogen atom and the alkyl group are usually located at the 4-position. R ² represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an i-propyl group, a butyl group, a t-butyl group, and a cyclohexyl group. R ³ represents an alkylene group or alkylidene group having 1 to 10 carbon atoms, preferably 1 to ³ carbon atoms. Examples of the alkylene group include a methylene group, an ethylene group, a trimethylene group, and a propylene group. Examples of the alkylidene group include an ethylidene group and a propylidene group.

  Specific examples of the compound represented by the general formula (1) include 3- (5-chloro-2H-benzotriazol-2-yl) -5- (1,1-dimethylethyl) -4-hydroxy-benzenepropanoic acid. 3- (2H-benzotriazol-2-yl) -5- (1,1-dimethylethyl) -4-hydroxy-benzeneethanoic acid, 3- (2H-benzotriazol-2-yl) -4-hydroxybenzene Ethanoic acid, 3- (5-methyl-2H-benzotriazol-2-yl) -5- (1-methylethyl) -4-hydroxybenzenepropanoic acid, 2- (2′-hydroxy-5′-methylphenyl) Benzotriazole, 2- (2′-hydroxy-3 ′, 5′-bis (α, α-dimethylbenzyl) phenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5 '-Di-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 3- (5-chloro-2H-benzo And triazol-2-yl) -5- (1,1-dimethylethyl) -4-hydroxy-benzenepropanoic acid octyl ester.

Suitable examples of the compound having a benzophenone skeleton include compounds represented by the following general formulas (2) to (4).

In the general formulas (2) to (4), R ⁵ , R ⁶ , R ⁸ , R ⁹ , R ¹¹ , and R ¹² are the same or different from each other, and are a hydroxyl group, 1 to 10 carbon atoms, Preferably 1-6 alkyl groups or alkoxy groups are shown. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an i-propyl group, a butyl group, a t-butyl group, and a cyclohexyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, an i-propoxy group, and a butoxy group.
R ⁴ , R ⁷ and R ¹⁰ represent an alkylene group or alkylidene group having 1 to 10 carbon atoms, preferably 1 to 3 carbon atoms. Examples of the alkylene group include a methylene group, an ethylene group, a trimethylene group, and a propylene group. Examples of the alkylidene group include an ethylidene group and a propylidene group.
p1, p2, p3, q1, q2, and q3 each independently represent an integer of 0 to 3.

Preferred examples of the compound having a benzophenone skeleton represented by the general formulas (2) to (4) include 2-hydroxy-4-methoxybenzophenone-5-carboxylic acid and 2,2′-dihydroxy-4-methoxybenzophenone. -5-carboxylic acid, 4- (2-hydroxybenzoyl) -3-hydroxybenzenepropanoic acid, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfone Acid, 2-hydroxy-4-n-octoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, 2-hydroxy-4-methoxy -2'-carboxybenzophenone and the like.
Of course, two or more of these can be used in combination.

  The use of the UV absorber is optional, and the amount used is not particularly limited. However, when used, the concentration in the electrolyte is 0.001 to 10 mol / L, preferably 0. It is desirable that it is 01-1 mol / L.

  Moreover, it does not specifically limit as an amine compound which can be contained in the electrolyte of this invention, Various aliphatic amines, aromatic amines, etc. can be used. For example, pyridine derivatives, aniline derivatives, quinoline derivatives, imidazole derivatives, and the like are typical examples. By adding these amine compounds, an improvement in open circuit voltage is expected. Specific examples of these compounds include pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 4-ethylpyridine, 4-propylpyridine, 4-t-butyl-pyridine, 4-dimethylaminopyridine, 2-dimethylaminopyridine, 2,6-dimethylpyridine, 2,4,6-trimethylpyridine, 4-pyridinopyridine, 4-pyrrolidinopyridine, 4- (2-aminoethyl) pyridine, 2- (2-amino Ethyl) pyridine, 2-methoxymethylpyridine, picolinic acid, 2-pyridinemethanol, 2-pyridineethanol, 3-pyridinemethanol, 2,3-cyclopentenopyridine, nicotinamide, nicotinic acid, 4,4′-bipyridine, Pyridine derivatives such as 2,2'-bipyridine, and anilines such as aniline and dimethylaniline Phosphorus derivatives, quinoline, quinoline derivatives such as isoquinoline, benzimidazole, imidazole derivatives such as N- methyl benzimidazole.

  The use of the amine compound is optional, and the amount used is not particularly limited, but when used, the concentration in the electrolyte is 0.001 to 10 mol / L, preferably 0.01. It is desirable that it is ˜1 mol / L.

  The electrolyte used in the present invention may be a liquid as described above, but a polymer solid electrolyte is particularly preferable from the viewpoint that solidification is possible. As the polymer solid electrolyte, it is particularly preferable that (a) the polymer matrix (component (a)) contains at least (b) a substance (component (b)) exhibiting reversible electrochemical redox characteristics. If desired, those further containing (c) a plasticizer (component (c)) may be mentioned. In addition to these, other optional components such as the above-described supporting electrolyte, ultraviolet absorber, and amine compound may be further contained as desired. As the polymer solid electrolyte, the component (b), the component (b) and the component (c), or a further optional component is held in a polymer matrix to form a solid state or a gel state.

  In the present invention, the material that can be used as the polymer matrix (component (a)) is a polymer matrix alone, solid state or gel by adding a plasticizer, adding a supporting electrolyte, or adding a plasticizer and a supporting electrolyte. There is no particular limitation as long as the state is formed, and generally used so-called polymer compounds can be used.

  Examples of the polymer compound exhibiting characteristics as the polymer matrix include hexafluoropropylene, tetrafluoroethylene, trifluoroethylene, ethylene, propylene, acrylonitrile, vinylidene chloride, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, methyl Examples thereof include polymer compounds obtained by polymerizing or copolymerizing monomers such as acrylate, ethyl acrylate, methyl methacrylate, styrene, and vinylidene fluoride. These polymer compounds may be used alone or in combination. Among these, a polyvinylidene fluoride polymer compound is particularly preferable.

  Examples of the polyvinylidene fluoride polymer compound include a homopolymer of vinylidene fluoride, or a copolymer of vinylidene fluoride and another polymerizable monomer, preferably a radical polymerizable monomer. Specific examples of other polymerizable monomers copolymerized with vinylidene fluoride (hereinafter referred to as copolymerizable monomers) include hexafluoropropylene, tetrafluoroethylene, trifluoroethylene, ethylene, propylene, acrylonitrile, vinylidene chloride. Acrylic acid, methacrylic acid, maleic acid, maleic anhydride, methyl acrylate, ethyl acrylate, methyl methacrylate, styrene and the like can be exemplified. Among these, a copolymer with a monomer having a carboxyl group is particularly preferable. That is, as the polyvinylidene fluoride polymer compound, those containing a carboxyl group are preferable.

  These copolymerizable monomers can be used in the range of 0.1 to 50 mol%, preferably 1 to 25 mol%, based on the total amount of monomers.

  As the copolymerizable monomer, hexafluoropropylene is preferably used. In the present invention, in particular, it can be preferably used as an ion conductive film using a vinylidene fluoride-hexafluoropropylene copolymer obtained by copolymerizing 1 to 25 mol% of hexafluoropropylene with vinylidene fluoride as a polymer matrix. Two or more kinds of vinylidene fluoride-hexafluoropropylene copolymers having different copolymerization ratios may be mixed and used.

  Further, two or more of these copolymerizable monomers can be used for copolymerization with vinylidene fluoride. For example, vinylidene fluoride + hexafluoropropylene + tetrafluoroethylene, vinylidene fluoride + hexafluoropropylene + acrylic acid, vinylidene fluoride + hexafluoropropylene + maleic anhydride, vinylidene fluoride + tetrafluoroethylene + ethylene, vinylidene fluoride A copolymer obtained by copolymerization with a combination of + tetrafluoroethylene + propylene can also be used.

  Furthermore, in the present invention, a polyacrylic acid-based polymer compound, a polyacrylate-based polymer compound, a polymethacrylic acid-based polymer compound, a polymethacrylate-based polymer compound, One or more polymer compounds selected from acrylonitrile polymer compounds and polyether polymer compounds may be used in combination. Alternatively, one or more kinds of copolymers obtained by copolymerizing two or more kinds of monomers of the above-described polymer compound with a polyvinylidene fluoride polymer compound may be used. In this case, the blending ratio of the homopolymer or copolymer is usually preferably 200 parts by mass or less with respect to 100 parts by mass of the polyvinylidene fluoride polymer compound.

  The weight-average molecular weight of the polyvinylidene fluoride polymer compound used in the present invention is usually 10,000 to 2,000,000, preferably 100,000 to 1,000,000. can do.

As the substance (component (b)) exhibiting reversible electrochemical oxidation-reduction characteristics, specifically, various redox materials and redox room temperature molten salts exemplified in the above-described liquid electrolyte are used.
When components other than redox room temperature molten salts are used as component (b), it is usually preferred to use in combination with component (c). When redox room temperature molten salts are used as the component (b), the component (c) may or may not be used in combination.

The amount of the substance exhibiting reversible electrochemical oxidation-reduction characteristics (component (b)) is not particularly limited, but is usually 0.1% by mass or more, preferably 1% by mass or more in the polymer solid electrolyte. More preferably, it is 10% by mass or more and 70% by mass or less, preferably 60% by mass or less, and more preferably 50% by mass or less.
In addition, it is preferable to use a component (b) together with a plasticizer (component (c)).

The plasticizer (component (c)) acts as a solvent for substances exhibiting reversible electrochemical redox properties. Any plasticizer can be used as long as it can be generally used as an electrolyte solvent in an electrochemical cell or battery, and specific examples thereof include various solvents exemplified in liquid electrolytes. In particular, propylene carbonate, ethylene carbonate, dimethyl sulfoxide, dimethoxyethane, acetonitrile, 3-methyl-2-oxazolidinone, γ-butyrolactone, sulfolane, 3-methylsulfolane, dioxolane, dimethylformamide, dimethoxyethane, tetrahydrofuran, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, dimethylacetamide, methylpyrrolidinone, trimethyl phosphate and triethyl phosphate are preferred. Moreover, the above-mentioned room temperature molten salts can also be used.
One plasticizer may be used alone, or two or more plasticizers may be mixed and used.

  The amount of the plasticizer (component (c)) used is not particularly limited, but is usually 20% by mass or more, preferably 50% by mass or more, more preferably 70% by mass or more, and 98% by mass in the polymer solid electrolyte. It can be contained in an amount of not more than mass%, preferably not more than 95 mass%, more preferably not more than 90 mass%.

When the component (b) and the component (c) are used in combination, it is desirable that the component (b) has a mixing ratio that dissolves in the component (c) and does not cause precipitation even when the polymer solid electrolyte is formed. Preferably component (b) / component (c) is 0.01-0.5 by mass ratio, More preferably, it is the range of 0.03-0.3.
For component (a), the mass ratio of component (a) / (component (b) + component (c)) is preferably 1/20 to 1/1, more preferably 1/10 to 1/2. It is desirable to be in the range.

In addition to these, the solid electrolyte may further contain other optional components such as a supporting electrolyte, an ultraviolet absorber, and an amine compound as desired.
The amount of the supporting electrolyte used in the polymer solid electrolyte is not particularly limited and is arbitrary, but is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 10% by mass or more in the polymer solid electrolyte. And 70% by mass or less, preferably 60% by mass or less, and more preferably 50% by mass or less. In addition, the types and contents of ultraviolet absorbers, amine compounds and the like are as exemplified in the liquid electrolyte.

  Next, in the present invention, the polymer solid electrolyte can be used as an ion conductive film. For example, an ion conductive film can be obtained by forming a polymer solid electrolyte comprising the components (a) and (b) or an optional component further blended as desired into a film by a known method. The molding method in this case is not particularly limited, and examples thereof include extrusion molding, a method obtained in a film state by a casting method, a spin coating method, a dip coating method, an injection method, and an impregnation method.

Extrusion molding can be performed by a conventional method, and after the mixture is melted by heating, film molding is performed.
Regarding the casting method, the mixture can be formed into a film by further adjusting the viscosity with an appropriate diluent, applying the mixture with a normal coater used in the casting method, and drying. As the coater, a doctor coater, a blade coater, a rod coater, a knife coater, a reverse roll coater, a gravure coater, a spray coater, and a curtain coater can be used, and they can be selectively used depending on the viscosity and the film thickness.
As for the spin coating method, the mixture can be formed into a film by further adjusting the viscosity with an appropriate diluent, applying the mixture with a commercially available spin coater, and drying.
As for the dip coating method, a film can be formed by adjusting the viscosity of the mixture with an appropriate diluent to prepare a mixture solution, pulling up an appropriate base from the mixture solution, and drying.

Next, the counter electrode used in the present invention will be described.
The counter electrode in the present invention has a configuration in which a metal mesh coated with a substance having a catalytic action on the substance exhibiting the above-described reversible electrochemical redox characteristics is contacted (preferably fixed) with a transparent substrate. .
The transparent substrate is provided with an antireflection film on the substrate surface opposite to the electrolyte layer side or on both substrate surfaces.

  The metal mesh used in the present invention is not particularly limited as long as it has a high transmittance, but preferably has a configuration in which a metal wire is woven. Examples of the material of the metal wire constituting the metal mesh include nickel, titanium, chromium, tungsten, molybdenum, platinum, tantalum, niobium, zirconium, zinc, various stainless steels, and alloys thereof, preferably titanium, chromium. , Tungsten, various stainless steels and their alloys are desirable.

In addition, the wire diameter of the metal wire and the mesh opening of the metal mesh greatly affect the diffusion distance of the substance exhibiting reversible electrochemical oxidation-reduction characteristics contained in the electrolyte layer. This greatly affects the transmittance. As long as the space ratio of the metal mesh can function as an electrode, it is preferably as high as possible. For example, 60% or more, more preferably 70% or more, and further preferably 80% or more is desirable.
In addition, the wire diameter of the metal wire and the mesh opening of the metal mesh are preferable as the wire diameter is thinner and the mesh opening is narrower as long as the function as an electrode can be achieved.

The metal mesh is coated with a material that has a catalytic action on the material exhibiting the above-described reversible electrochemical redox characteristics.
Examples of the substance having a catalytic action include noble metals such as platinum, conductive organic compounds such as polydioxythiophene and polypyrrole, and carbon substances. The carbon material is not particularly limited. For example, a diamond thin film doped with boron, graphite, graphite, glassy carbon, acetylene black, ketjen black, activated carbon, petroleum coke, C60, C70, and other fullerenes. And single-walled or multi-walled carbon nanotubes. The shape of the carbon material is not particularly limited as long as it finally forms a carbon layer, and the raw material shape is liquid, gaseous, solid (powder, short fiber, long fiber, woven) Any form of a cloth, a nonwoven fabric, etc. may be sufficient.

  The method for coating the metal mesh with the catalyst material is not particularly limited, and a known method can be employed. For example, a catalyst material and a binder are mixed to form a paste, which can be produced by a screen printing, flat printing, gravure printing, intaglio printing, flexographic printing, letterpress printing, special printing method, doctor blade method or the like on the surface of a metal mesh. . Moreover, after arrange | positioning a paste on the metal mesh surface, you may improve electroconductivity and adhesiveness by heating etc. In addition to an oven, a muffle furnace, an electric furnace, infrared heating or the like may be used for heating. The firing temperature varies depending on the paste used and the metal mesh material, but is preferably 50 ° C to 700 ° C, more preferably 100 ° C to 600 ° C, and still more preferably 200 ° C to 500 ° C. Moreover, you may bake in nitrogen atmosphere as needed. Alternatively, CVD such as thermal CVD and plasma CVD, sputtering such as ion beam sputtering, PLD, arc method and the like, and electrodeposition, electrophoresis, electroplating, electroless plating, electroless plating, and other wet film forming methods can be used. In the case of film formation by CVD, the film formation temperature is preferably 300 ° C. or higher, more preferably 500 ° C. or higher. Moreover, you may irradiate electromagnetic waves in the case of CVD. Further, in the wet film forming method, it is preferably formed within the range of (metal mesh temperature) − (20 ° C. to 300 ° C.).

The metal mesh coated with the catalyst substance is preferably attached to a transparent substrate and fixed.
The method of attaching to the transparent substrate is not particularly limited as long as the transparency is not impaired, and it can be attached by a usual method using various adhesives, pressure-sensitive adhesives, adhesive films and the like.

The transparent substrate to be used is not particularly limited as long as it is transparent. For example, colorless or colored soda lime glass, Pyrex (registered trademark) glass, water glass, high transmittance glass called white plate, synthetic quartz, fused quartz, alumina In addition to inorganic materials such as zirconia, colorless or colored resins may be used. Specific examples of the resin include polyesters such as polyethylene terephthalate, polyamide, polysulfone, polyether sulfone, polyether ether ketone, polyphenylene sulfide, polycarbonate, polyimide, polymethyl methacrylate, polystyrene, cellulose triacetate, and polymethylpentene. Is mentioned. In addition, the transparency in this invention is 10-100% of transmittance | permeability, Preferably it has the transmittance | permeability of 50% or more.
The thickness of the transparent substrate is not particularly limited, and usually 5 μm to 2 mm can be used, but preferably 5 μm to 0. A 5 mm flexible transparent substrate can be suitably used.

The antireflection film used in the present invention is not particularly limited as long as it is a thin film having an antireflection effect, and a general antireflection film can be used. As one of the preferable antireflection films, an alternating laminated film of a high refractive index film and a low refractive index film can be mentioned. Here, in the high refractive index film and the low refractive index film, the higher refractive index film is called a high refractive index film, and the lower refractive index film is called a low refractive index film. As the low refractive index film, those having a refractive index of 1.55 or less are preferable. Examples of these films are silicon oxide, fluorine compound or aluminum compound (for example, SiO ₂ , MgF ₂ or Al ₂ O ₃ ). The film | membrane which becomes is mentioned. A low refractive index film made of such a material can be formed by a vapor deposition method such as vacuum evaporation, sputtering, or ion plating. Alternatively, a low refractive index film can be obtained by preparing a coating liquid containing the powder of the above material and an organic polymer binder or an inorganic polymer binder, coating the substrate on the substrate, drying, and curing as necessary. In the case of using an ultraviolet curable or thermosetting resin as the binder, it is particularly preferable because the formation becomes easy. For example, when a SiO ₂ film is formed by coating, the SiO ₂ content of the film is suitably 30 to 50% by mass. A low refractive index film made of these materials can be formed by a casting method, a dip coating method, a screen printing method, a roll coater method, a spin coating method, a spray method, or the like.

The high refractive index film preferably has a refractive index exceeding 1.55. Examples of these films include tin-doped indium oxide (ITO), ZnO, aluminum-doped zinc oxide (ZAO), TiO ₂ , SnO _{2, and} ZrO. These metal oxide films can be mentioned. A high refractive index film made of such a material can be formed by a vapor deposition method or the like. Alternatively, a high-refractive-index film can be obtained by preparing a coating liquid containing the above-mentioned powder and an organic polymer binder or an inorganic polymer binder, applying the coating liquid to a substrate, drying, and curing as necessary. When an ultraviolet curable resin or a thermosetting resin is used as the binder, it is particularly preferable because the formation becomes easy. For example, when an ITO film is formed by coating, an ITO content of the film is suitably 80 to 89% by mass. A high refractive index film made of these materials can be formed by a casting method, a dip coating method, a screen printing method, or the like.

  As such a laminated structure of alternating laminated films, the film farthest from the transparent substrate is preferably a low refractive index film. Furthermore, it is preferable that one high refractive index film and one low refractive index film are formed on the transparent substrate in this order, and the total number of layers of the alternately laminated film is 3 to 6 layers.

Specific examples of the antireflection film include the following configuration examples.
(1) Consisting of a single transparent film having a lower refractive index than the transparent substrate.
(2) A high-refractive-index film and a low-refractive-index film are laminated on a transparent substrate in this order, a total of two layers.
(3) A film in which a high refractive index film, a low refractive index film, a high refractive index film, and a low refractive index film are laminated in this order, for a total of four layers on a transparent substrate.
(4) A low-refractive index film, a high-refractive index film, and a low-refractive index film are laminated in this order on a transparent substrate in a total of three layers. In this case, the first low refractive index film on the transparent substrate side preferably has an intermediate refractive index between the second high refractive index film and the third low refractive index film.
(5) On a transparent substrate, a high refractive index film, a low refractive index film, a high refractive index film, a low refractive index film, a high refractive index film, and a low refractive index film are laminated in this order, for a total of 6 layers. .

1 and 2 are sectional views of typical examples of the structure of the antireflection film. This corresponds to cases (2) and (4) of the above configuration.
In FIG. 1, on the surface of the transparent substrate 1, a high refractive index film H1 and a low refractive index film L1 are laminated in this order. These two layers constitute the antireflection film 2. For example, TiO 2 as a high refractive index _film, SiO ₂ is generally used because of easy availability as a low refractive index film.
In FIG. 2, a low refractive index film L2, a high refractive index film H2, and a low refractive index film L3 are laminated on the transparent substrate 1 in this order. These three layers constitute the antireflection film 3. For example, TiO ₂ as a high refractive index film or SiO ₂ as an ITO low refractive index film is generally used because it is easily available.

  The film thicknesses of these high and low refractive index films are appropriately determined in order to lower the reflectance in the visible light region due to light interference, but this depends on the number of layers in the laminated film, the material used, and the center wavelength. . For example, in the case of a four-layer structure, the high refractive index film of the first layer on the transparent substrate side is 5 to 50 nm, the low refractive index film of the second layer is 5 to 50 nm, and the high refractive index film of the third layer is 50 to 100 nm. The low refractive index film of the fourth layer is preferably in the range of 50 to 150 nm. For example, in the case of a two-layer structure, the high refractive index film of the first layer on the transparent substrate side is preferably 50 to 150 nm, and the low refractive index film of the second layer is preferably 50 to 150 nm.

  Further, a contamination prevention film may be further formed on such an antireflection film to improve the surface contamination resistance. As this contamination-preventing film, a fluorine resin thin film or a silicone resin thin film is preferable. The film thickness is usually 1-1000 nm

  In the present invention, the measurement of the optical density of the photoelectric conversion electrode is not particularly limited. For example, a method of measuring the optical density of the produced photoelectric conversion electrode using an ultraviolet / visible spectrophotometer (manufactured by Hitachi, Ltd., U4000). Is mentioned. Also, the measurement of the reflectance is not particularly limited. For example, the reflectance can be measured by attaching a specular reflection measurement unit to the spectrophotometer.

  In the present invention, by adopting the above-described configuration, it is possible to reduce the reflection loss of incident light on the substrate surface of the transparent substrate, improve the transmittance, and produce a counter electrode excellent in transparency. A high dye-sensitized solar cell can be produced.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
(1) Production of dye-adsorbing titania electrode A titanium foil (purity: 99.7% by weight) having a size of 6 cm × 1.5 cm and a thickness of 0.05 mm was prepared and subjected to ultrasonic cleaning in ethanol for 5 minutes. A titania electrode was prepared by anodizing the titanium foil at 30 V for 1 hour in a 0.002 mol / L perchloric acid aqueous solution kept at 16 ° C. This was baked at 450 ° C. for 1 hour.
The titania electrode obtained above was immersed in a ruthenium dye (Rutenium 535-bisTBA: Solaronics) / ethanol solution (4.0 × 10 ⁻⁴ mol / L) for 15 hours, washed with ethanol, and dye-adsorbed titania. An electrode was produced.

(2) Preparation of counter electrode substrate with single-sided antireflection film After placing float glass in a magnetron sputtering apparatus, a titanium oxide target is used to oxidize a first layer of a titanium oxide thin film (15 nm) using a silicon oxide target. Forming a second layer of silicon thin film (30 nm), a third layer of titanium oxide thin film (100 nm) using a titanium oxide target, and a fourth layer of silicon oxide thin film (100 nm) using a silicon oxide target; A counter electrode substrate in which an antireflection film (a) was formed on one surface (for the air side surface) of the transparent substrate was produced (glass with antireflection film (A)). The reflection spectrum of the glass with antireflection film (A) is shown in FIG. The measurement of the reflection spectrum was performed using an ultraviolet-visible spectrum measuring apparatus (U-4000, manufactured by Hitachi, Ltd.) and a specular reflection unit mounted at 5 degrees.

(3) Production of counter electrode substrate with antireflection film on both sides ITO fine powder having a refractive index of 1.7 is dispersed on the substrate surface on which antireflection film (a) of glass with antireflection film (A) is not formed. The applied ultraviolet curable acrylic resin coating solution is applied to form a coating film having a dry film thickness of 100 nm (ITO content: 84% by mass), and irradiated with ultraviolet rays under a condition of 300 mJ / cm ² in a nitrogen atmosphere. Cured. Next, a coating solution of an ultraviolet curable acrylic resin in which silicon oxide fine powder having a refractive index of 1.5 is dispersed is applied to form a coating film having a dry film thickness of 100 nm (silicon oxide content: 40% by mass), It was cured by irradiating ultraviolet rays under a condition of 300 mJ / cm ^{2 in} a nitrogen atmosphere. Thus, a two-layered antireflection film (b) was formed (glass with antireflection film (B)). The reflection spectrum of this glass (B) with an antireflection film is shown in FIG.
Moreover, the reflection spectrum of the float glass without an antireflection film is shown in FIG.

(4) Production of counter electrode A tungsten mesh having a wire diameter of 15 μm and a mesh number of 105 was cut into 11 cm square, and a Pt thin film of 30 nm was formed on both surfaces thereof by DC magnetron sputtering.
Four sides of the tungsten thin film with platinum thin film were fixed to the surface side on which the antireflection film (b) of the glass with antireflection film (B) was formed with an imide tape, and used as a counter electrode (metal mesh counter electrode).

(5) Production of Dye-Sensitized Solar Cell After partially removing the titania around the titania electrode, a 1.5 mmφ injection hole for injecting an electrolyte was formed in one corner. A butyl rubber seal was placed around the substrate, and glass beads having a diameter of 53 to 63 μm were dispersed on the side of the butyl rubber. On top of this, the metal mesh surface of the metal mesh counter electrode produced above was put together and adhered by applying a pressure of 2 MPa. Using the injection hole of the obtained cell, 0.1 mol / L lithium iodide, 0.5 mol / L 1-propyl-2,3-dimethyl-imidazolium iodide, 0.05 mol / L iodine, A 3-methoxypropionitrile solution containing 0.5 mol / L of 4-t-butylpyridine is vacuum-injected, the injection hole is sealed with butyl rubber, and then a small piece of a titanium metal plate is used for the injection hole using an epoxy resin. Was pasted. Moreover, the secondary seal | sticker was performed to the peripheral part with the same epoxy resin. A cross-sectional view of the cell thus fabricated is shown in FIG. When the produced cell was irradiated with pseudo-sunlight (1 kW / m ² ) and the current-voltage characteristics were measured, good photoelectric conversion characteristics (conversion efficiency 5.7%) were obtained.

(Example 2)
As the counter electrode, instead of the glass with antireflection film (B), the glass with antireflection film (A) produced in Example 1 was used, and the tungsten with platinum thin film was formed on the side where the antireflection film (a) was not formed. A dye-sensitized solar cell was produced in the same manner as in Example 1 except that the mesh was fixed and the metal mesh counter electrode was used. A cross-sectional view of the fabricated cell is shown in FIG. When the produced cell was irradiated with pseudo sunlight (1 kW / m ² ) and the current-voltage characteristics were measured, the photoelectric conversion efficiency was 5.5%.

(Comparative Example 1)
A photoelectric conversion element was prepared in the same manner as in Example 1 except that a float glass substrate in which an antireflection film was not disposed on the counter electrode substrate was used, and pseudo-sunlight (1 kW / m ² ) was irradiated, and current-voltage characteristics. Was measured, and the photoelectric conversion efficiency was 4.5%.

It is an example of a structure of an antireflection film. It is an example of a structure of an antireflection film. It is an example of the reflection spectrum of glass (A) with an antireflection film. It is an example of the reflection spectrum of glass (B) with an antireflection film. It is an example of the reflection spectrum of transparent glass without an antireflection film. 2 is a cross-sectional view of a cell manufactured in Example 1. FIG. 6 is a cross-sectional view of a cell manufactured in Example 2. FIG.

Explanation of symbols

H1 High refractive index film H2 High refractive index film L1 Low refractive index film
L2 Low refractive index film L3 Low refractive index film
DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Antireflection film 3 Antireflection film 4 Transparent substrate 5 Antireflection film (a)
6 Antireflection film (b)
7 Metal Mesh Covered with Catalyst 8 Conductive Substrate 9 Semiconductor Layer 10 Sensitized with Dye 10 Electrolyte Layer 11 Seal

Claims (6)

An electrode having a semiconductor layer modified with a sensitizer on a conductive substrate, an electrolyte layer containing a substance showing at least reversible electrochemical redox characteristics, and a substance showing the reversible electrochemical redox characteristics On the other hand, a metal mesh coated with a substance having a catalytic action is at least composed of a counter electrode in contact with a transparent substrate, and has a refractive index of 1 on at least the substrate surface opposite to the electrolyte layer side of the transparent substrate. An antireflection film composed of an alternating laminated film of a high refractive index film exceeding .55 and a low refractive index film having a refractive index of 1.55 or less is formed so that the film farthest from the transparent substrate is a low refractive index film. And a dye-sensitized solar cell. 2. The dye-sensitized solar cell according to claim 1, wherein the antireflection film has any one of the following constitutions (a) to (d):
(A) A high-refractive index film and a low-refractive index film laminated on a transparent substrate, one layer each in this order.
(B) A high-refractive index film, a low-refractive index film, a high-refractive index film, and a low-refractive index film are laminated in this order on a transparent substrate in a total of four layers.
(C) A low-refractive-index film, a high-refractive-index film, and a low-refractive-index film are laminated in this order on a transparent substrate in a total of three layers. In this case, the first low refractive index film on the transparent substrate side has an intermediate refractive index between the second high refractive index film and the third low refractive index film.
(D) A high-refractive-index film, a low-refractive-index film, a high-refractive-index film, a low-refractive-index film, a high-refractive-index film, and a low-refractive-index film laminated in this order, six in total, on a transparent substrate. . The dye-sensitized solar cell according to claim 1 or 2 , wherein an antireflection film is formed on the substrate surface on both sides of the transparent substrate. The dye-sensitized solar cell according to any one of claims 1 to 3, wherein a metal mesh is fixed to a transparent substrate. The dye-sensitized solar cell according to any one of claims 1 to 4 , wherein the metal mesh has a configuration in which a metal wire is woven. The dye-sensitized solar cell according to any one of claims 1 to 5, characterized in that the semiconductor layer is titanium oxide produced titanium is anodized.

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