JP2010073495A - Dye-sensitized solar battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dye-sensitized solar battery excellent in conversion efficiency and capable of being used for a long period as well. <P>SOLUTION: The dye-sensitized solar battery is provided with a hard transparent substrate composed of and hardened from silicone resin having a main component of poly-organo silsesquioxane as expressed in a formula (1) (RSiO<SB>1.5</SB>)m(RSiO<SB>0.5</SB>)n and having a basket type structure in a structure unit, wherein R is an unsaturated group as shown (a) -R<SP>1</SP>-OCO-CR<SP>2</SP>=CH<SB>2</SB>, (b) -R<SP>1</SP>-CR<SP>2</SP>=CH<SB>2</SB>, or (c) -CH=CH<SB>2</SB>, an alkyl group, a cyclo alkyl group, a cyclo alkenyl group, a phenyl group, a hydrogen atom, an alkoxyl group, or alkylsiloxy group, and a plurality of R's in the formula (1) can be different from each other, but at least one shall contain either (a), (b) or (c), and R<SP>1</SP>is an alkylene group, an alkylene group, or a phenylene group, R<SP>2</SP>is hydrogen or an alkyl group, and m=8 to 16 and n=0 to 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a dye-sensitized solar cell obtained using a novel hard transparent substrate.

  Dye-sensitized solar cells are attracting attention as clean energy, and there are remarkable advances in technology. In particular, there are great expectations for practical use due to the features of low cost and high conversion efficiency.

  In general, a dye-sensitized solar cell has a structure in which a transparent conductive layer, a porous metal oxide semiconductor layer, an electrolyte layer, and a conductive layer are laminated on a substrate. A substrate is used. However, the glass substrate is thick and heavy, and has a drawback of being easily broken, and there may be a problem in workability when it is installed on an outdoor roof or the like. In addition, there has been a demand for thinner and lighter solar cells. Recently, flexible solar cells using a flexible plastic film as a substrate have been put into practical use and have flexibility. A solar cell using a resin thin film such as polyethylene terephthalate resin (PET) or polycarbonate as a substrate has already been proposed (see, for example, Patent Document 1).

In general, conversion efficiency, which is an important characteristic of dye-sensitized solar cells, depends on the firing temperature at which a metal oxide semiconductor layer such as titanium oxide is formed. To improve the conversion efficiency, the firing temperature is increased. It is necessary to. In the case of a type using a glass substrate as a hard transparent substrate as in the prior art, the film is usually formed at 300 ° C. or higher. However, when using a plastic film as described above, 150 ° C. from the viewpoint of heat resistance. The film formation is as follows, and the conversion efficiency is inevitably lowered. Therefore, the characteristics of the obtained solar cell are insufficient. In addition, when used outdoors for a long period of time, the plastic film on the substrate is particularly yellowed and deteriorated by ultraviolet light, and the transparency is lowered. Therefore, the amount of power generation is reduced because sunlight cannot be taken in sufficiently.
Japanese Patent Laid-Open No. 55-4994

  Therefore, the object of the present invention is to provide strength, transparency, heat resistance, light resistance and dimensional stability like inorganic glass, as well as high toughness and workability like plastic, and also to bend resistance. An object of the present invention is to provide a dye-sensitized solar cell that has excellent conversion efficiency and can be used for a long time by using an excellent hard transparent substrate.

  As a result of diligent investigations to solve the problems described above, the present inventors have obtained a cage-type structure with respect to a flexible substrate that replaces the glass substrate conventionally used in dye-sensitized solar cells. A silicone resin mainly composed of polyorganosilsesquioxane having a combination of the excellent performance of a glass substrate and a resin film substrate, excellent flex resistance, and curing this silicone resin. It was found that if a hard transparent substrate was used, the metal oxide semiconductor layer could be formed at a high temperature, and the present invention was completed.

That is, the present invention has a photoelectrode in which a transparent conductive layer and a porous metal oxide semiconductor layer are sequentially laminated on at least a hard transparent substrate, and a dye is adsorbed on the metal oxide semiconductor layer, and a conductive layer. A dye-sensitized solar cell comprising a counter electrode, and the photoelectrode and an electrolyte layer interposed between the counter electrode, wherein the hard transparent substrate has the following general formula (1)
(RSiO _1.5 ) _m (RSiO _0.5 ) _n (1)
[However, R is an unsaturated group or alkyl group represented by (a) -R ¹ —OCO—CR ² ═CH ₂ , (b) —R ¹ —CR ² ═CH ₂ or (c) —CH═CH ₂ ) , A cycloalkyl group, a cycloalkenyl group, a phenyl group, a hydrogen atom, an alkoxyl group, or an alkylsiloxy group, and a plurality of R in the formula (1) may be different from each other, but at least one of the above ( any one of a), (b) or (c), R ¹ represents an alkylene group, an alkylidene group or a phenylene group, R ² represents hydrogen or an alkyl group, m = 8 to 16, n = 0 to The number 4 is shown. It is a dye-sensitized solar cell obtained by curing a silicone resin mainly composed of a polyorganosilsesquioxane having a cage structure in a structural unit.

  In the present invention, a compound having at least one hydrosilyl group and / or a compound having an ethylenically unsaturated group in the molecule is blended with the silicone resin, and a hydrosilylation catalyst and / or a radical initiator is blended. Then, after obtaining a curable resin composition, the curable resin composition may be heat-cured or photocured to obtain a hard transparent substrate.

The present invention will be specifically described below.
The hard transparent substrate constituting the dye-sensitized solar cell in the present invention is formed by curing a silicone resin as specifically described below. That is, the silicone resin used in the present invention is a polyorganosilsesquioxane represented by the above general formula (1) and having a cage structure in the structural unit (hereinafter referred to as “cage polyorganosilsesquioxane”). (Also called) as the main component. Here, the structural unit specifically means a repeating unit represented by m or n in the general formula (1), and the polyorganosilsesquioxane having a cage structure will be described below. In addition, the three-dimensional polyhedral structure skeleton and R are included, and among these, a structure in which a part of the three-dimensional polyhedral structure skeleton is opened (that is, an incomplete cage structure) is also included.

  Here, in general formula (1), at least one of R needs to be the unsaturated group represented by the above (a), (b) or (c), and these unsaturated groups Specific examples include 3-methacryloxypropyl group, 3-acryloxypropyl group, aryl group, vinyl group, and styryl group.

（上記各式中、Ｒの少なくとも一部は一般式（１）で表される基を示し、また、ｌは繰返し数を示す。なお、ｌの範囲は特に限定されないが、通常、２〜３０である。） In addition to the polyorganosilsesquioxane having a cage structure, the silicone resin of the present invention may include a silicone resin not including a cage structure having the following structure, and the ratio may be less than 30 wt%. desirable.

(In each of the above formulas, at least a part of R represents a group represented by the general formula (1), and l represents the number of repetitions. The range of l is not particularly limited, but is usually 2-30. .)

The general formula (1) represents a cage siloxane composed of a three-dimensional polyhedral structure skeleton and R. As an example, a case where m in the general formula (1) is 8 and n is 0 is shown below. In the structural formula (3), the case where m is 10 and n is 0 is the following structural formula (4), the case where m is 12 and n is 0 is the following structural formula (5), and m is The cases where n is 8 and n is 2 are shown in the following structural formula (6). However, the silicone resin represented by the general formula (1) is not limited to those shown in the structural formulas (3), (4), (5), and (6).

The cage siloxane represented by the structural formulas (3), (4), and (5) is represented by the following general formula (7).
RSix ₃ (7)
[However, R is an unsaturated group or alkyl group represented by (a) -R ¹ -OCO-CR ² = CH ₂ , (b) -R ¹ -CR ² = CH ₂ or (c) -CH = CH ₂ , A cycloalkyl group, a cycloalkenyl group, a phenyl group, a hydrogen atom, an alkoxyl group, or an alkylsiloxy group, R ¹ represents an alkylene group, an alkylidene group, or a phenylene group, and R ² represents a hydrogen or an alkyl group. X represents one kind of hydrolyzable group selected from the group consisting of an alkoxy group, a halogen atom, and a hydroxyl group. It can be obtained by hydrolysis and partial condensation with one or both of a solvent and a polar solvent.

  In addition, the cage siloxane represented by the structural formula (6) is the same as the cage siloxane represented by the structural formula (3), (4) or (5) in the presence of a nonpolar solvent and a basic catalyst. The recondensate obtained by recondensation can be obtained by equilibrating a disiloxane compound.

  Examples of the polar solvent used in obtaining the cage siloxanes of the structural formulas (3) to (6) include methanol, ethanol, 2-propanol, and alcohols. Moreover, about a nonpolar solvent, toluene, xylene, benzene etc. can be mentioned, for example. Examples of the basic catalyst include ammonium hydroxide salts such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, and benzyltriethylammonium hydroxide. Of these, tetramethylammonium hydroxide is preferably used because of its high catalytic activity. The basic catalyst is usually used as an aqueous solution.

  In the present invention, the silicone resin is compounded with either a compound having at least one ethylenically unsaturated double bond in the molecule or a compound having at least a hydrosilyl group in the molecule. It is good also as a resin composition, and it is good also considering these both as a curable resin composition. And you may make it obtain such a hard transparent substrate by thermosetting or photocuring such a curable resin composition. Here, when a compound having at least one ethylenically unsaturated double bond is included in the molecule, it is preferable to include a radical initiator in the curable resin composition, and at least hydrosilylation in the molecule. When a compound having a group is blended, a hydrosilylation catalyst is preferably included in the curable resin composition.

  The compound having at least one ethylenically unsaturated double bond in the molecule may be any unsaturated compound capable of radical copolymerization with a silicone resin, but is suitable for blending with the silicone resin. Are roughly classified into a reactive oligomer which is a polymer having about 2 to 20 repeating structural units, and a reactive monomer having a low molecular weight and a low viscosity. Further, it can be broadly classified into a monofunctional unsaturated compound having one unsaturated group and a polyfunctional unsaturated compound having two or more. In order to obtain a good three-dimensional cross-linked product, it is preferable to contain a very small amount of polyfunctional unsaturated compound (about 1% or less), but per molecule when the heat resistance and strength of the copolymer are expected. The average is 1.1 or more, preferably 1.5 or more, and more preferably 1.6 to 5. For this purpose, it is preferable to adjust the average number of functional groups using a mixture of a monofunctional unsaturated compound and a polyfunctional unsaturated compound having 2 to 5 unsaturated groups.

  Specifically, as reactive oligomers, for example, epoxy acrylate, epoxidized oil acrylate, urethane acrylate, unsaturated polyester, polyester acrylate, polyether acrylate, vinyl acrylate, polyene / thiol, silicone acrylate, polybutadiene, polystyrylethyl methacrylate, etc. Can be illustrated. These include monofunctional unsaturated compounds and polyfunctional unsaturated compounds, and reactive monofunctional monomers include styrene, vinyl acetate, N-vinylpyrrolidone, butyl acrylate, 2-ethylhexyl acrylate, n-hexyl acrylate, Examples include cyclohexyl acrylate, n-decyl acrylate, isobornyl acrylate, dicyclopentenyloxyethyl acrylate, phenoxyethyl acrylate, trifluoroethyl methacrylate, and the like. In addition, reactive polyfunctional monomers include unsaturated compounds other than the general formula (2) such as tripropylene glycol diacrylate, 1,6-hexanediol diacrylate, bisphenol A diglycidyl ether diacrylate, and tetraethylene glycol diacrylate. Examples thereof include acrylate, hydroxypivalate neopentyl glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, and the like.

  As the compound having at least one ethylenically unsaturated double bond in the molecule that can be used in the present invention, various reactive oligomers or monomers can be used in addition to those exemplified above. These reactive oligomers and monomers may be used alone or in combination of two or more. Similarly, a silicone resin copolymer can be obtained by radical copolymerization thereof.

  As a radical initiator to be blended with a compound having at least one ethylenically unsaturated double bond in the molecule, a photopolymerization initiator or a thermal polymerization initiator may be used. Here, as the photopolymerization initiator, compounds such as acetophenone-based, benzoin-based, benzophenone-based, thioxanthone-based, and acylphosphine oxide-based compounds can be suitably used. Specifically, trichloroacetophenone, diethoxyacetophenone, 1-phenyl-2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- (4-methylthiophenyl) -2 -Morpholinopropan-1-one, benzoin methyl ether, benzyldimethyl ketal, benzophenone, thioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, methylphenylglyoxylate, camphorquinone, benzyl, anthraquinone, Michler's ketone, etc. can do. Moreover, the photoinitiator adjuvant and the sharpening agent which show an effect in combination with a photoinitiator can also be used together. These photopolymerization initiators may be used alone or in combination of two or more.

  In addition, as the thermal polymerization initiator used for the above purpose, ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxydicarbonate, peroxyester Various organic peroxides can be suitably used. Specifically, cyclohexanone peroxide, 1,1-bis (t-hexaperoxy) cyclohexanone, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, diisopropyl peroxide, t-butyl peroxide-2-ethyl Although hexanoate etc. can be illustrated, it is not restrict | limited at all to this. These thermal polymerization initiators may be used alone or in combination of two or more.

  When a photopolymerization initiator or a thermal polymerization initiator is blended as a radical initiator, the amount added should be in the range of 0.1 to 5 parts by weight with respect to 100 parts by weight of the silicone resin. It is more preferable to use the range of parts by weight. If this addition amount is less than 0.1 parts by weight, curing is insufficient and the strength and rigidity of the resulting substrate are lowered. On the other hand, if it exceeds 5 parts by weight, problems such as coloring of the substrate may occur.

  On the other hand, the compound having at least a hydrosilyl group in the molecule is preferably an oligomer or monomer having at least one hydrosilylatable hydrogen atom on the silicon atom in the molecule. Examples of the oligomer having a hydrogen atom on a silicon atom include polyhydrogensiloxanes, polydimethylhydroxysiloxanes and copolymers thereof, and siloxanes whose ends are modified with dimethylhydrosiloxy. Examples of the monomer having a hydrogen atom on a silicon atom include cyclic siloxanes such as tetramethylcyclotetrasiloxane and pentamethylcyclopenta, dihydrodisiloxanes, trihydromonosilanes, dihydromonosilanes, and monohydromonosilanes. And dimethylsiloxysiloxanes. Two or more of these may be mixed.

  For hydrosilylation catalysts formulated with compounds having at least a hydrosilyl group in the molecule, platinum chloride, chloroplatinic acid, chloroplatinic acid and alcohol, aldehyde, ketone complex, chloroplatinic acid and olefin complex And platinum group metal catalysts such as platinum and vinylsiloxane complexes, dicarbonyldichloroplatinum and palladium catalysts, rhodium catalysts, and the like. Among these, those selected from chloroplatinic acid, complexes of chloroplatinic acid and olefins, and complexes of platinum and vinylsiloxane are preferable from the viewpoint of catalytic activity. Moreover, these may be used independently and may be used together 2 or more types.

  When the hydrosilylation catalyst is blended, the amount added is preferably 1 to 1000 ppm, more preferably 20 to 500 ppm as a metal atom based on the weight of the silicone resin. Further, the hydrosilylation catalyst may be used alone or in combination with two or more of the radical initiators described above.

  In the present invention, when obtaining the curable resin composition containing the silicone resin, at least in the molecule for the purpose of obtaining a rigid transparent substrate by curing the silicone resin and improving the physical properties of the rigid transparent substrate. A compound having one ethylenically unsaturated double bond, a compound having at least a hydrosilyl group in the molecule, a radical initiator, a hydrosilylation catalyst, and the like may be appropriately selected and blended. That is, when a compound having an ethylenically unsaturated double bond or a compound having a hydrosilyl group is blended, a hydrosilylation catalyst or radical initiator (thermal polymerization initiator or photopolymerization initiator) is used as an additive for promoting the reaction. In addition, a thermal polymerization accelerator, a photoinitiator assistant, a sharpener, and the like may be added. In addition, organic / inorganic fillers, plasticizers, flame retardants, thermal stabilizers, antioxidants, light stabilizers, ultraviolet absorbers, lubricants, antistatic agents, mold release agents are within the scope of the present invention. Various additives such as a foaming agent, a nucleating agent, a colorant, a crosslinking agent, a dispersion aid, and a resin component can also be added.

  In the present invention, a hard transparent substrate is obtained by molding a curable resin composition into a predetermined shape and curing it by heating or light irradiation according to the type and application of the target dye-sensitized solar cell. You can do it. Here, when a copolymer (hard transparent substrate) is obtained by heating, the temperature can be selected from a wide range from room temperature to around 200 ° C., depending on the selection of a thermal polymerization initiator and an accelerator. On the other hand, when obtaining a hard transparent substrate by light irradiation, it can be cured by irradiating ultraviolet rays having a wavelength of 100 to 400 nm or visible rays having a wavelength of 400 to 700 nm. The wavelength of the light to be used is not particularly limited, but near ultraviolet light having a wavelength of 200 to 400 nm is particularly preferably used. The lamps used as ultraviolet light sources include low-pressure mercury lamps (output: 0.4 to 4 W / cm), high-pressure mercury lamps (40 to 160 W / cm), ultra-high pressure mercury lamps (173 to 435 W / cm), metal halide lamps (80 ˜160 W / cm), pulse xenon lamp (80 to 120 W / cm), electrodeless discharge lamp (80 to 120 W / cm), and the like. Each of these ultraviolet lamps is characterized by its spectral distribution, and is therefore selected according to the type of photoinitiator used.

  The thickness of the hard transparent substrate obtained is preferably 5 to 500 μm from the viewpoint of flexibility. When the thickness is less than 5 μm, when the metal oxide semiconductor layer is laminated, the hard transparent substrate may be deformed without alleviating the thermal stress applied during the lamination. On the other hand, when the thickness exceeds 500 μm, flexibility is insufficient, and continuous rollup, which is one of the advantages of using a flexible substrate, becomes difficult.

  As the hard transparent substrate in the present invention, a film laminate obtained by casting and curing the curable resin composition on at least one surface of a transparent plastic film can be used. In the transparent plastic film, it is preferable to use a transparent plastic film having a glass transition temperature (heat resistance temperature) of 70 ° C. or higher. If the glass transition temperature is less than 70 ° C., the hard transparent substrate may be deformed without alleviating the thermal stress applied when the metal oxide semiconductor layer is laminated. A transparent plastic film having a glass transition temperature of 220 ° C. or lower is effective. When the heat resistance temperature of the transparent plastic film exceeds 220 ° C., these films have sufficient heat resistance, and the intention of producing the laminate structure according to the present invention is reduced.

  Examples of such transparent plastic film materials include PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PBT (polybutylene phthalate), COP (cycloolefin polymer), COC (cycloolefin copolymer), PC (polycarbonate), Examples of the film include acetate, acrylic, vinyl fluoride, polyamide, polyarylate, cellophane, polyethersulfone, and norbornene resin. These films can be used alone or in combination of two or more. In particular, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), COP (cycloolefin polymer), and COC (cycloolefin copolymer), which are excellent in heat resistance and transparency and have various properties balanced, are preferable. In addition, it is desirable to use a transparent plastic film having excellent adhesion to the film obtained by curing the curable resin composition. In order to further improve the adhesion to the cured film, for example, corona discharge treatment is applied to the film surface. Surface activation treatment such as ultraviolet irradiation treatment or plasma treatment may be performed.

  About the thickness of a transparent plastic film, it is necessary to satisfy | fill the ratio of thickness with a cured film, However As an independent thickness, Preferably it is 0.05 mm or more. When the thickness of the transparent plastic film is less than 0.05 mm, there is a risk of deformation due to shrinkage at the time of curing of the curable resin composition, and there is a possibility that it cannot withstand the tension at the time of coating. In addition, about the surface shape of a transparent plastic film, even if it has flatness, the uneven | corrugated process may be given to the surface. However, a surface shape that does not hinder transparency is preferable.

  Since the curable resin composition is in a liquid state, it can be applied with a known coating apparatus. However, if a curing reaction is caused by using a coating head, the gel-like deposits cause streaks and foreign matter, so that the coating head is desirable. It is better not to be exposed to UV rays. As a coating method, known methods such as gravure coating, roll coating, reverse coating, knife coating, die coating, lip coating, doctor coating, extrusion coating, slide coating, wire bar coating, curtain coating, extrusion coating, spinner coating, etc. Can be used.

  The curable resin composition is applied to a transparent plastic film and cast and then cured. As a curing method, heat or photocuring can be used as described above.

  The structure of the dye-sensitized solar cell is not particularly limited, and a conventionally known structure can be adopted. One example is a dye-sensitized solar cell including the photoelectrode 1, the counter electrode 9, and the electrolyte layer 6 shown in FIG. Here, the photoelectrode 1 includes a hard transparent substrate 2, a transparent conductive layer 3, a metal oxide semiconductor layer 4, and a dye 5 carried on the metal oxide semiconductor layer 4. The counter electrode 9 may be formed of a transparent conductive layer 7 and a hard transparent substrate 8 as shown in FIG. 1. In addition to the hard transparent substrate, a transparent film such as polyethylene terephthalate or polycarbonate and a transparent conductive layer You may form from.

In addition to the hard transparent substrate, each material forming the dye-sensitized solar cell of the present invention is not particularly limited, and conventionally known materials can be used. For example, as the transparent conductive layers 3 and 7, tin oxide, zinc oxide doped with fluorine, indium, or the like, and other transparent transparent conductors with little absorption in the visible light region can be used. Further, as the metal oxide semiconductor layer 4, a metal oxide exhibiting n-type semiconductor properties can be used. Specific examples include oxides of zinc, niobium, tin, titanium, vanadium, indium, tungsten, tantalum, zirconium, molybdenum, and manganese. In addition, perovskites such as SrTiO ₃ , CaTiO ₃ , BaTiO ₃ , MgTiO ₃ , SrNb ₂ O ₆ , or complex oxides or oxide mixtures thereof can also be used. Furthermore, as the dye 5, for example, a transition metal complex such as ruthenium, a metal such as phthalocyanine or porphine, or a nonmetal can be used as appropriate. Furthermore, the electrolyte layer 6 can be formed using an appropriate redox material such as a combination of iodide ions and iodine. The redox form contains an appropriate solvent that can dissolve the redox form.

  The method for producing the dye-sensitized solar cell of the present invention is not particularly limited, and a conventionally known production method can be adopted. One example will be described below. The transparent conductive layer 3 is formed on the surface of either one of the hard transparent substrates 2 of the present invention by a vacuum film formation process such as sputtering, and a metal oxide sol is applied on the transparent conductive layer 3, The metal oxide semiconductor layer 4 is formed by baking at the temperature-time. Further, the hard transparent substrate 2 on which the transparent conductive layer 3 and the metal oxide semiconductor 4 are formed is immersed in a dye solution in which a dye is dissolved in a predetermined solvent, and the dye is adsorbed and supported on the metal oxide semiconductor layer 4. By doing so, the photoelectrode 1 is obtained. Next, after overlapping the counter electrode 9 having the conductive layer 7 formed on the hard transparent substrate 8 by a method similar to that of the photoelectrode 1 through a spacer, an oxidation-reduction body forming the electrolyte layer 6 is injected and sealed. A dye-sensitized solar cell can be obtained by sealing with an agent.

  In the dye-sensitized solar cell of the present invention, a near-infrared shielding film (IR cut filter) may be formed on a hard transparent substrate for the purpose of shielding near-infrared rays that may damage the substrate. The IR cut filter is formed by a method of forming a metal or metal oxide thin film on the hard transparent substrate, or a method of laminating metal or metal oxide thin films having different refractive indexes on the hard transparent substrate in multiple layers. Can do.

  The formation of a thin film of metal or metal oxide for obtaining an IR cut filter is not particularly limited, but can be formed by, for example, a CVD method, a sputtering method, a vacuum evaporation method, or the like. In these methods, since the shielding film is usually formed under a temperature condition of about 100 to 300 ° C., a substrate that does not warp during the formation is preferable, and the hard transparent substrate of the present invention is also from the viewpoint of its heat resistance. Is preferred.

  The dye-sensitized solar cell of the present invention has strength, transparency, heat resistance, light resistance and dimensional stability like glass, and has high toughness and workability like plastic, and is also flexible. In addition, since an excellent hard transparent substrate is used, it is possible to reduce the thickness and weight, and the workability such as installation is improved as compared with the conventional case. Furthermore, if this hard transparent substrate is used, film formation at a high temperature becomes possible, so that conversion efficiency can be improved and excellent durability can be exhibited over a long period of time.

  Hereinafter, the present invention will be specifically described based on examples and the like. The scope of the present invention is not limited by these examples.

  Examples of the present invention will be described below. The curable resin used in the following examples was obtained by the method shown in the following synthesis examples.

<Synthesis Example 1>
A reaction vessel equipped with a stirrer, a dropping funnel, and a thermometer was charged with 40 ml of 2-propanol (IPA) as a solvent and a 5% tetramethylammonium hydroxide aqueous solution (TMAH aqueous solution) as a basic catalyst. Into the dropping funnel, 15 ml of IPA and 12.69 g of 3-methacryloxypropyltrimethoxysilane (MTMS: SZ-6300 manufactured by Toray Dow Corning Silicone Co., Ltd.) were added, and the IPMS solution of MTMS was 30 at room temperature while stirring the reaction vessel It was added dropwise over a period of minutes. After completion of the MTMS addition, the mixture was stirred for 2 hours without heating. After stirring for 2 hours, the solvent was removed under reduced pressure and dissolved in 50 ml of toluene. The reaction solution was washed with saturated brine until neutral, and then dehydrated with anhydrous magnesium sulfate. 8.6 g of hydrolysis product (silsesquioxane) was obtained by filtering off anhydrous magnesium sulfate and concentrating. This silsesquioxane was a colorless viscous liquid soluble in various organic solvents.

Next, 8.0 g of silsesquioxane obtained above, 32 ml of toluene, and 1.2 g of 10% TMAH aqueous solution were placed in a reaction vessel equipped with a stirrer, a Dinsterk, and a cooling tube, and heated gradually to remove water. Distilled off. Further, the mixture was heated to 130 ° C., and toluene was recondensed at the reflux temperature. The temperature of the reaction solution at this time was 108 ° C. After stirring for 2 hours after refluxing toluene, the reaction was terminated. The reaction solution was washed with saturated brine until neutral, and then dehydrated with anhydrous magnesium sulfate. The anhydrous magnesium sulfate was filtered off and concentrated to obtain a cage silsesquioxane (silicone resin) represented by the following formula (8) (yield 7.5 g, yield 87%). The resulting cage-type silsesquioxane was a colorless viscous liquid soluble in various organic solvents.
[CH ₂ = CH (CH ₃ ) OCO (CH ₂ ) ₃ SiO _1.5 ] _m [CH ₂ = CH (CH ₃ ) OCO (CH ₂ ) ₃ SiO _0.5 ] _n (8)

  The main peaks detected by mass spectrometry using the liquid chromatography atmospheric pressure ionization analyzer (LC / APCl-MS) of the silicone resin (8) obtained in Table 1 and m and n of the corresponding silicone resin (8) The numerical values that apply to are collectively shown. The detected peak m / z is a value obtained by adding ammonium ions to the molecular weight of the silicone resin represented by the silicone resin (7) (where m is 8 to 16 and n is 0 to 4).

<Synthesis Example 2>
A reaction vessel equipped with a stirrer, a dropping funnel, and a thermometer was charged with 150 ml of toluene and 85 ml of 2-propanol (IPA) as a solvent, and 5% tetramethylammonium hydroxide aqueous solution (TMAH aqueous solution) as a basic catalyst. ) 37.2g was charged. To the dropping funnel, 25 ml of toluene and 50.3 g of trimethoxyvinylsilane (KBM1003 manufactured by Shin-Etsu Chemical Co., Ltd.) were added, and a toluene solution of trimethoxyvinylsilane was added dropwise at room temperature over 3 hours while stirring the reaction vessel. After completion of the dropwise addition of trimethoxyvinylsilane, the mixture was stirred at room temperature for 2 hours. After stirring for 1 hour, stirring was stopped and the mixture was allowed to stand for 1 day. The reaction solution was neutralized with 23.0 g of 10% aqueous citric acid solution, washed with saturated brine, and dehydrated over anhydrous magnesium sulfate. Anhydrous magnesium sulfate was filtered off and concentrated to obtain 20.6 g of polycondensate (yield 77%). This polycondensate was a white solid hardly soluble in various organic solvents.

  Next, 15.0 g of the polycondensate obtained above, 380 ml of toluene, and 1.72 g of 5% TMAH aqueous solution were placed in a reaction vessel equipped with a stirrer, dinstark, condenser, and thermometer, and water was distilled off at 120 ° C. Then, toluene was heated to reflux to carry out a recondensation reaction. The mixture was stirred for 3 hours after refluxing toluene, and then returned to room temperature to complete the reaction. The reaction solution was neutralized with 23.0 g of 10% citric acid, washed with saturated brine, and dehydrated over anhydrous magnesium sulfate. The anhydrous magnesium sulfate was filtered off and concentrated to obtain 14.5 g of a recondensate. The obtained recondensate is a white solid and variously insoluble in a solvent.

Finally, 14.5 g of the recondensate obtained above in a reaction vessel equipped with a stirrer, a Dinsterk, and a condenser, 300 ml of toluene, 3.0 g of 5% TMAH aqueous solution, and 1,3-divinyl-1,1, 9.76 g of 3,3-tetramethyldisiloxane (TMDVDS: LS-7250 manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and toluene was refluxed while distilling off water at 120 ° C. to perform a recondensation reaction. The mixture was stirred for 3 hours after refluxing toluene, and then returned to room temperature to complete the reaction. The reaction solution was neutralized with 3.24 g of 10% citric acid, washed with saturated brine, and dehydrated over anhydrous magnesium sulfate. Anhydrous magnesium sulfate was filtered off and concentrated to obtain a silicone resin having the following average composition formula (9) (yield 16.9 g, yield 88%). The obtained silicone resin was a colorless viscous liquid soluble in various organic solvents.
[CH ₂ = CHSiO _1.5 ] _m [CH ₂ = CH (CH ₃ ) ₂ SiO _0.5 ] _n (9)

  The main peaks detected by mass spectrometry using the liquid chromatography atmospheric pressure ionization analyzer (LC / APCl-MS) of the silicone resins obtained in Table 2 and the numerical values corresponding to n and m of the corresponding silicone resin (8) Are shown together. The detected peak m / z is a value obtained by adding ammonium ions to the molecular weight of the silicone resin (9) represented by the silicone resin (9) (where m is 8 to 16 and n is 0 to 4).

(Specimen No.1)
25 parts by weight of a cage-type silicone resin having a methacryloyl group obtained on Synthesis Example 1 on a silicon atom, 75 parts by weight of dicyclopentanyl diacrylate, and 2.5 parts by weight of 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator Were mixed to obtain a transparent curable resin composition (silicone resin composition). Table 3 shows the composition of the silicone resin composition used in this specimen No. 1. The numerical values in Table 3 represent parts by weight.

A part of the curable resin composition is poured into a mold formed of glass plates so as to have a thickness of 2 mm, and cured using a 30 W / cm high-pressure mercury lamp with an accumulated exposure amount of 2000 mJ / cm ² to a predetermined thickness. A hard substrate was obtained. The physical properties of the hard substrate were evaluated as follows.

1) Total light transmittance (reference standard JIS K 7361-1)
It measured using the ultraviolet visible light infrared spectrophotometer (V-630M JASCO Corporation make).

2) Bending test Both ends of the hard transparent substrate were bent so as to have a curvature radius of 5 mm and held for 5 minutes. The state of the bent part after that was confirmed visually. The evaluation was made in two stages: ○: no change, Δ: marks remained on the bent part of the film.

3) Heat resistance The film shape (curl presence or absence) after heat-treating the hard transparent substrate at 250 ° C. for 1 hour was observed. Table 4 shows the results.

(Specimen No.2-4)
A hard substrate was obtained in the same manner as the specimen No. 1 except that the composition of the curable resin composition was as shown in Table 3. In addition, the physical property values of the obtained hard substrate were evaluated in the same manner as the specimen No. 1. The results are shown in Table 4.

(Specimen No. 5)
60 parts by weight of resin having vinyl group on silicon obtained in Synthesis Example 2, 40 parts by weight of terminal hydrogen-modified methylhydrosiloxane-phenylmethylsiloxane copolymer (HPM-502 manufactured by Amax Co., Ltd.), and platinum-vinylsiloxane complex (AIPMAX Co., Ltd. SIP6830.3) 0.5 part by weight was mixed until uniform, to obtain a curable resin composition. Table 5 shows the composition of the curable resin composition used in this specimen No. 5. In addition, the numerical value in Table 5 represents a weight part.

  The curable resin composition obtained above was poured into a mold composed of glass plates so as to have a thickness of 2 mm, 100 ° C for 1 hour, 120 ° C for 1 hour, 140 ° C for 1 hour, 160 ° C for 1 hour, 180 ° C. A hard substrate having a predetermined thickness was obtained by heating at 0 ° C. for 2 hours. The physical property values of the obtained hard substrate were evaluated in the same manner as specimen No. 1. The results are shown in Table 4.

(Specimen No. 6-8)
A hard substrate was obtained in the same manner as in the specimen No. 5 except that the composition of the curable resin composition was as shown in Table 5. The physical property values of the obtained hard substrate were similarly evaluated. The results are shown in Table 4.

(Specimen No. 9)
A curable resin composition having the same composition as the above specimen No. 1 was applied on a transparent film (PET: polyethylene terephthalate film, thickness 0.1 mm, light transmittance 90% or more at a wavelength of 550 nm) with a bar coater. Using a 30 W / cm high-pressure mercury lamp, curing was performed with an integrated exposure amount of 2000 mJ / cm ² . Then, a hard substrate having a curable resin layer formed on both sides of the PET film by applying a curable resin composition having the same composition to the opposite surface of the resin layer obtained by curing and photocuring under the same conditions. Obtained. The thickness of one side of the resin layer obtained by curing was set to 0.05 mm. The physical property values of the obtained hard substrate were similarly evaluated. The results are shown in Table 4.

(Specimen No. 10)
A rigid substrate was obtained in the same manner as in the specimen No. 9 except that a cycloolefin copolymer film (A4 size, thickness 0.1 mm, light transmittance at wavelength 550 nm of 85% or more) was used as the transparent film. The physical property values of the obtained hard substrate were similarly evaluated. The results are shown in Table 4.

[Example 1]
First, in the photoelectrode 1, indium tin oxide (ITO) was formed as the transparent conductive layer 3 on the hard transparent substrate 2 made of the specimen No. 1 by vacuum sputtering. On this, titanium oxide was coated as a metal oxide semiconductor layer 4 on a bar coat, and then dried using a dryer at 300 ° C. As a raw material for titanium oxide, a titanium oxide sol was synthesized using a sol-gel method by hydrolyzing titanium tetra-t-butoxide with nitric acid, and the obtained titanium oxide sol was used. By immersing the laminate obtained above in an ethanol solution of bis (4,4-dicarboxy-2,2-bipyridyl) dithiocyanate ruthenium, bis (4,4-dicarboxy-2, After supporting 2-bipyridyl) dithiocyanate ruthenium, photoelectrode 1 was obtained by washing with water and ethanol, and drying.

As the counter electrode 9, a transparent conductive layer 7 made of indium tin oxide (ITO) formed by sputtering on the hard transparent substrate 8 made of specimen No. 1 was used. The photoelectrode 1 and the counter electrode 9 described above are overlapped with a spacer so that the film formation surfaces face each other, and I ₂ having a concentration of 0.25 mol / l and a t- concentration of 0.6 mol / l in acetonitrile. A dye-sensitized solar cell was manufactured by injecting a redox body containing BuPy to form the electrolyte layer 6 and sealing the side surface with a silicone-based adhesive resin.

[Examples 2 to 10]
A dye-sensitized solar cell was produced in the same manner as in Example 1 using the specimens No. 2 to No. 10 and the hard transparent substrate.

[Example 11]
A titanium dioxide (film thickness 120 to 190 nm) layer and silicon dioxide (film thickness 70 to 120 nm) as a high refractive material on one side of the hard transparent substrate made of specimen No. 1 ) Layers were alternately laminated by a sputtering method to form a near-infrared shielding film having a total number of laminations of 50. Using this substrate, a dye-sensitized solar cell was produced in the same manner as in Example 1.

[Comparative Example 1]
A solar cell was produced in the same manner as in Example 1 except that a commercially available PET film was used as the hard transparent substrate and the titanium oxide was dried at 150 ° C.

The battery characteristics of the dye-sensitized solar cells created in Examples and Comparative Examples were obtained by irradiating a sample cell with 100 mA / cm ² pseudo-sunlight and using a potentiostat and a function generator to sweep the potential. From the photocurrent potential curve, the short-circuit current, open-circuit voltage, F.V. F (fill factor) was determined, and the conversion efficiency was determined from these values. Table 6 shows the evaluation results.

FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a dye solar cell according to the present invention.

Explanation of symbols

1: Photoelectrode 2: Hard transparent substrate 3: Transparent conductive layer 4: Metal oxide semiconductor layer 5: Dye 6: Electrolyte layer 7: Transparent conductive layer 8: Hard transparent substrate 9: Counter electrode

Claims (5)

At least a transparent conductive layer and a porous metal oxide semiconductor layer are sequentially stacked on a hard transparent substrate, and a photoelectrode in which a dye is adsorbed to the metal oxide semiconductor layer, a counter electrode having a conductive layer, and the light A dye-sensitized solar cell comprising an electrode and an electrolyte layer interposed between the counter electrode,
The hard transparent substrate has the following general formula (1)
(RSiO _1.5 ) _m (RSiO _0.5 ) _n (1)
[However, R is an unsaturated group or alkyl group represented by (a) -R ¹ —OCO—CR ² ═CH ₂ , (b) —R ¹ —CR ² ═CH ₂ or (c) —CH═CH ₂ ) , A cycloalkyl group, a cycloalkenyl group, a phenyl group, a hydrogen atom, an alkoxyl group, or an alkylsiloxy group, and a plurality of R in the formula (1) may be different from each other, but at least one of the above ( any one of a), (b) or (c), R ¹ represents an alkylene group, an alkylidene group or a phenylene group, R ² represents hydrogen or an alkyl group, m = 8 to 16, n = 0 to The number 4 is shown. A dye-sensitized solar cell obtained by curing a silicone resin mainly composed of a polyorganosilsesquioxane having a cage structure in a structural unit.   The hard transparent substrate contains a compound having at least one ethylenically unsaturated double bond in the molecule and / or a compound having at least a hydrosilyl group in the molecule, and further a radical initiator and / or a silicone resin. The dye-sensitized solar cell according to claim 1, wherein a curable resin composition obtained by blending a hydrosilylation catalyst is cured.   A film laminate in which a hard transparent substrate is cast-coated with a silicone resin represented by the above general formula (1) on at least one surface of a transparent plastic film having a glass transition temperature of 70 ° C. or higher and 220 ° C. or lower and cured. The dye-sensitized solar cell according to claim 1, wherein the dye-sensitized solar cell is provided.   The hard transparent substrate is formed by casting and curing the silicone resin represented by the general formula (1) on both surfaces of a transparent plastic film having a glass transition temperature of 70 ° C. or higher and 220 ° C. or lower. The dye-sensitized solar cell according to claim 1.   The dye-sensitized solar cell according to any one of claims 1 to 4, wherein a film that blocks near-infrared light is formed on a hard transparent substrate on which a photoelectrode is formed.

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