JP4091463B2 - Photosensitized solar cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photosensitized solar cell.
[0002]
[Prior art]
As a general photosensitized solar cell, an electrode (semiconductor electrode) composed of a semiconductor layer made of metal oxide fine particles having a dye supported thereon, and a transparent electrode (conductive layer) facing the electrode ) And a liquid carrier transfer layer (electrolyte layer) interposed between two electrodes (see, for example, Patent Document 1).
[0003]
The photosensitized solar cell as described above operates through the following process. That is, the light incident on the semiconductor electrode reaches the dye supported on the surface of the semiconductor electrode and excites the dye. The excited dye quickly passes electrons to the semiconductor electrode. On the other hand, the positively charged dye by losing electrons is electrically neutralized by receiving electrons from ions diffused from the electrolyte layer. The ions that have passed the electrons diffuse to the transparent electrode and receive the electrons. The wet photosensitized solar cell operates by using the semiconductor electrode and the transparent electrode facing the semiconductor electrode as a negative electrode and a positive electrode, respectively.
[0004]
In the photosensitized solar cell, after the light incident on the semiconductor electrode reaches the dye supported on the surface of the semiconductor electrode, a part of the light passes through the semiconductor electrode and escapes to the electrolyte layer. Since many electrolyte layers use a reduction pair supplied from a mixture of iodine and iodide as an oxidation-reduction pair, light entering the electrolyte layer is absorbed by the electrolyte layer. For this reason, there is a problem that light is wasted and light utilization efficiency is lowered.
[0005]
[Patent Document 1]
JP 2002-289268 A (page 3-14, FIG. 1)
[0006]
[Problems to be solved by the invention]
In view of this problem, an object of the present invention is to provide a highly efficient photosensitized solar cell.
[0007]
[Means for Solving the Problems]
Therefore, the present invention provides a semiconductor electrode having a dye supported on its surface, a counter substrate disposed on the surface of the semiconductor electrode so as to be spaced apart from the semiconductor electrode, and provided between the semiconductor electrode and the conductive layer. Characterized in that it comprises a spherical insulating particle having a diameter of 40 nm or more and 800 nm or less and a ratio of a major axis to a minor axis of 1.2 or less, and an electrolyte layer having an electrolyte containing iodine molecules and iodide. A photosensitized solar cell is provided.
[0008]
In the present invention, the spherical insulating particles may be ceramic particles.
[0009]
In the present invention, spherical insulating particles may be contained in the electrolyte layer in an amount of 0.05% by volume to 2% by volume.
[0010]
In the present invention, the electrolyte may be a gel electrolyte.
[0011]
In the present invention, the support substrate may be disposed on the surface of the semiconductor electrode opposite to the surface on the electrolyte layer side, and at least one of the support substrate and the counter substrate may be a plastic substrate.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0013]
The photosensitized solar cell of the present invention comprises spherical insulating particles having an average particle size of about 40 nm or more and about 800 nm or less and a ratio of major axis to minor axis of about 1.2 or less, iodine molecules and iodide. And an electrolyte layer having an electrolyte. The reason why the photosensitized solar cell of the present invention needs to have these will be described below.
[0014]
In the photosensitized solar cell, it is most preferable that all incident light is absorbed by the dye supported on the surface of the semiconductor electrode. However, a part of this light passes through the semiconductor electrode and escapes to the electrolyte layer. Since the electrolyte layer contains iodine molecules and iodide, this light is absorbed and the light utilization efficiency is lowered. Therefore, in the present invention, the electrolyte layer includes spherical insulating particles having an average particle size of about 40 nm or more and about 800 nm or less and a ratio of the major axis to the minor axis of about 1.2 or less.
[0015]
As the spherical insulating particles, insulative particles are used so as not to deteriorate the carrier movement characteristics of the electrolyte layer.
[0016]
Then, by making the average particle size of the spherical insulating particles about 40 nm or more and about 800 nm or less, the light entering the electrolyte layer is scattered and returned to the semiconductor electrode, and absorbed by the dye supported on the surface of the semiconductor electrode, Light utilization efficiency can be increased. Since the absorption wavelength region of the dye is in the visible region, that is, about 400 nm or more and about 800 nm or less, if the average particle size is less than about 40 nm, it is out of the range where Rayleigh scattering occurs, and the average particle size exceeds about 800 nm It will deviate from the range where Mie scattering occurs, and light in the visible range cannot be scattered and returned to the semiconductor electrode.
[0017]
At this time, the ratio of the major axis to the minor axis of the spherical insulating particles needs to be 1.2 or less. This is because if the insulating particles are not spherical and the ratio of the major axis to the minor axis exceeds 1.2, the light scattering characteristics are degraded. Here, the spherical shape may have small irregularities as long as the light scattering characteristics are not deteriorated, and may be approximately spherical.
[0018]
In the photosensitized solar cell of the present invention, since the spherical insulating particles are put in the electrolyte layer, solvent resistance and electrical stability are necessary, and therefore ceramic particles are preferable. The ceramic used is not particularly limited, and examples thereof include silica, alumina, zirconia and the like. In addition, since the insulating particles need to be spherical in order to improve the light scattering characteristics, porous particles such as silica gel and activated alumina cannot be used.
[0019]
By the way, when a flexible plastic substrate is used as a counter substrate or a support substrate for supporting a semiconductor electrode, and a planar cell is changed into a curved surface shape, a conductive layer that faces the semiconductor electrode in a place where stress is concentrated. The distance between and may change and become narrower. Further, the interval is narrowed even when pressure is partially applied during use. In such a case, when a semiconductor electrode and a conductive layer contact, there exists a problem of carrying out an internal short circuit. However, in the photosensitized solar cell of the present invention, since spherical insulating particles are added to the electrolyte, the semiconductor electrode of the solar cell and the conductive layer provided on the counter substrate are not in contact with each other, and an internal short circuit is caused. Can be prevented. Therefore, the counter substrate and the support substrate can be plastic substrates. Conventionally, a spacer is included in the electrolyte layer. However, the amount of the spacer is small, the particle size is large, and the light scattering property cannot be obtained, so that the effect of the present invention cannot be obtained.
[0020]
The spherical insulating particles are preferably contained in the electrolyte layer in an amount of about 0.05% by volume or more and about 2% by volume or less in order to improve light scattering characteristics and prevent internal short circuits. By containing about 0.05 volume% or more, light scattering occurs effectively, and an internal short circuit can be prevented, which is preferable. By containing about 2% by volume or less, the viscosity of the electrolyte can be easily injected into the solar cell without increasing.
[0021]
In the present invention, it is preferable to use a gel electrolyte as the electrolyte. Use of the gel electrolyte is desirable because the spherical insulating particles are retained in the non-flowable gel electrolyte, thereby eliminating the problem of changing the dispersion state of the spherical insulating particles.
[0022]
Next, the electrolyte layer used in the photosensitized solar cell of the present invention will be described in detail.
[0023]
The electrolyte layer of the present invention comprises spherical insulating particles having an average particle size of about 40 nm or more and about 800 nm or less and a ratio of major axis to minor axis of about 1.2 or less, iodine molecules (I₂And an electrolyte containing iodide.
(Electrolytes)
The electrolyte used in the present invention contains iodine (I), and I^-And I_Three ^-A reversible redox pair consisting of The reversible redox couple is an iodine molecule (I₂) And iodide.
[0024]
The redox couple as described above desirably exhibits a redox potential smaller by about 0.1 to 0.6 V than the oxidation potential of the dye described later. In the redox pair showing a redox potential 0.1 to 0.6 V lower than the oxidation potential of the dye, for example, a reducing species such as I- can receive holes from the oxidized dye. By containing such a redox pair in the electrolyte, the speed of charge transport between the semiconductor electrode and the conductive layer can be increased, and the open-circuit voltage can be increased.
[0025]
Examples of the iodide in the electrolyte include an alkali metal iodide, an organic compound iodide, and a molten salt of iodide.
[0026]
Examples of the molten salt of iodide include iodides of heterocyclic nitrogen-containing compounds such as imidazolium salts, pyridinium salts, quaternary ammonium salts, pyrrolidinium salts, pyrazolidium salts, isothiazolidinium salts, and isoxazolidinium salts. Etc. can be used.
[0027]
Examples of the molten salt of iodide include 1,3-dimethylimidazolium iodide, 1-ethyl-3-methylimidazolium iodide, 1-methyl-3-propylimidazolium iodide, 1-methyl-3-pentyl. Imidazolium iodide, 1-methyl-3-isopentylimidazolium iodide, 1-methyl-3-hexylimidazolium iodide, 1-methyl-3-isohexyl (branched) imidazolium iodide, 1-methyl-3 Ethyl imidazolium iodide, 1,2-dimethyl-3-propylimidazole iodide, 1-ethyl-3-isopropylimidazolium iodide, 1-propyl-3-propylimidazolium iodide, and pyrrolidinium iodide Etc. Kill. Such a molten salt of iodide can be used alone or in combination of two or more. Further, the content thereof is preferably about 0.005 mol / l or more and 7 mol / l or less in the electrolyte. By setting it to 0.005 mol / l or more, the effect can be sufficiently obtained. On the other hand, by setting it to 7 mol / l or less, the viscosity can be kept low and the ionic conductivity can be kept high.
[0028]
As the alkali metal iodide, lithium iodide, sodium iodide, potassium iodide, or the like can be used.
[0029]
Trimethylamine, triethylamine, tripropylamine, etc. can be used as the iodide of the organic compound.
[0030]
The content of iodine molecules in the electrolyte is preferably 0.01 mol / L or more and 3 mol / L or less. Iodine is mixed with iodide in the electrolyte and acts as a reversible redox pair. Therefore, by setting the iodine content to 0.01 mol / L or more, a sufficient redox pair can be obtained and electric charges can be transported. On the other hand, by setting it as 3 mol / L or less, the light absorption of a solution can be reduced and light can be efficiently given to a semiconductor electrode. The iodine content is more preferably 0.03 mol / L or more and 1.0 mol / L or less.
[0031]
The electrolyte in the present invention may be either liquid or gel, and can contain an organic solvent. By containing the organic solvent, the viscosity of the electrolyte can be further reduced, so that the electrolyte can easily penetrate into the n-type semiconductor electrode.
[0032]
Examples of the organic solvent that can be used include cyclic carbonates such as ethylene carbonate (EC) and propylene carbonate (PC); chain carbonates such as dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate; γ-butyrolactone, acetonitrile, propionic acid Examples include methyl and ethyl propionate. Furthermore, cyclic ethers such as tetrahydrofuran and 2-methyltetrahydrofuran; chain ethers such as dimethoxyethane and diethoxyethane; nitrile solvents such as acetonitrile, propionitrile, glutaronitrile, and methoxypropionitrile It is done. These organic solvents can be used alone or as a mixture of two or more.
[0033]
The content of the organic solvent is not particularly limited, but is preferably 80% by weight or less in the electrolyte. If the content of the organic solvent exceeds 80% by weight, performance may be deteriorated due to volatilization. The content of the organic solvent is more preferably 30% by weight or less.
[0034]
When setting it as a gel-like electrolyte layer, in addition to the electrolyte mentioned above, you may contain a gelatinizer. The gelling agent contains at least one kind of a halogen-containing compound or a divalent or higher-valent metal compound and at least one element selected from the group consisting of N, P and S, and the halogen-containing compound forms an onium salt. And a compound capable of forming a complex (hereinafter referred to as Compound A) with a metal compound. As described above, in the present invention, since the spherical insulating particles are retained in the non-flowable gel electrolyte by using the gel electrolyte layer, there is no problem that the dispersion state of the spherical insulating particles changes. Desirable for.
[0035]
Compound A contains at least one element selected from the group consisting of N, P, and S, and can form an onium salt with the halogen-containing compound. The compound A contains at least one element selected from the group consisting of N, P, and S, and can form a complex with the metal compound.
[0036]
Compound A preferably has two or more groups (N, P, S-containing groups) containing at least one atom selected from the group consisting of N, P and S per molecule. The N, P, and S-containing groups present in one molecule may be of the same type, but one molecule may have two or more different N, P, and S-containing groups. When the number of N, P, and S-containing groups per molecule is one, polymerization of a reaction product of a complex formed from an onium salt formed from compound A and a halogen-containing compound or a metal-containing compound There is a risk that gelation of the electrolyte becomes difficult due to the low degree. A more preferable range of the number of N, P and S-containing groups per molecule is 2 or more and 1,000,000 or less.
[0037]
The form of Compound A can be, for example, a monomer, an oligomer, a polymer, or the like.
[0038]
Examples of the compound A include those having a substituent (N, P, S-containing substituent) containing at least one atom selected from the group consisting of N, P and S in the main chain or side chain. be able to. The position of the N, P, S-containing substituent is not particularly limited as long as the intended polymer is obtained.
[0039]
The backbone of the main chain of Compound A is not particularly limited, and can be, for example, polyethylene, polyester, polycarbonate, polymethyl methacrylate, polyacrylonitrile, polyamide, polyethylene terephthalate, or the like.
[0040]
The N-, P- and S-containing substituents are selected from the group consisting of groups derived from primary amino groups, secondary amino groups, tertiary amino groups, phosphine groups (PH2-) and nitrogen-containing heterocyclic compounds, for example. At least one type of group can be used. Compound A may have the same type of N, P, and S-containing substituents present in one molecule, but may have two or more different N, P, and S-containing substituents in one molecule. good. Among these, a primary amino group, a secondary amino group, and a tertiary amino group are preferable.
[0041]
Among the compounds A, examples of the compound containing N include, for example, polyvinylimidazole, poly (4-vinylpyridine), poly (3-vinylpyridine), poly (2-vinylpyridine), polybenzimidazole, bipyridyl, terpyridyl, Polyvinylpyrrole, 1,3,5-tris (3-dimethylamino) propylhexahydro-1,3,5 triazine, tris-2aminoethylamine, polydiallylmethylamine, polyallyldimethylamine, polydimethylallylamine, polyallylamine, Examples thereof include polydimethylaminoethyl methyl methacrylate and polydimethylaminoethyl methacrylate. These compounds can be used alone or in combination of two or more. Among these, polyvinyl imidazole, poly (4-vinylpyridine), poly (3-vinylpyridine), poly (2-vinylpyridine), polybenzimidazole, and the like are preferable because the electrolyte can be gelled in a small amount.
[0042]
Among the compounds A, examples of the compound containing P include a monomer, oligomer or polymer having a phosphine group. Specific examples include polyvinylphenyl diphenylphosphine, 1,2-phenylenebisphosphine, 1,3-bis (diphenylphosphino) propane, 1,5-bis (diphenylphosphino) pentane, and the like. These compounds can be used alone or in combination of two or more.
[0043]
Among compounds A, examples of the compound containing S include those containing a thioether structure. Specific examples include bis (methylthio) methane, 1,1-bis (methylthio) -2-nitroethylene, (di) ethyl sulfide, polyvinylphenylphenylthioether, and ethyl (bisethylthio) acetate. These compounds can be used alone or in combination of two or more.
[0044]
As the halogen-containing compound that forms a polymer of compound A and an onium salt, an organic halide is preferable. Organic halides are preferred because they can easily form onium salts and can be crosslinked to increase the crosslinking density.
[0045]
The halogen-containing compound preferably has 2 or more halogen atoms per molecule. In such a compound, different halogen atoms may exist in one molecule and the total number of halogen atoms may be 2 or more, but two or more types of halogen atoms may exist in one molecule. When the number of halogen atoms per molecule is 1, the degree of polymerization of the polymer obtained from the compound A and the halogen-containing compound described above may be low, and it may be difficult to gel the electrolyte. The number of halogen atoms per molecule is more preferably 2 or more and 1,000,000 or less.
[0046]
Examples of the halogen-containing compound having 2 or more halogen atoms per molecule include dibromomethane, dibromoethane, dibromopropane, dibromobutane, dibromopentane, dibromohexane, dibromoheptane, dibromooctane, dibromononane, dibromodecane, Dibromoundecane, dibromododecane, dibromotridecane, dichloromethane, dichloroethane, dichloropropane, dichlorobutane, dichloropentane, dichlorohexane, dichloroheptane, dichlorooctane, dichlorononane, dichlorodecane, dichloroundecane, dichlorododecane, dichlorotridecane, diiodomethane, Diiodoethane, diiodopropane, diiodobutane, diiodopentane, diiodohexane, diiodoheptane, diiodoocta , Diiodononane, diiododecane, diiodoundecane, diiodododecane, diiodotridecane, 1,2,4,5-tetrakisbromomethylbenzene, epichlorohydrin oligomer, epibromohydrin oligomer, hexabromocyclododecane, tris ( 3,3-dibromo-2-bromopropyl) isocyanuric acid, 1,2,3-tribromopropane, diiodoperfluoroethane, diiodoperfluoropropane, diiodoperfluorohexane, polyepichlorohydrin, polyepichlorohydrin and polyethylene ether And polyfunctional halides such as polyepibromohydrin and polyvinyl chloride. As a halogen containing compound, it can be used individually or in combination of 2 or more types of organic halides. Of these, organic halides having two halogen atoms per molecule are preferred.
[0047]
The metal compound that forms a complex with compound A can form a crosslinked structure between the metal compounds by metal ions by setting the valence of the metal to 2 or more. The electrolyte can be gelled. Further, the gelling agent containing this metal compound is stable even when the solar cell is used for a long period of time and the temperature of the solar cell is increased to about 50 to 70 ° C. by irradiation with sunlight. It is possible to avoid the occurrence of a phase transition. As a result, it is possible to prevent liquid leakage when the temperature rises and maintain high energy conversion efficiency even when the temperature rises.
[0048]
Examples of the divalent or higher metal compound include Mg halide, Ca halide, Ba halide, transition metal halide and the like. The metal compound to be used can be used individually or in combination of 2 or more types. Specifically, ZnI2, MgI2, MgCl2, CaI2, CuI₂, ZnI2, RuI_Three, PtI_Four, MnI₂, OsCl_Three, IrBr_Three, RhI_Three, PdI₂, FeI₂And so on. Among these, it is preferable to use a metal iodide. Furthermore, a metal compound having a ligand such as an organic acid group other than a halogen atom such as an acetic acid group and an oxalic acid group; an inorganic acid group such as a carbonic acid group and a nitric acid group can also be used.
[0049]
The following method etc. are mentioned as a method of making the electrolyte mentioned above into a gel form.
[0050]
An electrolyte A is prepared by dissolving at least one of a halogen-containing compound or a metal compound having a valence of 2 or more in the electrolyte, and an electrolyte B is prepared by dissolving the compound A in the electrolyte. The obtained electrolyte A and electrolyte The raw material kit containing B is stored. The stored electrolyte A and electrolyte B are mixed when necessary, and the obtained mixed electrolyte is used as a gel electrolyte.
(Spherical insulating particles)
The spherical insulating particles added to the electrolyte described above need to be an insulator that does not participate in the electrochemical reaction in the electrolyte. For this reason, the spherical insulating particles are desirably inorganic ceramic particles or organic plastic particles. Examples of the ceramic particles include, but are not limited to, silica, alumina, zirconia and the like. Examples of the plastic particles include, but are not limited to, polystyrene, polymethyl methacrylate (PMMA), polyethylene, and polypropylene. In view of solvent resistance and electrical stability, inorganic ceramics are desirable.
[0051]
A flame hydrolysis method, a wet method, etc. are used as a manufacturing method of the spherical insulation particle whose average particle diameter is about 40 nm or more and about 800 nm or less and whose ratio of a major axis to a minor axis is about 1.2 or less. The specific gravity of the spherical insulating particles is preferably close to the specific gravity of the electrolyte, which facilitates dispersion of the spherical insulating particles in the electrolyte. Moreover, since it is preferable that the surface of the spherical insulating particles is hydrophilic, it is preferable that a hydroxyl group is present at the surface terminal of the spherical insulating particles.
[0052]
Next, an embodiment of a photosensitized solar cell using this electrolyte layer will be described.
[0053]
In this embodiment, a support substrate having a light receiving surface, a transparent conductive film formed on one surface of the support substrate, a semiconductor electrode formed on the transparent conductive film and having a dye adsorbed on the surface, A counter substrate facing the semiconductor electrode; a conductive layer (counter electrode) formed on a surface of the counter substrate facing the semiconductor electrode; and an electrolyte existing between the conductive layer and the semiconductor electrode. It is a structure of the type which injects from a support substrate.
[0054]
Hereinafter, the support substrate, the transparent conductive film, the semiconductor electrode, the counter substrate, and the conductive layer will be described.
(A) Support substrate
Since the support substrate has a light receiving surface, a substrate such as a glass substrate or a plastic substrate that absorbs less visible light is preferable.
(A) Transparent conductive film
The transparent conductive film is preferably provided on the supporting substrate, has little absorption in the visible light region, and has conductivity. The transparent conductive film is preferably a tin oxide film doped with fluorine or indium, or a zinc oxide film doped with fluorine or indium. Further, from the viewpoint of improving conductivity and preventing an increase in resistance, it is desirable to wire a low-resistance metal matrix in combination with a transparent conductive film.
(C) Semiconductor electrode
The semiconductor electrode is preferably made of a transparent semiconductor with little absorption in the visible light region. As such a semiconductor, a metal oxide semiconductor is preferable. Specifically, oxides of transition metals such as titanium, zirconium, hafnium, strontium, zinc, indium, yttrium, lanthanum, vanadium, niobium, tantalum, chromium, molybdenum or tungsten, SrTiO_Three, CaTiO_Three, BaTiO_Three, MgTiO_Three, SrNb₂O₆Perovskites such as these, or a composite oxide or a mixture of these oxides, GaN, and the like.
[0055]
Examples of the dye adsorbed on the surface of the semiconductor electrode include a ruthenium-tris transition metal complex, a ruthenium-bis transition metal complex, an osmium-tris transition metal complex, an osmium-bis transition metal complex, A ruthenium-cis-diaqua-bipyridyl complex, phthalocyanine, porphyrin and the like can be mentioned.
(D) Counter substrate
It is preferable that the counter substrate has little absorption in the visible light region and has conductivity. The counter substrate is preferably a tin oxide film, a fluorine-doped tin oxide film, a zinc oxide film, or the like. It is preferable that platinum or carbon adhere to such a counter substrate. Platinum can be attached to the counter substrate by electrochemical or sputtering.
(E) Conductive layer
The conductive layer can be formed of, for example, a metal such as platinum, gold, silver, carbon, porous carbon, or the like. In view of durability against the electrolyte, platinum is most preferable. By reducing the thickness of these conductive layers, a transparent conductive layer with little absorption in the visible light region can be obtained.
[0056]
The photosensitized solar cell of the present invention may be manufactured, for example, by the method described below.
[0057]
First, a support substrate having a light receiving surface is prepared, and a transparent conductive film and a semiconductor electrode are sequentially formed on one surface thereof. Then, the dye is adsorbed on the surface of the semiconductor electrode. On the other hand, a counter substrate having a conductive layer provided on the surface is prepared, and the battery unit is assembled by disposing the conductive layer and the above-described semiconductor electrode so as to face each other.
[0058]
Next, the electrolyte in which the spherical insulating particles are dispersed is injected into the gap between the semiconductor electrode and the conductive layer to form an electrolyte layer. When the gel electrolyte layer is used, the electrolyte precursor is gelled. Subsequently, the photosensitized solar cell of the present invention can be obtained by sealing the battery unit.
[0059]
When obtaining a gel electrolyte layer, it is preferable to heat the battery unit when the electrolyte precursor is gelled. It is preferable that the temperature of heat processing shall be in the range of 50-200 degreeC. This is due to the following reason. That is, when the heat treatment temperature is lower than 50 ° C., the degree of polymerization of the gel is lowered, and it may be difficult to form a gel. On the other hand, when heat treatment is performed at a high temperature exceeding 200 ° C., the decomposition of the dye is likely to occur. More preferably, the heat treatment temperature is 70 to 150 ° C.
[0060]
【Example】
Hereinafter, specific examples will be described in more detail with reference to the drawings.
Example 1
First, as an n-type semiconductor electrode material, 1 g of high-purity titanium oxide (anatase) powder (Degussa P25) having an average primary particle size of about 25 nm is mixed with 0.1 g of 15% titanium oxide colloidal dispersion to form a paste. did.
[0061]
As shown in FIG. 1A, an ITO electrode (transparent conductive film) 2 having a thickness of about 200 μm is formed on a PET substrate (support substrate) 1. A titanium oxide paste was applied onto the ITO electrode 2 by a doctor blade method to form an n-type semiconductor electrode 4 having an area of 1 cm × 1 cm composed of titanium oxide particles 3. The n-type semiconductor electrode 4 was baked at 100 degrees for 1 hour. The n-type semiconductor electrode 4 had a roughness factor of 500. The roughness factor was obtained from the nitrogen adsorption amount with respect to the projected area of the substrate.
[0062]
On the other hand, cis-bis (ciocyanato) -N, N-bis (2,2′-dipyridyl-4,4′-dicarboxylic acid) -ruthenium (II) dihydrate) was dissolved in dry ethanol to obtain 3 × A 10 @ -4 M dry ethanol solution was prepared. The n-type semiconductor electrode 4 described above was immersed in this solution (temperature of about 80 ° C.) for 4 hours and then pulled up in an argon stream. As a result, a ruthenium complex as a dye was supported on the surface of the n-type semiconductor electrode 4.
[0063]
Further, silica fine particles 12 (spherical insulating particles) manufactured by Nippon Aerosil Co., Ltd. and Aerosil OX50 were mixed with a small amount of ethanol to form a paste. This paste was applied to the surface of the electrode 4 carrying the dye by the doctor blade method. The silica fine particles were spherical with an average particle size of 40 nm and a ratio of major axis to minor axis of 1.0.
[0064]
On the other hand, a PET substrate on which an ITO electrode 5 (conductive layer) with platinum attached was formed as a counter substrate 6 and placed on the support substrate 1 on which the above-described n-type semiconductor electrode 4 was formed at a predetermined interval. Thereafter, ethanol was removed at about 50 ° C. Further, the periphery of the electrolyte was left and fixed with an epoxy resin 7 except for the electrolyte inlet.
[0065]
Through the above operation, a photoelectric conversion element unit as shown in FIG. 1A was obtained.
[0066]
Electrolyte dissolves 0.5 mol / L of lithium iodide, 0.3 mol / L of methylhexylimidazolium iodide, 0.5 mol / L of t-butylpyridine, and 0.05 mol / L of iodine in 100 ml of acetonitrile. It was prepared by letting.
[0067]
Next, as shown in FIG. 1B, an electrolyte 9 was injected from the injection port 8 into the opening of the photoelectric conversion unit. As shown in FIG. 1C, the electrolyte 9 penetrates the n-type semiconductor electrode 4 and is also injected between the n-type semiconductor electrode 4 and the ITO electrode 5. In addition, by injecting the electrolyte 9, an electrolyte layer in which 1.0 vol% spherical insulating particles 12 were uniformly dispersed in the electrolyte 9 was formed.
[0068]
Subsequently, as shown in FIG. 1D, the opening of the photoelectric conversion unit was sealed with the epoxy resin 10, and then the photoelectric conversion element, that is, the photosensitized solar cell was completed. A cross-sectional view of the obtained solar cell is shown in FIG.
[0069]
As shown in FIG. 2, a transparent conductive film 2 and a transparent n-type semiconductor electrode 4 are sequentially formed on the support substrate 1. Since the n-type semiconductor electrode 4 is formed from an aggregate of titanium oxide particles 3, the surface area is extremely large. Further, a single molecule is adsorbed on the surface of the n-type semiconductor electrode 4, and the surface can have a fractal shape having self-similarity like a resinous structure. One counter substrate 6 includes a glass substrate 6 and a conductive layer 5 formed on the surface of the glass substrate 6 on the n-type semiconductor electrode 4 side.
[0070]
The electrolyte 9 is held in the pores in the transparent n-type semiconductor electrode 4 and is interposed between the n-type semiconductor electrode 4 and the conductive film 6. In addition, spherical insulating particles 12 are uniformly dispersed in the electrolyte 9. When light 11 is incident from the glass substrate 1 side in such a photosensitized solar cell, first, the dye adsorbed on the surface of the n-type semiconductor electrode 4 is excited by absorbing the incident light 11. . The light that is not absorbed by the dye leaks into the electrolyte 9 but is scattered by hitting the spherical insulating particles 12 in the electrolyte 9, and part of the light returns to the n-type semiconductor electrode 4 and is absorbed by the dye. The excited dye passes electrons to the n-type semiconductor electrode 4 and also passes holes to the electrolyte 9 to perform photoelectric conversion. When the energy conversion efficiency of this solar cell was measured, it was 3.0%, and a sufficiently high energy conversion efficiency was obtained. This is because the use of spherical insulating particles 12 in the electrolyte 9 causes the light to be scattered and the light utilization efficiency to be increased.
[0071]
(Example 2)
The silica fine particles of Example 1 were replaced with spherical alumina fine particles having an average particle size of 300 nm and a ratio of major axis to minor axis of 1.1, and the photosensitized solar cell of this example was obtained by the same method. Manufactured. The energy conversion efficiency of this solar cell was measured and found to be 3.2%. Also in this example, since the spherical insulating particles were included, a sufficiently high energy conversion efficiency could be obtained.
[0072]
(Example 3)
A solar cell similar to that of Example 1 except that an electrolytic solution in which 10 wt% of water was added to a solution of 0.3M iodine, 0.58M t-butylpyridine 0.58M, and LiI 0.5M in 1-methyl-3-propylimidazolium iodide was used. It was created. The energy conversion efficiency of this solar cell was measured and found to be 2.0%. Also in this example, since the spherical insulating particles were included, a sufficiently high energy conversion efficiency could be obtained.
[0073]
Example 4
A solar cell similar to that of Example 1 was used except that an electrolytic solution in which 0.3 M of iodine, 0.24 g of polyvinylpyridine and 0.24 g of 1,6-dibromohexane were added to 5 ml of 1-methyl-3-propylimidazolium iodide. Created. This electrolyte was gelled by reaction after injection. The energy conversion efficiency of this solar cell was measured and found to be 2.0%. Moreover, after irradiating simulated sunlight (AM1.5) for 100 hours, when energy conversion efficiency was measured again, it was 2.0%. Also in this example, it can be seen that not only a sufficiently high energy conversion efficiency could be obtained but also the durability was high by using a gel electrolyte because of including spherical insulating particles.
[0074]
(Example 5)
An n-type semiconductor substrate was prepared by the same method as in Example 1. This was placed in a sealed container with the semiconductor electrode facing upward. Both of the two cocks were opened, and silica fine particles similar to those in Example 1 were blown off with air from one of the cocks, and deposited on the semiconductor electrode to a thickness of about 20 μm. After that, a counter electrode was formed by the same method to produce a solar cell. Also in this example, an electrolyte layer in which 1.0% by volume of spherical insulating particles 12 was uniformly dispersed in the electrolyte 9 was formed. The energy conversion efficiency of this solar cell was measured and found to be 2.0%. Also in this example, since the spherical insulating particles were included, a sufficiently high energy conversion efficiency could be obtained.
[0075]
(Example 6)
An n-type semiconductor substrate was prepared by the same method as in Example 1. Next, a counter substrate similar to that of Example 1 was bonded as a 50 μm gap. 1-Methyl-3-propylimidazolium iodide has an average particle size of 300 nm to an electrolyte prepared by adding 0.3 M iodine, 0.24 g polyvinyl pyridine, 0.24 g 1,6-dibromohexane in 5 ml of iodine, and has a major axis and a minor axis. An electrolyte mixed with 1% by volume of titania fine particles having a ratio of 1.1 was injected. After that, a counter electrode was formed by the same method to produce a solar cell. The energy conversion efficiency of this solar cell was measured and found to be 2.2%. Also in this example, since the spherical insulating particles were included, a sufficiently high energy conversion efficiency could be obtained.
[0076]
(Example 7)
A solar cell was produced in the same manner as in Example 6 except that 0.1% by volume of titania fine particles was used. The energy conversion efficiency of this solar cell was measured and found to be 2.1%. Also in this example, since the spherical insulating particles were included, a sufficiently high energy conversion efficiency could be obtained.
[0077]
(Example 8)
A solar cell was produced in the same manner as in Example 6 except that 1% by volume of titania fine particles having a particle diameter of 100 nm were used. The energy conversion efficiency of this solar cell was measured and found to be 2.2%. Also in this example, since the spherical insulating particles were included, a sufficiently high energy conversion efficiency could be obtained.
[0078]
Example 9
A solar cell was produced in the same manner as in Example 6 except that 1% by volume of titania fine particles having a particle size of 800 nm was used. The energy conversion efficiency of this solar cell was measured and found to be 2.2%. Also in this example, since the spherical insulating particles were included, a sufficiently high energy conversion efficiency could be obtained.
[0079]
The center of each of the solar cells of Examples 1 to 9 was pressed with a finger, but the cell gap did not change significantly because fine particles were present in the cell. In addition, the n-type semiconductor electrode and the counter electrode were in contact with each other, and there was no internal short circuit.
[0080]
(Comparative Example 1)
A solar cell similar to that of Example 6 was produced except that titania fine particles were not used. The energy conversion efficiency of this solar cell was measured and found to be 1.8%. In this comparative example, since it does not contain spherical insulating particles, it seems that the energy conversion efficiency was lowered. Further, when this solar cell was bent, an internal short circuit occurred.
[0081]
(Comparative Example 2)
A solar cell similar to that of Example 6 was prepared except that 1% by volume of silica fine particles having a particle size of 10 nm was used. The energy conversion efficiency of this solar cell was measured and found to be 1.8%. In this comparative example, it is considered that the energy conversion efficiency was lowered because the spherical insulating particles had a small particle size and low light scattering characteristics.
[0082]
(Comparative Example 3)
A solar cell similar to that of Example 6 was prepared except that 1% by volume of silica fine particles having a particle diameter of 1 μm was used. The energy conversion efficiency of this solar cell was measured and found to be 1.8%. In this comparative example, it is considered that the energy conversion efficiency was lowered because the spherical insulating particles had a large particle size and low light scattering characteristics.
[0083]
(Comparative Example 4)
A solar cell similar to that of Example 6 was prepared except that 5% by volume of silica fine particles having a particle diameter of 10 nm was used. As a result, the amount of the silica fine particles was too large to flow into the cell. .
[0084]
(Comparative Example 5)
A solar cell was produced in the same manner as in Example 6 except that 1% by volume of a silica fiber having a diameter of 30 nm and a length of 1 μm was used. The energy conversion efficiency of this solar cell was measured and found to be 1.8%. In this comparative example, since the insulating particles are not spherical, it is considered that the light scattering characteristics are low and the energy conversion efficiency is lowered.
[0085]
【The invention's effect】
As described above in detail, according to the present invention, a highly efficient photosensitized solar cell can be provided.
[Brief description of the drawings]
FIGS. 1A, 1B, 1C and 1D are cross-sectional views illustrating an example of a manufacturing process of a photosensitized solar cell according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing an example of a photosensitized solar cell according to an embodiment of the present invention.
[Explanation of symbols]
1 ... Support substrate
2 ... Transparent conductive film
3. Titanium oxide particles
4 ... n-type semiconductor electrode
5 ... Conductive layer
6 ... Counter substrate
7, 10 ... Epoxy resin
8 ... Inlet
9 ... Electrolyte
11 ... Incident light
12 ... Spherical insulating particles

Claims (5)

A semiconductor electrode having a dye supported on the surface;
A counter substrate that is disposed to be opposed to the semiconductor electrode and has a conductive layer on the surface;
Spherical insulating particles provided between the semiconductor electrode and the conductive layer, having an average particle diameter of 40 nm to 800 nm and a ratio of major axis to minor axis of 1.2 or less, iodine molecules and iodide A photosensitized solar cell comprising an electrolyte layer having an electrolyte. The photosensitized solar cell according to claim 1, wherein the spherical insulating particles are ceramic particles. The photosensitized solar cell according to claim 1, wherein the spherical insulating particles are contained in the electrolyte layer in an amount of 0.05% by volume or more and 2% by volume or less. The photosensitized solar cell according to claim 1, wherein the electrolyte is a gel electrolyte. The support substrate is disposed on a surface of the semiconductor electrode opposite to the surface on the electrolyte layer side, and at least one of the support substrate and the counter substrate is a plastic substrate. Photosensitized solar cell.

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