JP2002080205A - Sol solution for manufacturing fine particle aggregation of metal oxide, its manufacturing method, fine particle aggregation of metal oxide, and photoelectric conversion apparatus with fine particle aggregation of metal oxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly productive sol solution for manufacturing a fine particle aggregation of a metal oxide, its manufacturing method, a fine particle aggregation of the metal oxide manufactured from the sol solution and suitable to photoelectric material and photo conductive material, and a high performance photoelectric conversion apparatus with the fine particle aggregation of the metal oxide. SOLUTION: By dissolving a high molecular compound containing a carboxyl group into a solution containing at least a metal alkoxide, a gel compound containing a high molecular compound with the carboxyl group and the metal alkoxide is produced. With continuous reaction, a dispersed colloid sol solution of fine particle metal oxide is then produced. The dispersed colloid sol solution of fine particle metal oxide is mixed with at least one type solvent selected from alcohols, ethers and ketones each being water-soluble solvent and having a boiling point of 120 deg.C and/or water in soluble solvent having a boiling point of 120 deg.C or higher. With this mixing, a sol solution for manufacturing fine particle aggregation of metal oxide is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a metal oxide fine particle aggregate suitable for a photovoltaic material, a photoconductive material, and a photocatalytic material, and a metal oxide fine particle aggregate for producing the metal oxide fine particle aggregate. The present invention relates to a sol liquid for production, a method for producing a sol liquid for producing an aggregate of metal oxide fine particles, and a photoelectric conversion device using the aggregate of metal oxide fine particles.

[0002]

2. Description of the Related Art Global warming due to the burning of fossil fuels and an increase in energy demand due to an increase in population have become major issues relating to the survival of humankind. Needless to say, sunlight has nurtured the earth's environment since ancient times and has become an energy source for all living things, including humans. Recently, the use of sunlight as an infinite and clean energy source that does not generate harmful substances has been studied. Above all, a so-called solar cell that converts light energy into electric energy has attracted attention as a powerful technical means. As photovoltaic materials for solar cells, monocrystalline, polycrystalline, amorphous silicon, and compound semiconductors such as CuInSe, GaAs, and CdS are used. Solar cells using these inorganic semiconductors exhibit relatively high energy conversion efficiencies of 10% to 20%, and are therefore widely used as power supplies for remote locations and auxiliary power supplies for portable small electronic devices.

[0003] However, in light of the purpose of suppressing the consumption of fossil fuels and preventing the deterioration of the global environment as described at the beginning, at present, solar cells using inorganic semiconductors are not sufficiently effective. Hard to say. This is because solar cells using these inorganic semiconductors are plasma CVD.
This is because it is manufactured by a method or a high-temperature crystal growth process, and requires a large amount of energy to manufacture an element. In addition, it contains components that may have a harmful effect on the environment, such as Cd, As, and Se, and there is a concern about the possibility of environmental destruction due to disposal of the element.

As a method for solving such a problem, a photoelectrochemical energy conversion device utilizing a photoelectrochemical reaction generated at an interface between an optical semiconductor (a semiconductor in which carriers are generated by light irradiation) and an electrolyte solution is known. Expected.
Have found that when a titanium oxide electrode in an aqueous solution is irradiated with light, water is decomposed to obtain oxygen and hydrogen, and at the same time, a photocurrent flows between the counter electrode and a platinum electrode (A. Fujishima). , K. Honda, Nat
ure, 238, 37 (1972)). The photoelectrochemical energy conversion device described above converts solar energy into electric energy, and at the same time, decomposes water, which is an inexhaustible natural resource, and generates hydrogen that is expected to be used as a clean fuel. It is noteworthy.

The titanium oxide used as an electrode material is photoelectrochemically stable and has an excellent surface as an optical semiconductor electrode material for a photoelectrochemical energy conversion device. Its band gap is as large as 3.0 eV, and spectrum matching with sunlight is poor. Therefore, when titanium oxide is used as an electrode material or the like, there is a problem that an energy conversion device having excellent photoelectric conversion efficiency cannot be obtained. Under the current situation, it has been studied to sensitize the surface of titanium oxide by adsorbing an organic dye (H. Tsubomura, Sol. Energy,
21, 93 (1978)). On the other hand, since only the dye adsorbed on the surface of titanium oxide contributes to sensitization, titanium oxide having a large specific surface area should be used as a material for the optical semiconductor electrode for the purpose of increasing light use efficiency. Has been proposed (Japanese Patent Laid-Open No. 1-220380).

As a means for producing the above-mentioned metal oxide thin film having a large specific surface area, a hydrolytic colloid method of a metal alkoxide has been proposed (JP-A-3-114150). In the metal alkoxide hydrolysis colloid method, an excess amount of water is added to an alcohol solution of a metal alkoxide in the presence of a disintegrating agent such as nitric acid to stabilize the dispersion, and the mixture is heated to hydrolyze the metal alkoxide. Then, after obtaining a colloid solution in which metal oxide fine particles are dispersed, this colloid solution is applied and sintered to produce a metal oxide fine particle thin film. According to this method, a film in which ultrafine titanium oxide particles having an average particle size of about several tens nm are deposited can be obtained. Because the size of the voids is smaller than the size of the titanium oxide ultrafine particles, although the specific surface area is somewhat large,
When the thickness of the metal oxide fine particle thin film is increased, it is difficult for the dye to penetrate into the metal oxide fine particle thin film, and there is a problem that the amount of dye adsorbed per unit film thickness decreases.

Further, after hydrolyzing the metal alkoxide, the particle size is reduced to several tens nm by using an autoclave, and at the same time, the growth of crystallites is promoted to improve the photoelectric conversion efficiency (M. Gratzel, Nature, Vol.
353/24 OCTOBER 1991), but it is necessary to maintain a high temperature and a high pressure of about tens of atmospheres and about 200 ° C. for several hours or more, which is inferior in productivity. Further, a metal alkoxide is reacted in a solution containing a polymer compound having at least a carboxyl group, a composite gel containing the polymer compound and the metal alkoxide is generated by the reaction, and the reaction is further continued to produce a metal oxide fine particle colloidal dispersion sol. And a method of applying and sintering the dispersion sol to obtain metal oxide fine particle aggregates (hereinafter, referred to as a “composite gelling method”) has been proposed (JP-A-11-11912).
Publication), the film thickness that can be applied and sintered at once is as thin as about 0.2 μm, and a large number of application and sintering operations are required to obtain a practical film thickness. In addition, since the solvent is mainly a mixture of water-soluble alcohols and water, the drying speed is high, and the viscosity is low, so that the pattern printing is possible and the screen printing method, which is an application method with excellent productivity, is used. There was a disadvantage that it was not suitable.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and achieve the following objects. That is, an object of the present invention is to provide a sol liquid for producing a metal oxide fine particle aggregate excellent in productivity, and a method for producing the same. The present invention also provides a photovoltaic material produced from the sol liquid for producing a metal oxide fine particle aggregate,
An object is to provide a metal oxide fine particle aggregate suitable for a photoconductive material and a photocatalytic material. Still another object of the present invention is to provide a photoelectric conversion device having excellent photoelectric conversion efficiency using the metal oxide fine particle aggregate.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies on means for producing metal oxide fine particle aggregates, and as a result have obtained the following knowledge. First, it is effective to reduce the amount of water in the final stage of drying in order to obtain a thick film free of cracks or the like by coating using the composite gelling method. Second, the sol liquid produced by the composite gelation method is stable in that the solvent can be replaced with a specific high boiling point solvent. Based on these findings, by adding a water-soluble solvent having a boiling point sufficiently higher than that of water to the sol liquid, it is assumed that the liquid that evaporates in the final stage of drying is not water, or the solvent of the sol liquid is a specific solvent. We thought that it would be effective to reduce the amount of water in the sol in advance by substituting with a boiling point solvent. Third, by causing a specific polymer compound to coexist in a solution and in a film after coating, the occurrence of cracks during sintering can be reduced. Fourth,
By separately adding metal oxide particles to the sol, it is possible to reduce the occurrence of cracks during sintering, and it is more effective to add particles subjected to a specific treatment with nitric acid.

The means for solving the above problems are as follows. That is, <1> in a solution containing at least a metal alkoxide,
Dissolve the polymer compound having a carboxyl group, generate a composite gel containing the polymer compound having a carboxyl group and a metal alkoxide, and further generate a metal oxide fine particle colloidal dispersion sol solution by continuing the reaction, The metal oxide fine particle colloidal dispersion sol may be prepared from a water-soluble solvent having a boiling point of 120 ° C. and / or an alcohol, ether or ketone which is a water-insoluble solvent and has a boiling point of 120 ° C. or more. A method for producing a sol liquid for producing an aggregate of metal oxide fine particles, comprising mixing at least one selected material to obtain a sol liquid for producing an aggregate of metal oxide fine particles. <2> The polymer compound having a carboxyl group is
The method for producing a sol liquid for producing an aggregate of metal oxide fine particles according to <1>, which is polyacrylic acid. <3> The method for producing a sol liquid for producing an aggregate of metal oxide fine particles according to <1> or <2>, wherein at least one selected from alkyl celluloses and hydroxylated alkyl celluloses is dissolved. <4> The method according to any one of <1> to <3>, wherein the metal oxide particles are separately dispersed. <5> The method for producing a sol liquid for producing an aggregate of metal oxide fine particles according to <4>, wherein the metal oxide particles to be separately dispersed are dry particles obtained by removing nitric acid after mixing with nitric acid. It is. <6> The metal oxide fine particle aggregate according to <4> or <5>, wherein the metal oxide particles to be separately dispersed are at least one selected from titanium oxide, zinc oxide, and tin oxide. This is a method for producing a sol liquid for production. <7> The method according to any one of <1> to <6>, wherein the metal alkoxide is a titanium compound. <8> A sol liquid for producing metal oxide fine particle aggregates, which is produced by the method for producing a sol liquid for producing metal oxide fine particle aggregates according to any one of <1> to <7>. is there. <9> A metal oxide fine particle aggregate obtained by drying the sol liquid for producing a metal oxide fine particle aggregate according to <8>. <10> The metal oxide fine particle aggregate according to <9>, wherein the metal oxide fine particle aggregate is in the form of a thin film. <11> a semiconductor electrode having at least a semiconductor layer;
A photoelectric conversion device in which an electrolyte layer is sandwiched between a counter electrode and the semiconductor layer, wherein the semiconductor layer contains the metal oxide fine particle aggregate according to <10>. Device.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. [Method for producing sol liquid for producing metal oxide fine particle aggregates] The method for producing a sol liquid for producing metal oxide fine particle aggregates according to the present invention comprises preparing a polymer compound having a carboxyl group in a solution containing at least a metal alkoxide. By dissolving to form a composite gel containing the polymer compound having a carboxyl group and a metal alkoxide (hereinafter, referred to as a “composite gel forming step”), and further continuing the reaction, the metal oxide fine particle colloidal dispersion sol A sol solution containing the metal oxide fine particles and a water-soluble solvent having a boiling point of 12
0 ° C. and / or a mixture of at least one selected from alcohols, ethers and ketones which are water-insoluble solvents and have a boiling point of 120 ° C. or higher (hereinafter referred to as “a specific high boiling point solvent mixing step”). To prepare a sol liquid for producing metal oxide fine particle aggregates.

In the step of producing a composite gel according to the present invention,
A polymer compound having a carboxyl group is dissolved in a solution containing at least a metal alkoxide to produce a composite gel containing the polymer compound having a carboxyl group and a metal alkoxide, that is, a metal oxide fine particle precursor. The metal alkoxide is represented by a general formula, M (OR) _n . Here, M represents a metal element, and R represents an alkyl group. n represents the oxidation number of the metal element. As the metal alkoxide, for example, zinc dialkoxide such as zinc diethoxide, tungsten hexaalkoxide such as tungsten hexaethoxide, vanadyl dialkoxide such as vanadyl diethoxide, tin tetraalkoxide such as tin tetraisopropoxide, strontium diisotoxide Examples include strontium dialkoxide such as propoxide and titanium tetraalkoxide such as titanium tetraisopropoxide. These may be used alone or in combination of two or more. Among these, titanium tetraalkoxide is preferable in terms of durability and semiconductor characteristics.

In the present invention, in the case where composite oxide fine particles such as strontium titanate are obtained as the metal oxide fine particle aggregate obtained from the sol liquid for producing the metal oxide fine particle aggregate, the metal alkoxide is used as the metal alkoxide. A double alkoxide containing at least two kinds of metals which are components of the composite oxide fine particles in a molecule can be used. In this case, at least two kinds of metals that are components of the composite oxide fine particles can be appropriately selected according to the purpose. When obtaining titanium oxide fine particles as the metal oxide fine particle aggregates, as the metal alkoxide, titanium tetraisopropoxide, titanium tetranormal propoxide, titanium tetraethoxide, titanium tetranormal butoxide, titanium tetraisobutoxide, Titanium tetratertiary butoxide and the like can be suitably used. Among these, titanium tetraisopropoxide is particularly preferred.

The solution containing the metal alkoxide contains a solvent, and the solvent is preferably an organic solvent. In the present invention, the organic solvent may contain a very small amount of water. As the organic solvent, those having the property of dissolving the metal alkoxide and not reacting with the metal alkoxide, for example, alcohols such as methanol, ethanol, isopropanol and butanol, formamide, dimethylformamide, dioxane, and benzene are used. However, among these organic solvents, the boiling point is 100 in terms of reaction controllability.
Solvents at a temperature of not more than ° C are preferred, alcohols are preferred in terms of solubility, and methanol, ethanol and isopropanol are particularly preferred.

The polymer compound having a carboxyl group is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polyacrylic acid and polypeptide. These may be used alone or in combination of two or more. The polyacrylic acid is a water-soluble polymer compound and is insoluble in organic solvents such as the above-mentioned alcohols, but partially hydrolyzes the metal alkoxide in an organic solvent such as the alcohols. It has the property of easily dissolving in a solution to form a uniform solution. This is because the carboxyl group of polyacrylic acid and the metal alkoxide are combined by a salt-forming reaction to form a polymer complex compound.

In the mixing step of the specific high boiling point solvent in the present invention, the metal oxide fine particle colloidal dispersion sol liquid produced by further continuing the reaction with the composite gel obtained in the composite gel producing step is added to the composite gel obtained in the composite gel production step. The following specific high boiling point solvents are mixed. That is, a water-soluble solvent (in the present invention, "a solvent that can be mixed with water in an arbitrary ratio") has a boiling point of 120 ° C. or higher, and / or a non-water-soluble solvent. In some cases the boiling point is 12
At least one solvent selected from alcohols, ethers and ketones at 0 ° C. or higher is mixed with the metal oxide fine particle colloidal dispersion sol. These high-boiling solvents may be added in a small amount to the solution before the reaction in advance, but the metal oxide fine particle aggregates of the present invention may be used so as not to hinder the reaction for producing the composite gel. It is desirable to newly add in the final step of the production of the sol solution for production, or to introduce the solvent by replacing the solvent by distillation. More specifically, the boiling point of the selected solvent is desirably sufficiently different from the boiling point of water, and therefore, it is preferably at least 120 ° C or more, and more preferably 135 ° C or more. Particularly preferred. When the solvent is replaced using a rotary evaporator or the like, a boiling point of 160 ° C. or higher is preferable in terms of operation because evaporation of the replacement solvent is small.

The production process of the sol liquid for producing the metal oxide fine particle aggregate of the present invention is specifically as follows. That is, first, the metal alkoxide is mixed with the solvent (for example,
Ethanol). Here, water necessary for partially hydrolyzing the metal alkoxide and an acid such as hydrochloric acid, nitric acid, sulfuric acid, and acetic acid as a catalyst are added. The amounts of water, acid, and the like added here vary depending on the degree of ease of hydrolysis of the metal alkoxide to be used, and thus cannot be specified unconditionally, but are appropriately selected within a range that does not impair the effects of the present invention. be able to. Thus, a mixed solution of the metal alkoxide, the solvent (eg, ethanol), the water, and the catalyst (eg, acid) is obtained.

Next, the mixed solution is refluxed under a dry nitrogen stream while stirring at room temperature to 80 ° C. The reflux temperature and time also vary depending on the degree of ease of hydrolysis of the metal alkoxide to be used, and thus cannot be specified unconditionally, but can be appropriately selected within a range that does not impair the effects of the present invention. As a result of the reflux, the metal alkoxide is in a partially hydrolyzed state. That is, since the amount of the water contained in the mixed solution is so small that the alkoxyl group of the metal alkoxide cannot be sufficiently hydrolyzed, the metal alkoxide represented by the general formula, M (OR) _n In, only a part of all the -OR groups is hydrolyzed, resulting in a partially hydrolyzed state. In the partially hydrolyzed metal alkoxide, the polycondensation reaction has not progressed. Therefore, -MO between the metal alkoxides
Even though the -M- chain is formed, the metal alkoxide is in an oligomer state. The refluxed mixed solution containing the metal alkoxide in the oligomer state is colorless and transparent, and hardly increases in viscosity.

Next, the polymer compound having a carboxyl group (preferably polyacrylic acid) is added to the mixed solution after the reflux. Then, the polymer compound having a carboxyl group, which is originally difficult to dissolve in an organic solvent such as alcohols, is easily dissolved in this mixed solution, and the polymer compound having a carboxyl group and the metal alkoxide are at least dissolved. Is obtained. this is,
This is because the carboxyl group of the polymer compound having a carboxyl group and the metal alkoxide are combined by a salt forming reaction to form a polymer complex compound. This transparent sol is usually a colorless and transparent homogeneous solution. The amount of the polymer compound having a carboxyl group to be added to the metal alkoxide is generally 0.1% by weight.
1-1 is preferable, and 0.2-0.8 is more preferable. If the weight ratio is less than 0.1, a large three-dimensional network of -MOM- grows, so that the composite gel does not redissolve. The properties are inferior.

Further, an excess amount of water is added to the transparent sol,
When the reaction is further continued while being kept at room temperature to about 90 ° C., the transparent sol gels in a few minutes to about 1 hour, and a composite having a crosslinked structure containing at least the polymer compound having a carboxyl group and the metal alkoxide. A gel is formed. Then, the composite gel is heated at room temperature to about 90 ° C (usually,
(About 80 ° C.) for 5 to 50 hours, and the reaction is further continued. Then, the composite gel is dissolved again, and a translucent metal oxide fine particle colloid dispersion sol liquid is obtained. This is because the hydrolysis reaction and the polycondensation reaction of the metal alkoxide proceed, and the salt structure of the polymer compound having a carboxyl group and the metal alkoxide is decomposed to form a metal oxide fine particle precursor and a carboxylic acid ester. This is due to the change to

The water-soluble solvent (solvent that can be mixed with water in an arbitrary ratio) has a boiling point of 120 in the thus obtained colloidal dispersion sol of metal oxide fine particles.
Or at least one solvent selected from alcohols, ethers and ketones having a boiling point of 120 ° C. or higher when the solvent is a water-insoluble solvent, or newly added After that, water and components having a lower boiling point than water are removed by a distillation operation to obtain a sol liquid for producing metal oxide fine particle aggregates.

If water and components having a lower boiling point than water are not removed by distillation, even water-insoluble solvents can be used to some extent because they are mixed with water to some extent. It is more preferable to use a highly water-soluble solvent. Specific examples of the water-soluble solvent include, besides alcohols, ethers and ketones, dimethylformamide (153 ° C), formamide (211 ° C),
Dimethyl sulfoxide (189 ° C.), N-methylpyrrolidone (202 ° C.), etc., and alcohols, ethers and ketones include ethylene glycol (198)
° C), propylene glycol (187 ° C), trimethylene glycol (214 ° C), tetramethylene glycol (229 ° C), pentamethylene glycol (242 ° C).
° C), diethylene glycol dimethyl ether (160
° C), diethylene glycol diethyl ether (188
° C), diethylene glycol monoethyl ether acetate (207 ° C), 2-methoxyethanol (125 ° C).
° C), 2-ethoxyethanol (136 ° C), ethylene glycol isopropyl ether (143 ° C), 2-butoxyethanol (170 ° C), 2- (isopentyloxy) ethanol (181 ° C), 2- (2-methoxyethoxy) ) Ethanol (194 ° C), 2- (2-ethoxyethoxy) ethanol (203 ° C), 2- (2-butoxyethoxy) ethanol (230 ° C), diethylene glycol (245 ° C), polyoxyethylene (10) octylphenyl ether (200 ° C. or higher), 2,5-hexanedione (191 ° C.), triethylene glycol dimethyl ether (216 ° C.), low molecular weight polyethylene glycol, and the like. Of course, even a water-insoluble solvent is mixed with water to some extent, and is not limited to the above-mentioned water-soluble solvents.

These solvents have a high affinity for low-boiling alcohols such as water and ethanol. Therefore, in many cases there is no upper limit to the amount of the solvent. The liquid has a relatively high drying speed, and is suitable for producing a thin film by a coating method such as a dip coating method, a spray coating method, and a blade coating method as well as the spin coating method. Suitable to get. Therefore, when the metal oxide fine particle aggregate is manufactured by using these coating methods, an excessive addition of a high boiling point component may have an adverse effect such as sagging of the coating film. The content is preferably 20% by weight or less, particularly preferably 10% by weight or less, in the sol liquid for producing the aggregate. In order to prevent cracks during drying, it is preferable to add 0.5% by weight or more.

On the other hand, when water and components having a lower boiling point than water are removed by distillation, in addition to the above-mentioned water-soluble solvents, an alcohol which is a water-insoluble solvent having a low affinity for water is added. , Ethers and ketones can be used. Specific examples of the water-insoluble solvent include 1-pentanol (138 ° C), 2-methyl-1-
Butanol (128 ° C), 3-methyl-1-butanol (131 ° C), 1-hexanol (157 ° C), 2-methyl-1-pentanol (148 ° C), 4-methyl-2
-Pentanol (132 ° C), 2-ethyl-1-butanol (147 ° C), 1-heptanol (176 ° C), 2
-Heptanol (160 ° C), 3-heptanol (15
6 ° C.), 1-octanol (195 ° C.), 2-octanol (178 ° C.), 2-ethyl 1-hexanol (18 ° C.)
5 ° C.), 1-nonanol (214 ° C.), 1-decanol (231 ° C.), cyclohexanol (161 ° C.), benzyl alcohol (205 ° C.), α-terpineol (2
19 ° C.), 1,2-dibutoxyethane (203 ° C.), diethylene glycol dibutyl ether (255 ° C.), diethylene glycol monobutyl ether acetate (2
45 ° C.), 2- (hexyloxy) ethanol (208
° C), 2-hexanone (127 ° C), 2-heptanone (150 ° C), 4-heptanone (144 ° C), diisobutyl ketone (168 ° C), isophorone (138 ° C), cyclohexanone (156 ° C), methylcyclohexanone (169 ° C). ° C) and 2,5-pentanedione (141 ° C). Above all, when 1-heptanol and dimethylsulfoxide are simultaneously contained, a rapid increase in liquid viscosity is often observed, and a screen printing method,
A sol liquid suitable for a coating method using a squeegee is obtained.

A solvent or a mixed solvent selected from these high-boiling solvents according to the purpose is added to the sol of the metal oxide fine particle colloid dispersion, and water and a solvent component having a lower boiling point than water are removed by a distillation operation. . As the distillation operation, a conventional method under atmospheric pressure or a reduced pressure may be used, but it is efficient to use a rotary evaporator. The sol solution after solvent replacement can be directly used as a sol solution for producing metal oxide fine particle aggregates in a dip coating method, a wire bar coating method, a roller coating method, a curtain coating method, etc. When using a coating method such as a coating method, a solvent having a boiling point lower than that of water may be added to adjust the drying rate to be suitable for the coating method. Such solvents include methanol (65 ° C),
Ethanol (78 ° C), isopropyl alcohol (82
° C), tert-butanol (83 ° C), dioxane and the like.

Simultaneously dissolving at least one selected from the group consisting of alkyl celluloses and hydroxylated alkyl celluloses in the sol liquid for producing metal oxide fine particle aggregates makes it possible to adjust the viscosity of the sol liquid to one suitable for a coating method. In addition to this, there is an effect of reducing the occurrence of cracks during the sintering of the aggregates, and a film having a thickness of 1 to 2 μm can be obtained. Specific examples of such a compound include ethyl cellulose, propyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, tridecane, hexadecane, paraffin and the like. These compounds can be used as a mixture of two or more kinds. When tridecane or hexadecane is used, the liquid composition is designed so that these liquids have the highest boiling point in the sol liquid. There must be. If the amount of these compounds is too large or too small, cracks are likely to occur during sintering. Therefore, the amount of the compound is 1% by weight or more of the metal oxide component in the sol liquid, 50% or more. It is desirable that the content be not more than% by weight. Here, the amount of the metal oxide component in the sol liquid can be estimated from a weight ratio before and after sintering by weighing a part of the sol liquid.

Further, by dispersing other metal oxide particles in the sol liquid for producing metal oxide fine particle aggregates to obtain a sol liquid, not only can a sintered film of about 2 to 10 μm be obtained. Since a proper viscosity and thixotropy (thixotropy) can be imparted to the sol liquid, a sol liquid suitable for screen printing can be obtained when the solvent is composed of a mixture of high-boiling solvents. Of course, even in this case, when 1-heptanol and dimethylsulfoxide are simultaneously contained, a sharp increase in the liquid viscosity is observed, and it can be used together with the dispersion of metal oxide particles. Various metal oxides can be used, but titanium oxide,
The particles of zinc oxide and tin oxide are excellent in dispersibility in a sol solution and also excellent in crack resistance during sintering. These particles may be used alone or as a mixture. Those having different particle diameters, for example, titanium oxide of several tens nm and 0.2 to 0.1.
About 3 μm of zinc oxide may be mixed and used. The dispersion of the metal oxide particles can use a generally known method, for example, ball milling, an attritor, a sand mill, a paint shaker, and the like,
If necessary, media such as glass, steel, and ceramics may coexist. If the amount added to the sol liquid is too large, the aggregated film after firing will not sinter, so the upper limit of the metal oxide particles to be added is 10 parts by weight of the metal oxide component amount in the sol liquid. It is preferably 90 parts by weight or less. In addition, from the viewpoint of the dispersibility of the metal oxide particles to be added, the weight is preferably equal to or less than the weight of the entire sol liquid.

However, by pre-treating the metal oxide particles to be added by the method described below, the sinterability at a low temperature is remarkably improved. The upper limit is 100 parts by weight with respect to 10 parts by weight of the metal oxide component in the sol solution, and the thickness of the obtained aggregate film exceeds 15 μm. The pretreatment is performed by preparing a nitric acid slurry of a metal oxide and removing nitric acid from the nitric acid slurry by some method. It is also possible to obtain a strong thick film by sintering the nitric acid slurry itself, but if nitric acid is newly mixed into the sol liquid for producing metal oxide fine particle aggregates, gelation of the sol proceeds excessively. Therefore, it is not preferable to mix the nitric acid slurry itself. As a method of removing nitric acid from the nitric acid slurry, it is easy to evaporate by heating, and even if the obtained particles are dispersed in an organic solvent and applied and baked, the film forming property is obtained when the film is formed from the nitric acid slurry. Not inferior to Such a treatment is particularly effective for titanium oxide particles. For example, in the case where a dye is adsorbed on a metal oxide aggregate thin film to perform photosensitization, an effect of increasing the amount of dye adsorbed can also be obtained.

[Aggregate of Metal Oxide Fine Particles] The agglomerate of metal oxide fine particles of the present invention is obtained by drying the sol liquid for producing the aggregate of metal oxide fine particles of the present invention.
In particular, when it is used as a material for a photoelectric conversion device described later, it is preferable that the sol liquid is applied in a thin film form and then dried to form a thin metal oxide fine particle aggregate. When obtaining a sintered film composed of the metal oxide fine particle aggregate of the present invention, the sintering temperature can be appropriately selected depending on the composition of the sol liquid to be used.
Is preferable in terms of improving the strength of the film and the crystallinity of the metal oxide fine particles, and more preferably 350 to 550 ° C.
Also, the sintering time can be appropriately selected in the same manner,
A time of 5 to 300 minutes is preferable from the viewpoint of improving the strength of the film and the crystallinity of the metal oxide fine particles, and a time of 10 to 60 minutes is more preferable.

[Photoelectric Conversion Device] The photoelectric conversion device of the present invention comprises an electrolyte layer sandwiched between at least a semiconductor electrode having a semiconductor layer and a counter electrode. It is characterized by containing a metal oxide fine particle aggregate. The photoelectric conversion device of the present invention preferably has connection means for connecting the semiconductor electrode and the counter electrode so as to be able to conduct electricity, and may further include a device appropriately selected according to the purpose.

(Semiconductor electrode) The semiconductor electrode has at least a semiconductor layer. Preferably, a semitransparent conductive layer and a semiconductor layer are formed in this order on a substrate. The semiconductor layer contains the metal oxide fine particle aggregate of the present invention, and further contains other components as necessary. Preferably, the semiconductor layer is sensitized by adsorbing an organic dye on the surface. Examples of the material constituting the translucent conductive layer include ITO, tin oxide, and fluorine-doped tin oxide.

(Counter Electrode) The counter electrode is not particularly limited as long as it is electrochemically stable, and can be appropriately selected from known ones depending on the purpose. Examples thereof include platinum, gold, and the like.
It can be selected from a plate-like electrode such as graphite or a transparent electrode such as ITO glass and Nesa glass.

(Electrolyte solution layer) The electrolyte solution used in the electrolyte solution layer is not particularly limited and may be appropriately selected. Examples thereof include potassium chloride, lithium chloride, potassium carbonate, and tetraethylammonium perchlorate. Salts, alkalis such as sodium hydroxide and potassium carbonate,
An aqueous solution such as an acid such as sulfuric acid or hydrochloric acid, or a mixture thereof, or a non-aqueous solvent solution such as an alcohol or propylene carbonate may be used. These may be used alone or in combination of two or more. In the present invention, for the purpose of stabilizing the photocurrent characteristics, a compound that causes a reversible oxidation-reduction reaction, such as potassium iodide or p-benzoquinone, may be added to the electrolyte solution. In addition, the electrolyte solution can be semi-solidified by using a polymer gel or the like to prevent liquid leakage.

(Connecting Means) The connecting means is not particularly limited as long as it has a function of electrically connecting the pair of electrodes, and can be appropriately selected depending on the purpose. For example, a lead wire known per se is used. And wires, plates, printed films, vapor-deposited films, etc., made of conductive materials such as various metals, carbon, and metal oxides. In a photoelectric conversion method in a photoelectric conversion device, a pair of electrodes connected to each other so as to be able to conduct electricity is immersed in an electrolyte solution, and at least one of the pair of electrodes is irradiated with light to cause a photoelectric conversion reaction. The electrode irradiated with light in the pair of electrodes is a semiconductor electrode having a semiconductor layer formed using the sol liquid for producing metal oxide fine particle aggregates of the present invention, and the other is the counter electrode.

FIG. 1 shows a schematic diagram of an example of the photoelectric conversion device of the present invention, but the present invention is not limited to this embodiment. In the photoelectric conversion device shown in FIG. 1, an electrolyte layer 5 is sandwiched between a semiconductor electrode 4 and a counter electrode 8, and a pair of these electrodes is connected so that a conductive material can conduct electricity. The semiconductor electrode 4 is formed on the glass substrate 1 by ITO.
And a semiconductor layer 3 containing the metal oxide fine particle aggregate of the present invention are formed in this order. The counter electrode 8 has a metal film 6 made of platinum or the like formed on a glass substrate 7. The semiconductor layer 3 in the semiconductor electrode 4 and the metal film 6 in the counter electrode 8
Are arranged so as to face each other, and light is emitted from the semiconductor electrode 4 side. Since the semiconductor layer in the photoelectric conversion device of the present invention is formed using the sol liquid for producing a metal oxide fine particle aggregate of the present invention, it is easy to increase the film thickness, and the manufactured photoelectric conversion device Can have high photoelectric conversion efficiency.

[0036]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. (Reaction Example 1)-Preparation of Metal Oxide Fine Particle Colloid Dispersion Sol Solution-A 1000 ml round bottom flask prepared by diluting 64 g of titanium tetraisopropoxide (manufactured by Wako Pure Chemical Industries, purity: 95%) as a metal alkoxide in 100 ml of ethanol. Into which nitric acid 5.2 for electronic industry with a specific gravity of 1.38 was added.
g and 2.6 g of distilled water diluted in 100 ml of ethanol were poured with stirring. 80 of this mixed solution
C. and refluxed for 2 hours under a stream of dry nitrogen to obtain a colorless and transparent liquid. This colorless and transparent liquid is mixed with polyacrylic acid (Aldri)
(15 g) was added while stirring, and the polyacrylic acid was completely dissolved to obtain a transparent liquid. When 200 g of distilled water was poured into the transparent liquid at a stretch and the temperature of the liquid was raised to 80 ° C. again, the entire solution was solidified in about 5 minutes, and an almost transparent and uniform polymer composite gel was obtained. 8
When the reaction was continued at 0 ° C. for further 15 hours, the composite gel was dissolved again to give a slightly whitish translucent solution, and 410.1 g of a titanium oxide fine particle colloid dispersion sol solution was obtained. When 0.9923 g of the dispersion sol was taken out and baked at 450 ° C. for 20 minutes, 0.041 g of a titanium oxide aggregate was obtained, and the amount of the titanium oxide component in the dispersion sol was 4.1.
% By weight.

(Reaction Example 2) -Preparation of Metal Oxide Particles Treated with Nitric Acid- In a 1000 ml round-bottom separable flask, 100 g of titanium oxide fine particles (P25, manufactured by Nippon Aerosil Co., Ltd.) were charged, and the specific gravity was 1.38. While gradually adding 253 g of nitric acid for electronic industry, mix with a metal spoon coated with PTFE,
A nitric acid slurry was prepared. After leaving the flask closed at room temperature for 1 hour, the flask was fitted with a condenser for collecting nitric acid and heated in an oil bath kept at 120 ° C. for 12 hours. After confirming that no nitric acid remained in the vapor in the flask with a pH test paper wetted with water, the nitric acid-treated titanium oxide fine particles were cooled and taken out.

(Reaction Example 3) Preparation of Colloidal Dispersion Solution of Metal Oxide Fine Particles 11.36 g of tungsten hexaethoxide as a metal alkoxide was diluted with 20 ml of ethanol, and 0.514 g of nitric acid having a specific gravity of 1.38 was added thereto with stirring. 0.2 ml of water
Was added to prepare a mixed solution. The above operation was performed under a dry nitrogen stream. The temperature of the mixed solution was raised to 80 ° C., and the mixture was refluxed for 2 hours under a stream of dry nitrogen to obtain a colorless and transparent mixed solution. After cooling the mixed solution to room temperature, the mixed solution 2
When 0.1 g of polyacrylic acid was added as a polymer compound having a carboxyl group while stirring with respect to g, the polyacrylic acid was completely dissolved, and a colorless transparent sol was obtained. 2 ml of water was further added to the transparent sol to obtain a colorless and uniform transparent sol. The transparent sol was sealed in a glass container and heated to 80 ° C. The transparent sol turned into a composite gel in about 20 minutes, and a nearly transparent and uniform composite gel was obtained. 8
When the composite gel was kept at 0 ° C. for further 20 hours, the composite gel was dissolved again to obtain a slightly whitish translucent colloidal dispersion of tungsten oxide fine particle colloid.

(Example 1) 1 g of polyoxyethylene (10) octyl phenyl ether (boiling point: 200 ° C. or higher) as a water-soluble solvent was added to 10 g of the colloidal dispersion sol of titanium oxide fine particles obtained in Reaction Example 1. The resulting sol solution for producing an aggregate of titanium oxide fine particles was dip-coated on a slide glass. Several coating films were obtained by changing the lifting speed, and one side was wiped off and dried on a hot plate set at 60 ° C., whereby a transparent and uniform film was obtained. When the crystal structure was examined by X-ray diffraction for the material fixed to the slide glass by sintering at 450 ° C. for 20 minutes in an electric furnace, it was found that anatase type titanium oxide was formed. According to observation with a scanning electron microscope, it was observed that particles having a diameter of about 20 nm were aggregated. Finally, the aggregate was scraped off linearly using the blade of a small screwdriver, and the film thickness was measured with a surface roughness meter. As a result, a film having a maximum thickness of 0.6 μm was obtained.

(Comparative Example 1) The colloidal dispersion sol of titanium oxide fine particles obtained in Reaction Example 1 was used as it was to try dip coating on a slide glass. Only a state where the white powder was weakly adhered to the glass was obtained. Further, in order to obtain a film thickness of 0.6 μm by the spin coating method, coating and sintering (at 450 ° C. for 20 minutes) had to be repeated four times. When the crystal structure of the film thus obtained was examined by X-ray diffraction, it was found that anatase-type titanium oxide was formed. According to the scanning electron microscope observation, it was observed that particles having a diameter of about 5 to 10 nm were aggregated.

(Example 2) In Example 1, 1 g of polyoxyethylene (10) octyl phenyl ether was used.
N-methylpyrrolidone (boiling point 202)
(° C.) Except having changed to 250 mg, the same operation as in Example 1 was performed to obtain a film-like aggregate of titanium oxide fine particles. The results are shown in Table 1 below.

(Example 3) In Example 1, 1 g of polyoxyethylene (10) octyl phenyl ether was used.
Dimethyl sulfoxide which is a water-soluble solvent (boiling point 18
(9 ° C.) Except having changed to 500 mg, the same operation as in Example 1 was performed to obtain a film-like aggregate of titanium oxide fine particles. The results are shown in Table 1 below.

(Example 4) In Example 1, 1 g of polyoxyethylene (10) octyl phenyl ether was
2-butoxyethanol as a water-soluble solvent (boiling point 170
(C) The same operation as in Example 1 was carried out except that the amount was changed to 500 mg, to obtain a film-like aggregate of titanium oxide fine particles. The results are shown in Table 1 below.

(Example 5) In Example 1, 1 g of polyoxyethylene (10) octyl phenyl ether was replaced with
2-ethoxyethanol (boiling point 135) which is a water-soluble solvent
(C) The same operation as in Example 1 was carried out except that the amount was changed to 500 mg, to obtain a film-like aggregate of titanium oxide fine particles. The results are shown in Table 1 below.

(Example 6) In Example 1, 1 g of polyoxyethylene (10) octyl phenyl ether was
2-methoxyethanol (boiling point 125
(C) The same operation as in Example 1 was carried out except that the amount was changed to 500 mg, to obtain a film-like aggregate of titanium oxide fine particles. The results are shown in Table 1 below.

Comparative Example 2 In Example 1, 1 g of polyoxyethylene (10) octyl phenyl ether was added
The same operation as in Example 1 was carried out except that the amount was changed to 500 mg of 1-butanol (boiling point: 118 ° C.), and an attempt was made to obtain a film-like aggregate of titanium oxide fine particles. Only a state in which the white powder was weakly adhered to the glass was obtained. In order to obtain a film thickness of 0.6 μm by spin coating, coating and sintering must be carried out for
Had to be repeated several times. When the crystal structure of the film thus obtained was examined by X-ray diffraction, it was found that anatase-type titanium oxide was formed. According to the scanning electron microscope observation, it was observed that particles having a diameter of about 5 to 10 nm were aggregated.

Comparative Example 3 In Comparative Example 2, 500 mg of 1-butanol was added to 3-pentanol (boiling point: 116
C.) The same operation as in Comparative Example 2 was carried out except that the amount was changed to 1 g, to obtain a film-like aggregate of titanium oxide fine particles. The results are shown in Table 1 below.

Comparative Example 4 Comparative Example 2 was repeated, except that 500 mg of 1-butanol was replaced with 250 mg of 2-methyl-1-propanol (boiling point: 108 ° C.).
The same operation as described above was performed to obtain a film-like aggregate of titanium oxide fine particles. The results are shown in Table 1 below.

Comparative Example 5 The same operation as in Comparative Example 2 was carried out except that 1-butanol was changed to 2-propanol (boiling point: 82 ° C.), to obtain a film-like aggregate of titanium oxide fine particles. Obtained. The results are shown in Table 1 below.

(Example 7) Hydroxypropyl cellulose (manufactured by Wako Pure Chemical Industries, 1000-400 g) was added to 1.99 g of the titanium oxide fine particle colloidal dispersion sol obtained in Reaction Example 1.
0cP) was dissolved, and 100 mg of dimethyl sulfoxide (boiling point: 189 ° C.), which is a water-soluble solvent, was mixed to prepare a sol liquid for producing an aggregate of titanium oxide fine particles. No. Apply onto a glass slide using a wire bar while changing the count to 10, 20, 30, 40,
When dried on a hot plate set at 60 ° C., a transparent and homogeneous film was obtained. The dried film was sintered in an electric furnace at 450 ° C. for 20 minutes. 1
In the cases of Nos. 0, 20, and 30, a transparent sintered film was fixed on the slide glass. What was applied at 40 was a state in which white powder adhered to the slide glass. When the crystal structure of the transparent and fixed glass slide was examined by X-ray diffraction, it was found that anatase type titanium oxide was formed. According to observation with a scanning electron microscope, it was observed that particles having a diameter of about 10 nm were aggregated. Finally, the aggregate was scraped off linearly using the blade of a small screwdriver, and the film thickness was measured with a surface roughness meter. 0.5 μm, N
o. No. 20 was applied at 1.1 μm. The one coated at 30 was 1.4 μm.

Comparative Example 6 The procedure of Example 7 was repeated, except that dimethylsulfoxide was not added, to obtain a film-like aggregate of titanium oxide fine particles. At that time, the white powder was attached to the glass, and a good sintered film could not be obtained.

Example 8 2 g of the colloidal dispersion sol of titanium oxide fine particles obtained in Reaction Example 1, 400 mg of titanium oxide fine particles P25 (manufactured by Nippon Aerosil Co., Ltd.), and dimethyl sulfoxide (boiling point 189) as a water-soluble solvent
C.) in an 8 ml glass bottle together with an appropriate amount of glass beads (1 to 1.2 mmφ) and dispersed with a paint shaker for 1 hour to prepare a sol liquid for producing titanium oxide fine particle aggregates. This sol solution was used for No. 30
Was applied onto a slide glass with a wire bar and sintered in an electric furnace at 450 ° C. for 20 minutes, whereby a white film was fixed on the slide glass. The aggregate was scraped off linearly using a blade of a small screwdriver, and the film thickness was measured with a surface roughness meter. The film thickness was 7.5 μm.

Comparative Example 7 The procedure of Example 8 was repeated, except that dimethylsulfoxide was not added, to obtain a film-like aggregate of titanium oxide fine particles. The sintered film was separated from the slide glass by a small rubbing with a finger.

Example 9 2 g of the colloidal dispersion sol of the titanium oxide fine particles obtained in Reaction Example 1, 400 mg of the titanium oxide fine particles treated with nitric acid obtained in Reaction Example 2, and dimethyl sulfoxide (boiling point) as a water-soluble solvent 189 ° C)
100 mg was put into a glass bottle having an internal volume of 8 ml together with an appropriate amount of glass beads (1 to 1.2 mmφ), and dispersed for 1 hour with a paint shaker to prepare a sol liquid for producing an aggregate of titanium oxide fine particles. This sol solution was coated on both ends of a slide glass with a scotch tape (manufactured by 3M) as a spacer, and an NMR sample tube made of glass was applied as a squeegee and sintered at 450 ° C. for 20 minutes in an electric furnace to obtain a white film. Adhered to the slide glass. The aggregate was scraped off linearly using a blade of a small screwdriver, and the film thickness was measured with a surface roughness meter. The film thickness was 15 μm.

(Example 10) 2 g of the titanium oxide fine particle colloidal dispersion sol obtained in Reaction Example 1, 200 mg of nitric acid-treated titanium oxide fine particles obtained in Reaction Example 2, 200 mg of zinc oxide fine particles (manufactured by Rare Metallics), and N-methylpyrrolidone (boiling point: 202 ° C.) which is a water-soluble solvent 10
0 mg was placed in a glass bottle having an internal volume of 8 ml together with an appropriate amount of glass beads (1 to 1.2 mmφ), and dispersed with a paint shaker for 1 hour to prepare a sol liquid for producing an aggregate of titanium oxide fine particles. This sol solution was applied to both ends of a slide glass with scotch tape (manufactured by 3M) as a spacer, and an NMR sample tube made of glass was applied as a squeegee.
After sintering at 450 ° C. for 20 minutes in an electric furnace, a white film was fixed on the slide glass. The aggregate was scraped off linearly using a blade of a small screwdriver, and the film thickness was measured with a surface roughness meter. The film thickness was 18 μm.

Comparative Example 8 A sol solution containing metal oxide particles was prepared in the same manner as in Example 10 except that N-methylpyrrolidone was not added. After sintering, the obtained sintered film was shattered from the slide glass and peeled off only by lightly rubbing with a finger.

(Example 11) 10 g of the tungsten oxide fine particle colloidal dispersion sol obtained in Reaction Example 3 was added to
1 g of polyoxyethylene (10) octyl phenyl ether (boiling point: 200 ° C. or higher), which is a water-soluble solvent, was added and stirred, and the obtained sol liquid for producing an aggregate of tungsten oxide fine particles was dip-coated on a slide glass.
Several coating films were obtained by changing the lifting speed, and one side was wiped off and dried on a hot plate set at 60 ° C., whereby a transparent and uniform film was obtained. 45 in electric furnace
The agglomerated material was fixed to the slide glass by sintering at 0 ° C. for 20 minutes, and the aggregate was scraped off linearly using the blade of a small screwdriver, and the film thickness was measured with a surface roughness meter. A film had been obtained.

(Comparative Example 9) An attempt was made to dip-coat a slide glass using the tungsten oxide fine particle colloidal dispersion sol obtained in Reaction Example 3 as it was.
Only a state where the white powder was weakly adhered to the glass was obtained. Further, in order to obtain a film thickness of 0.4 μm by spin coating, it was necessary to repeat coating and sintering (450 ° C., 20 minutes) five times.

[0059]

[Table 1]

Example 12 A 50 ml eggplant-shaped flask was charged with 10 g of the titanium oxide fine particle colloidal dispersion sol obtained in Reaction Example 1 and 5 g of a water-insoluble solvent, cyclohexanol (boiling point: 161 ° C.). The solvent was reduced on a rotary evaporator while maintaining the temperature at 60 ° C. Some time after the start of the operation, droplets considered to be water appeared in the solution, but disappeared when the operation was continued. At this stage, the operation was terminated, and 5.1 g of a pale yellow-green cyclohexanol-substituted sol solution was obtained. 0.8911 g was taken out of the sol liquid for producing an aggregate of titanium oxide fine particles,
After baking for minutes, 0.071 g of an aggregate of titanium oxide fine particles was obtained, and the amount of the titanium oxide component in the sol solution was 8.2% by weight. This sol solution was used for No. When the composition was applied on a slide glass with a wire bar No. 10 and baked at 450 ° C. for 20 minutes, a 1 μm transparent film was firmly adhered to the slide glass. Examination of the crystal structure by X-ray diffraction revealed that anatase-type titanium oxide was formed. According to the scanning electron microscope observation, the diameter 5
It was observed that particles of about 10 to 10 nm were aggregated.

Example 13 An experiment was performed in the same manner as in Example 12, except that 5 g of cyclohexanol was replaced with 10 g of 1-heptanol (boiling point: 176 ° C.) which was a water-insoluble solvent. The solution immediately after mixing 1-heptanol was cloudy, but became clear as evaporation continued. When the solution became sufficiently transparent, the operation was terminated, and a transparent sol solution was obtained. The results are shown in Table 2 below.

Example 14 The procedure of Example 12 was repeated, except that 5 g of cyclohexanol was replaced with 10 g of dimethyl sulfoxide (boiling point: 189 ° C.) as a water-soluble solvent.
The same experiment as in Example 12 was performed. The solution was clear when mixed with dimethyl sulfoxide. The operation was terminated when the droplets attached to the neck of the eggplant flask disappeared, and a transparent sol solution was obtained. The results are shown in Table 2 below.

Example 15 An experiment was performed in the same manner as in Example 12, except that 5 g of cyclohexanol was replaced with 10 g of N-methylpyrrolidone (boiling point: 202 ° C.) as a water-soluble solvent. The solution turned yellow when N-methylpyrrolidone was mixed, but was transparent. The operation was terminated when the droplets attached to the neck of the eggplant flask disappeared, and a transparent sol solution was obtained. The results are shown in Table 2 below.

Example 16 An experiment was performed in the same manner as in Example 12, except that 5 g of cyclohexanol was replaced with 10 g of cyclohexanone (boiling point: 156 ° C.) which was a water-insoluble solvent. The solution was clear when mixed with cyclohexanone. The operation was terminated when the droplets attached to the neck of the eggplant flask disappeared, and a transparent sol solution was obtained. The results are shown in Table 2 below.

(Example 17) In Example 12, 10 g of a titanium oxide fine particle colloidal dispersion sol was added to 30 g, and 5 g of cyclohexanol was added to polyoxyethylene (10) octyl phenyl ether (a boiling point of 200) as a water-soluble solvent.
The same experiment as in Example 12 was performed, except that 6 g was used. The solution was clear when mixed with polyoxyethylene (10) octyl phenyl ether. The operation was terminated when the droplets attached to the neck of the eggplant flask disappeared, and a transparent sol solution was obtained. The results are shown in Table 2 below.

(Example 18) 0.1 g of dimethyl sulfoxide (boiling point: 189 ° C) was added to 1.9 g of the sol liquid for producing titanium oxide fine particle aggregates obtained in Example 13, and the mixture was vigorously mixed. The liquid became yellowish white and opaque, the viscosity increased sharply, and it became a paste. Using a 240 mesh screen provided with a 1.6 cm × 2.1 cm rectangular pattern using this paste, 2 cm
When screen printing was attempted on soda glass measuring 2.5 cm, a good print pattern could be obtained on the glass. After sintering at 450 ° C. for 20 minutes, a transparent aggregated sintered film was obtained.

Comparative Example 10 In Example 12, 5 g of cyclohexanol was added to 10 g of toluene (boiling point: 111 ° C.).
The same operation as in Example 12 was attempted, except that the above was replaced with The solution immediately after mixing the toluene is strongly cloudy, and a white solid precipitates as evaporation is continued.
A coatable sol could not be obtained.

Comparative Example 11 In Example 12, 5 g of cyclohexanol was added to chlorobenzene (boiling point: 132 ° C.).
The same operation as in Example 12 was attempted, except that the amount was changed to 10 g. The solution immediately after chlorobenzene was mixed was strongly cloudy, and a white solid was precipitated as the evaporation was continued, so that a coatable sol could not be obtained.

(Comparative Example 12) In Example 12, 5 g of cyclohexanol was added to isoamyl acetate (boiling point: 142 ° C).
The same operation as in Example 12 was attempted, except that the amount was changed to 10 g. Immediately after mixing isoamyl acetate, a white solid was precipitated, and a coatable sol could not be obtained.

Comparative Example 13 The same operation as in Example 12 was attempted, except that 5 g of cyclohexanol was replaced with 10 g of 1,1,2-trichloroethane (boiling point: 114 ° C.). Immediately after mixing 1,1,2-trichloroethane, a white solid precipitated, and a coatable sol could not be obtained.

Comparative Example 14 In Example 12, 5 g of cyclohexanol was added with 10 g of tridecane (boiling point: 234 ° C.).
The same operation as in Example 12 was attempted, except that g was changed.
The solution immediately after mixing tridecane is separated into two layers,
As the evaporation was continued, a white solid precipitated, and a coatable sol solution could not be obtained.

Example 19 1.9 g of the cyclohexanol-substituted sol obtained in Example 12 was added to hydroxypropylcellulose (150-400 cP, manufactured by Wako Pure Chemical Industries, Ltd.).
1.9 g of a solution of 100 mg dissolved in 9.9 g of 1-heptanol was added and mixed well. This solution is
o. The composition was applied to a slide glass using a wire bar while changing the counts to 10, 20, 30, and 40, and dried on a hot plate set at 60 ° C., to give a homogeneous film that was all slightly opaque. The dried film was sintered in an electric furnace at 450 ° C. for 20 minutes. 1
When the coating was applied at Nos. 0, 20, and 30, a slightly cloudy sintered film was fixed on the slide glass. What was applied at 40 was a state in which a white solid adhered to the slide glass. When the crystal structure of the substance fixed to the slide glass was examined by X-ray diffraction, it was found that anatase-type titanium oxide was formed. According to observation with a scanning electron microscope, it was observed that particles having a diameter of about 15 nm were aggregated. Finally, the aggregate was scraped off linearly using the blade of a small screwdriver, and the film thickness was measured with a surface roughness meter. 0.8μ applied in 10
m, No. No. 20 was 1.4 μm. 3
The one coated at 0 was 1.8 μm.

(Example 20) 300 mg of ethyl cellulose (45-55 cps, manufactured by Wako Pure Chemical Industries, Ltd.) was added to 1.9 g of the cyclohexanol-substituted sol solution obtained in Example 12.
0.08 g of a solution dissolved in 9.7 g of heptanol
And 0.8 g of 1-heptanol were added and mixed well. This sol solution was evaluated by applying a wire bar in the same manner as in Example 19, and the results are shown in Table 2 below.

(Example 21) 300 mg of ethyl cellulose (45-55 cps, manufactured by Wako Pure Chemical Industries, Ltd.) was added to 1.9 g of the cyclohexanol-substituted sol solution obtained in Example 12.
0.16 solution in 9.7 g of heptanol
g, hydroxypropyl cellulose (manufactured by Wako Pure Chemical Industries, Ltd., 1
50-400 cP) 300 mg 1-heptanol9.
0.35 g of the solution dissolved in 7 g and 0.65 g of 1-heptanol were mixed well. The results of performing the same operation as in Example 19 on this sol solution are shown in Table 2 below.

Example 22 A solution obtained by adding 6 g of polyoxyethylene (10) octyl phenyl ether (boiling point: 200 ° C. or higher) as a water-soluble solvent to 30 g of the titanium oxide fine particle colloidal dispersion sol obtained in Reaction Example 1. In addition, hydroxypropyl cellulose (manufactured by Wako Pure Chemical Industries, Ltd., 1000-4
After dissolving 0.2 g of 000 cP), an evaporation operation was performed to obtain a slightly opaque sol liquid for producing an aggregate of titanium oxide fine particles. Example 18 using this sol liquid
An aggregate sintered thin film was prepared and evaluated in the same manner as described above. The results are shown in Table 2 below.

Example 23 1.9 g of the sol obtained in the same manner as in Example 19 was added to dimethyl sulfoxide 0.1.
g was added and mixed vigorously, the sol liquid became yellowish white and opaque, the viscosity increased sharply, and it became a paste. An aggregate sintered thin film was prepared and evaluated in the same manner as in Example 18 using this paste. The results are shown in Table 2 below.

Example 24 1.9 g of a sol obtained in the same manner as in Example 20 was added to dimethyl sulfoxide 0.1.
g was added and mixed vigorously, the sol liquid became yellowish white and opaque, the viscosity increased sharply, and it became a paste. An aggregate sintered thin film was prepared and evaluated in the same manner as in Example 18 using this paste. The results are shown in Table 2 below.

Example 25 1.9 g of a sol obtained in the same manner as in Example 21 was added to dimethyl sulfoxide 0.1.
g was added and mixed vigorously, the sol liquid became yellowish white and opaque, the viscosity increased sharply, and it became a paste. An aggregate sintered thin film was prepared and evaluated in the same manner as in Example 18 using this paste. The results are shown in Table 2 below.

[0079]

[Table 2]

Example 26 A 5 mm × 5 mm fluorine-doped tin oxide transparent conductive layer was provided on a 2 cm × 2.5 cm soda glass substrate. An aggregate sintered film having a thickness of 5.6 μm was formed on the tin oxide transparent conductive layer in the same manner as in Example 8 to obtain a semiconductor layer. However, a squeegee coating method similar to that of Example 9 was used as the coating method. This sample was prepared using a dye Ru535, 1 manufactured by Solaronix.
Dye solution 3 obtained by dissolving 0.3 mg in 50 ml of ethanol
When immersed in ml overnight, the membrane stained dark purple.
The molar absorption coefficient of Ru535 was 14200, and the amount of dye adsorbed per 1 cm ² was estimated from the change in the absorbance of the dye solution as follows: A = ｛(absorbance of dye solution before adsorption) − (after adsorption) Absorbance of the dye solution of) (molar extinction coefficient of Ru535) (estimated adsorption amount) = (A × 0.003) ÷ (area of sample) = 5.2 × 10 ^-8 mole.

A wet-type photoelectric conversion device was manufactured using the dye adsorption film as a semiconductor electrode, and was 550 nm and 0.1 mW / cm.
^{When the} photoelectric conversion efficiency was measured using the monochromatic light of ² , the result was 7
A value of 5% was obtained. TG-50 manufactured by Solaronix was used as an electrolyte, and ITO glass coated with platinum by sputtering was used as a counter electrode.

(Example 27) An aggregate sintered film having a thickness of 5.0 µm was obtained in the same manner as in Example 9, and a photoelectric conversion device was fabricated and evaluated in the same manner as in Example 26. However, a wire bar coating method was used as a coating method. The results are shown in Table 3 below.

Example 28 1.5 g of 1-heptanol was added to 1.5 g of the sol obtained in the same manner as in Example 12.
0.6 g of P25 particles and an appropriate amount of glass beads were added, and the mixture was dispersed with a paint shaker for 1 hour to obtain a dispersion. 1.9 g of this dispersion was added to dimethyl sulfoxide 1
When 00 mg was added and mixed vigorously, the viscosity of the solution rapidly increased to form a paste. This paste was screen-printed on the same tin oxide transparent conductive layer as in Example 26, sintered at 450 ° C. for 20 minutes, and 5.5 μm in thickness.
A photoelectric conversion device was produced in the same manner as in Example 26 except that an aggregate sintered film was obtained. The results of evaluation in the same manner as in Example 26 are shown in Table 3 below.

(Example 29) To 1.5 g of the sol obtained in the same manner as in Example 9, 1.45 g of 1-heptanol,
0.6 g of P25 particles and an appropriate amount of glass beads were added, and the mixture was dispersed with a paint shaker for 1 hour to obtain a dispersion. To 1.85 g of this dispersion, 300 m of hydroxypropyl cellulose (150 to 400 cP, manufactured by Wako Pure Chemical Industries, Ltd.)
g solution in 9.7 g of 1-heptanol.
When 05 g and 100 mg of dimethylsulfoxide were added and mixed vigorously, the viscosity of the solution rapidly increased to form a paste. This paste was prepared in Example 26.
A photoelectric conversion device was produced in the same manner as in Example 26, except that a screen printing was performed on the same tin oxide transparent conductive layer as in Example 1 and sintering was performed at 450 ° C. for 20 minutes to obtain a 6.0 μm aggregated sintered film. . The results of evaluation in the same manner as in Example 26 are shown in Table 3 below.

(Embodiment 30) In the embodiment 29, P2
A photoelectric conversion device was produced in the same manner as in Example 29, except that five particles were replaced with the nitric acid-treated metal oxide particles obtained in Reaction Example 2 to obtain an aggregate sintered film having a thickness of 5.2 μm. The results of evaluation in the same manner as in Example 26 are shown in Table 3 below.

(Comparative Example 15) The metal oxide fine particle colloidal dispersion sol obtained in Reaction Example 1 was spin-coated and sintered on the same tin oxide transparent conductive layer as in Example 26 by one step.
A photoelectric conversion device was manufactured in the same manner as in Example 26, except that an aggregate sintered film having a thickness of 2.0 μm was obtained by repeating the process five times.
The results of evaluation in the same manner as in Example 26 are shown in Table 3 below.

[0087]

[Table 3]

As specifically shown in the examples, by using the sol liquid for producing metal oxide fine particle aggregates of the present invention, the metal oxide having a thickness which cannot be realized by the conventional composite gelation method was obtained. An object-aggregated thin film can be easily produced. In addition, by selecting a specific high boiling solvent, it is possible to apply a screen printing method excellent in productivity,
Aggregates of metal oxide fine particles suitable for photovoltaic materials, photoconductive materials, and photocatalytic materials, photoelectric conversion devices using the aggregates of metal oxide fine particles, and the like can be manufactured at low cost.

[0089]

According to the present invention, it is possible to provide a sol liquid for producing an aggregate of metal oxide fine particles having excellent productivity and a method for producing the same. Further, according to the present invention, it is possible to provide a metal oxide fine particle aggregate produced from the sol liquid for producing a metal oxide fine particle aggregate and suitable for a photovoltaic material, a photoconductive material, and a photocatalyst material. Further, according to the present invention, it is possible to provide a photoelectric conversion device having excellent photoelectric conversion efficiency using the metal oxide fine particle aggregate.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an example of a photoelectric conversion device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Translucent conductive layer 3 Semiconductor layer 4 Semiconductor electrode 5 Electrolyte layer 6 Electrode film 7 Glass substrate 8 Counter electrode

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01M 14/00 H01L 31/04 Z 5H032 (72) Inventor Yoshiyuki Ono 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Zero 4G042 DA01 DB11 DC01 DD04 DD08 DE09 DE14 4G047 AA02 AB02 AC03 AD03 4G048 AA02 AB02 AC08 AD03 AD06 AE05 4G065 AA05 AB02X AB03X AB09X AB38X CA13 DA04 DA09 FA01 5F051 AA27 CB13 CB13 FA06 AS16 BB02 BB05 BB10 CC16 EE04 EE14

Claims (11)

[Claims] 1. A polymer compound having a carboxyl group is dissolved in a solution containing at least a metal alkoxide,
A composite gel containing the polymer compound having a carboxyl group and a metal alkoxide is generated, and the reaction is further continued to generate a metal oxide fine particle colloid dispersion sol solution. A water-soluble solvent having a boiling point of 120 ° C, and / or an alcohol which is a non-water-soluble solvent having a boiling point of 120 ° C or more;
A method for producing a sol liquid for producing an aggregate of metal oxide fine particles, comprising mixing at least one selected from ethers and ketones to obtain a sol liquid for producing an aggregate of metal oxide fine particles. 2. The method according to claim 1, wherein the polymer compound having a carboxyl group is polyacrylic acid. 3. The method for producing a metal oxide fine particle aggregate producing sol liquid according to claim 1, wherein at least one selected from alkyl celluloses and hydroxylated alkyl celluloses is dissolved. 4. The method for producing a sol liquid for producing an aggregate of metal oxide fine particles according to claim 1, wherein the metal oxide particles are separately dispersed. 5. The sol liquid according to claim 4, wherein the separately dispersed metal oxide particles are dry particles obtained by mixing with nitric acid and removing the nitric acid. Method. 6. The method according to claim 4, wherein the separately dispersed metal oxide particles are at least one selected from titanium oxide, zinc oxide, and tin oxide. Of producing sol liquid for use. 7. The method for producing a sol liquid for producing an aggregate of metal oxide fine particles according to claim 1, wherein the metal alkoxide is a titanium compound. 8. A sol liquid for producing metal oxide fine particle aggregates, which is produced by the method for producing a sol liquid for producing metal oxide fine particle aggregates according to any one of claims 1 to 7. 9. A metal oxide fine particle aggregate obtained by drying the sol liquid for producing a metal oxide fine particle aggregate according to claim 8. 10. The metal oxide fine particle aggregate according to claim 9, wherein the metal oxide fine particle aggregate is in the form of a thin film. 11. A photoelectric conversion device comprising an electrolyte layer sandwiched between a semiconductor electrode having at least a semiconductor layer and a counter electrode, wherein the semiconductor layer is a metal oxide according to claim 10. A photoelectric conversion device comprising a fine particle aggregate.