JP2001155791A - Photoelectric cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric cell whose absorption quantity of a photosensitizer in a metal oxide semiconductor layer is high, bonding strength between the metal oxide semiconductor layer and the photosensitizer is strong and the photoelectric conversion efficiency is remarkably improved. SOLUTION: In the photoelectro cell, (i) a semiconductor film 2 of metallic oxide consists of metallic oxide particles in range of 5-600 nm of average particle diameter, (ii) the metallic oxide particles is core-shell structure of core particle and shell formed on surface of the core particle, (iii) average particle diameter of the core is in a range of 2-500 nm and thickness of the shell is in a range of 1-150 nm, and (iv) an inherent volume resistance (Ec) of metallic oxide consisting the core particle and an inherent volume resistance (Es) of metallic oxide consisting the shell have a relation of Ec<Es.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a photoelectric cell having excellent photoelectric conversion efficiency. More specifically, since a specific metal oxide semiconductor film is formed on the surface of the electrode layer, the amount of adsorption and support of the photosensitizer is high, and the bonding strength between the metal oxide semiconductor layer and the photosensitizer is high. Electrons are quickly transferred from the photosensitizer layer, which has absorbed and excited light, to the metal oxide semiconductor film, and further, electrons are quickly transferred from the metal oxide semiconductor film to the electrode film. The electrons transferred to the metal oxide semiconductor film are less likely to recombine with the photosensitizer and the electrons,
The present invention relates to a photoelectric cell having improved photoelectric conversion efficiency.

[0002]

BACKGROUND OF THE INVENTION A photoelectric conversion material is a material that can continuously take out light energy as electric energy, and is a material that converts light energy into electric energy by utilizing an electrochemical reaction between electrodes. When such a photoelectric conversion material is irradiated with light, electrons are generated on one electrode side, move to the counter electrode, and the electrons moved to the counter electrode move as ions in the electrolyte and return to the one electrode. Since this energy conversion is continuous, it is used for, for example, solar cells.

In a general solar cell, first, a film of a semiconductor for a photoelectric conversion material is formed on a support such as a glass plate on which a transparent conductive film is formed to form an electrode, and then another transparent electrode is formed as a counter electrode. With a support such as a glass plate on which a conductive film is formed,
An electrolyte is sealed between these electrodes. When the photosensitizer adsorbed on the semiconductor for a photoelectric conversion material is irradiated with sunlight, the photosensitizer absorbs and excites light in a visible region.
The electrons generated by this excitation move to the semiconductor, then move to the transparent conductive glass electrode, move to the counter electrode through the conductor connecting the two electrodes, and the electrons moved to the counter electrode are oxidized in the electrolyte. Reduce the reduction system. On the other hand, the photosensitizer in which electrons have been transferred to the semiconductor is in an oxidized state, which is reduced by a redox system in the electrolyte and returns to the original state. Thus, electrons flow continuously,
The photoelectric conversion material functions as a solar cell.

As this photoelectric conversion material, a material in which a spectral sensitizing dye having absorption in a visible light region is adsorbed on a semiconductor surface is used. For example, Japanese Patent Application Laid-Open No. Hei.
Japanese Patent Laid-Open Publication No. HEI 9-176566 describes a solar cell having a spectral sensitizing dye layer made of a transition metal complex such as a ruthenium complex on the surface of a metal oxide semiconductor. In addition, Tokuhyo Hei 5-5040
No. 23 describes a solar cell having a spectral sensitizing dye layer made of a transition metal complex such as a ruthenium complex on the surface of a titanium oxide semiconductor layer doped with metal ions.

[0005] In the above solar cell, it is important to improve the light conversion efficiency that electrons are quickly transferred from the spectral sensitizing dye layer, which is excited by absorbing light, to the titanium oxide semiconductor layer. If the electron transfer is not performed, recombination of the ruthenium complex with the electrons occurs, causing a problem that the light conversion efficiency is reduced. For this reason, studies have been made to increase the amount of adsorption between the surface of the titanium oxide semiconductor film and the spectral sensitizing dye and to improve the electron mobility in the titania film.

For example, when a titanium oxide semiconductor film is formed, the steps of applying titania sol on an electrode substrate, drying and then firing are repeated to form a porous thick film, and the semiconductor film is made porous. Thus, it has been proposed to increase the amount of the Ru complex supported on the surface. It has also been proposed that the titania particles be fired at a temperature of 400 ° C. or higher to improve the conductivity. Further, Japanese Patent Application Laid-Open No. 6-511113 proposes, in order to increase the effective surface, immersion in an aqueous solution of titanium chloride or electrochemical deposition on a titania film using a hydrolysis solution of titanium chloride. I have.

However, in these methods, the titanium oxide semiconductor film is fired in order to improve the electron mobility. Therefore, the porosity (effective surface) is reduced by sintering of the particles, and the spectral sensitizing dye is reduced. There is a problem such as a decrease in the adsorption amount of, and the photoelectric conversion efficiency is not always sufficient, and further improvement has been desired. The present inventors have proposed a method for manufacturing a titanium oxide semiconductor film for a photovoltaic cell and a photovoltaic cell in which these points are improved (for example, Japanese Patent Application No. 10-149).
550). However, according to this method, although the conventional disadvantages are improved, the adsorption amount of the spectral sensitizing dye is improved, and the photoelectric conversion efficiency is improved, but it is required to further improve the photoelectric conversion efficiency.

[0008]

An object of the present invention is to increase the amount of photosensitizer adsorbed in a metal oxide semiconductor layer, to increase the bonding strength between the metal oxide semiconductor layer and the photosensitizer, and to significantly improve photoelectric conversion efficiency. It is an object of the present invention to provide a photovoltaic cell having the above configuration.

[0009]

SUMMARY OF THE INVENTION A photovoltaic cell according to the present invention comprises an electrode layer (1) on the surface, and a metal oxide semiconductor film (2) having a photosensitizer adsorbed on the surface of the electrode layer (1). A substrate formed and a substrate having an electrode layer (3) on the surface are arranged so that the metal oxide semiconductor film (2) and the electrode layer (3) face each other, and the metal oxide semiconductor film (2) In the photoelectric cell comprising an electrolyte layer provided between the electrode layer (3), (i) the metal oxide semiconductor film (2) is a metal oxide having an average particle diameter in the range of 5 to 600 nm. (Ii) the metal oxide particles,
It has a core-shell structure consisting of a core particle and a shell portion formed on the surface of the core particle, (iii) the average particle size of the core particle is in the range of 2 to 500 nm, and the thickness of the shell portion is 1 And (iv) the volume resistivity (E _c ) of the metal oxide constituting the core particles and the volume resistivity (E _s ) of the metal oxide constituting the shell portion are expressed by E It is set to satisfy the relationship shown by the _c <E _s.

It is preferable that the metal oxide constituting the shell part is crystalline titanium oxide. The crystalline titanium oxide is preferably obtained by heating and aging peroxotitanic acid. The metal oxide semiconductor film is preferably made of a titanium oxide binder together with metal oxide particles.

[0011]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the photoelectric cell according to the present invention will be specifically described. The photoelectric cell according to the present invention has an electrode layer (1) on the surface, and a substrate on which a metal oxide semiconductor film (2) having a photosensitizer adsorbed on the surface of the electrode layer (1) is formed. And a substrate having an electrode layer (3) on the surface, the metal oxide semiconductor film (2) and the electrode layer (3) are arranged so as to face each other, the metal oxide semiconductor film (2) and the electrode An electrolyte layer is provided between the layer (3).

In this photoelectric cell, the metal oxide semiconductor film
(2) is composed of metal oxide particles having an average particle diameter in the range of 5 to 600 nm, the metal oxide particles are a core particle having an average particle diameter in the range of 2 to 500 nm, and the surface of the core particles Having a core-shell structure composed of a metal oxide and a shell made of a metal oxide, wherein the thickness of the shell is 1 to 1.
In the range of 150 nm, the volume resistivity (E _c ) of the material constituting the core particles and the volume resistivity (E _s ) of the metal oxide constituting the shell portion satisfy E _c <E _s . It is characterized by satisfying the relationship.

FIG. 1 shows an example of such a photoelectric cell. FIG. 1 is a schematic sectional view showing one embodiment of the photoelectric cell according to the present invention.
Reference numeral 1 is a transparent electrode layer, 2 is a semiconductor film, 3 is an electrode layer having a catalytic activity for reduction, 4 is an electrolyte, and 5 and 6 are substrates. The photovoltaic cell shown in FIG. 1 has a transparent electrode layer 1 on the surface, a substrate 5 on which a semiconductor film 2 on which a photosensitizer is adsorbed is formed on the surface of the transparent electrode layer 1, and a reduction electrode A substrate 6 having an electrode layer 3 having catalytic ability is arranged so that the electrode layers 1 and 3 face each other, and an electrolyte 4 is sealed between the metal oxide semiconductor film 2 and the electrode layer 3. .

As the transparent substrate 5, a transparent and insulating substrate such as a glass substrate or an organic polymer substrate such as PET can be used. The substrate 6 is not particularly limited as long as it has strength enough to be used.
In addition to an insulating substrate made of an organic polymer substrate such as PET, a conductive substrate made of metal titanium, metal aluminum, metal copper, metal nickel, or the like can be used.

Further, a spacer 7 may be interposed between the metal oxide semiconductor film 2 and the transparent electrode layer 3,
If a spacer is interposed, the transparent substrate 5 and the substrate 6 have P
A deformable substrate such as an ET film can be used, and a photoelectric cell having a shape other than a flat plate, for example, a semi-cylindrical shape can be used. In this case, for example,
It is possible to obtain a transparent or thin and flexible photoelectric cell or the like.

The transparent electrode layer 1 formed on the surface of the transparent substrate 5
As the electrode, a conventionally known electrode such as tin oxide, tin oxide doped with Sb, F or P, indium oxide doped with Sn and / or F, antimony oxide, zinc oxide, and a noble metal can be used. . Such a transparent electrode layer 1 can be formed by a conventionally known method such as a thermal decomposition method and a CVD method.

The electrode layer 3 formed on the surface of the substrate 6 is not particularly limited as long as it has a reduction catalytic activity, and may be an electrode material such as platinum, rhodium, ruthenium metal or ruthenium oxide. Tin oxide, Sb, F or P
It is possible to use a conventionally known electrode such as an electrode obtained by plating or depositing the electrode material on the surface of a conductive material such as tin oxide, Sn and / or F doped with Sn and / or F, and a carbon electrode. it can.

The electrode layer 3 is formed by directly coating, plating or depositing the electrode on the substrate 6 to form a conductive layer on the conductive material by a conventionally known method such as a thermal decomposition method or a CDV method. The electrode material can be formed on the conductive layer by a conventionally known method such as plating or vapor deposition. The substrate 6 may be transparent like the transparent substrate 5, and the electrode layer 3 may be a transparent electrode like the transparent electrode layer 1.

The visible light transmittance of the transparent substrate 5 and the transparent electrode layer 1 is preferably higher, specifically, 50% or more, particularly preferably 90% or more. When the visible light transmittance is less than 50%, the photoelectric conversion efficiency may decrease. The resistance of each of the transparent electrode layer 1 and the electrode layer 3 is preferably 100 Ω / □ or less. If the resistance value of the electrode layer exceeds 100Ω / □, the photoelectric conversion efficiency may decrease.

The metal oxide semiconductor film 2 may be formed on the electrode layer 3 formed on the substrate 6. The thickness of the metal oxide semiconductor film 2 is preferably in the range of 0.1 to 50 μm. In particular, the metal oxide particle semiconductor film is made of metal oxide particles having a specific core-shell structure.

The average particle diameter of the metal oxide particles is 5 to 60.
It is desirably in the range of 0 nm, preferably 10 to 300 nm. When the average particle diameter of the metal oxide particles is less than 5 nm, cracks are easily generated in the formed metal oxide semiconductor film, and it is difficult to form a crack-free thick film having a film thickness described below in a small number of times. In addition, the pore diameter and pore volume of the metal oxide semiconductor film may decrease, and the adsorption amount of the photosensitizer may decrease. Further, when the average particle diameter of the metal oxide particles exceeds 600 nm, the strength of the metal oxide semiconductor film may be insufficient.

The particle diameters of the metal oxide particles and the core particles described below can be measured with a laser Doppler type particle diameter measuring device (Microtrack manufactured by Nikkiso Co., Ltd.). Such a metal oxide particle has a core particle and a core-shell structure in which a shell portion is formed on the surface of the core particle.

The average particle size of the core particles is 2 to 500 nm.
Preferably, it is in the range of 4 to 250 nm.
When the average particle size of the core particles is less than 2 nm, the effect of using the core particles having higher conductivity than the shell portion is not sufficiently exhibited, and the metal composed of a single phase of the metal oxide constituting the shell portion is not obtained. It does not differ from oxide particles at all, and therefore recombination of electrons occurs, resulting in insufficient photoelectric conversion efficiency. If the average particle size of the core particles exceeds 500 nm, the amount of the photosensitizer adsorbed is high, and the ratio of the shell portion that absorbs visible light to excite and efficiently generate electrons is reduced, so that the photoelectric conversion efficiency is reduced. Becomes insufficient.

The thickness of the shell portion constituting the metal oxide particles depends on the size of the metal oxide particles.
It is desirably in the range of 50 nm, preferably 2 to 100 nm. In the metal oxide particles having a core-shell structure used in the present invention, the volume resistivity of the metal oxide constituting the core particles (E _c ) and the volume resistivity of the metal oxide constituting the shell portion (E _s ) satisfies the relationship expressed by E _c <E _s .

The volume resistivity (E _c ) of the core particles is 10 ¹⁰
Ω · cm or less, preferably 10 ⁵ Ω · cm or less, particularly preferably 10 ³ Ω · cm or less. Further, it is desirable that the volume resistivity of the shell portion is 10 ¹⁶ Ω · cm or less, preferably 10 ¹⁴ Ω · cm or less. Volume resistivity (E _c ) of the metal oxide that constitutes the core particles
And the volume resistivity of the metal oxide forming the shell
When (E _s ) has the above relationship, the photoelectric conversion efficiency of the photoelectric cell in which the semiconductor film including such metal oxide particles is formed is improved. It is not clear why the photoelectric conversion efficiency is improved, but in the case of conventional particles comprising a single-phase metal oxide component, electrons in the photosensitizer layer excited by absorbing light at the surface layer of the particles are removed. Recombines with other excited photosensitizers to move the surface of the particles,
Alternatively, the photoelectric conversion efficiency could not be increased due to a longer electron transfer distance. On the other hand, the use of particles having a core-shell structure as described in the present application allows light to be absorbed in the shell portion. When the electrons of the photosensitizer layer excited by the excitation move quickly to the highly conductive core particles without recombination, and furthermore, the transfer of the electrons to the electrode film is rapidly performed, thereby improving the photoelectric conversion efficiency. Conceivable.

The volume resistivity of the metal oxide particles can be measured by the following method. The cross-sectional area is 0.5cm ²
Is filled with 0.5 g of particles into a ceramic cylindrical cell, and placed on a pedestal with a connection terminal for resistance measuring device, and a lid with a pressure rod (piston-like) with a terminal is pressed from above with a pressure of 100 kg / cm ^2. And the height of the metal oxide particles in the cell when pressurized are determined, and the resistance (Ω) is calculated by converting the height to 1 cm and the cross-sectional area to 1 cm ² . The volume resistivity of the shell was determined by preparing particles made of the material constituting the shell, and using the volume resistivity of the particles as the volume resistivity of the shell.

Specific example: measured resistance value 100Ω, height 0.4
cm, 100 x (1 / 0.4 cm) x 0.5 cm ² = 125 Ω
cm 2 As the metal oxide constituting the core particles and the shell portion, as long as the above relational expression is satisfied (the conductivity of the metal oxide constituting the core particle is higher than the conductivity of the metal oxide constituting the shell portion). Is not particularly limited, and titanium oxide, lanthanum oxide, zirconium oxide, niobium oxide, tungsten oxide, strontium oxide, zinc oxide, tin oxide, indium oxide, lower titanium oxide (Ti ₂ O ₃ ), Al-doped zinc oxide, F or S
Examples include at least one or two or more metal oxides selected from b-doped tin oxide and Sn-doped indium oxide.

As a particularly preferred combination of the core particles and the metal oxide constituting the shell part used in the present invention, the core particles are composed of F-doped tin oxide, Sn-doped indium oxide, indium oxide, low titanium oxide (Ti
₂ O ₃ ), Al-doped zinc oxide, etc., and the metal oxide used for the shell portion is crystalline titanium oxide such as anatase (anatase) type titanium oxide, brookite type titanium oxide, rutile type titanium oxide. A configured one is preferred.

When the shell portion is made of such crystalline titanium oxide, the band gap is high, the dielectric constant is high, and the amount of the photosensitizer adsorbed is higher than other metal oxides. Further, it has excellent characteristics such as excellent stability and safety and easy film formation. The crystallite diameter of such a crystalline titanium oxide is 1 to 50 nm, preferably 5 to 30 nm.
It is preferably in the range of nm. The crystallite diameter of the crystalline titanium oxide particles can be determined by measuring the half width of the peak on the crystal plane of each crystal form by X-ray diffraction and calculating by the Debye-Scherrer equation. It can also be determined by observing a field emission type transmission electron micrograph (FE-TEM).

This crystalline titanium oxide has a crystallite diameter of 1n.
m, the electron mobility in the shell part is reduced,
If it is larger than 0 nm, the adsorption amount of the photosensitizer may decrease, and the photoelectric conversion efficiency may decrease. Further, since the particles are too large, adhesion to the core particles is low, and electron transfer from the shell portion to the core particles becomes difficult to occur. Such core particles constituting the core-shell structure used in the present invention can be produced by a conventionally known method. That is, a gel or sol of a hydrated metal oxide obtained by, for example, a sol-gel method is prepared using an inorganic compound salt or an organic metal compound which is a precursor of the above metal oxide, and an acid or an alkali is added as necessary. After that, it can be produced by a method such as heating and aging.

The shell part is obtained by dispersing the core particles obtained as described above in an aqueous solution or an alcohol solution of an inorganic compound salt or an organic metal compound which is a precursor of the metal oxide, and optionally adding an acid or an alkali. After the addition, it can be formed on the surface of the core particles by a method such as heating and aging. For example, core-shell particles formed of crystalline titanium oxide as a shell can be produced as follows.

Specifically, the above-mentioned core particles having higher conductivity than titanium oxide are dispersed in a hydrous titanate gel or sol obtained by a sol-gel method or the like, and an acid or alkali is added as necessary. After heating and aging, core-shell particles formed of crystalline titanium oxide as a shell can be obtained. Further, the core-shell particles having a shell portion formed of crystalline titanium oxide are formed by adding hydrogen peroxide to a hydrous titanic acid gel or sol to dissolve the hydrous titanic acid to form peroxotitanic acid, and then crystallize the peroxotitanic acid. The above-mentioned core particles having higher conductivity than the conductive titanium oxide are dispersed, and alkalis, preferably, ammonia and / or an organic base are added to make them alkaline, and the temperature is 80 to 350 ° C.
Can be obtained by heating and aging in the above temperature range. Further, it can be fired at a high temperature of 350 ° C. or more as necessary. In the metal oxide particles having a core-shell structure used in the present invention, it is particularly preferable that the shell portion is made of crystalline titanium oxide heated and aged by adding an alkali to peroxotitanic acid.

"Peroxotitanic acid" refers to hydrated titanium peroxide, and such hydrated titanium peroxide has an absorption range in the visible light region. This peroxotitanic acid is prepared by adding hydrogen peroxide to an aqueous solution of a titanium compound or a sol or gel of hydrated titanium oxide and heating. The sol or gel of hydrated titanium oxide is
It is obtained by adding an acid or alkali to an aqueous solution of a titanium compound, hydrolyzing the resultant, and optionally washing, heating and aging. The titanium compound used is not particularly limited, but titanium halides, titanium salts such as titanyl sulfate, titanium alkoxides such as tetraalkoxytitanium,
A titanium compound such as titanium hydride can be used.

The sol or gel of hydrated titanium oxide is obtained by adding an acid or alkali to an aqueous solution of a titanium compound, hydrolyzing the resultant, and washing, heating and aging as necessary. The titanium compound used is not particularly limited, but titanium halides, titanium salts such as titanyl sulfate,
A titanium alkoxide such as tetraalkoxytitanium or a titanium compound such as titanium hydride can be used.

The metal oxide semiconductor film 2 preferably contains a titanium oxide binder component together with the metal oxide particles. Examples of such a titanium oxide binder component include titanium oxide composed of a hydrous titanate gel or sol obtained by a sol-gel method or the like, and peroxot in which hydrous titanate is dissolved by adding hydrogen peroxide to a hydrous titanate gel or sol. Decomposition products of titanic acid and the like can be mentioned. When the shell part of the metal oxide particles is crystalline titanium oxide, a decomposition product of peroxotitanic acid is preferably used as a binder component.

Such a titanium oxide binder component comprises:
A dense and uniform adsorption layer is formed on the surface of metal oxide (crystalline titanium oxide) particles. Thus, the obtained metal oxide semiconductor film can have improved adhesion to an electrode. Furthermore, when such a titanium oxide binder component is used, the contact between the metal oxide (crystalline titanium oxide) particles changes from point contact to surface contact, so that the electron mobility can be improved, and the photosensitization can be improved. The amount of material adsorbed can be increased.

The ratio of the titanium oxide binder component to the metal oxide particles in the metal oxide semiconductor film 2 is 0.05 to 0.50 in terms of oxide-weight ratio (titanium oxide binder component / metal oxide particles). Preferably, it is in the range of 0.1 to 0.3. If the weight ratio is less than 0.05, light absorption in the visible light region is insufficient, and the amount of adsorption of the photosensitizer may not increase. When the weight ratio is higher than 0.50, a porous metal oxide semiconductor film may not be obtained, and the amount of the photosensitizer adsorbed may not be increased.

The metal oxide semiconductor film 2 has a pore volume of 0.5.
0.5 to 0.8 ml / g, preferably 0.2 to 0.8 ml
/ G and an average pore diameter of 2 to 250 nm, preferably 5 to 150 nm. When the pore volume is smaller than 0.05 ml / g, the adsorption amount of the photosensitizer is low, and when the pore volume is higher than 0.8 ml / g, the electron mobility in the film is reduced and the photoelectric conversion efficiency is reduced. May lower. When the average pore diameter is less than 2 nm, the adsorption amount of the photosensitizer decreases, and when it exceeds 250 nm, the electron mobility decreases and the photoelectric conversion efficiency may decrease.

Such a metal oxide semiconductor film 2 can be produced, for example, by using the following coating liquid for forming a metal oxide semiconductor film for a photoelectric cell. The coating solution for forming a metal oxide semiconductor film for a photoelectric cell used in the present invention is:
It consists of the above-mentioned metal oxide particles and a dispersion medium. further,
If necessary, a binder component precursor may be contained.Particularly, as a metal oxide particle, a shell portion formed on the surface of the core particle is heated and aged by adding an alkali to peroxotitanic acid. When a material composed of crystalline titanium oxide is used, it is desirable that peroxotitanic acid is contained as a precursor of the binder component. As described above, peroxotitanic acid is prepared by adding hydrogen peroxide to an aqueous solution of a titanium compound or a sol or gel of hydrated titanium oxide and heating. The sol or gel of hydrated titanium oxide is obtained by adding an acid or an alkali to an aqueous solution of a titanium compound, hydrolyzing the resultant, and optionally washing, heating and aging it.
The titanium compound used is not particularly limited, but titanium salts such as titanium halide and titanyl sulfate, titanium alkoxides such as tetraalkoxytitanium, and titanium compounds such as titanium hydride can be used.

The ratio of the precursor of the metal oxide binder component to the metal oxide particles in the coating solution for forming a metal oxide semiconductor film for a photovoltaic cell is such that the precursor of the metal oxide binder component is the oxide MO _X (1 expressed in), 0.03 metal oxide particles MO _X (weight ratio when expressed in _{2) (MO X (1)} / MO X (2))
It is desirably in the range of 0.50, preferably 0.1 to 0.3. If the weight ratio is less than 0.03, the strength and conductivity of the metal oxide semiconductor film may be insufficient, and the adsorption amount of the photosensitizer may not increase. If the weight ratio is higher than 0.50, a porous semiconductor film may not be obtained, and the electron mobility may not be improved.

The precursor of the metal oxide binder component and the metal oxide particles are used as (MO _X (1) + MO _X (2)) in the coating liquid for forming the metal oxide semiconductor film for the photoelectric cell. It is desirable that it be contained at a concentration of 1 to 30% by weight, preferably 2 to 20% by weight. The dispersion medium is not particularly limited as long as the precursor of the metal oxide binder component and the metal oxide particles can be dispersed and can be removed when dried, and alcohols are particularly preferable.

Further, the coating liquid for forming a metal oxide semiconductor film for a photovoltaic cell may contain a film forming aid, if necessary. Examples of the film forming aid include polyethylene glycol, polyvinylpyrrolidone, hydroxypropylcellulose, polyacrylic acid, and polyvinyl alcohol. When such a film-forming aid is contained in the coating solution, the viscosity of the coating solution increases, whereby a uniformly dried film is obtained. The density can be increased, and a metal oxide semiconductor film having high adhesion to an electrode can be obtained.

Such a coating liquid for forming a metal oxide semiconductor film for a photoelectric cell is applied to the surface of the electrode layer of the substrate provided with the above-mentioned electrode layer, dried, and then cured to obtain a metal oxide. An object semiconductor film can be formed. It is preferable that the coating liquid is applied so that the thickness of the finally formed metal oxide semiconductor film is in the range of 0.1 to 50 μm. The coating solution can be applied by a conventionally known method such as a dipping method, a spinner method, a spray method, a roll coater method, flexographic printing, and screen printing.

The drying temperature is not particularly limited as long as the dispersion medium can be removed. In the present invention, if necessary, the coating film may be irradiated with ultraviolet rays to be cured.
Irradiation of ultraviolet rays causes the precursor of the binder component to be decomposed and cured. When the coating liquid contains a film forming aid, the film forming aid may be decomposed by further heating after the coating film is cured.

In the present invention, after the coating film is cured by irradiating ultraviolet rays, O ₂ , N ₂ , H ₂ , neon, argon,
Annealing may be performed after irradiation with ions of at least one gas selected from inert gases of Group 0 of the periodic table such as krypton. For the ion irradiation, a known method such as a method of injecting boron or phosphorus into a silicon wafer to a certain amount and a certain depth into a silicon wafer when manufacturing an IC or an LSI can be adopted.

Annealing is performed by heating at a temperature of 200 to 500 ° C., preferably 250 to 400 ° C., for 10 minutes to 20 hours. By ion irradiation,
These ions do not remain in the metal oxide semiconductor film, many defects are generated on the surface of the metal oxide particles, and annealing is performed, thereby improving the crystallinity of the metal oxide particles and joining the particles. Is promoted, which increases the bonding strength with the photosensitizer and increases the amount of adsorption,
Further, by promoting the bonding of the particles, the electron mobility is improved, so that the photoelectric conversion efficiency is improved.

In the present invention, the metal oxide semiconductor film 2 adsorbs the photosensitizer. The photosensitizer is not particularly limited as long as it absorbs and excites light in a visible light region and / or an infrared light region. For example, an organic dye, a metal complex, or the like can be used. As the organic dye, a conventionally known organic dye having a functional group such as a carboxyl group, a hydroxyalkyl group, a hydroxyl group, a sulfone group, and a carboxyalkyl group in a molecule can be used. Specific examples thereof include metal-free phthalocyanine, cyanine-based dyes, metalocyanine-based dyes, triphenylmethane-based dyes, and xanthene-based dyes such as uranine, eosin, rose bengal, rhodamine B, and dibromofluorescein. These organic dyes have a characteristic that the adsorption speed to the metal oxide semiconductor film is high.

Further, as the metal complex, JP-A-1-220380
No., metal phthalocyanines such as copper phthalocyanine and titanyl phthalocyanine described in Japanese Patent Publication No. Hei 5-504023, chlorophyll, hemin, ruthenium-tris
(2,2'-bispyridyl-4,4'-dicarboxylate), cis-
(SCN ⁻ ) -bis (2,2′-bipyridyl-4,4′-dicarboxylate) ruthenium, ruthenium-cis-diaqua-bis (2,
Ruthenium-cis-diaqua-bipyridyl complex such as 2'-bipyridyl-4,4'-dicarboxylate), zinc-tetra (4-
Porphyrins such as (carboxyphenyl) porphine,
Ruthenium, osmium, such as iron-hexacyanide complex,
Complexes such as iron and zinc can be mentioned. These metal complexes are excellent in the effect of spectral sensitization and durability.

These organic dyes or metal complexes may be used alone, two or more of the organic dyes or metal complexes may be used in combination, or the organic dye and the metal complex may be used in combination. The method for adsorbing such a photosensitizer to a semiconductor film is not particularly limited, and a solution obtained by dissolving the photosensitizer in a solvent is subjected to metal oxide semiconductor by a method such as dipping, spinner, or spraying. General methods such as absorption into a film and subsequent drying can be employed. Further, the absorption step may be repeated as necessary. Alternatively, the photosensitizer can be adsorbed to the metal oxide semiconductor film by bringing the photosensitizer into contact with the substrate while heating and circulating the solution.

The solvent for dissolving the photosensitizer may be any solvent capable of dissolving the photosensitizer, and specifically, water, alcohols, toluene, dimethylformamide, chloroform, ethylcellosolve, N- Methylpyrrolidone, tetrahydrofuran and the like can be used. The amount of the photosensitizer adsorbed on the metal oxide semiconductor film is preferably 50 μg or more per 1 cm ² of the specific surface area of the metal oxide semiconductor film. When the amount of the photosensitizer is less than 50 μg, the photoelectric conversion efficiency may be insufficient.

As shown in FIG. 2, the photovoltaic cell according to the present invention is provided between the metal oxide semiconductor film 2 and the electrode layer 3.
A spacer 7 may be interposed, the side surface may be sealed with resin or the like, and an electrolyte layer 4 in which an electrolyte is sealed between the electrodes may be provided for use. FIG. 2 is a schematic sectional view showing another embodiment of the photoelectric cell according to the present invention. In FIG.
It shows the same thing as FIG. 1, and 7 shows a spacer.

At this time, the spacer 7 is not particularly limited as long as it does not damage the metal oxide semiconductor film 2 and the electrode layer 3 and does not come into contact with each other. A spherical spacer, a rod-shaped spacer, or the like can be used. Conventionally known insulating particles made of a resin (plastic), an organic-inorganic composite, a metal oxide or ceramics can be used. When the spacer 7 is interposed, a photoelectric cell in which the distance between the metal oxide semiconductor film 2 and the electrode layer 3 is as small as about 1 to 50 μm can be suitably obtained.

As the resin spacer, Japanese Patent Publication 7-9
Resin particles disclosed in, for example, Japanese Patent No. 5165 and the like. As the spacer of the organic-inorganic composite, JP-A-7-17-1
Particles obtained by hydrolyzing metal alkoxides disclosed in Japanese Patent No. 40472, Japanese Patent Publication No. 8-25739 and the like can be suitably used.

As the spacers made of metal oxides or ceramics, spherical particles disclosed in JP-A-3-218915 and JP-B-7-64548 can be suitably used. Further, particles obtained by fusing a synthetic resin to the surface of each of the above-mentioned particles can also be suitably used. Such particles are described, for example, in JP-A-63-9422.
The resin-coated particles disclosed in JP-A No. 4 can be suitably used. In particular, particles coated with an adhesive resin are fixed by adhering to the metal oxide semiconductor film and / or the electrode layer, and can exhibit a uniform gap adjustment or a stress absorbing effect effectively without moving.

As the electrolyte, a mixture with at least one compound forming an oxidation-reduction system together with an electrochemically active salt is used. Examples of the electrochemically active salt include tetrapropylammonium iodide and the like.
Secondary ammonium salts. Compounds that form a redox system include quinone, hydroquinone, iodine (I ⁻ /
I ^- _3), potassium iodide, bromine _{^{(Br - / Br - 3)}} , potassium bromide, and the like. In some cases, these can be mixed and used.

The amount of use of such an electrolyte varies depending on the type of the electrolyte and the type of the solvent described later, but is generally about 0.1%.
Preferably it is in the range of 1 to 5 mol / l. Such an electrolyte is usually dissolved in a solvent and used as an electrolyte. As the solvent, a conventionally known solvent can be used. Specifically, water, alcohols, oligoethers, carbonates such as propion carbonate, phosphates, dimethylformamide, dimethylsulfoxide, N-methylpyrrolidone, N-vinylpyrrolidone, sulfur compounds of sulfolane 66, ethylene carbonate, acetonitrile , Γ-butyrolactone and the like.

In the present invention, the electrolyte layer 4 may further contain a liquid crystal. When liquid crystal is used, the light scattering effect of the liquid crystal makes it possible to stably convert light energy into electric energy and extract the light energy without significantly reducing the amount of received light even when the incident angle of light increases. Further, of the incident light, the light reflected by the semiconductor film as it is without exerting the excitation of the photosensitizer is again irradiated on the spectral sensitizing dye in the semiconductor film by the light scattering effect of the liquid crystal, and is converted into electric energy. The effect that the utilization rate of light energy is improved is obtained. Furthermore, when a liquid crystal having hydrophobicity is used as a liquid crystal, the hygroscopic effect is reduced as compared with a case where only an electrolyte having a hygroscopic property is used, so that deterioration due to decomposition of the electrolyte or the photosensitizer due to moisture absorption or decomposition of the solvent is suppressed. As a result, the effect of improving long-term stability is obtained.

The liquid crystal is not particularly limited as long as the photosensitizer has a low solubility so that the photosensitizer adsorbed on the semiconductor film does not desorb and dissolve, and a conventionally known liquid crystal is used. be able to. As such a liquid crystal, a smectic liquid crystal, a nematic liquid crystal, a cholesteric liquid crystal, and the like, which are conventionally known as a temperature transition type liquid crystal, can be used, and further, a concentration transition type liquid crystal, a polymer liquid crystal, a polymer dispersed liquid crystal, a discotic liquid crystal, and the like. Can be used. Among them, when a liquid crystal containing a fluorine atom is used, hydrophobicity is high and excellent in long-term stability.

The photovoltaic cell according to the present invention comprises a substrate 5 having an electrode layer 1 on the surface and a semiconductor film 2 having a photosensitizer adsorbed on the surface of the electrode layer 1, and a reduction catalyst on the surface. A substrate 6 having an electrode layer 3 having a function is arranged such that the metal oxide semiconductor film 2 and the electrode layer 3 face each other, and a spacer is interposed if necessary, and the side surface is sealed with a resin. Then, an electrolyte 4 is sealed between the metal oxide semiconductor film 2 and the transparent electrode layer 3, and the electrodes are connected by a lead wire.

In the photovoltaic cell according to the present invention, the metal oxide semiconductor film has a specific core-shell structure, and the volume resistivity of the core particles is specific to the volume of the metal oxide constituting the shell. It is formed from metal oxide particles having a higher resistance value. For this reason, electrons can be quickly transferred from the photosensitizer layer excited by absorbing light to the metal oxide semiconductor film, so that a photoelectric cell having excellent photoelectric conversion efficiency can be obtained.

[0061]

According to the present invention, the metal oxide semiconductor film is made of metal oxide particles having a core-shell structure, and the conductivity of the core particles is higher than the conductivity of the shell portion. The electrons generated in the photosensitizer layer excited by the absorption of light at the surface are quickly transferred to the core particles, and furthermore, the light is absorbed at the shell part so that the electrons can be transferred quickly from the metal oxide semiconductor film to the electrode film. The electrons generated in the photosensitizer layer excited by the excitation are less likely to stay in the shell portion or to move to the electrode film through the shell portion, so that the recombination of electrons is less likely to occur, so that the photoelectric conversion is difficult. A photoelectric cell with high conversion efficiency can be obtained.

[0062]

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

[0063]

Production Examples Metal oxide particles (A) to (E) and metal oxide particles (F) having a core-shell structure composed of a core particle and a shell portion shown in the table below,
(G) was prepared. Preparation of Metal Oxide (A) A solution was prepared by dissolving 57.7 g of tin chloride and 14.0 g of stannous fluoride in 100 g of methanol. The prepared solution was added to 1000 g of pure water with stirring at 90 ° C. for 4 hours to perform hydrolysis, and the formed precipitate was separated by filtration and washed,
Calcination was performed at 500 ° C. for 2 hours in dry air to obtain a tin oxide powder doped with fluorine. 30 g of this powder was added to 70 g of an aqueous potassium hydroxide solution (containing 3.0 g as KOH), and the mixture was pulverized with a sand mill for 3 hours while maintaining the mixture at 30 ° C. to prepare a sol. Then, the sol was treated with an ion exchange resin to remove alkali, and coarse particles were settled and removed with an ultracentrifuge to obtain a fluorine-doped tin oxide core particle dispersion. Ethyl cellosolve was added to this dispersion, and the solvent was replaced with a rotary evaporator to obtain an ethyl cellosolve dispersion of core particles composed of fluorine-doped tin oxide. Some of the particles at this time were dried and 500
C. for 2 hours, and the average particle size and conductivity were measured. Table 1 shows the results.

Next, ethylcellosolve was added to the fluorine-doped tin oxide core particle dispersion to prepare a 5% by weight core particle dispersion. To 100 g of this dispersion, acetylacetonate alkoxide titanium obtained by separately reacting 1.2 g of acetylacetone and 3.5 g of isopropoxytitanate was added, and the mixture was treated at a temperature of 80 ° C. to convert the core particles into a titanium hydrolyzate (water). (Titanium oxide), and 10 g of a hydrogen peroxide solution having a concentration of 36% by weight was added thereto.

To this, a separately prepared solution of peroxotitanic acid was added, and a quaternary ammonium hydroxide was further added to adjust the pH to 12, followed by treatment in an autoclave at 200 ° C. for 12 hours to obtain metal oxide particles ( A) was prepared. The average particle diameter of the obtained metal oxide particles (A) was measured, and the half of the difference between the average particle diameter of the metal oxide particles (A) and the average particle diameter of the core particles was determined as the film thickness of the shell part. And Table 1 shows the results.

Preparation of Peroxotitanic Acid Solution Titanium tetrachloride was diluted with pure water to obtain an aqueous solution of titanium tetrachloride containing 1.0% by weight in terms of TiO ₂ . While stirring the aqueous solution, aqueous ammonia having a concentration of 15% by weight was added to obtain a white slurry having a pH of 9.5. This slurry was filtered and washed to obtain a hydrated titanium oxide gel cake of 10.2% by weight in terms of TiO ₂ . 190 g of this cake and 670 g of a 5% strength hydrogen peroxide solution were mixed.
And dissolved by heating to prepare a solution of peroxotitanic acid.

Preparation of Metal Oxide (B) A solution obtained by dissolving 79.9 g of indium nitrate in 686 g of water and 12.7 g of potassium stannate at a concentration of 10% by weight
And a solution obtained by dissolving the same in a potassium hydroxide solution was prepared, and these solutions were added to 1000 g of pure water kept at 50 ° C. over 2 hours. During this time, the pH in the system was adjusted to 1
It was kept at 1. From the obtained Sn-doped indium oxide hydrate dispersion, the Sn-doped indium oxide hydrate was separated by filtration.
After washing, drying, firing in air at 350 ° C. for 3 hours, and firing in air at 600 ° C. for 2 hours to obtain Sn-doped indium oxide particles. This was dispersed in pure water so as to have a concentration of 30% by weight, and the pH was adjusted to 3.5 with an aqueous nitric acid solution.
A sol was prepared by grinding for 3 hours. Next, the sol was treated with an ion exchange resin to remove nitrate ions, and coarse particles were settled and removed by an ultracentrifuge to obtain a tin-doped indium oxide core particle dispersion. Ethyl cellosolve was added to this dispersion, and the solvent was replaced with a rotary evaporator to obtain an ethyl cellosolve dispersion composed of tin-doped indium oxide core particles. Some of the particles at this time were dried and fired at 500 ° C. for 2 hours, and the average particle diameter and the conductivity were measured. Table 1 shows the results.

Then, ethyl cellosolve was added to the tin-doped indium oxide core particle dispersion to prepare a core particle dispersion having a concentration of 5% by weight. 300 g of this dispersion
Then, acetylacetonate alkoxide titanium obtained by separately reacting 1.2 g of acetylacetone and 3.5 g of isopropoxytitanate is added, and the mixture is treated at a temperature of 80 ° C. to make the core particles a hydrolyzate of titanium (titanium hydroxide). After coating, 10 g of a hydrogen peroxide solution having a concentration of 36% by weight was added thereto, followed by further heat treatment.

To this, a separately prepared solution of peroxotitanic acid was added, and a quaternary ammonium hydroxide was further added to adjust the pH to 12, followed by treatment in an autoclave at 200 ° C. for 12 hours to obtain metal oxide particles ( B) was prepared. The average particle diameter and the film thickness of the obtained metal oxide particles (B) were determined. Table 1 shows the results.

Preparation of Metal Oxide Particles (C) In the same manner as in the metal oxide particles (B), ethyl cellosolve was added to a tin-doped indium oxide core particle dispersion to obtain a core particle having a concentration of 5% by weight. A dispersion was prepared. To 100 g of this dispersion, acetyl acetone 1.
Titanium acetylacetonate alkoxide obtained by reacting 2 g with 3.5 g of isopropoxy titanate was added, and the mixture was treated at a temperature of 80 ° C. to coat the core particles with a hydrolyzate of titanium (titanium hydroxide). 10 g of a 36% by weight aqueous hydrogen peroxide solution was added, followed by further heat treatment.

To this solution, a separately prepared solution of peroxotitanic acid was added, and quaternary ammonium hydroxide was further added to adjust the pH to 12, and then treated with an autoclave at 200 ° C. for 12 hours to obtain metal oxide particles ( C) was prepared. The average particle diameter and film thickness of the obtained metal oxide particles (C) were determined. Table 1 shows the results.

Preparation of Metal Oxide Particles (D) In the same manner as for the metal oxide particles (B), ethyl cellosolve was added to the tin-doped indium oxide core particle dispersion to obtain a core particle having a concentration of 5% by weight. A dispersion was prepared. To 50 g of this dispersion, separately add 0.6 of acetylacetone.
g and 1.75 g of isopropoxy titanate were added to each other, and titanium acetylacetonate alkoxide was added thereto. The mixture was treated at a temperature of 80 ° C. to coat the core particles with a hydrolyzate of titanium (titanium hydroxide). 5 g of a 36% by weight aqueous hydrogen peroxide solution was added, followed by further heat treatment.

To this, a separately prepared solution of peroxotitanic acid was added, and a quaternary ammonium hydroxide was further added to adjust the pH to 12, followed by treatment in an autoclave at 200 ° C. for 12 hours to obtain metal oxide particles ( D) was prepared. The average particle diameter and the film thickness of the obtained metal oxide particles (D) were determined. Table 1 shows the results.

Preparation of Metal Oxide (E) 136 g of zinc chloride and 10 g of aluminum chloride 100 g of pure water
Dissolved in 0 g. The solution was kept at 50 ° C. for 30 minutes.
It was added to 00 g of pure water over 2 hours. During this time, the pH in the system was maintained at 9.0. The Al-doped zinc oxide hydrate dispersion was filtered, washed and dried from the obtained Al-doped zinc oxide hydrate dispersion, and then dried at 350 ° C. in air.
After sintering for 2 hours and further in air at 700 ° C. for 2 hours, Al-doped zinc oxide particles were obtained. This was dispersed in diacetone alcohol to a concentration of 30% by weight, and the dispersion was pulverized with a sand mill for 3 hours while maintaining the dispersion at 30 ° C. to prepare a sol. Next, the sol was removed by sedimentation of coarse particles with an ultracentrifuge.
To obtain a zinc oxide core particle dispersion. Some of the particles at this time were dried and fired at 500 ° C. for 2 hours, and the average particle diameter and the conductivity were measured. Table 1 shows the results.

Next, diacetone alcohol was added to the Al-doped zinc oxide particle dispersion to prepare a core particle dispersion having a concentration of 5% by weight. To 100 g of this dispersion, 1.2 g of acetylacetone and 3.5 g of isopropoxytitanate were separately added.
Was added, and the mixture was treated at a temperature of 80 ° C. to coat the core particles with a hydrolyzate of titanium (titanium hydroxide).
10 g of a 6% by weight aqueous hydrogen peroxide solution was added, followed by further heat treatment.

To this, a separately prepared solution of peroxotitanic acid was added, and a quaternary ammonium hydroxide was further added to adjust the pH to 12, followed by treatment in an autoclave at 200 ° C. for 12 hours to obtain metal oxide particles ( E) was prepared. The average particle diameter and the film thickness of the obtained metal oxide particles (E) were determined. Table 1 shows the results.

Preparation of Metal Oxide (F) 18.3 g of titanium tetrachloride was diluted with pure water to obtain an aqueous solution containing 1.0% by weight in terms of TiO ₂ . While stirring the aqueous solution, aqueous ammonia having a concentration of 15% by weight was added to obtain a white slurry having a pH of 9.5. This slurry was filtered and washed to obtain a hydrated titanium oxide gel cake of 10.2% by weight in terms of TiO ₂ . This cake was mixed with 400 g of a 5% strength hydrogen peroxide solution, and then heated to 80 ° C. to dissolve to prepare a peroxotitanic acid solution.

To this, concentrated aqueous ammonia was added to adjust the pH to 1.
It was adjusted to 0, placed in an autoclave, and subjected to hydrothermal treatment at 250 ° C. for 8 hours under a saturated vapor pressure to prepare titania colloid particles (F). The obtained particles were anatase-type titanium oxide having high crystallinity by X-ray diffraction, and had an average particle size of 40 nm. Preparation of Metal Oxide (G) As a core particle dispersion, silica sol (catalyst SI-30P, manufactured by Catalyst Chemical Industry Co., Ltd., average particle diameter 30 n)
m, an aqueous sol having a concentration of 30% by weight), ethylcellosolve was added to the sol, and the solvent was replaced with a rotary evaporator to obtain an ethylcellosolve dispersion of silica core particles.

Next, ethylcellosolve was added to the silica core particle dispersion to prepare a core particle dispersion having a concentration of 5% by weight. To 100 g of this dispersion, acetylacetonate alkoxide titanium obtained by separately reacting 1.2 g of acetylacetone and 3.5 g of isopropoxytitanate was added, and the mixture was treated at a temperature of 80 ° C. to convert the core particles into a titanium hydrolyzate (water). (Titanium oxide) and a concentration of 36% by weight
Was added and 10 g of hydrogen peroxide solution was added thereto, followed by further heat treatment.

To this, a separately prepared solution of peroxotitanic acid was added, and quaternary ammonium hydroxide was further added to adjust the pH to 12, and then treated with an autoclave at 200 ° C. for 12 hours to obtain metal oxide particles ( G) was prepared. The average particle diameter and the film thickness of the obtained metal oxide particles (G) were determined. Table 1 shows the results.

[0081]

Example 1 Formation of Metal Oxide Semiconductor Film The metal oxide particles (A) obtained in Reference Example were concentrated to a concentration of 10%, and the peroxotitanic acid solution was mixed with the peroxotitanic acid solution and the metal oxide particles. The mixture was mixed so that the weight ratio in terms of oxide (peroxotitanic acid / metal oxide particles) was 0.1, and hydroxy was used as a film-forming auxiliary so as to be 30% by weight of the total oxide weight in the mixture. Propyl cellulose was added to prepare a coating solution for forming a semiconductor film.

Next, the above-mentioned coating solution was applied to a transparent glass substrate on which fluorine-doped tin oxide was formed as an electrode layer, air-dried, and then dried using a low-pressure mercury lamp.
Ultraviolet rays of 000 mJ / cm ² were irradiated to decompose peroxoacid, and the coating film was cured. The coating film was heated at 300 ° C. for 30 minutes to decompose and anneal hydroxypropylcellulose to form a metal oxide semiconductor film (A).

Table 1 shows the thickness of the obtained metal oxide semiconductor film (A), the pore volume and the average pore diameter determined by the nitrogen adsorption method. Adsorption of photosensitizer Next, as photosensitizer cis - (SCN ^-) - bis (2,2'-bipyridyl-4,4'-dicarboxylate) ruthenium (II) represented in the ruthenium complex is An ethanol solution having a concentration of 3 × 10 ⁻⁴ mol / liter was prepared. This photosensitizer solution is
It was applied onto the metal oxide semiconductor film (A) using an rpm100 spinner and dried. This coating and drying process was performed five times. Table 1 shows the adsorption amount of the photosensitizer in the obtained metal oxide semiconductor film.

Preparation of Photoelectric Cell A mixture of acetonitrile and ethylene carbonate in a volume ratio (acetonitrile: ethylene carbonate) of 1: 4 was mixed with tetrapropylammonium iodide at 0.46 mol / l and iodine at 0.40 mol / l. It mixed so that it might be set to 06 mol / l, and the electrolyte solution was prepared.

The electrode prepared above was used as one electrode, and the other electrode was formed of fluorine-doped tin oxide as an electrode. A transparent glass substrate carrying platinum was placed on the electrode, and the side was made of resin. Then, the above-mentioned electrolyte solution (A) was sealed between the electrodes, and the electrodes were connected with a lead wire to form a photoelectric cell (A). The photoelectric cell (A) is irradiated with light of 100 W / m ² intensity at an incident angle of 90 ° (90 ° with respect to the cell surface) by a solar simulator, and Voc (voltage in an open circuit state) and Joc (short circuit) Density, current factor, FF (fill factor) and η
(Conversion efficiency) was measured.

Table 1 shows the results.

[0087]

Examples 2 to 5 Photovoltaic cells were produced in the same manner as in Example 1 except that metal oxide particles (B) to (E) described in Reference Examples were used instead of metal oxide particles (A). (B) ~
(E) was prepared, and the same evaluation as in Example 1 was performed. Table 1 shows the results.

[0088]

Comparative Examples 1 and 2 A photoelectric cell was prepared in the same manner as in Example 1 except that the metal oxide particles (F) and (G) described in Reference Example were used instead of the metal oxide particles (A). (F) and (G) were prepared, and the same evaluation as in Example 1 was performed. Table 1 shows the results.

[0089]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one embodiment of a photoelectric cell according to the present invention.

FIG. 2 is a schematic sectional view showing another embodiment of the photoelectric cell according to the present invention.

[Description of Signs] 1 ... Transparent electrode layer 2 ... Semiconductor film with photosensitizer adsorbed 3 ... Electrode layer 4 ... ······ Electrolyte 5, 6 ····· Substrate 7 ········· Spacer

Claims (4)

[Claims] An electrode layer (1) is provided on the surface, and said electrode layer (1)
A substrate on which a metal oxide semiconductor film (2) having a photosensitizer adsorbed thereon is formed, and a substrate having an electrode layer (3) on the surface, the metal oxide semiconductor film (2) and the electrode layer (3) are arranged so as to face each other, in a photoelectric cell comprising an electrolyte layer provided between the metal oxide semiconductor film (2) and the electrode layer (3), (i) a metal oxide semiconductor film (2) has an average particle size of 5 to 600
(ii) the metal oxide particles have a core-shell structure consisting of core particles and a shell formed on the surface of the core particles; ) The average particle diameter of the core particles is in the range of 2 to 500 nm, the thickness of the shell portion is in the range of 1 to 150 nm, and (iv) the volume resistivity of the metal oxide constituting the core particles.
A photovoltaic cell, wherein (E _c ) and the volume resistivity (E _s ) of the metal oxide constituting the shell part satisfy a relationship represented by E _c <E _s . 2. The photovoltaic cell according to claim 1, wherein the shell of the metal oxide particles is made of crystalline titanium oxide. 3. The photovoltaic cell according to claim 1, wherein said crystalline titanium oxide is obtained by heating and aging peroxotitanic acid. 4. The photovoltaic cell according to claim 1, wherein said metal oxide semiconductor film is made of a titanium oxide binder together with metal oxide particles.