JP2001102104A - Photoelectric conversion device and photoelectric cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion device of high energy conversion rate, and a photoelectric cell using the same. SOLUTION: A photoelectric conversion device comprises at least a photosensitive semiconductor layer, charge transfer layer, opposite electrode, and an electrically insulating spacer layer between the semiconductor layer and opposite layer. Additionally deposited over the opposite electrode is a porous electron- conductive layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photoelectric conversion device using a semiconductor, and more particularly to a photoelectric conversion device sensitized by a dye. Furthermore, the present invention relates to a photovoltaic cell using the same.

[0002]

2. Description of the Related Art At present, photovoltaic power generation is the main technology for practical use in which monocrystalline silicon solar cells, polycrystalline silicon solar cells, amorphous silicon solar cells, and compound solar cells such as cadmium telluride and indium copper selenide are improved. The power generation efficiency of about 10% is obtained as the solar energy conversion efficiency. However, in order to popularize these materials in the future, it is necessary to overcome the problems that the energy cost for material production is high, the environmental load for commercialization is large, and the energy payback time is long for users. For this reason, many solar cells that use organic materials that can easily be increased in area and used as photosensitive materials in place of silicon have been proposed so far in order to reduce costs,
There is a problem that the energy conversion efficiency is as low as 1% or less and the durability is poor. Under these circumstances, Nature (No. 35)
3, 737-740, 1991) and U.S. Pat. No. 4,492,721 disclose a photoelectric conversion element and a solar cell using semiconductor fine particles sensitized by a dye, and materials and manufacturing techniques required for the production thereof. Was done. The proposed battery is
This is a wet solar cell using a titanium dioxide porous thin film spectrally sensitized by a ruthenium complex as a working electrode. The first advantage of this method is that an inexpensive oxide semiconductor such as titanium dioxide can be used without having to purify it to high purity, and therefore it can be provided as an inexpensive photoelectric conversion element. Dye absorption is broad, and sunlight can be converted into electricity over a wide visible light wavelength range. Third, energy conversion efficiency is 1 under optimum conditions.
This is as high as nearly 0%. However, for practical use as a solar cell, improvement of the durability of the charge transfer layer has been an important issue. In the initial investigation, an organic solvent solution of a redox compound was used as the charge transfer layer. However, in these devices, there was a problem that the organic solvent was scattered and the performance was greatly deteriorated. To solve this problem, the use of a molten salt or a solid charge transporting material that maintains a liquid state at room temperature has been considered.However, in these charge transfer layers, the charge transfer tends to be slow, so How to reduce the thickness was an important technical issue.

In a conventional element, a short circuit caused by direct contact between an oxide semiconductor layer and a counter electrode is prevented by interposing a spacer between a support supporting semiconductor fine particles and a support supporting a counter electrode via a spacer. Was common. However, if a large cell is to be produced by this method, both supports need to be made of a highly planar and rigid material, and it is difficult to keep the thickness of the charge transfer layer constant over the entire area. However, there has been a problem that the performance of the battery is deteriorated due to a decrease in battery performance or a change in thickness due to aging. Further, in the conventional method, it is difficult to form a thin spacer, and it is substantially difficult to obtain a material having a thickness of about ten and several μm.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photoelectric conversion element and a photovoltaic cell having excellent energy conversion efficiency.

[0005]

The object of the present invention has been attained by the following items which specify the present invention and preferred embodiments thereof. (1) In a photoelectric conversion element having at least a photosensitive semiconductor film, a charge transfer layer, and a counter electrode, a substantially electrically insulating spacer layer is provided between the semiconductor film and the counter electrode, and the counter electrode is porous. A photoelectric conversion element comprising an electron conductive layer of (2) The photoelectric conversion element according to (1), wherein the porous electron conductive layer is provided adjacent to the spacer layer. (3) The photoelectric conversion element according to (1) or (2), wherein the porous electron conductive layer is formed by binding conductive fine particles. (4) The photoelectric conversion element according to (3), wherein the conductive fine particles are platinum black or carbon fine particles carrying platinum. (5) The photoelectric conversion element according to any one of (1) to (4), wherein the counter electrode has a configuration in which the porous electron conductive layer is provided on a conductive substrate. (6) The photoelectric conversion element according to any one of (1) to (5), wherein the spacer layer is a porous layer formed by binding insulating fine particles. (7) The photoelectric conversion element according to (6), wherein the insulating fine particles of the spacer layer are made of an oxide containing at least one element selected from aluminum, silicon, boron and phosphorus. (8) The photoelectric conversion element according to (6), wherein the insulating fine particles of the spacer layer are made of an organic polymer. (9) The photoelectric conversion element according to any one of (1) to (8), wherein the photosensitive semiconductor film contains titanium dioxide. (10) The photoelectric conversion element according to any one of (1) to (9), wherein the photosensitive semiconductor film is sensitized by a dye. (11) The photoelectric conversion element according to any one of (1) to (10), wherein the charge transfer layer contains a molten salt. (12) A photovoltaic cell using the photoelectric conversion element according to any of (1) to (11).

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. First, the configurations and materials of the photoelectric conversion element and the photovoltaic cell of the present invention are described in detail. In the present invention, the photoelectric conversion element includes a photoelectrode comprising a semiconductor film (photosensitive layer) provided on a conductive support, a counter electrode, and a charge transfer layer electrically contacting the photoelectrode and the counter electrode and joining them. Take a laminated configuration. The semiconductor film is sensitized by a dye as necessary, and this is called a dye-sensitized semiconductor film. The conductive support provided with the dye-sensitized semiconductor film is a working electrode in the photoelectric conversion element and functions as a photoanode. This photoelectric conversion element is a photovoltaic cell that generates a current and an electromotive force in an external circuit under irradiation of light from a working electrode, and is characterized as an electrochemical photovoltaic cell when the charge transfer layer is an ion-conductive electrolyte. The semiconductor layer as the photosensitive layer is designed according to the purpose, and may have a single-layer structure or a multilayer structure. In the case of a dye-sensitized photosensitive layer, light incident on the photosensitive layer is absorbed by the dye and excites dye molecules. The dye molecules in the excited state inject excited electrons with high energy into the conduction band of the semiconductor fine particles, and the injected conductor electrons diffuse through the semiconductor bulk and reach the counter electrode. The electron-injected dye molecule becomes an oxidized form having an electron deficiency, and is electronically reduced and regenerated by an electron donor in the charge transporting material in contact with the dye. In other words, the excited electrons received on the conductive support perform electrical work in an external circuit and are transmitted to the counter electrode, return to the dye oxidant via the charge transport material of the charge transfer layer, and regenerate the dye. Although the present invention has a layer structure,
At the contact portion of each layer (for example, at the boundary between the conductive layer and the photosensitive layer of the conductive support, at the boundary between the photosensitive layer and the charge transfer layer, or at the boundary between the charge transfer layer and the counter electrode), the material or compound constituting the layer is used. And the ions may be in a state of being diffused and mixed with each other.

According to the present invention, the semiconductor film and the counter electrode are electrochemically connected to each other through a thin charge transfer layer without short-circuiting. And a counter electrode having a porous electron conductive layer. In the present invention, it is necessary that the charge transporting material penetrates into the spacer layer and the electron conductive layer, and more preferably, penetrates into the semiconductor film. In this case, there is no need for a clear single charge transfer layer.

The spacer layer may have spacers intermittently arranged, but is preferably a continuous porous film, and particularly preferably a porous layer made of insulating fine particles. The preferred thickness of the spacer layer is 0.05 μm
〜１０10 μm. As the substantially electrically insulating particles used in the spacer layer of the present invention, a substance having an electric conductivity of 10 ⁻³ Siemens / cm or less and a substance that is inactive with respect to the components forming the charge transfer layer is used. If any, any one is used. One such material is an oxide,
Either amorphous oxide glass or crystalline oxide can be used. A specific example of a preferred oxide glass material is an oxide glass containing at least one element selected from aluminum, silicon, boron and phosphorus. Further, a specific example of a preferable crystalline oxide is aluminum oxide.

A more preferred oxide glass is a glass containing at least one of silicon, boron and phosphorus and having a softening point of 700 ° C. or less. For example, the following compositions may be mentioned, but the present invention is not limited thereto. _{Na 0.2 B 0.4 P 0.4 O X} Rb 0.2 B 0.4 P 0.4 O X Pb 0.2 B 0.25 Si 0.25 O X Pb 0.2 Zn 0.1 BO X

As another electrically insulating particle, there can be mentioned a particle composed of an organic polymer. As the organic polymer material forming the particles, any material can be used as long as it is a material that is inert to the components forming the charge transfer layer. Examples of preferred organic polymers include polymethyl methacrylate, polyethylene, polystyrene, polypropylene, and polyvinylidene difluoride.

The above-mentioned insulating particles have a particle diameter of 5 to 1000 times that of semiconductor fine particles used for an electrode described later,
Preferably it is 20 to 500 times.

[0012] The porous electron conductive layer of the present invention is a conductive and porous material, is a material which is inert to the components constituting the charge transfer layer, and has a high speed between the layer and the charge transfer layer. Any material can be used as long as it can transfer electrons. Preferred materials having such properties include A
u, Pt, carbon (graphite, carbon black, acetylene black, coke, carbon fiber, graphitized carbon microbeads, etc.) and the like. Further, the porous electron conductive layer is preferably formed by binding conductive fine particles. As the conductive fine particles, in addition to the fine particles of the above-described materials (particularly, platinum black), particles obtained by plating the surfaces of substantially electrically insulating particles with Au or Pt to impart electron conductivity, or the above-described particles. Particles in which Pt is partially supported on carbon particles (particularly graphite) to improve the electron transfer speed are preferably used. Further, a foamed metal can also be used. The preferred thickness of the porous electron conductive layer is 0.1 μm to 100 μm, and more preferably 0.5 μm to 30 μm.

Next, the photoelectrode of the photoelectric conversion element will be described. The semiconductor material used for the photoelectrode in the present invention is a material that generates conductivity when excited by absorption of light energy or the like, has a valence band and a conduction band as energy levels, and has a wavelength corresponding to a band gap. Excitation by light produces conduction band electrons and valence band holes. At this time, the conduction band electrons serve as carriers in the n-type semiconductor, and the holes serve as carriers in the p-type semiconductor, thereby generating conductivity. The semiconductor used for dye sensitization in the present invention is preferably an n-type semiconductor that gives an anode current by using conduction band electrons as carriers under photoexcitation. An n-type semiconductor generates an anodic rectified current when it generates conduction band excited electrons while the electrode is anodic polarized (positively polarized). Also,
Semiconductors having a carrier concentration related to conduction in the range of 10 ¹⁴ to 10 ²⁰ / cm ³ are preferable. In the dye-sensitized semiconductor of the present invention, light absorption and the resulting generation of excited electrons and holes mainly occur in dye molecules, and the semiconductor receives the excited electrons in the conduction band and transmits them to the electrode of the support. Carry. The mechanism of dye sensitization of such a semiconductor electrode related to the present invention is described in Kenichi Honda, Akira Fujishima, Chemical Review No. 7, p77 (1976), Tadashi Watanabe, Takuro Takizawa, Kenichi Honda, Catalyst, 20, p370 (1978) ).

Examples of the semiconductor include simple semiconductors such as silicon and germanium, III-V compound semiconductors, metal chalcogenides (eg, oxides, sulfides, selenides, etc.),
Alternatively, a compound having a perovskite structure (for example, strontium titanate, calcium titanate, sodium titanate, barium titanate, potassium niobate, or the like) can be used.

Preferred metal chalcogenides include titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium or tantalum oxide, cadmium, zinc, lead and silver. , Antimony or bismuth sulfide, cadmium or lead selenide, cadmium telluride and the like. Other compound semiconductors include phosphides such as zinc, gallium, indium and cadmium, selenides of gallium-arsenic or copper-indium, and sulfides of copper-indium.

More preferably, the semiconductor used in the present invention is specifically Si, TiO ₂ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , Zn
O, Nb ₂ O ₅ , CdS, ZnS, PbS, Bi ₂ S ₃ , CdSe, CdTe, GaP, I
nP, GaAs, CuInS ₂ and CuInSe ₂ are mentioned. More preferably _{TiO 2, ZnO, SnO 2,} Fe 2 O 3, WO 3, Nb 2 O 5, CdS, Pb
S, CdSe, InP, GaAs, a CuInS _2, CuInSe _2, particularly preferably a TiO ₂ or Nb ₂ O _5, and most preferably TiO
₂

The semiconductor used in the present invention may be single crystal or polycrystal. Although a single crystal is preferable as the conversion efficiency, a polycrystal is preferable in terms of manufacturing cost, securing of raw materials, energy payback time, and the like, and a fine particle semiconductor having a nanometer to micrometer size is particularly preferable.

The particle diameter of these semiconductor fine particles is preferably 5 to 200 nm as a primary particle as an average particle diameter using the diameter when the projected area is converted into a circle, and particularly preferably 8 to 1 nm.
Preferably it is 00 nm. The average particle size of the semiconductor fine particles (secondary particles) in the dispersion is 0.01 to 10
It is preferably 0 μm.

Further, two or more kinds of fine particles having different particle size distributions may be mixed and used. In this case, the average size of the small particles is preferably 5 nm or less. Also, in order to improve the light capture rate by scattering incident light,
Semiconductor particles having a large particle size, for example, about 300 nm may be mixed.

The method for producing semiconductor fine particles is described in Sol-gel described in "Sol-gel method science" by Agaku Shofusha (1988) by Sakuhana Sakubana, "Thin-film coating technology by sol-gel method" (1995) by Technical Information Association. Tadao Sugimoto, "Synthesis of Monodisperse Particles by New Synthetic Gel-Sol Method and Size Morphology Control" Materia, Vol. 35, No. 9, 1012
The gel-sol method described on pages 10 to 1018 (1996) is preferred.

It is also preferable to use a method developed by Degussa to produce an oxide by hydrolyzing a chloride in an oxyhydrogen flame at a high temperature.

In the case of titanium oxide, the above-mentioned sol-gel method, gel-sol method, and high-temperature hydrolysis method of chloride in an oxyhydrogen flame are all preferable, but furthermore, Manabu Kiyono's "Titanium oxide physical properties and applied technology", published by Gihodo ( 1997) can also be used.

In the case of titanium oxide, among the sol-gel methods described above, in particular, "Journal of American
Ceramic Society Vol. 80, No. 12, 31
Pages 57 to 3171 (1997) "and Burnside et al.," Chemical Materials Vol. 10, No. 9, pages 2419 to 2425 "
The described method is preferred.

Titanium oxide mainly has two types of crystal forms, anatase type and rutile type. Depending on the production method and thermal history, any type can be used, and often it is obtained as a mixture of both. The titanium oxide of the present invention preferably has a high anatase content, more preferably 80% or more. Anatase has a shorter long-wavelength wavelength of light absorption than rutile, and has less damage to the photoelectric conversion element due to ultraviolet rays. The anatase content can be determined by the X-ray diffraction method, and can be determined from the ratio of the diffraction peak intensities derived from anatase and rutile.

In the device of the present invention, the conductive support serving as the substrate of the semiconductor layer is substantially transparent. Substantially transparent means that the transmittance of light (visible light range of 400 to 900 nm) is 10% or more,
It is preferably at least 50%, particularly preferably at least 70%.

As the substantially transparent conductive support, a glass or plastic support having on its surface a conductive layer containing a conductive agent (conductive agent layer) can be used.
Preferred conductive agents include metals (eg, platinum, gold, silver,
Thin films of copper, aluminum, rhodium, indium, etc.)
Examples thereof include a carbon thin film and a conductive metal oxide (indium-tin composite oxide (ITO), tin oxide doped with fluorine, and the like). The thickness of the conductive agent layer is preferably about 0.02 to 10 μm within a substantially transparent range.

The lower the surface resistance of the conductive support, the better. The preferred range of the surface resistance is 100 Ω / □ or less, and more preferably 40 Ω / □ or less. The lower limit is not particularly limited, but is usually about 0.1 Ω / □.

The transparent conductive support is preferably made of glass or plastic coated with a conductive metal oxide. Of these, conductive glass in which a conductive layer made of tin dioxide doped with fluorine is deposited on a transparent substrate made of low-cost soda-lime float glass is particularly preferable. In addition, for a low-cost and flexible photoelectric conversion element or photovoltaic cell, a transparent polymer film provided with the above conductive layer is preferably used. Transparent polymer films include tetraacetyl cellulose (TAC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and syndioctatic polysterene (SP
S), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate (PAr), polysulfone (PSF), polyester sulfone (PE)
S), polyetherimide (PEI), cyclic polyolefin, brominated phenoxy and the like. When a transparent conductive support is used, it is preferable that light is incident from the support side. In this case, the coating amount of the conductive metal oxide is 0.01 to 1 m ² per glass or plastic support.
100 g is preferred.

A metal lead may be used for the purpose of lowering the resistance of the transparent conductive substrate. The material of the metal lead is preferably a metal such as aluminum, copper, silver, gold, platinum and nickel,
Particularly, aluminum and silver are preferable. It is preferable that the metal lead is provided on a transparent substrate by vapor deposition, sputtering, or the like, and a transparent conductive layer made of tin oxide doped with fluorine or an ITO film is provided thereon. It is also preferable to provide a metal lead on the transparent conductive layer after providing the transparent conductive layer on a transparent substrate. The decrease in the amount of incident light due to the installation of the metal leads is 1 to 10%, more preferably 1 to 5%.

Examples of the method of applying the semiconductor fine particles on the conductive support include a method of applying a dispersion or a colloid solution of the semiconductor fine particles on the conductive support, and the above-mentioned sol-gel method. In consideration of mass production of photoelectric conversion elements, liquid physical properties, and flexibility of a support, a wet film forming method is relatively advantageous. As a wet type film applying method, a coating method and a printing method are typical.

As a method for preparing a dispersion of semiconductor fine particles, in addition to the above-mentioned sol-gel method, a method of grinding in a mortar, a method of dispersing while pulverizing using a mill, or a method of synthesizing a semiconductor in a solvent when synthesizing a semiconductor. A method of precipitating it as fine particles and using it as it is may be mentioned. Examples of the dispersion medium include water and various organic solvents (eg, methanol, ethanol, isopropyl alcohol, dichloromethane, acetone, acetonitrile, ethyl acetate, etc.). When dispersing,
If necessary, a polymer, a surfactant, an acid, a chelating agent or the like may be used as a dispersing aid.

As a coating method, a roller method, a dipping method as an application system, an air knife method, a blade method, etc. as a metering system.
No. 4,589,294, U.S. Pat. No. 2,761,419, and U.S. Pat.
A slide hopper method, an extrusion method, a curtain method and the like described in US Pat. As a general-purpose machine, a spin method or a spray method is also preferably used.

As the wet printing method, three types of printing methods, namely, relief printing, offset printing and gravure printing, intaglio printing, rubber printing, and screen printing have been conventionally preferred.

From the above methods, a preferred film forming method is selected according to the liquid viscosity and the wet thickness.

The liquid viscosity is greatly affected by the type and dispersibility of the semiconductor fine particles, the type of solvent used, and additives such as a surfactant and a binder. High viscosity liquid (for example, 0.01 to 500 Po
In ise), an extrusion method or a casting method is preferable, and in a low-viscosity liquid (for example, 0.1 Poise or less), a slide hopper method, a wire bar method, or a spin method is preferable, and a uniform film can be formed.

Incidentally, even in the case of applying a low-viscosity liquid by the extrusion method, the application is possible if the applied amount is a certain amount.

Screen printing is often used for applying a high-viscosity paste of semiconductor fine particles, and this method can also be used.

As described above, a method of applying a wet film may be appropriately selected according to parameters such as the liquid viscosity of the coating liquid, the coating amount, the support, and the coating speed.

Further, the layer containing semiconductor fine particles need not be limited to a single layer. It is also possible to apply a multi-layer coating of dispersion liquids having different particle diameters, and different types of semiconductors.
Alternatively, multi-layer coating of coating layers having different compositions of binders and additives can be performed, and multi-layer coating is effective even when the film thickness is insufficient by one-time coating. The extrusion method or the slide hopper method is suitable for multilayer coating. In the case of multi-layer coating, multi-layer coating may be performed at the same time, or several to dozens of times may be sequentially applied. Furthermore, a screen printing method can also be preferably used in the case of successive coating.

In general, as the thickness of the layer containing semiconductor fine particles increases, the amount of dye carried per unit projected area increases, so that the light capture rate increases. However, the diffusion distance of the generated electrons increases, and the loss due to charge recombination also increases. growing. Therefore, the semiconductor fine particle-containing layer has a preferable thickness, but typically has a thickness of 0.1 to 100 μm. When used as a photovoltaic cell, the thickness is preferably 1 to 30 μm,
It is more preferable that the thickness be 25 μm. The coating amount per support 1 m ² of the semiconductor fine particles 0.5～400G, more 5~100g is preferred.

The semiconductor fine particles are preferably subjected to a heat treatment in order to bring the particles into electronic contact after being applied to the conductive support, and to improve the strength of the coating film and the adhesion to the support. The preferred range of the heat treatment temperature is 40 ° C. or more and less than 700 ° C., more preferably 1 ° C.
It is not less than 00 ° C and not more than 600 ° C. The heat treatment time is 1
It is about 0 minutes to 10 hours. When a support having a low melting point or softening point, such as a polymer film, is used, high-temperature treatment is not preferable because it causes deterioration of the support. It is preferable that the temperature is as low as possible from the viewpoint of cost. The lowering of the temperature can be achieved by the above-mentioned combination of small semiconductor particles of 5 nm or less, heat treatment in the presence of a mineral acid, and the like.

After the heat treatment, chemical plating using, for example, an aqueous solution of titanium tetrachloride for the purpose of increasing the surface area of the semiconductor particles, increasing the purity in the vicinity of the semiconductor particles, and increasing the efficiency of electron injection from the dye into the semiconductor particles. Alternatively, electrochemical plating using an aqueous solution of titanium trichloride may be performed.

It is preferable that the semiconductor fine particles have a large surface area so that many dyes can be adsorbed. Therefore, the surface area when the semiconductor fine particle layer is coated on the support is preferably at least 10 times, more preferably at least 100 times the projected area. The upper limit is not particularly limited, but is usually about 1000 times.

The dye used in the present invention is preferably a metal complex dye or a methine dye. In the present invention, two or more dyes can be mixed in order to widen the wavelength range of photoelectric conversion as much as possible and to increase the conversion efficiency. Dyes to be mixed and their proportions can be selected so as to match the wavelength range and intensity distribution of the target light source. These dyes are suitably linked to the surface of the semiconductor fine particles (interlocki).
ng group). Preferred linking groups include OH, COOH, SO ₃ H, cyano, -P (O)
(OH) ₂ groups, —OP (O) (OH) ₂ groups, or chelating groups having π conductivity such as oximes, dioximes, hydroxyquinolines, salicylates and α-keto enolates. Among them, COOH group, -P (O) (OH) ₂ group, -OP (O) (O
H) _Two groups are particularly preferred. These groups may form a salt with an alkali metal or the like, or may form an inner salt. In the case of a polymethine dye, if the methine chain contains an acidic group as in the case of forming a squarylium ring or a croconium ring, this portion may be used as a bonding group.

The dyes preferably used in the present invention will be specifically described below. When the dye used in the present invention is a metal complex dye, a ruthenium complex dye is preferable, and a dye represented by the following formula (I) is more preferable. Wherein _{(I) (A 1) p} RuB a B b B c formula (I), p is 0 to 2, preferably 2.
Ru represents ruthenium. A ₁ is Cl, SCN, H ₂ O,
A ligand selected from Br, I, CN, NCO, and SeCN. B _a, B _b, B _c is an organic ligand selected from the following B-1 to B-8 independently.

[0046]

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Here, _Ra is a hydrogen atom, a halogen atom,
A substituted or unsubstituted alkyl group having 1 to 12 carbon atoms (hereinafter referred to as C number), an aralkyl group substituted or unsubstituted with 7 to 12 carbon atoms, or a substituted or unsubstituted with 6 to 12 carbon atoms Represents an aryl group. The above alkyl group,
The alkyl portion of the aralkyl group may be linear or branched, and the aryl portion of the aralkyl group may be monocyclic or polycyclic (condensed ring, ring assembly). .

Specific ruthenium complex dyes for use in the present invention include, for example, US Pat.
No. 5084365, No. 5350644, No. 5463057, No. 55254
No. 40, JP-A-7-249790, JP-T10-504521 and WO9
The complex dyes described in each specification of 8/50393 are exemplified.

Preferred specific examples of the metal complex dye used in the present invention are shown below, but the present invention is not limited to these.

[0050]

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[0051]

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[0052]

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The methine dyes preferably used in the present invention are described in JP-A-11-35836 and JP-A-11-1583.
No. 95, JP-A-11-163378, JP-A-11-2
No. 14730, JP-A-11-214731, European Patents 892411 and 911841.

The method of adsorbing the dye on the semiconductor fine particles can be carried out by immersing the working electrode containing the semiconductor particles which are well dried in the dye solution, or by applying the dye solution to the semiconductor fine particle layer and adsorbing it. . In the former case, a dipping method, a dipping method, a roller method, an air knife method, or the like can be used. In the case of the immersion method, the dye may be adsorbed at room temperature or may be heated and refluxed as described in JP-A-7-249790. As the latter application method,
There are a wire bar method, a slide hopper method, an extrusion method, a curtain method, a spin method, and a spray method. Examples of the printing method include letterpress, offset, gravure, and screen printing.

The solvent can be appropriately selected according to the solubility of the dye. For example, water, alcohols (methanol, ethanol, t-butanol, benzyl alcohol, etc.), nitriles (acetonitrile, propionitrile, 3-methoxypropionitrile, etc.), nitromethane, halogenated hydrocarbons (dichloromethane, dichloroethane, chloroform) , Chlorobenzene, etc.), ethers (diethyl ether, tetrahydrofuran, etc.), dimethyl sulfoxide, amides (N, N-dimethylformamide, N, N
-Dimethylacetamide, etc.), N-methylpyrrolidone,
1,3-dimethylimidazolidinone, 3-methyloxazolidinone, esters (ethyl acetate, butyl acetate, etc.), carbonates (diethyl carbonate, ethylene carbonate,
Propylene carbonate), ketones (acetone, 2-butanone, cyclohexanone, etc.), hydrocarbons (hexane, petroleum ether, benzene, toluene, etc.) and mixed solvents thereof.

As in the case of the formation of the semiconductor fine particle layer, the liquid viscosity is not limited to the extrusion method for a high-viscosity liquid (for example, 0.01 to 500 Poise), and various printing methods are used for a low-viscosity liquid (for example, 0.1 Poise or less). A slide hopper method, a wire bar method, or a spin method is suitable, and a uniform film can be obtained.

As described above, the viscosity of the dye coating solution, the coating amount,
An application method may be appropriately selected according to parameters such as a support and a coating speed. The time required for dye adsorption after coating should be as short as possible in consideration of mass production.

The total amount of the dye used is preferably 0.01 to 100 mmol per 1 m ² of the support. The amount of the dye adsorbed on the semiconductor fine particles is preferably 0.01 to 1 mmol per 1 g of the semiconductor fine particles. With such an amount of the dye, a sensitizing effect in the semiconductor can be sufficiently obtained. On the other hand, if the amount of the dye is small, the sensitizing effect becomes insufficient, and if the amount of the dye is too large, the dye not adhering to the semiconductor floats and causes a reduction in the sensitizing effect.

Since the presence of unadsorbed dye causes disturbance of device performance, it is preferable to remove the dye by washing immediately after adsorption. It is preferable to perform cleaning with a polar solvent such as acetonitrile and an organic solvent such as an alcohol solvent using a wet cleaning tank. Further, in order to increase the amount of the adsorbed dye, it is preferable to perform the heat treatment before the adsorption. After the heat treatment, in order to avoid the adsorption of water on the surface of the semiconductor fine particles, it is also preferable to quickly adsorb the dye at 40 to 80 ° C. without returning to normal temperature.

A colorless compound may be co-adsorbed for the purpose of reducing the interaction between dyes such as association. Examples of the hydrophobic compound to be co-adsorbed include a steroid compound having a carboxyl group (for example, chenodeoxycholic acid). Further, for the purpose of promoting the removal of excess dye, the surface of the semiconductor fine particles may be treated with an amine after adsorbing the dye. Preferred amines are pyridine, 4
-Tert-butylpyridine, polyvinylpyridine and the like. When these are liquids, they may be used as they are or may be used by dissolving them in an organic solvent. In addition, an ultraviolet absorber can be co-adsorbed for the purpose of preventing light deterioration due to ultraviolet light.

The porous spacer layer and the electron conductive layer of the present invention can be prepared by dispersing the insulating fine particles and the conductive fine particles in an appropriate dispersion medium and coating the semiconductor fine particle layer. . The semiconductor fine particle layer, the spacer layer and the electron conductive layer may be coated simultaneously or sequentially and may be selected according to the heat resistance of each material. Preferably, a semiconductor fine particle layer and a spacer layer are simultaneously coated, sintered, dyed with a dye, and then coated with conductive fine particles dispersed in an appropriate solvent to form an electron conductive layer (counter electrode). As the dispersion medium, water and an organic solvent are used. When coating is performed after the dye is adsorbed on the semiconductor fine particle layer, it is preferable to use an organic solvent. Such organic solvents include methanol,
Examples thereof include ethanol, methoxyacetonitrile, methoxypropionitrile, N-methylpyrrolidone, and propylene carbonate. It is preferable that the dispersion medium contains not only a suitable dispersing agent (for example, carboxymethyl cellulose (CMC), etc.) but also a suitable binder for improving the physical strength of the coating film. As such a binder, a polymer compound having a softening point of 60 ° C to 300 ° C can be used. Specifically, polyvinylidene difluorate, a copolymer of vinyl acetate and vinyl methyl methacrylate, a copolymer of vinyl styrene and vinyl acetic acid, and the like are preferably used.

The substrate on the counter electrode side may be either transparent or opaque, and any substrate may be used as long as it has a structure capable of taking out current by contacting the above-mentioned electron conductive porous layer acting as the counter electrode. For example, the transparent conductive support described for the substrate of the semiconductor film may be used, or a glass or plastic support with metal leads arranged at regular intervals may be used. In this case, the support itself may not have conductivity. Good. Further, a metal plate which is substantially inactive with respect to the components of the charge transfer layer may be used. Examples thereof include a Pt plate, corrosion-resistant stainless steel (SUS316) and the like. Can also be used.

Hereinafter, the charge transfer layer will be described in detail. The charge transfer layer is a layer containing a charge transport material having a function of replenishing electrons to an oxidized dye. Examples of typical charge transport materials that can be used in the present invention include:
As an ion transport material, a solution (electrolyte solution) in which redox couple ions are dissolved, a so-called gel electrolyte in which a redox couple solution is impregnated in a gel of a polymer matrix, a molten salt electrolyte containing redox counter ions, and a solid Electrolytes. In addition to a charge transporting material involving ions, an electron transporting material or a hole (hole) transporting material may be used as a material relating to electric conduction in which carrier movement in a solid is involved.

The molten salt electrolyte is preferable from the viewpoint of achieving both photoelectric conversion efficiency and durability. When a molten salt electrolyte is used in the photoelectric conversion element of the present invention, for example, WO95 / 18456, JP-A-8-259543, Electrochemistry, Vol. 65, No. 11, p.
Known iodine salts such as pyridinium salts, imidazolium salts, and triazolium salts described in J. Org.

The molten salt which can be preferably used includes those represented by any of the following formulas (Ya), (Yb) and (Yc).

[0066]

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In the general formula (Ya), Q _y1 is 5 together with a nitrogen atom.
Or an atomic group capable of forming a 6-membered aromatic cation. Q _y1 is preferably composed of one or more atoms selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom and a sulfur atom.

The 5-membered ring formed by Q _y1 is preferably an oxazole ring, a thiazole ring, an imidazole ring, a pyrazole ring, an isoxazole ring, a thiadiazole ring, an oxadiazole ring or a triazole ring. It is more preferably a ring or an imidazole ring, particularly preferably an oxazole ring or an imidazole ring. The 6-membered ring formed by Q _y1 is preferably a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring or a triazine ring, and more preferably a pyridine ring.

In the general formula (Yb), A _y1 represents a nitrogen atom or a phosphorus atom.

R in the general formulas (Ya), (Yb) and (Yc)
_{y1 to Ry6} each independently represent a substituted or unsubstituted alkyl group (preferably having 1 to 24 carbon atoms, which may be linear, branched, or cyclic; for example, methyl Group, ethyl group, propyl group, isopropyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group, t-
Octyl, decyl, dodecyl, tetradecyl,
2-hexyldecyl group, octadecyl group, cyclohexyl group, cyclopentyl group, etc.) or a substituted or unsubstituted alkenyl group (preferably having 2 to 24 carbon atoms, which may be linear or branched, For example, a vinyl group or an allyl group), more preferably an alkyl group having 2 to 18 carbon atoms or an alkenyl group having 2 to 18 carbon atoms, and particularly preferably an alkyl group having 2 to 6 carbon atoms. .

Further, two or more of R _{y1 to} R _{y4 in} the general formula (Yb) may be linked to each other to form a non-aromatic ring containing A _y1, and R in the general formula (Yc) Two or more of _{y1 to Ry6} may be connected to each other to form a ring structure.

Q in the general formulas (Ya), (Yb) and (Yc)
_y1 and R _y1 to R _y6 may have a substituent, examples of preferred substituents, a halogen atom (F, Cl, Br, I
), A cyano group, an alkoxy group (such as a methoxy group and an ethoxy group), an aryloxy group (such as a phenoxy group), an alkylthio group (such as a methylthio group and an ethylthio group), an alkoxycarbonyl group (such as an ethoxycarbonyl group), and a carbonate group ( Ethoxycarbonyloxy group, etc.), acyl group (acetyl group, propionyl group, benzoyl group, etc.), sulfonyl group (methanesulfonyl group, benzenesulfonyl group, etc.), acyloxy group (acetoxy group, benzoyloxy group, etc.), sulfonyloxy group ( Methanesulfonyloxy group, toluenesulfonyloxy group, etc.), phosphonyl group (diethylphosphonyl group, etc.), amide group (acetylamino group, benzoylamino group, etc.), carbamoyl group (N, N-
Dimethylcarbamoyl group), alkyl group (methyl group,
Ethyl group, propyl group, isopropyl group, cyclopropyl group, butyl group, 2-carboxyethyl group, benzyl group, etc., aryl group (phenyl group, toluyl group, etc.), heterocyclic group (pyridyl group, imidazolyl group, furanyl group) etc),
Alkenyl groups (vinyl group, 1-propenyl group, etc.) and the like.

According to the general formula (Y-a), (Y-b) or (Y-c)
The compound represented by_y1Or R_y1~ R _y6Multimer through
May be formed.

These molten salts may be used alone or
The iodine anion may be used in combination with a molten salt obtained by replacing the iodine anion with another anion. As the anion to replace the iodine anion,
Halide ions (Cl ^-, Br ^{-, _{etc.), NSC -, BF 4 -}} , P
_{^{F 6 -, ClO 4 -,}} (CF 3 SO 2) 2 N -, (CF 3 CF 2 SO 2) 2 N -, CF 3 SO 3 -,
Preferred examples include CF ₃ COO ⁻ , Ph ₄ B ⁻ , (CF ₃ SO ₂ ) ₃ C ^{−, and} more preferably (CF ₃ SO ₂ ) ₂ N ⁻ or BF ₄ ⁻ . Also, other iodine salts such as LiI can be added.

Specific examples of the molten salt preferably used in the present invention are shown below, but are not limited thereto.

[0076]

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[0077]

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[0078]

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[0079]

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[0080]

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[0081]

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[0082]

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The above molten salt can be used without using a solvent. Although the solvent described below may be added, the content of the molten salt is preferably 50% by weight or more based on the entire electrolyte composition. Further, it is preferable that at least 50% by weight of the salt is an iodine salt.

It is preferable to add iodine to the electrolyte composition. In this case, the content of iodine is preferably 0.1 to 20% by weight, and more preferably 0.5 to 5% by weight based on the whole electrolyte composition. Is more preferred.

When an electrolyte is used for the charge transfer layer,
Liquids can consist of electrolytes, solvents, and additives
preferable. The electrolyte of the present invention comprises I_TwoAnd iodide combinations
(Iodides include LiI, NaI, KI, CsI,
CaI_TwoMetal iodide such as, or tetraalkyl
Ammonium iodide, pyridinium iodide, i
Of quaternary ammonium compounds such as midazolium iodide
Iodine salt), Br _TwoAnd bromide combinations (bromide
As LiBr, NaBr, KBr, CsBr, Ca
Br_TwoMetal bromide or tetraalkylan
Grade 4 such as monium bromide and pyridinium bromide
Bromide salts of ammonium compounds)
Phosphate-ferricyanate or ferrocene-ferricinium
Metal complexes such as muon, sodium polysulfide,
Sulfur compounds such as ruthiol-alkyl disulfide
Products, viologen dyes, hydroquinone-quinone, etc.
Can be Among them I_TwoAnd LiI and pyridinium
Grade 4 ammo such as iodide, imidazolium iodide
The present invention provides an electrolyte comprising a combination of an iodine salt of a sodium compound.
Is preferred. The above-mentioned electrolytes may be used as a mixture.
No.

The preferred electrolyte concentration is 0.1M or more and 15M or less, more preferably 0.2M or more and 10M or less. When iodine is added to the electrolyte, a preferable concentration of iodine is 0.01 M or more and 0.5 M or less.

The solvent used for the electrolyte in the present invention is a compound capable of exhibiting excellent ionic conductivity by lowering the viscosity and improving the ionic mobility or increasing the dielectric constant and improving the effective carrier concentration. Desirably. Examples of such a solvent include carbonate compounds such as ethylene carbonate and propylene carbonate, 3-methyl-
Heterocyclic compounds such as 2-oxazolidinone, dioxane, ether compounds such as diethyl ether, ethylene glycol dialkyl ether, propylene glycol dialkyl ether, polyethylene glycol dialkyl ether, chain ethers such as polypropylene glycol dialkyl ether, methanol, ethanol,
Alcohols such as ethylene glycol monoalkyl ether, propylene glycol monoalkyl ether, polyethylene glycol monoalkyl ether, and polypropylene glycol monoalkyl ether; polyhydric alcohols such as ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, and glycerin; acetonitrile; Nitrile compounds such as glutaronitrile, methoxyacetonitrile, propionitrile, and benzonitrile; aprotic polar substances such as dimethylsulfoxide (DMSO) and sulfolane; and water can be used.

Further, according to the present invention, J. Am. Ceram. Soc.,
80 (12) 3157-3171 (1997), ter-butylpyridine, and basic compounds such as 2-picoline and 2,6-lutidine can also be added. The preferred concentration range when adding a basic compound is 0.05M or more and 2M or less.

In the present invention, the electrolyte may be gelled (solidified) by a technique such as addition of a polymer, addition of an oil gelling agent, polymerization containing a polyfunctional monomer, or crosslinking reaction of the polymer. When gelling by adding a polymer, use the Polymer Electrolyte Review-1 and 2
(Co-edited by JR MacCallum and CA Vincent, ELSEVIER APPLI
Compounds described in ED SCIENCE) can be used, and particularly, polyacrylonitrile and polyvinylidene fluoride can be preferably used. When gelling by adding an oil gelling agent, use J. Chem Soc. Japan, Ind.
Chem.Sec., 46,779 (1943), J. Am. Chem. Soc., 111,5
542 (1989), J. Chem. Soc., Chem. Commun., 1993, 39
0, Angew. Chem. Int. Ed. Engl., 35, 1949 (1996), Che
m. Lett., 1996, 885, J. Chm. Soc., Chem. Commun., 1
Although the compounds described in 997,545 can be used, preferred compounds are compounds having an amide structure in the molecular structure.

When the gel electrolyte is formed by polymerization of polyfunctional monomers, a solution is prepared from the polyfunctional monomers, a polymerization initiator, an electrolyte, and a solvent, and the solution is prepared by a method such as a casting method, a coating method, a dipping method, or an impregnation method. A method in which a sol-like electrolyte layer is formed on an electrode supporting a dye and then gelled by radical polymerization is preferable. The polyfunctional monomer is preferably a compound having two or more ethylenically unsaturated groups, for example, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and triethylene glycol dimethacrylate. Ethylene glycol diacrylate, triethylene glycol dimethacrylate,
Preferred examples include pentaerythritol triacrylate and trimethylolpropane triacrylate. The monomers constituting the gel electrolyte may include a monofunctional monomer in addition to the above, and may include acrylic acid or α-
Esters or amides derived from alkylacrylic acids (such as methacrylic acid) (such as Nis
o-propylacrylamide, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, acrylamidopropyltrimethylammonium chloride,
Methyl acrylate, hydroxyethyl acrylate,
n-propyl acrylate, n-butyl acrylate,
2-methoxyethyl acrylate, cyclohexyl acrylate, etc.), vinyl esters (eg, vinyl acetate), esters derived from maleic acid or fumaric acid (eg, dimethyl maleate, dibutyl maleate, diethyl fumarate, etc.), maleic acid, Fumaric acid,
p-styrenesulfonic acid sodium salt, acrylonitrile, methacrylonitrile, dienes (eg, butadiene, cyclopentadiene, isoprene), aromatic vinyl compound (eg, styrene, p-chlorostyrene, sodium styrenesulfonate), nitrogen-containing heterocycle A vinyl compound having a quaternary ammonium salt,
N-vinylformamide, N-vinyl-N-methylformamide, vinyl sulfonic acid, sodium vinyl sulfonate, vinylidene fluoride, vinylidene chloride, vinyl alkyl ethers (eg, methyl vinyl ether), ethylene, propylene, 1-butene, isobutene, N-phenylmaleimide and the like can be preferably used. The preferred weight composition range of the polyfunctional monomer in the total amount of the monomers is preferably from 0.5% by weight to 70% by weight, more preferably from 1.0% by weight to 50% by weight.
% By weight or less.

The above-mentioned monomers are generally described in Takatsu Otsu and Masayoshi Kinoshita: Experimental Method for Polymer Synthesis (Chemical Doujin) and Takatsu Otsu: Lecture Polymerization Reaction Theory 1 Radical Polymerization (I) (Chemical Doujin) It can be polymerized by radical polymerization, which is a simple polymer synthesis method. The monomer for a gel electrolyte that can be used in the present invention can be radically polymerized by heating, light, electron beam, or electrochemically, but it is particularly preferable to radically polymerize by heating. The polymerization initiator preferably used when the crosslinked polymer is formed by heating,
For example, 2,2'-azobis (isobutyronitrile),
Azo initiators such as 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2'-azobis (2-methylpropionate), peroxide initiators such as benzoyl peroxide, etc. It is. The preferable addition amount of the polymerization initiator is 0.01% by weight or more based on the total amount of the monomers.
0% by weight or less, more preferably 0.1% by weight or more and 10% by weight or less.

The weight composition range of the monomers in the gel electrolyte is preferably from 0.5% by weight to 70% by weight, more preferably from 1.0% by weight to 50% by weight.

When the electrolyte is gelled by the crosslinking reaction of the polymer, it is desirable to use a polymer containing a crosslinkable reactive group and a crosslinking agent together. In this case, a preferable crosslinkable reactive group is a nitrogen-containing heterocyclic ring (for example, a pyridine ring, an imidazole ring, a thiazole ring, an oxazole ring, a triazole ring, a morpholine ring, a piperidine ring, a piperazine ring, etc.), and a preferable crosslinking agent. Is a bifunctional or higher functional reagent capable of electrophilic reaction with a nitrogen atom (for example, alkyl halide, aralkyl halide, sulfonic acid ester, acid anhydride, acid chloride, isocyanate, etc.).

In the present invention, an organic or organic material is used instead of the electrolyte.
Use a hole transport material that is inorganic or a combination of both.
Can be used. Organic hole transport applicable to the present invention
Materials include N, N'-diphenyl-N, N'-bis (4-meth
(Xyphenyl)-(1,1'-biphenyl) -4,4'-diamine
(J. Hagen et al., Synthetic Metal 89 (1997) 215-22
0), 2,2 ', 7,7'-tetrakis (N, N-di-p-methoxyphenyl)
Ruamine) 9,9'-spirobifluorene (Nature, Vol. 395,
 8 Oct. 1998, p583-585 and WO97 / 10617), 1,1-bis
{4- (di-p-tolylamino) phenyl} cyclohexane
Aromatic Diamine Linked with Tertiary Aromatic Amine Unit
Compound (JP-A-59-194393), 4,4-bis
[(N-1-naphthyl) -N-phenylamino] biphenyl
Condensation of two or more containing two or more tertiary amines represented
Aromatic amine having an aromatic ring substituted by a nitrogen atom
-234681), a derivative of triphenylbenzene
Aromatic triamine having terburst structure (US Patent
No. 4,923,774, JP-A-4-308688), N, N'-di
Phenyl-N, N'-bis (3-methylphenyl)-(1,1'-bi
Aromatic diamines such as phenyl) -4,4'-diamine (US
Patent No. 4,764,625), α, α, α ′, α′-tetramethy
-Α, α'-bis (4-di-p-tolylaminophenyl) -p-
Xylene (JP-A-3-269084), p-phenylene
Amine derivatives, sterically asymmetric trif as a whole molecule
Phenylamine derivatives (JP-A-4-129271),
Compounds in which a plurality of aromatic diamino groups are substituted for a benzyl group (particularly
JP-A-4-175395), tertiary aromatic amine with ethylene group
Unit-linked aromatic diamine (JP-A-4-264189)
Japanese Patent Application Laid-Open (JP-A) No. 6-64, and aromatic diamine having a styryl structure
JP-A-4-290851), benzylphenyl compounds (JP-A
JP-A-4-364153), connecting a tertiary amine with a fluorene group
(JP-A-5-25473), triamine compound
(JP-A-5-239455), pisdipyridylaminobi
Phenyl (JP-A-5-320634), N, N, N-trif
Phenylamine derivatives (JP-A-6-1972), phenoamines
Aromatic diamine having a xazazine structure (Japanese Patent Application Laid-Open No. 7-138562)
No.), diaminophenylphenanthridine derivative (JP-A
Aromatic amines, α-octane shown in
Tilthiophene and α, ω-dihexyl-α-octylchi
Offen (Adv. Mater. 1997, 9, N0.7, p557), hexadode
Sild decithiophene (Angew. Chem. Int. Ed. Engl. 1
995, 34, No. 3, p303-307), 2,8-dihexylanthra [2,
3-b: 6,7-b '] dithiophene (JACS, Vol120, N0.4,1998, p66
Oligothiophene compounds such as 4-672), polypyrrole (K.
 Murakoshi et al.,; Chem. Lett. 1997, p471), ¨ Ha
ndbook of Organic Conductive Molecules and Polymer
s Vol.1,2,3,4¨ (by NALWA, published by WILEY)
Polyacetylene and its derivatives, poly (p-phenylene)
Len) and its derivatives, poly (p-phenylene vinylene)
And its derivatives, polythienylenevinylene and
Derivatives, polythiophenes and their derivatives, polya
Nirin and its derivatives, polytoluidine and its derivatives
Conductive polymers such as conductors can be preferably used
You. In addition, Nature, Vo
l. 395, 8 Oct. 1998, as described in p583-585
Tris (4) to control dopant level
-Bromophenyl) aminium hexachloroantimonate
Addition of compounds containing cation radicals such as salts
Control of the oxide semiconductor surface
Li [(CF _ThreeSO_Two)_TwoN]
It may be added.

The organic hole transporting material can be introduced into the inside of the electrode by a method such as a vacuum evaporation method, a casting method, a coating method, a spin coating method, an immersion method, an electrolytic polymerization method, and a photoelectrolytic polymerization method. When a hole transport material is used instead of an electrolyte, use Electorochim. Acta 40, 643-6 to prevent short circuits.
52 (1995), it is preferable to apply a thin layer of titanium dioxide as an undercoat layer between the conductive support and the semiconductor-containing layer by using a technique such as spray pyrolysis.

When an inorganic solid compound is used in place of the electrolyte, copper iodide (p-CuI) (J. Phys. D: Appl. Phys. 31
(1998) 1492-1496), copper thiocyanate (Thin Solid Film)
s 261 (1995) 307-310, J. Appl. Phys. 80 (8), 15 Octobe
r 1996, p4749-4754, Chem. Mater. 1998, 10, 1501-150.
9, Semicond. Sci. Technol. 10, 1689-1693) can be introduced into the inside of the electrode by a method such as a casting method, a coating method, a spin coating method, a dipping method, and an electrolytic plating method.

There are several methods for forming the charge transfer layer. One is a method in which a counter electrode substrate is first bonded on a porous electron conductive layer, and a liquid charge transfer layer is sandwiched in the gap. In the second method, the charge transfer layer is directly provided on the porous electron conductive layer, and then the counter electrode substrate is provided.

In the former case, as a method of sandwiching the charge transfer layer, a normal pressure process using a capillary phenomenon by immersion or the like, or a method in which the gas phase between the electrodes or in the porous film is replaced with a liquid phase at a pressure lower than normal pressure. A vacuum process is available.

In the latter case, the wet type charge transfer layer is provided with the counter electrode substrate in an undried state, and measures are taken to prevent the edge portion from leaking liquid. In the case of a gel electrolyte, there is also a method of applying in a wet manner and solidifying it by a method such as polymerization.
In that case, a counter electrode can be provided after drying and immobilization. As a method for applying a wet organic hole transport material or a gel electrolyte in addition to the electrolytic solution, the immersion method, the roller method, the dipping method, the air knife method, the extrusion method, and the slide method are the same as the method for applying the semiconductor fine particle-containing layer and the dye. A hopper method, a wire bar method, a spin method, a spray method, a casting method, various printing methods and the like can be considered. In the case of a solid electrolyte or a solid hole transporting material, a vacuum evaporation method or a CVD method is used.
The charge transfer layer may be formed by a dry film forming process such as a method, and then a counter electrode substrate may be provided.

The water content in the charge transfer layer was 10,
2,000 ppm or less, more preferably 2,0 ppm
It is at most 00 ppm, particularly preferably at most 100 ppm.

[0101]

EXAMPLES The effects of the present invention will be specifically described below with reference to examples.

1. Preparation of coating solution containing titanium dioxide particles J. J. Barbe et al. Am. Ceramic S
oc. According to the production method described in the article of Vol. 80, p. 3157, titanium tetraisopropoxide is used as a titanium raw material, and the temperature of the polymerization reaction in the autoclave is 230 ° C.
And a titanium dioxide dispersion having a titanium dioxide concentration of 11% by weight was synthesized. The average size of the obtained titanium dioxide particles was about 10 nm. 30% by weight of polyethylene glycol (molecular weight: 2
000, manufactured by Wako Pure Chemical Industries, Ltd.) and mixed to obtain a coating solution.

2. Preparation of Alumina Particle-Containing Coating Solution 2% C
120 g of an MC aqueous solution and 150 ml of water were added, and the mixture was stirred at 10,000 rpm for 3 minutes using a homogenizer to obtain a dispersion. To this, 1 ml of a 2% aqueous solution of nonylphenol ether was added to prepare a coating solution.

3. Preparation of a graphite dispersion carrying platinum 10 ml of chloroplatinic acid in 100 ml of isopropyl alcohol
g was dissolved in the powdered graphite powder (with a particle size of about 1).
μm) was added, and the mixture was sufficiently stirred using a stirrer, and then heated at 60 ° C. for 30 minutes to obtain a graphite dispersion supporting platinum.

4. Dioxide with spacer layer adsorbing dye
Preparation of titanium electrode Transparent conductor coated with fluorine-doped tin oxide
Electrical glass (made by Nippon Sheet Glass, area resistance is about 10Ω / □)
On the conductive surface side of 1. Titanium dioxide dispersion prepared in
Is applied to a thickness of 80 μm with a doctor blade and dried.
Further, the above-mentioned 2. 25 parts of the alumina dispersion prepared in
It was applied to a thickness of μm. After air drying for 30 minutes,
(450 ° C in Yamato Scientific muffle furnace fp-32)
Baking for 30 minutes. The thickness of titanium dioxide is 7.2 μm,
The thickness of the alumina layer functioning as a spacer layer is about 2μ.
m. After removing the glass and cooling it,
3 × 10 of the dye represented by R-1 ^-FourMol / l
Immersed in 2-propanol solution at room temperature for 16 hours.
Wash the stained glass with acetonitrile in a dark place.
And dried.

5. 3. Installation of graphite layer 2. Screen-printing method on the electrode prepared in 3. The dispersion of the platinum-supported graphite prepared in the above was coated to a thickness of about 30 μm, and then dried, and further heated in a vacuum dryer at 60 ° C. for 30 minutes to form a porous electron conductor acting as a counter electrode. The active layer was installed.

6. Injection of electrolytic solution The electrode laminate (2 cm × 1.5
5 μl of an electrolytic solution having the composition shown in Table 1 was dropped on the surface of the graphite layer (cm), and heated at 50 ° C. for 1 hour under reduced pressure to allow the electrolytic solution to permeate the pores of the electrode laminate.

7. Preparation of Photovoltaic Cell A counter electrode-side substrate obtained by sputtering platinum on an aluminum plate having the same size as the above-mentioned electrode was superimposed on the above-mentioned electrode laminate so that the platinum side faced. At this time, the positions were shifted by the dimension for taking out the leads, and the leads were overlaid. Next, the peripheral portions of the two substrates were sealed with a hot-melt adhesive. In this way, as in the basic layer configuration shown in FIG. 1, the glass substrate 1, the transparent conductive layer 2, the dye-adsorbed TiO ₂ electrode 3 (the electrolyte 6 penetrates), the spacer layer 4 (the electrolyte 6 penetrates), A photovoltaic cell according to the present invention was obtained in which the porous electron conductive layer 5 (permeated by the electrolyte 6), the platinum layer 7 and the aluminum substrate 8 were sequentially laminated. FIGS. 2 and 3 are cross-sectional views of examples of the basic configuration of a photovoltaic cell exhibiting the effects of the present invention. However, the present invention is not limited to this.

8. Preparation of photovoltaic cell for comparison Except for the absence of a spacer layer and a porous electron conductive layer, the same electrode laminate as above was prepared, and after permeating the same electrolytic solution, the same aluminum substrate with Pt as above and polyethylene Were superposed with each other with a frame type spacer (thickness: 20 μm) therebetween. This was further heated and sealed to obtain a comparative photocell.

[0110]

[Table 1]

9. Measurement of photoelectric conversion efficiency A 500 W xenon lamp (USHIO Inc.) and a correction filter for sunlight simulation (AM manufactured by Oriel)
1.5), and the incident light intensity on the battery is 100 mW /
Simulated sunlight adjusted to cm ² was generated. Ohmic contacts are made to both poles of the fabricated photovoltaic cell with conducting wires.
The electrical response of both electrodes was input to a current / voltage measuring device (Keisley source measure unit type 238). The photovoltaic cell is set in a thermostat holder, keeping the temperature at 30 ° C,
Irradiation light from the above light source was incident from the transparent electrode side of the battery, and current-voltage characteristics were measured. The open-circuit voltage (Voc), short-circuit current density (Jsc), and form factor (F
F) and conversion efficiency (η) are collectively shown in Table 2.

[0112]

[Table 2]

From the results of the above examples, it can be seen that the battery according to the present invention has a higher short-circuit current than the battery of the comparative example, and as a result, a higher light conversion efficiency can be obtained.

[0114]

According to the present invention, a dye-sensitized photoelectric conversion element and a photovoltaic cell having excellent energy conversion efficiency can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a photovoltaic cell according to the present invention prepared in an example.

FIG. 2 is a cross-sectional view showing a basic configuration example of a photovoltaic cell of the present invention.

FIG. 3 is a cross-sectional view showing a basic configuration example of a photovoltaic cell of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 glass substrate 2 transparent conductive layer (fluorine-doped tin oxide film) 3 dye-adsorbed TiO ₂ layer 4 porous alumina spacer layer 5 platinum-supported graphite layer (porous electron conductive layer) 6 electrolyte (3, 4, 5 layers) 7 Platinum layer 8 Aluminum substrate 9 Metal mesh or metal lead 10 Dye-adsorbing semiconductor film 11 Spacer layer (impregnated with charge transport material) 12 Porous electron conductive layer (impregnated with charge transport material) 13 Transparent support 14 Undercoat layer 15 Transparent conductive layer 16 Metal layer 17 Support substrate

Claims (12)

[Claims] 1. A photoelectric conversion device having at least a photosensitive semiconductor film, a charge transfer layer, and a counter electrode, comprising a substantially electrically insulating spacer layer between the semiconductor film and the counter electrode, and wherein the counter electrode is A photoelectric conversion element comprising a porous electron conductive layer. 2. The photoelectric conversion device according to claim 1, wherein the porous electron conductive layer is provided adjacent to the spacer layer. 3. The photoelectric conversion device according to claim 1, wherein the porous electron conductive layer is formed by binding conductive fine particles. 4. The photoelectric conversion element according to claim 3, wherein the conductive fine particles are platinum black or carbon fine particles carrying platinum. 5. The device according to claim 1, wherein the counter electrode has a structure in which the porous electron conductive layer is provided on a conductive substrate.
The photoelectric conversion element according to any one of claims 1 to 4. 6. The method according to claim 1, wherein the spacer layer is a porous layer formed by binding insulating fine particles.
The photoelectric conversion element according to any one of the above. 7. The photoelectric conversion element according to claim 6, wherein the insulating fine particles of the spacer layer are made of an oxide containing at least one element selected from aluminum, silicon, boron and phosphorus. 8. The photoelectric conversion device according to claim 6, wherein the insulating fine particles of the spacer layer are made of an organic polymer. 9. The photoelectric conversion device according to claim 1, wherein said photosensitive semiconductor film contains titanium dioxide. 10. The photoelectric conversion device according to claim 1, wherein the photosensitive semiconductor film is sensitized by a dye. 11. The photoelectric conversion device according to claim 1, wherein the charge transfer layer contains a molten salt. 12. A photovoltaic cell using the photoelectric conversion element according to claim 1.