JP2001243995A - Photoelectric conversion element and photoelectric cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion element and a photoelectric cell using the same that has a high durability and has low fluctuation of conversion efficiency due to the environmental temperature. SOLUTION: The photoelectric conversion element and photoelectric cell comprise a semiconductor layer which is provided on a conductive supporting body and adsorbed with pigment, a charge transfer layer containing charge transfer material, and opposite electrodes successively in order. A porous layer which holds charge transfer material is provided adjacent to the opposite electrodes and at the opposite side of the semiconductor layer against the opposite electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photoelectric conversion element using a semiconductor sensitized with 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 high. 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 study, a solution of a redox compound in an organic solvent was used as the charge transporting material. However, in these devices, there was a problem that the organic solvent was scattered and the performance was greatly deteriorated.
As a method of solving this, the use of room temperature molten salts that maintain a liquid state at room temperature has been studied.However, in these charge transfer layers, the movement of charges tends to be slow. There is a problem that the performance as a battery cannot be sufficiently exhibited.

In a conventional device, a working electrode carrying semiconductor fine particles and a planar counter electrode are opposed to each other via a spacer.
In the meantime, it has been general to form an element by injecting an electrolyte. However, in order to facilitate charge transport in the structure of this device, it is necessary to make the gap between the working electrode and the counter electrode sufficiently small. It was necessary to approach the counter electrode almost to the close contact state. However, in such an element structure, a short circuit is likely to occur due to contact between the electrodes, and the amount of electrolyte between the electrodes becomes extremely small. However, there are problems such as slight changes in the electrolyte immediately resulting in deterioration of element performance, and as a result, further new technology was required to realize a solar cell with excellent durability and high performance .

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a dye-sensitized photoelectric conversion element and a photovoltaic cell having high durability and excellent energy conversion efficiency even at a low temperature.

[0005]

The object of the present invention has been attained by the following items which specify the present invention and preferred embodiments thereof. (1) A photoelectric conversion element, which is provided on a conductive support and has a dye-adsorbed semiconductor layer, a charge transport layer containing a charge transport material, and a counter electrode in sequence, adjacent to the counter electrode, and
A photoelectric conversion element comprising a porous layer holding a charge transporting material on a side opposite to a semiconductor layer with respect to a counter electrode. (2) The photoelectric conversion device according to the above (1), wherein the charge transport material is a composition containing a room temperature molten salt. (3) The light conversion element according to (1) or (2), wherein the counter electrode is a mesh-shaped or mesh-shaped metal electrode. (4) The light conversion element according to (1) or (2), wherein the porous layer is made of a conductive material, and the counter electrode is made of fine metal particles discretely attached to the upper layer of the porous layer. (5) The light conversion element according to (3) or (4), wherein the metal is platinum. (6) The photoelectric conversion element according to any one of (1) to (5), wherein the semiconductor layer contains titanium oxide. (7) The photoelectric conversion device according to any one of (2) to (6), wherein the composition containing a room-temperature molten salt contains at least iodide of an imidazolium derivative and iodine. (8) A photovoltaic cell using the photoelectric conversion element according to any one of (1) to (7).

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION [1] Structure of Photoelectric Conversion Device In the present invention, a dye-sensitized photoelectric conversion device is provided on a conductive support and comprises a semiconductor layer (photosensitive layer) sensitized by a dye. It has a laminated structure including a photoelectrode, a counter electrode, and a charge transfer layer (containing a charge transport material) that is in electrical contact with and joins the photoelectrode and the counter electrode. The present invention is further characterized in that a porous layer holding the charge transporting material is provided adjacent to the counter electrode and on the opposite side of the photosensitive layer with respect to the counter electrode (that is, the conductive support, the photosensitive layer, A charge transfer layer, a counter electrode, and a porous layer in this order). 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 light irradiation of a working electrode, and is characterized as a photoelectrochemical cell when the charge transporting material is an ion-conductive electrolyte. The dye-sensitized semiconductor layer, which is a photosensitive layer, is designed according to the purpose, and may have a single-layer structure or a multilayer structure. Light incident on the photosensitive layer is absorbed by the dye and excites the dye molecules. The dye molecules in the excited state inject excited electrons having high energy into the conduction band of the semiconductor fine particles, and the injected conductor electrons diffuse through the semiconductor bulk and reach the conductive support. 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 by the conductive support perform electric work in an external circuit, are transmitted to the counter electrode, return to the oxidized dye via the charge transport material layer, and the dye is regenerated. In the present invention, although a layer structure is adopted, a contact portion of each layer (for example, a boundary between a conductive layer and a photosensitive layer of a conductive support, a boundary between a photosensitive layer and a charge transport material layer, and a charge transport material layer and a counter electrode). At the boundary, etc.), the materials or compounds and ions constituting the layer may be in a state of being diffused and mixed with each other. In particular, the semiconductor layer is preferably porous made of a fine particle semiconductor, and it is preferable that the charge transport material is held in the void. Further, the charge transport materials of the semiconductor layer, the charge transfer layer and the porous layer in contact with the counter electrode can be diffused and mixed with each other.

(A) Conductive Support In the device of the present invention, an optically transparent support that supports the dye-sensitized semiconductor layer is used. Optically transparent means that a region that transmits visible light is present in the plane, and may be substantially translucent. Specifically, the transparent conductive support has a thickness of 400 to 900 n.
m means that the maximum light transmittance in the visible light range is 10% or more, preferably 50% or more, and particularly preferably 70% or more. The photoelectric conversion element of the present invention has a structure in which incident light penetrates a transparent conductive support and reaches a photosensitive layer.As the light transmittance of the conductive support increases,
The light absorption efficiency of the photosensitive layer increases, and the photoelectric conversion efficiency improves. In the present invention, a metal lead (a metal such as aluminum, copper, silver, gold, platinum, nickel, etc.) is connected to a transparent electrode in order to increase the transmittance and reduce the resistance of the electrode to maintain a high current collection efficiency. A transparent conductive support having a structure arranged in the plane of is preferred. Specifically, it is a transparent or translucent glass or plastic substrate having a transparent conductive layer on the surface. Preferred conductive agents used for the conductive layer include metals (for example, platinum, gold, silver, copper, aluminum, rhodium,
And a thin film of a conductive metal oxide (such as indium-tin composite oxide or tin oxide doped with fluorine). The conductive agent layer preferably has a thickness of about 0.02 to 10 μm. The coating amount of the conductive metal oxide is 1 m ^{2 on the} support.
0.01 to 100 g per unit is preferred. The lower the surface resistance of the transparent conductive substrate, the better. The preferable range of the sheet resistance is 100 Ω / □ or less, more preferably 40Ω / □.
Ω / □ or less. The lower limit is not particularly limited, but is usually about 10Ω / □. A particularly preferred transparent conductive support is glass or plastic coated with a conductive metal oxide. Among them, conductive glass in which a highly conductive transparent layer made of tin dioxide doped with fluorine or antimony or indium tin oxide (ITO) is coated on 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. For the transparent polymer film, tetraacetyl cellulose (TA
C), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), syndioctatic polysterene (SPS), polyphenylene sulfide (P
PS), polycarbonate (PC), polyarylate (PAr), polysulfone (PSF), polyestersulfone (PES), polyetherimide (PE)
I), cyclic polyolefin, brominated phenoxy and the like.

(B) Photosensitive Layer (1) Semiconductor The semiconductor used for dye sensitization in the present invention is preferably an n-type semiconductor which gives an anode current by using conduction band electrons as carriers under photoexcitation. Specifically, silicon, a simple semiconductor such as germanium, a III-V compound semiconductor,
Use of metal chalcogenides (eg, oxides, sulfides, selenides, etc.) or compounds having a perovskite structure (eg, strontium titanate, calcium titanate, sodium titanate, barium titanate, potassium niobate, etc.) Can be.

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.

Preferred specific examples of the semiconductor used in the present invention
Is Si, TiO_Two, SnO_Two, Fe_TwoO_Three, WO_Three, ZnO, Nb_TwoO_Five, CdS, Z
nS, PbS, Bi_TwoS_Three, CdSe, CdTe, GaP, InP, GaAs, CuIn
S_Two, CuInSe_TwoEtc., more preferably TiO_Two, ZnO, Sn
O_Two, Fe_TwoO_Three, WO_Three, Nb_TwoO_Five, CdS, PbS, CdSe, InP, GaAs,
CuInS_TwoOr CuInSe_TwoAnd particularly preferably TiO_TwoAlso
Is Nb _TwoO_FiveAnd most preferably TiO_TwoIt is.

The semiconductor used in the present invention may be a single crystal or a 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 an average particle diameter using the diameter when the projected area is converted into a circle, and is 5% as a primary particle.
It is preferably from 200 to 200 nm, particularly preferably from 8 to 100 nm. The average particle size of the semiconductor fine particles (secondary particles) in the dispersion is 0.01 to 100 μm.
It is preferred that Further, two or more kinds of fine particles having different particle size distributions may be mixed and used, and in this case, the average size of the small particles is preferably 5 nm or less. In addition, semiconductor particles having a large particle size, for example, about 300 nm may be mixed for the purpose of improving the light capture rate by scattering incident light.

The method for producing semiconductor fine particles is described in "Sol-gel method", described in "Sol-gel method science" by Agne Shofusha (1988), "Technical Information Association", "Thin-film coating technique by sol-gel method" (1995). 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. Further, a method of producing an oxide by hydrolyzing a chloride in an oxyhydrogen flame at a high temperature developed by Degussa is also preferable. In the case of titanium oxide, the above sol-gel method,
The gel-sol method and the high-temperature hydrolysis method of chloride in an oxyhydrogen flame are both preferred, but the sulfuric acid method and chlorine method described in Manabu Kiyono's "Titanium oxide physical properties and applied technology" Gihodo Shuppan (1997) may also be used. it can. In the case of titanium oxide, among the above-mentioned sol-gel methods, in particular, Barb et al., Journal of American Ceramic Society No. 8
Vol. 0, No. 12, pages 3157 to 3171 (1997) "and the method described in Burnside et al.," Chemical Materials Vol. 10, No. 9, pages 2419 to 2425 "are preferred.

(2) Coating of semiconductor fine particles As a method of coating semiconductor fine particles on a conductive substrate (conductive layer side), a method of coating a dispersion or colloid solution of semiconductor fine particles on a conductive substrate, as described above. 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. The semiconductor fine particle layer may be a single layer, or may have a multilayer structure in which dispersion liquids having different particle diameters are applied in multiple layers. Further, a configuration in which coating layers having different types of semiconductors or different compositions of binders and additives are applied in multiple layers may be employed. When the thickness of the semiconductor fine particle layer is increased, the amount of the dye supported per unit projected area is increased, so that the light capture rate is increased. However, the diffusion distance of generated electrons is increased, and the loss due to charge recombination is also increased. 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 0.5 to 30 μm,
More preferably, it is 25 μm. The coating amount of the semiconductor fine particles per 1 m ² of the support is preferably 0.5 to 400 g, more preferably 2 to 100 g. The semiconductor fine particles may be subjected to a heat treatment to remove the dispersing aid after being applied to the conductive substrate, to make the particles electronically contact each other, and to improve the coating film strength and the adhesion to the substrate. preferable. The preferred range of the heat treatment temperature is 40 ° C. or more and 700.
The temperature is lower than 100 ° C, more preferably 100 ° C to 600 ° C. The heat treatment time is about 10 minutes to 10 hours. After the heat treatment, for example, chemical treatment using an aqueous solution of titanium tetrachloride or trichloride 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 to the semiconductor particles. Electrochemical treatment using a titanium aqueous solution may be performed. The semiconductor fine particles preferably 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. There is no particular upper limit, but usually 1
It is about 000 times.

(3) Sensitizing Dye In the present invention, a dye-adsorbed semiconductor layer obtained by physically or chemically adsorbing a dye to the above semiconductor fine particles is used as a photosensitive layer. In the photosensitive layer, excited electrons generated by light absorption in the absorption wavelength region of the dye are injected into the conduction band of the semiconductor, and are transmitted to the conductive support to generate an electric current. The dye used here is preferably a complex dye, particularly a metal complex dye or a methine dye. In order to widen the wavelength range of photoelectric conversion as much as possible and to increase the conversion efficiency, two or more dyes can be mixed. 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. Such a dye preferably has an appropriate interlocking group for the surface of the semiconductor fine particles. Preferred linking groups include COOH
Group, OH group, SO ₃ H group, cyano group, -P (O) (OH) ₂ group, -OP (O) (O
H) ₂ groups or chelating groups having π conductivity, such as oximes, dioximes, hydroxyquinolines, salicylates and α-ketoenolates. Especially
A COOH group, -P (O) (OH) ₂ group and -OP (O) (OH) ₂ group 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.

Hereinafter, preferred dyes used in the photosensitive layer will be specifically described.

(A) Metal complex dye When the dye is a metal complex dye, the metal atom is ruthenium.
Ru is preferred. Ruthenium complex dyes include:
For example, U.S. Pat.Nos. 4,492,721, 4,684,537, 5,084,365
No. 5,350,644, No. 5463057, No. 5,525,440, JP-A-7
-249790, Japanese Translation of PCT International Publication No. 10-504512, and the complex dyes described in World Patent No. 98/50393.

Further, the ruthenium complex dye used in the present invention is preferably represented by the following general formula (I): (A ₁ ) _p Ru (Ba) (Bb) (Bc) (I) In the general formula (I), A ₁ is C
1, represents a ligand selected from the group consisting of SCN, H ₂ O, Br, I, CN, NCO and SeCN, and p is an integer of 0 to 3. B-
a, Bb and Bc are each independently the following formulas B-1 to B-8:

[0018]

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(However, Ra represents a hydrogen atom or a substituent. Examples of the substituent include a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alkyl group having 7 to 12 carbon atoms. A substituted aralkyl group, or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, a carboxylic acid group, a phosphoric acid group (these acid groups may form a salt); The alkyl part of the aralkyl group may be linear or branched, and the aryl group and the aryl part of the aralkyl group may be monocyclic or polycyclic (condensed ring, ring assembly). Represents an organic ligand. Ba, Bb and Bc
May be the same or different.

Preferred specific examples of the metal complex dye are shown below, but the present invention is not limited thereto.

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[0022]

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[0023]

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(B) Methine Dye The methine dye preferably used in the present invention is disclosed in
-35836, JP-A-11-158395, JP-A-11-163378, JP-A-11-214730,
Dyes described in the specifications of JP-A-11-214731, European Patents 892411 and 911841. For the synthesis of these dyes, see FM Hamer, Heterocyclic Compounds-Cyanine Dyes and Relative Compounds.
ated Compounds), John Wiley & Sons-New York, London,
Published in 1964, DMSturmer
Author, Heterocyclic Compounds-Special topics in heterogeneous
cyclic chemistry) ", Chapter 18, Section 14, 482
515 pages, John Willie and Sons (Jo
hn Wiley & Sons)-New York, London, 197
7th year, "Rodd's Chemistry of Carbon Compounds"
2nd.Ed.vol.IV, part B, 1977, Chapter 15, Chapter 36
9-422, Elsevier Science Public Company, Inc.
ompanyInc.), New York, UK Patent 1,077,611
No. Ukrainskii Khimicheskii Zhurnal, Vol. 40, No. 3
No. 253-258, Dyes and Pigments, No. 21
Volumes 227-234 and in the references cited therein.

(4) Adsorption of Dye on Semiconductor Fine Particles The dye is adsorbed on the semiconductor fine particles by immersing a conductive support having a well-dried semiconductor fine particle layer in a dye solution or by dissolving the dye solution in a semiconductor solution. A method of applying to the fine particle layer can be used. 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,
It may be carried out by heating and refluxing as described in JP-A-7-249790. In addition, as the latter coating method, a wire bar method, a slide hopper method, an extrusion method,
There are a curtain method, a spin method, a spray method and the like, and a printing method includes letterpress, offset, gravure, screen printing and the like. The solvent can be appropriately selected according to the solubility of the dye. For example, 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), dimethylsulfoxide, 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, etc.), ketones (acetone, 2-butanone, cyclohexanone, etc.), hydrocarbons (hexane, petroleum ether, benzene, toluene, etc.) And a mixed solvent thereof.

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 was 0.1 to 1 g of the semiconductor fine particles. It is preferably from 01 to 1 mmol. 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.

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). In addition, an ultraviolet absorber can be co-adsorbed for the purpose of preventing light deterioration due to ultraviolet light. For the purpose of accelerating the removal of excess dye, the surface of the semiconductor fine particles may be treated with an amine after adsorbing the dye. Preferred amines include pyridine, 4-tert-butylpyridine, polyvinylpyridine and the like. When these are liquid, they may be used as they are, or may be used by dissolving them in an organic solvent.

(C) Charge Transfer Layer and Charge Transport Material The charge transfer layer is a layer having a function of replenishing an oxidized dye with electrons. Examples of typical electrotransport materials that can be used in the present invention include a liquid in which a redox couple is dissolved in an organic solvent (electrolyte solution) and a so-called gel in which a liquid in which a redox couple is dissolved in an organic solvent is impregnated in a polymer matrix. Examples include an electrolyte and a molten salt containing a redox couple. (1) Room Temperature Molten Salt Electrolyte The preferred charge transporting material in the present invention is a composition comprising a room temperature molten salt. Examples of such a room temperature molten salt include, for example, WO95 / 18456, and JP-A-8-259543.
No., Electrochemistry 65: 11 923 (1997),
EP-718288, J. Electrochem. Soc., Vol. 14
3, No. 10, 3099 (1996), Inorg. Chem. 1996, 35, 1168-1178
Pyridinium salts, imidazolium salts described in
Known room temperature molten salts such as triazonium salts can be used.

Examples of the molten salt that can be preferably used include those represented by any of the following formulas (Ya), (Yb) and (Yc).

[0030]

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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. .

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 , 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.), SCN -, 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.

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[0041]

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[0044]

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[0045]

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[0046]

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It is preferable not to use a solvent for the molten salt electrolyte. Although a solvent for an electrolytic solution described later may be added, the content of the molten salt is 50% with respect to the entire electrolyte composition.
It is preferable that the amount is at least mass%. In addition, 10% by mass or more of the salt is preferably an iodine salt, and more preferably 50% or more.

It is preferable to add iodine to the electrolyte composition. In this case, the content of iodine is preferably 0.1 to 20% by mass, and more preferably 0.2 to 5% by mass based on the entire electrolyte composition. Is more preferred.

(2) Electrolyte When an electrolyte is used for the charge transfer layer, the electrolyte is an electrolyte,
It is preferable to be composed of a solvent and an additive. Book
The electrolyte of the invention is I_TwoAnd iodide combinations (iodide
Include LiI, NaI, KI, CsI, CaI_Two Such
Metal iodide or tetraalkyl ammonium
Iodide, pyridinium iodide, imidazolium
Iodine salts of quaternary ammonium compounds such as iodide
Etc.), Br _TwoAnd bromide (the bromide is L
iBr, NaBr, KBr, CsBr, CaBr_Two Such
Metal bromide or tetraalkylammonium
Quaternary ammonium such as romide and pyridinium bromide
Bromide salts), ferrocyanate salts
Ferricyanate and ferrocene-ferricinium ions
Which metal complex, sodium polysulfide, alkyl thiol
-Sulfur compounds such as alkyl disulfide, viologen
Dyes, hydroquinone-quinone and the like can be used.
You. Among them I_TwoAnd LiI and pyridinium iodide,
Quaternary ammonium compounds such as imidazolium iodide
In the present invention, an electrolyte containing a combination of various iodine salts is preferred.
No. The above-mentioned electrolytes may be used as a mixture.

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 electrolytic solution in the present invention is a compound that can exhibit excellent ionic conductivity by lowering the viscosity and improving the ionic mobility, or increasing the dielectric constant and improving the effective carrier concentration. It is desirable that 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 dimethyl sulfoxide and sulfolane; and water can be used.

In 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.

(3) Gel Electrolyte In the present invention, the electrolyte may be gelled (solidified) by a method such as addition of a polymer, addition of an oil gelling agent, polymerization containing a polyfunctional monomer, or crosslinking reaction of a polymer. it can. When gelling by adding a polymer, use "Pol
ymer Electrolyte Reviews-1 and 2 "(with JRMacCallum
Compounds described in ELSEVIER APPLIEDSCIENCE (co-edited by CA Vincent) 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. Soc., 46779.
(1943), J. Am. Chem. Soc., 111,5542 (1989), J. Che.
m. Soc., Chem. Commun., 1993, 390, Angew. Chem. In
t. Ed. Engl., 35, 1949 (1996), Chem. Lett., 1996, 88.
5, J. Chm. Soc., Chem. Commun., 1997, 545, but 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 a casting method, a coating method,
It is preferable to form a sol-like electrolyte layer on the electrode supporting the dye by a method such as an immersion method or an impregnation method, and then to cause a gelation by radical polymerization. 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,
Preferred examples include diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, pentaerythritol triacrylate, and trimethylolpropane triacrylate. The monomers constituting the gel electrolyte may further contain a monofunctional monomer, and esters or amides derived from acrylic acid or α-alkylacrylic acid (such as methacrylic acid) (for example,
N-iso-propylacrylamide, acrylamide,
2-acrylamido-2-methylpropanesulfonic acid,
Derived from acrylamidopropyltrimethylammonium chloride, methyl acrylate, hydroxyethyl acrylate, n-propyl acrylate, n-butyl acrylate, 2-methoxyethyl acrylate, cyclohexyl acrylate, etc., vinyl esters (for example, vinyl acetate), maleic acid or fumaric acid (E.g., dimethyl maleate, dibutyl maleate, diethyl fumarate, etc.), maleic acid, fumaric acid, sodium salt of p-styrenesulfonic acid, acrylonitrile, methacrylonitrile, dienes (e.g., butadiene, cyclopentadiene, Isoprene), aromatic vinyl compounds (eg, styrene, p-chlorostyrene,
Sodium styrenesulfonate), vinyl compounds having a nitrogen-containing heterocycle, vinyl compounds having a quaternary ammonium salt, N-vinylformamide, N-vinyl-N-methylformamide, vinylsulfonic acid, sodium vinylsulfonate, vinylidene fluoride , Vinylidene chloride, vinyl alkyl ethers (for example, methyl vinyl ether), ethylene, propylene, 1-butene, isobutene, N-phenylmaleimide and the like can be preferably used. The preferred mass composition range of the polyfunctional monomer in the total amount of the monomers is preferably 0.5% by mass or more and 70% by mass or less, more preferably 1.0% by mass or more and 50% by mass or less.

The above-mentioned monomers can be subjected to radical polymerization by heating, light, electron beam or electrochemically in the presence of a polymerization initiator. The mass composition range of the monomers in the gel electrolyte is preferably 0.5% by mass to 70% by mass, and more preferably 1.0% by mass to 50% by mass. When the electrolyte is gelled by a crosslinking reaction of the polymer, it is preferable 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 halides, aralkyl halides, sulfonic esters, acid anhydrides, acid chlorides, isocyanates, etc.).

(4) Formation of Charge Transfer Layer There are two methods for forming the charge transfer layer. One is a method in which a counter electrode is first attached to a semiconductor layer on which a sensitizing dye is supported, and a liquid charge transfer layer is sandwiched in the gap. The other is a method in which a charge transfer layer is provided directly on a semiconductor layer, and a counter electrode is subsequently provided.

As the method of sandwiching the charge transfer layer in the former case, a normal pressure process utilizing a capillary phenomenon by immersion or the like and a vacuum process of replacing the gas phase with a liquid phase at a pressure lower than normal pressure can be used.

In the latter case, the wet charge transfer layer is provided with a counter electrode 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 it by a wet method and solidifying it by a method such as polymerization. In this case, a counter electrode can be provided after drying and fixing. As a method for applying an electrolytic solution or a gel electrolyte, the immersion method, the roller method, the dipping method, the air knife method, the extrusion method, the slide hopper method, the wire bar method, and the spin method are the same as the method for applying the semiconductor fine particle-containing layer and the dye. , Spraying, casting, various printing methods, and the like.

The charge transfer layer has a certain thickness so as not to cause a short circuit between the photosensitive layer (semiconductor layer) and the counter electrode. However, if the charge transfer layer is too thick, it is not preferable in terms of photoelectric conversion efficiency. The thickness of the charge transfer layer is preferably from 0.05 μm to 100 μm, and more preferably from 0.1 μm to 50 μm. In addition, the charge transport material, as described above,
It is also present in a porous photosensitive layer formed from semiconductor fine particles or in a porous layer adjacent to a counter electrode described below.

The charge transfer layer has a water content of 10,000.
0 ppm or less, more preferably 2,000 ppm.
More preferably, it is 0 ppm or less, especially 100 ppm or less.

(D) Porous Layer In the present invention, the porous layer portion which is adjacent to the counter electrode described below and which has the same charge transporting material as in the charge transfer layer on the side opposite to the semiconductor fine particle layer with respect to the counter electrode. It is characterized by having. The porous layer portion has a space for holding the charge transport material, and the charge transport material held in this space is connected to the charge transport material held in the charge transfer layer or the semiconductor fine particle layer. Any structure can be adopted as long as the structure is appropriate. The present porous layer is provided by, for example, laser processing on a porous layer formed by sintering fine particles, a porous layer formed by a sol-gel method, a layer having a honeycomb structure formed electrochemically, or a base. And the like having a perforated hole. The pore size of the porous layer is 5 nm
To 1 μm, more preferably 50 nm to 500 nm. The thickness of the porous layer is preferably 2 μm or more, and is usually used in the range of 10 μm to 100 μm.

The material constituting the porous portion is a charge transport material.
Any material that is chemically stable in contact with the material
Quality is available. For example, SiO_Two, SnO_Two, ZnO,
Al _TwoO_ThreeMetal oxides or oxide glass
I can do it. Specific examples of preferred oxide glass materials include silica.
At least one element selected from boron, boron and phosphorus
Is an oxide glass containing, for example, a glass having the following composition:
No.

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

It is also possible to use a porous layer made of an organic polymer. For example, a porous membrane made of a material such as polymethyl methacrylate, polyethylene, polystyrene, polypropylene, and polyvinylidene-di-fluorate is exemplified. Further, the porous layer may be made of a conductive substance (for example, metal, carbon, a conductive organic material, or the like).

(E) Counter Electrode A counter electrode that performs an electron transfer reaction with the charge transporting material in the charge transfer layer is disposed adjacent to the porous layer and on the side of the porous layer on the semiconductor electrode side on which the dye is adsorbed. . The counter electrode must have a structure in which the charge transport material in the porous layer and the charge transport layer and the charge transport material in the dye-adsorbing electrode portion can move back and forth, and can take out current outside. Specifically, examples thereof include a mesh-like or mesh-like metal thin film formed on the porous layer and a metal film having a large number of holes. When the porous film has conductivity, the electrode portion does not necessarily have to have a continuous structure, and the conductive portion such as metal fine particles discretely attached to the upper layer of the conductive porous material (the dye-adsorbing semiconductor electrode side). Fine particles may be used.

As the counter electrode, any material (metal, conductive metal oxide, carbon, etc.) can be used as long as it can form an ohmic contact with a small resistance with the charge transporting material. Platinum or carbon is preferable. Platinum is particularly preferred.

As a method for forming a mesh-like metal film on the porous film, for example, a vapor deposition method, a sputtering method and the like can be mentioned, and patterning can be performed using a mask. Examples of a method for depositing metal fine particles discretely on the conductive porous film include, in addition to an electrodeposition method, a method of attaching a metal colloid by electrophoresis, and an electroless plating method.

A support can also be used on the side opposite to the side on which light is incident (ie, on the porous layer side) for the purpose of imparting strength to the element, facilitating manufacture, extracting current, and the like. The support on the porous layer side may be either transparent or opaque, and may be conductive or insulating. Further, a structure having an electrical contact with the counter electrode and capable of extracting a current from the counter electrode, for example, a conductive support or a support having a structure in which metal leads are arranged at regular intervals on a glass or plastic substrate may be used. In the case where electrical connection can be made separately, such as when the counter electrode is a metal film, the support itself may not have conductivity.

[2] Photovoltaic cell The photovoltaic cell of the present invention has the photoelectric conversion element work in an external circuit. It is preferable that the side surface of the photovoltaic cell is sealed with a polymer, an adhesive, or the like in order to prevent deterioration of components and volatilization of the contents. The external circuit itself connected to the conductive support and the counter electrode via a lead may be a known one. When the photoelectric conversion element of the present invention is applied to a so-called solar cell, the structure inside the cell is basically the same as the structure of the above-described photoelectric conversion element. Hereinafter, a module structure of a solar cell using the photoelectric conversion element of the present invention will be described.

The module structure of the dye-sensitized solar cell of the present invention can have basically the same structure as a conventional solar cell module. Generally, a cell is formed on a supporting substrate such as a metal or ceramic, and the cell is covered with a filling resin or a protective glass or the like, and light can be taken in from the opposite side of the supporting substrate. It is also possible to use a transparent material such as tempered glass for the substrate, form a cell thereon, and take in light from the transparent support substrate side. Specifically, a module structure called a superstrate type, a substrate type, or a potting type, or a module structure such as an integrated substrate type used in an amorphous silicon solar cell or the like is possible. These module structures can be appropriately selected depending on the purpose of use and the place of use (environment).

A typical structure of a superstrate type or a substrate type is that cells are arranged at regular intervals between supporting substrates which are transparent on one or both sides and have been subjected to antireflection treatment, and metal leads or adjacent cells are provided between adjacent cells. They are connected by a flexible wiring or the like, and have a structure in which current collecting electrodes are arranged on the outer edge to take out generated power to the outside. Various types of plastic materials such as ethylene vinyl acetate (EVA) can be used between the substrate and the cell in the form of a film or a filling resin, depending on the purpose, in order to protect the cell and increase current collection efficiency. When using in places where it is not necessary to cover the surface with a hard material, such as places where there is little external impact, make the surface protective layer of a transparent plastic film or cure the above-mentioned filling and sealing material. It is also possible to provide a protective function and eliminate the support substrate on one side. The periphery of the support substrate is fixed in a sandwich shape with a metal frame in order to seal the inside and ensure the rigidity of the module, and the space between the support substrate and the frame is hermetically sealed with a sealing material.

Hereinafter, the effects of the present invention will be specifically described with reference to examples. Example 1

1. Preparation of Transparent Conductive Support (for Working Electrode) A 1.9 mm-thick alkali-free glass substrate is uniformly coated with fluorine-doped tin dioxide on the entire surface by CVD, and has a thickness of 600 nm and a sheet resistance of about 20Ω. / □,
A transparent conductive support was formed in which a conductive tin dioxide film having a light transmittance (500 nm) of 85% was coated on one side.

2. 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 mass was synthesized. The average size of the obtained titanium dioxide particles was about 10 nm. 30% by mass of polyethylene glycol (molecular weight: 2
000, manufactured by Wako Pure Chemical Industries, Ltd.) and mixed to obtain a coating solution.

3. Preparation of Titanium Dioxide Electrode Adsorbing Dye A coating solution of 2 was applied to the conductive surface side of the transparent conductive support prepared in 1 above at a thickness of 100 μm by a doctor blade method, dried at 25 ° C. for 30 minutes, and then dried. It was baked in a furnace at 450 ° C. for 30 minutes. The application amount of titanium dioxide is 15 g / m ²
And the film thickness was 8 μm. After the glass was taken out and cooled, an organic solution of dye R-2 (dye 3 × 10 ^-4 mol /
Liter, solvent: 2-propanol) at 40 ° C. for 12 hours. The dyed glass was washed with ethanol and dried naturally in the dark. The amount of the dye adsorbed was about 1.5 × 10 ⁻³ mol per 1 m ^{2 of the} titanium dioxide coated area.

4. Preparation of Counter Electrode A with Porous Layer 10 g of commercially available SiO ₂ fine particle powder (manufactured by Nanotech: particle size: 20 nm) was dispersed in 100 ml of water, and 7 g of polyethylene glycol having an average molecular weight of 500,000 was added thereto, followed by stirring. , SiO ₂ dispersion was prepared. Next, this dispersion was put on a quartz glass substrate for 200 hours.
After coating with a thickness of μm, sintering was performed at 1100 ° C. to obtain a substrate with a porous film. Platinum was adhered to this by a sputtering method until the average film thickness became 100 nm, whereby a platinum electrode portion connected on a mesh was formed on the upper portion of the porous SiO ₂ film.

5. Preparation of Counter Electrode B with Porous Layer 10 g of conductive fine particles (average particle diameter: about 5 nm) composed of tin oxide and indium oxide are dispersed in 100 ml of water, and 7 g of polyethylene glycol having an average molecular weight of 500,000 is added thereto, followed by stirring. Thus, a dispersion was prepared. This was applied on a non-alkali glass substrate with a thickness of 200 μm, and then sintered at 450 ° C. to obtain a substrate with a porous film. This was heated to a temperature of about 120 ° C on a hot plate, and an aqueous solution of chloroplatinic acid was sprayed.
For 20 minutes, thereby causing fine platinum particles to adhere to the surface.

6. Production of Photovoltaic Cell The color-sensitized TiO ₂ electrode (2 cm × 1.5 cm) produced as described above and the counter electrode A with a porous layer were sandwiched by a polyethylene frame spacer (thickness: 10 μm). Terminals for terminals with a width of 2 mm were alternately put outside in the direction of the long side and superposed (see FIG. 1). The entire cell was sealed with an epoxy resin adhesive except for the surface of the transparent conductive support of the TiO ₂ electrode as the light receiving portion. Next, a small hole for liquid injection was made on the side surface of the spacer, and a room temperature molten salt containing 0.8 g of the compound (Y8-1), 0.3 g of (Y7-2) and 0.02 g of iodine described in the text. 5 μl of the composition
Was injected. In this manner, the light receiving area is about 2 cm ² , and as shown in the basic layer configuration shown in FIG. 1, the conductive glass 1 (the conductive agent layer 2 is provided on the glass), the dye-adsorbed TiO ₂ A photovoltaic cell in which the layer 3, the charge transfer layer (containing the molten salt) 4, the platinum counter electrode layer 5, the porous layer 6, and the support glass 7 were sequentially laminated was assembled. A photovoltaic cell was similarly prepared for the counter electrode B with a porous layer. On the same quartz substrate for comparison, platinum was deposited to a thickness of 100 nm by sputtering, thereby producing a counter electrode having a smooth structure without a porous layer, and assembling the stacked photovoltaic cells in the same manner. .

7. 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 94 mW / c
Simulated sunlight adjusted to m ² was irradiated from the transparent conductive support side. A lead wire was connected to a terminal taken out of the conductive glass and the counter electrode of the fabricated photovoltaic cell, and the electric response of both electrodes was input to a current / voltage measuring device (source measure unit 238 made by Keithley) to measure current-voltage characteristics. . The measurement was performed by fixing the battery on a temperature-controlled stage and controlling the temperature during light irradiation as shown in Table 1. The open-circuit voltage (Voc) and short-circuit current density of the photovoltaic cell determined by this
(Jsc), form factor (FF) and conversion efficiency (η) are summarized in Table 1.
It described in.

[0080]

[Table 1]

From the results of the above example, it is found that in the battery using the conventional counter electrode of the comparative example, the conversion efficiency decreases as the environmental temperature decreases. It can be seen that high conversion efficiency can be exhibited in a wide temperature range.

Example 2 Alumina Porous Filter (Wattman, Anodisc / Pore Diameter 0.2 μm)
After palladium treatment, platinum metal was deposited on the surface to a thickness of about 200 nm by electroless plating to produce a counter electrode with a porous layer. A titanium dioxide electrode to which a dye was adsorbed was prepared in the same manner as in Example 1, and a frame spacer made of polyethylene (thickness: 10 μm), a counter electrode with an alumina porous layer described above, and a frame made of polyethylene were sequentially formed. A spacer (thickness: 25 μm) and a substrate made of non-alkali glass having a liquid injection hole were overlapped and sealed by heating at 120 ° C. for 30 seconds to produce a photovoltaic cell. The electrolyte is
The same composition as in Example 1 was injected and used. Further, a comparative battery similar to that of Example 1 was produced. For the battery of Example 2 and the comparative battery, 9
A durability test was carried out by exposing it to simulated sunlight of 4 mW / m ² , and the results are shown in Table 2.

[0083]

[Table 2]

From Table 2, it can be seen that the photovoltaic cell according to the present invention, having a porous portion holding the charge transport material adjacent to the counter electrode,
It can be seen that the conventional photovoltaic cell having a smooth counter electrode exhibits high durability.

[0085]

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

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing the structure of a preferred photoelectric conversion element of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 conductive glass 2 transparent conductive layer 3 dye-adsorbed TiO ₂ layer 4 charge transfer layer 5 counter electrode composed of network platinum layer 6 porous layer (containing charge transporting material) 7 glass support 8 frame spacer

Claims (8)

[Claims] 1. A photoelectric conversion element, which is provided on a conductive support and has a dye-adsorbed semiconductor layer, a charge transport layer containing a charge transport material, and a counter electrode in sequence, wherein the photoelectric conversion element is adjacent to and opposite to the counter electrode. A photoelectric conversion element comprising a porous layer holding a charge transporting material on the side opposite to the semiconductor layer. 2. The photoelectric conversion device according to claim 1, wherein the charge transporting material is a composition containing a room temperature molten salt. 3. The light conversion element according to claim 1, wherein the counter electrode is a mesh-shaped or mesh-shaped metal electrode. 4. The light conversion element according to claim 1, wherein the porous layer is made of a conductive material, and the counter electrode is made of fine metal particles discretely attached to an upper layer of the porous layer. 5. The light conversion device according to claim 3, wherein the metal is platinum. 6. The photoelectric conversion device according to claim 1, wherein the semiconductor layer contains titanium oxide. 7. The photoelectric conversion device according to claim 2, wherein the composition containing a room-temperature molten salt contains at least iodide of an imidazolium derivative and iodine. 8. A photovoltaic cell using the photoelectric conversion element according to claim 1.