JP2001185242A - Photoelectric transducer element and photocell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric transducer element of high energy conversion efficiency and improved durability, and provide a photocell using this transducer. SOLUTION: In the photoelectric transducer element and the photocell having at least a transparent substrate, a conductive electrode installed on the transparent substrate, an exposure layer including a semiconductor, and counter poles, it is constituted so that a fluorescent material or a light-storage material, that converts ultraviolet rays into visible light or a near-infrared rays is installed in the element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion element having excellent energy conversion efficiency and a photovoltaic cell using the same.

[0002]

2. Description of the Related Art At present, single-crystal silicon solar cells, polycrystalline silicon solar cells, amorphous silicon solar cells, and compound semiconductor junction type solar cells such as cadmium telluride and indium copper selenide are mainly used for photovoltaic power generation. Technology. 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. Among the above existing technologies, amorphous silicon is the most promising solar cell material in terms of cost.
Absorbs visible light up to 00 nm and generates 10% power generation efficiency
Near solar energy conversion efficiency is obtained. on the other hand,
Many solar cells that use organic materials, which can easily be made larger in area, as a photosensitive material in place of silicon have been studied in order to further reduce the price, but the energy conversion efficiency is as low as 1% or less and the durability is poor. was there. Under these circumstances, Nature (Vol. 353, pp. 737-740, 1991) and U.S. Pat.
No. 504023, etc., disclosed a photovoltaic cell using porous semiconductor fine particles sensitized by a dye, as well as materials and manufacturing techniques required for the fabrication. This photovoltaic cell is a wet solar cell using a titanium dioxide porous thin film spectrally sensitized using a ruthenium complex as a dye as a photoanode, that is, an electrochemical photocell. 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 collected over a wide visible light wavelength range up to 800 nm. Third, the quantum efficiency of photoelectric conversion is high, and high energy conversion efficiency can be realized. A battery manufacturing technique using this wet solar cell that surpasses amorphous silicon in cost was shown. However, in order to further improve the energy conversion efficiency and secure a great advantage in terms of performance, it is necessary to first expand the photosensitive wavelength range and increase the solar light collection rate. For this purpose, a study to lengthen the photosensitive wavelength of dye sensitization to titanium dioxide has been carried out by using a so-called black dye having broad absorption up to a long wavelength, using Chem. Commun.
705 (1997). However, the sensitization of the photoanode with these long-wavelength sensitizing dyes generally has low quantum efficiency and, when used alone, has little benefit in energy conversion efficiency.

On the other hand, since ultraviolet light promotes fading of the sensitizing dye, a UV cut filter has conventionally been used in combination, and the ultraviolet light component has not been effectively used.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a high conversion efficiency by converting ultraviolet light contained in sunlight or fluorescent lamps into visible light or near infrared light. Another object of the present invention is to provide a photoelectric conversion element exhibiting light durability and a photovoltaic cell using the same.
A second object of the present invention is to provide a photoelectric conversion element that functions even under relatively dark conditions and a photovoltaic cell using the same. The third object of the present invention is easy to manufacture,
An object of the present invention is to provide a low-cost dye-sensitized photoelectric conversion element and a photovoltaic cell using the same. A fourth object of the present invention is to provide a photoelectric conversion element that can also be used as a guide light or a guide sign at night and a photovoltaic cell using the same.

[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 device having at least a transparent substrate, a conductive electrode provided on the transparent substrate, a photosensitive layer containing a semiconductor, and a counter electrode, a fluorescent material or a phosphorescent material is added to the transparent substrate or on the transparent substrate or the counter electrode. A photoelectric conversion element characterized by being present inside. (2) The above-mentioned (1), wherein the fluorescent material or the phosphorescent material is dispersed in a transparent binder and applied to the surface of the transparent substrate opposite to the conductive electrode.
Photoelectric conversion element. (3) The photoelectric conversion element according to (1) or (2), wherein the semiconductor is a porous semiconductor containing at least one kind of metal chalcogenide, and a dye is adsorbed on the semiconductor. . (4) The photoelectric conversion element according to (1), (2) or (3), wherein the photoelectric conversion element has a charge transfer layer between a photosensitive layer and a counter electrode. (5) The fluorescent material or the phosphorescent material has an average particle diameter in a range of 1 to 200 nm, and the ratio of the number of particles having a particle diameter of 400 nm or more is 10% or less (1). The photoelectric conversion element according to any one of (1) to (4). (6) The fluorescent material or the phosphorescent material has a thickness of 400 to 900 nm.
The photoelectric conversion element according to any one of (1) to (5), which emits light in a wavelength range of: (7) The photoelectric conversion element according to any one of claims 1 to 6, wherein the fluorescent material or the phosphorescent material is an inorganic compound. (8) A photocell using the photoelectric conversion element according to any one of (1) to (7).

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [1] Photoelectric conversion element The photoelectric conversion element of the present invention has a structure having at least a transparent substrate, a conductive electrode, a photosensitive layer and a counter electrode. And
The present invention incorporates a function (light emission) of absorbing high-energy light and converting it into light having a wavelength in the photosensitive region of the photosensitive layer. Specifically, a fluorescent material or a phosphorescent material is provided in a transparent substrate, on a transparent substrate, or in a counter electrode. The photoelectric conversion element of the present invention can have various configurations and various materials, but preferably, as shown in FIG. 1, a transparent substrate 50a, a transparent conductive layer 10a, a photosensitive layer 20, a charge transfer layer 30,
The counter electrode conductive layer 40 is stacked in this order, and the photosensitive layer 20 is composed of the semiconductor fine particles 21 sensitized by the dye 22 and the charge transporting material 23 that has penetrated from the charge transfer layer 30 into the gap between the semiconductor fine particles 21. The charge transport material 23 is composed of the same components as the materials used for the charge transfer layer 30. Further, in order to impart strength to the photoelectric conversion element, a support substrate 50 may be provided on the counter electrode conductive layer 40 side. Hereinafter, in the present invention, a layer including the counter electrode conductive layer 40 and an optional substrate 50 is referred to as a “counter electrode”. The photovoltaic cell connects the photoelectric conversion element to an external circuit to perform work. Note that the counter electrode conductive layer 40 and the support substrate 50 in FIG. 1 may be a transparent counter electrode conductive layer 40a and a transparent substrate 50a, respectively. In the present invention, the transparent substrate 50a on the conductive electrode side
A fluorescent material or a phosphorescent material is present on the support substrate 50 of the counter electrode, and it is preferable that the fluorescent material or the phosphorescent material be present on at least the transparent substrate 50a on the conductive electrode side.

In the photoelectric conversion device of the present invention shown in FIG. 1, the light incident on the photosensitive layer 20 containing the semiconductor fine particles 21 sensitized by the dye 22 excites the dye 22 and the like, and the excited dye
High-energy electrons in 22 and the like are transferred to the conduction band of the semiconductor fine particles 21 and further reach the transparent conductive layer 10a by diffusion. At this time, molecules such as the dye 22 are oxidized. In the photovoltaic cell, the electrons in the transparent conductive layer 10a return to an oxidant such as the dye 22 through the counter electrode conductive layer 40 and the charge transfer layer 30 while working in an external circuit, and the dye 22 is regenerated. Photosensitive layer 20
Works as a negative electrode. Boundary of each layer (for example, boundary between transparent conductive layer 10a and photosensitive layer 20, photosensitive layer 20 and charge transfer layer 30
, The boundary between the charge transfer layer 30 and the counter electrode conductive layer 40, etc.), the constituent components of each layer may be mutually diffused and mixed. In the present invention, in addition to the semiconductor or the dye directly absorbing external light, the above-described fluorescent material or light-storing material absorbs higher-energy light (such as ultraviolet light) and has a wavelength (such as a wavelength that the semiconductor or the dye can absorb). (Visible light, near-infrared light) is emitted, and is absorbed by a semiconductor or a dye to improve the energy use efficiency. Hereinafter, each layer will be described in detail.

(A) Transparent substrate In the photoelectric conversion element of the present invention, light is received from the transparent substrate side, and thus the transparent substrate is substantially transparent. Being substantially transparent means that the light transmittance is 10% or more,
It is preferably at least 50%, particularly preferably at least 70%. Transparent substrates include glass substrates such as soda-lime glass, phosphosilicate glass, borosilicate glass, and quartz glass, as well as plastic substrates such as polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyether sulfone, polyarylate, and polycycloolefin. Can be used. A glass substrate is preferable from the viewpoint of durability.

(B) Fluorescent material and luminous material The fluorescent or luminous material used in the present invention is 400 to 900.
Those having substantially no absorption in the range of nm are preferred.
Phosphor or phosphor particles used in ordinary luminous paints have a particle size of about several μm, so that light in this wavelength range is scattered and reflected, so that they are used in photoelectric conversion elements. However, the conversion efficiency is slightly improved. In the present invention, the ratio of the number of particles having an average particle diameter of preferably 1 to 200 nm and having a particle diameter of 400 nm or more is preferably 10 or more.
% Or less, more preferably 5% or less. Such particles, for example, even in a film having a thickness of about several tens of μm, in order to transmit light in the above-mentioned wavelength region, are dispersed in a transparent substrate, adhered to the transparent substrate, or in a transparent binder. Even if the coating material dispersed in is coated on a transparent substrate, the original function as a transparent substrate is not impaired in a light place. It is effective to remove particles having a size of 400 nm or more, preferably 200 nm or more by classification to sharpen the particle size distribution. On the other hand, ultrafine particles of less than 1 nm are not practical because they are difficult to produce and have poor handling properties (dispersibility). The ultrafine particle phosphor or phosphorescent material used in the present invention is prepared, for example, by evaporating in a high-frequency thermal plasma having a temperature of a boiling point or a sublimation point or higher, and then cooling and solidifying as described in JP-A-9-95771. it can. Further, the adhesion to the transparent substrate can be performed by a sputtering method, an ion plating method, a vacuum evaporation method, or the like.

The fluorescent material used in the present invention may be an inorganic fluorescent material, an organic fluorescent pigment, or a combination of both, but an inorganic fluorescent material is preferred from the viewpoint of durability. Also,
The phosphor may be a localized type using a transition metal or a rare earth element as a luminescent center or a non-localized type in which free electrons and holes are involved in a light emitting process. Specific examples of the phosphor include ZnO: Zn, Zn
S: Cl, ZnS: Cu, Al, (Zn, Cd) S: A
g, Cl, SnO ₂ : Eu, Y ₂ O ₂ S: Eu, ZnGa
₂ O ₄ , 3Ca ₃ (PO ₄ ) ₂ .Ca (F, Cl) ₂ : S
b ³⁺ , Mn ²⁺ , Y ₂ O ₃ : Eu ³⁺ , LaPO ₄ : Ce ³⁺ ,
Tb ³⁺ , Zn ₂ SiO ₄ : Mn ^{2+ and the} like. The fluorescent material is described in “Phosphor Handbook”, edited by Phosphors Society of Japan, Ohmsha (1987) and the like.

The luminous material used in the present invention stores ultraviolet light such as sunlight or fluorescent light, and emits light efficiently for a long time when there is little or no visible light. Light absorption-
The cycle of accumulation-emission can be repeated many times. As a specific example of such a material, ZnS: C
u, CaS: Bi, (Ca, Sr) S: Bi, (Ca,
Sr) S: Ce, SrS: Eu, SrAl ₂ O ₄ : Eu,
CaAl ₂ O ₄ : Eu and SrAl ₂ O ₄ : Eu, Dy can be used. In particular, metal oxides such as alumina, strontium oxide, barium oxide, cesium oxide, zinc borosilicate glass, and rare earth elements such as Eu, Dy, Ru, and Tb, which are excellent in luminosity such as luminous luminance and luminous time, on the environmental side and the like. And those obtained by firing are preferred.

These fluorescent materials and phosphorescent materials can be used alone or in combination, or both materials can be used in combination (co-dispersed). In the present invention, a fluorescent material or a phosphorescent material which emits light in a semiconductor absorption region or a sensitizing dye absorption region of a photosensitive layer to be used, specifically, in a wavelength range of 400 to 900 nm, is preferable. In particular, a material having a light emission maximum in this range is preferable.

The above-mentioned fluorescent material or luminous material is contained in a transparent substrate, a fluorescent material or a luminous material is adhered to a transparent substrate (for example, provided in a layered form), dispersed in a transparent binder and dispersed on a transparent substrate. And can be incorporated into the photoelectric conversion element by a method such as coating. In and, it is preferable to install on the surface of the transparent substrate opposite to the conductive electrode (conductive layer). Note that the step of applying a coating material in which a fluorescent or phosphorescent material is dispersed on the surface of the transparent substrate opposite to the conductive electrode surface is preferably performed after the later-described semiconductor layer is installed in order to avoid deterioration due to heating. In the present invention,
The content of the fluorescent or luminous material in the transparent substrate or the transparent binder is not particularly limited, and can be used in a wide range.
Preferably, it is 0.1 to 90% by mass.

In the above case, the transparent binder used is not particularly limited. Specifically, polyvinyl chloride, polyvinylidene chloride, (meth) acrylic resin, epoxy resin, styrene resin, polyurethane, polycarbonate, fluororesin, acrylic silicone resin, unsaturated polyester, and the like can be used. These compounds may be homopolymers or copolymers.

(C) Conductive electrode The conductive electrode is preferably a transparent conductive layer. As the transparent conductive layer, a thin film of a metal or the like, or a transparent conductive metal oxide can be used. Preferred metal thin film materials include, for example, platinum, gold, silver, copper, aluminum, rhodium, indium and carbon, and examples of conductive metal oxides include indium-tin composite oxides and tin oxide doped with fluorine. ). Among these, a transparent conductive layer made of tin dioxide doped with fluorine is preferable.

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

To install a transparent conductive layer on a transparent substrate,
A transparent conductive layer can be formed on the surface of the aforementioned transparent substrate such as glass or plastic by coating or vapor deposition. In order to ensure sufficient transparency, the amount of the conductive metal oxide applied is preferably 0.01 to 100 g per 1 m ² of a glass or plastic support. The thickness of the conductive layer is 0.
About 02 to 10 μm is preferable.

It is preferable to use a metal lead for the purpose of lowering the resistance of the transparent conductive layer. The material of the metal lead is preferably a metal such as aluminum, copper, silver, gold, platinum, and nickel, and particularly preferably aluminum and silver. The metal leads are preferably arranged in a linear or lattice shape 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 preferably provided thereon.
It is also preferable to provide a metal lead on the transparent conductive layer after providing the transparent conductive layer on the transparent substrate. The decrease in the amount of incident light due to the installation of the metal leads is preferably within 10%, more preferably 1 to 5%.

(D) Photosensitive Layer In the photosensitive layer, the semiconductor acts as a so-called photoreceptor, absorbs light to separate charges, and generates electrons and holes. In the dye-sensitized semiconductor fine particles, light absorption and the resulting generation of electrons and holes mainly occur in the dye, and the semiconductor fine particles have a role of receiving and transmitting the electrons. It is preferable that the semiconductor used in the present invention is an n-type semiconductor which gives an anode current by conducting electrons as carriers under photoexcitation.

(1) Semiconductor As the semiconductor, a simple semiconductor such as silicon or germanium, a III-V compound semiconductor, a metal chalcogenide (eg, oxide, sulfide, selenide, etc.), or a compound having a perovskite structure ( For example, strontium titanate, calcium titanate, sodium titanate,
Barium titanate, potassium niobate, etc.) can be used.

The present invention is particularly preferably applied to a photoelectric conversion element and a photovoltaic cell in which a semiconductor selected from metal chalcogenides is dye-sensitized. In this case, it is preferable to select a fluorescent or phosphorescent material that emits light in the absorption region of the sensitizing dye. Preferred metal chalcogenides include titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium, or tantalum oxide, cadmium, zinc, lead, silver, antimony or Examples include bismuth sulfide, cadmium or lead selenide, and cadmium telluride. 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 single crystal or polycrystal. From the viewpoint of conversion efficiency, a single crystal is preferable,
From the viewpoints of production cost, securing of raw materials, energy payback time, and the like, polycrystal is preferable, and a porous film made of semiconductor fine particles is particularly preferable.

The particle size of the semiconductor fine particles is generally on the order of nm to μm, but the average particle size of the primary particles obtained from the diameter when the projected area is converted into a circle is preferably from 5 to 200 nm, and from 8 to 200 nm. 100 nm is more preferred. The average particle size of the semiconductor fine particles (secondary particles) in the dispersion is preferably 0.01 to 100 μm.

Two or more types of fine particles having different particle size distributions may be mixed. In this case, the average size of the small particles is 5 nm.
It is preferred that: For the purpose of improving the light capture rate by scattering incident light, semiconductor particles having a large particle size, for example, about 300 nm may be mixed.

As for the method of producing semiconductor fine particles, there is a method of sol-gel method by Akio Sakuhana, Agne Shofusha (1998), and a thin film coating technique by sol-gel method by the Technical Information Association (1995). ), Tadao Sugimoto, "Synthesis of Monodisperse Particles and Size Morphology Control by New Synthetic Gel-Sol Method", Materia, Vol. 35, No. 9, 1012-1018.
The gel-sol method described on page (1996) is preferred. Also De
Also preferred is a method developed by Gussa to produce oxides by high temperature hydrolysis of chlorides in oxyhydrogen salts.

When the semiconductor fine particles are titanium oxide, any of the above-mentioned sol-gel method, gel-sol method, and high-temperature hydrolysis method in chloride oxyhydrogen salt are preferred. Applied Technology "Gihodo Publishing (1997)
The sulfuric acid method and the chlorine method described in (1) can also be used. Further, the sol-gel method is described in Barb et al., Journal of American Ceramic Society, Vol.
12, No. 3, pp. 3157-3171 (1997), and Burnside et al., Chemistry of Materials, No. 10
Vol. 9, No. 9, pages 2419 to 2425 are also preferable.

(2) Semiconductor fine particle layer In order to coat the semiconductor fine particles on the conductive electrode, in addition to the method of applying a dispersion or colloid solution of the semiconductor fine particles on the conductive electrode, the above-mentioned sol-gel method or the like is used. Can also be used. In consideration of mass production of photoelectric conversion elements, physical properties of semiconductor fine particle liquids, flexibility of conductive electrodes, and the like, a wet film forming method is relatively advantageous. As a wet film forming 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-described sol-gel method, a method of grinding in a mortar, a method of dispersing while pulverizing using a mill, or a method of preparing a solvent when synthesizing a semiconductor. A method of precipitating fine particles in the solution 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.). At the time of dispersion, if necessary, a polymer such as polyethylene glycol, a surfactant, an acid, a chelating agent, or the like may be used as a dispersion aid. By changing the molecular weight of polyethylene glycol, it is possible to form a film that does not easily peel off or to adjust the viscosity of the dispersion liquid. Therefore, it is preferable to add polyethylene glycol.

The application method includes a roller method and a dipping method as an application system, an air knife method and a blade method as a metering system.
-4589, the wire bar method, US Patent 268
The slide hopper method, extrusion method, curtain method, and the like described in Nos. 1294, 2761419, and 2761791 are preferable. As a general-purpose machine, a spin method or a spray method is also preferable. As the wet printing method, intaglio printing, rubber printing, screen printing, and the like are preferable, including three major printing methods of letterpress, offset and gravure. From these, a preferable film forming method is selected according to the liquid viscosity and the wet thickness.

The layer of semiconductor fine particles is not limited to a single layer, but a multi-layer coating of a dispersion of semiconductor fine particles having different particle diameters or a coating layer containing semiconductor fine particles of different types (or different binders and additives) may be formed in multiple layers. It can also be applied. Multilayer coating is effective even when the film thickness is insufficient by one 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 semiconductor fine particle layer (same as the thickness of the photosensitive layer) increases, the amount of the dye carried per unit projected area increases, so that the light capture rate increases, but the diffusion distance of generated electrons increases. Therefore, the loss due to charge recombination also increases. Therefore, the preferred thickness of the semiconductor fine particle layer is
It is 0.1-100 μm. When used for a solar cell, the thickness of the semiconductor fine particle layer is preferably 1 to 30 μm, more preferably 2 to 25 μm. Support 1 m ² per coating amount of the semiconductor fine particles 0.
5 to 400 g is preferable, and 5 to 100 g is more preferable.

After coating the semiconductor fine particles on the conductive electrode, the semiconductor fine particles are brought into electronic contact with each other, and in order to improve the coating strength and the adhesion to the support,
Heat treatment is preferred. The preferred heating temperature range is
40 ° C or more and 700 ° C or less, more preferably 100 ° C or more and 60 ° C or more.
0 ° C or less. The heating time is about 10 minutes to 10 hours. When using a support having a low melting point and softening point such as a polymer film, high temperature treatment causes deterioration of the support,
Not preferred. It is preferable that the temperature be as low as possible from the viewpoint of cost. The lowering of the temperature can be attained by the above-mentioned combined use of small semiconductor particles of 5 nm or less, heat treatment in the presence of a mineral acid, and the like.

For the purpose of increasing the surface area of the semiconductor fine particles after the heat treatment, increasing the purity in the vicinity of the semiconductor fine particles, and increasing the efficiency of electron injection from the dye into the semiconductor fine particles, for example, chemical plating using titanium tetrachloride aqueous solution or titanium plating. Electrochemical plating using an aqueous solution of titanium chloride 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 in a state where the layer of semiconductor fine particles is coated on the support is preferably 10 times or more the projected area,
Further, it is preferably 100 times or more. The upper limit is not particularly limited, but is usually about 1000 times.

(3) Dye The dye used in the photosensitive layer is preferably a metal complex dye, a phthalocyanine dye or a methine dye. 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. The dyes to be mixed and their proportions can be selected so as to match the wavelength range and intensity distribution of the desired light source.

Preferably, such a dye has an appropriate interlocking group for the surface of the semiconductor fine particles. Preferred linking groups include a COOH group, an OH group,
SO ₃ H group, a cyano group, -P (O) (OH) 2 group, -OP (O) (OH) 2 group, or oxime, dioxime, hydroxyquinoline, a π conductivity, such as salicylate and α- ketoenolate Chelating groups. Above all, COOH group, -P
(O) (OH) ₂ group, -OP (O) (OH) ₂ group is 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 for use 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 WO98 / 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:

[0042]

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(However, Ra represents _a hydrogen atom or a substituent, and 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. An unsubstituted aralkyl group, or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, a carboxylic acid group, a phosphate group (these acid groups may form a salt), and an alkyl group And the alkyl part of the aralkyl group may be linear or branched, and the aryl part of the aryl group and 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.

[0045]

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[0046]

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[0047]

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(B) Methine Dye A 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.

As for the viscosity of the dye solution, similarly to the formation of the semiconductor fine particle layer, a high viscosity liquid (for example, 0.01 to 500
For se), various printing methods other than the extrusion method are suitable, and for low-viscosity liquids (for example, 0.1 Poise or less), the slide hopper method, the wire bar method, or the spin method are suitable. It is possible.

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

Since the presence of unadsorbed dye causes disturbance of device performance, it is preferable to remove the dye by washing immediately after adsorption. Using a wet cleaning tank, polar solvents such as acetonitrile,
It is preferable to perform washing with an organic solvent such as an alcohol solvent. Further, in order to increase the adsorption amount of the dye, it is preferable to perform a heat treatment before the adsorption. After the heat treatment, do not return to room temperature to avoid water adsorbing on the surface of the semiconductor fine particles.
Preferably, the dye is adsorbed quickly between 40 and 80 ° C.

The total amount of the dye used is preferably 0.01 to 100 mmol per unit surface area (1 m ² ) of the conductive support. The amount of dye adsorbed on the semiconductor fine particles is 1 g of the semiconductor fine particles.
It is preferably 0.01 to 1 mmol per unit. By using such a dye adsorption amount, a sufficient sensitizing effect in a semiconductor can be obtained. On the other hand, if the amount of the dye is too 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.

For the purpose of reducing the interaction between dyes such as association, a colorless compound may be co-adsorbed on the semiconductor fine particles. Examples of the hydrophobic compound to be co-adsorbed include a steroid compound having a carboxyl group (for example, chenodeoxycholic acid). Further, an ultraviolet absorber can be used in combination.

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-t-butylpyridine, polyvinylpyridine and the like. When these are liquids, they may be used as they are, or may be used after being dissolved in an organic solvent.

(E) Charge Transfer Layer The charge transfer layer is a layer containing a charge transport material having a function of replenishing electrons to the oxidized dye. Examples of typical charge transporting materials that can be used in the present invention include, as an ion transporting material, a solution in which redox pair ions are dissolved (electrolyte solution), and a redox pair solution impregnated in a gel of a polymer matrix. A so-called gel electrolyte, a molten salt electrolyte containing a redox counter ion, and a solid electrolyte can be used. In addition to charge transport materials involving ions,
An electron transporting material or a hole transporting material can also be used as a material in which carrier movement in a solid is related to electric conduction. These can be used in combination.

(1) Molten Salt Electrolyte The molten salt electrolyte is preferable from the viewpoint of achieving both photoelectric conversion efficiency and durability, and it is particularly preferable to use a room temperature molten salt which is in a liquid state near room temperature. Molten salt electrolyte preferably used in the photoelectric conversion element of the present invention, for example, WO95 / 18456
No., JP-A-8-259543, Electrochemistry, Vol. 65, No. 11, 923
Page (1997), iodine salts such as pyridinium salts, imidazolium salts, triazolium salts, etc.
Also, EP 718288, J. Electrochem. Soc., Vol. 143, 3
099 (1996), Inorg. Chem. 1996, 35, 1168-1178.

These molten salts can 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.

It is preferable not to use a solvent for the molten salt electrolyte. Although a solvent described below may be added, the content of the molten salt is preferably 50% by mass or more based on the entire electrolyte composition. Further, it is preferable that 50% by mass or more 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 mass, and more preferably 0.5 to 5% by mass based on the whole electrolyte composition. Is more preferred.

(2) Electrolyte When an electrolyte is used for the charge transfer layer, the electrolyte may be 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 0.1 M or more and 15 M or less, more preferably 0.2 M or more and 10 M 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 dimethyl sulfoxide and sulfolane; and water can be used.

Further, in the present invention, J. Am. Ceram. Soc.,
80 tert- as described in (12) 3157-3171 (1997)
Basic compounds such as butylpyridine, 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. To gel by adding a polymer, use
lymer Electrolyte Revews-1 and 2¨ (JRMacCallu
Compounds described in ELSEVIER APPLIED SCIENCE (co-edited by m and CA Vincent) can be used, and particularly, polyacrylonitrile and polyvinylidene fluoride can be preferably used. For gelation by adding an oil gelling agent, use J. Chem Soc. Japan, Ind. Chem.Sec., 4
6,779 (1943), J. Am. Chem. Soc., 111,5542 (1989), J.
Chem. Soc., Chem. Com mun., 1993, 390, Angew. Che
m. Int. Ed. Engl., 35, 1949 (1996), Chem. Lett., 199
6, 885, J. Chm. Soc., Chem. Commun., 1997, 545, but preferred compounds are those having an amide structure in the molecular structure.

When the electrolyte is gelled by a crosslinking reaction of the polymer, it is desirable to use a polymer having 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.).

(4) Hole Transport Material In the present invention, an organic or inorganic hole transport material or a combination thereof can be used in place of the electrolyte.

(A) Organic hole transporting material The organic hole transporting material applicable to the present invention includes N, N'-
Diphenyl-N, N'-bis (4-methoxyphenyl)-(1,
1'-biphenyl) -4,4'-diamine (J. Hagen et al., Synth
etic Metal 89 (1997) 215-220), 2,2 ', 7,7'-tetrakis (N, N-di-p-methoxyphenylamine) 9,9'-spirobifluorene (Nature, Vol. 395, 8 Oct. 1998, p583-585 and WO97 / 10617), 1,1-bis {4- (di-p-tolylamino)
An aromatic diamine compound in which a tertiary aromatic amine unit of phenyl @ cyclohexane is linked (JP-A-59-194393), and 4,4-bis [(N-1-naphthyl) -N-phenylamino] biphenyl Aromatic amine containing two or more tertiary amines represented by two or more fused aromatic rings substituted with a nitrogen atom (JP-A-5-234681), and a derivative of triphenylbenzene having a starburst structure Aromatic triamine (U.S. Pat. No. 4,923,774, JP-A-4-3086)
No. 88), and aromatic diamines such as N, N′-diphenyl-N, N′-bis (3-methylphenyl)-(1,1′-biphenyl) -4,4′-diamine (US Pat. , 764, 625), α,
α, α ′, α′-Tetramethyl-α, α′-bis (4-di-p-tolylaminophenyl) -p-xylene (JP-A-3-269084), p-phenylenediamine derivative, whole molecule As a sterically asymmetric triphenylamine derivative (Japanese Unexamined Patent Publication No.
JP-A-129271), a compound in which a pyrenyl group is substituted with a plurality of aromatic diamino groups (JP-A-4-175395), and an aromatic diamine in which a tertiary aromatic amine unit is linked by an ethylene group (JP-A-4-264189) JP-A-5-25473, an aromatic diamine having a styryl structure (JP-A-4-290851), a benzylphenyl compound (JP-A-4-364153), and a tertiary amine linked by a fluorene group (JP-A-5-25473).
JP-A-5-320455), triamine compounds (JP-A-5-239455), and pisdipyridylaminobiphenyl (JP-A-5-320).
634), N, N, N-triphenylamine derivatives (JP-A-6-1972), aromatic diamines having a phenoxazine structure (JP-A-7-138562), and diaminophenylphenanthridine derivatives (JP-A-7-138562). The aromatic amines shown in, for example, Kaihei 7-252474) can be preferably used. Α-octylthiophene and α, ω-dihexyl-α
-Octylthiophene (Adv. Mater. 1997, 9, N0.7, p55
7), hexadodecyldodecithiophene (Angew.Chem. In
t. Ed. Engl. 1995, 34, No. 3, p303-307), 2,8-dihexylanthra [2,3-b: 6,7-b '] dithiophene (JACS, Vol12
0, N0.4, 1998, p664-672) and the like,
Polypyrrole (K. Murakoshi et al.,; Chem. Lett. 199
7, p471), ¨ Handbook of Organic Conductive Molec
ules and Polymers Vol.1,2,3,4¨ (by NALWA, published by WILEY) Polyacetylene and its derivatives, poly (p-phenylene) and its derivatives, poly (p-
Conductive polymers such as phenylenevinylene) and derivatives thereof, polythienylenevinylene and derivatives thereof, polythiophene and derivatives thereof, polyaniline and derivatives thereof, and polytoluidine and derivatives thereof can be preferably used. Natur for hole transport material
e, Vol. 395, 8 Oct. 1998, p583-585. To control dopant levels, compounds containing cation radicals such as tris (4-bromophenyl) aminium hexachloroantimonate were used. A salt such as Li [(CF ₃ SO ₂ ) ₂ N] may be added for controlling the potential of the oxide semiconductor surface (compensating for the space charge layer).

(B) Inorganic hole transport material As the inorganic hole transport material, a p-type inorganic compound semiconductor is used.
Can be. Bandgap of p-type inorganic compound semiconductor
The tip is preferably large so as not to hinder dye absorption.
The band gap of the p-type inorganic compound semiconductor is 2 eV or more.
And more preferably 2.5 eV or more.
Good. In addition, ionization potential of p-type inorganic compound semiconductor
Shall uses a dye adsorption electrode to reduce dye holes.
Needs to be smaller than the ionization potential of
Charge transfer by the dye used in the photoelectric conversion device of the present invention
Potential of p-type inorganic compound semiconductor used for layer
The preferred range of the signal varies, but is generally 4.5 eV or less.
It is preferably 5.5 eV or less, and more preferably 4.7 eV or more.
It is preferably 3 eV or less. Preferably used in the present invention
The p-type inorganic compound semiconductor is a compound semiconductor containing monovalent copper.
It is a conductor and as a compound semiconductor containing monovalent copper, CuI,
 CuSCN, CuInSe_Two, Cu (In, Ga) Se_Two, CuGaSe_Two, Cu _TwoO, CuS,
 CuGaS_Two, CuInS_Two, CuAlSe_TwoAnd the like. In this
Also, CuI and CuSCN are preferable, and CuI is most preferable. copper
-Type inorganic compounds that can be used other than compounds containing
As semiconductors, GaP, NiO, CoO, FeO, Bi_TwoO_Three, MoO_Two, C
r_TwoO_ThreeAnd the like. Further, the p-type inorganic material of the present invention
Preferred hole transfer in charge transfer layer containing compound semiconductor
Mobility is 10^-Fourcm^Two/ Vsec or more 10^Fourcm^Two/ V · sec or less,
More preferably 10^-3cm^Two/ Vsec or more 10^Threecm^Two/ V ・ sec or less
Below. Furthermore, the preferred conductivity of the charge transfer layer of the present invention
Rate is 10^-8S / cm or more 10^TwoS / cm or less, more preferably
Is 10^-6It is not less than S / cm and not more than 10 S / cm.

(5) 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 stuck on a semiconductor fine particle-containing layer carrying a sensitizing dye, 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 the semiconductor fine particle-containing 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 due to 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 liquid leakage at the edge. 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 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 (hole) transporting material, the charge transfer layer can be formed by a dry film forming process such as a vacuum evaporation method or a CVD method, and then a counter electrode can be provided. 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, a dipping method, an electrolytic polymerization method, and a photoelectrolytic polymerization method.
In the case of an inorganic solid compound, it can be introduced into 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.

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.

(F) Counter electrode The counter electrode functions as the positive electrode of the photoelectric conversion element. The counter electrode may have a single-layer structure of a counter electrode conductive layer made of a conductive material, or may include a counter electrode conductive layer and a support substrate. As the conductive material used for the counter electrode conductive layer, a metal (for example, platinum, gold, silver, copper, aluminum, magnesium,
Rhodium, indium, etc.), carbon, or a conductive metal oxide (indium-tin composite oxide, tin oxide doped with fluorine, or the like). Among them, platinum,
Gold, silver, copper, aluminum, and magnesium can be preferably used as the counter electrode layer. An example of a preferable support substrate for the counter electrode is glass or plastic, to which the above-described conductive agent is applied or vapor-deposited. In the present invention, a phosphorescent material or a fluorescent material may be present on the support substrate of the counter electrode. The method of causing the light storage material or the fluorescent material to be present on the support substrate of the counter electrode may be the same as that of the above-described transparent substrate on the conductive electrode side when light is also incident from the counter electrode side.
In the case where the light is incident only from the conductive electrode side, the counter electrode support substrate may be light-reflective, and therefore, the size (for example, μm order) larger than the particle size described for the transparent substrate on the conductive electrode side ). The thickness of the counter electrode conductive layer is not particularly limited, but is preferably 3 nm to 10 μm. When the counter electrode conductive layer is made of metal, its thickness is preferably 5 μm or less, more preferably 5 nm.
３3 μm. The lower the surface resistance of the counter electrode layer, the better. The preferred range of the surface resistance is 80 Ω / □ or less, and more preferably 20 Ω / □ or less.

Since light may be irradiated from one or both of the conductive support and the counter electrode, at least one of the conductive support and the counter electrode is substantially transparent in order for the light to reach the photosensitive layer. I just want it. From the viewpoint of improving the power generation efficiency, in the photoelectric conversion element of the present invention, it is preferable that light be incident from the transparent substrate side. In this case, the counter electrode preferably has a property of reflecting light.

As the counter electrode, a conductive material may be applied directly onto the charge transfer layer, plated or vapor-deposited (PVD, CVD), or may be attached to the conductive layer side of the substrate having the conductive layer. Further, as in the case of the conductive electrode, a metal lead may be used for the purpose of reducing the resistance of the counter electrode.

(G) Other Layers When an electron transporting material or a hole transporting material is used for the charge transfer layer, a dense semiconductor is previously placed between the conductive electrode and the photosensitive layer in order to prevent a short circuit between the counter electrode and the conductive electrode. It is preferable that the thin film layer is coated as an undercoat layer. Preferred as the undercoat layer are TiO ₂ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , ZnO and Nb ₂ O ₅ , more preferably TiO ₂ . The undercoat layer is Electroc
himi. Acta 40, 643-652 (1995) can be applied by a spray pyrolysis method. The preferred thickness of the undercoat layer is 5 to 1000 nm or less, more preferably 10 to 500 nm.

A functional layer such as a protective layer or an antireflection layer may be provided on one or both of the conductive support serving as an electrode and the counter electrode. When such a functional layer is formed in multiple layers, a simultaneous multilayer coating method or a sequential coating method can be used. In the simultaneous multi-layer coating method, a slide hopper method or an extrusion method is suitable in consideration of productivity and uniformity of a coating film. In forming these functional layers, an evaporation method, a sticking method, or the like can be used depending on the material. Sealing is performed to join the two electrode substrates, including the charge transfer layer, and to insulate and shield the outside air. The sealing is preferably performed by sealing the periphery of the junction of the element or the battery with a sealant or an adhesive and solidifying the periphery.

(H) Specific Example of Internal Structure of Photoelectric Conversion Element As described above, the internal structure of the photoelectric conversion element can take various forms according to the purpose. When roughly divided into two, a structure in which light can enter from both sides and a structure in which light can be entered only from one side are possible. 2 to 9 exemplify an internal structure of a photoelectric conversion element which can be preferably applied to the present invention. The phosphorescent material or fluorescent material of the present invention is present on the transparent substrate 50a of the following components.

FIG. 2 shows a partially metal lead 1 on a transparent substrate 50a.
1, a transparent conductive layer 10a is further provided, an undercoat layer 60, a photosensitive layer 20, a charge transfer layer 30, and a counter electrode conductive layer 40 are provided in this order, and a support substrate 50 is further provided. Light is incident from the (transparent conductive layer) side. FIG. 3 is a view in which a metal lead 11 is partially provided on a transparent substrate 50a, and a transparent conductive layer 10a is further provided. An undercoat layer 60, a photosensitive layer 20, and a charge transfer layer 30 are interposed between one set. In this structure, light enters from both sides. FIG. 4 shows a photosensitive layer formed on a transparent substrate 50a via a transparent conductive layer 10a and an undercoat layer 60.
20, a charge transfer layer 30 and a counter electrode conductive layer 40 are provided, and a support substrate 50 is disposed thereon, and has a structure in which light is incident from the conductive layer side. FIG. 5 shows a transparent conductive layer 1 on a transparent substrate 50a.
0a, the photosensitive layer 20 is provided via the undercoat layer 60, the charge transfer layer 30 and the transparent counter electrode conductive layer 40a are further provided, and the transparent substrate 50a is disposed thereon, and light is incident from both sides. It has a structure to do.

[2] Photocell The photocell 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, and can have the same module structure as a conventional solar cell.

[0083]

EXAMPLES The effects of the present invention will be specifically described below with reference to examples. In this example, fine particles of n-type semiconductor TiO ₂ were used as the semiconductor for dye sensitization. [Example 1] 1. Preparation of Transparent Glass Substrate Containing Luminescent Material An SrAl ₂ O ₄ : Eu-based luminous material having an average particle diameter of 15 μm was supplied into a high-frequency thermal plasma using a mixed gas of argon gas and oxygen gas as a carrier, evaporated and rapidly cooled. As a result, ultrafine particles were obtained. The ultrafine particles are classified to have an average particle diameter of 5
The ratio of particles having a particle diameter of 0 nm and a particle diameter of 100 nm or more is 5
% Or less. The ultrafine phosphorescent material thus obtained was mixed with a raw material of an alkali-free glass by 0.5% by mass to have a thickness of 1.9.
mm glass substrate was produced. When the visibility of the transparent glass substrate was confirmed, haze was hardly observed and the glass substrate was transparent, and light green light was emitted in a dark place. For comparison, an alkali-free glass substrate containing no luminous material was also prepared.

2. Film formation of transparent conductive film layer (for working electrode) One surface of the transparent glass substrate is uniformly coated with fluorine-doped tin dioxide by CVD method,
Thickness 600nm, sheet resistance about 20Ω / □, light transmittance 85%
(500 nm) conductive tin dioxide film was formed.

3. Installation of Undercoat Layer Titanium dioxide was vacuum-deposited on the transparent conductive electrode to a thickness of 50 nm to form an undercoat layer.

[0086] 4. 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 kneaded to obtain a coating solution.

5. Preparation of Titanium Dioxide Semiconductor Electrode Adsorbing Dye The coating solution prepared in 4 was applied to the undercoat layer of the transparent conductive electrode prepared in 3 above at a thickness of 60 μm by a doctor blade method, and dried at 25 ° C. for 30 minutes. After that, 45
Baking at 0 ° C. for 30 minutes covered the titanium dioxide layer.
The coating amount of titanium dioxide was 9 g / m ² and the film thickness was 6 μm. The above electrode was taken out into dry air and cooled to 120 ° C., and an organic solution of ruthenium complex dye R-1 (dye concentration: 3 × 10 ⁻⁴ mol / l, mixed solvent of acetonitrile: t-butanol (1: 1)) ) And left at 40 ° C. for 12 hours. The semiconductor electrode to which the dye was dyed in this way was washed with ethanol and dried naturally in a dark place. The amount of the dye adsorbed was about 1.5 × 10 ⁻³ mol per 1 m ^{2 of the} titanium dioxide coated area.

6. Fabrication of Photovoltaic Cell A dye-sensitized TiO ₂ electrode substrate (2 cm × 1.5 cm) produced as described above was combined with a counter electrode (glass substrate with a 400 nm-thick platinum layer) of the same size as the above, and thermocompression bonding. A frame-type spacer made of polyethylene film (thickness: 20 μm) is inserted and overlapped, and the terminal ends (width 2 mm) of both substrates are alternately put out in the long side direction.
The substrates were heated to 120 ° C. and pressed together (see FIG. 1). The entire cell was sealed with an epoxy resin adhesive except for the surface of the transparent glass substrate as a light receiving part. Next, a small hole for liquid injection is made on the side surface of the spacer, and a room temperature molten salt, a molten salt (A): a molten salt (B): iodine = 15: An electrolyte having a composition of 35: 1 (mass ratio) was impregnated. The above cell assembly process,
All the steps of electrolyte injection were performed in dry air at the above dew point of -60 ° C. After the injection of the molten salt, the cell was suctioned for several hours under vacuum to deaerate the inside of the cell including the porous electrode and the molten salt, and finally the small holes were sealed with low-melting glass. In this way, the light receiving area is about 2 cm ² , and as shown in the layer configuration shown in FIG.
a, transparent conductive film layer 10a, undercoat layer 60, photosensitive layer (dye adsorption T
iO ₂ layer) 20, charge transfer layer 30, counter electrode conductive layer (platinum layer) 40
Then, a photovoltaic cell in which the support substrate 50 was sequentially stacked was assembled.

[0089]

Embedded image

7. Measurement of photoelectric conversion efficiency A 500 W xenon lamp (USHIO Inc.) and a correction filter for sunlight simulation (AM manufactured by Oriel)
1.5D), and the incident light intensity on the battery is 100 mW
Simulated sunlight adjusted to / cm ² was irradiated. Ohmic contact was made with a conductive wire to the terminal provided at the end of the glass substrate with a transparent conductive film and the support substrate with a platinum film of the fabricated photovoltaic cell,
The electrical response of both electrodes was input to a current / voltage measuring device (Keisley source measure unit type 238). Irradiation light from a light source was incident on the transparent electrode (transparent glass substrate) side of the battery, and current-voltage characteristics were measured. The open-circuit voltage (Voc), short-circuit current density (Jsc), shape factor (FF), and conversion efficiency (η) of the photovoltaic cell thus determined are collectively shown in Table 1. The number of the photovoltaic cell produced using the transparent glass substrate containing the luminous material of the present invention was designated as A1, and the number of the comparative photocell produced using a normal glass substrate containing no luminous material was designated as Comparative 1.

8. Evaluation of Light Durability The assembled cell was put into a Xe lamp light resistance tester with an illuminance of 85000 lx, and the light durability was evaluated. The tester was composed of a cycle of 3.5 hours of exposure and 1 hour of standing in the dark, and the temperature of the atmosphere was adjusted to 30 ° C. and the humidity was adjusted to 80 to 100%. When a forced light resistance test was performed for 10 days using this tester, the energy conversion efficiencies before and after the test and the rate of change thereof were measured. The results are shown in Table 1.

Example 2 The ultrafine SrAl ₂ O ₄ : Eu-based phosphorescent material prepared in Example 1 or the ultrafine Y ₂ O ₃ : Eu-based fluorescent material prepared in the same manner as in Example 1 was methyl methacrylate / butyl methacrylate. Each of them was separately dispersed at a ratio of 2% by mass in a copolymer binder, and applied to a surface of the non-alkali glass substrate opposite to the transparent conductive film to a thickness of 5 μm. Note that this coating was performed after the step of preparing the titanium dioxide semiconductor electrode adsorbing the above-mentioned 5 dye. A photovoltaic cell was produced in the same manner as in Example 1 except that the glass substrate coated with the above-described phosphorescent material or the fluorescent material was used instead of the transparent glass substrate containing the phosphorescent material used in Example 1 (the phosphorescent material was applied). The number of the photovoltaic cell obtained was A2, and the number of the photovoltaic cell coated with the fluorescent material was B1). The results are also shown in Table 1.

[0093]

[Table 1]

From the results of the above examples, it can be seen that the photovoltaic cell having the structure shown in the present invention provides more excellent performance in conversion of sunlight and storage durability. In addition, it was also found that the photocells A1 and A2 using the luminous material emit green light for a long time even in a dark place, so that they can be used both as guide lights and guide signs.

[0095]

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

FIG. 2 is a partial sectional view showing the structure of a preferred photoelectric conversion element of the present invention.

FIG. 3 is a partial sectional view showing the structure of a preferred photoelectric conversion element of the present invention.

FIG. 4 is a partial sectional view showing the structure of a preferred photoelectric conversion element of the present invention.

FIG. 5 is a partial sectional view showing the structure of a preferred photoelectric conversion element of the present invention.

[Explanation of symbols]

10a ・ ・ ・ Transparent conductive layer 11 ・ ・ ・ Metal lead 20 ・ ・ ・ Photosensitive layer 21 ・ ・ ・ Semiconductor fine particles 22 ・ ・ ・ Dye 23 ・ ・ ・ Charge transport material 30 ・ ・ ・ Charge transfer layer 40 ・ ・ ・ Counter electrode conductivity Layer 40a: Transparent counter electrode conductive layer 50: Support substrate 50a: Transparent substrate (containing or coated with a phosphorescent or fluorescent material) 60: Undercoat layer

Claims (8)

[Claims] 1. A photoelectric conversion element having at least a transparent substrate, a conductive electrode provided on the transparent substrate, a photosensitive layer containing a semiconductor, and a counter electrode, wherein a fluorescent material or a phosphorescent material is contained in or on the transparent substrate. Alternatively, a photoelectric conversion element characterized by being present in a counter electrode. 2. The transparent substrate according to claim 1, wherein the fluorescent material or the phosphorescent material is dispersed in a transparent binder and applied to a surface of the transparent substrate opposite to the conductive electrode. Photoelectric conversion element. 3. The photoelectric conversion element according to claim 1, wherein the semiconductor is a porous semiconductor containing at least one kind of metal chalcogenide, and a dye is adsorbed on the semiconductor. . 4. The photoelectric conversion device according to claim 1, wherein the photoelectric conversion device has a charge transfer layer between a photosensitive layer and a counter electrode. 5. The method according to claim 1, wherein the fluorescent material or the phosphorescent material is 1 to 200.
having an average particle size in the range of nm and a particle size of 400 n
The photoelectric conversion element according to any one of claims 1 to 4, wherein the ratio of the number of particles having a particle size of m or more is 10% or less. 6. The fluorescent material or the phosphorescent material is 400 to 9
The photoelectric conversion device according to claim 1, wherein the photoelectric conversion device emits light in a wavelength range of 00 nm. 7. The photoelectric conversion device according to claim 1, wherein the fluorescent material or the luminous material is an inorganic compound. 8. A photovoltaic cell using the photoelectric conversion element according to claim 1.