JP2001185743A - Photoelectric conversion element and solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pigment-intensified photoelectric conversion element having a high photoelectric conversion power and a high durability and a solar cell using the same by overcoming the disadvantage that the photoelectric conversion efficiency and the durability were not compatible as found in the conventional pigment-intensified photoelectric conversion element. SOLUTION: In the pigment-intensified photoelectric conversion element having a conductive support, a photosensitive layer containing semiconductor particles having adsorbed pigments, a charge transfer layer and a counter electrode, a p-type inorganic compound semiconductor and a nitrile compound are contained in the charge transfer layer to constitute a photoelectric conversion element and a solar cell.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photoelectric conversion device using semiconductor fine particles sensitized with a dye. Furthermore, the present invention relates to a solar cell and a solar cell module using the same.

[0002]

2. Description of the Related Art Photovoltaic power generation is a single-crystal silicon solar cell,
Polycrystalline silicon solar cells, amorphous silicon solar cells, and compound solar cells such as cadmium telluride and indium copper selenide have been put into practical use or subject to major research and development.
It is necessary to overcome problems such as a long energy payback time. On the other hand, many solar cells using an organic material intended to have a large area and a low price have been proposed so far, but have a problem that conversion efficiency is low and durability is poor. Under these circumstances, Nature (Vol. 353, 737
Pp. 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, as well as materials and manufacturing techniques for producing the same. The proposed battery 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 purification to a high degree of purity, so that an inexpensive photoelectric conversion element can be provided. Since the absorption of the dye is broad, it is possible to convert light in almost all visible wavelength regions into electricity. However, since this element is a wet type solar cell in which an electrical connection with the counter electrode is made by using an electrolyte solution, there is a concern that when used for a long period of time, the photoelectric conversion efficiency will be significantly reduced due to the exhaustion of the electrolyte, or the element will not function as an element. Have been. J. Phys. D: Appl. Phys. 31 (1998) 1492-1496 proposes a solid-state photoelectric conversion device using CuI as a hole transport material to prevent electrolyte depletion over time in wet solar cells. ing. However, as a result of examination, photoelectric conversion elements using these hole transport materials showed that
It has been found that there is a problem that the photoelectric conversion characteristics such as (Jsc) are significantly deteriorated.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned drawbacks of the dye-sensitized photoelectric conversion element and to provide a dye-sensitized photoelectric conversion element having excellent durability and a solar cell using the same. It is to provide.

[0004]

The object of the present invention is achieved by the following items that specify the present invention. (1) In a dye-sensitized photoelectric conversion device having a conductive support, a photosensitive layer containing dye-adsorbed semiconductor fine particles, a charge transfer layer, and a counter electrode, the charge transfer layer comprises a p-type inorganic compound semiconductor and a nitrile compound. A photoelectric conversion element comprising: (2) The band gap of the p-type inorganic compound semiconductor is 2e
V. The photoelectric conversion element according to the above (1), which is not less than V. (3) The photoelectric conversion element according to (1) or (2), wherein the ionization potential of the p-type inorganic compound semiconductor is 4.5 eV or more and 5.5 eV or less. (4) The photoelectric conversion element according to (1), (2) or (3), wherein the p-type inorganic compound semiconductor is a compound semiconductor containing monovalent copper. (5) The photoelectric conversion element according to (4), wherein the compound semiconductor containing monovalent copper is CuI. (6) The photoelectric conversion element according to (4), wherein the compound semiconductor containing monovalent copper is CuSCN. (7) The photoelectric conversion element according to any one of (1) to (6), wherein the nitrile compound is solid at room temperature. (8) The photoelectric conversion element according to any one of (1) to (7), wherein the nitrile compound is a polynitrile compound. (9) The photoelectric conversion element according to any one of (1) to (8), wherein the nitrile compound is an organic hole transport material. (10) The photoelectric conversion element according to any one of (1) to (9), wherein the nitrile compound is a compound represented by the following general formula (1).

[0005]

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[Wherein, R _{11 to} R ₁₆ each represent a substituent,
n ₁₁ and n _{12 each} represent an integer of 0 to 4, and n _{13 to} n _{16 each} represent an integer of 0 to 5. R ₁₁ and R ₁₂ may combine with each other to form a ring. However, at least one of n _{11 to} n ₁₆ is not 0, and at least one of R _{11 to} R ₁₆ is a substituent having a cyano group. (11) The photoelectric conversion according to any one of (1) to (10), wherein a mass composition ratio of the nitrile compound is 0.01% by mass or more and 50% by mass or less based on the p-type inorganic compound semiconductor. element. (12) The photoelectric conversion element according to any one of (1) to (11), wherein an undercoat layer made of an oxide semiconductor is provided between the conductive support and the photosensitive layer. (13) The photoelectric conversion element according to any one of (1) to (12), wherein the dye is a ruthenium complex dye. (14) The photoelectric conversion element according to any one of (1) to (13), wherein the semiconductor fine particles are titanium dioxide fine particles. (15) A solar cell using the photoelectric conversion element described in any one of (1) to (14). (16) A solar cell module comprising the photoelectric conversion element according to any one of (1) to (14).

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [1] Photoelectric conversion element The photoelectric conversion element of the present invention comprises a conductive support, a photosensitive layer containing semiconductor fine particles having a dye adsorbed thereon, a charge transfer layer, and a counter electrode. Charge transport material (hole transport material)
Contains a p-type inorganic compound semiconductor, and additionally contains a nitrile compound. Preferably, as shown in FIG. 1, a conductive layer 10, an undercoat layer 60, a photosensitive layer 20, a charge transfer layer 30, and a counter electrode conductive layer 40 are laminated in this order, and the photosensitive layer 20 is dyed.
Charge transporting material permeated from the charge transfer layer into the gap between the semiconductor fine particles 21 sensitized by 22 and the semiconductor fine particles 21
23. The charge transport material 23 is composed of the same components as the materials used for the charge transfer layer 30. Further, a substrate 50 may be provided on the conductive layer 10 side and / or the counter electrode conductive layer 40 side in order to impart strength to the photoelectric conversion element. Hereinafter, in the present invention, a layer composed of the conductive layer 10 and the optional substrate 50 is referred to as a “conductive support”, and a layer composed of the counter electrode conductive layer 40 and the optional substrate 50 is referred to as a “counter electrode”. What connects this photoelectric conversion element to an external circuit to perform work is a solar cell. The conductive layer 10, the counter electrode conductive layer 40, and the substrate 50 in FIG.
May be a transparent conductive layer 10a, a transparent counter electrode conductive layer 40a, and a transparent substrate 50a, respectively.

In the photoelectric conversion device of the present invention shown in FIG. 1, 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 conductive layer 10 by diffusion. At this time, molecules such as the dye 22 are oxidized. In the solar cell, the electrons in the conductive layer 10 return to an oxidant such as the dye 22 via the counter electrode conductive layer 40 and the charge transfer layer 30 while working in an external circuit, and the dye 22 is regenerated. The photosensitive layer 20 functions as a negative electrode. Each layer boundary (for example, conductive layer 10 and photosensitive layer 20)
, The boundary between the photosensitive layer 20 and the charge transfer layer 30, the boundary between the charge transfer layer 30 and the counter electrode conductive layer 40, etc.), the components of each layer may be mutually diffused and mixed. Hereinafter, each layer will be described in detail.

(A) Charge Transfer Layer The charge transfer layer in the present invention is a layer having a function of rapidly reducing the oxidized form of the dye and transporting the holes injected at the interface with the dye to the counter electrode. The charge transfer layer of the present invention is mainly composed of a p-type compound semiconductor as a hole transport material and a nitrile compound.

(1) P-type inorganic compound semiconductor The band gap of the p-type inorganic compound semiconductor is preferably large so as not to hinder dye absorption. P used in the present invention
The band gap of the type inorganic compound semiconductor is preferably 2 eV or more, and more preferably 2.5 eV or more. Further, the ionization potential of the p-type inorganic compound semiconductor needs to be smaller than the ionization potential of the dye adsorption electrode in order to reduce dye holes. The preferred range of the ionization potential of the p-type inorganic compound semiconductor used in the charge transfer layer varies depending on the dye used in the photoelectric conversion element of the present invention, but is generally 4.5 eV or more.
It is preferably 5.5 eV or less, more preferably 4.7 eV or more.
It is preferably at most 3 eV. The p-type inorganic compound semiconductor preferably used in the present invention is a compound semiconductor containing monovalent copper, and the compound semiconductor containing monovalent copper is CuI
, CuSCN, CuInSe ₂ , Cu (In, Ga) Se ₂ , CuGaSe ₂ , Cu ₂ O
, CuS, CuGaS ₂ , CuInS ₂ , CuAlSe ₂ , and the like. Among them, CuI and CuSCN are preferred, and CuI
Is most preferred. Examples of the p-type inorganic compound semiconductor that can be used other than the compound containing copper include GaP, NiO, and CoO.
, FeO, Bi ₂ O ₃ , MoO ₂ , Cr ₂ O _{3 and the} like. Further, the charge transport layer containing the p-type inorganic compound semiconductor of the present invention preferably has a hole mobility of 10 ^-4 cm ² / Vsec or more and 10 ⁴ cm ² / Vsec or less, more preferably 10 ^-3 cm / Vsec or less. cm
It is not less than ² / V · sec and not more than 10 ³ cm ² / V · sec. Further, the preferred conductivity of the charge transfer layer of the present invention is 10 ^-8 S / cm or more and 10 ² S
/ cm or less, more preferably 10 ^-6 S / cm or more and 10 S / cm
It is as follows.

(2) Nitrile compound The nitrile compound used in the present invention is an organic compound having a cyano group, and is preferably an organic nitrile compound which is solid at room temperature. A polynitrile compound having two or more cyano groups is more preferable than a mononitrile compound having one cyano group. Further, as the nitrile compound of the present invention, an organic hole transporting material substituted with a cyano group is preferable, and in this case, an organic hole transporting material substituted with two or more cyano groups is more preferable. Examples of the organic hole transporting material include a polypyrrole derivative, a polythiophene derivative, a polyaniline derivative, a polyacetylene derivative, and a triarylamine derivative, and a triarylamine derivative is particularly preferred.

Among the triarylamine derivatives, a triarylamine-based nitrile compound represented by the following general formula (1) is particularly preferably used in the present invention.

[0013]

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In the formula, R _{11 to} R ₁₆ each represent a substituent;
_11, n ₁₂ represents an integer of 0~4, n ₁₃ ~n ₁₆ represents an integer of 0 to 5. R ₁₁ and R ₁₂ may combine with each other to form a ring. However, at least one of n _{11 to} n ₁₆ is not 0, and at least one of R _{11 to} R ₁₆ is a substituent having a cyano group, and n of the substituent having the cyano group (for example, R _In the case of ₁₁ , n ₁₁ ) is at least 1. n ₁₁ ,
n ₁₂ is preferably 0 or 1, and n _{13 to} n ₁₆ are preferably 1.

Examples of the substituents represented by R _{11 to} R ₁₆ include halogen atoms (F, Cl, Br, I, etc.), cyano groups, alkoxy groups (methoxy, ethoxy groups, etc.), aryloxy groups (phenoxy groups, etc.). Group), alkylthio group (methylthio group, ethylthio group, etc.), alkoxycarbonyl group (ethoxycarbonyl group, etc.), 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.), carbamoy Group (N, N-dimethylcarbamoyl group etc.), alkyl group (methyl group, ethyl group, propyl group, isopropyl group, butyl group, t-butyl group, cyclopropyl group, cyclohexyl group, benzyl group etc.), aryl group ( A phenyl group, a toluyl group, a naphthyl group, etc.), a heterocyclic group (pyridyl group, imidazolyl group, furanyl group, etc.), an alkenyl group (vinyl group, 1-propenyl group, etc.) and the like. These may further have the above substituents. Examples of the substituent having a cyano group include the above-described substituents having a cyano group such as a cyanoalkyl group, a cyanoaryl group, a cyanoalkoxy group, and a cyanoaryloxy group, in addition to the cyano group itself. The number of carbon atoms in the alkyl moiety of the above substituent is preferably 1 to 30, more preferably 1 to 12, particularly preferably 1 to 6,
Further, the carbon number of the aryl portion of the above substituent is preferably 6 to 30, more preferably 6 to 20, and particularly preferably 6 to 20.
~ 12. R ₁₁ and R ₁₂ are preferably unsubstituted (n ₁₁ , n
Both ₁₂ are 0) or R ₁₁ and R ₁₂ can be closed to form a methylene group or the like. R _{13 to} R ₁₆ are preferably a cyanoalkoxy group (cyanomethoxy group, cyanoethoxy group, cyanopropoxy group, etc.). When n ₁₁ and n ₁₂ are both 0 or R ₁₁ and R ₁₂ are closed to form a methylene group,
_{13 to} R ₁₆ are a cyanoalkoxy group, and n _{13 to} n ₁₆
Is preferably 1.

Hereinafter, specific examples of the nitrile compound of the present invention will be shown, but the present invention is not limited thereto.

[0017]

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[0018]

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In addition to the above, at least one hydrogen of --OH of saccharides such as sucrose, cellulose, hydroxyethylcellulose, amylose, hydroxypropylamylose, pullulan, and glycidol pullulan, or alcohols such as sorbitol and polyvinyl alcohol is substituted with a cyanoalkyl group. Compounds substituted with (for example, a cyanoethyl group) are also examples of preferred nitrile compounds. Representative examples are shown below. Nitrile compound (16): Cyanoethylated sucrose (CR-U) manufactured by Shin-Etsu Chemical Co., Ltd. Nitrile compound (17): Cyanoethylated pullulan (CR-S) manufactured by Shin-Etsu Chemical Co., Ltd. Nitrile compound (18): Shin-Etsu Chemical ( Cyanoethylated HEC (CR-E) Co., Ltd. When these nitrile compounds are used in combination with the p-type inorganic compound semiconductor of the present invention, the nitrile compounds may be used alone or in combination of two or more. Well.

(3) Formation of Charge Transfer Layer The mass composition ratio of the nitrile compound in the charge transfer layer is as follows:
0.01 to 50% by mass based on p-type inorganic compound semiconductor
Is preferably 0.1% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 10% by mass or less.

Further, the charge transfer layer of the present invention comprises an acceptor
Doping to improve carrier concentration and conductivity
This can be done as needed. Dopa of the present invention
Iodine, tris
(4-bromophenyl) aminium hexachloroanti
Monate, NOPF₆ , SbCl_Five , I_Two, Br_Two , HClO_Four , (N-C_FourH
₉)_FourClO_Four , Trifluoroacetic acid, 4-dodecylbenzenes
Sulfonic acid, 1-naphthalenesulfonic acid, FeCl_Three , AuCl
_Three , NOSbF₆, AsF_Five, NOBF_Four , LiBF_Four , H_Three[PMo₁₂O₄₀], 7,
7,8,8-tetracyanoquinodimethane (TCNQ), fullerene
C60 and the like, but are not limited thereto. Do
When adding punt, the preferable addition amount is p-type inorganic compound.
Not less than 0.0001% by mass and not more than 5% by mass
More preferably, the range is 0.001% by mass or more and 3% by mass or less.
Below.

The preferred thickness of the charge transfer layer of the present invention is 0.1 as a thickness between the semiconductor fine particle layer adsorbing the dye and the counter electrode.
005 μm or more and 100 μm or less, more preferably 0.
It is from 01 μm to 50 μm.

The charge transfer layer containing the p-type inorganic compound semiconductor and the nitrile compound of the present invention can be formed by any of the following three methods. (Formation method 1) Simultaneous formation method: A solution or dispersion containing a p-type inorganic compound semiconductor and a nitrile compound is applied on a dye adsorption electrode substrate to form a charge transfer layer containing both. (Formation Method 2) P-type Inorganic Compound Semiconductor / Nitrile Compound Sequential Formation Method: A p-type inorganic compound semiconductor is previously deposited on a dye-adsorbing electrode substrate, and then formed by overcoating a nitrile compound. (Formation method 3) Nitrile compound / p-type inorganic compound semiconductor successive formation method: After depositing a nitrile compound on a dye adsorption electrode substrate, a p-type inorganic compound semiconductor layer is formed thereon.

(Formation method 1) can be performed using a coating method. When the charge transfer layer is formed by a coating method, a binder resin that does not easily trap holes as necessary,
A coating solution containing additives such as a coating agent such as a leveling agent and a surfactant is added, and a spin coating method, a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, and a wire bar coating method are prepared. The charge transfer layer can be formed by coating using a gravure coating method or an extrusion coating method using a hopper described in US Pat. No. 2,681,294. Solvents or dispersion media preferably used for coating include acetonitrile, methoxyacetonitrile, methoxypropionitrile, pyridine and the like, among which acetonitrile is particularly preferred. In the present invention, it is preferable to heat the dye-adsorbing electrode during coating. The preferred substrate temperature during coating is from 15 ° C to 200 ° C, more preferably from 40 ° C to 150 ° C.

The p-type inorganic compound semiconductor layer in (Formation Method 2) is formed by a vacuum evaporation method, a sputtering method, a casting method,
It can be formed using a coating method, a spin coating method, a dipping method, or an electrolytic plating method. When a p-type inorganic compound semiconductor layer is formed by a vacuum deposition method, a boat heating temperature is generally 50 to 400 on an inorganic oxide electrode substrate supporting a sensitizing dye.
° C, vacuum degree 10 ^-6 to 10 ^-3 Pa, deposition rate 0.01 to 50 nm / sec,
Vapor deposition can be performed by appropriately selecting the vapor deposition conditions within the range of the substrate temperature of -50 to + 300 ° C. and the film thickness of 5 nm to 20 μm. The overcoating of the nitrile compound in (Formation Method 2) is preferably performed by using the coating method described in (Formation Method 1).

The deposition of the nitrile compound in the (formation method 3) is preferably performed by a casting method, a spin coating method, an immersion method, or the like. The subsequent formation of the p-type inorganic compound semiconductor layer can be performed by a vacuum evaporation method, a sputtering method, a casting method, or a coating method. In the formation method 2 and the formation method 3, the nitrile compound and the p-type inorganic compound semiconductor may be separated from each other to form a layered structure, or may have a layered structure in which they penetrate each other to form a single layer.

(B) Conductive Support The conductive support comprises (1) a single layer of a conductive layer, or (2) two layers of a conductive layer and a substrate. A substrate is not necessarily required if a conductive layer that maintains sufficient strength and sealing properties is used.

In the case of (1), a conductive layer having sufficient strength, such as metal, and having conductivity is used as the conductive layer.

In the case of (2), a substrate having a conductive layer containing a conductive agent on the photosensitive layer side can be used. Preferred conductive agents are metals (for example, platinum, gold, silver, copper, aluminum, rhodium, indium, etc.), carbon, or conductive metal oxides (indium-tin composite oxide, tin oxide doped with fluorine, etc.). Is mentioned. The thickness of the conductive layer is preferably about 0.02 to 10 μm.

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

When light is irradiated from the conductive support side, the conductive support is preferably substantially transparent.
Substantially transparent means that the light transmittance is 10% or more, preferably 50% or more, and particularly preferably 70% or more.

As the transparent conductive support, it is preferable to form a transparent conductive layer made of a conductive metal oxide on the surface of a transparent substrate such as glass or plastic by coating or vapor deposition. Of these, conductive glass in which a conductive layer made of tin dioxide doped with fluorine is deposited on a transparent substrate made of low-cost soda-lime float glass is preferable. For a low-cost and flexible photoelectric conversion element or solar cell, a transparent polymer film provided with a conductive layer is preferably used. Transparent polymer film materials include tetraacetyl cellulose (TAC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and syndiotactic polysterene (SP
S), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate (PAr), polysulfone (PS
F), polyester sulfone (PES), polyetherimide (PEI), cyclic polyolefin, brominated phenoxy and the like. To ensure sufficient transparency, the amount of conductive metal oxide applied should be 1 m ² of glass or plastic support.
It is preferably 0.01 to 100 g per unit.

It is preferable to use a metal lead for the purpose of lowering the resistance of the transparent conductive support. 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 lead is preferably provided on a transparent substrate by vapor deposition, sputtering, or the like, and a transparent conductive layer made of tin oxide doped with fluorine or an ITO film is 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%.

(C) Photosensitive Layer In the photosensitive layer, the semiconductor fine particles act as a so-called photoreceptor, absorb light to separate charges, and generate 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.

(1) Semiconductor Fine Particles Semiconductor fine particles include a simple semiconductor such as silicon or germanium, a III-V compound semiconductor, a metal chalcogenide (eg, oxide, sulfide, selenide, etc.), or a perovskite structure. Compounds (for example, strontium titanate, calcium titanate, sodium titanate, barium titanate, potassium niobate, etc.) can be used.

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

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 , Cd
S, ZnS, PbS, Bi_TwoS_Three , CdSe, CdTe, GaP, InP, Ga
As, CuInS_Two, CuInSe_Two Etc., more preferably TiO_Two,
ZnO, SnO_Two, Fe_TwoO_Three , WO_Three , Nb _TwoO_Five , CdS, PbS, CdS
e, InP, GaAs, CuInS_TwoOr CuInSe_Two Especially good
Preferably TiO_TwoOr Nb_TwoO_Five And most preferably TiO_Two
It 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,
Polycrystal is preferred from the viewpoints of production cost, securing of raw materials, energy payback time and the like.

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 kinds 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 a method for producing semiconductor fine particles, Sakuhana Shizuo's "Sol-Gel Method Science" Agne Shofusha (1998), Technical Information Association "Sol-Gel Method for Thin Film Coating" (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 a chloride oxyhydrogen salt is preferable. 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 support, in addition to the method of coating a dispersion or colloidal solution of the semiconductor fine particles on the conductive support, the above-mentioned sol-gel is used. A method can also be used. In consideration of mass production of photoelectric conversion elements, physical properties of semiconductor fine particle liquid, flexibility of a conductive support, 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-mentioned sol-gel method, a method of grinding with a mortar, a method of dispersing while pulverizing with a mill, or a solvent for 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, US Patent No.
The slide hopper method, extrusion method, curtain method and the like described in Nos. 81294, 2761419 and 2761791 are preferred. 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 viscosity of the dispersion of semiconductor fine particles greatly depends on the type and dispersibility of the semiconductor fine particles, the type of solvent used, and additives such as a surfactant and a binder. For a high viscosity liquid (for example, 0.01 to 500 Poise), an extrusion method, a casting method, a screen printing method, or the like is preferable. For a low-viscosity liquid (for example, 0.1 Poise or less), a slide hopper method, a wire bar method, or a spin method is preferable, and a uniform film can be formed. If a certain amount of coating is used, application by the extrusion method is possible even in the case of a low-viscosity liquid. As described above, a wet film forming method may be appropriately selected according to the viscosity of the coating solution, the coating amount, the support, the coating speed, and the like.

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) becomes larger, the amount of 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
0.1 to 100 μm. When used in a solar cell, the thickness of the semiconductor fine particle layer is preferably 1 to 30 μm, and 1.5 to 25 μm.
Is more preferred. Support 1 m ² per coating amount of the semiconductor fine particles is preferably from 0.5 ~400g, 3~100g is more preferable.

After applying the semiconductor fine particles on the conductive support, the semiconductor fine particles are brought into electronic contact with each other,
Heat treatment is preferably performed to improve the strength of the coating film and the adhesion to the support. The preferred heating temperature range is from 40 ° C to 700 ° C, more preferably 100 ° C.
Not less than 600 ° C. The heating time is about 10 minutes to 10 hours. When a support having a low melting point or softening point such as a polymer film is used, high-temperature treatment is not preferable because it causes deterioration of the support. It is preferable that the temperature be as low as possible from the viewpoint of cost. The lowering temperature is 5 nm as described above.
This can be achieved by the use of the following small semiconductor fine particles in combination or heat treatment in the presence of a mineral acid.

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 improving the efficiency of electron injection from the dye into the semiconductor fine particles, for example, a chemical plating treatment using an aqueous solution of titanium tetrachloride or a titanium plating method. Electrochemical plating using an aqueous solution of titanium chloride may be performed.

The semiconductor fine particles preferably 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.

Such a dye preferably 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 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, 4,845,537 and 5,084,365
No. 5350644, No. 5463057, No. 5525440, JP-A-7-249790, JP-T10-504512, World Patent 98/50393
And the like.

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
l, SCN, H ₂ represents O, Br, I, CN, a ligand selected from the group consisting of NCO and SeCN, p is an integer of 0 to 3. Ba, Bb and Bc are each independently the following formula B-1
~ B-8:

[0058]

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(Provided that 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, 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 B-
c 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.

[0061]

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[0062]

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[0063]

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(B) Methine Dye The methine dye preferably used in the present invention is described 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
By Heterogeneous Cyclic Compounds Special Topics in Complex Cyclic Chemistry
(Heterocyclic Compounds-Special topics in heterocy
clic chemistry ", Chapter 18, Section 14, pp. 482-515, John Willy and Sons.
Wiley & Sons)-New York, London, 1977
Annual, `` Rodd's Chemistry of Carbon Compounds '' 2n
d.Ed.vol.IV, part B, 1977, Chapter 15, Chapter 369
422 pages, Elsevier Science Public
Company Inc. (Elsevier Science Publishing Com
Pany Inc.), New York, UK Patent 1,077,611
No. Ukrainskii Khimicheskii Zhurnal, Vol. 40, No. 3
No. 253-258, Dyes and Pigments, Vol. 21,
227-234 and 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.

Regarding 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 coating solution of the dye, 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 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 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.

(D) Counter electrode When the photoelectric conversion element is a solar cell, the counter electrode acts as a positive electrode of the solar cell. The counter electrode may have a single-layer structure of a counter electrode conductive layer made of a conductive material, or may be composed of a counter electrode conductive layer and a support substrate, similarly to the above-described conductive support. Examples of the conductive material used for the counter electrode conductive layer include metals (eg, platinum, gold, silver, copper, aluminum, magnesium, rhodium, indium, and the like), carbon, and conductive metal oxides (indium-tin composite oxide, tin oxide). And the like doped with fluorine). 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. 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 to 3 nm.
μm range. 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 emitted from one or both of the conductive support and the counter electrode, at least one of the conductive support and the counter electrode must be substantially transparent in order for the light to reach the photosensitive layer. I just want it. From the viewpoint of improving power generation efficiency,
It is preferable that the conductive support is made transparent and light is incident from the conductive support side. In this case, the counter electrode preferably has a property of reflecting light. As such a counter electrode, glass or plastic on which a metal or a conductive oxide is deposited, or a metal thin film can be used.

As the counter electrode, a conductive material may be applied directly on 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. Also, as in the case of the conductive support, especially when the counter electrode is transparent,
It is preferable to use a metal lead for the purpose of reducing the resistance of the counter electrode. Note that the preferable material and the installation method of the metal lead, the decrease in the amount of incident light due to the installation of the metal lead, and the like are the same as those of the conductive support.

(E) Other Layers In the present invention, in order to prevent a short circuit between the counter electrode and the conductive support,
It is preferable that a dense semiconductor thin film layer is previously coated between the conductive support and the photosensitive layer as an undercoat layer. The material of the undercoat layer is preferably an oxide semiconductor, specifically, TiO ₂ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , ZnO, and Nb ₂ O ₅ , more preferably TiO ₂ . The undercoat layer can be applied, for example, by a spray pyrolysis method described in Electrochimi. Acta 40, 643-652 (1995). The preferred thickness of the undercoat layer is 5 to 1000 nm or less, 1
0-500 nm is more preferred.

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, but from the viewpoint of productivity, the simultaneous multilayer coating method is preferable.
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.

(F) 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.

FIG. 2 shows a transparent conductive layer 10a and a transparent counter electrode conductive layer.
40a, a photosensitive layer 20 and a charge transfer layer 30 are interposed therebetween, and have a structure in which light is incident from both sides. FIG. 3 shows that a metal lead 11 is partially provided on a transparent substrate 50a, a transparent conductive layer 10a is further provided, an undercoat layer 60, a photosensitive layer
20, the charge transfer layer 30 and the counter electrode conductive layer 40 are provided in this order,
Further, a support substrate 50 is provided, and light is incident from the conductive layer side. FIG. 4 shows that the conductive layer 10 is further provided on the support substrate 50, and the photosensitive layer 20 is provided via the undercoat layer 60.
Further, a charge transfer layer 30 and a transparent counter electrode conductive layer 40a are provided, and a transparent substrate 50a partially provided with a metal lead 11 is disposed with the metal lead 11 side inward. Are incident. FIG. 5 shows a structure in which a metal lead 11 is partially provided on a transparent substrate 50a and a transparent conductive layer 10a is further provided, and an undercoat layer 60, a photosensitive layer 20, and a charge transfer layer 30 are interposed therebetween. This is a structure from which light enters. FIG. 6 shows a structure in which a transparent conductive layer 10a, a photosensitive layer 20, a charge transfer layer 30, and a counter electrode conductive layer 40 are provided on a transparent substrate 50a, and a support substrate 50 is disposed thereon. Light is incident from the conductive layer side. Structure. FIG. 7 shows that the conductive layer 10 is provided on the support substrate 50, 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 provided, and the transparent substrate 50a is disposed thereon. This is a structure in which light is incident from the counter electrode side. FIG. 8 shows a transparent conductive layer on a transparent substrate 50a.
10a, 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 enters from both sides. It has a structure. FIG. 9 shows that a conductive layer 10 is provided on a supporting substrate 50, a photosensitive layer 20 is provided via an undercoat layer 60, a solid charge transfer layer 30 is further provided, and a partial counter electrode conductive layer 40 or a metal lead 11 is provided thereon. And has a structure in which light is incident from the counter electrode side.

[2] Solar Cell The solar cell of the present invention is such that the photoelectric conversion element works in an external circuit. It is preferable that the side surface of the solar cell is sealed with a polymer, an adhesive, or the like in order to prevent deterioration of components and volatilization of 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 dye-sensitized solar cell of the present invention can have a module structure basically similar to a conventional solar cell module. The solar cell module generally has a structure in which cells are formed on a supporting substrate such as a metal and a ceramic, and the cells are covered with a filling resin or a protective glass or the like, and light is taken in from the opposite side of the supporting substrate. It is also possible to adopt a structure in which a transparent material such as tempered glass is used for the support substrate, a cell is formed thereon, and light is taken in from the transparent support substrate side. Specifically, a module structure called a superstrate type, a substrate type, or a potting type, a substrate-integrated module structure used in an amorphous silicon solar cell, and the like are known. The module structure of the dye-sensitized solar cell of the present invention can be appropriately selected depending on the purpose of use, the place of use, and the environment.

In a typical superstrate type or substrate type module, cells are arranged at regular intervals between support substrates which are transparent on one or both sides and have been subjected to antireflection treatment, and adjacent cells are made of metal leads or flexible. It is connected by wiring or the like, and a current collecting electrode is arranged on the outer edge, so that generated power is taken out to the outside. Between the substrate and the cell, various kinds of plastic materials such as ethylene vinyl acetate (EVA) may be used in the form of a film or a filling resin depending on the purpose, in order to protect the cell and improve current collection efficiency. Also, when used in places where it is not necessary to cover the surface with a hard material, such as places where there is little external impact, the surface protective layer is made of a transparent plastic film, or the above resin is cured to cure the protective function. It is possible to 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 secure the inside sealing and the rigidity of the module, and the space between the support substrate and the frame is hermetically sealed with a sealing material. When a flexible material is used for the cell itself, the supporting substrate, the filling material, and the sealing material, a solar cell can be formed on a curved surface.

In a super straight type solar cell module, for example, while a front substrate sent out from a substrate supply device is conveyed by a belt conveyor or the like, a cell is formed thereon with a sealing material-cell connection lead wire, a back surface sealing. After laminating sequentially with materials and the like, a back substrate or a back cover can be placed, and a frame can be set on the outer edge to produce.

On the other hand, in the case of the substrate type, while the support substrate sent from the substrate supply device is conveyed by a belt conveyor or the like, the cells are sequentially laminated thereon with the inter-cell connection lead wires, the sealing material, and the like. It can be manufactured by placing a front cover and setting a frame on the periphery.

FIG. 10 shows an example of a structure in which the photoelectric conversion element of the present invention is formed into a substrate-integrated module. FIG. 10 shows that after a transparent conductive layer 10a is provided on one surface of a transparent substrate 50a, an undercoat layer 60 is provided, and a photosensitive layer 20 containing a dye-adsorbed semiconductor, a charge transfer layer 30 and Metal counter electrode conductive layer 40
Represents a structure in which a cell provided with is formed into a module, and an antireflection layer 70 is provided on the other surface of the substrate 50a.
In the case of such a structure, the area ratio of the photosensitive layer 20 (the substrate 50 which is the light incident surface) is increased in order to increase the efficiency of using the incident light.
It is preferable to increase the area ratio when viewed from the a side).

In the case of the module having the structure shown in FIG. 10, selective plating, selective etching, and CVD are performed so that the transparent conductive layer, the photosensitive layer, the charge transfer layer, the counter electrode, and the like are arranged three-dimensionally at regular intervals on the substrate. , PVD and other semiconductor process technologies, laser scribing after pattern coating or wide coating, plasma CVM (Solar Energy Materials and Sol
ar Cells, 48, p373-381), and a desired module structure can be obtained by patterning by a mechanical method such as grinding.

Hereinafter, other members and steps will be described in detail. As a sealing material, weather resistance imparting, electrical insulation imparting,
Various materials such as liquid EVA (ethylene vinyl acetate), film EVA, and a mixture of vinylidene fluoride copolymer and acrylic resin can be used according to the purpose of improving the light collection efficiency and cell protection (impact resistance). It is. It is preferable to use a sealing material having high weather resistance and moisture resistance between the outer edge of the module and the frame surrounding the periphery. In addition, the strength and light transmittance can be increased by mixing a transparent filler into the sealing material.

When fixing the sealing material on the cell, a method suitable for the physical properties of the material is used. In the case of film-like materials, various methods such as roll pressing, bar coating, spray coating, screen printing, etc. are possible. is there.

When a flexible material such as PET or PEN is used as the support substrate, a roll-shaped support is drawn out to form a cell thereon, and then a sealing layer is continuously laminated by the above method. Can be highly productive.

In order to increase the power generation efficiency, the surface of the substrate (generally tempered glass) on the light intake side of the module is subjected to an antireflection treatment. As the anti-reflection treatment method,
There are a method of laminating an antireflection film and a method of coating an antireflection layer.

Further, by treating the surface of the cell by a method such as grooving or texturing, it is possible to increase the utilization efficiency of incident light.

In order to increase the power generation efficiency, it is most important that light is taken into the module without loss. However, light that has passed through the photoelectric conversion layer and has reached the inside thereof is reflected, and the efficiency is reduced toward the photoelectric conversion layer. It is also important to return well. As a method of increasing the reflectance of light, after polishing the supporting substrate surface to a mirror surface, a method of depositing or plating Ag, Al, or the like, an alloy layer such as Al-Mg or Al-Ti is used as a reflection layer on the lowermost layer of the cell. There are a method of providing a texture structure and a method of forming a texture structure in the lowermost layer by annealing.

In order to increase the power generation efficiency, it is important to reduce the connection resistance between cells in order to suppress the internal voltage drop. As a method of connecting the cells, wire bonding and connection using a conductive flexible sheet are generally used.However, a method of fixing the cells using a conductive adhesive tape or a conductive adhesive and simultaneously electrically connecting the cells, There is also a method of pattern-coating a conductive hot melt at a desired position.

In the case of a solar cell using a flexible support such as a polymer film, the cells are sequentially formed by the above-described method while the roll-shaped support is being sent out, cut into a desired size, and the peripheral portion is flexible and moisture-proof. The battery body can be manufactured by sealing with a material having a property.
Also, Solar Energy Materials and Solar Cells, 48,
A module structure called “SCAF” described in p383-391 can also be used. Further, a solar cell using a flexible support can be used by being adhered and fixed to a curved glass or the like.

As described in detail above, solar cells having various shapes and functions can be manufactured according to the purpose of use and environment of use.

[0095]

The present invention will be specifically described below with reference to examples. 1. Preparation of Titanium Dioxide Dispersion Titanium dioxide (Nippon Aerosil Co., Ltd.)
Degussa P-25) 15 g, water 45 g, dispersant (Triton X-100, manufactured by Aldrich) 1
g of zirconia beads having a diameter of 0.5 mm (manufactured by Nikkato Co., Ltd.), and dispersed for 2 hours at 1500 rpm using a sand grinder mill (manufactured by Imex). The zirconia beads were removed by filtration from the dispersion. In this case, the average particle size of the titanium dioxide dispersion was 2.5 μm (the primary particle size was 20 nm to 30 nm). The particle size at this time was measured with a master sizer manufactured by MALVERN.

2. Preparation of TiO ₂ electrode adsorbing dye 2-1. Electrode A Conductive glass coated with fluorine-doped tin oxide (manufactured by Nippon Sheet Glass; 25 mm × 100 mm, area resistance 10 Ω / □) Cover a part of the conductive surface side (5mm from the end) with glass and protect it.
Acta 40, 643-652 (1995) to form a titanium dioxide thin film (60 nm thick) by the spray pyrolysis method. Part of the conductive surface (3mm from the end)
Was coated with an adhesive tape to form a spacer, and the above-mentioned titanium dioxide dispersion was applied thereon using a glass rod. After application, the adhesive tape was peeled off and air-dried at room temperature for 1 hour. Next, this glass was converted into an electric furnace (muffle furnace FP manufactured by Yamato Scientific).
-32 type) and baked at 450 ° C for 30 minutes. After taking out the glass and cooling it for 7 minutes, Ru complex dye R-6
In ethanol solution (3 × 10 ⁻⁴ mol / l) at room temperature for 12 hours. The dye-adsorbed glass was washed with acetonitrile, air-dried, and cut into a 25 mm × 10 mm width to obtain an electrode A. The thickness of the thus obtained photosensitive layer (the titanium dioxide layer on which the dye was adsorbed) was 1.9 μm, and the coating amount of the semiconductor fine particles was 3 g / m ² .

2-2. Electrode B (J. Phys. D: Appl. Phys. 3
1 (1998) 1492-1496, electrode formulation for comparative example) 5 ml of distilled water was slowly dropped into this solution while vigorously stirring a mixture of 1 ml of titanium tetraisopropoxide, 5 ml of glacial acetic acid and 15 ml of isopropanol. did. The obtained white gel-like dispersion (solution T) was placed on a hot plate heated to 125 ° C. and placed on a conductive glass (1.5 cm × 2.0 cm size) coated with fluorine-doped tin oxide having a sheet resistance of 10 Ω / □. ) And left for a few minutes. This electrode was placed in the same electric furnace as used for producing the electrode A, and baked at 430 ° C. for 10 minutes. After firing, cracked coating fragments on the electrodes were removed. After that, the solution T is
Again on the coated electrode heated to
℃, 10 minutes) and remove the coating film fragments on the electrode by 20 minutes.
This was repeated twice to obtain an electrode having a TiO ₂ film thickness of 3 μm. This electrode is immersed in an aqueous ammonia solution and distilled water in this order, washed,
Washed with acetone heated to 50 ° C. for 10 minutes. Dye adsorption is performed by heating the above-mentioned washed electrode to 70 ° C. and heating an ethanol solution of Ru complex dye R-6 (dye 25 mg / ethanol 50 ml).
And then cooled to room temperature over 45 minutes. The dye-adsorbed electrode was washed with distilled water and dried under a nitrogen atmosphere in a dark place to obtain an electrode B.

3. Formation of charge transfer layer The charge transfer layer was formed by the following simultaneous coating method. [Simultaneous Coating Method] A nitrile compound shown in Table 1 is added to an acetonitrile solution of CuI (3.2% by mass) to have a mass composition shown in Table 1 and dissolved to prepare a coating solution (coating solution A ). The exposed portion of the conductive surface of the electrode A and the 1 mm width around the cell prepared in the section 2 of the example were protected with an adhesive tape, and placed on a hot plate heated to 100 ° C. for 2 minutes. 0.2 ml of coating solution A was slowly added to electrode A over about 10 minutes while evaporating acetonitrile. After coating, the solution was left on a hot plate for 2 minutes to form a charge transfer layer. The thickness of the charge transfer layer formed at this time is 15 to
It was 20 μm.

4. Production of Solar Cell [Battery of the Invention] On the charge transfer layer formed in the above item 3,
Platinum-deposited glass (platinum layer thickness = 1 µm, glass thickness = 1.1 m
m, size 1 cm × 2.5 cm 2) and sandwiched by clips to produce a photoelectric conversion element. Thus, the configuration shown in FIG. 1, that is, the glass 50a, the conductive layer 10a, the TiO ₂ undercoat layer
A solar cell was fabricated in which 60, a TiO ₂ electrode layer 20 to which a dye was adsorbed, a hole transport layer 30, and a counter electrode layer 40 were sequentially stacked. Batteries 1 to 9 using the different nitrile compounds shown in Table 1 were produced.

[Comparative Solar Cell A] The sensitized TiO ₂ electrode substrate (electrode A; 1 cm × 2.5
cm) was overlaid with platinum-evaporated glass of the same size. Next, an electrolytic solution (a mixture of acetonitrile and 3-methyl-2-oxazolidinone having a volume ratio of 90:10 of iodine 0.00) was used as a solvent in the gap between the two glasses by utilizing the capillary phenomenon.
5 mol / L and a solution of lithium iodide 0.5 mol / L) to produce a comparative solar cell A.

[Comparative solar cell B (J. Phys. D: Appl.
hys. 31 (1998) 1492-1496)] The 3 μm-thick dye-adsorbed TiO ₂ electrode (electrode B) prepared in Section 2-2 was placed on a hot plate at 125 ° C under a nitrogen atmosphere and the CuI Anhydrous acetonitrile coating solution saturated with
The acetonitrile was added slowly while volatilizing until. After the application, the substrate was left on a hot plate for 2 minutes, and then sandwiched with a substrate obtained by depositing gold on the above-described conductive glass, and the periphery of the electrode was sealed with an epoxy resin under a nitrogen atmosphere to produce a comparative solar cell B. .

5. Measurement of Photoelectric Conversion Efficiency Simulated sunlight was generated by passing light of a 500 W xenon lamp (made by Ushio) through a spectral filter (AM1.5 made by Oriel). The intensity of this light was 100 mW / cm ² . Alligator clips are connected to the conductive glass and the counter electrode of the above-described solar cell, and simulated sunlight is irradiated. The generated electricity is measured by a current / voltage measuring device (Keisley SMU238).
(Type). The open-circuit voltage (V _oc ), short-circuit current density (J _sc ), form factor (FF), and conversion efficiency (η) of the solar cell thus obtained are shown in Table 1. In addition, in order to examine the durability of the solar cell, the above-mentioned solar cell was subjected to 60 ° C and relative humidity.
After storing for 7 days under a storage condition of 30%, the same photoelectric conversion characteristic measurement was performed again. Table 1 shows the short-circuit current density and the reduction rate of the short-circuit current density after storage.

[0103]

[Table 1]

It is clear that the solar cell of the present invention has less deterioration over time than the comparative solar cell A, and has a higher photoelectric conversion efficiency and less deterioration over time than the solar cell B for comparison.

[0105]

As described above, the photoelectric conversion element of the present invention has a relatively high photoelectric conversion efficiency and has extremely little characteristic deterioration over time. Therefore, a solar cell including such a photoelectric conversion element is extremely effective.

[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.

FIG. 6 is a partial sectional view showing the structure of a preferred photoelectric conversion element of the present invention.

FIG. 7 is a partial sectional view showing the structure of a preferred photoelectric conversion element of the present invention.

FIG. 8 is a partial sectional view showing the structure of a preferred photoelectric conversion element of the present invention.

FIG. 9 is a partial sectional view showing the structure of a preferred photoelectric conversion element of the present invention.

FIG. 10 is a partial cross-sectional view illustrating an example of the structure of a substrate-integrated solar cell module using the photoelectric conversion element of the present invention.

[Explanation of symbols]

 10: conductive layer 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 conductive layer 40a: Transparent counter electrode layer 50: Substrate 50a: Transparent substrate 60: Undercoat layer 70: Anti-reflection layer

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshisada Nakamura 210 Nakanakanuma, Minamiashigara-shi, Kanagawa Prefecture Fuji Photo Film Co., Ltd. F-term (reference) 5F051 AA14 BA11 CB13 CB24 EA04 EA10 FA02 FA03

Claims (16)

[Claims] 1. A dye-sensitized photoelectric conversion device having a conductive support, a photosensitive layer containing semiconductor fine particles having a dye adsorbed thereon, a charge transfer layer, and a counter electrode, wherein the charge transfer layer comprises p
A photoelectric conversion element comprising a type inorganic compound semiconductor and a nitrile compound. 2. The photoelectric conversion device according to claim 1, wherein a band gap of the p-type inorganic compound semiconductor is 2 eV or more. 3. The photoelectric conversion device according to claim 1, wherein the ionization potential of the p-type inorganic compound semiconductor is 4.5 eV or more and 5.5 eV or less. 4. The compound semiconductor according to claim 1, wherein said p-type inorganic compound semiconductor is a compound semiconductor containing monovalent copper.
Or the photoelectric conversion element according to 3. 5. The method according to claim 1, wherein the compound semiconductor containing monovalent copper is CuI.
The photoelectric conversion device according to claim 4, wherein 6. The compound semiconductor containing monovalent copper is CuSC.
The photoelectric conversion element according to claim 4, wherein N is N. 7. The photoelectric conversion device according to claim 1, wherein the nitrile compound is solid at normal temperature. 8. The photoelectric conversion device according to claim 1, wherein the nitrile compound is a polynitrile compound. 9. The photoelectric conversion device according to claim 1, wherein the nitrile compound is an organic hole transport material. 10. The photoelectric conversion device according to claim 1, wherein the nitrile compound is a compound represented by the following general formula (1). Embedded image [Wherein, R _{11 to} R ₁₆ each represent a substituent, n ₁₁ and n ₁₂ each represent an integer of 0 to 4, and n _{13 to} n _{16 each} represent an integer of 0 to 5. R
₁₁ and R ₁₂ may combine with each other to form a ring. However, at least one of n _{11 to} n ₁₆ is not 0 and R ₁₁
At least one of R ₁₆ to R ₁₆ is a substituent having a cyano group. ] 11. The mass composition ratio of the nitrile compound is p
The photoelectric conversion element according to any one of claims 1 to 10, wherein the content is 0.01% by mass or more and 50% by mass or less based on the type inorganic compound semiconductor. 12. The photoelectric conversion element according to claim 1, wherein an undercoat layer made of an oxide semiconductor is provided between the conductive support and the photosensitive layer. 13. The photoelectric conversion device according to claim 1, wherein the dye is a ruthenium complex dye. 14. The photoelectric conversion element according to claim 1, wherein said semiconductor fine particles are titanium dioxide fine particles. 15. A solar cell using the photoelectric conversion element according to claim 1. Description: 16. A solar cell module comprising the photoelectric conversion element according to claim 1. Description: