JP2001076773A - Photoelectric transfer element, photoelectrochemical cell, and new squalenium cyanine dye - Google Patents

Abstract

PROBLEM TO BE SOLVED: To widen an absorbed wavelength region and to increase photoelectric transfer efficiency by containing semiconductor fine grains sensitized by a squalenium cyanine dye in a photosensitive layer on a conductive carrier. SOLUTION: The photosensitive layer of a photoelectric transfer element having the photosensitive layer contains semiconductor fine grains sensitized by a squalenium cyanine dye expressed by equation, where R11-R16 each indicates a hydrogen atom, a substitutional or nonsubstitutional alkyl group or aryl group, A11 and A12 each indicates a substitutional group, EDG indicates an electron donating group, n11 indicates an integer of 1-4, n12 indicates an integer of 0-3, and n13 indicates an integer of 0-4. The EDG is an amino group or a diaryl amino group preferably. The dye has at least one acid group preferably. The acid group is selected from a carboxyl group, a hydroxy group, a phosphonyl group, and a phosphoryl group. The thickness of the photosensitive layer is preferably set to 9 μm or below. A photoelectrochemical battery made of this element is useful for a solar battery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel cyanine dye having a wide absorption wavelength region, a photoelectric conversion element having high photoelectric conversion efficiency using semiconductor fine particles sensitized by such a dye,
And an electrochemical cell comprising the same.

[0002]

2. Description of the Related Art Photoelectric conversion elements are used in various optical sensors, copying machines, and photovoltaic devices. Various types of photoelectric conversion elements have been put into practical use, such as those using metals, those using semiconductors, those using organic pigments and dyes, and those combining these.

U.S. Pat.Nos. 4,492,721, 4,684,537 and 5,084
Nos. 365, 5350644, 5463057, 5525440 and JP-A-7-249790 describe a photoelectric conversion element using semiconductor fine particles sensitized by a dye (hereinafter referred to as a dye-sensitized photoconductive element). A conversion element), or a material and a manufacturing technique for producing the same are disclosed. The 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 a relatively inexpensive photoelectric conversion element can be provided.

[0004] European Patent No. 911841, and Solar Energy Materials and Solar Cells, Vol. 58, 173-183
Page (1999) discloses a dye-sensitized photoelectric conversion element using a squarylium cyanine dye. Advantages of using a squarylium cyanine dye include a high absorption coefficient of the dye, a low cost of the dye, and a high monochromatic light conversion efficiency. However, since the squarylium cyanine dye has sharp absorption, its action spectrum is correspondingly sharp, and photoelectric conversion cannot be performed over a wide wavelength range of visible light. For this reason, squarylium cyanine dyes have not always been suitable for photoelectric conversion elements (so-called solar cells) intended to convert solar energy into electricity. For these reasons, development of a dye having a broad action spectrum and high photoelectric conversion efficiency with respect to sunlight has been desired.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a squarylium cyanine dye having a wide absorption wavelength region, and a photoelectric conversion element or a photoelectrochemical cell using the dye, which has a high conversion efficiency.

[0006]

Means for Solving the Problems As a result of intensive studies in view of the above object, the present inventors have found that the following general formula (1):

Embedded image (In the general formula (1), R _{11 to} R ₁₆ each represent a hydrogen atom, a substituted or unsubstituted alkyl group or an aryl group, A ₁₁ and A ₁₂ represent a substituent, EDG represents an electron donating group, and n11 represents 1 to
An integer of 4, n12 is an integer of 0 to 3, and n13 is 0 to 4
Represents an integer. The squarylium cyanine dye represented by the formula (1) absorbs light over a wide wavelength range and can efficiently sensitize semiconductor fine particles. A photoelectric conversion element using such a dye exhibits high photoelectric conversion efficiency and has a good photoelectric conversion efficiency. The present inventors have found that a photoelectrochemical cell can be used, and have reached the present invention.

According to the present invention, a photovoltaic cell and a photoelectrochemical cell having more excellent photoelectric conversion efficiency can be obtained by satisfying the following conditions.

(1) EDG in the general formula (1) is preferably an amino group.

(2) EDG in the general formula (1) is preferably a diarylamino group.

(3) R _{13 to} R in the general formula (1)
₁₆ is preferably an alkyl group having 1 to 4 carbon atoms.

(4) The dye represented by the general formula (1) is
It is preferred to have at least one acidic group.

(5) The acidic group is preferably at least one group selected from the group consisting of a carboxyl group, a hydroxy group, a phosphonyl group, and a phosphoryl group.

(6) In the general formula (1), A ₁₂ is an acidic group or a substituent having an acidic group, and n 13 is preferably an integer of 1 or more.

(7) The squarylium cyanine dye represented by the general formula (1) is represented by the following general formula (2):

Embedded image (In the general formula (2), R _{21 to} R ₂₆ each represent a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, R ₂₇ and R ₂₈ represent substituents, X represents a carboxyl group or a phosphonyl group, and n ₂₁ And n22 each represent an integer of 0 to 3.)

(8) The thickness of the photosensitive layer is preferably 9 μm or less.

[Detailed Description of the Invention]

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The photoelectric conversion device of the present invention has a photosensitive layer on a conductive support, and the photosensitive layer contains semiconductor fine particles sensitized by a squarylium cyanine dye.

[1] Squarylium cyanine dye The squarylium cyanine dye used in the present invention is a compound represented by the following general formula (1).

Embedded image

In the general formula (1), R _{11 to} R ₁₆ are preferably a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms (for example, methyl, ethyl, isobutyl, n-
Represents a dodecyl, cyclohexyl, vinyl, allyl, benzyl, etc.) or substituted or unsubstituted aryl group having a total of 6 to 20 carbon atoms (eg, phenyl, tolyl, naphthyl, etc.). Examples of the substituent include a halogen atom (eg, fluorine, chlorine, bromine), an alkoxy group (eg, methoxy, ethoxy, benzyloxy, etc.), an aryloxy group (eg, phenoxy, etc.), an alkylthio group (eg, methylthio, ethylthio, etc.), Arylthio group (eg, phenylthio etc.), hydroxy group and oxygen anion, nitro group, cyano group, amide group (eg, acetylamino, benzoylamino etc.), sulfonamide group (eg, methanesulfonylamino, benzenesulfonylamino, etc.), ureido group (Eg, 3-phenylureido), urethane group (eg, isobutoxycarbonylamino, carbamoyloxy, etc.), ester group (eg, acetoxy, benzoyloxy, methoxycarbonyl, phenoxycarbonyl, etc.), carbamoyl group (eg, N- methylcarbamoyl,
N, N-diphenylcarbamoyl, etc.), sulfamoyl group (eg, N-phenylsulfamoyl, etc.), acyl group (eg, acetyl, benzoyl, etc.), amino group (amino, methylamino, dimethylamino, anilino, N-methylanilino, diphenyl Amino) and a sulfonyl group (eg, methylsulfonyl). The above substituent may be further present on the carbon atom of the substituent. R ₁₃ and R _14,
R ₁₅ and R ₁₆ may combine with each other to form a 3- to 8-membered ring.

R _{11 to} R ₁₆ are preferably a substituted or unsubstituted alkyl group, more preferably an alkyl group having 1 to 6 carbon atoms. R _{13 to} R ₁₆ are particularly preferably a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms.

EDG represents an electron donating group. "Electron donating group" means a group having a Hammett sigma value of less than 0. Hammett's sigma value is widely recognized in the field of organic chemistry, and many references are known, such as "Hammet's Rule" (Maruzen) by Naoki Inamoto. Among the electron donating groups, alkoxy groups, alkylthio groups, amino groups, 1-
Pyrrolidino group, 1-piperidino group, 4-morpholino group, 2-alkoxyvinyl group, 2-aminovinyl group (eg, 2-dimethylaminovinyl, 2-diphenylaminovinyl, etc.), 4-alkoxyphenyl group, 4-aminophenyl Groups are preferred,
Of these, an amino group is particularly preferred. Among the amino groups, a diarylamino group (eg, diphenylamino, ditolylamino, 4,4′-dimethoxydiphenylamino, etc.) is most preferred. n11 represents an integer of 1 to 4.

A ₁₁ and A ₁₂ represent a substituent. Examples of the substituent are the same as the substituents of R _{11 to} R ₁₆ described above. n12 is 0-3
And n13 represents an integer of 0 to 4. n12 is the plurality of A ₁₁ when two or more may be the same or different, may be bonded to each other plurality of A ₁₁ with each other to form a ring. Also, A ₁₁ and EDG may be bonded to each other to form a ring. n1
3 is a plurality of A ₁₂ when two or more may be the same or different, may be bonded to ₁₂ to each other a plurality of A each other to form a ring.

Since the compound represented by the general formula (1) is used by being adsorbed on semiconductor fine particles, it preferably has at least one acidic group in the molecule. An “acidic group” is defined as having a pKa of 1 in a mixed solvent of water and tetrahydrofuran (volume ratio of 50 to 50).
A group having a Bronsted acid of 0 or less,
Preferred are a carboxyl group, a hydroxy group, a phosphonyl group and a phosphoryl group. Of these, a carboxyl group is most preferred. These groups may form a salt with an alkali metal or the like. Further, an inner salt may be formed.

The substitution position of the acidic group is represented by the following general formula (1).
R₁₁, R₁₂, A₁₁, A₁₂Above or A₁₁, A₁₂That too
Is preferably an acidic group. The acidic group is A₁₂On top
Ruka A ₁₂Most preferably, it is an acidic group.

Among the squarylium cyanine dyes represented by the general formula (1), the most preferable one is represented by the following general formula (2).

[0026]

Embedded image

In the general formula (2), R _{21 to} R ₂₆ are each independently a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, R ₂₇ and R ₂₈ are substituents, X is a carboxyl group or a phosphonyl group. And n21 and n22 represent an integer of 0 to 3. Examples of R ₂₇ and R ₂₈ include the same groups as the substituents of R _{11 to} R ₁₆ described above, and are preferably an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms. X is preferably a carboxyl group. n21 and n22 are preferably 0 or 1.

The compounds represented by the general formulas (1) and (2) may have a counter ion depending on the charge of the whole molecule.
Further, an inner salt may be formed. The counter ion is not particularly limited and may be either organic or inorganic. Representative examples include halogen ions (fluorine ions, chloride ions, bromine ions, and iodine ions), hydroxide ions, perchlorate ions, tetrafluoroborate ions, hexafluorophosphate ions, acetate ions, and trifluoroacetate ions. Anions such as methanesulfonate ion, paratoluenesulfonate ion, trifluoromethanesulfonate ion, alkali metals (lithium, sodium, potassium, etc.), alkaline earth metals (magnesium, calcium, etc.), ammonium, alkylammonium (eg, diethyl Ammonium, tetrabutylammonium, etc.),
Examples include cations such as pyridinium, alkylpyridinium (eg, methylpyridinium), guanidinium, and tetraalkylphosphonium.

In the general formulas (1) and (2), each bond is represented as a covalent bond (represented by-), but it may mean a coordination bond depending on the type of the substituent. Notation is not absolute.

Preferred specific examples of the compounds represented by formulas (1) and (2) are shown below, but the present invention is not limited thereto.

[0031]

Embedded image

[0032]

Embedded image

[0033]

[Formula 10]

[0034]

[Formula 11]

[2] Photoelectric Conversion Device The photoelectric conversion device of the present invention has a photosensitive layer having semiconductor fine particles sensitized by the squarylium cyanine dye. Preferably, as shown in FIG.
Laminated in the order of the photosensitive layer 20, the charge transfer layer 30, and the counter electrode conductive layer 40,
Semiconductor fine particles sensitized to the photosensitive layer 20 by a dye 22
Electrolyte filled in the gap between 21 and the semiconductor fine particles 21
23. The electrolyte 23 is composed of the same components as the material 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, the conductive layer 10
The layer composed of the optionally provided substrate 50 is referred to as a “conductive support”, and the layer composed of the counter electrode conductive layer 40 and the optionally provided substrate 50 is referred to as a “counter electrode”. A photoelectrochemical cell in which the photoelectric conversion element is connected to an external circuit to perform a work is provided. 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, the light incident on the photosensitive layer 20 containing the semiconductor fine particles 21 sensitized by the squarylium cyanine dye 22 excites the dye 22, etc., and the excited dye 22, etc. The high-energy electrons in the inside are passed 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 photoelectrochemical 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. At the boundary of each layer (for example, the boundary between the conductive layer 10 and the 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.), They may be mutually diffused and mixed. Hereinafter, each layer will be described in detail.

(A) 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, more preferably 40 Ω / □ or less. The lower limit of the surface resistance is not particularly limited, but is usually about 0.1Ω / □.

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 that a transparent conductive layer made of a conductive metal oxide is formed 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), syndiotactic polystyrene (SPS), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate (PAr), polysulfone (PSF), polyester sulfone (PES), Examples include polyetherimide (PEI), cyclic polyolefin, and brominated phenoxy. To ensure sufficient transparency,
The coating amount of the conductive metal oxide is preferably a support 1 m ² per 0.01~100g of glass or plastic.

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%.

(B) Photosensitive Layer In the photosensitive layer containing the semiconductor fine particles sensitized by the squarylium cyanine dye of the present invention, the semiconductor fine particles act as a so-called photoreceptor, absorb light to separate electric charges, and form electrons and positive electrons. Creates a hole. 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, 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,
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 types of fine particles having different particle size distributions may be mixed, in which 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.
No. 12, pages 3157-3171 (1997), and Burnside et al., Chemical Materials, Vol. 10, No. 9,
The method described on pages 2419 to 2425 is also preferred.

(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 colloid 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 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, a polymer, a surfactant, an acid, a chelating agent, or the like may be used as a dispersing aid, if necessary.

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 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 for a low-viscosity liquid. Thus, the viscosity of the coating solution, the amount of coating, the support,
A wet film forming method may be appropriately selected according to 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 used. 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
It is 0.1-100 μm. When used in a photoelectrochemical cell, the thickness of the semiconductor fine particle layer is preferably 1 to 30 μm, and 2 to 9 μm.
Is more preferred. The coating amount of the semiconductor fine particles per m ² of the support is preferably 0.5 to 400 g, more preferably 5 to 100 g.

After coating 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. A preferred heating temperature range is from 40 ° C to less than 700 ° C, more preferably from 100 ° C to 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 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 injecting electrons from the dye into the semiconductor particles, for example, chemical plating using an aqueous solution of titanium tetrachloride or trichloride. Electrochemical plating using an aqueous titanium solution may be performed.

The semiconductor fine particles preferably have a large surface area so that many dyes can be adsorbed. Therefore, the surface area 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) Adsorption of Dye on Semiconductor Fine Particles The squarylium cyanine 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. To the semiconductor fine particle layer. In the former case, a dipping method, a dipping method, a roller method, an air knife method, or the like can be used. In the case of the immersion method, the dye may be adsorbed at room temperature or may be heated and refluxed as described in JP-A-7-249790. In addition, as the latter coating method, a wire bar method, a slide hopper method,
There are extrusion method, curtain method, spin method, spray method and the like. Printing methods include 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) ), Ethers (diethyl ether, tetrahydrofuran, etc.), dimethyl sulfoxide, amides (N, N-dimethylformamide, N, N-dimethylacetamide, etc.), N-methylpyrrolidone, 1,3-dimethylimidazolidinone , 3-methyloxazolidinone, esters (ethyl acetate, butyl acetate, etc.),
Carbonates (diethyl carbonate, ethylene carbonate, propylene carbonate, etc.), ketones (acetone, 2-butanone, cyclohexanone, etc.), hydrocarbons (hexane, petroleum ether, benzene, toluene, etc.), water and mixed solvents of these No.

As for the viscosity of the squarylium cyanine dye solution, various printing methods other than the extrusion method are suitable for a high-viscosity liquid (for example, 0.01 to 500 Poise), as in the formation of the semiconductor fine particle layer. Liquid (for example,
In the case of 0.1 Poise or less), a slide hopper method, a wire bar method, or a spin method is appropriate, and any of them can form a uniform film.

As described above, the method of adsorbing the squarylium cyanine dye may be appropriately selected according to the viscosity of the coating solution of the squarylium cyanine dye, the coating amount, 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 squarylium cyanine dye causes disturbance of device performance, it is preferable to remove the squarylium cyanine dye by washing immediately after adsorption. It is preferable to perform washing with a polar solvent such as acetonitrile and an organic solvent such as an alcohol solvent using a wet washing tank. In order to increase the adsorption amount of the squarylium cyanine dye, it is preferable to perform a heat treatment before the adsorption. After the heat treatment, do not return to normal temperature to avoid 40-80
It is preferred that the dye be adsorbed quickly between ° C.

The total amount of the squarylium cyanine dye used is 0.01 to 10 per unit surface area (1 m ² ) of the conductive support.
0 mmol is preferred. The amount of the squarylium cyanine dye adsorbed on the semiconductor fine particles is preferably 0.01 to 1 mmol per 1 g of the semiconductor fine particles. 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.

In order to widen the wavelength range of photoelectric conversion as much as possible and to increase the conversion efficiency, two or more dyes can be mixed. In this case, it is preferable to select the dyes to be mixed and the ratio thereof so as to match the wavelength range and the intensity distribution of the light source.

For the purpose of reducing the interaction between dyes such as association, a colorless compound may be co-adsorbed on 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.

(C) Charge Transfer Layer The charge transfer layer is a layer having a function of replenishing the oxidized metal complex dye with electrons. Typical materials that can be used for the charge transfer layer include a liquid (electrolytic solution) in which a redox couple is dissolved in an organic solvent, a so-called gel electrolyte in which a liquid in which a redox couple is dissolved in an organic solvent is impregnated in a polymer matrix,
Molten salts containing a redox couple may be mentioned. Further, a solid electrolyte or a hole transporting material can be used.

The electrolyte used in the present invention preferably comprises an electrolyte, a solvent and an additive. As the electrolyte,
(a) I ₂ and an iodide (LiI, NaI, KI, CsI, metal iodide such as CaI ₂ or tetraalkylammonium iodide, pyridinium iodide, imidazolium iodide, etc. iodine salt such as quaternary ammonium compounds ), And (b) Br ₂ and bromide (LiBr, NaBr, KBr, CsBr, CaB
r ₂ of a metal such as bromide or tetraalkylammonium bromide, a combination of a bromine salt, etc.) of the quaternary ammonium compounds such as pyridinium bromide, (c) ferrocyanate - ferricyanide or ferrocene - such as ferricinium ion Metal complexes, (d) sulfur compounds such as sodium polysulfide, alkylthiol-alkyldisulfide, (e) viologen dyes, hydroquinone-quinone, and the like can be used. Among them, I ₂ and LiI or pyridinium iodide, electrolyte obtained by combining the iodine salt of imidazolium iodide quaternary ammonium compounds such as id are preferred. The above electrolytes may be used as a mixture. Also electrolyte
EP718288, WO95 / 18456, J. Electrochem.Soc., Vol.14
3, No. 10, 3099 (1996), Inorg. Chem., 35, 1168-1178.
The salt in a molten state at room temperature (molten salt) described in (1996) can also be used. When a molten salt is used as an electrolyte, a solvent need not be used.

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

As the solvent for the electrolyte, a compound that can exhibit excellent ionic conductivity because it has low viscosity and high ion mobility, or has high dielectric constant and increases the effective carrier concentration, or both are used. It is desirable. Examples of such solvents include, for example, the following.

(A) Carbonates Esters such as ethylene carbonate, propylene carbonate, vinylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate and dipropyl carbonate are preferred.

(B) Lactones For example, γ-butyrolactone, γ-valerolactone, γ-caprolactone, crotlactone, γ-caprolactone, δ-valerolactone and the like are preferable.

(C) Ethers For example, ethyl ether, 1,2-dimethoxyethane, diethoxyethane, trimethoxymethane, ethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, 1,3-dioxolan, 1,4-dioxane and the like are preferable.

(D) Alcohols For example, methanol, ethanol, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, polyethylene glycol monoalkyl ether, and polypropylene glycol monoalkyl ether are preferred.

(E) Glycols For example, ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, glycerin and the like are preferable.

(F) Glycol ethers Preferred are, for example, ethylene glycol dialkyl ether, propylene glycol dialkyl ether, polyethylene glycol dialkyl ether, polypropylene glycol dialkyl ether and the like.

(G) Tetrahydrofurans For example, tetrahydrofuran, 2-methyltetrahydrofuran and the like are preferable.

(H) Nitriles For example, acetonitrile, glutarodinitrile, propionitrile, methoxyacetonitrile, benzonitrile and the like are preferable.

(I) Carboxylic esters Esters such as methyl formate, methyl acetate, ethyl acetate and methyl propionate are preferred.

(J) Phosphoric acid triesters For example, trimethyl phosphate, triethyl phosphate and the like are preferable.

(K) Heterocyclic compounds For example, N-methylpyrrolidone, 4-methyl-1,3-dioxane, 2-methyl-1,3-dioxolan, 3-methyl-2-oxazolidinone, 1,3-propanesal Ton, sulfolane and the like are preferred.

(L) Other aprotic organic solvents such as dimethyl sulfoxide, formamide, N, N-dimethylformamide, nitromethane, etc.
Water and the like are preferred.

Among these, carbonate-based, nitrile-based and heterocyclic compound-based solvents are preferred. These solvents may be used as a mixture of two or more as necessary.

In the present invention, J. Am. Ceram. Soc., 80
(12), basic compounds such as t-butylpyridine, 2-picoline and 2,6-lutidine as described in 3157-3171 (1997) can also be added. A preferred concentration range when adding a basic compound is 0.05 to 2M.

The electrolyte can be gelled (solidified) by a method such as addition of a polymer or an oil gelling agent, polymerization of coexisting polyfunctional monomers, and crosslinking reaction with the polymer. When gelling by adding a polymer, use "Polymer Electrolyte Reviews-1,2" (JR Mac
ELSEIVER APPLIED SCIE co-edited by CaLLum and CA Vincent
NCE) can be used,
In particular, it is preferable to use polyacrylonitrile and polyvinylidene fluoride. When gelation is performed by adding an oil gelling agent, use J. Chem. Soc. Japan, Ind. Chem. Se.
c., 46,779 (1943), J. Am. Chem. Soc., 111, 5542 (19
89), J. Chem. Soc., Chem. Commun., 1993, 390, Ange
w. Chem. Int. Ed. Engl., 35, 1949 (1996), Chem. Let.
t., 1996, 885, J. Chem. Soc., Chem. Commun., 545 (19
The compounds described in 97) can be used.
Among these, preferred are compounds having an amide structure in the molecular structure.

When a gel electrolyte is formed by polymerization of polyfunctional monomers coexisting in the electrolyte, a solution is prepared from the polyfunctional monomers, polymerization initiator, electrolyte and solvent,
Coating is performed on the dye-sensitized semiconductor fine particle layer (photosensitive layer 20) by a method such as a casting method, a coating method, a dipping method, and an impregnation method. FIG.
As shown in (2), it is preferable to fill the voids between the dye-sensitized semiconductor fine particles 21 with a sol-like electrolyte, form a sol-like electrolyte layer on the photosensitive layer 20, and then gel it by radical polymerization.

The polyfunctional monomer has an ethylenically unsaturated group.
It is preferably a compound having two or more, for example, divinylbenzene, ethylene glycol dimethacrylate,
Preferred are ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, and the like.

The gel electrolyte may contain a monofunctional monomer in addition to the above polyfunctional monomer. Examples of the monofunctional monomer include esters or amides derived from acrylic acid or α-alkylacrylic acid (eg, methacrylic acid) (eg, N-isopropylacrylamide, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, Derived from acrylamidopropyltrimethylammonium chloride, methyl acrylate, hydroxyethyl acrylate, N-propyl acrylate, N-butyl acrylate, 2-methoxyethyl acrylate, cyclohexyl acrylate, etc., vinyl esters (eg vinyl acetate), maleic acid or fumaric acid Esters (eg, dimethyl maleate, dibutyl maleate, diethyl fumarate, etc.) and organic acid salts (eg, maleic acid, fumaric acid, sodium salt of p-styrenesulfonic acid, etc.) Nitriles (acrylonitrile, methacrylonitrile, etc.), dienes (eg, butadiene, cyclopentadiene, isoprene, etc.), aromatic vinyl compounds (eg, styrene, p-chlorostyrene, sodium styrenesulfonate, etc.), and nitrogen-containing heterocycles Vinyl compounds having, quaternary ammonium salt-containing vinyl compounds, N-vinylformamide, N-vinyl-N-methylformamide, vinylsulfonic acid, sodium vinylsulfonate, vinylidene fluoride, vinylidene chloride,
Preferred are vinyl alkyl ethers (eg, methyl vinyl ether), olefins (ethylene, propylene, 1-butene, isobutene, etc.), N-phenylmaleimide, and the like. The ratio of the polyfunctional monomer to the total amount of the monomer is 0.
It is preferably 5-70% by weight, more preferably 1.0%
~ 50% by weight.

The above-mentioned monomers for gel electrolytes are described in Takatsu Otsu,
Masayoshi Kinoshita, "Experimental Methods for Polymer Synthesis" (Chemical Doujin)
Alternatively, it can be polymerized by a radical polymerization method, which is a general polymer synthesis method described in "Lecture Polymerization Theory 1 Radical Polymerization (I)" by Takatsu Otsu (Chemical Doujinshi).
The radical polymerization of the monomer for the gel electrolyte can be carried out by heating, light, ultraviolet rays, an electron beam or electrochemically, but it is particularly preferable to carry out the radical polymerization by heating.

When a crosslinked polymer is formed by heating, preferred polymerization initiators are, for example, 2,2′-azobis (isobutyronitrile), 2,2′-azobis (dimethylvaleronitrile), dimethyl-2,2 Azo-based initiators such as' -azobis (2-methylpropionate); and peroxide-based initiators such as benzoyl peroxide. The preferable addition amount of the polymerization initiator is 0.01 to 20% by weight, more preferably 0.1 to 10% by weight, based on the total amount of the monomers.

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

When the electrolyte is gelled by a crosslinking reaction of the polymer, it is desirable to use a polymer having a crosslinking reactive group and a crosslinking agent together. Preferred crosslinkable reactive groups are
It 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 capable of electrophilic reaction with a nitrogen atom. Reagents having two or more functionalities (eg, alkyl halides, aralkyl halides, sulfonic acid esters, acid anhydrides, acid chlorides, isocyanates, etc.).

Organic and / or inorganic hole transport materials can be used in place of the electrolyte. Examples of the organic hole transporting material that can be preferably used in the present invention include the following.

(A) Aromatic amines N, N'-diphenyl-N, N'-bis (4-methoxyphenyl)-
(1,1'-biphenyl) -4,4'-diamine (J. Hagen et a
l., Synthetic Metal 89, 2153-220, (1997)), 2,
2 ', 7,7'-tetrakis (N, N-di-p-methoxyphenylamine) -9,9'-spirobifluorene (Nature, Vol. 395, 8
Oct. 1998, pp. 583-585 and WO97 / 10617), aromatic diamine compounds linked with tertiary aromatic amine units of 1,1-bis {4- (di-p-tolylamino) phenyl} cyclohexane No. 59-194393) and 2,4'-bis [(N-1-naphthyl) -N-phenylamino] biphenyl
Aromatic amines containing two or more tertiary amines and two or more condensed aromatic rings bonded to a nitrogen atom (JP-A-5-234681
), An aromatic triamine having a starburst structure as a derivative of triphenylbenzene (US Pat. No. 4,923,774)
No., JP-A-4-308688), N, N'-diphenyl-N, N'-bis
Aromatic diamines such as (3-methylphenyl)-(1,1′-biphenyl) -4,4′-diamine (US Pat. No. 4,764,625), α,
α, α ', α'-Tetramethyl-α, α'-bis {4- (di-p-tolylamino) phenyl} -p-xylene (JP-A-3-269084
), A p-phenylenediamine derivative, and a triphenylamine derivative whose entire molecule is sterically asymmetric (JP-A-4-129271)
), 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).
No.), aromatic diamine having a styryl structure (Japanese Unexamined Patent Publication No.
No. 290851), benzylphenyl compound (JP-A-4-364153)
Tertiary amine linked by a fluorene group (JP-A-5-25473), triamine compound (JP-A-5-239455)
No.), bis (dipyridylamino) biphenyl (Japanese Unexamined Patent Publication No.
320634), N, N, N-triphenylamine derivatives (Japanese Unexamined Patent Application Publication
6-1972), aromatic diamines having a phenoxazine structure (Japanese Patent Application No. 5-290728), diaminophenylphenanthridine derivatives (Japanese Patent Application No. 6-45669) and the like.

(B) Oligothiophene compounds α-octylthiophene and α, ω-dihexyl-α-octylthiophene (Adv. Mater., Vol. 9, No. 7, 5578 (19
97)), hexadodecyldodecithiophene (Angew. Chem.
Int. Ed. Engl., 34, No. 3, 303-307 (1995)), 2, 8-
Dihexyl anthra [2,3-b: 6,7-b '] dithiophene (JACS,
Vol.120, N0.4,664-672 (1998)).

(C) Conducting Polymer Polypyrrole (K. Murakoshi et al., Chem. Lett. 199
7, p.471), and polyacetylene and its derivatives,
Poly (p-phenylene) and its derivatives, poly (p-phenylenevinylene) and its derivatives, polythienylenevinylene and its derivatives, polythiophene and its derivatives, polyaniline and its derivatives, and polytoluidine and its derivatives (each “Handbook” of Orga
nic Conductive Molecules and Polymers, ”Vol. 1-4
(Written by NALWA, published by WILEY).

Organic, hole-transporting materials include Nature,
Vol. 395, 8 Oct. 583-585 (1998).
To add a compound containing a cation radical such as (4-bromophenyl) aminium hexachloroantimonate, or to control the potential of the oxide semiconductor surface (compensate for the space charge layer), use Li [(CF ₃ SO ₂ ) ₂ N].

The organic hole transporting material can be introduced into the inside of the electrode by a method such as a vacuum evaporation method, a casting method, a coating method, a spin coating method, an immersion method, an electrolytic polymerization method, and a photoelectrolytic polymerization method. When a hole transport material is used instead of the electrolyte, use Electrochem. Acta 40, 643-65 to prevent short circuits.
2 (1995), it is preferable to apply a thin layer of titanium dioxide as an undercoat layer using a technique such as spray pyrolysis.

When an inorganic solid compound is used in place of the electrolyte, copper iodide (p-CuI) (J. Phys. D: Appl. Phys. 31, 1
492-1496 (1998)), copper thiocyanate (Thin Solid Film)
s 261 (1995), 307-310, J. Appl. Phys. 80 (8), 15 Oc.
tober 1996, 4749-4754, Chem. Mater. 1998, 10, 150.
1-1509, SemiCond. Sci. Technol. 10, 1689-1693)
Etc., casting method, coating method, spin coating method, dipping method,
It can be introduced into the electrode by a technique such as an electrolytic plating method.

To form the charge transfer layer, the following two methods can be used. One is to attach a counter electrode via a spacer on the dye-sensitized semiconductor fine particle layer,
This is a method in which the open ends of both are immersed in an electrolyte solution to allow the electrolyte solution to penetrate into the semiconductor fine particle layer and the gap between the semiconductor fine particle layer and the counter electrode. The other is a method in which an electrolyte solution is applied to the semiconductor fine particle layer so that the electrolyte solution penetrates into the semiconductor fine particle layer, a charge transfer layer is formed on the semiconductor fine particle layer, and finally a counter electrode is provided.

In the former case, as a method of infiltrating the electrolyte solution into the gap between the semiconductor fine particle layer and the counter electrode, a normal pressure method utilizing capillary action, and an upper open end of the semiconductor fine particle layer and the counter electrode (dipping into the electrolyte solution). There is a decompression method that sucks from the open end that does not exist.

In the latter case, in the case of a wet type charge transfer layer, a counter electrode is provided in an undried state to take measures to prevent liquid leakage at the edge portion. In the case of a gel electrolyte, a counter electrode may be provided after being wet-coated and solidified by a method such as polymerization, or a solid may be provided after the counter electrode is provided. As a method of forming a layer of a wet organic hole transport material or a gel electrolyte in addition to the electrolytic solution, as in the case of forming a semiconductor fine particle layer and dye adsorption, a dipping method, a roller method, a dipping method, an air knife method, The extrusion method, slide hopper method, wire bar method, spin method, spray method, casting method, various printing methods and the like can be used. In the case of a solid electrolyte or a solid hole (hole) transport material, the charge transfer layer may be formed by a dry film forming process such as a vacuum evaporation method or a CVD method, and then a counter electrode may be provided.

In the case of an electrolyte that cannot be solidified or a wet hole transport material, it is preferable to seal the edge portion immediately after application, and in the case of a hole transport material that can be solidified, the edge is sealed by wet application. After forming the hole transport layer, it is preferable to solidify the film by a method such as photopolymerization or thermal radical polymerization. As described above, the film application method may be appropriately selected depending on the physical properties of the electrolyte and the process conditions.

The amount of water in the charge transfer layer was 10,000 ppm.
The following is preferred, more preferably 2,000 ppm or less, and particularly preferably 100 ppm or less.

(D) Counter electrode The counter electrode functions as a positive electrode of a photoelectrochemical cell when the photoelectric conversion element is a photoelectrochemical 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 metal (for example, platinum, gold, silver, copper, aluminum, rhodium, indium, and the like), carbon, and conductive metal oxide (indium-tin composite oxide, tin oxide with fluorine). And the like). Examples of preferred support substrates for the counter electrode are glass or plastic,
The above-mentioned conductive agent is applied or vapor-deposited on this. 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
It is in the range of 3 μm.

Since light may be irradiated from one or both of the conductive support and the counter electrode, in order for the light to reach the photosensitive layer, at least one of the conductive support and the counter electrode is substantially transparent. I just need. 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.

(E) Other Layers 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 8 exemplify an internal structure of a photoelectric conversion element which can be preferably applied to the present invention.

FIG. 2 shows the transparent conductive layer 10 a and the transparent counter electrode conductive layer 4.
The photosensitive layer 20 and the charge transfer layer 30 are interposed between the photosensitive layer 20a and the light transfer layer 0a, and have a structure in which light enters 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, a charge transfer layer 30, and a counter electrode conductive layer 40 are provided in this order. The substrate 50 is arranged, and has a structure in which light is incident from the conductive layer side. FIG. 4 shows that the conductive layer 10 is further provided on the supporting 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 metal leads 11 are partially provided. Is disposed with the metal lead 11 side inside, and has a structure in which light is incident from the counter electrode side. 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 on the transparent substrate 50a with an undercoat layer 60, a photosensitive layer 20, and a charge transfer layer 30 interposed therebetween. This is a structure from which light enters. FIG. 6 shows that a transparent conductive layer 10a is provided on a transparent substrate 50a, a photosensitive layer 20 is provided through an undercoat layer 60, and a charge transfer layer 30 is further provided.
In addition, a counter electrode conductive layer 40 is provided, and a support substrate 50 is disposed thereon, and has a structure in which light is incident from the conductive layer side.
FIG. 7 shows that the conductive layer 10 is provided on the supporting 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.
Has a transparent conductive layer 10a on a transparent substrate 50a,
And a charge transfer layer 30 and a transparent counter electrode conductive layer 40a, and a transparent substrate 50a is disposed thereon. Light is incident from both sides.

[3] Photoelectrochemical Cell The photoelectrochemical cell of the present invention is one in which the above-mentioned photoelectric conversion element is made to work in an external circuit. It is preferable that the side surface of the photoelectrochemical 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.

[4] Dye-Sensitized Solar Cell 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 that 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 fixed intervals between supporting 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 a protective function is provided by curing the above-mentioned filling resin. 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. Also,
If 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.

[0118] The super straight type solar cell module is, for example, a method in which a front substrate sent from a substrate supply device is conveyed by a belt conveyor or the like, and a cell is formed thereon with a sealing material-cell connection lead wire and 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 out 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 wire, the sealing material, and the like. It can be manufactured by placing a front cover and setting a frame on the periphery.

FIG. 9 shows an example of a structure in which the photoelectric conversion element of the present invention is formed into a module integrated with a substrate. FIG. 9 shows that a transparent conductive layer 10a is provided on one surface of a transparent substrate 50a, on which a photosensitive layer 20 containing dye-adsorbed TiO ₂ and a charge transfer layer 30 are further provided.
In addition, the cell provided with the metal counter electrode conductive layer 40 is modularized, and the antireflection layer 70 is provided on the other surface of the substrate 50a. In the case of such a structure, it is preferable to increase the area ratio of the photosensitive layer 20 (the area ratio when viewed from the substrate 50a which is the light incident surface) in order to increase the utilization efficiency of incident light.

In the case of the module having the structure shown in FIG. 9, 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 Sola)
r Cells, 48, pp. 373-381), and a desired module structure can be obtained by patterning with a mechanical method such as grinding.

Hereinafter, other members and steps will be described in detail.

Examples of the sealing material include liquid EVA (ethylene vinyl acetate), depending on the purpose of imparting weather resistance, imparting electrical insulation, improving light-collecting efficiency, and improving cell protection (impact resistance).
Various materials such as a film-like EVA and a mixture of a vinylidene fluoride copolymer and an acrylic resin can be used. 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 the sealing material is fixed 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 a support substrate, a roll-shaped support is drawn out to form cells thereon, and then a sealing layer is continuously laminated by the above-described 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 anti-reflection treatment. As the anti-reflection treatment method,
There are a method of laminating an antireflection film and a method of coating an antireflection layer.

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 any loss. However, light transmitted through the photoelectric conversion layer and reaching 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 inter-cell connection resistance from the viewpoint of suppressing 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, cells are sequentially formed by the above-described method while feeding a roll-shaped support, and cut into a desired size. 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 the environment of use.

[0132]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

1. Synthesis of Squarylium Cyanine Dye (A) Synthesis of Squarylium Cyanine Dye (D-4) The squarylium cyanine dye (D-4) of the present invention was synthesized by the following synthesis route.

[0134]

Embedded image

20 g of 5-bromo-2,3,3-trimethylindolenine (4a), 16.5 g of diphenylamine, 0.1 g of copper powder, 0.05 g of iodine and 50 ml of orthodichlorobenzene were mixed and refluxed for 20 hours with stirring. The reaction solution was filtered, and the solvent was distilled off under reduced pressure. The residue was purified by silica gel column chromatography (the effluent was a 20: 1 mixture of hexane and ethyl acetate) to obtain 16.3 g of compound (4b).

20 g of methyl p-toluenesulfonate and 16.3 g of the compound (4b) were mixed and heated with stirring at 120 ° C. for 1 hour. Ethyl acetate was added to the reaction solution, the mixture was filtered, and the obtained solid (4c) was washed with ethyl acetate. Yield 20.4g
Met. Compound (4c) 10.2 g, ethyl acetate 50 ml, water 50 m
l, after mixing 2g of sodium hydroxide and stirring vigorously,
The organic layer of the reaction solution separated into two layers was concentrated. To this, 9.6 g of compound (4d) synthesized by a conventional method and 1-butanol 15
0 ml and toluene 150 ml were added, and the mixture was heated and stirred at 120 ° C. for 3 hours. The solvent was distilled off, and the residue was subjected to silica gel column chromatography (the effluent was methylene chloride and methanol 6:
1 mixture), and recrystallized from acetonitrile to obtain 3.5% of the squarylium cyanine dye (D-4) of the present invention.
g was obtained.

(B) Squarylium cyanine dye (D-5)
In the synthesis example of (D-4), 16.5 g of diphenylamine was used.
A squarylium cyanine dye (D-D) was prepared in exactly the same manner except that 18.2 g of 4,4'-dimethoxydiphenylamine was used.
5) 2.2 g was synthesized.

(C) Other squarylium cyanine dyes Other than the above, squarylium cyanine dyes represented by the general formula (1) of the present invention can be easily synthesized in the same manner as the above compounds.

[0139] 2. Preparation of Coating Solution Containing Titanium Dioxide Particles Except that the autoclave temperature was set to 230 ° C., TiO ₂ concentration of 11% by weight was obtained in the same manner as described in Barbe et al., Journal of American Ceramic Society, Vol. 80, p. 3157. _Two dispersions were obtained. The average size of the resulting titanium dioxide particles was about 10 nm. This dispersion to TiO ₂ 30
By weight, polyethylene glycol (molecular weight: 20,000, manufactured by Wako Pure Chemical Industries, Ltd.) was added and mixed to obtain a coating solution.

3. Preparation of dye-adsorbed titanium dioxide electrode (photoelectric conversion element) This coating solution is applied to the conductive surface of transparent conductive glass (made by Nippon Sheet Glass, surface resistance is about 10Ω / □) coated with fluorine-doped tin oxide. It was applied with a blade to a thickness of 100 μm, dried at 25 ° C. for 30 minutes, and baked at 450 ° C. for 30 minutes in an electric furnace (muffle furnace FP-32 manufactured by Yamato Scientific). The amount of TiO ₂ applied was 15.5 g / m ² and the film thickness was 8.3 μm. After removing the glass and cooling, the dyes (3
× 10 ^-5 mol / L) and a mixed solution of chenodeoxycholic acid (0.04 mol / L) (solvent is ethanol and dimethyl sulfoxide
(0: 1 mixture) for 16 hours. In Comparative Examples, a squarylium cyanine dye (A) described in European Patent No. 911841 described below was used.

Embedded image

The dyed glass was washed successively with ethanol and acetonitrile, and dried in a dark place under a stream of nitrogen.

[0142] 4. Preparation of Photoelectrochemical Cell The dye-sensitized TiO ₂ electrode substrate (2 cm × 2 cm) prepared as described above was overlaid on a platinum-deposited glass of the same size (see FIG. 1). Next, an electrolytic solution (tetrabutyl ammonium iodide 0.65 mol / L, iodine 0.05 mol / L acetonitrile solution) was impregnated into the gap between both glasses by capillary action, and introduced into the TiO ₂ electrode.
Photoelectrochemical cells shown in Table 1 (Examples 1 to 4, Comparative Example 1)
I got

Thus, as shown in FIG. 1, conductive glass (a conductive agent layer 10a provided on glass 50a),
A photoelectrochemical cell in which the photosensitive layer 20, the electrolytic solution 30, the platinum layer 40, and the glass 50a were sequentially laminated was prepared.

[0144] 5. Measurement of action spectrum The photoelectrochemical cells of Examples 1 to 4 and Comparative Example 1 were measured for monochromatic light conversion efficiencies of 400 to 800 nm at 10 nm intervals using an IPCE measuring device manufactured by Optel. Table 1 shows the maximum value of IPCE in Examples 1 to 4 and Comparative Example 1, and the wavelength range in which IPCE exceeding 10% was obtained. IPCE (%) = (number of generated electrons / number of irradiated photons) x
100

[0145]

[Table 1]

In Examples 1 to 4 using the dye of the present invention, compared to Comparative Example 1 using the dye (A) for comparison, the I value exceeded 10%.
It can be seen that the wavelength range in which PCE is given is wide, that is, the action spectrum is broad and the capture rate of sunlight is high. This is an important property for photoelectrically converting sunlight and meets the purpose of the present invention.

6. Measurement of Solar Photoelectric Conversion Efficiency Simulated sunlight was generated by passing light of a 500 W xenon lamp (Ushio) through a spectral filter (Oriel AM1.5). The intensity of this light was 85 mW / cm ² in the vertical plane.

A silver paste was applied to the end of the conductive glass of the photoelectrochemical cell to form a negative electrode. The negative electrode and platinum-deposited glass (positive electrode) were connected to a current-voltage measuring device (Keisley SMU238 type).
Connected to. The generated current was measured while irradiating the simulated sunlight vertically. Table 2 shows the solar cell characteristics of the photoelectrochemical cells of Examples 1 to 4 and Comparative Example 1.

[0149]

[Table 2]

It can be seen that Examples 1-4 using the dye of the present invention have a higher photoelectric conversion efficiency with respect to simulated sunlight than Comparative Example 1 using the dye (A) for comparison.

[0151]

As described above in detail, since the novel squarylium cyanine dye of the present invention has a wide absorption wavelength range, the photoelectric conversion device sensitized by the dye has excellent photoelectric conversion efficiency. A photoelectrochemical cell including such a photoelectric conversion element is extremely useful as a solar cell.

[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 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 fine semiconductor particles 22 dye 23 electrolyte 30 charge transfer layer 40 ..Counter electrode conductive layer 40a ... Transparent counter electrode conductive layer 50 ... Substrate 50a ... Transparent substrate 60 ... Undercoat layer 70 ... Anti-reflective layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4H056 CA02 CA05 CB01 CC02 CC08 CE03 CE06 DD03 FA05 5F051 AA11 AA14 5H032 AA06 AS16 EE16 EE20 HH04

Claims (11)

[Claims] 1. A photoelectric conversion device having at least a photosensitive layer, wherein the photosensitive layer has the following general formula (1): (In the general formula (1), R _{11 to} R ₁₆ each represent a hydrogen atom, a substituted or unsubstituted alkyl group or an aryl group, A ₁₁ and A ₁₂ represent a substituent, EDG represents an electron donating group, and n11 represents 1 to
An integer of 4, n12 is an integer of 0 to 3, and n13 is 0 to 4
Represents an integer. A photoelectric conversion device comprising semiconductor fine particles sensitized by a squarylium cyanine dye represented by the formula (1). 2. The photoelectric conversion device according to claim 1, wherein EDG in the general formula (1) is an amino group. 3. The photoelectric conversion device according to claim 1, wherein EDG in the general formula (1) is a diarylamino group. 4. The photoelectric conversion element according to claim 1, wherein R _{13 to} R ₁₃ in the general formula (1).
_{16. A} photoelectric conversion element, wherein ₁₆ is a substituted or unsubstituted alkyl group. 5. The photoelectric conversion device according to claim 1, wherein the dye represented by the general formula (1) has at least one acidic group. 6. The photoelectric conversion device according to claim 5, wherein the acidic group is at least one group selected from the group consisting of a carboxyl group, a hydroxy group, a phosphonyl group, and a phosphoryl group. Photoelectric conversion element. 7. The photoelectric conversion device according to claim 5, wherein in the general formula (1), A ₁₂ is an acidic group or a substituent having an acidic group, and n 13 is an integer of 1 or more. Characteristic photoelectric conversion element. 8. The photoelectric conversion element according to claim 1, wherein the thickness of the photosensitive layer is 9 μm or less. 9. A photoelectrochemical cell having the photoelectric conversion element according to claim 1. Description: 10. The following general formula (1): (In the general formula (1), R _{11 to} R ₁₆ each represent a hydrogen atom, a substituted or unsubstituted alkyl group or an aryl group, A ₁₁ and A ₁₂ represent a substituent, EDG represents an arylamino group, 1-pyrrolidino Group, 1-piperidino group, 4-morpholino group, 2-alkoxyvinyl group, 2-aminovinyl group, 4-alkoxyphenyl group or 4-aminophenyl group, n11 is an integer of 1 to 4, n12 is 0 to A squarylium cyanine dye, wherein n is an integer of 3 and n13 is an integer of 0 to 4. 11. The squarylium cyanine dye according to claim 10, wherein the squarylium cyanine dye has the following general formula (2): (In the general formula (2), R _{21 to} R ₂₆ each represent a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, R ₂₇ and R ₂₈ represent substituents, X represents a carboxyl group or a phosphonyl group, and n ₂₁ And n22 each represent an integer of 0 to 3.)