JP2003323920A - Film of fine semiconductor particle, photoelectric conversion element and photoelectric cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a fine semiconductor particle film useful for photoelectric conversion element and the like, a method for manufacturing a dye-sensitized photoelectric conversion element showing excellent conversion efficiency, the photoelectric conversion element produced by this method, and a photocell using this photoelectric conversion element. <P>SOLUTION: The method for manufacturing the fine semiconductor particle film comprises the step of forming a metal oxide layer by cathordicelectrodeposition on a porous fine semiconductor particle film with 10 of roughness factor or more. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a semiconductor fine particle film, a method for producing a photoelectric conversion element using this semiconductor fine particle film, a photoelectric conversion element produced by the method, and a photovoltaic cell using such a photoelectric conversion element. Regarding

[0002]

2. Description of the Related Art Some semiconductors including titanium oxide
It is known as an n-type semiconductor and has the property of emitting electrons when receiving light or the like. Utilizing such characteristics, n-type semiconductors are widely used for photocatalysts and the like, and are also being studied as materials for photoelectric conversion elements. Photoelectric conversion elements are used in various optical sensors, copying machines, photovoltaic devices, and the like. Photoelectric conversion elements include those using metals, those using semiconductors, those using organic pigments or dyes, those using these in combination, and various methods have been put to practical use.

US Pat. Nos. 4,927,721, 4,884,537, and 5084.
365, 5350644, 5463057, 5525440, WO98
/ 50393, Japanese Patent Application Laid-Open No. 7-249790 and Japanese Patent Publication No. 10-504521 (Patent Documents 1 to 9) disclose a photoelectric conversion element using semiconductor fine particles sensitized by a dye (hereinafter, referred to as "dye-sensitized photoelectric conversion. Also referred to as “element”), and materials and manufacturing techniques for manufacturing the same. The advantage of the dye-sensitized photoelectric conversion element is that an inexpensive oxide semiconductor such as titanium dioxide can be used without purification to a high degree of purity and thus can be manufactured at a relatively low cost. However, such a photoelectric conversion element does not always have sufficiently high conversion efficiency,
Further improvement in conversion efficiency is desired.

[0004]

[Patent Document 1] US Pat. No. 4,927,721

[Patent Document 2] US Pat. No. 4684537

[Patent Document 3] US Pat. No. 5084365

[Patent Document 4] US Pat. No. 5350644

[Patent Document 5] US Pat. No. 5463057

[Patent Document 6] US Pat. No. 5,525,440

[Patent Document 7] International Publication No. 98/50393 pamphlet

[Patent Document 8] Japanese Patent Laid-Open No. 7-249790

[Patent Document 9] Japanese Patent Publication No. 10-504521

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a semiconductor fine particle film useful for a photoelectric conversion element and the like, and a dye-sensitized photoelectric conversion element exhibiting excellent conversion efficiency by using this semiconductor fine particle film. It is to provide a manufacturing method, a photoelectric conversion element manufactured by the method, and a photovoltaic cell using the photoelectric conversion element.

[0006]

As a result of earnest research in view of the above object, the present inventor has found that a semiconductor fine particle film obtained by forming a metal oxide layer on a porous semiconductor fine particle layer by cathode electrodeposition is used as a photosensitive layer. The present invention was discovered by discovering that it is possible to improve the conversion efficiency of a photoelectric conversion element by using it, and arrived at the present invention.

That is, the method for producing a semiconductor fine particle film of the present invention is characterized by including a step of forming a metal oxide layer by cathode electrodeposition on a porous semiconductor fine particle layer having a roughness factor of 10 or more. .

The method for producing a photoelectric conversion element of the present invention is a method for producing a photoelectric conversion element having a photosensitive layer containing semiconductor fine particles having a dye adsorbed thereon and a conductive support, and the semiconductor of the present invention as described above. A feature is characterized in that a dye is adsorbed on a semiconductor fine particle film produced by the method for producing a fine particle film to form a photosensitive layer.

The photoelectric conversion element of the present invention is produced by the method for producing the photoelectric conversion element of the present invention, and usually has a conductive support, a photosensitive layer, a charge transport layer and a counter electrode. Further, the photovoltaic cell of the present invention uses the photoelectric conversion element.

In the present invention, the porous semiconductor fine particle layer preferably comprises an oxide semiconductor, titanium oxide,
Zinc oxide, niobium oxide, tin oxide, tungsten oxide,
Particularly preferably, it consists of indium oxide, zirconium oxide or strontium titanate. The metal oxide layer formed by cathode electrodeposition is preferably a layer made of zinc oxide or titanium oxide, and the working electrode having a semiconductor fine particle layer formed on a conductive support is immersed in a titanium tetranitrate solution. It is particularly preferable that the layer is made of titanium oxide formed by performing cathodic electrodeposition. The solvent of the electrolyte used for cathode electrodeposition is preferably water. In the method for producing a photoelectric conversion element, it is preferable to dissolve the dye in the electrolyte in advance, and it is more preferable to form the zinc oxide layer. It is particularly preferred that the dye is a ruthenium complex dye.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION [1] Method for Producing Semiconductor Fine Particle Film The method for producing a semiconductor fine particle film of the present invention comprises a step of forming a metal oxide layer on a porous semiconductor fine particle layer by cathode electrodeposition (cathode electrodeposition). Process) is included. The semiconductor fine particle film obtained by the method of the present invention is useful for an antifouling treatment film, a photocatalyst film represented by a superhydrophilic film, a photoelectric conversion element, and the like.
Hereinafter, embodiments in which the semiconductor fine particle film is used as the photosensitive layer of the photoelectric conversion element will be described in detail.

(A) Porous semiconductor fine particle layer The semiconductors forming the porous semiconductor fine particle layer are simple semiconductors (silicon, germanium, etc.), III-V group compound semiconductors,
It may be a metal chalcogenide (oxide, sulfide, selenide, etc.), a compound having a perovskite structure (strontium titanate, calcium titanate, sodium titanate, barium titanate, potassium niobate, etc.) and the like. Above all, an oxide semiconductor can be preferably used.

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

The semiconductor used in the present invention is preferably titanium oxide, zinc oxide, niobium oxide, tin oxide, tungsten oxide, indium oxide, zirconium oxide or strontium titanate, more preferably titanium oxide or niobium oxide, Particularly preferred is titanium oxide. As crystal forms of titanium oxide, anatase type, rutile type, brookite type and the like are known. The titanium oxide used in the present invention may have any of these crystal forms.

The semiconductor used in the present invention may be a single crystal or a polycrystal, but a single crystal is preferable from the viewpoint of conversion efficiency,
Polycrystal is advantageous from the viewpoints of manufacturing cost, securing raw materials, energy payback time, and the like. The semiconductor used in the present invention may include an amorphous part.

The particle size of the semiconductor fine particles is generally in 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 5 to 200 nm.
More preferably, it is 8 to 100 nm. The average particle size of the semiconductor fine particles (secondary particles) in the dispersion is preferably 0.01-
It is 100 μm.

Two or more kinds of semiconductor fine particles having different particle size distributions may be mixed and used. In this case, the average particle size of the small particles is preferably 5 to 50 nm, and the average size of the large particles is preferably. 100-600 nm. The small particles have the effect of increasing the area of the surface on which the dye is adsorbed, and the large particles have the effect of scattering the incident light to improve the light capture rate. 50-99% of particles with small mixing ratio (mass ratio)
And it is preferable that the large particles are 1 to 50%, the small particles are 70 to 95%, and the large particles are 5 to 30%.

As a method for producing semiconductor fine particles, Sakuhana Sakuo's "Sol-Gel Method Science" Agne Jofusha (1998), Technical Information Institute "Sol-Gel Method Thin Film Coating Technology" (1995 ), Etc., Tadao Sugimoto, "Synthesis and size morphology control of monodisperse particles by a new synthesis gel-sol method", Materia, Vol. 35, No. 9, 1012-1018.
Page (1996), etc. Gel-sol method, Manabu Seino's "Titanium oxide physical properties and applied technology" Sulfuric acid method and chlorine method described in Gihodo Publishing (1997), chloride developed by Degussa, A method of producing an oxide by high temperature hydrolysis in a salt or the like can be preferably used.

When titanium oxide fine particles are used as semiconductor fine particles, the journal of American by Barbe et al.
Ceramic Society, Volume 80, Issue 12, 3157-31
The sol-gel method described on page 71 (1997), Chemistry of Materials by Burnside et al., Volume 10, No. 9, pages 2419 to 2425 can be particularly preferably used.

When the porous semiconductor fine particle layer made of the above semiconductor is formed on the conductive support, a method of coating a dispersion or colloidal solution containing semiconductor fine particles on the conductive support is generally used. Target. Considering the mass production of photoelectric conversion devices, the physical properties of dispersion liquids or colloidal solutions containing semiconductor particles, the flexibility of the conductive support, and the like, it is relatively desirable to use a wet film forming method. As a wet film forming method, a coating method and a printing method are typical.

As an example of a method for producing a dispersion liquid of semiconductor fine particles, a dispersion liquid or a colloidal solution prepared by the above-mentioned sol-gel method or the like is used as it is, a mortar grind method, or a crushing method using a mill. Examples of the method include dispersing.

The dispersion medium used for the dispersion liquid of semiconductor fine particles is
It may be water or various organic solvents (methanol, ethanol, isopropyl alcohol, dichloromethane, acetone, acetonitrile, ethyl acetate, etc.). At the time of dispersion, a polymer such as polyethylene glycol, a surfactant, an acid, a chelating agent and the like may be used as a dispersion aid, if necessary. By changing the molecular weight of polyethylene glycol, the viscosity of the dispersion liquid can be adjusted, and a semiconductor fine particle layer that is difficult to peel off can be formed. Therefore, it is preferable to add polyethylene glycol.

Preferred examples of the coating method include a roller method and a dip method as an application system, an air knife method and a blade method as a metering system, and JP-B-58-4589 as a method in which the application and the metering can be performed in the same part. Wire bar method disclosed in No.
The slide hopper method, the extrusion method, the curtain method and the like described in U.S. Pat. Nos. 2,681,294, 2,761,419 and 2,761,791 can be mentioned. A spin method or a spray method is also preferable as a general-purpose machine. As a wet printing method, intaglio, a rubber plate, screen printing, etc. are preferable, including the three major printing methods of letterpress, offset and gravure. The film forming method may be selected from these depending on the liquid viscosity and the wet thickness.

The viscosity of the dispersion liquid of semiconductor fine particles is greatly influenced by the type and dispersibility of the semiconductor fine particles, the type of solvent used, and additives such as surfactants and binders. When the dispersion has a high viscosity (for example, 0.01 to 500 Poise), it is preferable to use the extrusion method, the casting method or the screen printing method. Further, when the viscosity is low (for example, 0.1 Poise or less), it is preferable to use the slide hopper method, the wire bar method, or the spin method in order to form a uniform film. When the coating amount is large to some extent, the extrusion method can be used even if the viscosity is low. Thus, the film forming method may be appropriately selected depending on the viscosity of the dispersion liquid, the coating amount, the support, the coating speed, and the like.

The porous semiconductor fine particle layer is not limited to a single layer, and a layer containing a dispersion of semiconductor fine particles having different particle diameters applied in multiple layers or containing different kinds of semiconductor fine particles (or different binders, additives, etc.). Can also be applied in multiple layers. The multi-layer coating is effective even when the film thickness is insufficient by one-time coating. The extrusion method and the slide hopper method are suitable for multilayer coating. In the case of applying multiple layers, the multiple layers may be applied simultaneously, or may be applied several times to several tens of times in sequence. A screen printing method can also be preferably used for successive overcoating.

Generally, as the thickness of the porous semiconductor fine particle layer increases, the amount of supported dye per unit projected area increases, so that the light trapping rate increases, but the diffusion distance of generated electrons increases, so that loss due to charge recombination occurs. Also grows. Therefore, the preferable thickness of the porous semiconductor fine particle layer is 0.1 to 100 μm. When the photoelectric conversion element of the present invention is used in a solar cell, the thickness of the porous semiconductor fine particle layer is preferably 1 to 30 μm, more preferably 2 to 25 μm. The coating amount of the semiconductor fine particles per 1 m ^{2 of the} conductive support is preferably 0.5 to 400 g,
It is more preferably 5 to 100 g.

After the semiconductor fine particles are coated on the conductive support, the semiconductor fine particles are brought into electronic contact with each other and at the same time, the coating strength and the adhesion with the conductive support are improved.
It is preferable to perform heat treatment. The heating temperature in the heat treatment is preferably 40 to 700 ° C, more preferably 100 to 60.
It is 0 ° C. The heating time is about 10 minutes to 10 hours.
When a substrate 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 substrate. Also, from the viewpoint of cost, it is preferable to perform the heat treatment at a temperature as low as possible. When the heat treatment is carried out in the presence of fine semiconductor particles of 5 nm or less, mineral acid, etc., the heating temperature can be lowered.

After the heat treatment, for the purpose of increasing the surface area of the semiconductor fine particles and increasing the purity in the vicinity of the semiconductor fine particles to improve the electron injection efficiency from the dye into the semiconductor fine particles, US Pat.
Chemical plating treatment using a titanium tetrachloride aqueous solution or the like as described in No. 84365 or electrochemical plating treatment using a titanium trichloride aqueous solution or the like may be performed.

The porous semiconductor fine particle layer preferably has a large surface area so that many dyes can be adsorbed. The roughness factor of the porous semiconductor fine particle layer is 10 or more, preferably 100 or more. The upper limit of the roughness factor is not particularly limited, but is usually about 1000. In the present invention, the roughness factor is
It means the value of surface area / projected area of a porous semiconductor fine particle layer formed on a conductive support or the like.

(B) Cathodic Electrodeposition Cathodic electrodeposition can be carried out by referring to, for example, the method described in Applied Physics Letter, 1996, 68, (17), pp. 2439-2440. Typically, semiconductor particles are applied to a conductive support to obtain a semiconductor electrode (working electrode), and a three-electrode method using a potentiostat is used to work in an electrolyte solution containing a metal nitrate. The pole may be polarized on the cathode side. The set potential of the working electrode may be appropriately selected according to the metal used, but when the reference electrode is a silver / silver chloride electrode, it is preferably about -2 to -0.5 V, more preferably -1.5 to -0.7 V. V, and particularly preferably -1.1 to -0.9 V. The voltage application time is usually 1 minute to 24 hours, preferably 1 minute to 1 hour.
By this step, the metal oxide or the metal hydroxide adheres to the working electrode, and the metal oxide layer is formed by further drying or heating. Usually, drying or heating may be performed at 50 to 450 ° C. for about 30 minutes to 24 hours. The mass ratio of the metal oxide layer to the porous semiconductor fine particle layer is preferably 0.01 to 10%, more preferably 0.05 to 1%.

The metal nitrate may be used as it is by dissolving it in an electrolyte solution. Alternatively, a metal halide or metal alkoxide compound may be added to a nitric acid (usually 0.001 to 10 N, preferably 0.01 to 1 N) aqueous solution to generate a metal nitrate by hydrolysis, and this solution may be used as an electrolyte solution. The concentration of the metal nitrate in the electrolyte solution is preferably 0.001 to 5 mol / l, more preferably 0.01 to 1 mol / l.
is l.

The metal contained in the metal nitrate is, for example, titanium,
It may be tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, scandium, yttrium, lanthanum, vanadium, niobium, tantalum, cadmium, lead, antimony, gallium, etc., preferably titanium, tin, zinc. , Tungsten, zirconium, indium, scandium,
It is yttrium, niobium or gallium, more preferably zinc or titanium, and further preferably titanium.

The electrolyte solution used for cathode electrodeposition is usually
It usually contains an electrolyte salt and a solvent. Electrolyze the above metal nitrates
It is preferable to use as electrolyte salt, but use other electrolyte salt
You may stay. The cation of the electrolyte salt is preferably alkali
Metal ion (Li⁺, Na⁺, K⁺, Rb ⁺, Cs⁺Etc., and more
Preferably K⁺Is. The anion of the electrolyte salt is a strong acid conjugate
It is preferably an anion, and specific examples thereof include halo.
Genide ion (F^-, Cl ^-, Br^-, I^-Etc.), sulfate ion,
Nitrate ion, phosphate ion, ClO_Four ^-, BF_Four ^-, PF₆ ^-, Sb
F₆ ^-, AsF₆ ^-, Trifluoroacetate ion, methane sulfone
Acid ion, paratoluene sulfonate ion, trifluoride
Rmethanesulfonate ion, bis (trifluoroethane
Sulfonyl) imide ion, tris (trifluoromethane)
Examples thereof include sulfonyl) methide ion. These
The nitrate ion is particularly preferable.

The electrolyte salt may be used alone or as a mixture of two or more kinds. The concentration of the electrolyte salt in the electrolyte solution used for cathode electrodeposition is preferably 0.001
˜5 mol / l, more preferably 0.01 to 1 mol / l.

The solvent of the electrolyte solution used for the cathode electrodeposition is not particularly limited as long as it can dissolve the salt,
It is usually water or an organic solvent, preferably water. Examples of organic solvents include alcohols (methanol, ethanol, t-butyl alcohol, benzyl alcohol, etc.),
Nitriles (acetonitrile, propionitrile, 3-methoxypropionitrile, etc.), nitromethane, halogenated hydrocarbons (dichloromethane, dichloroethane, chloroform, chlorobenzene, etc.), ethers (dimethoxyethane, 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.), carbonate ester Class (diethyl carbonate, ethylene carbonate, propylene carbonate, etc.),
Examples thereof include ketones (acetone, 2-butanone, cyclohexanone, etc.) and mixtures thereof.

After the cathode electrodeposition, the working electrode is preferably washed. Usually, washing is performed using the same solvent as that used for the electrolyte solution.

The dye can be dissolved in advance in the electrolyte solution used for cathode electrodeposition. This is particularly preferable when forming a zinc oxide layer on the semiconductor fine particle layer. The concentration of the dye in the electrolyte solution is preferably 0.0001 ~
It is 5 mol / l, and more preferably 0.001 to 0.1 mol / l. The dye is not particularly limited as long as it can be dissolved in the electrolyte solution, but is preferably a ruthenium complex dye.

[2] Photoelectric Conversion Element The method for producing a photoelectric conversion element of the present invention includes a step of adsorbing a dye on the semiconductor fine particle film produced by the method for producing a semiconductor fine particle film of the present invention. In the present invention, by forming the metal oxide layer by cathode electrodeposition,
The conversion efficiency of the photoelectric conversion element is improved. The photoelectric conversion element of the present invention has a photosensitive layer containing semiconductor fine particles to which a dye is adsorbed and a conductive support, and the photosensitive layer is obtained by adsorbing the dye on the semiconductor fine particle film.

The photoelectric conversion element of the present invention is preferably the one shown in FIG.
The conductive layer 10, the photosensitive layer 20, the charge transport layer 30, and the counter conductive layer 40 are laminated in this order as shown in FIG.
Semiconductor fine particles 21 sensitized by this semiconductor fine particles 21
And a charge transport material 23 that has penetrated into the space between the two.
The charge transport material 23 in the photosensitive layer 20 is usually the same material used for the charge transport layer 30. An undercoat layer 60 may be provided between the conductive layer 10 and the photosensitive layer 20. Further, in order to impart strength to the photoelectric conversion element, the conductive layer 10 and / or the counter conductive layer 40
The substrate 50 may be provided as a base of the substrate. In the present invention, the layer composed of the conductive layer 10 and the substrate 50 optionally provided is referred to as a “conductive support”, and the layer composed of the counter electrode conductive layer 40 and the substrate 50 optionally provided is referred to as a “counter electrode”. The conductive layer 10, the counter conductive layer 40, and the substrate 50 in FIG. 1 may be the transparent conductive layer 10a, the transparent counter conductive layer 40a, and the transparent substrate 50a, respectively. Among such photoelectric conversion elements, a photoelectric cell is connected to an external load in order to perform electric work (power generation), and an optical sensor is formed for the purpose of sensing optical information. Among photovoltaic cells, those in which the charge transport material is mainly composed of an ion transport material are called photoelectrochemical cells, and those whose main purpose is power generation by sunlight are called solar cells.

In the photoelectric conversion element shown in FIG.
The light incident on the photosensitive layer 20 containing the semiconductor fine particles 21 sensitized by excites the dye 22 or the like, and the high-energy electrons in the excited dye 22 or the like are passed to the conduction band of the semiconductor fine particles 21 and further diffused. Reach the conductive layer 10. At this time, the dye 22 is an oxidant. In the photovoltaic cell, the electrons in the conductive layer 10 return to the oxidant of the dye 22 via the counter conductive layer 40 and the charge transport layer 30 while working in the external circuit, and the dye 22 is regenerated.
The photosensitive layer 20 functions as a negative electrode, and the counter conductive layer 40 functions as a positive electrode. The boundary of each layer (for example, conductive layer 10 and photosensitive layer 20)
The boundary between the photosensitive layer 20 and the charge transport layer 30, the boundary between the charge transport layer 30 and the counter electrode conductive layer 40, and the like) may be diffused and mixed with each other. Each layer will be described in detail below.

(A) Conductive Support The conductive support is composed of a single layer of (1) a conductive layer or two layers of (2) a conductive layer and a substrate. In the case of (1), as the material of the conductive layer,
Use a conductive layer that can sufficiently maintain the strength and hermeticity of the conductive layer (for example, a metal material such as platinum, gold, silver, copper, zinc, titanium, aluminum, or an alloy containing these). be able to. In the case of (2), a substrate having a conductive layer made of a conductive agent on the photosensitive layer side can be used as a conductive support. Examples of preferable conductive agents include metals (platinum, gold, silver, copper, aluminum, rhodium, indium, etc.), carbon and conductive metal oxides (indium-tin composite oxide, tin oxide doped with fluorine, etc.). Is mentioned. The thickness of the conductive layer is preferably 0.02-10
It is about μm.

The lower the surface resistance of the conductive support, the better. This surface resistance is preferably 100Ω / □ or less,
It is more preferably 40Ω / □ or less. Although the lower limit of the surface resistance is not particularly limited, it is usually about 0.1Ω / □.

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

As the transparent conductive support, one having a transparent conductive layer made of a conductive metal oxide formed on the surface of a transparent substrate made of glass, plastic or the like by coating, vapor deposition or the like can be preferably used. Examples of preferable materials for forming the transparent conductive layer include tin dioxide doped with fluorine. As the transparent substrate, a glass substrate made of soda lime float glass, which is advantageous in terms of cost and strength, a transparent polymer film useful for obtaining a low-cost flexible photoelectric conversion element, and the like can be used. Examples of materials forming the transparent polymer film include tetraacetyl cellulose (TAC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), syndiotactic polystyrene (SPS), polyphenylene sulfide (PP).
S), polycarbonate (PC), polyarylate (PA
r), polysulfone (PSF), polyester sulfone (PES), polyetherimide (PEI), cyclic polyolefin, and brominated phenoxy resin. In order to secure sufficient transparency, the coating amount of the conductive metal oxide is 0.01 to 1 m ² of the glass or plastic substrate.
It is preferably 100 g.

A metal lead can be used as a current collector for the purpose of reducing the resistance of the transparent conductive support. Metal leads are platinum, gold, nickel, titanium, aluminum, copper,
It is preferably made of a metal such as silver, and particularly preferably made of aluminum or silver. It is preferable to dispose a metal lead on a transparent substrate by vapor deposition, sputtering or the like, and provide a transparent conductive layer made of fluorine-doped tin oxide, an ITO film or the like on the metal lead. Further, it is also preferable to dispose 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, the semiconductor fine particles act as a photoconductor and absorb light to separate charges to generate electrons and holes. In the dye-sensitized semiconductor fine particles, light absorption and generation of electrons and holes thereby occur mainly in the dye, and the semiconductor fine particles play a role of receiving and transmitting the electrons or holes. The semiconductor used in the present invention is preferably an n-type semiconductor in which a conductor electron serves as a carrier under photoexcitation and gives an anode current. Preferred embodiments, forming methods, etc. of the semiconductor or porous semiconductor fine particle layer used for the photosensitive layer are as described in the section of "[1] Method for producing semiconductor fine particle film".

(1) Treatment In the present invention, the semiconductor fine particles used in the photosensitive layer may be treated with a solution of a metal compound. As the metal compound, for example, scandium, yttrium, lanthanoid, zirconium, hafnium, niobium, tantalum, gallium, indium, germanium, and an alkoxide or halide of a metal selected from the group consisting of tin can be used.
The metal compound solution (treatment liquid) is usually an aqueous solution or an alcohol solution. The "treatment" means an operation of bringing the semiconductor fine particles into contact with the treatment liquid for a certain period of time before adsorbing the dye on the semiconductor fine particles. The metal compound may or may not be adsorbed on the semiconductor fine particles after the contact. The treatment is preferably performed after forming the semiconductor fine particle layer.

As a concrete method of the treatment, a method of immersing the semiconductor fine particles in the treatment liquid (immersion method) can be mentioned as a preferable example. A method (spray method) of spraying the treatment liquid in a spray shape for a certain period of time can also be applied. The temperature of the treatment liquid when performing the immersion method (immersion temperature) is not particularly limited,
It is typically -10 to 70 ° C, preferably 0 to 40 ° C. The processing time is not particularly limited, and is typically 1 minute to 24 minutes.
Time, preferably 30 minutes to 15 hours. After the immersion, the semiconductor fine particles may be washed with a solvent such as distilled water.
Further, it may be fired in order to strengthen the bond of the substance attached to the semiconductor fine particles by the dipping treatment. The firing conditions may be set in the same manner as the heat treatment conditions described above.

(2) Dye The sensitizing dye used in the photosensitive layer is not particularly limited as long as it has absorption characteristics in the visible region and the near infrared region and can sensitize a semiconductor, but metal complex dyes, methine dyes, Porphyrin dyes and phthalocyanine dyes can be preferably used, of which metal complex dyes are more preferable, and ruthenium complex dyes are particularly preferable. Phthalocyanines, naphthalocyanines, metal phthalocyanines, metal naphthalocyanines, porphyrins such as tetraphenylporphyrin and tetraazaporphyrin, metal porphyrins, and derivatives thereof can also be used. Dyes used for dye lasers can also be used in the present invention. Further, two or more kinds of dyes can be used in combination in order to widen the wavelength range of photoelectric conversion as much as possible and increase the conversion efficiency. In this case, the dyes to be used together and the ratio thereof can be selected so as to match the wavelength range and intensity distribution of the intended light source.

The dye preferably has an appropriate interlocking group capable of adsorbing to the surface of the semiconductor fine particles. Examples of preferred linking groups include -COOH
Groups, -OH groups, -SO ₂ H groups, acidic groups such as -P (O) (OH) ₂ groups and -OP (O) (OH) ₂ groups, and oximes, dioximes, hydroxyquinolines, salicylates and α -Chelating groups having π conductivity such as ketoenolate. Of these, a —COOH group, a —P (O) (OH) ₂ group and a —OP (O) (OH) ₂ group are particularly preferred. These bonding groups may form a salt with an alkali metal or the like, or may form an intramolecular 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 binding group. The preferred sensitizing dyes used in the photosensitive layer will be specifically described below.

(A) Metal Complex Dye The metal atom of the metal complex dye used in the present invention is ruthenium Ru.
Is preferred. Examples of ruthenium complex dyes, U.S. Pat.Nos. 4,927,721, 4,884,537, 5084365,
No. 5350644, No. 5463057, No. 5525440, JP-A-7-249
790, Tokuyohei 10-504512, WO98 / 50393, JP 2000-2
6487 etc. are mentioned. Specific examples of preferable metal complex dyes include those described in JP-A 2001-320068, paragraphs 0051 to 0057. The most typical metal complex dyes include D-1 and D-2 below.

[0052]

[Chemical 1]

(B) Methine Dyes Preferred methine dyes are polymethine dyes such as cyanine dyes, merocyanine dyes and squarylium dyes. Examples of preferable polymethine dyes include JP-A-11-35836.
No. 11, No. 11-158395, No. 11-163378, No. 11-214730,
Examples thereof include dyes described in Nos. 11-214731, European Patents 892411 and 911841. For synthetic methods of these polymethine dyes, see FM Hamer.
Written by "Heterocyclic Compounds-Cyanine Soybeans and Related Compounds (Heterocycl
ic Compounds-Cyanine Dyes and Related Compound
s) ", John Wile and Sons
y & Sons), New York, London (1964),
Heterocy Compounds-Special Topics in Heterocyclic Chemistry by DM Sturmer
clic Compounds-Special topics in Heterocyclic Che
mistry), Chapter 18, Section 14, pp. 482-515, John Wiley & Sons
Co., New York, London (1977), "Rods.
Chemistry of Carbon Compounds (Rodd's
Chemistry of Carbon Compounds) '', 2nd. Ed., Vol.
IV, part B, Chapter 15, 369-422, Elsevier
Science Public Company, Inc. (Elsevi
er Science Publishing Company Inc.), New York (1977), British Patent No. 1,077,611, Ukrainskii
Khimicheskii Zhurnal, Volume 40, No. 3, pp. 253-258,
Dyes and Pigments, Volume 21, pp. 227-234, and the references cited therein.

(3) Adsorption of Dye on Semiconductor Fine Particle Film When adsorbing the dye on the semiconductor fine particle film, a method of immersing a conductive support having a well-dried semiconductor fine particle film in a solution of the dye, or the dye The method of applying the solution of 1) to the semiconductor fine particle film can be used. In the case of the former method,
The dipping method, the dipping method, the roller method, the air knife method and the like can be used. When the dipping method is used, the dye may be adsorbed at room temperature or may be heated under reflux as described in JP-A-7-249790. In the latter case,
Wire bar method, slide hopper method, extrusion method, curtain method, spin method, spray method and the like can be used. Alternatively, a dye may be applied in an image form by an inkjet method or the like, and the image itself may be used as a photoelectric conversion element.

The solvent used for the dye solution (adsorption liquid) is preferably alcohols (methanol, ethanol, t-butanol, benzyl alcohol, etc.), nitriles (acetonitrile, propionitrile, 3-methoxypropionitrile, etc.). , Nitromethane, halogenated hydrocarbons (dichloromethane, dichloroethane, chloroform, chlorobenzene, etc.), ethers (diethyl ether, tetrahydrofuran, etc.), dimethyl sulfoxide, amides (N,
N-dimethylformamide, N, N-dimethylacetamide, etc.), N-methylpyrrolidone, 1,3-dimethylimidazolidinone, 3-methyloxazolidinone, esters (ethyl acetate, butyl acetate, etc.), carbonates ( Diethyl carbonate, ethylene carbonate, propylene carbonate, etc.), ketones (acetone, 2-butanone, cyclohexanone, etc.), hydrocarbons (hexane, petroleum ether, benzene, toluene, etc.) or mixed solvents thereof.

The adsorption amount of the dye is preferably 0.01 to 100 mmol per unit area (1 m ² ) of the semiconductor fine particle film.
The amount of the dye adsorbed on the semiconductor fine particles is preferably 0.01 to 1 mmol per 1 g of the semiconductor fine particles. With such an amount of dye adsorbed, the sensitizing effect of the semiconductor fine particles can be sufficiently obtained. If the amount of dye adsorbed is too small, the sensitizing effect will be insufficient, and if the amount of dye adsorbed is too large, the dye not attached to the semiconductor will float and the sensitizing effect will be reduced. In order to increase the adsorption amount of the dye, it is preferable to heat-treat the semiconductor fine particles before the adsorption. In order to prevent water from adsorbing to the surface of the semiconductor fine particles, it is preferable to quickly adsorb the dye at a temperature of the semiconductor fine particle film of 60 to 150 ° C. without returning to room temperature after the heat treatment.

In order to reduce interactions such as aggregation between dyes, a colorless compound having a property as a surfactant may be added to the dye adsorbing solution and co-adsorbed on the semiconductor fine particles. Examples of such colorless compounds include steroid compounds having a carboxyl group or a sulfo group (cholic acid, deoxycholic acid, chenodeoxycholic acid, taurodeoxycholic acid, etc.), and the following sulfonates. .

[0058]

[Chemical 2]

It is preferable to remove the unadsorbed dye by washing immediately after the adsorption step. The washing is preferably performed in a wet washing tank using an organic solvent such as acetonitrile or an alcohol solvent.

After adsorbing the dye, amines, quaternary ammonium salts, ureido compounds having at least one ureido group, silyl compounds having at least one silyl group, alkali metal salts, alkaline earth metal salts and the like are used. The surface of the semiconductor fine particles may be treated. Examples of preferable amines include pyridine, 4-t-butylpyridine, polyvinylpyridine and the like. Examples of preferred quaternary ammonium salts include tetrabutylammonium iodide,
Tetrahexyl ammonium iodide etc. are mentioned.
These may be used by dissolving them in an organic solvent, or may be used as they are in the case of a liquid.

(C) Charge Transport Layer The charge transport layer contains a charge transport material having a function of supplementing electrons to the oxidized form of the dye. The charge transport material used in the present invention is (i) a charge transport material involving ions,
(ii) It may be a charge-transporting material that involves carrier movement in a solid. (i) As the charge transport material involving ions, a molten salt electrolyte composition containing a redox counter ion,
Examples include a solution in which ions of a redox couple are dissolved (electrolyte solution, electrolyte solution), a so-called gel electrolyte composition in which a gel of a polymer matrix is impregnated with a solution of a redox couple, a solid electrolyte composition, and the like (ii) in solid Examples of the charge transport material involved in carrier transfer include electron transport materials and hole transport materials. A plurality of these charge transport materials may be used in combination. In the present invention, it is preferable to use a molten salt electrolyte composition or a gel electrolyte composition for the charge transport layer.

(1) Molten Salt Electrolyte Composition The molten salt electrolyte composition contains a molten salt. The molten salt electrolyte composition is preferably liquid at room temperature. The molten salt as the main component is liquid at room temperature, or is an electrolyte having a low melting point, as a general example thereof WO95 / 18456, JP-A-8-
259543, Electrochemistry, Vol. 65, No. 11, p. 923 (1997) and the like, and pyridinium salts, imidazolium salts, triazolium salts and the like. The melting point of the molten salt is preferably 50 ° C or lower, and particularly preferably 25 ° C or lower. Specific examples of the molten salt are described in JP-A-2001-320068, paragraph numbers 0066 to 008.
Details are described in 2.

The molten salts may be used alone or in combination of two or more. In addition, LiI, NaI, KI, LiBF ₄ , CF ₃ CO
Alkali metal salts such as OLi, CF ₃ COONa, LiSCN and NaSCN can also be used in combination. The amount of the alkali metal salt added is preferably 2% by mass or less, and more preferably 1% by mass or less, based on the entire composition. Further, it is preferable that 50 mol% or more of the anions contained in the molten salt electrolyte composition are iodide ions.

Usually, the molten salt electrolyte composition contains iodine. The content of iodine is preferably 0.1 to 20% by mass, and 0.5 to 5% by mass with respect to the entire molten salt electrolyte composition.
Is more preferable.

The molten salt electrolyte composition preferably has low volatility and preferably does not contain a solvent. Even when the solvent is added, the amount of the solvent added is preferably 30% by mass or less with respect to the entire molten salt electrolyte composition. The molten salt electrolyte composition may be gelled and used as described below.

(2) Electrolyte Solution The electrolyte solution is preferably composed of an electrolyte, a solvent and additives. Examples of the electrolyte used in the electrolytic solution, I ₂ and iodide (metal iodide such as LiI, NaI, KI, CsI, CaI ₂ ,
Tetraalkylammonium iodide, pyridinium iodide, quaternary ammonium compounds such as imidazolium iodide, etc.) combination, Br ₂ and bromide (metal bromide such as LiBr, NaBr, KBr, CsBr, CaBr ₂ , tetraalkylammonium) Bromide, quaternary ammonium compound such as pyridinium bromide, bromine salt, etc.), metal complex such as ferrocyanate-ferricyanate or ferrocene-ferricinium ion, sodium polysulfide, sulfur compound such as alkylthiol-alkyldisulfide , Viologen dyes, hydroquinone-quinone, and the like. Among them, an electrolyte in which I ₂ and LiI or a quaternary ammonium compound iodine salt such as pyridinium iodide or imidazolium iodide is combined is preferable.
The electrolytes may be mixed and used.

The electrolyte concentration in the electrolytic solution is preferably 0.1 to 1
It is 0 M, more preferably 0.2 to 4 M. When iodine is added to the electrolytic solution, the preferable addition concentration of iodine is 0.01 to 0.5 M.

The solvent used for the electrolytic solution is a compound that can exhibit excellent ionic conductivity by having low viscosity and improving ion mobility or by having high dielectric constant and improving effective carrier concentration. desirable. Examples of such solvents include carbonate compounds such as ethylene carbonate and propylene carbonate, heterocyclic compounds such as 3-methyl-2-oxazolidinone, ether compounds such as dioxane and diethyl ether, ethylene glycol dialkyl ether, propylene glycol dialkyl ether. , Chain ethers such as polyethylene glycol dialkyl ether, polypropylene glycol dialkyl ether, alcohols such as methanol, ethanol, ethylene glycol monoalkyl ether, propylene glycol monoalkyl ether, polyethylene glycol monoalkyl ether, polypropylene glycol monoalkyl ether, ethylene Glycol, propylene glycol, polyethylene glycol, polypropylene glycol Lumpur, polyhydric alcohols such as glycerin, acetonitrile, glutarodinitrile, methoxy acetonitrile, propionitrile, nitrile compounds such as benzonitrile, dimethyl sulfoxide, aprotic polar substances such as sulfolane, water and the like. These solvents may be mixed and used.

Also, J. Am. Ceram. Soc., 80 (12) 3157
-3171 (1997), tert-butylpyridine, and basic compounds such as 2-picoline and 2,6-lutidine are preferably added to the above-described molten salt electrolyte composition or electrolytic solution. The preferable concentration range when the basic compound is added to the electrolytic solution is 0.05 to 2M. When added to the molten salt electrolyte composition, the basic compound preferably has an ionic group. The mass ratio of the basic compound to the entire molten salt electrolyte composition is preferably 1 to 40% by mass, more preferably 5 to 30% by mass.

(3) Gel Electrolyte Composition In the present invention, the above-mentioned molten salt electrolyte composition or electrolytic solution is prepared by a method such as polymer addition, oil gelling agent addition, polymerization containing polyfunctional monomers, and polymer crosslinking reaction. It can also be used by gelling (solidifying). If gelation occurs due to addition of polymer, use “Polymer Electrolyte Revi
The compounds described in ews-1 and 2 "(ELSEVIER APPLIED SCIENCE, co-edited by JR MacCallum and CAVincent) can be used, but polyacrylonitrile and polyvinylidene fluoride are particularly preferably used. Gelation by addition of oil gelling agent If you do
Chem. Soc. Japan, Ind. Chem. Sec.), 46, 779 (194
3), J. Am. Chem. Soc., 111, 5542 (1989), J. Chem.
Soc., Chem. Commun., 1993, 390, Angew. Chem. Int.
Ed. Engl., 35, 1949 (1996), Chem. Lett., 1996, 88
5 and J. Chem. Soc., Chem. Commun., 1997, 545 can be used, but it is preferable to use a compound having an amide structure. An example of gelling an electrolytic solution is described in JP-A-11-185863, and an example of gelling a molten salt electrolyte is also described in JP-A-2000-58140.
These are also applicable to the present invention.

When the polymer is gelated by a crosslinking reaction, it is desirable to use a polymer containing a crosslinkable reactive group and a crosslinking agent together. In this case, the preferred crosslinkable reactive group is an amino group, a nitrogen-containing heterocycle (pyridine ring, imidazole ring, thiazole ring, oxazole ring, triazole ring, morpholine ring, piperidine ring, piperazine ring, etc.) The agent is a bifunctional or higher functional reagent capable of undergoing an electrophilic reaction with respect to a nitrogen atom (halogenated alkyls, halogenated aralkyls, sulfonic acid esters, acid anhydrides, acid chlorides, isocyanate compounds, α, β-unsaturated compounds). Saturated sulfonyl compounds, α, β-unsaturated carbonyl compounds, α, β-unsaturated nitrile compounds, etc.). The cross-linking techniques described in JP-A Nos. 2000-17076 and 2000-86724 can also be applied.

(4) Hole Transport Material In the present invention, an organic solid hole transport material, an inorganic solid hole transport material, or a combination of both materials is used instead of the ion conductive electrolyte such as molten salt. be able to.

(A) Organic Hole Transport Material Examples of organic hole transport materials that can be preferably used in the present invention include J. Hagen, et al., Synthetic Metal, 89,
215-220 (1997), Nature, Vol.395, 8 Oct., p583-585
(1998), WO97 / 10617, JP-A-59-194393, JP-A-5-234.
681, U.S. Pat.No. 4,923,774, JP-A-4-308688, U.S. Pat.No. 4,764,625, JP-A-3-269084, and JP-A-4-129271.
No. 4, No. 4-175395, No. 4-264189, No. 4-290851, No. 4-
364153, 5-25473, 5-239455, 5-320634
No. 6, No. 6-1972, No. 7-138562, No. 7-252474, No. 11-1
Aromatic amines described in JP-A-11-149821
No. 11-148067, No. 11-176489, etc., and the like. Also, Adv. Mater.,
9, No.7, p557 (1997), Angew. Chem. Int. Ed. Engl.,
34, No.3, p303-307 (1995), JACS, Vol.120, No.4, p6
64-672 (1998), etc., oligothiophene compounds, K.
Murakoshi, et al., Chem. Lett. P471 (1997), the polypyrrole, “Handbook of Organic Conductive Mol.
ecules and Polymers, Vol. 1,2,3,4 ”(NALWA, WILE
Y publication), polyacetylene and its derivatives, poly
Conductive polymers such as (p-phenylene) and its derivatives, poly (p-phenylene vinylene) and its derivatives, polythienylene vinylene and its derivatives, polythiophene and its derivatives, polyaniline and its derivatives, polytoluidine and its derivatives, etc. It can be preferably used.

Nature, Vol.395, 8 Oct., p583-585 (199
As described in 8), a compound containing a cation radical such as tris (4-bromophenyl) aminium hexachloroantimonate may be added to the hole transport material to control the dopant level. Further, a salt such as Li [(CF ₃ SO ₂ ) ₂ N] may be added in order to control the potential of the oxide semiconductor surface (compensation of the space charge layer).

(B) Inorganic hole transport material A p-type inorganic compound semiconductor is used as the inorganic hole transport material.
And its bandgap is preferably 2 eV or more.
The upper limit is more preferably 2.5 eV or higher. Also, p-type inorganic
The ionization potential of the compound semiconductor is
To reduce the ionization potential of the dye adsorption electrode
It needs to be smaller. P depending on the dye used
Of ionization potential of type inorganic compound semiconductor
Ranges differ, but generally 4.5-5.5 eV, more
It is preferably 4.7 to 5.3 eV. Preferred p-type inorganic compound
The semiconductor is a compound semiconductor containing monovalent copper.
Is CuI, CuSCN, CuInSe₂, Cu (In, Ga) Se₂, CuGaSe₂,
Cu₂O, CuS, CuGaS₂, CuInS ₂, CuAlSe₂Etc.
Among them, CuI and CuSCN are preferable, and CuI is most preferable.
Yes. Examples of other p-type inorganic compound semiconductors include GaP and Ni.
O, CoO, FeO, Bi₂O₃, MoO₂, Cr₂O₃Etc.

(5) Formation of Charge Transport Layer The charge transport layer can be formed by either of two methods. One is to attach the counter electrode on the photosensitive layer first,
In this method, a liquid charge transport layer is sandwiched in the gap. The other is a method of directly providing a charge transport layer on the photosensitive layer.
The opposite pole will be added later.

In the case of the former method, when sandwiching the charge transport layer, a normal pressure process utilizing a capillary phenomenon due to dipping or the like or a vacuum process of replacing the gas phase in the gap with a liquid phase by making the pressure lower than the normal pressure is used. Available.

In the latter method, when a wet charge transporting layer is used, a counter electrode is usually provided in an undried state to prevent liquid leakage at the edge portion. When the gel electrolyte composition is used, it may be solidified by a method such as polymerization after being applied by a wet method. The solidification may be performed before or after applying the counter electrode. When forming a charge transport layer composed of an electrolytic solution, a wet organic hole transport material, a gel electrolyte composition, etc., the same method as the method for forming the semiconductor fine particle layer described above can be used.

When the solid electrolyte composition or the solid hole transport material is used, the charge transport layer may be formed by a dry film forming process such as a vacuum deposition method or a CVD method, and then the counter electrode may be provided. The organic hole transport material can be introduced into the electrode by a vacuum deposition method, a casting method, a coating method, a spin coating method, a dipping method, an electrolytic polymerization method, a photoelectrolytic polymerization method or the like. The inorganic solid compound can be introduced into the electrode by a casting method, a coating method, a spin coating method, a dipping method, an electrolytic deposition method, an electroless plating method or the like.

(D) Counter Electrode 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 supporting substrate, like the above-mentioned conductive support. Examples of the conductive agent used for the counter conductive layer include metals (platinum, gold, silver, copper, aluminum, magnesium, indium, etc.), carbon, conductive metal oxides (indium-tin composite oxide, fluorine-doped tin oxide, etc.). ) And the like. Among these, platinum, gold,
Silver, copper, aluminum and magnesium are preferred. The substrate used for the counter electrode is preferably a glass substrate or a plastic substrate, and the above conductive agent can be applied or vapor-deposited on the substrate. The thickness of the counter electrode conductive layer is not particularly limited, but is preferably 3 nm to 10 μm. The surface resistance of the counter conductive layer is preferably as low as possible, preferably 50 Ω / □ or less, and more preferably 20 Ω / □ or less.

Since light may be irradiated from either or both of the conductive support and the counter electrode, in order for light to reach the photosensitive layer, at least one of the conductive support and the counter electrode is substantially transparent. I wish I had it. From the viewpoint of improving power generation efficiency, it is preferable to make the conductive support transparent and allow light to enter from the side of the conductive support. In this case, the counter electrode preferably has a property of reflecting light. To obtain this property,
As a counter electrode, glass or plastic having a metal or conductive oxide deposited thereon, or a metal thin film may be used.

For the counter electrode, a conductive agent is applied directly on the charge transport layer,
It may be plated or vapor-deposited (PVD, CVD), or may be placed by attaching the conductive layer side of a substrate having a conductive layer. As in the case of the conductive support, it is preferable to use a metal lead for the purpose of reducing the resistance of the counter electrode, especially when the counter electrode is transparent.
The preferred embodiment of the metal lead is the same as that of the conductive support.

(E) Other Layers In order to prevent a short circuit between the counter electrode and the conductive support, a dense thin film layer of a semiconductor should be previously coated as an undercoat layer between the conductive support and the photosensitive layer. Is preferred. The method of preventing a short circuit by this undercoat layer is particularly effective when an electron transport material or a hole transport material is used for the charge transport layer. The subbing layer is preferably TiO ₂ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , ZnO or Nb ₂ O ₅
And more preferably TiO ₂ . The undercoat layer can be applied by, for example, a spray pyrolysis method described in Electrochim. Acta, 40, 643-652 (1995), a sputtering method, or the like. The thickness of the undercoat layer is preferably 5
˜1000 nm, more preferably 10 to 500 nm.

Further, a functional layer such as a protective layer or an antireflection layer may be provided on the outer surface of one or both of the conductive support and the counter electrode, or between the conductive layer and the substrate or between the substrates. The method of forming these functional layers can be appropriately selected from a coating method, a vapor deposition method, a sticking method and the like 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 be variously formed according to the purpose. If roughly divided into two, it is possible to have a structure in which light can enter from both sides and a structure in which light can enter from only one side. Examples of preferable internal structures of the photoelectric conversion element of the present invention are shown in FIGS. 1 and 2 to 9 described above.

In the structure shown in FIG. 2, the photosensitive layer 20 and the charge transport layer 30 are interposed between the transparent conductive layer 10a and the transparent counter electrode conductive layer 40a, and light is incident from both sides. Has become. In the structure shown in FIG. 3, the metal substrate 11 is partially provided on the transparent substrate 50a, the transparent conductive layer 10a is provided thereon, and the undercoat layer 60, the photosensitive layer 20, the charge transport layer 30, and the counter electrode conductive layer 40 are arranged in this order. And the support substrate 50 is further arranged,
The structure is such that light enters from the conductive layer side. The structure shown in FIG. 4 has a conductive layer 10 on a supporting substrate 50 and an undercoat layer 60.
The photosensitive layer 20 is provided via the above, the charge transport layer 30 and the transparent counter electrode conductive layer 40a are further provided, and the transparent substrate 50a partially provided with the metal lead 11 is arranged with the metal lead 11 side inside. The structure in which light is incident from the counter electrode side. In the structure shown in FIG. 5, a metal lead 11 is partially provided on a transparent substrate 50a, and a transparent conductive layer 10a (or 40a) is further provided between a set of an undercoat layer 60, a photosensitive layer 20, and a charge transport layer 30. Is a structure in which light is incident from both sides. The structure shown in FIG. 6 includes a transparent conductive layer 10a, an undercoat layer 60, and a transparent conductive layer 10a on a transparent substrate 50a.
The photosensitive layer 20, the charge transport layer 30, and the counter electrode conductive layer 40 are provided, and the support substrate 50 is disposed on the photosensitive layer 20, and the light is incident from the conductive layer side. The structure shown in FIG. 7 has a supporting substrate 50.
Having the conductive layer 10 on the top, the photosensitive layer 20 is provided via the undercoat layer 60, further the charge transport layer 30 and the transparent counter electrode conductive layer 40a are provided,
The transparent substrate 50a is arranged on this, and the structure is such that light enters from the counter electrode side. In the structure shown in FIG. 8, the transparent conductive layer 10a is provided on the transparent substrate 50a, the photosensitive layer 20 is provided via the undercoat layer 60, and the charge transport layer 30 and the transparent counter conductive layer 40 are further provided.
a is provided, and the transparent substrate 50a is arranged on this,
The structure is such that light enters from both sides. In the structure shown in FIG. 9, the conductive layer 10 is provided on the support substrate 50, the photosensitive layer 20 is provided via the undercoat layer 60, and the solid charge transport layer 30 is further provided.
A part of the counter electrode conductive layer 40 or the metal lead 11 is provided on this, and the structure is such that light enters from the counter electrode side.

[3] Photocell The photocell of the present invention is one in which the photoelectric conversion element of the present invention is made to work with an external load. Of the photovoltaic cells, the case where the charge transport material mainly consists of the ion transport material is called a photoelectrochemical cell, and the case where the main purpose is power generation by sunlight is called a solar cell.

The side surface of the photovoltaic cell is preferably sealed with a polymer, an adhesive or the like in order to prevent deterioration of the constituents and volatilization of the contents. The external circuit itself, which is connected to the conductive support and the counter electrode via the lead, may be a known one.

Even when the photoelectric conversion element of the present invention is applied to a solar cell, the internal structure of the cell is basically the same as the structure of the photoelectric conversion element described above. Further, the dye-sensitized solar cell using the photoelectric conversion element of the present invention can basically have the same module structure as the conventional solar cell module. In the solar cell module, cells are generally formed on a supporting substrate such as metal or ceramic, and the structure is covered with a filling resin or protective glass to take in light from the opposite side of the supporting substrate. It is also possible to use a transparent material such as tempered glass for the supporting substrate and construct a cell on the transparent material to take in light from the transparent supporting substrate side. Specifically, a module structure called super straight type, substrate type, potting type,
A substrate-integrated module structure used in an amorphous silicon solar cell or the like is known, and a dye-sensitized solar cell using the photoelectric conversion element of the present invention is also selected as appropriate depending on the purpose of use, place of use and environment. it can. Specifically, the structures and aspects described in Japanese Patent Application No. 11-8457 and Japanese Patent Application Laid-Open No. 2000-268892 are preferable.

[0090]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

1. Preparation of Titanium Dioxide Particle Coating Liquid By the same method as that described in Barbe et al., Journal of American Ceramic Society, Volume 80, page 3157, except that the autoclave temperature was 230 ° C. 11% by mass titanium dioxide particle dispersion was obtained. The average particle size of the titanium dioxide particles in this dispersion is about
It was 10 nm. 20 to titanium dioxide in this dispersion
Mass% polyethylene glycol (molecular weight 20000, manufactured by Wako Pure Chemical Industries, Ltd.) was added and mixed to obtain a titanium dioxide particle coating solution.

2. Preparation of titanium dioxide electrode Transparent conductive glass coated with fluorine-doped tin oxide (Nippon Sheet Glass Co., Ltd., surface resistance: about 10Ω /
cm ² ), apply the above titanium dioxide particle coating solution on the conductive surface side of the surface with a doctor blade to a wet thickness of 120 μm, and
After drying for 30 minutes, a titanium dioxide layer was formed by heat treatment at 450 ° C. for 30 minutes using an electric furnace (“Muffle furnace FP-32 type” manufactured by Yamato Scientific Co., Ltd.) to obtain a titanium dioxide electrode. The amount of titanium dioxide applied per unit area of the transparent conductive glass was 16.0 g / m ² , and the film thickness of the titanium dioxide layer was about 11 μm. The roughness factor of the obtained titanium dioxide layer was measured by the BET method, and it was about 1000.

3. Cathode Electrodeposition and Adsorption of Dye The above titanium dioxide electrode was cut into a size of 10 mm × 12 mm. However, the area of the titanium dioxide layer was 10 mm × 10 mm. Subsequently, the titanium dioxide electrode was subjected to cathodic electrodeposition treatment by a three-electrode method using a potentiostat with platinum as a counter electrode and a silver / silver chloride electrode as a reference electrode. An electrolyte consisting of an aqueous solution containing 0.02 M metal nitrate Zn (NO ₃ ) ₂ , 0.02 M lithium nitrate and 0.01 M nitric acid was used.In this electrolyte, a titanium dioxide electrode was polarized to the cathode side, and then water and acetonitrile were used. It was sequentially washed with and baked at 450 ° C. for 30 minutes. The cathode electrodeposition was performed under the conditions of a polarization voltage of -1.1 V and an electrodeposition time of 30 minutes. The weight of the semiconductor fine particle layer per unit area was increased to 17.5 g / m ² by the cathode electrodeposition treatment, but the roughness factor was hardly changed. After the firing was completed, the titanium dioxide electrode subjected to the cathodic electrodeposition treatment was cooled and immersed in a dye adsorbing solution containing the following dye 1 for 3 hours. Immersion was performed while shaking with a shaker. The temperature of the dye adsorbent was 45 ° C, the concentration of dye 1 in the dye adsorbent was 0.3 mmol / l, and the solvent was a mixed solvent of ethanol, 2-methyl-2-propanol and acetonitrile (ethanol: 2-methyl-2 -Propanol: acetonitrile = 1: 1: 2 (volume ratio) was used. After the immersion, it was washed successively with ethanol and acetonitrile, and dried in a dark place under a nitrogen stream to obtain a dye-adsorbed titanium dioxide electrode E-4.

[0094]

[Chemical 3]

Further, the electrodes E-1 to E- were prepared in the same manner as the preparation of the electrode E-4 except that the metal nitrate and the solvent used in the electrolyte solution and the electrodeposition conditions were changed as shown in Table 1 below. 3 and E-5 to E-20 were prepared respectively. Table 1 shows the weight of the semiconductor fine particle layer per unit area of these electrodes. Similar to E-4, roughness factor showed almost no change. The cleaning after polarization was performed sequentially with the solvent used for the electrolyte solution and acetonitrile. When producing the electrodes E-3, E-5 and E-8, Dye 1 was added to the electrolyte solution used for cathode electrodeposition at the concentration shown in Table 1.

[0096]

[Table 1]

4. Production of Photoelectric Conversion Element The above electrode E-1 was overlaid on a 15 mm × 20 mm platinum vapor-deposited glass. Next, an electrolyte solution (1,3-dimethylimidazolium iodide (0.6 mol /
l), lithium iodide (0.1 mol / l) and iodine (0.05 m
(ol / l) in acetonitrile) was soaked and introduced into the electrode to prepare a photoelectric conversion element C-1 for comparison. In this photoelectric conversion element, as shown in FIG. 10, conductive glass 1 (glass 2 having conductive layer 3 provided thereon), dye adsorbing titanium dioxide layer 4, charge transport layer 5, platinum layer 6 and glass 7 were used. It has a structure in which layers are sequentially stacked. Comparative photoelectric conversion elements C-2, C-3 and C-16 were prepared in the same manner as the photoelectric conversion element C-1 except that the electrodes shown in Table 2 below were used instead of the electrode E-1.
And photoelectric conversion elements C-4 to C-15 and C-17 to C-20 of the present invention
Were produced respectively.

5. Evaluation of photoelectric conversion efficiency Light from a 500 W xenon lamp (manufactured by Ushio Inc.) was passed through a spectral filter ("AM1.5" manufactured by Oriel) to generate simulated sunlight. The intensity of this simulated sunlight was 100 mW / cm ² on the vertical plane. Each photoelectric conversion element C-1
Silver paste was applied to the end of the conductive glass of ~ C-20 to form a negative electrode, and this negative electrode and platinum vapor-deposited glass (positive electrode) were connected to a current-voltage measuring device (Keithley SMU238 type). The current-voltage characteristics were measured while vertically irradiating each photoelectric conversion element with simulated sunlight to obtain the photoelectric conversion efficiency. Table 2 shows the conversion efficiency of each photoelectric conversion element.

[0099]

[Table 2]

As shown in Table 2, the photoelectric conversion element of Comparative Example
Compared with C-1, C-3 and C-16, the photoelectric conversion element C- of the present invention
4 to C-15 and C-17 to C-20 showed excellent conversion efficiency.

[0101]

As described above in detail, according to the present invention, a good quality semiconductor fine particle film can be obtained by performing the cathode electrodeposition treatment, and a dye is adsorbed to this semiconductor fine particle film to form a photosensitive layer. A dye-sensitized photoelectric conversion element excellent in conversion efficiency can be obtained.

[Brief description of drawings]

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

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

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

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

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

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

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

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

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

FIG. 10 is a partial cross-sectional view showing a structure of a photoelectric conversion element manufactured in an example.

[Explanation of symbols]

10 ... Conductive layer 10a ... Transparent conductive layer 11 ... Metal leads 20 ... Photosensitive layer 21 ... Semiconductor fine particles 22 ... Dye 23 ... Charge transport material 30 ... Charge transport layer 40 ... Counter electrode conductive layer 40a: Transparent counter electrode conductive layer 50 ... Substrate 50a ... Transparent substrate 60 ... Undercoat layer 1 ... Conductive glass 2 ... glass 3 ... Conductive layer 4 ... Dye adsorption titanium dioxide layer 5 ... Charge transport layer 6 ... Platinum layer 7 ... glass

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5F051 AA14 CB13 FA03 FA06 GA03                 5H032 AA06 AS06 AS16 BB07 EE02                       EE16 HH04

Claims (6)

[Claims] 1. A method for producing a semiconductor fine particle film, which comprises the step of forming a metal oxide layer by cathode electrodeposition on a porous semiconductor fine particle layer having a roughness factor of 10 or more. 2. The method for producing a semiconductor fine particle film according to claim 1, wherein the metal oxide layer is made of zinc oxide or titanium dioxide. 3. The method for producing a semiconductor fine particle film according to claim 1, wherein the metal oxide layer is formed by cathodic electrodeposition in a titanium tetranitrate solution. Method. 4. A method for producing a photoelectric conversion element having a photosensitive layer containing semiconductor fine particles having a dye adsorbed thereon and a conductive support, which is produced by the method according to claim 1. A method for producing a photoelectric conversion element, characterized in that a dye is adsorbed on a semiconductor fine particle film to form the photosensitive layer. 5. A photoelectric conversion element manufactured by the method according to claim 4. 6. A photovoltaic cell comprising the photoelectric conversion element according to claim 5.