JP2003187882A - Photoelectric conversion element, method for manufacturing the same, and photoelectric cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a photoelectric conversion element exhibiting excellent conversion efficiency, the photoelectric conversion element manufactured by this method, and a photoelectric cell using this photoelectric conversion element. <P>SOLUTION: The photoelectric conversion element comprises a photosensitive layer containing fine semiconductor particles onto which a dye is adsorbed, and a conductive support. After the fine semiconductor particles are treated with a metal alkoxide solution where a metal is selected among a group consisting of scandium, yttrium, lanthanoid, zirconium, hafnium, tantalum, gallium, indium, germanium and tin; the dye is adsorbed onto the fine semiconductor particles. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a photoelectric conversion element using semiconductor fine particles sensitized with a dye, a photoelectric conversion element produced by this method, and a photovoltaic cell using the photoelectric conversion element.

[0002]

2. Description of the Related Art 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, JP-A-7-249790 and JP-A-10-504521, a photoelectric conversion element using semiconductor fine particles sensitized by a dye (hereinafter, referred to as "dye-sensitized photoelectric conversion element") and this Materials and manufacturing techniques for making the are disclosed. 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, and improvement in conversion efficiency is desired. Chemical Comunications, 2000, 2231-2232
Have reported that the photoelectric conversion quantum yield is improved by immersing a titanium dioxide film in a solution of niobium isopropoxide in 2-propanol. However, even if this method is used, the effect of improving the conversion efficiency is not necessarily great, and further improvement in conversion efficiency has been demanded.

[0004]

An object of the present invention is to provide a method for producing a dye-sensitized photoelectric conversion element exhibiting excellent conversion efficiency, a photoelectric conversion element produced by this method, and a photovoltaic cell using this photoelectric conversion element. Is to provide.

[0005]

As a result of earnest research in view of the above object, the present inventor has found that the semiconductor fine particles used for the photosensitive layer of a dye-sensitized photoelectric conversion element are treated with a specific aqueous solution of a metal alkoxide to obtain the element. The inventors have found that it is possible to improve the conversion efficiency of, and have conceived the present invention.

That is, 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. , Yttrium, lanthanoid, zirconium, hafnium, tantalum, indium, germanium, and tin are treated with an aqueous solution of a metal selected from the group, and then the dye is adsorbed to the semiconductor fine particles.

The photoelectric conversion device of the present invention is characterized by being manufactured by the method of the present invention, and the photovoltaic cell of the present invention uses the photoelectric conversion device.

The photoelectric conversion device and the photovoltaic cell of the present invention exhibit further excellent conversion efficiency by satisfying the following preferable conditions. (1) The semiconductor fine particles are preferably titanium oxide fine particles. (2) The aqueous solution of metal alkoxide preferably contains an acid or an alkali. (3) The metal is preferably selected from the group consisting of zirconium, indium, hafnium and germanium, and particularly preferably hafnium or germanium. (4) After the semiconductor fine particles are treated with the above aqueous solution and baked,
It is preferable to adsorb the dye. (5) The titanium oxide fine particles are preferably mainly anatase type. (6) The dye is particularly preferably a ruthenium complex dye.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION 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 and a conductive support. The photosensitive layer contains semiconductor fine particles to which a dye is adsorbed. In the method of the present invention, the conversion efficiency of the photoelectric conversion element is improved by treating the semiconductor fine particles with an aqueous metal alkoxide solution described later. The photoelectric conversion element of the present invention is characterized by being manufactured by this method, and the photovoltaic cell of the present invention uses the photoelectric conversion element. Hereinafter, the photoelectric conversion element and the photovoltaic cell of the present invention will be described in detail.

[1] Photoelectric Conversion Element The photoelectric conversion element of the present invention is produced by the production method of the present invention. As shown in FIG. 1, the photoelectric conversion element of the present invention preferably comprises a conductive layer 10, a photosensitive layer 20, a charge transport layer 30, and a counter conductive layer 40 laminated in this order, and the photosensitive layer 20 is sensitized with a dye 22. The semiconductor fine particles 21 and the charge transport material 23 that permeates the voids between the semiconductor fine particles 21. Photosensitive layer
The charge transport material 23 in 20 is typically the same material used for charge transport layer 30. An undercoat layer 60 may be provided between the conductive layer 10 and the photosensitive layer 20. Further, a substrate 50 may be provided as a base of the conductive layer 10 and / or the counter conductive layer 40 in order to impart strength to the photoelectric conversion element. In the present invention, a layer composed of the conductive layer 10 and the substrate 50 optionally provided is a "conductive support",
A layer composed of the counter electrode conductive layer 40 and an optional substrate 50 is called a "counter electrode". The conductive layer 10 in FIG. 1, the counter conductive layer 40,
The substrate 50 is a transparent conductive layer 10a, a transparent counter conductive layer 40a,
It may be the transparent substrate 50a. 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 the photovoltaic cells, those in which the charge transport material is mainly composed of the 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 (1) a single layer of the conductive layer or (2) two layers of the conductive layer and the 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 the light is irradiated from the side of the conductive support, it is preferable that the conductive support is 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.

It is preferable to use metal leads for the purpose of reducing the resistance of the transparent conductive support. The metal lead is platinum,
It is preferably made of a metal such as gold, nickel, titanium, aluminum, copper or 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.

(1) Semiconductor The semiconductor used in the present invention includes a single semiconductor (silicon, germanium, etc.), a III-V group compound semiconductor, 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.

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 Si,
TiO ₂ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , ZnO, Nb ₂ O ₅ , CdS, ZnS, Pb
S, Bi ₂ S ₃ , CdSe, CdTe, GaP, InP, GaAs, CuInS ₂ or Cu
InSe ₂ , more preferably TiO ₂ , ZnO, SnO ₂ , Fe
₂ O ₃ , WO ₃ , Nb ₂ O ₅ , CdS, PbS, CdSe, InP, GaAs, CuInS ₂
Or a CuInSe _2, particularly preferably TiO ₂ or Nb ₂ O _5, and most preferably TiO _2.

As crystal forms of TiO ₂ (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, but it is preferably mainly anatase type because the amount of dye adsorbed increases. The anatase type ratio is preferably 50% or more, more preferably 70% or more.

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 determined from the diameter when the projected area is approximated to 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. The mixing ratio (mass ratio) is preferably 50 to 99% for small particles and 1 to 50% for large particles, and more preferably 70 to 95% for small particles and 5 to 30% for large particles.

As a method for producing semiconductor fine particles, Sakubana Sio'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 the semiconductor fine particles, the journal of American by Barbe et al.
Ceramic Society, Volume 80, Issue 12, 3157-31
71 (1997) and Burnside et al., Chemistry of Materials, Volume 10, No. 9, 2419-2425.
The sol-gel method such as the method described on page can be particularly preferably used.

(2) Semiconductor fine particle layer When forming a semiconductor fine particle layer on a 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, 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.

Examples of preferred coating methods 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 capable of application and metering 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 depends largely on the type and dispersibility of the semiconductor fine particles, the solvent used, and the 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 semiconductor fine particle layer is not limited to a single layer, and a dispersion of semiconductor fine particles having different particle diameters may be applied in multiple layers, or a layer containing different types of semiconductor fine particles (or different binders, additives, etc.) may be formed in multiple layers. It can also be applied. 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 semiconductor fine particle layer (which is the same as the thickness of the photosensitive layer) increases, the amount of supported dye 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 becomes large. Therefore, the preferable thickness of the semiconductor fine particle layer is 0.1 to 1
It is 00 μm. When the photoelectric conversion element of the present invention is used in a solar cell, the thickness of the semiconductor fine particle layer is preferably 1 to 30 μm.
m, more preferably 2 to 25 μm. Conductive support 1m ²
The coating amount of semiconductor fine particles per is preferably 0.5 to 400
g, 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 the coating strength and the adhesion to 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 or enhancing the purity of the vicinity of the semiconductor fine particles and the efficiency of electron injection from the dye into the semiconductor fine particles, chemical plating treatment using an aqueous solution of titanium tetrachloride or the like Electrochemical plating treatment using a titanium chloride aqueous solution or the like may be performed.

The semiconductor fine particle layer preferably has a large surface area so that many dyes can be adsorbed. The surface area of the semiconductor fine particle layer coated on the conductive support is preferably 10 times or more, and more preferably 100 times or more of the projected area. This upper limit is not particularly limited, but is usually about 1000 times.

(3) Treatment In the production method of the present invention, the semiconductor fine particles used in the photosensitive layer are an aqueous solution containing an alkoxide of a metal selected from the group consisting of scandium, yttrium, lanthanoid, zirconium, hafnium, tantalum, indium, germanium and tin. To process. Hereinafter, such an aqueous solution is referred to as a “treatment liquid”. After the treatment with the treatment liquid, the dye is adsorbed on the semiconductor fine particles. The adsorption of the dye will be described later. The lanthanoid refers to the elements with atomic numbers 57 to 71.

In the present invention, "treatment" means an operation of bringing the fine semiconductor particles into contact with the treatment liquid for a certain period of time before adsorbing the dye on the fine semiconductor particles. The metal alkoxide 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.

The metal alkoxide used in the treatment liquid is a lower alcohol having 1 to 4 carbon atoms (methanol, ethanol,
It is preferably an alkoxide (methoxide, ethoxide, 1-propoxide, 2-propoxide, 1-butoxide etc.) of 1-propanol, 2-propanol, 1-butanol etc.). The metal contained in the metal alkoxide is preferably zirconium, indium, hafnium or germanium, particularly preferably hafnium or germanium.

The treatment liquid is preferably transparent without containing precipitates. The treatment liquid can be prepared, for example, by gradually adding the metal alkoxide to water cooled to 10 ° C. or lower. When a metal alkoxide (niobium ethoxide, zirconium ethoxide, etc.) that easily causes precipitation when put in cold water is used, the precipitation can be prevented by adding it to an acidic aqueous solution (dilute hydrochloric acid, dilute nitric acid, concentrated hydrochloric acid, etc.). . As described above, it is usually preferable that the treatment liquid is acidic. On the other hand, when a germanium alkoxide is used, the treatment liquid can be made acidic or basic, but it is preferable to make it basic because the effect is large. To make the treatment liquid basic, add appropriate amount of alkali metal hydroxide (sodium hydroxide, potassium hydroxide, etc.) and organic base (ammonia, amines, pyridines, imidazoles, guanidine, amidine, etc.). Good. In addition, when a precipitate is unavoidable, it is preferable to filter the precipitate and use the supernatant.

In the treatment liquid, the metal alkoxide may be present as it is, or may be partially converted into other chemical species such as hydroxide and oxide by reacting with water. What chemical species are present in the treatment liquid depends on the metal alkoxide used. That is, in the present invention, it suffices that the treatment liquid contains a metal alkoxide or a reaction product thereof, and it is not important what the chemical species in the treatment liquid are. The concentration of the metal alkoxide or the reaction product thereof in the treatment liquid is preferably 0.001 to 1 mol / l, more preferably 0.01 to 0.5 mol / l, and particularly preferably 0.02 to 0.2 mol / l.

A preferable example of the treatment method is a method of immersing the semiconductor fine particles in the treatment liquid (immersion method). 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 (immersion temperature) when performing the immersion method is not particularly limited, but is typically -10 to 70 ° C, preferably 0 ° C to 40 ° C. The treatment time is also not particularly limited, and is typically 1 minute to 24 hours, preferably 30 minutes to 15 hours. After immersion
The semiconductor particles may be washed with 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.

(4) 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 a metal complex dye, a methine dye, Porphyrin dyes and phthalocyanine dyes can be preferably used. 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 improve 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 Dyes Among the metal complex dyes, metal phthalocyanine dyes, metal porphyrin dyes and ruthenium complex dyes are preferable, and ruthenium complex dyes are particularly preferable. Examples of ruthenium complex dyes that can be used in the present invention include US Pat.
No., No. 4684537, No. 5084365, No. 5350644, No. 54630.
No. 57, No. 5525440, Japanese Patent Laid-Open No. 7-249790, Special Table 10-5045
No. 12, WO98 / 50393, JP-A No. 2000-26487, and the like.

The ruthenium complex dye used in the present invention is preferably represented by the following general formula (I): (A ₁ ) _p Ru (Ba) (Bb) (Bc) ... (I). In the general formula (I), A ₁ represents a mono- or bidentate ligand, preferably Cl, SCN, H ₂ O, Br,
It is a ligand selected from the group consisting of I, CN, NCO, SeCN, β-diketone derivatives, oxalic acid derivatives and dithiocarbamic acid derivatives. p is an integer of 0 to 3. Ba, Bb and Bc each independently represent an organic ligand represented by any of the following formulas B-1 to B-10.

[0046]

[Chemical 1]

In formulas B-1 to B-10, each R ₁ represents a hydrogen atom or a substituent, and examples of the substituent include a halogen atom,
A substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 12 carbon atoms, a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, the aforementioned acidic group and Examples include chelating groups. Here, the alkyl part of the alkyl group and aralkyl group may be linear or branched, and the aryl part of the aryl group and aralkyl group may be monocyclic or polycyclic (fused ring, ring assembly). )
May be Ba, Bb and Bc may be the same or different. The ruthenium complex dye represented by the general formula (I) may contain only one or two of Ba, Bb and Bc.

Specific examples of the metal complex dye that can be preferably used in the present invention are shown below, but the present invention is not limited thereto.

[0049]

[Chemical 2]

[0050]

[Chemical 3]

(B) Methine Dyes Preferred methine dyes usable in the present invention are polymethine dyes such as cyanine dyes, merocyanine dyes and squarylium dyes. Examples of polymethine dyes include those disclosed in
11-35836, 11-67285, 11-86916, 11-97725
No. 11, No. 11-158395, No. 11-163378, No. 11-214730,
Examples thereof include dyes described in JP-A Nos. 11-214731, 11-238905, JP-A 2000-26487, European Patents 892411, 911841 and 991092. Specific examples of preferable methine dyes are shown below.

[0052]

[Chemical 4]

[0053]

[Chemical 5]

(5) Adsorption of Dye on Semiconductor Fine Particles When adsorbing a dye on the semiconductor fine particles, a method of immersing a conductive support having a well-dried semiconductor fine particle layer in a solution of the dye, or a solution of the dye Can be applied to the semiconductor fine particle layer. In the case of the former method, a dipping method, a dipping method, a roller method, an air knife method or 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 case of the latter method, a wire bar method, a slide hopper method, an extrusion method, a curtain method, a spin method, a spray method or 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 amount of dye adsorbed is preferably 0.01 to 100 mmol per unit area (1 m ² ) of the semiconductor fine particle layer.
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 layer 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 surface active property 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 sulfonic acid group (chenodeoxycholic acid, taurodeoxycholic acid, etc.), and the following sulfonates.

[0058]

[Chemical 6]

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, the surface of the semiconductor fine particles may be treated with an amine or a quaternary ammonium salt. Examples of preferable amines include pyridine, 4-t-butylpyridine, polyvinylpyridine and the like. Examples of preferable quaternary ammonium salts include tetrabutylammonium iodide and tetrahexylammonium iodide. These may be dissolved in an organic solvent and used, 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 (electrolyte) in which ions of a redox couple are dissolved, 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, and (ii) carrier migration in a solid Examples of the charge transport material related to the above include an electron transport material and a hole transport material. 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 an electrolytic solution for the charge transport layer.

(1) Molten Salt Electrolyte Composition From the viewpoint of achieving both photoelectric conversion efficiency and durability, it is preferable to use a molten salt electrolyte as the charge transport material. The molten salt electrolyte is a liquid at room temperature or an electrolyte having a low melting point, examples of which are WO95 / 18456 and JP-A-8-2595.
43, Electrochemistry, Vol. 65, No. 11, page 923 (1997) and the like, and pyridinium salts, imidazolium salts, triazolium salts and the like. The melting point of the molten salt is preferably 100 ° C. or lower, and particularly preferably liquid at around room temperature.

The molten salt used in the present invention has the following general formula (Y-
It is preferably represented by any of a), (Yb) and (Yc).

[0064]

[Chemical 7]

In formula (Ya), Q _y1 represents an atomic group forming a 5- or 6-membered aromatic cation together with a nitrogen atom. Q
_y1 is preferably composed of an atom selected from the group consisting of carbon atom, hydrogen atom, nitrogen atom, oxygen atom and sulfur atom. The 5-membered ring formed by Q _y1 is an oxazole ring, a thiazole ring, an imidazole ring, a pyrazole ring, an isoxazole ring, a thiadiazole ring, an oxadiazole ring,
It is preferably a triazole ring, an indole ring or a pyrrole ring, more preferably an oxazole ring, a thiazole ring or an imidazole ring, particularly preferably an oxazole ring or an imidazole ring. The 6-membered ring formed by Q _y1 is a pyridine ring, a pyrimidine ring, a pyridazine ring,
A pyrazine ring or a triazine ring is preferable, and a pyridine ring is particularly preferable.

In the general formula (Yb), A _y1 represents a nitrogen atom or a phosphorus atom.

In the general formulas (Ya), (Yb) and (Yc), R _{y1 to} R _y
y11 is independently a substituted or unsubstituted alkyl group (preferably having 1 to 24 carbon atoms, may be linear or branched, or may be cyclic, for example, a methyl group , Ethyl group, propyl group, isopropyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group,
t-octyl group, decyl group, dodecyl group, tetradecyl group, 2-hexyldecyl group, octadecyl group, cyclohexyl group, cyclopentyl group, etc., or a substituted or unsubstituted alkenyl group (preferably having 2 to 24 carbon atoms) ,
It may be linear or branched and represents, for example, a vinyl group or an allyl group. R _{y1 to} R _y11 each independently represent, more preferably, an alkyl group having 2 to 18 carbon atoms or an alkenyl group having 2 to 18 carbon atoms, and particularly preferably an alkyl group having 2 to 6 carbon atoms.

Two or more of R _{y2 to} R _{y5 in} the general formula (Yb) may be linked to each other to form a non-aromatic ring containing A _y1, and R _y6 to the general formula (Yc) to Two or more of R _y11 may be linked to each other to form a ring.

The above Q _y1 and R _{y1 to} R _y11 may have a substituent. Preferred examples of this substituent include a halogen atom (F, Cl, Br, I, etc.), a cyano group, an alkoxy group (methoxy group, ethoxy group, methoxyethoxy group, methoxyethoxyethoxy group, etc.), aryloxy group (phenoxy group, etc.). Etc.), alkylthio group (methylthio group, ethylthio group, etc.), alkoxycarbonyl group (ethoxycarbonyl group, etc.), carbonic acid ester group (ethoxycarbonyloxy group, etc.), acyl group (acetyl group, propionyl group, benzoyl group, etc.), sulfonyl Group (methanesulfonyl group, benzenesulfonyl group, etc.), acyloxy group (acetoxy group, benzoyloxy group, etc.), sulfonyloxy group (methanesulfonyloxy group, toluenesulfonyloxy group, etc.), phosphonyl group (diethylphosphonyl group, etc.), Amido group (acetylamino group, benzoyl group Amino group, etc.), carbamoyl group (N, N-dimethylcarbamoyl group, etc.), alkyl group (methyl group, ethyl group, propyl group, isopropyl group, cyclopropyl group, butyl group, 2-carboxyethyl group, benzyl group, etc.) , Aryl groups (phenyl group, toluyl group, etc.), heterocyclic groups (pyridyl group, imidazolyl group,
Furanyl group etc.), alkenyl group (vinyl group, 1-propenyl group etc.), silyl group, silyloxy group and the like.

The molten salt represented by any one of the general formulas (Ya), (Yb) and (Yc) may form a multimer via Q _y1 and any _{one of} R _{y 1 to} R _y11. .

In the general formulas (Ya), (Yb) and (Yc), X ⁻ represents an anion. Preferred examples of X ⁻ are halide ions (I ⁻ , Cl ⁻ , Br ^−, etc.), SCN ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ ,
_{(CF 3 SO 2) 2 N} -, (CF 3 CF 2 SO 2) 2 N -, CH 3 SO 3 -, CF 3 SO 3 -, CF 3
COO ⁻ , Ph ₄ B ⁻ , (CF ₃ SO ₂ ) ₃ C ^{− and the} like. X ^- is I ^-, SC
More preferably, it is N ⁻ , CF ₃ SO ₃ ⁻ , CF ₃ COO ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ or BF ₄ ⁻ .

Specific examples of the molten salt preferably used in the present invention are shown below, but the present invention is not limited thereto.

[0073]

[Chemical 8]

[0074]

[Chemical 9]

[0075]

[Chemical 10]

[0076]

[Chemical 11]

[0077]

[Chemical 12]

[0078]

[Chemical 13]

The molten salt may be used alone or in combination of two or more kinds. In addition, other iodine salts such as LiI and LiB
Alkali metal salts such as F ₄ , CF ₃ COOLi, CF ₃ COONa, LiSCN and NaSCN can also be used together. The amount of the alkali metal salt added is preferably 0.02 to 2% by mass, more preferably 0.1 to 1% by mass, based on the entire composition.

The molten salt electrolyte is preferably in a molten state at room temperature, and it is preferable not to use a solvent in the composition containing the molten salt electrolyte. The solvent described below may be added, but the content of the molten salt is preferably 50% by mass or more, and particularly preferably 90% by mass or more, based on the entire composition.
Further, it is preferable that 50 mass% or more of the salt contained in the composition is an iodine salt. The molten salt electrolyte composition may be gelled and used as described below.

Iodine is preferably added to the molten salt electrolyte composition, and in this case, the content of iodine is preferably 0.1 to 20% by mass, and 0.5 to 5% by mass based on the whole composition.
More preferably, it is mass%.

(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 0M, and more preferably 0.2 to 4M. When iodine is added to the electrolytic solution, the preferable addition concentration of iodine is 0.01 to 0.5M.

The solvent used for the electrolytic solution is a compound which has a low viscosity and improves the ion mobility, or has a high dielectric constant and the effective carrier concentration, thereby exhibiting excellent ionic conductivity. 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 mass ratio of the basic compound to the entire composition is preferably 0.1 to 40% by mass, more preferably 1 to 20% 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 addition of a polymer, addition of an oil gelling agent, polymerization containing polyfunctional monomers, and crosslinking reaction of a polymer. It can also be used by gelling (solidifying). When gelling by adding a polymer, use “Polymer Electrolyte Re
The compounds described in views-1 and 2 "(JR MacCallum and CA Vincent co-edited, ELSEVIER APPLIED SCIENCE) can be used, but polyacrylonitrile and polyvinylidene fluoride are particularly preferably used. Gels can be added by adding an oil gelling agent. In case of chemical conversion, Journal of Industrial Science (J. Chem. Soc. Japan, Ind. Chem. Sec.), 46, 779
(1943), J. Am. Chem. Soc., 111, 5542 (1989), J. Che.
m. Soc., Chem. Commun., 1993, 390, Angew. Chem. In
t. Ed. Engl., 35, 1949 (1996), Chem. Lett., 1996,
Although the compounds described in 885 and J. Chem. Soc., Chem. Commun., 1997, 545 can be used, it is preferable to use the compound having an amide structure. An example of gelling an electrolytic solution is described in JP-A No. 11-185863, and an example of gelling a molten salt electrolyte is also described in JP-A No. 2000-58140, and 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 in combination. 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 in place of the ion conductive electrolyte such as molten salt. be able to.

(A) Organic Hole Transport Material As examples of the organic hole transport material which can be preferably used in the present invention, 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 mineralization
The ionization potential of the compound semiconductor returns the holes of the dye
To do this, the ionization potential of the dye adsorption electrode
Needs to be smaller. P-type depending on the dye used
Preferred range of ionization potential for inorganic compound semiconductors
Different enclosures, but generally 4.5-5.5 eV, more preferred
It is 4.7 to 5.3 eV. Preferred p-type inorganic compound semiconductor
The body is a compound semiconductor containing monovalent copper.
Is CuI, CuSCN, CuInSe₂, Cu (In, Ga) Se₂, CuGaSe₂, Cu
₂O, CuS, CuGaS₂, CuInS₂, CuAlSe₂Etc. During ~
However, CuI and CuSCN are preferable, and CuI is most preferable.
Examples of other p-type inorganic compound semiconductors include GaP, NiO, and Co.
O, FeO, Bi₂O₃, MoO₂, Cr ₂O₃Etc.

(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 normal pressure is carried out. Available.

In the latter method, when a wet charge transport layer is used, a counter electrode is usually applied while still undried 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 support 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 10-500 nm.

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.

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.

[2] Photocell The photocell of the present invention is such that the photoelectric conversion element of the present invention is caused to work by 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.

When the photoelectric conversion device 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 device 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.

[0106]

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 size of the titanium dioxide particles in this dispersion was about 18 nm. 20 to titanium dioxide in this dispersion
Mass% polyethylene glycol (molecular weight 20000, 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, surface resistance: approx. 10 Ω / cm ² )
The above titanium dioxide particle coating solution was applied to the conductive surface side of the coating solution with a doctor blade at a wet thickness of 120 μm and dried at 25 ° C. for 30 minutes, and then an electric furnace (“Muffle furnace FP-32” manufactured by Yamato Scientific Co., Ltd.
Mold ”) and heat-treated at 450 ° C. for 30 minutes to form a titanium dioxide layer to obtain a titanium dioxide electrode. Titanium dioxide coating amount per unit area of transparent conductive glass is 16.5g / m ²
The thickness of the titanium dioxide layer was about 11.5 μm.

3. Metal alkoxide treatment and dye adsorption The above titanium dioxide electrode was transformed into Sc (OC ₃ H ₇ ) ₃ aqueous solution (treatment liquid).
It was immersed for 12 hours, treated with a metal alkoxide, and washed with distilled water. The pH of the treatment liquid was adjusted to 1 with hydrochloric acid and / or sodium hydroxide. In addition, Sc (O
The concentration of C ₃ H ₇ ) ₃ was 0.1 mol / l. When this was dried and the mass was measured and compared with the mass before the treatment, the mass increase due to the treatment was 0.02 g per 1 m ² . Furthermore, when the surface of titanium dioxide was examined with an ESCA-750 elemental analyzer manufactured by Shimadzu Corporation, the presence of Sc was confirmed. The treated 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. This again in the electric furnace
It was baked at 450 ° C for 30 minutes. After firing, this titanium dioxide electrode was transferred to a hot plate at 100 ° C. in a dry room, gradually cooled, and immersed in a dye adsorbing liquid at a liquid temperature of 45 ° C. for 3 hours. Immersion was performed while shaking with a shaker. The dye-adsorbed titanium dioxide electrode was washed successively with ethanol and acetonitrile, and dried in a dark place under a nitrogen stream to prepare a dye-adsorbed titanium dioxide electrode E-2. As the dye adsorbing liquid, the following Ru complex dye (concentration 0.3 mmol / l), the following adsorption aid (concentration 3 g / l) and a mixed solvent of ethanol, 2-methyl-2-propanol and acetonitrile (ethanol: 2-
Methyl-2-propanol: acetonitrile = 1: 1: 2
(Volume ratio)) was used. Except that the above treatment was not performed, a comparative electrode E-1 was produced in the same manner as in the production method of the electrode E-2, and the treatment liquid and treatment time were changed as shown in Table 1 below. Electrodes E-3 to E-10 were produced in the same manner as the above-mentioned production method of electrode E-2.
In each of the electrodes E-3 to E-10, a mass increase due to the treatment was observed, and the surface of titanium dioxide was further examined with an ESCA-750 type elemental analyzer manufactured by Shimadzu Corporation. The presence of the corresponding element was confirmed. The increase in mass is also shown in Table 1. Chemical Communica
Refer to the method described in tions, 2000, 2231-2232, and the untreated titanium dioxide electrode was treated with a 2-propanol solution of niobium isopropoxide (concentration of niobium isopropoxide: 0.005 mol.
/ l) in a nitrogen atmosphere for 30 seconds. After the immersion, this was washed in a nitrogen atmosphere with sufficiently dried 2-propanol, and baked in air at 500 ° C. for 30 minutes. The mass increase due to this immersion treatment was 0.27 g per 1 m ² . In addition, when the surface of titanium dioxide was examined with an ESCA-750 elemental analyzer manufactured by Shimadzu Corporation, the presence of Nb was confirmed. A dye was adsorbed to the obtained titanium dioxide electrode in the same manner as in the production method of the electrode E-2 to produce a comparative electrode E-11.

[0110]

[Table 1]

[0111]

[Chemical 14]

4. Fabrication of photoelectric conversion element Dye-adsorbed titanium oxide electrode E-2 obtained as described above was applied to 15 mm × 2
It was laminated with 0 mm platinum vapor-deposited glass. Next, the electrolyte solution (1,3-dimethylimidazolium iodide (0.6mol / l), lithium iodide (0.
1 mol / l) and iodine (0.05 mol / l) in acetonitrile) were soaked and introduced into the electrode to obtain a photoelectric conversion element C-2 of the present invention. As shown in FIG. 10, the photoelectric conversion element includes a conductive glass 1 (a glass 2 on which a conductive layer 3 is provided), a dye-adsorbed titanium dioxide layer 4, a charge transport layer 5,
It has a structure in which a platinum layer 6 and a glass 7 are sequentially stacked.
Further, the photoelectric conversion elements C-1 and C-11 of Comparative Examples and the photoelectric conversion element of the present invention were prepared in the same manner as in the production of the photoelectric conversion element C-2 except that the electrodes were changed to those shown in Table 2 below. Element C
-3 to C-10 were produced respectively.

5. Measurement of photoelectric conversion efficiency Simulated sunlight was generated by passing light of a 500 W xenon lamp (manufactured by USHIO) through a spectral filter ("AM1.5" manufactured by Oriel). The intensity of this simulated sunlight is vertical
It was 90 mW / cm ² . Silver paste was applied to the ends of the conductive glass of each photoelectric conversion element C-1 to C-11 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 photoelectric conversion efficiency was obtained by measuring the current-voltage characteristics while irradiating each photoelectric conversion element vertically with simulated sunlight. Table 2 shows the conversion efficiency of each photoelectric conversion element.

[0114]

[Table 2]

As shown in Table 2, the photoelectric conversion element of Comparative Example
Compared with C-1 and C-11, the photoelectric conversion elements C-2 to C-10 of the present invention in which semiconductor particles are treated with a specific metal alkoxide
Showed excellent conversion efficiency. Among the photoelectric conversion elements of the present invention, the photoelectric conversion elements (C-5, C-7 and C-8) using Hf or Ge alkoxide show the best conversion efficiency, and Zr
Alternatively, the photoelectric conversion elements (C-4 and C-6) using In alkoxide were the next results.

[0116]

As described above in detail, according to the manufacturing method of the present invention, the dye-sensitized photoelectric conversion element having excellent conversion efficiency can be obtained by treating the semiconductor fine particles with the metal alkoxide.

[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

Claims (10)

[Claims] 1. 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, wherein the semiconductor fine particles are scandium, yttrium, lanthanoid, zirconium, hafnium, tantalum. A method for producing a photoelectric conversion element, comprising: treating with an aqueous solution of an alkoxide of a metal selected from the group consisting of, indium, germanium, and tin, and then adsorbing a dye on the semiconductor fine particles. 2. The method for producing a photoelectric conversion element according to claim 1, wherein the semiconductor fine particles are titanium oxide fine particles. 3. The method for producing a photoelectric conversion element according to claim 1, wherein the aqueous solution contains an acid or an alkali. 4. The method for manufacturing a photoelectric conversion element according to claim 1, wherein the metal is zirconium.
A method for producing a photoelectric conversion element, which is selected from the group consisting of indium, hafnium and germanium. 5. The method for manufacturing a photoelectric conversion element according to claim 4, wherein the metal is hafnium or germanium. 6. The method of manufacturing a photoelectric conversion element according to claim 1, wherein the semiconductor fine particles are treated with the aqueous solution and baked, and then the dye is adsorbed. A method for manufacturing an element. 7. The method for producing a photoelectric conversion element according to claim 2, wherein the titanium oxide fine particles are mainly of anatase type. 8. The method for producing a photoelectric conversion element according to claim 1, wherein the dye is a ruthenium complex dye. 9. A photoelectric conversion element manufactured by the method according to claim 1. 10. A photovoltaic cell using the photoelectric conversion element according to claim 9.