JP5449252B2 - Photoelectric conversion element and photovoltaic cell manufacturing method - Google Patents

Description

  The present invention relates to a photoelectric conversion element using a fine particle semiconductor and a photovoltaic cell using the photoelectric conversion element. In particular, the present invention relates to a photoelectric conversion element and a photovoltaic cell sensitized with a dye.

  At present, photovoltaic power generation is the main technology for practical application, improvement of compound solar cells such as single crystal silicon solar cells, polycrystalline silicon solar cells, amorphous silicon solar cells, cadmium telluride and indium copper selenide, A power generation efficiency of around 10% is obtained as the solar energy conversion efficiency. However, in order to disseminate these for the future, it is necessary to overcome problems such as high energy costs for material production and a large environmental load for commercialization, and long energy payback time for users. For this reason, a large number of photovoltaic cells have been proposed so far, in which an organic material that can be easily increased in size and used as a photosensitive material to replace silicon has been proposed, but the energy conversion efficiency is as low as 1% or less, and the durability is high. There was also a problem of being bad. Under such circumstances, Non-Patent Document 1 and Patent Document 1 disclosed a photoelectric conversion element and a photovoltaic cell using semiconductor fine particles sensitized with a dye, and materials and manufacturing techniques necessary for the production thereof. The proposed battery is a wet solar cell using a titanium dioxide porous thin film spectrally sensitized with a ruthenium complex as a working electrode. The first advantage of this method is that an inexpensive oxide semiconductor such as titanium dioxide can be used without the need to purify it to high purity, so that it can be provided as an inexpensive photoelectric conversion element, and it is used for the second. The absorption of the dye is broad, and sunlight can be converted into electricity over a wide wavelength range of visible light. However, with the widespread use of photovoltaic cells, high temperatures exceeding 400 ° C. are used to make titanium dioxide porous thin films, and flexible supports using polymers or the like cannot be used. There was a limited problem. In addition, the use of high temperature has been a problem because it uses a large amount of energy and has a large impact on the environment.

US Patent 4927721

Nature (Vol.353, 737-740, 1991)

  The objective of this invention is providing the photoelectric conversion element excellent in energy conversion efficiency, and a photovoltaic cell using the same. Furthermore, it is providing the photoelectric conversion element using a flexible support body, and a photovoltaic cell using the same. Another object of the present invention is to provide a photoelectric conversion element with low energy consumption required for production and high energy recovery efficiency, and a photovoltaic cell using the photoelectric conversion element.

The object of the present invention has been achieved by the following items specifying the present invention and preferred embodiments thereof.
[1] In the manufacturing method of the semiconductor fine particle film photoelectric conversion device using, that the semiconductor fine particle film, the semiconductor fine particles under the following pressure 0.05 MPa, which is produced by the process comprising about Engineering you heated at 250 ° C. A process for producing a photoelectric conversion element characterized by the above.
[2] The method for producing a photoelectric conversion element according to [1], including a step of forming a layer containing semiconductor fine particles on a substrate before the heating step.
[ 3 ] The photoelectric conversion according to [1] or [2] , wherein the semiconductor fine particles forming the semiconductor fine particle film contain particles having a particle size of 10 nm or more and less than 10 nm. Device manufacturing method.
[ 4 ] The method for producing a photoelectric conversion element according to any one of [1] to [ 3 ], wherein the semiconductor fine particle film is sensitized with a dye.
[ 5 ] The semiconductor fine particles are titanium oxide, zinc oxide, tin oxide, tungsten oxide, niobium oxide, iron oxide, alkaline earth metal titanate, alkali metal titanate, or a composite thereof [1] ] The manufacturing method of the photoelectric conversion element of any one of [ 4 ].
[ 6 ] The method for producing a photoelectric conversion element according to any one of [1] to [ 5 ], wherein the semiconductor fine particle film is provided on a polymer support.
[ 7 ] A method for producing a photovoltaic cell including a photoelectric conversion element, wherein the photoelectric conversion element is produced by the method for producing a photoelectric conversion element according to any one of [1] to [ 6 ]. Manufacturing method.
The present invention is the invention according to the above [1] to [ 7 ], but other matters are also described below for reference.
(1) In a photoelectric conversion element using a semiconductor fine particle film, the semiconductor fine particle film includes a step of irradiating ultraviolet light having a wavelength of 400 nm or less having absorption by the semiconductor fine particles in the coexistence of the semiconductor fine particles and the semiconductor fine particle precursor. A photoelectric conversion element manufactured.
(2) In the photoelectric conversion element using the semiconductor fine particle film, the semiconductor fine particle film heats the semiconductor fine particles at 50 ° C. or higher and lower than 350 ° C. and the step of irradiating ultraviolet light having a wavelength of 400 nm or less that the semiconductor fine particles absorb. A photoelectric conversion element produced by a method including:
(3) In the photoelectric conversion element using the semiconductor fine particle film, the semiconductor fine particle film is produced by a method including a step of heating the semiconductor fine particles at a pressure of 0.05 MPa or less at 50 ° C. or more and less than 350 ° C. A characteristic photoelectric conversion element.
(4) A photoelectric conversion element using a semiconductor fine particle film, wherein the semiconductor fine particle film is produced by a method including a step of irradiating semiconductor fine particles with microwaves.
(5) A photoelectric conversion element using a semiconductor fine particle film, wherein the semiconductor fine particle film is produced by a method including a step of irradiating the semiconductor fine particles with infrared rays absorbed by water molecules.
(6) In the photoelectric conversion element of (1) to (5), the semiconductor fine particles forming the semiconductor fine particle film are characterized by containing particles having a particle size of 10 nm or more and those having a particle size of less than 10 nm. A photoelectric conversion element.
(7) The photoelectric conversion element according to any one of (2) to (6), wherein a semiconductor fine particle precursor is allowed to coexist when the semiconductor fine particle film is produced.
(8) In the photoelectric conversion device according to (1) or (7), the semiconductor fine particle precursor may completely or partially include a metal alkoxide compound, a halide, or a compound containing a hydrolyzable group constituting the semiconductor. A photoelectric conversion element that is hydrolyzed and that is completely or partially polymerized.
(9) The photoelectric conversion element according to any one of (1) to (8), wherein the semiconductor fine particle film is sensitized with a dye.
(10) In the photoelectric conversion element of (1) to (9), the semiconductor fine particles are titanium oxide, zinc oxide, tin oxide, tungsten oxide, niobium oxide, iron oxide, alkaline earth metal titanate, alkali metal titanate, or these A photoelectric conversion element characterized by being a composite of the above.
(11) The photoelectric conversion element according to any one of (1) to (10), wherein a semiconductor fine particle film is provided on a polymer support.
(12) A photovoltaic cell using the photoelectric conversion element of (1) to (11).

  The photoelectric conversion element of the present invention is extremely effective as a photovoltaic element because it can be assembled without using high temperature and has high photoelectric conversion efficiency.

It is a fragmentary sectional view which shows the structure of the preferable photoelectric conversion element of this invention. It is a fragmentary sectional view which shows the structure of the preferable photoelectric conversion element of this invention. It is a fragmentary sectional view which shows the structure of the preferable photoelectric conversion element of this invention. It is a fragmentary sectional view which shows the structure of the preferable photoelectric conversion element of this invention. It is a fragmentary sectional view which shows the structure of the preferable photoelectric conversion element of this invention. It is a fragmentary sectional view which shows the structure of the preferable photoelectric conversion element of this invention. It is a fragmentary sectional view which shows the structure of the preferable photoelectric conversion element of this invention. It is a fragmentary sectional view which shows the structure of the preferable photoelectric conversion element of this invention. It is a fragmentary sectional view which shows the structure of the preferable photoelectric conversion element of this invention. It is a schematic diagram which shows the example of how to overlap the electrode in an Example.

[1] Photoelectric Conversion Element The photoelectric conversion element of the present invention is preferably formed by laminating a conductive layer 10, a photosensitive layer 20, a charge transfer layer 30, and a counter electrode conductive layer 40 in this order, as shown in FIG. It is composed of semiconductor fine particles 21 sensitized by the dye 22 and a charge transport material 23 that has penetrated into the gaps between the semiconductor fine particles 21 (the semiconductor fine particles 21 are in contact with each other and connected to form a porous film. ). The charge transport material 23 is composed of the same components as the material used for the charge transfer layer 30. Further, a substrate 50 may be provided as a base for the conductive layer 10 and / or the counter electrode conductive layer 40 in order to impart strength to the photoelectric conversion element. Hereinafter, in the present invention, the layer composed of the conductive layer 10 and the optionally provided substrate 50 is referred to as “conductive support”, and the layer composed of the counter electrode conductive layer 40 and the optionally provided substrate 50 is referred to as “counter electrode”. Note that the conductive layer 10, the counter electrode conductive layer 40, and the substrate 50 in FIG. 1 may be the transparent conductive layer 10a, the transparent counter electrode conductive layer 40a, and the transparent substrate 50a, respectively. A photocell is made for the purpose of generating electrical work by connecting this photoelectric conversion element to an external load (power generation), and a photosensor is made for the purpose of sensing optical information. Among the photovoltaic cells, the case where the charge transport material 23 is mainly made of an ion transport material is particularly called a photoelectrochemical cell, and the case where the main purpose is power generation by sunlight is called a solar cell.

  In the photoelectric conversion element of the present invention shown in FIG. 1, the light incident on the photosensitive layer 20 containing the semiconductor fine particles 21 sensitized by the dye 22 excites the dye 22 and the like, and the high energy in the excited dye 22 and the like. Electrons are transferred to the conduction band of the semiconductor fine particles 21 and further reach the conductive layer 10 by diffusion. At this time, the molecule such as the dye 22 is an oxidant. In the photovoltaic cell, the electrons in the conductive layer 10 return to the oxidant such as the dye 22 through the counter electrode conductive layer 40 and the charge transfer layer 30 while working in the external circuit, and the dye 22 is regenerated. The photosensitive layer 20 functions as a negative electrode (photoanode), and the counter electrode 40 functions as a positive electrode. At the boundary of each layer (for example, the boundary between the conductive layer 10 and the photosensitive layer 20, the boundary between the photosensitive layer 20 and the charge transfer layer 30, the boundary between the charge transfer layer 30 and the counter electrode conductive layer 40, etc.) They may be diffusively mixed with each other. Each layer will be described in detail below.

(A) Conductive support The conductive support comprises (1) a single layer of a conductive layer, or (2) two layers of a conductive layer and a substrate. In the case of (1), a material that can sufficiently maintain strength and hermeticity is used as the conductive layer. For example, a metal material can be used. In the case of (2), a substrate having a conductive layer containing a conductive agent on the photosensitive layer side can be used. Preferred conductive agents include metals (eg, platinum, gold, silver, copper, zinc, titanium, aluminum, indium, etc.), carbon, or conductive metal oxides (indium-tin composite oxide, tin oxide doped with fluorine or antimony) Etc.). The thickness of the conductive layer is preferably about 0.02 to 10 μm.

  The lower the surface resistance of the conductive support, the better. The range of the surface resistance is preferably 50Ω / □ or less, more preferably 20Ω / □ or less.

  When irradiating light from the conductive support side, the conductive support is preferably substantially transparent. Substantially transparent means that the light transmittance is 10% or more, preferably 50% or more, and particularly preferably 80% or more.

The transparent conductive support is preferably formed by applying or vapor-depositing a transparent conductive layer made of a conductive metal oxide on the surface of a transparent substrate such as glass or plastic. Preferred as the transparent conductive layer is fluorine dioxide or antimony doped tin dioxide or indium-tin oxide (ITO). As the transparent substrate, a transparent polymer film can be used in addition to a glass substrate such as soda glass which is advantageous in terms of low cost and strength, alkali-free glass which is not affected by alkali elution. Transparent polymer film materials include tetraacetyl cellulose (TAC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), syndiotactic polyester (SPS), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate. (PAr), polysulfone (PSF), polyester sulfone (PES), polyetherimide (PEI), cyclic polyolefin, brominated phenoxy and the like. In order to ensure sufficient transparency, the coating amount of the conductive metal oxide is preferably 0.01 to 100 g per 1 m ² of glass or plastic support.

  It is preferable to use a metal lead for the purpose of reducing the resistance of the transparent conductive support. The material of the metal lead is preferably a metal such as platinum, gold, nickel, titanium, aluminum, copper, or silver. The metal lead is preferably provided on a transparent substrate by vapor deposition, sputtering or the like, and a transparent conductive layer made of conductive tin oxide or ITO film is preferably provided thereon. The decrease in the amount of incident light due to the installation of the metal lead is preferably within 10%, more preferably 1 to 5%.

(B) Photosensitive layer In the photosensitive layer, the semiconductor acts as a photoconductor, absorbs light, separates charges, and generates electrons and holes. In a dye-sensitized semiconductor, light absorption and the generation of electrons and holes thereby occur mainly in the dye, and the semiconductor particles play a role of receiving and transmitting these electrons (or holes). The semiconductor used in the present invention is preferably an n-type semiconductor in which conductor electrons become carriers under photoexcitation and give an anode current.

(1) Semiconductor Semiconductor fine particles include simple semiconductors such as silicon and germanium, III-V compound semiconductors, metal chalcogenides (for example, oxides, sulfides, selenides, etc.), or compounds having a perovskite structure (for example, titanium). Strontium acid, calcium titanate, sodium titanate, barium titanate, potassium niobate, etc.) can be used.

  Preferred metal chalcogenides include titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium or tantalum oxides, cadmium, zinc, lead, silver, antimony or Bismuth sulfide, cadmium or lead selenide, 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.

Preferred specific examples of the semiconductor used in the present invention are Si, TiO ₂ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , ZnO, Nb ₂ O ₅ , CdS, ZnS, PbS, Bi ₂ S ₃ , CdSe, CdTe, GaP InP, GaAs, CuInS ₂ , CuInSe _{2 and the} like, more preferably TiO ₂ , ZnO, SnO ₂ , Fe ₂ O ₃ , WO ₃ or Nb ₂ O ₅ , or alkaline earth titanate or alkali metal titanate Particularly preferred is TiO ₂ , ZnO, SnO ₂ or Nb ₂ O ₅ , and most preferred is TiO ₂ . These semiconductors may be used alone or as a composite (mixture, mixed crystal, solid solution, etc.).

  The semiconductor used in the present invention may be single crystal or polycrystalline. From the viewpoint of conversion efficiency, a single crystal is preferable, but from the viewpoint of manufacturing cost, securing raw materials, energy payback time, and the like, polycrystalline is preferable, and a porous film made of semiconductor fine particles is particularly preferable.

  The particle size of the semiconductor fine particles is generally on the order of nm to μm, but the average particle size of the primary particles obtained from the diameter when the projected area is converted into a circle is preferably 5 to 200 nm, more preferably 8 to 100 nm. preferable. In the present invention, it is preferable that particles having a particle size of 10 nm or more and particles having a particle size of 10 nm or less are included. The average particle size of the semiconductor fine particles (secondary particles) in the dispersion is preferably 0.01 to 30 μm.

  Two or more types of fine particles having different particle size distributions may be mixed. In this case, the average size of the small particles is preferably 10 nm or less. For the purpose of scattering incident light and improving the light capture rate, semiconductor particles having a large particle size, for example, about 300 nm may be mixed.

  Semiconductor fine particles are prepared by Sakuo Sakuo's "Sol-gel Method Science" Agne Jofusha (1998), Technical Information Association "Sol-gel Method Thin Film Coating Technology" (1995), etc. The sol-gel method described, Tadao Sugimoto's "Synthesis and size control of monodisperse particles by the new synthetic gel-sol method", Materia, Vol. 35, No. 9, pp. 1012-1018 (1996) The gel-sol method described in 1 is preferred. Also preferred is a method developed by Degussa to produce an oxide by high-temperature hydrolysis of chloride in an oxyhydrogen salt.

  When the semiconductor fine particles are titanium oxide, the sol-gel method, gel-sol method, and high-temperature hydrolysis method in oxyhydrogen salt of chloride are all preferred, but Kiyoshi Manabu's “Titanium oxide properties and applied technology” The sulfuric acid method and the chlorine method described in Gihodo Publishing (1997) can also be used. Further, as a sol-gel method, the method described in Journal of American Ceramic Society of Barbe et al., Vol. 80, No. 12, pp. 3157-3171 (1997), the chemistry of Burnside et al. , Vol. 10, No. 9, pages 2419-2425 are also preferred.

  Titanium oxide has mainly two types of crystal forms, anatase type and rutile type. In the present invention, the anatase type is preferable. In the case of a mixture of the two, it is preferable that the content of the anatase type is higher, and more preferably 80% or more. The anatase content can be determined by X-ray diffraction, and can be determined from the ratio of the diffraction peak intensities derived from anatase and rutile.

(2) Semiconductor fine particle film In order to apply semiconductor fine particles on a conductive support, in addition to the method of applying a dispersion or colloidal solution of semiconductor fine particles on a conductive support, the sol-gel method described above is used. It can also be used. In consideration of mass production of photoelectric conversion elements, physical properties of semiconductor fine particle liquid, flexibility of conductive support, etc., a wet film forming method is relatively advantageous. As a wet film forming method, a coating method and a printing method are typical.

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

  The semiconductor fine particle layer is not limited to a single layer, but a multi-layer coating of a dispersion of semiconductor fine particles having different particle diameters, or a multi-layer coating of a coating layer containing different types of semiconductor fine particles (or different binders and additives) You can also Multi-layer coating is also effective when the film thickness is insufficient with a single coating. For multilayer coating, an extrusion method or a slide hopper method is suitable. In the case of applying multiple layers, the multiple layers may be applied at the same time, or may be successively applied several times to several dozen times. Further, screen printing can be preferably used as long as it is sequentially overcoated.

In general, as the thickness of the semiconductor fine particle layer (same as the thickness of the photosensitive layer) increases, the amount of supported dye increases per unit projected area, and thus the light capture rate increases. Loss due to coupling also increases. Therefore, the preferred thickness of the semiconductor fine particle layer is 0.1 to 100 μm. When used for a solar cell, the thickness of the semiconductor fine particle layer is preferably 1 to 30 μm, and more preferably 2 to 25 μm. The coating amount per 1 m ² of the semiconductor fine particles is preferably 0.5 to 100 g, more preferably 3 to 50 g.

When semiconductor fine particles are used as a constituent element of a photoelectric conversion element, the function as a semiconductor fine particle film has been developed by “sintering”. That is, after making the fine particles into a laminated state by the above-mentioned application, etc., by heating at a high temperature, some of the fine particles are fused to develop conductivity, and unnecessary particles on the surface of the fine particles are removed and activated. This promotes the adsorption / bonding of the sensitizing dye, which is the next step, and increases the efficiency of photoelectron injection from the sensitizing dye into the fine particles. However, this “calcination” required heating at a high temperature of 400 ° C. or higher. (Depending on the composition of the semiconductor fine particles, it was preferable to heat at 450 ° C. or higher in the case of TiO ₂ ).

In this invention, in order to express this baking state, without heating at high temperature, the following methods are used individually or in combination of 2 or more.
(1) Heat semiconductor fine particles to 50 ° C. or higher and lower than 350 ° C.
(2) Irradiating the semiconductor fine particles with ultraviolet light having a wavelength of 400 nm or less that the semiconductor fine particles absorb.
(3) Irradiate semiconductor particles with microwaves.
(4) Irradiate the semiconductor fine particles with infrared light having a wavelength at which water molecules absorb.
(5) The semiconductor fine particles are depressurized under a pressure of 0.05 MPa or less.
(6) Place semiconductor fine particles in an ozone atmosphere.
(7) Place semiconductor fine particles under oxidizing or reducing conditions.
(8) Place semiconductor particles under a high electric field.
(9) Place semiconductor fine particles under high magnetic field.
(10) A high current is passed through the semiconductor fine particles.
(11) A semiconductor fine particle precursor is allowed to coexist with semiconductor fine particles.

That is, in order to fuse fine particles, some energy must be supplied to the fine particles, and the substance should move to the contact points between the particles by surface diffusion, grain boundary diffusion, etc., and a neck (contact portion between particles) must be formed. I must. In addition to giving thermal energy as this energy (1), by giving energy ((2), (3), (4), (8), (9)) by electromagnetic waves or by passing a high current, the semiconductor itself and Heat generation due to resistance at grain boundaries (10) is effective.
In addition, to remove and activate unwanted particles on the surface of the fine particles, evaporation, decomposition, etc. are performed by heating (1), evaporation is promoted by reduced pressure (5), and decomposition by chemical reaction ((6) (7)) is also effective. In addition, in the case of particles such as TiO ₂ particles having a photocatalytic function that generates strong oxidizing or reducing species by light irradiation, it is also effective to perform light irradiation. In the case of TiO ₂ particles, the ultraviolet irradiation of (2) is particularly effective. Furthermore, coexistence of the semiconductor fine particle precursor of (11) under each of the above conditions is effective for the diffusion and supply of substances and the reduction of necessary energy, and the semiconductor fine particle film having a photoelectric conversion function can be formed at a lower temperature. Is preferable. The heating in (1) is preferably a high temperature for fusion between the semiconductor fine particles, but a lower temperature is more preferable from the viewpoint of resistance when a polymer support is used. Therefore, the upper limit of the heating temperature is preferably 300 ° C, more preferably 250 ° C. Moreover, 80 degreeC is preferable and the minimum of heating temperature has more preferable 100 degreeC.

As a preferable combination of the above methods (1) to (11), the method for fusion between fine particles ((1) to (4), (8) to (10)) and unnecessary particles on the surface of the fine particles are removed. The method for activation ((1), (5) to (7)) is preferably combined, and it is preferable to further combine (11). In addition, two or more methods for fusion between fine particles ((1) to (4), (8) to (10)), a method for removing and activating unnecessary particles on the surface of the fine particles ((1), It is also effective to combine two or more of (5) to (7)), and more effective by combining them.
Examples of preferred combinations are (1) + (2), (1) + (3), (1) + (4), (1) + (5), (1) + (2) + (5) , (4) + (5), (2) + (4) + (5), (3) + (5), (1) + (2) + (6), (4) + (6), ( 3) + (7), (1) + (3) + (7), (1) + (8), (1) + (2) + (8), (1) + (2) + (8) + (10) and the like, and (11) is preferably combined with these. The combinations for obtaining the above effects are not limited to these.

  Moreover, the combination process of said method may be used simultaneously with respect to semiconductor fine particles, and may be used continuously. That is, for example, in the combination of (1) + (2), (1) and (2) may be performed simultaneously, (1) may be performed, and (2) may be performed, or ( (1) may be performed after performing 2), or (1) alone may be performed after performing (1) and (2) simultaneously.

Regarding (2), when the semiconductor particles are particularly titanium oxide, the surface of the particles may be superhydrophilic, and depending on the purpose, it may be better to use at the end of the process or not. Similarly for (1), contrary to (2), when the semiconductor particles are particularly titanium oxide, the surface of the particles may be hydrophobized. (2) Similarly, depending on the purpose, it is better to use at the end of the process. Sometimes it is better not to use it.
For example, when the sensitizing dye is adsorbed on the surface of the semiconductor fine particle film as a subsequent step, particularly in the case of a hydrophobic dye, the adsorptivity is better when the particle surface is hydrophobic. Therefore, in this case, it is preferable to perform (1) after (2) or (1) alone after (1) + (2) as the above combination.

The semiconductor fine particle precursor of (11) may be any precursor as long as it becomes a semiconductor fine particle upon heating. When the semiconductor fine particle is a metal oxide, a metal alkoxide, a metal halide, a metal compound having a hydrolyzable group, and the like can be used as the precursor. Here, the hydrolyzable group may be any group as long as it can be substituted with a proton or a hydroxyl group, and preferably includes an acyloxy group, an alkoxycarbonyloxy group, a carbamoyloxy group, and the like. Further, a precursor obtained by partially or fully hydrolyzing the precursor metal compound, a polymer obtained by polymerizing the hydrolyzate, or a mixture thereof is also effective as a precursor. In particular, a mixture obtained by partially hydrolyzing a metal alkoxide or metal halide under an acid or alkali condition and further partially polymerizing is effective because of its low temperature reactivity. Preferred acids in that case include hydrochloric acid and nitric acid, with hydrochloric acid being most preferred.
The metal is preferably the same as the main metal of the semiconductor fine particles, which is the main component of the semiconductor fine particle film, but other metals may be used. In particular, titanium and silicon are effective because hydrolysis and polymerization occur at low temperatures. Said precursor may be used independently and may use 2 or more types together.

  After the above baking treatment, for example, chemical plating or trichloride using an aqueous solution of titanium tetrachloride for the purpose of increasing the surface area of the semiconductor particles, increasing the purity in the vicinity of the semiconductor particles, and increasing the efficiency of electron injection from the dye to the semiconductor particles. Electrochemical plating using a titanium aqueous solution may be performed.

  The semiconductor fine particle layer is preferably a porous film having a large surface area so that a large amount of dye can be adsorbed. For this reason, the surface area of the semiconductor fine particle layer coated on the support is preferably 10 times or more, more preferably 100 times or more the projected area. The upper limit is not particularly limited, but is usually about 1000 times.

(3) Dye The sensitizing dye used in the photosensitive layer can be arbitrarily used as long as it is a compound that has absorption in the visible region and near infrared region and can sensitize semiconductors, but organometallic complex dyes, methine dyes, porphyrins. A dye or a phthalocyanine dye is preferable. Moreover, in order to make the wavelength range of photoelectric conversion as wide as possible and increase the conversion efficiency, two or more kinds of dyes can be used together or mixed. In this case, the dye to be used or mixed and the ratio thereof can be selected so as to match the wavelength range and intensity distribution of the target light source.

Such a dye preferably has an appropriate interlocking group capable of adsorbing to the surface of the semiconductor fine particles. Preferred linking groups include COOH groups, OH groups, SO ₃ H groups, acidic groups such as —P (O) (OH) ₂ groups or —OP (O) (OH) ₂ groups, or oximes, dioximes, and hydroxy groups. Examples include chelating groups having π conductivity such as quinoline, salicylate or α-ketoenolate. Of these, a COOH group, —P (O) (OH) ₂ group or —OP (O) (OH) ₂ group is particularly preferred. These groups may form a salt with an alkali metal or the like, or may form an internal salt. In the case of a polymethine dye, if the methine chain contains an acidic group as in the case where the methine chain forms a squarylium ring or a croconium ring, this part may be used as a linking group.

Hereinafter, preferred sensitizing dyes used in the photosensitive layer will be specifically described.
(A) Organometallic complex dye When the dye is a metal complex dye, a metal phthalocyanine dye, a metal porphyrin dye or a ruthenium complex dye is preferable, and a ruthenium complex dye is particularly preferable. Examples of the ruthenium complex dye include U.S. Pat. Nos. 4,972,721, 4,684,537, 5,844,365, 5,350,644, 5,630,57, 5,525,440, JP-A-7-249790, JP-A-10-504512, WO98 / 50393. And complex dyes described in JP-A-2000-26487.

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

(However, Ra represents _a hydrogen atom or a substituent. Examples of the substituent include a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, and a substituted or unsubstituted group having 7 to 12 carbon atoms. Aralkyl group, substituted or unsubstituted aryl group having 6 to 12 carbon atoms, carboxylic acid group, phosphoric acid group (these acid groups may form a salt), alkyl group and aralkyl group The alkyl part of the aryl group and the aryl part of the aralkyl group may be monocyclic or polycyclic (condensed ring, ring assembly)). Represents a quantifier. Ba, Bb and Bc may be the same or different, and may be any one or two.

  Although the preferable specific example of an organometallic complex pigment | dye is shown below, this invention is not limited to these.

(B) Methine dyes Preferred methine dyes for use in the present invention are polymethine dyes such as cyanine dyes, merocyanine dyes, and squarylium dyes. Examples of polymethine dyes preferably used in the present invention include JP-A Nos. 11-35836, 11-67285, 11-86916, 11-97725, 11-158395, and 11-158395. -163378, JP-A-11-214730, JP-A-11-214731, JP-A-11-238905, European Patents 892411 and 918441.

(4) Adsorption of dye to semiconductor fine particles In order to adsorb the dye to semiconductor fine particles, a conductive support having a well-dried semiconductor fine particle layer is immersed in the dye solution, or the dye solution is applied to the semiconductor fine particle layer. A coating method can be used. In the former case, an immersion method, a dip method, a roller method, an air knife method or the like can be used. In the case of the immersion method, the adsorption of the dye may be performed at room temperature or may be performed by heating and refluxing as described in JP-A-7-249790. Examples of the latter application method include a wire bar method, a slide hopper method, an extrusion method, a curtain method, a spin method, and a spray method. Preferred solvents for dissolving the dye include, for example, alcohols (methanol, ethanol, t-butanol, benzyl alcohol, etc.), nitriles (acetonitrile, propionitrile, 3-methoxypropionitrile, etc.), nitromethane, halogenated compounds, etc. Hydrocarbon (dichloromethane, dichloroethane, chloroform, chlorobenzene, etc.), ethers (diethyl ether, tetrahydrofuran, etc.), dimethyl sulfoxide, amides (N, N-dimethylformamide, N, N-dimethylacetamide, etc.), N-methyl Pyrrolidone, 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.), Examples include hydrocarbons (hexane, petroleum ether, benzene, toluene, etc.) and mixed solvents thereof.

The total amount of dye adsorbed is preferably 0.01 to 100 mmol per unit surface area (1 m ² ) of the porous semiconductor electrode substrate. The amount of the dye adsorbed on the semiconductor fine particles is preferably in the range of 0.01 to 100 ml / g of the semiconductor fine particles. By using such an amount of dye adsorbed, a sensitizing effect in a semiconductor can be sufficiently obtained. On the other hand, if the amount of the dye is too small, the sensitizing effect becomes insufficient, and if the amount of the dye is too large, the dye not attached to the semiconductor floats, which causes a reduction in the sensitizing effect. In order to increase the adsorption amount of the dye, it is preferable to perform a heat treatment before the adsorption. In order to avoid water adsorbing on the surface of the semiconductor fine particles after the heat treatment, it is preferable to quickly adsorb the dye between 40 to 80 ° C. without returning to normal temperature. Further, for the purpose of reducing the interaction such as aggregation between the dyes, a colorless compound may be added to the dyes and co-adsorbed on the semiconductor fine particles. Compounds effective for this purpose are compounds having surface active properties and structures, and examples thereof include steroid compounds having a carboxyl group (for example, chenodeoxycholic acid) and surfactants such as sulfonates.

The unadsorbed dye is preferably removed by washing immediately after adsorption. It is preferable to use a wet cleaning tank and perform cleaning with a polar solvent such as acetonitrile or an organic solvent such as an alcohol solvent. After adsorbing the dye, the surface of the semiconductor fine particles may be treated with amines. Preferable amines include pyridine, 4-t-butylpyridine, polyvinylpyridine and the like. When these are liquids, they may be used as they are, or may be used after being dissolved in an organic solvent.
(C) Charge transfer layer The charge transfer layer is a layer containing a charge transport material having a function of replenishing electrons to the oxidant of the dye. Examples of typical charge transport materials that can be used in the present invention include: [1] As an ion transport material, a solution (electrolytic solution) in which ions of a redox pair are dissolved, and a solution of a redox pair are polymer matrix gels. So-called gel electrolytes impregnated in the above, molten salt electrolytes containing redox counterions, and solid electrolytes. In addition to the charge transport material in which ions are involved, [2] an electron transport material or a hole transport material can also be used as a material in which carrier movement in a solid is involved in electrical conduction. These can be used in combination.

(1) Molten salt electrolyte The molten salt electrolyte is particularly preferable from the viewpoint of achieving both photoelectric conversion efficiency and durability. Examples of the molten salt electrolyte include pyridinium salts, imidazolium salts, and triazolium salts described in WO95 / 18456, JP-A-8-259543, Electrochemistry, Vol. 65, No. 11, 923 (1997), etc. And electrolytes containing known iodine salts.

  Examples of the molten salt that can be preferably used include those represented by any of the following general formulas (Y-a), (Y-b), and (Y-c).

In the general formula (Ya), Qy ₁ represents an atomic group capable of forming a 5- or 6-membered aromatic cation with a nitrogen atom. Qy ₁ is preferably composed of one or more atoms selected from the group consisting of carbon atom, hydrogen atom, nitrogen atom, oxygen atom and sulfur atom. The 5-membered ring formed by Qy ₁ is preferably an oxazole ring, thiazole ring, imidazole ring, pyrazole ring, isoxazole ring, thiadiazole ring, oxadiazole ring or triazole ring, An imidazole ring is more preferable, and an oxazole ring or an imidazole ring is particularly preferable. The 6-membered ring formed by Qy ₁ is preferably a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring or a triazine ring, and more preferably a pyridine ring.

In the general formula (Yb), Ay ₁ represents a nitrogen atom or a phosphorus atom.

In the general formulas (Ya), (Yb) and (Yc), Ry ₁ to Ry ₆ are each independently a substituted or unsubstituted alkyl group (preferably having 1 to 24 carbon atoms, linear or branched). Or may be cyclic. For example, methyl, ethyl, propyl, isopropyl, pentyl, hexyl, octyl, 2-ethylhexyl, t-octyl, decyl, 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, linear or branched) And may be, for example, a vinyl group, an allyl group, etc., more preferably an alkyl group having 2 to 18 carbon atoms or an alkenyl group having 2 to 18 carbon atoms, particularly preferably 2 to 2 carbon atoms. 6 alkyl groups.

Further, two or more of Ry ₁ to Ry _{4 in} the general formula (Yb) may be connected to each other to form a non-aromatic ring containing Ay _1, and Ry ₁ to Ry in the general formula (Yc) Two or more of ₆ may be connected to each other to form a ring structure.

Qy ₁ and Ry _{1 to} Ry ₆ in the general formulas (Ya), (Yb) and (Yc) may have a substituent. Examples of preferred substituents include halogen atoms (F, Cl, Br , I etc.), cyano group, alkoxy group (methoxy group, ethoxy group etc.), aryloxy group (phenoxy group etc.), alkylthio group (methylthio group, ethylthio group etc.), alkoxycarbonyl group (ethoxycarbonyl group etc.), carbonate 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.), amide group ( Acetylamino group, benzoylamino 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 group (phenyl group, toluyl group etc.), heterocyclic group (pyridyl group, imidazolyl group, furanyl group etc.), alkenyl group (vinyl group, 1-propenyl group etc.) and the like.

The compound represented by the general formula (Ya), (Yb) or (Yc) may form a multimer via Qy ₁ or Ry _{1 to} Ry ₆ .

These molten salts may be used singly or as a mixture of two or more, and may be used in combination with a molten salt in which the iodine anion is replaced with another anion. The anionic replaced with iodine anion, halide ions (Cl ^-, Br ^{-, _{etc.), NSC -, BF 4 -}} , PF 6 -, ClO 4 -, (CF 3 SO 2) 2 N -, (CF 3 CF 2 SO ₂ ) ₂ N ⁻ , CF ₃ SO ₃ ⁻ , CF ₃ COO ⁻ , Ph ₄ B ⁻ , (CF ₃ SO ₂ ) ₃ C ^{− and the} like are preferred examples, and (CF ₃ SO ₂ ) ₂ N ⁻ or BF ₄ ^- and more preferable. Also, other iodine salts such as LiI can be added.

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

  The molten salt electrolyte is preferably in a molten state at room temperature, and preferably does not use a solvent. Although the solvent described later may be added, the content of the molten salt is preferably 50% by mass or more, and particularly preferably 90% by mass or more with respect to the entire electrolyte composition. Moreover, it is preferable that 50 mass% or more is an iodine salt among salts.

  It is preferable to add iodine to the electrolyte composition. In this case, the content of iodine is preferably 0.1 to 20% by mass, and 0.5 to 5% by mass with respect to the entire electrolyte composition. Is more preferable.

(2) Electrolytic Solution When an electrolytic solution is used for the charge transfer layer, the electrolytic solution is preferably composed of an electrolyte, a solvent, and an additive. The electrolyte of the present invention is a metal iodide such as a combination of I ₂ and iodide (LiI, NaI, KI, CsI, CaI ₂ as iodide), tetraalkylammonium iodide, pyridinium iodide, imidazolium iodide, etc. Iodine salts of quaternary ammonium compounds), Br ₂ and bromide combinations (bromides include metal bromides such as LiBr, NaBr, KBr, CsBr, CaBr ₂ or bromine of quaternary ammonium compounds such as tetraalkylammonium bromide and pyridinium bromide) Salts), metal complexes such as ferrocyanate-ferricyanate and ferrocene-ferricinium ions, sulfur compounds such as sodium polysulfide and alkylthiol-alkyldisulfides, viologen dyes, hydroquinone-quinones, etc. Can do. Among these, electrolytes in which iodine salts of quaternary ammonium compounds such as I ₂ and LiI, pyridinium iodide, and imidazolium iodide are combined are preferable. The electrolytes described above may be used in combination.

  A preferable electrolyte concentration is 0.1 M or more and 15 M or less, and more preferably 0.2 M or more and 10 M or less. In addition, when iodine is added to the electrolyte, a preferable iodine concentration is 0.01 M or more and 0.5 M or less.

  The solvent used for the electrolyte is desirably a compound having a low viscosity and improving ion mobility, or having a high dielectric constant and an effective carrier concentration, thereby exhibiting excellent ion conductivity. 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, and polyethylene. Chain ethers such as glycol dialkyl ether and 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, polyhydric alcohols such as glycerin, acetonitrile, glutarodinitrile, methoxy acetonitrile, propionitrile, nitrile compounds such as benzonitrile, dimethyl sulfoxide, can be used aprotic polar substances such as sulfolane, water, and the like.

  In the present invention, tert-butylpyridine, 2-picoline, 2,6-lutidine and the like described in J. Am. Ceram. Soc., 80, (12) 3157-3171 (1997) Basic compounds can also be added. A preferable concentration range when adding the basic compound is 0.05 M or more and 2 M or less.

(3) Gel Electrolyte In the present invention, the electrolyte can be used after being gelled (solidified) by techniques such as addition of a polymer, addition of an oil gelling agent, polymerization including polyfunctional monomers, and a crosslinking reaction of the polymer. In the case of gelation by addition of a polymer, compounds described in “Polymer Electrolyte Reviews-1 and 2” (JR MacCallum and CA Vincent, edited by ELSEVIERAPPLIED SCIENCE) can be used. In particular, polyacrylonitrile, polyvinylidene fluoride, and the like can be used. Can be preferably used. In the case of gelation by adding an oil gelling agent, J. Chem. Soc. Japan, Ind. Chem. Sec., 46, 779 (1943), 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, 885, J. Chm. Soc. Chem. Commun ., 1997, 545 can be used, but preferred compounds are those having an amide structure in the molecular structure.

  Further, when the electrolyte is gelled by a polymer crosslinking reaction, it is desirable to use a polymer containing a crosslinkable reactive group and a crosslinking agent in combination. In this case, a preferable crosslinkable reactive group is a nitrogen-containing heterocyclic ring (for example, a pyridine ring, an imidazole ring, a thiazole ring, an oxazole ring, a triazole ring, a morpholine ring, a piperidine ring, a piperazine ring), and a preferable crosslinking agent. Is a bifunctional or higher functional reagent (for example, alkyl halide, halogenated aralkyl, sulfonate ester, acid anhydride, acid chloride, isocyanate, etc.) capable of electrophilic reaction with a nitrogen atom.

(4) Hole transport material In the present invention, instead of an ion conductive electrolyte such as a molten salt, a solid hole transport material combining organic or inorganic or a combination of both can be used.
(A) Organic hole transport material Organic hole transport materials applicable to the present invention include J. Hagen et al., Synthetic Metal 89 (1997) 215-220, Nature, Vol. 395, 8 Oct. 1998, p583. -585 and WO 97/10617, JP 59-194393, JP 5-34681, U.S. Pat.No. 4,923,774, JP 4-308688, U.S. Pat.No. 4,764,625, JP 3-269084 JP, 4-129271, JP 4-175395, JP 4-264189, JP 4-90851, JP 4-364153, JP 5-25473, JP-A-5-239455, JP-A-5-320634, JP-A-6-1972, JP-A-7-138562, JP-A-7-252474, JP-A-11-144773 And triphenylene derivatives described in JP-A-11-149821, JP-A-11-148067, JP-A-11-176489 and the like can be preferably used.
Also, Adv. Mater. 1997, 9, No. 7, p557, Angew. Chem. Int. Ed. Engl. 1995, 34, No. 3, p303-307, JACS, Vol. 120, No. 4, 1998, Oligothiophene compounds described in p664-672 and the like, polypyrrole described in K. Murakoshi et al., Chem. Lett. 1997, p471, “Handbook of Organic Conductive Molecules and Polymers Vol.1,2,3,4” (NALWA, published by WILEY), polyacetylene and its derivatives, poly (p-phenylene) and its derivatives, poly (p-phenylenevinylene) and its derivatives, polythienylene vinylene and its derivatives, polythiophene and its derivatives Conductive polymers such as polyaniline and derivatives thereof and polytoluidine and derivatives thereof can be preferably used.
Hole transport materials include tris (4-bromophenyl) aminium hexachloroantimonate to control the dopant level as described in Nature, Vol. 395, 8 Oct. 1998, p583-585. Such as Li [(CF ₃ SO ₂ ) ₂ N] to add potential compounds on the surface of oxide semiconductors (space charge layer compensation). It doesn't matter.

(B) Inorganic hole transport material A p-type inorganic compound semiconductor can be used as the inorganic hole transport material. The p-type inorganic compound semiconductor for this purpose preferably has a band gap of 2 eV or more, and more preferably 2.5 eV or more. Also, the ionization potential of the p-type inorganic compound semiconductor needs to be smaller than the ionization potential of the dye-adsorbing electrode from the condition that the holes of the dye can be reduced. Although the preferable range of the ionization potential of the p-type inorganic compound semiconductor varies depending on the dye used, it is generally preferably 4.5 eV or more and 5.5 eV or less, and more preferably 4.7 eV or more and 5.3 eV or less. . Preferred p-type inorganic compound semiconductors are compound semiconductors containing monovalent copper. Examples of compound semiconductors containing monovalent copper include CuI, CuSCN, CuInSe ₂ , Cu (In, Ga) Se ₂ , CuGaSe ₂ , Cu ₂ O, CuS, CuGaS ₂ , CuInS ₂ , CuAlSe _{2 and the} like. Among these, CuI and CuSCN are preferable, and CuI is most preferable. As other p-type inorganic compound semiconductors, GaP, NiO, CoO, FeO, Bi ₂ O ₃ , MoO ₂ , Cr ₂ O _{3 and the} like can be used.
The preferred hole mobility of the charge transfer layer containing the p-type inorganic compound semiconductor is 10 ⁻⁴ cm ² / V · sec or more and 10 ⁴ cm ² / V · sec or less, and more preferably 10 ⁻³ cm ² / V · sec. sec to 10 ³ cm ² / V · sec. The preferable conductivity of the charge transport layer is 10 ⁻⁸ S / cm or more and 10 ² S / cm or less, and more preferably S10 ⁻⁶ / cm or more and 10 S / cm or less.

(5) Formation of charge transfer layer There are two methods for forming the charge transfer layer. One is a method in which a counter electrode is first bonded onto the photosensitive layer, and a liquid charge transfer layer is sandwiched between the gaps. The other is a method in which a charge transfer layer is provided directly on the photosensitive layer, and a counter electrode is subsequently provided.

  In the former case, as a method for sandwiching the charge transfer layer, a normal pressure process using a capillary phenomenon due to immersion or a vacuum process in which the gas phase in the gap is replaced with a liquid phase at a pressure lower than normal pressure can be used.

  In the latter case, in the wet charge transfer layer, a counter electrode is provided without being dried, and measures for preventing liquid leakage at the edge portion are taken. In the case of a gel electrolyte, there is a method in which it is applied in a wet manner and solidified by a method such as polymerization. In this case, the counter electrode can be applied after drying and fixing. As a method for applying the wet organic hole transporting material and the gel electrolyte in addition to the electrolytic solution, the same methods as those for the semiconductor fine particle layer and the dye can be used.

  In the case of a solid electrolyte or a solid hole transport material, a charge transfer layer can be formed by a dry film formation process such as a vacuum deposition method or a CVD method, and then a counter electrode can be provided. The organic hole transport material can be introduced into the electrode by a technique such as a vacuum deposition method, a casting method, a coating method, a spin coating method, a dipping method, an electrolytic polymerization method, or a photoelectrolytic polymerization method. Also in the case of an inorganic solid compound, it can be introduced into the electrode by techniques such as casting, coating, spin coating, dipping, and electrolytic plating.

(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 conductive support described above. As a conductive material used for the counter electrode conductive layer, metal (for example, platinum, gold, silver, copper, aluminum, magnesium, indium, etc.), carbon, or conductive metal oxide (indium-tin composite oxide, fluorine-doped tin oxide, Etc.). Among these, platinum, gold, silver, copper, aluminum, and magnesium can be preferably used as the counter electrode layer. An example of a preferable supporting substrate for the counter electrode is glass or plastic, and the above-mentioned conductive agent is applied or vapor-deposited thereon. The thickness of the counter electrode conductive layer is not particularly limited, but is preferably 3 nm to 10 μm. When the counter electrode conductive layer is a metal, the thickness is preferably 5 μm or less, and more preferably in the range of 10 nm to 3 μm. The lower the surface resistance of the counter electrode layer, the better. The range of the surface resistance is preferably 50Ω / □ or less, and more preferably 20Ω / □ 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, it is sufficient that at least one of the conductive support and the counter electrode is substantially transparent. . From the viewpoint of improving the power generation efficiency, it is preferable to make the conductive support transparent so that light is incident from the conductive support side. In this case, the counter electrode preferably has a property of reflecting light. As such a counter electrode, glass or plastic on which a metal or a conductive oxide is deposited, or a metal thin film can be used.

  The counter electrode may be formed by directly applying, plating, or vapor-depositing (PVD, CVD) a conductive material on the charge transfer layer, or attaching the conductive layer side of the substrate having the conductive layer. Further, 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, particularly when the counter electrode is transparent. The preferable metal lead material and installation method, the reduction in the amount of incident light due to the metal lead installation, and the like are the same as those for the conductive support.

(E) Other layers In order to prevent a short circuit between the counter electrode and the conductive support, it is preferable to coat a dense semiconductor thin film layer as an undercoat layer between the conductive support and the photosensitive layer in advance. This is particularly effective when an electron transport material or a hole transport material is used for the moving layer. Preferred as the undercoat layer is 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 sputtering method in addition to the spray pyrolysis method described in Electrochimi. Acta 40, 643-652 (1995). The preferable film thickness of the undercoat layer is 5 to 1000 nm or less, and more preferably 10 to 500 nm.

  Moreover, you may provide functional layers, such as a protective layer and an antireflection layer, in the inside or the outer surface of one or both of the electroconductive support body which acts as an electrode, and a counter electrode. For forming these functional layers, a coating method, a vapor deposition method, a bonding method, or the like can be used depending on the material.

(F) Specific examples of internal structure of photoelectric conversion element As described above, the internal structure of the photoelectric conversion element can take various forms according to the purpose. If roughly divided into two, a structure that allows light to enter from both sides and a structure that allows only one side are possible. 2 to 9 illustrate the internal structure of a photoelectric conversion element that can be preferably applied to the present invention.

In FIG. 2, a photosensitive layer 20 and a charge transfer layer 30 are interposed between a transparent conductive layer 10a and a transparent counter electrode conductive layer 40a, and light is incident from both sides. In FIG. 3, a part of the metal lead 11 is provided on the transparent substrate 50a, the transparent conductive layer 10a is further provided, the undercoat layer 60, the photosensitive layer 20, the charge transfer layer 30 and the counter electrode conductive layer 40 are provided in this order and further supported. A substrate 50 is disposed, and light is incident from the conductive layer side. In FIG. 4, a conductive layer 10 is further provided on a support substrate 50, a photosensitive layer 20 is provided via an undercoat layer 60, a charge transfer layer 30 and a transparent counter electrode conductive layer 40a are provided, and a metal lead 11 is partly provided. The transparent substrate 50a provided with the metal lead 11 side is arranged inside, and light is incident from the counter electrode side. FIG. 5 shows that an undercoat layer 60, a photosensitive layer 20, and a charge transfer layer 30 are interposed between a pair of metal leads 11 provided on a transparent substrate 50a and a transparent conductive layer 10a (or 40a). In this structure, light enters from both sides. In FIG. 6, a transparent conductive layer 10a, an undercoat layer 60, a photosensitive layer 20, a charge transfer layer 30 and a counter electrode conductive layer 40 are provided on a transparent substrate 50a, and a support substrate 50 is disposed thereon. It is a structure where light enters. In FIG. 7, the conductive layer 10 is provided on the support substrate 50, the photosensitive layer 20 is provided via the undercoat layer 60, the charge transfer layer 30 and the transparent counter electrode conductive layer 40a are provided, and the transparent substrate 50a is disposed thereon. In this structure, light is incident from the counter electrode side. In FIG. 8, a transparent conductive layer 10a is provided on a transparent substrate 50a, a photosensitive layer 20 is provided via an undercoat layer 60, a charge transfer layer 30 and a transparent counter electrode conductive layer 40a are provided, and a transparent substrate 50a is provided thereon. It is arranged and has a structure in which light enters from both sides. In FIG. 9, a conductive layer 10 is provided on a support substrate 50, a photosensitive layer 20 is provided via an undercoat layer 60, a solid charge transfer layer 30 is further provided, and a partially counter electrode conductive layer 40 or a metal lead 11 is provided thereon. It has a structure in which light is incident from the counter electrode side.
[2] Photocell The photovoltaic cell of the present invention is one in which the photoelectric conversion element is caused to work with an external load. Of the photovoltaic cells, the case where the charge transport material is mainly composed of an ion transport material is particularly called a photoelectrochemical cell, and the case where the main purpose is power generation by sunlight is called a solar cell. In order to prevent deterioration of components and volatilization of the contents of the photovoltaic cell, it is preferable to seal the side surface with a polymer or an adhesive. The external circuit itself connected to the conductive support and the counter electrode via a lead may be a known one. When the photoelectric conversion element of the present invention is applied to a solar cell, the structure inside the cell is basically the same as the structure of the photoelectric conversion element described above. Moreover, the dye-sensitized solar cell of the present invention can basically have the same module structure as a conventional solar cell module. The solar cell module generally has a structure in which cells are formed on a support substrate such as metal or ceramic, and the cell is covered with a filling resin or protective glass, and light is taken in from the opposite side of the support substrate. It is also possible to use a transparent material such as tempered glass for the support substrate, configure a cell thereon, and take in light from the transparent support substrate side. Specifically, a module structure called a super straight type, a substrate type, a potting type, a substrate integrated module structure used in an amorphous silicon solar cell, and the like are known, and the dye-sensitized solar cell of the present invention is also used. These module structures can be appropriately selected depending on the place of use and the environment. Specifically, the structure and aspect described in Japanese Patent Application No. 11-8457 are preferable.

Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the examples as long as the gist of the invention is not exceeded.
In the following description, the electrodes B, C, E, F, and G and the photovoltaic cells 102, 103, 105, 106 , 107, and 202 are to be read as “reference examples”.

Hereinafter, the present invention will be specifically described by way of examples.
Example 1
1-1. Preparation of Titanium Dioxide Particle Dispersion 1 Titanium tetraisopropoxide 142.1 g and triethanolamine 149.2 g were mixed at room temperature in a dry box and allowed to stand for 2 hours. The mixed solution was taken out from the dry box, diluted with distilled water to a total volume of 1000 ml, and used as a mother liquor.
100 ml of the mother liquor and 100 ml obtained by adding 2.85 ml of acetic acid to distilled water were mixed. After heating in a sealed container at 100 ° C. for 24 hours to obtain a white gel, the temperature was raised to 140 ° C. and further heated for 72 hours. After cooling to room temperature, the supernatant was removed to obtain a pale reddish brown precipitate. The mass of the precipitate containing water was 33 g.
To the obtained precipitate, 1.0 g of polyethylene glycol having a molecular weight of 500,000 was added and kneaded for 20 minutes with a kneader to obtain a titanium dioxide dispersion having a mass concentration of 12%. The average particle diameter of the titanium dioxide particles contained in the dispersion 1 was about 16 nm, and particles of 10 nm or less were included.

1-2. Preparation of Titanium Dioxide Particle Dispersion 2 (with Precursor) 25 ml of 1 mol / l hydrochloric acid solution is added to 4.5 ml of titanium tetraisopropoxide and stirred at room temperature. When stirring was performed for 1 to 3 hours, 4 ml of this solution was added to 15.5 g of titanium dioxide particle dispersion 1 to obtain titanium dioxide particle dispersion 2. This solution was used in the next step immediately after mixing.

2. Preparation of Titanium Dioxide Electrode Adsorbed with Dye Dispersion 1 or 2 described above was applied to the conductive surface side of transparent conductive glass coated with fluorine-doped tin oxide (manufactured by Nippon Sheet Glass, surface resistance of about 10Ω / □) Coating and processing were performed under conditions to form a semiconductor porous electrode made of metal oxide fine particles. In any electrode, the coating amount of titanium dioxide was about 9.0 g / m ² and the film thickness was about 6 μm. Table 1 shows the amount of dye adsorbed on each electrode.

2-1. Preparation of Electrode A (Comparative Example) Dispersion 1 was applied with a doctor blade to a thickness of 100 μm, dried at 25 ° C. for 40 minutes, and then heated at 350 ° C. in an electric furnace (Yamato Scientific muffle furnace FP-32 type). Baked for minutes. After cooling, the dye was dyed by heating and refluxing in a solution of R-1 dye (dye 3 × 10 ⁻⁴ mol / liter, solvent: ethanol) for 3 minutes. This was designated as an electrode A.

2-2. Preparation of Electrode B (Invention) Dispersion 2 was applied with a doctor blade to a thickness of 100 μm, dried at 25 ° C. for 40 minutes, and then irradiated with ultraviolet light having a wavelength of 400 nm or less on the electrode surface using a xenon lamp in an atmosphere at 25 ° C. Was irradiated for 30 minutes. Thereafter, the dye was dyed by heating under reflux for 3 minutes in an R-1 dye solution (dye 3 × 10 ⁻⁴ mol / liter, solvent: ethanol). This was designated as an electrode B.
2-3. Preparation of Electrode C (Invention) Dispersion 1 was applied with a doctor blade to a thickness of 100 μm, dried at 25 ° C. for 40 minutes, and then heated on a hot plate at 150 ° C. using a xenon lamp with a wavelength of 400 nm or less on the electrode surface. Then, ultraviolet rays having an intensity of 30 mW / cm ² were irradiated for 30 minutes. After completing the heating and ultraviolet irradiation at the same time, the dye was dyed by heating to reflux in a solution of R-1 dye (dye 3 × 10 ⁻⁴ mol / liter, solvent: ethanol) for 3 minutes. This was designated as an electrode C.
2-4. Preparation of Electrode D (Invention) Dispersion 1 was applied with a doctor blade to a thickness of 100 μm, dried at 25 ° C. for 40 minutes, and then heated under reduced pressure at 0.04 MPa for 30 minutes on a 250 ° C. hot plate. did. Thereafter, the dye was dyed by heating under reflux for 3 minutes in an R-1 dye solution (dye 3 × 10 ⁻⁴ mol / liter, solvent: ethanol). This was designated as an electrode D.
2-5. Preparation of Electrode E (Invention) Dispersion 1 was applied with a doctor blade to a thickness of 100 μm, dried at 25 ° C. for 40 minutes, and then irradiated with infrared rays in a far-infrared furnace for 30 minutes. Thereafter, the dye was dyed by heating under reflux for 3 minutes in an R-1 dye solution (dye 3 × 10 ⁻⁴ mol / liter, solvent: ethanol). This was designated as an electrode E.
2-6. Preparation of Electrode F (Invention) Dispersion 1 was applied to a thickness of 100 μm with a doctor blade, dried at 25 ° C. for 40 minutes, and then heated on a hot plate at 150 ° C. using a xenon lamp with a wavelength of 400 nm or less on the electrode surface. Then, ultraviolet rays having an intensity of 30 mW / cm ² were irradiated for 30 minutes. However, the heating was continued for 15 minutes after the completion of UV irradiation, and then the dye was dyed by heating to reflux for 3 minutes in an R-1 dye solution (dye 3 × 10 ⁻⁴ mol / liter, solvent: ethanol). I wore it. This was designated as an electrode F.
2-7. Preparation of Electrode G (Invention) Electrode G was prepared in the same manner as in preparation of electrode F, except that dispersion 1 was replaced with dispersion 2.

3. Formation of Charge Transport Layer and Production of Photocell The electrode produced in the second section was cut into a size of 26 mm × 18 mm, leaving a central 14 mm × 14 mm square, and removing the titanium dioxide particle layer.
3-1. Formation of ion charge transport layer and assembly of photovoltaic cell A platinum-deposited glass of the same size as the prepared electrode (counter electrode, platinum layer thickness = 1 μm, glass thickness = 1.1 mm) and a polyethylene frame spacer (thickness) And a width of 4 mm, which is a terminal portion for terminals, are alternately brought out in the long side direction and overlapped. (See Figure 10)

The whole was sealed with an epoxy resin adhesive, leaving the surface of the TiO ₂ transparent electrode substrate as the light receiving portion. Next, a small hole for injection is formed on the side surface of the spacer, and a molten salt electrolyte (compound 1: compound 2: iodine = 15: 35: 1 (mass ratio)) is utilized in the space between the electrodes by utilizing a capillary phenomenon. Was soaked at 80 ° C. Then, the small hole for liquid injection was sealed. As described above, the photovoltaic cells 101 to 107 shown in Table 1 were completed.

3-2. Formation of hole transport layer and assembly of photovoltaic cell After protecting the portion other than the central portion (14 mm × 14 mm square) where the titanium dioxide particle layer adsorbing the dye of the prepared electrode remains, place it on a hot plate heated to 100 ° C. 2 Left for a minute. Thereafter, 0.2 ml of a solution of γ-CuI in acetonitrile (3.2% by mass) was slowly added to the titanium dioxide particle layer while volatilizing acetonitrile over about 10 minutes. A CuI (hole transport) layer was formed on the hot plate for 2 minutes after the addition. On top of this, the above platinum-deposited glass was superposed while being pressed, and then the whole was sealed with an epoxy resin adhesive, leaving the surface of the TiO ₂ transparent electrode substrate as the light receiving portion. Thus, the photovoltaic cells 201 to 203 shown in Table 1 were produced.

4). Measurement of photoelectric conversion efficiency Simulated sunlight was generated by passing light from a 500 W xenon lamp (USHIO) through a spectral filter (AM1.5G manufactured by Oriel). The intensity of this light was 100 mW / cm ² . The simulated sunlight was irradiated, and electricity generated between the conductive glass of the photoelectric conversion element and the counter electrode layer was measured with a current-voltage measuring device (Keutley SMU2400 type). The photoelectric conversion efficiency (η) is shown in Table 1.

5. Measurement of Adsorbed Dye Quantity For photovoltaic cells 101 to 107 provided with an ion transport layer, after measuring the photoelectric conversion performance, the device was disassembled, and the electrolyte was washed and removed with acetonitrile. Thereafter, the adsorbed dye was extracted into an alkaline solution, and the amount of adsorbed dye was quantified. The quantitative results are shown in Table 1. In the photovoltaic cell provided with the hole transport layer, it was difficult to extract the dye, and the quantitative determination was not possible.

  From Table 1, it can be seen that the comparative type 101 has extremely low dye adsorption amount and photoelectric conversion efficiency. Compared to 101, it can be seen that all of the photovoltaic cells 102 to 107 in which the electrodes were processed by the method of the present invention have a large amount of dye adsorption and high photoelectric conversion efficiency. Among the electrode treatments of the present invention, it can be seen that, in particular, the combination of ultraviolet light irradiation and heating (103, 106, 107) is excellent in both dye adsorption and photoelectric conversion efficiency. In the combined use of UV light irradiation and heating according to the present invention, when Example 103 (UV light irradiation and heating ends at the same time) is compared with Example 106 (finished by heating), UV irradiation is performed as in Example 106. It can be seen that the amount of dye adsorbed is higher and the photoelectric conversion efficiency is higher when heated after completion. This seems to be due to the fact that the surface of the titanium oxide becomes superhydrophilic by UV light, which is disadvantageous for dye adsorption, and that the surface is hydrophobized by heating. Moreover, it can be seen from the comparison between Examples 106 and 107 that the photoelectric conversion efficiency is higher when the precursor is added.

  The same tendency is observed when the charge transport layer is a hole transport material (201 to 203). That is, it can be seen that both the photovoltaic cells 202 and 203 in which the electrodes were treated by the method of the present invention have higher photoelectric conversion efficiency than the comparative photovoltaic cell (201) using the electrode fired only by heating at 350 ° C. Of these, the combination of ultraviolet light irradiation and heating (202) is particularly excellent.

Example 2
A similar experiment was conducted using a transparent conductive film provided with conductivity on a polymer support (PET). When the conditions of Comparative Example in Table 1, ie, heating at 350 ° C. was used, The shape changed and the photoelectric conversion element could not be assembled. On the other hand, under the conditions of the present invention shown in Table 1, a photoelectric conversion element could be assembled, and photoelectric conversion was possible.

DESCRIPTION OF SYMBOLS 1 ... Dye adsorption titanium dioxide electrode 2 ... Counter electrode (platinum vapor deposition glass)
3. Light receiving part where a titanium dioxide layer exists
10 ... conductive layer
10a ・ ・ ・ Transparent conductive layer
11 ... Metal lead
20 ... Photosensitive layer
21 ... Semiconductor fine particles
22 ... Dye
23 ... Charge transport material
30 ... Charge transport layer
40 ... Counterelectrode conductive layer
40a ・ ・ ・ Transparent counter electrode conductive layer
50 ... Board
50a ・ ・ ・ Transparent substrate
60 ... Undercoat layer

Claims (7)

In the manufacturing method of a photoelectric conversion device using the semiconductor fine particle film, and characterized in that the semiconductor fine particle film, the semiconductor fine particles under the following pressure 0.05 MPa, which is produced by the process comprising about Engineering you heated at 250 ° C. A method for manufacturing a photoelectric conversion element. The manufacturing method of the photoelectric conversion element of Claim 1 which has the process of forming the layer containing a semiconductor fine particle on a board | substrate before the said process to heat . The method for producing a photoelectric conversion element according to claim 1 or 2 , wherein the semiconductor fine particles forming the semiconductor fine particle film contain particles having a particle size of 10 nm or more and less than 10 nm. Method of manufacturing a photoelectric conversion device according to any one of claims 1 to 3, wherein the semiconductor particle film is characterized by being sensitized by a dye. The semiconductor fine particles are titanium oxide, zinc oxide, tin oxide, tungsten oxide, niobium oxide, iron oxide, titanium alkaline earth metal, according to claim 1-4, characterized in that the alkali metal titanate or complex thereof The manufacturing method of the photoelectric conversion element of any one of these. Method of manufacturing a photoelectric conversion device according to any one of claims 1 to 5, characterized in that providing the semiconductor fine particle layer on a polymer support. In the manufacturing method of the photovoltaic cell containing a photoelectric conversion element, this photoelectric conversion element was produced with the manufacturing method of the photoelectric conversion element of any one of Claims 1-6 , The manufacturing method of the photovoltaic cell characterized by the above-mentioned.

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