JP2001160425A - Optical semiconductor electrode and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical semiconductor electrode using a high polymer film which has a higher photoelectric conversion efficiency than that of an optical semiconductor electrode using a glass substrate, and its manufacturing method. SOLUTION: Optical semiconductor particles are carried by a transparent porous polymer film having conductivity. The optical semiconductor particles are filled in holes of the porous polymer film and may be carried by of the porous polymer film in such manner that an optical semiconductor layer is formed on one side of the porous polymer film. Moreover, the optical semiconductor electrode may be laminated on a high conductivity layer which is formed on one side face of a transparent support body include a transparent support body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor electrode used for wet photovoltaic cells, photolysis of water, photoorganic chemical reaction, and the like, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years,
Dye-sensitized wet solar cells have attracted attention and have been studied for practical use. Here, in the wet solar cell, as shown in FIG. 8, the optical semiconductor electrode 30 is provided on the side to which light is irradiated, the counter electrode 35 is provided on the opposite side (light emission side), and the optical semiconductor electrode 30 is provided. It has a basic structure in which an electrolyte solution 36 is sealed between the battery and the counter electrode 35.
The optical semiconductor electrode 30 includes a glass substrate 31 and a transparent conductive layer 32 formed on the light-emitting side of the glass substrate 31 by sputtering a conductive inorganic compound.
And a titanium oxide porous film 33 formed on the conductive layer 32. A dye as a sensitizer for efficiently converting sunlight into electricity is fixed to the titanium oxide or a photosensitizing dye. Is formed on the porous film 33 of titanium oxide.

A titanium oxide porous film 33 is formed by hydrolyzing a titanium alkoxide, heat-treating the titanium alkoxide, and further adding a polyethylene glycol to a titanium oxide colloid solution on a glass substrate 31 by a doctor blade method or the like. It is generally formed by applying it to the surface of the formed conductive layer 32, drying and baking it at about 450 ° C. During firing, the polyethylene glycol disappears,
It becomes a porous film of titanium oxide. Making the titanium oxide film porous is effective in that the specific surface area can be increased and a large amount of the photosensitizing dye can be attached.

By the way, from the viewpoints of cost, handling, and the like, there is a demand for a semiconductor electrode using a flexible polymer film as an electrode substrate. However, Sommeling et al.
Photovoltaic Solar Energy Conversion, Vienna 1
As described in 998, since the heat resistance of a transparent polymer film such as a PET film is inferior to that of glass, the heat treatment temperature after applying a titanium oxide paste is limited. Specifically, since the temperature is limited to 150 ° C. or lower, the titanium oxide film becomes insufficiently porous.

On the other hand, as a method of forming a titanium oxide film without firing, a coating solution in which titanium oxide particles are dispersed in a binder solution is applied to the surface of a conductive layer formed on one side of a transparent polymer film. A method of repeating the steps of drying and drying is being studied. However, since the formed titanium oxide film has poor adhesion to the conductive layer and the base film, it is difficult to form a titanium oxide layer having such a thickness that the photoelectric conversion efficiency necessary for practical use can be secured. In a severe case, the formed optical semiconductor layer is separated from the substrate.

[0006] Similarly, in an optical semiconductor electrode used other than a wet solar cell, for example, an optical semiconductor electrode used for photolysis of water, an optical semiconductor having high photoelectric conversion efficiency based on a flexible polymer film is used. Electrodes are useful and need to be developed.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a polymer film as a base material and at least as high as an optical semiconductor electrode using a glass substrate. An object of the present invention is to provide a semiconductor electrode having photoelectric conversion efficiency and a method for manufacturing the same.

[0008]

In order to form an optical semiconductor electrode based on a polymer film, a large amount of light per unit area is required to obtain a transparent substrate and high photoelectric conversion efficiency. It is required that semiconductor particles can be retained.

The present inventors have developed a transparent porous conductive film having a large specific surface area, and completed the present invention by further filling this conductive film with optical semiconductor particles.

That is, the photosemiconductor electrode of the present invention is characterized in that the photosemiconductor particles are supported on a conductive porous polymer film and are transparent. The optical semiconductor particles are filled in the pores of the porous polymer film, and are supported by the porous polymer film so as to form an optical semiconductor layer on one surface of the porous polymer film. You may.

The optical semiconductor electrode of the present invention further includes a transparent support, and a highly conductive layer is formed on one side of the transparent support, and the optical semiconductor electrode of the present invention is provided on the high conductive layer. May be laminated.

Preferably, the optical semiconductor particles are supported on the porous polymer film using a binder. Preferably, a photosensitizing dye is attached to the optical semiconductor particles.

The conductive porous polymer film preferably has a conductive inorganic compound supported on a continuous porous polymer film. The thickness of the communicating porous polymer film is preferably 30 μm or less. Further, it is preferable that the conductive inorganic compound is supported on the communication type porous polymer film using a binder. Furthermore, it is preferable that the communication type porous polymer film is stretched porous polytetrafluoroethylene.

The optical semiconductor electrode according to the present invention has a thickness of 550 n.
The light transmittance of m is preferably 5% or more.

The method for producing an optical semiconductor electrode according to the present invention comprises a step of applying a coating liquid comprising a conductive inorganic compound and optical semiconductor particles dispersed on at least one surface of a continuous porous polymer film and drying the coating liquid. It is characterized by the following.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a conductive porous polymer film serving as a base material of an optical semiconductor electrode of the present invention will be described.

[Conductive Porous Polymer Film] The conductive porous polymer film (hereinafter abbreviated as “conductive film”) used in the present invention is a transparent conductive polymer film as a substrate of an optical semiconductor electrode. It is necessary to have pores that can impregnate the optical semiconductor particles. FIGS. 1 and 2 show the basic configuration of a conductive film satisfying such requirements.

The conductive film 10 shown in FIG. 1 has a particulate conductive inorganic compound 4 attached to the surface of the skeleton 2 constituting the communicating porous polymer film 1 or the empty space of the communicating porous polymer film 1. The hole 3 is filled with a conductive inorganic compound 4.

The conductive film 11 shown in FIG. 2 has a long diameter (corresponding to the length if it is fibrous or needle-like) larger than the average diameter of the pores 3 as a conductive inorganic compound. This is a conductive film using a conductive inorganic compound 4 ′. The conductive inorganic compound is formed such that a conductive layer 5 made of the conductive inorganic compound 4 ′ is formed on one surface of the communicating porous polymer film 1. 4 'is carried.

The communicating porous polymer film 1 may be any porous polymer film having pores communicating with the outside, and specifically, expanded porous polytetrafluoroethylene (ePTFE), Polymer films such as cellulose acetate, porous polystyrene, and porous polyethylene are exemplified. Of these, expanded porous polytetrafluoroethylene (ePT) is excellent in chemical stability (particularly heat resistance and chemical resistance) and electrochemical stability.
FE) is preferably used. This is because the optical semiconductor electrode is strongly required to have chemical resistance and electrochemical stability from its use.

Here, expanded porous polytetrafluoroethylene (ePTFE) refers to a molding aid obtained by mixing a fine powder of polytetrafluoroethylene (PTFE) with a molding aid. It is obtained by stretching after or without removing, and further baking if necessary. In the case of uniaxial stretching, the fibril is oriented in the stretching direction and the fibrous material has voids 3 between fibrils. It has a structure. In the case of biaxial stretching, fibrils spread radially, and have a spider web-like fibrous structure in which a large number of holes 3 defined by nodes and fibrils exist.

The thickness of the porous polymer film 1 is 30 μm
The following is preferred. The porous polymer film is
This is because the light transmittance decreases as the thickness increases, and if the thickness exceeds 30 μm, it is difficult to obtain a transparent conductive film, and furthermore, a transparent optical semiconductor electrode. Therefore, in order to increase transparency, it is more preferable to use a porous polymer film having a thickness of 10 μm or less. Here, the transparency required in the present invention is a dry conductive film,
The light transmittance at 550 nm is 40% or more. Transparency is increased by the wet state, and transmittance can be further increased by containing a binder as described later. Therefore, if the transparent layer has such a transmittance in a dry state, a transparent conductive film, and furthermore, a transparent optical semiconductor electrode can be obtained. Note that the lower limit of the thickness of the porous polymer film is 0.02 μm because a film having a thickness of less than 0.02 μm is difficult to manufacture.
It is about.

The porosity of the communication type porous polymer film 1 is as follows:
The size of the vacancy may be appropriately selected according to the size of the conductive inorganic compound 4 and the like. In the case of ePTFE, the porosity is 2
The pore size is preferably about 0 to 98%, and the maximum pore size is preferably 0.2 to 6.5 μm. here,
The porosity (%) is obtained from the following equation. In the formula, the true specific gravity is the true specific gravity of the material constituting the continuous porous polymer film. For example, in the case of ePTFE, the specific gravity is 2.2, which is the specific gravity of polytetrafluoroethylene. Porosity = (true specific gravity−apparent specific gravity) ÷ true specific gravity × 100 The maximum pore diameter of the pore is a value obtained by a bubble point shown in the following equation. Wherein B.I. P. Is the pressure at which continuous air bubbles are generated when 2-propanol is poured into the upper surface of the membrane and air is injected from the lower surface. Maximum pore size = 0.65 ° B. P.

The conductive inorganic compound 4 may be any inorganic compound capable of forming a transparent conductive layer, such as indium tin oxide (ITO) corresponding to tin-doped indium oxide,
Fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), zinc oxide, or the like can be used. The shape and the like of these conductive inorganic compounds are not particularly limited. In general, when a particulate conductive inorganic compound is used, the conductive inorganic compound 4 adheres to the surface of the skeleton 2 of the porous polymer film 1 or fills the pores 3. The functional film 10 is obtained. On the other hand, when the fibrous or acicular conductive inorganic compound 4 ′ having a longer diameter (corresponding to the length in the case of fibrous or acicular) larger than the average pore diameter of the pores 3, the porous polymer film 1 is used. It is difficult to penetrate deep into the inside of the
A conductive film as shown in FIG. 2 in which a conductive layer 5 made of a conductive inorganic compound 4 'is formed on one side of the conductive film.

[Supporting of Optical Semiconductor Particles] The optical semiconductor electrode of the present invention is obtained by supporting the optical semiconductor particles on the conductive film having the above-described structure.

Here, the optical semiconductor particles include titanium oxide, tin oxide, zirconium oxide, yttrium oxide,
Examples include niobium oxide, strontium titanate, calcium titanate, sodium titanate, and potassium niobate. Among these, oxidization having a high photocatalytic function is used as an optical semiconductor electrode of a wet solar cell or an electrode for the photolysis reaction of water. Titanium, particularly anatase type titanium oxide, is preferably used.

Such optical semiconductor particles may be attached to the skeleton 2 of the porous polymer film 1 as a carrier together with the conductive inorganic compound, or may be filled in the pores 3. Furthermore, an optical semiconductor layer in which optical semiconductor particles exist densely on one surface of the porous polymer film may be formed.

The optical semiconductor electrode of the present invention specifically has a configuration as shown in FIGS. The optical semiconductor electrode 20 shown in FIG. 3 is obtained by supporting the optical semiconductor particles 6 on the conductive film 10 shown in FIG. 1. The optical semiconductor particles 6 are formed together with the conductive inorganic compound 4 on the skeleton of the porous polymer film 1. 2 or held in the holes 3. Further, the optical semiconductor particles 6 are provided on one side of the porous polymer film 1.
The optical semiconductor layer 7 is formed.

The optical semiconductor electrode 21 shown in FIG. 4 is obtained by supporting the optical semiconductor particles 6 on the conductive film 11 shown in FIG. Such a photo-semiconductor electrode 21 is made of a porous material such that the photo-semiconductor particles 6 are supported from the side facing the conductive layer 5 so as to be denser on the side where the conductive inorganic compound 4 ′ is smaller. It is attached to the skeleton 2 of the molecular film 1 or held in the holes 3. Further, an optical semiconductor layer 7 made of optical semiconductor particles 6 is formed on a surface opposite to the conductive layer 5.

The photo-semiconductor electrode 22 shown in FIG. 5 is a case where the manufacturing method of the present invention described later is employed, and the porous polymer film 1 in which the particulate conductive inorganic compound 4 and the photo-semiconductor particles are simultaneously a carrier. Is filled. Therefore, the point that the optical semiconductor particles 6 and the conductive inorganic compound 4 are attached to the skeleton 2 of the porous polymer film 1 or held in the pores 3 is different from that of the optical semiconductor electrode 20 shown in FIG. Although common, the optical semiconductor layer 7 ′ formed on one side of the porous polymer film 1 is a mixture layer of the optical semiconductor particles 6 and the conductive inorganic compound 4.

In any of the above structures, since the semiconductor material 6 is held in the pores 3 of the porous polymer film 1, the semiconductor material 6 is smaller than a titanium oxide film formed on a smooth film surface by a simple coating method. And is kept stable. In addition, since it is possible to carry an amount of optical semiconductor particles according to the thickness and pores of the porous polymer film, it is possible to carry a large amount of optical semiconductor particles that cannot be achieved by a method of coating a smooth film. it can. That is, a sufficient amount of optical semiconductor particles required for practical use can be supported. Further, in the photosemiconductor electrode (photosemiconductor electrode in the case of using a particulate conductive inorganic compound) shown in FIGS. The inorganic compound 6 is mixed at a ratio corresponding to the content ratio. In such a case, the electrons generated by the photoexcitation of the optical semiconductor particles 4 can move through the conductive inorganic compound 6 present in the vicinity, so that the electrons pass through the layer composed of only the optical semiconductor particles, which are almost insulators. The resistance may be lower than when moving to the conductive layer. That is, an optical semiconductor electrode having high conductivity can be obtained.
Furthermore, the optical semiconductor electrode 22 shown in FIG. 5 has the advantage that the resistance can be further reduced because the conductive inorganic compound 4 is also mixed in the optical semiconductor layer 7 ′ based on the manufacturing method.

The optical semiconductor electrodes shown in FIGS. 3 to 5 have optical semiconductor layers 7, 7 on one surface of the porous polymer film 1.
Although 7 ′ is formed, the optical semiconductor electrode of the present invention may not have the optical semiconductor layers 7, 7 ′.

The content ratio of the conductive inorganic compound and the optical semiconductor particles in the optical semiconductor electrode varies depending on the production method, the conductivity required as a product, and the types of the conductive inorganic compound and the optical semiconductor particles. In order to support a large amount of optical semiconductors, it is preferable to include the conductive inorganic compound: optical semiconductor particles in a ratio of 10: 1 to 1:10.

The conductive inorganic compounds 4, 4 'and the optical semiconductor particles 6 adhere to the surface of the skeleton 2 depending on their size and shape, the size and material of the pores 3 of the porous polymer film 1, and the like. When the conductive inorganic compound 4 is held in the pores 3 or in the form of fibers or needles, the conductive inorganic compounds 4 ′ are entangled with each other or the skeleton of the porous polymer film 1. By being engaged with 2, the porous polymer film 1 is supported on the communication-type porous polymer film 1. Therefore, it is possible to support these particles without a binder. However, for the following reasons, it is preferable to be supported on the porous polymer film 1 via a binder. That is, by containing the binder, not only the holding power of the conductive inorganic compound and the semiconductor substance can be increased, but also the transparency can be improved. Furthermore, as described later, when a porous conductive film containing an optical semiconductor is laminated on a support, the binder can also contribute to improving the adhesion between the support and the conductive film 10.

As the binder that can be used, butyral resin, silicone resin, fluorine resin and the like can be mentioned. Further, the amount of the binder is preferably set to an amount necessary for increasing the light transmittance and an amount necessary for supporting the conductive inorganic compound. This is because the conductivity tends to decrease as the amount of the binder increases.

The optical semiconductor electrode having the above-described structure may be used alone as it is as an optical semiconductor electrode. However, from the viewpoint of handleability, it is preferable to use the optical semiconductor electrode laminated on a support.

[Optical semiconductor electrode with support] FIGS. 6 and 7
Indicates an optical semiconductor electrode obtained by laminating the optical semiconductor electrodes of FIG. 3 (or FIG. 5) and FIG. 4 on a support, respectively (hereinafter, an optical semiconductor electrode not laminated on the support and an optical semiconductor electrode laminated on the support). When distinguishing the optical semiconductor electrodes that are present, the optical semiconductor electrodes laminated on the support are referred to as “optical semiconductor electrodes with a support”.
An optical semiconductor electrode that is not laminated on a support is referred to as an “optical semiconductor electrode body”).

An optical semiconductor electrode 23 with a support shown in FIG.
Is a transparent film substrate 12a and this film substrate 12
a supporting member 12 comprising a highly conductive layer 12b formed by attaching a conductive inorganic compound by sputtering, ion plating or the like to the optical semiconductor electrode body 20 (22). 12b. The optical semiconductor electrode body 20 (22) is provided on the side where the optical semiconductor layer 7 (7 ') is not formed, with the high conductive layer 12 (22).
The layers are laminated so as to come into contact with b.

An optical semiconductor electrode 24 with a support shown in FIG.
Is on one side of a support 13 which is a transparent polymer film,
The optical semiconductor electrode body 21 is laminated so that the conductive layer 5 is on the support 13 side, in other words, the optical semiconductor layer 7 is on the surface of the optical semiconductor electrode 24 with the support. .

The support 13 and the film substrate 12a of the support 12 may be any as long as they do not impair the transparency, light weight and flexibility of the transparent conductive film of the present invention. Specifically, any transparent polymer film may be used. For example, a polyester film, a polyethylene film, a polycarbonate film, a transparent fluororesin film and the like can be mentioned. The thickness of the polymer film used for the support can be appropriately selected depending on the required strength, handleability, and flexibility as long as the light transmittance according to the intended use is within a range.

The conductive inorganic compound constituting the high conductive layer 12b of the support 12 is a conductive inorganic compound that can be used for the conductive films 10 and 11, that is, indium tin oxide (ITO), fluorine-doped Tin oxide (F
TO), antimony-doped tin oxide (ATO), zinc oxide and the like. The high conductive layer 12b is formed by sputtering, ion plating, vacuum deposition, or the like, and has a thickness of 0.01 to 0.5 μm. This high conductive layer 12b
It plays the role of a current collector in the optical semiconductor electrode with a support, and from this role, this thickness is sufficient,
This is because it is difficult to form a conductive layer having a thickness of 1 μm or more by a sputtering method or the like.

The optical semiconductor electrode (optical semiconductor electrode main body and optical semiconductor electrode with support) of the present invention having the above-mentioned structure is transparent and can transmit light. Specifically, the light transmittance at 550 nm in a dry state is about 5 to 70%, preferably about 10 to 70%, and more preferably about 20 to 70%. Transparency is higher in the state of being immersed in the electrolytic solution than in the dry state. As described above, since the optical semiconductor electrode of the present invention can transmit light, not only the optical semiconductor layers 7 and 7 ′ on the surface of the optical semiconductor electrode but also the optical semiconductor particles contained in the conductive films 10 and 11. Therefore, almost all of the optical semiconductor particles can be effectively excited by using light to generate electrons. In the photosemiconductor electrode of the present invention, particularly the photosemiconductor electrode using the particulate conductive inorganic compound (applicable to the photosemiconductor electrodes 20, 22, and 23), the photosemiconductor particles 6 and the conductive inorganic compound 4 are mixed. , Electrons generated from the photosemiconductor material can move through the nearby conductive inorganic compound. This means
This means that a higher conductivity can be expected than an optical semiconductor electrode of a type in which a conductive layer made of a conductive inorganic compound and an optical semiconductor layer made of optical semiconductor particles are in contact with each other.

The photo-semiconductor electrode of the present invention contains photo-semiconductor particles that can effectively utilize incident light having a large specific surface area, because the polymer film serving as a carrier for the photo-semiconductor particles is porous. A porous membrane is obtained. In addition, since the polymer film is used for the carrier and the support, an optical semiconductor electrode that is lightweight and has excellent flexibility and flexibility can be obtained.

[Method of Manufacturing Optical Semiconductor Electrode] Next, a method of manufacturing a semiconductor electrode having the above-described configuration will be described.

In the semiconductor electrode of the present invention, a conductive inorganic compound is first supported on a continuous porous polymer film to form conductive films 10 and 11 as shown in FIG. 1 or FIG. The conductive films 10 and 11 may be coated with a coating liquid containing optical semiconductor particles and dried (sequential method), or may be manufactured by a one-pot method described below.

First, the one-pot method will be described. This production method is a method in which a conductive inorganic compound and optical semiconductor particles are simultaneously supported on a communication type porous polymer film. Apply to film,
It is a method of drying. According to the one-pot method, it is possible to obtain an optical semiconductor electrode in which a conductive inorganic compound and optical semiconductor particles are almost uniformly mixed and dispersed in a communication type porous polymer film. When the optical semiconductor layer is formed on one side of the porous polymer film, the conductive inorganic compound 4 and the optical semiconductor particles 6
Is obtained, and an optical semiconductor electrode on which an optical semiconductor layer 7 'is formed is obtained (see the optical semiconductor electrode shown in FIG. 5). The one-pot method requires only one coating operation, and therefore requires only one drying operation, which has the advantage of shortening the manufacturing process.

The coating liquid to be used is prepared by dispersing a conductive inorganic compound and optical semiconductor particles in a solvent. Further, it is preferable that a binder is contained.

Examples of the solvent include alcohols such as ethanol, propanol and butanol; ketones such as 2-butanone; and aromatic hydrocarbons such as toluene. What is necessary is just to select suitably according to the kind of porous polymer film, workability, etc. Examples of the binder include a butyral resin, a silicone resin, and a fluorine resin, and a binder having good wettability may be appropriately selected according to the type of the porous film. Specifically, the coating liquid may be prepared by adding optical semiconductor particles to a commercially available conductive inorganic compound dispersed ink, or by adding a conductive inorganic compound to a commercially available optical semiconductor particle dispersion. May be prepared.

Examples of the coating method include a roller coating method, a spray method, and a dipping method.

After the application, the solvent is volatilized by drying. The drying temperature may be any temperature at which the solvent can be volatilized, and may be appropriately selected according to the heat resistance and productivity (drying time) of the porous polymer film and the type of the solvent. Therefore, when using a polymer film excellent in heat resistance,
In order to dry quickly, heat to a high temperature of 100 ℃ or more,
It is preferable to dry at a temperature lower than 300 ° C., and when a highly volatile solvent such as a lower alcohol is used, it can be dried at room temperature. On the other hand, when there is no problem with the heat resistance of the porous polymer film, for example, when a porous polymer film having excellent heat resistance such as ePTFE is used as the porous polymer film, a drying treatment was performed. It is preferable to perform calcination at 150 ° C. or higher after or without drying treatment. The upper limit of the firing temperature is 300 ° C.
Considering the effect on the porous polymer film, further high-temperature heating is not preferable.

Next, the sequential method will be described. In the sequential method, it is necessary to separately prepare and use a conductive coating solution used for producing a conductive film and a photosemiconductor coating solution for further filling the photosemiconductor particles. The conductive coating liquid is prepared by dispersing a conductive inorganic compound in a solvent, and the optical semiconductor coating liquid is prepared by dispersing optical semiconductor particles in a solvent. When a binder is used, the binder may be added to each coating liquid, or the binder may be added to only one of the coating liquids. The binders and solvents that can be used are the same as those exemplified in the one-pot method.

In the sequential method, first, a conductive coating solution is applied to a continuous porous polymer film and dried to prepare a conductive film. Next, an optical semiconductor coating solution is applied to the conductive film and dried to obtain an optical semiconductor electrode. The optical semiconductor coating liquid may be applied from any surface of the conductive film. However,
When the conductive layer 5 is formed on one side of the conductive film 11 like the conductive film 11 shown in FIG. 2, it is preferable to apply the optical semiconductor coating liquid from the side where the conductive layer 5 is not formed. In addition, the application method and the drying method
Same as the one-pot method. In the case of such a sequential method,
The optical semiconductor layer 7 with dense optical semiconductor particles is formed (see the optical semiconductor electrode 22 shown in FIG. 3).

When the optical semiconductor electrode with a support is manufactured, the optical semiconductor electrode body is formed on the support 12 or 13 after the optical semiconductor electrode body is formed based on the above manufacturing method. Although it is good, it is preferable to manufacture by the following method.

When preparing the optical semiconductor electrode 23 with a support shown in FIG. 6, first, the porous polymer film 1 is placed on the high conductive layer 12b of the support 12, and a coating solution is applied in this state. Is preferred. Such a method is not only excellent in the workability of coating, but also when the binder is contained in the coating solution, the binder can improve the adhesive strength between the porous polymer film 1 and the highly conductive layer 12b. This is because it contributes to improvement.

On the other hand, when manufacturing the optical semiconductor electrode 24 with a support shown in FIG. 7, it is necessary to first prepare an optical semiconductor electrode body and then to laminate it on the support 13. in this case,
In order to ensure the adhesive strength between the support 13 and the optical semiconductor electrode body, there is also a method of bonding them with a binder. However, after applying a coating liquid, the support 13 is laminated on the support 13 in a semi-dry state, and dried in such a state. It is preferable to terminate or bake.

According to the above-described manufacturing method, the coating solution is simply applied and dried regardless of the one-pot method or the sequential method, and firing at a high temperature is not required. As a method for manufacturing an optical semiconductor electrode using a polymer film having a poor heat resistance as a base material.

[Photosensitizing Photo-Semiconductor Electrode] The photo-semiconductor electrode of the present invention may be further impregnated with a photosensitizing dye. In particular, when the photo-semiconductor particles are a substance excited by ultraviolet rays such as titanium oxide, and the application is to effectively utilize sunlight such as a photo-semiconductor electrode of a wet solar cell, a photosensitizing dye is attached. It is preferable to keep it.

As the photosensitizing dye, a dye capable of absorbing long-wavelength visible light is preferable so that sunlight can be effectively used, and specifically, a dye having a skeleton of a ruthenium complex is preferably used. For example, cis-bis (isothiocyanato) bis (2,2'-bipyridyl-4,4'-dicarboxylato) ruthenium (II), cis-bis (isothiocyanato) bis (2,2'-bipyridyl-4,4 ' -Dicarboxylato) ruthenium (II) bis (tetrabutylammonium), tris (isothiocyanato) ruthenium (II) -2,2 ': 6', 2 "-terpyridine-
4,4 ', 4 "-tricarboxylic acid, bis (3,4-dicarboxypyridine) (1,4,8,11,15,18,
22,25-octamethylphthalocyaninato) ruthenium (II) and cis-bis (isothiocyanato) bis (1,10-phenanthrolyl-4,7-dicarboxylato) ruthenium (II).

As a method for attaching the photosensitizing dye, a dye solution in which the above dye is dissolved in a solvent is prepared, and the optical semiconductor electrode may be immersed in the dye solution. When immersed and dried, the dye mainly adheres to the optical semiconductor particles. In some cases, heating makes it easier to adhere. Some photosensitizing dyes have the property that, due to their chemical structure, they can easily form bonds with the photo-semiconductor particles. Can be attached.

The photo-semiconductor electrode having the photo-sensitizing dye adhered to the photo-semiconductor particles, as is well known as a Gretzell-type solar cell, is capable of emitting visible light having a wavelength longer than the band gap of the photo-semiconductor particles. The electrons in the dye that are absorbed and photoexcited are conducted from the surface of the photo-semiconductor particles through the nearby conductive inorganic compound. On the other hand, the dye oxidized by the transfer of electrons is reduced by a reducing agent (iodide ion) in a redox electrolyte solution, for example, an iodine solution. As described above, the photosensitizing dye can effectively convert sunlight into electric energy. In other words, even in the case of an optical semiconductor electrode using an optical semiconductor material that generates electrons by being photoexcited by ultraviolet light, such as titanium oxide, visible light can be used by attaching a photosensitizing dye, so that It is effective as an electrode.

[0061]

EXAMPLES First, measurement methods used in the following examples will be described.

[Measurement Method] Light Transmittance (%) The light transmittance of the composite film was measured using an ultraviolet-visible spectrophotometer UV-240 manufactured by Shimadzu Corporation and evaluated by the light transmittance (%) at 550 nm. did. 550 nm corresponds to a yellow-green wavelength of visible light, and the higher the light transmittance at this time, the higher the transparency.

Surface resistivity (Ω / □) The surface resistivity (Ω / □) was measured by a four probe method using a low resistivity meter Loresta GP manufactured by Mitsubishi Chemical Corporation.

Film thickness (μm) Digimatic micrometer No. manufactured by Mitutoyo Corporation
293-421-20.

Amount of Dye Attached UV-visible spectrophotometer UV-240 manufactured by Shimadzu Corporation
Using the dye λ_{ma x}The absorbance at was measured. Absorbance
The higher the value, the greater the amount of dye attached,
It indicates that the content of titanium oxide is large.

[Production of Optosemiconductor Electrode by Sequential Method] Examples 1-3: As a support, a transparent conductive film OTEC-110B-125N (1.
1 × 10 ¹ Ω / □, transmittance at 550 nm: 73%). This is a transparent conductive film in which a high conductive layer made of indium tin oxide (ITO) is formed on one surface of a polyester film having a thickness of 124 μm by ion plating.

ITO-M6 manufactured by Sumitomo Metal Mining Co., Ltd. (Indium tin oxide (ITO)
Wako Pure Chemical Industries, Ltd. polyvinyl butyral 2000 (average degree of polymerization 1900)
To 2100) to a concentration of 5 g / dm ³ to prepare a conductive coating solution.

As the porous polymer film, a film thickness of about 2 μm
m, an expanded porous polytetrafluoroethylene (ePTFE) film having a porosity of 60% and a maximum pore diameter of 0.30 μm, and placing the porous polymer film on the highly conductive layer of the support, The above-mentioned conductive coating solution was applied to the surface of the ePTFE film with a glass rod.
After the application, the coating was dried at 150 ° C. for 20 minutes using a vacuum drier to prepare a conductive porous polymer film with a support. The thickness, weight and surface resistivity of this porous polymer film are as shown in Table 1.

On the surface of the conductive film which is not in contact with the support, a titanium oxide coating solution ST-K01 (solid content: 10% by mass, TiO ₂ /
(Silicate binder = 80/20) was applied. After the application, the semiconductor electrode supporting titanium oxide was obtained by drying at 150 ° C. for 20 minutes using a vacuum drier. Measure the surface resistivity, film thickness, and weight of the obtained optical semiconductor electrode,
Table 1 shows the results.

Examples 4 and 5: Conductive films produced in the same manner as in Example 1 were used. An optical semiconductor electrode was manufactured in the same manner as in Example 1 except that the titanium oxide coating solution was changed to ST-K03 (solid content: 10 wt%, TiO ₂ / binder = 50/50).

The surface resistivity and light transmittance of the produced conductive film and optical semiconductor electrode were measured, and the measurement results are shown in Table 1.

Comparative Example 1: The transparent conductive film OTEC- manufactured by Oji Tobi Co., Ltd. used as a support in the above example.
One side of 110B-125N was directly coated with the same titanium oxide coating solution as in Example 1 and dried. Table 1 shows the results of measuring the thickness and weight of the obtained optical semiconductor electrode.

The obtained photosemiconductor electrode had colorless and transparent crystals deposited on the surface, the adhesion of the photosemiconductor layer (titanium oxide film) to the transparent conductive film was extremely poor, and most of the titanium oxide was peeled off. I fell.

Comparative Example 2: Titanium oxide coating solution was
The titanium oxide coating solution used in Example 4 (ST-K
An optical semiconductor electrode was produced in the same manner as in Comparative Example 1 except that the optical semiconductor electrode was replaced with 03). Table 1 shows the results of measuring the thickness and weight of the manufactured optical semiconductor electrode.

The optical semiconductor layer formed by drying had poor adhesion, and most of the titanium oxide was peeled off.

Example 6: Included in conductive coating liquid
Polyvinyl butyral content of 1 g / dm ^Threechange to
The optical semiconductor electrode was formed in the same manner as in Example 1 except that
Made.

The thickness increase of the optical semiconductor electrode was 7 μm, and the weight increase was 15.6 mg. The surface resistivity was 2.34 × 10 ⁷ Ω / □ and the light transmittance at 550 nm was 48.6%.

[0078]

[Table 1]

As can be seen from Table 1, in each case,
The photosemiconductor electrode coated with the titanium oxide coating solution had a higher surface resistivity, and a larger film thickness and weight. This indicates that the titanium oxide was attached by the application of the titanium oxide coating liquid. However, in each of the examples, the amount increased by 10 mg or more, whereas in the comparative example, the amount of adhesion was 5 to 8 mg, which was small.
This indicates that the optical semiconductor electrode of the present invention was able to carry a large amount of titanium oxide at high density because the porous polymer film was used as the conductive film.

[Production of Photo-Semiconductor Electrode by One-Pot Method] Examples 7-14: Titanium oxide powder ST-21 from Ishihara Techno Co., Ltd. was added to ITO ink using polyvinyl butyral as a binder, and ITO particles and titanium oxide were added. Was prepared at a ratio shown in Table 2 to prepare a one-pot coating solution.

As a support, a transparent conductive film OTEC
-110B-125N and a thickness of 2
A μm ePTFE film was placed thereon, and the one-pot coating liquid was applied to the surface of the ePTFE film. After the application, the coating was dried at 150 ° C. for 20 minutes using a vacuum drier to prepare an optical semiconductor electrode. The surface resistivity and transmittance of the obtained optical semiconductor electrode were measured, and the results are shown in Table 2.

[0082]

[Table 2]

As can be seen from Table 2, the greater the content of titanium oxide in the coating solution, in other words, the greater the amount of titanium oxide in the optical semiconductor electrode, the higher the surface resistivity. However, the surface resistivity was extremely low as compared with the photosemiconductor electrode manufactured by the sequential method (see Table 1), which was almost the same as that of the conductive film alone. This is presumably because the optical semiconductor layer formed on one side of the film is formed by a mixture of titanium oxide and a conductive inorganic compound. In addition, the transmittance was 20% or more, though depending on the content of titanium oxide, and the transmittance could be secured to such an extent that it could be used as an optical semiconductor electrode of a solar cell.

[Dye-Sensitized Photo-Semiconductor Electrode] Example 15: The photo-semiconductor electrode produced in Example 1 was replaced with
After vacuum drying at 80 ° C. for 30 minutes, a 2-propanol solution of a dye Coumarin 343 manufactured by Aldrich (1.0 mm
ol / dm ³ ) at room temperature for 3 hours, rinsed with 2-propanol, and vacuum dried at 50 ° C. for 30 minutes to produce a dye-sensitized optical semiconductor electrode.

The absorption spectrum of the obtained dye-sensitized photo-semiconductor electrode was measured, and λ _max 448 nm of coumarin 343 was measured.
Was measured. Table 3 shows the results.

Comparative Example 3 Example 1 was repeated except that the optical semiconductor electrode of Comparative Example 1 was used instead of the optical semiconductor electrode of Example 1.
A dye-sensitized optical semiconductor electrode was prepared in the same manner as in No. 5, and the absorption spectrum was measured to determine the absorbance. Table 3 shows the results.

[0087]

[Table 3]

As can be seen from Table 3, the photosemiconductor electrode using the porous polymer film (Example 15) was obtained by directly coating a nonporous polymer film with a titanium oxide coating solution (comparative example). Compared with Example 3), the amount of titanium oxide attached was large, and as a result, the amount of dye attached was large, and the absorbance was also high.

[0089]

The photo-semiconductor electrode of the present invention has a conductive layer and a photo-semiconductor layer having a large thickness and a specific surface area which spread three-dimensionally and cannot be obtained by the conventional method. Since it is held in the pores of the porous polymer film, it is possible to carry a stable, high-density, and large amount of optical semiconductor particles. Furthermore, in the production of the photosemiconductor electrode of the present invention, a high-temperature heat treatment is not indispensable, so that a lightweight and flexible transparent photosemiconductor electrode can be produced using a polymer film having insufficient heat resistance as a substrate.

Further, in the case of the dye-sensitized photo-semiconductor electrode of the present invention in which a dye is adhered to the photo-semiconductor electrode, a photo-semiconductor electrode with high photoelectric conversion efficiency utilizing sunlight effectively can be obtained. It is suitable for an optical semiconductor electrode for a solar cell.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a configuration of a conductive film according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a configuration of a conductive film according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram showing a configuration of an optical semiconductor electrode using the conductive film of FIG.

FIG. 4 is a schematic diagram showing a configuration of an optical semiconductor electrode using the conductive film of FIG.

FIG. 5 is a schematic diagram showing a configuration of an optical semiconductor electrode manufactured using the conductive film of FIG. 1 and by the manufacturing method of the present invention.

6 is a schematic diagram showing a configuration of an optical semiconductor electrode with a support using the optical semiconductor electrode of FIG. 3;

FIG. 7 is a schematic diagram showing a configuration of an optical semiconductor electrode with a support using the optical semiconductor electrode of FIG. 4;

FIG. 8 is a schematic diagram showing a basic configuration of a conventional wet-type solar cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Communication-type porous polymer film 2 Skeleton 3 Void 4,4 'Conductive inorganic compound 5 Conductive layer 6 Optical semiconductor particle 7,7' Optical semiconductor layer 10,11 Conductive film 12,13 Support 12a Substrate 12b High conductive layer 20, 21, 22 Optical semiconductor electrode (main body) 23, 24 Optical semiconductor electrode with support

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5F051 AA14 5H032 AA06 AS16 BB00 BB05 EE01 EE04 EE05 EE07 EE12 EE16 EE18 HH01 HH04 HH07

Claims (11)

[Claims] 1. An optical semiconductor electrode, wherein optical semiconductor particles are supported on a conductive porous polymer film and are transparent. 2. The porous polymer film is filled in the pores of the porous polymer film and forms the optical semiconductor layer on one surface of the porous polymer film. The optical semiconductor electrode according to claim 1, which is supported on a film. 3. The optical semiconductor device according to claim 1, further comprising a transparent support, wherein a highly conductive layer is formed on one side surface of the transparent support, and the optical semiconductor electrode according to claim 1 or 2 is laminated on the highly conductive layer. Optical semiconductor electrode. 4. The photosemiconductor electrode according to claim 1, wherein the photosemiconductor particles are supported on the porous polymer film using a binder. 5. The photosemiconductor electrode according to claim 1, wherein a photosensitizing dye is attached to the photosemiconductor particles. 6. The photosemiconductor electrode according to claim 1, wherein the conductive porous polymer film has a conductive inorganic compound supported on a continuous porous polymer film. . 7. The photosemiconductor electrode according to claim 6, wherein the thickness of the communicating porous polymer film is 30 μm or less. 8. The optical semiconductor electrode according to claim 6, wherein the conductive inorganic compound is supported on the communicating porous polymer film using a binder. 9. The communication type porous polymer film is stretched porous polytetrafluoroethylene.
9. The optical semiconductor electrode according to any one of 8. 10. The optical semiconductor electrode according to claim 1, which has a light transmittance at 550 nm of 5% or more. 11. A method for coating an optical semiconductor electrode, comprising: applying a coating liquid obtained by dispersing a conductive inorganic compound and optical semiconductor particles to at least one surface of a communication-type porous polymer film and drying the coating liquid. Production method.