WO2014091809A1 - Electrode substrate and dye-sensitized solar cell - Google Patents

Abstract

An electrode substrate is provided with a conductive substrate, a porous film that is formed on the conductive substrate, and a catalyst layer that is applied to the porous film.

Description

Electrode substrate and dye-sensitized solar cell

The present invention relates to an electrode substrate that can be used as a counter electrode of a dye-sensitized solar cell and a dye-sensitized solar cell using the electrode substrate.
This application claims priority based on Japanese Patent Application No. 2012-273719 for which it applied to Japan on December 14, 2012, and uses the content here.

A so-called Gretzel type system is known as a dye-sensitized solar cell (Non-Patent Document 1). When light is irradiated to the sensitizing dye adsorbed on the porous oxide semiconductor layer constituting the photoelectrode, electrons are generated. These electrons flow in the order of the dye, the porous oxide semiconductor layer, the transparent conductive film, and the external circuit, and are taken out as a current. On the other hand, the dye that has released the electrons is reduced by the redox couple in the electrolyte, and the oxidized redox couple is regenerated into a reductant by the catalyst layer constituting the counter electrode.

A platinum electrode (platinum thin film) formed on a substrate is widely used as a catalyst layer constituting a counter electrode of a conventional dye-sensitized solar cell. Known methods for forming a platinum electrode include a method in which a chloroplatinic acid solution is applied on a substrate and heat-treated, and a method such as vacuum deposition and sputtering. However, since platinum is an expensive noble metal, the use of a platinum electrode has a problem of increasing the production cost of the dye-sensitized solar cell. Furthermore, there is a problem that the durability of platinum against I ⁻ ions (iodide ions) is not sufficient in the presence of moisture.

In order to solve this problem, a new catalyst layer material that can replace the platinum electrode has been studied. For example, a counter electrode using a conductive polymer such as polythiophene, polyaniline, or polypyrrole as a catalyst layer is used as a dye-sensitized solar cell. An applied example is disclosed (Non-patent Document 2, Patent Documents 1 and 2).

However, the power generation efficiency when using a catalyst layer having these conductive polymers is much lower than the power generation efficiency when using a catalyst layer made of a platinum electrode. This is because the electrical conductivity of the conductive polymer and the reduction ability as a catalyst (reduction ability to I ₃ ⁻ → I ⁻ ) are lower than the electrical conductivity and reduction ability of platinum.

The reducing ability of the catalyst layer is determined by “catalytic activity” × “specific surface area of the catalyst layer”, but the conductive polymer has lower catalytic activity than platinum. For this reason, when the catalyst layer made of a conductive polymer has a specific surface area comparable to that of the platinum electrode, the reducing ability of the catalyst layer made of the conductive polymer is inferior to that of the platinum electrode. Therefore, a method for improving the specific surface area and conductivity of the catalyst layer by mixing a carbon material such as carbon nanotubes and carbon particles into the catalyst layer made of a conductive polymer and improving the reducing ability of the catalyst layer is also disclosed. (Patent Documents 3 to 4). For example, the structure of the conventional catalyst layer is represented as shown in the schematic diagram of FIG. The catalyst layer in FIG. 1 has a configuration in which a film of a conductive polymer 23 that embeds a carbon material 22 is formed on a conductive substrate 21.

JP 2003-313317 A JP 2003-317814 A JP 2006-147411 A JP 2011-14411 A

However, even when the catalyst layer manufactured by the methods of Patent Documents 3 to 4 is used, the specific surface area of the catalyst layer is not sufficient, so that the reducing ability of the catalyst layer does not reach or exceed that of the platinum electrode. Further, in the catalyst layers of Patent Documents 3 to 4, since the conductive polymer and the carbon material are mixed in a messy state, the structure (porosity) controllability of the catalyst layer is low. There are concerns about variations in reducing ability of the catalyst layer and variations in film strength. Further, in the catalyst layer, the carbon materials are bound through the conductive polymer without being in direct contact, and there are many regions where the carbon material and the conductive substrate are not in direct contact. Resistance increases and does not reach the platinum electrode in terms of electrical conductivity. For this reason, improvement in the performance of an electrode substrate using a catalyst layer having a conductive polymer and improvement in power generation efficiency of a dye-sensitized solar cell using the electrode substrate as a counter electrode are required.

The present invention has been made in view of the above circumstances, and an electrode substrate capable of realizing power generation efficiency equal to or higher than that of a platinum electrode used as a counter electrode of a conventional dye-sensitized solar cell, and a dye sensitizer. An object is to provide a solar cell.

(1) An electrode substrate having a conductive substrate, a porous film formed on the conductive substrate, and a catalyst layer coated on the porous film.
(2) The electrode substrate according to (1), wherein the catalyst layer is coated along a three-dimensional structure of the porous membrane.
(3) The electrode substrate according to (1) or (2) above, wherein a solid cell structure in which a plurality of single holes are connected to the porous film coated with the catalyst layer is included.
(4) In the porous membrane coated with the catalyst layer, the number of the ream structure is larger than the number of the single holes. (5) The electrode substrate according to (3), wherein the porous membrane is a metal or The electrode substrate according to any one of (1) to (4), which is made of a metal compound.
(6) The electrode substrate according to any one of (1) to (4), wherein the porous film is made of a carbon material.
(7) The electrode substrate according to any one of (1) to (6), wherein the catalyst layer is made of a conductive polymer.
(8) The electrode substrate according to (7), wherein the conductive polymer is a polymer of a thiophene compound represented by the following general formula (1).

[Wherein R ¹ and R ² are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an aryl group having 6 or 8 carbon atoms, a carboxyl group, It represents any of an ester group, an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amino group, a nitro group, an azo group, a sulfo group, and a sulfonyl group. When R ¹ and R ² are the alkyl group or alkoxy group, the carbon atoms at the terminals of the alkyl group or alkoxy group may be bonded to form a ring. ]
(9) The electrode substrate according to (7), wherein the conductive polymer is a polymer of a pyrrole compound represented by the following general formula (2).

[Wherein R ³ and R ⁴ each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an aryl group having 6 or 8 carbon atoms, a carboxyl group, An ester group, an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amino group, a nitro group, an azo group, a sulfo group, or a sulfonyl group is represented. When R ³ and R ⁴ are the alkyl group or alkoxy group, carbon atoms at the terminals of the alkyl group or alkoxy group may be bonded to form a ring. ]
(10) The electrode substrate according to (7), wherein the conductive polymer is a polymer of an aniline compound represented by the following general formula (3).

[Wherein R ⁵ to R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an aryl group having 6 or 8 carbon atoms, a carboxyl group, An ester group, an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amino group, a nitro group, an azo group, a sulfo group, or a sulfonyl group is represented. When R ⁵ and R ⁶ , or R ⁷ and R ⁸ are the alkyl group or alkoxy group, carbon atoms at the terminals of the alkyl group or alkoxy group may be bonded to form a ring. ]

(11) The electrode substrate according to any one of (1) to (10), wherein a surface of the conductive substrate is in contact with the porous film.
(12) The electrode according to any one of (7) to (11), wherein the conductive polymer is coated on the porous film by an electrolytic polymerization method using the porous film as a working electrode. substrate.
(13) A dye-sensitized solar cell comprising a counter electrode constituted by the electrode substrate according to any one of (1) to (12), a photoelectrode adsorbing a dye, and an electrolytic solution.

The electrode substrate of the present invention has a wide specific surface area that functions as a catalyst because a porous polymer film having a wide specific surface area is coated with a catalyst layer such as a conductive polymer. Further, when the electrode substrate of the present invention has a structure in which a catalyst layer such as a conductive polymer is coated along a three-dimensional structure of a porous film having a wide specific surface area, the electrode substrate further functions as a catalyst. Has a large specific surface area. As a result, the reduction ability of the catalyst determined by “catalytic activity” × “specific surface area of the catalyst layer” can be improved, and the power generation efficiency of the dye-sensitized solar cell using the electrode substrate of the present invention can be improved. be able to.
In the electrode substrate of the present invention, the electrical contact portion between the conductive substrate and the porous membrane and the electrical contact portion between the porous membrane and the coating of the catalyst layer such as the conductive polymer are homogeneous and reliable. Therefore, it is excellent in conductivity. As a result, the power generation efficiency of the dye-sensitized solar cell using the electrode substrate of the present invention can be improved.
Furthermore, in the electrode substrate of the present invention, since the three-dimensional structure of the porous film formed on the conductive substrate functions as a support member for the coating of the catalyst layer such as a conductive polymer, The structural strength is improved (as compared to a film of a functional polymer alone (a catalyst layer alone)). As a result, the production yield in the case of producing a dye-sensitized solar cell using the electrode substrate of the present invention can be improved, and the use environment of the dye-sensitized solar cell is an environment in which an external force is applied to the counter electrode. In this case, the dye-sensitized solar cell can be given excellent durability.

Since the dye-sensitized solar cell of the present invention uses the electrode substrate of the present invention, the dye-sensitized solar cell is excellent in power generation efficiency and exhibits excellent durability even in a use environment in which an external force is applied to the counter electrode.

It is a cross-sectional schematic diagram of a conventional counter electrode. It is a cross-sectional schematic diagram of the electrode substrate (counter electrode) of the first embodiment. It is a cross-sectional schematic diagram of the dye-sensitized solar cell of 2nd embodiment. 10 is an SEM image obtained by observing the surface of the counter electrode of Example 9. 10 is an SEM image obtained by observing the surface of the porous film before coating PEDOT on the surface of the counter electrode of Example 9. 10 is an SEM image obtained by observing a cross section of a counter electrode of Example 9. 4D is an enlarged image of the cross section of FIG. 4C. 10 is an SEM image obtained by observing the surface of the counter electrode of Example 10. 10 is an SEM image obtained by observing the surface of the porous film before coating PEDOT on the surface of the counter electrode of Example 10. 10 is an SEM image obtained by observing the surface of the counter electrode of Example 7. 6 is an SEM image obtained by observing the surface of a porous film before coating PEDOT on the surface of the counter electrode of Example 7. 10 is an SEM image obtained by observing the surface of the counter electrode of Example 8. 10 is an SEM image obtained by observing the surface of the porous film before coating PEDOT on the surface of the counter electrode of Example 8. 10 is an SEM image obtained by observing the surface of the counter electrode of Comparative Example 6. 10 is an SEM image obtained by observing the surface of the counter electrode of Comparative Example 7. 14 is an SEM image obtained by observing the surface of a counter electrode of Comparative Example 11.

Hereinafter, the present invention will be described with reference to the drawings based on preferred embodiments, but the present invention is not limited to such embodiments.
<Electrode substrate>
The electrode substrate of the first embodiment of the present invention includes a porous film 2 formed on a conductive substrate 1 as shown in FIG. The porous membrane 2 has pores communicating with the outside in a three-dimensional manner, not only on the surface facing the outside, but also inside the membrane. It is preferable that the porous membrane 2 includes a continuous cell structure in which a plurality of single independent holes (single holes) are connected. In the porous membrane 2, it is preferable that the number (existence ratio) of the cell structure is larger than the number (existence ratio) of the single pores.
The porous membrane 2 having a continuous cell structure is preferable because the redox couple contained in the electrolytic solution can permeate sufficiently from the surface to the inside. Furthermore, in the porous membrane 2 having a continuous cell structure, an area where the surface of the porous membrane and the electrolyte solution contact (surface area where an electrochemical reaction occurs) increases, and as a result, the reduction reaction is more efficiently performed. There is an advantage to go.
The surface of the porous membrane 2 is coated with a catalyst layer 3 such as a conductive polymer. Here, the surface of the porous membrane 2 includes the surface of the internal porous structure communicating with the outside. Moreover, it is preferable that the catalyst layer 3 is coated along a three-dimensional porous membrane structure constituted by the above-mentioned streak structure of the porous membrane 2. By coating the catalyst layer 3 on the surface (inner wall surface) of the three-dimensional porous structure in this way, the specific surface area contributing to the catalyst activity of the catalyst layer 3 becomes much larger than before.
In the electrode substrate of the first embodiment, since the porous film 2 has a three-dimensionally connected structure, the electric resistance inside the porous film is reduced and the electric conductivity is excellent. In addition, since the entire lower surface of the porous film 2 is in direct contact with the conductive film 1a constituting the conductive substrate 1, the electrical contact portion between the conductive substrate 1 and the porous film 2 is homogeneous and reliable. Is formed. Further, since the porous film 2 and the coating layer of the conductive polymer 3 (catalyst layer 3) are in contact with each other in almost the entire region where the porous film 2 is not in contact with the conductive substrate 1, the porous film 2 The electrical contact portion between the conductive polymer 3 and the conductive polymer 3 (catalyst layer 3) is uniformly and reliably formed. Thus, since the electrical contact portion is uniformly and reliably formed, the conductivity of the electrode substrate of the first embodiment is excellent.

(Conductive substrate)
The conductive substrate 1 includes a conductive film 1a that imparts conductivity and a substrate 1b.
The kind in particular of the said conductive film is not restrict | limited, For example, a transparent conductive film and a metal film are applicable.
The kind in particular of the said transparent conductive film is not restrict | limited, The transparent conductive film used for a conventionally well-known dye-sensitized solar cell is applicable, For example, the thin film comprised with a metal oxide is mentioned.

Examples of the metal oxide include tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), indium-doped zinc oxide (IZO), gallium-doped zinc oxide (GZO), and aluminum-doped zinc oxide. (AZO), zinc oxide, tin oxide and the like. Among these, ITO with low specific resistance and high electrical conductivity and FTO excellent in heat resistance and weather resistance are particularly preferable.
Examples of the metal film include gold (Au), platinum (Pt), silver (Ag), copper (Cu), chromium (Cr), tungsten (W), aluminum (Al), magnesium (Mg), and titanium (Ti). , Nickel (Ni), manganese (Mn), zinc (Zn), iron (Fe), and alloys thereof, and the like, Au, Pt, Cr, Ti, Ni excellent in electrical conductivity and weather resistance are particularly preferable. preferable.

The type of the substrate 1b is not particularly limited as long as the conductive film or the metal film can be formed on the surface. For example, a glass substrate, a metal substrate, a resin substrate, etc. are mentioned.

The conductive substrate 1 of the first embodiment is not necessarily provided with the conductive film because the substrate surface only needs to have conductivity. Examples of the conductive substrate 1 include a metal substrate and a conductive resin substrate. Moreover, the conductive substrate 1 which comprises the electrode substrate of 1st embodiment contains the conductive film and conductive sheet which have flexibility. When a conductive film or a conductive sheet is used as the conductive substrate 1, the conductive substrate 1 can be read as a conductive base material.

(Porous membrane)
The porous membrane 2 of the first embodiment is a membrane (layer) having a three-dimensional porous structure, and the structure is a single structure formed by using a structure in which fine particles 2a are joined or a phase separation structure. And a structure in which nano meshes are laminated.
The material constituting the fine particles 2a is not particularly limited as long as it has conductivity or semiconductor characteristics, but from the viewpoint of obtaining a porous film having high structural strength, titanium, platinum, gold, silver, copper, aluminum, cobalt, iron, magnesium Metals such as nickel, zinc, titanium oxide, tin oxide, zinc oxide, gallium oxide, indium oxide, aluminum oxide, chromium oxide, cobalt oxide, copper oxide, iron oxide, titanium carbide, vanadium carbide, tungsten carbide, titanium nitride Metal compounds such as vanadium nitride, and carbon materials such as carbon black, carbon nanotubes, carbon fibers, activated carbon, and graphite are preferable.
Among these, from the viewpoint of low cost and mass production, it is preferable to use fine particles made of a metal compound containing a metal oxide or a carbon material. As the material constituting the fine particles, titanium oxide, tin oxide, zinc oxide, and carbon black are particularly preferable.

The shape of the fine particles 2a is not particularly limited, and examples thereof include spherical, needle-like, fiber-like, bowl-like and sea urchin-like fine particles.
The primary particle size of the spherical fine particles may vary in a suitable range depending on the method of forming the fine particles on the conductive substrate 1, but is usually preferably 1 nm to 500 μm, more preferably 1 nm to 250 μm, and more preferably 5 nm. Is more preferably from 100 to 100 μm, particularly preferably from 10 to 10 μm, most preferably from 10 to 1 μm. In addition, as a method for obtaining the primary particle diameter of the fine particles, for example, a method of determining the peak value of the volume average diameter distribution obtained by measurement with a laser diffraction particle size distribution measuring device or the long diameters of a plurality of fine particles by SEM observation. The method of measuring and averaging is mentioned. The primary particle diameter of the fine particles is preferably measured by the SEM observation.

The primary particle diameter of the acicular, fibrous, or bowl-shaped fine particles may vary in a suitable range depending on the method of forming the particles on the conductive substrate 1, but is usually 1 nm to 500 μm is preferable, 1 nm to 250 μm is more preferable, 5 nm to 100 μm is still more preferable, 10 nm to 10 μm is particularly preferable, and 10 nm to 5 μm is most preferable. In the minor axis direction, 1 nm to 500 μm is preferable, 1 nm to 250 μm is more preferable, 5 nm to 100 μm is further preferable, 10 nm to 10 μm is particularly preferable, and 10 nm to 1 μm is most preferable.

One type of fine particles constituting the porous membrane 2 may be used alone, or two or more types may be used in combination.

The thickness of the porous membrane 2 is not particularly limited, and is appropriately adjusted in consideration of the structural strength, for example, in the range of 0.1 μm to 100 μm. Although depending on the material of the fine particles, the thickness of the porous film 2 is preferably 0.1 μm to 10 μm from the viewpoint of enhancing the conductivity.

The porosity (porosity) of the porous membrane 2 is preferably as large as possible to increase the specific surface area. However, if the porosity is too large, the structural strength of the porous membrane 2 may be weakened. Considering this, the porosity of the porous membrane 2 is preferably 50 to 80%. The porosity (porosity) can be measured by a known method such as a gas adsorption method or a mercury intrusion method.

Here, the specific surface area of the porous membrane 2 coated with the catalyst layer 3 is preferably 0.1 m ² / g or more, when measured by a gas adsorption method, and is 1 m ² / g or more. Is more preferable, and it is still more preferable that it is 3 m < ² > / g or more. By being 3 m ² / g or more, the contact efficiency between the coated catalyst layer 3 and the electrolyte is improved, and the electrolyte can be efficiently reduced. That is, the catalyst efficiency can be further improved. The upper limit value of the specific surface area is not particularly limited, but for example, 300 m ² / g can be used as a guide for the upper limit value.

The method for forming the porous film 2 constituting the electrode substrate of the first embodiment on the conductive substrate 1 is not particularly limited as long as it is a method capable of forming a porous film having an appropriate porosity. The film forming method can be applied. For example, the film can be formed by applying a paste containing fine particles 2a having conductivity or semiconductor characteristics and a known binder resin on the conductive substrate 1, and further baking. Here, examples of the fine particles 2a include conductive fine particles and metal oxide fine particles.
In addition, the fine particles 2a having conductivity or semiconductor characteristics are sprayed onto the conductive substrate 1 with a carrier gas, whereby the fine particles 2a having conductivity or semiconductor characteristics and the conductive substrate 1 are joined, and the conductivity or semiconductor characteristics are improved. A porous film is obtained in which the fine particles 2a are joined. Examples of a method for forming the porous film 2 by spraying the fine particles 2a having conductivity or semiconductor characteristics include an aerosol deposition method (AD method).

(Catalyst layer)
In the electrode substrate of the first embodiment, the material constituting the catalyst layer 3 coated along the three-dimensional structure of the porous membrane 2 is a conductive material capable of reducing a redox couple constituting a known electrolyte. There is no particular limitation as long as it is a substance. Specifically, for example, platinum; conductive carbon material; titanium compounds such as titanium carbide TiC and titanium nitride TiN; vanadium compounds such as vanadium oxide V ₂ O ₃ and vanadium nitride VN; Etc.
The material constituting the catalyst layer 3 may be only one type or two or more types.

The method for forming the catalyst layer 3 with a metal having catalytic activity such as platinum is not particularly limited as long as it is a method capable of forming a platinum layer along the surface of the three-dimensional structure of the porous membrane 2. Specific examples include an electrolytic plating method and an electroless plating method using the conductivity of the porous film 2 and the conductive substrate 1.

The lower limit of the thickness of the catalyst layer 3 coated on the porous membrane 2 can vary depending on the material of the catalyst layer 3, but is usually preferably 0.01 nm or more, more preferably 0.1 nm or more. More preferably, it is 1 nm or more. When the thickness is 0.01 nm or more, sufficient catalytic activity can be obtained. The upper limit value of the thickness of the catalyst layer 3 is not particularly limited, but is preferably less than a thickness that completely fills the porous structure of the porous membrane 2, and more preferably 1000 nm or less. .
The thickness of the catalyst layer 3 exemplified here is formed on the surface (outer surface) of the porous membrane 2 facing the outside (that is, the surface recognized when the porous membrane 2 is viewed from above). The thickness of the catalyst layer 3 is said. As a method of examining the thickness of the catalyst layer 3 formed on the outer surface, a method of observing a cross section of the porous film 2 on which the catalyst layer 3 is formed with an electron microscope is preferable.

Below, the case where a conductive polymer is used as a material which comprises the catalyst layer 3 is demonstrated.

(Conductive polymer)
In the electrode substrate of the first embodiment, the catalyst layer is formed by coating the porous film 2 with the conductive polymer 3 (catalyst layer 3). By the coating, a layer of the conductive polymer 3 is formed on the surface of the porous membrane 2.
The kind in particular of said conductive polymer is not restrict | limited, A conventionally well-known conductive polymer is applicable, For example, the conductive polymer which the thiophene compound represented by following General formula (1) superposed | polymerized is mentioned.

[Wherein R ¹ and R ² are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an aryl group having 6 or 8 carbon atoms, a carboxyl group, It represents any of an ester group, an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amino group, a nitro group, an azo group, a sulfo group, and a sulfonyl group. When R ¹ and R ² are the alkyl group or alkoxy group, the carbon atoms at the terminals of the alkyl group or alkoxy group may be bonded to form a ring. ]

The alkyl group is preferably a linear or branched alkyl group, and more preferably a linear alkyl group.
The alkyl group preferably has 1 to 8 carbon atoms, more preferably 1 to 5, and still more preferably 1 to 3.

As said alkoxy group, a methoxy group, an ethoxy group, a propoxy group, and a butoxy group are preferable, and a methoxy group or an ethoxy group is more preferable.
Examples of the aryl group include a phenyl group, a benzyl group, a tolyl group, and a naphthyl group.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

When R ¹ and R ² are the alkyl group or alkoxy group, the carbon at the terminal of the alkyl group or alkoxy group is excluded except for one hydrogen atom bonded to the carbon atom at the terminal of the alkyl group or alkoxy group. Atoms may combine to form a ring.

Specific examples of the thiophene compound represented by the general formula (1) include compounds represented by the following formulas (1-1) to (1-4).

In addition, examples of the conductive polymer include a conductive polymer obtained by polymerizing a pyrrole compound represented by the following general formula (2).

[Wherein R ³ and R ⁴ each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an aryl group having 6 or 8 carbon atoms, a carboxyl group, It represents any of an ester group, an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amino group, a nitro group, an azo group, a sulfo group, and a sulfonyl group. When R ³ and R ⁴ are the alkyl group or alkoxy group, carbon atoms at the terminals of the alkyl group or alkoxy group may be bonded to form a ring. ]

The alkyl group is preferably a linear or branched alkyl group, and more preferably a linear alkyl group.
The alkyl group preferably has 1 to 8 carbon atoms, more preferably 1 to 5, and still more preferably 1 to 3.

As said alkoxy group, a methoxy group, an ethoxy group, a propoxy group, and a butoxy group are preferable, and a methoxy group or an ethoxy group is more preferable.
Examples of the aryl group include a phenyl group, a benzyl group, a tolyl group, and a naphthyl group.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

When R ³ and R ⁴ are the alkyl group or alkoxy group, the carbon at the terminal of the alkyl group or alkoxy group is excluded except for one hydrogen atom bonded to the carbon atom at the terminal of the alkyl group or alkoxy group. Atoms may combine to form a ring.

Specific examples of the pyrrole compound represented by the general formula (2) include compounds represented by the following formulas (2-1) to (2-4).

Further, examples of the conductive polymer include a conductive polymer obtained by polymerizing an aniline compound represented by the following general formula (3).

[Wherein R ⁵ to R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an aryl group having 6 or 8 carbon atoms, a carboxyl group, It represents any of an ester group, an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amino group, a nitro group, an azo group, a sulfo group, and a sulfonyl group. When R ⁵ and R ⁶ , or R ⁷ and R ⁸ are the alkyl group or alkoxy group, carbon atoms at the terminals of the alkyl group or alkoxy group may be bonded to form a ring. ]

The alkyl group is preferably a linear or branched alkyl group, and more preferably a linear alkyl group.
The alkyl group preferably has 1 to 8 carbon atoms, more preferably 1 to 5, and still more preferably 1 to 3.

As said alkoxy group, a methoxy group, an ethoxy group, a propoxy group, and a butoxy group are preferable, and a methoxy group or an ethoxy group is more preferable.
Examples of the aryl group include a phenyl group, a benzyl group, a tolyl group, and a naphthyl group.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

When R ⁵ to R ⁸ are the alkyl group or alkoxy group, the carbon atom at the terminal of the alkyl group or alkoxy group is removed except for one hydrogen atom bonded to the carbon atom at the terminal of the alkyl group or alkoxy group. Atoms may combine to form a ring.

Specific examples of the aniline compound represented by the general formula (3) include compounds represented by the following formulas (3-1) to (3-4).

The method for coating the porous polymer 2 constituting the electrode substrate of the first embodiment with a conductive polymer is not particularly limited, and examples thereof include the following methods (a) to (d).
(A) A porous film is immersed in a solution containing an unpolymerized monomer constituting a conductive polymer, and the monomer is subjected to electrolytic polymerization using the porous film as a working electrode, and conductive on the porous film. Coating is performed by synthesizing a functional polymer.
(B) A solution containing a prepolymerized conductive polymer is applied to the porous film, and the solvent is volatilized to coat.
(C) A mixture containing a prepolymerized conductive polymer and another known binder resin is applied to the porous film, and the mixture is solidified to be coated.
(D) The porous membrane is immersed in a solution containing unpolymerized monomers constituting the conductive polymer, and a known oxidizing agent (for example, iron chloride) is added to the solution to Coating is performed by synthesizing a conductive polymer.

Of the above methods (a) to (c), the method (a) or (b) is preferable, and the method (a) is more preferable. In the method (c), since the binder resin remains on the porous film, the electrical contact between the conductive polymer and the porous film may be weakened. In the method (d), there is a possibility that the conductive polymer is overpolymerized, and as a result, there is a risk of filling the pores inside the porous film. On the other hand, in the methods (a) and (b), the porous membrane and the conductive polymer are in direct contact with each other, so that sufficient electrical contact between them can be obtained. Furthermore, according to the method (a), since the polymerization reaction occurs also in the pores (porous structure) inside the porous membrane (that is, inside the three-dimensional structure of the porous membrane), the pores are formed. The inner wall surface can be sufficiently coated with the conductive polymer. Therefore, the method (a) is more preferable.

Molar concentration of the conductive polymer coating the porous membrane 2, from the viewpoint of enhancing the reducibility of the catalyst is preferably 0.00001 ~ 1mol / cm ^3, more preferably 0.0001 ~ 0.1mol / cm ³ 0.001 to 0.01 mol / cm ³ is more preferable.

In the electrode substrate of the first embodiment, since the specific surface area of the region (catalyst layer) functioning as a catalyst is increased, and the conductivity and the structural strength are improved, the electrode substrate is opposed to the dye-sensitized solar cell. When used as an electrode, it greatly contributes to the improvement of power generation efficiency.
Below, the dye-sensitized solar cell using the electrode of 1st embodiment is demonstrated.

《Dye-sensitized solar cell》
The dye-sensitized solar cell according to the second embodiment of the present invention includes the electrode substrate of the first embodiment as a counter electrode (counter electrode substrate), and further, a photoelectrode (photoelectrode substrate) that adsorbs the dye, an electrolyte solution, It has. An example of such a dye-sensitized solar cell is the dye-sensitized solar cell 10 shown in FIG.

The dye-sensitized solar cell 10 includes a photoelectrode 11 composed of a transparent conductive film 7 and a porous oxide semiconductor layer 8 laminated on a transparent substrate 6, a counter electrode 12, and an electrolytic solution 5. The electrolytic solution 5 is sealed between the photoelectrode 11 and the counter electrode 12 by the sealing material 4.

(Photoelectrode)
The photoelectrode 11 includes a glass substrate that is the transparent substrate 6, a transparent conductive film 7, and a porous oxide semiconductor layer 8. A known sensitizing dye is adsorbed on the surface of the porous oxide semiconductor layer 8 with which the electrolytic solution 5 is in contact (including the surface inside the porous film (porous body)).

The substrate (base material) constituting the photoelectrode 11 is not limited to glass and is not particularly limited as long as it is a substrate having visible light permeability. For example, in addition to a glass substrate, a transparent resin substrate, a film or a sheet can be used.

As the glass, glass having visible light permeability is preferable, and soda lime glass, quartz glass, borosilicate glass, Vycor glass, non-alkali glass, blue plate glass, white plate glass and the like can be mentioned.

As the resin (plastic), a resin having visible light permeability is preferable, and examples thereof include polyacryl, polycarbonate, polyester, polyimide, polystyrene, polyvinyl chloride, and polyamide. Among these, polyesters, particularly polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are produced and used in large quantities as transparent heat-resistant films. From the viewpoint of producing a thin and light flexible dye-sensitized solar cell, the substrate is preferably a plastic transparent substrate, and more preferably a PET or PEN film.

As the oxide semiconductor composing the porous oxide semiconductor layer 8, a conventionally known material can be applied as long as it can adsorb a sensitizing dye. Examples thereof include titanium oxide, zinc oxide, and strontium titanate.

When the porous oxide semiconductor layer 8 (porous layer) is composed of oxide semiconductor fine particles, the porous layer is formed by firing a known paste containing the fine particles on the substrate. It may be a porous layer. In addition, a porous layer formed in such a state that the fine particles and the substrate and the fine particles are bonded to each other by spraying the fine particles onto the substrate with a carrier gas may be applied. As a method for forming a porous layer by spraying fine particles, an aerosol deposition method (AD method) can be exemplified.

The primary particle diameter of the fine particles may vary in a suitable range depending on the method of forming the fine particles on the substrate, but is usually preferably 1 nm to 500 μm, more preferably 1 nm to 250 μm, and more preferably 5 nm to 100 μm. Further preferred is 10 nm to 10 μm. In addition, as a method for obtaining the primary particle diameter of the fine particles, for example, a method of determining the peak value of the volume average diameter distribution obtained by measurement with a laser diffraction particle size distribution measuring device or the long diameters of a plurality of fine particles by SEM observation. The method of measuring and averaging is mentioned. The primary particle diameter of the fine particles is preferably measured by the SEM observation.

[Electrolyte]
As the electrolytic solution 5, an electrolytic solution used in a conventionally known dye-sensitized solar cell can be applied.
In the electrolytic solution 5, a redox couple (electrolyte) is dissolved. As the redox couple, a conventionally known redox couple can be applied. The electrolyte solution 5 may contain other additives such as fillers and thickeners without departing from the spirit of the present invention.

Examples of the redox pair include a combination of iodine molecule and iodide, or a combination of bromine molecule and bromine compound.
Suitable examples of the iodide include metal iodides such as sodium iodide (NaI) and potassium iodide (KI), or iodine salts such as tetraalkylammonium iodide, pyridinium iodide, and imidazolium iodide. Listed as iodide.
Examples of the bromine compound include metal bromides such as sodium bromide (NaBr) and potassium bromide (KBr), and bromine salts such as tetraalkylammonium bromide, pyridinium bromide, and imidazolium bromide as suitable bromine compounds. It is done.

The concentration of the redox couple in the electrolytic solution 5 is not particularly limited, but is preferably 0.1 to 10 mol / L, more preferably 0.2 to 2 mol / L. Further, when iodine is added to the solvent of the electrolytic solution 5, a preferable iodine concentration is 0.01 to 1 mol / L.

Instead of the electrolytic solution 5, an electrolyte layer (solid electrolyte layer) may be applied. The electrolyte layer has the same function as the electrolytic solution 5 and is in a gel or solid state. As the electrolyte layer, for example, an electrolyte layer obtained by gelling or solidifying the electrolyte solution 5 by adding a gelling agent or a thickener to the electrolyte solution 5 and removing the solvent as necessary can be applied. When a gel-like or solid electrolyte layer is used, there is no possibility that the electrolyte solution leaks from the dye-sensitized solar cell 10.

The electrolytic solution 5 or the electrolyte layer may contain a conventionally known conductive polymer.

The sealing material is preferably a member that can hold the electrolytic solution inside the battery cell. As such a sealing material, synthetic resins, such as a conventionally well-known thermoplastic resin and a thermosetting resin, are applicable, for example.

(Counter electrode)
The counter electrode 12 in the dye-sensitized solar cell of the second embodiment is the electrode substrate of the first embodiment.

(Method for producing dye-sensitized solar cell)
The dye-sensitized solar cell of the second embodiment can be produced by a conventional method except that the electrode substrate (counter electrode 12) of the first embodiment is used.

Since the coating layer of the conductive polymer (catalyst layer) of the electrode substrate of the first embodiment which is the counter electrode 12 is supported by the porous film, it has high structural strength. For this reason, also when a jig etc. contact the said coating layer at the time of manufacture, the possibility that the said coating layer will be reduced is reduced. Therefore, the production yield of the dye-sensitized solar cell of the second embodiment can be improved by using the electrode substrate of the first embodiment as a counter electrode.

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[Example 1]
(Formation of porous oxide semiconductor layer)
A porous oxide semiconductor layer (thickness 8 μm) was formed using a paste composed of 19% by mass of titanium oxide particles (particle diameter Φ19 nm), 9% by mass of ethyl cellulose, and 72% by mass of terpineol. As a transparent conductive substrate, a glass substrate having a surface resistance of 10 ohms (Ω) provided with an FTO film was used, and the paste was applied on the FTO film in an area of 4 mm × 4 mm by screen printing, and then at 500 ° C. in an air atmosphere. Was baked for 30 minutes to form a porous oxide semiconductor layer (transparent layer) on the transparent conductive film.

(Dye adsorption)
By immersing the substrate on which the porous oxide semiconductor layer is formed in a dye solution in which a sensitizing dye N719 is dissolved in a 1: 1 mixture of acetonitrile and tert-butanol at a concentration of 0.3 mM for 20 hours, A sensitizing dye was adsorbed on the porous oxide semiconductor layer of the photoelectrode.

(Preparation of counter electrode)
A porous film was formed using a paste composed of 19% by mass of titanium oxide particles (particle diameter Φ19 nm), 9% by mass of ethyl cellulose, and 72% by mass of terpineol. As a transparent conductive substrate, a glass substrate having a surface resistance of 10 ohms (Ω) provided with an FTO film was used, and the paste was applied on the FTO film in an area of 4 mm × 4 mm by screen printing, and then at 500 ° C. in an air atmosphere. Was baked for 30 minutes to form a porous titanium oxide film (thickness: 1.5 μm) on the transparent conductive film. Since the titanium oxide particles constituting the porous film thus formed and the FTO film are in direct contact with each other, the conductivity between the porous film and the FTO film is excellent.

Next, the conductive polymer was coated on the porous film by an electrolytic polymerization method. Using the porous film and the FTO film as the working electrode, a platinum wire as the counter electrode, and an Ag / Ag ⁺ electrode as the reference electrode, electropolymerization of the conductive polymer was performed. For the electropolymerization, 10 ⁻² M EDOT (3,4-ethylenedioxythiophene: a compound represented by the above formula (1-1)), 10 ⁻¹ M LiTFSI (lithium bistrifluoromethanesulfonylimide) is used. The above working electrode, counter electrode, and reference electrode are immersed in the acetonitrile solution, and a voltage of 40 V is applied at 1.2 V using a potentiostat (manufactured by IVIUM). Molecules (PEDOT: TFSI) were formed. That is, the catalyst layer 3 (the conductive polymer layer) along the three-dimensional structure of the porous membrane as schematically shown in FIG. 2 could be formed.

(Evaluation of film strength)
The prepared counter electrode is immersed in ethanol, stimulated with ultrasonic waves (oscillation frequency 42 kHz) for 5 minutes, and then the surface of the porous film coated with the conductive polymer of the counter electrode is observed to obtain the film strength. Evaluated. Evaluation was performed in the following two stages. The results are also shown in Table 1.
Good (A): Peeling and damage are hardly seen.
Defect (B): It is seen so that peeling and damage cannot be overlooked.

(Cell assembly and power generation performance evaluation)
The counter electrode and the photoelectrode prepared by the above method are overlapped and clipped via a resin gasket (separator) having a thickness of 30 μm, and a dye-sensitized solar cell ( Cell). As an electrolytic solution, iodine 0.03M, 1,3-dimethyl-2-propylimidazolium iodide 0.6M, lithium iodide 0.10M, and tert-butylpyridine 0.5M were dissolved in acetonitrile as a solvent. The obtained electrolytic solution was used.
As the power generation performance of the produced cell, photoelectric conversion efficiency η, short circuit current Isc, open circuit voltage Voc, and fill factor FF were evaluated by a solar simulator (AM1.5). The results are shown in Table 1.

[Example 2]
A dye-sensitized solar cell was produced in the same manner as in Example 1 except that the fine particles constituting the counter electrode were changed to zinc oxide particles (particle diameter Φ23 nm), and the power generation performance was evaluated. The results are shown in Table 1.

[Example 3]
A dye-sensitized solar cell was prepared in the same manner as in Example 1 except that the fine particles constituting the counter electrode were changed to carbon black (particle diameter Φ23 nm), and the power generation performance was evaluated. The results are shown in Table 1.

[Comparative Example 1]
A dye-sensitized solar cell was produced in the same manner as in Example 1 except that a platinum electrode substrate in which a platinum thin film was formed on a glass substrate by a sputtering method was used as the counter electrode, and power generation performance was evaluated. The results are shown in Table 1.

[Comparative Example 2]
A glass substrate on which the same FTO film as that in Example 1 was disposed was used as a working electrode, and electropolymerization was performed in the same manner as in Example 1 to form a conductive polymer on the FTO film to produce a counter electrode.
Except for the counter electrode, a dye-sensitized solar cell was produced in the same manner as in Example 1, and the power generation performance was evaluated. The results are shown in Table 1.

[Comparative Example 3]
A dye-sensitized solar cell was prepared in the same manner as in Example 1 except that the conductive polymer was not coated on the porous film constituting the counter electrode, and the power generation performance was evaluated. The results are shown in Table 1.

[Comparative Example 4]
A dye-sensitized solar cell was produced in the same manner as in Example 2 except that the conductive polymer was not coated on the porous film constituting the counter electrode, and the power generation performance was evaluated. The results are shown in Table 1.

[Comparative Example 5]
A dye-sensitized solar cell was prepared in the same manner as in Example 3 except that the porous polymer constituting the counter electrode was not coated with the conductive polymer, and the power generation performance was evaluated. The results are shown in Table 1.

From the results of Table 1, it is clear that the photoelectric conversion efficiency (power generation efficiency) η of Examples 1 to 3 according to the present invention is equal to or higher than that of Comparative Examples 1 to 5. .

[Example 4]
In the production of the photoelectrode, on the porous oxide semiconductor layer (transparent layer) (film thickness 8 μm) formed in the same manner as in Example 1, a reflective layer (film thickness 4 μm) made of titanium oxide particles having a particle diameter of 400 nm. Then, a cell (a dye-sensitized solar cell) was produced in the same manner as in Example 1 except that the dye was adsorbed on the transparent layer and the reflective layer.
As in the case of forming the transparent layer, the reflective layer is formed by printing a paste composed of 19% by mass of titanium oxide (particle diameter Φ400 nm), 9% by mass of ethyl cellulose, and 72% by mass of terpineol on the transparent layer, It was formed by firing at 500 ° C.
Here, the transparent layer and the reflective layer differ in the particle size of the titanium oxide contained. The transparent layer can be read as the first layer, and the reflective layer can be read as the second layer.
In addition, adsorption | suction of the pigment | dye was performed like Example 1 after laminating | stacking and baking the said 1st layer and 2nd layer.

[Example 5]
A cell was produced in the same manner as in Example 4 except that the titanium oxide particles having a particle size of 19 nm were changed to titanium oxide particles having a particle size of 30 nm in the production of the counter electrode.

[Example 6]
A cell was prepared in the same manner as in Example 4 except that in the production of the counter electrode, the titanium oxide particles having a particle size of 19 nm were changed to titanium oxide particles having a particle size of 200 nm.

[Example 7]
A cell was produced in the same manner as in Example 4 except that the titanium oxide particles having a particle size of 19 nm were changed to ATO (antimony-doped tin oxide) particles having a particle size of 10 to 30 nm in the production of the counter electrode.

[Example 8]
A cell was prepared in the same manner as in Example 4 except that the titanium oxide particles having a particle diameter of 19 nm were changed to ATO needle particles having a long axis particle diameter of 200 to 2000 nm and a short axis particle diameter of 10 to 20 nm in the preparation of the counter electrode. did.

[Example 9]
A cell was produced in the same manner as in Example 4 except that the titanium oxide particles having a particle size of 19 nm were changed to titanium oxide particles coated with ATO having a particle size of 200 to 500 nm in the production of the counter electrode.

[Example 10]
A cell was produced in the same manner as in Example 4 except that the titanium oxide particles having a particle size of 19 nm were changed to carbon black particles having a particle size of 23 nm in the production of the counter electrode.

[Example 11]
A cell was prepared in the same manner as in Example 4 except that the porous film formed of titanium oxide particles having a particle diameter of 19 nm was changed to a nickel mesh having an opening of 8 μm, a wire diameter of 8 μm, and a thickness of 3 μm. did.

[Example 12]
In preparation of the counter electrode, Example 10 was carried out except that PEDOT obtained by polymerizing EDOT of the formula (1-1) was changed to polypyrrole obtained by polymerizing pyrrole of the formula (2-2) as a coating material for the catalyst layer. A cell was prepared in the same manner as described above.

[Example 13]
In the production of the counter electrode, Example 10 was carried out except that PEDOT obtained by polymerizing EDOT of the formula (1-1) was changed to polyaniline polymerized by aniline of the formula (3-1) as a coating material for the catalyst layer. A cell was prepared in the same manner as described above.

[Example 14]
In the production of the counter electrode, instead of forming the PEDOT catalyst layer by the electrolytic polymerization method, the porous membrane was immersed in 10 mM 2-propanol solution of chloroplatinic acid and then baked at 450 ° C. A cell was produced in the same manner as in Example 4 except that a catalyst layer made of platinum was formed on the surface.

[Example 15]
A cell was produced in the same manner as in Example 14 except that the titanium oxide particles having a particle size of 19 nm were changed to ATO (antimony-doped tin oxide) particles having a particle size of 10 to 30 nm in the production of the counter electrode.

[Example 16]
A cell was produced in the same manner as in Example 14 except that in the production of the counter electrode, the titanium oxide particles having a particle diameter of 19 nm were changed to carbon black particles having a particle diameter of 23 nm.

[Comparative Example 6]
In the production of the photoelectrode, a reflective layer (film thickness 4 μm) made of titanium oxide particles having a particle diameter of 400 nm on a porous oxide semiconductor layer (transparent layer) (film thickness 8 μm) formed in the same manner as in Comparative Example 1. Then, a cell was prepared in the same manner as in Comparative Example 1 except that the pigment was adsorbed on the transparent layer and the reflective layer. The reflective layer was formed by the same method as in Example 4.

[Comparative Example 7]
In the production of the photoelectrode, a reflective layer (film thickness 4 μm) made of titanium oxide particles having a particle diameter of 400 nm on a porous oxide semiconductor layer (transparent layer) (film thickness 8 μm) formed in the same manner as in Comparative Example 2. Then, a cell was prepared in the same manner as in Comparative Example 2 except that the pigment was adsorbed on the transparent layer and the reflective layer. The reflective layer was formed by the same method as in Example 4.

[Comparative Example 8]
Comparative Example 7 except that PEDOT obtained by polymerizing EDOT of the formula (1-1) was changed to polypyrrole obtained by polymerizing pyrrole of the formula (2-2) as a coating material for the catalyst layer in the production of the counter electrode. A cell was prepared in the same manner as described above.

[Comparative Example 9]
Comparative Example 7 except that PEDOT obtained by polymerizing EDOT of the formula (1-1) was changed to polyaniline polymerized by aniline of the formula (3-1) as a coating material for the catalyst layer in the production of the counter electrode. A cell was prepared in the same manner as described above.

[Comparative Example 10]
In the production of the counter electrode, instead of forming a catalyst layer of PEDOT by electrolytic polymerization, a dispersion obtained by mixing PEDOT, carbon black particles (particle size 23 nm) and ethanol at a weight ratio of 2:16 is used as an FTO membrane. A cell was prepared in the same manner as in Example 4 except that a catalyst layer composed of PEDOT and carbon black was formed on the surface of the conductive glass substrate by applying it to a glass substrate disposed on the surface and drying at 120 ° C. for 60 minutes. did.

[Comparative Example 11]
A cell was prepared in the same manner as in Comparative Example 10, except that in the production of the counter electrode, titanium oxide particles (particle size 200 to 500 nm) coated with ATO were used instead of the carbon black particles.

[Comparative Example 12]
In the production of the counter electrode, a cell was produced in the same manner as in Example 4 except that the porous polymer was not coated with the conductive polymer.

[Comparative Example 13]
In the production of the counter electrode, a cell was produced in the same manner as in Example 7 except that the porous polymer was not coated with the conductive polymer.

[Comparative Example 14]
In the production of the counter electrode, a cell was produced in the same manner as in Example 10 except that the porous polymer was not coated with the conductive polymer.
Each cell produced in Examples 4 to 16 and Comparative Examples 6 to 14 was evaluated in the same manner as Example 1. The results are shown in Table 2.

From the above results, it can be seen that the electrode substrate of the example in which the catalyst layer is coated on the porous membrane can obtain excellent power generation efficiency regardless of the type of the catalyst layer and the type of the porous membrane.
In Examples 4 to 6, it can be seen that the electrode substrate having a larger specific surface area improves the power generation efficiency.
In the electrode substrates of Comparative Examples 10 to 11, the conductive polymer is coated on the surface of the conductive glass, but the power generation efficiency is inferior to that of Example 4 because the coated surface does not have a porous structure.

FIG. 4A shows an SEM image obtained by observing the surface of the counter electrode of Example 9. Moreover, the SEM image which observed the surface of the porous membrane before coating the surface of the counter electrode of Example 9 with PEDOT is shown in FIG. 4B. 4A and 4B, it can be seen that PEDOT is coated along the three-dimensional porous structure on the surface of the porous membrane of FIG. 4A.

FIG. 4C shows an SEM image obtained by observing the cross section of the counter electrode of Example 9. An enlarged image of this cross section is shown in FIG. 4D. In FIG. 4C and FIG. 4D, it turns out that the continuous cell structure which a single hole connects in a porous membrane exists. In the enlarged image of FIG. 4D, the range indicated by the black broken line represents the surface (boundary) of titanium oxide coated with ATO, and the range indicated by the white broken line represents the surface (boundary) of the catalyst layer made of PEDOT. . The distance between the black broken line and the white broken line represents the thickness of the catalyst layer.

FIG. 5A shows an SEM image obtained by observing the surface of the counter electrode of Example 10. FIG. Moreover, the SEM image which observed the surface of the porous membrane before coating the surface of the counter electrode of Example 10 with PEDOT is shown in FIG. 5B. 5A and 5B, it can be seen that PEDOT is coated along the three-dimensional porous structure on the surface of the porous film of FIG. 5A.

FIG. 6A shows an SEM image obtained by observing the surface of the counter electrode of Example 7. FIG. Moreover, the SEM image which observed the surface of the porous membrane before coating the surface of the counter electrode of Example 7 with PEDOT is shown in FIG. 6B. 6A and 6B, it can be seen that PEDOT is coated along the three-dimensional porous structure on the surface of the porous film of FIG. 6A.

FIG. 7A shows an SEM image obtained by observing the surface of the counter electrode of Example 8. Moreover, the SEM image which observed the surface of the porous membrane before coating the surface of the counter electrode of Example 8 with PEDOT is shown in FIG. 7B. 7A and 7B, it can be seen that PEDOT is coated along the three-dimensional porous structure on the surface of the porous film of FIG. 7A.

FIG. 8 shows an SEM image of the surface of the counter electrode of Comparative Example 6 observed. It can be seen that a platinum film is formed flat. Moreover, the SEM image which observed the surface of the counter electrode of the comparative example 7 is shown in FIG. It can be seen that the film containing PEDOT is formed flat. Moreover, the SEM image which observed the surface of the counter electrode of the comparative example 11 is shown in FIG. Although roughness is observed on the surface of the film containing PEDOT, it can be seen that the film is formed substantially flat. It can be seen that no film structure having a three-dimensional depth is formed in the counter electrode of any of these comparative examples.

[Example 17]
A cell was produced in the same manner as in Example 9. In the counter electrode of this cell, the film thickness of the porous film made of titanium oxide particles coated with ATO was 2.2 μm. The film thickness was measured by the method of measuring the film thickness difference with a stylus type surface shape measuring instrument.

[Example 18]
In the production of the counter electrode, a cell was produced in the same manner as in Example 17 (Example 9) except that the thickness of the porous film to be formed was changed to 5.6 μm by increasing the number of screen printings.

[Example 19]
In the production of the counter electrode, a cell was produced in the same manner as in Example 17 (Example 9) except that the thickness of the porous film to be formed was changed to 10.1 μm by increasing the number of screen printings.

[Comparative Example 15]
A cell was produced in the same manner as in Comparative Example 6. In the counter electrode of this cell, the film thickness of the platinum thin film (platinum electrode) formed by the sputtering method was 20 nm. The film thickness was estimated by observing a cross-sectional image of the platinum electrode with an SEM.

[Comparative Example 16]
A cell was produced in the same manner as in Comparative Example 15 (Comparative Example 6) except that the thickness of the platinum thin film was changed to 50 nm.

[Comparative Example 17]
A cell was produced in the same manner as in Comparative Example 15 (Comparative Example 6) except that the thickness of the platinum thin film was changed to 100 nm.

[Comparative Example 18]
A cell was produced in the same manner as in Comparative Example 7. In the counter electrode of this cell, the film thickness of PEDOT formed by electrolytic polymerization was 20 nm. The film thickness was estimated by observing a cross-sectional image of the PEDOT electrode with an SEM.

[Comparative Example 19]
In the production of the counter electrode, a cell was produced in the same manner as in Comparative Example 18 (Comparative Example 7), except that the film thickness of PEDOT to be formed was changed to 40 nm by increasing the polymerization time of the electrolytic polymerization method. .

[Comparative Example 20]
In the production of the counter electrode, a cell was produced in the same manner as in Comparative Example 18 (Comparative Example 7) except that the film thickness of PEDOT to be formed was changed to 100 nm by increasing the polymerization time of the electrolytic polymerization method. .

[Comparative Example 21]
In the production of the counter electrode, a cell was produced in the same manner as in Comparative Example 18 (Comparative Example 7) except that the film thickness of the PEDOT film to be formed was changed to 200 nm by increasing the polymerization time of the electrolytic polymerization method. .
Each cell produced in Examples 17 to 19 and Comparative Examples 15 to 21 was evaluated in the same manner as Example 1. The results are shown in Table 3.

From the results of Examples 17 to 19 in the above table, it can be seen that the power generation efficiency of the cell improves as the thickness (film thickness) of the catalyst layer of the counter electrode increases. The reason is considered that the catalyst reaction area increases as the film thickness increases because the catalyst layer of the example has a three-dimensionally connected structure along the porous structure.
On the other hand, in the cells of Comparative Examples 15 to 17 using a platinum thin film as the counter electrode, the power generation efficiency hardly changes even when the film thickness of the platinum electrode is increased. The same applies to the cells of Comparative Examples 18 to 21 in which the film made of PEDOT directly formed on the surface of the conductive glass substrate is used as the counter electrode. The reason why the power generation efficiency does not change is that the catalytic reaction area does not increase even if the thickness of the counter electrode of the comparative example is increased. In addition, in the cell of the comparative example 21 which made PEDOT the film thickness of about 200 nm, the film | membrane peeled by the film | membrane intensity | strength lack.

The configurations and combinations thereof in the embodiments described above are merely examples, and additions, omissions, substitutions, and other changes can be made without departing from the spirit of the present invention. Further, the present invention is not limited by each embodiment, and is limited only by the scope of the claims.

The electrode substrate of the present invention and the dye-sensitized solar cell using the electrode substrate are widely applicable in the field of solar cells.

DESCRIPTION OF SYMBOLS 1 ... Conductive substrate, 1a ... Conductive film, 1b ... Substrate, 2 ... Porous film, 2a ... Fine particle which has electroconductivity or semiconductor characteristic, 3 ... Conductive polymer (catalyst layer), 4 ... Sealing material, DESCRIPTION OF SYMBOLS 5 ... Electrolyte solution, 6 ... Transparent substrate, 7 ... Transparent electrically conductive film, 8 ... Porous oxide semiconductor layer, 10 ... Dye-sensitized solar cell, 11 ... Photoelectrode (photoelectrode substrate), 12 ... Counter electrode (counter electrode) Substrate), 21 ... conductive substrate, 21a ... transparent conductive film, 21b ... glass substrate, 22 ... carbon material, 23 ... conductive polymer

Claims (13)

1. An electrode substrate having a conductive substrate, a porous film formed on the conductive substrate, and a catalyst layer coated on the porous film.
2. The electrode substrate according to claim 1, wherein the catalyst layer is coated along a three-dimensional structure of the porous membrane.
3. The electrode substrate according to claim 1 or 2, wherein the electrode substrate includes a continuous structure in which a plurality of single holes are connected to a porous film coated with the catalyst layer.
4. 4. The electrode substrate according to claim 3, wherein in the porous membrane coated with the catalyst layer, the number of the ream structure is larger than the number of the single holes.
5. The electrode substrate according to any one of claims 1 to 4, wherein the porous film is made of a metal or a metal compound.
6. The electrode substrate according to any one of claims 1 to 4, wherein the porous film is made of a carbon material.
7. The electrode substrate according to any one of claims 1 to 6, wherein the catalyst layer is composed of a conductive polymer.
8. The electrode substrate according to claim 7, wherein the conductive polymer is a polymer of a thiophene compound represented by the following general formula (1).
   

   

   [Wherein R ¹ and R ² are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an aryl group having 6 or 8 carbon atoms, a carboxyl group, An ester group, an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amino group, a nitro group, an azo group, a sulfo group, or a sulfonyl group is represented. When R ¹ and R ² are the alkyl group or alkoxy group, the carbon atoms at the terminals of the alkyl group or alkoxy group may be bonded to form a ring. ]
9. The electrode substrate according to claim 7, wherein the conductive polymer is a polymer of a pyrrole compound represented by the following general formula (2).
   

   

   [Wherein R ³ and R ⁴ each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an aryl group having 6 or 8 carbon atoms, a carboxyl group, An ester group, an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amino group, a nitro group, an azo group, a sulfo group, or a sulfonyl group is represented. When R ³ and R ⁴ are the alkyl group or alkoxy group, carbon atoms at the terminals of the alkyl group or alkoxy group may be bonded to form a ring. ]
10. The electrode substrate according to claim 7, wherein the conductive polymer is a polymer of an aniline compound represented by the following general formula (3).
    

    

    [Wherein R ⁵ to R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an aryl group having 6 or 8 carbon atoms, a carboxyl group, An ester group, an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amino group, a nitro group, an azo group, a sulfo group, or a sulfonyl group is represented. When R ⁵ and R ⁶ , or R ⁷ and R ⁸ are the alkyl group or alkoxy group, carbon atoms at the terminals of the alkyl group or alkoxy group may be bonded to form a ring. ]
11. The electrode substrate according to any one of claims 1 to 10, wherein the surface of the conductive substrate is in contact with the porous film.
12. The electrode substrate according to any one of claims 7 to 11, wherein the conductive polymer is coated on the porous film by an electrolytic polymerization method using the porous film as a working electrode.
13. A dye-sensitized solar cell comprising a counter electrode constituted by the electrode substrate according to any one of claims 1 to 12, a photoelectrode adsorbing a dye, and an electrolyte.
    

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