TW201424088A - Electrode substrate and dye-sensitized solar cell - Google Patents

Abstract

This invention provides an electrode substrate that comprises a conductive substrate, a porous membrane formed on the conductive substrate, and a catalytic layer coated on the porous membrane.

Description

Electrode substrate and dye-sensitized solar cell

The present invention relates to an electrode substrate which can be used as a counter electrode of a dye-sensitized solar cell and a dye-sensitized solar cell using the electrode substrate.

The present application claims priority based on Japanese Patent Application No. 2012-273719, filed on Jan.

A so-called Graetzel type system is known as a dye-sensitized solar cell (Non-Patent Document 1). When light is irradiated to the sensitizing dye adsorbed to the porous oxide semiconductor layer constituting the photoelectrode, electrons are generated. The electrons sequentially flow to the dye, the porous oxide semiconductor layer, the transparent conductive film, and an external circuit, and are extracted as a current. On the other hand, the dye which emits electrons is reduced by the redox pair in the electrolyte, and the oxidized redox pair is regenerated into a reduced body by the catalyst layer constituting the counter electrode.

As a conventional catalyst layer constituting a counter electrode of a dye-sensitized solar cell, a platinum electrode (platinum film) formed on a substrate is widely used. As a method of forming a platinum electrode, a method of applying a chloroplatinic acid solution to a substrate and heat-treating the method, vacuum vapor deposition, sputtering, or the like is known. However, since platinum is a noble metal of high price, the use of a platinum electrode has a problem of increasing the manufacturing cost of the dye-sensitized solar cell. Further, there is a problem that platinum does not have sufficient durability against I ^- ions (iodide ions) in the presence of moisture.

In order to solve this problem, a material having a new catalyst layer instead of a platinum electrode has been studied. For example, it has been disclosed that a counter electrode using a conductive polymer such as polythiophene, polyaniline or polypyrrole as a catalyst layer is applied to dye sensitization. Examples of solar cells (Non-Patent Document 2, Patent Documents 1 to 2).

However, the power generation efficiency in the case of using a catalyst layer having such a conductive polymer is significantly lower than that in the case of using a catalyst layer composed of a platinum electrode. The reason for this is that the conductivity of the conductive polymer and the reducing ability (I ₃ ^- → I ^- reducing ability) as a catalyst are lower than those of platinum.

The reducing power of the catalyst layer is determined by the "catalytic activity" × "specific surface area of the catalyst layer", and the catalytic activity of the conductive polymer is lower than that of platinum. Therefore, when the catalyst layer composed of the conductive polymer has a specific surface area similar to that of the platinum electrode, the catalytic ability of the catalyst layer composed of the conductive polymer is inferior to that of the platinum electrode. Therefore, it has also been disclosed that a carbon material such as a carbon nanotube or a carbon particle is mixed by a catalyst layer made of a conductive polymer to improve the specific surface area or conductivity of the catalyst layer, thereby improving the reducing power of the catalyst layer. Method (Patent Documents 3 to 4). For example, the composition of a conventional catalyst layer is as shown in the schematic diagram of FIG. The catalyst layer of FIG. 1 has a structure in which a film of a conductive polymer 23 encapsulating the carbon material 22 is formed on the conductive substrate 21.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2003-313317

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2003-317814

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2006-147411

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2011-14411

[Non-patent literature]

[Non-Patent Document 1] Nature, Vol. 353, p. 737, 1991

[Non-Patent Document 2] Electrochemistry 71, No. 11 (2003) 944-946

However, even in the case of using the catalyst layer manufactured by the methods of Patent Documents 3 to 4, since the specific surface area of the catalyst layer is insufficient, the reducing ability of the catalyst layer is not equal to or higher than 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 disordered state, the structure (porosity) of the catalyst layer is low in controllability, and therefore, each batch is worried. The difference in the reducing power of the catalyst layer or the difference in film strength. Further, in the catalyst layer, the carbon materials are not directly in contact with each other and are bonded via the conductive polymer, and further, a region in which a plurality of carbon materials are not in direct contact with the conductive substrate is formed, so that the electric resistance is increased and the conductivity is not as good as platinum. electrode. Therefore, improvement in 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 have been sought.

The present invention has been made in view of the above circumstances, and an object of the invention is to provide an electrode substrate and a dye-sensitized solar cell which can achieve a power generation efficiency equivalent to or higher than that of a platinum electrode used as a counter electrode of a dye-sensitized solar cell.

(1) An electrode substrate having a conductive substrate and film forming the above conductivity a porous film on the substrate and a catalyst layer applied to the porous film.

(2) The electrode substrate according to the above (1), wherein the catalyst layer is applied along a three-dimensional structure of the porous film.

(3) The electrode substrate according to the above (1) or (2), wherein the porous film coated with the catalyst layer contains a plurality of single pores connected to each other.

(4) The electrode substrate according to the above (3), wherein the number of the unitary structures is larger than the number of the single holes in the porous film coated with the catalyst layer.

The electrode substrate according to any one of the above aspects, wherein the porous film is made of a metal or a metal compound.

The electrode substrate according to any one of the above aspects, wherein the porous film is made of a carbon material.

(7) The electrode substrate according to any one of the above-mentioned (1), wherein the catalyst layer is made of a conductive polymer.

(8) The electrode substrate according to the above (7), wherein the conductive polymer is a polymer of a thiophene compound represented by the following formula (1).

Wherein R ¹ and R ² each independently represent 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 or an ester; Any of a group, an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amine group, a nitro group, an azo group, a sulfo group, or a sulfonyl group. When R ¹ and R ² are the above alkyl group or alkoxy group, the carbon atom at the terminal of the above alkyl group or alkoxy group may be bonded to each other to form a ring].

(9) The electrode substrate according to the above (7), wherein the conductive polymer is a polymer of a pyrrole compound represented by the following formula (2).

Wherein R ³ and R ⁴ each independently represent 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 or an ester; A group, an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amine group, a nitro group, an azo group, a sulfo group or a sulfonyl group. When R ³ and R ⁴ are the above alkyl group or alkoxy group, the carbon atom at the terminal of the above alkyl group or alkoxy group may be bonded to each other to form a ring].

(10) The electrode substrate according to the above (7), wherein the conductive polymer is a polymer of an aniline compound represented by the following formula (3).

In the formula, R ⁵ to R ⁸ each independently represent 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, or a carboxyl group. Ester group, aldehyde group, hydroxyl group, halogen atom, cyano group, amine group, nitro group, azo group, sulfo group or sulfonyl group. When R ⁵ and R ⁶ or R ⁷ and R ⁸ are the above alkyl group or alkoxy group, the carbon atom at the terminal of the alkyl group or the alkoxy group may be bonded to each other to form a ring].

The electrode substrate according to any one of the above aspects, wherein the surface of the conductive substrate is in contact with the porous film.

(12) The electrode substrate according to any one of the above aspects, wherein the conductive polymer is applied to the porous film via an electrolytic polymerization method using the porous film as a working electrode. .

(13) A dye-sensitized solar cell comprising the counter electrode comprising the electrode substrate according to any one of the above (1) to (12), a photoelectrode for adsorbing a dye, and an electrolytic solution.

In the electrode substrate of the present invention, a porous film having a wide specific surface area is coated with a catalyst layer such as a conductive polymer, and therefore has a wide specific surface area which functions as a catalyst. Further, when the electrode substrate of the present invention has a structure in which a catalyst layer such as a conductive polymer is applied to a three-dimensional structure having a porous film having a wide specific surface area, it has a wider function as a catalyst. Specific surface area. As a result, the reducing power of the catalyst determined by the "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.

Further, in the electrode substrate of the present invention, the electrical contact portion between the conductive substrate and the porous film and the electrical contact portion between the porous film and the catalyst layer such as the conductive polymer are uniformly and surely formed, respectively. Excellent in electrical 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.

Further, in the electrode substrate of the present invention, the three-dimensional structure of the porous film formed on the conductive substrate functions as a supporting member for coating the catalyst layer such as a conductive polymer, and thus the phase The structural strength is improved as compared with the conventional one (the film of the conductive polymer alone (the catalyst layer alone)). As a result, the manufacturing yield in the case of producing the dye-sensitized solar cell using the electrode substrate of the present invention can be improved, and even when the use environment of the dye-sensitized solar cell is an environment in which an external force is applied to the opposite electrode, It can also provide excellent durability to the above dye-sensitized solar cells.

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

1‧‧‧Electrically conductive substrate

1a‧‧‧ Conductive film

1b‧‧‧Substrate

2‧‧‧Porous membrane

2a‧‧‧Microparticles with conductive or semiconducting properties

3‧‧‧ Conductive polymer (catalyst layer)

4‧‧‧ Sealing material

5‧‧‧ electrolyte

6‧‧‧Transparent substrate

7‧‧‧Transparent conductive film

8‧‧‧Porous oxide semiconductor layer

10‧‧‧Dye-sensitized solar cells

11‧‧‧Photoelectrode (photoelectrode substrate)

12‧‧‧ Counter electrode (opposite electrode substrate)

21‧‧‧Electrically conductive substrate

21a‧‧‧Transparent conductive film

21b‧‧‧ glass substrate

22‧‧‧Carbon materials

23‧‧‧ Conductive polymer

Figure 1 is a schematic cross-sectional view of a conventional counter electrode.

Fig. 2 is a schematic cross-sectional view showing an electrode substrate (opposing electrode) of the first embodiment.

Fig. 3 is a schematic cross-sectional view showing the dye-sensitized solar cell of the second embodiment.

Fig. 4A is an SEM image of the surface of the counter electrode of Example 9.

4B is an SEM image of the surface of the porous film before PEDOT coating on the surface of the counter electrode of Example 9.

4C is an SEM image of a cross section of the counter electrode of Example 9.

Figure 4D is an enlarged image of the section of Figure 4C.

Fig. 5A is an SEM image of the surface of the counter electrode of Example 10.

Fig. 5B is an SEM image of the surface of the porous film before PEDOT coating on the surface of the counter electrode of Example 10.

Fig. 6A is an SEM image of the surface of the counter electrode of Example 7.

Fig. 6B is an SEM image of the surface of the porous film before PEDOT coating on the surface of the counter electrode of Example 7.

Fig. 7A is an SEM image of the surface of the counter electrode of Example 8.

Fig. 7B is an SEM image of the surface of the porous film before PEDOT coating on the surface of the counter electrode of Example 8.

Fig. 8 is a view showing an SEM image of the surface of the counter electrode of Comparative Example 6.

Fig. 9 is a view showing an SEM image of the surface of the counter electrode of Comparative Example 7.

Fig. 10 is a view showing an SEM image of the surface of the 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 the embodiments.

Electrode Substrate

As shown in FIG. 2, the electrode substrate according to the first embodiment of the present invention includes a porous film 2 formed on a conductive substrate 1. The porous film 2 has a hole that communicates three-dimensionally with respect to the outside not only on the surface facing the outside but also on the inside. Preferably, the porous membrane 2 comprises a unitary structure in which a plurality of single independent pores (single pores) are joined. In the porous membrane 2, it is preferred that the number of the unitary structures (the ratio of existence) is larger than the number of the single pores (the ratio of existence).

In the porous membrane 2 having a continuous structure, the redox pair contained in the electrolytic solution can be sufficiently permeated from the surface to the inside, which is preferable. Further, in the porous membrane 2 having a continuous structure, the area of the surface of the porous membrane in contact with the electrolytic solution (the surface area where the electrochemical reaction occurs) is increased, and as a result, the reduction reaction is more efficiently promoted.

A catalyst layer 3 such as a conductive polymer is applied (coated) on the surface of the porous film 2. Here, The surface of the porous membrane 2 also contains a surface of a porous structure that communicates with the outside. Further, it is preferable to apply the catalyst layer 3 along the three-dimensional porous film structure formed by the above-described cell structure of the porous film 2. By applying the catalyst layer 3 to the surface (inner wall surface) of the three-dimensional porous structure in this manner, the specific surface area of the catalytic activity of the catalyst layer 3 is significantly increased as compared with the conventional one.

In the electrode substrate of the first embodiment, since the porous film 2 has a three-dimensional structure, the electric resistance inside the porous film is lowered, and the electrical conductivity is excellent. Further, 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 uniformly and surely formed. Further, the porous film 2 is in contact with the coating layer of the conductive polymer 3 (catalyst layer 3) in almost the entire region of the region where the porous film 2 is not in contact with the conductive substrate 1, so that the porous film 2 is homogeneously and surely formed. The electrical contact portion between the plasma film 2 and the conductive polymer 3 (the catalyst layer 3). Since the electrical contact portion is formed homogeneously and surely, the electrode substrate of the first embodiment is excellent in conductivity.

(conductive substrate)

The conductive substrate 1 is configured by imparting a conductive conductive film 1a and a substrate 1b.

The type of the conductive film is not particularly limited, and for example, a transparent conductive film or a metal film can be applied.

The type of the transparent conductive film is not particularly limited, and a transparent conductive film used in a conventionally known dye-sensitized solar cell can be applied, and examples thereof include a film composed of a metal oxide.

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 doping. Zinc oxide (AZO), zinc oxide, tin oxide, and the like. Among these, ITO which is smaller in specific resistance and higher in electrical conductivity, and FTO which is excellent in heat resistance and weather resistance are particularly preferable.

Examples of the metal film include gold (Au), platinum (Pt), silver (Ag), copper (Cu), and chromium. (Cr), tungsten (W), aluminum (Al), magnesium (Mg), titanium (Ti), nickel (Ni), manganese (Mn), zinc (Zn), iron (Fe) and alloys thereof, etc. It is Au, Pt, Cr, Ti, and Ni which are excellent in electrical conductivity and weather resistance.

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.

In the conductive substrate 1 of the first embodiment, since the surface of the substrate is electrically conductive, the conductive film is not necessarily required. Examples of the conductive substrate 1 include a substrate made of a metal or a substrate made of a conductive resin. Further, the conductive substrate 1 constituting the electrode substrate of the first embodiment contains a conductive film or a conductive sheet having flexibility. When a conductive film or a conductive sheet is used as the conductive substrate 1, the conductive substrate 1 can be replaced with a conductive substrate.

(porous membrane)

The porous film 2 of the first embodiment is a film (layer) having a three-dimensional porous structure, and its structure includes a structure in which the fine particles 2a are joined, a single structure formed by a phase separation structure, or a structure in which a nano mesh is laminated. Wait.

The material constituting the fine particles 2a is not particularly limited as long as it has conductivity or semiconductor characteristics, and from the viewpoint of obtaining a porous film having high structural strength, titanium, platinum, gold, silver, copper, aluminum, or preferably Metals such as cobalt, iron, magnesium, nickel, zinc, or titanium oxide or tin oxide, zinc oxide, gallium oxide, indium oxide, aluminum oxide, chromium oxide, cobalt oxide, copper oxide, iron oxide, titanium carbide, vanadium carbide, carbonization Metal compounds such as tungsten, titanium nitride, and vanadium nitride, or carbon materials such as carbon black or carbon nanotubes, carbon fibers, activated carbon, and graphite.

Among them, from the viewpoint of low cost and mass production, it is preferred to use a fine particle composed of a metal compound containing a metal oxide or a carbon material. As a material constituting the above fine particles, Particularly preferred are titanium oxide, tin oxide, zinc oxide, and carbon black.

The shape of the fine particles 2a is not particularly limited, and examples thereof include spherical, needle-shaped, fibrous, bag-shaped, and urchin-shaped fine particles.

The preferred range of the primary particle diameter of the spherical fine particles varies depending on the method of forming the fine particles on the conductive substrate 1, and is usually preferably from 1 nm to 500 μm, more preferably from 1 nm to 250 μm. Preferably, it is 5 nm to 100 μm, particularly preferably 10 nm to 10 μm, and most preferably 10 nm to 1 μm. In addition, as a method of obtaining the primary particle diameter of the fine particles, for example, a method of determining the peak value of the distribution of the volume average diameter obtained by measurement by a laser diffraction type particle size distribution measuring apparatus, or A method of averaging the long diameters of a plurality of fine particles by SEM observation. The primary particle diameter of the above fine particles is preferably measured by the above SEM observation.

The preferred primary particle diameter of the acicular, fibrous or bag-like fine particles differs depending on the method of forming the fine particles on the conductive substrate 1, and is usually in the long axis direction, preferably 1 nm. 500 μm, more preferably 1 nm to 250 μm, further preferably 5 nm to 100 μm, particularly preferably 10 nm to 10 μm, and most preferably 10 nm to 5 μm. The direction of the minor axis is preferably from 1 nm to 500 μm, more preferably from 1 nm to 250 μm, further preferably from 5 nm to 100 μm, particularly preferably from 10 nm to 10 μm, and most preferably from 10 nm to 1 μm.

The fine particles constituting the porous membrane 2 may be used singly or in combination of two or more.

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

The porosity (void ratio) of the porous film 2 is preferably larger in order to increase the specific surface area. However, if the porosity is too large, the structural strength of the porous film 2 may be weak. In view of this, the porosity of the porous membrane 2 is preferably from 50 to 80%. The porosity (void ratio) 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 film 2 in which the catalyst layer 3 is applied is measured by a gas adsorption method, and is preferably 0.1 m ² /g or more, more preferably 1 m ² /g or more, and further Good is 3m ² /g or more. By being 3 m ² /g or more, the contact efficiency between the applied catalyst layer 3 and the electrolyte can be improved, and the electrolyte can be efficiently reduced. That is, the catalyst efficiency can be further improved. Further, the upper limit of the specific surface area is not particularly limited, and for example, 300 m ² /g can be set as the upper limit.

The method of 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 can produce a porous film having an appropriate porosity. A well-known film forming method is known. For example, a paste containing fine particles 2a having conductivity or semiconductor characteristics and a known binder resin can be applied onto the conductive substrate 1 and further calcined to form a film. Here, examples of the fine particles 2a include conductive fine particles or metal oxide fine particles.

In addition, the fine particles 2a having conductivity or semiconductor characteristics are blown onto the conductive substrate 1 by the carrier gas, and the fine particles 2a having conductivity or semiconductor characteristics are bonded to the conductive substrate 1 to obtain conductivity or semiconductor characteristics. A porous film in which the microparticles 2a are bonded to each other. As a method of forming the porous film 2 by blowing the fine particles 2a having conductivity or semiconductor characteristics, for example, an aerosol deposition method (AD method) can be mentioned.

(catalyst layer)

In the electrode substrate of the first embodiment, as a material constituting the catalyst layer 3 applied along the three-dimensional structure of the porous film 2, a conductive material capable of reducing a redox pair of a known electrolyte is used. There are no special restrictions. Specifically, for example, in addition to the conductive polymer described below, a titanium compound such as platinum, a conductive carbon material, titanium carbide TiC or titanium nitride TiN, vanadium oxide V ₂ O ₃ or vanadium nitride VN may be mentioned. Compounds, etc.

The material constituting the catalyst layer 3 may be one type or two or more types.

The method of forming the catalyst layer 3 by a catalyst-active metal such as platinum is not particularly limited as long as it forms a layer of platinum along the surface of the three-dimensional structure of the porous film 2. Specific examples thereof include electrolytic plating using the conductivity of the porous film 2 and the conductive substrate 1, electroless plating, and the like.

The lower limit of the thickness of the catalyst layer 3 applied to the porous film 2 may vary depending on the material of the catalyst layer 3, and is usually preferably 0.01 nm or more, more preferably 0.1 nm or more, and still more preferably 1 nm. the above. Catalyst activity can be sufficiently obtained by being 0.01 nm or more. The upper limit of the thickness of the catalyst layer 3 is not particularly limited, and is preferably a thickness that does not reach the extent that the porous structure of the porous membrane 2 is completely filled. Specifically, it is more preferably 1000 nm or less.

The thickness of the catalyst layer 3 exemplified herein means a catalyst layer formed on the surface (outer surface) of the porous film 2 facing the outside (that is, the surface recognized when the porous film 2 is observed from above) 3 thickness. As a method of inspecting the thickness of the catalyst layer 3 formed on the outer surface, it is preferable to observe the cross section of the porous film 2 on which the catalyst layer 3 is formed by an electron microscope.

Hereinafter, a case where a conductive polymer is used as a material constituting the catalyst layer 3 will be described.

(conductive polymer)

The electrode substrate of the first embodiment is coated with a conductive polymer 3 (catalyst layer 3) The porous film 2 constitutes a catalyst layer. A layer of the conductive polymer 3 is formed on the surface of the porous film 2 by the above coating.

The type of the conductive polymer is not particularly limited, and a known conductive polymer can be used. For example, a conductive polymer obtained by polymerizing a thiophene compound represented by the following formula (1) can be used.

Wherein R ¹ and R ² each independently represent 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 or an ester; Any of a group, an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amine group, a nitro group, an azo group, a sulfo group, or a sulfonyl group. When R ¹ and R ² are the above alkyl group or alkoxy group, the carbon atom at the terminal of the above alkyl group or alkoxy group may be bonded to each other to form a ring].

The above alkyl group is preferably a linear or branched alkyl group, more preferably a linear alkyl group.

The number of carbon atoms of the above alkyl group is preferably from 1 to 8, more preferably from 1 to 5, still more preferably from 1 to 3.

The alkoxy group is preferably a methoxy group, an ethoxy group, a propoxy group or a butoxy group, more preferably a methoxy group or an ethoxy group.

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 above alkyl group or alkoxy group, the carbon of the above alkyl group or alkoxy group may be removed in addition to one hydrogen atom bonded to a carbon atom at the terminal of the above alkyl group or alkoxy group. The atoms are bonded to each other to form a ring.

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

In addition, as the conductive polymer, for example, a conductive polymer obtained by polymerizing a pyrrole compound represented by the following formula (2) can be mentioned.

Wherein R ³ and R ⁴ each independently represent 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 or an ester; Any of a group, an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amine group, a nitro group, an azo group, a sulfo group, or a sulfonyl group. When R ³ and R ⁴ are the above alkyl group or alkoxy group, the carbon atom at the terminal of the above alkyl group or alkoxy group may be bonded to each other to form a ring].

The above alkyl group is preferably a linear or branched alkyl group, more preferably a linear alkyl group. The number of carbon atoms of the above alkyl group is preferably from 1 to 8, more preferably from 1 to 5, still more preferably from 1 to 3.

The alkoxy group is preferably a methoxy group, an ethoxy group, a propoxy group or a butoxy group, more preferably a methoxy group or an ethoxy group.

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 above alkyl group or alkoxy group, the carbon of the above alkyl group or alkoxy group may be removed in addition to one hydrogen atom bonded to a carbon atom at the terminal of the above alkyl group or alkoxy group. The atoms are bonded to each other to form a ring.

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

In addition, as the conductive polymer, for example, a conductive polymer obtained by polymerizing an aniline compound represented by the following formula (3) can be mentioned.

In the formula, R ⁵ to R ⁸ each independently represent 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, and an ester. Any of a group, an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amine group, a nitro group, an azo group, a sulfo group, or a sulfonyl group. When R ⁵ and R ⁶ or R ⁷ and R ⁸ are the above alkyl group or alkoxy group, the carbon atom at the terminal of the alkyl group or the alkoxy group may be bonded to each other to form a ring].

The above alkyl group is preferably a linear or branched alkyl group, more preferably a linear alkyl group. The number of carbon atoms of the above alkyl group is preferably from 1 to 8, more preferably from 1 to 5, still more preferably from 1 to 3.

The alkoxy group is preferably a methoxy group, an ethoxy group, a propoxy group or a butoxy group, more preferably a methoxy group or an ethoxy group.

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 above alkyl group or alkoxy group, the carbon of the above alkyl group or alkoxy group may be removed in addition to one hydrogen atom bonded to a carbon atom at the terminal of the above alkyl group or alkoxy group. The atoms are bonded to each other to form a ring.

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

The method of applying the conductive polymer to the porous film 2 constituting the electrode substrate of the first embodiment is not particularly limited, and examples thereof include the following methods (a) to (d).

(a) immersing the porous membrane in a solution containing an unpolymerized monomer constituting the conductive polymer, using the porous membrane as a working electrode, performing electrolytic polymerization of the monomer, and synthesizing conductivity on the porous membrane The polymer is coated by this.

(b) Coating is carried out by applying a solution containing a prepolymerized conductive polymer to a porous film and volatilizing the solvent.

(c) Applying a mixture containing a prepolymerized conductive polymer and another known binder resin to a porous film, and curing the mixture to coat the mixture.

(d) by immersing the porous membrane in a solution containing an unpolymerized monomer constituting the conductive polymer, adding a known oxidizing agent (for example, ferric chloride or the like) to the solution to synthesize conductivity on the porous membrane The polymer is coated by this.

Among the above methods (a) to (c), the method (a) or (b) is preferred, and the method (a) is more preferred. In the method (c), since the binder resin remains on the porous film, the electrical contact between the conductive polymer and the porous film is weak. Regarding the method (d), there is a possibility that the conductive polymer is superpolymerized, and as a result, there is a void in the inside of the porous film. On the other hand, in the methods (a) and (b), since the porous film is in direct contact with the conductive polymer, electrical contact between the two can be sufficiently obtained. Further, according to the method (a), a polymerization reaction occurs also in the pores (porous structure) inside the porous membrane (that is, inside the three-dimensional structure of the porous membrane), so that the inner wall surface constituting the pores is The conductive polymer can also be sufficiently coated. Therefore, it is better to be the method of (a).

The molar concentration of the conductive polymer to which the porous film 2 is applied is preferably from 0.00001 to 1 mol/cm ³ , more preferably from 0.0001 to 0.1 mol/cm ³ , from the viewpoint of improving the reducing ability of the catalyst. It is preferably 0.001 to 0.01 mol/cm ³ .

In the electrode substrate of the first embodiment, the specific surface area of the region (catalyst layer) functioning as a catalyst is increased, and the conductivity and the structural strength are improved. Therefore, the electrode substrate is used as a pair of dye-sensitized solar cells. In the case of an electrode, it contributes greatly to an increase in power generation efficiency.

Hereinafter, a dye-sensitized solar cell using the electrode of the first embodiment will be described.

Dye Sensitized Solar Cell

A dye-sensitized solar cell according to a second embodiment of the present invention includes the electrode substrate of the first embodiment as a counter electrode (counter electrode substrate), a photoelectrode (photoelectrode substrate) that adsorbs a dye, and an electrolyte solution. As an example of such a dye-sensitized solar cell, the dye-sensitized solar cell 10 shown in Fig. 3 can be cited.

The dye-sensitized solar cell 10 has 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 member 4.

(photoelectrode)

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

The substrate (substrate) constituting the photoelectrode 11 is not limited to glass production, and is not particularly limited as long as it is a substrate having visible light transmittance. For example, a substrate or a film or a sheet made of a transparent resin may be mentioned in addition to the glass substrate.

As the glass, a glass having a visible light transmittance is preferable, and examples thereof include soda lime glass, quartz glass, borosilicate glass, Vico glass, alkali-free glass, blue plate glass, and white glass.

The resin (plastic) is preferably a resin having visible light transmittance, and examples thereof include polyacrylic acid, polycarbonate, polyester, polyimine, polystyrene, polyvinyl chloride, and polyamine. Among these, polyester, especially polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), is widely produced and used as a transparent heat-resistant film. Made thin and light In view of the flexible dye-sensitized solar cell, the substrate is preferably a transparent substrate made of plastic, more preferably a PET or PEN film.

As the oxide semiconductor constituting the porous oxide semiconductor layer 8, a conventionally known material can be applied, and a material which can adsorb the sensitizing dye can be used. For example, titanium oxide, zinc oxide, barium titanate, etc. are mentioned.

When the porous oxide semiconductor layer 8 (porous layer) is formed of fine particles of an oxide semiconductor, the porous layer may be a porous layer formed by firing a known paste containing the fine particles on the substrate. . Further, a porous layer formed by blowing the fine particles onto the substrate by a carrier gas, bonding the fine particles to the substrate, and joining the fine particles to each other may be applied. As a method of forming a porous layer by blowing fine particles, an aerosol deposition method (AD method) can be exemplified.

The preferred range of the primary particle diameter of the fine particles is preferably from 1 nm to 500 μm, more preferably from 1 nm to 250 μm, even more preferably from 5 nm, depending on the method of forming the fine particles on the substrate. ~100μm, particularly preferably 10nm~10μm. In addition, as a method of obtaining the primary particle diameter of the fine particles, for example, a method of determining the peak value of the distribution of the volume average diameter obtained by measurement by a laser diffraction type particle size distribution measuring apparatus, or A method of averaging the long diameters of a plurality of fine particles by SEM observation. The primary particle diameter of the above fine particles is preferably measured by the above SEM observation.

[electrolyte]

The electrolyte 5 can be applied to an electrolyte used in a previously known dye-sensitized solar cell.

In the electrolytic solution 5, a redox pair (electrolyte) is dissolved. Redox pairs can be applied to previously known redox couples. Furthermore, in the electrolyte 5, it is possible not to deviate from the gist of the present invention. Within the scope, it contains other additives such as fillers or tackifiers.

Examples of the redox pair include a combination of an iodine molecule and an iodide, or a combination of a bromine molecule and a bromine compound.

Examples of the iodide include a metal iodide such as sodium iodide (NaI) or potassium iodide (KI), or an iodide salt such as a tetraalkylammonium iodide, a pyridinium iodide or an imidazolium iodide as a preferred iodide.

The bromine compound may, for example, be a metal bromide such as sodium bromide (NaBr) or potassium bromide (KBr) or a bromine salt such as a tetraalkylammonium bromide, a pyridinium bromide or an imidazolium bromide as a preferred bromine. Compound.

The concentration of the above 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, in the case where iodine is added to the solvent of the electrolytic solution 5, the preferred iodine concentration is 0.01 to 1 mol/L.

Instead of the electrolytic solution 5, an electrolyte layer (solid electrolyte layer) may also be applied. The electrolyte layer has the same function as the electrolytic solution 5, and is in any of a gel state or a solid state. As the electrolyte layer, for example, an electrolyte layer obtained by adding a gelling agent or a tackifier to the electrolytic solution 5, and removing the solvent as needed, thereby gelling or solidifying the electrolytic solution 5 can be used. In the case of using a gel-like or solid electrolyte layer, no electrolyte leaks from the dye-sensitized solar cell 10.

The electrolyte solution 5 or the above electrolyte layer may also contain a previously known conductive polymer.

As the sealing material, a member capable of holding the electrolytic solution inside the battery unit is preferable. As such a sealing material, for example, a synthetic resin such as a conventionally known thermoplastic resin or thermosetting resin can be applied.

(opposite electrode)

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

(Manufacturing method of dye-sensitized solar cell)

The dye-sensitized solar cell of the second embodiment can be produced by a usual method in addition to the electrode substrate (counter electrode 12) of the first embodiment.

Since the coating layer of the conductive polymer (catalyst layer) which is the electrode substrate of the first embodiment of the counter electrode 12 is supported by the porous film, it has high structural strength. Therefore, when the coating tool or the like is brought into contact with the coating layer at the time of manufacture, the damage of the coating layer is also reduced. Therefore, by using the electrode substrate of the first embodiment as a counter electrode, the manufacturing yield of the dye-sensitized solar cell of the second embodiment can be improved.

[Examples]

Hereinafter, the present invention will be described in further detail by way of examples, but the invention is not limited by the 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 rosin. As a transparent conductive substrate, a glass substrate having a surface resistance of 10 ohms (Ω) of an FTO film was used, and the paste was applied onto an FTO film by a screen printing method at an area of 4 mm × 4 mm, and then in an air atmosphere. The porous oxide semiconductor layer (transparent layer) was formed on the transparent conductive film by calcination at 500 ° C for 30 minutes.

(dye adsorption)

The sensitizing dye N719 was dissolved in a dye solution of 1:1 mixture of acetonitrile and third butanol at a concentration of 0.3 mM, and the substrate on which the porous oxide semiconductor layer was formed was immersed for 20 hours. This causes the sensitizing dye to be adsorbed to the porous oxide semiconductor layer of the photoelectrode.

(production 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 rosin alcohol. As a transparent conductive substrate, a glass substrate having a surface resistance of 10 ohms (Ω) of an FTO film was used, and the paste was applied onto an FTO film by a screen printing method at an area of 4 mm × 4 mm, and then in an air atmosphere. After calcination at 500 ° C for 30 minutes, a porous film of titanium oxide (thickness: 1.5 μm) was formed on the transparent conductive film. Since the titanium oxide particles constituting the porous film thus formed are in direct contact with the FTO film, the conductivity between the porous film and the FTO film is excellent.

Then, the conductive polymer is applied to the porous film by electrolytic polymerization. The porous film and the FTO film were used as the working electrode, and a platinum wire was used as a counter electrode, and an Ag/Ag ⁺ electrode was used as a reference electrode to carry out electrolytic polymerization of the conductive polymer. In electrolytic polymerization, it contains 10 ^-2 M EDOT (3,4-extended ethylenedioxythiophene: a compound represented by the above formula (1-1)), 10 ^-1 M of LiTFSI (bistrifluoromethanesulfonate) In the acetonitrile solution of lithium imide), the working electrode, the counter electrode, and the reference electrode were immersed, and a constant potential device (manufactured by IVIUM) was used, and a voltage was applied at 1.2 V for 40 seconds to form a conductive polymer on the surface of the porous film ( PEDOT: TFSI). That is, the catalyst layer 3 (layer of the above-mentioned conductive polymer) having a three-dimensional structure along the porous film as schematically shown in Fig. 2 can be formed.

(Evaluation of film strength)

The prepared counter electrode was immersed in ethanol, and after 5 minutes of stimulation with ultrasonic waves (oscillation frequency of 42 kHz), the surface of the porous film coated with the conductive polymer of the counter electrode was observed, thereby evaluating the film. strength. The evaluation was carried out in the following two stages. The results are shown in Table 1.

Good (A): almost no peeling or damage was observed.

Poor (B): Peeling or damage can be seen to the extent that it cannot be ignored.

(Battery assembly and power generation performance evaluation)

The counter electrode and the photoelectrode formed by the above method are separated by sandwiching a resin spacer (separator) having a thickness of 30 μm, and an electrolyte solution is injected between the electrodes to assemble a dye-sensitized solar cell ( battery). As the electrolytic solution, 0.03 M of iodine, 0.6 M of 1,3-dimethyl-2-propylimidazolium iodide, 0.10 M of lithium iodide, and 0.5 M of a third butylpyridine were dissolved in acetonitrile as a solvent. The electrolyte.

As the power generation performance of the produced battery, the photoelectric conversion efficiency η, the short-circuit current Isc, the open circuit voltage Voc, and the fill factor FF were evaluated by a solar simulator (AM 1.5). The results are shown in Table 1.

[Embodiment 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 Φ 23 nm), and the power generation performance was evaluated. The results are shown in Table 1.

[Example 3]

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 carbon black (particle diameter Φ 23 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 film was formed on a glass substrate by a sputtering method was used as a counter electrode, and power generation performance was evaluated. The results are shown in Table 1.

[Comparative Example 2]

A glass substrate having an FTO film similar to that of Example 1 was used as a working electrode, and electrolytic polymerization was carried out in the same manner as in Example 1, and a conductive polymer was formed on the FTO film to prepare a counter electrode.

A dye-sensitized solar cell was produced in the same manner as in Example 1 except for the counter electrode, and evaluation of power generation performance was performed. The results are shown in Table 1.

[Comparative Example 3]

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

[Comparative Example 5]

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

As is apparent from the results of Table 1, the photoelectric conversion efficiency (power generation efficiency) η of Examples 1 to 3 of the present invention has the same performance as Comparative Examples 1 to 5 or higher.

[Example 4]

In the production of the photoelectrode, a reflective layer composed of titanium oxide particles having a particle diameter of 400 nm was laminated on a porous oxide semiconductor layer (transparent layer) (film thickness: 8 μm) formed in the same manner as in Example 1. A battery (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.

In the same manner as in the case of forming the above-mentioned transparent layer, the paste is printed with a paste composed of titanium oxide (particle diameter Φ400 nm) of 19% by mass, ethylcellulose 9% by mass, and rosinol 72% by mass. After being over the above transparent layer, it was calcined at 500 ° C, thereby being formed.

Here, the transparent layer and the titanium oxide contained in the reflective layer have different particle diameters. The transparent layer may be replaced by a first layer, and the reflective layer may be replaced by a second layer.

Further, the adsorption of the dye was carried out in the same manner as in Example 1 after the first layer and the second layer were laminated and fired.

[Example 5]

A battery was fabricated in the same manner as in Example 4 except that the titanium oxide particles having a particle diameter of 19 nm were changed to titanium oxide particles having a particle diameter of 30 nm in the production of the counter electrode.

[Embodiment 6]

A battery was fabricated in the same manner as in Example 4 except that the titanium oxide particles having a particle diameter of 19 nm were changed to titanium oxide particles having a particle diameter of 200 nm in the production of the counter electrode.

[Embodiment 7]

A battery was fabricated 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 (antimony tin oxide) particles having a particle diameter of 10 to 30 nm in the production of the counter electrode.

[Embodiment 8]

In the production of the counter electrode, 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-like particles having a major axis diameter of 200 to 2000 nm and a short-axis particle diameter of 10 to 20 nm. battery.

[Embodiment 9]

In the production of the counter electrode, a battery was produced in the same manner as in Example 4 except that the titanium oxide particles having a particle diameter of 19 nm were changed to the titanium oxide particles coated with ATO having a particle diameter of 200 to 500 nm.

[Embodiment 10]

A battery was fabricated in the same manner as in Example 4 except that the titanium oxide particles having a particle diameter of 19 nm were changed to carbon black particles having a particle diameter of 23 nm in the production of the counter electrode.

[Example 11]

In the fabrication of the counter electrode, except for the porous material formed by the titanium oxide particles having a particle diameter of 19 nm A battery was fabricated in the same manner as in Example 4 except that the film was changed to a nickel mesh having a mesh size of 8 μm, a wire diameter of 8 μm, and a thickness of 3 μm.

[Embodiment 12]

In the production of the counter electrode, the PEDOT obtained by polymerizing the EDOT of the above formula (1-1) is changed to the polypyrrole obtained by polymerizing the pyrrole of the above formula (2-2) as a coating material for the catalyst layer. A battery was fabricated in the same manner as in Example 10 except for the above.

[Example 13]

In the production of the counter electrode, the PEDOT obtained by polymerizing the EDOT of the above formula (1-1) is changed to the polyaniline obtained by polymerizing the aniline of the above formula (3-1). A battery was fabricated in the same manner as in Example 10 except for the above.

[Embodiment 14]

In the fabrication of the counter electrode, instead of forming a catalyst layer of PEDOT by electrolytic polymerization, the porous membrane is immersed in a 2-propanol solution of 10 mM chloroplatinic acid, and then calcined at 450 ° C to be porous. A battery was fabricated in the same manner as in Example 4 except that a catalyst layer made of platinum was formed on the surface of the plasma film.

[Example 15]

A battery was fabricated in the same manner as in Example 14 except that the titanium oxide particles having a particle diameter of 19 nm were changed to ATO (antimony tin oxide) particles having a particle diameter of 10 to 30 nm in the production of the counter electrode.

[Example 16]

A battery was fabricated in the same manner as in Example 14 except that the titanium oxide particles having a particle diameter of 19 nm were changed to carbon black particles having a particle diameter of 23 nm in the production of the counter electrode.

[Comparative Example 6]

In the production of the photoelectrode, a reflective layer composed of titanium oxide particles having a particle diameter of 400 nm was laminated on a porous oxide semiconductor layer (transparent layer) (thickness: 8 μm) formed in the same manner as in Comparative Example 1. (The film thickness was 4 μm), and a battery was produced in the same manner as in Comparative Example 1, except that the dye was adsorbed on the transparent layer and the reflective layer. The above reflective layer was formed in the same manner as in Example 4.

[Comparative Example 7]

In the production of the photoelectrode, a reflective layer composed of titanium oxide particles having a particle diameter of 400 nm was laminated on a porous oxide semiconductor layer (transparent layer) (film thickness: 8 μm) formed in the same manner as in Comparative Example 2. (The film thickness was 4 μm), and a battery was produced in the same manner as in Comparative Example 2 except that the dye was adsorbed on the transparent layer and the reflective layer. The above reflective layer was formed in the same manner as in Example 4.

[Comparative Example 8]

In the production of the counter electrode, the PEDOT obtained by polymerizing the EDOT of the above formula (1-1) is changed to the polypyrrole obtained by polymerizing the pyrrole of the above formula (2-2) as a coating material for the catalyst layer. A battery was fabricated in the same manner as in Comparative Example 7, except the above.

[Comparative Example 9]

In the production of the counter electrode, the PEDOT obtained by polymerizing the EDOT of the above formula (1-1) is changed to the polyaniline obtained by polymerizing the aniline of the above formula (3-1). A battery was fabricated in the same manner as in Comparative Example 7, except the above.

[Comparative Example 10]

In the fabrication of the counter electrode, instead of forming the catalyst layer of PEDOT by electrolytic polymerization, A dispersion obtained by mixing PEDOT, carbon black particles (particle diameter: 23 nm) and ethanol at a weight ratio of 2:1:16 was applied to a glass substrate having an FTO film on the surface, and dried at 120 ° C for 60 minutes. A battery was fabricated 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.

[Comparative Example 11]

In the production of the counter electrode, a battery was fabricated in the same manner as in Comparative Example 10 except that the titanium oxide particles (particle diameter: 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 battery was fabricated in the same manner as in Example 4 except that the porous film was not coated with a conductive polymer.

[Comparative Example 13]

In the production of the counter electrode, a battery was fabricated in the same manner as in Example 7 except that the porous film was not coated with a conductive polymer.

[Comparative Example 14]

In the production of the counter electrode, a battery was fabricated in the same manner as in Example 10 except that the porous film was not coated with a conductive polymer.

The same evaluation as in Example 1 was carried out for each of the batteries produced in the above Examples 4 to 16 and Comparative Examples 6 to 14. The results are shown in Table 2.

From the above results, it is understood that the electrode substrate of the embodiment in which the catalyst layer is coated on the porous film can obtain excellent power generation efficiency regardless of the type of the catalyst layer and the type of the porous film.

In Examples 4 to 6, it was found that the power generation efficiency of the electrode substrate having a large specific surface area was improved.

In the electrode substrates of Comparative Examples 10 to 11, the conductive polymer was applied to the surface of the conductive glass, but the coated surface was not a porous structure, and thus the power generation efficiency was inferior to that of the fourth embodiment.

An SEM image of the surface of the counter electrode of Example 9 is shown in Fig. 4A. Further, the surface of the counter electrode of Example 9 was coated with the surface of the porous film before PEDOT. The SEM image is shown in Figure 4B. 4A and 4B, it can be seen that PEDOT is applied along the three-dimensional porous structure on the surface of the porous film of FIG. 4A.

An SEM image of a cross section of the counter electrode of Example 9 is shown in Fig. 4C. Further, an enlarged image of the cross section is shown in Fig. 4D. In FIG. 4C and FIG. 4D, it is understood that a continuous structure in which a single pore is connected is formed in the porous membrane. Further, in the enlarged image of Fig. 4D, the range indicated by the black dotted line indicates the surface (boundary) of the titanium oxide coated with ATO, and the range indicated by the white dotted line indicates the surface (boundary) of the catalyst layer composed of PEDOT. . The distance between the black dashed line and the white dashed line indicates the thickness of the catalyst layer.

An SEM image of the surface of the counter electrode of Example 10 was observed in Fig. 5A. Further, an SEM image of the surface of the porous film before the PEDOT was applied to the surface of the counter electrode of Example 10 is shown in Fig. 5B. 5A and 5B, it can be seen that PEDOT is applied along the three-dimensional porous structure on the surface of the porous film of FIG. 5A.

An SEM image of the surface of the counter electrode of Example 7 is shown in Fig. 6A. Further, an SEM image of the surface of the porous film before the PEDOT was applied to the surface of the counter electrode of Example 7 is shown in Fig. 6B. 6A and 6B, it can be seen that PEDOT is applied along the three-dimensional porous structure on the surface of the porous film of FIG. 6A.

An SEM image of the surface of the counter electrode of Example 8 is shown in Fig. 7A. Further, an SEM image of the surface of the porous film before the PEDOT was applied to the surface of the counter electrode of Example 8 is shown in Fig. 7B. 7A and 7B, it can be seen that PEDOT is applied along the three-dimensional porous structure on the surface of the porous film of FIG. 7A.

An SEM image of the surface of the counter electrode of Comparative Example 6 is shown in Fig. 8. It can be seen that the film made of platinum is formed flat. Also, the counter electrode of Comparative Example 7 will be observed. The SEM image of the surface is shown in Fig. 9. It can be seen that the film containing PEDOT is formed into a film flat. Further, an SEM image of the surface of the counter electrode of Comparative Example 11 is shown in Fig. 10 . It is understood that although the degree of roughness is observed on the surface of the film containing PEDOT, the film is formed substantially flat. It is understood that the counter electrode of any of the comparative examples does not have a film structure having a three-dimensional depth.

[Example 17]

A battery was fabricated in the same manner as in Example 9. The thickness of the porous film made of the ATO-coated titanium oxide particles was 2.2 μm in the counter electrode of the battery. Further, the film thickness was measured by a method of measuring the film thickness step by a stylus type surface shape measuring device.

[Embodiment 18]

In the production of the counter electrode, a battery was fabricated in the same manner as in Example 17 (Example 9) except that the film thickness of the formed porous film was changed to 5.6 μm by increasing the number of times of screen printing.

[Embodiment 19]

In the production of the counter electrode, a battery was fabricated in the same manner as in Example 17 (Example 9) except that the film thickness of the formed porous film was changed to 10.1 μm by increasing the number of times of screen printing.

[Comparative Example 15]

A battery was fabricated in the same manner as in Comparative Example 6. The film thickness of the platinum film (platinum electrode) formed by sputtering on the counter electrode of the battery was 20 nm. Further, the film thickness was estimated by observing a cross-sectional image of the platinum electrode by SEM.

[Comparative Example 16]

The same as Comparative Example 15 (Comparative Example 6) except that the film thickness of the platinum film was changed to 50 nm. The way to make a battery.

[Comparative Example 17]

A battery was fabricated in the same manner as in Comparative Example 15 (Comparative Example 6) except that the film thickness of the platinum film was changed to 100 nm.

[Comparative Example 18]

A battery was fabricated in the same manner as in Comparative Example 7. In the counter electrode of the battery, the film thickness of the film composed of PEDOT formed by electrolytic polymerization was 20 nm. Further, the film thickness was estimated by observing the cross-sectional image of the PEDOT electrode by SEM.

[Comparative Example 19]

In the production of the counter electrode, the film thickness of the film formed of PEDOT was changed to 40 nm by the polymerization time of the electrolytic polymerization method, and was produced in the same manner as in Comparative Example 18 (Comparative Example 7). battery.

[Comparative Example 20]

In the production of the counter electrode, the film thickness of the film formed of PEDOT was changed to 100 nm by the polymerization time of the electrolytic polymerization method, and the film was produced in the same manner as in Comparative Example 18 (Comparative Example 7). battery.

[Comparative Example 21]

In the production of the counter electrode, the film thickness of the film formed of PEDOT was changed to 200 nm by the polymerization time of the electrolytic polymerization method, and the film was produced in the same manner as in Comparative Example 18 (Comparative Example 7). battery.

The same evaluation as in Example 1 was carried out for each of the batteries produced in the above Examples 17 to 19 and Comparative Examples 15 to 21. The results are shown in Table 3.

From the results of Examples 17 to 19 of the above table, it is understood that as the thickness (film thickness) of the catalyst layer of the counter electrode increases, the power generation efficiency of the battery increases. For this reason, it is conceivable that the catalyst layer of the embodiment has a structure in which the porous structure is three-dimensionally connected. Therefore, as the film thickness increases, the catalyst reaction area increases.

On the other hand, in the case of using the platinum film as the counter electrode of Comparative Examples 15 to 17, even if the film thickness of the platinum electrode was increased, the power generation efficiency hardly changed. On the other hand, in the case of the batteries of Comparative Examples 18 to 21 in which the film made of PEDOT formed directly on the surface of the conductive glass substrate was used as the counter electrode, the same was also the case. The reason why the power generation efficiency does not change is that the catalyst reaction area does not increase even if the film thickness of the counter electrode of the comparative example is increased. Further, in the battery of Comparative Example 21 in which PEDOT was set to a film thickness of about 200 nm, the film was peeled off due to insufficient strength of the film.

Each of the above-described embodiments and combinations thereof are one In addition, the additions, omissions, substitutions, and other changes may be made without departing from the scope of the invention. Further, the present invention is not limited by the embodiments, but is limited only by the claimed patent.

[Industrial availability]

The electrode substrate of the present invention and the dye-sensitized solar cell using the same can be widely used in the field of solar cells.

Claims (13)

An electrode substrate comprising a conductive substrate, a porous film formed on the conductive substrate, and a catalyst layer applied to the porous film. The electrode substrate according to claim 1, wherein the catalyst layer is applied along a three-dimensional structure of the porous film. The electrode substrate according to claim 1 or 2, wherein the porous film coated with the catalyst layer contains a plurality of single pores connected to each other. The electrode substrate of claim 3, wherein the number of the unitary structures is larger than the number of the single holes in the porous film coated with the catalyst layer. The electrode substrate according to claim 1 or 2, wherein the porous film is made of a metal or a metal compound. The electrode substrate according to claim 1 or 2, wherein the porous film is made of a carbon material. The electrode substrate according to claim 1 or 2, wherein the catalyst layer is made of a conductive polymer. The electrode substrate according to claim 7, wherein the conductive polymer is a polymer of a thiophene compound represented by the following formula (1); Wherein R ¹ and R ² each independently represent 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 or an ester; a group, an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amine group, a nitro group, an azo group, a sulfo group, or a sulfonyl group; when R ¹ and R ² are the above alkyl group or alkoxy group, the above alkyl group Or the carbon atoms at the terminal of the alkoxy group may be bonded to each other to form a ring]. The electrode substrate according to claim 7, wherein the conductive polymer is a polymer of a pyrrole compound represented by the following formula (2); Wherein R ³ and R ⁴ each independently represent 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 or an ester; a group, an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amine group, a nitro group, an azo group, a sulfo group, or a sulfonyl group; when R ³ and R ⁴ are the above alkyl group or alkoxy group, the above alkyl group Or the carbon atoms at the terminal of the alkoxy group may be bonded to each other to form a ring]. The electrode substrate of the seventh aspect of the invention, wherein the conductive polymer is a polymer of an aniline compound represented by the following formula (3); Wherein R ⁵ to R ⁸ each independently represent 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 or an ester; a base, an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amine group, a nitro group, an azo group, a sulfo group, or a sulfonyl group; when R ⁵ and R ⁶ or R ⁷ and R ⁸ are the above alkyl group or alkane In the case of an oxy group, the carbon atoms at the terminal of the above alkyl group or alkoxy group may be bonded to each other to form a ring]. The electrode substrate according to claim 1 or 2, wherein the surface of the conductive substrate is in contact with the porous film. The electrode substrate of the seventh aspect of the invention, wherein the conductive polymer is applied to the porous film via an electrolytic polymerization method using the porous film as a working electrode. A dye-sensitized solar cell comprising a counter electrode comprising an electrode substrate according to claim 1 or 2, a photoelectrode for adsorbing a dye, and an electrolyte.