WO2015030193A1

WO2015030193A1 - Method for reactivating counter electrode active material for dye-sensitive solar cell, method for regenerating dye-sensitive solar cell in which said method is used, catalyst layer for dye-sensitive solar cell, counter electrode, electrolyte, and dye-sensitive solar cell

Info

Publication number: WO2015030193A1
Application number: PCT/JP2014/072785
Authority: WO
Inventors: 大輔時田; 純一郎安西; 俊介功刀; 山口　文治; 智弘大塚; 友章片桐; 壮一郎鈴木; 篤生駒; 剛之小林
Original assignee: 積水化学工業株式会社
Priority date: 2013-08-30
Filing date: 2014-08-29
Publication date: 2015-03-05
Also published as: CN105283936A; JPWO2015030193A1; KR20160052462A; KR102286239B1; CN105283936B; JP5960921B2; TW201517354A

Abstract

　The present invention addresses the problem of providing: a method for reactivating a counter electrode active material for a dye-sensitive solar cell capable of preventing a decrease in the power generation performance of a dye-sensitive solar cell, the method for reactivating a counter electrode active material allowing the temporarily decreased power generation performance of the dye-sensitive solar cell to be restored to the initial performance by regenerating an electroconductive polymer reduced by a redox pair in an electrolyte in the dye-sensitive solar cell; a method for regenerating a dye-sensitive solar cell in which said method is used; a catalyst layer for a dye-sensitive solar cell; a counter electrode; an electrolyte; and a dye-sensitive solar cell. The present invention is a method for reactivating a counter electrode active material for a dye-sensitive solar cell having a counter electrode configured from a catalyst layer that contains at least one electroconductive polymer as the counter electrode active material, wherein the method for reactivating a counter electrode active material for a dye-sensitive solar cell includes re-oxidizing the electroconductive polymer by chemical or electrochemical oxidation.

Description

Method for reactivating counter electrode active material of dye-sensitized solar cell, method for regenerating dye-sensitized solar cell applying the method, catalyst layer for dye-sensitized solar cell, counter electrode, electrolyte and dye-sensitized solar cell

The present invention relates to a method for reactivating a counter electrode active material of a dye-sensitized solar cell, a method for regenerating a dye-sensitized solar cell to which the method is applied, a catalyst layer for a dye-sensitized solar cell, a counter electrode, an electrolytic solution, and a dye. It relates to a sensitized solar cell.
This application claims priority based on Japanese Patent Application No. 2013-179849 filed in Japan on August 30, 2013 and Japanese Patent Application No. 2013-260073 filed on December 17, 2013 in Japan. , The contents of which are incorporated herein.

In recent years, solar cells have attracted attention as a clean power source that can directly convert light energy into electric power using the photovoltaic effect and does not discharge pollutants such as carbon dioxide. Among solar cells, a dye-sensitized solar cell is expected as a next-generation solar cell because it has high conversion efficiency, is manufactured by a relatively simple method, and the raw material cost is low.

A generally known dye-sensitized solar cell is a so-called Gretzel type dye-sensitized solar cell. In a Gretzel type dye-sensitized solar cell (hereinafter simply referred to as a dye-sensitized solar cell), when light is irradiated to a sensitizing dye adsorbed on the surface of a metal oxide semiconductor particle, electrons are converted from the sensitizing dye. In order to move sequentially to the photoelectrode, transparent conductive film, and external circuit, this is used as a current (see Non-Patent Document 1). On the other hand, the sensitizing dye that has emitted electrons is reduced by receiving electrons from the redox couple in the electrolytic solution. As a result, the redox couple in the electrolytic solution is oxidized, but is subsequently reduced by the catalyst layer constituting the counter electrode.

A platinum layer is widely used as a catalyst layer constituting the counter electrode of the conventional dye-sensitized solar cell. This is because platinum has a high catalytic ability for the oxidation-reduction reaction, and also has high stability and conductivity.
As a method for forming the platinum layer constituting the counter electrode, for example, there is a method in which a chloroplatinic acid solution is applied to a base material such as a glass substrate or a metal plate and heat treatment, or a method in which a film is formed by vacuum deposition, sputtering, or the like .

While having the advantages as described above, platinum is an expensive noble metal, and therefore has a problem of increasing the manufacturing cost of the dye-sensitized solar cell. For this reason, a new catalyst layer material that can replace platinum is being studied. For example, Non-Patent Document 2 and Patent Documents 1 and 2 disclose a dye-sensitized solar cell using a conductive polymer such as polythiophene, polyaniline, and polypyrrole as a material for a catalyst layer.

JP 2003-313317 A JP 2003-317814 A

In the dye-sensitized solar cell using the conductive polymer, the power generation performance (photoelectric conversion efficiency) is significantly deteriorated. This is because the conductive polymer is reduced from the oxidized state (doped state) to the neutral state (undoped state) by the oxidation-reduction pair (for example, I ⁻ , Br ⁻ etc.) in the electrolytic solution, and the catalytic activity, This is because the electrical conductivity is lowered.

The present invention has been made in view of the above circumstances, and a dye-sensitized solar cell once lowered by regenerating a conductive polymer reduced by a redox couple in an electrolyte solution of a dye-sensitized solar cell. The method of reactivating the counter active material of the dye-sensitized solar cell capable of restoring the power generation performance of the dye to the initial performance or preventing the deterioration of the power generation performance of the dye-sensitized solar cell, and applying the method An object is to provide a method for regenerating a dye-sensitized solar cell, a catalyst layer for the dye-sensitized solar cell, a counter electrode, an electrolytic solution, and a dye-sensitized solar cell.

As a result of diligent research, the present inventors have chemically synthesized the conductive polymer in a dye-sensitized solar cell having a counter electrode composed of a catalyst layer containing at least one type of conductive polymer as a counter electrode active material. It has been found that the above-mentioned problems can be solved by reoxidation by oxidation or electrochemical oxidation. Based on this knowledge, the present invention has been completed.

Next, in order to facilitate understanding of the present invention, basic features and preferred embodiments of the present invention will be listed.
<1> A method for reactivating the counter electrode active material of a dye-sensitized solar cell having a counter electrode composed of a catalyst layer containing at least one type of conductive polymer as a counter electrode active material,
Reoxidizing the conductive polymer by chemical oxidation or electrochemical oxidation,
A method for reactivating a counter electrode active material of a dye-sensitized solar cell.
<2> The method for reactivating a counter electrode active material for a dye-sensitized solar cell according to <1>, wherein the chemical oxidation is performed by immersing the conductive polymer in a solution in which an oxidizing agent is dissolved.
<3> The dye according to <1>, wherein the electrochemical oxidation is performed by immersing the conductive polymer as a working electrode in a solution containing a supporting electrolyte and applying a predetermined voltage to the working electrode. A method for reactivating a counter electrode active material of a sensitized solar cell.
<4> The catalyst layer according to <1>, wherein the catalyst layer further contains a photoacid generator, and the acid is generated by irradiating the photoacid generator with light, thereby performing the chemical oxidation. A method for reactivating a counter electrode active material of a dye-sensitized solar cell.
<5> The <1>, wherein the dye-sensitized solar cell includes an electrolytic solution containing at least one oxidizing agent capable of oxidizing a conductive polymer, and performs the chemical oxidation with the oxidizing agent. > The reactivation method of the counter electrode active material of the dye-sensitized solar cell described in>.
<6> A method for regenerating a dye-sensitized solar cell in which at least one type of conductive polymer forming a catalyst layer constituting a counter electrode is in a reduced state or a neutral state,
A method for regenerating a dye-sensitized solar cell, comprising a step of re-oxidizing the conductive polymer provided in the counter electrode by chemical oxidation or electrochemical oxidation.
<7> A catalyst layer for a dye-sensitized solar cell, comprising one or more conductive polymers and a photoacid generator.
<8> The catalyst layer 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, An ester group, an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amino group, a nitro group, or a sulfo group is represented. When R ¹ and R ² are the alkyl group or aryl group, the alkyl group or aryl group may be bonded to the thiophene ring via an azo group or 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 catalyst layer 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, or a sulfo group is represented. When R ³ and R ⁴ are the alkyl group or aryl group, the alkyl group or aryl group may be bonded to the pyrrole ring via an azo group or 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. ]
<10> The catalyst layer 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, or a sulfo group is represented. When R ⁵ to R ⁸ are the alkyl group or aryl group, the alkyl group or aryl group may be bonded to the benzene ring via an azo group or 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. ]
<11> In any one of the above <7> to <10>, in the catalyst layer, a ratio of (total mass of the photoacid generator) / (total mass of the conductive polymer) is 0.01 to 10. The catalyst layer according to claim 1.
<12> A counter electrode for a dye-sensitized solar cell, comprising a substrate on which a catalyst layer according to any one of the above <7> to <11> is formed.
<13> A dye-sensitized solar cell comprising the counter electrode according to <6>, a photoelectrode having a sensitizing dye, and an electrolytic solution containing a redox pair.
<14> A method for regenerating a dye-sensitized solar cell according to <13>, wherein at least a part of the conductive polymer constituting the catalyst layer is in a reduced state or a neutral state.
A method for regenerating a dye-sensitized solar cell, comprising re-oxidizing the conductive polymer by irradiating a photoacid generator contained in the catalyst layer with light.
<15> An electrolytic solution comprising at least one oxidizing agent capable of oxidizing a conductive polymer.
<16> The oxidizing agent is a group of simple substances including oxygen gas, chlorine gas and bromine gas, iron (III) chloride hexahydrate, anhydrous iron (III) chloride, iron (III) nitrate nonahydrate, A group of inorganic acids including ferric nitrate anhydride and iron (III) perchlorate, a group of organic acids including dodecylbenzenesulfonic acid, toluenesulfonic acid, trifluoroacetic acid and propionic acid, and tris (4-bromophenyl) The electrolyte solution according to <15>, wherein the electrolyte solution is at least one selected from the group consisting of amine hexane chloroantimonate.
<17> The electrolytic solution according to <16>, wherein the oxidizing agent is at least one selected from the inorganic acid group.
<18> When the oxidizing agent is at least one selected from the group of single gases, the content of the oxidizing agent is 1 mg / L to 50 mg / L when the entire electrolytic solution is 1 L. The electrolytic solution according to any one of <15> to <17>, which is characterized in that it is characterized in that
<19> When the oxidizing agent is at least one selected from the inorganic acid group and the organic acid group, the content of the oxidizing agent is 0.001 when the entire electrolytic solution is 100% by mass. The electrolyte solution according to any one of <15> to <17>, wherein the electrolyte solution has a content of 10% by mass to 10% by mass.
<20> The electrolyte solution according to any one of <15> to <19>, a working electrode having a semiconductor, and a counter electrode,
The working electrode includes an electrode layer made of a semiconductor and a dye adsorbed on the electrode layer,
The dye-sensitized solar cell, wherein the electrolytic solution is sandwiched between the working electrode and the counter electrode.

According to the method for reactivating the counter electrode active material of the dye-sensitized solar cell of the present invention, the conductive polymer reduced by contact with the electrolytic solution is reoxidized by chemical oxidation or electrochemical oxidation, The oxidation state is positively charged. That is, holes are present in the conductive polymer, and the conductive polymer is regenerated, thereby making it possible to recover or prevent the catalytic activity and electrical conductivity of the catalyst layer containing the conductive polymer.

In addition, according to the method for regenerating a dye-sensitized solar cell of the present invention, the catalyst layer for the dye-sensitized solar cell, the counter electrode, the electrolytic solution, and the dye-sensitized solar cell, to which the above method is applied, It becomes possible to realize recovery or prevention of deterioration of the catalytic activity and electrical conductivity of the catalyst layer.

It is sectional drawing which shows the dye-sensitized solar cell which has a counter electrode comprised from the catalyst layer which consists of conductive polymers. It is sectional drawing for demonstrating the reproduction | regenerating method of the dye-sensitized solar cell of the 2nd aspect of this invention. It is sectional drawing for demonstrating the reproduction | regenerating method of the dye-sensitized solar cell of the 2nd aspect of this invention. It is a figure for demonstrating the formation method of the counter electrode in Example 1, Comprising: It is a schematic diagram which shows the opposing base material in which the opposing conductive film was formed. It is a figure for demonstrating the formation method of the counter electrode in Example 1, Comprising: It is a schematic diagram which shows a counter electrode. 6 is a schematic diagram for explaining a counter electrode reduction method in Example 1. FIG. FIG. 2 is a diagram showing a dye-sensitized solar cell in Example 1, and is a schematic diagram showing a dye-sensitized solar cell having a counter electrode before being immersed in a γ-butyrolactone solution (0 hour). FIG. 2 is a diagram showing a dye-sensitized solar cell in Example 1, and is a schematic diagram showing a dye-sensitized solar cell having a counter electrode immersed in a γ-butyrolactone solution for 100 hours. FIG. 2 is a diagram showing a dye-sensitized solar cell in Example 1, and is a schematic diagram showing a dye-sensitized solar cell having a counter electrode immersed in a γ-butyrolactone solution for 300 hours. FIG. 2 is a diagram showing a dye-sensitized solar cell in Example 1, and is a schematic diagram showing a dye-sensitized solar cell having a counter electrode immersed in a γ-butyrolactone solution for 500 hours. 2 is a schematic diagram for explaining a counter electrode reoxidation method in Example 1. FIG. In Example 1, it is a photograph of a counter electrode before being immersed in a γ-butyrolactone solution (0 hour), a counter electrode immersed in a γ-butyrolactone solution for 500 hours, and then a counter electrode immersed in an acetonitrile solution for 5 minutes. 6 is a schematic diagram for explaining a counter electrode re-oxidation method in Example 2. FIG. It is a schematic cross section of a dye-sensitized solar cell provided with the catalyst layer and counter electrode concerning this invention.

Hereinafter, various embodiments of the present invention will be described with reference to the drawings. The drawings used in the following description are schematic, and the length, width, thickness ratio, and the like are not necessarily the same as actual ones, and can be changed as appropriate.

≪Reactivation method of counter active material≫
The method for reactivating a counter electrode active material of a dye-sensitized solar cell according to the first aspect of the present invention is a counter electrode of a dye-sensitized solar cell having a counter electrode composed of a catalyst layer made of at least one kind of conductive polymer. This is a method of reactivating the active material. Prior to describing the method for reactivating the counter electrode active material of the dye-sensitized solar cell, the configuration of the dye-sensitized solar cell 10 having the counter electrode composed of a catalyst layer made of a conductive polymer will be described with reference to FIG. I will explain.
In addition, the structure of the dye-sensitized solar cell 10 shown in FIG. 1 is the activation method of the counter electrode active material of the dye-sensitized solar cell of the present invention, the regeneration method of the dye-sensitized solar cell to which the method is applied, and the dye-sensitized It is an example of the structure which can apply the catalyst layer, counter electrode, electrolyte solution, and dye-sensitized solar cell for solar cells. That is, the dye-sensitized solar cell to which the various aspects of the present invention as described above are applied is not limited to the configuration of the dye-sensitized solar cell 10 illustrated in FIG. A plurality of unit cells may be connected in the width direction (that is, the W direction shown in FIG. 1).

As shown in FIG. 1, the dye-sensitized solar cell 10 includes a working electrode 11, a counter electrode 12 disposed to face the working electrode 11, and an electrolytic solution 20 interposed between the working electrode 11 and the counter electrode 12. It is configured with at least. The side of the electrolytic solution 20 is sealed with a sealing material 21.
An external circuit (not shown) is connected to the working electrode 11 and the counter electrode 12.
Hereinafter, each component will be sequentially described.

The working electrode 11 is an electrode in which a transparent substrate 13, a transparent conductive film 14, and a photoelectrode 15 are laminated in this order.

The transparent base material 13 is a base for the transparent conductive film 14 and the photoelectrode 15 and is made of a material that can transmit the light applied to the photoelectrode 15. Examples of such materials include soda lime glass, borosilicate glass, quartz glass, borosilicate glass, Vycor glass, non-alkali glass, blue plate glass, and white plate glass, polyethylene terephthalate (PET), polyethylene naphthalate, and the like. Examples of the resin include phthalate (PEN), acrylic resin, polycarbonate, and polyimide.

The transparent conductive film 14 is formed on one plate surface of the transparent substrate 13 by a sputtering method or a printing method. Examples of the transparent conductive film 14 include tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), antimony-doped tin oxide (ATO), indium oxide / zinc oxide (IZO), and gallium. Doped zinc oxide (GZO) or the like is used.

The photoelectrode 15 functions as a power generation layer of the dye-sensitized solar cell, and examples of the semiconductor compound constituting the photoelectrode include known metal oxides, compounds having perovskite crystals, and the like. A plurality of types of compounds may be selected and used. Examples of the metal oxide include titanium oxide and zinc oxide, and examples of the compound having a perovskite crystal include CH ₃ NH ₃ PbX ₃ (X is a halogen atom). The semiconductor compound (not shown) may be in the form of particles. The semiconductor compound may be configured by supporting a sensitizing dye on the semiconductor compound. As the metal oxide semiconductor particles, titanium oxide (TiO ₂ ) particles are preferable because a nano-order porous layer is formed and a surface area much larger than the surface area of the lower layer is obtained.

The sensitizing dye emits electrons by the light applied to the photoelectrode 15. The emitted electrons are transferred to the metal oxide semiconductor particles, smoothly moved to the transparent conductive film 14, and taken out to an external circuit (not shown). Examples of the sensitizing dye that emits electrons by the irradiated light include organic dyes such as ruthenium complex, cyanine, and chlorophyll. A ruthenium complex is preferred as the sensitizing dye because it has a wide absorption wavelength range, has a long photoexcitation lifetime, and stabilizes electrons transferred to the porous layer made of metal oxide semiconductor particles. Ruthenium complexes include, for example, cis-di (thiocyanato) -bis (2,2′-bipyridyl-4,4′-dicarboxylic acid) ruthenium (II), cis-di (thiocyanato) -bis (2,2 ′ -Bipyridyl-4,4'-dicarboxylic acid) ruthenium (II) bis-tetrabutylammonium salt (hereinafter referred to as N719).

The counter electrode 12 is an electrode in which a counter base material 16, a counter conductive film 17, and a conductive polymer catalyst layer 18 (catalyst layer) are laminated in this order.

The opposing base material 16 serves as a base for the opposing conductive film 17 and the conductive polymer catalyst layer 18, and is arranged at a distance from the transparent base material 13 in the thickness direction. Examples of the material of the counter substrate 16 include the same glass and resin as the transparent substrate 13, but are not particularly limited.

The counter conductive film 17 is formed on one plate surface of the counter substrate 16 by a sputtering method or a printing method. Examples of the counter conductive film 17 include tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), antimony-doped tin oxide (ATO), indium oxide / zinc oxide (IZO), and gallium. Doped zinc oxide (GZO) or the like is used. Although the counter conductive film 17 is preferably formed on the counter electrode 12, the counter conductive film 17 may be omitted.
The counter conductive film 17 is not necessarily light-transmitting. In addition to the above materials, examples of the material for forming the counter conductive film 17 include titanium, aluminum, nickel, chromium, gold, silver, and copper. These metals can also be used.

The conductive polymer catalyst layer 18 is formed on the surface of the counter conductive film 17 opposite to the surface in contact with the counter base material 16, and is disposed so as to oppose the photoelectrode 15 with the electrolytic solution 20 interposed therebetween. . The conductive polymer catalyst layer 18 contains at least one type of conductive polymer and reduces the redox couple contained in the electrolytic solution 20. Examples of the conductive polymer contained in the conductive polymer catalyst layer 18 include polythiophene, polyaniline, polypyrrole, poly (3,4-ethylenedioxythiophene) (PEDOT), and the like. The conductive polymer may be any one of these substances, or may be a mixture of two or more. The conductive polymer is in an oxidized state having a positive charge before the dye-sensitized solar cell 10 is manufactured. Further, the conductive polymer catalyst layer 18 may contain a conductive material other than the conductive polymer, such as a carbon material such as a carbon nanotube. As a specific example of the conductive polymer, a polymer of a thiophene compound represented by the general formula (1) described later in relation to the catalyst layer of the third aspect of the present invention, represented by the general formula (2) Examples include a polymer of a pyrrole compound and a polymer of an aniline compound represented by the general formula (3).
The amount of the conductive polymer contained in the conductive polymer catalyst layer 18 is preferably 10% by mass or more, more preferably 20% by mass or more, and particularly preferably 30% by mass or more. .

The thickness of the catalyst layer 18 is not particularly limited, but if it is an excessively thin catalyst layer, there is a concern that sufficient catalytic ability may not be exhibited, and therefore, for example, it is preferably 0.001 μm or more. The upper limit of the thickness of the catalyst layer 18 is not particularly limited. However, if it is excessively thick, it is uneconomical, and usually 10 μm or less is sufficient.

The catalyst layer 18 may be a dense layer or a porous layer. When the porous layer is used, the contact area with the electrolytic solution 20 increases, so that the catalytic ability of the catalyst layer 18 can be improved.

Examples of the method for forming the dense catalyst layer 18 include a method in which a solution containing a conductive polymer is applied on the surface of the counter conductive film 17 and dried, or the counter conductive film 17 is formed by using a monomer of a conductive polymer. And an electrolytic polymerization method in which a voltage is applied in a state of being immersed in a solution containing.

Examples of a method for forming the porous catalyst layer 18 include a method in which a conductive polymer is coated on the surface of a porous body of conductive fine particles by an electrolytic polymerization method, or in a solution containing the conductive polymer. Examples include a poor solvent-induced phase separation method in which a poor solvent is added.

The electrolytic solution 20 is injected into a space surrounded by the working electrode 11, the counter electrode 12, and the sealing material 21, and includes a redox pair that causes a redox reaction for causing electricity to flow in the dye-sensitized solar cell 10. It is a solution. Examples of such a redox pair include a combination of iodine and an iodide salt such as dimethylpropylimidazolium iodide and lithium iodide (iodide ion (I ⁻ ) / triiodide ion (I ₃ ⁻ )), A combination of bromine and a bromide salt such as dimethylpropylimidazolium bromide or lithium bromide (bromide ion (Br ⁻ ) / tribromide ion (Br ₃ ⁻ )) can be mentioned. Examples of the solvent for the electrolytic solution 20 include nitrile nonaqueous solvents such as acetonitrile and propionitrile, lactone nonaqueous solvents such as γ-butyrolactone and γ-valerolactone, ethylmethylimidazolium tetracyanoborate, and ethylmethylimidazole. Examples include ionic liquids such as lithium dicyanamide. Further, the electrolytic solution 20 may be gelled by a gelling agent such as polyacrylonitrile.
The concentration of the halogen in the electrolytic solution 20 is preferably 1 to 500 mM, more preferably 5 to 300 mM, and particularly preferably 10 to 200 mM. The concentration of the halide salt in the electrolytic solution 20 is preferably 0.1 to 10M, more preferably 0.2 to 5M, and particularly preferably 0.5 to 3M.
The molar ratio of the halogen to the halide salt is preferably 1: 1 to 1: 1000, more preferably 1: 5 to 1: 500, and 1:10 to 1: 200. It is particularly preferred.

Examples of the material of the sealing material 21 include a mixture of a photocurable resin and a thermosetting resin.

In the dye-sensitized solar cell 10, when “power generation light” is incident from the direction of the arrow shown in FIG. 1, the sensitizing dye of the photoelectrode 15 absorbs light, emits electrons to the metal oxide semiconductor particles, and is in an oxidized state. become. The emitted electrons move through the porous layer made of metal oxide semiconductor particles and reach the transparent conductive film 14. Thereafter, the electrons pass through the wiring connected to the working electrode 11 and move to the counter conductive film 17 or the conductive polymer catalyst layer 18 of the counter electrode 12 through an external circuit. On the other hand, the oxidized sensitizing dye receives electrons from the redox couple contained in the electrolytic solution 20 and is reduced. Further, the redox couple is oxidized, moves to the conductive polymer catalyst layer 18 side, and is reduced by the conductive polymer contained in the conductive polymer catalyst layer 18. A current flows through the dye-sensitized solar cell 10 by repeating such a redox reaction.

In the initial state of the dye-sensitized solar cell 10, the conductive polymer contained in the conductive polymer catalyst layer 18 is in an oxidized state. On the other hand, after the production, in the dye-sensitized solar cell 10, the conductive polymer provided in the conductive polymer catalyst layer 18 is reduced by contact with the redox couple in the electrolytic solution 20 and is not charged. It becomes a neutral state or a reduced state with a negative charge. Since the conductive polymer in the neutral state or the reduced state cannot exhibit catalytic ability and electrical conductivity, the battery performance decreases as the reduction proceeds.

Next, a method for reactivating the counter electrode active material of the dye-sensitized solar cell according to the first aspect of the present invention will be described.
The method for reactivating the counter electrode active material of the dye-sensitized solar cell of the present invention is a conductive polymer contained in the conductive polymer catalyst layer 18 of the dye-sensitized solar cell 10 (hereinafter simply referred to as a conductive polymer). Is a method in which when the dye-sensitized solar cell 10 is reduced by long-term use or the like, the conductive polymer is re-oxidized by chemical oxidation or electrochemical oxidation. In the present invention, “reactivation” means that the power generation performance is improved by the reduction of the conductive polymer in the conductive polymer catalyst layer 18 after a certain period of time has elapsed after the dye-sensitized solar cell 10 is manufactured. The counter electrode of the lowered dye-sensitized solar cell 10 is regenerated by reoxidation of the conductive polymer, or the conductive polymer reduced in the conductive polymer catalyst layer 18 is sequentially reoxidized. It is meant to maintain the power generation performance.
Hereinafter, each of a method for re-oxidizing a conductive polymer by chemical oxidation and a method for re-oxidation by electrochemical oxidation will be described.

<Method of re-oxidizing conductive polymer by chemical oxidation>
Here, an example in which the conductive polymer is reoxidized by immersing the conductive polymer in a solution in which the oxidizing agent is dissolved will be described. The time for immersing the conductive polymer in the solution in which the oxidizing agent is dissolved can be, for example, about 1 to 10 minutes.

The oxidizing agent may be any substance that can oxidize the conductive polymer without impairing the properties of the conductive polymer. Examples of such substances include inorganic compounds such as iron chloride (III) and iron chloride (III) hydrate, organic acids such as sulfonic acid such as dodecylbenzenesulfonic acid and toluenesulfonic acid, trifluoroacetic acid, and propionic acid. Examples include acids and tris (4-promophenyl) amine hexane chloroantimonate. From the viewpoint of high solubility in a general-purpose solvent and high oxidizing action, it is preferable to use iron (III) chloride or iron (III) chloride hydrate as the oxidizing agent.

Examples of the solvent for the oxidizing agent include solvents that can dissolve the oxidizing agent and do not elute the conductive polymer catalyst layer 18 made of a conductive polymer. For example, general-purpose organic solvents such as acetonitrile, ethanol, acetone, and toluene are used. be able to.

In this method, a solution in which an oxidizing agent is dissolved in a conductive polymer may be applied directly, or may be evaporated and applied as a vapor.

Alternatively, a catalyst layer containing a photoacid generator may be used, and the photoacid generator may be irradiated with light to generate an acid, thereby performing the chemical oxidation. The specific configuration and material of the catalyst layer and the light irradiation method will be described later in relation to the catalyst layer of the third aspect of the present invention.

Further, an electrolytic solution containing at least one oxidizing agent capable of oxidizing the conductive polymer may be used, and the chemical oxidation may be performed with the oxidizing agent. The composition of the electrolytic solution and the oxidant that can be used will be described later in relation to the electrolytic solution of the seventh aspect of the present invention.

<Method of re-oxidizing conductive polymer by electrochemical oxidation>
Here, an example in which a conductive polymer is immersed in a solution containing a supporting electrolyte as a working electrode and a predetermined voltage is applied to the working electrode to reoxidize the conductive polymer will be described.
The time for immersing the conductive polymer in the solution containing the supporting electrolyte can be, for example, about 1 to 10 minutes. The predetermined voltage applied to the working electrode is preferably set in consideration of the material of the reference electrode. When the material of the reference electrode is silver, the voltage applied to the working electrode can be set to, for example, −1.0V to 1.0V.

The supporting electrolyte may be any substance that is easily dissolved in a general-purpose solvent and gives sufficient ionic conductivity to the solvent. Examples of such substances include perchlorates such as tetraethylammonium perchlorate and tetrabutylammonium perchlorate, tetrafluoroborate such as tetraethylammonium tetrafluoroborate and bis (trifluoromethanesulfonyl) imide lithium. Examples include trifluoromethanesulfonate.

As the solvent for the supporting electrolyte, a solvent that can dissolve the supporting electrolyte and does not elute the conductive polymer catalyst layer 18 made of a conductive polymer, for example, acetonitrile, propylene carbonate, γ-butyrolactone, dichloromethane, methanol, or the like is used. be able to.

By performing the above-described “method of reoxidizing a conductive polymer by chemical oxidation” or “method of reoxidizing a conductive polymer by electrochemical oxidation”, the dye-sensitized solar cell 10 can be used for a long time. The conductive polymer reduced by the use or the like is regenerated.

≪Regeneration method of dye-sensitized solar cell≫
Next, a method for regenerating a dye-sensitized solar cell according to the second aspect of the present invention will be described with reference to FIGS.
In the method for regenerating a dye-sensitized solar cell of the present invention, the dye in which at least one kind of conductive polymer forming the conductive polymer catalyst layer 18 constituting the counter electrode 12 shown in FIG. 1 is in a reduced state or a neutral state. This is a method for regenerating the sensitized solar cell 10. That is, the method for regenerating a dye-sensitized solar cell of the present invention includes a step of reoxidizing at least the conductive polymer of the conductive polymer catalyst layer 18 by chemical oxidation or electrochemical oxidation. Here, in addition to the step of reoxidizing the conductive polymer, the step of removing the counter electrode 12 from the dye-sensitized solar cell 10 and the step of reassembling the dye-sensitized solar cell 10 using the counter electrode 12 were provided. A method for regenerating the dye-sensitized solar cell will be described.
Hereinafter, each step will be described.

<Step of removing counter electrode from dye-sensitized solar cell>
As shown in FIG. 2, the sealing material 21 is cut into two sealing materials 21 </ b> A and 21 </ b> B in the thickness direction, and the counter electrode 12 is taken out from the dye-sensitized solar cell 10.

<Step of re-oxidizing the conductive polymer provided on the counter electrode by chemical oxidation or electrochemical oxidation>
In this step, for the conductive polymer forming the conductive polymer catalyst layer 18 of the counter electrode 12 of the dye-sensitized solar cell 10, the counter electrode active material of the dye-sensitized solar cell according to the first aspect of the present invention described above is used. In the reactivation method, “a method of reoxidizing a conductive polymer by chemical oxidation” or “a method of reoxidizing a conductive polymer by electrochemical oxidation” is performed. Description of each method is omitted. By this step, the conductive polymer provided in the counter electrode 12 and in the reduced state or neutral state is reoxidized to the oxidized state, and the catalytic activity and electrical conductivity of the conductive polymer are restored to the initial performance. .

<The process of reassembling a dye-sensitized solar cell using a counter electrode>
Next, as shown in FIG. 3, the working electrode 11 is made so that the conductive polymer catalyst layer 18 of the counter electrode 12 having the reoxidized conductive polymer and the photoelectrode 15 of the working electrode 11 face each other. The counter electrode 12 is arranged at a predetermined interval with respect to each other, and the sealing

materials

21A and 21B are joined by heat treatment or the like. Thereafter, an injection hole 22 for injecting the electrolytic solution 20 is formed in a part of the sealing material 21.
The injection hole 22 may be formed in a part of the counter electrode 12 as shown by a broken line in FIG. Subsequently, the electrolytic solution 20 is injected from the injection hole 22 into a space S formed by the working electrode 11, the counter electrode 12, and the sealing material 21. By this step, the dye-sensitized solar cell 10 is reassembled using the counter electrode 12.

Through the above steps, the dye-sensitized solar cell 10 obtained by reoxidizing at least one kind of conductive polymer forming the conductive polymer catalyst layer 18 constituting the counter electrode 12 is obtained.

As described above, the method for reactivating the counter active material of the dye-sensitized solar cell according to the first aspect of the present invention includes the conductive polymer catalyst layer 18 composed of at least one kind of conductive polymer. The conductive polymer of the dye-sensitized solar cell 10 having the counter electrode 12 is re-oxidized by chemical oxidation or electrochemical oxidation.
As a result, the conductive polymer reduced by long-term use of the dye-sensitized solar cell 10 is oxidized by chemical oxidation or electrochemical oxidation, that is, has a positive charge and has holes. And can be played. As a result, the catalytic activity and electrical conductivity of the catalyst layer containing the conductive polymer can be restored to the initial performance before the conductive polymer is reduced.

In the method for reactivating the counter active material of the dye-sensitized solar cell according to the first aspect of the present invention, when chemical oxidation is carried out by immersing a conductive polymer in a solution in which an oxidizing agent is dissolved, When the oxidant therein extracts electrons from the conductive polymer, the oxidant is reduced and the conductive polymer is oxidized. Therefore, the conductive polymer can be easily regenerated by the room temperature process, and the catalytic activity and electrical conductivity of the conductive polymer catalyst layer can be restored to the initial state before the conductive polymer is reduced.

In the method for reactivating a counter electrode active material of a dye-sensitized solar cell according to the first aspect of the present invention, electrochemical oxidation is performed by immersing a conductive polymer as a working electrode in a solution containing a supporting electrolyte, and further, a reference electrode When the auxiliary electrode is immersed and then applied by applying a predetermined voltage to the working electrode, the working electrode undergoes an oxidation reaction due to electron extraction, and the auxiliary electrode undergoes a reduction reaction due to electron delivery. Is oxidized. Accordingly, the conductive polymer can be regenerated, and the catalytic activity and electrical conductivity of the conductive polymer catalyst layer can be restored to the initial performance before the conductive polymer is reduced.

The method for regenerating a dye-sensitized solar cell of the present invention includes a step of reoxidizing the conductive polymer forming the conductive polymer catalyst layer 18 constituting the counter electrode 12 by chemical oxidation or electrochemical oxidation. Yes.
Thereby, the conductive polymer of the conductive polymer catalyst layer 18 of the counter electrode 12 reduced by the long-term use of the dye-sensitized solar cell 10 is reoxidized by the above-described chemical oxidation or electrochemical oxidation. The catalytic activity and electrical conductivity of the conductive polymer catalyst layer 18 can be increased.
Therefore, the power generation performance of the dye-sensitized solar cell 10 whose power generation performance is reduced by reducing the conductive polymer of the conductive polymer catalyst layer 18 is reliably restored to the initial performance, and the dye-sensitized solar cell 10 is restored. Can play. As a result, the use period of the dye-sensitized solar cell 10 can be extended.
In addition, when using the above-mentioned photoacid generator containing catalyst layer, the simple method of irradiating light to the catalyst layer which comprises a counter electrode, without decomposing | disassembling the dye-sensitized solar cell 10 (6th aspect of this invention). Thus, the power generation performance can be recovered.
Moreover, when using the above-mentioned oxidizing agent-containing electrolyte, when the dye-sensitized solar cell 10 is used, the reduced conductive polymer is sequentially reoxidized by the oxidizing agent contained in the electrolyte. Since it is possible to prevent a decrease in the power generation performance of the battery, it is usually unnecessary to perform the regeneration method as described above.

<Catalyst layer>
The catalyst layer of the third aspect of the present invention is a catalyst layer for a dye-sensitized solar cell, and is a catalyst layer containing one or more conductive polymers and a photoacid generator.
Examples of the form of the catalyst layer include a form formed on the surface of a conductive substrate. The catalyst layer may be a dense layer or a porous layer. The thickness of the catalyst layer is not particularly limited, and can be set to 0.001 μm to 10 μm, for example.

(Conductive polymer)
The conductive polymer constituting the catalyst layer is not particularly limited as long as it can supply electrons to the oxidation-reduction pair contained in the electrolytic solution. For example, the conductive polymer used in the first aspect of the present invention may be recycled. Known conductive polymers as described above in connection with the activation method can be applied.
The conductive polymer is preferably at least one selected from the group consisting of a thiophene compound polymer, a pyrrole compound polymer, and an aniline compound polymer.
Examples of the polymer of the thiophene compound include a polymer obtained by polymerizing 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 (R′OOC— (R ′ represents an alkyl group having 1 to 8 carbon atoms)), an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amino group, a nitro group, or a sulfo group. When R ¹ and R ² are the alkyl group or aryl group, the alkyl group or aryl group may be bonded to the thiophene ring via an azo group or 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.

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

Moreover, as a polymer of a pyrrole compound, for example, a polymer obtained by polymerizing a pyrrole compound represented by the following general formula (2) may be mentioned.

[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 (R′OOC— (R ′ represents an alkyl group having 1 to 8 carbon atoms)), an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amino group, a nitro group, or a sulfo group. When R ³ and R ⁴ are the alkyl group or aryl group, the alkyl group or aryl group may be bonded to the pyrrole ring via an azo group or 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. ]

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 polymer of the aniline compound include a 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, An ester group (R′OOC— (R ′ represents an alkyl group having 1 to 8 carbon atoms)), an aldehyde group, a hydroxyl group, a halogen atom, a cyano group, an amino group, a nitro group, or a sulfo group. When R ⁵ to R ⁸ are the alkyl group or aryl group, the alkyl group or aryl group may be bonded to the benzene ring via an azo group or 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. ]

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 conductive polymer constituting the catalyst layer may be subjected to a known doping treatment for improving the conductivity. For example, sulfonic acids such as polystyrene sulfonic acid (PSS) and p-toluenesulfonic acid (PTS), halogens such as iodine, bromine and chlorine, perchloric acid (ClO ₄ ⁻ ), bistrifluoromethanesulfonylimide (TFSI), tetracyano Quinodimethane (TCNQ) or the like may be added to the conductive polymer as a dopant.

The one or more kinds of conductive polymers contained in the catalyst layer reduce the redox couple contained in the electrolytic solution. Specific examples of such a conductive polymer include polythiophene, polyaniline, polypyrrole, poly (3,4-ethylenedioxythiophene) (PEDOT), and the like. The conductive polymer contained in the catalyst layer may be one kind or two or more kinds. The conductive polymer in the catalyst layer is preferably in an oxidized state with a positive charge before the production of the dye-sensitized solar cell.

One or more kinds of conductive polymers contained in the catalyst layer may be contained singly or in combination of two or in combination of three or more. It may be. The upper limit of the type of the conductive polymer used in combination is not particularly limited, but it may be usually 10 or less.
When using 2 or more types in combination, for example, from the group consisting of a conductive polymer polymerized with the thiophene compound, a conductive polymer polymerized with the pyrrole compound, and a conductive polymer polymerized with the aniline compound. Any two or three or more kinds of conductive polymers selected may be used in combination. The mixing ratio of the two or more conductive polymers may be set as appropriate in consideration of conductivity.

(Photoacid generator)
The photoacid generator constituting the catalyst layer is not particularly limited as long as it can generate an acid by irradiation with light such as ultraviolet rays, and a known photoacid generator can be applied. Specific examples include sulfonic photoacid generators such as bis-paratoluenesulfonyldiazomethane and bis-tert-butylsulfonyldiazomethane, diphenyl-4-methylphenylsulfonium trifluoromethanesulfonate, diphenyl-2,4,6-trimethylphenyl. Sulfonium p-toluenesulfonate, 4-methoxyphenyldiphenylsulfonium trifluoromethanesulfonate and other sulfonium photoacid generators, bis-4-tert-butylphenyliodonium bisperfluorobutanesulfonylimide and other iodonium photoacid generators, etc. Can be mentioned. The photoacid generator constituting the catalyst layer may be used alone or in combination of two or more.

It is preferable that the photoacid generator contained in the catalyst layer absorbs light in a wavelength region of 300 nm or more. The reason is that the reproduction light can be absorbed by the base material (for example, FTO glass, ITO-PET film, ITO-PEN film, etc.) constituting the counter electrode by irradiating the light in the wavelength range as the reproduction light described later. This is because it becomes easy to irradiate the photoacid generator (catalyst layer) with a sufficient amount of light.

In the catalyst layer, the ratio of (total weight of the photoacid generator) / (total weight of the conductive polymer) is preferably 0.01 to 10, more preferably 0.05 to 5, 1 is more preferable.
When the mass ratio is 0.01 or more, a sufficient amount of acid can be generated by light irradiation. When the mass ratio is 10 or less, it is possible to prevent an excessive amount of the photoacid generator from lowering the electrical conductivity of the catalyst layer.

The total mass of the conductive polymer with respect to the total mass of the catalyst layer is preferably 10% by mass or more, more preferably 20% by mass or more, and still more preferably 50% by mass or more.
When it is 10% by mass or more, the catalytic ability and electrical conductivity of the catalyst layer can be sufficiently enhanced. The upper limit of the total mass of the conductive polymer is not particularly limited, and can be, for example, 90% by mass or less.

The total mass of the photoacid generator relative to the total mass of the catalyst layer is preferably 1 to 90 mass%, more preferably 5 to 70 mass% or more, and still more preferably 10 to 50 mass% or more.
When the amount is 1% by mass or more, a sufficient amount of acid can be generated by ultraviolet irradiation. When it is 90% by mass or less, it is possible to avoid an excessive amount of the photoacid generator from lowering the electrical conductivity of the catalyst layer.

(Auxiliary)
The catalyst layer may contain a conductive material other than the conductive polymer. Examples of such conductive materials include carbon materials such as carbon nanotubes and acetylene black. The content of the conductive material is preferably about 10 to 500 parts by mass when the conductive polymer constituting the catalyst layer is 100 parts by mass.

《Counter electrode》
The counter electrode of the fourth aspect of the present invention is a counter electrode for a dye-sensitized solar cell, and has a substrate on which the catalyst layer of the third aspect is formed.

The form of the substrate is not particularly limited, and examples thereof include a plate-like substrate and a film. The substrate may be light transmissive or non-light transmissive, but it is easy to irradiate the catalyst layer constituting the dye-sensitized solar cell with light. The substrate is preferably light transmissive.

The surface of the substrate may be conductive or non-conductive. Since the catalyst layer itself formed on the surface is conductive, even if the surface of the substrate is non-conductive, it can sufficiently function as a counter electrode. From the viewpoint of increasing the conductivity of the counter electrode, the surface on which the conductive polymer is formed is preferably conductive.

Examples of the light-transmitting substrate having at least a conductive surface include a transparent conductive substrate in which a transparent conductive film is formed on the surface of a glass substrate or a transparent resin substrate. Examples of the non-light transmissive substrate include a metal substrate and a resin substrate having no light transmissive property. In addition, the light transmittance of the resin substrate may vary depending on the thickness of the substrate.

Examples of the resin include resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), acrylic resin, polycarbonate, and polyimide.

The thickness of the catalyst layer formed on the surface of the base material is not particularly limited. However, if the catalyst layer is excessively thin, there is a concern that sufficient catalytic ability may not be exhibited. For example, the thickness may be 0.001 μm or more. preferable. The upper limit of the thickness of the catalyst layer is not particularly limited, but if it is excessively thick, it is uneconomical, and usually 10 μm or less is sufficient.

The catalyst layer formed on the surface of the substrate may be a dense layer or a porous layer. When the porous layer is used, the contact area with the electrolytic solution increases, so that the catalytic ability of the catalyst layer can be improved.
The specific surface area of the porous layer is preferably 0.1 m ² / g or more, more preferably 1 m ² / g or more, and further preferably 3 m ² / g or more when measured by a gas adsorption method. preferable.

Examples of a method for forming a dense catalyst layer include a method in which a solution containing a conductive polymer and a photoacid generator is applied on the surface of the substrate and dried.

As a method for forming a porous catalyst layer, for example, a porous layer made of a metal oxide semiconductor such as titanium oxide fine particles is previously formed on the surface of the substrate by a known baking method or particle spraying method. The porous layer may be impregnated with a solution containing a conductive polymer and a photoacid generator and dried.

As another forming method, the base material on which the porous layer is formed is immersed in a solution containing the monomer molecules constituting the conductive polymer, and the monomer molecules are diffused in the porous layer. The conductive polymer may be synthesized in the porous layer by an electrolytic polymerization method in which a current is passed through the porous layer. According to this electrolytic polymerization method, the conductive polymer can be disposed also in the deep portion in the porous layer. Thereafter, the porous polymer layer is impregnated with a solution containing a photoacid generator, and the solvent is removed and dried, so that the conductive polymer and the photoacid generator coexist on the surface and inside of the porous layer. A catalyst layer can be formed. Examples of the monomer molecule include the thiophene compound, pyrrole compound, and aniline compound described above.

《Dye-sensitized solar cell》
A dye-sensitized solar cell according to a fifth aspect of the present invention includes the counter electrode according to the fourth aspect described above, a photoelectrode having a sensitizing dye, and an electrolytic solution including a redox pair.
In FIG. 10, sectional drawing of the dye-sensitized solar cell 10 is shown as an example of a 5th aspect. The configuration, materials, and functions of the dye-sensitized solar cell 10 shown in FIG. 10 are basically the same as those described above with reference to the dye-sensitized solar cell 10 shown in FIG. It is a catalyst layer.

<Regeneration method of dye-sensitized solar cell>
In the method for regenerating a dye-sensitized solar cell according to the sixth aspect of the present invention, the dye-sensitized solar cell according to the fifth aspect described above, wherein at least a part of the conductive polymer constituting the catalyst layer is in a reduced state or a neutral state. A method for regenerating a battery, wherein the conductive polymer is reoxidized by irradiating a photoacid generator contained in the catalyst layer with light.

For example, when the dye-sensitized solar cell 10 shown in FIG. 10 is regenerated, light (for example, ultraviolet light) in a wavelength region capable of generating an acid from the photoacid generator from the direction of the arrow “reproduction light” shown in FIG. ), The regenerated light transmitted through the light-transmitting counter substrate 16 and counter conductive film 17 constituting the counter electrode 12 reaches the catalyst layer 18. The photoacid generator that has absorbed the regenerated light generates an acid, and returns the conductive polymer contained in the same catalyst layer 18 to an oxidized state. As a result, the catalytic ability and electrical conductivity of the catalyst layer 18 are restored, and the battery performance is preferably restored to the initial state.

The light source of the reproduction light (ultraviolet light or the like) may be any light source that is capable of irradiating light stronger than sunlight. Etc. The irradiation time varies depending on the reduced state of the conductive polymer contained in the catalyst layer 18, the light source used, the type and amount of photoacid generator, etc., and thus cannot be specified unconditionally, but is preferably 10 to 600 seconds, 30 More preferably, ˜300 seconds.

In a normal usage pattern (power generation) of the dye-sensitized solar cell 10, light for power generation (power generation light) such as sunlight enters from the direction of the arrow “power generation light” shown in FIG. The generated light passing through the electrolytic solution 20 and reaching the catalyst layer 18 is attenuated. For this reason, there is no fear that the photoacid generator contained in the catalyst layer 18 is consumed up in a normal usage pattern (a usage pattern not intended for regeneration). Even if the generated light reaches the catalyst layer 18 and releases the acid from the photoacid generator, the acid contributes to maintaining the oxidation state of the conductive polymer. It does not matter that the generated light reaches the catalyst layer 18.

<Electrolyte>
The electrolyte solution according to the seventh aspect of the present invention is an electrolyte solution containing at least one oxidizing agent capable of oxidizing a conductive polymer. More specifically, in the dye-sensitized solar cell, the electrolyte solution of the present embodiment includes an oxidizing agent that can oxidize a catalyst layer made of a conductive polymer that constitutes the dye-sensitized solar cell, and a dye-sensitized solar cell. It is a solution comprising a redox couple that causes a redox reaction for flowing electricity and a solvent.

(Oxidant)
The oxidizing agent is not particularly limited as long as it is a substance that can oxidize the conductive polymer. Examples of the oxidizing agent include a group of simple gases including oxygen gas, chlorine gas, bromine gas, ozone, iron (III) chloride hexahydrate, anhydrous iron (III) chloride, iron nitrate (III) nonahydrate , Inorganic acid groups including ferric nitrate anhydride and iron (III) perchlorate, organic acid groups including dodecylbenzenesulfonic acid, toluenesulfonic acid, trifluoroacetic acid and propionic acid, and tris (4 -Bromophenyl) amine hexane chloroantimonate at least one selected from the group consisting of. Among these, it is preferable to use at least one selected from the group of simple gases and inorganic acids from the viewpoint of high solubility in general-purpose solvents and high oxidizing action on conductive polymers. More preferably, bromine gas or iron (III) chloride is used.

When the oxidizing agent is at least one selected from the group of simple gases, the content of the oxidizing agent is preferably 1 mg / L to 50 mg / L when the entire electrolyte is 1 L, and is preferably 5 mg / L to More preferably, it is 50 mg / L, and even more preferably 10 mg / L to 50 mg / L.
When the content of the oxidizing agent with respect to the entire electrolytic solution is less than 1 mg / L%, it is difficult to oxidize the conductive polymer reduced by the redox couple again. On the other hand, if the content of the oxidant with respect to the entire electrolyte exceeds 50 mg / L, the redox reaction of the redox couple may be inhibited, and electricity may not flow.
When the oxidizing agent is at least one selected from the group of single gases, the single gas is contained or dissolved in the electrolytic solution by bubbling the single gas in the electrolytic solution.
Further, when the oxidizing agent is at least one selected from the group of simple gases, these simple gases exist as molecules in the electrolytic solution.
When the simple substance gas is oxygen gas, the amount of dissolved oxygen in the electrolytic solution is measured by, for example, a dissolved oxygen meter.

When the oxidizing agent is at least one selected from the group of inorganic acids and organic acids, the content of the oxidizing agent is 0.001% by mass to 10% by mass with respect to 100% by mass of the entire electrolyte. Preferably, the content is 0.005% by mass to 5% by mass, and more preferably 0.01% by mass to 1% by mass.
When the content of the oxidizing agent with respect to the entire electrolytic solution is less than 0.001% by mass, it becomes difficult to oxidize the conductive polymer reduced by the redox couple again. On the other hand, if the content of the oxidizing agent with respect to the entire electrolyte exceeds 10% by mass, the oxidation-reduction reaction of the oxidation-reduction pair may be inhibited, and electricity may not flow.
In addition, when an oxidizing agent is at least 1 sort (s) selected from the group of an inorganic acid and the group of an organic acid, these acids dissociate in electrolyte solution and exist as an ion.

(Redox couple and solvent)
As the redox couple and the solvent, the same ones as described above in relation to the method for reactivating the counter electrode active material according to the first aspect of the present invention can be used.

According to the electrolytic solution of this embodiment, since it contains at least one kind of oxidizing agent, when applied to a dye-sensitized solar cell or the like, it constitutes a catalyst layer that is reduced by a redox pair contained in the electrolytic solution. The conductive polymer can be oxidized again by the oxidizing agent contained in the electrolytic solution. That is, the power generation performance (photoelectric conversion efficiency) of the dye-sensitized solar cell can be prevented from being deteriorated by oxidizing the conductive polymer again with the oxidizing agent.
By the way, by adding an oxidizing agent to the electrolytic solution, when the conductive polymer constituting the catalyst layer is reduced from the oxidized state to the neutral state by the redox pair contained in the electrolytic solution, immediately ( (Automatically) the conducting polymer is again oxidized by the oxidizing agent contained in the electrolyte.

<< Dye-sensitized solar cell >>
A dye-sensitized solar cell according to an eighth aspect of the present invention includes the electrolytic solution according to the seventh aspect, a working electrode having a semiconductor, and a counter electrode, and the electrolytic solution is sandwiched between the working electrode and the counter electrode. It becomes. Each member and basic structure of the dye-sensitized solar cell of the eighth aspect can be the same as those described above with reference to FIG.

According to the dye-sensitized solar cell 10 of the present embodiment, since the electrolyte solution 20 includes the electrolyte solution of the seventh aspect, even when a conductive polymer is used for the catalyst layer 18, power generation when used for a long period of time. Degradation of performance can be prevented. In addition, since the electroconductive polymer constituting the catalyst layer 18 is reduced by the redox couple contained in the electrolytic solution 20, the power generation performance is not deteriorated. Therefore, the dye-sensitized solar cell 10 is decomposed. Since the work of regenerating the catalyst layer 18 becomes unnecessary, the maintenance cost and management cost of the dye-sensitized solar cell 10 can be reduced.

The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific embodiments, and various modifications are possible within the scope of the gist of the present invention described in the claims. Deformation / change is possible. Moreover, the various aspects of the present invention described above can be combined as appropriate as long as the object of the present invention is not impaired.

In the present invention, as a method for confirming how much the conductive polymer is in a reduced state, for example, a method using a spectroscopic spectrum can be mentioned. Since the shape of the spectral spectrum differs depending on whether the conductive polymer is in an oxidized state, neutral state or reduced state, the reduced state can be determined quantitatively by measuring the spectral spectrum of the conductive polymer catalyst layer. is there. Therefore, in various embodiments of the present invention, it is possible to determine how much the reduction process has been performed.

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

Example 1
<Formation of working electrode>
A glass substrate having an FTO film formed on the plate surface was prepared as the transparent substrate 13. On the FTO film, a paste composed of TiO ₂ particles having an average particle diameter of 14 nm: 19% by mass, ethyl cellulose: 9% by mass, and terpineol: 72% by mass was formed into a film with a size of 4 mm × 4 mm by a screen printing method. and fired at 500 ° C. 30 minutes to form a porous layer made of TiO ₂ particles. Thereafter, a porous material composed of TiO ₂ particles in a sensitizing dye solution in which N719 was dissolved as a sensitizing dye at a concentration of 0.3 mM in a mixed solution in which acetonitrile and tert-butanol were mixed at a mass ratio of 1: 1. After immersing the glass substrate provided with the layer and the FTO film for 20 hours, the sensitizing dye was adsorbed on the surface of the porous layer by washing with acetonitrile. This produced the working electrode 11 in which the transparent conductive film 14 and the photoelectrode 15 were laminated on the transparent substrate 13.

<Formation of counter electrode>
Next, a glass substrate having an FTO film formed of the same material as that of the working electrode 11 was prepared, and an injection hole penetrating the FTO film and the glass substrate was formed as an injection hole 22 for injecting the electrolytic solution 20. Thereby, as shown to FIG. 4A, the opposing base material 16 which consists of the glass with which the opposing conductive film 17 which consists of FTO was laminated | stacked was formed. In FIG. 4A, FIG. 4B, and FIG. 5, the illustration of the injection hole for electrolyte injection is omitted. Subsequently, a polyaniline solution containing 10% by mass of polyaniline containing sulfonate as a dopant and 90% by mass of toluene was formed on the FTO film by spin coating (rotation speed: 3000 rpm, 20 seconds). Then, the conductive polymer catalyst layer 18 containing polyaniline which is a conductive polymer was formed by performing a heat treatment at 100 ° C. for 10 minutes on a hot plate. As a result, as shown in FIG. 4B, the counter electrode 12 in which the counter conductive film 17 and the conductive polymer catalyst layer 18 were laminated on the counter substrate 16 was produced.

Next, as shown in FIG. 5, a γ-butyrolactone solution containing the counter electrode 12 prepared by the above method, containing iodine: 0.05M and 1,3-dimethyl-2-propylimidazolium iodide: 1.0M. In order to promote the reduction of the conductive polymer, the conductive polymer of the conductive polymer catalyst layer 18 of the counter electrode 12 was reduced by heating to 85 ° C. At this time, the counter electrode 12 with an immersion time of 0 hour (before immersion), 100 hours, 300 hours, and 500 hours was taken out as counter electrodes 12A to 12D, washed with acetonitrile, and dried.

<Assembly of dye-sensitized solar cell>
Next, as shown in FIGS. 6A to 6D, the conductive polymer catalyst layer 18 reduced as described above and the photoelectrode 15 of the working electrode 11 are opposed to each other so that the

counter electrodes

12A, 12B, Each of 12C and 12D is arranged at a predetermined interval with respect to the working electrode 11, a sealing material (not shown) is arranged on the side of the space between the working electrode 11 and the counter electrode 12, and the heat treatment or the like is performed. The encapsulant was cured. Thereafter, the electrolyte solution 20 was injected from a not-shown injection hole into a space surrounded by the working electrode 11, the counter electrode 12, and the sealing material, thereby producing dye-sensitized solar cells 10A to 10D. Electrolyte 20 includes iodine: 0.03M, 1,3-dimethyl-2-propylimidazolium iodide: 0.6M, lithium iodide: 0.10M, tert-butylpyridine: 0.5M in a solvent. What was dissolved in a certain acetonitrile was used.

<Evaluation of power generation performance of dye-sensitized solar cell>
Next, using a solar simulator (model number: XES-301S, manufactured by Mitsunaga Electric Co., Ltd.), the photoelectric conversion efficiency, short-circuit current density, open-circuit voltage, and fill factor of each of the dye-sensitized solar cells 10A to 10D were measured. Thus, the power generation performance of the dye-sensitized solar cells 10A to 10D was evaluated.

<Removal of counter electrode from dye-sensitized solar cell>
Next, in the same manner as the “step of removing the counter electrode from the dye-sensitized solar cell” in the method for regenerating a dye-sensitized solar cell described above, the conductive polymer is reduced by being immersed in a γ-butyrolactone solution for 500 hours. The counter electrode 12D was taken out from the obtained dye-sensitized solar cell 10D.

<Reoxidation of conductive polymer by chemical oxidation>
Next, as shown in FIG. 7, the taken-out counter electrode 12D is immersed in an acetonitrile solution containing iron chloride (hexahydrate): 0.01M for 5 minutes, and the conductivity of the conductive polymer catalyst layer 18 of the counter electrode 12D. The polymer was reoxidized by chemical oxidation. Thereby, the counter electrode 12E provided with the conductive polymer re-oxidized from the reduced state was produced. FIG. 8 shows a counter electrode 12D before being immersed in a γ-butyrolactone solution containing iodine: 0.05M and 1,3-dimethyl-2-propylimidazolium iodide: 1.0M, iodine: 0.05M, 1,3-Dimethyl-2-propylimidazolium iodide: A counter electrode 12D immersed in a γ-butyrolactone solution containing 1.0M for 500 hours, and the counter electrode 12D as iron chloride (hexahydrate): acetonitrile containing 0.01M It is the photograph of the counter electrode 12E immersed for 5 minutes in the solution.

<Reassembly of dye-sensitized solar cells and evaluation of power generation performance>
Next, using the counter electrode 12E, the dye-sensitized solar cell 10E was assembled in the same manner as in “Assembly of dye-sensitized solar cell” described above. Moreover, each item of the photoelectric conversion efficiency of the dye-sensitized solar cell 10E, a short circuit current density, an open circuit voltage, and a fill factor using the solar simulator used when performing the above "evaluation of the power generation performance of the dye-sensitized solar cell" Was measured to evaluate the power generation performance of the dye-sensitized solar cell 10E.

(Example 2)
A process similar to that in Example 1 was performed, except that re-oxidation of the conductive polymer provided in the counter electrode 12 was performed by electrochemical oxidation instead of chemical oxidation. Hereinafter, “reoxidation of conductive polymer by electrochemical oxidation” and subsequent “reassembly of dye-sensitized solar cell / evaluation of power generation performance” will be described, and other steps similar to those in Example 1 will be described. The description about is omitted.

<Reoxidation of conductive polymer by electrochemical oxidation>
As shown in FIG. 9, the conductive polymer catalyst layer 18 of the counter electrode 12D of the dye-sensitized solar cell 10D shown in FIGS. 6A to 6D is used as a working electrode, and LiTFSI (lithium bistrifluoromethanesulfonylimide) as a supporting electrolyte: It was immersed in an acetonitrile solution containing 10 ⁻¹ M. Thereafter, using a platinum wire and a silver wire as an auxiliary electrode and a reference electrode, respectively, a voltage of 1.0 V was applied to the conductive polymer catalyst layer 18 as a working electrode by a potentiostat (manufactured by IVIUM) for 120 seconds, and the counter electrode 12D The conductive polymer of the conductive polymer catalyst layer 18 was reoxidized by electrochemical oxidation. Thereby, the counter electrode 12F provided with the conductive polymer re-oxidized from the reduced state was produced.

<Reassembly of dye-sensitized solar cells and evaluation of power generation performance>
Next, using the counter electrode 12F, the dye-sensitized solar cell 10F was assembled in the same manner as in “Assembly of dye-sensitized solar cell” described above. Moreover, each item of the photoelectric conversion efficiency of the dye-sensitized solar cell 10F, a short circuit current density, an open circuit voltage, and a fill factor using the solar simulator used when performing the above "evaluation of the power generation performance of the dye-sensitized solar cell" Was measured to evaluate the power generation performance of the dye-sensitized solar cell 10F.

(Comparative Example 1)
The same steps as in Example 1 were performed except that “reoxidation of the conductive polymer by chemical oxidation” was not performed. That is, the counter electrode 12D reduced by dipping in a γ-butyrolactone solution for 500 hours was washed with acetonitrile and dried to form a counter electrode 12G (not shown), and then the dye-sensitized solar cell 10G was assembled using the counter electrode 12G. Then, using the solar simulator used when performing the above-mentioned “evaluation of power generation performance of the dye-sensitized solar cell”, each item of photoelectric conversion efficiency, short-circuit current density, open-circuit voltage, and fill factor of the dye-sensitized solar cell 10G Was measured to evaluate the power generation performance of the dye-sensitized solar cell 10G.

(Evaluation results of power generation performance of dye-sensitized solar cells in Examples 1 and 2 and Comparative Example 1) Tables show evaluation results of power generation performance of dye-sensitized solar cells 10A to 10G in Examples 1, 2 and Comparative Example 1. It is shown in 1. The recovery rate of photoelectric conversion efficiency due to reoxidation in Table 1 was calculated by the ratio of the photoelectric conversion efficiency of the dye-sensitized solar cells 10E to 10G to the photoelectric conversion efficiency of the dye-sensitized solar cell 10A.

As shown in Table 1, in the dye-sensitized solar cell 10E of Example 1, the recovery rate of photoelectric conversion efficiency due to re-oxidation of the counter electrode 12D was 0.97, and a value close to 1 was obtained. Regarding the short-circuit current density, the open-circuit voltage, and the fill factor of the dye-sensitized solar cell 10E, the same results as the respective items in the dye-sensitized solar cell 10A were obtained. This is because the conductive polymer reduced by being immersed in the γ-butyrolactone solution for 500 hours was re-oxidized and regenerated by chemical oxidation after being immersed in the acetonitrile solution for 5 minutes. In addition, due to the regeneration of the conductive polymer, the catalytic activity and electrical conductivity of the conductive polymer catalyst layer 18 of the counter electrode 12E are substantially restored to the initial performance before the conductive polymer is reduced. .

Moreover, also in the dye-sensitized solar cell 10F of Example 2, the recovery rate of photoelectric conversion efficiency due to re-oxidation of the counter electrode 12D was 0.98, and a value close to 1 was obtained. Regarding the short-circuit current density, the open-circuit voltage, and the fill factor of the dye-sensitized solar cell 10F, the same results as the respective items in the dye-sensitized solar cell 10A were obtained. This is because the conductive polymer reduced by immersing in a γ-butyrolactone solution for 500 hours is immersed in an acetonitrile solution containing LiTFSI: 10 ⁻¹ M, and a platinum wire and a silver wire are used as an auxiliary electrode and a reference, respectively. This is because a voltage was applied to the conductive polymer catalyst layer 18 serving as a working electrode to reoxidize and regenerate by electrochemical oxidation. In addition, due to the regeneration of the conductive polymer, the catalytic activity and electrical conductivity of the conductive polymer catalyst layer 18 of the counter electrode 12F are substantially restored to the initial performance before the conductive polymer is reduced. .

In contrast to these examples, in the dye-sensitized solar cell 10G of Comparative Example 1, the photoelectric conversion efficiency is hardly recovered. The short-circuit current density, the open-circuit voltage, and the fill factor of the dye-sensitized solar cell 10G were all lower than the values of the respective items in the dye-sensitized solar cell 10A. This is because the conductive polymer reduced by dipping in a γ-butyrolactone solution for 500 hours and provided in the counter electrode 12G of the dye-sensitized solar cell 10G is reoxidized by chemical oxidation or reoxidation by electrochemical oxidation. None of this was done, and it was because it was not regenerated in the reduced state.

From the evaluation results of the power generation performance of the dye-sensitized solar cells in Examples 1 and 2 described above, according to the present invention, the conductive polymer reduced by long-term use of the dye-sensitized solar cells is reoxidized. By regenerating the counter electrode composed of the catalyst layer made of the conductive polymer, the catalyst activity and electrical conductivity of the catalyst layer are restored to the initial performance before the conductive polymer is reduced, and the dye The power generation performance of the sensitized solar cell was reliably restored to the initial performance, and it was confirmed that the dye-sensitized solar cell could be regenerated.

Example 3
<Production of photoelectrode>
A porous film was formed using a paste composed of 19% by mass of titanium oxide particles (particle diameter Φ14 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 layer (film thickness 10 μm) on the transparent conductive film.
The substrate provided with the porous layer was immersed in a dye solution in which a sensitizing dye N719 was dissolved at a concentration of 0.3 mM in a 1: 1 mixture of acetonitrile and tert-butanol, and then washed with acetonitrile. Then, a photoelectrode provided with a power generation layer formed by adsorbing a sensitizing dye to the porous layer was produced.

<Production of counter electrode>
In a glass substrate on which the FTO film was formed, an injection hole for injecting an electrolyte solution was formed in a later step. On this glass substrate, a solution containing a conductive polymer and a photoacid generator is applied by spin coating (rotation speed: 3000 rpm, 20 seconds), and a heat treatment is performed on a hot plate at 60 ° C. for 5 minutes, whereby an FTO film is obtained. A catalyst layer made of a conductive polymer and a photoacid generator was formed thereon.
In the solution, the content of the conductive polymer (poly 3,4-ethylenedioxythiophene (PEDOT) containing sulfonate as a dopant) is 85% by mass with respect to the total mass of the solution, and photoacid generation The content of the agent (Irgacure PAG103 (IR 103, manufactured by BASF)) was 15% by mass. Moreover, methanol was used as a solvent.

<Preparation of electrolyte>
An electrolyte solution was prepared by dissolving iodine in a solvent γ-butyrolactone to a concentration of 0.05 M and 1,3-dimethyl-2-propylimidazolium iodide at a concentration of 1.0 M.

<Assembly of dye-sensitized solar cell (DSC)>
A DSC cell was assembled by arranging a counter electrode provided with a catalyst layer and a photoelectrode provided with a power generation layer facing each other with a sealing material sandwiched therebetween, and curing the sealing material by heat treatment. Next, an electrolytic solution was injected from the injection hole formed in the counter electrode into a space surrounded by the photoelectrode, the counter electrode, and the sealing material, and the injection hole was sealed.

<Evaluation of power generation performance of dye-sensitized solar cell>
Using a solar simulator (model number: XES-301S, manufactured by Mitsunaga Electric Manufacturing Co., Ltd.), the photoelectric conversion efficiency (power generation efficiency) of the produced DSC cell under simulated sunlight irradiation with a light intensity of 100 mW / cm ² is measured. did. The results are shown in the column “Power generation efficiency (before 85 ° C.)” in Table 2.

<Heat resistance test of dye-sensitized solar cell (acceleration test)>
Next, after the DSC cell whose power generation efficiency was measured was placed in an electric furnace at 85 ° C. for 300 hours, the power generation performance was measured in the same manner as described above. The results are shown in the column “Power generation efficiency (after 85 ° C.)” in Table 2.

<Regeneration test of dye-sensitized solar cell>
Subsequently, the DSC cell whose power generation efficiency was measured after the heat resistance test was irradiated with ultraviolet light using a UV spot cure (manufactured by USHIO INC.). At this time, in order to increase the irradiation efficiency with respect to the conductive polymer constituting the catalyst layer, ultraviolet light was irradiated from the counter electrode side. Thereafter, the power generation performance was evaluated again. The results are shown in the column “Power generation efficiency (with ultraviolet light)” in Table 2.
The results of Examples 4 to 7 and Comparative Example 2 described later are also shown in Table 2.

Example 4
The “poly 3,4-ethylenedioxythiophene containing sulfonate as a dopant” used in Example 3 was changed to “polyaniline containing a sulfonate as a dopant”. Other than that was carried out in the same manner as in Example 3.

(Example 5)
The “poly 3,4-ethylenedioxythiophene containing sulfonate as a dopant” used in Example 3 was changed to “polypyrrole containing tetracyanotetraazanaphthalene as a dopant”. Other than that was carried out in the same manner as in Example 3.

(Example 6)
“Irgacure PAG103” used in Example 3 was changed to “Irgacure PAG121 (manufactured by BASF)”. Other than that was carried out in the same manner as in Example 3.

(Example 7)
“Irgacure PAG103” used in Example 3 was changed to “Irgacure PAG290 (manufactured by BASF)”. Other than that was carried out in the same manner as in Example 3.

(Comparative Example 2)
The same operation as in Example 3 was performed except that Irgacure PAG103 was not contained.

Consider the above results. First, the initial power generation performance has been degraded by an accelerated test that is stored at 85 ° C. for a long time. This is considered to be because the conductive polymer constituting the catalyst layer was chemically reduced or neutralized by the redox couple in the electrolyte. Thereafter, the power generation performance has been greatly recovered by irradiating the catalyst layer with ultraviolet light. This is presumably because, in the DSC cells of Examples 3 to 7, the conductive polymer returned to the oxidized state by the action of the acid released from the photoacid generator contained in the catalyst layer. On the other hand, since the photoacid generator is not contained in the catalyst layer of the DSC cell of Comparative Example 2, the power generation performance is not recovered even when irradiated with ultraviolet rays.

From the above, in the dye-sensitized solar cell provided with the catalyst layer and the counter electrode according to the present invention, the conductive polymer constituting the catalyst layer is neutralized or reduced by the contact between the electrolyte solution and the catalyst layer over a long period of time. Even if the power generation performance is reduced, it is apparent that the power generation performance can be recovered by irradiating the catalyst layer with light (regeneration light) that can release acid from the photoacid generator.

(Example 8)
<Formation of power generation layer (working electrode)>
As a transparent conductive substrate, a glass substrate having a surface resistance of 10 ohm (Ω) having an FTO film formed on the plate surface was prepared.
On the FTO film, a paste composed of TiO ₂ particles having an average particle diameter of 14 nm: 19% by mass, ethyl cellulose: 9% by mass, and terpineol: 72% by mass was formed into a film with a size of 4 mm × 4 mm by a screen printing method. and fired at 500 ° C. 30 minutes to form a porous layer made of TiO ₂ particles.
Thereafter, a porous material composed of TiO ₂ particles in a sensitizing dye solution in which N719 was dissolved as a sensitizing dye at a concentration of 0.3 mM in a mixed solution in which acetonitrile and tert-butanol were mixed at a mass ratio of 1: 1. After immersing the glass substrate provided with the layer and the FTO film for 20 hours, the sensitizing dye was adsorbed on the surface of the porous layer by washing with acetonitrile. This produced a working electrode in which a transparent conductive film and a photoelectrode were laminated on a transparent conductive substrate.

<Formation of catalyst layer (counter electrode)>
Next, a glass substrate on which an FTO film was formed of the same material as the working electrode was prepared, and an injection hole penetrating the FTO film and the glass substrate was formed as an injection hole for injecting an electrolytic solution. Thereby, the opposing base material which consists of glass with which the opposing electrically conductive film which consists of FTO films | membranes was laminated | stacked was formed.
Subsequently, a PEDOT solution comprising poly 3,4-ethylenedioxythiophene (PEDOT): 1 to 2% by mass and methanol: 98 to 99% by mass containing sulfonate as a dopant is spin-coated on the FTO film. The film was formed by (rotation speed: 3000 rpm, 20 seconds). Then, the catalyst layer containing PEDOT which is a conductive polymer was formed by performing a heat treatment at 80 ° C. for 5 minutes on a hot plate. This produced the counter electrode by which the opposing electrically conductive film and the catalyst layer which consists of a conductive polymer were laminated | stacked on the opposing base material.

<Formation of electrolyte containing oxidant>
In γ-butyrolactone as a solvent, 0.05 M iodine and 1.0 M 1,3-dimethyl-2-propylimidazolium iodide were dissolved as an oxidation-reduction pair to prepare an electrolytic solution.
Subsequently, oxygen (oxidant) was contained in the electrolytic solution by bubbling oxygen gas through the electrolytic solution for 10 minutes. At this time, the amount of dissolved oxygen in the electrolyte was measured with a dissolved oxygen meter. As a result, the amount of dissolved oxygen in the electrolytic solution was 10 g / L (converted to water saturation).

<Assembly of dye-sensitized solar cell>
The power generation layer and the catalyst layer produced as described above are opposed to each other, the counter electrode is arranged at a predetermined interval with respect to the working electrode, and is sealed to the side of the space between the working electrode and the counter electrode. A sealing material was placed, and the sealing material was cured by heat treatment or the like. Thereafter, the electrolyte prepared as described above is injected from the injection hole formed in the counter electrode into the space surrounded by the working electrode, the counter electrode and the sealing material, and then the injection hole is thermoset the sealing material. Thus, a dye-sensitized solar cell was produced.

<Evaluation of power generation performance of dye-sensitized solar cell>
Using a solar simulator, the power generation performance of the dye-sensitized solar cell was evaluated by measuring the photoelectric conversion efficiency under irradiation of pseudo sunlight with a light intensity of 100 mW / cm ² . The results are shown in Table 3.

<85 ° C heat resistance test for dye-sensitized solar cells (accelerated heat resistance test for catalyst layer)>
The dye-sensitized solar cell was stored in an electric furnace at 85 ° C. for 500 hours.
Thereafter, the photoelectric conversion efficiency of the dye-sensitized solar cell was measured as described above. The results are shown in Table 3.
Moreover, from the measurement result of the photoelectric conversion efficiency before and after the 85 ° C. heat test, the photoelectric conversion efficiency after the 85 ° C. heat test with respect to the photoelectric conversion efficiency before the 85 ° C. heat test ((photoelectric conversion efficiency after the 85 ° C. heat test) / (85 (Photoelectric conversion efficiency before heat resistance test at 100 ° C.) × 100 (%)) was calculated and used as the maintenance ratio of photoelectric conversion efficiency. The results are shown in Table 3.

Example 9
In <Formation of catalyst layer (counter electrode)>, the dye increase in Example 9 was performed in the same manner as in Example 8 except that a polyaniline solution was used instead of the poly 3,4-ethylenedioxythiophene (PEDOT) solution. A solar cell was prepared.
About the obtained dye-sensitized solar cell, it carried out similarly to Example 8, and evaluated the power generation performance of the dye-sensitized solar cell, and the 85 degreeC heat test of the dye-sensitized solar cell. The results are shown in Table 3.

(Example 10)
<Formation of electrolyte containing oxidant> In the same manner as in Example 1 except that 1 mmol / L of iron (III) chloride was contained in the electrolyte instead of bubbling oxygen gas into the electrolyte. A dye-sensitized solar cell of Example 3 was produced.
About the obtained dye-sensitized solar cell, it carried out similarly to Example 8, and evaluated the power generation performance of the dye-sensitized solar cell, and the 85 degreeC heat test of the dye-sensitized solar cell. The results are shown in Table 3.

(Comparative Example 3)
A dye-sensitized solar cell of Comparative Example 3 was produced in the same manner as in Example 8 except that oxygen gas was not bubbled into the electrolyte in <Formation of electrolyte containing oxidant>.
About the obtained dye-sensitized solar cell, it carried out similarly to Example 8, and evaluated the power generation performance of the dye-sensitized solar cell, and the 85 degreeC heat test of the dye-sensitized solar cell. The results are shown in Table 3.

(Comparative Example 4)
A dye-sensitized solar cell of Comparative Example 3 was produced in the same manner as in Example 9 except that in the <formation of electrolyte containing oxidant>, oxygen gas was not bubbled into the electrolyte.
About the obtained dye-sensitized solar cell, it carried out similarly to Example 8, and evaluated the power generation performance of the dye-sensitized solar cell, and the 85 degreeC heat test of the dye-sensitized solar cell. The results are shown in Table 3.

From the results shown in Table 3, it was found that in Examples 8 to 10, the electrolytic solution contained oxygen or iron (III) chloride as an oxidizing agent, and therefore the photoelectric conversion efficiency maintenance rate was high.
On the other hand, in Comparative Examples 3 and 4, since the electrolytic solution did not contain an oxidant, it was found that the maintenance ratio of the photoelectric conversion efficiency was low.

10, 10A, 10B, 10C, 10D, 10E, 10F, 10G Dye-sensitized solar cell 12 Counter electrode 18 Conductive polymer catalyst layer (catalyst layer)

Claims

A method of reactivating the counter electrode active material of a dye-sensitized solar cell having a counter electrode composed of a catalyst layer containing at least one type of conductive polymer as a counter electrode active material,
Reoxidizing the conductive polymer by chemical oxidation or electrochemical oxidation,
A method for reactivating a counter electrode active material of a dye-sensitized solar cell.
The method for reactivating a counter electrode active material of a dye-sensitized solar cell according to claim 1, wherein the chemical oxidation is performed by immersing the conductive polymer in a solution in which an oxidizing agent is dissolved.
The dye-sensitized solar cell according to claim 1, wherein the electrochemical oxidation is performed by immersing the conductive polymer in a solution containing a supporting electrolyte as a working electrode and applying a predetermined voltage to the working electrode. Method for reactivating the counter electrode active material.
The dye-sensitized solar according to claim 1, wherein the catalyst layer further contains a photoacid generator, and the photoacid generator is irradiated with light to generate an acid and thereby perform the chemical oxidation. A method for reactivating a counter active material of a battery.
The said dye-sensitized solar cell is equipped with the electrolyte solution containing the at least 1 sort (s) of oxidizing agent which can oxidize a conductive polymer, The said chemical oxidation is performed with the said oxidizing agent, The Claim 1 characterized by the above-mentioned. A method for reactivating a counter electrode active material of a dye-sensitized solar cell.
A method for regenerating a dye-sensitized solar cell in which at least one kind of conductive polymer forming a catalyst layer constituting a counter electrode is in a reduced state or a neutral state,
A method for regenerating a dye-sensitized solar cell, comprising a step of re-oxidizing the conductive polymer provided in the counter electrode by chemical oxidation or electrochemical oxidation.
A catalyst layer for a dye-sensitized solar cell, comprising one or more conductive polymers and a photoacid generator.
The catalyst layer 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, or a sulfo group is represented. When R 1 and R 2 are the alkyl group or aryl group, the alkyl group or aryl group may be bonded to the thiophene ring via an azo group or 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 catalyst layer 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, or a sulfo group is represented. When R 3 and R 4 are the alkyl group or aryl group, the alkyl group or aryl group may be bonded to the pyrrole ring via an azo group or 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 catalyst layer 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, or a sulfo group is represented. When R 5 to R 8 are the alkyl group or aryl group, the alkyl group or aryl group may be bonded to the benzene ring via an azo group or 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. ]
11. The catalyst layer according to claim 7, wherein a ratio of (total mass of the photoacid generator) / (total mass of the conductive polymer) is 0.01 to 10. Catalyst layer.
A counter electrode for a dye-sensitized solar cell, comprising a substrate on which a catalyst layer according to any one of claims 7 to 11 is formed.
A dye-sensitized solar cell comprising: the counter electrode according to claim 6; a photoelectrode having a sensitizing dye; and an electrolytic solution containing a redox pair.
The method for regenerating a dye-sensitized solar cell according to claim 13, wherein at least a part of the conductive polymer constituting the catalyst layer is in a reduced state or a neutral state.
A method for regenerating a dye-sensitized solar cell, comprising re-oxidizing the conductive polymer by irradiating a photoacid generator contained in the catalyst layer with light.
An electrolytic solution comprising at least one oxidizing agent capable of oxidizing a conductive polymer.
The oxidizing agent includes a group of simple gases including oxygen gas, chlorine gas and bromine gas, iron (III) chloride hexahydrate, anhydrous iron (III) chloride, iron (III) nitrate nonahydrate, anhydrous nitric acid A group of inorganic acids including diiron and iron (III) perchlorate, a group of organic acids including dodecylbenzenesulfonic acid, toluenesulfonic acid, trifluoroacetic acid and propionic acid, and tris (4-bromophenyl) aminehexane The electrolyte solution according to claim 15, which is at least one selected from the group consisting of chloroantimonate.
The electrolytic solution according to claim 16, wherein the oxidizing agent is at least one selected from the inorganic acid group.
When the oxidizing agent is at least one selected from the group of single gases, the content of the oxidizing agent is 1 mg / L to 50 mg / L when the entire electrolyte is 1 L. The electrolytic solution according to any one of claims 15 to 17.
When the oxidizing agent is at least one selected from the group of inorganic acids and the group of organic acids, the content of the oxidizing agent is 0.001% by mass to 100% by mass when the entire electrolytic solution is 100% by mass. The electrolytic solution according to any one of claims 15 to 17, wherein the electrolytic solution is 10% by mass.
An electrolyte solution according to any one of claims 15 to 19, a working electrode having a semiconductor, and a counter electrode,
The working electrode includes an electrode layer made of a semiconductor and a dye adsorbed on the electrode layer,
The dye-sensitized solar cell, wherein the electrolytic solution is sandwiched between the working electrode and the counter electrode.