JP2008251420A - Seal material for dye-sensitized solar cell, and dye- sensitized solar cell using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seal member having excellent resistance against electrolyte components used for a dye-sensitized solar cell, especially, iodide ion that is a redox pair, and as a result, having a highly reliable sealing performance, as well as a dye-sensitized solar cell using the same with degradation with time of solar battery characteristics restrained and with high durability. <P>SOLUTION: The seal material for a dye-sensitized solar cell contains conductive polymers in resin components, and is capable of absorbing iodide anion or the like as electrolyte ion of the dye-sensitized solar cell, endowed with excellent resistance to the above compound and highly reliable sealing performance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a solar cell that converts light energy into electric energy, and more particularly to a sealing material for a dye-sensitized solar cell, and a dye-sensitized solar cell using the same.

In recent years, dye-sensitized solar cells in which a semiconductor layer is loaded with a sensitizing dye that absorbs a visible light region have been studied. This dye-sensitized solar cell is expected to be put to practical use because of the advantages that the material used is inexpensive and that it can be manufactured by a relatively simple process.
In the dye-sensitized solar cell, electrons are injected into a semiconductor electrode from a sensitizing dye excited by absorbing visible light, and a current is taken out through a current collector. On the other hand, the oxidized form of the sensitizing dye is reduced and regenerated by a redox pair in the electrolyte. The oxidized redox pair is reduced on the counter electrode surface facing the semiconductor electrode, and the cycle goes around.

At present, the electrolyte generally uses a solution, that is, an electrolytic solution or a gel electrolyte in which the solution is held in a gel, and an iodide (for example, I ₃ ⁻ / I) is usually used as a redox couple. ^- etc.) have been used. The redox couple indispensable for the power generation mechanism is generally used after being dissolved in the electrolyte solution or the solvent in the gel. Therefore, sealing technology for preventing volatilization and leakage of the electrolyte and solvent is an important element for ensuring long-term reliability, durability, and safety.

  As a sealing material for a dye-sensitized solar cell, various sealing materials can be used according to the properties of each resin, such as a method using a sheet-like thermoplastic resin or a method using a liquid resin. Use is under consideration (Patent Documents 1 to 9).

However, various technologies and materials have been proposed, but they are sufficiently durable against the wide range of temperatures from direct sunlight to below freezing, and from the dry conditions to the humid conditions. The reality is that sex is not secured. This is because, in addition to severe use conditions, electrolyte components, especially anionic electrolyte components, particularly iodine and iodide anions used as redox couples, promote the deterioration of the sealing material.
Therefore, it can still be manufactured with lower manufacturing costs and processes, and it has excellent resistance to electrolyte components used in dye-sensitized solar cells, especially iodine, which is a redox couple, and has a reliable sealing performance. There is a need for a sealing material having a dye-sensitized solar cell using the same, as well as a high-durability dye-sensitized solar cell in which a decrease in solar cell characteristics over time is suppressed.

JP 2006-286413 A JP 2005-302564 A JP 2006-324201 A JP 2006-260899 A JP 2004-95248 A JP 2003-223939 A JP 2000-173680 A JP 2002-368236 A JP 2002-313443 A

  The present invention can be produced with a lower manufacturing cost and process, and has excellent resistance to an electrolyte component used in a dye-sensitized solar cell, particularly iodine which is a redox couple, and as a result, reliability. It is an object of the present invention to provide a sealing material having a high sealing performance, and a dye-sensitized solar cell having high durability in which deterioration of solar cell characteristics over time using the sealing material is suppressed.

  As a result of intensive studies to solve the above problems, the inventors of the present invention provide a sealing material for a dye-sensitized solar cell, wherein the sealing material comprises a sealing resin component and a conductive polymer. It has been found that it has excellent durability against electrolyte components used in dye-sensitized solar cells, particularly iodine which is a redox couple, and as a result, a sealing material having highly reliable sealing performance.

Therefore, the present invention
[1] A porous metal oxide semiconductor electrode containing a dye having a photosensitizing action;
In a resin sealing material used for a dye-sensitized solar cell having an electrolyte containing a chemical species that becomes a redox pair enclosed between a counter electrode disposed opposite to the semiconductor electrode,
It is a dye-sensitized solar cell sealing material characterized by containing a conductive polymer in the resin component,

[2] The dye-sensitized solar cell sealing material according to [1], wherein the conductive polymer can occlude anions.

[3] The dye-sensitized solar cell sealing material according to [1] or [2], wherein the conductive polymer dopant is desorbed,

[4] The dye-sensitized solar cell sealing material according to any one of [1] to [3], wherein the conductive polymer is chemically crosslinked with the resin component. ,

[5] The dye-sensitized solar cell according to any one of [1] to [4], wherein the conductive polymer is a polymerized conductive polymer containing a monomer in a resin component. Sealing material for

[6] The above-mentioned [1] to [1], wherein the monomer constituting the conductive polymer is at least one selected from the group consisting of aniline and derivatives thereof, pyrrole and derivatives thereof, thiophene and derivatives thereof. 5] is a sealing material for a dye-sensitized solar cell according to any one of

[7] The dye-sensitized solar cell according to any one of [1] to [6], wherein the distribution ratio of the conductive polymer increases as the electrolyte is closer to the inside of the sealing material. Sealing material,

[8] The dye-sensitized solar cell seal according to any one of [1] to [7], wherein a conductive polymer farther from the electrolyte is polymerized more densely in the seal material. Material,

[9] In a dye-sensitized solar cell in which an electrolyte is sealed between a semiconductor electrode and a counter electrode disposed to face each other,
A dye-sensitized solar cell, wherein a peripheral portion of the dye-sensitized solar cell is sealed with the sealing material for a dye-sensitized solar cell according to any one of [1] to [8]. ,

[10] A dye-sensitized solar cell having a plurality of dye-sensitized solar cells in which an electrolyte is sealed between a semiconductor electrode and a counter electrode disposed to face each other and a peripheral edge portion of the dye-sensitized solar cell is sealed. In battery modules,
At least a part of the electrode surface of the dye-sensitized solar cell is partitioned by the dye-sensitized solar cell sealing material according to any one of [1] to [8], and a pair of semiconductor electrodes and a counter electrode are provided. A dye-sensitized solar cell module comprising a plurality of dye-sensitized solar cells.

  The present invention is a sealing material for a dye-sensitized solar cell, wherein the sealing material comprises a sealing resin component and a conductive polymer, whereby an electrolyte component used for a dye-sensitized solar cell, In particular, it has excellent resistance to iodide ion, which is a redox pair, and as a result, it has a highly reliable sealing performance, and the solar cell characteristics using the sealing material are suppressed from deterioration over time and have high durability. The dye-sensitized solar cell which has can be provided.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings as appropriate. The structure will be briefly described with reference to a schematic cross-sectional view showing an example of the dye-sensitized solar cell in FIG. 1. The surface of the electrode substrate 1 including the transparent substrate 2 and the transparent conductive film 3 formed thereon is porous. A porous metal oxide semiconductor layer 4 is formed, and a sensitizing dye layer 5 is adsorbed on the surface of the porous metal oxide semiconductor layer 4 to form a semiconductor electrode 6. A counter electrode 8 composed of an electrode substrate 9 and a catalytically active layer 10 is disposed so as to face the electrolyte layer 7, and a gap between the electrodes is provided in part between the counter electrode and the semiconductor electrode as necessary. A regulating spacer 11 is provided. Furthermore, the peripheral part of both electrodes is sealed with the peripheral seal part 12 using the sealing material of this invention, and comprises the cell.

  On the other hand, FIG. 2 is a schematic cross-sectional view showing an example of a dye-sensitized solar cell module in which a plurality of the cells are arranged in parallel with the intermediate seal portion 13 interposed therebetween.

  FIG. 3 is an enlarged schematic view of a cross section showing an example of the sealing material of the present invention, and is a schematic view showing a state of the peripheral seal portion 12 composed of the sealing resin component 14 and the conductive polymer 15. 4 and 5 are enlarged schematic views of a cross section showing an example of the sealing material of the present invention. In the peripheral seal portion 12 composed of the sealing resin component 14 and the conductive polymer 15, the closer to the electrolyte, the closer the electrolyte is. It is the schematic diagram which showed a mode that the distribution ratio of the conductive polymer was increasing.

Hereinafter, a suitable form is demonstrated about each structural material of the dye-sensitized solar cell of this invention.
[Transparent substrate]
As the transparent substrate 2 constituting the electrode substrate 1, one that transmits visible light can be used, and transparent glass can be suitably used. Moreover, the thing which processed the glass surface and scattered incident light, and a translucent ground glass-like thing can also be used. Moreover, not only glass but a plastic plate, a plastic film, etc. can be used if it transmits light.
The thickness of the transparent substrate 2 is not particularly limited because it varies depending on the shape and use conditions of the solar cell. For example, when glass or plastic is used, the thickness is about 1 mm to 1 cm in consideration of durability during actual use. Yes, flexibility is required, and when a plastic film or the like is used, it is about 1 μm to 1 mm.

[Transparent conductive film]
As the transparent conductive film 3, a material that transmits visible light and has conductivity can be used, and examples of such a material include metal oxide. Although not particularly limited, for example, tin oxide doped with fluorine (hereinafter abbreviated as “FTO”), indium oxide, a mixture of tin oxide and indium oxide (hereinafter abbreviated as “ITO”), and oxidation. Zinc or the like can be suitably used. In addition, an opaque conductive material can be used as long as visible light is transmitted through a treatment such as dispersion. Such materials include carbon materials and metals. Although it does not specifically limit as a carbon material, For example, graphite (graphite), carbon black, glassy carbon, a carbon nanotube, fullerene, etc. are mentioned. Further, the metal is not particularly limited, and examples thereof include platinum, gold, silver, copper, aluminum, nickel, cobalt, chromium, iron, molybdenum, titanium, and alloys thereof. Therefore, the transparent conductive film 3 can be formed by providing on the surface of the transparent substrate 2 at least one of the above conductive materials. Alternatively, it is also possible to incorporate the conductive material into the material constituting the transparent substrate 2 and integrate the transparent substrate and the transparent conductive film into the electrode substrate 1.

As a method for forming the transparent conductive film 3 on the transparent substrate 2, in the case of forming a metal oxide, there are a sol-gel method, a vapor phase method such as sputtering and CVD, and a coating of a dispersion paste. Moreover, when using an opaque electroconductive material, the method of fixing powder etc. with a transparent binder etc. is mentioned.
In order to integrate the transparent substrate and the transparent conductive film, the conductive film material may be mixed as a conductive filler when the transparent substrate is molded.
The thickness of the transparent conductive film 3 is not particularly limited because the conductivity varies depending on the material to be used, but is generally 0.01 μm to 5 μm, preferably 0.1 μm to 1 μm in the FTO-coated glass. It is. Further, the required conductivity varies depending on the area of the electrode to be used, and a larger area electrode is required to have a lower resistance, but is generally 100Ω / □ or less, preferably 10Ω / □ or less, more preferably 5Ω / □ or less. If it exceeds 100Ω / □, the internal resistance of the solar cell increases, which is not preferable.
The thickness of the electrode substrate 1 composed of a transparent substrate and a transparent conductive film, or the electrode substrate 1 in which the transparent substrate and the transparent conductive film are integrated varies depending on the shape and use conditions of the solar cell as described above, and thus is particularly limited. Generally, it is about 1 μm to 1 cm.

[Porous metal oxide semiconductor]
Examples of the porous metal oxide semiconductor 4 include, but are not limited to, titanium oxide, zinc oxide, tin oxide, and the like. Particularly, titanium dioxide and further anatase type titanium dioxide are preferable. Further, it is desirable that the metal oxide has few grain boundaries in order to reduce the electric resistance value. Further, in order to adsorb more sensitizing dye, the semiconductor layer is desirably porous, and specifically has a specific surface area of 10 to 200 m ² / g. Further, in order to increase the light absorption amount of the sensitizing dye, it is desirable to scatter the light by making the particle diameter of the oxide to be used wide.
Such a porous metal oxide semiconductor is not particularly limited and can be provided on the transparent conductive film 3 by a known method. For example, there are a sol-gel method, dispersion paste application, electrodeposition and electrodeposition. Further, the porous metal oxide semiconductor may be further subjected to a high temperature treatment in order to enhance the electronic contact between the semiconductor particles and improve the adhesion to the support.
The thickness of such a semiconductor layer is not particularly limited because the optimum value varies depending on the oxide used and its properties, but is 0.1 μm to 50 μm, preferably 5 to 30 μm.

[Sensitizing dye]
The sensitizing dye layer 5 is not particularly limited as long as it can be excited by sunlight and can inject electrons into the metal oxide semiconductor layer 4, and dyes generally used in dye-sensitized solar cells can be used. However, in order to improve the conversion efficiency, it is desirable that the absorption spectrum overlaps with the sunlight spectrum in a wide wavelength region and the light resistance is high. Although not particularly limited, a ruthenium complex, particularly a ruthenium polypyridine complex is desirable, and a ruthenium complex represented by Ru (L) 2 (X) 2 is more desirable. Here, L is 4,4′-dicarboxy-2,2′-bipyridine, or a quaternary ammonium salt thereof, and a polypyridine ligand into which a carboxyl group is introduced, and X is SCN, Cl, CN It is. Examples thereof include bis (4,4′-dicarboxy-2,2′-bipyridine) diisothiocyanate ruthenium complex.
Examples of other dyes include metal complex dyes other than ruthenium, such as iron complexes and copper complexes. Further examples include organic dyes such as cyan dyes, porphyrin dyes, polyene dyes, coumarin dyes, cyanine dyes, squaric acid dyes, styryl dyes, and eosin dyes. These dyes preferably have a bonding group with the metal oxide semiconductor layer in order to improve the efficiency of electron injection into the metal oxide semiconductor layer. The linking group is not particularly limited, but a carboxyl group, a sulfonic acid group and the like are desirable.

The method for adsorbing the sensitizing dye to the porous metal oxide semiconductor 4 is not particularly limited. For example, the porous metal oxide is dissolved in a solution in which the dye is dissolved at room temperature and atmospheric pressure. A method of immersing the electrode substrate 1 on which the physical semiconductor 4 is formed may be mentioned. It is desirable that the immersion time is appropriately adjusted so that a monomolecular film of the dye is uniformly formed on the semiconductor layer depending on the type of the semiconductor, the dye, the solvent, and the concentration of the dye used. In addition, what is necessary is just to perform the immersion under a heating in order to perform adsorption | suction effectively.
Examples of the solvent used to dissolve the sensitizing dye include alcohols such as ethanol, nitrogen compounds such as acetonitrile, ketones such as acetone, ethers such as diethyl ether, halogenated aliphatic hydrocarbons such as chloroform, Examples thereof include aliphatic hydrocarbons such as hexane, aromatic hydrocarbons such as benzene, and esters such as ethyl acetate. It is desirable that the dye concentration in the solution is appropriately adjusted according to the type of dye and solvent used. For example, a concentration of 5 × 10 ⁻⁵ mol / L or more is desirable.

[Electrolyte layer]
The electrolyte layer 7 includes a supporting electrolyte, a redox couple capable of reducing the oxidized sensitizing dye, and a solvent for dissolving them. The solvent is not particularly limited, and can be arbitrarily selected from a non-aqueous organic solvent, a room temperature molten salt, water, a protic organic solvent, etc., for example, acetonitrile, dimethylformamide, ethylmethylimidazolium bistrifluoromethylimide, methoxyacetonitrile. , Methoxypropionitrile, propylene carbonate, γ-butyllactone, and the like. Among them, methoxyacetonitrile, methoxypropionitrile, propylene carbonate, γ-butyllactone, and the like can be preferably used. Further, the solvent can be used after gelation.
Examples of the supporting electrolyte include lithium salts, imidazolium salts, and quaternary ammonium salts.

The oxidation-reduction pair is not particularly limited as long as it can be generally used in a battery or a solar battery. For example, a combination of a halogen diatomic molecule and a halide salt, a thiocyanate anion and Examples include a combination of two thiocyanate molecules, a polypyridyl cobalt complex, and organic redox such as hydroquinone. Among these, a combination of iodine molecules and iodide is particularly preferable.
The supporting electrolyte, the redox couple, and the like are not particularly limited because the optimum concentration differs depending on the solvent, the semiconductor electrode, the dye, and the like used, but is about 1 mmol / L to 5 mol / L.
Further, t-butylpyridine, 1,2-dimethyl-3-propylimidazolium iodide, water, and the like can be added to the electrolyte layer as additives.

[Counter electrode-electrode substrate]
The counter electrode 8 is provided with a catalytically active layer 10 on the electrode substrate 9 for reducing the redox couple. Since the electrode substrate 9 is used as a counter electrode support and current collector, at least the surface portion on which the catalytically active layer 10 is formed has conductivity.
As a material of such an electrode substrate, for example, conductive metal, metal oxide, carbon material, or the like is used. As the metal, a metal having high durability with respect to the electrolyte is preferable, and a metal that is inexpensive is desirable. When iodine is used as the redox pair, for example, nickel, titanium, stainless steel, a corrosion-resistant alloy, and the like can be given. Although it does not specifically limit as a carbon material, For example, graphite (graphite), carbon black, glassy carbon, a carbon nanotube, fullerene etc. are mentioned. In addition, metal oxides such as FTO, ITO, indium oxide, and zinc oxide are transparent or translucent, so that the amount of light incident on the sensitizing dye layer can be increased and can be preferably used.

  In addition, an insulator such as glass or plastic may be used as long as at least the surface of the electrode substrate is treated. As a treatment method for maintaining conductivity in such an insulator, a method of covering a part or the whole surface of the insulating material with the above-described conductive material, for example, when using a metal, plating, electrodeposition, etc. And a gas phase method such as sputtering or vacuum deposition. When a metal oxide is used, a sol-gel method or the like can be used. In addition, one or more of the above conductive material powders may be used and mixed with an insulating material. In particular, a glass electrode with FTO or ITO coating, the above metal plate, or the like can be suitably used.

The shape of the electrode substrate is not particularly limited because it can be changed according to the shape of the dye-sensitized solar cell used as the counter electrode, and may be a plate shape or a film shape that can be curved. Further, the electrode substrate may be transparent or opaque. However, it is desirable that the electrode substrate be transparent or translucent because the amount of light incident on the sensitizing dye layer can be increased and, in some cases, the design can be improved. . Generally, glass with an FTO film or a PEN film with an ITO film is used as the electrode substrate, but the conductivity is different depending on the material used, and therefore the thickness of the electrode substrate is not particularly limited. For example, in the FTO-coated glass, the thickness is 0.01 μm to 5 μm, preferably 0.1 μm to 1 μm. Further, the required conductivity varies depending on the area of the electrode to be used, and a wider electrode is required to have a lower resistance, but is generally 100Ω / □ or less, preferably 10Ω / □ or less, more preferably 5Ω. / □ or less. Exceeding 100Ω / □ is not preferable because the internal resistance of the solar cell increases and current does not sufficiently flow.
The thickness of the electrode substrate 9 is not particularly limited because it varies depending on the shape and use conditions of the solar cell as described above, but is generally about 1 μm to 1 cm.

[Counter electrode-catalytically active layer]
The catalytically active layer 10 in the present invention functions as a catalyst for a reduction reaction for reducing the oxidized form of the redox couple in the electrolyte to a reduced form, and is not particularly limited, and a known material can be used. Specifically, platinum, its alloy, and a conductive polymer are mentioned. The conductive polymer may be one or more homopolymers, one or more copolymers, or a mixture thereof. As the monomer for forming the conductive polymer, aniline, thiophene, pyrrole, and derivatives thereof can be used. Particularly, polyaniline and poly (3,4-ethylenedioxythiophene) can be preferably used.

The method for forming the catalytically active layer 10 is not particularly limited because the optimum method differs depending on the constituent materials, and can be formed by a known method. For example, when a catalytically active layer is formed using platinum or an alloy thereof, a gas phase method such as sputtering, ion plating, vacuum deposition, chemical vapor deposition, or a solution in which a platinum raw material such as chloroplatinic acid is dissolved is used. And a method in which a solution containing a platinum raw material is applied to an electrode substrate and then heated and reduced together with the electrode substrate.
Further, when forming a catalytically active layer using a conductive polymer, a method of forming a film from a solution in which the conductive polymer is dissolved or a dispersion solution of conductive polymer particles, or a conductive polymer is formed. For example, a method of forming a film by oxidative polymerization on the surface of the electrode substrate 9 by electrolyzing the electrode substrate 9 as a working electrode in a solution containing a monomer may be used.

[spacer]
In addition, in the dye-sensitized solar cell according to the present invention, a spacer 11 that defines a distance between both electrodes can be provided in a part between the counter electrode and the semiconductor electrode as necessary. Such a material of the spacer 11 is at least a non-conductive material, and examples thereof include glass and plastic. Since the space between the electrodes can be arbitrarily adjusted with a spacer, the shape and size thereof are not particularly limited, and any shape such as a sheet shape, a spherical shape, a fiber shape, or a rod shape can be used. At this time, since the distance between both electrodes is preferably 100 μm or less, more preferably 50 μm or less, the thickness or diameter of the spacer 11 is preferably 100 μm or less, more preferably 50 μm or less.

[Seal part-Resin component for seal]
The sealing material in the present invention includes both a semiconductor electrode and a counter electrode in the peripheral seal portion 12 of the dye-sensitized solar cell and the intermediate seal portion 13 that separates the cells of the solar cell module formed by arranging a plurality of the cells. Used to bond and seal between electrodes with a defined spacing. Hereinafter, both the seal portions will be referred to as seal portions. The sealing material includes a sealing resin component 14 and a conductive polymer 15, and the bonding and sealing function itself is mainly performed by the sealing resin component.

  The sealing resin component seals the inside of the cell and isolates it from the outside to prevent the passage of components that may affect the performance of the device, for example, active gas such as moisture, oxygen, carbon monoxide, etc. The material is not particularly limited as long as it can be used, and the composition can be appropriately selected from known materials according to the electrode material, the spacer material, and the electrolyte material to be bonded and sealed. Furthermore, it is desirable that the adhesive strength and moisture resistance, heat / cold resistance, and thermal shock resistance are high, and that the durability against the electrolyte component is high. In addition, in order to cope with the thermal expansion and contraction of the electrode due to heating during solar radiation, and when flexibility is required, it is desirable to have sufficient plasticity.

Specific examples of the materials include polyisobutylene resins, phenol resins, urea resins, epoxy resins, urethane acrylate resins, epoxy acrylate resins, silicone resins, curable resins such as polyamide, polystyrene resins, and the like. These thermoplastic resins can be mentioned. These may be used alone or as a mixture of two or more. Or even if it is the material which does not harden | cure alone, you may make it harden | cure by adding various hardening | curing agents, a crosslinking agent, etc. Further, various improvements may be made by modifying these or adding a filler. Among the above resins, polyisobutylene resins, epoxy resins, epoxy acrylate resins, silicone resins and the like are desirable.
Various curing methods such as a thermosetting type, a photocurable type, and an electron beam curable type can also be applied to the curing methods of these curable resins.
Further, the peripheral seal portion 12 and the intermediate seal portion 13 may use the same resin or different resins.

[Seal part-conductive polymer]
The conductive polymer 15 contained in the sealing material of the present invention includes a peripheral seal portion 12 of the dye-sensitized solar cell and an intermediate seal portion 13 that separates the cells of the solar cell module formed by arranging a plurality of the cells. In the above, the deterioration of the sealing resin component 14 is suppressed, and leakage and volatilization of the electrolytic solution are reduced, thereby increasing the long-term durability of the cell. In particular, it protects the sealing resin component from anions that promote the deterioration of the sealing resin component, and among them, iodide anions such as I ⁻ and I ₃ ⁻ .

The conductive polymer 15 of the present invention constitutes the conductive polymer so as to suppress the deterioration of the sealing resin component by interacting with the anionic electrolyte component that promotes the deterioration of the sealing resin component 14. A polymer formed by oxidative polymerization of the monomer is desirable. More desirably, it is a conductive polymer that has been oxidatively polymerized and is in a state in which the anionic dopant is eliminated.
In addition, the conductive polymer 15 in the seal portion increases the distribution ratio of the conductive polymer closer to the electrolyte in the sealing material so that the sealing resin component can be more effectively protected from the electrolyte component. It is desirable to distribute it. Furthermore, it is desirable that the conductive polymer farther away from the electrolyte is more densely polymerized in the sealing material so that the electrolyte component does not penetrate and leak inside the sealing material.

The conductive polymer in the present invention is not particularly limited, and a known conductive polymer can be used. The composition may also be one or more homopolymers, one or more copolymers, or a mixture thereof.
As a monomer that forms such a conductive polymer, for example, an aromatic amine compound represented by the following general formula (1) or (2), a thiophene compound represented by the following general formula (3), and the following general formula: And at least one monomer selected from the group consisting of pyrrole compounds represented by (4).

（式（１）又は（２）中、Ｒ₁及びＲ₆はそれぞれ独立に水素原子、メチル基又はエチル基を示し、Ｒ₂〜Ｒ₅及びＲ₇〜Ｒ₁₀はそれぞれ独立に水素原子、炭素原子数１〜８のアルキル基又はアルコキシ基、炭素原子数６〜１２のアリール基、炭素原子数６〜１２のアラルキル基（例えばベンジル基）、シアノ基、チオシアノ基、ハロゲン基、またはニトロ基を示し、式（１）中、Ｒ₂とＲ₃、又はＲ₄とＲ₅はそれぞれ連結して環を形成していてもよく、式（２）中、Ｒ₈とＲ₉、又はＲ₉とＲ₁₀はそれぞれ連結して環を形成していてもよい。）

(In the formula (1) or (2), R ₁ and R ₆ each independently represent a hydrogen atom, a methyl group or an ethyl group, and R _{2 to} R ₅ and R _{7 to} R ₁₀ each independently represent a hydrogen atom or carbon. An alkyl group or alkoxy group having 1 to 8 atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 6 to 12 carbon atoms (for example, benzyl group), a cyano group, a thiocyano group, a halogen group, or a nitro group; In formula (1), R ₂ and R ₃ , or R ₄ and R ₅ may be linked to form a ring, respectively, and in formula (2), R ₈ and R ₉ , or R ₉ and R ₁₀ may be linked to each other to form a ring.)

（式（３）中、Ｒ₁₁、Ｒ₁₂はそれぞれ独立に水素原子、炭素原子数１〜８のアルキル基又はアルコキシ基、炭素原子数６〜１２のアリール基、シアノ基、チオシアノ基、ハロゲン基、又はニトロ基を示し、Ｒ₁₁とＲ₁₂は連結して環を形成していてもよい。）

(In Formula (3), R ₁₁ and R ₁₂ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or an alkoxy group, an aryl group having 6 to 12 carbon atoms, a cyano group, a thiocyano group, and a halogen group. Or a nitro group, and R ₁₁ and R ₁₂ may be linked to form a ring.)

（式（４）中、Ｒ₁₃、Ｒ₁₄はそれぞれ独立に水素原子、炭素原子数１〜８のアルキル基又はアルコキシ基、炭素原子数６〜１２のアリール基、シアノ基、チオシアノ基、ハロゲン基、ニトロ基、又はアミノ基を示し、Ｒ₁₃とＲ₁₄は連結して環を形成していてもよい。）

(In Formula (4), R <_13> , R <_14> is respectively independently a hydrogen atom, a C1-C8 alkyl group or an alkoxy group, a C6-C12 aryl group, a cyano group, a thiocyano group, and a halogen group. Nitro group or amino group, R ₁₃ and R ₁₄ may be linked to form a ring.)

  Examples of the aromatic amine compound include aniline and aniline derivatives. More specifically, examples include aniline, anisidine, phenetidine, toluidine, phenylenediamine, hydroxyaniline, N-methylaniline, trifluoromethaneaniline, nitroaniline, cyanoaniline, and halogenated aniline. Of these, anisidine, toluidine, phenylenediamine and aniline are preferably used. Among them, aniline is particularly preferably used, and examples thereof include a polymer formed by polymerizing at least aniline as a monomer. In particular, polyaniline using aniline alone as a monomer can be suitably used at low cost.

Examples of the thiophene compound include thiophene and thiophene derivatives, and more specifically, alkylthiophenes such as thiophene, 3-methylthiophene, 3-butylthiophene, 3-octylthiophene, tetradecylthiophene, isothianaphthene, Examples include 3-phenylthiophene and 3,4-ethylenedioxythiophene. When used as a homopolymer, 3,4-ethylenedioxythiophene can be preferably used.
A conductive polymer may be formed using one or more thiophene compounds.

  Examples of the pyrrole compound include pyrrole and pyrrole derivatives, and examples of the pyrrole derivative include those having an alkyl group having 1 to 8 carbon atoms at the 3-position. Specific examples of the pyrrole compound include pyrrole, 3-methylpyrrole, 3-butylpyrrole and 3-octylpyrrole. The conductive polymer may be formed using one or more pyrrole compounds.

  The above aromatic amine compound, thiophene compound, and pyrrole compound may be used as one or more kinds, and may be one or more kinds of copolymers or a mixture thereof.

  A method for forming the conductive polymer 15 is not particularly limited, and a known method can be used. For example, a particulate conductive polymer can be easily obtained by a method of proceeding polymerization by adding an oxidizing agent to a solution containing a monomer of a conductive polymer (hereinafter referred to as “chemical polymerization method”). Can do. A production method using such a chemical polymerization method can be suitably used because it is simple and has high productivity. At this time, it is desirable to desorb the dopant as described above by a method such as solution washing or dipping. Thereafter, the conductive polymer is mixed with a sealing resin component to obtain a sealing material.

  In addition, as another desirable method for forming a conductive polymer, once the particulate conductive polymer powder obtained by the chemical polymerization is fractionated, it is dissolved again in a solvent to obtain a solution of the conductive polymer. Can be produced. Examples of a method for forming the sealing material of the present invention using the solution capable include, for example, a method in which the solution is mixed with a resin component for sealing and then the solvent is dried, or a resin component for sealing is previously provided in the seal portion. After that, before curing and adhering, the conductive polymer solution can be mixed with the sealing resin component by injection, application, impregnation or the like and then cured and adhered.

Alternatively, a conductive polymer layer can be formed on the surface of the conductive substrate by electrochemical polymerization (hereinafter referred to as “electrolytic polymerization method”) using a separately prepared conductive substrate as an electrode. Since such an electropolymerization method can electrically control the polymerization of the conductive polymer in a room temperature air atmosphere, the thickness and denseness of the conductive polymer layer can be optimally adjusted. It can be preferably used. The method of electrolytic polymerization is not particularly limited and can be carried out by a known method.
As a method of forming the sealing material of the present invention using the conductive polymer obtained by such electrolytic polymerization, the generated conductive polymer film is peeled from the conductive substrate and physically pulverized. It is possible to adopt a method such as injecting and installing a sealing resin component after the powder is formed into a powder or after being placed in the seal portion in the same shape.

  Furthermore, in the present invention, a method of conducting polymerization of the conductive polymer inside the sealing material can be adopted. As such a method, an electrolytic polymerization method can be used. For example, the monomer containing the monomer constituting the conductive polymer is mixed with the sealing resin component by a method such as coating or impregnation, and then mixed with the sealing resin component by applying a voltage from the outside. And the like, and a method of finally removing the solvent. In such a case, the conductive polymer may be formed and then provided on the seal portion to be sealed and bonded, or the sealing resin component containing the monomer component in advance may be provided on the seal portion before electrolysis. It may be polymerized. In the case where the sealing resin component is a thermosetting resin, the heating step may serve both as the removal of the solvent for electrolytic polymerization and the curing of the sealing resin component.

  Further, as another method for polymerizing the conductive polymer inside the sealing material, a chemical polymerization method can be used. A solution containing a monomer of a conductive polymer and a polymerization catalyst is mixed with a sealing resin component by a method such as coating or impregnation, and then heat-treated, thereby chemically treating the monomer mixed with the sealing resin component. There is a method in which polymerization is advanced by polymerization and finally the solvent is removed. At this time, as long as the sealing resin component can be thermoset, the sealing resin component 14 may be cured simultaneously with the heat treatment and the solvent removal when the conductive polymer is polymerized.

  The method of polymerizing the conductive polymer inside the sealing material as described above may cause a crosslinking reaction between the conductive polymer and the sealing resin component, and as a result, the portion of the sealing resin component in contact with the conductive polymer. Since the chemical stability of can be improved, it can utilize suitably. Also in the method of forming a sealing material by mixing a prepolymerized conductive polymer with a sealing resin component, it is desirable to crosslink the conductive polymer and the sealing resin component. Examples of such a method include a method of adding a crosslinking agent capable of reacting with the conductive polymer into the sealing resin component.

The method of sealing a cell using said sealing material is not specifically limited, Various well-known methods are applicable. For example, the sealing material is formed on the electrode substrate in a desired shape using printing, spraying, a known application such as dispenser, carrying, or injection. At this time, the sealing material may be applied to the electrodes only on one or both of the pair of substrates. Thereafter, the gap between the semiconductor electrode and the counter electrode is adjusted and bonded together by an arbitrary method, and then the sealing material is solidified and sealed. Note that a spacer material may be added to the sealing material. Further, in order to improve the adhesive force between the sealing resin component and the adherend, it is desirable to perform a primer treatment on the adherend surface. As such a primer, a known material such as a silane coupling agent can be used.
At this time, the order of steps such as formation of the sealing material, bonding of both electrodes and injection of the electrolyte is appropriately changed depending on the shape of the cell to be manufactured and various materials, and thus is not particularly limited.
Since the optimum value of the width of the sealing material varies depending on the electrolyte component and electrode material to be sealed, it is not particularly limited, but is preferably 1 mm or more, and more preferably 3 mm or more.

  The reason why the sealing material of the present invention has high durability by suppressing the deterioration of the performance over time is considered as follows. That is, 1) the conductive polymer itself contained in the sealing material has high durability against an anionic component that promotes the deterioration of the electrolyte component, particularly the resin component for sealing, particularly iodide anion. The conductive polymer can occlude and hold the anion, particularly the iodide anion, as a dopant, thereby suppressing the diffusion of the anion and the chemical reaction with the sealing resin component. It is possible to reduce deterioration of the sealing resin component 14, 3) As a result, it is possible to reduce leakage and volatilization of the electrolyte, and 4) to stably hold iodine having sublimation as a dopant, which is an essential constituent material. For example, the loss of the redox couple can be reduced.

Thus, a sealing material composed of the sealing resin component and the conductive material is obtained.
After preparing each component material of the dye-sensitized solar cell as described above, the metal oxide semiconductor electrode and the counter electrode are assembled to face each other through an electrolyte by a conventionally known method, and the sealing material of the present invention By sealing with. A dye-sensitized solar cell is completed.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited at all by these.
〔Example〕
[Porous metal oxide semiconductor]
As a transparent substrate with a transparent conductive film, FTO glass (Nippon Sheet Glass 25 mm × 30 mm) was used, and a 50 nm thick titanium oxide thin film layer was formed on the surface by sputtering. Further, a titanium oxide paste (Titania Paste PST-18NR manufactured by Catalytic Chemical Industry Co., Ltd.) was applied to the surface of the titanium oxide thin film layer with a bar coater, dried at 100 ° C. for 1 hour, and then fired at 550 ° C. for 120 minutes in an air atmosphere. Then, it was left as it was until it reached room temperature to form a porous titanium oxide semiconductor layer having a thickness of 10 μm. Furthermore, a titanium oxide paste (Titania Paste PST-400C manufactured by Catalytic Chemical Industry Co., Ltd.) was applied on the porous titanium oxide semiconductor layer by a bar coater and then fired in the same manner to obtain a porous material having a thickness of 15 μm. A quality titanium oxide semiconductor electrode was completed.

[Adsorption of sensitizing dye]
As a sensitizing dye, a bis (4,4′-dicarboxy-2,2′-bipyridine) diisothiocyanate ruthenium complex generally called N3dye was used. The porous titanium oxide semiconductor electrode once heated to 150 ° C. was immersed in an ethanol solution having a pigment concentration of 0.5 mmol / L, and left standing under light shielding overnight. Thereafter, excess dye was washed with ethanol and then air-dried, and then the semiconductor electrode to which the dye was adsorbed was ground so as to be 6 mm square, thereby completing a semiconductor electrode of a solar cell.
[Counter electrode]
As a counter electrode, a glass with a Pt sputtered film (manufactured by Geomat Co., Ltd.) obtained by sputtering soda lime glass as a substrate, titanium at 30 nm, and platinum at 270 nm on the titanium layer was cut into 25 mm × 30 mm and used.

[Preparation of sealing material]
To a 1 wt% pyrrole aqueous solution cooled with ice at 5 ° C. or less, 2.5 times equivalent amount of ammonium persulfate was dropped while stirring, and pyrrole was polymerized by continuing stirring for 20 hours while cooling with ice. The resulting black powder of polypyrrole was washed with pure water, methanol, and acetone in this order to wash pyrrole, oxidant residue, and pyrrole oligomer. Next, the resulting polypyrrole powder was desorbed by stirring in a 5% aqueous ammonia solution for 1 hour, and then sufficiently washed with pure water.
On the other hand, a silicone-based resin sealing agent (LHR-120S manufactured by Shin-Etsu Polymer Co., Ltd.) was used as a sealing resin component constituting the sealing material. The prepared polypyrrole powder was vacuum dried at 100 ° C. for 20 hours with respect to this sealing resin component, and then added and mixed at a blending ratio of 30 wt% to prepare a sealing material.

[Assembly of solar cells]
After placing the 25 μm-thick fluororesin film with the sealing material applied on both sides in advance on the semiconductor electrode produced as described above as a separator, the pre-drying step was heated at 60 ° C. for 10 minutes, A counter electrode was bonded so as to face the semiconductor electrode. Subsequently, the sealing material was applied to the outer edge portion of the bonded electrodes in an annular shape, and then heat-treated at 120 ° C. for 30 minutes to cure the sealing material. However, two portions of the sealing material are removed as sealing ports for sealing the electrolytic solution before applying the sealing material and before curing. After the sealing material is cured, the electrolyte is impregnated between the two electrodes by capillary action from one of the sealing ports, and the electrolyte is inserted while removing the bubbles between the two electrodes by reducing the pressure from the other, and the sealing port is cured at room temperature. A solar battery cell was assembled by encapsulating with a conductive resin. As an electrolyte, a solution containing methoxypropionitrile as a solvent, lithium iodide as a reducing agent, iodine as an oxidizing agent, n-methylbenzimidazole and 1,2-dimethyl-3-propylimidazolium iodide as additives is used. It was.

[Measurement of photoelectric conversion characteristics of solar cells]
About the above-mentioned solar battery cell, after mounting a black shielding mask for defining the light irradiation area with a 5 mm square window, pseudo-sunlight with a light amount of 100 mW / cm ² was irradiated to open voltage (hereinafter referred to as “Voc”). ), Short-circuit current density (hereinafter abbreviated as “Jsc”), shape factor (hereinafter abbreviated as “FF”), and photoelectric conversion efficiency, the following results were obtained. .
About each measured value of "Voc", "Jsc", "FF", and a photoelectric conversion efficiency, it represents that a larger value is preferable as a performance of a photovoltaic cell.

[Measurement results of Examples]
Open-circuit voltage (Voc): 0.65V
Short circuit current density (Jsc): 11.5 mA / cm ²
Form factor (FF): 0.64
Photoelectric conversion efficiency: 4.8%

[Durability test of solar cells]
The solar battery cell was subjected to a constant temperature holding test at 85 ° C., and the photoelectric conversion characteristics after 500 hours were measured. As a result, a 96% holding ratio was obtained.
[Durability Test Results of Examples]
Open circuit voltage (Voc): 0.67V
Short circuit current density (Jsc): 11.1 mA / cm ²
Form factor (FF): 0.62
Photoelectric conversion efficiency: 4.6%

[Comparative example]
In the production of the sealing material, except that polypyrrole fine particles, which are conductive polymers, were added, solar cells were produced in the same manner as in the examples, and the durability test similar to the examples was performed. The electrolyte solution leaked without being able to perform photoelectric conversion.
[Measurement results before durability test]
Open-circuit voltage (Voc): 0.66V
Short circuit current density (Jsc): 11.3 mA / cm ²
Form factor (FF): 0.64
Photoelectric conversion efficiency: 4.8%

  From the above results, it can be seen that the dye-sensitized solar cell provided with the sealing material of the present invention has high durability.

  In view of the above circumstances, the present invention is a dye-sensitized solar cell sealing material, which is used for a dye-sensitized solar cell by including a sealing resin component and a conductive polymer. A sealing material having excellent resistance to iodine as an electrolyte component, particularly an oxidation-reduction pair, and, as a result, a highly reliable sealing performance, and a dye-sensitized solar cell using the sealing material, or A dye-sensitized solar cell module can be provided.

It is a cross-sectional schematic diagram which shows an example of a structure of the dye-sensitized solar cell of this invention. It is a cross-sectional schematic diagram which shows an example of the dye-sensitized solar cell module using the sealing material of this invention. It is an expanded schematic diagram of the cross section showing an example of the dye-sensitized solar cell using the sealing material of this invention. It is an expanded schematic diagram of the cross section showing an example of the dye-sensitized solar cell using the sealing material of this invention. It is an expanded schematic diagram of the cross section showing an example of the dye-sensitized solar cell using the sealing material of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrode base body 2 Transparent base body 3 Transparent electrically conductive film 4 Porous metal oxide semiconductor layer 5 Sensitizing dye layer 6 Semiconductor electrode 7 Electrolyte layer 8 Counter electrode 9 Electrode base body 10 Catalytic active layer 11 Spacer 12 Peripheral seal part 13 Intermediate seal part 14 Seal Resin component 15 Conductive polymer

Claims (10)

A porous metal oxide semiconductor electrode containing a dye having a photosensitizing action;
In a resin sealing material used for a dye-sensitized solar cell having an electrolyte containing a chemical species that becomes a redox pair enclosed between a counter electrode disposed opposite to the semiconductor electrode,
The sealing material for dye-sensitized solar cells characterized by including a conductive polymer in a resin component.   The dye-sensitized solar cell sealing material according to claim 1, wherein the conductive polymer can occlude anions.   3. The dye-sensitized solar cell sealing material according to claim 1, wherein the conductive polymer dopant is desorbed.   The dye-sensitized solar cell sealing material according to any one of claims 1 to 3, wherein the conductive polymer is chemically crosslinked with the resin component.   5. The dye-sensitized solar cell sealing material according to claim 1, wherein the conductive polymer is a conductive polymer obtained by polymerizing a monomer component in a resin component.   6. The monomer constituting the conductive polymer is at least one selected from the group consisting of aniline and derivatives thereof, pyrrole and derivatives thereof, thiophene and derivatives thereof. The sealing material for dye-sensitized solar cells as described.   The sealing material for a dye-sensitized solar cell according to any one of claims 1 to 6, wherein the distribution ratio of the conductive polymer increases as the electrolyte is closer to the inside of the sealing material.   8. The dye-sensitized solar cell sealing material according to claim 1, wherein a conductive polymer farther from the electrolyte is more densely polymerized inside the sealing material. 9. In a dye-sensitized solar cell in which an electrolyte is sealed between a semiconductor electrode and a counter electrode arranged to face each other,
The peripheral part of this dye-sensitized solar cell is sealed with the sealing material for dye-sensitized solar cells in any one of Claims 1-8, The dye-sensitized solar cell characterized by the above-mentioned. A module for a dye-sensitized solar cell having a plurality of dye-sensitized solar cells in which an electrolyte is sealed between a semiconductor electrode and a counter electrode disposed so as to face each other and a peripheral portion of the dye-sensitized solar cell is sealed In
At least a part of the electrode surface of the dye-sensitized solar cell is partitioned by the sealing material for a dye-sensitized solar cell according to any one of claims 1 to 8, and has a pair of semiconductor electrodes and a counter electrode. A dye-sensitized solar cell module comprising a plurality of solar cells.

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