JP5786286B2 - Counter electrode for dye-sensitized solar cell, dye-sensitized solar cell, and method for manufacturing counter electrode - Google Patents

Description

  The present invention relates to a counter electrode for a dye-sensitized solar cell, a dye-sensitized solar cell, and a method for manufacturing the counter electrode.

  It has already been reported by Gretzell et al. That a dye-sensitized solar cell having performance comparable to that of an amorphous silicon solar cell can be obtained by using a porous titanium oxide electrode (J. Am. Chem. Soc. 115 (1993) 6382). In recent years, application development research on dye-sensitized solar cells has been actively conducted at various research institutions both in Japan and overseas.

  A general structure of a dye-sensitized solar cell includes a working electrode having a metal oxide layer (metal oxide semiconductor) carrying a sensitizing dye on a conductive substrate, and a catalyst layer on the conductive substrate. A structure in which an electrolytic solution (electrolyte) is sandwiched between a counter electrode (counter electrode) is widely known.

  Conventionally, a thin film such as a sputtered Pt film or a plated film has been used as the catalyst layer of the counter electrode. However, the use of Pt, which is a noble metal, is a big problem in terms of cost. Therefore, recently, attempts have been made to use carbon as a catalyst layer. As a method for producing a counter electrode using carbon for the catalyst layer (hereinafter also referred to as “carbon counter electrode”), for example, a paste or slurry containing carbon particles and an organometallic compound or metal salt is printed on a glass substrate. A method of forming a film is known by applying it by a method or the like and then heating and sintering at 300 to 600 ° C. (see Patent Document 1).

  In order for this type of carbon counter electrode to fully perform its function, a strong bond between the carbon particles and a strong bond between the carbon particles and the surface of the conductive substrate are very important. In order to achieve this object, conventionally, a coating liquid such as a paste or a slurry to which an appropriate amount of an organic binder component such as polyethylene glycol is added is prepared, and this coating liquid is applied onto a substrate, and thereafter, a temperature of 400 ° C. or higher. It has been common to form a catalyst layer by baking at a high temperature.

  However, in such a method that requires high-temperature baking treatment, the substrate may be damaged, so that a substrate containing a resin material cannot be used in practice, and as a result, the use of the obtained electrode is limited. There was a problem. In addition, since the amount of applied energy is large, there is also a problem that the environmental load is large.

  On the other hand, in order to omit the high-temperature baking treatment, attempts have been made to blend a relatively large amount of organic binder into the coating solution. In this case, although the effect of improving the mechanical strength of the catalyst layer is recognized, there may be a problem that the battery characteristics are remarkably deteriorated due to, for example, the organic binder component in the film being dissolved into the electrolytic solution.

  Therefore, a fibrous carbon having a diameter of nanometer size, more specifically, a nanocarbon film made of at least one carbon material selected from the group consisting of single wall carbon nanotubes, multiwall carbon nanotubes, and carbon nanofibers. Attempts have been made to obtain a thin film having excellent mechanical strength without using an additive such as a binder by constituting the electrode (see Patent Document 2).

JP 2005-302390 A Japanese Patent Laid-Open No. 2004-111216

  According to the technique described in Patent Document 2, it can be understood that the mechanical strength can be improved by the entanglement of the fibrous carbon material even without binder. However, fibrous carbon materials, particularly single-wall carbon nanotubes, are very expensive, and there is a problem that they deviate significantly from the original purpose of cost reduction by substitution of Pt.

  The present invention has been made in view of such circumstances, and the object thereof is excellent in the mechanical strength (film strength, adhesion strength) of the carbon catalyst layer without excessively impairing the battery characteristics of the dye-sensitized solar cell. The object is to provide a dye-sensitized solar cell counter electrode capable of improving durability (long-term reliability). Another object of the present invention is to provide a dye-sensitized solar cell that is excellent in battery characteristics and durability. Furthermore, another object of the present invention is to provide a production method capable of producing a counter electrode excellent in mechanical strength (film strength, adhesion strength) of a carbon catalyst layer easily and at low cost with high reproducibility. .

  As a result of intensive studies, the present inventors have found that the above problems can be solved by using a polymer type anionic surfactant together with conductive carbon particles, and have completed the present invention.

  That is, the counter electrode for a dye-sensitized solar cell of the present invention has a substrate having a conductive surface and a carbon catalyst layer provided on at least a part of the conductive surface, and the carbon catalyst layer includes: , Containing conductive carbon particles and a polymer type anionic surfactant.

  The present inventors have measured the characteristics of a dye-sensitized solar cell in which the counter electrode for the dye-sensitized solar cell and the working electrode configured as described above are arranged to face each other and an electrolyte is provided therebetween. Compared with the conventional organic binder component, the durability (long-term reliability) is remarkably enhanced, and furthermore, the battery characteristics that are unavoidably associated with the organic binder component. It has been found that even the decline in the number is suppressed significantly. The details of the mechanism of action that produces this effect are not yet clear, but are estimated as follows, for example.

  In the counter electrode for the dye-sensitized solar cell having the above-described configuration, since the polymer type anionic surfactant is used in combination with the conductive carbon particles, the conductive carbon particles and the conductive carbon particles and the conductive surface are used. (For example, in the case of a transparent conductive film, usually, a metal element such as In or Sn) can be strongly bonded or interacted with. Therefore, the mechanical strength and adhesion strength of the carbon catalyst layer can be significantly increased. In addition, since the dispersibility of the conductive carbon particles can be improved by blending the polymer-type anionic surfactant, the carbon catalyst layer containing the conductive carbon particles and the polymer-type anionic surfactant is the above-mentioned conventional organic binder component. Compared to the case where is used, a fine porous structure excellent in mechanical strength and adhesion strength can be adopted. Furthermore, the surface of the conductive carbon particles becomes charged due to the interaction of the anionic group on the surface of the conductive carbon particles, and the conductive carbon particles are more in comparison with the case where the conventional organic binder component is used. It is considered that the wettability of the electrolyte on the surface is improved and the electrolyte is drawn into the porous structure. This is considered to be particularly remarkable when the electrolyte contains an ionic substance or a polar substance. As a result of a combination of these actions, in the counter electrode for the dye-sensitized solar cell having the above-described configuration, unlike the case of using the organic binder component described in the above prior art, the battery characteristics are not excessively impaired, and the durability is improved. It is considered that the reliability (long-term reliability) has been improved. However, the action is not limited to these.

  In the above, the carbon catalyst layer preferably has a porous structure in which the conductive carbon particles are aggregated and / or bonded. By configuring such a carbon catalyst layer having a porous structure, the surface area is dramatically increased, and the electrolyte is drawn into the carbon catalyst layer. As a result, the reaction point of photoelectric conversion (redox reaction) is increased. This increases the battery characteristics.

  Furthermore, it is preferable that the polymer type anionic surfactant described above is contained in an amount of 0.5 to 30 wt% with respect to the conductive carbon particles. By adjusting the content of the polymer-type anionic surfactant to this range, both battery characteristics and durability (long-term reliability) that cannot be achieved in the past can be achieved.

  The dye-sensitized solar cell of the present invention can effectively use the counter electrode for a dye-sensitized solar cell of the present invention, and has a base having a conductive surface and at least one on the conductive surface. A working electrode having a dye-carrying metal oxide layer provided on the surface, a counter electrode having a substrate having a conductive surface and a carbon catalyst layer provided on at least a part of the conductive surface, and the function An electrolyte provided between an electrode and the counter electrode, wherein the carbon catalyst layer contains conductive carbon particles and a polymer-type anionic surfactant. For the same reason as described above, the carbon catalyst layer preferably has a porous structure in which conductive carbon particles are aggregated and / or bonded, and the polymer type anionic surfactant is based on the conductive carbon particles. It is preferable that 0.5-30 wt% is contained.

  The counter electrode manufacturing method of the present invention can effectively manufacture the counter electrode for a dye-sensitized solar cell of the present invention, and is provided on a substrate having a conductive surface and the conductive surface. A method for producing a counter electrode having a carbon catalyst layer, the step of preparing a preparation containing conductive carbon particles and a polymer type anionic surfactant, and the preparation having a conductive surface of the substrate And a step of imparting to. According to this production method, a counter electrode excellent in mechanical strength (film strength, adhesion strength) of the carbon catalyst layer can be produced easily and stably at low cost with good reproducibility.

  ADVANTAGE OF THE INVENTION According to this invention, the counter electrode for dye-sensitized solar cells which is excellent in the mechanical strength of a carbon catalyst layer, and can improve durability, without impairing the battery characteristic of a dye-sensitized solar cell excessively is provided. A dye-sensitized solar cell that is realized and has excellent battery characteristics and durability is realized. In addition, since such a working electrode does not require a high-temperature firing process as in the prior art, and can be manufactured easily, at low cost and stably with high reproducibility, productivity and economy are improved.

1 is a cross-sectional view showing a schematic configuration of a dye-sensitized solar cell 100 and a counter electrode 14.

  Embodiments of the present invention will be described below. In addition, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the illustrated ratios. The following embodiments are examples for explaining the present invention, and the present invention is not limited only to the embodiments.

FIG. 1 is a cross-sectional view showing a schematic configuration of the dye-sensitized solar cell of the present embodiment.
The dye-sensitized solar cell 100 includes a working electrode 11 (dye-carrying electrode, photoelectric conversion electrode), a counter electrode 21, and an electrolyte 31 provided between the working electrode 11 and the counter electrode 21. The working electrode 11 and the counter electrode 21 are arranged to face each other via a spacer 41, and an electrolyte 31 is placed in a sealed space defined by the working electrode 11, the counter electrode 21, the spacer 41, and a sealing member (not shown). It is enclosed.

  The working electrode 11 includes a substrate 12 having a conductive surface 12a and a porous metal oxide layer 13 formed on the conductive surface 12a. A sensitizing dye is supported (adsorbed) on the metal oxide layer 13. As a result, the dye-supported metal oxide layer 14 is formed. In other words, the working electrode 11 of the present embodiment includes a dye-supported metal oxide layer 14, that is, a composite structure in which a sensitizing dye is supported (adsorbed) on the surface of the metal oxide. It is the structure laminated | stacked on 12a.

  The type and size of the substrate 12 are not particularly limited as long as at least the metal oxide layer 13 can be supported. For example, a plate-like or sheet-like material is preferably used. Specific examples thereof include glass substrates, plastic substrates such as polyethylene terephthalate, polyethylene, polypropylene, and polystyrene, metal substrates, alloy substrates, ceramic substrates, and laminates thereof. Moreover, it is preferable that the base | substrate 12 has translucency, and the thing excellent in the translucency in visible region is more preferable. Further, the base 12 is preferably flexible. In this case, it is possible to provide various types of structures utilizing the flexibility.

The conductive surface 12a can be applied to the substrate 12 by, for example, forming a transparent conductive film on a part or the entire surface of the substrate 12 like a conductive PET film. Moreover, the process which provides the electroconductive surface 12a to the base | substrate 12 can be skipped by using the base | substrate 12 which has electroconductivity. Specific examples of the transparent conductive film include indium-tin oxide (ITO), indium-zinc oxide (IZO), SnO ₂ , InO ₃ , and FTO in which SnO ₂ is doped with fluorine. However, it is not particularly limited to these. These may be used alone or in combination. The formation method of a transparent conductive film is not specifically limited, For example, well-known methods, such as a vapor deposition method, CVD method, a spray method, a spin coat method, or an immersion method, are applicable. Moreover, the film thickness of a transparent conductive film can be set suitably. The conductive surface 12a of the substrate 12 may be subjected to appropriate surface modification treatment as necessary. Specifically, for example, a known surface treatment such as a degreasing treatment with a surfactant, an organic solvent or an alkaline aqueous solution, a mechanical polishing treatment, an immersion treatment in an aqueous solution, a preliminary electrolytic treatment with an electrolytic solution, a water washing treatment, a drying treatment, etc. However, it is not particularly limited to these.

The metal oxide layer 13 is a porous semiconductor layer mainly composed of a metal oxide such as TiO ₂ , ZnO, SnO ₂ , ZrO ₂ , SiO ₂ , Al ₂ O ₃ , WO ₃ , and Nb ₂ O _5. . The metal oxide layer 13 is made of metal such as titanium, tin, zinc, iron, tungsten, zirconium, strontium, indium, cerium, vanadium, niobium, tantalum, cadmium, lead, antimony, bismuth, these metal oxides and these A metal chalcogenide may be included. In addition, although the thickness of the metal oxide layer 13 is not specifically limited, It is preferable that it is 0.05-50 micrometers.

  The formation method of the metal oxide layer 13 is not specifically limited, A well-known method is applicable. For example, a method (slurry, sol, etc.) containing metal oxide particles is applied to the conductive surface 12a of the substrate 12 and then sintered, or such a formulation is applied to the conductive surface 12a of the substrate 12. And a method of performing low-temperature treatment at about 50 to 150 ° C., preferably about 70 to 150 ° C. According to these methods, the metal oxide layer 13 having a porous structure in which metal oxide particles are aggregated and / or bonded can be easily obtained. Among these, the latter method of performing a low-temperature treatment at about 50 to 150 ° C. is preferable from the viewpoint that the substrate containing the resin can be used and the applied energy amount can be reduced to reduce the environmental load. In addition, the application | coating method to the electroconductive surface 12a of the base | substrate 12 of a formulation is not specifically limited, A conventionally well-known coating method etc. are applicable.

  The preparation containing the metal oxide particles is preferably a preparation liquid containing a dispersion medium (for example, a dispersion liquid, a sol liquid or a slurry liquid). Specific examples of the dispersion medium include, but are not limited to, various organic solvents such as water, methanol, ethanol, isopropyl alcohol, butanol, dichloromethane, acetone, acetonitrile, ethyl acetate, toluene, dimethylformamide, ethoxyethanol, and cyclohexanone. Is mentioned. These may be used alone or in combination. Moreover, auxiliary agents, such as other surfactant, an acid, a chelating agent, may be included as needed.

  The sensitizing dye supported on the metal oxide layer 13 is not particularly limited, and may be any of a water-soluble dye, a water-insoluble dye, and an oil-soluble dye. Depending on the performance required as a photoelectric conversion element, one having a desired light absorption band / absorption spectrum can be appropriately selected. Specific examples of the sensitizing dye include, for example, xanthene dyes such as eosin Y, coumarin dyes, triphenylmethane dyes, cyanine dyes, merocyanine dyes, phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes, In addition to polypyridine metal complex dyes, ruthenium bipyridium dyes, azo dyes, quinone dyes, quinone imine dyes, quinacridone dyes, squalium dyes, perylene dyes, indigo dyes, oxonol dyes, polymethine dyes, Examples include riboflavin dyes, but are not particularly limited thereto. These may be used alone or in combination. Further, from the viewpoint of increasing the amount of the dye supported, the sensitizing dye preferably has an adsorptive group that interacts with the metal oxide. Specific examples of the adsorptive group include, but are not limited to, a carboxyl group, a sulfonic acid group, and a phosphoric acid group.

  The method for supporting the sensitizing dye on the metal oxide layer 13 is not particularly limited, and a known forming method can be applied. Specifically, for example, a method of immersing the metal oxide layer 13 in a solution containing a sensitizing dye, a method of applying a solution containing a sensitizing dye to the metal oxide layer 13 and the like can be given. The solvent of the sensitizing dye-containing solution used here is appropriately selected from known solvents such as water, ethanol-based solvent, nitrile-based solvent, and ketone-based solvent, depending on the solubility or compatibility of the sensitizing dye to be used. Can be selected.

  The working electrode 11 may have an intermediate layer between the conductive surface 12a of the base 12 and the metal oxide layer 13 (dye-carrying metal oxide layer 14). Although the material of an intermediate | middle layer is not specifically limited, For example, the metal oxide etc. which were demonstrated with the transparent conductive film of said electroconductive surface 12a are preferable. The intermediate layer is formed by depositing or depositing a metal oxide on the conductive surface 12a of the substrate 12 by a known method such as vapor deposition, CVD, spraying, spin coating, dipping, or electrodeposition. Can be formed. Note that the intermediate layer preferably has translucency, and more preferably has conductivity. The thickness of the intermediate layer is not particularly limited, but is preferably about 0.1 to 5 μm.

  The counter electrode 21 includes a base 22 having a conductive surface 22a and a porous carbon catalyst layer 23 formed on the conductive surface 22a. The carbon catalyst layer 23 is a metal oxide layer 13 ( The dye-supporting metal oxide layer 14) is disposed so as to face the dye-supporting metal oxide layer 14). The base 22 and the conductive surface 22a correspond to the base 12 and the conductive surface 12a described above, and well-known ones can be used as appropriate, and the base 12 and the conductive surface 12a What has been described can be suitably used. As a specific example of the substrate 22 having the conductive surface 22a, for example, in addition to the conductive substrate 12, the conductive surface 12a is formed on a part of or the entire surface of the substrate 12 by forming a transparent conductive film. In addition, a conductive layer formed on the conductive surface 12a of the substrate 12 as a conductive layer is formed with a metal such as platinum, gold, silver, copper, aluminum, indium, molybdenum, titanium, or a film of a conductive polymer. It is done.

  The carbon catalyst layer 23 contains conductive carbon particles and a polymer type anionic surfactant. The carbon catalyst layer 23 preferably has a porous structure mainly composed of conductive carbon particles. The carbon catalyst layer 23 having a porous structure tends to have a large surface area and excellent battery characteristics.

  Specific examples of the conductive carbon particles constituting the carbon catalyst layer 23 include, for example, carbon black, graphite, glass carbon, amorphous carbon, hard carbon, soft carbon, carbon whisker, carbon nanotube, and fullerene. It is not specifically limited to. These may be used alone or in combination. In addition, the thickness of the carbon catalyst layer 23 is not particularly limited, but is preferably 0.05 to 50 μm.

  The polymer-type anionic surfactant contained in the carbon catalyst layer 23 means a surfactant having at least one anionic functional group or a salt thereof in the molecule and having a repeating structural unit. By including a polymer-type anionic surfactant in the carbon catalyst layer 23, mechanical strength (film strength, adhesion strength) is dramatically improved, and unlike the above-described conventional method of adding an organic binder, durability ( A dye-sensitized solar cell excellent in long-term reliability) and battery characteristics (particularly initial characteristics) can be realized. Here, specific examples of the anionic functional group or a salt thereof are not particularly limited, and examples thereof include an adsorbing group such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group, and an ester salt thereof. Further, the repeating structural unit and the number of repeating units are not particularly limited, but the molecular weight of the polymer type anionic surfactant is preferably 1000 or more and 10,000 or less. If the molecular weight of the polymer type anionic surfactant is small, the effect of improving the mechanical strength (film strength, adhesion strength) and durability (long-term reliability) tends to be small, and the molecular weight of the polymer type anionic surfactant is low. If it is large, battery characteristics tend to deteriorate. As anionic surfactants, for example, fatty acid sodium, monoalkyl sulfate, alkyl polyoxyethylene sulfate, alkyl benzene sulfonate, monoalkyl phosphate, alkyl polyoxyethylene phosphate are known. Yes.

  A preferred polymer type anionic surfactant is a polymer type anionic surfactant having a phosphate group. The polymer type surfactant having a phosphoric acid group has a low-bubble property among the surfactants. Therefore, in the case where the carbon catalyst layer 23 is formed using a preparation containing conductive carbon particles and a polymeric surfactant having a phosphate group, in a preparation (slurry, sol, etc.) containing conductive carbon particles. The generation of bubbles can be suppressed, and as a result, the mechanical strength of the carbon catalyst layer 23 can be further increased. In general, since air bubbles mixed in a preparation containing conductive carbon particles are also taken into the coating film (conductive carbon particle film, carbon catalyst layer 23), the mechanical strength of the formed carbon catalyst layer 23 is reduced. Can cause. Therefore, it is preferable to use a low-bubble type polymer surfactant such as a polymer surfactant having a phosphate group as the polymer anionic surfactant. In addition, since the phosphate group can form a strong bond with a constituent element of the transparent electrode (for example, a metal element such as In or Sn), the adhesion strength can be improved by using a polymer type surfactant having a phosphate group. It is further enhanced.

  Specific examples of the polymer type anionic surfactant having a phosphoric acid group include, for example, those having an alkyl group having phosphoric acid as a side chain in the polymer main chain, more specifically, for example, polyoxyethylene alkyl ether Examples thereof include phosphoric acid and polyoxyethylene alkylphenyl ether phosphoric acid. Although carbon number of the alkyl group contained in these is not specifically limited, About 12-20 is preferable and the length of the alkyl group contained in a molecule | numerator may be single or different. Typical examples include polyoxyethylene lauryl ether phosphate, polyoxyethylene lauryl phenyl ether phosphate, polyoxyethylene stearyl ether phosphate, polyoxyethylene stearyl phenyl ether phosphate, and the like. It is not limited.

  The content of the polymer type anionic surfactant contained in the carbon catalyst layer 23 is not particularly limited, but is preferably 0.5 to 30 wt%, more preferably 0.8% with respect to the total amount of conductive carbon particles. ~ 20 wt%. The higher the content of the polymer type anionic surfactant, the better the mechanical strength and the durability. On the other hand, the lower the content of the polymer type anionic surfactant, the better the initial characteristics. Therefore, in view of these balances, the content of the polymer type anionic surfactant may be appropriately set.

  The formation method of the carbon catalyst layer 23 is not specifically limited, A well-known method is applicable. For example, a method (slurry, sol, etc.) containing conductive carbon particles is applied to the conductive surface 22a of the substrate 22 and then sintered, or such a formulation is applied to the conductive surface 22a of the substrate 22. And a method of performing low-temperature treatment at about 50 to 150 ° C., preferably about 70 to 150 ° C. According to these methods, the carbon catalyst layer 23 having a porous structure in which conductive carbon particles are aggregated and / or bonded can be easily obtained. Among these, the latter method of performing a low-temperature treatment at about 50 to 150 ° C. is preferable from the viewpoint that the substrate containing the resin can be used and the applied energy amount can be reduced to reduce the environmental load. In addition, the application | coating method to the electroconductive surface 22a of the base | substrate 22 of a formulation is not specifically limited, A conventionally well-known coating method etc. are applicable.

  The preparation containing the conductive carbon particles and the polymer-type anionic surfactant is preferably a preparation liquid containing a dispersion medium (for example, a dispersion liquid, a sol liquid or a slurry liquid). Specific examples of the dispersion medium used here are not particularly limited. For example, water, methanol, ethanol, isopropyl alcohol, butanol, dichloromethane, acetone, methyl ethyl ketone, acetonitrile, ethyl acetate, toluene, dimethylformamide, ethoxyethanol, cyclohexanone, and the like. These various organic solvents are mentioned. These may be used alone or in combination. Moreover, you may contain adjuvants, such as another surfactant and a chelating agent, as needed.

  As the electrolyte 31, a redox electrolyte solution, a semi-solid electrolyte obtained by gelling this, or a film formed with a p-type semiconductor solid hole transport material or the like, which is generally used in batteries, solar cells, etc., can be used as appropriate. . As a typical electrolyte solution of a dye-sensitized solar cell, for example, an acetonitrile solution, an ethylene carbonate solution, or a propylene carbonate solution containing iodine and iodide or bromine and bromide, a mixed solution thereof, and the like can be given. The concentration of the electrolyte, various additives, and the like can be set and selected as appropriate according to the required performance. Specific examples of additives include, for example, p-type conductive polymers such as polyaniline, polyacetylene, polypyrrole, polythiophene, polyphenylene, polyphenylene vinylene, and derivatives thereof; imidazolium ions, pyridinium ions, triazolium ions, derivatives thereof, and halogens Examples thereof include, but are not limited to, molten salts composed of combinations with ions; gelling agents; oil gelling agents; dispersants; surfactants;

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited to these.

Example 1
1. Production of working electrode First, a titanium oxide sol solution was prepared by the following procedure.
125 ml of titanium isopropoxide was added to 750 ml of a 0.1 M aqueous nitric acid solution with stirring, and this was vigorously stirred at 80 ° C. for 8 hours. The obtained liquid was autoclaved at 230 ° C. for 16 hours in a pressure vessel made of Teflon (registered trademark). The resulting sol solution was then stirred to resuspend the precipitate. Thereafter, the precipitate that was not resuspended was removed by suction filtration, and the sol solution was concentrated with an evaporator until the titanium oxide concentration became 11 wt%. Polyoxyethylene lauryl ether phosphoric acid (trade name: Fusphenol ML-220, manufactured by Toho Chemical Co., Ltd.) was added to the obtained sol solution in an amount of 5 wt% based on the titanium oxide weight, and then stirred for 1 hour.
The sol solution thus obtained was diluted with methanol so that the titanium oxide concentration was 2 wt%, whereby the titanium oxide sol solution of Example 1 was obtained.

Next, a titanium oxide electrode (metal oxide layer) was prepared by the following procedure using the titanium oxide sol solution of Example 1 described above.
First, ITO having a thickness of about 600 nm as a transparent conductive film is sputter-deposited on the surface of the polycarbonate film substrate to provide a flexible conductive polycarbonate film resin substrate (size: 2.0 cm long, 1.5 cm wide, A thickness of 0.1 mm and a sheet resistance of 30Ω / □ were prepared. Next, on the transparent conductive film of the obtained conductive polycarbonate film resin substrate, a masking tape with a thickness of 70 μm provided with square holes of 0.5 cm in length and 0.5 cm in width was applied, and it was carried out toward the square holes. By spray-coating the titanium oxide sol solution of Example 1, the titanium oxide sol solution was applied onto the transparent conductive film exposed inside the square hole. Then, the masking tape was peeled off, and the metal oxide layer (titanium oxide film) containing a metal oxide and a phosphoric acid type surfactant was formed by heating at 100 ° C. for 30 minutes using an electric furnace. The heating rate during heating was 2 ° C./min.
Subsequently, in order to remove the nitric acid component contained in the obtained metal oxide layer, the metal oxide layer was treated with an alkaline solution. Specifically, a 2 wt% ammonia water / methanol diluted solution is used as an alkaline solution, and the metal oxide layer is immersed in this solution for 30 minutes, and then the metal oxide layer is taken out and washed with methanol. Dry at 10 ° C. for 10 minutes.
By the above operation, a titanium oxide electrode of Example 1 having a metal oxide layer (titanium oxide film) containing a metal oxide and a phosphoric acid surfactant on the conductive surface of the substrate was obtained. When the film thickness of this metal oxide layer was measured, it was about 6 μm.

Next, a working electrode was prepared according to the following procedure.
The titanium oxide electrode of Example 1 was added to 20 ml of an absolute ethanol solution to which (4,4′-dicarboxylic acid-2,2′-bipyridine) ruthenium (II) diisothiocyanate was added at a concentration of 3 × 10 ⁻⁴ M as a sensitizing dye. Immersion and let stand for 12 hours. After standing, the electrode was taken out, washed with anhydrous acetonitrile and dried naturally. In the obtained electrode, it was confirmed that the metal oxide layer was deep red due to the loading (adsorption) of the ruthenium dye.
By the above operation, a working electrode (dye-supported metal oxide layer) of Example 1 having a metal oxide layer having a sensitizing dye supported on the surface of the metal oxide on the conductive surface of the substrate was obtained.

2. Preparation of counter electrode Next, a counter electrode (carbon counter electrode) was prepared by the following procedure.
As the conductive carbon particles, conductive carbon black (trade name: Ketjen Black EC600JD, manufactured by Lion Corporation) was prepared, and this was added to methanol so as to be 5% by weight. Next, 1 wt% of polyoxyethylene lauryl ether phosphate (trade name: Fusphenol ML-220, manufactured by Toho Chemical Industry Co., Ltd.) as a polymer type anionic surfactant was added to the total amount of conductive carbon particles and stirred for 1 hour. . Furthermore, the slurry liquid (preparation) of Example 1 was prepared by diluting with methanol so that the conductive carbon particle concentration was 2% by weight to obtain a concentration suitable for spray coating.

Next, using the slurry liquid of Example 1 prepared as described above, a counter electrode (carbon counter electrode) was produced in the following manner.
First, similar to the working electrode, ITO having a thickness of about 600 nm is sputter-deposited as a transparent conductive film on the surface of the polycarbonate film substrate, whereby a flexible conductive polycarbonate film resin substrate (size: 2.0 cm in length) , Width 1.5 cm, thickness 0.1 mm, sheet resistance: 30Ω / □). On the transparent conductive film of this conductive polycarbonate film resin substrate, a masking tape with a thickness of 70 μm provided with square holes of 0.5 cm in length and 0.5 cm in width was pasted, and the slurry of Example 1 was directed toward the square holes. The solution was spray applied. After coating, the masking tape was peeled off and heated at 100 ° C. for 30 minutes using an electric furnace. The temperature rising rate was 2 ° C./min.
By the above operation, the counter electrode of Example 1 having a carbon catalyst layer containing conductive carbon particles and a polymer type anionic surfactant on the conductive surface of the substrate was obtained.

  Further, the counter electrode of Example 1 was prepared for analysis in the same manner as described above, and the carbon catalyst layer was collected and subjected to thermogravimetric analysis (TGA). As a result, polyoxyethylene lauryl ether phosphate was converted to conductive carbon black. It was confirmed that 0.8 wt% was contained. The measurement conditions for this thermogravimetric analysis are as follows. Using a TG / DTA22 device manufactured by Seiko Electronics Co., Ltd., sample 2 mg, set it in the sample holder, set a reference sample in the reference holder, and put He gas as an ambient gas around the sample at a flow rate of 300 mL / min. After the distribution was started, the temperature increase was started from room temperature under a temperature increase program at a temperature increase rate of 10 ° C./min, and the mass change of the sample at that time was measured (room temperature to 500 ° C.).

3. Preparation of dye-sensitized solar cell And a dye-sensitized solar cell was manufactured according to the following procedure using the above working electrode and carbon counter electrode.
First, a spacer having a square hole of 0.5 cm in length and 0.5 cm in width and having a length of 1.5 cm, a width of 1.5 cm, and a thickness of 70 μm was placed on and closely adhered to the working electrode. At this time, the spacer was placed on the working electrode so that the square hole portion of the spacer and the portion of the metal oxide layer (dye-supporting metal oxide layer) on which the sensitizing dye was supported coincided. Next, an electrolyte (electrolytic solution) was poured from the opening of the square hole, and the electrolyte was filled in the square hole. Here, a methoxypropionitrile solution containing tetrapropylammonium iodide (0.4M) and iodine (0.04M) was used as the electrolytic solution. Then, the counter electrode was mounted on the opening of the square hole. At this time, the counter electrode was placed so that the opening of the square hole coincided with the carbon catalyst layer portion of the counter electrode. And the dye-sensitized solar cell of Example 1 was produced by sealing the periphery with an epoxy resin.

4). Evaluation The battery characteristics of the dye-sensitized solar cell of Example 1 obtained were measured using an AM-1.5 (1000 W / m ² ) solar simulator.
As battery characteristics, four items of open circuit voltage (Voc), photocurrent density (Jsc), form factor (FF), and conversion efficiency (η) were measured. In addition, an open circuit voltage (Voc) represents the voltage between both terminals when the output terminal of a photovoltaic cell module is opened. The photocurrent density (Jsc) represents a current (per 1 cm ² ) flowing between both terminals when the output terminal of the solar cell module is short-circuited. The form factor (FF) is a value obtained by dividing the maximum output Pmax by the product of the open-circuit voltage (Voc) and the photocurrent density (Jsc) (FF = Pmax / Voc · Jsc), and the current-voltage characteristics as a solar cell. It is a parameter that represents the characteristic of the curve. Furthermore, the photoelectric conversion efficiency (η) is obtained by measuring the response current by sweeping the voltage of the photoelectric conversion element with a source meter. The maximum output, which is the product of the voltage and current, is the light intensity per 1 cm ^2. The value divided by is multiplied by 100 and expressed as a percentage, expressed as (maximum output / light intensity per cm ² ) × 100. These results are shown in Table 1.

  Moreover, in order to evaluate the durability (long-term reliability) of the obtained dye-sensitized solar cell of Example 1, the photoelectric conversion efficiency after being left for 100 hours at 60 ° C. and 95% RH, and from 60 ° C. to − The photoelectric conversion efficiency after the 20 ° C. temperature cycle test (1 cycle 6 hours × 10 times) was measured, and the variation rate (%) from the previously measured (initial) photoelectric conversion efficiency was calculated. . These results are also shown in Table 1.

Furthermore, in order to evaluate the film strength of the carbon catalyst layer, a washing bottle containing methanol was prepared, and methanol was poured from the position about 20 cm away from the surface of the carbon catalyst layer of the working electrode to the surface of the carbon catalyst layer, The peeling state of the carbon catalyst layer at that time was observed. The evaluation criteria were as follows.
○: No peeling △: Partial peeling ×: Complete peeling

(Example 2)
A slurry solution (preparation) of Example 2 was prepared in the same manner as in Example 1 except that 5% by weight of polyoxyethylene lauryl ether phosphoric acid was added to the total amount of conductive carbon particles.
A counter electrode, a working electrode, and a dye-sensitized solar cell of Example 2 were produced in the same manner as in Example 1 except that the obtained slurry liquid of Example 2 was used.
The dye-sensitized solar cell of Example 2 was subjected to various measurements in the same manner as in Example 1. The results are shown in Table 1.

(Example 3)
A slurry liquid (preparation) of Example 3 was prepared in the same manner as in Example 1 except that 10 wt% of polyoxyethylene lauryl ether phosphoric acid was added to the total amount of conductive carbon particles.
A counter electrode, a working electrode and a dye-sensitized solar cell of Example 3 were produced in the same manner as in Example 1 except that the obtained slurry liquid of Example 3 was used.
The dye-sensitized solar cell of Example 3 was subjected to various measurements in the same manner as in Example 1. The results are shown in Table 1.

Example 4
A slurry solution (formulation) of Example 4 was prepared in the same manner as in Example 1 except that 20 wt% of polyoxyethylene lauryl ether phosphoric acid was added to the total amount of conductive carbon particles.
A counter electrode, a working electrode and a dye-sensitized solar cell of Example 4 were produced in the same manner as in Example 1 except that the obtained slurry liquid of Example 4 was used.
The dye-sensitized solar cell of Example 4 was subjected to various measurements in the same manner as in Example 1. The results are shown in Table 1.

(Example 5)
A slurry solution (formulation) of Example 5 was prepared in the same manner as in Example 1 except that 30 wt% of polyoxyethylene lauryl ether phosphoric acid was added to the total amount of conductive carbon particles.
A counter electrode, a working electrode and a dye-sensitized solar cell of Example 5 were produced in the same manner as in Example 1 except that the obtained slurry liquid of Example 5 was used.
The dye-sensitized solar cell of Example 5 was subjected to various measurements in the same manner as in Example 1. The results are shown in Table 1.

(Example 6)
Other than changing polyoxyethylene lauryl ether phosphoric acid to a special polycarboxylic acid type polymer surfactant (trade name: Poise 520, manufactured by Lion Corporation, polymer type polymer surfactant having a carboxyl group or a salt thereof) The same procedure as in Example 2 was performed to prepare a slurry liquid (formulation) of Example 6.
A counter electrode, a working electrode and a dye-sensitized solar cell of Example 6 were produced in the same manner as in Example 1 except that the obtained slurry liquid of Example 6 was used.
The dye-sensitized solar cell of Example 6 was subjected to various measurements in the same manner as in Example 1. The results are shown in Table 1.

(Example 7)
Except for changing polyoxyethylene lauryl ether phosphoric acid to sodium polyoxyethylene lauryl ether sulfate (trade name: EMAL 20C, manufactured by Lion Corporation), the same procedure as in Example 2 was carried out, and the slurry liquid of Example 7 (formulation) Prepared).
A counter electrode, a working electrode, and a dye-sensitized solar cell of Example 7 were produced in the same manner as in Example 1 except that the obtained slurry liquid of Example 7 was used.
The dye-sensitized solar cell of Example 7 was subjected to various measurements in the same manner as in Example 1. The results are shown in Table 1.

(Example 8)
The same procedure as in Example 3 was conducted except that the conductive carbon black was changed to graphite (trade name: flake graphite Z-5F, manufactured by Ito Graphite Industries Co., Ltd.), and the slurry liquid (formulation) of Example 8 was used. Was prepared.
A counter electrode, a working electrode, and a dye-sensitized solar cell of Example 8 were produced in the same manner as in Example 1 except that the obtained slurry liquid of Example 8 was used.
The dye-sensitized solar cell of Example 8 was subjected to various measurements in the same manner as in Example 1. The results are shown in Table 1.

Example 9
A slurry liquid (formulation) of Example 9 was prepared in the same manner as in Example 3 except that the conductive carbon black was changed to fullerene (trade name: Nanomumix ST, Frontier Carbon Co., Ltd.).
A counter electrode, a working electrode and a dye-sensitized solar cell of Example 9 were produced in the same manner as in Example 1 except that the obtained slurry liquid of Example 9 was used.
The dye-sensitized solar cell of Example 9 was subjected to various measurements in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
A slurry liquid (preparation) of Comparative Example 1 was prepared in the same manner as in Example 1 except that polyoxyethylene lauryl ether phosphoric acid was not added.
A counter electrode, a working electrode, and a dye-sensitized solar cell of Comparative Example 1 were produced in the same manner as in Example 1 except that the obtained slurry liquid of Comparative Example 1 was used.
The dye-sensitized solar cell of Comparative Example 1 was subjected to various measurements in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
A slurry solution (preparation) of Comparative Example 2 was prepared in the same manner as in Example 2 except that polyoxyethylene lauryl ether phosphate was changed to polyethylene glycol (molecular weight 4000, manufactured by Wako Pure Chemical Industries, Ltd.).
A counter electrode, a working electrode, and a dye-sensitized solar cell of Comparative Example 2 were produced in the same manner as in Example 1 except that the obtained slurry liquid of Comparative Example 2 was used.
Various measurements were performed on the dye-sensitized solar cell of Comparative Example 2 in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 3)
A slurry liquid (preparation) of Comparative Example 3 was prepared in the same manner as in Example 5 except that polyoxyethylene lauryl ether phosphate was changed to polyethylene glycol (molecular weight 4000, manufactured by Wako Pure Chemical Industries, Ltd.).
A counter electrode, a working electrode, and a dye-sensitized solar cell of Comparative Example 3 were produced in the same manner as in Example 1 except that the obtained slurry liquid of Comparative Example 3 was used.
The dye-sensitized solar cell of Comparative Example 3 was subjected to various measurements in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 4)
The same procedure as in Example 2 was conducted except that polyoxyethylene lauryl ether phosphate was changed to alkylbenzyldimethylammonium chloride (trade name: SANISOL B-50, manufactured by Lion Corporation). Prepared).
A counter electrode, a working electrode and a dye-sensitized solar cell of Comparative Example 4 were produced in the same manner as in Example 1 except that the obtained slurry liquid of Comparative Example 4 was used.
The dye-sensitized solar cell of Comparative Example 4 was subjected to various measurements in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 5)
A slurry solution (composition) of Comparative Example 5 was prepared in the same manner as in Example 2 except that polyoxyethylene lauryl ether phosphate was changed to stearylamine acetate (trade name: Acetamine 86, manufactured by Lion Corporation). did.
A counter electrode, a working electrode and a dye-sensitized solar cell of Comparative Example 5 were produced in the same manner as in Example 1 except that the obtained slurry liquid of Comparative Example 5 was used.
The dye-sensitized solar cell of Comparative Example 5 was subjected to various measurements in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 6)
A slurry solution (composition) of Comparative Example 6 was carried out in the same manner as in Example 2 except that polyoxyethylene lauryl ether phosphate was changed to polyoxyethylene alkylamine (trade name: Amit 102, manufactured by Lion Corporation). Was prepared.
A counter electrode, a working electrode, and a dye-sensitized solar cell of Comparative Example 6 were produced in the same manner as in Example 1 except that the obtained slurry liquid of Comparative Example 6 was used.
The dye-sensitized solar cell of Comparative Example 6 was subjected to various measurements in the same manner as in Example 1. The results are shown in Table 1.

  As shown in Examples 1 to 7 and Comparative Example 1, the durability (long-term reliability) of the dye-sensitized solar cell is remarkably improved by including the polymer type anionic surfactant in the carbon catalyst layer. It was confirmed. In addition, by adjusting the content of the polymer type anionic surfactant, it is possible to achieve both excellent battery characteristics and excellent durability (long-term reliability) that could not be achieved in the past. confirmed.

  On the other hand, in comparison with Examples 1 to 7 and Comparative Examples 2 to 6, when a conventional organic binder component, a non-polymer type surfactant, or a surfactant other than an anionic type was used, a dye-sensitized type It was confirmed that not only the effect of improving the durability (long-term reliability) of the solar battery was insufficient, but also good battery characteristics were not exhibited in the first place.

  Further, in comparison with Example 2 and Examples 6 and 7, the polymer type surfactant having a phosphate group is different from other polymer type anionic surfactants, and the battery performance and the dye-sensitized solar cell are shown. It was confirmed that this is a unique additive that can more effectively increase the durability (long-term reliability) of the resin.

  Furthermore, it was confirmed from the comparison between Examples 1 to 7 and Examples 8 and 9 that the above-described effects are exhibited regardless of the type of conductive carbon particles.

  In addition, as above-mentioned, this invention is not limited to the said embodiment and Example, In the range which does not deviate from the summary, it can add suitably.

  As described above, a counter electrode capable of improving durability without excessively degrading battery characteristics can be realized, and the productivity, economy, and versatility are excellent. It can be widely and effectively used in electric devices and various devices, facilities, systems and the like equipped with them, and can be effectively used particularly in the fields of photoelectric conversion elements and dye-sensitized solar cells.

  DESCRIPTION OF SYMBOLS 11 ... Working electrode, 12 ... Base | substrate, 12a ... Conductive surface, 13 ... Metal oxide layer, 14 ... Metal oxide electrode, 21 ... Counter electrode, 22 ... Base | substrate, 22a ... Conductive surface, 23 ... Carbon catalyst layer, 31 ... Electrolyte, 41 ... Spacer, 100 ... Dye-sensitized solar cell.

Claims (4)

A substrate having a conductive surface; and a carbon catalyst layer provided on at least a part of the conductive surface;
The carbon catalyst layer contains conductive carbon particles and a polymer type anionic surfactant having a phosphate group,
The polymer type anionic surfactant having a phosphate group is selected from polyoxyethylene lauryl ether phosphate, polyoxyethylene stearyl ether phosphate, polyoxyethylene lauryl phenyl ether phosphate, polyoxyethylene stearyl phenyl ether phosphate And
The conductive carbon particles have a porous structure in which they are aggregated and / or bonded.
Counter electrode for dye-sensitized solar cell. The polymer type anionic surfactant having a phosphate group is contained in an amount of 0.5 to 30 wt% with respect to the conductive carbon particles.
The counter electrode for dye-sensitized solar cells according to claim 1. A working electrode having a substrate having a conductive surface and a dye-supported metal oxide layer provided on at least a part of the conductive surface;
A counter electrode having a substrate having a conductive surface and a carbon catalyst layer provided on at least a part of the conductive surface; and
An electrolyte provided between the working electrode and the counter electrode,
The carbon catalyst layer contains conductive carbon particles and a polymer type anionic surfactant having a phosphate group,
The polymer type anionic surfactant having a phosphate group is selected from polyoxyethylene lauryl ether phosphate, polyoxyethylene stearyl ether phosphate, polyoxyethylene lauryl phenyl ether phosphate, polyoxyethylene stearyl phenyl ether phosphate And
The conductive carbon particles have a porous structure in which they are aggregated and / or bonded.
Dye-sensitized solar cell. A method for producing a counter electrode having a substrate having a conductive surface and a carbon catalyst layer provided on the conductive surface ,
Preparing a formulation containing conductive carbon particles and a polymeric anionic surfactant having a phosphate group;
Applying the formulation to the substrate having a conductive surface;
Have a, a low-temperature process of 50 to 150 ° C.,
The polymer type anionic surfactant having a phosphate group is selected from polyoxyethylene lauryl ether phosphate, polyoxyethylene stearyl ether phosphate, polyoxyethylene lauryl phenyl ether phosphate, polyoxyethylene stearyl phenyl ether phosphate To be
Manufacturing method of counter electrode.