JP2006318770A - Catalyst electrode of dye-sensitized solar battery, and dye-sensitized solar battery with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst electrode which can be simply manufactured by using a cheap material, excellent in durability capable of quickly reducing oxidant of redox pair contained in an electrolyte, and to provide a dye-sensitized solar battery provided with the catalyst electrode having an excellent photoelectric conversion rate. <P>SOLUTION: The catalyst electrode contains at least a metal layer and a corrosion resistant conductive layer formed on a metal layer. The corrosion resistant conductive layer contains a catalytic compound composed of at least one kind of material selected from a transition metal, a conductive carbon material, a conductive polymeric material, and an organic metal complex. The dye-sensitized solar battery provided with the above catalyst electrode as a counter electrode is provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a catalyst electrode of a dye-sensitized solar cell and a dye-sensitized solar cell including the same.

  In recent years, dye-sensitized solar cells in which a sensitizing dye that absorbs a visible light region is supported on a porous metal semiconductor layer have been studied. This dye-sensitized solar cell is expected to be put to practical use because of the advantages that it is inexpensive and can be manufactured by a relatively simple process.

  In the dye-sensitized solar cell, electrons are injected into the semiconductor electrode from the sensitizing dye excited by absorbing visible light, and current is taken out through the 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 surface of the catalyst electrode placed opposite to the semiconductor electrode, and the cycle goes around.

  As a catalyst electrode conventionally used in a dye-sensitized solar cell, a chloroplatinic acid is applied and heat-treated on a substrate coated with a conductive oxide as a current collector, platinum is deposited, or Electroplated platinum catalyst electrodes are known.

  In consideration of practical use, electrolytes have been studied for higher viscosity and gelation. However, in dye-sensitized solar cells equipped with platinum catalyst electrodes as shown above, redox is accompanied by higher electrolyte viscosity. The diffusion of iodine as a pair becomes a rate-determining process of the electron transfer reaction in the solar cell, and there is a problem that the solar cell characteristics are deteriorated. For this reason, in order to advance the iodine reduction reaction on the surface of the catalyst electrode more rapidly, it is necessary to increase the surface area by increasing the surface area by forming a film thickness and unevenness, or the amount of platinum used increases, or There is also a problem that the manufacturing process becomes complicated and the manufacturing cost increases.

  In addition, the conductive oxide generally used as a current collector is insufficient in conductivity, so that it is necessary to increase the film thickness. As a result, the cost of the catalyst electrode increases. Furthermore, in the dye-sensitized solar cell of practical size, there is a problem that the solar cell performance is greatly deteriorated because the conductivity is insufficient even if the conductive oxide layer is thickened. .

  Patent Document 1 discloses a dye-sensitized solar cell using a hole current collecting electrode (catalyst electrode) made of an organic film formed simultaneously with polymerization of a monomer.

  According to this document, it is described that a hole-collecting electrode can be produced at a low cost by a simple process compared with a conventional method for forming a catalyst electrode, and a dye-sensitized solar cell advantageous in terms of production process and production cost can be provided. Has been.

  Patent Document 2 discloses a carbon electrode that has improved conductivity by using conductive oxide particles having higher conductivity than anatase-type titanium oxide as a conductive additive, and as a result, oxidation of the redox couple is disclosed. It is described that the reduction reaction of the body can be advanced promptly, a larger electrode area than that of the platinum catalyst glass electrode can be easily secured, and a lightweight, chemically stable and low-cost electrode can be obtained.

  However, when a conductive polymer material or a powdery carbon material is used as the hole collector electrode, the practical size is insufficient, and the conductivity must be supplemented to obtain high conversion efficiency. I must. In other words, the catalyst electrode still requires the use of a substrate coated with a highly conductive current collector. However, in order to avoid corrosion due to iodine, which is generally used as a redox couple, it is expensive. The current situation is that a substrate coated with an oxide is used.

  As described in Non-Patent Document 1, most of the catalyst electrode manufacturing cost is occupied by the material cost, especially the substrate coated with the conductive oxide, and it is not enough to reduce the manufacturing cost due to the reduction of platinum usage. It is. Therefore, there is a need for a catalyst electrode that uses an inexpensive substrate having corrosion resistance and high conductivity, exhibits excellent battery characteristics even in practical size, and a dye-sensitized solar cell including the catalyst electrode.

JP 2003-317814 A Japanese Patent Laid-Open No. 2004-127849 Wet Solar Cell Practicability Study, “1999 New Energy and Industrial Technology Development Organization Consignment Results Report Solar Power Generation System Practical Technology Development Manufacturing Technology for Super-Efficient Crystalline Compound Solar Cell Research on Peripheral Elemental Technology "Industry Creation Institute, March 2000, p. 41-42

  In view of the above-described circumstances, the present invention can be produced by an inexpensive material and a simple manufacturing method, and can quickly reduce an oxidized form of a redox pair contained in an electrolyte, and has excellent durability. It is an object of the present invention to provide a catalyst electrode and a dye-sensitized solar cell having the same and having excellent photoelectric conversion efficiency.

  As a result of intensive studies to solve the above problems, the inventors of the present invention include at least a metal layer and a corrosion-resistant conductive layer formed on the metal layer, and the corrosion-resistant conductive layer includes a transition metal, a conductive carbon material, An electrode containing a conductive polymer material or at least one catalyst compound selected from organometallic complexes has high corrosion resistance and high conductivity and is included in the electrolyte for a long period of time. The inventors have found that the catalyst electrode can rapidly reduce the oxidant of the redox couple, and has completed this research.

That is, the present invention is as follows.
1. In a dye-sensitized solar cell having a light-transmitting semiconductor electrode containing a dye having a photosensitizing action and an electrolyte layer containing a chemical species serving as a redox pair, the semiconductor electrode faces the semiconductor electrode through the electrolyte layer. A catalyst electrode to be disposed, wherein the catalyst electrode includes at least a metal layer and a corrosion-resistant conductive layer formed on the metal layer, and the corrosion-resistant conductive layer contains a catalyst compound. Catalytic electrode.
2. 2. The catalyst electrode according to 1 above, wherein the metal layer is made of at least one metal selected from iron, nickel, chromium, molybdenum, titanium, and aluminum, or an alloy thereof, or stainless steel. .
3. 2. The catalyst electrode according to 1 above, wherein the corrosion-resistant conductive layer is made of a metal oxide.
4). The metal oxide contains at least one selected from tin oxide, indium oxide, a mixture of tin oxide and indium oxide, titanium oxide, zinc oxide, iridium oxide, or ruthenium oxide. The catalyst electrode as described.
5. 2. The catalyst electrode according to 1 above, wherein the corrosion-resistant conductive layer is made of a metal nitride.
6). 6. The catalyst electrode according to 5 above, wherein the metal nitride is a metal nitride selected from at least one of chromium, titanium, zirconium, vanadium, and niobium.
7). 2. The catalyst electrode according to 1 above, wherein the corrosion-resistant conductive layer is made of a metal boride.
8). 8. The catalyst electrode according to 7 above, wherein the metal boride is a boride of a metal selected from at least one of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, or tungsten.
9. 2. The catalyst electrode according to 1 above, wherein the corrosion-resistant conductive layer is made of a metal carbide.
10. 10. The catalyst electrode according to 9 above, wherein the metal carbide is a carbide of a metal selected from at least one of titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, or tungsten.
11. 11. The catalyst electrode according to any one of 3 to 10 above, wherein the electrical conductivity of the corrosion-resistant conductive layer is 1 × 10 ⁻⁹ S / cm or more.
12 2. The catalyst electrode according to 1 above, wherein the catalyst compound comprises at least one selected from a transition metal, a conductive carbon material, a conductive polymer material, or an organometallic complex.
13. 13. The catalyst electrode as described in 12 above, wherein the transition metal is platinum.
14 13. The catalyst electrode as described in 12 above, wherein the conductive polymer material is at least one polymer selected from pyrrole, thiophene, aniline and derivatives thereof.
15. 13. The catalyst electrode as described in 12 above, wherein the organometallic complex is at least one selected from a porphyrin complex, a phthalocyanine complex, and derivatives thereof.
16. Dye sensitization comprising a light-transmitting semiconductor electrode containing a dye having a photosensitizing action, an electrolyte layer containing a chemical species serving as a redox pair, and a counter electrode disposed opposite to the semiconductor electrode via the electrolyte layer A dye-sensitized solar cell, wherein the counter electrode is the catalyst electrode according to any one of 1 to 15 above.

  According to the present invention, a metal can be used as a current collector even in a corrosive environment by forming a corrosion-resistant conductive layer on a metal layer. As a result, the electrode material and manufacturing cost can be reduced. In addition, since the electrical resistance value of the current collector can be lowered, the reduction reaction of the oxidant of the redox pair contained in the electrolyte can be performed quickly even with a small amount of catalyst used, further reducing costs. And high energy conversion efficiency can be obtained. Furthermore, the solar cell can be increased in size without reducing the conversion efficiency. Therefore, a catalyst electrode that can stably perform the reduction reaction over a long period of time with high efficiency, and a highly durable large-sized dye-sensitized solar cell having the same and having excellent photoelectric conversion efficiency can be manufactured at low cost. Can be provided easily.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of the dye-sensitized solar cell of the present invention. A porous metal oxide semiconductor layer 4 is formed on the surface of the electrode substrate 1 composed of the transparent substrate 2 and the transparent conductive film 3 formed thereon, and further on the surface of the porous metal oxide semiconductor layer 4, The sensitizing dye layer 5 is adsorbed. And the catalyst electrode 7 of this invention is installed facing through the electrolyte layer 6. FIG.

  FIG. 2 is a schematic cross-sectional view of the catalyst electrode 7 in the present invention. The catalyst electrode 7 shown in FIG. 2 has a corrosion-resistant conductive layer 10 formed on a metal layer 9 and further contains a catalyst compound on the surface of the corrosion-resistant conductive layer 10 (not shown). Moreover, like the catalyst electrode shown in FIG. 3, the metal layer 9 may be formed on the base body 8 made of glass, plastic, or the like. 2 and 3, the surface on which the corrosion-resistant conductive layer 10 containing the catalyst compound is formed is disposed so as to be in contact with the electrolyte layer 6 in the solar cell shown in FIG. Used.

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”), 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, ruthenium, copper, aluminum, nickel, cobalt, chromium, iron, molybdenum, titanium, tantalum, and alloys thereof. Therefore, the transparent conductive film 3 can be formed by providing a conductive material made of at least one of the above-described conductive materials on the surface of the transparent substrate 2. 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, when a metal oxide is used, there are a liquid phase method such as a sol-gel method, a gas phase method such as sputtering or 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 wider electrode is required to have a lower resistance, but is generally 100Ω / □ or less, preferably 10Ω / □ or less, more preferably 5Ω. / □ or less.
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. Moreover, in order to adsorb more sensitizing dyes, it is desirable to be porous. 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.
The thickness of such a semiconductor layer is not particularly limited because the optimum value varies depending on the oxide used, 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 a dye 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, but the electrode substrate 1 on which the porous metal oxide semiconductor 4 is formed is immersed in a solution in which the dye is dissolved. Can be adsorbed easily.
There is an optimum value of the amount of the sensitizing dye to be adsorbed on the porous metal oxide semiconductor 4. That is, if the amount of the dye is small, a sufficient sensitizing effect cannot be obtained and a sufficient photocurrent cannot be obtained. Conversely, if the amount is too large, a sufficient photocurrent cannot be obtained due to an electron transfer reaction between the dyes. Although such an optimum value varies depending on the combination of the semiconductor and the dye used, it is desirable that a monomolecular film of the dye is uniformly formed on the semiconductor layer.

[Electrolyte layer]
The electrolyte layer 6 is composed of a supporting electrolyte, a redox pair 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 non-aqueous organic solvents, room temperature molten salts, water, protic organic solvents, and the like, such as acetonitrile, dimethylformamide, ethylmethylimidazolium bistrifluoromethylimide, methoxyacetonitrile. , Methoxypropionitrile, propylene carbonate, and the like. Among them, methoxyacetonitrile, methoxypropionitrile, propylene carbonate, 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.
Examples of the redox pair include iodine anion, polypyridyl cobalt complex, and thiocyanic acid.
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.

[Catalyst electrode-substrate]
The catalyst electrode 7 includes a metal layer 9 and a corrosion-resistant conductive layer 10 containing a catalyst compound. As long as the metal layer 9 can be formed on the upper part and the electrode can be supported, the substrate 8 can be used. Since the material and thickness can be changed according to the shape of the dye-sensitized solar cell, there is no particular limitation. Considering practicality and durability, for example, plastic or glass can be suitably used. Further, the substrate may be transparent or opaque, but it is desirable that the 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.
Further, the shape of the substrate is not particularly limited because it can be changed according to the shape of the dye-sensitized solar cell used as the catalyst electrode, and it may be a plate or a film that can be curved.

[Catalyst electrode-metal layer]
The metal layer 9 functions as a current collector. The material can be suitably used as long as it is a metal having conductivity, but at least one selected from iron, nickel, chromium, molybdenum, titanium, and aluminum is excellent in terms of convenience and cost. It is desirable to be a metal, an alloy thereof, or stainless steel.
Moreover, since the shape can be changed according to the shape of the dye-sensitized solar cell used as the catalyst electrode, it is not particularly limited and can be formed in any shape and thickness.
The forming method is not particularly limited, and an existing method such as sputtering on the substrate 8 or bonding a metal plate or metal foil can be used. Further, as illustrated in FIG. 2, the base 8 can be omitted.
Further, before forming the following corrosion-resistant conductive layer 10 on the metal layer 9, the corrosion-resistant conductive layer 10, even in a complicated shape, can be obtained by performing desired molding by bending such as press working together with the substrate, and The effects of the corrosion-resistant conductive layer 10 and the catalyst can be reliably obtained without damaging the catalyst contained on the surface of the corrosion-resistant conductive layer 10.
The thickness of the metal layer is required to be able to maintain conductivity that can function as a current collector, but the required film thickness varies depending on the material and can be changed according to the shape of the dye-sensitized solar cell to be used. There is no particular limitation. In general, the thickness is preferably 5 nm or more, more preferably 1 μm or more.

[Catalyst electrode-Corrosion-resistant conductive layer]
The corrosion-resistant conductive layer 10 is required to have corrosion resistance and conductivity. For example, metal oxide, metal nitride, metal carbide, metal boride and the like can be suitably used. Examples of the metal oxide include tin oxide, indium oxide, a mixture of tin oxide and indium oxide, titanium oxide, zinc oxide, iridium oxide, and ruthenium oxide. Further, examples of the metal nitride include chromium and titanium nitrides. Examples of the metal carbide include a carbide of metal selected from at least one of titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten. Examples of the metal boride include a metal boride selected from at least one of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten. These may be used in combination of a plurality of materials. Furthermore, a dopant may be added to these materials in order to further improve the corrosion resistance or conductivity. The thickness of the corrosion-resistant conductive layer 10 is desirably 5 nm to 50 μm so that the corrosion resistance is enhanced and the high conductivity of the metal layer can be utilized. More preferably, the thickness is desirably 0.01 μm to 20 μm. The electrical conductivity of the corrosion-resistant conductive layer is desirably 1 × 10 ⁻⁹ S / cm or more.

  The method for forming the corrosion-resistant conductive layer 10 is not particularly limited, and a known method can be used. For example, when a metal oxide is used, a sol-gel method or an electrodeposition method can be used. When metal nitride is used, various known nitriding methods such as heat treatment of the metal substrate in a nitrogen atmosphere and plasma nitriding can be used. In the case of using metal carbide and metal boride, a method of depositing or spraying the respective particles on the metal substrate and then crushing with the metal substrate, paste, emulsion, or polymer solution And a method of forming the mixture on the corrosion-resistant conductive layer 10 by screen printing, spray coating, brush coating, etc.

[Catalyst electrode-catalyst compound]
The catalyst compound of the present invention is not particularly limited as long as it can reduce the oxidized form of the redox pair contained in the electrolyte layer 6, and a known substance can be used. For example, transition metals, conductive polymer materials, etc. A conductive carbon material, an organometallic complex, or the like can be preferably used.
The shape is not particularly limited because it varies depending on the type of catalyst compound used. A catalyst material composed of at least one of the above catalyst compounds can be formed on the surface of the corrosion-resistant conductive layer 10. Alternatively, the catalyst material can be incorporated into the material constituting the corrosion-resistant conductive layer 10.

  As the transition metal, platinum, palladium, ruthenium, rhodium and the like can be preferably used, and platinum is particularly preferable among them. As a method for supporting the transition metal on the corrosion-resistant conductive layer, a known method can be used. For example, sputtering, vapor deposition, electrodeposition, thermal decomposition, or the like can be used.

  As a conductive polymer monomer, a conductive polymer polymer obtained by polymerizing at least one monomer from pyrrole, aniline, thiophene, and derivatives thereof can be used as a catalyst compound. At this time, the conductive polymer may be in an undoped state, but a dopant can be added in order to improve conductivity and durability. As a method for supporting the conductive polymer on the corrosion-resistant conductive layer, a known method can be used. For example, a method of electrochemical polymerization by immersing a metal layer substrate on which the corrosion-resistant conductive layer is formed in a solution containing the monomer, an oxidizing agent such as Fe (III) ion or ammonium persulfate, and the monomer A method of forming a film from a solution in which the conductive polymer is melted or dissolved, a paste containing the polymer particles of the conductive polymer, Alternatively, there may be mentioned a method of forming an emulsion or a mixture containing a polymer solution and a binder and then forming the mixture on the corrosion-resistant conductive layer 10 by screen printing, spray coating, brush coating, or the like.

  A known carbon material can be used as the conductive carbon material, but carbon nanotubes, carbon black, activated carbon, and the like are preferable. As a method for supporting the carbon material on the corrosion-resistant conductive layer, a known method such as a method of applying and drying a paste using a fluorine-based binder or the like can be used.

  As the organometallic complex, a complex having a ligand containing an atom that easily coordinates to a central metal ion such as N, O, S, or P can be used. For example, a porphyrin complex or a phthalocyanine complex can be suitably used. As a method for supporting the metal complex on the corrosion-resistant conductive layer, a known method can be used. For example, a method of forming the organometallic complex in a paste form, an emulsion form, or a mixture form containing a polymer solution and a binder, followed by screen printing, spray coating, brushing, etc. on the corrosion-resistant conductive layer 10 And a method of forming a film from a solution in which the organometallic complex is dissolved.

[Catalyst electrode]
The shape of the surface of the catalyst electrode is preferably large so that the oxidized form of the redox couple can be efficiently reduced. In particular, it is preferably at least twice the projected area of the catalyst electrode. The method for increasing the surface of the catalyst electrode is not particularly limited, and examples thereof include any of the methods described in (1) to (3) below, or a combination thereof. (1) Enlarging the surface area of the catalyst itself (2) Enlarging the surface area of the corrosion-resistant conductive layer and enlarging the surface area of the catalyst electrode (3) Enlarging the surface area of the substrate or metal layer and enlarging the surface area of the catalyst electrode

  As the method of (1), for example, when a conductive polymer is used as a catalyst, a method of making it porous in the polymerization process is used, and a transition metal, a conductive carbon material, or an organometallic complex is pasted as a catalyst. The catalyst layer can be made porous by forming the paste in a porous state when forming it on the corrosion-resistant conductive layer 10 in the shape of

  Examples of the method (2) include, for example, a method of making the corrosion-resistant conductive layer 10 porous when the sol-gel method is formed, or a treatment with an acid after the corrosion-resistant conductive layer 10 is formed in advance. Can also be made porous. However, since the corrosion-resistant conductive layer 10 protects the metal layer 9, it is necessary that the corrosion-resistant conductive layer is densely formed at the interface with the metal layer 9, and the catalyst is only made porous. This is the corrosion-resistant conductive layer on the layer side.

  As the method (3), for example, the conductivity can be made porous by a method such as treatment with an acid so that the electrical conductivity does not decrease or the electrical conductivity required is satisfied.

  After preparing each constituent material as described above, the dye-sensitized solar cell is completed by assembling the metal oxide semiconductor electrode and the catalyst electrode so as to face each other through an electrolyte by a conventionally known method.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited at all by these.

Example 1
[Porous metal oxide semiconductor]
Titanium dioxide paste (Soralonix) is applied to the surface of FTO glass (Japanese plate glass 25 mm × 50 mm) with a bar coater, dried at 450 ° C. for 30 minutes and allowed to stand at room temperature, and the thickness is 10 μm. A porous titanium oxide semiconductor electrode was formed. Further, the semiconductor layer was ground so that the obtained semiconductor electrode had a titanium oxide projected area of 25 mm ² .

[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 pigment was washed with ethanol and then air-dried to produce a semiconductor electrode of a solar cell.

[Production of catalyst electrode]
Stainless steel 304 was used as the substrate and the metal layer. A substrate ultrasonically cleaned in an organic solvent is immersed in an aqueous solution containing 5 mmol / L of zinc chloride and 0.1 mol / L of potassium chloride, and electrochemically reduced using the counter electrode as a zinc plate while bubbling oxygen. A zinc oxide film was formed on the surface of the metal substrate. The film thickness of the zinc oxide film was 1 to 2 μm, and as a result of surface SEM observation, it was confirmed that the lower part had a homogeneous state without cracks and the upper part had a columnar oxide structure.

  Further, an n-butanol solution containing 3,4-ethylenedioxythiophene, imidazole and Fe (III) p-toluenesulfonic acid, which had been subjected to an ice bath, was applied to the obtained metal substrate with a zinc oxide film. After that, by drying at 120 ° C. in the air, a polyethylene dioxythiophene film was produced to obtain a catalyst electrode.

[Assembly of solar cells]
The semiconductor electrode prepared as described above and the catalyst electrode were placed so as to face each other, and an electrolyte was impregnated between both electrodes by capillary action. As the electrolyte, a solution containing methoxyacetonyl as a solvent, lithium iodide as a reducing agent, iodine as an oxidizing agent, t-butylpyridine as an additive, and 1,2-dimethyl-3-propylimidazolium iodide was used.

[Measurement of photoelectric conversion characteristics of solar cells]
The solar battery cell is irradiated with pseudo-sunlight with a light amount of 100 mW / cm ² to open circuit voltage (hereinafter abbreviated as “Voc”), short-circuit current density (hereinafter abbreviated as “Jsc”), and shape. When the factors (hereinafter abbreviated as “FF”) and photoelectric conversion efficiency were evaluated, the following results were obtained. In addition, about each measured value of "Voc", "Jsc", "FF", and photoelectric conversion efficiency, it represents that a larger value is preferable as a performance of a photovoltaic cell.

[Durability test of solar cells]
The corrosion resistant conductive layer of the catalyst electrode and the back surface of the metal substrate on which the catalyst layer is not formed are subjected to a corrosion resistance treatment with a silicon resin, and 0.1 mol / L of iodine and lithium iodide of 0. The container was immersed in an acetonitrile solution containing 05 mol / L, and the container was sealed and left at room temperature in the dark. After taking out from the iodine solution at regular intervals, washing with acetonitrile and air-drying, the change rate of the short-circuit current density value was measured by the above method.

[Measurement results of Example 1]
Open-circuit voltage (Voc): 0.69V
Short circuit current density (Jsc): 11.0 mA / cm ²
Form factor (FF): 79%
Photoelectric conversion efficiency: 6.0%
Change rate of short-circuit current density after 500 hours: 88%
Change rate of short-circuit current density after 1000 hours: 85%

Example 2
A mixed solution in which a titanium-n-butoxide-containing butanol aqueous solution was added to benzene was heated to reflux, and a titanium-n-butoxide-containing butanol aqueous solution was appropriately added and concentrated to obtain a titanium oxide precursor solution.

  A titanium substrate polished with alumina having an average particle diameter of 1 μm is immersed in the obtained titanium oxide precursor solution, air-dried in air, and then baked in air at 500 ° C., whereby a titanium oxide thin film electrode is obtained. Obtained. The thickness of the obtained thin film layer was about 1.2 μm. When surface SEM observation was performed, it was confirmed that it was a homogeneous thin film without a crack.

  The obtained titanium substrate with titanium oxide thin film is kneaded with activated carbon (KP222 manufactured by Takeda Pharmaceutical) and acetylene black together with a fluorine-based binder (KF polymer # 1120 manufactured by Kureha Chemical), and an appropriate amount of N-methyl-2-pyrrolidone is added. Then, a conductive carbon paste was prepared. The obtained paste was applied on the titanium substrate with the titanium oxide thin film and dried at 120 ° C. for 1 hour to obtain a catalyst electrode. When surface SEM observation was performed about the obtained catalyst electrode, it was confirmed that the porous carbon catalyst layer is formed.

  A solar battery cell was produced and evaluated for the obtained catalyst electrode in the same manner as in Example 1 except for the production method of the catalyst electrode.

[Measurement results of Example 2]
Open circuit voltage (Voc): 0.62V
Short circuit current density (Jsc): 10.2 mA / cm ²
Form factor (FF): 80%
Photoelectric conversion efficiency: 5.1%
Change rate of short-circuit current density after 500 hours: 105%
Change rate of short-circuit current density after 1000 hours: 98%

Example 3
A titanium substrate was used as the metal substrate, treated with hydrochloric acid so as to be porous, then washed thoroughly with water and dried at 100 ° C. When the surface of the metal substrate treated with hydrochloric acid was observed by SEM, it was confirmed to be porous.

  A ruthenium oxide precursor solution was obtained in the same manner as in Example 2, except that ruthenium-n-butoxide was used instead of titanium-n-butoxide in Example 2.

  The obtained ruthenium oxide precursor solution was applied to a metal substrate that had been treated with hydrochloric acid by spin coating, and a metal substrate with a ruthenium oxide thin film of about 1.4 μm was obtained in the same manner as in Example 2. The surface SEM photograph of the obtained thin film reflected the porosity of the underlying metal substrate and confirmed that it had the same porosity.

Using the obtained electrode substrate with a ruthenium oxide thin film as an electrode, platinum was deposited and supported in a sulfuric acid aqueous solution containing [Pt (NH ₃ ) ₄ ] Cl ₂ · nH ₂ O to obtain a catalyst electrode. The particle diameter of the platinum particles on the surface of the catalyst electrode thus obtained was 5 to 10 nm.

  A solar battery cell was produced and evaluated for the obtained catalyst electrode in the same manner as in Example 1 except for the production method of the catalyst electrode.

[Measurement results of Example 3]
Open-circuit voltage (Voc): 0.73V
Short circuit current density (Jsc): 9.5 mA / cm ²
Form factor (FF): 72%
Photoelectric conversion efficiency: 5.0%
Change rate of short-circuit current density after 500 hours: 105%
Change rate of short-circuit current density after 1000 hours: 98%

Example 4
In the production method of the catalyst electrode, the metal substrate and the pretreatment were produced in the same manner as in Example 1.
The indium oxide precursor raw material solution was prepared by concentrating an organic indium compound complex solution obtained by heating and refluxing a 2-propanol aqueous solution containing propoxy indium and diluting with toluene. The tin oxide precursor raw material solution was prepared by heating and refluxing a toluene solution containing acetic acid and tin acetate and then diluting with toluene. Furthermore, the mixed solution of the indium oxide precursor raw material solution and the tin oxide precursor raw material solution was heated to reflux to obtain an ITO precursor raw material solution.

  When the metal substrate coated with the ITO precursor liquid was baked at 400 ° C., a transparent thin film was formed. The film thickness of the obtained thin film was 0.7 μm.

  When the obtained thin film was analyzed using an X-ray diffractometer, it was confirmed by X-ray diffraction pattern that it was so-called ITO in which tin oxide was dissolved in indium oxide. Further, as a result of surface SEM observation of the ITO film, it was confirmed that a homogeneous thin film without cracks was formed.

  The obtained metal substrate with a corrosion-resistant conductive layer was immersed in an aqueous sulfuric acid solution containing 0.1 mol / L of aniline and electrochemically oxidized to form a polyaniline film on the ITO surface. This FTO glass with a polyaniline film was washed with pure water and dried at 100 ° C. in air, and then immersed in a dichloromethane solution in which 5,10,15,20-tetraphenylporphyrin platinum complex was dissolved, and then at 100 ° C. in air. The catalyst electrode was obtained by drying with.

  When the obtained catalyst electrode was observed by surface SEM, it was confirmed that the polyaniline film was a porous body.

  A solar battery cell was produced and evaluated in the same manner as in Example 1 except that the method for producing the catalyst electrode and the area of the semiconductor electrode were 10 cm × 10 cm.

[Measurement results of Example 4]
Open-circuit voltage (Voc): 0.74V
Short circuit current density (Jsc): 11.8 mA / cm ²
Form factor (FF): 81%
Photoelectric conversion efficiency: 7.1%
Change rate of short-circuit current density after 500 hours: 105%
Change rate of short-circuit current density after 1000 hours: 98%

Example 5
In the production method of the catalyst electrode, titanium-coated stainless steel was used as a metal substrate in which the substrate and the metal layer were integrated. The metal substrate was heated at 700 ° C. in a nitrogen atmosphere for 5 hours to form a nitride film on the surface. The obtained metal base with a corrosion-resistant conductive layer was formed in the same manner as in Example 1 to obtain a catalyst electrode.

  When the obtained catalyst electrode was produced and evaluated in the same manner as in Example 1 except for the method for producing the catalyst electrode, the same result as in Example 1 was obtained.

[Measurement results of Example 5]
Open circuit voltage (Voc): 0.67V
Short circuit current density (Jsc): 11.6 mA / cm ²
Form factor (FF): 83%
Photoelectric conversion efficiency: 6.5%
Change rate of short-circuit current density value after 500 hours: 110%
Change rate of short-circuit current density value after 1000 hours: 104%

Example 6
In the method for producing the catalyst electrode, a polyimide foil was used as a base and a titanium foil was used as a metal layer, and both were adhered and used. A slurry prepared by adding titanium boride particles in a polyamic acid solution was applied onto the metal substrate with a bar coater, and then heat-treated at 380 ° C. for 2 hours to form a corrosion-resistant conductive layer.

  Poly (3,4-ethylenedioxythiophene) particles were prepared by chemical polymerization using p-toluenesulfonic acid as a dopant. The obtained poly (3,4-ethylenedioxythiophene) particles were kneaded together with a fluorine-based binder (KF Polymer # 1120 manufactured by Kureha Chemical), and a paste was prepared while adding an appropriate amount of N-methyl-2-pyrrolidone. Further, the obtained paste was squeegee-printed on the corrosion-resistant conductive layer, and then dried at 120 ° C. for 1 hour to obtain a catalyst electrode.

  When the obtained catalyst electrode was produced and evaluated in the same manner as in Example 1 except that the method for producing the catalyst electrode and the area of the semiconductor electrode were changed to 10 cm × 10 cm, the same results as in Example 1 were obtained. Obtained.

[Measurement results of Example 6]
Open circuit voltage (Voc): 0.60V
Short circuit current density (Jsc): 9.8 mA / cm ²
Form factor (FF): 73%
Photoelectric conversion efficiency: 4.3%
Change rate of short-circuit current density value after 500 hours: 92%
Change rate of short-circuit current density after 1000 hours: 95%

Example 7
In the production method of the catalyst electrode, a polyethylene naphthalate (PEN) film was used as a base and a titanium foil was used as a metal layer, and both were adhered and used. A slurry prepared by adding a low molecular weight polyester dissolved in a solvent, tungsten carbide particles, and a curing agent onto the metal layer is applied with a bar coater, and then subjected to a heat treatment at 150 ° C. for 15 minutes to provide a corrosion-resistant conductive material. A layer was obtained.

  A catalyst layer was formed on the corrosion-resistant conductive layer in the same manner as in Example 2.

  A solar battery cell was produced and evaluated for the obtained catalyst electrode in the same manner as in Example 1 except that the production method of the catalyst electrode and the area of the semiconductor electrode were 10 cm × 10 cm.

[Measurement results of Example 7]
Open circuit voltage (Voc): 0.62V
Short circuit current density (Jsc): 9.1 mA / cm ²
Form factor (FF): 78%
Photoelectric conversion efficiency: 4.4%
Short-circuit current density value change rate after 500 hours: 82%
Change rate of short-circuit current density after 1000 hours: 85%

Comparative Example 1
A solar battery cell was prepared and evaluated in the same manner as in Example 1 except that the zinc oxide layer as the corrosion-resistant conductive layer 10 was not formed among the methods for preparing the catalyst electrode.

[Measurement results of Comparative Example 1]
Open circuit voltage (Voc): 0.60V
Short circuit current density (Jsc): 12.2 mA / cm ₂
Form factor (FF): 60%
Photoelectric conversion efficiency: 4.4%
Short-circuit current density change rate after 500 hours: 63%
Change rate of short-circuit current density after 1000 hours: 27%

Comparative Example 2
Except for the method for producing the catalyst electrode, solar cells were produced and evaluated in the same manner as in Example 4. In the catalyst electrode, FTO glass was used instead of the metal substrate. Using an electrode substrate that has been ultrasonically cleaned in an organic solvent and an aqueous solution and dried at 120 ° C. as an electrode, platinum is deposited and supported in a sulfuric acid aqueous solution containing [Pt (NH ₃ ) ₄ ] Cl ₂ · nH ₂ O. Then, a catalyst electrode was obtained. The particle diameter of the platinum particles on the surface of the catalyst electrode thus obtained was 200 nm to 300 nm.

[Measurement results of Comparative Example 2]
Open circuit voltage (Voc): 0.58V
Short circuit current density (Jsc): 10.9 mA / cm ²
Form factor (FF): 22%
Photoelectric conversion efficiency: 1.4%

  From the above results, it is shown that the dye-sensitized solar cell provided with the catalyst electrode of the present invention has excellent performance.

  The catalyst electrode of the present invention is preferably used as a counter electrode of a dye-sensitized solar cell, but can also be used as an electrode other than the counter electrode of a dye-sensitized solar cell. For example, it can be suitably used as an electrode for organic synthesis and an electrode used in an electrochemical device.

The cross-sectional schematic diagram which shows the structure of the dye-sensitized solar cell of this invention. An example of the cross-sectional schematic diagram which shows the structure of the catalyst electrode of this invention. An example of the cross-sectional schematic diagram which shows the structure of the catalyst electrode of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrode base 2 Transparent base 3 Transparent conductive film 4 Porous metal oxide semiconductor layer 5 Sensitizing dye layer 6 Electrolyte layer 7 Catalyst electrode 8 Electrode base 9 Metal layer 10 Corrosion-resistant conductive layer

Claims (16)

In a dye-sensitized solar cell having a light-transmitting semiconductor electrode containing a dye having a photosensitizing action and an electrolyte layer containing a chemical species serving as a redox pair, the semiconductor electrode faces the semiconductor electrode through the electrolyte layer. A catalyst electrode disposed,
The catalyst electrode includes at least a metal layer and a corrosion-resistant conductive layer formed on the metal layer,
A catalyst electrode comprising a catalyst compound in the corrosion-resistant conductive layer. The catalyst according to claim 1, wherein the metal layer is made of at least one metal selected from iron, nickel, chromium, molybdenum, titanium, and aluminum, or an alloy thereof, or stainless steel. electrode. The catalyst electrode according to claim 1, wherein the corrosion-resistant conductive layer is made of a metal oxide. The metal oxide contains at least one selected from tin oxide, indium oxide, a mixture of tin oxide and indium oxide, titanium oxide, zinc oxide, iridium oxide, or ruthenium oxide. The catalyst electrode according to claim 3. The catalyst electrode according to claim 1, wherein the corrosion-resistant conductive layer is made of a metal nitride. 6. The catalyst electrode according to claim 5, wherein the metal nitride is a metal nitride selected from at least one of chromium, titanium, zirconium, vanadium, and niobium. The catalyst electrode according to claim 1, wherein the corrosion-resistant conductive layer is made of a metal boride. 8. The metal boride according to claim 7, wherein the metal boride is a boride of a metal selected from at least one of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten. Catalytic electrode. The catalyst electrode according to claim 1, wherein the corrosion-resistant conductive layer is made of a metal carbide. The catalyst electrode according to claim 9, wherein the metal carbide is a carbide of metal selected from at least one of titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, or tungsten. 11. The catalyst electrode according to claim 3, wherein the electrical conductivity of the corrosion-resistant conductive layer is 1 × 10 ⁻⁹ S / cm or more. 2. The catalyst electrode according to claim 1, wherein the catalyst compound comprises at least one selected from a transition metal, a conductive carbon material, a conductive polymer material, or an organometallic complex. The catalyst electrode according to claim 12, wherein the transition metal is platinum. The catalyst electrode according to claim 12, wherein the conductive polymer material is at least one polymer selected from pyrrole, thiophene, aniline, and derivatives thereof. The catalyst electrode according to claim 12, wherein the organometallic complex is at least one selected from a porphyrin complex, a phthalocyanine complex, and derivatives thereof. A dye having a light-transmitting semiconductor electrode containing a dye having a photosensitizing action, an electrolyte layer containing at least a chemical species serving as a redox pair, and a counter electrode disposed opposite to the semiconductor electrode via the electrolyte layer A sensitized solar cell,
The dye-sensitized solar cell, wherein the counter electrode is the catalyst electrode according to any one of claims 1 to 15.

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