JP2006066278A - Electrode for dye-sensitized solar cell, and dye-sensitized solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode for a dye-sensitized solar cell having a transparent conductive film formed on a base and designed to reduce the resistance of the electrode by providing a mesh-shaped conductor made of a metal or alloy lower in resistance than the transparent conductive film to serve as an auxiliary electrode, the electrode for a dye-sensitized solar cell solving the problem of corrosion of the auxiliary electrode due to the electrolyte more reliably and having high durability and reliability. <P>SOLUTION: An auxiliary electrode 12 formed of a mesh of a metal or alloy is provided on a base film 11. A transparent semiconductor film 13 is formed on the auxiliary electrode 12, and a transparent conductive film 14 is formed as the uppermost layer. The metal or alloy used to form the auxiliary electrode 12 is a material lower in resistance than the transparent conductive film 14. The provision of the semiconductor film 13 prevents the auxiliary electrode 12 and the transparent conductive film 14 from being in direct contact with each other and prevents the formation of a local battery. It is thereby possible to prevent the auxiliary electrode 12 from suffering degradation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dye-sensitized solar cell electrode and a dye-sensitized solar cell, and more particularly, in a dye-sensitized solar cell electrode in which a transparent conductive film is formed on a substrate, than the transparent conductive film. An electrode for a dye-sensitized solar cell in which a mesh-like conductor made of a metal or alloy having a low resistance value is provided as an auxiliary electrode to reduce the resistance of the electrode, and the problem of corrosion of the auxiliary electrode due to an electrolyte solution The present invention relates to an electrode for a dye-sensitized solar cell improved in the above and a dye-sensitized solar cell provided with the electrode for a dye-sensitized solar cell.

  It is already known that a solar cell is configured using an oxide semiconductor adsorbed with a sensitizing dye as an electrode. FIG. 4 is a cross-sectional view showing a general structure of such a dye-sensitized solar cell. As shown in FIG. 4, a transparent conductive film 2 such as FTO (fluorine-doped tin oxide) or ITO (indium tin oxide) is provided on a substrate 1 such as a glass substrate, and a spectral sensitizing dye is formed on the transparent conductive film 2. A metal oxide semiconductor film 3 in which is adsorbed is formed. A counter electrode 5 is disposed opposite to the dye-sensitized semiconductor electrode 4 with a space therebetween, and an electrolyte 6 is sealed between the dye-sensitized semiconductor electrode 4 and the counter electrode 5 by a sealing material (not shown). Has been. Reference numeral 7 denotes an insulating spacer provided at the peripheral edge in order to maintain the distance between the semiconductor electrode 4 and the counter electrode 5.

The dye-adsorbing semiconductor film 3 is usually composed of a titanium oxide thin film on which a dye is adsorbed. The dye adsorbed on the titanium oxide thin film is excited by visible light, and the generated electrons are transferred to titanium oxide fine particles to generate power. Done. In the counter electrode 4, a transparent conductive film such as ITO or FTO is formed on a substrate such as glass or plastic, and the transfer of electrons between the transparent conductive film and the sensitizing dye is promoted on the transparent conductive film. The platinum film or carbon film as the catalyst is formed to a thickness that does not decrease the transmittance. As the electrolyte 6, redox substances, for example, LiI, NaI, KI, combinations of metal iodides and iodine, such as CaI _2, LiBr, NaBr, KBr, the metal bromide and bromine, such as CaBr ₂ combination, preferably Uses an electrolytic solution prepared by dissolving a redox substance composed of a combination of metal iodide and iodine in a solvent such as a carbonate compound such as propylene carbonate or a nitrile compound such as acetonitrile.

  When a metal or alloy film having a lower resistance than a metal oxide film such as ITO is formed as a transparent conductive film provided on the substrate of the counter electrode or semiconductor electrode of the dye-sensitized solar cell, iodine or the like in the electrolyte solution Since this film is subject to corrosion, such a film cannot be formed. In addition, in order to reduce the thickness and weight of the dye-sensitized solar cell electrode, when the substrate is a polymer film having a lower heat resistance than the glass substrate, a transparent conductive material with low resistance is caused by the problem of restrictions during film formation. Formation of the film is difficult. For this reason, conventionally, a metal oxide film such as ITO has been adopted as the transparent conductive film of the counter electrode and the semiconductor electrode, but the transparent conductive film made of such a metal oxide film has a resistance value. This is not sufficiently low, and this causes a decrease in the photoelectric conversion efficiency of the dye-sensitized solar cell. In particular, when the area is increased, the loss due to the resistance of the transparent conductive film causes a decrease in photoelectric conversion efficiency.

  As an electrode for a dye-sensitized solar cell effective in improving the photoelectric conversion efficiency of a dye-sensitized solar cell, which solves the above-described conventional problems, has a sufficiently low resistance value, and is not easily corroded by an electrolytic solution. As shown in FIG. 3, the applicant of the present invention firstly, in the electrode for a dye-sensitized solar cell in which the transparent conductive film 14 is formed on the base film 11, between the base film 11 and the transparent conductive film 14. In addition, a dye-sensitized solar cell electrode provided with a mesh-like conductor (hereinafter, this conductor may be referred to as “auxiliary electrode”) 12 having a lower resistance value than the transparent conductive film is proposed ( (Japanese Patent Application No. 2003-85559, hereinafter referred to as “prior application”).

With the dye-sensitized solar cell electrode 10 of the prior application, the resistance of the electrode can be reduced by the auxiliary electrode 12 made of a mesh conductor having a resistance value lower than that of the transparent conductive film 14.
Japanese Patent Application No. 2003-85559

  In the dye-sensitized solar cell electrode 10 of the prior application, although the auxiliary electrode 12 is covered with the transparent conductive film 14, corrosion of the corrosive auxiliary electrode due to the electrolytic solution cannot be reliably prevented. In particular, when the auxiliary electrode, the transparent conductive film, and the electrolytic solution are in contact with each other to form a base material, the mesh-shaped conductor is easily corroded.

  The present invention relates to an electrode for a dye-sensitized solar cell in which a transparent conductive film is formed on a substrate, and a mesh-like conductor made of a metal or alloy having a lower resistance value than the transparent conductive film is used as an auxiliary electrode. In the electrode for dye-sensitized solar cells, the resistance of the electrode is reduced by providing it as an electrode, and the problem of corrosion due to the electrolyte solution of the auxiliary electrode is more reliably solved, and the dye sensitization with excellent durability and reliability is achieved. An object of the present invention is to provide a dye-sensitized solar cell including the electrode for a sensitive solar cell and the electrode for the dye-sensitized solar cell.

  The electrode for a dye-sensitized solar cell of the present invention (invention 1) comprises a transparent conductive film and a mesh auxiliary electrode made of a metal or alloy having a lower resistance value than the transparent conductive film on a substrate. A dye-sensitized solar cell electrode provided, wherein a semiconductor film is formed between the transparent conductive film and the auxiliary electrode.

  The electrode for a dye-sensitized solar cell according to claim 2 is characterized in that, in claim 1, the semiconductor film is made of a metal oxide.

  A dye-sensitized solar cell electrode according to claim 3 is characterized in that, in claim 2, the semiconductor film is made of at least one of titanium oxide, niobium oxide, magnesium oxide, silicon oxide, and aluminum oxide. is there.

  A dye-sensitized solar cell electrode according to claim 4 is characterized in that, in any one of claims 1 to 3, the transparent electrode film / semiconductor film / auxiliary electrode / base material are laminated in this order. It is.

  The electrode for a dye-sensitized solar cell according to claim 5 is characterized in that, in any one of claims 1 to 3, the auxiliary electrode / semiconductor film / transparent electrode film / substrate are laminated in this order. It is characterized by.

  A dye-sensitized solar cell electrode according to claim 6 is characterized in that, in any one of claims 1 to 5, the transparent electrode film is ITO, FTO, ATO, AZO or GZO. .

  A dye-sensitized solar cell electrode according to claim 7 is characterized in that, in any one of claims 1 to 6, the auxiliary electrode is made of at least one of aluminum, copper and silver.

  An electrode for a dye-sensitized solar cell according to claim 8 is characterized in that the surface of the auxiliary electrode is passivated in any one of claims 1 to 7.

  A dye-sensitized solar cell electrode according to a ninth aspect is characterized in that, in any one of the first to eighth aspects, the substrate is made of a polymer film.

  The dye-sensitized solar cell of the present invention (invention 10) is characterized by including the dye-sensitized solar cell electrode according to any one of claims 1 to 9.

  The electrode for a dye-sensitized solar cell according to the present invention has a semiconductor film provided between a transparent conductive film and an auxiliary electrode to prevent direct contact between the transparent conductive film and the auxiliary electrode. Formation of the local battery by the electrode and the electrolyte is prevented. Thereby, corrosion of the auxiliary electrode made of the mesh-like conductor is sufficiently prevented.

  DESCRIPTION OF EMBODIMENTS Embodiments of an electrode for a dye-sensitized solar cell and a dye-sensitized solar cell according to the present invention will be described below in detail with reference to the drawings.

  FIG.1 and FIG.2 (a) is a perspective view which shows embodiment of the electrode for dye-sensitized solar cells of this invention, FIG.2 (b) follows the BB line of Fig.2 (a). It is sectional drawing.

  In the dye-sensitized solar cell electrode 10A of FIG. 1, an auxiliary electrode 12 made of a metal or alloy mesh is provided on a base film 11, a transparent semiconductor film 13 is formed thereon, and a transparent conductive film is formed as the outermost layer. A film 14 is formed.

  Since the base film 11 is excellent in transparency and birefringence, a polymer film such as polycarbonate, polymethyl methacrylate, polyvinyl chloride, polystyrene, or polyethylene terephthalate is used, and the thickness is usually 12 μm. About 2 mm.

  The metal or alloy forming the auxiliary electrode 12 may be any material having a lower resistance value than that of the transparent conductive film 14, and is not particularly limited, but generally Ag, Ag alloy (Ag / Pd, Ag / P) Nd, Ag / Au, etc.), Cu, Cu alloy, Al, Al alloy are preferable, but Ni, Cr alloy, etc. may be used.

  Although it is conceivable that the auxiliary electrode 12 is formed in a thin film so as not to impair the transparency, the film-shaped auxiliary electrode formed in such a thin film cannot obtain a sufficiently low resistance effect. From FIG. 1, it is formed in a mesh shape. There are no particular restrictions on the wire diameter and mesh opening of the mesh-like auxiliary electrode 12, but if the wire diameter is excessively thin and the mesh opening is excessively large, a sufficient resistance reduction effect cannot be obtained, and conversely If the diameter is excessively large and the opening is excessively small, the transparency of the electrode is impaired. Therefore, it is preferable that the mesh auxiliary electrode 12 has a wire diameter of 10 to 1000 μm and an opening (area ratio of the opening to the electrode area) of 80% or more. In addition, it is preferable that the thickness (height) of the auxiliary electrode 12 is about 0.1 to 10 μm.

  The transparent conductive film 14 is a transparent conductive film such as indium oxide-based ITO, tin oxide-based FTO, ATO, zinc oxide-based AZO, and GZO, and the film thickness is usually about 100 to 1000 nm. preferable.

  The transparent conductive film 14 is preferably formed by a sputtering method, and particularly preferably formed by a reactive sputtering method using an oxygen atmosphere gas. If it is a sputtering method, the transparent conductive film 14 which consists of a favorable low resistance film can be formed at the low temperature below the heat-resistant temperature of the base film 11, and it is efficient.

  As the transparent semiconductor film 13, a metal oxide film such as titanium oxide, niobium oxide, magnesium oxide, silicon oxide, or aluminum oxide can be used.

  The semiconductor film 13 can be formed by a sputtering method, preferably a reactive sputtering method using a metal target. Further, it can be formed by a precipitation method using a chemical solution, a method of applying a peroxide and heat treatment, or a sol-gel method. In particular, a sputtering method can form a dense semiconductor film with excellent barrier properties.

  If the semiconductor film 13 is too thin, the effect of preventing the formation of a local battery due to the formation of the semiconductor film 13 cannot be sufficiently obtained. If the semiconductor film 13 is too thick, the film is likely to be cracked. preferable.

  By providing such a semiconductor film 13, the auxiliary electrode 12 and the transparent conductive film 14 are not in direct contact with each other, so that the formation of a local battery can be prevented and deterioration of the auxiliary electrode 12 can be prevented.

  A dye-sensitized solar cell electrode 10B shown in FIG. 2 is obtained by providing a transparent conductive film 14, a transparent semiconductor film 13, and an auxiliary electrode 12A with a protective film on a base film 11 in this order. The auxiliary electrode 12A with the protective film is formed by forming the auxiliary electrode 12 from a metal or an alloy thereof that can easily form a passive film, and forming a passive film as the protective film 15 on the auxiliary electrode surface during use. The surface of the electrode 12 is oxidized to form a passive film as the protective film 15. Other configurations of the base film 11, the transparent conductive film 14, and the semiconductor film 13, the wire diameters and openings of the auxiliary electrodes 12 are the same as those in FIG. 1.

  In the dye-sensitized solar cell electrode 10B of FIG. 2, as a metal or alloy that easily forms a passive film, one kind of metal such as Ti, Ni, Al or the like, or one or more of these may be used. Including alloys.

  Even when the passive film is formed by oxidation treatment, the auxiliary electrode 12 is preferably formed of a metal or an alloy that easily forms the passive film as described above.

  The oxidation treatment for forming the passive film can be performed by metal anode treatment, ultraviolet irradiation in an oxidizing gas atmosphere, or plasma treatment in an oxidizing gas atmosphere. Here, the oxidizing gas atmosphere is oxygen, ozone, or a gas atmosphere containing these gases.

  The passive film is preferably formed on the surface of the auxiliary electrode 12 to a thickness of about 1 to 50 nm.

  By forming the protective film 15 made of such a passive film, it is possible to reliably protect the auxiliary electrode 12 from the electrolytic solution and prevent the auxiliary electrode 12 from deteriorating.

  In the dye-sensitized solar cell electrode 10B shown in FIG. 2, when a titanium oxide nanoporous semiconductor film is formed as the transparent semiconductor film 13 disposed on the electrolyte side of the transparent conductive film 14, The semiconductor film 13 can be given a function as a semiconductor layer of a semiconductor electrode, and the dye-sensitized solar cell electrode can be used as it is as a dye-sensitized solar cell semiconductor electrode.

  The electrode for a dye-sensitized solar cell of the present invention is particularly suitable for a counter electrode of a dye-sensitized solar cell in which a platinum thin film is provided on a transparent conductive film, and this platinum thin film is also formed by sputtering. It is preferable that However, as described above, in the dye-sensitized solar cell electrode in which the titanium oxide nanoporous semiconductor film is formed as the electrolyte-side semiconductor film 13 in the embodiment of FIG. 2, the dye-sensitized solar cell semiconductor electrode is used. Can also be suitably used.

  The dye-sensitized solar cell of the present invention is assembled according to a conventional method using such an electrode of the present invention.

  The present invention is particularly suitable for a film-type dye-sensitized solar cell electrode using a base film, but is not limited to this, and a dye-sensitized solar cell electrode using a glass substrate. It can also be applied to.

  Below, the suitable formation method of the auxiliary electrode 12 which consists of a mesh-shaped conductor which concerns on this invention is demonstrated with reference to FIG. FIG. 5 is a schematic cross-sectional view showing an example of the manufacturing procedure of the mesh conductor according to the present invention.

  First, as in (1) and (2), dots 22 are printed on the polymer film 21 using a material that is soluble in a solvent such as water. Next, as shown in (3), a conductive material layer 23 is formed so as to cover all of the exposed surfaces of the polymer film 21 on the dots 22 and between the dots 22. Next, the film 21 is washed with a solvent such as water. At this time, if necessary, dissolution accelerating means such as ultrasonic irradiation, rubbing with a brush, sponge or the like may be used in combination.

  Thereby, as shown in (4), the soluble dots 22 are dissolved, and the conductive material on the dots 22 is also peeled off from the film 21 and removed. Then, a mesh-like conductor pattern 24 made of a conductive material formed in a region between the dots remains on the film 21. Since the mesh-like conductor pattern 24 occupies the area between the dots 22, the mesh-like conductor pattern 24 has a mesh shape as a whole.

  Therefore, by reducing the gap between the dots 22, a mesh-like mesh-like conductor pattern 24 having a small line width is formed. Further, by increasing the area of each dot 22, a mesh-like conductor pattern 24 having a large aperture ratio is formed. The printing material soluble in water or the like for forming the dots 22 does not need to disperse the fine particles, and a low viscosity material is sufficient. According to this low-viscosity printing material, dots can be printed so as to have a fine dot pattern.

  After the step (4), finish cleaning (rinsing) is performed as necessary, and drying is performed.

  The dots 22 formed on the polymer film 21 are preferably formed by printing. As the printing material, a solution of a material that is soluble in a solvent for removing the dots 22 is used. The solvent for removing the dots 22 may be an organic solvent, but water is preferable because it is inexpensive and has an influence on the environment. The water may be an aqueous solution containing an acid, an alkali or a surfactant in addition to normal water. This printing material may be mixed with a pigment or a dye to make it easy to check the print finish.

  In view of the relationship that the solvent is water as described above, a water-soluble polymer material is preferable as a material for forming the dots 22, and specifically, polyvinyl alcohol or the like is preferable.

  The dots 22 are printed so that the film exposure area between them is a mesh. Preferably, the film exposure region is printed so that the line width is 30 μm or less. As a printing method, gravure printing, screen printing, inkjet printing, and electrostatic printing are suitable, but gravure printing is suitable for thinning.

  The shape of the dot 22 is arbitrary such as a circle, an ellipse, and a square, but is preferably a square, particularly a square. The printing thickness of the dots 22 is not particularly limited, but is usually about 0.1 to 5 μm.

  After the dots 22 are printed, they are preferably dried, and then the conductive material layer 23 is formed using the auxiliary electrode forming material described above.

  Examples of the method for forming the conductive material layer 23 include vapor phase plating methods such as sputtering, ion plating, vacuum vapor deposition, and chemical vapor deposition, liquid phase plating (electrolytic plating, electroless plating, etc.), printing, and application. However, vapor phase plating (sputtering, ion plating, vacuum deposition, chemical vapor deposition) or liquid phase plating in a broad sense is suitable.

  After the formation of the conductive material layer 23, as described above, the dots 22 are removed using a solvent, preferably water, and dried as necessary to form a mesh-like conductor as an auxiliary electrode.

  It is possible to further reduce the resistance by further wet-plating the formed mesh conductor to form a wet plating layer.

  Thus, the first step of forming the mesh-like conductor as the auxiliary electrode on the substrate surface with a substance soluble in the solvent, and then insoluble in the solvent on the substrate surface By forming through a second step of forming a conductive material layer made of a conductive material, and then a third step of contacting the substrate surface with a solvent to remove the dots and the conductive material layer on the dots, A mesh-like conductor having high light transmittance and high conductivity can be easily and efficiently formed at a low temperature. That is, dots can be printed and formed with a low-viscosity material as a material soluble in a solvent. For this reason, it is possible to perform fine and fine printing so that the interval between dots is remarkably reduced. Since the thin region between the dots is a region in which the conductive material remains later and becomes a mesh-like conductor, according to the present invention, an extremely thin conductive mesh pattern can be formed with high accuracy. . By reducing the line width, the mesh aperture ratio can be increased.

  Although the auxiliary electrode is directly formed on the film 21 in FIG. 5, the auxiliary electrode can be formed in the same manner when a transparent conductive film and a semiconductor film are formed on the film.

It is a perspective view which shows embodiment of the electrode for dye-sensitized solar cells of this invention. FIG. 2A is a perspective view showing another embodiment of the dye-sensitized solar cell electrode of the present invention, and FIG. 2B is a cross-sectional view taken along line BB in FIG. It is an enlarged view. It is a perspective view which shows embodiment of the electrode for dye-sensitized solar cells of a prior application. It is sectional drawing which shows the general structure of a dye-sensitized solar cell. It is typical sectional drawing which shows an example of the manufacture procedure of a mesh-shaped conductor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Transparent conductive film 3 Dye adsorption semiconductor film 4 Dye sensitized semiconductor electrode 5 Counter electrode 6 Electrolyte 7 Spacer 10, 10A, 10B Dye sensitized solar cell electrode 11 Base film 12 Auxiliary electrode 12A Auxiliary with protective film Electrode 13 Transparent semiconductor film 14 Transparent conductive film 15 Protective film 21 Base film (polymer film)
22 dots 23 conductive material layer 24 mesh conductor pattern

Claims (10)

On a substrate, a dye-sensitized solar cell electrode provided with a transparent conductive film and a mesh auxiliary electrode made of a metal or alloy having a lower resistance than the transparent conductive film,
A dye-sensitized solar cell electrode, wherein a semiconductor film is formed between the transparent conductive film and the auxiliary electrode.   2. The dye-sensitized solar cell electrode according to claim 1, wherein the semiconductor film is made of a metal oxide.   3. The dye-sensitized solar cell electrode according to claim 2, wherein the semiconductor film is made of at least one of titanium oxide, niobium oxide, magnesium oxide, silicon oxide, and aluminum oxide.   4. The dye-sensitized solar cell electrode according to claim 1, wherein the electrode is laminated in the order of transparent electrode film / semiconductor film / auxiliary electrode / base material. 5.   4. The dye-sensitized solar cell electrode according to claim 1, wherein the electrode is laminated in the order of auxiliary electrode / semiconductor film / transparent electrode film / base material. 5.   6. The dye-sensitized solar cell electrode according to claim 1, wherein the transparent electrode film is ITO, FTO, ATO, AZO, or GZO.   The dye-sensitized solar cell electrode according to any one of claims 1 to 6, wherein the auxiliary electrode is made of at least one of aluminum, copper, and silver.   8. The dye-sensitized solar cell electrode according to claim 1, wherein a surface of the auxiliary electrode is passivated.   9. The dye-sensitized solar cell electrode according to claim 1, wherein the substrate is made of a polymer film.   A dye-sensitized solar cell comprising the electrode for a dye-sensitized solar cell according to any one of claims 1 to 9.

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