JPWO2005122322A1 - Dye-sensitized solar cell and method for producing the same - Google Patents

Abstract

A dye-sensitized solar cell having excellent reproducibility and stable performance by keeping the distance between two substrates constant and controlling the amount and fluidity of the electrolyte held between the substrates, and a method for producing the same I will provide a. In a dye-sensitized solar cell in which at least one transparent substrate surface is overlaid with two substrates on which a transparent conductive film and a dye-sensitized semiconductor electrode are formed, and an electrolytic solution is sealed between the two substrates A dye-sensitized solar cell, wherein a member that functions as an electrode, which is a mesh-like member composed of two or more wires, is disposed between the two substrates.

Description

  The present invention relates to a dye-sensitized solar cell that directly converts light energy into electric energy and a method for manufacturing the same.

  The dye-sensitized solar cell announced by Gretzell et al. In 1991 operates by a mechanism different from that of a silicon semiconductor pn junction solar cell and has the advantage of high conversion efficiency and low manufacturing cost. Since the electrolyte is sealed inside, it is also called a dye-sensitized solar cell.

In this solar cell, as shown in FIG. 4, a transparent conductive film 7 formed on one surface of the transparent substrate 1 and a semiconductor electrode carrying a sensitizing dye (dye-sensitized semiconductor electrode 4) are formed. The conductive substrate 5 is overlaid in a state where the electrolytic solution is contained, and the periphery thereof is coated with a resin and sealed. When a coating of a sensitizing dye capable of efficiently absorbing sunlight, such as a ruthenium complex, is used as a dye-sensitized semiconductor electrode on a porous titanium oxide film provided on the surface of a conductive substrate, Electrons excited by light can be injected into titanium oxide to flow electricity. In this type of solar cell, an electrolytic solution is required for transferring electrons, and an iodine electrolytic solution is generally used.
Japanese Patent Publication No. 8-15097. JP 2000-173680 A.

  In the conventional dye-sensitized solar cell shown in FIG. 4, only a thick resin is applied to the peripheral portion (near the cross-sectional portion) and cured in order to seal the electrolytic solution. The amount of electrolyte is not constant because it varies from one battery production to another, or even within a single solar cell. Reproducibility and stability such as the electrolyte flowing out when the solar cell is tilted. There was a problem.

  In addition, the porous titanium oxide film used as the dye-sensitized semiconductor electrode has a surface irregularity shape that varies depending on the coating method, particle size, and thickness, but the convex portion is in contact with the conductive film of the opposing substrate. As a result, the dye-sensitized semiconductor electrode and the conductive film are energized without passing through the electrolyte solution, so that electrons are not sufficiently transferred, resulting in a decrease in efficiency as a solar cell and unstable performance. Invitation

  Therefore, the present invention has been made in view of such problems, and is reproduced by keeping the distance between the two substrates constant and controlling the amount and fluidity of the electrolyte held between the substrates. It is an object of the present invention to provide a dye-sensitized solar cell having excellent properties and stable performance and a method for producing the same.

  As a result of intensive studies, the inventors have conceived that the above problem can be solved by sandwiching a wire braided between both substrates of the dye-sensitized solar cell and holding the electrolytic solution thereby. .

  That is, the present invention relates to a dye obtained by superposing two substrates each having a transparent conductive film and a dye-sensitized semiconductor electrode formed on the surface of at least one transparent substrate, and encapsulating an electrolyte between the two substrates. In the sensitized solar cell, a dye-sensitized solar cell comprising a member formed by weaving two or more wires in a mesh shape and serving as an electrode between the two substrates. Is to provide.

  The dye-sensitized solar cell of the present invention is characterized in that the wire has conductivity. Alternatively, the wire may be insulative, and a conductive film may be formed on one or both surfaces of the wire.

  In the dye-sensitized solar cell of the present invention, the thickness of the wire is larger than the height of the unevenness on the surface of the substrate on which the transparent conductive film and the dye-sensitized semiconductor electrode are formed.

  The dye-sensitized solar cell of the present invention is characterized in that the substrate on which the transparent conductive film and the dye-sensitized semiconductor electrode are not formed is insulating among the two substrates.

  As described above, according to the present invention, by disposing the electrolyte solution holding / electrode material between the two substrates, the amount of the electrolyte solution held is stabilized, the fluidity is suppressed, and the dye increase Since the sensitive semiconductor electrode and the conductive film are not energized without passing through the electrolytic solution, a dye-sensitized solar cell having high efficiency, excellent reproducibility and stable performance is provided.

It is a schematic sectional drawing which shows the structural example of the dye-sensitized solar cell of this invention. It is a process flow figure which shows the example of the manufacturing process of the dye-sensitized solar cell of this invention. It is a figure which shows the structural example of the electrolyte solution holding | maintenance and electrode material in the dye-sensitized solar cell of this invention. It is a schematic sectional drawing which shows the structural example of the conventional dye-sensitized solar cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Electrolyte holding / electrode material 3 Electrolytic solution 4 Dye-sensitized semiconductor electrode 5 Transparent glass substrate 6 Transparent conductive film 7 Conductive film 8 Sealing material

  Hereinafter, a dye-sensitized solar cell as an embodiment of the present invention will be described with reference to the drawings. A schematic cross-sectional view of a dye-sensitized solar cell according to an embodiment of the present invention is shown in FIG.

  In FIG. 1, the dye-sensitized solar cell of this embodiment has a substrate 1 and a transparent glass substrate 5 on which a dye-sensitized semiconductor electrode 4 and a transparent conductive film 6 are formed. Between them, a mesh-like electrolyte solution holding / electrode material 2 is arranged, and the electrolyte solution 3 is included. Although both substrates are sealed by applying a sealing material to the side surfaces, the illustration is omitted here.

  The substrate 1 can be composed of an insulating glass substrate, a ceramic substrate, a substrate on which a conductive material such as metal or carbon is formed, or a metal plate. The transparent glass substrate 5 may be replaced with a transparent plastic substrate or the like. The dye-sensitized semiconductor electrode 4 can be composed of titanium oxide, tantalum oxide, niobium oxide, zirconium oxide, or the like, but is not limited thereto. The transparent conductive film 6 can be composed of ITO (tin-containing indium oxide), tin oxide, zinc oxide, or the like, but is not limited to these, and platinum or a film having a thickness that does not decrease the transmittance. A metal or carbon film is also applicable. The sealing material is a material whose hardness changes depending on temperature, and may be any material that can seal between substrates.

  The electrolyte solution holding / electrode material 2 has a mesh shape in which a plurality of wire rods are knitted in a mesh shape, and there are plain weave, twill weave, plain tatami weave, twill tatami weave, and the like. Not only one knitted wire, but also knitted stranded wire twisting two or more wires may be used. The shape of the wire for the electrolyte solution holding / electrode material 2 may be a prismatic shape, a cylindrical shape, or the like, but is not limited thereto. The thickness of the electrolytic solution holding / electrode material 2 may be larger than the unevenness of the surface of the conductive substrate or the unevenness of the dye-sensitized semiconductor electrode 4, and is generally about several μm to 1 mm, more preferably several tens of μm. ˜about several hundred μm. The electrolyte solution holding / electrode material 2 mesh spacing, wire diameter, etc., can be arbitrarily selected so that the electrolyte solution is immersed in between the meshes or between the wire materials, thereby suppressing the flow of the electrolyte solution. Good.

  The material of the electrolyte holding / electrode material 2 is made of an insulating material made of a polymer such as glass, ceramics such as alumina, nylon or polyimide, as well as those using metallic conductive materials such as stainless steel, Al and Ni. The surface of one side may be coated with a metal such as Pt, carbon, Al, or Ni by vapor deposition or plating, but is not limited to these. Any material that does not repel liquid (water repellency) may be used.

  Next, the manufacturing method of the dye-sensitized solar cell of embodiment of this invention is demonstrated, referring FIG.

  First, as the transparent glass substrate 5, a transparent glass substrate or a plastic substrate is prepared, and the film thickness is such that the substrate is made of ITO (tin-containing indium oxide), tin oxide, zinc oxide, or the like, or the transmittance is not lowered. A transparent conductive film 6 made of a metal such as platinum, Ti, or a carbon film is formed.

  Next, a colloidal solution containing metal oxide fine particles such as titanium oxide, tantalum oxide, niobium oxide, zirconium oxide and a small amount of organic polymer is applied on the surface of the transparent conductive film 6 by a printing method or the like. After drying, the organic polymer is volatilized by heat treatment at a temperature of 500 ° C. At this time, fine pores are formed on the surface coated with the metal oxide fine particles. Here, the height of the irregularities on the surface is measured with a surface shape evaluation apparatus such as an α step. The porous metal oxide film thus formed on the surface of the transparent conductive film 6 is immersed in a sensitizing dye solution, and the sensitizing dye is adsorbed on the surface to form the dye-sensitized semiconductor electrode 4. To do.

  On the dye-sensitized semiconductor electrode 4 formed on the transparent conductive substrate 5 in this manner, the electrolytic solution holding / electrode material 2 knitted in a mesh shape is disposed. FIG. 3 is a top view schematically showing the arrangement of the electrolytic solution holding / electrode material 2. At this time, the electrolytic solution holding / electrode material 2 is prepared with a thickness larger than the height of the unevenness on the surface of the dye-sensitized semiconductor electrode 4 measured as described above.

  Thereafter, the substrate 1 is overlapped with the electrolyte solution holding / electrode material 2 sandwiched from above, an iodine electrolyte solution is injected between the substrates, and a sealing material is applied around the substrate. The electrolytic solution 3 is not limited to the iodine electrolytic solution, and may be an organic electrolytic solution containing oxidation / reduction species.

Example 1
The dye-sensitized solar cell according to the above-described embodiment was manufactured according to the following procedure. Two glass substrates each having a size of 2 × 3 cm and a thickness of 2.8 mm were prepared, and an ITO film was formed as a transparent conductive film 6 by 200 nm on one sheet by a sputtering method. The height of the irregularities on the surface was approximately 1 μm or less. After masking and coating with tape or the like on the substrate 5 on which the transparent conductive film 6 was formed, titanium oxide for photocatalyst having a particle size of about 20 nm was added with water, polyethylene glycol and nitric acid, mixed well to form a paste, and printed.

  Next, it was heat-treated at 500 ° C. for 30 minutes in the atmosphere, and cooled to obtain a titania film having an average thickness of about 10 μm. The height of the unevenness on the surface was approximately 30 μm or less. Accordingly, the electrolytic solution holding / electrode material 2 to be used has a thickness of 30 μm or more. Further, the titania film formed above was immersed in an acetonitrile solution of a ruthenium complex. As a result, the ruthenium complex, which is a sensitizing dye, was adsorbed and coated on the titanium oxide fine particles constituting the film, and the dye-sensitized semiconductor electrode 4 was formed.

  As the electrolyte solution holding / electrode material 2, a wire having three ropes made of stainless steel having a diameter of 16 μm was formed, and then a mesh having a mesh shape with a pitch of about 100 μm was prepared. The thickness was about 50 μm. The substrate 5 on which the dye-sensitized semiconductor electrode 4 was formed and the other substrate 1 were superposed with the electrolyte solution holding / electrode material 2 interposed therebetween, and then the iodine electrolyte solution 3 was injected between the substrates.

  As the iodine electrolyte 3, a solution obtained by dissolving 0.5 M lithium iodide and 0.05 M iodine in a mixed solution of 3-methoxypropionitrile and acetonitrile was used. Furthermore, a sealant was applied around the periphery of the substrate using a dispenser and sealed to prepare a dye-sensitized solar cell.

Example 2
In this example, dye sensitization was performed in the same manner as in Example 1 except that the electrolyte solution holding / electrode material used in Example 1 was coated with about 10 nm of Pt by ion beam assisted deposition. Type solar cells were produced. Ten cells were manufactured in this example.

Example 3
In this example, dye sensitization was performed in the same manner as in Example 1 except that the electrolyte solution holding / electrode material used in Example 1 was coated with about 10 nm of Pt by ion beam assisted deposition. Type solar cells were fabricated. Ten cells were manufactured in this example.

Example 4
In this example, a 16 μm diameter nylon wire was used as the electrolyte solution holding / electrode material 2 and a mesh having a thickness of about 100 μm and a pitch of about 100 μm was used. A dye-sensitized solar cell was produced in the same manner as in Example 1 by using a surface on which one side of the electrolyte solution holding / electrode material 2 was coated with Pt of about 10 nm by ion beam assisted deposition. Ten cells were manufactured in this example.

Comparative Example As a comparative example with respect to the above example, 10 dye-sensitized solar cells were produced in the same manner as in Example 1 except that the electrolytic solution holding / electrode material 2 was not used.

Comparative Results When the electromotive force was measured by irradiating the dye-sensitized solar cells produced in Examples 1 to 4 with a xenon lamp, the cell of the comparative example was 100 mW, the short-circuit current per 1 cm ² was 5 to 15 mA, and the open circuit was open. While the voltage was 0.57 to 0.65 V, the cell of Example 1 had a short circuit current of about 15 mA per cm ² , the open circuit voltage was about 0.6 V, and the cell of Example 2 had a capacity of 1 cm ² . The short-circuit current is about 20 mA, the open-circuit voltage is about 0.65 V, the cell of Example 3 has a short-circuit current of about 25 mA per 1 cm ² , the open-circuit voltage is about 0.65 V, and the cells of Example 4 all have 10 cells per 1 cm ^2. The short circuit current was about 8 mA, and the open circuit voltage was about 0.60V.

  Thus, it was confirmed that the dye-sensitized solar cell of the present invention has excellent reproducibility and stable performance.

  As mentioned above, although the specific embodiment was shown and demonstrated about the dye-sensitized solar cell and its manufacturing method of this invention, this invention is not limited to these. A person skilled in the art can make various changes and improvements to the configurations and functions of the invention according to the above-described embodiments or other embodiments without departing from the gist of the present invention.

Claims (5)

In a dye-sensitized solar cell in which two substrates each having a transparent conductive film and a dye-sensitized semiconductor electrode formed on at least one transparent substrate are overlapped and an electrolyte solution is sealed between the two substrates. ,
A dye-sensitized solar cell comprising a member formed by weaving two or more wire rods in a mesh shape and serving as an electrode between the two substrates. The dye-sensitized solar cell according to claim 1, wherein the wire has conductivity. The dye-sensitized solar cell according to claim 1, wherein the wire is insulative, and a conductive film is formed on one or both surfaces of the wire. The dye sensitization according to any one of claims 1 to 3, wherein the thickness of the wire is larger than the height of the unevenness on the surface of the substrate on which the transparent conductive film and the dye-sensitized semiconductor electrode are formed. Sensitive solar cell. 4. The dye-sensitized solar according to claim 1, wherein a substrate on which the transparent conductive film and the dye-sensitized semiconductor electrode are not formed is insulative among the two substrates. 5. battery.

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