JP5689202B1 - Dye-sensitized solar cell provided with a condensing device - Google Patents

Abstract

An object of the present invention is to provide a dye-sensitized solar cell capable of expressing high power corresponding to high photoelectric conversion efficiency. A dye-sensitized solar cell in which a photoelectrode and a counter electrode are arranged to face each other via an electrolyte layer, wherein (1) the photoelectrode contains a dye sensitizer on a titanium material. (2) The counter electrode is a transparent conductive glass or transparent conductive film coated with an electrochemical reduction catalyst layer, and (3) the light collecting device is on the counter electrode side. A dye-sensitized solar cell, which is disposed in [Selection figure] None

Description

  The present invention relates to a dye-sensitized solar cell.

  There are many types of solar cells, such as single crystal, polycrystalline or amorphous silicon solar cells, compound semiconductor solar cells such as CIGS, CdTe, and GaAs, organic thin film solar cells, and dye-sensitized solar cells.

  At present, silicon solar cells are the mainstream. However, a silicon-type solar cell requires a high-purity silicon material. In addition, silicon type solar cells need to be manufactured under high temperature and high vacuum, and there is room for improvement in terms of high manufacturing cost.

  In these circumstances, in recent years, dye-sensitized solar cells have attracted attention. The dye-sensitized solar cell can be easily manufactured because of its simple structure, and the constituent materials are abundant. In addition, the dye-sensitized solar cell can be manufactured at low cost and has high photoelectric conversion efficiency. Therefore, the dye-sensitized solar cell has attracted attention as a next-generation solar cell.

  The dye-sensitized solar cell has a simple method of sealing and connecting the photoelectrode and the counter electrode after injecting an electrolytic solution having reversible electrochemical redox characteristics between the photoelectrode and the counter electrode. Can be built.

  Conventionally, the photoelectrode is produced by the following method. First, a paste containing titanium oxide fine particles is coated on the surface of transparent conductive glass, which is a glass substrate on which a transparent conductive film such as ITO (Indium Tin Oxide) or FTO (Fluorine Tin Oxide) is formed. Next, the obtained coating material is heat-treated at a temperature of 400 to 500 ° C. to produce an electrode having a porous titanium oxide layer. Next, a photoelectrode in which the dye sensitizer is adsorbed on the surface of the porous titanium oxide by immersing the obtained electrode in an organic solution containing a dye sensitizer such as a ruthenium dye or an indoline dye Is made.

  Next, the counter electrode is produced by forming a platinum layer that exhibits an electrochemical reduction action on a glass substrate or film on which a transparent conductive film has been formed by a technique such as sputtering.

  However, in the conventional dye-sensitized solar cell, the transparent conductive film constituting the photoelectrode and the counter electrode has a relatively large electric resistance. Therefore, there is room for improvement in that the photoelectric conversion efficiency of the obtained dye-sensitized solar cell is significantly reduced when the coating area of titanium oxide (area of the transparent conductive film) is increased. Moreover, the electrical resistance of a transparent conductive film becomes large by the heat processing at the time of producing a porous titanium oxide layer (titanium oxide sintered body). Therefore, there is room for improvement in that the photoelectric conversion efficiency of the dye-sensitized solar cell is reduced.

  Under such circumstances, a technique using metal titanium as a substrate for a photoelectrode is being studied. This technology has a low electrical resistance value compared to a conventional glass substrate on which a transparent conductive film is formed, and has a particularly large titanium oxide coating area compared to a dye-sensitized solar cell using a conventional transparent conductive film. In this case, the photoelectric conversion efficiency is increased, and it has corrosion resistance against iodine and the like contained in the electrolyte solution used in the dye-sensitized solar cell.

However, there is a problem that the photoelectric conversion efficiency of the dye-sensitized solar cell is lower than that of the silicon type solar cell which is the mainstream of the current solar cell, and the electric power obtained is small.

From such a viewpoint, a dye-sensitized solar cell using a condensing device has also been studied.
For example, Patent Document 1 collects incident light by installing a microlens array on the electrode side of a dye-sensitized solar cell made of transparent conductive glass or transparent conductive plastic. In addition, a technique is disclosed in which a mirror is installed on the counter electrode side, the transmitted light is reflected, and the conversion efficiency is improved by irradiating the porous layer again.

Patent Document 2 discloses that a light receiving surface of a transparent plastic material such as a glass substrate coated with an ITO (Indium Tin Oxide) film or PET (polyethylene terephthalate) or PEN (polyethylene naphthalate) is curved with a paraxylylene resin film. A technique of increasing the light collection efficiency by forming the cover is disclosed.

  However, since these techniques use a transparent conductive film having a large electric resistance, the photoelectric conversion efficiency does not improve so much and there is room for improvement.

JP 2009-224105 A JP 2009-193702

  An object of this invention is to provide the dye-sensitized solar cell which can express the high electric power equivalent to high photoelectric conversion efficiency.

  As a result of diligent studies to solve the problems of the prior art, the present inventor has found that a dye-sensitized solar cell having a specific structure can achieve the above object.

  That is, the present invention is the following dye-sensitized solar cell.

Item 1: A dye-sensitized solar cell in which a photoelectrode and a counter electrode are disposed to face each other with an electrolyte layer interposed therebetween,
(1) A photoelectrode is formed by forming a titanium oxide layer containing a dye sensitizer on a titanium material,
(2) The counter electrode is a transparent conductive glass or transparent conductive film coated with an electrochemical reduction catalyst layer,
(3) The dye-sensitized solar cell, wherein the light collecting device is disposed on the counter electrode side.

  Item 2. The dye-sensitized solar cell according to Item 1, wherein the titanium material is a material selected from the group consisting of titanium metal, titanium alloy, surface-treated metal titanium, and surface-treated titanium alloy.

  Item 3. The dye-sensitized solar cell according to Item 1 or 2, wherein the titanium oxide layer has a rectangular shape.

Item 4. The dye-sensitized solar cell according to any one of Items 1 to 3, wherein the electrochemical reduction catalyst layer is a platinum catalyst layer.

  Item 5. The dye-sensitized solar cell according to any one of Items 1 to 4, wherein the transparent conductive glass or transparent conductive film of the counter electrode is an antireflection film processed.

  Item 6 The dye-sensitized dye according to any one of Items 1 to 4, wherein the counter electrode is provided with an antireflection film on the light irradiation surface of the transparent conductive glass or the transparent conductive film. Solar cell.

  Item 7. The dye-sensitized solar cell according to any one of Items 1 to 6, wherein a cooling device is disposed.

Item 8 The dye-sensitized solar cell according to any one of Items 1 to 7, wherein the titanium material of the photoelectrode is produced by the following surface treatment method:
(1) a step of forming titanium nitride on the surface of the metal titanium material or titanium alloy material, and (2) a metal titanium material or titanium alloy material obtained in step (1) and having titanium nitride formed on the surface. A process of forming an anatase-type titanium oxide film by anodizing at a voltage higher than the spark discharge voltage using an electrolytic solution having an etching action on titanium.

Item 9 The dye-sensitized solar cell according to any one of Items 1 to 7, wherein the titanium material of the photoelectrode is produced by the following surface treatment method:
(1) a step of forming titanium nitride on the surface of the titanium metal material or titanium alloy material;
(2) A step of anodizing the metal titanium material or titanium alloy material having titanium nitride formed on the surface obtained in step (1) in an electrolyte solution having no etching action on titanium, And (3) A step of heat-treating the anodized metal titanium material or titanium alloy material obtained in step (2) in an oxidizing atmosphere to form an anatase-type titanium oxide film.

  Item 10. The method of forming the titanium nitride is one treatment method selected from the group consisting of PVD treatment, CVD treatment, thermal spray treatment, heat treatment under an ammonia gas atmosphere, and heat treatment under a nitrogen gas atmosphere Item 10. The dye-sensitized solar cell according to Item 8 or 9, wherein

  Item 11 The dye-sensitized solar cell according to Item 10, wherein the heat treatment under a nitrogen gas atmosphere is performed in the presence of an oxygen trap agent.

  The dye-sensitized solar cell of the present invention can express high power corresponding to high photoelectric conversion efficiency.

It is the schematic (sectional drawing) which shows one Embodiment of the dye-sensitized solar cell of this invention.

  The present invention is described in detail below. In the present specification, a material selected from the group consisting of titanium metal, titanium alloy, surface-treated metal titanium, and surface-treated titanium alloy may be simply referred to as titanium material.

In the dye-sensitized solar cell of the present invention, the photoelectrode and the counter electrode are disposed to face each other with the electrolyte layer interposed therebetween,
(1) A photoelectrode is formed by forming a titanium oxide layer containing a dye sensitizer on a titanium material,
(2) The counter electrode is a transparent conductive glass or transparent conductive film coated with an electrochemical reduction catalyst layer,
(3) A dye-sensitized solar cell is characterized in that the light collecting device is disposed on the counter electrode side.
In the dye-sensitized solar cell of the present invention, since the photoelectrode is composed of a titanium material that does not transmit light, light irradiation is performed from the counter electrode. Furthermore, by using a condensing device between the counter electrode and the light source, high power corresponding to high photoelectric conversion efficiency can be expressed.

  The dye-sensitized solar cell of the present invention is composed of the following members.

(1) In a photoelectrode dye-sensitized solar cell, a photoelectrode and a counter electrode are arranged to face each other with an electrolyte layer interposed therebetween. The photoelectrode contains a dye sensitizer on a material selected from the group consisting of titanium metal, titanium alloy, surface-treated metal titanium, and surface-treated titanium alloy (hereinafter also referred to as “titanium material”). The titanium oxide layer to be formed is formed.

Photoelectrode substrate The titanium electrode itself can be used for the photoelectrode substrate. Titanium material becomes a base material.

  The metal titanium material is titanium itself. When a titanium alloy material is used, the type is not particularly limited. Examples of the titanium alloy include Ti-6Al-4V, Ti-4.5Al-3V-2Fe-2Mo, Ti-0.5Pd, and the like.

  In addition, the photoelectrode substrate is for the titanium material, for example, to prevent leakage of electrons to the electrolyte layer when electrons accompanying photoexcitation of the dye sensitizer migrate from the titanium oxide layer to the photoelectrode substrate. The following surface treatment method A or B is preferably used, and an anatase-type titanium oxide film formed on the surface of the titanium material is preferably used. The film of anatase type titanium oxide becomes a semiconductor layer.

  In the dye-sensitized solar cell of the present invention, since the photoelectrode substrate is a titanium material on which a semiconductor layer containing a dye sensitizer is formed, the photoelectric conversion efficiency is particularly large when the titanium oxide coating area is large. Is expensive.

The thickness of the photoelectrode substrate is usually about 0.01 to 10 mm, preferably about 0.01 to 5 mm, more preferably about 0.05 to 1 mm.

Surface treatment method A
The photoelectrode substrate (titanium material of the photoelectrode) is preferably made of a photoelectrode substrate having a semiconductor layer having anatase-type titanium oxide on the surface, which is produced by the following surface treatment method.
(1) a step of forming titanium nitride on the surface of the metal titanium material or titanium alloy material, and (2) a metal titanium material or titanium alloy material obtained in step (1) and having titanium nitride formed on the surface. A process of forming an anatase-type titanium oxide film by anodizing at a voltage higher than the spark discharge voltage using an electrolytic solution having an etching action on titanium.

Surface treatment method B
The photoelectrode substrate (titanium material of the photoelectrode) is preferably made of a photoelectrode substrate having a semiconductor layer having anatase-type titanium oxide on the surface, which is produced by the following surface treatment method.
(1) a step of forming titanium nitride on the surface of the titanium metal material or titanium alloy material;
(2) A step of anodizing the metal titanium material or titanium alloy material having titanium nitride formed on the surface obtained in step (1) in an electrolyte solution having no etching action on titanium, And (3) A step of heat-treating the anodized metal titanium material or titanium alloy material obtained in step (2) in an oxidizing atmosphere to form an anatase-type titanium oxide film.

Step (1) of surface treatment methods A and B
In the step of forming titanium nitride on the surface of the titanium material (metal titanium or titanium alloy) (step (1)), a titanium nitride layer can usually be formed on the surface of the titanium material to a thickness of about 0.1 to 100 μm. The titanium nitride layer is preferably about 0.5 to 50 μm, more preferably about 1 to 10 μm.

  The means for forming titanium nitride on the surface of the titanium material is not particularly limited. For example, there are a method of physically or chemically attaching titanium nitride to the surface of the titanium material, and a method of forming titanium nitride by reacting titanium and nitrogen on the surface of the titanium material.

  The titanium nitride formation process includes PVD treatment (physical vapor deposition), CVD treatment (chemical vapor deposition), thermal spray treatment (film formation by spraying), heat treatment in an ammonia gas atmosphere, and nitrogen gas atmosphere. It is preferable to carry out by one kind of treatment method selected from the group consisting of the heat treatment in [1].

Examples of the PVD treatment include ion plating and sputtering. Examples of the CVD process include a thermal CVD process, a plasma CVD process, and a laser CVD process. Examples of the thermal spraying process include flame spraying, arc spraying, plasma spraying, and laser spraying.

The heating temperature of the heat treatment under an ammonia gas or nitrogen gas atmosphere is preferably about 500 ° C. or more, more preferably about 750 to 1050 ° C., and further preferably about 750 to 950 ° C. A method of heating the titanium material at about 500 ° C. or higher (preferably about 750 ° C. or higher) in a nitrogen gas atmosphere is preferable.

  The heat treatment in an ammonia gas or nitrogen gas atmosphere is preferably performed in the presence of an oxygen trap agent.

  In particular, it is preferable to form titanium nitride by performing a heat treatment in a nitrogen gas atmosphere in the presence of an oxygen trap agent.

  Examples of the oxygen trap agent used in the heat treatment of the titanium material include a substance or gas having a higher affinity for oxygen than the titanium material. For example, carbon materials, metal powder, hydrogen gas, etc. are preferable materials. These oxygen trap agents may be used individually by 1 type, and may be used in combination of 2 or more type.

  The carbon material is not particularly limited, and examples thereof include graphitic carbon, amorphous carbon, and carbon having an intermediate crystal structure. The carbon material may have any shape such as a flat plate shape, a foil shape, and a powder shape. It is preferable to use a flat carbon material because it is easy to handle and prevents thermal distortion during the heat treatment of the titanium material.

The metal powder is not particularly limited. For example, titanium, titanium alloy, chromium, chromium alloy, molybdenum, molybdenum alloy, vanadium, vanadium alloy, tantalum, tantalum alloy, zirconium, zirconium, zirconium alloy, silicon, silicon alloy, aluminum, Examples thereof include metal powders such as aluminum alloys. For reasons of high oxygen affinity, it is preferable to use metal powder such as titanium, titanium alloy, chromium, chromium alloy, zirconium, zirconium alloy, aluminum, aluminum alloy. The most preferable metal powder is fine particle titanium or titanium alloy metal powder. The said metal powder may be used individually by 1 type, and may be used in combination of 2 or more type.

  The average particle diameter of the metal powder is preferably about 0.1 to 1000 μm, more preferably about 0.1 to 100 μm, and still more preferably about 0.1 to 10 μm.

  Conditions for using the oxygen trap agent in an ammonia gas or nitrogen gas atmosphere can be set in a timely manner according to the type and shape of the oxygen trap agent. For example, when a carbon material or metal powder is used as an oxygen trap agent, the carbon material or metal powder is brought into contact with the titanium material, the surface of the titanium material is covered with the carbon material or metal powder, and the titanium material is covered with ammonia gas or The method of heat-processing in nitrogen gas atmosphere is mentioned. In the case where hydrogen gas is used as the oxygen trap agent, there is a method in which the titanium material is heat-treated in a state where hydrogen gas is introduced in an atmosphere of ammonia gas or nitrogen gas.

  Heat treatment can be performed in an atmosphere of ammonia gas, nitrogen gas, or a mixed gas of ammonia gas and nitrogen gas. Considering simplicity, economy and safety, it is most preferable to use nitrogen gas.

  The reaction pressure for the heat treatment in an ammonia gas or nitrogen gas atmosphere is about 0.01 to 100 MPa, preferably about 0.1 to 10 MPa, and more preferably about 0.1 to 1 MPa. Heat treatment in a nitrogen gas atmosphere is preferable.

The heating time of the heat treatment under an ammonia gas or nitrogen gas atmosphere is preferably about 1 minute to 12 hours, more preferably about 10 minutes to 8 hours, and further preferably about 1 hour to 6 hours. It is preferable to heat-treat the titanium material for this time.

In the method of heat-treating titanium material in an atmosphere of ammonia gas or nitrogen gas, in order to efficiently form titanium nitride on the surface of the titanium material, a rotary vacuum pump, mechanical booster pump, or oil diffusion pump is used as necessary. It is preferable that the inside of the furnace to be heat-treated is depressurized to reduce the oxygen concentration remaining in the furnace to be heat-treated (inside the nitriding furnace). By reducing the vacuum degree in the furnace for heat treatment to about 10 Pa or less, more preferably about 1 Pa or less, and even more preferably about 0.1 Pa or less, titanium nitride can be efficiently formed on the surface of the titanium material.

  By supplying ammonia gas, nitrogen gas or a mixed gas of ammonia gas and nitrogen gas into the furnace in the decompressed furnace, the inside of the furnace is decompressed, and the titanium material is heat-treated, so that the surface of the titanium material is heated. Titanium nitride can be formed efficiently. About the heating temperature, heating time, etc. of the heat treatment using the main furnace, the same conditions as described above may be used. As the gas composition, it is most preferable to use nitrogen gas in consideration of simplicity, economy, and safety.

  In addition, by alternately repeating (several times) a decompression process for reducing the oxygen concentration remaining in the furnace to be heat-treated and a return pressure process for supplying nitrogen gas or the like into the furnace, the surface of the titanium material is made of titanium. Nitride can be formed more efficiently. Furthermore, titanium nitride can be more efficiently formed on the surface of the titanium material by performing pressure reduction treatment in the presence of an oxygen trap agent and heat treatment in a gas atmosphere such as ammonia gas or nitrogen gas.

The type of titanium nitride formed on the surface of the titanium material is not particularly limited. For example, TiN, Ti ₂ N, α-TiN _0.3 , η-Ti ₃ N _2-X , ζ-Ti ₄ N _3-X (where X represents a numerical value of 0 or more and less than 3), a mixture thereof, And amorphous titanium nitride. Among these, TiN, Ti ₂ N, and a mixture thereof, more preferably TiN, and a mixture of TiN and Ti ₂ N, particularly preferably TiN are exemplified.

  In the present invention, as a means for forming the titanium nitride, one of the above methods may be performed alone, or two or more methods may be arbitrarily combined. Among the methods for forming titanium nitride, from the viewpoints of simplicity, mass productivity, production cost, etc., heat treatment of the titanium material in a nitrogen gas atmosphere is preferable.

Step (2) of surface treatment method A
In the surface treatment method A, a titanium material having titanium nitride formed on the surface is subjected to anodization at a spark discharge generation voltage or higher by using an electrolytic solution having an etching action on titanium, and anatase titanium oxide A film is formed (step (2)). A photoelectrode substrate having a semiconductor layer having anatase-type titanium oxide on the surface can be produced. By performing the anodizing treatment, an anatase-type titanium oxide film can be suitably formed. By forming an anatase-type titanium oxide film, high photoelectric conversion efficiency can be suitably exhibited.

  As the surface treatment by applying a voltage higher than the spark discharge generation voltage, an electrolytic solution having an etching action on the titanium material is preferable. The electrolytic solution preferably contains an inorganic acid and / or an organic acid having an etching action on titanium. It is preferable that the electrolytic solution further contains hydrogen peroxide. Anodization is preferably performed by applying a voltage equal to or higher than the discharge generation voltage.

  As the electrolytic solution, it is preferable to use an aqueous solution containing an inorganic acid having an etching action on the titanium material and / or an organic acid having the action. Examples of the inorganic acid having an etching action on the titanium material include sulfuric acid, hydrofluoric acid, hydrochloric acid, nitric acid, and aqua regia. Moreover, as an organic acid which has an etching effect | action with respect to titanium, an oxalic acid, a formic acid, a citric acid, a trichloroacetic acid etc. are mentioned, for example. These acids may be used alone or in combination of two or more of these acids regardless of whether they are organic acids or inorganic acids.

  As an example of the preferable aspect of the electrolyte solution containing 2 or more types of acids, the aqueous solution which contains phosphoric acid as needed in sulfuric acid is mentioned. The blending ratio of the acid in the electrolytic solution varies depending on the type of acid used, anodizing conditions, and the like, but is usually 0.01 to 10M, preferably 0.1 to 10M, and more preferably 1 to 10M in terms of the total amount of the acid. Can be mentioned. For example, in the case of an electrolytic solution containing sulfuric acid and phosphoric acid, an electrolytic solution containing sulfuric acid 1 to 8M and phosphoric acid 0.1 to 2M can be exemplified.

  The electrolyte solution preferably contains hydrogen peroxide in addition to the organic acid and / or inorganic acid. By containing hydrogen peroxide in the electrolytic solution, it becomes possible to prepare a film of anatase-type titanium oxide more efficiently. When hydrogen peroxide is blended in the electrolytic solution, the blending ratio is not particularly limited, but for example, a ratio of 0.01 to 5M, preferably 0.01 to 1M, and more preferably 0.1 to 1M is exemplified.

  As an example of a preferable embodiment of the electrolytic solution used in the anodic oxidation, an aqueous solution containing sulfuric acid 1 to 8M, phosphoric acid 0.1 to 2M and hydrogen peroxide 0.1 to 1M can be given.

An anatase-type titanium oxide film is obtained by immersing a titanium material in the electrolytic solution and applying a constant current so that a voltage equal to or higher than the spark discharge generation voltage can be applied. The voltage higher than the spark discharge generation voltage is typically 100 V or higher, preferably 150 V or higher.

Anodization can be performed, for example, by increasing the voltage at a constant rate up to the spark discharge generation voltage and applying a constant voltage for a predetermined time at a voltage equal to or higher than the spark discharge generation voltage. The speed at which the voltage is increased to the spark discharge generation voltage is usually set to 0.01 to 1 V / second, preferably 0.05 to 0.5 V / second, and more preferably 0.1 to 0.5 V / second. Further, the time for applying a voltage equal to or higher than the spark discharge generation voltage is usually set to 1 minute or longer, preferably 1 to 60 minutes, and more preferably 10 to 30 minutes.

Anodization by spark discharge can be performed by controlling the current instead of controlling the voltage. In anodic oxidation, the current density may be 0.1 A / dm ² or more, but 1 A / dm ² to 10 A / dm ² is preferable from the viewpoint of economy, simplicity, and performance.

According to the said method, the film | membrane containing an anatase type titanium oxide whose film thickness is about 1-100 micrometers can be obtained.

Step (2) of surface treatment method B
In the surface treatment method B, a titanium material having titanium nitride formed on the surface is anodized in an electrolyte solution that does not have an etching action on titanium (step (2)), and then anodized. The obtained titanium material is heat-treated in an oxidizing atmosphere to form an anatase-type titanium oxide film (step (3)). A photoelectrode substrate having a semiconductor layer having anatase-type titanium oxide on the surface and exhibiting high photoelectric conversion efficiency can be produced.

  The electrolytic solution preferably contains at least one acid selected from the group consisting of inorganic acids and organic acids that do not have an etching action on titanium and a salt compound thereof. Amorphous titanium oxide film is formed on the surface of the titanium material by anodizing the titanium material with titanium nitride formed on the surface in an electrolyte that does not etch titanium. can do.

  As an electrolytic solution having no etching action on titanium, an electrolytic solution containing at least one compound selected from the group consisting of inorganic acids, organic acids and salts thereof (hereinafter also referred to as “inorganic acids etc.”) It is preferable that The electrolytic solution containing the inorganic acid or the like is preferably a dilute aqueous solution such as phosphoric acid or phosphate.

  Only the step (2) of performing the anodic oxidation in the surface treatment method B is a condition in which spark discharge does not occur, and usually, crystalline titanium oxide such as anatase-type titanium oxide is not formed. In the next heat treatment under an oxidizing atmosphere, anatase-type titanium oxide can be formed from amorphous titanium oxide. Therefore, for the reason that an amorphous titanium oxide film is effectively formed on the surface of the titanium material, it is preferable to anodize the titanium material having titanium nitride formed on the surface.

  As an electrolytic solution having no etching action on titanium, at least one compound (inorganic acid, etc.) selected from the group consisting of inorganic acids (phosphoric acid, etc.), organic acids and salts thereof (phosphates, etc.) ) Is preferable.

As an inorganic acid that does not have an etching action on titanium, phosphoric acid, carbonic acid, and the like are preferable in consideration of convenience, economy, safety, and the like. As the organic acid having no etching action on titanium, acetic acid, adipic acid, lactic acid and the like are preferable. Further, salts of these acids such as sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium hydrogen carbonate, sodium acetate, potassium adipate, sodium lactate and the like can also be used.

  In addition, it is preferable to use an electrolytic solution containing an electrolyte such as sodium sulfate, potassium sulfate, magnesium sulfate, sodium nitrate, potassium nitrate, magnesium nitrate, or calcium nitrate.

  As an electrolytic solution having no etching action on titanium, at least one compound (inorganic acid, etc.) selected from the group consisting of inorganic acids (phosphoric acid, etc.), organic acids and salts thereof (phosphates, etc.) ) Is preferable. As the inorganic acid, phosphoric acid and phosphate are most preferable.

The electrolytic solution is preferably a dilute aqueous solution such as an inorganic acid. The concentration of the inorganic acid or the like in the electrolytic solution is preferably in the range of about 1% by weight for reasons such as economy. For example, in an electrolytic solution containing phosphoric acid, a concentration range of about 0.01 to 10% by weight is preferable, a concentration range of about 0.1 to 10% by weight is more preferable, and a concentration range of about 1 to 3% by weight is more preferable.

These acids may be used alone or in combination of two or more of these acids regardless of whether they are organic acids or inorganic acids. As an example of the preferable aspect of the electrolyte solution containing 2 or more types of acids, the aqueous solution containing a phosphate and phosphoric acid is mentioned. The mixing ratio of the acid in the electrolytic solution varies depending on the type of acid and acid salt used, anodization conditions, etc., but is generally 0.01 to 10% by weight, preferably 0.1 to 10% by weight, based on the total amount of the acid. Furthermore, the ratio which becomes 1-3 weight% more preferably can be mentioned.

A titanium material in which titanium nitride is formed is immersed in a dilute electrolytic solution containing an inorganic acid or the like that does not have an etching action on titanium on the surface obtained in the step of forming titanium nitride. Next, anodic oxidation is preferably performed by applying a voltage of about 10 to 300V. It is more preferable to perform anodization at a voltage of about 50 to 300V, and it is further preferable to perform anodization at a voltage of about 50 to 200V.

The treatment temperature for anodization is preferably about 0 to 80 ° C. for reasons such as simplicity, economy and safety. It is more preferable to perform anodization at a temperature of about 10 to 50 ° C, and it is further preferable to perform anodization at a temperature of about 20 to 30 ° C.

The treatment time for anodization is preferably about 1 second to 1 hour. It is more preferable to perform anodization in a time of about 10 seconds to 30 minutes, and it is more preferable to perform anodization in a time of about 5 minutes to 20 minutes.

Step (3) of surface treatment method B
Next, the titanium material having a titanium oxide film formed on the surface is subjected to heat treatment in an oxidizing atmosphere to form an anatase-type titanium oxide film (step (3)).

  By simply heat-treating a metal titanium material or the like in an oxidizing atmosphere, rutile titanium oxide is formed, but anatase titanium oxide is not sufficiently formed.

  Titanium material (titanium material after anodization) on which titanium nitride is formed and an oxide film of titanium (amorphous titanium oxide film) is heated in an oxidizing atmosphere (atmospheric oxidation, etc.) By doing so, an anatase-type titanium oxide film excellent in photocatalytic characteristics and photoelectric conversion characteristics can be formed in crystalline titanium oxide. As a result, the titanium material after the heat treatment is excellent in photoelectric conversion characteristics.

  The oxidizing atmosphere for performing the heat treatment may be selected from an air oxidizing atmosphere, an atmosphere having an arbitrary oxygen gas concentration in which oxygen gas and nitrogen gas are mixed, an oxygen gas atmosphere, etc., but is simple and economical. For reasons such as safety, heat treatment in an atmospheric oxidizing atmosphere is preferable.

The temperature of the heat treatment in the oxidizing atmosphere is preferably about 300 ° C. or higher because it efficiently changes from amorphous titanium oxide to anatase titanium oxide. The temperature of the heat treatment in an oxidizing atmosphere is preferably about 800 ° C. or less because it prevents phase transition from anatase-type titanium oxide to rutile-type titanium oxide. This is because rutile type titanium oxide has poor photoelectric conversion characteristics compared to anatase type titanium oxide. The temperature of the heat treatment in the oxidizing atmosphere is more preferably about 300 to 800 ° C, further preferably about 300 to 700 ° C, and particularly preferably about 400 to 700 ° C.

The reaction pressure for performing the heat treatment is about 0.01 to 10 MPa, preferably about 0.01 to 5 MPa, and more preferably about 0.1 to 1 MPa.

  The heating time for performing the heat treatment is preferably about 1 minute to 12 hours, more preferably about 10 minutes to 8 hours, and further preferably about 1 hour to 6 hours.

  The crystalline titanium oxide film is preferably an anatase type titanium oxide film. Anatase-type titanium oxide has high photoelectric conversion characteristics because the open-circuit voltage value is improved compared to the use of rutile-type titanium oxide for the photoelectrode of a dye-sensitized solar cell. By the heat treatment after the anodic oxidation of the present invention, a film having a large amount of anatase-type titanium oxide having high photoelectric conversion characteristics can be formed.

  By the heat treatment, a photoelectric conversion element material in which a large amount of highly active anatase-type titanium oxide is formed on the surface of the titanium material can be prepared. It is also possible to use it for a photoelectric conversion element material that achieves high conversion efficiency.

According to the said method, the film | membrane containing an anatase type titanium oxide whose film thickness is about 1-100 micrometers can be obtained.

  A dilute acidic aqueous solution that does not have etching properties with respect to titanium such as phosphoric acid, phosphoric acid, after titanium nitride is formed on the surface of the titanium material, and after the titanium nitride is formed and before heat treatment in an oxidizing atmosphere By incorporating a step of anodizing in an electrolytic solution such as an aqueous solution of a salt such as, an excellent material for a photoelectric conversion element can be produced.

  Titanium materials are used as materials for photoelectric conversion elements such as photoelectrode substrates of dye-sensitized solar cells, which are attracting attention as next-generation solar cells, because anatase-type titanium oxide (film) is formed on the surface of these materials. be able to.

The titanium oxide layer photoelectrode is a titanium oxide layer (semiconductor layer) containing a dye sensitizer on a titanium material (material selected from the group consisting of metal titanium, titanium alloy, surface-treated metal titanium, and surface-treated titanium alloy). ).

  The anatase-type titanium oxide film prepared by the surface treatment methods A and B may form a semiconductor layer. Furthermore, after applying a paste containing fine particles such as titanium oxide, a titanium oxide layer can be formed by a heat treatment in an oxidizing atmosphere.

The average particle diameter of the titanium oxide fine particles is preferably about 0.1 to 3000 nm, more preferably about 1 to 1000 nm, and still more preferably about 10 to 500 nm. In addition, it is not necessary to use a single type of titanium oxide fine particle powder, and a dye obtained by scattering light in the titanium oxide layer by mixing small and large particle sizes. The photoelectric conversion efficiency of the sensitized solar cell can be improved.

  The paste agent can be prepared, for example, by dispersing titanium oxide fine particles in a solvent. As the solvent, polyethylene glycol is preferable. The content of the titanium oxide fine particles in the paste is not particularly limited, and may be appropriately adjusted so that the sintered body is suitably formed.

  The method for applying the paste on the titanium material is not particularly limited, and examples thereof include screen printing, ink jet, roll coating, doctor blade, spray coating and the like.

  The thickness of the coating film after applying the paste agent is not particularly limited, and may be set as appropriate so that a titanium oxide sintered body having a target thickness is formed.

  Moreover, it is preferable that the application | coating shape of this titanium oxide layer is a rectangle. By making the titanium oxide layer rectangular instead of square, electrons accompanying photoexcitation of the dye sensitizer are not lost in the titanium oxide layer, and the photoelectric conversion efficiency is improved.

  When the photoelectrode substrate is a surface-treated metal titanium material or titanium alloy material, a laminate of the titanium oxide sintered body and the titanium oxide film is obtained as the titanium oxide layer.

  The temperature of the heat treatment is preferably about 100 to 600 ° C, more preferably about 400 to 500 ° C. In particular, the titanium oxide fine particles can be suitably sintered by heat treatment at a temperature of about 400 to 500 ° C. What is necessary is just to set the time of heat processing suitably according to heat processing temperature. The heat treatment is performed in an oxidizing atmosphere (for example, in an atmosphere in which oxygen exists such as air).

The dye sensitizer photoelectrode is obtained by forming a titanium oxide layer containing a dye sensitizer on a titanium material.

  The dye sensitizer can be adsorbed on the titanium oxide layer by immersing the photoelectrode on which the titanium oxide layer (semiconductor layer) is formed by the above-described method in a solution containing the dye sensitizer.

  The dye sensitizer is not particularly limited as long as it is a dye having light absorption in the near infrared light region and the visible light region. Of the dye sensitizers, ruthenium metal complexes such as red dye (N719) and black dye (N749); metal complexes other than ruthenium such as copper phthalocyanine; These dye sensitizers can be used alone or in combination of two or more. Of the dye sensitizers, a ruthenium complex is preferable, and a mixture of a red dye (N719) and a black dye (N749) having light absorption in the near infrared region is more preferable.

  As a method of adsorbing the dye sensitizer to the titanium oxide layer, there is a method of immersing a semiconductor layer such as a titanium oxide layer in a solution containing the dye sensitizer. The dye sensitizer can be attached (chemical adsorption, physical adsorption, deposition, etc.) to the semiconductor layer.

  What is necessary is just to set the quantity which makes a dye sensitizer adhere suitably according to the area of a semiconductor layer, etc. within the range which does not inhibit the effect of this invention.

(2) In the counter electrode dye-sensitized solar cell, the counter electrode is obtained by coating an electrochemical reduction catalyst layer on a transparent conductive glass or a transparent conductive film. Transparent conductive glass or transparent conductive film is made of transparent conductive films such as ITO (Indium Tin Oxide) and FTO (Fluorine Tin Oxide), which are transparent glass and transparent plastic materials such as PET (polyethylene terephthalate) and PEN (polyethylene naphthalate). ) Etc. On the surface of the transparent conductive glass or transparent conductive film on the electrolyte side, an electrochemical reduction catalyst layer is coated by PVD treatment such as electron beam evaporation or sputtering.

As the electrochemical reduction catalyst layer, platinum catalyst layer, carbon layer, poly (3,4-ethylenedioxythiophene) (PEDOT) layer, gold layer, silver layer, copper layer, aluminum layer, rhodium layer, indium layer, etc. Can be used. The electrochemical reduction catalyst layer is preferably a platinum catalyst layer because, for example, electrons are easily injected into the electrolyte that has lost electrons in the electrolytic layer because the hydrogen overvoltage is low.

Since the product of the present invention is composed of a titanium material that does not transmit light as a photoelectrode, the light irradiation means is implemented from the counter electrode. The thinner the platinum coating on the counter electrode is, the higher the light transmittance is. Therefore, it is preferable to coat several nm or less. If the coating film thickness is too thin, it becomes difficult for electrons to be injected into the electrolyte that has lost the electrons in the electrolyte, and the photoelectric conversion efficiency of the resulting dye-sensitized solar cell is reduced. More preferably, about 0.5 to 1 nm.

In addition, in order to increase the amount of light entering the dye-sensitized solar cell, MgF ₂ or SiO ₂ or the like is applied to the surface of the transparent conductive film glass or transparent conductive film to be irradiated with light, such as vacuum deposition or sputtering. The photosensitivity of the dye-sensitized solar cell obtained by using an antireflection film formed by spin coating or dip coating or by attaching an antireflection film to the light-irradiated surface Conversion efficiency is improved.

(3) Electrolyte layer The electrolyte layer may be any layer that can supply electrons to the dye sensitizer that has been photoexcited and injects electrons into the semiconductor layer, and can reduce the dye sensitizer. The electrolyte layer may be a layer in which electrons are supplied from the counter platinum catalyst layer to the electrolyte that has lost electrons.

Examples of the liquid electrolyte layer include a non-aqueous electrolyte solution containing a redox species. Redox species include combinations of iodide salts such as lithium iodide, sodium iodide, potassium iodide, calcium iodide and iodine, and bromide salts such as lithium bromide, sodium bromide, potassium bromide, calcium bromide. A combination of and bromine is preferred. Each may be used alone or in combination of two or more. Further, DMPII (1,2-dimethyl-3-propylimidazolium iodide), TBP (tert-butylpyridine) or the like may be added.

  Examples of the solvent include acetonitrile, 3-methoxypropionitrile, ethylene carbonate, propionate and the like. These solvents may be used alone or in combination of two. In the dye-sensitized solar cell of the present invention, the dye adsorbed on the titanium oxide layer on the photoelectrode is irradiated with light via the light collecting device, the counter electrode material, and the electrolyte layer, and the dye is photoexcited. The electrolyte layer needs to have high light transmittance. The thickness of the electrolyte layer, that is, the distance between the photoelectrode and the counter electrode is preferably 25 to 100 μm, and more preferably 25 to 50 μm.

In the separator (spacer) and the sealing material dye-sensitized solar cell, it is preferable to install a separator (spacer) in order to prevent contact between the photoelectrode and the counter electrode.

The thickness of the separator (spacer) placed between the photoelectrode and the counter electrode determines the thickness of the electrolyte layer. The thinner the electrolyte layer, the more the dye-sensitized solar cell of the present invention is irradiated with light to the dye adsorbed on the titanium oxide layer on the photoelectrode via the light collecting device, the counter electrode material, and the electrolyte layer. In order for the dye to be photoexcited, the electrolyte layer needs to have high light transmittance, and the electrolyte layer is preferably thin. If the separator (spacer) is too thin, contact between the photoelectrode and the counter electrode occurs. The separator (spacer) is preferably 25 to 100 μm, more preferably 25
~ 50 μm. As the separator, a known separator usually used in the battery field can be used. As the separator, an ionomer resin film, a polyimide resin film, an acrylic UV curable resin, a glass material, a silane-modified polymer, a polyimide tape, or the like can be used.

  The area of the separator is not particularly limited, and may be set as appropriate according to the scale of the target solar cell.

As the sealing material, acrylic UV curable resins, ionomer resin films, epoxy resins, polyester resins, acrylic resins, hot melt resins, silicone elastomers, butyl rubber elastomers, glass materials, and the like can be used. As an acrylic UV curable resin, TB3017B manufactured by ThreeBond can be used. The gap between both the photoelectrode and the counter electrode can be sealed.

(4) Condensing device In this dye-sensitized solar cell, the condensing device is disposed on the counter electrode side.

  The light irradiation means is arrange | positioned from the counter electrode side via the condensing apparatus. In the dye-sensitized solar cell, since the photoelectrode is composed of a titanium material having no light transmittance, light irradiation is performed from the counter electrode. By installing a light condensing device between the counter electrode and the light source, light that is wasted is condensed, and high power corresponding to high photoelectric conversion efficiency is achieved. Sheets using transparent conductive films such as ITO (Indium Tin Oxide) and FTO (Fluorine Tin Oxide) used in conventional dye-sensitized solar cells have high sheet resistance, and the light is converged by a condensing device. However, especially in a large-area dye-sensitized solar cell, an improvement in photoelectric conversion efficiency is not recognized. On the other hand, the metal titanium, titanium alloy or metal titanium, titanium alloy surface-treated material used in the photoelectrode of the present invention has a sheet resistance of transparent conductive such as ITO (Indium Tin Oxide), FTO (Fluorine Tin Oxide), etc. There are advantages such as extremely low compared to the membrane. As a result, in the dye-sensitized solar cell of the present invention, even in a large-area dye-sensitized solar cell, it is equivalent to the photoelectric conversion efficiency of the obtained dye-sensitized solar cell by converging light using a condensing device Power to be obtained.

The condensing device is not particularly limited, but condensing lenses such as linear Fresnel lenses made of transparent plastics such as glass, PMMA (Polymethyl methacrylate), PET (Polyethylene terephthalate), PEN (Polyethylene naphthalate), etc. It is preferable to use it.

Organic components such as dye sensitizers used in dye-sensitized solar cells may be deteriorated by ultraviolet rays having a short wavelength contained in sunlight. Therefore, by using a condensing device such as glass, PMMA (Polymethyl methacrylate), PET (Polyethylene terephthalate), PEN (Polyethylene naphthalate) or other transparent plastic linear Fresnel lenses, ultraviolet rays with a short wavelength contained in sunlight are dyed. It is possible to prevent entry into the sensitized solar cell. Deterioration of organic components such as a dye used in the dye-sensitized solar cell can be prevented, and the durability of the dye-sensitized solar cell can be improved.

In addition, since the dye-sensitized solar cell itself generated by the light converging in the condensing device has heat, the durability of the dye-sensitized solar cell may be impaired. Is preferred. Although it does not restrict | limit especially as a cooling device, In order to interrupt | block the thermal energy of sunlight between a condensing device and a counter electrode, what provided the near-infrared cut off filter, and is used for a photoelectrode Metal titanium, titanium alloy or metal titanium, an apparatus for water-cooling the titanium alloy, a material having high thermal conductivity such as a copper plate, and the like are preferable. By attaching these cooling devices, it is possible to prevent heat generation due to the light converged by the light collecting device. In order to further increase the cooling efficiency, two or more kinds of materials having good thermal conductivity (aluminum, copper plate, etc.) may be laminated on the photoelectrode surface of the dye-sensitized solar cell of the present invention.

(5) Method for Producing Dye-Sensitized Solar Cell The dye-sensitized solar cell of the present invention can be produced according to a known method. For example, the photoelectrode and the counter electrode are arranged to face each other via a spacer, and an electrolyte layer is sealed between the photoelectrode and the counter electrode. The method of encapsulating the electrolyte layer is not limited. For example, after the counter electrode is stacked on the semiconductor layer side of the photoelectrode, an injection port is provided, and a material constituting the electrolyte layer is injected from the injection port. It is done. The injection port may be closed with a predetermined member or resin after the injection of the material is completed. In addition, when the material is injected, if the electrolyte layer is a gel, it may be liquefied by heating. When the electrolyte layer is solid, for example, a solution in which the solid electrolyte is dissolved using a solvent capable of dissolving the solid electrolyte is prepared and injected into the injection port, and then the solvent is removed.

  The dye-sensitized solar cell of the present invention is a next-generation solar cell with high photoelectric conversion efficiency. The dye-sensitized solar cell of the present invention can have the form of a module provided with a plurality of batteries.

  FIG. 1 is a schematic view (cross-sectional view) showing an embodiment of the dye-sensitized solar cell of the present invention. The dye-sensitized solar cell in FIG. 1 is a dye-sensitized solar cell in which a photoelectrode and a counter electrode are arranged to face each other with an electrolyte layer interposed therebetween.

  The photoelectrode is a semiconductor layer 2 containing a dye sensitizer on the titanium material 1, and the counter electrode is a transparent conductive glass 3. On the counter electrode, an electrochemical catalyst layer 4 is deposited. An electrolyte 5 is interposed between the photoelectrode and the counter electrode, and a spacer 6 is installed between the photoelectrode and the counter electrode, and then sealed with a sealing material 7.

  A condensing device 8 is installed above the counter electrode, and an antireflection film 9 is provided on the light irradiation surface of the counter electrode.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not limited to these Examples.

Example 1
(1) Preparation of anodized titanium material Metal titanium plate (titanium material, photoelectrode substrate) is degreased with trichlorethylene and then used in a nitriding furnace (NVF-600-PC, manufactured by Central Japan Reactor Industry) Thus, titanium nitride was formed on the surface of the degreased metal titanium plate.

First, a metal titanium plate was sandwiched between flat carbon materials installed in a nitriding furnace. Next, in order to remove oxygen, the nitriding furnace was depressurized to 1 Pa or less, and then nitrogen gas with a purity of 99.99% or more was introduced into the nitriding furnace to restore the pressure to 0.1 MPa (atmospheric pressure). Next, the temperature of the nitriding furnace was raised to 950 ° C. over 2 hours. Next, in this 950 ° C. nitriding furnace, heat treatment is performed for 1 hour,
Titanium nitride was formed on the surface of the metal titanium plate.
The titanium metal plate with titanium nitride formed on the surface was anodized with 1.5 M sulfuric acid, 0.05 M phosphoric acid, 0.3 M hydrogen peroxide at a current density of 4 A / dm ^{2 for} 30 minutes. A film of anatase-type titanium oxide was formed.

(2) Production of photoelectrode A dye-sensitized solar cell was produced using the surface-treated 12 mm x 50 mm titanium metal plate as the photoelectrode.

First, the surface-treated titanium metal plate is washed with a solvent, then subjected to an oxygen flow (0.05 MPa, 5 minutes) in a UV ozone cleaner UV253S (manufactured by Filgen Co., Ltd.), and then subjected to ultraviolet irradiation for 30 minutes. Nitrogen flow (0.2 MPa, 7.5 min) was performed.
Titanium oxide material (PST-18NR, manufactured by JGC Catalysts & Chemicals) was coated three times by the squeegee method on the surface treatment material after this treatment so that the coating area was 2cm ² (5mm × 40mm) (semiconductor Layer) and then fired at 450 ° C. for 1 hour. Furthermore, after performing oxygen flow (0.05 MPa, 5 minutes) in UV ozone cleaner UV253S (manufactured by Philgen), ultraviolet irradiation was performed for 30 minutes, and nitrogen flow (0.2 MPa, 7.5 min) was further performed.

Next, ruthenium dye N719 0.45 mM (Solaronix, dye sensitizer), ruthenium dye N749 0.15 mM (Solaronix, dye sensitizer), tert-butanol (t-BuOH) and acetonitrile ( A dye solution was prepared by diluting in a mixed solution containing (CH ₃ CN). The mixed solution has a mixing ratio of t-BuOH: CH ₃ CN = 1: 1. Place the titanium metal plate after firing into the dye solution.
It was immersed for 14 hours at 0 ° C. to obtain a photoelectrode material.

Similarly, work was performed on a metal titanium material not subjected to surface treatment and an FTO (Fluorine Tin Oxide) vapor-deposited glass plate (manufactured by Asahi Glass Co., Ltd.) used in conventional dye-sensitized solar cells, and a photoelectrode was prepared.

  The current collector was provided by etching the surface-treated metal titanium by immersing it in a 5% hydrofluoric acid solution for 5 minutes. Metal titanium was not subjected to the process of providing a current collector. An FTO (Fluorine Tin Oxide) vapor-deposited glass plate was coated with Dotite D-550 (silver paste manufactured by Fujikura Kasei Co., Ltd.) to provide a current collector.

(3) As a counter electrode for the dye-sensitized solar cell, a 12 × 50 mm material obtained by electron beam evaporation of platinum on an FTO (Fluorine Tin Oxide) vapor-deposited glass plate (manufactured by Asahi Glass Co., Ltd.) was used. A current collector was provided by coating Doutite D-550 (silver paste manufactured by Fujikura Kasei Co., Ltd.). The deposition thickness of platinum is 1nm,
A 30 μm ionomer resin spacer (High Milan, made by Mitsui DuPont Polychemical Co., Ltd.) was installed in the gap between the photoelectrode and the counter electrode. An antireflection film (manufactured by Hori Co., Ltd.) was attached to the light irradiation surface of this counter electrode.

Next, 0.01M I ₂ (iodine), 0.02M LiI (lithium iodide), 0.24M DMPII (1,2-dimethyl-3-propylimidazolium iodide), 1.0M TBP (tert-butylpyridine) are dissolved in acetonitrile. An electrolyte solution was prepared. The prepared electrolytic solution was put in the gap between the photoelectrode and the counter electrode (electrolyte layer).

Next, using an acrylic UV curable resin TB3017B (manufactured by Three Bond Co., Ltd., a sealing material), the gap between both electrodes was sealed to prepare a dye-sensitized solar cell.

As a condensing device (condensing lens) lens, incident light was converged using a linear Fresnel lens (manufactured by Nippon Special Optical Resin Co., Ltd.) made of PMMA (Polymethyl methacrylate). The condensing rate when the incident light was converged using the condensing lens was obtained from the current value when the light was converged using a silicon standard cell (manufactured by Spectrometer Co., Ltd.).

(4) Evaluation results In a dye-sensitized solar cell using surface-treated metal titanium, metal titanium, and FTO (Fluorine Tin Oxide) vapor-deposited glass plates, the apparent photoelectric conversion efficiency corresponding to the generated electric power when condensed is examined. The results are shown in Table 1.

From this result, it was found that the photoelectric conversion efficiency is not improved so much even in the FTO glass used for the photoelectrode substrate of the conventional dye-sensitized solar cell.
On the other hand, by condensing light in a dye-sensitized solar cell using the titanium metal of the present invention or surface-treated metal titanium as a photoelectrode substrate, photoelectric conversion efficiency improves and high power is generated if light is converged. I found out that

Example 2
(1) Preparation of anodized titanium material Metal titanium plate (titanium material, photoelectrode substrate) is degreased with trichlorethylene and then used in a nitriding furnace (NVF-600-PC, manufactured by Central Japan Reactor Industry) Thus, titanium nitride was formed on the surface of the degreased metal titanium plate.

First, a metal titanium plate was sandwiched between flat carbon materials installed in a nitriding furnace. Next, in order to remove oxygen, the nitriding furnace was depressurized to 1 Pa or less, and then nitrogen gas with a purity of 99.99% or more was introduced into the nitriding furnace to restore the pressure to 0.1 MPa (atmospheric pressure). Next, the temperature of the nitriding furnace was raised to 950 ° C. over 2 hours. Next, in this 950 ° C. nitriding furnace, heat treatment is performed for 1 hour,
Titanium nitride was formed on the surface of the metal titanium plate.

The titanium metal plate with titanium nitride formed on the surface was anodized with 1.5 M sulfuric acid, 0.05 M phosphoric acid, 0.3 M hydrogen peroxide at a current density of 4 A / dm ^{2 for} 30 minutes. A film of anatase-type titanium oxide was formed.

(2) Production of photoelectrode A dye-sensitized solar cell was produced using the surface-treated 17 mm x 50 mm titanium metal plate as the photoelectrode.

First, the surface-treated titanium metal plate is washed with a solvent, then subjected to an oxygen flow (0.05 MPa, 5 minutes) in a UV ozone cleaner UV253S (manufactured by Filgen Co., Ltd.), and then subjected to ultraviolet irradiation for 30 minutes. Nitrogen flow (0.2 MPa, 7.5 min) was performed.

Titanium oxide material (PST-18NR, manufactured by JGC Catalysts & Chemicals) was coated three times by the squeegee method (semiconductor) on the surface treatment material after this treatment so that the coating area was 4cm ² (10mm × 40mm). Layer) and then fired at 450 ° C. for 1 hour. Furthermore, after performing oxygen flow (0.05 MPa, 5 minutes) in UV ozone cleaner UV253S (manufactured by Philgen), ultraviolet irradiation was performed for 30 minutes, and nitrogen flow (0.2 MPa, 7.5 min) was further performed.

Next, ruthenium dye N719 0.45 mM (Solaronix, dye sensitizer), ruthenium dye N749 0.15 mM (Solaronix, dye sensitizer), tert-butanol (t-BuOH) and acetonitrile A dye solution was prepared by diluting in a mixed solution containing (CH ₃ CN). The mixed solution has a mixing ratio of t-BuOH: CH ₃ CN = 1: 1. The fired titanium metal plate was immersed in the dye solution at 40 ° C. for 14 hours to obtain a photoelectrode material. Similarly, work was performed on a metal titanium material not subjected to surface treatment and an FTO (Fluorine Tin Oxide) vapor-deposited glass plate (manufactured by Asahi Glass Co., Ltd.) used in conventional dye-sensitized solar cells, and a photoelectrode was prepared.

The surface-treated metal titanium was subjected to an etching treatment by immersing it in a 5% hydrofluoric acid solution for 5 minutes to provide a current collector. Metal titanium was not subjected to the process of providing a current collector.

  An FTO (Fluorine Tin Oxide) vapor-deposited glass plate was coated with Dotite D-550 (silver paste manufactured by Fujikura Kasei Co., Ltd.) to provide a current collector.

(3) As a counter electrode for the dye-sensitized solar cell, a 17 mm × 50 mm material obtained by electron beam vapor deposition of platinum on an FTO (Fluorine Tin Oxide) vapor deposition glass plate (Asahi Glass Co., Ltd.) was used. A current collector was provided by coating Doutite D-550 (silver paste manufactured by Fujikura Kasei Co., Ltd.). The platinum deposition thickness was 1 nm, and a 30 μm ionomer resin spacer (High Milan, made by Mitsui DuPont Polychemical Co., Ltd.) was installed in the gap between the photoelectrode and the counter electrode. An antireflection film (manufactured by Hori Co., Ltd.) was attached to the light irradiation surface of this counter electrode.

Next, 0.01M I ₂ (iodine), 0.02M LiI (lithium iodide), 0.24M DMPII (1,2-dimethyl-3-propylimidazolium iodide), 1.0M TBP (tert-butylpyridine) are dissolved in acetonitrile. An electrolyte solution was prepared. The prepared electrolytic solution was put in the gap between the photoelectrode and the counter electrode (electrolyte layer).

Next, using an acrylic UV curable resin TB3017B (manufactured by Three Bond Co., Ltd., a sealing material), the gap between both electrodes was sealed to prepare a dye-sensitized solar cell.

As the condenser lens, a linear Fresnel lens (manufactured by Nippon Special Optical Resin Co., Ltd.) made of PMMA (Polymethyl methacrylate) was used to converge the incident light. The condensing rate when the incident light was converged using the condensing lens was obtained from the current value when the light was converged using a silicon standard cell (manufactured by Spectrometer Co., Ltd.).

(4) Evaluation results In a dye-sensitized solar cell using surface-treated metal titanium, metal titanium, and FTO (Fluorine Tin Oxide) vapor-deposited glass plates, the apparent photoelectric conversion efficiency corresponding to the generated electric power when condensed is examined. The results are shown in Table 2.

From this result, in the FTO glass used for the photoelectrode substrate of the conventional dye-sensitized solar cell, the photoelectric conversion efficiency is not so much improved even if it is condensed. On the other hand, it was found that by using the metal titanium of the present invention or the surface-treated metal titanium as a photoelectrode substrate and condensing, if the light is converged, the photoelectric conversion efficiency is improved and high power is generated.

Example 3
(1) Preparation of anodized titanium material Metal titanium plate (titanium material, photoelectrode substrate) is degreased with trichlorethylene and then used in a nitriding furnace (NVF-600-PC, manufactured by Central Japan Reactor Industry) Thus, titanium nitride was formed on the surface of the degreased metal titanium plate.

First, a metal titanium plate was sandwiched between flat carbon materials installed in a nitriding furnace. Next, in order to remove oxygen, the nitriding furnace was depressurized to 1 Pa or less, and then nitrogen gas with a purity of 99.99% or more was introduced into the nitriding furnace to restore the pressure to 0.1 MPa (atmospheric pressure). Next, the temperature of the nitriding furnace was raised to 950 ° C. over 2 hours. Next, in this 950 ° C. nitriding furnace, heat treatment is performed for 1 hour,
Titanium nitride was formed on the surface of the metal titanium plate.

The titanium metal plate with titanium nitride formed on the surface was anodized with 1.5 M sulfuric acid, 0.05 M phosphoric acid, 0.3 M hydrogen peroxide at a current density of 4 A / dm ^{2 for} 30 minutes. A film of anatase-type titanium oxide was formed.

(2) Production of photoelectrode A dye-sensitized solar cell was produced using the surface-treated titanium metal plate as a photoelectrode.

First, the surface-treated titanium metal plate is washed with a solvent, then subjected to an oxygen flow (0.05 MPa, 5 minutes) in a UV ozone cleaner UV253S (manufactured by Filgen Co., Ltd.), and then subjected to ultraviolet irradiation for 30 minutes. Nitrogen flow (0.2 MPa, 7.5 min) was performed. Titanium oxide material (PST-18NR, manufactured by JGC Catalysts & Chemicals) is applied to the surface treatment materials of 9 × 50mm, 10 × 50mm, 12mm × 50mm, and 17mm × 50mm, respectively, and the coating area is 0.8cm ² (2mm) × 40 mm), 1.2 cm ² (3 mm × 40 mm), 2.0 cm ² (5 mm × 40 mm), and 4.0 cm ² (10 mm × 40 mm) were coated three times by the squeegee method (semiconductor layer). Further, UV ozone treatment was performed for 30 minutes, followed by baking at 450 ° C. for 1 hour. Furthermore, after performing oxygen flow (0.05 MPa, 5 minutes) in UV ozone cleaner UV253S (manufactured by Philgen), ultraviolet irradiation was performed for 30 minutes, and nitrogen flow (0.2 MPa, 7.5 min) was further performed.

Next, ruthenium dye N719 0.45 mM (Solaronix, dye sensitizer), ruthenium dye N749 0.15 mM (Solaronix, dye sensitizer), tert-butanol (t-BuOH) and acetonitrile ( A dye solution was prepared by diluting in a mixed solution containing (CH ₃ CN). The mixed solution has a mixing ratio of t-BuOH: CH ₃ CN = 1: 1. Place the titanium metal plate after firing into the dye solution.
It was immersed for 14 hours at 0 ° C. to obtain a photoelectrode material. Surface treated titanium metal is 5% hydrofluoric acid
A current collector was provided by immersing in the solution for 5 minutes.

(3) As a counter electrode for the dye-sensitized solar cell, a material having the same area as that of a photoelectrode substrate obtained by electron beam vapor deposition of platinum on an FTO (Fluorine Tin Oxide) vapor deposition glass plate (manufactured by Asahi Glass Co., Ltd.) was used. Doutite D-550 (Fujikura Kasei (
A current collector was provided by coating silver paste). The platinum deposition thickness was 1 nm, and a 30 μm ionomer resin spacer (High Milan, made by Mitsui DuPont Polychemical Co., Ltd.) was installed in the gap between the photoelectrode and the counter electrode. An antireflection film (manufactured by Hori Co., Ltd.) was attached to the light irradiation surface of this counter electrode.

Next, 0.01M I ₂ (iodine), 0.02M LiI (lithium iodide), 0.24M DMPII (1,2-dimethyl-3-propylimidazolium iodide), 1.0M TBP (tert-butylpyridine) are dissolved in acetonitrile. An electrolyte solution was prepared. The prepared electrolytic solution was put in the gap between the photoelectrode and the counter electrode (electrolyte layer).

Next, using an acrylic UV curable resin TB3017B (manufactured by Three Bond Co., Ltd., a sealing material), the gap between both electrodes was sealed to prepare a dye-sensitized solar cell.

As the condenser lens, a linear Fresnel lens (manufactured by Nippon Special Optical Resin Co., Ltd.) made of PMMA (Polymethyl methacrylate) was used to converge the incident light. The condensing rate when the incident light was converged using the condensing lens was obtained from the current value when the light was converged using a silicon standard cell (manufactured by Spectrometer Co., Ltd.).

(4) Evaluation results Table 3 shows the photoelectric conversion efficiency of the dye-sensitized solar cell in which the titanium oxide coating width and the aspect ratio which is the balance between the vertical and horizontal directions were changed for the surface-treated metal titanium. Table 4 shows the photoelectric conversion efficiency corresponding to the generated power when the light is condensed using a condensing device in a dye-sensitized solar cell in which the area of the titanium oxide coating is 0.8 cm ² (2 mm × 40 mm).

From these results, when the oxide coating layer was formed in a rectangular shape with a narrow cell width and a high aspect ratio which is a balance between vertical and horizontal, the resulting dye-sensitized solar cell was improved. 2mm
The photoelectric conversion efficiency of the dye-sensitized solar cell using the photoelectrode substrate coated with titanium oxide with a width of 5 mm was further improved, and high power was obtained.

  It was found that the amount of generated power is equivalent to that of silicon solar cells that are the mainstream of current solar cells.

Example 4
(1) Preparation of anodized titanium material Metal titanium plate (titanium material, photoelectrode substrate) is degreased with trichlorethylene and then used in a nitriding furnace (NVF-600-PC, manufactured by Central Japan Reactor Industry) Thus, titanium nitride was formed on the surface of the degreased metal titanium plate.

First, a metal titanium plate was sandwiched between flat carbon materials installed in a nitriding furnace. Next, in order to remove oxygen, the nitriding furnace was depressurized to 1 Pa or less, and then nitrogen gas with a purity of 99.99% or more was introduced into the nitriding furnace to restore the pressure to 0.1 MPa (atmospheric pressure). Next, the temperature of the nitriding furnace was raised to 950 ° C. over 2 hours. Next, in this 950 ° C. nitriding furnace, heat treatment is performed for 1 hour,
Titanium nitride was formed on the surface of the metal titanium plate.

The titanium metal plate with titanium nitride formed on the surface was anodized with 1.5 M sulfuric acid, 0.05 M phosphoric acid, 0.3 M hydrogen peroxide at a current density of 4 A / dm ^{2 for} 30 minutes. A film of anatase-type titanium oxide was formed.

(2) Production of photoelectrode A dye-sensitized solar cell was produced using the surface-treated 10 mm x 50 mm titanium metal plate as the photoelectrode.

First, the surface-treated titanium metal plate is washed with a solvent, then subjected to an oxygen flow (0.05 MPa, 5 minutes) in a UV ozone cleaner UV253S (manufactured by Filgen Co., Ltd.), and then subjected to ultraviolet irradiation for 30 minutes. Nitrogen flow (0.2 MPa, 7.5 min) was performed. Titanium oxide material (PST-18NR, manufactured by JGC Catalysts & Chemicals) was coated three times by the squeegee method on the surface treatment material after this treatment so that the coating area was 1.2cm ² (3mm × 40mm) ( After the semiconductor layer), it was baked at 450 ° C. for 1 hour. Furthermore, after performing oxygen flow (0.05 MPa, 5 minutes) in UV ozone cleaner UV253S (manufactured by Philgen), ultraviolet irradiation was performed for 30 minutes, and nitrogen flow (0.2 MPa, 7.5 min) was further performed.

Next, ruthenium dye N719 0.45 mM (Solaronix, dye sensitizer), ruthenium dye N749 0.15 mM (Solaronix, dye sensitizer), tert-butanol (t-BuOH) and acetonitrile ( A dye solution was prepared by diluting in a mixed solution containing (CH ₃ CN). The mixed solution has a mixing ratio of t-BuOH: CH ₃ CN = 1: 1. Place the titanium metal plate after firing into the dye solution.
It was immersed for 14 hours at 0 ° C. to obtain a photoelectrode material.

The surface-treated metal titanium and metal titanium were subjected to an etching treatment by immersing them in a 5% hydrofluoric acid solution for 5 minutes to provide a current collector.

(3) As a counter electrode for the dye-sensitized solar cell, a 10 mm × 50 mm material obtained by electron beam evaporation of platinum on an FTO (Fluorine Tin Oxide) vapor-deposited glass plate (Asahi Glass Co., Ltd.) was used. A current collector was provided by coating Doutite D-550 (silver paste manufactured by Fujikura Kasei Co., Ltd.). The platinum deposition thickness was 1 nm, and a 30 μm ionomer resin spacer (High Milan, made by Mitsui DuPont Polychemical Co., Ltd.) was installed in the gap between the photoelectrode and the counter electrode. On the light-irradiated surface of this counter electrode, an antireflection film (manufactured by Hori Co., Ltd.) and an uncoated film were prepared.

Next, 0.01M I ₂ (iodine), 0.02M LiI (lithium iodide), 0.24M DMPII (1,2-dimethyl-3-propylimidazolium iodide), 1.0M TBP (tert-butylpyridine) are dissolved in acetonitrile. An electrolyte solution was prepared. The prepared electrolytic solution was put in the gap between the photoelectrode and the counter electrode (electrolyte layer).

Next, using an acrylic UV curable resin TB3017B (manufactured by Three Bond Co., Ltd., a sealing material), the gap between both electrodes was sealed to prepare a dye-sensitized solar cell.

As the condenser lens, a linear Fresnel lens (manufactured by Nippon Special Optical Resin Co., Ltd.) made of PMMA (Polymethyl methacrylate) was used to converge the incident light. The condensing rate when the incident light was converged using the condensing lens was obtained from the current value when the light was converged using a silicon standard cell (manufactured by Spectrometer Co., Ltd.).

(4) Evaluation results Table 5 shows the difference in apparent photoelectric conversion efficiency corresponding to the generated power of the dye-sensitized solar cell with and without the antireflection film.

  From this result, it was found that by using the antireflection film, the photoelectric conversion efficiency of the obtained dye-sensitized solar cell was further improved, and high power was generated.

1 Titanium material 2 Semiconductor layer containing dye sensitizer 3 Transparent conductive glass 4 Electrochemical catalyst layer 5 Electrolyte 6 Spacer
7 Sealing material 8 Condensing device 9 Antireflection film

Claims (11)

A method for producing a dye-sensitized solar cell in which a photoelectrode and a counter electrode are arranged to face each other via an electrolyte layer,
The dye-sensitized solar cell is
(1) A photoelectrode is formed by forming a titanium oxide layer containing a dye sensitizer on a titanium material,
(2) The counter electrode is a transparent conductive glass or transparent conductive film coated with an electrochemical reduction catalyst layer,
(3) The light collecting device is arranged on the counter electrode side,
The titanium material is a material selected from the group consisting of metal titanium and titanium alloy,
The photoelectrode has the following steps:
(1) a step of forming titanium nitride on the surface of the titanium metal material or titanium alloy material;
(2) The metal titanium material or titanium alloy material having titanium nitride formed on the surface obtained in step (1) is made to have a spark discharge generation voltage or higher by using an electrolytic solution having an etching action on titanium. Anodizing and forming a film of anatase-type titanium oxide,
(3) On the anatase-type titanium oxide film obtained in step (2), after applying a paste containing titanium oxide, heat treatment is performed at a temperature of 400 to 500 ° C. in an oxidizing atmosphere to form a titanium oxide layer. Forming, and
(4) The titanium oxide layer obtained in the step (3) is formed by a step of adsorbing the dye sensitizer to the titanium oxide layer by immersing it in a solution containing the dye sensitizer. Production method. A method for producing a dye-sensitized solar cell in which a photoelectrode and a counter electrode are arranged to face each other via an electrolyte layer,
The dye-sensitized solar cell is
(1) A photoelectrode is formed by forming a titanium oxide layer containing a dye sensitizer on a titanium material,
(2) The counter electrode is a transparent conductive glass or transparent conductive film coated with an electrochemical reduction catalyst layer,
(3) The light collecting device is arranged on the counter electrode side,
The titanium material is a material selected from the group consisting of metal titanium and titanium alloy,
The photoelectrode has the following steps:
(1) a step of forming titanium nitride on the surface of the titanium metal material or titanium alloy material;
(2) A step of anodizing the metal titanium material or titanium alloy material having titanium nitride formed on the surface obtained in step (1) in an electrolyte solution having no etching action on titanium,
(3) A step of heat-treating the anodized metal titanium material or titanium alloy material obtained in step (2) in an oxidizing atmosphere to form a film of anatase-type titanium oxide,
(4) A titanium oxide layer is formed by applying a paste containing titanium oxide on the anatase-type titanium oxide film obtained in step (3) and then heat-treating it at a temperature of 400 to 500 ° C. in an oxidizing atmosphere. Forming, and
(5) The titanium oxide layer obtained in step (4) is formed by a step of adsorbing the dye sensitizer to the titanium oxide layer by immersing it in a solution containing the dye sensitizer. Production method. The method for producing a dye-sensitized solar cell according to claim 1 or 2 , wherein the titanium oxide layer has a rectangular shape. The method for producing a dye-sensitized solar cell according to any one of claims 1 to 3 , wherein the electrochemical reduction catalyst layer is a platinum catalyst layer. The method for producing a dye-sensitized solar cell according to any one of claims 1 to 4 , wherein the transparent conductive glass or transparent conductive film of the counter electrode is an antireflection film processed. The dye-sensitized solar according to any one of claims 1 to 4 , wherein the counter electrode is one in which an antireflection film is further provided on a light irradiation surface of the transparent conductive glass or the transparent conductive film. Battery manufacturing method. The manufacturing method of the dye-sensitized solar cell according to any one of claims 1 to 6, wherein a cooling device is arranged. The step of forming the titanium nitride is performed by one kind of treatment method selected from the group consisting of PVD treatment, CVD treatment, thermal spray treatment, heat treatment under an ammonia gas atmosphere, and heat treatment under a nitrogen gas atmosphere. The manufacturing method of the dye-sensitized solar cell in any one of Claims 1-7 which is what is. The method for producing a dye-sensitized solar cell according to claim 8 , wherein the heat treatment under the nitrogen gas atmosphere is performed in the presence of an oxygen trap agent. The method for producing a dye-sensitized solar cell according to any one of claims 1 to 9 , wherein the electrochemical reduction catalyst layer is a platinum catalyst layer having a thickness of 0.5 to 1 nm. The method for producing a dye-sensitized solar cell according to any one of claims 1 to 10 , wherein the electrolyte layer has a thickness of 25 to 100 µm.

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