JP2010009830A - Photoelectric conversion element and its manufacturing method as well as solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric conversion element with high conversion efficiency and excellent in durability and its manufacturing method, as well as a solar cell using the photoelectric conversion element. <P>SOLUTION: In the manufacturing method of the photoelectric conversion element of a dye-sensitized type, made up of an electrode layer, a semiconductor electrode sequentially formed of semiconductor layers each carrying dyes, and an electrolyte layer on a substrate, the dyes are aromatic amine compounds, and carried on the semiconductor layer and formed at 40°C or more and 100°C or less. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a photoelectric conversion element, a manufacturing method thereof, and a solar cell.

  In recent years, the use of sunlight, which is infinite and does not generate harmful substances, has been energetically studied. What is currently put into practical use as solar energy, which is a clean energy source, includes residential single crystal silicon, polycrystalline silicon, amorphous silicon, and inorganic solar cells such as cadmium telluride and indium copper selenide. .

  However, the disadvantages of these inorganic solar cells include, for example, that silicon is required to have a very high purity, and naturally, the purification process is complicated, the number of processes is large, and the manufacturing cost is high.

  On the other hand, many solar cells using organic materials have been proposed. As an organic solar cell, a Schottky photoelectric conversion element that joins a p-type organic semiconductor and a metal having a low work function, a p-type organic semiconductor and an n-type inorganic semiconductor, or a p-type organic semiconductor and an electron-accepting organic compound are joined. There are heterojunction photoelectric conversion elements and the like, and organic semiconductors used are synthetic dyes and pigments such as chlorophyll and perylene, conductive polymer materials such as polyacetylene, or composite materials thereof. These are thinned by a vacuum deposition method, a casting method, a dipping method, or the like to form a battery material. Although organic materials have advantages such as low cost and easy area enlargement, there are many problems that the conversion efficiency is as low as 1% or less and the durability is poor.

  Under such circumstances, a solar cell exhibiting good characteristics has been reported by Dr. Gretzell of Switzerland (see Non-Patent Document 1). The proposed battery is a dye-sensitized solar cell, which is a wet solar cell using a titanium oxide porous thin film spectrally sensitized with a ruthenium complex as a working electrode. The advantage of this method is that inexpensive metal compound semiconductors such as titanium oxide do not need to be purified to high purity. Therefore, the light that is inexpensive and can be used extends over a wide visible light region, and the sun is rich in visible light components. It is that light can be effectively converted into electricity.

  On the other hand, ruthenium complexes with limited resources are used, so when this solar cell is put to practical use, the supply of ruthenium complexes is in danger. Further, this ruthenium complex is expensive and has problems with stability over time, and this problem can be solved if it can be changed to an inexpensive and stable organic dye.

  It is known that a dye molecule having both a π-electron conjugated system having an electron donating ability and an acidic adsorbing group having an electron-withdrawing property gives an element having high photoelectric conversion efficiency. Triarylamine derivatives are widely used as the electron-donating π-electron system (see, for example, Patent Documents 1 to 4). If there is a substituent or ring structure having a strong electron-withdrawing property around the acidic adsorbing group, the excited electrons are distributed unevenly around the adsorbing group, which is advantageous for charge injection into the oxide semiconductor electrode. It is expected to provide a more excellent photoelectric conversion element.

  In addition to the structure of the dye, the stability over time of the solar cell also depends on the amount of dye adsorbed on the semiconductor layer, the arrangement, the manner of aggregation, etc., and the process of supporting the dye on the semiconductor layer is durable. It is important for improvement of sex.

  It is known that the N3 dye of ruthenium complex has high conversion efficiency when a dye is adsorbed in a single layer by mixing a bile acid derivative or the like in a dye solution and co-adsorbing it to a titanium oxide semiconductor electrode. However, due to single molecule adsorption, it is easy to desorb with moisture, and oxidative decomposition is likely to occur, and there is a problem in durability.

On the other hand, dyes that form polymers or aggregates are advantageous for durability, but intermolecular interactions such as electron transfer between the dyes occur, and the efficiency is inferior to single molecule adsorbents.
JP 2005-123033 A JP 2006-079898 A JP 2006-134649 A JP 2006-156212 A B. O'Regan, M.M. Gratzel, Nature, 353, 737 (1991)

  An object of the present invention is to provide a photoelectric conversion element having high conversion efficiency and excellent durability, a method for producing the photoelectric conversion element, and a solar cell using the photoelectric conversion element.

  The above object of the present invention is achieved by the following configurations.

  1. In the method for producing a dye-sensitized photoelectric conversion element comprising an electrode layer, a semiconductor electrode formed by sequentially providing a semiconductor layer carrying a dye on a substrate, and an electrolyte layer, the dye is an aromatic amine A method for producing a photoelectric conversion element, which is a compound and formed by supporting the dye on a semiconductor layer at 40 ° C. or higher and 100 ° C. or lower.

  2. 2. The method for producing a photoelectric conversion element as described in 1 above, wherein the semiconductor layer carrying the dye is formed by immersing in a solution or dispersion of the dye.

  3. 3. The method for producing a photoelectric conversion element according to 1 or 2, wherein the aromatic amine compound is a triarylamine compound.

  4). 4. The method for producing a photoelectric conversion element according to any one of 1 to 3, wherein the dye has an acidic group.

  5. 5. The method for producing a photoelectric conversion element as described in 4 above, wherein the acidic group is a carboxyl group.

  6). 6. The method for producing a photoelectric conversion element according to any one of 1 to 5, wherein the dye has a cyano group.

  7). 7. The method for producing a photoelectric conversion element according to any one of 1 to 6, wherein the semiconductor forming the semiconductor layer is titanium oxide.

  8). A photoelectric conversion element obtained by the method for manufacturing a photoelectric conversion element according to any one of 1 to 7 above.

  9. 9. A solar cell comprising the photoelectric conversion element as described in 8 above.

  According to the present invention, it was possible to provide a photoelectric conversion element having high conversion efficiency and excellent durability, a method for producing the photoelectric conversion element, and a solar cell using the photoelectric conversion element.

  The inventors of the present invention determined that a sensitizing dye generates a current by repeating a photooxidation reaction during power generation, and that a dye resistant to oxidation is suitable for improving durability. Therefore, a dye having an aromatic amine structure was selected. Furthermore, among the dyes having an aromatic amine structure, triarylamine, which is highly durable against ozone, which is a strong oxidant, is used as the nuclei of the sensitizing dye, and photoexcited electrons are efficiently transferred to the titanium oxide electrode. In order to make it possible, an acidic group was added, and a structure capable of forming a chelate bond with titanium oxide was found to be preferable.

  Furthermore, the present inventors have determined that control of the aggregation state of the sensitizing dye carried on the semiconductor electrode is important for improving the durability of the photoelectric conversion element. The control of the aggregation state is performed in the process of carrying the sensitizing dye on the semiconductor electrode. When dye adsorption is performed by immersing a semiconductor electrode in a dye solution or a dye dispersion, the dye on the semiconductor electrode surface is a result of complex interactions between the semiconductor electrode surface, solvent, dye, and other additive substances. It is presumed that the aggregation state is determined.

  The present inventors have found that durability is improved by using a dye having an aromatic amine structure to adsorb the dye at a higher temperature than usual. The reason is not clear, but it is presumed that at high temperatures, the reaction rate of adsorption / desorption of the dye on the surface of the semiconductor electrode increases, and a thermally stable array state is created. In addition, it is presumed that the solvent volatilization rate, temperature change, and the like at the time of taking out the semiconductor electrode adsorbed with the dye from the dye solution or the dye dispersion solution also contribute to stabilization of the aggregation state of the dye.

  Hereinafter, the present invention will be described in more detail.

  The photoelectric conversion element of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an example of the photoelectric conversion element of the present invention.

  As shown in FIG. 1, it is composed of substrates 1, 1 ', transparent conductive films (also referred to as electrode layers) 2, 7, semiconductor 3, dye 4, electrolyte 5, counter electrode 6, partition wall 9 and the like.

  As a semiconductor electrode, it has a semiconductor layer having pores formed by sintering particles of the semiconductor 3 on a substrate 1 (also referred to as a conductive support) provided with a transparent conductive film 2, and the surface of the pores. A material in which the dye 4 is adsorbed is used.

  As the counter electrode 6, a transparent conductive film 7 formed on a substrate 1 ′ and platinum 8 deposited thereon is used, and an electrolyte 5 is filled between both electrodes as a charge transport layer (also referred to as an electrolyte layer). Has been.

<Dye>
In the present invention, a dye of an aromatic amine compound (hereinafter also referred to as a dye of the present invention) is used. The entire compound preferably constitutes one π-conjugated system. Examples of the aromatic group of the aromatic amine compound include an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent. Examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, a biphenyl group, an anthryl group, and a henanthryl group. Examples of the aromatic heterocyclic group include a thienyl group, a furyl group, an indolyl group, and the like. . Preferred groups of the aromatic group of the aromatic amine compound are shown below.

  The aromatic amine compound is preferably a triarylamine compound.

  The dye of the present invention preferably has an acidic group. Examples of the acidic group include a carboxyl group, a sulfo group, a sulfino group, a sulfinyl group, a phosphoryl group, a phosphinyl group, a phosphono group, a thiol group, a hydroxy group, a phosphonyl group, and a sulfonyl group. As the acidic group, a carboxyl group is more preferable. In the case of a compound having a carboxyl group having a high adsorbing ability on a semiconductor, the flow of electric charge to the semiconductor is smooth, and favorable characteristics are exhibited.

  The dye of the present invention preferably has an electron withdrawing group. Examples of the electron withdrawing group include a fluoro group, a chloro group, a bromo group, a nitro group, a cyano group, an alkylsulfonyl group, an arylsulfonyl group, a perfluoroalkylsulfonyl group, a perfluoroarylsulfonyl group, and a rhodanine ring. Among them, it is preferable to have a cyano group having a high electron attractive force.

  Although the specific example of the pigment | dye of this invention is shown below, this invention is not limited to these.

  The dye of the present invention can be produced using a known method such as JP-A-7-5709 and JP-A-7-5706.

  The thus obtained dye of the present invention is sensitized by supporting it on a semiconductor, and the effects described in the present invention can be achieved. Here, loading a dye on a semiconductor means various modes such as adsorption onto the surface of the semiconductor, and when the semiconductor has a porous structure such as a porous structure, the semiconductor porous structure is filled with the dye. Can be mentioned.

Further, the total supported amount of the dye of the present invention per 1 m ² of the semiconductor layer (which may be a semiconductor) is preferably in the range of 0.01 to 100 mmol, more preferably 0.1 to 50 mmol, particularly preferably 0.8. 5-20 mmol.

  When the sensitization treatment is performed using the dye of the present invention, the dye may be used alone or in combination, and other compounds (for example, US Pat. No. 4,684,537). 4,927,721, 5,084,365, 5,350,644, 5,463,057, 5,525,440 And compounds described in JP-A-7-249790, JP-A-2000-150007, and the like.

  In particular, when the use of the photoelectric conversion element of the present invention is a solar cell to be described later, two or more types of dyes having different absorption wavelengths are used so that the wavelength range of photoelectric conversion can be made as wide as possible to effectively use sunlight. It is preferable to use a mixture.

  In order to support the dye of the present invention on a semiconductor, it is preferable to form the semiconductor by immersing a well-dried semiconductor in a solution or dispersion in which the dye is dissolved in an appropriate solvent (ethanol or the like).

  When sensitizing the dyes of the present invention in combination with a plurality of dyes or in combination with other dyes, a mixed solution or dispersion of each dye may be prepared and used. These solutions or dispersions can be prepared and immersed in each solution or dispersion in order. When preparing a separate solution or dispersion for each dye and immersing in each solution or dispersion in order, the effects described in the present invention can be obtained regardless of the order in which the dye is included in the semiconductor. Obtainable. Alternatively, it may be produced by mixing fine particles of semiconductor adsorbing the dye alone.

  The details of the semiconductor sensitization process according to the present invention will be specifically described in the photoelectric conversion element described later.

  In the case of a semiconductor with a high porosity, it is preferable to complete the adsorption treatment of the dye or the like before water is adsorbed on the semiconductor thin film and in the voids inside the semiconductor thin film due to moisture, water vapor or the like.

  Next, the photoelectric conversion element of the present invention will be described.

[Photoelectric conversion element]
The photoelectric conversion element of the present invention is formed by disposing a semiconductor electrode obtained by adding a dye to a semiconductor on a conductive support and a counter electrode through an electrolyte layer. Hereinafter, the semiconductor, the semiconductor electrode, the electrolyte, and the counter electrode will be sequentially described.

"semiconductor"
Semiconductors used for semiconductor electrodes include simple substances such as silicon and germanium, compounds having elements of Group 3 to Group 5, Group 13 to Group 15 of the periodic table (also referred to as element periodic table), metals Chalcogenides (for example, oxides, sulfides, selenides, etc.), metal nitrides, and the like can be used.

  Preferred metal chalcogenides include titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium or tantalum oxides, cadmium, zinc, lead, silver, antimony or Bismuth sulfide, cadmium or lead selenide, cadmium telluride and the like. Examples of other compound semiconductors include phosphides such as zinc, gallium, indium and cadmium, gallium-arsenic or copper-indium selenide, copper-indium sulfide, titanium nitride, and the like.

Specific examples include TiO ₂ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , ZnO, Nb ₂ O ₅ , CdS, ZnS, PbS, Bi ₂ S ₃ , CdSe, CdTe, GaP, InP, GaAs, CuInS ₂ , CuInSe ₂ , Ti ₃ N _{4 and the} like can be mentioned, but TiO ₂ , ZnO, SnO ₂ , Fe ₂ O ₃ , WO ₃ , Nb ₂ O ₅ , CdS, and PbS are preferably used. Is TiO ₂ or Nb ₂ O ₅ , among which TiO ₂ (titanium oxide) is particularly preferably used.

The semiconductor used for the semiconductor electrode may be used in combination with a plurality of semiconductors described above. For example, several kinds of the metal oxides or metal sulfides described above can be used in combination, or 20% by mass of titanium nitride (Ti ₃ N ₄ ) may be mixed and used in the titanium oxide semiconductor. In addition, J.H. Chem. Soc. , Chem. Commun. 15 (1999). At this time, when a component is added as a semiconductor in addition to the metal oxide or metal sulfide, the mass ratio of the additional component to the metal oxide or metal sulfide semiconductor is preferably 30% or less.

  Further, the semiconductor according to the present invention may be surface-treated using an organic base. Examples of the organic base include diarylamine, triarylamine, pyridine, 4-t-butylpyridine, polyvinylpyridine, quinoline, piperidine, and amidine, among which pyridine, 4-t-butylpyridine, and polyvinylpyridine are preferable. .

  When the organic base is a liquid, the surface treatment can be carried out by preparing a solution dissolved in an organic solvent and immersing the semiconductor according to the present invention in a liquid amine or an amine solution.

(Substrate, conductive support)
The conductive support used in the photoelectric conversion element of the present invention and the solar battery of the present invention is provided with a conductive material such as a conductive material such as a metal plate or a non-conductive material such as a glass plate or a plastic film. A structure having a different structure can be used. Examples of materials used for the conductive support include metal (for example, platinum, gold, silver, copper, aluminum, rhodium, indium) or conductive metal oxide (for example, indium-tin composite oxide, tin oxide doped with fluorine) And carbon). The thickness of the conductive support is not particularly limited, but is preferably 0.3 to 5 mm.

  Further, the conductive support is preferably substantially transparent, and substantially transparent means that the light transmittance is 10% or more, more preferably 50% or more, Most preferably, it is 80% or more. In order to obtain a transparent conductive support, it is preferable to provide a conductive layer made of a conductive metal oxide on the surface of a glass plate or a plastic film. When a transparent conductive support is used, light is preferably incident from the support side.

The surface resistance of the conductive support is preferably 50 Ω / cm ² or less, and more preferably 10 Ω / cm ² or less.

<< Production of semiconductor electrode >>
A method for manufacturing a semiconductor electrode according to the present invention will be described.

  When the semiconductor of the semiconductor electrode according to the present invention is in the form of particles, the semiconductor electrode is preferably manufactured by coating or spraying the semiconductor on a conductive support. In addition, when the semiconductor according to the present invention is in the form of a film and is not held on the conductive support, it is preferable to produce a semiconductor electrode by bonding the semiconductor onto the conductive support.

  As a preferred embodiment of the semiconductor electrode according to the present invention, there is a method of forming the semiconductor electrode on the conductive support by firing using fine particles of semiconductor.

  When the semiconductor according to the present invention is produced by firing, the semiconductor sensitization (adsorption, filling in a porous layer, etc.) treatment with a dye is preferably performed after firing. It is particularly preferable to perform the compound adsorption treatment quickly after the firing and before the water is adsorbed to the semiconductor.

  Hereinafter, a method for forming a semiconductor electrode preferably used in the present invention by baking using semiconductor fine powder will be described in detail.

(Preparation of coating liquid containing semiconductor fine powder)
First, a coating solution containing fine semiconductor powder is prepared. The finer the primary particle diameter of the semiconductor fine powder, the better. The primary particle diameter is preferably 1 to 5000 nm, and more preferably 2 to 50 nm. The coating liquid containing the semiconductor fine powder can be prepared by dispersing the semiconductor fine powder in a solvent. The semiconductor fine powder dispersed in the solvent is dispersed in the form of primary particles. The solvent is not particularly limited as long as it can disperse the semiconductor fine powder.

  Examples of the solvent include water, an organic solvent, and a mixed solution of water and an organic solvent. As the organic solvent, alcohols such as methanol and ethanol, ketones such as methyl ethyl ketone, acetone and acetyl acetone, hydrocarbons such as hexane and cyclohexane, and the like are used. A surfactant and a viscosity modifier (polyhydric alcohol such as polyethylene glycol) can be added to the coating solution as necessary. The range of the semiconductor fine powder concentration in the solvent is preferably 0.1 to 70% by mass, and more preferably 0.1 to 30% by mass.

(Application of coating solution containing fine semiconductor powder and baking treatment of the formed semiconductor layer)
The semiconductor fine powder-containing coating solution obtained as described above is applied or sprayed onto a conductive support, dried, etc., and then baked in air or an inert gas to provide a conductive support. A semiconductor layer (also referred to as a semiconductor film) is formed thereover.

  A film obtained by applying and drying a coating solution containing semiconductor fine powder on a conductive support is composed of an aggregate of semiconductor fine particles, and the particle size of the fine particles is equal to the primary particle size of the semiconductor fine powder used. Corresponding.

  Thus, the semiconductor fine particle layer formed on the conductive layer such as the conductive support is weak in bonding strength with the conductive support and fine particles, and has low mechanical strength. The semiconductor fine particle layer is baked to increase the mechanical strength and form a semiconductor layer that is strongly adhered to the substrate.

  In the present invention, the semiconductor layer may have any structure, but is preferably a porous structure film (also referred to as a porous layer having voids).

  Here, the porosity of the semiconductor layer according to the present invention is preferably 10% by volume or less, more preferably 8% by volume or less, and particularly preferably 0.01 to 5% by volume. The porosity of the semiconductor layer means a porosity that is penetrable in the thickness direction of the dielectric, and can be measured using a commercially available device such as a mercury porosimeter (Shimadzu Polarizer 9220 type).

  The film thickness of the semiconductor layer that is a fired product film having a porous structure is preferably at least 10 nm or more, and more preferably 100 to 10,000 nm.

  From the viewpoint of appropriately preparing the actual surface area of the fired film during the firing treatment and obtaining a fired film having the above porosity, the firing temperature is preferably lower than 1000 ° C, more preferably in the range of 200 to 800 ° C. Especially preferably, it is the range of 300-800 degreeC.

  The ratio of the actual surface area to the apparent surface area can be controlled by the particle size, specific surface area, firing temperature, etc. of the semiconductor fine particles. In addition, for the purpose of increasing the surface area of the semiconductor particles after heating, increasing the purity in the vicinity of the semiconductor particles, and increasing the efficiency of electron injection from the dye into the semiconductor particles, for example, chemical plating using a titanium tetrachloride aqueous solution or three An electrochemical plating process using a titanium chloride aqueous solution may be performed.

(Semiconductor sensitization treatment)
As described above, the semiconductor sensitization treatment is performed by dissolving or dispersing the dye of the present invention in an appropriate solvent and immersing the substrate obtained by firing the semiconductor in the solution or dispersion. In that case, it is preferable that a base in which a semiconductor layer (also referred to as a semiconductor film) is formed by baking is subjected to a pressure reduction treatment or a heat treatment in advance to remove bubbles in the film. Such treatment allows the dye of the present invention to penetrate deep inside the semiconductor layer (semiconductor film), and is particularly preferable when the semiconductor layer (semiconductor film) is a porous structure film.

  The solvent used for dissolving the coloring matter of the present invention is not particularly limited as long as it can dissolve or disperse the compound and does not dissolve or react with the semiconductor. However, in order to prevent moisture and gas dissolved in the solvent from entering the semiconductor film and hindering the sensitization treatment such as adsorption of the compound, it is preferable to perform deaeration and distillation purification in advance.

  Solvents preferably used for dissolving or dispersing the compound include alcohol solvents such as methanol, ethanol and n-propanol, ketone solvents such as acetone and methyl ethyl ketone, diethyl ether, diisopropyl ether, tetrahydrofuran and 1,4-dioxane. Ether solvents, halogenated hydrocarbon solvents such as methylene chloride, 1,1,2-trichloroethane, etc., particularly preferably methanol, ethanol, acetone, methyl ethyl ketone, tetrahydrofuran and methylene chloride.

(Tensing temperature and time)
The time for immersing the substrate obtained by baking the semiconductor in the solution or dispersion containing the dye of the present invention is to deeply enter the semiconductor layer (semiconductor film) to sufficiently advance adsorption and the like and sufficiently sensitize the semiconductor. preferable. In addition, from the viewpoint of suppressing degradation of the dye produced by decomposition of the dye in the solution or dispersion and hindering adsorption of the dye, the time is preferably 3 to 48 hours, and more preferably 4 to 24 hours. This effect is particularly remarkable when the semiconductor film is a porous structure film.

  The temperature at which the substrate obtained by firing the semiconductor is immersed in the solution or dispersion containing the dye of the present invention is 40 to 100 ° C. As long as the dye does not decompose, it may be used by heating to a temperature at which it does not boil. The preferred temperature range is 60 to 80 ° C. However, this is not the case when the solvent boils within the temperature range as described above. Thus, durability is improved by carrying out dye adsorption at higher temperature than usual. Although the reason is not clear, it is presumed that at high temperatures, the reaction rate of dye adsorption / desorption on the surface of the semiconductor electrode is increased, and a thermally stable array state is created. Further, it is presumed that the solvent volatilization rate, temperature change, and the like at the time of taking out the dye-adsorbed semiconductor electrode from the dye solution or dye dispersion solution also contribute to stabilization of the dye aggregation state.

"Electrolytes"
The electrolyte used in the present invention will be described.

In the photoelectric conversion element of the present invention, an electrolyte is filled between the counter electrodes to form an electrolyte layer. A redox electrolyte is preferably used as the electrolyte. Here, examples of the redox electrolyte include I ⁻ / I ₃ ⁻ system, Br ⁻ / Br ₃ ⁻ system, and quinone / hydroquinone system. Such redox electrolyte can be obtained by a conventionally known method, for example, I ^- / I ₃ ^- system electrolyte can be obtained by mixing an ammonium salt of iodine and iodine. The electrolyte layer is composed of dispersions of these redox electrolytes. These dispersions are dispersed in liquid electrolytes when they are solutions, solid polymer electrolytes and gel substances when dispersed in polymers that are solid at room temperature. It is called a gel electrolyte. When a liquid electrolyte is used as the electrolyte layer, an electrochemically inert solvent is used as the solvent, for example, acetonitrile, propylene carbonate, ethylene carbonate, or the like is used. Examples of the solid polymer electrolyte include the electrolyte described in JP-A No. 2001-160427, and examples of the gel electrolyte include the electrolyte described in “Surface Science” Vol. 21, No. 5, pages 288 to 293.

  Instead of the electrolyte, the following solid electrolyte (solid charge transport material) may be used.

As an electrolyte layer (charge transport layer) using a solid electrolyte, a solid hole or an electron transfer material can also be applied. Various metal phthalocyanines, perylene tetracarboxylic acids, polycyclic aromatics such as perylene and coronene, tetrathiafulvalene, tetracyano, etc. Crystalline materials such as charge transfer complexes such as quinodimethane, or amorphous conductive polymers such as Alq ₃ , diamine, various oxadiazoles, polypyrrole, polyaniline, polyphenylene vinylene, and the like are also applicable. The raw material of the solid charge transport material is a powdery, granular or plate-like solid at room temperature. At the time of bonding with the n-type semiconductor electrode, the solid material is placed on the surface of the semiconductor electrode under normal pressure and then the pressure is reduced, or the solid material is placed on the surface of the semiconductor electrode under reduced pressure. Subsequently, the solid charge transport material is heated to a glass transition temperature or a melting point or higher, and the solid charge transport material and the n-type semiconductor electrode are bonded, thereby realizing a good bond between the n-type semiconductor electrode and the solid charge transport material.

  Alternatively, a film in which the charge transport material is dissolved or dispersed in the binder resin may be formed. Examples of the charge transport material used in the present invention include the following compounds.

《Counter electrode》
The counter electrode used in the present invention will be described.

The counter electrode as long as it has conductivity, but any conductive material is used, I ₃ ^- with catalytic ability to perform fast enough the reduction reaction of oxidation and other redox ions such as ions Is preferably used. Examples of such a material include a platinum electrode, a surface of a conductive material subjected to platinum plating or platinum deposition, rhodium metal, ruthenium metal, ruthenium oxide, and carbon.

[Solar cell]
The solar cell of the present invention will be described.

  The solar cell of the present invention has a structure in which the optimum design and circuit design for sunlight are performed as one aspect of the photoelectric conversion element of the present invention, and the optimum photoelectric conversion is performed when sunlight is used as a light source. Have That is, the semiconductor is dye-sensitized and can be irradiated with sunlight. When configuring the solar cell of the present invention, it is preferable that the semiconductor electrode, the electrolyte layer and the counter electrode are housed in a case and sealed, or the whole is sealed with a resin.

  When the solar cell of the present invention is irradiated with sunlight or an electromagnetic wave equivalent to sunlight, the dye according to the present invention supported on a semiconductor absorbs the irradiated light or electromagnetic wave and excites it. Electrons generated by excitation move to the semiconductor, and then move to the counter electrode via the conductive support to reduce the redox electrolyte in the charge transfer layer. On the other hand, the dye according to the present invention in which electrons are transferred to a semiconductor is an oxidant, but is reduced to the original state by supplying electrons from the counter electrode via the redox electrolyte of the electrolyte layer. At the same time, the redox electrolyte of the charge transfer layer is oxidized and returned to a state where it can be reduced again by electrons supplied from the counter electrode. In this way, electrons flow, and a solar cell using the photoelectric conversion element of the present invention can be configured.

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

Example << Production of Photoelectric Conversion Element >>
<Production of liquid electrolyte cell type photoelectric conversion element>
(Preparation of photoelectric conversion element SC-1: the present invention)
Photoelectric conversion element SC-1 was produced according to the procedure described below.

  A commercially available titanium oxide paste (particle size 18 nm) was applied to a fluorine-doped tin oxide (FTO) conductive glass substrate by a screen printing method. The paste was dried by heating at 100 ° C. for 10 minutes, and then baked at 500 ° C. for 30 minutes to obtain a titanium oxide thin film having a thickness of 8 μm.

Exemplified Compound A-1 was dissolved in ethanol to prepare a 3 × 10 ⁻⁴ M solution. The FTO glass substrate coated and sintered with titanium oxide was immersed in this solution at 40 ° C. for 3 hours for dye adsorption treatment, then washed with ethanol and vacuum dried to obtain a semiconductor electrode.

  As the electrolytic solution, a 3-methylpropionitrile solution containing 0.4 M lithium iodide, 0.05 M iodine, and 0.5 M 4- (t-butyl) pyridine was used.

  A platinum plate was used as the counter electrode, and a photoelectric conversion element (solar cell) SC-1 was obtained by assembling the previously prepared semiconductor electrode, an electrolytic solution, and a clamp cell.

(Production of photoelectric conversion elements SC-2 and SC-3: the present invention)
In the production of the photoelectric conversion element SC-1, the same applies except that the solvent of the dye solution is changed from ethanol to acetonitrile / t-butanol = 1/1, and the liquid temperature of the adsorption solution is changed from 40 ° C. to 60 ° C. and 80 ° C. Thus, photoelectric conversion elements SC-2 and SC-3 were obtained.

(Preparation of photoelectric conversion element SC-4: the present invention)
In the production of the photoelectric conversion element SC-1, the solvent of the dye solution was changed from ethanol to methyl isobutyl ketone / chlorobenzene = 1/1, and the liquid temperature of the adsorption solution was changed from 40 ° C. to 100 ° C. in the same manner. A photoelectric conversion element SC-4 was obtained.

(Preparation of photoelectric conversion elements SC-5 to SC-7: the present invention)
In the production of the photoelectric conversion element SC-2, except that Exemplified Compound A-1 was changed to Exemplified Compounds A-2, A-3, and A-4, Photoelectric Conversion Elements SC-5, SC-6, SC-7 was obtained.

(Production of photoelectric conversion elements SC-R1 and SC-R2: comparison)
In the production of the photoelectric conversion element SC-1, photoelectric conversion elements SC-R1 and SC-R2 were obtained in the same manner except that the liquid temperature of the adsorption solution was changed from 40 ° C. to 5 ° C. and 35 ° C.

(Production of photoelectric conversion element SC-R3: comparison)
In the production of the photoelectric conversion element SC-1, the solvent of the dye solution was changed from ethanol to methyl isobutyl ketone / chlorobenzene = 1/1, and the liquid temperature of the adsorption solution was changed from 40 ° C. to 110 ° C. in the same manner. A photoelectric conversion element SC-R3 was obtained.

(Production of photoelectric conversion element SC-R4: comparison)
Photoelectric conversion element SC-R4 was obtained in the same manner except that the exemplary compound was changed from A-1 to R1 and the temperature of the adsorbed solution was changed to 50 ° C. in the production of photoelectric conversion element SC-1.

(Production of photoelectric conversion element SC-R5: comparison)
Photoelectric conversion element SC-R5 was obtained in the same manner except that the exemplary compound was changed from A-1 to R2 and the liquid temperature of the adsorption solution was changed to 25 ° C. in the production of photoelectric conversion element SC-1.

<Production of solid electrolyte cell type photoelectric conversion element>
(Preparation of photoelectric conversion element SE-1: the present invention)
An alkoxy titanium solution (Matsumoto Kosho: TA-25 / IPA dilution) was applied to the FTO electrode by spin coating. After standing at room temperature for 30 minutes, baking was performed at 450 ° C. for 30 minutes to form a short-circuit prevention layer. Subsequently, a commercially available titanium oxide paste (particle size: 18 nm) was applied to the base plate by a screen printing method, then heat-treated at 100 ° C. for 10 minutes, and then baked at 500 ° C. for 30 minutes. A semiconductor electrode substrate having a thin film was obtained.

Exemplified Compound A-1 was dissolved in ethanol to prepare a 3 × 10 ⁻⁴ M solution. The semiconductor electrode substrate was immersed in this solution at 60 ° C. for 3 hours to perform a dye adsorption treatment, and then washed with ethanol and vacuum dried to obtain a semiconductor electrode.

Next, 0.17 M of the following spiro-MeO TAD is used as a hole transport agent in a toluene solvent, 0.33 mM of N (PhBr) ₃ SbCl ₆ as a hole doping agent, and Li [(CF ₃ SO ₂ ) ₂ N]. 15 mM was dissolved and spin-coated on the semiconductor electrode after dye adsorption to form a solid electrolyte layer. Furthermore, 30 nm of gold was vapor-deposited by a vacuum vapor deposition method, a counter electrode was produced, and photoelectric conversion element SE-1 was obtained.

(Production of photoelectric conversion element SE-R1: comparison)
In the production of the photoelectric conversion element SE-1, Exemplified Compound A-1 was changed to R2, and the photoelectric conversion element SE-R1 was obtained in the same manner except that the dye adsorption condition was changed to 25 ° C. for 20 hours.

<< Evaluation of photoelectric conversion element >>
Photoelectric conversion element manufactured, xenon lamp irradiation of a strength 100 mW / cm ^2, was measured photoelectric conversion characteristics under conditions masked of 5 × 5 mm ² in the semiconductor electrode.

  That is, for the photoelectric conversion element, current-voltage characteristics were measured at room temperature using an IV tester, and a short circuit current (Jsc), an open circuit voltage (Voc), and a form factor (FF) were obtained. From this, the photoelectric conversion efficiency (η (%)) was determined. The photoelectric conversion efficiency (η (%)) of the photoelectric conversion element was calculated based on the following formula (A).

η = 100 × (Voc × Jsc × FF) / P (A)
Here, P is the incident light intensity [mW · cm ⁻² ], Voc is the open circuit voltage [V], Jsc is the short-circuit current density [mA · cm ⁻² ], F.V. F. Represents a form factor.

Further, the semiconductor electrode was irradiated with a xenon lamp having an intensity of 100 mW / cm ² for 30 minutes, and then exposed to a 9 ppm ozone atmosphere for 20 minutes. Then, the photoelectric conversion efficiency was measured, and the xenon lamp irradiation / ozone exposure was measured. The efficiency ratio of the photoelectric conversion efficiency before and after the deterioration operation was obtained.

  The evaluation results are shown in Table 1.

  From Table 1, the dye adsorption temperature of the photoelectric conversion elements SC-1 to SC-7 of the present invention in which the dye is an aromatic amine compound and the dye adsorption temperature to the semiconductor layer is 40 ° C. or higher and 100 ° C. or lower is 40. It turns out that it has high light resistance compared with the comparative photoelectric conversion element SC-R1-SC-R3, SC-R5 which is outside the range of ℃ -100 ℃. Further, even when the dye adsorption temperature is in the range of 40 ° C. or higher and 100 ° C. or lower, the photoelectric conversion element SC-R4 using the comparative dye (R1: Ru complex) in which the dye is not an aromatic amine compound has poor light resistance. I understand that.

  Also in the case of a solid electrolyte cell type photoelectric conversion element, the photoelectric conversion element SE-1 of the present invention having a dye adsorption temperature of 40 ° C. or more and 100 ° C. or less is outside the range of the dye adsorption temperature of 40 ° C. or more and 100 ° C. or less. It turns out that it has high light resistance compared with the comparative photoelectric conversion element SE-R1 which is.

It is a structure sectional view showing an example of a photoelectric conversion element of the present invention.

Explanation of symbols

1, 1 ′ substrate 2, 7 transparent conductive film 3 semiconductor 4 dye 5 electrolyte 6 counter electrode 8 platinum

Claims (9)

In the method for producing a dye-sensitized photoelectric conversion element comprising an electrode layer, a semiconductor electrode formed by sequentially providing a semiconductor layer carrying a dye on a substrate, and an electrolyte layer, the dye is an aromatic amine A method for producing a photoelectric conversion element, which is a compound and formed by supporting the dye on a semiconductor layer at 40 ° C. or higher and 100 ° C. or lower. The method for producing a photoelectric conversion element according to claim 1, wherein the semiconductor layer carrying the dye is formed by immersing in a solution or dispersion of the dye. The method for producing a photoelectric conversion element according to claim 1, wherein the aromatic amine compound is a triarylamine compound. The method for producing a photoelectric conversion element according to claim 1, wherein the dye has an acidic group. The method for producing a photoelectric conversion element according to claim 4, wherein the acidic group is a carboxyl group. The method for producing a photoelectric conversion device according to claim 1, wherein the dye has a cyano group. The method for manufacturing a photoelectric conversion element according to claim 1, wherein the semiconductor forming the semiconductor layer is titanium oxide. A photoelectric conversion element obtained by the method for manufacturing a photoelectric conversion element according to claim 1. A solar cell comprising the photoelectric conversion element according to claim 8.

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