JP2009252403A - Method of manufacturing dye-sensitized solar cell and dye-sensitized solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dye-sensitized solar cell forming a porous n-type semiconductor electrode on a film substrate with low temperature and in a short time. <P>SOLUTION: In a method of manufacturing the dye-sensitized solar cell manufactured by laminating a porous n-type semiconductor electrode 2 with dye supported, a charge transport layer and a counter electrod in this order on a conductive base material 1, the porous n-type semiconductor electrode is a porous semiconductor film consisting of at least a core layer having a crystalline n-type semiconductor 22 and a shell layer with its surface consisting of a microwave absorbing layer 21, and is manufactured by irradiating microwave to the porous semiconductor film. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a dye-sensitized solar cell, and a dye-sensitized solar cell produced by the production method.

  In recent years, with the burning of fossil fuels and an increase in the amount of carbon dioxide generated, environmental and energy problems such as global warming have become more serious, and the energy source is clean and inexhaustible. Air pollutants during power generation As a power generation system that does not generate noise and has a low environmental impact, various solar cells that efficiently extract solar energy as an energy source have been actively developed.

  Among them, the dye-sensitized solar cell is a structure that can be manufactured by a simple manufacturing process under atmospheric pressure using a general printing process. It is attracting attention as a next-generation solar cell following silicon, polycrystalline silicon, amorphous silicon, CIGS, and the like.

  In dye-sensitized solar cells, dye molecules adsorbed on the semiconductor surface absorb sunlight, and electrons are injected from the dye LUMO (lowest orbital) into the semiconductor CB (conduction band), so-called spectral sensitization. I do.

  The dye absorbs light energy and emits electrons, and the semiconductor titania receives the electrons and delivers them to the conductive substrate. On the other hand, the holes remaining in the dye oxidize iodine ions in the electrolyte, and I- changes to I3-, and this oxidized I3- receives and reduces electrons again at the counter electrode, and the electrons cycle between the two electrodes. To generate electricity.

  A semiconductor electrode used in a dye-sensitized solar cell generally has a nanoporous structure mainly composed of titanium oxide. The reason why nanoporous titanium oxide is preferable is that (1) the amount of dye adsorption can be dramatically increased by the high specific surface area due to nanoporous, and (2) the semiconductor film can be thickened because it has a particularly long electron lifetime. In other words, it is superior in electron uptake, (3) has an appropriate energy level in the exchange of electrons with the dye and electrolyte, and (4) is inexpensive as a material.

  In order to increase the productivity of dye-sensitized solar cells, application to flexible substrates is being studied. For example, instead of the FTO glass substrate conventionally used for the conductive base material, flexibility is achieved by producing a porous semiconductor electrode on a resinous conductive film substrate (hereinafter referred to as a film substrate). ing.

  Specific means for forming the porous semiconductor layer on the film substrate include a semiconductor layer forming method such as a pressure bonding method, an electrodeposition method, and microwave sintering. Among them, since sintering by microwaves heats and sinters the conductive substrate and the semiconductor electrode itself in a short time, a porous semiconductor layer can be formed on the film substrate with little load on the substrate (for example, , See Patent Document 1).

  However, since semiconductors used in dye-sensitized solar cells such as TiO2 and ZnO have a low dielectric loss factor and a low absorption of microwaves, the transparent electrode substrate itself is heated by increasing the irradiation frequency and output. The load on the substrate is large, and application to a film substrate is difficult.

  In addition, a method of laminating a transparent conductive layer, a microwave absorption layer, and a semiconductor layer in order to increase the energy absorption efficiency and producing a porous semiconductor layer has been studied (for example, see Patent Document 2). In this case, charge transfer between the microwave absorption layer and the semiconductor layer becomes a problem, and similarly to the above, it is difficult to apply to a film substrate.

Thus, the photoelectric conversion efficiency of the dye-sensitized solar cell using the semiconductor electrode produced using the microwave sintering method is an insufficient value particularly when a film substrate is used as the conductive substrate, Further improvement in sinterability is desired.
International Publication No. 04-033756 Pamphlet JP 2006-344507 A

  An object of the present invention is to form a dye-sensitized solar cell by forming a porous n-type semiconductor electrode on a film substrate at a low temperature for a short time.

  The above object of the present invention can be achieved by the following configuration.

  1. In a method for producing a dye-sensitized solar cell, in which a porous n-type semiconductor electrode carrying a dye, a charge transport layer, and a counter electrode are sequentially laminated on a conductive substrate, the porous n-type semiconductor electrode Is a porous semiconductor film comprising at least a core layer having a crystalline n-type semiconductor and a shell layer having a microwave absorption layer on the surface, and is produced by irradiating the porous semiconductor film with microwaves. A method for producing a dye-sensitized solar cell.

  2. 2. The method for producing a dye-sensitized solar cell according to 1, wherein the surface of the shell layer is further treated with hydrochloric acid, sulfuric acid, acetic acid or nitric acid after irradiation with microwaves.

  3. 3. The method for producing a dye-sensitized solar cell as described in 1 or 2 above, wherein the conductive substrate is a film substrate.

  4). 4. The method for producing a dye-sensitized solar cell according to any one of 1 to 3, wherein the shell layer is made of manganese oxide, bismuth oxide, or cobalt oxide.

  5). 5. The method for producing a dye-sensitized solar cell according to any one of 1 to 4, wherein the shell layer has a thickness of 20 nm or less.

  6). A dye-sensitized solar cell produced by the method for producing a dye-sensitized solar cell according to any one of 1 to 5 above.

  According to the present invention, a dye-sensitized solar cell could be produced by forming a porous n-type semiconductor electrode on a film substrate at a low temperature for a short time.

  Hereinafter, the present invention will be described in detail.

  The present invention relates to a method for producing a dye-sensitized solar cell in which a porous n-type semiconductor electrode carrying a dye, a charge transport layer, and a counter electrode are sequentially laminated on a conductive substrate. The n-type semiconductor electrode is a porous semiconductor film comprising a core layer having at least a crystalline n-type semiconductor and a shell layer having a microwave absorption layer on the surface, and the porous semiconductor film is irradiated with microwaves It is characterized by being manufactured. Further, it is preferable to further treat the surface of the shell layer with hydrochloric acid, sulfuric acid, acetic acid or nitric acid after irradiation with microwaves.

  Next, the dye-sensitized solar cell of the present invention will be described with reference to FIG.

  FIG. 1 is a schematic cross-sectional view showing the basic structure of the dye-sensitized solar cell of the present invention. As shown in FIG. 1, the dye-sensitized solar cell of the present invention includes a conductive substrate 1, a porous n-type semiconductor electrode 2 having a dye 3 adsorbed on the surface of a semiconductor, and a charge transfer layer (electrolyte layer). 4) and the counter electrode 5. In FIG. 1, e- represents an electron, and an arrow represents the flow of the electron.

  When constituting the dye-sensitized solar cell of the present invention, the porous n-type semiconductor electrode (also simply referred to as a semiconductor electrode), the charge transfer layer and the counter electrode are housed in a case and sealed. It is preferable to seal them entirely with resin.

  When the dye-sensitized solar cell of the present invention is irradiated with sunlight or an electromagnetic wave equivalent to sunlight, the dye 3 adsorbed on the semiconductor is excited by absorbing the irradiated sunlight or electromagnetic wave. Electrons generated by excitation move to the semiconductor, and then move to the counter electrode 5 via the conductive substrate 1 to reduce the redox electrolyte of the charge transfer layer 4.

  On the other hand, the dye 3 that has moved electrons to the semiconductor is an oxidant, but is reduced to the original state by supplying electrons from the counter electrode 5 via the redox electrolyte of the charge transfer layer 4. At the same time, the redox electrolyte of the charge transfer layer 4 is oxidized and returned to a state where it can be reduced again by the electrons supplied from the counter electrode 5. In this way, electrons flow and the dye-sensitized solar cell of the present invention can be configured.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  The present inventor examined issues such as open-circuit voltage, short-circuit current, form factor fill factor, and photoelectric conversion efficiency in dye-sensitized solar cells using a porous semiconductor film produced by microwave sintering as a photoelectrode. As a result, when the film electrode substrate was used to irradiate microwaves, the film substrate was preferentially heated and the substrate melted, and the energy required for sintering could not be applied sufficiently to the semiconductor layer itself. It was confirmed that the formation was insufficient, the grain boundary resistance was high, the short-circuit current value and the photoelectric conversion efficiency were not yet sufficiently satisfied.

  As a result of intensive studies in view of the above problems, the present inventor sinters by irradiating a porous film of an n-type semiconductor having a microwave absorption layer in a shell portion on a conductive substrate with microwave irradiation. As a result, the inventors have found that a high short circuit current value can be realized.

  Hereinafter, although this invention and its component are demonstrated in detail, this invention is not limited.

[Porous n-type semiconductor electrode]
<Crystalline n-type semiconductor (core layer)>
The crystalline n-type semiconductor according to the present invention will be described.

  The material constituting the crystalline n-type semiconductor according to the present invention is appropriately selected from known materials mainly including metal oxides and metal sulfides. There is no particular limitation as long as it is a semiconductor that receives electrons generated by light irradiation from a dye adsorbed on a crystalline n-type semiconductor and transmits the electrons to a conductive substrate, and a metal oxide used in a known dye-sensitized solar cell As various metal oxide semiconductors such as titanium oxide, tin oxide, zirconium oxide, zinc oxide, vanadium oxide, niobium oxide, tantalum oxide, tungsten oxide, strontium titanate, calcium titanate, magnesium titanate, barium titanate, niobium Examples include various composite metal oxide semiconductors such as potassium oxide and strontium tantalate, and transition metal oxides such as magnesium oxide, strontium oxide, aluminum oxide, cobalt oxide, nickel oxide, and manganese oxide. In addition, metal sulfides such as cadmium sulfide and zinc sulfide, metal chalcogenites such as cadmium selenide, and the like are also included.

  In addition, these materials can be used in appropriate combination with the design of the semiconductor electrode. The average particle size of the crystalline n-type semiconductor particles in the core part is preferably 10 nm or more and 300 nm or less, and particularly preferably 10 nm or more and 200 nm or less. When the thickness is 10 nm or less, the pores of the semiconductor layer become small, so that the redox substance in the electrolyte solution cannot be sufficiently transferred, and a preferable short-circuit current may not be expected. When it is 300 nm or more, it is difficult to have a specific surface area sufficient for supporting the dye, and sufficient power generation efficiency may not be obtained due to light reflection on the surface.

  Further, the shape of the crystalline n-type semiconductor is not particularly limited, and may be a spherical, acicular or amorphous crystal.

  The method for forming a crystalline n-type semiconductor is not particularly limited, and various liquid phase methods such as hydrothermal reaction method, sol-gel method / gel sol method, colloid chemical synthesis method, coating pyrolysis method, spray pyrolysis method, and flame spraying. It can be formed using various gas phase methods such as a method, a plasma method, and a gas phase reaction method. Among these, a hydrothermal reaction method, a sol-gel method, a flame reaction method, or the like having a particle size of 100 nm or less and a uniform particle size distribution is preferably used.

  Although a specific preparation means is known, for example, a chemical flame can be formed by a burner in an atmosphere containing oxygen, which is usually used for manufacturing fine oxide particles, and a dust cloud can be formed from the metal powder in the chemical flame. A desired amount of oxide fine particles are obtained in the gas phase by a method of synthesizing 10 to 30 nm of oxide fine particles by injecting a quantity or by reaction of a raw material gas flow and oxygen gas as disclosed in JP-A-2005-218937. You can also.

  The crystalline n-type semiconductor may have a core-shell structure or may be doped with a different metal element, and a crystalline n-type semiconductor having an arbitrary structure and composition can be applied.

<Microwave absorption layer (shell layer)>
When the microwave absorption layer is placed in a microwave electric field, the dipole vibrates violently due to the microwave electric field, and the absorber itself is heated. Assuming that the angular frequency ω and the volume of the dielectric are V, the energy absorbed by the microwave absorption layer is given by the following equation.

  Here, the dielectric loss factor is expressed by the following equation, and changes according to temperature and frequency.

  Specific examples of the excellent dielectric loss factor are nickel, copper, manganese, molybdenum, chromium, bismuth, cobalt, iron, vanadium, tungsten, cerium, yttrium, calcium, strontium, holmium, ytterbium, samarium, Dysprosium and the like and compounds containing the element are preferable, and examples thereof include oxides, nitrides, chlorides, carbonates, and fluorides.

  When heating from room temperature to the temperature required for sintering, an excellent dielectric loss factor at room temperature is preferable. More specifically, manganese oxide, cerium oxide, bismuth oxide, cobalt oxide, chromium oxide, silicon carbide, barium titanate, etc. as materials that can absorb energy sufficient for sintering with a 2.45 GHz microwave heating device Is mentioned.

  Specific dielectric property measurement methods include the cavity resonator method, coaxial line method, and waveguide method. Among them, the coaxial line method is preferable because it can be measured simply by placing a sample in the probe. Used. In addition, the dielectric properties of various oxides (Fukushima Hideoki et al .: Japan Ceramic Society Autumn Symposium, 1992) etc. are summarized in the present invention using a network analyzer (Hewlett Packard, HP8753A) and a test set (Hewlett Packard, HP85044A). The dielectric properties were evaluated using this.

  As the dielectric loss factor of the shell layer, if the core dielectric loss factor at room temperature 2.45 GHz is Aε, and the core dielectric loss factor at 2.45 GHz is Bε, Bε / Aε is preferably 9.5 or more, more than 50 Is more preferable. When it is 9.5 or less, there is a possibility that the semiconductor electrode itself does not sufficiently absorb microwaves and sintering does not proceed. Further, when heating is performed by increasing the microwave output, the film substrate may be dissolved or damaged, which is not preferable.

  The thickness of the shell layer is preferably 20 nm or less, and more preferably 5 nm or less. If the shell layer is 20 nm or more, the injection of excited electrons into the core semiconductor is inhibited, and light absorption by the shell layer occurs, so that the photoelectric conversion efficiency may be reduced. Moreover, if a pyrolyzate of the shell layer is generated or fine powder is scattered during heating, the porous membrane may be damaged, or the sintering may be promoted excessively so that the porous property cannot be maintained.

  Although there is no particular designation as a covering form of the shell layer, it is sufficient that at least a part of the crystalline n-type semiconductor is covered. As a method for coating the shell layer, there are no problems with general known methods, but precipitation methods (coprecipitation method, chemical precipitation method), hydrolysis methods (salt aqueous solution method, alkoxide method, sol-gel method, etc.), hydrothermal method, etc. (Precipitation method, crystallization method, hydrothermal decomposition method, hydrothermal oxidation method, etc.), vapor phase method, plasma method, electroless plating method, solid phase method and the like. Among these, the chemical precipitation method and the vapor deposition method are preferable in terms of producing particles in which the shell layer is uniformly coated.

  In addition, the film thickness referred to here is an average film thickness converted from the shell layer volume, and when there is no shell layer removal step described later, a part of the core portion is used for dye adsorption or formation of a conductive path. It may be exposed.

<Porous n-type semiconductor electrode>
As a specific method for manufacturing a semiconductor electrode according to the present invention, (1) a colloidal solution in which a shell layer is formed on a crystalline n-type semiconductor is coated on a conductive substrate, dried, and then subjected to microwave irradiation. A method, (2) a method in which a crystalline n-type semiconductor to which a binder is added is sintered to produce a porous layer, a shell layer is produced, and microwave irradiation is applied.

  Among the above-described production methods, a known method can be applied particularly as a coating method, and examples thereof include a screen printing method, an ink jet method, a roll coating method, a doctor blade method, a spin coating method, and a spray coating method. Can do.

  The suspension containing the crystalline n-type semiconductor is prepared by dispersing the crystalline n-type semiconductor in a solvent, and the solvent is not particularly limited as long as the crystalline n-type semiconductor can be dispersed. , Water, organic solvents, and mixtures of water and organic solvents. 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 suspension as necessary. The concentration range of the metal oxide fine particles in the solvent is preferably 0.1 to 70% by mass, more preferably 0.1 to 30% by mass.

  The porosity of the semiconductor electrode in the present invention is preferably 0.1 to 20% by volume, and more preferably 5 to 20% by volume. The porosity of the semiconductor electrode 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 thickness of the semiconductor electrode is preferably at least 10 nm, and more preferably 100 to 10,000 nm.

<Microwave irradiation>
A suspension containing a crystalline n-type semiconductor having a microwave absorption layer obtained as described above is applied onto a conductive substrate, dried, etc., and then irradiated with microwaves to introduce a suspension. A semiconductor electrode is formed on the conductive substrate.

  The microwave irradiation apparatus used in the present invention can be applied from a relatively low frequency apparatus of 2.45 GHz to a high frequency apparatus of 28 GHz because the semiconductor electrode has a microwave absorption layer. When using low-frequency microwaves, use a well-known method such as installing a heat sink or a low-loss material that does not easily transmit microwaves in the vicinity of the microwave irradiated object in order to perform uniform heating. Can do.

  There is no specific designation as an atmosphere for irradiating microwaves, and there is no special designation such as an inert gas atmosphere such as N 2 or Ar, in the atmosphere, or a reducing gas such as Ar + H 2, but the semiconductor may be reduced in the reducing gas In addition, since it may take heating time even in an inert gas, the atmosphere is preferable.

<Surface treatment of shell layer>
After the microwave heat treatment, the shell layer is preferably surface-treated with an appropriate solution. Examples of the solution to be used include hydrochloric acid, sulfuric acid, acetic acid, nitric acid and the like in which the crystalline n-type semiconductor does not dissolve. Surface treatment of the shell layer is more preferable because it increases the amount of dye supported, has an effect of suppressing leakage to the electrolyte, and increases the short-circuit current value.

[Conductive substrate]
As the conductive substrate used in the present invention, when the conductive substrate side is the light receiving surface, the conductive substrate is preferably substantially transparent. “Substantially transparent” means that the light transmittance is 10% or more, preferably 50% or more, and particularly preferably 80% or more.

  As the conductive substrate, a substrate having conductivity by itself or a substrate having a conductive layer on the surface thereof can be used. In the latter case, it is possible to use a glass plate, a ceramic polishing plate such as titanium oxide or alumina as a base material, and a film substrate having a conductive layer by a known thermal spray pyrolysis method, In consideration of cost and plasticity, it is preferable to use a film substrate as a conductive base material.

  Specific examples of the film substrate include triacetyl cellulose (TAC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), syndiotactic polyester (SPS), polycarbonate (PC), Examples include polyarylate (PA), polyetherimide (PEI), polysulfone (PSF), polyethersulfone (PES), cyclic polyolefin, phenoxy resin, and brominated phenoxy.

  Examples of the conductive material used for the conductive layer provided on these substrates include inorganic conductive materials made of various known metals and metal oxides, polymer conductive materials, and inorganic / organic composite conductive materials. Or any material such as a conductive material in which these are arbitrarily mixed can be used.

  Specific examples of inorganic conductive materials include metals such as platinum, gold, silver, copper, zinc, titanium, aluminum, rhodium, and indium, conductive carbon, tin-doped indium oxide (ITO), tin oxide (SnO2), Examples thereof include metal oxides such as fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), and zinc oxide (ZnO 2).

  Specific examples of the polymer-based conductive material include conductive polymers obtained by polymerizing thiophene, pyrrole, furan, aniline, etc., which may or may not be variously substituted, and polyacetylene. From the viewpoint of high properties, polythiophene is preferable, and polyethylenedioxythiophene (PEDOT) is particularly preferable.

  As a method for forming the conductive layer on the substrate, a known appropriate method according to the conductive material can be used. For example, when forming a conductive layer made of a metal oxide such as ITO, a sputtering method is used. And thin film forming methods such as CVD, SPD (spray pyrolysis deposition), and vapor deposition. Further, when forming a conductive layer made of a polymer-based conductive material, it is preferably formed by various known coating methods.

  The thickness of the conductive layer is preferably about 0.01 to 10 μm, more preferably about 0.05 to 5 μm. As a conductive base material, the lower the surface resistance, the better. Specifically, it is preferably 50 Ω / cm 2 or less, more preferably 10 Ω / cm 2 or less.

  In addition, in order to improve the current collection efficiency of the conductive substrate and further increase the conductivity, the area ratio in a range that does not significantly impair the light transmittance, gold, silver, copper, platinum, aluminum, nickel, indium, titanium, A metal wiring layer made of tungsten or the like may be used in combination with the conductive layer. In the case of using a metal wiring layer, it is preferable that light is uniformly transmitted through the conductive substrate as a pattern such as a lattice shape, a stripe shape, or a comb shape. When using a metal wiring layer in combination, there is a method of installing the conductive layer on the substrate by vapor deposition, sputtering, etc., a method of applying and drying the metal nanowire, and a combination with a polymer-based conductive material Is also publicly applicable.

  In the present invention, it is intended to heat the semiconductor electrode itself, not the conductive base material, by microwave irradiation. Therefore, it is preferable to use a conductive base material using a film substrate.

(Short-circuit prevention layer)
In the dye-sensitized solar cell of the present invention, a short-circuit prevention layer can be provided between the conductive base material and the semiconductor electrode described above. Thereby, the short circuit current of electrolyte and a semiconductor can be reduced. In particular, when a solid p-type semiconductor is used as the electrolyte, it is preferable to have this layer.

  The short-circuit prevention layer is not particularly limited as long as it is an n-type semiconductor that is an insulating substance that transmits visible light and has a conduction band energy level close to that of a metal oxide semiconductor. For example, silicon oxide, magnesium oxide, aluminum oxide, calcium carbonate, polyvinyl alcohol, polyurethane and the like can be mentioned. Moreover, what is generally used for a photoelectric conversion material may be used, for example, titanium oxide, niobium oxide, tungsten oxide, etc. are mentioned.

  As a method for forming the short-circuit prevention layer, it can be produced by a vacuum film forming process, a liquid phase coating method, or the like, as in the case of the conductive layer. In the case of using a vacuum film formation process, the conductive layer, the short-circuit prevention layer, and the metal oxide film can be formed in-line under vacuum without opening to the atmosphere.

  The film thickness of the short-circuit prevention layer is preferably 0.001 to 0.02 μm, but can be adjusted as appropriate.

[Dye]
In the present invention, the dye adsorbed on the surface of the porous n-type semiconductor electrode described above has absorption in various visible light regions and / or infrared light regions, and has the lowest void higher than the conduction band of the metal oxide semiconductor. A dye having a level is preferable, and various known dyes can be used.

  For example, azo dyes, quinone dyes, quinone imine dyes, quinacridone dyes, squarylium dyes, cyanine dyes, cyanidin dyes, merocyanine dyes, triphenylmethane dyes, xanthene dyes, porphyrin dyes, perylene dyes And dyes, indigo dyes, phthalocyanine dyes, naphthalocyanine dyes, rhodamine dyes, and the like.

  Metal complex dyes are also preferably used. In this case, Cu, Ni, Fe, Co, V, Sn, Si, Ti, Ge, Cr, Zn, Ru, Mg, Al, Pb, Mn, In, Mo Y, Zr, Nb, Sb, La, W, Pt, Ta, Ir, Pd, Os, Ga, Tb, Eu, Rb, Bi, Se, As, Sc, Ag, Cd, Hf, Re, Au, Ac Various metals such as Tc, Te, and Rh can be used.

  Of the above, polymethine dyes such as cyanine dyes, merocyanine dyes, and squarylium dyes are one of the preferred embodiments. Specifically, JP-A Nos. 11-35836, 11-67285, 11-86916, 11-97725, 11-158395, 11-163378, 11-214730, 11-214731, 11-238905, JP-A-2004-207224, and 2004-319202 And dyes described in the specifications of European Patent Nos. 892,411 and 911,841.

  Furthermore, a metal complex dye is one of the preferred embodiments, and a metal phthalocyanine dye, a metal porphyrin dye or a ruthenium complex dye is preferable, and a ruthenium complex dye is more preferable. Examples of ruthenium complex dyes include U.S. Pat. Nos. 4,927,721, 4,684,537, 5,084,365, 5,350,644, 5,463,057, Nos. 5,525,440, JP-A-7-249790, JP-T-10-504512, WO98 / 50393, JP2000-26487, 2001-2223037 And complex dyes described in JP-A Nos. 2001-226607 and 3430254.

  The above-mentioned compound according to the present invention is, for example, “Cyanine Soybean and Related Compounds” (1964, published by Inter Science Publishers) by F. M. Hammer, US Pat. No. 2,454,629, It can be synthesized with reference to the methods described in the specifications of JP-A-2,493,748, JP-A-6-301136, JP-A-2003-203684, and the like.

  These dyes preferably have a large extinction coefficient and are stable against repeated redox. The dye is preferably chemically adsorbed on the metal oxide semiconductor and has a functional group such as a carboxyl group, a sulfonic acid group, a phosphoric acid group, an amide group, an amino group, a carbonyl group, or a phosphine group. preferable.

  In addition, two or more kinds of dyes can be used in combination or mixed in order to widen the wavelength range of photoelectric conversion as much as possible and increase the conversion efficiency. In this case, the dye to be used or mixed and the ratio thereof can be selected so as to match the wavelength range and intensity distribution of the target light source.

  In the present invention, the method for adsorbing the dye to the semiconductor electrode is not particularly limited, and a known method can be used. For example, a method of dissolving a dye in an organic solvent to prepare a dye solution and immersing the semiconductor layer on the transparent conductive film in the obtained dye solution, or a method of applying the obtained dye solution to the surface of the semiconductor layer, etc. Can be mentioned.

  In the former, a dip method, a roller method, an air knife method or the like can be applied, and in the latter, a wire bar method, an application method, a spin method, a spray method, an offset printing method, a screen printing method, or the like can be applied. Prior to the adsorption of the dye, the semiconductor layer surface may be subjected to a treatment such as decompression treatment or heat treatment in advance to activate the surface and remove bubbles in the film.

  From the viewpoint of preferably obtaining a sensitizing effect on the semiconductor layer, the time for immersing the semiconductor film in the dye solution is preferably 3 to 48 hours, and more preferably 4 to 24 hours.

  In addition, the dye solution may be heated to a temperature that does not boil as long as the dye is not decomposed. The preferred temperature range is 10 to 50 ° C., particularly preferably 15 to 35 ° C., but this is not the case when the solvent boils in the temperature range as described above.

  In addition, the dye solution in which the semiconductor film is immersed can be irradiated with ultrasonic waves. A commercially available apparatus can be used for the ultrasonic irradiation, and the irradiation time is preferably 30 minutes to 4 hours, and more preferably 1 to 3 hours.

  The solvent used in the dye solution may be any solvent that dissolves the dye, and a conventionally known solvent can be used. In addition, the solvent is preferably a solvent purified in accordance with a conventional method, or prior to use of the solvent, distilled and / or dried as necessary, and a higher purity solvent, for example, methanol, ethanol, Butanol, one or more hydrophobic solvents, aprotic solvents, hydrophobic and aprotic solvents or mixtures thereof.

  Here, examples of the hydrophobic solvent include halogenated aliphatic hydrocarbons such as methylene chloride, chloroform and carbon tetrachloride; hydrocarbons such as hexane and cyclohexane; aromatic hydrocarbons such as benzene, toluene and xylene; chlorobenzene, And halogenated aromatic hydrocarbons such as dichlorobenzene; esters such as ethyl acetate, butyl acetate, and ethyl benzoate;

  Examples of the aprotic solvent include ketones such as acetone and methyl ethyl ketone; ethers such as diethyl ether, diisopropyl ether and dimethoxyethane; nitrogen compounds such as acetonitrile, dimethylacetamide and hexamethylphosphoric triamide; carbon disulfide; Sulfur compounds such as dimethyl sulfoxide; phosphorus compounds such as hexamethylphosphoramide; and combinations thereof.

  Solvents preferably used include alcohol solvents such as methanol, ethanol, n-propanol and butanol, ketone solvents such as acetone and methyl ethyl ketone, ether solvents such as diethyl ether, diisopropyl ether, tetrahydrofuran and 1,4-dioxane, methylene chloride. 1,1,2-trichloroethane and the like, particularly preferably methanol, ethanol, acetone, methyl ethyl ketone, tetrahydrofuran and methylene chloride.

  The density | concentration of the pigment | dye in a pigment | dye solution can be suitably adjusted with the pigment | dye to be used, the kind of solvent, and a pigment | dye adsorption process, for example, 1x10-5 mol / L or more, Preferably it is 5x10-5-1x10. -2 mol / L.

  Note that if the adsorption amount of the dye is small, the sensitization effect becomes insufficient. Conversely, if the adsorption amount is large, the dye that is not adsorbed on the oxide semiconductor floats, which reduces the sensitization effect and reduces the photoelectric conversion efficiency. This is not preferable because it causes a decrease. From the above, it is preferable to quickly remove the unadsorbed dye by washing.

  As the cleaning solvent, a solvent such as acetone, which has a relatively low solubility of the dye and is relatively easy to dry, is preferable. Moreover, it is preferable to perform washing in a heated state. In addition, after removing excess dye by washing, the surface of the oxide semiconductor fine particles may be treated with an organic basic compound to promote removal of unreacted dye in order to make the adsorption state of the dye more stable. Good. Examples of the organic basic compound include derivatives such as pyridine and quinoline. When these compounds are liquid, they may be used as they are, but when they are solid, they may be dissolved in a solvent, preferably the same solvent as the dye solution.

  When two or more kinds of dyes are used, the ratio of the dyes to be mixed is not particularly limited, and is selected and optimized based on the respective dyes. Generally, from about equimolar mixing, about 10% mol or more per dye. It is preferred to use.

  As a specific method when two or more dyes are used in combination, they may be mixed and dissolved to be adsorbed, or the dyes may be adsorbed to the semiconductor layer sequentially. When the dye is adsorbed to the oxide semiconductor layer using a solution in which the dye to be used in combination is mixed and dissolved, the total concentration of the dye in the solution may be the same as when only one kind is supported. As a solvent in the case of using a mixture of dyes, the above-mentioned solvents can be used. Even when a solution is prepared for each dye to be used in combination and adsorbed to the semiconductor layer, the solvent described above can be used as the solvent, and the solvent for each dye to be used may be the same or different.

  In the case where a separate solution is prepared for each dye and is prepared by immersing in each solution in order, the effect of the present invention can be obtained regardless of the order in which the dye is adsorbed on the semiconductor layer. Moreover, you may produce by mixing the semiconductor fine particle which adsorb | sucked each pigment | dye independently.

  When the dye is supported on the thin film of oxide semiconductor fine particles, it is effective to support the dye in the coexistence of the inclusion compound in order to prevent association between the dyes. Examples of inclusion compounds include steroidal compounds such as cholic acid, crown ether, cyclodextrin, calixarene, polyethylene oxide, and the like. Deoxycholic acid, dehydrodeoxycholic acid, chenodeoxycholic acid, methyl cholate are preferable. Examples include esters, cholic acids such as sodium cholate, polyethylene oxide, and the like.

  Further, after the dye is supported, the surface of the semiconductor layer may be treated with an amine compound such as 4-t-butylpyridine. The treatment method may be, for example, a method of immersing a substrate provided with a semiconductor fine particle thin film carrying a dye in an ethanol solution of amine.

(Charge transfer layer)
The charge transfer layer is a layer containing a charge transport material having a function of replenishing electrons to the oxidant of the dye. Examples of typical charge transport materials that can be used in the present invention include a solvent in which a redox counter ion is dissolved, an electrolytic solution such as a room temperature molten salt containing the redox counter ion, and a solution of the redox counter ion as a polymer. Examples thereof include a gel-like quasi-solidified electrolyte impregnated with a matrix, a low-molecular gelling agent, and the like, and a polymer solid electrolyte.

  In addition to charge transport materials that involve ions, electron transport materials and hole transport materials can also be used as materials whose carrier transport in solids is involved in electrical conduction, and these can be used in combination. Is possible.

  When using an electrolytic solution for the charge transfer layer, the redox counter ion to be contained is not particularly limited as long as it can be used in a generally known solar cell or the like.

  Specifically, those containing an oxidation-reduction counter ion such as I- / I3-type, Br2- / Br3-type, ferrocyanate / ferricyanate, ferrocene / ferricinium ion, cobalt complex, etc. Examples thereof include metal redox systems such as metal complexes, organic redox systems such as alkylthiol-alkyldisulfides, viologen dyes, hydroquinones / quinones, and sulfur compounds such as sodium polysulfide and alkylthiols / alkyldisulfides.

  More specifically, the iodine system includes a combination of iodine and a metal iodide such as LiI, NaI, KI, CsI, and CaI2, quaternary ammonium compounds such as tetraalkylammonium iodide, pyridinium iodide, imidazolium iodide, The combination with the iodine salt of a quaternary imidazolium compound, etc. are mentioned.

  More specifically, examples of bromine include combinations of bromine with metal bromides such as LiBr, NaBr, KBr, CsBr, and CaBr2, and combinations with bromine salts of quaternary ammonium compounds such as tetraalkylammonium bromide and pyridinium bromide. It is done.

  As a solvent, it is an electrochemically inert compound that has low viscosity and improved ion mobility, or has a high dielectric constant and improved effective carrier concentration, and can exhibit excellent ionic conductivity. Is desirable.

  Specifically, carbonate compounds such as dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, heterocyclic compounds such as 3-methyl-2-oxazolidinone, ether compounds such as dioxane, diethyl ether, ethylene glycol dialkyl ether, propylene glycol dialkyl Ethers, chain ethers such as polyethylene glycol dialkyl ether, polypropylene glycol dialkyl ether, alcohols such as methanol, ethanol, ethylene glycol monoalkyl ether, propylene glycol monoalkyl ether, polyethylene glycol monoalkyl ether, polypropylene glycol monoalkyl ether, Ethylene glycol, diethylene glycol, triethylene Polyhydric alcohols such as glycol, polyethylene glycol, propylene glycol, polypropylene glycol, glycerin, nitrile compounds such as acetonitrile, glutaronitrile, propionitrile, methoxypropionitrile, methoxyacetonitrile, benzonitrile, tetrahydrofuran, dimethyl sulfoxide, An aprotic polar substance such as sulfolane can be used.

  A preferable electrolyte concentration is 0.1 to 15M, and more preferably 0.2 to 10M. Moreover, the preferable addition density | concentration of an iodine when using an iodine type is 0.01-0.5M.

  The molten salt electrolyte is preferable from the viewpoint of achieving both photoelectric conversion efficiency and durability. Examples of the molten salt electrolyte include International Publication No. 95/18456, JP-A-8-259543, JP-A-2001-357896, Electrochemistry, Vol. 65, No. 11, page 923 (1997). And electrolytes containing known iodine salts such as pyridinium salts, imidazolium salts, and triazolium salts described in the above. These molten salt electrolytes are preferably in a molten state at room temperature, and it is preferable not to use a solvent.

  Gels obtained by adding an electrolyte or electrolyte solution to an oligomer or polymer matrix, adding polymers, adding low-molecular gelling agents or oil gelling agents, polymerization containing polyfunctional monomers, polymer cross-linking reactions, etc. (Pseudo-solidification) can also be used.

  In the case of gelation by adding a polymer, polyacrylonitrile and polyvinylidene fluoride can be preferably used. In the case of gelation by adding an oil gelling agent, a preferred compound is a compound having an amide structure in the molecular structure.

  When the electrolyte is gelled by a polymer crosslinking reaction, it is desirable to use a polymer containing a crosslinkable reactive group and a crosslinking agent in combination. In this case, a preferable crosslinkable reactive group is a nitrogen-containing heterocyclic ring (for example, a pyridine ring, an imidazole ring, a thiazole ring, an oxazole ring, a triazole ring, a morpholine ring, a piperidine ring, a piperazine ring, etc.), and a preferable crosslinking agent is Bifunctional or higher reagent capable of electrophilic reaction with nitrogen atom (for example, alkyl halide, halogenated aralkyl, sulfonic acid ester, acid anhydride, acid chloride, isocyanate, etc.). The concentration of the electrolyte is usually 0.01 to 99% by mass, preferably about 0.1 to 90% by mass.

  Further, as the gel electrolyte, an electrolyte composition containing an electrolyte and metal oxide particles and / or conductive particles can also be used. The metal oxide particles are selected from the group consisting of TiO2, SnO2, WO3, ZnO, ITO, BaTiO3, Nb2O5, In2O3, ZrO2, Ta2O5, La2O3, SrTiO3, Y2O3, Ho2O3, Bi2O3, CeO2, and Al2O3. The mixture of 2 or more types is mentioned. These may be doped with impurities or complex oxides. Examples of the conductive particles include those made of a substance mainly composed of carbon.

  Next, the polyelectrolyte is a solid substance capable of dissolving the redox species or binding with at least one substance constituting the redox species, for example, polyethylene oxide, polypropylene oxide, polyethylene succinate, A polymer compound such as poly-β-propiolactone, polyethyleneimine, polyalkylene sulfide, or a cross-linked product thereof, polyphosphazene, polysiloxane, polyvinyl alcohol, polyacrylic acid, polyalkylene oxide, Examples include those obtained by adding an ether segment or oligoalkylene oxide structure as a side chain, or a copolymer thereof. Among them, those having an oligoalkylene oxide structure as a side chain or having a polyether segment as a side chain. It is preferred.

  In order to contain the redox species in the solid, for example, a method of polymerizing in the coexistence of a monomer that becomes a polymer compound and a redox species, a solid such as a polymer compound is dissolved in a solvent as necessary. Then, the above-mentioned method of adding the redox species can be used. The content of the redox species can be appropriately selected according to the required ion conduction performance.

  In the present invention, instead of an ion conductive electrolyte such as a molten salt, a solid hole transport material that is organic or inorganic or a combination of both can be used.

  Organic hole transport materials include aromatic amines and triphenylene derivatives, polyacetylene and its derivatives, poly (p-phenylene) and its derivatives, poly (p-phenylene vinylene) and its derivatives, polythienylene vinylene and its Conductive polymers such as derivatives, polythiophene and derivatives thereof, polyaniline and derivatives thereof, polytoluidine and derivatives thereof can be preferably used.

  In order to control the dopant level, the hole transport material may be added with a compound containing a cation radical such as tris (4-bromophenyl) aminium hexachloroantimonate, or the potential of the oxide semiconductor surface may be controlled. In order to perform (space charge layer compensation), a salt such as Li [(CF3SO2) 2N] may be added.

  A p-type inorganic compound semiconductor can be used as the inorganic hole transport material. The p-type inorganic compound semiconductor for this purpose preferably has a band gap of 2 eV or more, and more preferably 2.5 eV or more.

  Also, the ionization potential of the p-type inorganic compound semiconductor needs to be smaller than the ionization potential of the dye-adsorbing electrode from the condition that the holes of the dye can be reduced. Although the preferable range of the ionization potential of the p-type inorganic compound semiconductor varies depending on the dye used, it is generally preferably 4.5 to 5.5 eV, and more preferably 4.7 to 5.3 eV.

  A preferred p-type inorganic compound semiconductor is a compound semiconductor containing monovalent copper, preferably CuI and CuSCN, and most preferably CuI. The preferred hole mobility of the charge transfer layer containing the p-type inorganic compound semiconductor is 10 −4 to 104 m 2 / V · sec, more preferably 10 −3 to 103 cm 2 / V · sec. The preferred conductivity of the charge transport layer is 10-8 to 102 S / cm, more preferably 10-6 to 10 S / cm.

  In the present invention, the method for forming the charge transfer layer between the semiconductor electrode and the counter electrode is not particularly limited. For example, after the semiconductor electrode and the counter electrode are arranged to face each other, between the both electrodes The charge transfer layer is formed by filling the electrolyte solution or various electrolytes described above to form a charge transfer layer, or by dropping or coating the electrolyte or various electrolytes on the semiconductor electrode or the counter electrode. A method of overlaying the other electrode on the top can be used.

  Also, in order to prevent electrolyte from leaking between the semiconductor electrode and the counter electrode, the gap between the semiconductor electrode and the counter electrode is sealed with a film or resin as necessary, or the semiconductor electrode and the charge transfer It is also preferable to store the layer and the counter electrode in a suitable case.

  In the case of the former forming method, as a method for filling the charge transfer layer, a normal pressure process using capillary action by dipping or the like, or a vacuum process in which the gas phase in the gap is replaced with a liquid phase at a pressure lower than normal pressure can be used. .

  In the latter forming method, microgravure coating, dip coating, screen coating, spin coating or the like can be used as a coating method. In the wet charge transfer layer, the counter electrode is provided in an undried state and measures for preventing liquid leakage at the edge portion are taken. In the case of a gel electrolyte, there is a method in which it is applied in a wet manner and solidified by a method such as polymerization. In that case, a counter electrode can be applied after drying and fixing.

  In the case of a solid electrolyte or a solid hole transport material, a charge transfer layer can be formed by a dry film forming process such as a vacuum deposition method or a CVD method, and then a counter electrode can be provided. Specifically, it can be introduced into the electrode by techniques such as vacuum deposition, casting, coating, spin coating, dipping, electropolymerization, and photoelectropolymerization. It is formed by evaporating the solvent by heating to an arbitrary temperature.

  The thickness of the charge transfer layer is preferably 10 μm or less, more preferably 5 μm or less, and further preferably 1 μm or less. The conductivity of the charge transfer layer is preferably 1 × 10 −10 S / cm or more, and more preferably 1 × 10 −5 S / cm or more.

[Counter electrode]
As the counter electrode that can be used in the present invention, a single-layer structure of a base material having conductivity as in the case of the conductive base material described above, or a base material having a counter electrode conductive layer on the surface thereof can be used. In the latter case, the conductive material and the base material used for the counter electrode conductive layer, and the manufacturing method thereof are the same as those of the conductive base material described above, and various known materials and methods can be applied.

  Among them, it is preferable to use one having a catalytic ability that allows oxidation of I3- ions or other redox ions to be performed at a sufficiently high rate. Specifically, the surface of the platinum electrode or conductive material is white. Examples thereof include those plated with gold or platinum, rhodium metal, ruthenium metal, ruthenium oxide, and carbon.

  In addition, considering cost and flexibility as described above, using a plastic sheet as a base material and applying a polymer material as a conductive material is also one of preferred embodiments.

  The thickness of the counter electrode conductive layer is not particularly limited, but is preferably 3 nm to 10 μm. When the counter electrode conductive layer is a metal, the thickness is preferably 5 μm or less, and more preferably in the range of 10 nm to 3 μm. The surface resistance of the counter electrode is preferably as low as possible. Specifically, the range of the surface resistance is preferably 50Ω / □ or less, more preferably 20Ω / □ or less, still more preferably 10Ω / □ or less. .

  Since light may be received from one or both of the conductive base material and the counter electrode described above, it is sufficient that at least one of the conductive base material and the counter electrode is substantially transparent. From the viewpoint of improving the power generation efficiency, it is preferable to make the conductive base material transparent so that light is incident from the conductive base material side. In this case, the counter electrode preferably has a property of reflecting light. As such a counter electrode, glass or plastic deposited with a metal or a conductive oxide, or a metal thin film can be used.

  The counter electrode can be applied by directly applying, plating or vapor-depositing (PVD, CVD) a conductive material on the above-described charge transfer layer, or by adhering the conductive layer side of a substrate having a counter electrode conductive layer or a conductive substrate single layer. That's fine. In addition, as in the case of the conductive base material, it is also a preferable aspect to use a metal wiring layer in combination when the counter electrode is transparent.

  The counter electrode is preferably conductive and has a catalytic action on the reduction reaction of the redox electrolyte. For example, glass, a polymer film deposited with platinum, carbon, rhodium, ruthenium or the like, or coated with conductive fine particles can be used.

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

Example 1
[Preparation of dye-sensitized solar cell sealing cell SC-01]
<< Preparation of porous semiconductor film layer >>
As the porous semiconductor film layer, a paste containing semiconductor fine particles was applied on a conductive substrate and dried, and then a microwave absorption layer was formed by a chemical precipitation method. Each prepared below.

(Preparation of semiconductor fine particle dispersion paste 1)
Paste formulation Gas phase method Titania (Degussa P25, primary particle size 21nm, BET value 50m2 / g)
12% by mass
Titanium oxide sol (NTB-1 from Showa Denko) 3% by mass
Activator (Kao, Emulgen 120) 1% by mass
Ethanol 63 mass%
21% by mass of pure water
After preparing a dispersion containing twice the amount of ethanol from the above formulation and continuously dispersing for 30 minutes using an ultrasonic disperser UH-300 made by SMT, using Ultra Apex Mill / 50 μm diameter zirconia beads made by Kotobuki Industries The pulverization and dispersion treatment was performed at a rotation speed of 10 m / sec for 3 hours, and then concentrated using a rotary evaporator until the gas phase titania was 12 mass% to prepare a semiconductor fine particle dispersion paste.

  Then, it apply | coated by the screen printing method on the conductive film board | substrate (PECF-IP ITO-PEN) made from Peccell, and it dried at 80 degreeC, and formed the porous semiconductor film layer.

<Formation of microwave absorption layer>
The film substrate on which the porous semiconductor film layer was formed was impregnated in an aqueous solution prepared to 0.01 mol / L of manganese (II) chloride tetrahydrate and 0.005 mol / L of sodium bromate, and the mixture was impregnated at 60 ° C. for 2 hours. Retained. It was confirmed by TEM observation, XRD analysis, and ICP analysis that 49% by volume of a 5 nm manganese dioxide layer was deposited on the surface of the porous semiconductor film layer with respect to the core layer.

<Microwave irradiation>
In order to avoid local heating on the aluminum plate as a heat sink with respect to the porous n-type semiconductor electrode, an alumina plate is sequentially laminated as a low-loss body, and an alumina plate using a microwave irradiation device (μreactor manufactured by Shikoku Measurement) To 30 seconds of microwave irradiation at a frequency of 2.45 GHz and an output of 400 W.

<Surface treatment of shell layer>
After irradiation, it was washed in a 0.1 mol / L hydrochloric acid solution, washed with pure water, and dried to prepare a porous semiconductor film layer from which the microwave absorption layer was removed.

(Production of dye-sensitized solar cell)
The periphery of the porous semiconductor film is scraped to 5 mm × 5 mm (effective area 0.25 cm 2), then 3.0 × 10 −3 mol / L of ruthenium complex dye N719 for dye-sensitized solar cell, acetonitrile : Porous semiconductor film immersed in a solution of t-butanol = 1: 1 for 12 hours, adsorbing the dye, then thoroughly washing away the excess dye with the acetonitrile: t-butanol solution, and vacuum drying to adsorb the dye A layer was made.

  As a counter electrode, a hole for vacuum-depositing platinum on a glass substrate and injecting an electrolyte was provided. The porous semiconductor film layer and the counter electrode were bonded to each other using a 25 μm thick sheet-like spacer / sealing material (SX-1170-25 manufactured by SOLARONIX) having a 6.5 mm square hole, and provided on the counter electrode. From the electrolyte injection hole, dimethylpropylammonium iodide, iodine, t-butylpyridine, and lithium iodide are added to an acetonitrile solvent having a volume ratio of 1: 4 at concentrations of 0.6 mol / L and 0.05 mol / L, respectively. Then, a charge transfer layer containing a redox electrolyte dissolved so as to be 0.05 mol / L and 0.1 mol / L is injected, the hole is closed with a hot bond, and a cover glass is pasted from above using the sealant. Sealed.

  An anti-reflection film (Konica Minolta Op hard coat / anti-reflection type cellulose film) is laminated on the light-receiving surface side of the Peccell conductive film substrate (PECF-IP ITO-PEN), and a dye-sensitized solar cell sealing cell SC-01 was produced.

[Preparation of dye-sensitized solar cell sealing cell SC-02]
A dye-sensitized solar cell encapsulated cell SC-02 was produced in the same manner as the dye-sensitized solar cell encapsulated cell SC-01 except that the microwave absorbing layer was formed as described below.

<Formation of microwave absorption layer>
The film substrate on which the porous semiconductor film layer is formed is impregnated in an aqueous solution prepared with manganese (II) chloride tetrahydrate 0.01 mol / L and sodium bromate 0.005 mol / L and held at 90 ° C. for 10 hours. did. By TEM observation and XRD analysis, it was confirmed that a manganese dioxide layer having a thickness of 10 nm was deposited on the surface of the porous semiconductor film layer by 220% by volume with respect to the core layer.

[Preparation of dye-sensitized solar cell sealing cell SC-03]
A dye-sensitized solar cell encapsulated cell SC-03 was produced in the same manner as the dye-sensitized solar cell encapsulated cell SC-01 except that the microwave irradiation was performed as follows.

<Microwave irradiation>
The porous n-type semiconductor electrode was irradiated with 2.45 GHz, 200 W, 30 sec using a microwave irradiation apparatus (μreactor manufactured by Shikoku Measurement).

[Preparation of dye-sensitized solar cell sealing cell SC-04]
A dye-sensitized solar cell encapsulated cell SC-04 was produced in the same manner as the dye-sensitized solar cell encapsulated cell SC-01 except that the microwave irradiation was performed as follows.

<Microwave irradiation>
The porous n-type semiconductor electrode was irradiated with 2.45 GHz, 100 W, 30 sec using a microwave irradiation device (μreactor manufactured by Shikoku Measurement).

[Preparation of dye-sensitized solar cell sealing cell SC-05]
Dye sensitization was performed in the same manner as dye-sensitized solar cell sealed cell SC-01 except that the microwave absorption layer was formed as described below and the surface treatment of the microwave absorption layer (shell layer) was not performed. Type solar cell encapsulated cell SC-05 was produced.

<Formation of microwave absorption layer>
The film substrate on which the porous semiconductor film layer was formed was impregnated in an aqueous solution prepared with 0.01 mol / L of cerium (III) acetate and 0.1 mol / L of potassium chlorate, and held at 60 ° C. for 2 hours. TEM observation and XRD analysis confirmed that 192% by volume of 20 nm cerium dioxide fine particles were deposited on the surface of the porous semiconductor film layer with respect to the core layer.

[Preparation of dye-sensitized solar cell sealed cell SC-06]
In the production of the dye-sensitized solar cell sealing cell SC-01, as a semiconductor fine particle dispersion paste, 15 mass% of niobium hydroxide and oxalic acid dihydrate were used instead of 12 parts by mass of gas phase method titania and 3 parts by mass of titania sol. A dye-sensitized solar cell encapsulated cell SC-06 was similarly produced except that niobium oxide (50 nm) produced by mixing 45 parts by mass and hydrothermally treating was used.

[Preparation of dye-sensitized solar cell sealing cell SC-07]
After vapor-depositing bismuth on vapor phase titania (Degussa P25, primary particle size 21 nm, BET value 50 m2 / g), firing in the atmosphere to form a bismuth oxide layer (2.5 nm) as a shell layer did.

[Preparation of dye-sensitized solar cell sealing cell SC-08]
A dye-sensitized solar cell encapsulated cell SC-08 was produced in the same manner as the dye-sensitized solar cell encapsulated cell SC-01 except that the porous semiconductor film layer was produced as follows.

<< Preparation of porous semiconductor film layer >>
The porous semiconductor film layer is made by bead mill dispersion of a paste containing a semiconductor fine particle having a large particle size and a microwave absorption layer having a small particle size, and core-shell particles carrying the microwave absorption layer (51 nm) on the semiconductor fine particles. Produced. Each was prepared below.

[Preparation of semiconductor fine particle dispersed paste 7]
Paste formulation Titanium oxide (TITANIX JA-1 180 nm, manufactured by Teika) 13% by mass
Bismuth oxide (51 nm manufactured by C.I. Kasei) 2% by mass
Activator (Kao, Emulgen 120) 1% by mass
Ethanol 63 mass%
21% by mass of pure water
After preparing a dispersion containing twice the amount of ethanol from the above formulation and continuously dispersing for 30 minutes using an ultrasonic disperser UH-300 made by SMT, using Ultra Apex Mill / 50 μm diameter zirconia beads made by Kotobuki Industries The pulverization and dispersion treatment was performed at a rotation speed of 10 m / sec for 3 hours, and then the titanium oxide was concentrated to 13% by mass using a rotary evaporator to prepare a semiconductor fine particle dispersion paste.

  Then, it apply | coated by the screen printing method on the conductive film board | substrate (PECF-IP ITO-PEN) made from Peccell, and it dried at 80 degreeC, and formed the porous semiconductor film layer.

[Preparation of dye-sensitized solar cell sealing cell SC-09]
In preparing the dye-sensitized solar cell sealing cell SC-01, a dye-sensitized solar cell sealing cell SC-09 was manufactured in the same manner except that the microwave absorption layer was not manufactured.

[Production of Dye-Sensitized Solar Cell Sealed Cell SC-10]
In preparing the dye-sensitized solar cell sealing cell SC-04, a dye-sensitized solar cell sealing cell SC-10 was manufactured in the same manner except that the microwave absorbing layer was not manufactured.

[Production of Dye-Sensitized Solar Cell Sealed Cell SC-11]
Dye-sensitized solar cell encapsulated cell SC-11 was produced in the same manner as in production of dye-sensitized solar cell encapsulated cell SC-06, except that the microwave absorption layer was not produced.

<< Evaluation of photoelectric conversion characteristics of solar cells >>
The solar cell produced by the above method is measured for IV characteristics when irradiated with light of an AM 1.5 filter and an intensity of 100 mW / m 2 by a solar simulator (manufactured by JASCO, low energy spectral sensitivity measuring device CEP-25). Then, three short circuit currents Jsc (mA / cm 2) and open circuit voltage value Voc (V) were evaluated with the same configuration and manufacturing method, and the average values are shown in Table 1. Further, the photoelectric conversion efficiency η (%) was obtained from Jsc, Voc and FF (fill factor, form factor) and is also shown in Table 1.

  From Table 1, it was possible to uniformly heat the porous n-type semiconductor electrode by microwave irradiation by implementing the present invention, and as a result, the photoelectric conversion efficiency could be improved.

  Specifically, in SC-01, 04 with respect to SC-09 and 10 of the comparative example, the porous n-type semiconductor electrode can be efficiently heated by performing the same microwave irradiation, and the short circuit current Improvements in value and fill factor were confirmed.

  In SC-05 and SC-08, a slight increase in the open-circuit voltage and the short-circuit current value was observed even when the surface treatment of the shell layer was not performed. Moreover, it is shown from the comparison between SC-06 and SC-11 that similar effects are exhibited when niobium oxide is used as the core.

It is a schematic sectional drawing which shows an example of the basic structure of the dye-sensitized solar cell of this invention. It is an example of the schematic diagram of the microwave irradiation apparatus in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive base material 11 Substrate 12 Conductive layer 2 Porous n-type semiconductor electrode 21 Microwave absorption layer 22 N-type crystalline semiconductor 3 Dye 4 Charge transfer layer 5 Counter electrode 51 Substrate 52 Counter electrode conductive layer 61 Microwave generating means 7 Low Loss body 8 Heat sink

Claims (6)

In a method for producing a dye-sensitized solar cell, in which a porous n-type semiconductor electrode carrying a dye, a charge transport layer, and a counter electrode are sequentially laminated on a conductive substrate, the porous n-type semiconductor electrode Is a porous semiconductor film comprising at least a core layer having a crystalline n-type semiconductor and a shell layer having a microwave absorption layer on the surface, and is produced by irradiating the porous semiconductor film with microwaves. A method for producing a dye-sensitized solar cell. The method for producing a dye-sensitized solar cell according to claim 1, wherein after the microwave irradiation, the surface of the shell layer is further treated with hydrochloric acid, sulfuric acid, acetic acid or nitric acid. The method for producing a dye-sensitized solar cell according to claim 1, wherein the conductive base material is a film substrate. The method for manufacturing a dye-sensitized solar cell according to any one of claims 1 to 3, wherein the shell layer is made of manganese oxide, bismuth oxide, or cobalt oxide. The method for producing a dye-sensitized solar cell according to any one of claims 1 to 4, wherein the thickness of the shell layer is 20 nm or less. A dye-sensitized solar cell produced by the method for producing a dye-sensitized solar cell according to any one of claims 1 to 5.

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