JP2007073346A - Dye-sensitized solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dye-sensitized solar cell of which inverse electron movement is easily and effectively prevented at a low cost by using an industrial method. <P>SOLUTION: The dye-sensitized solar cell comprises: a transparent substrate with a surface on which a transparent electrically conductive film is formed; a porous semiconductor layer which is dye-sensitized; a carrier transporting layer, and a counter electrode, which are laminated in this order. An inverse electron movement prevention layer consisting of a titanium oxide thin film is formed between the transparent electrically conductive film and the porous semiconductor layer, wherein the titanium oxide thin film is made from titanium oxide dispersion solution obtained from titanium oxide precursor which can exist stably also in water. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a dye-sensitized solar cell, and more particularly to a dye-sensitized solar cell that can effectively prevent so-called reverse electron transfer industrially at low cost.

  In recent years, solar cells using sunlight have attracted attention. In particular, as shown in FIG. 1, FTO (fluorine dove tin oxide) transparent conductive thin film and dye are sensitized between transparent glass substrates. It has a structure in which a carrier transport layer (viscous gel electrolyte) including a porous semiconductor layer, a counter electrode (platinum thin film), and an FTO thin film are arranged. However, as shown in FIG. 1, this structure has a problem in that electron movement (short circuit) in the reverse direction occurs in addition to the regular electron movement shown in FIG. Therefore, for example, as shown in FIG. 2, a reverse electron transfer preventing layer for preventing reverse electron transfer is provided.

Conventionally, as a reverse electron transfer prevention layer, for example, after applying a metal oxide dispersion prepared by hydrolyzing a metal alkoxide (for example, an organic titanium compound such as titanium tetraisopropoxide) on a transparent conductive glass electrode, It has been proposed to prepare by repeating the operation of sintering at 450 ° C. or higher several times (see Patent Document 1 and Patent Document 2). However, metal alkoxides are expensive and have a problem that they are chemically unstable and difficult to handle. In addition, the metal oxide dispersion prepared by hydrolyzing the metal alkoxide in this way does not necessarily have good storage stability, and the reproducibility of the performance of the dye-sensitized solar cell having the reverse electron transfer prevention layer. There was a risk of problems. Moreover, when the reverse electron transfer preventing layer is prepared from a metal alkoxide, the kind of the metal alkoxide is limited, which is not always satisfactory in practical use.
Further, in order to use a metal oxide dispersion prepared by hydrolyzing the metal alkoxide (for example, titanium tetraisopropoxide) as a short-circuit prevention layer, the prepared metal oxide dispersion is used as a transparent conductive substrate. Heat treatment at 350 ° C. or higher is necessary after coating on the conductive film. Therefore, when the metal oxide dispersion is used as a short-circuit prevention layer, the transparent conductive substrate constituting the solar cell is limited to a heat-resistant glass substrate or the like, and the transparent conductive substrate such as a plastic film inferior in heat resistance. It could not be applied to a solar cell composed of

JP 2004-87622 A JP 2002-151168 A

  Therefore, the object of the present invention is to be used industrially, which can effectively prevent reverse electron transfer of the dye-sensitized solar cell, is inexpensive, and has excellent reproducibility of the performance of the dye solar cell. It is to develop a reverse electron transfer prevention layer advantageous to the above.

  According to the present invention, a dye-sensitized solar cell in which a transparent substrate having a transparent conductive film formed on its surface, a porous semiconductor layer sensitized with a dye, a carrier transport layer, and a counter electrode are stacked in this order. In this embodiment, a reverse electron transfer prevention layer of a titanium oxide thin film is provided between the transparent conductive film and the porous semiconductor layer, and the titanium oxide thin film is obtained from a titanium oxide precursor that can exist stably in water. There is provided a dye-sensitized solar cell formed using a titanium dispersion.

  According to the present invention, a titanium oxide dispersion obtained from a titanium oxide precursor (for example, titanyl sulfate, titanium sulfate, etc.) that is industrially inexpensive and versatile and can exist stably in water is used as a transparent conductive glass electrode or A reverse electron transfer prevention layer is formed on the transparent conductive film by coating and heat treatment. As described above, according to the present invention, a dye-sensitized solar cell using a transparent conductive glass or transparent conductive film having a reverse electron transfer prevention layer can be formed using an inexpensive and versatile substance, and the dye-sensitized solar cell can be formed. The short-circuit current value, open-circuit voltage, and conversion efficiency of the solar cell can be improved.

  As a result of researches to solve the above problems, the present inventors have applied a titanium oxide dispersion liquid on a transparent conductive substrate electrode, which can be industrially prepared at low cost from a titanium oxide precursor that can exist stably in water. Then, a titanium oxide thin film is formed by heat treatment, and a reverse electron prevention layer is formed using the titanium oxide thin film.

  The titanium oxide precursor is not particularly limited as long as it is a titanium compound that can stably exist in water. For example, a water-soluble inorganic titanium compound such as titanium sulfate, titanyl sulfate, and titanium tetrachloride can be preferably used.

  A method for preparing a titanium oxide dispersion from a titanium oxide precursor is known, and a titanium oxide dispersion can be produced industrially and inexpensively. The produced titanium oxide dispersion is a dispersion in which titanium oxide fine particles can be stably dispersed in water and / or an organic solvent for a long time without aggregation and precipitation.

  According to the present invention, for example, by neutralizing metatitanic acid generated by hydrolyzing an aqueous solution of the water-soluble inorganic titanium compound with aqueous ammonia, the precipitated hydrous titanium oxide is filtered, washed, and dehydrated, Aggregates of titanium oxide particles can be obtained. When this aggregate is peptized under the action of nitric acid, hydrochloric acid, aqueous ammonia or the like, an aqueous titanium oxide dispersion can be obtained.

In addition, as titanium sulfate or titanyl sulfate, which is a water-soluble inorganic titanium compound, a titanium sulfate aqueous solution formed by reacting ilmenite ore, the main component of which is FeO · TiO _2, with sulfuric acid is used in the present invention. You can also.

  Further, metatitanic acid produced by heating and hydrolyzing the aqueous solution of the water-soluble inorganic titanium compound is neutralized with aqueous ammonia, and the precipitated hydrous titanium oxide is filtered, washed, and dehydrated, thereby agglomerating titanium oxide particles. Is obtained. A titanium oxide dispersion (peroxytitanate sol) produced by adding a peroxide such as hydrogen peroxide solution to the aggregates by a heating reaction can also be used in the present invention.

  The titanium oxide sol of the present invention can be blended with alcohol in order to improve the affinity with the substrate. Alcohols to be blended include alcohols such as methanol, ethanol and propanol, ether alcohols such as methyl cellosolve, ethyl cellosolve and butyl cellosolve, and water-soluble alcohols such as polyhydric alcohols such as ethylene glycol and butylene glycol. One or more can be used. The compounding quantity of alcohol can be set suitably.

  Commercially available products of the titanium oxide sol include, for example, “TKS-201” manufactured by Teika Co., Ltd., “TKS-203” manufactured by Teika Co., Ltd., TKC-301 manufactured by Teika Co., Ltd., and PTA- manufactured by Aritex Co., Ltd. 85, PTA-170 and the like, but are not limited thereto.

  The transparent conductive substrate electrode used in the present invention is obtained by forming a transparent conductive film on a transparent substrate such as a glass substrate or a plastic substrate. As the plastic substrate, a transparent plastic sheet such as polyethylene terephthalate, polyphenylene sulfide, and polycarbonate can be used. Examples of the transparent conductive film include tin oxide, fluorine-doped tin oxide, tin-doped indium oxide, and zinc oxide. As a method for forming the transparent conductive film on the transparent substrate, for example, a known method such as a coating method, a vapor deposition method, or a sputtering method can be used.

  The porous semiconductor layer according to the present invention can be obtained by applying a dispersion of fine oxide semiconductor particles on the transparent conductive film 12. Examples of the oxide semiconductor fine particles include titanium oxide, tin oxide, zinc oxide, tungsten oxide, zirconium oxide, hafnium oxide, strontium oxide, vanadium oxide, niobium oxide, and the like. These may be used alone or in combination of two or more. Also good. A dispersion of oxide semiconductor fine particles can be obtained by mixing the semiconductor fine particles and the dispersion medium with a dispersing machine such as a sand mill, a bead mill, a ball mill, a three roll mill, a colloid mill, an ultrasonic homogenizer, a Henschel mixer, and a jet mill. it can. In addition, acetylacetone, hydrochloric acid, nitric acid, a surfactant, a chelating agent, or the like may be added in order to prevent reaggregation of fine particles in the dispersion. Various thickeners such as polymers such as polyethylene oxide and polyvinyl alcohol, and cellulose-based thickeners can be added for the purpose of thickening the dispersion.

  Commercially available products (Titanium oxide pastes Ti-Nanoxide D and Ti-Nanoxide T manufactured by Solaronix, Titanium oxide pastes SP100 and SP200 manufactured by Showa Denko KK) may be used as the semiconductor fine particle dispersion. As a method for applying the dispersion liquid of semiconductor fine particles to the transparent conductive film, for example, a known wet film forming method can be used. The wet film formation method is not particularly limited, and examples thereof include a dipping method, a spin coating method, a casting method, a die coating method, a roll coating method, a blade coating method, and a bar coating method.

  In addition, after applying a dispersion of oxide semiconductor fine particles on a transparent conductive film, heat treatment and chemical treatment are performed for the purpose of improving electronic contact between the fine particles, improving adhesion with the transparent conductive film, and improving film strength. It is preferable to perform plasma or ozone treatment. As temperature of heat processing, Preferably it is 40 to 700 degreeC, More preferably, it is 40 to 650 degreeC. The processing time is not particularly limited, but is usually about 10 to 24 hours. Examples of the chemical treatment include chemical plating treatment using a titanium tetrachloride aqueous solution, chemical adsorption treatment using a carboxylic acid derivative, and electrochemical plating treatment using a titanium trichloride aqueous solution.

  Further, a photoelectric conversion element in which a dye (photosensitizing dye) is supported on the porous semiconductor layer is a dye-sensitized solar cell. The photosensitizing dye is not particularly limited as long as it is a dye having absorption in the visible light region and / or the infrared light region, and a metal complex, an organic dye, or the like can be used. Specifically, a ruthenium complex dye, a porphyrin dye, a phthalocyanine dye, a cyanine dye, a merocyanine dye, a xanthene dye or the like coordinated with a ligand such as a bipyridine structure or a terpyridine structure can be used. There is no particular limitation on the method of supporting, but the dye is dissolved in, for example, water or alcohol, and the electrode composed of the porous semiconductor layer is immersed in the dye solution or the dye solution is applied to the porous semiconductor layer. It can be supported.

  The carrier transport layer used in the present invention is composed of an electrolytic solution containing an organic solvent containing an oxidation-reduction pair or an ionic liquid. Examples of the organic solvent include acetonitrile, methoxyacetonitrile, propionitrile, ethylene carbonate, propylene carbonate, and γ-butyrolactone. As ionic liquids, imidazolium salts, pyridinium salts, pyrrolidinium salts (Hiroyuki Ohno, Industrial Materials, 48, 39 (2000), edited by Hiroyuki Ohno, "Ionic Liquids-Frontiers and Future of Development", CMC Publishing ( 2003)) and the like, and preferably an imidazolium cation and an iodide ion, a pisttrifluoromethylsulfonylimide anion, and a dicyanoamide ion.

  The redox couple is not particularly limited, and iodine / iodide ions, bromine / bromide ions, and the like can be used. For example, iodine / iodide such as iodine and metal iodide such as LiI, NaI and KI, iodide salt of iodine and quaternary imidazolium compound, iodide salt of quaternary pyridinium compound, iodide salt of tetraalkylammonium compound, etc. Bromine / bromide ions such as ion pairs, bromine and metal bromides such as LiBr, NaBr, KBr, bromide salts of bromine and quaternary imidazolium compounds, bromide salts of quaternary pyridinium compounds, bromide salts of tetraalkylammonium compounds, ferrocyan Examples thereof include metal complexes such as acid-ferricyanate and ferrocene-ferricinium salts, sulfur compounds of disulfide compounds and mercapto compounds, hydroquinone and quinone. Preferably, a redox pair of iodine and iodide salt is preferred. These redox pairs may be used alone or in combination of two or more. 4-t-butylpyridine or N-methylbenzimidazole may be added to the electrolytic solution as an additive for efficiently transferring electrons. Further, an appropriate gelling agent may be added to the electrolytic solution to gel the electrolytic solution. The gelling agent is not particularly limited as long as it forms a physical gel and a chemical gel. The physical gel is gelled by the physical interaction between the gelling agent and the electrolytic solution, and the chemical gel is a chemical interaction between the gelling agent and / or between the gelling agent and the electrolytic solution. It is formed by (hydrogen bond, covalent bond, ionic bond, etc.). In the case of a physical gel, examples of the gelling agent include polyacrylonitrile and polyvinylidene fluoride. In the case of a chemical gel, examples of the gelling agent include polyvinyl pyridine, an oil gelling agent described in Japanese Patent Application Laid-Open No. 2000-58140, and a layered clay mineral described in Japanese Patent Application No. 2005-005332. it can.

  As the carrier transport layer, a solid hole transport material can be used instead of the electrolytic solution. Examples of the hole transport material include p-type semiconductors and organic hole transport materials. For example, P-type semiconductors include monovalent copper compounds such as copper iodide and copper thiocyanide, and organic hole transport materials include tri-type semiconductors. Phenylamine etc. are mentioned.

  The temperature which heat-processes a titanium oxide dispersion liquid is 25 to 250 degreeC, for example, Preferably it is 80 to 200 degreeC. Although there is no restriction | limiting in particular in the film thickness of the titanium oxide thin film which is a reverse electron prevention layer formed from a titanium oxide dispersion liquid, Preferably it is 0.01-1 micrometer, More preferably, it is 0.1-1 micrometer.

  The dye-sensitized solar cell of the present invention using the transparent conductive glass having such an inexpensive and versatile reverse electron transfer prevention layer has improved short-circuit current value, open-circuit voltage, conversion efficiency, and reverse electrons like conventional ones. A dye-sensitized solar cell excellent in reproducibility can be obtained without the problem of storage stability like the material constituting the migration preventing layer.

  The dye-sensitized solar cell according to the present invention can have a conventional configuration except that the specific reverse electron transfer prevention layer described above is used, and does not particularly require a new configuration or manufacturing process. .

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, it cannot be overemphasized that the scope of the present invention is not limited to these Examples.

Synthesis Example 1: Preparation of ionic liquid 1-methyl-3-propylimidazolium iodide 1-methylimidazole (8.2 g, manufactured by Aldrich) and propyl iodide (16.9 g, Kanto Chemical Co., Inc.) in toluene The product was stirred at 75 ° C. for 15 hours. After completion of the reaction, it was separated into two layers, a toluene layer and an ionic liquid layer. The ionic liquid was collected by removing the toluene layer from the reaction solution, and purification was performed by washing the obtained ionic liquid with toluene three times. Toluene was distilled off under reduced pressure to obtain ionic liquid 1-methyl-3-propylimidazolium iodide (23.8 g).

Synthesis Example 2: Preparation of ionic liquid electrolyte 0.5M lithium iodide, 0.3M iodine and 0.5M 4-tert-butylpyrzine are dissolved in ionic liquid 1-methyl-3-propylimidazolium iodide. Thus, an ionic liquid electrolyte was prepared.

Synthesis example 3: Preparation of ionic liquid gel electrolyte Dispersion liquid (concentration 5) in which organic layered clay mineral Lucentite SPN (manufactured by Co-op Chemical) was swollen and dispersed in acetonitrile in the ionic liquid electrolyte prepared in Synthesis Example 2. (Weight% dispersion) was added (mixing ratio was 7.5% by weight of SPN with respect to the ionic liquid electrolyte), and the mixture was stirred at room temperature for 3 hours. After completion of the stirring, acetonitrile was distilled off in vacuo to obtain a viscous substance ionic liquid gel electrolyte.

Production of transparent conductive glass 1 having a reverse electron transfer prevention layer On a hot plate set at 150 ° C., a transparent conductive glass made by Nippon Sheet Glass Co., Ltd. (tin oxide whose conductive film is fluorine-doped, sheet resistance 8Ω / □) is placed. Then, a transparent conductive glass 1 having a reverse electron transfer prevention layer was produced by applying a titanium oxide dispersion A (manufactured by TEIKA, titanium oxide sol dispersion TKS-201) on the transparent conductive film.

Preparation of transparent conductive glass 2 having a reverse electron transfer prevention layer On a hot plate set at 150 ° C., transparent conductive glass (tin oxide with conductive film fluorine-doped, sheet resistance 8Ω / □) manufactured by Nippon Sheet Glass Co., Ltd. is placed. By applying the titanium oxide dispersion liquid A (manufactured by Teika, titanium oxide sol dispersion liquid TKS-201) used when the transparent conductive glass 1 was produced, a reverse electron transfer prevention layer was applied one week after the transparent conductive glass 1 was produced. The transparent conductive glass 2 which has this was produced.

Preparation of transparent conductive glass 3 having a reverse electron transfer prevention layer 5 mL of titanium tetraisopropoxide, 15 mL of 2-propanol and 5.5 mL of acetic acid were mixed, and 3 mL of water was added dropwise little by little with vigorous stirring, and the suspension (oxidation) A titanium dispersion B) was obtained. The suspension was dropped, coated and dried on a transparent conductive glass manufactured by Nippon Sheet Glass Co., Ltd. placed on a hot plate set at 100 ° C., and then baked at 450 ° C. for 5 minutes to reverse the suspension. A transparent conductive glass 3 having an electron migration preventing layer was produced.

Preparation of transparent conductive glass 4 having reverse electron transfer prevention layer Titanium tetraisopropoxide, 5 mL of 2-propanol, and 5.5 mL of acetic acid are mixed, and 3 mL of water is dropped little by little with vigorous stirring, and the suspension (oxidation) A titanium dispersion B) was obtained. After this suspension was left for 1 week, a transparent conductive glass 4 having a reverse electron transfer preventing layer was prepared in the same manner as the transparent conductive glass 2 having a reverse electron transfer preventing layer was prepared.

Production of transparent conductive film 5 having a reverse electron transfer preventing layer Polyethylene terephthalate transparent conductive film (TOTEC OTEC manufactured by Nippon Steel Glass Co., Ltd.) instead of transparent conductive glass (tin oxide with conductive film fluorine-doped, sheet resistance 8Ω / □) -120, a thickness of 188 μm, forming an indium oxide transparent conductive film doped with tin on the surface, and using the same method as that for producing the transparent conductive glass 1 having a reverse electron transfer preventing layer except that a sheet resistance of 20Ω / □ is used. A transparent conductive film 5 was produced.

Preparation of transparent conductive film 6 having reverse electron transfer preventing layer 5 mL of titanium tetraisopropoxide, 15 mL of 2-propanol and 5.5 mL of acetic acid were mixed, and 3 mL of water was added dropwise little by little with vigorous stirring to obtain a suspension. It was. This suspension was placed on a hot plate set at 100 ° C., and a polyethylene terephthalate transparent conductive film (OTEC-120 manufactured by Tobi, thickness 188 μm, tin-doped indium oxide transparent conductive film was formed on the surface, sheet resistance 20Ω / □) was dropped, applied, and dried, and then fired at 150 ° C. for 10 minutes to obtain a transparent conductive film 6 having a reverse electron prevention layer.

Production of photoelectrode 1 On a transparent conductive glass 1 having an anti-electron transfer prevention layer, a titanium oxide paste (Solaronix, Ti-Nanoxide T) is applied, dried, and then sintered at 450 ° C. for 1 hour. A porous titanium oxide thin film was formed on the glass substrate 1. The transparent conductive electrode having this porous titanium oxide thin film was converted to a ruthenium complex dye (cis- (dithiocyanate) -N, N′-bis (2,2′-bipyridyl-4,4′-dicarboxylic acid) ruthenium ( II) Complex) was immersed in an ethanol solution (concentration 3 × 10 ⁻⁴ mol / L) for 12 hours. After washing with ethanol, the photoelectrode 1 having a porous titanium oxide thin film carrying a sensitizing dye on the transparent conductive glass 1 was produced by drying in a dark place under a nitrogen stream.

Production of photoelectrode 2 Photoelectrode 2 was produced in the same manner as photoelectrode 1 except that transparent conductive glass 2 having a reverse electron blocking layer was used instead of transparent conductive glass 1 having a reverse electron transfer preventing layer.

Production of photoelectrode 3 Photoelectrode 3 was produced in the same manner as photoelectrode 1 except that transparent conductive glass 3 having a reverse electron blocking layer was used instead of transparent conductive glass 1 having a reverse electron transfer preventing layer.

Production of Photo Electrode 4 Photo electrode 4 was produced in the same manner as photo electrode 1 except that transparent conductive glass 4 having a reverse electron blocking layer was used instead of transparent conductive glass 1 having a reverse electron transfer preventing layer.

Production of Photoelectrode 5 A titanium oxide paste (Solaronix, Ti-Nanoxide T) is applied on a transparent conductive glass (tin oxide with conductive film fluorine-doped, sheet resistance 8Ω / □) manufactured by Nippon Sheet Glass Co., Ltd., and dried. Then, the porous titanium oxide thin film was formed on the transparent conductive glass substrate 1 by sintering at 450 degreeC for 1 hour. The transparent conductive electrode having this porous titanium oxide thin film was converted to a ruthenium complex dye (cis- (dithiocyanate) -N, N′-bis (2,2′-bipyridyl-4,4′-dicarboxylic acid) ruthenium ( II) Complex) was immersed in an ethanol solution (concentration 3 × 10 ⁻⁴ mol / L) for 12 hours. After washing with ethanol, the photoelectrode 5 having a porous titanium oxide thin film carrying a sensitizing dye on the transparent conductive glass 1 was produced by drying in a dark place under a nitrogen stream.

Production of photoelectrode 6 Titanium oxide paste (manufactured by Solaronix, Ti-Nanoxide T-L) is applied on the transparent conductive film 5 having a reverse electron prevention layer, dried, and then sintered at 150 ° C. for 1 hour to obtain transparent A porous titanium oxide thin film was formed on the conductive film substrate 5. The transparent conductive electrode having this porous titanium oxide thin film was converted to a ruthenium complex dye (cis- (dithiocyanate) -N, N′-bis (2,2′-bipyridyl-4,4′-dicarboxylic acid) ruthenium ( II) Complex) was immersed in an ethanol solution (concentration 3 × 10 ⁻⁴ mol / L) for 12 hours. After washing with ethanol, the photoelectrode 6 having a porous titanium oxide thin film carrying a sensitizing dye on the transparent conductive film 5 was produced by drying in a dark place under a nitrogen stream.

Production of photoelectrode 7 Photoelectrode 7 was produced in the same manner as photoelectrode 6 except that transparent conductive film 6 having a reverse electron blocking layer was used instead of transparent conductive film 5 having a reverse electron blocking layer.

Production of photoelectrode 8 Polyethylene terephthalate transparent conductive film (Totec OTEC-120, thickness 188 μm, tin-doped indium oxide transparent conductive film formed on the surface instead of transparent conductive film 5 having a reverse electron prevention layer, sheet resistance Photoelectrode 8 was produced in the same manner as photoelectrode 6 except that 20Ω / □) was used.

Platinum counter electrode 1
A platinum thin film having a thickness of about 100 nm was formed by sputtering on the surface of Nippon Sheet Glass Co., Ltd. transparent conductive glass (the conductive film was fluorine-doped tin oxide, sheet resistance 8Ω / □), and this electrode was used as a platinum counter electrode. .

Platinum counter electrode 2
Tobi polyethylene terephthalate transparent conductive film (OTEC-120, thickness 188μm, tin-doped indium oxide transparent conductive film is formed on the surface, sheet resistance 20Ω / □) on the surface, a platinum thin film with a thickness of about 100nm is formed by sputtering This electrode was used as a platinum counter electrode.

Example 1
The battery of Example 1 was obtained by applying the ionic liquid electrolyte to the photoelectrode 1 produced above, superimposing this on the platinum counter electrode 1 produced above, and fixing with a clip.

Example 2
A battery of Example 2 was obtained in the same manner as in Example 1 except that the photoelectrode 2 was used instead of the photoelectrode 1.

Example 3
An ionic liquid gel electrolyte was applied to the photoelectrode 1 produced above, and the platinum counter electrode 1 produced above was overlaid and then fixed with a clip to obtain a battery of Example 3.

Example 4
A battery of Example 4 was obtained in the same manner as in Example 3 except that the photoelectrode 2 was used instead of the photoelectrode 1.

Example 5
An ionic liquid electrolyte was applied to the photoelectrode 6 produced above, and the platinum counter electrode 2 produced above was overlaid, and then fixed with a clip to obtain a battery of Example 5.

Example 6
An ionic liquid gel electrolyte was applied to the photoelectrode 6 produced above, and the platinum counter electrode 2 produced above was overlaid, and then fixed with a clip to obtain a battery of Example 6.

Comparative Example 1
An ionic liquid electrolyte was applied to the photoelectrode 3 produced above, and the platinum counter electrode 1 produced above was overlaid, and then fixed with a clip to obtain a battery of Comparative Example 1.

Comparative Example 2
A battery of Comparative Example 2 was obtained in the same manner as the battery of Comparative Example 1 except that the photoelectrode 4 was used instead of the photoelectrode 3.

Comparative Example 3
A battery of Comparative Example 3 was obtained in the same manner as the battery of Comparative Example 1, except that the photoelectrode 5 was used instead of the photoelectrode 3.

Comparative Example 4
An ionic liquid gel electrolyte was applied to the photoelectrode 3 produced above, the platinum counter electrode 1 produced above was overlaid, and then fixed with a clip to obtain a battery of Comparative Example 4.

Comparative Example 5
A battery of Comparative Example 5 was obtained in the same manner as the battery of Comparative Example 4 except that the photoelectrode 4 was used instead of the photoelectrode 3.

Comparative Example 6
A battery of Comparative Example 6 was obtained in the same manner as the battery of Comparative Example 4 except that the photoelectrode 5 was used instead of the photoelectrode 3.

Comparative Example 7
An ionic liquid electrolyte was applied to the photoelectrode 7 produced above, the platinum counter electrode 2 produced above was overlaid, and then fixed with a clip to obtain a battery of Comparative Example 7.

Comparative Example 8
A battery of Comparative Example 8 was obtained in the same manner as the battery of Comparative Example 7, except that the photoelectrode 8 was used instead of the photoelectrode 7.

Comparative Example 9
An ionic liquid gel electrolyte was applied to the photoelectrode 7 produced above, and the platinum counter electrode 2 produced above was overlaid, and then fixed with a clip to obtain a battery of Comparative Example 9.

Comparative Example 10
A battery of Comparative Example 10 was obtained in the same manner as the battery of Comparative Example 9, except that the photoelectrode 8 was used instead of the photoelectrode 7.

Evaluation of Battery The batteries of Examples 1 to 6 and Comparative Examples 1 to 10 described above were irradiated with simulated sunlight of AM1.5 from the photoelectrode side with a light intensity of 100 mW / cm ² using a solar simulator as a light source. Short-circuit current, open-circuit voltage, fill factor, and conversion efficiency were determined using a voltage measurement device (Digital Source Meter 2400 manufactured by Keithley Instruments).

  Comparing the batteries of Examples 1 and 2 made of transparent conductive glass and ionic liquid electrolyte with the batteries of Comparative Examples 1 to 3, Example 1 was compared with the battery of Comparative Example 3 without the reverse electron blocking layer. And the battery of Example 2 has improved open circuit voltage and conversion efficiency. On the other hand, the battery of Comparative Example 1 also has improved open-circuit voltage and conversion efficiency as compared with the battery of Comparative Example 3, but is smaller than the batteries of Examples 1 and 2. Further, in the batteries of Example 1 and Example 2, the battery characteristics are the same regardless of the time of the titanium oxide dispersion, whereas in the batteries of Comparative Examples 1 and 2, the battery characteristics are titanium oxide dispersed. It decreases with the aging of the liquid. Therefore, it can be seen that the battery in which the reverse electron blocking layer is formed using the titanium oxide dispersion of the present invention is a battery having high efficiency and excellent reproducibility.

  When the batteries of Examples 3 to 4 and the batteries of Comparative Examples 4 to 6 composed of a transparent conductive glass and an ionic liquid gel electrolyte are compared, the Examples are compared with the battery of Comparative Example 6 having no reverse electron blocking layer. The batteries of 3 and Example 4 have improved open circuit voltage and conversion efficiency. On the other hand, the battery of Comparative Example 4 also has improved open-circuit voltage and conversion efficiency as compared with the battery of Comparative Example 6, but the values are smaller than those of the batteries of Examples 3 and 4. In addition, in the batteries of Example 3 and Example 4, the battery characteristics are the same regardless of the time of the titanium oxide dispersion, whereas in the batteries of Comparative Examples 4 and 5, the battery characteristics are titanium oxide dispersed. It decreases with the aging of the liquid. Therefore, it can be seen that the battery in which the reverse electron blocking layer is formed using the titanium oxide dispersion of the present invention is a battery having high efficiency and excellent reproducibility.

  Compared with the battery of Example 5 and the batteries of Comparative Examples 7-8, which are composed of a transparent conductive film and an ionic liquid electrolyte, and the battery of Example 6 which is composed of a transparent conductive film and an ionic liquid gel electrolyte When the batteries of Examples 9 to 10 are compared, the battery of Example 5 (6) has improved open circuit voltage and conversion efficiency compared to the battery of Comparative Example 8 (10) without the reverse electron prevention layer. On the other hand, the battery of Comparative Example 7 (9) has lower open-circuit voltage and conversion efficiency than the battery of Comparative Example 8 (10). In Comparative Example 7 (9), the reverse electron prevention layer is formed using a titanium oxide dispersion formed from titanium isopropoxide, but the heat treatment temperature during the formation of the reverse electron prevention layer is as low as 150 ° C. Further, the crystallization of titanium oxide does not proceed sufficiently and the function as a reverse electron prevention layer is not expressed. Therefore, when the reverse electron prevention layer is formed using the titanium oxide dispersion of the present invention, a battery with high efficiency and excellent reproducibility can be obtained even in a battery using a film conductive substrate having poor heat resistance. I understood.

  According to the present invention, as described above, the reverse electron transfer of the dye-sensitized solar cell can be effectively prevented, and it is industrially used with low cost and excellent reproducibility of the performance of the dye solar cell. Therefore, the usefulness of the dye-sensitized solar cell can be further enhanced.

It is explanatory drawing which shows the structure of the classic dye-sensitized solar cell which does not have a reverse electron transfer prevention layer. It is explanatory drawing which shows the structure of the present dye-sensitized solar cell which has a reverse electron transfer prevention layer.

Claims (5)

  In the dye-sensitized solar cell in which a transparent substrate having a transparent conductive film formed on the surface, a porous semiconductor layer sensitized with a dye, a carrier transport layer, and a counter electrode are stacked in this order, the transparent conductive film Using a titanium oxide dispersion obtained from a titanium oxide precursor that is provided with a reverse electron transfer prevention layer of a titanium oxide thin film between the porous semiconductor layer and the porous semiconductor layer, and the titanium oxide thin film can exist stably even in water A dye-sensitized solar cell that is formed.   The dye-sensitized solar cell according to claim 1, wherein the porous semiconductor layer is composed of a metal oxide semiconductor.   The dye-sensitized solar cell according to claim 1 or 2, wherein the carrier transport layer is an electrolyte composed of an ionic liquid.   The dye-sensitized solar cell according to any one of claims 1 to 3, wherein the carrier transport layer is a gel or solid electrolyte.   The dye-sensitized solar cell according to any one of claims 1 to 4, wherein the titanium oxide thin film constituting the reverse electron transfer preventing layer has a thickness of 0.01 to 1 µm.

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