JP2011181286A - Dye-sensitized solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dye-sensitized solar cell having improved optical absorption and photoelectric conversion characteristics. <P>SOLUTION: In the dye-sensitized solar cell, a dye supporting metal oxide electrode includes a sensitizing dye represented by general formula (1). In the formula (1), R1 and R2 are independently hydrogen atoms, terminal aryl groups, terminal alkyl groups, or terminal alkoxy groups, at least one of the R1 and R2 is the terminal aryl group, terminal alkyl group, or terminal alkoxy group, the R1 and R2 can be bonded to each other to form a ring. R3, R4 are independently anchor groups or alkyl groups, and at least one of them is the anchor group. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a dye-sensitized solar cell using a plurality of sensitizing dyes.

  In recent years, dye-sensitized solar cells have attracted attention because they have high photoelectric conversion efficiency among organic solar cells and can be manufactured at low cost. The main components of the dye-sensitized solar cell are a porous metal oxide semiconductor (metal oxide layer), a sensitizing dye supported on the metal oxide semiconductor, an electrolyte, and a counter electrode. is there.

  In the technical field of such dye-sensitized solar cells, attempts have been made to increase the light absorption rate by changing the design of the sensitizing dye for the purpose of further improving the photoelectric conversion characteristics. However, since the wavelength region in which each sensitizing dye can be absorbed is limited, there is a natural limit to improving the light absorption rate of the sensitizing dye.

  Therefore, Patent Documents 1 to 3 attempt to increase the collection efficiency of light energy by using a mixture of a plurality of sensitizing dyes having different absorption wavelength characteristics.

JP 2009-032547 A JP 2007-234580 A

Applied Physics Letters 94, 073308 (2009)

  However, even if a plurality of types of sensitizing dyes are mixed and used as in the prior art, it is not easy to increase the collection efficiency of light energy. In fact, the photoelectric conversion efficiency of the dye-sensitized solar cell is not improved. In most cases, it decreased. This is presumably because the quantum yield is remarkably lowered by the adsorption state of plural kinds of sensitizing dyes, electron transfer between sensitizing dyes, and the like. Therefore, in order to increase the collection efficiency of light energy, in combination with a plurality of types of sensitizing dyes, it has been required to establish a combination of sensitizing dyes that can withstand practical use and a method for producing the same.

  This invention is made | formed in view of this situation, The objective is to provide the dye-sensitized solar cell with which the light absorption rate and the photoelectric conversion characteristic were improved. Another object of the present invention is to provide a dye-sensitized solar cell including a working electrode supported (adsorbed) on a metal oxide layer in a state where a plurality of kinds of sensitizing dyes are optimized.

  As a result of intensive studies, the inventors have improved light absorption and photoelectric conversion characteristics by using a plurality of sensitizing dyes having different wavelength sensitivity regions in chemical structure and spectral sensitivity characteristics (IPCE). In addition, the inventors have found that a dye-sensitized solar cell can be obtained, and have found the optimum conditions in which these sensitizing dyes are supported (adsorbed) on the metal oxide layer, thereby completing the present invention.

That is, the present invention provides the following <1> to <5>.
<1> A dye-sensitized solar cell including a working electrode having a dye-supported metal oxide electrode in which a dye is supported on a metal oxide layer,
The dye-supported metal oxide electrode has the following general formulas (1) and (2):
(In Formula (1), R1 and R2 are each independently a hydrogen atom, a terminal aryl group, a terminal alkyl group, or a terminal alkoxy group, and at least one of R1 and R2 is a terminal aryl group, a terminal alkyl group. R1 and R2 may be bonded to form a ring, and R3 and R4 are each independently an anchor group or an alkyl group, and at least one of them is a group or a terminal alkoxy group. Anchor group.)
(In Formula (2), R5 to R8 are each independently a linear alkyl group having 4 to 20 carbon atoms, and each may be the same or different, and R9 and R10 are each independent. And each of them may be the same or different, and R 11 is any one of a hydrogen atom, an alkyl group, a halogen element, and a cyano group.)
Comprising a sensitizing dye represented by:
Dye-sensitized solar cell.
<2> In the ultraviolet-visible absorption spectrum measurement, the dye-supported metal oxide electrode has an absorption maximum intensity of a light absorption peak derived from the sensitizing dye represented by the general formula (2) according to the general formula (2). 50% or more with respect to the absorption maximum intensity of the light absorption peak derived from the sensitizing dye represented by the general formula (2) when the sensitizing dye represented on the metal oxide layer is supported alone. In the range of less than 90%,
The dye-sensitized solar cell according to <1> above.
<3> The metal oxide layer is a layer substantially made of zinc oxide.
The dye-sensitized solar cell according to <1> or <2> above.
<4> The sensitizing dye represented by the general formula (1) is represented by the following general formula (3):
A sensitizing dye represented by
The sensitizing dye represented by the general formula (2) is represented by the following general formula (4):
Is a sensitizing dye represented by
The dye-sensitized solar cell according to any one of <1> to <3> above.
<5> Further, a counter electrode disposed so as to face the dye-supported metal oxide electrode of the working electrode, and an electrolyte provided between the working electrode and the counter electrode,
The dye-sensitized solar cell according to any one of <1> to <4> above.

  According to the present invention, a dye-sensitized solar cell with improved light absorption rate and photoelectric conversion characteristics is realized. In addition, a dye-sensitized solar cell including a working electrode in which a limited combination of a plurality of types of sensitizing dyes are supported (adsorbed) on a metal oxide layer in an optimal adsorption state is realized. Accordingly, it is possible to suppress a decrease in light absorption rate and photoelectric conversion characteristics due to excessive loading (adsorption) of the sensitizing dye. Moreover, since the usage-amount of a sensitizing dye is appropriate, cost increase is suppressed.

1 is a cross-sectional view showing a schematic configuration of a dye-sensitized solar cell 100. FIG. It is an ultraviolet-visible absorption spectrum measurement of the pigment | dye carrying | support metal oxide electrode of the dye-sensitized solar cell of Example 1- Example 3 and Comparative Examples 1-2. It is a spectral sensitivity characteristic of the dye-sensitized solar cell of Example 1, Comparative Example 1, and Reference Example.

  Embodiments of the present invention will be described below. In addition, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the illustrated ratios. The following embodiments are examples for explaining the present invention, and the present invention is not limited only to the embodiments.

FIG. 1 is a cross-sectional view showing a schematic configuration of the dye-sensitized solar cell of the present embodiment.
The dye-sensitized solar cell 100 includes a working electrode 11, a counter electrode 21, and an electrolyte 31 provided between the working electrode 11 and the counter electrode 21. At least one of the working electrode 11 and the counter electrode 21 is an electrode having optical transparency. The working electrode 11 and the counter electrode 21 are arranged to face each other via a spacer 41, and an electrolyte 31 is enclosed in a sealing space defined by the working electrode 11, the counter electrode 21, the spacer 41, and a sealing member (not shown). Has been.

  The working electrode 11 functions as a negative electrode for the external circuit. The working electrode 11 includes a porous metal oxide layer 13 containing a metal oxide on the conductive surface 12 a of the base 12, and a sensitizing dye is supported (adsorbed) on the metal oxide layer 13. A dye-supported metal oxide electrode 14 is formed. In other words, the working electrode 11 of the present embodiment has a composite structure in which a sensitizing dye is supported (adsorbed) on the metal oxide surface of the metal oxide layer 13 laminated on the conductive surface 12a of the substrate 12. (Dye-supported metal oxide electrode 14).

  The type and size of the substrate 12 are not particularly limited as long as at least the metal oxide layer 13 can be supported. For example, a plate-like or sheet-like material is preferably used. Specific examples thereof include glass substrates, polyethylene, polypropylene, polystyrene, tetraacetylcellulose (TAC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), syndiotactic polystyrene (SPS), and polyphenylene sulfide (PPS). , Polycarbonate (PC), polyarylate (PAR), polysulfone (PSF), polyester sulfone (PES), polyetherimide (PEI), cyclic polyolefin or brominated phenoxy plastic substrate, metal substrate or alloy substrate, ceramic substrate Or these laminated bodies etc. are mentioned. Moreover, it is preferable that the base | substrate 12 has translucency, and the thing excellent in the translucency in visible region is more preferable. Further, the base 12 is preferably flexible. In this case, it is possible to provide various types of structures utilizing the flexibility.

The conductive surface 12a can be applied to the base 12 by, for example, forming a transparent conductive film on the base 12 like a conductive PET film. Moreover, the process which provides the electroconductive surface 12a to the base | substrate 12 can be skipped by using the base | substrate 12 which has electroconductivity. Specific examples of the transparent conductive film include, for example, a metal thin film containing gold (Au), silver (Ag), platinum (Pt), or the like, or a conductive polymer, indium-tin oxide ( ITO), indium - zinc oxide (IZO), other SnO _2, InO _3, although FTO fluorine-doped SnO ₂ (F-SnO _2), and the like, not particularly limited thereto. These may be used alone or in combination. The formation method of a transparent conductive film is not specifically limited, For example, well-known methods, such as a vapor deposition method, CVD method, a spray method, a spin coat method, or an immersion method, are applicable. Moreover, the film thickness of a transparent conductive film can be set suitably. The conductive surface 12a of the substrate 12 may be subjected to appropriate surface modification treatment as necessary. Specifically, for example, a known surface treatment such as a degreasing treatment with a surfactant, an organic solvent or an alkaline aqueous solution, a mechanical polishing treatment, an immersion treatment in an aqueous solution, a preliminary electrolytic treatment with an electrolytic solution, a water washing treatment, a drying treatment, etc. However, it is not particularly limited to these.

  The metal oxide layer 13 is a carrier that carries a sensitizing dye. The metal oxide layer 13 generally has a porous structure with many voids and a large surface area, and is preferably dense and has few voids, and preferably has a film shape. More preferred. In particular, the metal oxide layer 13 preferably has a structure in which porous fine particles are attached.

  The metal oxide layer 13 of this embodiment is mainly composed of a metal oxide such as titanium oxide, zinc oxide, tin oxide, niobium oxide, indium oxide, zirconium oxide, tantalum oxide, vanadium oxide, yttrium oxide, aluminum oxide, or magnesium oxide. It is a porous semiconductor layer as a component. These metal oxides may be used alone or in combination of two or more (mixed, mixed crystal, solid solution, etc.). From the viewpoint of obtaining high photoelectric conversion efficiency, the metal oxide layer 13 is preferably a layer substantially made of zinc oxide. Here, “consisting essentially of zinc oxide” means containing 95 wt% or more of zinc oxide. The metal oxide layer 13 is made of a metal such as titanium, tin, zinc, iron, tungsten, zirconium, strontium, indium, cerium, vanadium, niobium, tantalum, cadmium, lead, antimony, bismuth, these metal oxides and These metal chalcogenides may be included. In addition, although the thickness of the metal oxide layer 13 is not specifically limited, It is preferable that it is 0.05-50 micrometers.

  As a method for forming the metal oxide layer 13, for example, a method in which a metal oxide dispersion is applied to the conductive surface 12 a of the substrate 12 and then dried, or a metal oxide dispersion is applied to the conductive surface 12 a of the substrate 12. An electrolytic solution containing a metal salt in addition to a method of high-temperature sintering after being applied on top, a method of performing a low-temperature treatment at about 50 to 150 ° C. after applying a metal oxide paste onto the conductive surface 12a of the substrate 12 The method of carrying out cathode electrodeposition on the conductive surface 12a of the substrate 12 is not particularly limited. Here, if a method that does not require high-temperature sintering is employed, a plastic material having low heat resistance can be used as the substrate 12.

  The metal oxide layer 13 carries (adsorbs) a sensitizing dye capable of injecting electrons into the metal oxide by being excited by absorbing light.

  In the present embodiment, as the sensitizing dye supported on the metal oxide layer 13, one represented by the following general formula (1) is essential. Although the sensitizing dye having such a structure has a bulky steric structure, it not only has excellent adsorptivity to the metal oxide surface of the metal oxide layer 13, but also has excellent electron injection efficiency into the metal oxide. Thereby, it is thought that the sensitizing dye represented by the following general formula (1) mainly contributes to the improvement of photoelectric conversion efficiency.

(In Formula (1), R1 and R2 are each independently a hydrogen atom, a terminal aryl group, a terminal alkyl group, or a terminal alkoxy group, and at least one of R1 and R2 is a terminal aryl group, a terminal alkyl group. R1 and R2 may be bonded to form a ring, and R3 and R4 are each independently an anchor group or an alkyl group, and at least one of them is a group or a terminal alkoxy group. Anchor group.)

  In the general formula (1), the “terminal aryl group” means a monovalent substituent whose terminal is an aryl group, and more specifically, a linking group such as a single bond, an alkylene group or an alkenylene group. Means a monovalent substituent in which an aryl group is connected via Specific examples of the terminal aryl group of R1 and R2 include, for example, aromatic hydrocarbons having 6 to 12 carbon atoms (for example, phenyl group, naphthyl group, etc.), and these aromatic hydrocarbons are alkylene groups or alkenylenes. Examples thereof include those linked via a linking group such as a group (for example, phenylmethyl group, diphenylethyl group, triphenylmethyl group, 1-phenylethylene group, 1,1-diphenylethylene group, etc.). There is no particular limitation. Among these, a phenyl group, a benzyl group, a tolyl group, a xylyl group, a 1,1-diphenylethylene group and the like are preferable, and a 1,1-diphenylethylene group is more preferable.

  In the general formula (1), “terminal alkyl group” means a monovalent substituent whose terminal is an alkyl group, and more specifically, via a linking group such as a single bond, an aryl group or an alkenylene group. Means a monovalent substituent to which an alkyl group is linked. Specific examples of the terminal alkyl group of R1 and R2 include, for example, a linear, branched or cyclic hydrocarbon having 1 to 20 carbon atoms (for example, methyl group, ethyl group, propyl group, isopropyl group, n -Butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, n-hexyl group, isohexyl group, 2-hexyl group, dimethylbutyl group, ethylbutyl group, In addition to heptyl group, octyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, etc., these hydrocarbons are linked through a linking group such as aryl group or alkenylene group (methylphenyl group, ethyl group, etc.) Phenyl group, dimethylphenyl group and the like), but is not particularly limited thereto. Among these, a linear or branched alkyl group having 1 to 8 carbon atoms is preferable, and a linear alkyl group having 1 to 5 carbon atoms is more preferable.

In the general formula (1), the “terminal alkoxy group” means a monovalent substituent whose terminal is an alkoxy group, and more specifically, via a linking group such as a single bond, an aryl group or an alkenylene group. Means a monovalent substituent to which an alkoxy group is linked. Specific examples of the terminal alkoxy group of R1 and R2 include, for example, an alkoxy group having 1 to 20 carbon atoms (for example, methoxy group, ethoxy group, propoxy group, isopropoxy group, isobutoxy group, sec-butoxy group, tert- In addition to butoxy group, hexyloxy group, etc., these alkoxy groups are linked via a linking group such as aryl group or alkenylene group (methoxyphenyl group, ethoxyphenyl group, dimethoxyphenyl group, methoxyphenylethylene group, ethoxy group) Phenylethylene group and the like), but is not particularly limited thereto. Among these, linear or branched hydrocarbons having 1 to 20 carbon atoms (for example, methoxy group, ethoxy group, propoxy group, isopropoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, hexyloxy group, etc.) are preferred, a methoxy group, an ethoxy group, n- propoxy group, isopropoxy group, n- butoxy group, isobutoxy group, sec- butoxy group, tert- butoxy group, and, are -O-nC ₆ H ₁₃ More preferred is a methoxy group.

  In general formula (1), R1 and R2 may combine to form a ring. Specific examples of the ring formed by combining R1 and R2 include, but are not limited to, pyran, dioxin, dioxane and the like.

  In the above general formula (1), the “anchor groups” of R3 and R4 have a chemical or electrostatic affinity or binding ability to the metal oxide surface of the metal oxide layer 13 as a support. Means a substituent. Specific examples of the anchor group include a substituent having a carboxyl group, a sulfonic acid group, and a phosphoric acid group. Among these, as the anchor group, a carboxymethyl group and a carboxyundecyl group are preferable. In the general formula (1), specific examples of the alkyl group represented by R3 and R4 include, for example, a linear or branched alkyl group having 1 to 8 carbon atoms exemplified in R1 and R2. . In these, a C1-C5 linear alkyl group is preferable.

  Specific examples of the sensitizing dye represented by the above general formula (1) include compounds represented by chemical formulas (1-1) to (1-4).

As the sensitizing dye represented by the general formula (1), a sensitizing dye represented by the following general formula (3) is particularly preferable.

  Moreover, in this embodiment, as a sensitizing dye carry | supported by the metal oxide layer 13, what is represented by following General formula (2) is also essential. The sensitizing dye having such a structure has a large steric size as a whole molecule because a sterically bulky linear alkyl group having 4 to 20 carbon atoms is introduced into the indolenine skeleton. . Therefore, it is difficult for the sensitizing dye to form an aggregate, and the ratio of the aggregate that hardly contributes to photoelectric conversion is reduced on the metal oxide surface of the metal oxide layer 13. Therefore, it is considered that the sensitizing dye represented by the following general formula (2) mainly contributes to an increase in light absorption by suppressing the formation of an aggregate that does not easily contribute to photoelectric conversion.

(In Formula (2), R5 to R8 are each independently a linear alkyl group having 4 to 20 carbon atoms, and each may be the same or different, and R9 and R10 are each independent. And each of them may be the same or different, and R 11 is any one of a hydrogen atom, an alkyl group, a halogen element, and a cyano group.)

  As a specific example of the alkoxy group in R9 and R10 of the general formula (2), a linear or branched alkyl group having 1 to 8 carbon atoms exemplified in R1 and R2 is preferable, and the carbon number is 1 A linear alkyl group of ˜5 is more preferred.

  Specific examples of the alkyl group in R9 and R10 in the general formula (2) include linear or branched alkyl groups having 1 to 8 carbon atoms exemplified in R1 and R2. In these, a C1-C5 linear alkyl group is preferable.

  Specific examples of the alkyl group in R11 of the general formula (2) include linear or branched alkyl groups having 1 to 8 carbon atoms exemplified in R1 and R2. In these, a C1-C5 linear alkyl group is preferable.

  Specific examples of the halogen element in R11 of the general formula (2) include fluorine, chlorine, bromine, and iodine.

  Specific examples of the sensitizing dye represented by the general formula (2) include, for example, compounds represented by the chemical formula (2-1) to the chemical formula (2-4).

  As the sensitizing dye represented by the general formula (2), a sensitizing dye represented by the following general formula (4) is particularly preferable.

  According to the knowledge of the present inventors, the dye-sensitized solar cell 100 of the present embodiment in which the sensitizing dyes represented by the general formula (1) and the general formula (2) are used together is manufactured under the same conditions. It was found that the photoelectric conversion characteristics were improved as compared with those obtained by using each sensitizing dye alone in the metal oxide layer 13. This is a sensitizing dye represented by the above general formula (1) that is considered to contribute to an improvement in photoelectric conversion efficiency, and a sensitizing dye represented by the above general formula (2) that is considered to contribute to an increase in light absorption. This is thought to be due to the skillful use of.

  In addition to the sensitizing dyes represented by the general formulas (1) and (2), other dyes may be included as the sensitizing dye. Depending on the performance required for the dye-sensitized solar cell, one having a desired light absorption band / absorption spectrum can be applied.

  Specific examples of other dyes include, for example, eosin Y, dibromofluorescein, fluorescein, rhodamine B, pyrogallol, dichlorofluorescein, erythrosine B (erythrocin is a registered trademark), fluorescin, mercurochrome, cyanine dye, merocyanine disazo dye, trisazo Dyes, anthraquinone dyes, polycyclic quinone dyes, indigo dyes, diphenylmethane dyes, trimethylmethane dyes, quinoline dyes, benzophenone dyes, naphthoquinone dyes, perylene dyes, fluorenone dyes, squarylium dyes, Examples thereof include organic dyes such as azulenium dyes, perinone dyes, quinacridone dyes, metal-free phthalocyanine dyes, and metal-free porphyrin dyes. These other dyes preferably have an anchor group (for example, a carboxyl group, a sulfonic acid group, or a phosphoric acid group) that can be bonded to or adsorbed to the metal oxide.

  In addition, for example, an organometallic complex compound can be used as the other dye. Specific examples of the organometallic complex compound include, for example, an ionic coordination bond formed between a nitrogen anion and a metal cation in an aromatic heterocyclic ring, and a nitrogen atom or a chalcogen atom formed between the metal cation. Between a nitrogen atom or a chalcogen atom and a metal cation, and an organometallic complex compound having both a nonionic coordinate bond and an ionic coordinate bond formed by an oxygen or sulfur anion and a metal cation. And organometallic complex compounds having both nonionic coordination bonds formed on the surface. More specifically, metal phthalocyanine dyes such as copper phthalocyanine and titanyl phthalocyanine, metal naphthalocyanine dyes, metal porphyrin dyes, bipyridyl ruthenium complexes, terpyridyl ruthenium complexes, phenanthroline ruthenium complexes, ruthenium bicinchonirate complexes, azo Examples include ruthenium complexes such as ruthenium complexes and quinolinol ruthenium complexes.

  The sensitizing dye may contain one or more additives. Examples of the additive include an association inhibitor that suppresses association of a sensitizing dye, and specifically, a cholic acid compound represented by the chemical formula (5). These may be used alone or in combination of two or more.

(In the above formula (5), R91 represents an alkyl group having an acidic group. R92 represents a group bonded to any of the carbon atoms constituting the steroid skeleton in the chemical formula, and represents a hydroxyl group, a halogen group, an alkyl group, an alkoxy group. A group, an aryl group, a heterocyclic group, an acyl group, an acyloxy group, an oxycarbonyl group, an oxo group, an acidic group, or a derivative thereof, which may be the same or different, and t is 1 or more. (It is an integer of 5 or less. The bond between the carbon atoms constituting the steroid skeleton in the chemical formula may be a single bond or a double bond.)

  The method for supporting the sensitizing dye on the metal oxide layer 13 is not particularly limited. Specific examples thereof include a method of immersing the metal oxide layer 13 in a solution containing a sensitizing dye, a method of applying a solution containing a sensitizing dye to the metal oxide layer 13 and the like. The solvent of the sensitizing dye-containing solution used here is appropriately selected from known solvents such as water, ethanol-based solvent, nitrile-based solvent, and ketone-based solvent, depending on the solubility or compatibility of the sensitizing dye to be used. Can be selected.

  Here, when the metal oxide layer 13 is formed by the cathodic electrodeposition method, the formation of the metal oxide layer 13 and the dye loading are simultaneously performed by using an electrolytic solution containing a metal salt and a sensitizing dye. It is also possible to immediately form the dye-supported metal oxide electrode 14 in which the dye-sensitive material is supported (adsorbed) on the metal oxide surface of the metal oxide layer 13. The electrolysis conditions may be appropriately set according to the characteristics of the material used in accordance with a conventional method. For example, when the dye-supported metal oxide electrode 14 made of ZnO and a sensitizing dye is formed, the reduction electrolysis potential is about -0.8 to -1.2 V (vs. Ag / AgCl), and the pH is 4 to 9. The bath temperature of the electrolyte solution is preferably about 0 to 100 ° C. Further, the metal ion concentration in the electrolytic solution is preferably about 0.5 to 100 mM, and the dye concentration in the electrolytic solution is preferably about 50 to 500 μM. Further, in order to further improve the photoelectric conversion characteristics, the sensitizing dye may be once desorbed from the metal oxide layer 13 on which the sensitizing dye is supported, and then another sensitizing dye may be re-adsorbed. .

  The working electrode 11 (metal oxide electrode 14) may have an intermediate layer between the conductive surface 12a of the base 12 and the metal oxide layer 13. Although the material of an intermediate | middle layer is not specifically limited, For example, the metal oxide etc. which were demonstrated by said transparent conductive film 12a are preferable. The intermediate layer is formed by depositing or depositing a metal oxide on the conductive surface 12a of the substrate 12 by a known method such as vapor deposition, CVD, spraying, spin coating, dipping, or electrodeposition. Can be formed. Note that the intermediate layer preferably has translucency, and more preferably has conductivity. The thickness of the intermediate layer is not particularly limited, but is preferably about 0.1 to 5 μm.

  The metal oxide layer 13 (metal oxide electrode 14) on which the sensitizing dyes represented by the general formulas (1) and (2) are supported (adsorbed) has an ultraviolet-visible absorption spectrum (UV-vis spectrum). ) In the measurement, the absorption maximum intensity of the light absorption peak derived from the sensitizing dye represented by the general formula (2) is supported by the sensitizing dye represented by the general formula (2) alone on the metal oxide layer ( When adsorbed), the absorption maximum intensity of the light absorption peak derived from the sensitizing dye represented by the general formula (2) is preferably in the range of 50% or more and less than 90%. By using the metal oxide electrode 14 in which the sensitizing dyes represented by the general formulas (1) and (2) are in such a supported state (adsorption state), each sensitizing dye was used alone. Compared to the case, the dye-sensitized solar cell 100 with improved photoelectric conversion characteristics can be realized.

  The counter electrode 21 functions as a positive electrode for the external circuit. The counter electrode 21 includes a base body 22 having a conductive surface 22 a, and is disposed so as to face the metal oxide layer 13 of the working electrode 11. As the base body 22 and the conductive surface 22a, well-known ones can be appropriately employed as in the case of the base body 12 and the conductive surface 12a. For example, in addition to the base body 12 having conductivity, a transparent conductive material is formed on the base body 12. A film having a film 12a, and a film made of a metal such as platinum, gold, silver, copper, aluminum, indium, molybdenum, titanium, rhodium, ruthenium, or magnesium, carbon, or a conductive polymer is further formed on the transparent conductive film 12a of the substrate 12. What was formed can be used. Note that, as described above, in the present embodiment, since the organic solvent-free electrolyte that can exhibit excellent photoelectric conversion characteristics without using platinum for the counter electrode is employed, the conductive base 12 or When a relatively inexpensive counter electrode such as one having a transparent conductive film 12a on the substrate 12 is used, the advantage over the prior art becomes significant.

  As the electrolyte 31, a redox electrolyte having a redox pair, a semi-solid electrolyte obtained by gelling the redox electrolyte, or a film formed of a p-type semiconductor solid hole transport material, or the like, which is generally used in batteries, solar cells, etc., is appropriately used. Can be used.

Examples of the redox electrolyte include I ⁻ / I ₃ ⁻ system, Br ⁻ / Br ₃ ⁻ system, and quinone / hydroquinone system. Specifically, a combination of an iodide salt and a simple substance of iodine, a combination of a bromide salt and bromine, a combination of a halide salt and a simple substance of halogen, or the like.

  Examples of the halide salts include cesium halides, quaternary alkyl ammonium halides, imidazolium halides, thiazolium halides, oxazolium halides, quinolinium halides, pyridinium halides, and the like. Is mentioned. More specifically, as these iodide salts, for example, cesium iodide, tetraethylammonium iodide, tetrapropylammonium iodide, tetrabutylammonium iodide, tetrapentylammonium iodide, tetrahexylammonium iodide, Quaternary alkylammonium iodides such as tetraheptylammonium iodide or trimethylphenylammonium iodide; imidazolium iodides such as 3-methylimidazolium iodide or 1-propyl-2,3-dimethylimidazolium iodide 3-ethyl-2-methyl-2-thiazolium iodide, 3-ethyl-5- (2-hydroxyethyl) -4-methylthiazolium iodide or 3-ethyl-2-methylbenzothia Zorium iodide, etc. Thiazolium iodides, oxazolium iodides such as 3-ethyl-2-methyl-benzoxazolium iodide, and quinolinium iodides such as 1-ethyl-2-methylquinolinium iodide And pyridinium iodides. Examples of the bromide salt include quaternary alkyl ammonium bromide. Among the combinations of halide salts and simple halogens, combinations of at least one of the above-described iodide salts and simple iodine are preferable.

  The redox electrolyte may be, for example, a combination of an ionic liquid and a halogen simple substance. In this case, the above-described halide salt and the like may be further included. What is generally used in a battery, a solar cell, etc. can be used suitably as an ionic liquid, and it does not specifically limit. Specific examples of the ionic liquid include, for example, “Inorg. Chem.” 1996, 35, p 1168 to 1178, “Electrochemistry” 2002, 2, p 130 to 136, JP-A-9-507334, or JP-A-8 Examples disclosed in JP-A No. 259543.

  The ionic liquid is preferably a salt having a melting point lower than room temperature (25 ° C.), or a salt that has a melting point higher than room temperature and liquefies at room temperature by dissolving with other molten salts. Specific examples of such an ionic liquid include the following anions and cations.

  Examples of the cation of the ionic liquid include ammonium, imidazolium, oxazolium, thiazolium, oxadiazolium, triazolium, pyrrolidinium, pyridinium, piperidinium, pyrazolium, pyrimidinium, pyrazinium, triazinium, phosphonium, sulfonium, carbazolium, indolium, and their Derivatives. These may be used alone or in combination. Specific examples include 1-methyl-3-propylimidazolium, 1-butyl-3-methylimidazolium, 1,2-dimethyl-3-propylimidazolium, 1-ethyl-3-methylimidazolium, and the like. .

Examples of the anion of the ionic liquid include metal chlorides such as AlCl ₄ ⁻ or Al ₂ Cl ₇ ⁻ , PF ₆ ⁻ , BF ₄ ⁻ , CF ₃ SO ₃ ⁻ , N (CF ₃ SO ₂ ) ₂ ⁻ , Fluorine-containing ions such as F (HF) _n ⁻ or CF ₃ COO ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ , C ₆ H ₁₁ COO ⁻ , CH ₃ OSO ₃ ⁻ , CH ₃ OSO ₂ ⁻ , CH ₃ SO Non-fluorine compound ions such as ₃ ⁻ , CH ₃ SO ₂ ⁻ , (CH ₃ O) ₂ PO ₂ ⁻ , N (CN) ₂ ⁻ or SCN ⁻ , and halide ions such as iodide ions or bromide ions can be mentioned. . These may be used alone or in combination. Among these, iodide ions are preferable as the anions of the ionic liquid.

  Even if the electrolyte 31 is a liquid electrolyte (electrolytic solution) in which the above-described redox electrolyte is dissolved, dispersed or suspended in a solvent, the solid polymer electrolyte in which the above-described redox electrolyte is held in a polymer substance. It may be. Further, it may be a quasi-solid (paste-like) electrolyte containing a redox electrolyte and a particulate conductive carbon material such as carbon black. Note that in a quasi-solid electrolyte containing a conductive carbon material, the conductive carbon material has a function of catalyzing the oxidation-reduction reaction, and therefore the halogen may not be contained in the electrolyte.

  The electrolyte 31 may include an organic solvent that dissolves or disperses the above-described halide salt, ionic liquid, and the like. Examples of the organic solvent include electrochemically inert solvents such as hexane, benzene, toluene, quinoline, diethyl ether, chloroform, ethyl acetate, tetrahydrofuran, methylene chloride, acetone, acetonitrile, methoxyacetonitrile, propio. Nitrile, butyronitrile, benzonitrile, 3-methoxypropionitrile, valeronitrile, N, N-dimethylformamide, dimethyl sulfoxide, sulfolane, acetic acid, formic acid, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, pen Tanol, methyl ethyl ketone, dimethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, ethylene glycol monoalkyl ether, propylene glycol Monoalkyl ether, polyethylene glycol monoalkyl ether, polypropylene glycol monoalkyl ether, ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, glycerin, dioxane, 1,4-dioxane, ethylene glycol dialkyl ether, propylene glycol dialkyl ether, polyethylene glycol Dialkyl ether, polypropylene glycol dialkyl ether, N-methylpyrrolidone, γ-butyrolactone, α-methyl-γ-butyrolactone, β-methyl-γ-butyrolactone, γ-valerolactone, 3-methyl-γ-valerolactone, etc. .

  The electrolyte 31 may contain various additives depending on the required performance. As the additive, those generally used in batteries, solar cells and the like can be appropriately used. Specific examples thereof include, for example, p-type conductive polymers such as polyaniline, polyacetylene, polypyrrole, polythiophene, polyphenylene, polyphenylene vinylene, and derivatives thereof; imidazolium ions, pyridinium ions, triazolium ions, derivatives thereof, and halogen ions. Examples include, but are not limited to, a molten salt comprising a combination of the following: a gelling agent; an oil gelling agent; a dispersant; a surfactant;

  The method for disposing the electrolyte 31 between the working electrode 11 and the counter electrode 21 is not particularly limited, and can be performed using various known methods. In addition, the electrolyte 31 may be used individually by 1 type, or may use 2 or more types together.

  When the working electrode 11 is irradiated with light (sunlight or ultraviolet light, visible light, or near infrared light equivalent to sunlight), the dye-sensitized solar cell 100 absorbs the light. The excited dye injects electrons into the metal oxide layer 13. The injected electrons move to the adjacent conductive surface 12a and then reach the counter electrode 21 via an external circuit. On the other hand, the electrolyte 31 is oxidized so that the oxidized dye is returned to the ground state (reduced) as the electrons move. The oxidized electrolyte 31 is reduced by receiving the electrons. As described above, the movement of electrons between the working electrode 11 and the counter electrode 21 and the accompanying oxidation-reduction reaction of the electrolyte 31 are repeated, whereby continuous movement of electrons occurs, and photoelectric conversion is constantly performed. Is done.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited to these.

Example 1
The dye-sensitized solar cell 100 described in the above embodiment was manufactured by the following procedure.

First, the working electrode 11 was produced according to the following procedure.
First, a conductive glass substrate (FTO) having a length of 2.0 cm, a width of 1.5 cm, and a thickness of 1.1 mm was prepared as the base 12 having the conductive surface 12a. Subsequently, a masking tape having a thickness of 70 μm is applied to the conductive surface 12a so as to enclose a square of 0.5 cm in length × 0.5 cm in width, and 3 cm ^{3 of} metal oxide slurry is uniformly formed on this portion. It was applied and dried. As the metal oxide slurry, zinc oxide powder (average particle size 20 nm; FINEX-50 manufactured by Sakai Chemical Industry Co., Ltd.) is used so as to be 10% by weight, and Triton X-100 (Triton is a registered trademark) as a nonionic surfactant. ) Was prepared by suspending in water to which 1 drop was added. Subsequently, the masking tape on the conductive surface 12a is peeled off, and the conductive glass substrate coated with the metal oxide slurry is baked at 450 ° C. in an electric furnace to form a metal oxide layer 13 having a thickness of about 2 μm. did.

  Subsequently, the sensitizing dye represented by the above formula (3) (D149, manufactured by Mitsubishi Paper Industries, Ltd.) 0.25 mM, the sensitizing dye 0.05 mM represented by the above formula (4), and deoxycholic acid 3 mM. Were dissolved in absolute ethanol to prepare a sensitizing dye-containing solution of Example 1.

D149

  And said metal oxide layer 13 is R.D. T.A. After immersing in the sensitizing dye-containing solution of Example 1 in the dark for 1 h to form a metal oxide electrode 14 by supporting the sensitizing dye on the metal oxide surface of the metal oxide layer 13, washing and drying are performed. As a result, the working electrode 11 was obtained.

Next, the counter electrode 21 was produced according to the following procedure.
First, a conductive glass substrate (FTO) having a length of 2.0 cm, a width of 1.5 cm, and a thickness of 1.1 mm was prepared as the base 22 having the conductive surface 22a. On the conductive surface 22a of this conductive glass substrate, a counter electrode 21 was obtained by forming a 100 nm thick conductive layer made of platinum by sputtering. In addition, two holes (φ1 mm) for injecting an electrolytic solution were formed in advance in the conductive glass substrate.

Subsequently, the electrolyte solution was adjusted in the following procedures.
Dimethylhexylimidazolium iodide (0.6 mol / dm ³ ), lithium iodide (0.1 mol / dm ³ ) and iodine (0.05 mol / dm ³ ) are added to acetonitrile so that each has a predetermined concentration. The electrolyte solution was prepared by adding.

Then, the dye-sensitized solar cell 100 was produced according to the following procedure using the working electrode 11, the counter electrode 21, and the electrolytic solution.
A spacer having a thickness of 50 μm was arranged so as to surround the dye-supported metal oxide electrode 14, and the surface of the working electrode 11 on which the dye-supported metal oxide electrode 14 was formed and the platinum conductive layer of the counter electrode 21 were formed. The working electrode 11 and the counter electrode 21 were bonded to each other through a spacer. Next, the electrolyte 31 was formed by injecting the above-described electrolytic solution from the injection port of the counter electrode 21. Finally, the whole was sealed to obtain the dye-sensitized solar cell 100 of Example 1.

(Example 2)
The sensitizing dye containing the sensitizing dye of Example 2 was processed in the same manner as in Example 1 except that the sensitizing dye D149 was changed to 0.5 mM and the sensitizing dye represented by the above formula (4) was changed to 0.15 mM. The solution was adjusted.
A dye-sensitized solar cell 100 of Example 2 was obtained in the same manner as in Example 1 except that the sensitizing dye-containing solution of Example 2 was used.

(Example 3)
Except for changing the sensitizing dye D149 to 0.5 mM, the sensitizing dye represented by the above formula (4) to 0.03 mM, and deoxycholic acid to 0.5 mM, the same treatment as in Example 1 was carried out. The sensitizing dye-containing solution of Example 3 was prepared.
Except for using the sensitizing dye-containing solution of Example 3, the same treatment as in Example 1 was performed to obtain a dye-sensitized solar cell 100 of Example 3.

(Comparative Example 1)
The sensitizing dye-containing solution of Comparative Example 1 was prepared in the same manner as in Example 1 except that the sensitizing dye represented by the above formula (4) was omitted and deoxycholic acid was changed to 1 mM. .
A dye-sensitized solar cell 100 of Comparative Example 1 was obtained in the same manner as in Example 1 except that the sensitizing dye-containing solution of Comparative Example 1 was used.

(Comparative Example 2)
A sensitizing dye-containing solution of Comparative Example 2 was prepared in the same manner as in Example 1 except that the sensitizing dye D149 was omitted.
A dye-sensitized solar cell 100 of Comparative Example 2 was obtained in the same manner as in Example 1 except that the sensitizing dye-containing solution of Comparative Example 2 was used.

<Measurement of photoelectric conversion characteristics>
The battery characteristics of the obtained dye-sensitized solar cells of Examples 1 to 3 and Comparative Examples 1 and 2 were measured using an AM-1.5 (1000 W / m ² ) solar simulator. As battery characteristics, four items of short-circuit photocurrent (Jsc), open-circuit voltage (Voc), form factor (FF), and photoelectric conversion efficiency (η) were measured. The measurement results are shown in Table 1.
In addition, short circuit photocurrent (Jsc) represents the electric current (per mA / cm < ² >) which flows between both terminals when the output terminal of a dye-sensitized solar cell is short-circuited. Moreover, the open circuit voltage (Voc) represents the voltage (V) between both terminals when the output terminal of a photovoltaic cell module is opened. Further, the form factor (FF) is a value (FF = Pmax / Voc · Jsc) obtained by dividing the maximum output Pmax by the product of the open circuit voltage (Voc) and the photocurrent density (Jsc), and the current-voltage characteristics as a solar cell. It is a parameter that represents the characteristic of the curve. On the other hand, the photoelectric conversion efficiency (η:%) is measured by measuring the response current by sweeping the voltage of the dye-sensitized solar cell with a source meter, and obtaining the maximum output that is the product of the voltage and current obtained by this. The value divided by the light intensity per 1 cm ² is calculated, and this calculation result is multiplied by 100 and displayed as a percentage. That is, the photoelectric conversion efficiency (η) is represented by (maximum output / light intensity per 1 cm ² ) × 100.

  From the results shown in Table 1, it was confirmed that the dye-sensitized solar cells of Examples 1 to 3 have excellent photoelectric conversion efficiency as compared with the dye-sensitized solar cells of Comparative Examples 1 and 2. . From the above, by using together the sensitizing dye represented by the general formula (1) and the sensitizing dye represented by the general formula (2), compared with the case where each is used alone, the photoelectric conversion It was confirmed that the characteristics were enhanced.

<Measurement of UV-visible absorption spectrum>
The obtained UV-visible absorption spectra of the dye-supported metal oxide electrodes of the dye-sensitized solar cells of Examples 1 to 3 and Comparative Examples 1 and 2 were slit with a width of 5 nm using UV-3101PC manufactured by Shimadzu Corporation. Measured under conditions. The measurement results are shown in FIG.

  From the results shown in FIG. 2, the dye-sensitized solar cells of Examples 1 to 3 are derived from the sensitizing dye represented by the above formula (4) in the UV-visible absorption spectrum measurement of the dye-supported metal oxide electrode. The absorption maximum intensity of the light absorption peak is in the range of 50% or more and less than 90% with respect to the absorption maximum intensity of the light absorption peak derived from the sensitizing dye represented by the above formula (4) in Comparative Example 2. Was confirmed.

  Further, from the results shown in FIG. 2, the dye-sensitized solar cell of Example 1 satisfies all the conditions A to C described above, the dye-sensitized solar cell of Example 2 satisfies the above-described conditions B and C, It was confirmed that the dye-sensitized solar cell of Example 3 satisfied the conditions A and C described above.

<Comparison of spectral sensitivity characteristics and short-circuit photocurrent (Jsc)>
FIG. 3 shows the spectral sensitivity characteristics (IPCE) of the dye-sensitized solar cells 100 of Example 1, Comparative Example 1, and Reference Example. In addition, the dye-sensitized solar cell 100 of the reference example has R.D. T.A. This was obtained by treating in the same manner as in Comparative Example 1 except that the sensitizing dye was supported in the dark for 3 minutes.
Table 2 shows the short-circuit photocurrent (Jsc) of the dye-sensitized solar cells of Example 1, Comparative Example 1, and Reference Example. The short-circuit photocurrent (Jsc) is a value calculated from the area of the IPCE.

  From the results shown in FIG. 3 and Table 2, the combined use of the sensitizing dye sensitizing dyes represented by the general formulas (3) and (4) improves the photoelectric conversion characteristics as compared to using them alone. It was confirmed. In particular, considering the comparison between the reference example and the comparative example 1 and the comparison between the reference example and the example 1, further improvement of characteristics is attempted by using the sensitizing dye represented by the general formula (3) alone. It was confirmed that it is particularly effective to use the sensitizing dye sensitizing dyes represented by the general formulas (3) and (4) together.

  In addition, as above-mentioned, this invention is not limited to the said embodiment and Example, In the range which does not deviate from the summary, it can add suitably.

  As described above, the present invention can be widely and effectively used in electronic / electrical materials, electronic / electrical devices related to dye-sensitized solar cells, and various devices, facilities, systems, and the like including them. Further, the present invention can be used widely and effectively in other applications other than the dye-sensitized solar cell, for example, in photoelectric conversion elements such as an optical sensor.

  DESCRIPTION OF SYMBOLS 11 ... Working electrode, 12 ... Base | substrate, 12a ... Conductive surface, 13 ... Metal oxide layer, 14 ... Dye carrying | support metal oxide electrode, 21 ... Counter electrode, 22a ... Conductive surface, 22 ... Base | substrate, 31 ... Electrolyte, 41: spacer, 100: photoelectric conversion element.

Claims (5)

A dye-sensitized solar cell comprising a working electrode having a dye-supported metal oxide electrode in which a dye is supported on a metal oxide layer,
The dye-supported metal oxide electrode has the following general formulas (1) and (2):
(In Formula (1), R1 and R2 are each independently a hydrogen atom, a terminal aryl group, a terminal alkyl group, or a terminal alkoxy group, and at least one of R1 and R2 is a terminal aryl group, a terminal alkyl group. R1 and R2 may be bonded to form a ring, and R3 and R4 are each independently an anchor group or an alkyl group, and at least one of them is a group or a terminal alkoxy group. Anchor group.)
(In Formula (2), R5 to R8 are each independently a linear alkyl group having 4 to 20 carbon atoms, and each may be the same or different, and R9 and R10 are each independent. And each of them may be the same or different, and R 11 is any one of a hydrogen atom, an alkyl group, a halogen element, and a cyano group.)
Comprising a sensitizing dye represented by:
Dye-sensitized solar cell. In the dye-supported metal oxide electrode, the absorption maximum intensity of the light absorption peak derived from the sensitizing dye represented by the general formula (2) in the ultraviolet-visible absorption spectrum measurement is represented by the general formula (2). 50% or more and less than 90% with respect to the absorption maximum intensity of the light absorption peak derived from the sensitizing dye represented by the general formula (2) when the sensitizing dye is supported alone on the metal oxide layer. Within the range of
The dye-sensitized solar cell according to claim 1. The metal oxide layer is a layer substantially made of zinc oxide.
The dye-sensitized solar cell according to claim 1 or 2. The sensitizing dye represented by the general formula (1) is represented by the following general formula (3):
A sensitizing dye represented by
The sensitizing dye represented by the general formula (2) is represented by the following general formula (4):
Is a sensitizing dye represented by
The dye-sensitized solar cell according to any one of claims 1 to 3. And a counter electrode disposed to face the dye-supported metal oxide electrode of the working electrode, and an electrolyte provided between the working electrode and the counter electrode.
The dye-sensitized solar cell according to any one of claims 1 to 4.