JP5418245B2 - Photoelectric conversion element and solar cell - Google Patents

Description

  The present invention relates to a photoelectric conversion element and a solar cell using the same, and more specifically to a dye-sensitized photoelectric conversion element (hereinafter also simply referred to as a photoelectric conversion element) and an organic dye-sensitized solar cell using the same. .

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

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

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

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

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

  It is disclosed that when a compound having a rhodanine skeleton-containing amine structure is used as the dye, an element having high photoelectric conversion efficiency can be obtained (see, for example, Patent Document 1). However, even when these dyes are used, there is a demand for sensitizing dyes having lower conversion efficiency and higher photoelectric conversion efficiency than when using a ruthenium complex.

Japanese Patent Laid-Open No. 2005-63833

Nature, 353, 737 (1991), B.R. O'Regan and M.C. Gratzel

  The present invention has been made in view of the above problems, and has as its object the provision of a photoelectric conversion element and a solar cell using a compound (pigment) that is novel, has good adsorption properties to oxide semiconductors, and has high photoelectric conversion efficiency. There is to do.

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

  1. In a photoelectric conversion element having at least a semiconductor layer in which a dye is supported on a semiconductor, a charge transport layer, and a counter electrode on a conductive support, the dye is represented by the following general formula (1). A photoelectric conversion element comprising a compound.

(In the formula, Ar represents a substituted or unsubstituted arylene group or heterocyclic group. R ₁ and R ₂ each independently represents a substituted or unsubstituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group. R ₁ , R ₂ and Ar may be linked to each other to form a cyclic structure, and R ₃ and R ₄ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, An alkynyl group, an acyl group, an aryl group, an amino group, a cyano group, or a heterocyclic group, wherein R ₅ is a substituted or unsubstituted alkyl group, alkenyl group, alkynyl group, alkoxy group, alkylthio group, alkyl group substituted with X. Represents a seleno group, an amino group, an aryl group or a heterocyclic group, Z represents a heterocyclic group, X represents an acidic group, m represents an integer of 1 or more, and when m ≧ 2, X may be the same or different. Which may be carbon -. Carbon double bond, cis form and a trans form).
2. 2. The photoelectric conversion element as described in 1 above, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (2).

_{(Wherein, Ar, R 1, R 2} , R 3, R 4, X and Z are _Ar in the general formula _{(1), R 1, R} 2, R 3, R 4, X and Z group having the same meaning as R ₆ and R ₇ represent a hydrogen atom, a halogen atom, a hydroxyl group, a thiol group, a cyano group, a substituted or unsubstituted alkyl group, an aryl group, an alkenyl group, an alkynyl group, an acyl group, an alkoxy group, an amino group, or a hetero group. Represents a cyclic group and may be linked to each other to form a cyclic structure, n represents an integer of 0 or more, and when n ≧ 2, R ₆ and R ₇ may be the same or different, Y represents a sulfur atom Represents an oxygen atom or a selenium atom, and the carbon-carbon double bond may be either a cis form or a trans form.)
3. 3. The photoelectric conversion element as described in 2 above, wherein Y in the compound represented by the general formula (2) is a sulfur atom.

4). 4. The photoelectric conversion device as described in 2 or 3 above, wherein R _{4 of the} compound represented by the general formula (2) is a hydrogen atom.

  5. The partial structure represented by said Z is represented by following General formula (3), The photoelectric conversion element of any one of said 1-4 characterized by the above-mentioned.

(Wherein R ₈ and R ₉ represent a hydrogen atom, a substituted or unsubstituted alkyl group, alkenyl group, acyl group, aryl group or heterocyclic group. ** represents a double on the imidazolin-5-one side. (The binding site, * represents a double binding site on the arylamine side.)
6). The partial structure represented by said Z is represented by following General formula (4), The photoelectric conversion element of any one of said 1-4 characterized by the above-mentioned.

(In the formula, R ₉ represents a group having the same meaning as R ₉ in formula (3). ** and * represent the same binding site as ** and * in formula (3).)
7). A photoelectric conversion element comprising a plurality of dyes selected from the dyes included in the photoelectric conversion element according to any one of 1 to 6 above.

  8). 8. The photoelectric conversion element according to any one of 1 to 7, wherein the semiconductor forming the semiconductor layer is titanium oxide.

  9. A solar cell comprising the photoelectric conversion element according to any one of 1 to 8 above.

  According to the present invention, it is possible to provide a photoelectric conversion element and a solar cell using a compound (pigment) which is novel and has a good adsorptivity to an oxide semiconductor and a high photoelectric conversion efficiency.

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

  The best mode for carrying out the present invention will be described in detail below, but the present invention is not limited thereto.

  The present invention relates to a dye-sensitized photoelectric conversion element in which at least a semiconductor layer in which a dye is supported on a semiconductor and a charge transport layer are provided between opposing electrodes, and the general formula (1) is used as the dye. It contains the compound represented by these, It is characterized by the above-mentioned.

  In the present invention, in particular, by incorporating the compound represented by the general formula (1) having high light resistance and high conversion efficiency as the dye of the semiconductor layer formed by supporting the dye on a semiconductor, high efficiency and A highly durable photoelectric conversion element and a solar cell using the photoelectric conversion element are obtained.

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

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

  As shown in FIG. 1, a substrate 1 and a transparent conductive film 2 constituting a conductive support, an oxide semiconductor 3 and a dye 4 constituting a semiconductor layer, an electrolyte 5 serving as a charge transport layer, and platinum constituting a counter electrode 6 8, a transparent conductive film 7, a substrate 1 ′, a partition wall 9, and the like.

  As a photoelectrode, on a substrate 1 (also referred to as a conductive support) to which a transparent conductive film 2 is attached, a semiconductor layer having pores formed by sintering particles of an oxide semiconductor 3 is provided. What adsorb | sucked the pigment | dye 4 on the hole surface is used.

  The present invention relates to a novel compound (pigment), a photoelectric conversion element using the same, and a solar cell.

<< Compound Represented by Formula (1) >>
In the general formula (1), Ar represents a substituted or unsubstituted arylene group or heterocyclic group, and examples of the arylene group include a benzene ring, a naphthalene ring, an anthracene ring, an azulene ring, an acenaphthylene ring, a fluorene ring, a phenanthrene ring, Indene ring, pyrene ring and the like can be mentioned. These groups may be further substituted with a substituent. Preferred are a benzene ring and a naphthalene ring.

  Examples of the heterocyclic group represented by Ar include a furan ring, a thiophene ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, an imidazole ring, a pyrazole ring, a thiazole ring, a quinazoline ring, a carbazole ring, A carboline ring, a diazacarboline ring (in which one of carbon atoms constituting the carboline ring of the carboline ring is replaced by a nitrogen atom), a 1,10-phenanthroline ring, a phthalazine ring, an indole ring, a coumarin ring, Etc. These groups may be further substituted with a substituent. Preferred is a coumarin ring or the like.

Examples of the alkyl group represented by R ₁ and R ₂ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a dodecyl group, and a tridecyl group. , Tetradecyl group, pentadecyl group, and the like. These groups may be further substituted with a substituent.

Examples of the alkenyl group represented by R ₁ and R ₂ include a vinyl group, an allyl group, a butenyl group, and an octenyl group. These groups may be further substituted with a substituent.

Examples of the aryl group represented by R ₁ and R ₂ include phenyl group, naphthyl group, biphenyl group, anthryl group, henanthryl group, azulenyl group, acenaphthylenyl group, fluorenyl group, phenanthrenyl group, indenyl group, pyrenyl group, etc. Is mentioned. These groups may be further substituted with a substituent.

Examples of the heterocyclic group represented by R ₁ and R ₂ include an aromatic heterocyclic group such as a furyl group, a thienyl group, an indolyl group, a coumarinyl group, a pyridyl group, a pyridazinyl group, a pyrimidinyl group, a pyrazinyl group, and a triazinyl group. Group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, dibenzofuranyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group (one of the carbon atoms constituting the carboline ring of the carbolinyl group is a nitrogen atom) And a phthalazinyl group, an indolyl group, a coumarinyl group, and the like. Examples of the saturated heterocyclic group include a pyrrolidinyl group, an imidazolidinyl group, a morpholinyl group, an oxazolidinyl group, and the like. These groups may be further substituted with a substituent.

The alkyl group, alkenyl group, alkynyl group, aryl group, and heterocyclic group represented by R ₃ , R ₄ , and R _{5 have} the same definitions as those described for R ₁ and R ₂ .

Examples of the amino group represented by R ₃ , R ₄ , and R ₅ include an amino group, an ethylamino group, a dimethylamino group, a butylamino group, and a cyclopoentylamino group.

Examples of the acyl group represented by R ₃ , R ₄ , and R ₅ include an acetyl group, a propanoyl group, a butanoyl group, and a tert-butanoyl group.

Examples of the alkoxy group represented by R ₅ include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Examples of the alkylthio group include a methylthio group, an ethylthio group, a propylthio group, an isopropylthio group, a butylthio group, and a tert-butylthio group. Group, hexylthio group and the like, and examples of the alkylseleno group include methylseleno group, ethylseleno group, propylseleno group, butylseleno group, hexylseleno group and the like.

  X substitutes for the alkyl group, alkenyl group, alkynyl group, acyl group, alkoxy group, alkylthio group, alkylseleno group, amino group, aryl group and heterocyclic group.

  X represents an acidic group, and examples of the acidic group include a carboxyl group, a sulfo group, a sulfino group, a sulfinyl group, a phosphoryl group, a phosphinyl group, a phosphono group, a phosphonyl group, a sulfonyl group, and salts thereof. Group and phosphonyl group are preferred.

  Examples of the substituent include alkyl groups (methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, cyclopentyl group, cyclohexyl group. Group), alkenyl group (for example, vinyl group, 1-propenyl group, 2-propenyl group, 2-butenyl group, allyl group, etc.), aryl group (for example, phenyl group, naphthyl group, anthracenyl group, etc.), hydroxyl group, amino group Group, thiol group, cyano group, halogen atom (for example, chlorine atom, bromine atom, fluorine atom, etc.) or heterocyclic group (for example, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, 2-tetrahydrofuranyl group, 2- Tetrahydrothienyl group, 2-tetrahydropyranyl group, 3-te Rahidoropiraniru group). In addition, a plurality of these substituents may be bonded to each other to form a ring.

  Examples of the heterocyclic group represented by Z include those having the same meaning as the heterocyclic group in Ar. Examples of the saturated heterocyclic group include a rhodanine ring, a pyrrole ring, an imidazole ring, a morpholine ring, an oxazozole ring, and a glycine anhydride ring, and these groups may be further substituted with a substituent.

  The above group and the compound of the present invention may further have a substituent, and examples of the substituent include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group). Pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (for example, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (for example, vinyl group, allyl group, etc.) An alkynyl group (eg, ethynyl group, propargyl group, etc.), an aryl group (eg, phenyl group, naphthyl group, etc.), an aromatic heterocyclic group (eg, furyl group, thienyl group, indolyl group, coumarinyl group, pyridyl group, Pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, imidazolyl, pyrazolyl, thiazo Group, quinazolinyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group (indicating that one of the carbon atoms constituting the carboline ring of the carbolinyl group is replaced by a nitrogen atom), a phthalazinyl group, etc.), Saturated heterocyclic group (for example, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy group (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyl) Oxy group etc.), cycloalkoxy group (eg cyclopentyloxy group, cyclohexyloxy group etc.), aryloxy group (eg phenoxy group, naphthyloxy group etc.), alkylthio group (eg methylthio group, ethylthio group, propylthio group, Pentylthio group, hexylchi Group, octylthio group, dodecylthio group, etc.), cycloalkylthio group (for example, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (for example, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (for example, methyloxycarbonyl group, Ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, Methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecyl Ruaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group) 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecyl) Carbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, pro Rucarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, amino Carbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, Naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido) Pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexyl) Sulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc., alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group) , 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group or heteroarylsulfonyl group (for example, phenyls) Sulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino) Group, naphthylamino group, 2-pyridylamino group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom, etc.), fluorinated hydrocarbon group (eg, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group) , Pentafluorophenyl group, etc.), cyano group, nitro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.). These substituents may be further substituted with the above substituents. In addition, a plurality of these substituents may be bonded to each other to form a ring.

<< Compound Represented by Formula (2) >>
Among the compounds represented by the general formula (1), the compound represented by the general formula (2) is preferable because of high photoelectric conversion efficiency.

In the general formula (2), examples of the halogen atom represented by R ₆ and R ₇ include a chlorine atom, a bromine atom, and a fluorine atom. As the substituted or unsubstituted alkyl group, aryl group, alkenyl group, alkynyl group, acyl group, alkoxy group or heterocyclic group, the aryl group, alkenyl group, alkynyl group, acyl group, alkoxy group in the general formula (1) or Synonymous with heterocyclic group.

In the general formula _{(2), Ar, R 1} , R 2, R 3, R 4, X and Z, _Ar in formula _{(1), R 1, R} 2, R 3, and _R 4, X and Z It is synonymous.

<< Partial structure represented by general formula (3) >>
In the general formula (3), the substituted or unsubstituted alkyl group, alkenyl group, acyl group, aryl group or heterocyclic group represented by R ₈ or R ₉ is represented by the general formula (1) or the general formula (2). Are the same as the substituted or unsubstituted alkyl group, alkenyl group, acyl group, aryl group or heterocyclic group.

<< Partial structure represented by general formula (4) >>
In the general formula (4), _{R 9} is the same meaning as _{R 9} in the general formula (3).

  Hereinafter, although the specific example of a compound represented by General formula (1) or (2) or (3) or (4) is shown below, this invention is not limited to these. In this table, the part with the wavy line of the partial structure represents a bonded part bonded by a general formula.

  The compound represented by the general formula (1) can be synthesized by a general synthesis method. Below, the synthesis example of the compound represented by General formula (1) based on this invention is shown.

<Synthesis example>
Synthesis Example 1 (Synthesis of Exemplified Compound 1)

  1 equivalent of thiourea in acetonitrile was cooled to 0 ° C., 1 equivalent of tert-butyric anhydride, 1.1 equivalent of triethylamine, and 0.05 equivalent of dimethylaminopyridine were added and stirred for 4 hours. The reaction solution was concentrated to dryness and treated with a silica column to obtain Compound A.

  A 1,2-dimethoxyethane solution of 1 equivalent of Compound A was cooled to 0 ° C., 2 equivalents of triethylamine, 1 equivalent of ethyl bromoacetate were added, and the mixture was stirred for 1 hour. The reaction solution was concentrated to dryness and treated with a silica column to obtain Compound B.

  A chloroform solution of 1 equivalent of Compound B was cooled to 0 ° C., 1.05 equivalent of trimethyloxonium tetrafluoroborate was added, and the mixture was stirred for 30 minutes. The reaction solution was extracted with chloroform, washed with water, dried over magnesium sulfate, concentrated to dryness with a rotary evaporator, and treated with a silica column to obtain compound C.

  1.1 equivalents of thiohydantoin, 5 equivalents of pyridine, and 0.2 equivalents of dimethylaminopyridine were added to 1 equivalent of a solution of compound C in dichloromethane, and the mixture was stirred at room temperature for 3 hours. The reaction solution was extracted with dichloromethane, washed with water, dried over magnesium sulfate, concentrated to dryness on a rotary evaporator, and treated with a silica column to obtain compound D.

  5 equivalents of pyridine was added to 1 equivalent of a triethylamine solution of Compound D, and the mixture was stirred at 70 ° C. for 2 hours. The reaction solution was extracted with ethyl acetate, washed with water, dried over magnesium sulfate, concentrated to dryness on a rotary evaporator, and treated with a silica column to obtain compound E.

  To an ethanol solution of 1 equivalent of compound E, 1.1 equivalent of ethyl bromoacetate was added, 1.3 equivalent of an ethanol solution of potassium hydroxide was added dropwise, and the mixture was stirred at 70 ° C. for 1 hour. The reaction mixture was concentrated to dryness, extracted with ethyl acetate, washed with water, dried over magnesium sulfate, concentrated to dryness on a rotary evaporator, and treated with a silica column to obtain compound F.

  To an acetic acid solution of 1 equivalent of Compound F, 1.05 equivalent of Compound H and 2 equivalents of ammonium acetate were added and stirred at 100 ° C. for 1 hour. The reaction solution was extracted with acetic acid, washed with water, dried over magnesium sulfate, concentrated to dryness with a rotary evaporator, and treated with a silica column to obtain compound G.

  To a solution of 1 equivalent of Compound G in ethanol / water = 1: 1, 1 equivalent of a 1N aqueous sodium hydroxide solution was added and stirred at 70 ° C. for 1 hour. The reaction mixture was concentrated to dryness, water was added, and 1N hydrochloric acid was added dropwise with stirring so that the reaction mixture had a pH of 5. The reaction solution was extracted with ethyl acetate, washed with water, dried over magnesium sulfate, concentrated to dryness on a rotary evaporator, and treated with a silica column to obtain compound 1.

  The structure of Compound 1 was confirmed by nuclear magnetic resonance spectrum and mass spectrum. Other compounds can be synthesized in the same manner.

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

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

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

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

  In order to support the dye of the present invention on a semiconductor, a method in which a semiconductor which has been dissolved in an appropriate solvent (ethanol or the like) and dried well in the solution is immersed for a long time is generally used.

  When using a plurality of the dyes of the present invention in combination, or in combination with other dyes for sensitization treatment, a mixed solution of each dye may be prepared and used, or a separate solution for each dye Can be prepared and immersed in each solution in order. In the case where a separate solution is prepared for each dye and is prepared by immersing in each solution in order, the effects described in the present invention can be obtained regardless of the order in which the dye is included in the semiconductor. Alternatively, it may be produced by mixing fine particles of semiconductor adsorbing the dye alone.

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

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

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

[Photoelectric conversion element]
The photoelectric conversion element of the present invention is formed by disposing a photoelectrode in which a dye is contained in a semiconductor on a conductive support and a counter electrode through a charge transport layer. Hereinafter, the semiconductor, the photoelectrode, the charge transport layer, and the counter electrode will be described in order.

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

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

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

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

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

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

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

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

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

<< Production of photoelectrode >>
A method for producing a photoelectrode according to the present invention will be described.

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

  As a preferred embodiment of the photoelectrode according to the present invention, a method of forming a semiconductor fine particle on the conductive support by firing is exemplified.

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

  Hereinafter, a method for forming a photoelectrode by firing using semiconductor fine powder, which is preferably used in the present invention, will be described in detail.

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

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

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

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

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

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

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

  As for the film thickness of the semiconductor layer used as the baked material film | membrane which has a porous structure, 10 nm or more is preferable at least, More preferably, it is 500-30000 nm.

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

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

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

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

  Solvents preferably used in dissolving the compound include nitrile solvents such as acetonitrile, alcohol solvents such as methanol, ethanol and n-propanol, ketone solvents such as acetone and methyl ethyl ketone, diethyl ether, diisopropyl ether, tetrahydrofuran, 1, Ether solvents such as 4-dioxane, and halogenated hydrocarbon solvents such as methylene chloride and 1,1,2-trichloroethane, and a plurality of solvents may be mixed. Particularly preferred are acetonitrile, acetonitrile / methanol mixed solvent, methanol, ethanol, acetone, methyl ethyl ketone, tetrahydrofuran and methylene chloride.

(Tensing temperature and time)
It is preferable that the time for immersing the semiconductor-baked substrate in the solution containing the dye of the present invention deeply enters the semiconductor layer (semiconductor film) to sufficiently advance adsorption or the like and sufficiently sensitize the semiconductor. In addition, from the viewpoint of suppressing degradation of the dye produced in the solution by decomposition or the like and hindering the adsorption of the dye, it is preferably 3 to 48 hours under 25 ° C., more preferably 4 to 24 hours. is there. This effect is particularly remarkable when the semiconductor film is a porous structure film. However, the immersion time is a value under the condition of 25 ° C., and is not limited to the above when the temperature condition is changed.

  When immersed, the solution containing the dye of the present invention may be used by heating to a temperature at which it does not boil as long as the dye does not decompose. A preferable temperature range is 5 to 100 ° C., more preferably 25 to 80 ° C., but this is not the case when the solvent boils in the temperature range as described above.

(Charge transport layer)
The charge transport layer is a layer having a function of rapidly reducing the oxidized oxidant and transporting holes injected at the interface with the dye to the counter electrode.

  The charge transport layer according to the present invention has a redox electrolyte dispersion or a p-type compound semiconductor (charge transport agent) as a hole transport material as a main functional component, and can be mixed with a film forming member such as a binder as necessary. Configured.

Examples of the redox electrolyte include I ⁻ / I ₃ ⁻ system, Br ⁻ / Br ₃ ⁻ system, and quinone / hydroquinone system. Such redox electrolyte can be obtained by a conventionally known method, for example, I ^- / I ₃ ^- system electrolyte can be obtained by mixing an ammonium salt of iodine and iodine. These dispersions are called liquid electrolytes when they are in solution, solid polymer electrolytes when dispersed in a polymer that is solid at room temperature, and gel electrolytes when dispersed in a gel-like substance. When a liquid electrolyte is used as the charge transport layer, an electrochemically inert solvent is used as the solvent, for example, acetonitrile, propylene carbonate, ethylene carbonate, or the like is used. Examples of the solid polymer electrolyte include the electrolyte described in JP-A No. 2001-160427, and examples of the gel electrolyte include the electrolyte described in “Surface Science” Vol. 21, No. 5, pages 288 to 293.

  The charge transfer agent preferably has a large band gap so as not to prevent dye absorption. The band gap of the charge transfer agent used in the present invention is preferably 2 eV or more, and more preferably 2.5 eV or more. Further, the ionization potential of the charge transport agent needs to be smaller than the dye adsorption electrode ionization potential in order to reduce the dye hole. Although the preferable range of the ionization potential of the charge transport agent used in the charge transport layer varies depending on the dye used, it is generally preferably 4.5 eV or more and 5.5 eV or less, and more preferably 4.7 eV or more and 5.3 eV or less.

  As the charge transport agent, an aromatic amine derivative having an excellent hole transport capability is preferable. For this reason, photoelectric conversion efficiency can be improved more by comprising a charge transport layer mainly with an aromatic amine derivative. As the aromatic amine derivative, it is particularly preferable to use a triphenyldiamine derivative. Triphenyldiamine derivatives are particularly excellent in the ability to transport holes among aromatic amine derivatives. Moreover, such an aromatic amine derivative may use any of a monomer, an oligomer, a prepolymer, and a polymer, and may mix and use these. Monomers, oligomers, and prepolymers have a relatively low molecular weight, and thus have high solubility in solvents such as organic solvents. For this reason, when forming a charge transport layer by the apply | coating method, there exists an advantage that preparation of charge transport layer material can be performed more easily. Among these, it is preferable to use a dimer or a trimer as the oligomer.

  Specific aromatic tertiary amine compounds include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N′-bis (3- Methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di) -P-tolylaminophenyl) cyclohexane; N, N, N ', N'-tetra-p-tolyl-4,4'-diaminobiphenyl; 1,1-bis (4-di-p-tolylaminophenyl)- 4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N′-diphenyl-N, N′-di (4 -Methoxyphenyl -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadriphenyl; N, N, N- Tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino- (2-diphenylvinyl) Benzene; 3-methoxy-4'-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and two fused aromatic rings described in US Pat. No. 5,061,569 For example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), described in JP-A-4-308688 That triphenylamine units are linked to three starburst 4,4 ', 4 "- tris [N- (3- methylphenyl) -N- phenylamino] triphenylamine (MTDATA) and the like.

  Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  Examples of charge transport agents other than aromatic amine derivatives include thiophene derivatives, pyrrole derivatives, stilbene derivatives, and the like.

  Specific examples of the charge transfer agent are shown below, but the present invention is not limited thereto.

  The charge transport layer is formed by applying the charge transport agent or the above-described p-type semiconductor polymer compound. Or it forms by apply | coating or filling the dispersion of the said redox electrolyte.

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

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

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

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

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

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.

Example [Production of Photoelectric Conversion Element 1]
Titanium oxide paste (anatase type, primary average particle diameter (microscope observation average) 18 nm, polyethylene glycol dispersion) is applied to fluorine-doped tin oxide (FTO) conductive glass substrate by screen printing (application area 5 × 5 mm ² ). did. Coating and drying (3 minutes at 120 ° C.) were repeated three times, and baking was carried out at 200 ° C. for 10 minutes and at 500 ° C. for 15 minutes to obtain a titanium oxide thin film having a thickness of 15 μm. On this thin film, a titanium oxide paste (anatase type, primary average particle diameter (microscope observation average) 400 nm, polyethylene glycol dispersion) was further applied and baked by the same method to form a titanium oxide thin film having a thickness of 5 μm.

Compound 1 of the present invention was dissolved in a mixed solvent of acetonitrile: t-butyl alcohol = 1: 1 to prepare a solution of 5 × 10 ⁻⁴ mol / l. The FTO glass substrate coated and sintered with titanium oxide was immersed in this solution at room temperature for 3 hours for dye adsorption treatment to obtain a semiconductor electrode.

  The charge transport layer (electrolyte) contains 1-methyl-3-butylimidazolium iodide 0.6 mol / l, guanidine thiocyanate 0.1 mol / l, iodine 0.05 mol / l, 4- (t-butyl) pyridine 0 A solution of acetonitrile: valeronitrile = 85: 15 containing 5 mol / l was used. The photoelectric conversion element 1 was produced by assembling with the semiconductive electrode and charge transport layer which were produced previously, and the clamp cell using the glass plate which vapor-deposited platinum and chromium as a counter electrode.

[Production of photoelectric conversion elements 2 to 28]
Photoelectric conversion elements 2 to 28 were produced in the same manner as in the production of the photoelectric conversion element 1 except that the compound 1 was changed to the dye described in Table 1.

[Preparation of photoelectric conversion element 29]
In preparation of the photoelectric conversion element 1, instead of a 5 × 10 ⁻⁴ mol / l solution in which the compound 1 was dissolved in a mixed solvent of acetonitrile: t-butyl alcohol = 1: 1, the compound 1 was converted to acetonitrile: t-butyl alcohol. = 1: 1 solution of 5 × ¹⁰ -4 mol / l dissolved in a mixed solvent and compound 15 acetonitrile: t-butyl alcohol = 1: a solution of 5 × ¹⁰ -4 mol / l dissolved in a mixed solvent of 1 A photoelectric conversion element 29 was produced in the same manner except that the dye solution was mixed in a 1: 1 ratio.

[Production of Photoelectric Conversion Element 30]
In preparation of the photoelectric conversion element 1, instead of a 5 × 10 ⁻⁴ mol / l solution in which the compound 1 was dissolved in a mixed solvent of acetonitrile: t-butyl alcohol = 1: 1, the compound 1 was converted to acetonitrile: t-butyl alcohol. = 1: 5 × ¹⁰ -4 mol / l of the solution and compound 201 mixture was dissolved in a solvent 1 acetonitrile: t-butyl alcohol = 1: a solution of 5 × ¹⁰ -4 mol / l dissolved in a mixed solvent of 1 The photoelectric conversion element 30 was produced in the same manner except that the dye solution was mixed in a 1: 1 ratio.

[Production of Photoelectric Conversion Element 31]
In the production of the photoelectric conversion element 1, the compound 1 is changed to the compound 301, and the charge transfer layer (electrolytic solution) is 1-methyl-3-butylimidazolium iodide 0.6 mol / l, lithium iodide 0.1 mol / l. The photoelectric conversion element 31 was produced in the same manner except that a solution of 3-methoxypropionitrile containing l, iodine 0.05 mol / l, 4- (t-butyl) pyridine 0.5 mol / l was used.

[Production of Photoelectric Conversion Element 32]
A photoelectric conversion element 32 was prepared in the same manner except that the compound 301 was changed to the compound 302 in the production of the photoelectric conversion element 31.

[Production of Photoelectric Conversion Element 33]
A commercially available titanium oxide paste (anatase type, primary average particle diameter (microscope observation average) 18 nm, polyethylene glycol dispersion) is screen printed onto a fluorine-doped tin oxide (FTO) conductive glass substrate (application area 5 × 5 mm ² ). Was applied at 200 ° C. for 10 minutes and 450 ° C. for 15 minutes to obtain a titanium oxide thin film having a thickness of 1.5 μm.

Compound 1 of the present invention was dissolved in a mixed solvent of acetonitrile: t-butyl alcohol = 1: 1 to prepare a solution of 5 × 10 ⁻⁴ mol / l. The FTO glass substrate coated and sintered with titanium oxide was immersed in this solution at room temperature for 3 hours for dye adsorption treatment to obtain a semiconductor electrode.

Subsequently, the aromatic amine derivative 2,2 ′, 7,7′-tetrakis (N, N′-di (4-methoxyphenyl) amine) -9, which is a hole transport material, is mixed with chlorobenzene: acetonitrile = 19: 1 mixed solvent. , 9′-spirobifluorene (OMeTAD) is 0.17 mol / l, N (PhBr) ₃ SbCl ₆ is 0.33 mmol / l as a hole doping agent, and Li [(CF ₃ SO ₂ ) ₂ N] is 15 mmol / l. A hole layer forming coating solution was prepared by dissolving t-Butylpyridine so as to be 50 mmol / l. Then, the hole layer forming coating solution was applied by spin coating on the upper surface of the semiconductor layer on which the photosensitizing dye was adsorbed and bonded to form a charge transport layer. Furthermore, 90 nm of gold was vapor-deposited by a vacuum vapor deposition method, a counter electrode was produced, and the photoelectric conversion element 33 was produced. In the application by the spin coating method described above, the rotation speed of the spin coating was set to 500 rpm.

[Production of Photoelectric Conversion Element 34]
A photoelectric conversion element 34 was produced in the same manner as the photoelectric conversion element 33 except that the compound 1 of the photoelectric conversion element was changed to the compound 302.

[Evaluation of power generation characteristics]
The evaluation test was performed by irradiating 100 mW / cm ² of simulated sunlight from a xenon lamp through an AM filter (AM-1.5) using a solar simulator (manufactured by Eiko Seiki). About each photoelectric conversion element, the current-voltage characteristic was measured at room temperature using the IV tester, and the short circuit current ( _ISC ) and the open circuit voltage ( _VOC ) were calculated _| required.

Next, after short-circuiting the cell and irradiating 120 mW / cm ² of artificial sunlight for 720 hours, current-voltage characteristics were measured in the same manner to determine a short-circuit current (I _SC1 ) and an open-circuit voltage (V _OC1 ).

  The conversion efficiency η is the same as the photoelectric conversion efficiency η, and means the efficiency at which light energy (W) is converted into electrical energy (W) by the solar cell. The photoelectric conversion efficiency (η (%)) was calculated based on the following formula (A).

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

The durability of the conversion efficiency was determined as a value obtained from (η ₁ / η).

  The evaluation results are shown in Table 1.

  From Table 1, the photoelectric conversion element 28 using a dye having a skeleton in which imidazolin-5-one is linked to the heterocyclic group of the present invention is short-circuited compared to the photoelectric conversion element 32 using a comparative dye having a rhodanine skeleton. Improvements were observed in current, open circuit voltage, and conversion efficiency. Further, the conversion efficiency is improved in the photoelectric conversion elements 29 and 30 using a plurality of dyes, and 2,2 ′, 7,7′-tetrakis (N, N′-di (4-methoxy) is added to the charge transport layer. The photoelectric conversion element 33 using (phenyl) amine) -9,9′-spirobifluorene was improved in short-circuit current, open-circuit voltage, and conversion efficiency as compared with the photoelectric conversion element 34. Conversion efficiency improvement was also observed in photoelectric conversion elements 1 to 28 using a dye having a skeleton in which an imidazolin-5-one group is linked to the heterocyclic group of the present invention. In addition, some of the dyes of the present invention have developed aggregation due to intermolecular interaction, and the absorption wavelength has been shifted to a long wave, or the amount of adsorbed dye has increased, so that more wavelengths of light are absorbed. This is also considered to be a factor in improving the conversion efficiency.

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

Claims (9)

In a photoelectric conversion element having at least a semiconductor layer in which a dye is supported on a semiconductor, a charge transport layer, and a counter electrode on a conductive support, the dye is represented by the following general formula (1). A photoelectric conversion element comprising a compound.

(In the formula, Ar represents a substituted or unsubstituted arylene group or heterocyclic group. R ₁ and R ₂ each independently represents a substituted or unsubstituted alkyl group, alkenyl group, alkynyl group, aryl group or heterocyclic group. R ₁ , R ₂ and Ar may be linked to each other to form a cyclic structure, and R ₃ and R ₄ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, An alkynyl group, an acyl group, an aryl group, an amino group, a cyano group, or a heterocyclic group, wherein R ₅ is a substituted or unsubstituted alkyl group, alkenyl group, alkynyl group, alkoxy group, alkylthio group, alkyl group substituted with X. Represents a seleno group, an amino group, an aryl group or a heterocyclic group, Z represents a heterocyclic group, X represents an acidic group, m represents an integer of 1 or more, and when m ≧ 2, X may be the same or different. Which may be carbon -. Carbon double bond, cis form and a trans form). 2. The photoelectric conversion device according to claim 1, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (2).

_{(Wherein, Ar, R 1, R 2} , R 3, R 4, X and Z are _Ar in the general formula _{(1), R 1, R} 2, R 3, R 4, X and Z group having the same meaning as R ₆ and R ₇ represent a hydrogen atom, a halogen atom, a hydroxyl group, a thiol group, a cyano group, a substituted or unsubstituted alkyl group, an aryl group, an alkenyl group, an alkynyl group, an acyl group, an alkoxy group, an amino group, or a hetero group. Represents a cyclic group and may be linked to each other to form a cyclic structure, n represents an integer of 0 or more, and when n ≧ 2, R ₆ and R ₇ may be the same or different, Y represents a sulfur atom Represents an oxygen atom or a selenium atom, and the carbon-carbon double bond may be either a cis form or a trans form.)   The photoelectric conversion element according to claim 2, wherein Y of the compound represented by the general formula (2) is a sulfur atom. The photoelectric conversion element according to claim 2 or 3, wherein R _{4 of the} compound represented by the general formula (2) is a hydrogen atom. The partial structure represented by said Z is represented by following General formula (3), The photoelectric conversion element of any one of Claims 1-4 characterized by the above-mentioned.

(Wherein R ₈ and R ₉ represent a hydrogen atom, a substituted or unsubstituted alkyl group, alkenyl group, acyl group, aryl group or heterocyclic group. ** represents a double on the imidazolin-5-one side. (The binding site, * represents a double binding site on the arylamine side.) The partial structure represented by said Z is represented by following General formula (4), The photoelectric conversion element of any one of Claims 1-4 characterized by the above-mentioned.

(In the formula, R ₉ represents a group having the same meaning as R ₉ in formula (3). ** and * represent the same binding site as ** and * in formula (3).)   A photoelectric conversion element comprising a plurality of dyes selected from the dyes included in the photoelectric conversion element according to claim 1.   The photoelectric conversion element according to claim 1, wherein the semiconductor forming the semiconductor layer is titanium oxide.   It has a photoelectric conversion element of any one of Claims 1-8, The solar cell characterized by the above-mentioned.

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