JP2012043639A - Photoelectric conversion element and dye-sensitized solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion element and a solar cell which are excellent in photoelectric conversion efficiency.SOLUTION: The photoelectric conversion element comprises a substrate, a first electrode, a photoelectric conversion layer formed of a semiconductor layer containing a dye and a semiconductor, a hole transport layer, and a second electrode, in this order. The dye is a compound represented by the following general formula (1).

Description

  The present invention relates to a photoelectric conversion element and a solar cell using the same, and more particularly to a dye-sensitized photoelectric conversion element and a dye-sensitized solar cell using the same.

  In recent years, solar energy has attracted attention as an energy source due to environmental problems.

  And the method of converting into the electrical energy which is the energy form which is easy to utilize using the light and heat of sunlight energy is put into practical use.

  Among these methods, for example, a method of converting sunlight into electric energy is a typical example, and a photoelectric conversion element is used in this method.

  As photoelectric conversion elements, photoelectric conversion elements using inorganic materials such as single crystal silicon, polycrystalline silicon, amorphous silicon, cadmium telluride and indium copper selenide are widely used, and are widely used for so-called solar cells. Yes.

  Solar cells using photoelectric conversion elements using these inorganic materials require a high-purity product such as silicon used as a material that requires an advanced refining process, and the manufacturing process is due to a structure with a multilayer pn junction. There were problems such as complexity, many processes, and high manufacturing costs.

  On the other hand, research on photoelectric conversion elements using organic materials as simpler elements is also underway.

  For example, C.I. W. Tang: A pn-junction organic material obtained by bonding a perylenetetracarboxylic acid derivative, which is an n-type organic dye, and copper phthalocyanine, which is a p-type organic dye, as described in Applied Physics Letters, 48, 183 (1986). A photoelectric conversion element has been reported.

  In an organic photoelectric conversion element, in order to improve the short exciton diffusion length and the thinness of the space charge layer, which are considered to be weak points, the area of the pn junction simply laminating the organic thin film is greatly increased. Attempts to ensure a sufficient number of organic dyes involved in the separation are producing results.

  Also, for example, G. Yu, J .; Gao, J .; C. Humelen, F.M. Wudl and A.W. J. et al. Heeger: As described in Science, 270, 1789 (1996), an n-type electron conductive organic material and a p-type hole conductive polymer are combined in a film to dramatically increase the pn junction portion. Thus, charge separation is performed throughout the film. In 1995, Heeger et al. Proposed a photoelectric conversion element in which a conjugated polymer is a p-type conductive polymer and fullerene is mixed as an electron conductive material.

  Although these photoelectric conversion elements are gradually improving their characteristics, they have not yet been able to behave stably with high conversion efficiency.

  However, in 1991, Gratzel made porous titanium oxide as a compilation of enormous and detailed experiments on the sensitized photocurrent of the dye adsorbed on titanium oxide, and the area of charge separation (number of molecules contributing to charge separation). As a result, a photoelectric conversion element having a stable operation and a high conversion efficiency was successfully produced (for example, see Non-Patent Document 1).

  In this photoelectric conversion element, the dye adsorbed on the surface of the porous titanium oxide is photoexcited, electrons are injected from the dye into the titanium oxide to become dye cations, and the dye receives electrons from the counter electrode through the hole transport layer. As the hole transport layer, an electrolytic solution in which an electrolyte containing iodine is dissolved in an organic solvent is used.

  This photoelectric conversion element, combined with the stability of titanium oxide, has excellent reproducibility, and the scope of research and development is greatly expanded. This photoelectric conversion element is also called a dye-sensitized solar cell and has great expectations and attention. Have been bathed. In this method, it is not necessary to purify an inexpensive metal compound semiconductor such as titanium oxide to a high purity, an inexpensive semiconductor can be used, and usable light extends over a wide visible light range. , It has the advantage that sunlight with a large amount of visible light components can be effectively converted into electricity.

  However, since a ruthenium complex having a resource limitation is used for the photoelectric conversion layer, there is a problem that it is necessary to use an expensive ruthenium complex, and stability over time is not sufficient.

  In addition, as a further problem, since dye-sensitized solar cells operate using an electrolyte as described above, a separate mechanism is required to prevent the electrolyte and iodine from being retained, discharged, or dissipated. Had a point. Furthermore, 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 Patent Document 1).

  Further, a technique using a specific dye having a triarylamine structure (see Patent Document 2) is known.

  However, even when these dyes are used, there is a demand for photoelectric conversion elements having relatively low conversion efficiency and high photoelectric conversion efficiency, and there is a need for sensitizing dyes for forming such photoelectric conversion elements. Yes.

Japanese Patent Laid-Open No. 2005-63833 JP 2009-269987 A

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

  This invention is made | formed in view of the said subject, The objective is to provide the photoelectric conversion element and solar cell which are excellent in photoelectric conversion efficiency.

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

  1. A photoelectric conversion element comprising a substrate, a first electrode, a dye and a semiconductor layer comprising a semiconductor layer containing a semiconductor, a hole transport layer and a second electrode in this order, wherein the dye is represented by the following general formula (1) A photoelectric conversion element characterized by being a compound to be produced.

(In the formula, Ar ₁ and Ar ₂ represent a divalent aromatic hydrocarbon residue, heterocyclic residue, chain hydrocarbon residue, or cyclic hydrocarbon residue which may have a substituent. .

Ar ₃ represents a divalent aromatic hydrocarbon residue or heterocyclic residue which may have a substituent.

X ₀ and X ₁ each independently represents a hydrogen atom or an electron-withdrawing group, and at least one of X ₀ and X ₁ is an electron-withdrawing group.

Ar ₁ , Ar ₂ and Ar ₃ may be connected to each other to form a cyclic structure.

R ₁ represents a hydrogen atom, a halogen atom, a cyano group, or an optionally substituted alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, aryl group or heterocyclic group.

R ₂ represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, which may have a substituent.

R ₃ represents an alkyl group, alkenyl group, alkynyl group, alkoxy group, alkylthio group, alkylseleno group, amino group, aryl group or heterocyclic group having a substituent represented by Z.

The substituent represented by Z is an acidic group, and m represents an integer of 1 or more and 7 or less. When m ≧ 2, Z may be the same or different. The carbon-carbon double bond may be either a cis isomer or a trans isomer. )
2. 2. The photoelectric conversion element as described in 1 above, wherein the electron-withdrawing group in the general formula (1) is a halogen atom or a trihalomethyl group.

3. -R < ₃ >-in the said General formula (1) is the following general formula (A), The said photoelectric conversion element of 1 or 2 characterized by the above-mentioned.

(Y represents a sulfur atom, an oxygen atom or a selenium atom.

R ₄ and R ₅ are a hydrogen atom, a halogen atom, a hydroxyl group, a thiol group, a cyano group, or an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, an aryl group, or a heterocyclic group, which may have a substituent. It represents a cyclic group and may be connected to each other to form a cyclic structure. n represents an integer of 0 or more and 14 or less, and when n ≧ 2, R ₄ and R ₅ may be the same or different. )
4). Y in said general formula (A) is S (sulfur atom), The said photoelectric conversion element of 3 characterized by the above-mentioned.

5. 5. The photoelectric conversion element according to any one of 1 to 4, wherein R ₂ in the general formula (1) is hydrogen.

  6). 6. A dye-sensitized solar cell comprising the photoelectric conversion device according to any one of 1 to 5 above.

  With the above configuration of the present invention, a photoelectric conversion element and a solar cell that are excellent in photoelectric conversion efficiency can be provided.

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

  The present invention is a photoelectric conversion element having a substrate, a first electrode, a dye and a photoelectric conversion layer comprising a semiconductor layer containing a semiconductor, a hole transport layer, and a second electrode in this order, wherein the dye is represented by the above general formula ( It is a compound represented by 1).

  In the present invention, a photoelectric conversion element having high photoelectric conversion efficiency can be obtained by supporting a specific compound represented by the general formula (1) on a semiconductor.

(Photoelectric conversion element)
The photoelectric conversion element of the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view illustrating an example of a photoelectric conversion element.

  As shown in FIG. 1, the photoelectric conversion element 10 includes a substrate 1, a first electrode 2, a photoelectric conversion layer 6, a hole transport layer 7, and a second electrode 8 arranged in this order.

  The photoelectric conversion layer 6 contains a semiconductor and a pigment. Between the 1st electrode 2 and the photoelectric converting layer 6, it is preferable to have the barrier layer 3 for the purpose of a short circuit prevention, sealing, etc. Sunlight enters from the direction of the arrow at the bottom of the figure.

  The manufacture example of the photoelectric conversion element of this invention is shown below. After the barrier layer 3 is deposited and formed on the substrate 1 (also referred to as a conductive support) provided with the first electrode 2, a semiconductor layer made of a semiconductor is formed on the barrier layer 3, and the semiconductor surface is formed on the surface of the semiconductor. The photoelectric conversion layer 6 is formed by adsorbing the dye. Thereafter, the hole transport layer 7 is formed on the photoelectric conversion layer 6.

  The hole transport layer 7 exists on a semiconductor layer made of a semiconductor carrying a sensitizing dye, and a second electrode 8 is attached thereon. Terminals can be attached to the first electrode 2 and the second electrode 8 to extract current.

(Photoelectric conversion layer)
The photoelectric conversion layer according to the present invention comprises a semiconductor layer containing a semiconductor that contains a semiconductor and a dye and carries the dye, and the dye is a compound represented by the general formula (1).

(semiconductor)
As a semiconductor used for the semiconductor layer, silicon, germanium, a compound having a group 3 to group 5, group 13 to group 15 element of a periodic table (also referred to as an element periodic table), metal 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 semiconductor layer, 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. .

  Surface treatment can be carried out by preparing a solution dissolved in an organic solvent as it is when the organic base is liquid, or by immersing the semiconductor according to the present invention in a liquid organic base or organic base solution.

<< Fabrication of semiconductor layer >>
A method for manufacturing the semiconductor layer will be described. In the case where the semiconductor of the semiconductor layer is in the form of particles, the semiconductor layer is preferably manufactured by applying or spraying the semiconductor onto a conductive support. In the case where the semiconductor according to the present invention is in a film form and is not held on the conductive support, it is preferable to produce a semiconductor layer by bonding the semiconductor onto the conductive support.

  As a preferred embodiment of the semiconductor layer, a method of forming the semiconductor layer by firing using fine particles of semiconductor on the conductive support can be mentioned. When the semiconductor according to the present invention is produced by firing, the semiconductor sensitization (adsorption, filling in a porous layer, etc.) treatment with a dye is preferably performed after firing. It is particularly preferable to perform the compound adsorption treatment quickly after the firing and before the water is adsorbed to the semiconductor.

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

(Preparation of coating liquid containing semiconductor fine powder)
First, a coating solution containing fine semiconductor powder is prepared. The finer the primary particle diameter of the semiconductor fine powder, the better. The primary particle diameter is preferably 1 to 5000 nm, more preferably 2 to 100 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 in an inert gas, on the conductive support. A semiconductor layer (also referred to as a semiconductor film) is formed.

  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.

  The semiconductor layer may have any structure, but is preferably a porous structure film (also referred to as a porous layer having voids). When the semiconductor layer is a porous structure film, it is preferable that components such as a hole transport material of the hole transport layer are also present in this void.

  Here, the porosity of the semiconductor layer 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 apparatus such as a mercury porosimeter (Shimadzu pore sizer 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.

  In addition, when the substrate is made of plastic or the like and is inferior in heat resistance, the fine particles and the fine particle-substrate can be fixed by pressurization without performing a baking process at 200 ° C. or higher, or the substrate can be formed by microwaves. Only the semiconductor layer can be heat-treated without heating.

  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, after heat treatment, in order to increase the efficiency of electron injection from the dye to the semiconductor particles by increasing the surface area of the semiconductor particles or increasing the purity in the vicinity of the semiconductor particles, Plating or electrochemical plating using a titanium trichloride aqueous solution may be performed.

(Dye)
The dye according to the present invention is a compound represented by the above general formula (1), and is supported on a semiconductor by a semiconductor sensitization treatment as described below, and is photoexcited to generate an electromotive force when irradiated with light. To get. As an aspect in which the dye is supported on the semiconductor, an aspect in which the dye is adsorbed on the semiconductor surface, or an aspect in which the semiconductor porous structure is filled with the dye when the semiconductor has a porous structure such as a porous structure. Is mentioned.

<< Compound Represented by Formula (1) >>
In the general formula (1), Ar ₁ and Ar ₂ are divalent aromatic hydrocarbon residues, heterocyclic residues, chain hydrocarbon residues, or cyclic hydrocarbon residues which may have a substituent. Represents a group.

Ar ₃ represents a divalent aromatic hydrocarbon residue or heterocyclic residue which may have a substituent.

X ₀ and X ₁ each independently represents a hydrogen atom or an electron-withdrawing group, and at least one of X ₀ and X ₁ is an electron-withdrawing group. In the present invention, the electron-withdrawing group is a substituent having a positive Hammett's substituent constant σp. For example, there are halogen, cyano group, nitro group, halogenated alkyl group and the like.

Ar ₁ , Ar ₂ and Ar ₃ may be connected to each other to form a cyclic structure.

R ₁ represents a hydrogen atom, a halogen atom, a cyano group, or an optionally substituted alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, aryl group or heterocyclic group.

R ₂ represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group which may have a substituent.

R ₃ represents an alkyl group, alkenyl group, alkynyl group, alkoxy group, alkylthio group, alkylseleno group, amino group, aryl group or heterocyclic group having a substituent represented by Z. R ₃ may have a substituent other than Z.

  The substituent represented by Z is an acidic group, and m represents an integer of 1 or more and 4 or less. When m ≧ 2, Z may be the same or different. The carbon-carbon double bond may be either a cis isomer or a trans isomer.

Examples of the divalent aromatic hydrocarbon residue represented by Ar _{1 to} Ar ₃ which may have a substituent include a benzene ring, a naphthalene ring, an anthracene ring, an azulene ring, an acenaphthylene ring, a fluorene ring, and a phenanthrene ring. A divalent group in which a hydrogen atom is removed from an indene ring, a pyrene ring, and the like.

  The divalent aromatic hydrocarbon residue may be further substituted with a substituent.

  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.), A cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), an alkenyl group (eg, vinyl group, allyl group, etc.), an alkynyl group (eg, ethynyl group, propargyl group, etc.), an aryl group (eg, phenyl group, naphthyl group). Etc.), aromatic heterocyclic group (for example, furyl group, thienyl group, indolyl group, coumarinyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, Carbazolyl group, carbolinyl group, diazacar A zolyl group (in which one of the carbon atoms constituting the carboline ring of the carbolinyl group is replaced by a nitrogen atom), a phthalazinyl group, etc., a saturated heterocyclic group (for example, a pyrrolidyl group, an imidazolidyl group, a morpholyl group) , Oxazolidyl group, etc.), alkoxy group (eg, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (eg, cyclopentyloxy group, cyclohexyl). Oxy group etc.), aryloxy group (eg phenoxy group, naphthyloxy group etc.), alkylthio group (eg methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group etc.), cycloalkylthio Group (example For example, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (eg, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (eg, 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, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminos Sulfonyl 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, phenyl) Carbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (eg, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide Groups (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexyl group) Rubonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl 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 groups (eg, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido) , Dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl 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, phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), Mino 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), halogen atom (For example, fluorine atom, chlorine atom, bromine atom, etc.), fluorinated hydrocarbon group (for example, 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.

  Heterocyclic residues include furan ring, thiophene ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, imidazole ring, pyrazole ring, thiazole ring, quinazoline ring, carbazole ring, carboline ring, diazacarboline ring (In which one of the carbon atoms constituting the carboline ring is replaced by a nitrogen atom), 1,10-phenanthroline ring, phthalazine ring, indole ring, coumarin ring, rhodanine ring, thiohydantoin ring, Examples thereof include a divalent group obtained by removing a hydrogen atom from a pyrrole ring, a morpholine ring, an oxazozole ring, a glycine anhydride ring and the like.

  The heterocyclic residue may be further substituted with a substituent. Examples of the substituent include the same substituents as described above.

Examples of the divalent chain hydrocarbon residue which may have a substituent represented by Ar ₁ and Ar ₂ include a hydrogen atom from a chain saturated or unsaturated hydrocarbon having 1 to 10 carbon atoms. And divalent groups excluding.

Examples of the divalent cyclic hydrocarbon residue represented by Ar ₁ and Ar ₂ which may have a substituent include divalent groups in which a hydrogen atom is removed from a cycloalkyl ring having 3 to 10 carbon atoms. Can be mentioned.

Examples of the electron-withdrawing group represented by X ₀ and X ₁ include a halogen group, a trihalomethyl group, a nitro group, a cyano group, an aldehyde group, a carboxy group, a substituted or unsubstituted alkylketo group, and an alkyloxycarbonyl group. It is done.

Examples of the substituent include the substituents exemplified in Ar _{1 to} Ar ₃ .

  Examples of the halogen group include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

  Examples of the trihalomethyl group include a trifluoroethyl group, a trichloromethyl group, a tribromomethyl group, a chlorodifluoromethyl group, a dichlorofluoromethyl group, a bromodichloromethyl group, and a dibromochloromethyl group.

  Examples of the alkylketo group include a methylketo group (acetyl group), an ethylketo group, a propylketo group, a butylketo group, and a tert-butylketo group. Examples of the alkyloxycarbonyl group include a methoxyketo group, an ethoxyketo group, a propoxyketo group, a butoxyketo group, Examples thereof include a tert-butoxyketo group.

Examples of the halogen atom represented by R ₁ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

Examples of the alkyl group represented by R ₁ include methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl, octyl, dodecyl, tridecyl, tetradecyl, pentadecyl. Group, and the like.

  These groups may be further substituted with a substituent.

Examples of the alkenyl group represented by R ₁ 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 alkynyl group represented by R ₁ include a propargyl group and a 3-pentynyl group.

Examples of the alkoxy group represented by R ₁ include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group.

Examples of the amino group represented by R ₁ include an amino group, an ethylamino group, a dimethylamino group, a butylamino group, and a cyclopentylamino group.

Examples of the aryl group represented by R ₁ include a phenyl group, a naphthyl group, and an anthracenyl group.

Examples of the heterocyclic group represented by R ₁ include a furanyl group, a thienyl group, an imidazolyl group, a thiazolyl group, a morphonyl group, and the like.

Represented by R _2, which may have a substituent, an alkyl group, an alkenyl group, an alkynyl group, the aryl group or heterocyclic group may be the same as those used in R _1.

As the alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, aryl group and heterocyclic group represented by R ₃ , the same groups as those described for R ₁ and R ₂ can be used.

Examples of the alkylthio group represented by R ₃ include a methylthio group, an ethylthio group, a propylthio group, an isopropylthio group, a butylthio group, a tert-butylthio group, and a hexylthio group. The alkylseleno group includes a methylseleno group and an ethylseleno group. Propylseleno group, butylseleno group, hexylseleno group and the like.

Z substitutes for the alkyl group, alkenyl group, alkynyl group, alkoxy group, alkylthio group, alkylseleno group, amino group, aryl group or heterocyclic group represented by R ₃ above.

  Z 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. Among these, a carboxyl group, a phosphonium group, and a sulfonium group are preferable.

  m represents an integer of 1 or more and 7 or less, preferably 1 to 4, and particularly preferably 1 to 2.

In addition, as a substituent which can be used for the group which may have a substituent represented by R _{1 to} R ₃ , an alkyl group (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), alkenyl group (for example, vinyl group, 1-propenyl group, 2-propenyl group, 2-butenyl group, allyl group) Group), aryl group (eg phenyl group, naphthyl group, anthracenyl group etc.), hydroxyl group, amino group, thiol group, cyano group, halogen atom (eg 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-tetrahydropyranyl group, etc.). In addition, a plurality of these substituents may be bonded to each other to form a ring.

  In the present invention, among the compounds represented by the general formula (1), those in which the electron withdrawing group in the general formula (1) is a halogen atom or a trihalomethyl group are particularly preferable from the viewpoint of photoelectric conversion efficiency. .

In addition, it is preferable from the viewpoint of photoelectric conversion efficiency that -R _3- in the general formula (1) is the above general formula (A) and that Y in the general formula (A) is a sulfur atom.

  In general formula (A), Y represents a sulfur atom, an oxygen atom or a selenium atom.

R ₄ and R _{5 each} represents a hydrogen atom, a halogen atom, a hydroxyl group, a thiol group, a cyano group, or an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, an aryl group, or a substituent. It represents a heterocyclic group and may be linked together to form a cyclic structure. n represents an integer of 0 or more and 14 or less, and when n ≧ 2, R ₄ and R ₅ may be the same or different.

In the general formula (A), the halogen atom represented by R ₄ and R ₅ , a substituted or unsubstituted alkyl group, an aryl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group or a heterocyclic group is represented by the general formula (1 ) Is the same as the halogen atom represented by R ₁ , a substituted or unsubstituted alkyl group, an aryl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, or a heterocyclic group.

  n represents an integer of 0 or more and 14 or less, preferably 0 to 9, and particularly preferably 0 to 4.

Furthermore, the compound whose R < ₂ > in General formula (1) is hydrogen is preferable from the surface of photoelectric conversion efficiency, and can be used.

(Synthesis of the compound represented by the general formula (1))
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 2 below)

  To a DMF solution of 4,4'-diformyltriphenylamine, 2.5 equivalents of diethyl (4-chlorophenyl) (phenyl) methylphosphonate, 3 equivalents of Na-Ot-butyl were added and stirred at 120 ° C for 1.5 hours. did. Water was added to the reaction solution, 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 A.

  To a toluene solution of Compound A, 1.2 equivalents of phosphorus oxychloride and 3 equivalents of DMF were added and stirred at 60 ° C. for 1 hour. Cold water was added to the reaction mixture, and the mixture was stirred at room temperature for 1 hour, 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 B.

  An acetic acid solution containing Compound B, 1.2 equivalents of thiohydantoin and 3 equivalents of ammonium acetate was stirred at 120 ° C. for 4 hours. Water was added to the reaction mixture, and the mixture was stirred for 1 hour, 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 C.

  To an ethanol solution of Compound C, 1.1 equivalents of bromoacetic acid and 4 equivalents of potassium hydroxide were added and stirred at 70 ° C. for 4 hours. After concentrating and drying with a rotary evaporator, water and ethyl acetate were added, and the organic layer was removed with a separatory funnel acetic acid. An excess amount of 1 mol / l hydrochloric acid was added to the water tank, and the mixture was stirred for 5 minutes, extracted with ethyl acetate, washed with water, dried over magnesium sulfate, concentrated to dryness with a rotary evaporator, and treated with a silica column to obtain compound 2.

  The structure of Compound 2 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.

  Although the specific example of a compound represented by General formula (1) below is shown, 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.

(Semiconductor sensitization treatment)
The total supported amount of the dye of the present invention per 1 m ^{2 of the} semiconductor layer is preferably in the range of 0.01 to 100 mmol, more preferably 0.1 to 50 mmol, and particularly preferably 0.5 to 20 mmol.

  When performing the sensitization treatment, sensitizing dyes may be used alone or in combination, and other compounds (for example, US Pat. No. 4,684,537, US Pat. No. 4,927). No. 721, No. 5,084,365, No. 5,350,644, No. 5,463,057, No. 5,525,440, JP-A-7- 249790, JP-A 2000-150007, etc.) can also be used as a mixture.

  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 a sensitizing dye on a semiconductor, a method in which a semiconductor which is 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 multiple types of sensitizing dyes or other dyes for sensitizing 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.

  When preparing different solutions for each sensitizing dye and immersing them in each solution in order, the order in which the sensitizing dye and the like are included in the semiconductor may be whatever.

  Alternatively, it may be produced by mixing fine particles of semiconductor adsorbing the dye alone. In the case of a semiconductor having a high porosity, it is preferable to complete the adsorption treatment of a sensitizing 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, etc. .

  The semiconductor sensitization treatment is performed by dissolving the sensitizing dye in an appropriate solvent as described above and immersing the substrate obtained by firing the semiconductor 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 be subjected to pressure reduction treatment or heat treatment in advance to remove bubbles in the film. Such treatment allows the sensitizing dye to enter 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 sensitizing dye is not particularly limited as long as it can dissolve the sensitizing dye 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 sensitizing treatment such as adsorption of a sensitizing dye, it is preferable to deaerate and purify in advance.

  Solvents preferably used for dissolving the sensitizing dye 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 1,4-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 substrate on which the semiconductor is baked in the solution containing the sensitizing dye penetrates deeply into the semiconductor layer (semiconductor film) to sufficiently advance adsorption and the like to 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.

  In soaking, the solution containing the dye of the present invention may be heated to a temperature that 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.

(Hole transport layer)
The hole transport layer is a layer responsible for the function of reducing the oxidized form of the dye after absorbing light and injecting electrons into the semiconductor, and transporting the holes injected at the interface with the dye to the second electrode.

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

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 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.

  By constituting the charge transport layer mainly with an aromatic amine derivative, the photoelectric conversion efficiency can be further improved.

  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 p-type semiconductor 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.

  The hole transport layer is formed by applying and drying the coating liquid containing the charge transport agent or the p-type semiconductor polymer compound, or the dispersion containing the redox electrolyte is applied to the photoelectric conversion layer. It is formed by filling the space for the hole transport layer (charge transport layer).

(substrate)
The substrate is provided on the light incident direction side, and from the viewpoint of photoelectric conversion efficiency of the photoelectric conversion element, the light transmittance is preferably 10% or more, more preferably 50% or more, and particularly 80% to 100%. % Is preferred.

  The light transmittance is the total light transmittance in the visible light wavelength region measured by a method according to “Testing method of total light transmittance of plastic-transparent material” of JIS K 7361-1 (corresponding to ISO 13468-1). Say.

  The material, shape, structure, thickness, hardness and the like of the substrate can be appropriately selected from known ones, but preferably have high light transmittance as described above.

  Examples of the substrate include polyester resin films such as polyethylene terephthalate (PET), polyethylene naphthalate, and modified polyester, polyolefins such as polyethylene (PE) resin film, polypropylene (PP) resin film, polystyrene resin film, and cyclic olefin resin. Resin films, vinyl resin films such as polyvinyl chloride and polyvinylidene chloride, polyvinyl acetal resin films such as polyvinyl butyral (PVB), polyether ether ketone (PEEK) resin films, polysulfone (PSF) resin films, polyether sal Hong (PES) resin film, polycarbonate (PC) resin film, polyamide resin film, polyimide resin film, acrylic resin film, triacetyl cellulose Loin (TAC) resin film, and the like. In addition to these resin films, an inorganic glass film may be used as the substrate.

  Any resin film having a transmittance of 80% or more at a visible wavelength (380 to 780 nm) can be particularly preferably applied to the present invention.

  Among them, from the viewpoint of transparency, heat resistance, ease of handling, strength and cost, it is preferably a biaxially stretched polyethylene terephthalate film, a biaxially stretched polyethylene naphthalate film, a polyethersulfone film, or a polycarbonate film, and biaxially stretched. More preferred are polyethylene terephthalate films and biaxially stretched polyethylene naphthalate films.

  These substrates can be subjected to a surface treatment or an easy-adhesion layer in order to ensure wettability and adhesion of the coating solution.

  A conventionally well-known technique can be used about a surface treatment or an easily bonding layer. For example, the surface treatment includes surface activation treatment such as corona discharge treatment, flame treatment, ultraviolet treatment, high frequency treatment, glow discharge treatment, active plasma treatment, and laser treatment.

  Examples of the easy adhesion layer include polyester, polyamide, polyurethane, vinyl copolymer, butadiene copolymer, acrylic copolymer, vinylidene copolymer, and epoxy copolymer.

  The thickness of the substrate is preferably 1 to 1000 μm, and more preferably 10 to 100 μm.

(First electrode)
The first electrode is disposed between the substrate and the photoelectric conversion layer.

  As the first electrode, one having a light transmittance of 80% or more, more preferably 90% or more is preferably used. The light transmittance is the same as that described in the description of the substrate.

  The first electrode is provided on one surface that is opposite to the light incident direction of the substrate.

As an example of the material for forming the first electrode, it is preferable to use a metal (for example, platinum, gold, silver, copper, aluminum, rhodium, indium) or a metal oxide, for example, SnO ₂ , CdO, ZnO, CTO. Examples include CdSnO ₃ , Cd ₂ SnO ₄ , CdSnO ₄ , In ₂ O ₃ , CdIn ₂ O _{4, and the} like.

  Silver is preferably used as the metal, and a grid-patterned film having openings or a film in which fine particles or nanowires are dispersed and applied is preferably used in order to impart light transmittance.

  The metal oxide is preferably a composite (dope) material obtained by adding one or more selected from Sn, Sb, F and Al to the above metal oxide.

Of these, conductive metal oxides such as In ₂ O ₃ (ITO) doped with Sn, SnO ₂ doped with Sb, and SnO ₂ (FTO) doped with F are preferably used, from the viewpoint of heat resistance. FTO is most preferred.

  What has a 1st electrode on a board | substrate is called an electroconductive support body here.

  The film thickness of the conductive support is preferably in the range of 0.1 mm to 5 mm.

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

  The preferable range of the light transmittance of the conductive support is the same as the preferable range of the light transmittance of the substrate.

(Barrier layer)
The photoelectric conversion element of the present invention preferably has a barrier layer positioned between the first electrode and the semiconductor layer as a short-circuit prevention means.

  As described below, the barrier layer and the photoelectric conversion layer are preferably porous. In this case, the barrier layer has a porosity of C [%] and the semiconductor layer has a porosity of D [ %], The D / C is, for example, preferably about 1.1 or more, more preferably about 5 or more, and still more preferably about 10 or more.

  Thereby, a barrier layer and a semiconductor layer can exhibit those functions more suitably, respectively.

  More specifically, the porosity C of the barrier layer is, for example, preferably about 20% or less, more preferably about 5% or less, and further preferably about 2% or less. That is, the barrier layer is preferably a dense layer. Thereby, the said effect can be improved more.

  The average thickness (film thickness) of the barrier layer is, for example, preferably about 0.01 to 10 μm, and more preferably about 0.03 to 0.5 μm. Thereby, the said effect can be improved more.

The constituent material of this barrier layer is not particularly limited, for example, zinc, niobium, tin, titanium, vanadium, indium, tungsten, tantalum, zirconium, molybdenum, manganese, iron, copper, nickel, iridium, rhodium, chromium, Ruthenium or oxides thereof, and perovskites such as strontium titanate, calcium titanate, barium titanate, magnesium titanate, strontium niobate, or complex oxides or oxide mixtures thereof, CdS, CdSe, TiC, Si One kind or a combination of two or more kinds of various metal compounds such as ₃ N ₄ , SiC and BN can also be used.

  In particular, when the hole transport layer is a p-type semiconductor, a metal having a work function smaller than that of the hole transport layer and having a Schottky contact is used when a metal is used for the barrier layer. When a metal oxide is used for the barrier layer, it is preferable that the barrier layer is in ohmic contact with the transparent conductive layer and the energy level of the conduction band is lower than that of the porous semiconductor layer 4.

  At this time, the efficiency of electron transfer from the porous semiconductor layer (photoelectric conversion layer) to the barrier layer can be improved by selecting an oxide.

  Among these, those having electrical conductivity equivalent to that of the semiconductor layer (photoelectric conversion layer) are preferable, and those mainly composed of titanium oxide are more preferable.

(Second electrode)
The 2nd electrode should just have electroconductivity, and arbitrary electroconductive materials are used.

  Even an insulating material can be used if a conductive material layer is provided on the side facing the hole transport layer.

  It is preferable that the contact property with the hole transport layer is good. Further, it is preferable that the work function difference with the hole transport layer is small and chemically stable. As such a material, a metal thin film such as gold, silver, copper, aluminum, or platinum, or an organic conductor such as carbon black or a conductive polymer can be used.

(Solar cell)
The dye-sensitized solar cell of the present invention has the photoelectric conversion element described above.

  The dye-sensitized solar cell of the present invention comprises the above-described photoelectric conversion element, is optimally designed and circuit designed for sunlight, and is optimally photoelectrically converted when sunlight is used as a light source. It has a structure.

  That is, the semiconductor is dye-sensitized and can be irradiated with sunlight. When configuring the solar cell of the present invention, it is preferable that the photoelectric conversion layer, the hole transport layer, and the second electrode are housed in a case and sealed, or the whole is resin-sealed.

  When the solar cell of the present invention is irradiated with sunlight or an electromagnetic wave equivalent to sunlight, the dye supported on the semiconductor is excited by absorbing the irradiated light or electromagnetic wave.

  Electrons generated by excitation move to the semiconductor, and then move to the second electrode via the conductive support and the external load, and are supplied to the hole transporting material of the hole transporting layer.

  On the other hand, the dye that has moved electrons to the semiconductor is an oxidant, but is reduced by the supply of electrons from the second electrode via the hole transport material of the hole transport layer, and the original state is reduced. At the same time, the hole transport material of the hole transport layer is oxidized and returned to a state where it can be reduced again by the electrons supplied from the second electrode. In this way, electrons flow and the solar cell 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 size (microscope observation average) 18 nm, polyethylene glycol dispersion) is applied to fluorine-doped tin oxide (FTO, first electrode) conductive glass substrate by screen printing (coating area 5 × 5 mm ² ). Coating and drying (at 120 ° C. for 3 minutes) were repeated three times, followed by baking 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 size (microscope observation average) 400 nm, polyethylene glycol dispersion) is further applied and fired in the same manner to form a titanium oxide thin film having a thickness of 1.5 μm. did.

Compound 2 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 the above titanium oxide is immersed in this solution at room temperature for 3 hours to perform dye adsorption treatment to form a photoelectric conversion layer composed of a semiconductor layer. A semiconductor electrode having a conversion layer was obtained.

  The charge transport layer (hole transport layer) (electrolyte) includes 1-methyl-3-butylimidazolium iodide 0.6 mol / l, guanidine thiocyanate 0.1 mol / l, iodine 0.05 mol / l, 4- ( A solution of acetonitrile: valeronitrile = 85: 15 containing 0.5 mol / l of t-butyl) pyridine was used. The photoelectric conversion element 1 was produced by assembling the semiconductive electrode produced previously and the charge transport layer with a clamp cell, using a glass plate on which platinum and chromium (second electrode) were deposited on the counter electrode.

[Production of photoelectric conversion elements 2 to 42]
In the production of the photoelectric conversion element 1, photoelectric conversion elements 2 to 42 were produced in the same manner except that the compound 2 was changed to the dye described in Table 1.

[Preparation of Photoelectric Conversion Element 43]
In preparation of the photoelectric conversion element 1, instead of a solution of 5 × 10 ⁻⁴ mol / l in which the compound 2 was dissolved in a mixed solvent of acetonitrile: t-butyl alcohol = 1: 1, the compound 2 was converted into acetonitrile: t-butyl alcohol. = 1: 1 solution of 5 × ¹⁰ -4 mol / l dissolved in a mixed solvent and acetonitrile following compounds 301: t-butyl alcohol = 1: ^10-4 mol / l 5 × dissolved in a mixed solvent of 1 A photoelectric conversion element 43 was produced in the same manner except that the solution was changed to a dye solution mixed at a ratio of 1: 1.

[Production of Photoelectric Conversion Element 44]
In preparation of the photoelectric conversion element 1, instead of a 5 × 10 ⁻⁴ mol / l solution in which the compound 2 was dissolved in a mixed solvent of acetonitrile: t-butyl alcohol = 1: 1, the compound 4 was converted to acetonitrile: t-butyl alcohol. = 1: 5 × ¹⁰ -4 mol / l of solution and compound 126 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 A photoelectric conversion element 44 was produced in the same manner except that the dye solution was mixed in a 1: 1 ratio.

[Production of Photoelectric Conversion Element 45 (Comparative Example)]
In the production of the photoelectric conversion element 1, the compound 2 is changed to the compound 401, and the charge transfer layer (electrolytic solution) is 1-methyl-3-butylimidazolium iodide 0.6 mol / l, lithium iodide 0.1 mol / l. A photoelectric conversion element 45 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 46 (Comparative Example)]
Photoelectric conversion element 46 was produced in the same manner except that compound 401 was changed to compound 402 in the production of photoelectric conversion element 45.

[Preparation of Photoelectric Conversion Element 47]
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 2 μm.

Compound 2 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 with titanium oxide and sintered was immersed in this solution at room temperature for 3 hours to perform a dye (compound 2) adsorption treatment to obtain a semiconductor electrode.

Subsequently, the aromatic amine derivative 2,2 ′, 7,7′-tetrakis (N, N′-di (4-methoxyphenyl) amine) −, which is a hole transport material, is mixed in a mixed solvent of chlorobenzene: acetonitrile = 19: 1. 9,9′-spirobifluorene (Spiro-OMeTAD) 0.17 mol / l, N (PhBr) ₃ SbCl ₆ 0.33 mmol / l, Li [(CF ₃ SO ₂ ) ₂ N] as a hole doping agent A coating solution for forming a hole transport layer in which 15 mmol / l and t-Butylpyridine were dissolved to 50 mmol / l was prepared. Then, the hole transport layer forming coating solution was applied to the upper surface of the semiconductor layer on which the dye was adsorbed and bonded by spin coating to form a hole transport layer. Furthermore, 90 nm of gold was vapor-deposited by a vacuum vapor deposition method, a counter electrode (second electrode) was produced, and a photoelectric conversion element 47 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 48 (Comparative Example)]
A photoelectric conversion element 48 was produced in the same manner as the photoelectric conversion element 46 except that the compound 2 of the photoelectric conversion element 47 was changed to the compound 401.

[Evaluation of power generation characteristics]
The following evaluation was performed using the photoelectric conversion elements 1 to 48 as solar cells 1 to 48.

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.

  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
(Jsc (mA · cm ⁻² ) = Isc (mA) / oxide semiconductor layer surface area (cm ² ))
Here, P is the incident light intensity [mW · cm ⁻² ], Voc is the open circuit voltage [V], Jsc is the short-circuit current density [mA · cm ⁻² ], F.V. F. Indicates a form factor.

  The evaluation results are shown in Table 1.

  From Table 1, photoelectric conversion elements 1 to 44 and 47 using dyes having a skeleton in which imidazolin-5-one is linked to the heterocyclic group of the present invention are photoelectric conversion elements 45, 46, and 48 using comparative dyes. It can be seen that the photoelectric conversion efficiency is higher than that.

1 Substrate 2 First Electrode 3 Barrier Layer 6 Photoelectric Conversion Layer 7 Hole Transport Layer 8 Second Electrode 10 Photoelectric Conversion Element

Claims (6)

A photoelectric conversion element comprising a substrate, a first electrode, a dye and a semiconductor layer comprising a semiconductor layer containing a semiconductor, a hole transport layer and a second electrode in this order, wherein the dye is represented by the following general formula (1) A photoelectric conversion element characterized by being a compound to be produced.

(In the formula, Ar ₁ and Ar ₂ represent a divalent aromatic hydrocarbon residue, heterocyclic residue, chain hydrocarbon residue, or cyclic hydrocarbon residue which may have a substituent. .
Ar ₃ represents a divalent aromatic hydrocarbon residue or heterocyclic residue which may have a substituent.
X ₀ and X ₁ each independently represents a hydrogen atom or an electron-withdrawing group, and at least one of X ₀ and X ₁ is an electron-withdrawing group.
Ar ₁ , Ar ₂ and Ar ₃ may be connected to each other to form a cyclic structure.
R ₁ represents a hydrogen atom, a halogen atom, a cyano group, or an optionally substituted alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, aryl group or heterocyclic group.
R ₂ represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, which may have a substituent.
R ₃ represents an alkyl group, alkenyl group, alkynyl group, alkoxy group, alkylthio group, alkylseleno group, amino group, aryl group or heterocyclic group having a substituent represented by Z.
The substituent represented by Z is an acidic group, and m represents an integer of 1 or more and 7 or less. When m ≧ 2, Z may be the same or different. The carbon-carbon double bond may be either a cis isomer or a trans isomer. )   The photoelectric conversion element according to claim 1, wherein the electron-withdrawing group in the general formula (1) is a halogen atom or a trihalomethyl group. -R < ₃ >-in the said General formula (1) is the following general formula (A), The photoelectric conversion element of Claim 1 or 2 characterized by the above-mentioned.

(Y represents a sulfur atom, an oxygen atom or a selenium atom.
R ₄ and R ₅ are a hydrogen atom, a halogen atom, a hydroxyl group, a thiol group, a cyano group, or an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, an aryl group, or a heterocyclic group, which may have a substituent. It represents a cyclic group and may be connected to each other to form a cyclic structure. n represents an integer of 0 or more and 14 or less, and when n ≧ 2, R ₄ and R ₅ may be the same or different. )   The photoelectric conversion element according to claim 3, wherein Y in the general formula (A) is S (sulfur atom). 5. The photoelectric conversion element according to claim 1, wherein R ₂ in the general formula (1) is hydrogen.   A dye-sensitized solar cell comprising the photoelectric conversion element according to any one of claims 1 to 5.

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