JP5435508B2 - Photoelectric conversion element and solar cell using the element - Google Patents

Description

  The present invention relates to a photoelectric conversion element and a solar cell using the element. Specifically, the present invention relates to a photoelectric conversion element including a fullerene derivative of an electron acceptor and an electron donor compound, and a solar cell using the element.

  Currently, solar cells in practical use are solar cells using photoelectric conversion elements using inorganic materials such as silicon. High-purity silicon is indispensable in the manufacture of photoelectric conversion elements using polycrystalline silicon, but its cost is relatively high.

On the other hand, a photoelectric conversion element using an organic material can be manufactured at a lower cost because a manufacturing method is easier than a photoelectric conversion element using an inorganic material.
As a solar cell including a photoelectric conversion element using an organic material, there is a solar cell using an organic semiconductor material called a dye-sensitized solar cell or an organic thin film solar cell. However, since the electrolyte used in a typical dye-sensitized solar cell is mainly a liquid (electrolytic solution), there may be a problem that the electrolytic solution leaks or volatilizes from a gap between the working electrode and the counter electrode. . Thus, the photoelectric conversion element using an organic material has a problem in durability as compared to the photoelectric conversion element using an inorganic material.

  In addition, as a photoelectric conversion element having a certain durability using an organic material, a photoelectric conversion element [C.C.] in which copper phthalocyanine as an electron donor and a perylene derivative as an electron acceptor are combined. W. Tang, “Two-Layer organic photovoltaic cell”, Applied Physics Letters, 1986, Vol. 48 (Non-patent Document 1)], a photoelectric conversion element combining a polyphenylene vinylene and a fullerene derivative as an electron donor [G. Yu et al., “Polymer Photovoltaic Cells: Enhanced Efficiency via a Network of Internal Donor-Acceptor Heterojunctions, 1995, pp. 270, pp. There is.

  However, these photoelectric conversion elements have a problem that an open circuit voltage or the like is not so high as compared with a photoelectric conversion element using an inorganic material.

JP-T 8-500701

C. W. Tang, “Two-Layer organic photovoltaic cell”, Applied Physics Letters, 1986, 48 volumes. G. Yu et al., “Polymer Photovoltaic Cells: Enhanced Efficiency via a Network of Internal Donor-Acceptor Heterojunctions”, 1995, 270.

  Under the above situation, for example, an organic material is used, but a photoelectric conversion element having a high open circuit voltage is required.

  The present inventors used a photoelectric conversion element including a mixture layer composed of a mixture including a fullerene derivative represented by the following formula (1) or the following formula (2) and an electron donor compound, and the element. A solar cell was found and the present invention was completed based on this finding. The present invention provides the following photoelectric conversion element and solar cell.

[1] At least the following formula (1) or the following formula (2) between a pair of electrodes and a pair of electrodes
(Wherein R ¹ is independently a hydrogen atom or an organic group having 1 to 50 carbon atoms, R ² is a hydrogen atom or an organic group having 1 to 20 carbon atoms, M is a metal atom, Is a ligand of M, and n is the number of L.)
A photoelectric conversion element comprising a fullerene derivative of an electron acceptor represented by formula (1) and an electron donor compound.
[2] The following formula (1) or the following formula (2) provided between a pair of electrodes and a pair of electrodes
(Wherein R ¹ is independently a hydrogen atom or an organic group having 1 to 50 carbon atoms, R ² is a hydrogen atom or an organic group having 1 to 20 carbon atoms, M is a metal atom, Is a ligand of M, and n is the number of L.)
The photoelectric conversion element containing the mixture layer which consists of a mixture containing the fullerene derivative of the electron acceptor represented by this, and the compound of an electron donor.
[3] In Formula (1) or Formula (2), each R ¹ is independently a hydrogen atom, a C ₁ -C ₂₀ hydrocarbon group that may have a substituent, or a C that may have a substituent. _{1 to} C ₂₀ alkoxy group, optionally substituted C _{6 to} C ₂₀ aryloxy group, optionally substituted amino group, optionally substituted silyl group, substituted An alkylthio group (—SY ¹ , wherein Y ¹ represents a C _{1 to} C ₂₀ alkyl group which may have a substituent), an arylthio group (—SY 1) ² , wherein Y ² represents a C ₆ -C ₁₈ aryl group which may have a substituent, and an alkylsulfonyl group which may have a substituent (—SO ₂ Y ³ , wherein Y ³ represents a substituted or unsubstituted group C ₁ -C ₂₀ alkyl group.), an aryl sulfonyl which may have a substituent Le group _(-SO 2 ^{Y 4,} in ^the formula, ^{Y 4} is a good _C 6 _{-C 18} aryl group which may have a substituent.) Shows a; ^{R 2} is a hydrogen atom or a _C 1 _{-C 20} hydrocarbon The photoelectric conversion element according to [1] or [2], which represents a group.
[4] In formula (1) or formula (2), each R ¹ is independently an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 1 to 20 carbon atoms, or the following formula: (3)
(In the formula, R ³ is alkyl having 1 to 15 carbons, alkenyl having 2 to 15 carbons, or alkynyl having 1 to 15 carbons.)
The photoelectric conversion element according to [1] or [2], which is a group represented by:

[5] The photoelectric conversion element according to any one of [1] to [4], wherein in formula (2), M is a transition metal.
[6] The photoelectric conversion element according to any one of [1] to [4], wherein M is a transition metal of group 8 to 10 in formula (2).
[7] In Formula (2), M is Fe or Ru, n is an integer of 0 to 5, L is a hydrogen atom, a halogen atom, an alkoxy group, an alkyl group, an alkyne group, an alkene group, an aryl group, [1] to [4] which are alkylidene group, vinylidene group, allenylidene group, thiolate group, amide group, phosphine group, carbonyl group, nitrile group, isonitrile group, imino group, amino group, ketone group or cyclopentadienyl group. ] The photoelectric conversion element in any one of.

[8] The photoelectric conversion device according to any one of [1] to [7], wherein the electron donor compound is a polymer compound.
[9] The photoelectric conversion device according to any one of [1] to [7], wherein the electron donor compound is a heterocyclic polymer compound.
[10] The photoelectric conversion device according to any one of [1] to [7], wherein the electron donor compound is a porphyrin compound or a phthalocyanine compound.
[11] The photoelectric conversion device according to any one of [1] to [7], wherein the electron donor compound is polythiophene or a copper phthalocyanine complex.

[12] The photoelectric conversion according to any one of [2] to [11], wherein a mixture layer is formed by applying a solution in which a mixture containing a fullerene derivative of an electron acceptor and an electron donor compound is dissolved. element.
[13] In Formula (1) or Formula (2), each R ¹ is independently the following Formula (3)
(In the formula, R ³ is alkyl having 1 to 10 carbons, alkenyl having 2 to 10 carbons, or alkynyl having 2 to 10 carbons.)
A group represented by
In formula (2), M is Fe or Ru, n is an integer of 0 to 5, L is a hydrogen atom, a halogen atom, an alkoxy group, an alkyl group, an alkyne group, an alkene group, an aryl group, an alkylidene group, The photoelectric conversion device according to [12], which is a vinylidene group, an allenylidene group, a thiolate group, an amide group, a phosphine group, a carbonyl group, a nitrile group, an isonitrile group, an imino group, an amino group, a ketone group, or a cyclopentadienyl group. .
[14] The photoelectric conversion element according to any one of [2] to [11], wherein a mixture layer is formed by vapor-depositing a fullerene derivative of an electron acceptor and an electron donor compound.
[15] In formula (1) or formula (2), each R ¹ independently represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, or the following formula (3)
(In the formula, R ³ is alkyl having 1 to 5 carbons, alkenyl having 2 to 5 carbons, or alkynyl having 1 to 5 carbons.)
A group represented by
In formula (2), M is Fe or Ru, n is an integer of 0 to 5, L is a hydrogen atom, a halogen atom, an alkoxy group, an alkyl group, an alkyne group, an alkene group, an aryl group, an alkylidene group, The photoelectric conversion device according to [14], which is a vinylidene group, an allenylidene group, a thiolate group, an amide group, a phosphine group, a carbonyl group, a nitrile group, an isonitrile group, an imino group, an amino group, a ketone group, or a cyclopentadienyl group. .
[16] A solar cell including the photoelectric conversion element according to any one of [1] to [15].

According to the preferable aspect of this invention, a photoelectric conversion element with a high open circuit voltage can be provided, using an organic material.
According to a preferred embodiment of the present invention, it is possible to provide a photoelectric conversion element that can be easily manufactured at low cost.

1 is a schematic diagram of a solar cell of Example 1. FIG. 6 is a schematic diagram of a solar cell of Example 4. FIG.

1 Glass substrate 2 ITO
3 hole extraction layer 4 mixture layer 5 electrode 6 electron extraction layer

1 Electron Donor and Electron Acceptor Included in Photoelectric Conversion Element of the Present Invention An electron donor and an electron acceptor are provided between a pair of electrodes constituting the photoelectric conversion element of the present invention. The photoelectric conversion element of the present invention may have, for example, a laminated structure in which an electron donor and an electron acceptor are layered and laminated, or may have a mixture layer made of a mixture containing both.
1.1 Electron acceptor used for photoelectric conversion element The compound used as an electron acceptor for the photoelectric conversion element of the present invention is a fullerene derivative represented by the above formula (1) or (2).
The fullerene derivative may be a kind of fullerene derivative or a mixture of plural kinds of fullerene derivatives.

1.1.1 In the fullerene derivative represented by the formula (1) (1), each R ¹ is independently a hydrogen atom or an organic group having 1 to 50 carbon atoms, and R ² is a hydrogen atom or carbon number. 1 to 20 organic groups.
Further, in formula (1), ^{R 1} each independently represent a hydrogen atom, an optionally substituted _C 1 _{-C 20} hydrocarbon group, _C 1 may have a substituent _{-C 20} alkoxy group A C ₆ -C ₂₀ aryloxy group which may have a substituent, an amino group which may have a substituent, a silyl group which may have a substituent, and an alkylthio group which may have a substituent (-SY ^1, in ^the formula, ^{Y 1} represents an optionally substituted _C 1 _{-C 20} alkyl group.), which may have a substituent arylthio group (-SY ^2, in the formula, Y ² represents an optionally substituted C ₆ -C ₁₈ aryl group), and an optionally substituted alkylsulfonyl group (—SO ₂ Y ³ , wherein Y ³ has a substituent. and shows a good _C 1 _{-C 20} alkyl group.), an optionally substituted arylsulfonyl group (-SO ₂ Y ^4, shown: in ^the formula, ^{Y 4} is preferably exhibit.) Showing a good _C 6 _{-C 18} aryl group which may have a substituent, ^{R 2} is a hydrogen atom or a _C 1 _{-C 20} hydrocarbon radical It is preferable.

In the present specification, the hydrocarbon group of the “C ₁ -C ₂₀ hydrocarbon group” may be a saturated or unsaturated acyclic group or a saturated or unsaturated cyclic group. When the C _{1 to} C ₂₀ hydrocarbon group is acyclic, it may be linear or branched. The “C ₁ -C ₂₀ hydrocarbon group” includes a C ₁ -C ₂₀ alkyl group, a C ₂ -C ₂₀ alkenyl group, a C ₂ -C ₂₀ alkynyl group, a C ₄ -C ₂₀ alkyl dienyl group, a C _6- C ₁₈ aryl _group, C 7 _{-C 20} alkylaryl _group, C 7 _{-C 20} arylalkyl _group, C 4 _{-C 20} cycloalkyl _group, C 4 _{-C 20} cycloalkenyl _{group, (C} 3 _{~C 10} cycloalkyl) C ₁ -C ₁₀ alkyl groups and the like are included.

In the present specification, _"C 1 _{-C 20} alkyl group" _is preferably C 1 _{-C 10} alkyl _group, more preferably a C 1 -C ₆ alkyl group. Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, dodecanyl and the like.

In the present specification, _"C 2 _{-C 20} alkenyl group" _is preferably C 2 _{-C 10} alkenyl _group, more preferably a C 2 -C ₆ alkenyl group. Examples of alkenyl groups include, but are not limited to, vinyl, allyl, propenyl, isopropenyl, 2-methyl-1-propenyl, 2-methylallyl, 2-butenyl and the like.

In the present specification, "C ₂ -C ₂₀ alkynyl group" _is preferably C 2 _{-C 10} alkynyl _group, more preferably a C 2 -C ₆ alkynyl group. Examples of alkynyl groups include, but are not limited to, ethynyl, propynyl, butynyl, and the like.

In the present specification, _"C 4 _{-C 20} alkyldienyl group" _is preferably C 4 _{-C 10} alkadienyl _group, more preferably a C 4 -C ₆ alkadienyl group. Examples of alkyldienyl groups include, but are not limited to, 1,3-butadienyl and the like.

In the present specification, the “C ₆ -C ₁₈ aryl group” is preferably a C ₆ -C ₁₀ aryl group. Examples of aryl groups include, but are not limited to, phenyl, 1-naphthyl, 2-naphthyl, indenyl, biphenyl, anthryl, phenanthryl and the like.

In the present specification, the “C ₇ -C ₂₀ alkylaryl group” is preferably a C ₇ -C ₁₂ alkylaryl group. Examples of alkylaryl groups include, but are not limited to, o-tolyl, m-tolyl, p-tolyl, 2,3-xylyl, 2,4-xylyl, 2,5-xylyl, o-cumenyl, m -Cumenyl, p-cumenyl, mesityl and the like can be mentioned.

In the present specification, the “C ₇ -C ₂₀ arylalkyl group” is preferably a C ₇ -C ₁₂ arylalkyl group. Examples of arylalkyl groups include, but are not limited to, benzyl, phenethyl, diphenylmethyl, triphenylmethyl, 1-naphthylmethyl, 2-naphthylmethyl, 2,2-diphenylethyl, 3-phenylpropyl, 4-phenyl Examples include phenylbutyl and 5-phenylpentyl.

In the present specification, the “C ₄ -C ₂₀ cycloalkyl group” is preferably a C ₄ -C ₁₀ cycloalkyl group. Examples of cycloalkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like.

In the present specification, the “C ₄ -C ₂₀ cycloalkenyl group” is preferably a C ₄ -C ₁₀ cycloalkenyl group. Examples of cycloalkenyl groups include, but are not limited to, cyclopropenyl, cyclobutenyl, cyclopentenyl, cyclohexenyl and the like.

In the present specification, the “C ₁ -C ₂₀ alkoxy group” is preferably a C ₁ -C ₁₀ alkoxy group, and more preferably a C ₁ -C ₆ alkoxy group. Examples of alkoxy groups include, but are not limited to, methoxy, ethoxy, propoxy, butoxy, pentyloxy and the like.

In the present specification, the “C ₆ -C ₂₀ aryloxy group” is preferably a C ₆ -C ₁₀ aryloxy group. Examples of aryloxy groups include, but are not limited to, phenyloxy, naphthyloxy, biphenyloxy, and the like.

In the present specification, “an alkylthio group (—SY ¹ , wherein Y ¹ represents an optionally substituted C ₁ -C ₂₀ alkyl group)” and “an alkylsulfonyl group (—SO ₂ Y ³ In the formula, Y ³ represents an optionally substituted C _{1 to} C ₂₀ alkyl group.) ”, Y ¹ and Y ³ are preferably C _{1 to} C ₁₀ alkyl groups. it is more preferably ₁ -C ₆ alkyl group. Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, dodecanyl and the like.

In the present specification, “arylthio group (—SY ² , wherein Y ² represents an optionally substituted C ₆ -C ₁₈ aryl group)” and “arylsulfonyl group (—SO ₂ Y ⁴ In the formula, Y ⁴ represents a C ₆ -C ₁₈ aryl group which may have a substituent.) In the formula, Y ² and Y ⁴ are preferably C ₆ -C ₁₀ aryl groups. Examples of the aryl group include, but are not limited to, phenyl, 1-naphthyl, 2-naphthyl, indenyl, biphenylyl, anthryl, phenanthryl and the like.

“C ₁ -C ₂₀ hydrocarbon group”, “C ₁ -C ₂₀ alkoxy group”, “C ₆ -C ₂₀ aryloxy group”, “amino group”, “silyl group”, “alkylthio group”, “arylthio group” ”,“ Alkylsulfonyl group ”, and“ arylsulfonyl group ”may have a substituent introduced therein. Examples of the substituent include an ester group, a carboxyl group, an amide group, an alkyne group, a trimethylsilyl group, an amino group, a phosphonyl group, a thio group, a carbonyl group, a nitro group, a sulfo group, an imino group, a halogeno group, and an alkoxy group. Can be mentioned. In this case, one or more substituents may be introduced at the substitutable position up to the maximum number that can be substituted, and preferably 1 to 4 substituents may be introduced. When the number of substituents is 2 or more, each substituent may be the same or different.

  In the present specification, examples of the “amino group which may have a substituent” include, but are not limited to, amino, dimethylamino, methylamino, methylphenylamino, phenylamino and the like.

  In this specification, examples of “optionally substituted silyl group” include, but are not limited to, dimethylsilyl, diethylsilyl, trimethylsilyl, triethylsilyl, trimethoxysilyl, triethoxysilyl, diphenyl Examples include methylsilyl, triphenylsilyl, triphenoxysilyl, dimethylmethoxysilyl, dimethylphenoxysilyl, and methylmethoxyphenyl.

In the present specification, examples of the “aromatic group” include a phenyl group, a biphenyl group, and a terphenyl group.
In the present specification, examples of the “heterocyclic group” include a thienyl group, a pyrrolyl group, a pyridyl group, a bipyridyl group, an oxazolyl group, an oxadiazolyl group, a thiazolyl group, a thiadiazolyl group, and a tertienyl group.
In the present specification, examples of the “condensed polycyclic aromatic group” include a fluorenyl group, a naphthyl group, a fluoranthenyl group, an anthryl group, a phenanthryl group, a pyrenyl group, a tetracenyl group, a pentacenyl group, a triphenylenyl group, a perylenyl group, and the like. There is.
In the present specification, examples of the “fused polycyclic heterocyclic group” include a carbazolyl group, an acridinyl group, a phenanthroyl group, and the like.

In addition, examples of the substituent that these “aromatic group”, “heterocyclic group”, “fused polycyclic aromatic group” and “fused polycyclic heterocyclic group” may have are limited. but _not, C 1 _{-C 10} hydrocarbon group (e.g., methyl, ethyl, propyl, butyl, phenyl, naphthyl, indenyl, tolyl, xylyl, benzyl, _etc.), C 1 _{-C 10} alkoxy group (e.g., methoxy, ethoxy , Propoxy, butoxy, etc.), C ₆ -C ₁₀ aryloxy groups (eg, phenyloxy, naphthyloxy, biphenyloxy, etc.), amino groups, hydroxyl groups, halogen atoms (eg, fluorine, chlorine, bromine, iodine) or silyl groups And so on. In this case, one or more substituents may be introduced at substitutable positions, and preferably 1 to 4 substituents may be introduced. When the number of substituents is 2 or more, each substituent may be the same or different.

^{R 1} fullerene derivative formula (2) represented by the 1.1.2 formula (2) is the same as ^{R 1} in formula (1).
In the formula (2), M is a metal atom, L is a ligand of M, and n is the number of L. M is Fe or Ru, n is an integer of 0 to 5, and L is a hydrogen atom, alkoxy group, alkyl group, alkyne group, alkene group, aryl group, alkylidene group, vinylidene group, allenylidene group, thiolate group Amide group, phosphine group, carbonyl group, nitrile group, isonitrile group, imino group, amino group, ketone group or cyclopentadienyl group (Cp).

1.2 Compound of electron donor used in photoelectric conversion device The compound of the electron donor used in the photoelectric conversion device of the present invention is not particularly limited as long as it functions as an electron donor.
In addition, the compound of the electron donor used for a photoelectric conversion element may be a single compound or a mixture of multiple compounds.

A preferred electron donor compound used in the present invention is a polymer compound, a porphyrin compound or a phthalocyanine compound.
As the polymer compound used as the electron donor, for example, a heterocyclic polymer such as polythiophene, polypyrrole, polyaniline, polyfuran, polypyridine, polycarbazole and the like can be used. Among these, polythiophene, polypyrrole, and polyfuran are preferable in that various substituents are bonded and various structures exist, so that a wide variety of polymers can be synthesized.

  Examples of the porphyrin compound used as the electron donor include 5,10,15,20-tetraphenyl-21H, 23H-porphine, 5,10,15,20-tetraphenyl-21H, 23H-porphine cobalt (II). 5,10,15,20-tetraphenyl-21H, 23H-porphine copper (II), 5,10,15,20-tetraphenyl-21H, 23H-porphine zinc (II), 5,10,15,20 -Tetraphenyl-21H, 23H-porphine vanadium (IV) oxide, 5,10,15,20-tetra (4-pyridyl) -21H, 23H-porphine.

Examples of the phthalocyanine compound used as an electron donor include 29H, 31H-phthalocyanine, copper phthalocyanine complex, zinc phthalocyanine complex, titanium phthalocyanine oxide complex, magnesium phthalocyanine complex, lead phthalocyanine complex, copper 4, 4 ′, 4 ′. Examples include ', 4'''-tetraaza-29H, 31H-phthalocyanine complex.
Among these, a copper phthalocyanine complex is preferable.

1.3 Method for Producing Mixture Layer The method for producing the mixture layer is not particularly limited. For example, a solution in which a fullerene derivative and an electron donor compound are dissolved together is spin-coated on a substrate or a layer provided on the substrate. (Coating-type mixture layer). It can also be produced by vapor-depositing a fullerene derivative and an electron donor compound on a substrate or a layer provided on the substrate (evaporation-type mixture layer).

The fullerene derivative represented by the above formula (1) or formula (2) used in the coating-type mixture layer is as described above. In formula (1) or formula (2), R ¹ is independently selected. Following formula (3)
(In the formula, R ³ is alkyl having 1 to 10 carbons, alkenyl having 2 to 10 carbons, or alkynyl having 2 to 10 carbons.)
Is preferable because the solubility in a solvent during coating is improved and the open-circuit voltage of the obtained photoelectric conversion element is also improved.

  The compound of the electron donor used in the coating type mixture layer is as described above. However, when polythiophene, polypyrrole, polyaniline, polyfuran, polypyridine, polycarbazole is used, the solubility in a solvent during coating is improved. Since the open circuit voltage of the obtained photoelectric conversion element is also improved, it is preferable.

The fullerene derivative represented by the above formula (1) or formula (2) used in the vapor deposition type mixture layer is as described above. In formula (1) or formula (2), each R ¹ is independently selected. C1-C10 alkyl, C2-C10 alkenyl, C2-C10 alkynyl, or following formula (3)
(In the formula, R ³ is alkyl having 1 to 5 carbons, alkenyl having 2 to 5 carbons, or alkynyl having 1 to 5 carbons.)
Is preferable because the fullerene derivative is easily deposited and the open-circuit voltage of the obtained photoelectric conversion element is improved.

  The compound of the electron donor used in the vapor deposition type mixture layer is as described above. However, when a porphyrin compound and a phthalocyanine compound are used, a uniform layer with a fullerene derivative can be easily provided, and the obtained photoelectric conversion It is preferable because the open circuit voltage of the element is improved.

  The mixture layer is not particularly limited as long as it includes a fullerene derivative and an electron donor compound, and may include other compounds.

2 Photoelectric Conversion Device and Solar Cell of the Present Invention The photoelectric conversion device of the present invention has a pair of electrodes, an electron acceptor fullerene derivative disposed between the pair of electrodes, and an electron donor compound. .

  In the photoelectric conversion element of the present invention, the material used for the electrode is not particularly limited as long as it has conductivity. For example, ITO, tin oxide, zinc oxide, Au, Co, Ni, Pt, etc. It is preferable to use a material having a high work function in combination with Al, Ag, Li, In, Ca, Mg, LiF, or the like. Especially, it is preferable to use transparent electrodes, such as ITO, a tin oxide, and a zinc oxide, for the electrode in the position which permeate | transmits light. The manufacturing method and film thickness of these electrodes can be selected as appropriate.

  In the photoelectric conversion device of the present invention, when a mixture layer of an electron acceptor fullerene derivative and an electron donor compound is provided, the thickness of the mixture layer is not particularly limited. The problem is that the property is not sufficient and a short circuit is likely to occur. On the other hand, when the thickness of the mixture layer exceeds 5000 nm, the internal resistance increases, and the volume ratio of the solid layer per element increases, which is not preferable because the capacity decreases. Further, since the distance between the electrodes is increased, there arises a problem that charge diffusion is deteriorated. Therefore, the thickness of the mixture layer is preferably 0.1 to 5000 nm, and more preferably 1 to 1000 nm. More preferably, 20-500 nm is further more preferable.

  The photoelectric conversion device of the present invention is selected from the group consisting of a pair of electrodes and a fullerene derivative of an electron acceptor and an electron donor compound disposed therebetween, and a hole extraction layer and an electron extraction layer. Can have one or more.

The material of the hole extraction layer is not particularly limited as long as it can improve the efficiency of extracting holes from the layer containing the electron acceptor and the electron donor to the electrode. Specific examples thereof include conductive organic compounds such as polythiophene, polypyrrole, polyacetylene, and triphenylenediamine. A thin film made of a metal such as Au, In, Ag, or Pd can also be used. Furthermore, a thin film of metal or the like may be formed alone or in combination with the above organic material.
The material of the electron extraction layer is not particularly limited as long as it can improve the efficiency of extracting electrons from the layer containing the electron acceptor and the electron donor to the electrode. Specifically, bathocuproine (BCP) or bathophenanthrene (Bphen) and a layer doped with an alkali metal or an alkali metal earth can be given. In addition, fullerenes, siloles, and the like can be used as the material for the electron extraction layer. For example, in the above-described bathocuproin (BCP), bathophenanthrene (Bphen), or bathocuproin (BCP) and bathophenanthrene (Bphen). A combination of layers doped with alkali metal or alkali metal earth can also be used.

  The hole extraction layer and the electron extraction layer are disposed so as to sandwich an electron acceptor and an electron donor (for example, a mixture layer) between a pair of electrodes. That is, when the photoelectric conversion element of the present invention includes both a hole extraction layer and an electron extraction layer, an electrode, a hole extraction layer, an electron acceptor and an electron donor (for example, a mixture layer), an electron extraction layer, an electrode It has the structure arranged in order. When the photoelectric conversion element of the present invention includes a hole extraction layer and does not include an electron extraction layer, the electrode, the hole extraction layer, an electron acceptor and an electron donor (for example, a mixture layer), and an electrode are arranged in this order. It has a configuration. When the photoelectric conversion element of the present invention includes an electron extraction layer and does not include a hole extraction layer, it has a configuration in which an electrode, an electron acceptor and an electron donor (for example, a mixture layer), an electron extraction layer, and an electrode are arranged in this order. .

  The fullerene derivative functions as an electron acceptor, and the electron donor compound functions as an electron donor. Specifically, when light is applied to a layer (for example, a mixture layer) containing an electron donor and an electron acceptor, electrons generated by excitation due to irradiation move to the counter electrode through the fullerene derivative in the layer. . Further, when electrons move to the fullerene derivative, the electron donor compound becomes oxidized, and holes move to the working electrode. In this way, a current flows.

  The photoelectric conversion element of this invention can be used conveniently for various photoelectric conversion apparatuses, such as not only a solar cell but an optical switching apparatus and a sensor.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention, this invention is not limited to these Examples.
Synthesis Example 1 Synthesis of C ₆₀ (nBuC ₆ H ₄ ) ₅ H
Fullerene C ₆₀ (4.00 g, 5.55 mmol) was dissolved in 1,2-dichlorobenzene (180 mL) at room temperature under a nitrogen atmosphere, and degassed for 1 hour. CuBr ・ SMe ₂ (17.1 g, 83.3 mmol) was suspended in tetrahydrofuran (94 mL) at 0 ° C. under a nitrogen atmosphere, and tetrahydrofuran solution (80.8 mL, 1.03 M, 83.4 mmol) of n-BuC ₆ H ₄ MgBr was suspended. Was slowly added dropwise and stirred at room temperature for a while, and then the reaction was started by transferring a 1,2-dichlorobenzene solution of C _60. After 2 hours, saturated ammonium chloride aqueous solution (10 mL) was added to stop the reaction. I let you. In the present specification, Me represents methyl.

Tetrahydrofuran was distilled off under reduced pressure, and by-product copper was removed through a mixture obtained on a silica gel short path column with toluene as the developing solvent, and then purified by silica gel column chromatography (eluent: carbon disulfide). did. After collecting and concentrating fractions of C ₆₀ (nBuC ₆ H ₄ ) ₅ H (fullerene derivative 1), ethanol was added to precipitate the target product, and fullerene derivative 1 was obtained by filtration and drying (isolation yield 96 %).

Synthesis Example 2 Synthesis of C ₆₀ (nBuC ₆ H ₄ ) ₅ Me
Next, as shown in Scheme 2, fullerene derivative 1 (1.00 g, 0.718 mmol) prepared at room temperature under a nitrogen atmosphere was dissolved in tetrahydrofuran (150 mL), and a solution of potassium tert-butoxide in tetrahydrofuran (0.790 mL, 0.790). mmol) was added dropwise and stirred for 15 minutes. Methyl iodide (0.400 mL, 2.82 mmol) was added to the resulting black solution and stirred for 1 hour. After the solvent was distilled off under reduced pressure, the residue was purified by silica gel column chromatography (eluent: carbon disulfide / hexane = 1/2). After collecting and concentrating the fraction of C ₆₀ (nBuC ₆ H ₄ ) ₅ Me (fullerene derivative 2), ethanol was added to precipitate the target product, and the fullerene derivative 2 was obtained by filtration and drying (isolation yield 77). %).

Synthesis Example 3 Synthesis of Fe (C ₆₀ (nBuC ₆ H ₄ ) ₅ ) Cp
Next, as shown in Scheme 3, fullerene derivative 1 (1.00 g, 0.718 mmol) produced at room temperature under a nitrogen atmosphere was dissolved in benzonitrile (150 mL), and [FeCp (CO) ₂ ] ₂ (0.508 g, 1.44 mmol) was added and the mixture was heated to 180 ° C. and stirred for 8 hours. After removing the solvent under reduced pressure and passing through the mixture obtained on a silica gel short pass column with toluene as the developing solvent, the insoluble matter was removed, and then silica gel column chromatography (eluent: carbon disulfide / hexane = 1/2) ). After collecting and concentrating the fraction of Fe (C ₆₀ (nBuC ₆ H ₄ ) ₅ ) Cp (fullerene derivative 3), ethanol was added to precipitate the target compound, and fullerene derivative 3 was obtained by filtration and drying (isolation) Yield 59%).
In the present specification, Ph represents phenyl.

Synthesis Example 4 Synthesis of Ru (C ₆₀ (nBuC ₆ H ₄ ) ₅ ) Cp
Next, as shown in Scheme 4, fullerene derivative 1 (500 mg, 0.359 mmol) produced at room temperature under a nitrogen atmosphere was dissolved in tetrahydrofuran (75 mL), and a solution of potassium tert-butoxide in tetrahydrofuran (0.395 mL, 0.395 mmol). ) Was added dropwise and stirred for 15 minutes. [RuCp (CH ₃ CN) ₃ ] PF ₆ (187 mg, 0.431 mmol) was added to the resulting black solution and stirred for 15 minutes. After evaporating the solvent under reduced pressure, the mixture obtained was passed through a silica gel short path column with toluene as the developing solvent to remove insolubles, and then silica gel column chromatography (eluent: carbon disulfide / hexane). = 1/2). The fractions of Ru (C ₆₀ (nBuC ₆ H ₄ ) ₅ ) Cp (fullerene derivative 4) were collected and concentrated, ethanol was added to precipitate the target product, and the fullerene derivative 4 was obtained by filtration and drying (isolation) Yield 47%).

[Synthesis Example _5] Synthesis of _C 60 Me ₅ H
C ₆₀ (4.00 g, 5.55 mmol) was dissolved in 1,2-dichlorobenzene (180 mL) at room temperature under a nitrogen atmosphere, and degassed for 1 hour. Suspend CuBr ・ SMe ₂ (13.7 g, 66.6 mmol) in tetrahydrofuran (94 mL) at 0 ° C under a nitrogen atmosphere, slowly add dropwise a solution of MeMgBr in tetrahydrofuran (66.6 mL, 1.00 M, 66.6 mmol) at room temperature. The temperature was raised to 1,3-dimethyl-2-imidazolidinone (7.60 mL, 66.6 mmol) was added. After raising the temperature to 35 ° C., the reaction was started by transferring a 1,2-dichlorobenzene solution of C ₆₀ , and after 1 hour, a saturated aqueous ammonium chloride solution (6 mL) was added to stop the reaction. Tetrahydrofuran was distilled off under reduced pressure, and the pressure was restored with nitrogen, and then by-product copper and the like were removed through a mixture obtained through a silica gel short pass column using toluene degassed as a developing solvent. After toluene was distilled off and the pressure was restored with nitrogen, degassed methanol was added to precipitate the target product, and filtration and drying gave C ₆₀ Me ₅ H (fullerene derivative 5) (isolation yield 96%). ).

[Synthesis Example _{6] Fe (C 60 Me 5} ) Cp Synthesis of
Next, as shown in Scheme 6, fullerene derivative 5 (1.00 g, 1.25 mmol) produced at room temperature under a nitrogen atmosphere was dissolved in benzonitrile (200 mL), and [FeCp (CO) ₂ ] ₂ (0.888 g, 2.51 mmol) was added, and the mixture was heated to 180 ° C. and stirred for 8 hours. The solvent was distilled off under reduced pressure, and the insoluble matter was removed through a mixture obtained through a silica gel short pass column using toluene as a developing solvent, and then purified by silica gel column chromatography (eluent: carbon disulfide). After collecting and concentrating the fraction of Fe (C ₆₀ Me ₅ ) Cp (fullerene derivative 6), ethanol was added to precipitate the desired product, and the fullerene derivative 6 was obtained by filtration and drying (isolation yield 35%). .

Synthesis Example 7 Synthesis of Ru (C ₆₀ Me ₅ ) Cp
Next, as shown in Scheme 7, fullerene derivative 5 (500 mg, 0.627 mmol) produced at room temperature under a nitrogen atmosphere was suspended in tetrahydrofuran (75 mL), and a solution of potassium tert-butoxide in tetrahydrofuran (0.690 mL, 0.690 mmol) was added dropwise and stirred for 15 minutes. [RuCp (CH ₃ CN) ₃ ] PF ₆ (327 mg, 0.753 mmol) was added to the resulting black solution, and the mixture was stirred for 15 minutes. After distilling off the solvent under reduced pressure, the mixture obtained was passed through a silica gel short path column with toluene as the developing solvent, and after removing insolubles, silica gel column chromatography (eluent: carbon disulfide) was used. Purified. After collecting and concentrating fractions of Ru (C ₆₀ Me ₅ ) Cp (fullerene derivative 7), ethanol was added to precipitate the target product, and fullerene derivative 7 was obtained by filtration and drying (isolation yield 34%). .

[Synthesis Example 8] Synthesis of C ₆₀ Ph ₅ H
C ₆₀ (4.00 g, 5.55 mmol) was dissolved in 1,2-dichlorobenzene (180 mL) at room temperature under a nitrogen atmosphere, and degassed for 1 hour. CuBr · SMe ₂ in a nitrogen atmosphere 0 ℃ (17.1 g, 83.3 mmol ) was suspended in tetrahydrofuran (94 mL), tetrahydrofuran PhMgBr (83.3 mL, 1.00 M, 83.3 mmol) was slowly added dropwise, at room temperature After stirring for a while, a 1,2-dichlorobenzene solution of C ₆₀ was transferred to start the reaction. After 2 hours, a saturated aqueous ammonium chloride solution (10 mL) was added to stop the reaction. Tetrahydrofuran was distilled off under reduced pressure, and by-product copper was removed through a mixture obtained on a silica gel short path column with toluene as the developing solvent, and then purified by silica gel column chromatography (eluent: carbon disulfide). did. After collecting and concentrating the fraction of C ₆₀ Ph ₅ H (fullerene derivative 8), ethanol was added to precipitate the target product, and filtration and drying gave fullerene derivative 8 (isolation yield 89%).

Synthesis Example 9 Synthesis of Fe (C ₆₀ Ph ₅ ) Cp
Next, as shown in Scheme 9, fullerene derivative 8 (1.00 g, 0.903 mmol) produced at room temperature under nitrogen atmosphere was dissolved in benzonitrile (200 mL), and [FeCp (CO) ₂ ] ₂ (0.639 g, 1.81 mmol) was added, and the mixture was heated to 180 ° C. and stirred for 20 hours. The solvent was distilled off under reduced pressure, and the insoluble matter was removed through a mixture obtained through a silica gel short pass column using toluene as a developing solvent, and then purified by silica gel column chromatography (eluent: carbon disulfide). After collecting and concentrating the fraction of Fe (C ₆₀ Ph ₅ ) Cp (fullerene derivative 9), ethanol was added to precipitate the target product, and the fullerene derivative 9 was obtained by filtration and drying (isolation yield 65%). .

Example 1 Solar Cell Having a Mixture Layer Formed by Application Based on FIG. 1, which is a schematic diagram of the solar cell of Example 1, the configuration of the solar cell of Example 1 is shown.
The molar ratio of poly (3-hexylthiophene-2,5-diyl) (trade name “Resiregular” manufactured by Aldrich) (hereinafter referred to as “P3HT”) and fullerene derivative 2 is a ratio of 1: 0.15, and A monochlorobenzene solution in which P3HT and fullerene derivative 2 were dissolved was prepared by dissolving in monochlorobenzene so that the solid content concentration was 1.6 wt%.

  Poly (3,4) -ethylenedioxythiophene / polystyrene sulfonate aqueous dispersion as a hole extraction layer 3 on an ITO glass substrate provided with ITO 2 on a glass substrate 1 “Baytron AI 4083”) was applied by spin coating, and then the substrate was heated on a hot plate. The film thickness was 28 nm. The monochlorobenzene solution was applied onto the heat-treated substrate by spin coating to obtain a mixture layer 4 having a thickness of 75 nm. An aluminum film having a thickness of 80 nm was provided as an electrode 5 on the mixture layer 4 by vacuum deposition, and a transparent glass substrate (not shown) was attached to an ITO glass substrate with a sealant in a nitrogen atmosphere and sealed. The sealed device was subjected to a heat treatment at 150 ° C. for 10 minutes on a hot plate to produce a bulk heterojunction solar cell as shown in FIG.

  The solar cell was irradiated with 100mW / cm2 of light from the ITO glass substrate side with a solar simulator (AM1.5G), and the current between ITO2 and electrode 5 was measured with a source meter (Caysley, Model 2400). -Voltage characteristics were measured and open circuit voltage and photoelectric conversion efficiency were calculated. The results are shown in Table 1.

[Example 2] Solar cell having a coating-type mixture layer A solar cell was produced under the same conditions as in Example 1 except that fullerene derivative 3 was used instead of fullerene derivative 2.
About the created battery, the current-voltage characteristic was measured similarly to Example 1, and the open circuit voltage and the photoelectric conversion efficiency were computed. The results are shown in Table 1.

[Example 3] Solar cell having a coating-type mixture layer A solar cell was produced under the same conditions as in Example 1 except that fullerene derivative 4 was used instead of fullerene derivative 2.
About the created battery, the current-voltage characteristic was measured similarly to Example 1, and the open circuit voltage and the photoelectric conversion efficiency were computed. The results are shown in Table 1.

[Comparative Example 1] Solar cell having coating-type mixture layer In place of fullerene derivative 2, the following formula (4)
A solar cell was produced under the same conditions as in Example 1 except that [6,6] -phenyl C61-butyric acid methyl ester represented by:
About the created battery, the current-voltage characteristic was measured similarly to Example 1, and the open circuit voltage and the photoelectric conversion efficiency were computed. The results are shown in Table 1.

Example 4 Solar Cell Having Vapor Deposition Type Mixture Layer The configuration of the solar cell of Example 4 is shown based on FIG. 2, which is a schematic diagram of the solar cell of Example 4.
Poly (3,4) -ethylenedioxythiophene / polystyrene sulfonate aqueous dispersion as a hole extraction layer 3 on an ITO glass substrate provided with ITO 2 on a glass substrate 1 Baytron PH ") was applied by spin coating, and then the substrate was heated on a hot plate. The film thickness was 40 nm. Next, the fullerene derivative 6 as the electron acceptor and the copper phthalocyanine as the electron donor are adjusted on the substrate so as to have the same vapor deposition rate in the vacuum vapor deposition machine. A vapor deposition film was formed. On the film, fullerene C ₆₀ is deposited to a thickness of 30 nm by vapor deposition (C ₆₀ vapor deposition film), and bathocuproine is deposited to a thickness of 6 nm by vapor deposition to extract electrons. Layer 6 was provided. Thereafter, silver was deposited to a thickness of 80 nm to form a film, and an electrode 5 was provided.

  The substrate thus formed is taken out from the vacuum vapor deposition machine, and a transparent glass substrate is attached to an ITO glass substrate with a sealant and sealed in a nitrogen atmosphere to seal the bulk heterojunction solar as shown in FIG. A battery was created.

  The solar cell was irradiated with 100mW / cm2 of light from the ITO glass substrate side with a solar simulator (AM1.5G), and the current between ITO2 and electrode 5 was measured with a source meter (Caysley, Model 2400). -Voltage characteristics were measured and open circuit voltage and photoelectric conversion efficiency were calculated. The results are shown in Table 2.

[Example 5] Solar cell having a mixture layer formed by vapor deposition A solar cell was produced under the same conditions as in Example 4 except that fullerene derivative 7 was used instead of fullerene derivative 6.
About the created battery, the current-voltage characteristic was measured similarly to Example 4, and the open circuit voltage and the photoelectric conversion efficiency were computed. The results are shown in Table 2.

[Example 6] Solar cell having a vapor-deposited mixture layer A solar cell was produced under the same conditions as in Example 4 except that fullerene derivative 9 was used instead of fullerene derivative 6.
About the created battery, the current-voltage characteristic was measured similarly to Example 4, and the open circuit voltage and the photoelectric conversion efficiency were computed. The results are shown in Table 2.

Comparative Example 2 Solar Cell Having Vapor Deposition Type Mixture Layer A solar cell was produced under the same conditions as in Example 4 except that fullerene C ₆₀ was used instead of fullerene derivative 6.
About the created battery, the current-voltage characteristic was measured similarly to Example 4, and the open circuit voltage and the photoelectric conversion efficiency were computed. The results are shown in Table 2.

  Examples of the utilization method of the present invention include various photoelectric conversion devices such as a solar cell, an optical switching device, and a sensor.

Claims (12)

At least the following formula (1) or the following formula (2) between the pair of electrodes and the pair of electrodes

(In the formula, each R ¹ independently represents a hydrogen atom , an optionally substituted C ₁ -C ₂₀ alkoxy group, an optionally substituted C ₆ -C ₂₀ aryloxy group, or a substituent. An optionally substituted amino group , an optionally substituted alkylthio group (-SY ¹ , wherein Y ¹ represents an optionally substituted C ₁ -C ₂₀ alkyl group), or (in, -SY ² wherein, ^{Y 2} is. showing a good _C 6 _{-C 18} aryl group which may have a substituent) may arylthio group which may have a substituent is, ^{R 2} is a hydrogen atom or An organic group having 1 to 20 carbon atoms, M is a metal atom, L is a ligand of M, and n is the number of L.)
A photoelectric conversion element comprising a fullerene derivative of an electron acceptor represented by formula (1) and an electron donor compound. The following formula (1) or the following formula (2) provided between a pair of electrodes and a pair of electrodes

(In the formula, each R ¹ independently represents a hydrogen atom , an optionally substituted C ₁ -C ₂₀ alkoxy group, an optionally substituted C ₆ -C ₂₀ aryloxy group, or a substituent. An optionally substituted amino group , an optionally substituted alkylthio group (-SY ¹ , wherein Y ¹ represents an optionally substituted C ₁ -C ₂₀ alkyl group), or (in, -SY ² wherein, ^{Y 2} is. showing a good _C 6 _{-C 18} aryl group which may have a substituent) may arylthio group which may have a substituent is, ^{R 2} is a hydrogen atom or An organic group having 1 to 20 carbon atoms, M is a metal atom, L is a ligand of M, and n is the number of L.)
The photoelectric conversion element containing the mixture layer which consists of a mixture containing the fullerene derivative of the electron acceptor represented by this, and the compound of an electron donor.   The photoelectric conversion element of Claim 1 or 2 whose M is a transition metal in Formula (2).   The photoelectric conversion element of Claim 1 or 2 whose M is a transition metal of 8-10 groups in Formula (2).   In formula (2), M is Fe or Ru, n is an integer of 0 to 5, L is a hydrogen atom, a halogen atom, an alkoxy group, an alkyl group, an alkyne group, an alkene group, an aryl group, an alkylidene group, The photoelectric according to claim 1 or 2, which is a vinylidene group, an allenylidene group, a thiolate group, an amide group, a phosphine group, a carbonyl group, a nitrile group, an isonitrile group, an imino group, an amino group, a ketone group or a cyclopentadienyl group. Conversion element.   The photoelectric conversion element according to claim 1, wherein the electron donor compound is a polymer compound.   The photoelectric conversion element according to claim 1, wherein the electron donor compound is a heterocyclic polymer compound.   The photoelectric conversion element according to claim 1, wherein the electron donor compound is a porphyrin compound or a phthalocyanine compound.   The photoelectric conversion element according to claim 1, wherein the electron donor compound is polythiophene or a copper phthalocyanine complex.   The photoelectric conversion element according to any one of claims 2 to 9, wherein a mixture layer is formed by applying a solution in which a mixture containing a fullerene derivative of an electron acceptor and a compound of an electron donor is dissolved.   The photoelectric conversion element according to claim 2, wherein the mixture layer is formed by vapor-depositing a fullerene derivative of an electron acceptor and a compound of an electron donor.   The solar cell containing the photoelectric conversion element in any one of Claims 1-11