JP2010254608A - Phthalimide compound, naphthalimide compound, naphthalic anhydride compound, electron transporting material including these compounds and organic thin film solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric converter, particularly a new material for photoelectric converters which shows high efficiency photoelectric conversion properties when used as an organic thin film solar cell. <P>SOLUTION: The compound is represented by formula (1) (wherein L is a divalent or trivalent group; Rg is a substituted or unsubstituted benzene ring or a naphthalene ring; X is oxygen or N-R<SP>1</SP>; R<SP>1</SP>is hydrogen, a halogen, a cyano group, a 1-20C substituted or unsubstituted alkyl group, a 2-20C substituted or unsubstituted alkenyl group, a 2-20C substituted or unsubstituted alkynyl group, a 6-20C substituted or unsubstituted aryl group, a 3-20C substituted or unsubstituted heteroaryl group, a 1-20C substituted or unsubstituted alkyloxy group, a 6-20C substituted or unsubstituted aryloxy group, a 6-20C substituted or unsubstituted arylamino group or a 1-20C substituted or unsubstituted alkylamino group; and n is 2 or 3). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a photoelectric conversion element material and a photoelectric conversion element using the same, and more specifically, by using a specific aromatic compound as an organic thin film solar cell material, particularly high efficiency photoelectric conversion characteristics can be obtained. The present invention relates to an organic thin film solar cell.

An organic thin film solar cell is a device that shows an electrical output with respect to an optical input, as represented by a photodiode or an imaging device that converts an optical signal into an electrical signal, or a solar cell that converts optical energy into electrical energy, It is a device that exhibits a response opposite to that of an electroluminescence (EL) element that exhibits an optical output with respect to an electrical input. In particular, solar cells have attracted a great deal of attention as a clean energy source in recent years against the background of fossil fuel depletion and global warming, and research and development have been actively conducted.
Conventionally, silicon solar cells represented by single crystal Si, polycrystal Si, amorphous Si, etc. have been put into practical use. However, as the cost and raw material Si shortage problems surface, The demand for next generation solar cells is increasing. Against this background, organic solar cells are attracting much attention as next-generation solar cells next to silicon-based solar cells because they are inexpensive, have low toxicity, and do not have a fear of shortage of raw materials.

Organic solar cells are basically composed of an n layer for transporting electrons and a p layer for transporting holes, and is roughly classified into two types depending on the material constituting each layer.
A n-layer in which a sensitizing dye such as ruthenium dye is adsorbed on the surface of an inorganic semiconductor such as titania and an electrolyte solution is used as a p-layer is called a dye-sensitized solar cell (so-called Gretzell cell), and has a conversion efficiency. From the height, it has been studied vigorously since 1991. However, since the solution is used, it has a drawback such as liquid leakage when used for a long time.
In order to overcome such drawbacks, an all-solid-state dye-sensitized solar cell obtained by solidifying an electrolyte solution has recently been studied. For example, a technique for impregnating organic matter into the pores of porous titania has been studied, but since this technique is difficult, a solar cell that can express high conversion efficiency with high reproducibility has not yet been completed. is there.

On the other hand, organic thin-film solar cells consisting of organic thin films in both the n-layer and p-layer are all solid, so they have no drawbacks such as liquid leakage, are easy to manufacture, and do not use ruthenium, which is a rare metal. Attracted attention and researched energetically.
Organic thin-film solar cells have been researched with single-layer films using merocyanine dyes, etc., but it has been found that conversion efficiency can be improved by using p-layer / n-layer multilayer films. Multilayer films are becoming mainstream. The materials used at this time were copper phthalocyanine (CuPc) for the p layer, peryleneimides (PTCBI) for the n layer, and a nitrogen-containing heterocyclic compound (bathocproine) for the third layer.

Subsequently, it has been found that the conversion efficiency is improved by inserting an i layer (a mixed layer of p material and n material) between the p layer and the n layer to increase the number of layers. However, the materials used at this time were still phthalocyanines, peryleneimides and BCP. Further, thereafter, the stack cell configuration in the p / i / n layers be stacked several layers, but further the conversion efficiency was found to be improved, a material system phthalocyanines and C ₆₀ and bathocuproine this time there were.

On the other hand, in an organic thin film solar cell using a polymer, a conductive polymer is used as a p material, a C ₆₀ derivative is used as an n material, and they are mixed and heat-treated to induce micro-layer separation to form a heterointerface. Research on so-called bulk heterostructures has been mainly conducted to increase the conversion efficiency and improve the conversion efficiency. Here material system that has been used is mostly soluble polythiophene derivative called P3HT as p material was soluble C ₆₀ derivatives referred to as PCBM as an n material.

Thus, in organic thin film solar cells, conversion efficiency has been improved by optimizing the cell configuration and morphology, but the material system used has not made much progress since the early days, and phthalocyanines and peryleneimides still remain. , _{C 60} acids, bathocuproine have been used. Therefore, development of a new material system to replace them has been eagerly desired.

  In general, the operation process of an organic solar cell consists of (1) light absorption and exciton generation, (2) exciton diffusion, (3) charge separation, (4) carrier movement, and (5) electromotive force generation. However, organic substances generally have poor electron transport properties. Moreover, the electron extraction efficiency from the organic layer to the cathode is low. Therefore, there has been a demand for an organic material that has high electron transport properties and high electron extraction efficiency to the cathode.

About the material which can be used for an organic thin-film solar cell, an organic EL element, etc., it describes in the patent documents 1-3 and the nonpatent literature 1-3, for example.
Patent Document 4 describes a method for improving the conversion efficiency of a photoelectric conversion element.
The phenanthroline compound of Patent Document 1 has poor electron transport properties, and has a very low mobility of about 10 ⁻⁶ cm ² / Vs. In addition, the perylene tetracarboxylic imide derivative of Patent Document 2 has insufficient energy extraction between the organic layer and the cathode, so that the electron extraction is insufficient.

Special table 2008-522413 gazette Japanese Patent No. 3763649 JP 2003-321448 A WO2007 / 015503

Journal of Applied Physics 100,094506, (2006) Applied Physics Letters 84, 3013, (2004) Japan Journal of Applied Physics, 44, 1974, (2005)

  The objective of this invention is providing the novel material for photoelectric conversion elements which shows a highly efficient photoelectric conversion characteristic, when it uses as a photoelectric conversion element, especially an organic thin-film solar cell.

（式中、Ｌは２価又は３価の基であり、
Ｒｇはそれぞれ、置換もしくは無置換の、ベンゼン環又はナフタレン環であり、
Ｘはそれぞれ、酸素原子、又はＮ−Ｒ^１であり、
Ｒ^１はそれぞれ、水素原子、ハロゲン原子、シアノ基、Ｃ_１〜Ｃ_２０の置換もしくは無置換のアルキル基、Ｃ_２〜Ｃ_２０の置換もしくは無置換のアルケニル基、Ｃ_２〜Ｃ_２０の置換もしくは無置換のアルキニル基、Ｃ_６〜Ｃ_２０の置換もしくは無置換のアリール基、Ｃ_３〜Ｃ_２０の置換もしくは無置換のヘテロアリール基、Ｃ_１〜Ｃ_２０の置換もしくは無置換のアルキルオキシ基、Ｃ_６〜Ｃ_２０の置換もしくは無置換のアリールオキシ基、Ｃ_６〜Ｃ_２０の置換もしくは無置換のアリールアミノ基、Ｃ_１〜Ｃ_２０の置換もしくは無置換のアルキルアミノ基であり、
ｎは２又は３である。）
２．下記式（１Ａ）で表される化合物である１に記載の化合物。

（式中、Ｌは２価の基であり、Ｒｇ及びＸは、それぞれ、前記式（１）のＲｇ及びＸと同様な基である。）
３．前記式（１）で表される化合物が、下記式（１Ｂ）又は（１Ｃ）で表わされる化合物である２に記載の化合物。

[式中、Ｘは前記式（１）のＸと同様な基であり、Ｌは、下記式（Ｌ１）〜（Ｌ１２）で表されるいずれかの基である。

（式中、Ｒ^１１〜Ｒ^２０はそれぞれ、ハロゲン原子、シアノ基、Ｃ_１〜Ｃ_２０の置換もしくは無置換のアルキル基、Ｃ_２〜Ｃ_２０の置換もしくは無置換のアルケニル基、Ｃ_２〜Ｃ_２０の置換もしくは無置換のアルキニル基、Ｃ_６〜Ｃ_２０の置換もしくは無置換のアリール基、Ｃ_３〜Ｃ_２０の置換もしくは無置換のヘテロアリール基、Ｃ_１〜Ｃ_２０の置換もしくは無置換のアルキルオキシ基、Ｃ_６〜Ｃ_２０の置換もしくは無置換のアリールオキシ基、Ｃ_６〜Ｃ_２０の置換もしくは無置換のアリールアミノ基、Ｃ_１〜Ｃ_２０の置換もしくは無置換のアルキルアミノ基である。
ａは０〜４の整数、ｂは０〜３の整数、ｃは０〜２の整数、ｄは０〜２の整数、ｅは０又は１、ｆは０〜２の整数、ｇは０〜２、ｈは０〜２の整数、iは０〜２の整数、ｊは０又は１である。
ａ〜ｉが２以上の場合、２以上のＲ^１１〜Ｒ^２０はそれぞれ同一でも異なっていてもよい。）]
４．上記１に記載の化合物を含有する電子輸送材料。
５．一対の電極の間に１〜３のいずれかに記載の化合物を含む有機薄膜太陽電池。
６．前記化合物を陰極側のバッファー層として有する５に記載の有機薄膜太陽電池。
７．上記５又は６に記載の有機薄膜太陽電池を具備する装置。 According to the present invention, the following compounds and the like are provided.
1. A compound represented by the following formula (1).

(Wherein L is a divalent or trivalent group,
Each Rg is a substituted or unsubstituted benzene ring or naphthalene ring;
Each X is an oxygen atom or N—R ¹ ;
R ¹ is a hydrogen atom, a halogen atom, a cyano group, a C _{1 to} C ₂₀ substituted or unsubstituted alkyl group, a C _{2 to} C ₂₀ substituted or unsubstituted alkenyl group, a C _{2 to} C ₂₀ substituted or unsubstituted alkynyl _groups, C substituted or unsubstituted aryl group having 6 _{~C 20, C} 3 substituted or unsubstituted heteroaryl group _{-C 20,} a substituted or unsubstituted alkyl group having C 1 _{-C 20,} substituted or unsubstituted aryloxy group C ₆ -C _20, a substituted or unsubstituted arylamino group C 6 _{-C 20,} a substituted or unsubstituted alkylamino group C 1 _{-C 20,}
n is 2 or 3. )
2. 2. The compound according to 1, which is a compound represented by the following formula (1A).

(In the formula, L is a divalent group, and Rg and X are the same groups as Rg and X in the formula (1), respectively.)
3. 3. The compound according to 2, wherein the compound represented by the formula (1) is a compound represented by the following formula (1B) or (1C).

[Wherein, X is a group similar to X in the formula (1), and L is any group represented by the following formulas (L1) to (L12).

Wherein R ^{11 to} R ²⁰ are each a halogen atom, a cyano group, a C _{1 to} C ₂₀ substituted or unsubstituted alkyl group, a C _{2 to} C ₂₀ substituted or unsubstituted alkenyl group, and a C ₂ to C _{20 20} substituted or unsubstituted alkynyl groups, C _{6 to} C ₂₀ substituted or unsubstituted aryl groups, C _{3 to} C ₂₀ substituted or unsubstituted heteroaryl groups, C _{1 to} C ₂₀ substituted or unsubstituted is an alkyl _group, C 6 _{-C 20} substituted or unsubstituted aryloxy _group, C a substituted or unsubstituted arylamino group 6 _{-C 20,} a substituted or unsubstituted alkylamino group C 1 _{-C 20} .
a is an integer of 0 to 4, b is an integer of 0 to 3, c is an integer of 0 to 2, d is an integer of 0 to 2, e is 0 or 1, f is an integer of 0 to 2, and g is 0 to 0 2, h is an integer from 0 to 2, i is an integer from 0 to 2, and j is 0 or 1.
When a to i are 2 or more, two or more R ^{11 to} R ²⁰ may be the same or different. )]
4). 2. An electron transport material containing the compound according to 1 above.
5). The organic thin-film solar cell containing the compound in any one of 1-3 between a pair of electrodes.
6). 6. The organic thin-film solar cell according to 5, having the compound as a buffer layer on the cathode side.
7). The apparatus which comprises the organic thin film solar cell of said 5 or 6.

  ADVANTAGE OF THE INVENTION According to this invention, when used as a photoelectric conversion element, especially an organic thin film solar cell, the novel material for photoelectric conversion elements which shows a highly efficient photoelectric conversion characteristic can be provided.

The compound of the present invention is a compound represented by the following formula (1).

In the formula, L is a divalent or trivalent group,
Each Rg is a substituted or unsubstituted benzene ring or naphthalene ring;
Each X is an oxygen atom or N—R ¹ ;
R ¹ is a hydrogen atom, a halogen atom, a cyano group, a C _{1 to} C ₂₀ substituted or unsubstituted alkyl group, a C _{2 to} C ₂₀ substituted or unsubstituted alkenyl group, a C _{2 to} C ₂₀ substituted or unsubstituted alkynyl _groups, C substituted or unsubstituted aryl group having 6 _{~C 20, C} 3 substituted or unsubstituted heteroaryl group _{-C 20,} a substituted or unsubstituted alkyl group having C 1 _{-C 20,} substituted or unsubstituted aryloxy group C ₆ -C _20, a substituted or unsubstituted arylamino group C 6 _{-C 20,} a substituted or unsubstituted alkylamino group C 1 _{-C 20,}
n is 2 or 3.

  The compound of formula (1) is characterized in that it contains two or three skeletal structures selected from a phthalimide skeleton, a naphthalic anhydride skeleton and a naphthalimide skeleton in the molecule. Since the compound of the present invention has two or more phthalimide skeletons, naphthalic anhydride skeletons or naphthalimide skeletons, it has high electron transport properties and a small energy barrier with respect to the electrode. In addition, naphthalimide, naphthalic anhydride, and phthalimide interact with the electrode and work as an anchor group, so that the effect of charge injection from the electrode and extraction of the charge from the electrode is high (Physical Review B. 54, 13748, (1996)). . Therefore, when used for an organic thin film solar cell, an organic thin film solar cell exhibiting highly efficient photoelectric conversion characteristics can be obtained.

  In the formula (1), L is a divalent or trivalent group. Specifically, phenyl group, pyridine group, pyrimidine group, pyrazine group, triazine group, benzoquinone group, tetracyanoquinodimethane group, thiophene group, furan group, isoxazole group, oxadiazole group, thiazole group, etc. Examples of the group include a group having one or two hydrogen atoms.

As the compound of the present invention, a compound represented by the following formula (1A) is preferable.

That is, L in the formula (1) is preferably a divalent group, and more preferably the above-described aromatic ring. Charge transportability is improved by connecting naphthalimide, naphthalic anhydride, and phthalimide with L which is an aromatic ring.
In particular, the compound represented by the formula (1A) is preferably a compound represented by the following formula (1B) or (1C).

In the formulas (1B) and (1C), L is any group represented by the following formulas (L1) to (L12).

In the formula, R ^{11 to} R ²⁰ are each a halogen atom, a cyano group, a C _{1 to} C ₂₀ substituted or unsubstituted alkyl group, a C _{2 to} C ₂₀ substituted or unsubstituted alkenyl group, and C _{2 to} C _20. Substituted or unsubstituted alkynyl group, C ₆ -C ₂₀ substituted or unsubstituted aryl group, C ₆ -C ₂₀ substituted or unsubstituted heteroaryl group, C ₁ -C ₂₀ substituted or unsubstituted alkyl oxy _group, a substituted or unsubstituted aryloxy _group, a substituted or unsubstituted arylamino group C 6 _{-C 20,} a substituted or unsubstituted alkylamino group C 1 _{-C 20} of C 6 _{-C 20.}
Cx to Cy means that the carbon number is x to y.

A substituted or unsubstituted alkyl group of C ₁ -C ₂₀ may be any of linear, branched or cyclic. Specific examples include methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl, decyl, dodecyl, 2-ethylhexyl, 3, 7 -Dimethyloctyl, cyclopropyl, cyclopentyl, cyclohexyl, 1-adamantyl, 2-adamantyl, norbornyl, trifluoromethyl, trichloromethyl, benzyl, α, α-dimethylbenzyl, 2-phenylethyl, 1-phenylethyl, etc. . Of these, methyl, ethyl, propyl, isopropyl, tert-butyl, cyclohexyl and the like are preferable from the viewpoint of availability of raw materials.

A substituted or unsubstituted alkenyl group having C ₂ -C ₂₀ straight chain, may be either branched or cyclic, as their specific examples include vinyl, propenyl, butenyl, oleyl, eicosapentaenoic enyl, Docosahexaenyl, styryl, 2,2-diphenylvinyl, 1,2,2-triphenylvinyl, 2-phenyl-2-propenyl and the like can be mentioned. Of these, vinyl, styryl, 2,2-diphenylvinyl and the like are preferable from the viewpoint of availability of raw materials.

The C _{2 to} C ₂₀ substituted or unsubstituted alkynyl group may be linear, branched or cyclic, and specific examples thereof include ethenyl, propynyl, 2-phenylethenyl and the like. . Of these, ethenyl, 2-phenylethenyl, and the like are preferable from the viewpoint of availability of raw materials.

Specific examples of the C _{6 to} C ₂₀ substituted or unsubstituted aryl group include phenyl, 2-tolyl, 4-tolyl, 4-trifluoromethylphenyl, 4-methoxyphenyl, 4-cyanophenyl, 2-biphenylyl, 3-biphenylyl, 4-biphenylyl, terphenylyl, 3,5-diphenylphenyl, 3,4-diphenylphenyl, pentaphenylphenyl, 4- (2,2-diphenylvinyl) phenyl, 4- (1,2,2-tri Phenylvinyl) phenyl, fluorenyl, 1-naphthyl, 2-naphthyl, 9-anthryl, 2-anthryl, 9-phenanthryl, 1-pyrenyl, chrycenyl, naphthacenyl, coronyl and the like. Of these, phenyl, 4-biphenylyl, 1-naphthyl, 2-naphthyl, 9-phenanthryl and the like are preferable from the viewpoint of availability of raw materials.

For substituted or unsubstituted heteroaryl group C ₃ -C _20, coupling position when the nitrogen-containing heterocyclic ring azole may be coupled with nitrogen, not only a carbon. Specific examples thereof include furan, thiophene, pyrrole, imidazole, benzimidazole, pyrazole, benzpyrazole, triazole, oxadiazole, pyridine, pyrazine, triazine, quinoline, benzofuran, dibenzofuran, benzothiophene, dibenzothiophene, carbazole and the like. Can be mentioned. Of these, furan, thiophene, pyridine, carbazole and the like are preferable from the viewpoint of availability of raw materials.

A substituted or unsubstituted alkyl group of C ₁ -C ₂₀ straight chain, may be either branched or cyclic, as their specific examples, methoxy, ethoxy, 1-propyloxy, 2-propyl Oxy, 1-butyloxy, 2-butyloxy, sec-butyloxy, tert-butyloxy, pentyloxy, hexyloxy, octyloxy, decyloxy, dodecyloxy, 2-ethylhexyloxy, 3,7-dimethyloctyloxy, cyclopropyloxy, cyclopentyl Examples thereof include oxy, cyclohexyloxy, 1-adamantyloxy, 2-adamantyloxy, norbornyloxy, trifluoromethoxy, benzyloxy, α, α-dimethylbenzyloxy, 2-phenylethoxy, 1-phenylethoxy and the like. Of these, methoxy, ethoxy, ter-butyloxy and the like are preferable from the viewpoint of availability of raw materials.

Substituted or unsubstituted aryloxy group C ₆ -C ₂₀ straight chain, may be either branched or cyclic, as their specific examples, the substituent which the aryl group is bonded through an oxygen Is mentioned. Of these, phenoxy, naphthoxy, phenanthryloxy and the like are preferable from the viewpoint of availability of raw materials.

The C _{6 to} C ₂₀ substituted or unsubstituted arylamino group may be any group in which at least one of the substituents bonded to the amino group is an aryl group. Specifically, phenylamino, methylphenylamino, diphenylamino, Di-p-tolylamino, di-m-tolylamino, phenyl-m-tolylamino, phenyl-1-naphthylamino, phenyl-2-naphthylamino, phenyl (sec-butylphenyl) amino, phenyl t-butylamino, bis (4-methoxyphenyl) ) Amino, phenyl-4-carbazolylphenylamino and the like. Of these, diphenylamino, ditolylamino, bis (4-methoxyphenyl) amino and the like are preferable from the viewpoint of availability of raw materials.

In the substituted or unsubstituted alkylamino group of C _{1 to} C ₂₀ , the alkyl groups bonded to the amino group may be the same or different, and may be bonded to each other to form a ring. Specific examples include methylamino, dimethylamino, methylethylamino, diethylamino, bis (2-hydroxyethyl) amino, bis (2-methoxyethyl) amino, piperidino, morpholino and the like. Of these, dimethylamino, diethylamino, piperidino and the like are preferable from the viewpoint of availability of raw materials.

a is an integer of 0 to 4, b is an integer of 0 to 3, c is an integer of 0 to 2, d is an integer of 0 to 2, e is 0 or 1, f is an integer of 0 to 2, and g is 0 to 0 2, h is an integer from 0 to 2, i is an integer from 0 to 2, and j is 0 or 1.
When a to i are 2 or more, two or more R ^{11 to} R ²⁰ may be the same or different. For example, when a is 2 or more, each R ¹¹ may be the same or different.

Rg in the formulas (1) and (1A) is a substituted or unsubstituted benzene ring or naphthalene ring, respectively. Examples of the substituent for Rg include the same groups as R ^{11 to} R ²⁰ described above. Specifically, a halogen atom, a cyano _group, a substituted or unsubstituted alkyl group of C 1 _{-C 20,} a substituted or unsubstituted alkenyl group having C 2 _{-C 20,} a substituted or unsubstituted C 2 _{-C 20} alkynyl _groups, C substituted or unsubstituted aryl group having 6 _{~C 20, C} 3 substituted or unsubstituted heteroaryl group _{-C 20,} a substituted or unsubstituted alkyl group having _C 1 _{~C 20,} C 6 ~ A C ₂₀ substituted or unsubstituted aryloxy group, a C _{6 to} C ₂₀ substituted or unsubstituted arylamino group, and a C _{1 to} C ₂₀ substituted or unsubstituted alkylamino group.

X in the formulas (1) and (1A) to (1C) is an oxygen atom or N—R ¹ , respectively.
R ¹ is a hydrogen atom, a halogen atom, a cyano group, a C _{1 to} C ₂₀ substituted or unsubstituted alkyl group, a C _{2 to} C ₂₀ substituted or unsubstituted alkenyl group, a C _{2 to} C ₂₀ substituted or unsubstituted alkynyl _groups, C substituted or unsubstituted aryl group having 6 _{~C 20, C} 3 substituted or unsubstituted heteroaryl group _{-C 20,} a substituted or unsubstituted alkyl group having C 1 _{-C 20,} substituted or unsubstituted aryloxy group C ₆ -C _20, a substituted or unsubstituted arylamino group C 6 _{-C 20,} a substituted or unsubstituted alkylamino group C 1 _{-C 20.}
Examples of these groups include the same groups as R ^{11 to} R ²⁰ described above.

Examples of the compound of the present invention include the following compounds.

Of these, the diphthalimide compounds shown below are preferred.

  There are various methods for synthesizing the compound of the present invention. Among them, a cross-coupling reaction using a metal catalyst typified by palladium can be mentioned. This synthetic route is preferable because the raw materials are easily available, the reaction conditions are mild, and the target product is provided in a high yield. An example of a synthesis route is shown.

In the reaction formula, Y represents a halogen element such as chlorine, bromine and iodine or a pseudohalogen substituent such as a trifluoromethanesulfonyloxy group, a nonafluorobutanesulfonyloxy group, a methanesulfonyloxy group, and a p-toluenesulfonyloxy group, M is represented by boronic acid such as B (OH) ₂ , pinacolatoboryl group, catecholboryl group and its ester reagent, organotin reagent such as Sn (Bu) ₄ , and organosilicon reagent such as Si (OH) _3. Represents a typical metal group. The typical metal group may be bonded to naphthalic anhydride (Scheme 1) or Q (Scheme 2). The conditions for reacting these pseudohalogen bonding units with typical metal reagents include Kumada-Tamao coupling (Grignard reagent), Negishi cup long (organic zinc reagent), Suzuki-Miyaura coupling (boron reagent), Kosugi-Udita, Personal name reactions such as Stille coupling (organotin reagent) and Ulsan coupling (organosilicon reagent) can be used.

  Examples of metal catalysts that can be used in this reaction include palladium chloride, palladium acetate, divalent palladium such as dichlorobis (triphenylphosphine) palladium, tetrakis (triphenylphosphine) paradidium, tris (dibenzylideneacetone) dipalladium, and the like. Divalent nickel such as zerovalent palladium, nickel chloride, dichlorobis (triphenylphosphine) nickel, dichloro (1,3-bisdiphenylphosphinopropane) nickel, tetrakis (triphenylphosphine) nickel, tetracarbonylnickel, bis (cycloocta Zero-valent nickel such as diene) nickel can be used. Moreover, a ligand can also be added to these metal catalysts. Examples of ligands that can be used in this case include pyridines such as 2,2′-bipyridine and 1,10-phenanthroline, triphenylphosphine, tri (o-tolyl) phosphine, tri (2-furyl) phosphine, Tricyclohexylphosphine, tri (t-butyl) phosphine, 2-di-t-butylphosphinobiphenyl (JohnPhos), 2-di-t-butylphosphino-2'-dimethylaminobiphenyl (DavePhos), 2-dicyclohexylphosphino- Monodentate phosphines such as 2 ′, 4 ′, 6′-triisopropyl-1,1′-biphenyl (XPhos), 2-dicyclohexylphosphino-2 ′, 6′-dimethoxybiphenyl (SPhos), 1,2-bis (Diphenylphosphino) ethane (DPPE), 1,3-bis (diph Nylphosphino) propane (DPPP), 2,2′-bis (diphenylphosphino) -1,1′-binaphthyl (BINAP), 1,1′-bis (diphenylphosphino) ferrocene (DPPF), 4,5-bis And bidentate phosphines such as (diphenylphosphino) -9,9-dimethylxanthene (XantPhos). Of these, phosphines are preferred because they give a high yield and the reaction conditions become mild.

The compound of the present invention is suitable as a material for a photoelectric conversion element, particularly as an electron transport material. Specifically, the compounds of the present invention, as large as ^{1.0 × 10 -6 (cm 2 /Vs)~2.0(cm} 2 / Vs) electron mobility.
Here, the electron mobility is calculated by the TOF (Time Of Flight) method (Optel Corporation (currently Sumitomo Heavy Industries Mechatronics Corporation, model number: TOF-401)).
Specifically, the time characteristic (transient characteristic time) of the transient current generated by light irradiation was measured at room temperature (23 degrees) for the ITO / compound layer / Al structure of the present invention, and the following equation was used. Calculate the electron mobility.
Electron mobility (cm ² / Vs) = (Invention layer (cm)) ² / (Transient characteristic time (s) · Applied voltage (V))
The electron transport material of the present invention may be formed from the compound of the present invention alone or may be formed from a mixture of the compound of the present invention and other components.

  The organic thin-film solar cell using the electron transport material of the present invention exhibits highly efficient conversion characteristics.

The cell structure of the organic thin-film solar battery of the present invention is not particularly limited as long as it is a structure containing the above compound between a pair of electrodes. Specifically, a structure having the following configuration on a stable insulating substrate can be given.
(1) Lower electrode / organic compound layer of the present invention / upper electrode (2) Lower electrode / p layer / n layer / upper electrode (3) Lower electrode / buffer layer / p layer / n layer / upper electrode (4) Lower part Electrode / p layer / n layer / buffer layer / upper electrode (5) lower electrode / buffer layer / p layer / n layer / buffer layer / upper electrode (6) lower electrode / buffer layer / p layer / i layer (or p) Mixed layer of material and n material) / n layer / buffer layer / upper electrode

  In the organic thin-film solar cell of the present invention, any material constituting the battery may contain the material of the present invention. Moreover, the member containing the material of this invention may contain the other component collectively. About the member and mixed material which do not contain the material of this invention, the well-known member and material used with an organic thin film solar cell can be used. Preferably, the compound of the present invention is used in the buffer layer on the cathode side of the device structures (3) to (6), more preferably in the buffer layer on the cathode side of the device structures (5) and (6). Hereinafter, each component will be briefly described.

1. Lower electrode, upper electrode The material of the lower electrode and the upper electrode is not particularly limited, and a known conductive material can be used. For example, a metal such as tin-doped indium oxide (ITO), gold (Au), osmium (Os), palladium (Pd) can be used as the electrode connected to the p layer, and silver as the electrode connected to the n layer. Metals such as (Ag), aluminum (Al), indium (In), calcium (Ca), platinum (Pt) lithium (Li) and the like, and binary metal systems such as Mg: Ag, Mg: In and Al: Li, Can use the electrode exemplified material connected to the P layer.
In order to obtain highly efficient photoelectric conversion characteristics, for example, when the organic thin film solar cell is a solar cell, it is desirable that at least one surface of the solar cell is sufficiently transparent in the solar spectrum. The transparent electrode is formed using a known conductive material so as to ensure predetermined translucency by a method such as vapor deposition or sputtering. The light transmittance of the electrode on the light receiving surface is preferably 10% or more. In a preferred configuration of the pair of electrode configurations, one of the electrode portions includes a metal having a high work function, and the other includes a metal having a low work function.

2. Organic compound layer One of a p layer, a mixed layer of p material and n material, or an n layer. When the material of the present invention is used for the organic compound layer, specifically, the lower electrode / the single layer of the material of the present invention / the upper electrode, the lower electrode / the material of the present invention, and the n layer material or p layer described later. Examples include a mixed layer / top electrode material.

3. p layer, n layer, i layer When the material of the present invention is used for the p layer, the n layer is not particularly limited, but a compound having a function as an electron acceptor is preferable. For example, if the organic _compound, fullerene derivatives such as _{C 60,} carbon nanotube, perylene derivatives, polycyclic quinone, quinacridone, the polymeric CN- poly (phenylene - vinylene), MEH-CN-PPV, -CN group or CF ₃ group-containing polymers, their -CF ₃ substituted polymers, poly (fluorene) derivatives and the like can be mentioned. A material having high electron mobility is preferred. Further, a material having a small electron affinity is preferable. Thus, a sufficient open-circuit voltage can be realized by combining materials having a small electron affinity as the n layer.

Moreover, if it is an inorganic compound, the inorganic semiconductor compound of an n-type characteristic can be mentioned. Specifically, doped semiconductors and compound semiconductors such as n-Si, GaAs, CdS, PbS, CdSe, InP, Nb ₂ O ₅ , WO ₃ , Fe ₂ O ₃ , titanium dioxide (TiO ₂ ), monoxide Examples include titanium oxide such as titanium (TiO) and dititanium trioxide (Ti ₂ O ₃ ), and conductive oxides such as zinc oxide (ZnO) and tin oxide (SnO ₂ ). You may use combining more than a seed. Preference is given to using titanium oxide, particularly preferably titanium dioxide.

  When the material of the present invention is used for the n layer, the p layer is not particularly limited, but a compound having a function as a hole acceptor is preferable. For example, for an organic compound, N, N′-bis (3-tolyl) -N, N′-diphenylbenzidine (mTPD), N, N′-dinaphthyl-N, N′-diphenylbenzidine (NPD), 4, Amine compounds represented by 4 ′, 4 ″ -tris (phenyl-3-tolylamino) triphenylamine (MTDATA), etc., phthalocyanine (Pc), copper phthalocyanine (CuPc), zinc phthalocyanine (ZnPc), titanyl phthalocyanine (TiOPc) ), Phthalocyanines such as octaethylporphyrin (OEP), platinum octaethylporphyrin (PtOEP), zinc tetraphenylporphyrin (ZnTPP) and the like, and polymer compounds such as polyhexylthiophene (P3HT), Methoxyethylhexyloxyphe Vinylene (MEHPPV) main chain type conjugated polymers such as side chain type polymers such as represented by polyvinyl carbazole, and the like.

  When the material of the present invention is used for the i layer, the i layer may be formed by mixing with the p layer compound or the n layer compound, but the material of the present invention can also be used alone as the i layer. In this case, any of the above exemplary compounds can be used for the p layer or the n layer.

4). Buffer layer In general, organic thin film solar cells often have a thin total film thickness, and therefore, the upper electrode and the lower electrode are short-circuited, and the yield of cell fabrication often decreases. In such a case, it is preferable to prevent this by laminating a buffer layer.
For the buffer layer, the material of the present invention is preferable, but as the other compound, a compound having sufficiently high carrier mobility is preferable so that the short-circuit current does not decrease even when the film thickness is increased. For example, if it is a low molecular compound, the aromatic cyclic acid anhydride represented by NTCDA shown below etc. will be mentioned, and if it is a high molecular compound, poly (3,4-ethylenedioxy) thiophene: polystyrene sulfonate (PEDOT: PSS), polyaniline: camphorsulfonic acid (PANI: CSA), and other known conductive polymers.

5). Substrate The substrate preferably has mechanical and thermal strength and transparency. For example, there are a glass substrate and a transparent resin film. Transparent resin films include polyethylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polypropylene, polystyrene, polymethyl methacrylate, polyvinyl chloride, polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone. , Polysulfone, polyethersulfone, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polyvinyl fluoride, tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polychlorotrifluoroethylene, Polyvinylidene fluoride, polyester, polycarbonate, polyurethane, polyimide, polyetherimide, polyimide, polypropylene, etc. It is.

The formation of each layer of the organic thin film solar cell of the present invention is performed by a dry film formation method such as vacuum deposition, sputtering, plasma, ion plating, or wet film formation such as spin coating, dip coating, casting, roll coating, flow coating, and ink jet. The law can be applied.
The thickness of each layer is not particularly limited, but is set to an appropriate thickness. Since it is generally known that the exciton diffusion length of an organic thin film is short, if the film thickness is too thick, the exciton is deactivated before reaching the heterointerface, resulting in low photoelectric conversion efficiency. If the film thickness is too thin, pinholes and the like are generated, so that sufficient diode characteristics cannot be obtained, resulting in a decrease in conversion efficiency. The normal film thickness is suitably in the range of 1 nm to 10 μm, but more preferably in the range of 5 nm to 0.2 μm.

  In the case of the dry film forming method, a known resistance heating method is preferable, and for forming the mixed layer, for example, a film forming method by simultaneous vapor deposition from a plurality of evaporation sources is preferable. More preferably, the substrate temperature is controlled during film formation.

  In the case of a wet film forming method, a material for forming each layer is dissolved or dispersed in an appropriate solvent to prepare a luminescent organic solution to form a thin film, and any solvent can be used. For example, halogenated hydrocarbon solvents such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride, tetrachloroethane, trichloroethane, chlorobenzene, dichlorobenzene, chlorotoluene, ether solvents such as dibutyl ether, tetrahydrofuran, dioxane, anisole, methanol, Alcohol solvents such as ethanol, propanol, butanol, pentanol, hexanol, cyclohexanol, methyl cellosolve, ethyl cellosolve, ethylene glycol, hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, hexane, octane, decane, tetralin, Examples include ester solvents such as ethyl acetate, butyl acetate, and amyl acetate. Of these, hydrocarbon solvents or ether solvents are preferable. These solvents may be used alone or in combination. In addition, the solvent which can be used is not limited to these.

In the present invention, in any organic thin film layer of the organic thin film solar cell, an appropriate resin or additive may be used for improving the film formability and preventing pinholes in the film. Usable resins include polystyrene, polycarbonate, polyarylate, polyester, polyamide, polyurethane, polysulfone, polymethyl methacrylate, polymethyl acrylate, cellulose and other insulating resins and copolymers thereof, poly-N-vinyl. Examples thereof include photoconductive resins such as carbazole and polysilane, and conductive resins such as polythiophene and polypyrrole.
Examples of the additive include an antioxidant, an ultraviolet absorber, and a plasticizer.

[Synthesis of the compound of the present invention]
Example 1
Compound A (phthalimide compound) was synthesized by the following reaction.

(1) Synthesis of Intermediate A1 Under a nitrogen atmosphere, 4-bromo-phthalic anhydride (15 g, 66.1 mmol), methylamine (40% in H ₂ O) (8.26 ml, 99.1 mmol), sodium acetate ( Acetic acid (100 ml) was added to 8.67 g, 106 mmol), and the mixture was heated to reflux with stirring for 6 hours. Water (200 ml) was added to the reaction mixture, and the precipitate was filtered off to obtain a white solid (15.2 g, 96%).
The results of nuclear magnetic resonance measurement ( ¹ H-NMR) of this solid are shown below.
¹ H-NMR (400 MHz, CDCl ₃ , TMS) δ: 3.18 (s, 3H), 7.71 (d, J8.0, 1H), 7.84 (d, J8.0, 1H), 7 .98 (s, 1H).

(2) Synthesis of intermediate A2 Under nitrogen atmosphere, intermediate A1 (10 g, 41.7 mmol), bis (pinacolato) diboron (13 g, 50.0 mmol), 1,1′-bis (diphenylphosphino) ferrocene] palladium (II) Dichloride Dichloromethane complex (0.65 g, 0.80 mmol), potassium acetate (30 g, 305 mmol), dioxane 100 ml) was added, and the mixture was stirred at 80 ° C. for 12 hours. Ethyl acetate (300 ml) and water (50 ml) were added to the reaction mixture, the organic layer was separated, dried over anhydrous magnesium sulfate, and the solvent was distilled off to obtain a white solid. This was purified by column chromatography (silica gel / hexane: ethyl acetate = 3: 1) to obtain a white solid (8.0 g, 67%).
¹ H-NMR (400 MHz, CDCl ₃ , TMS) δ: 1.37 (s, 12H), 3.18 (s, 3H), 7.82 (d, J8.0, 1H), 8.14 (d , J8.0, 1H), 8.27 (s, 1H).

(3) Synthesis of Compound A Under a nitrogen atmosphere, intermediate A2 (1.0 g, 3.8 mmol), 1,3-dibromobenzene (0.41 g, 1.74 mmol), cesium fluoride (0.79 g, 5. 22 mmol), tetrakis (triphenylphosphine) palladium (0) (0.1 g, 8.7 × 10 ⁻² mmol), and 1,2-dimethoxyethane (17 ml) were added and stirred at 80 ° C. for 6 hours. Water (50 ml) was added to the reaction mixture, and the precipitate was filtered off to obtain Compound A as a white solid (0.15 g, 21%).
¹ H-NMR (400 MHz, CDCl ₃ , TMS) δ: 3.23 (s, 6H), 7.65 (s, J6.8, 1H), 7.71 (d, J6.8, 2H), 7 .88 (s, 1H), 7.65 (d, J6.8, 1H), 7.98 (d, J7.6, 2H), 8.00. (S, 2H), 8.11 (d, J7.6, 2H).

Example 2
Compound B (phthalimide compound) was synthesized by the following reaction.

Intermediate A2 (2.0 g, 6.97 mmol) synthesized in Example 1 (2), 4,6-dichloropyrimidine (0.35 g, 2.32 mmol), cesium carbonate (3.4 g, 10) under nitrogen atmosphere .4 mmol), tetrakis (triphenylphosphine) palladium (0) (0.13 g, 0.12 mmol), and 1,2-dimethoxyethane (46 ml) were added and stirred at 80 ° C. for 6 hours. Water (50 ml) was added to the reaction mixture, and the precipitate was filtered off to obtain Compound B as a yellow solid (0.54 g, 58%).
¹ H-NMR (400 MHz, CDCl ₃ , TMS) δ: 3.26 (s, 6H), 8.05 (d, J8.0, 2H), 8.30 (s, 1H), 8.61 (d , J8.0, 2H), 8.64 (s, 2H), 9.45 (s, 1H).

Example 3
Compound C (naphthalimide compound) was synthesized by the following reaction.

(1) Synthesis of Intermediate C1 Under nitrogen atmosphere, 4-bromo-1,8-naphthalic anhydride (10 g, 36 mmol), methylamine (4.5 ml, 54 mmol), sodium acetate (4.8 g, 58 mmol) in ice Acetic acid (110 ml) was added and the mixture was heated to reflux with stirring for 6 hours. Water (200 ml) was added to the reaction mixture, and the precipitate was filtered off to obtain a white solid (9.9 g, 95%).
¹ H-NMR (400 MHz, CDCl ₃ , TMS) δ: 3.56 (s, 3H), 7.85 (t, J8.4, 1H), 8.05 (d, J8.0, 1H), 8 .43 (d, J8.0, 1H), 8.58 (d, J7.6, 1H), 8.67 (d, J7.6, 1H).

(2) Synthesis of Intermediate C2 Under a nitrogen atmosphere, intermediate A1 (5.0 g, 17 mmol), bis (pinacolato) diboron (4.8 g, 1.9 mmol), 1,1′-bis (diphenylphosphino) ferrocene Palladium (II) dichloride Dichloromethane complex (0.70 g, 0.86 mmol), potassium acetate (8.5 g, 86 mmol) and dioxane (50 ml) were added and stirred at 80 ° C. for 12 hours. Dichloromethane (150 ml) and water (50 ml) were added to the reaction mixture, the organic layer was separated, dried over anhydrous magnesium sulfate, and the solvent was distilled off to obtain a pale yellow solid. This was purified by column chromatography (silica gel / hexane: dichloromethane = 1: 3) to obtain a white solid (3.7 g, 65%).
¹ H-NMR (400 MHz, CDCl ₃ , TMS) δ: 1.45 (s, 12H), 3.57 (s, 3H), 7.78 (t, J8.4, 1H), 8.30 (d , J7.6, 1H), 8.62 (d, J7.2, 1H), 9.12 (d, J8.4, 1H).

(3) Synthesis of Compound C In a nitrogen atmosphere, intermediate A2 (0.4 g, 1.2 mmol) ”, 1,3-dibromobenzene (0.1 g, 0.5 mmol), tetrakis (triphenylphosphine) palladium (0 ) (0.03 g, 2.8 × 10 ⁻² mmol) was suspended in 1,2-dimethoxyethane (10 ml), 2M aqueous sodium carbonate solution (2.1 g, 21 mmol / 10 ml) was added, and the mixture was heated at 80 ° C. for 6 hours. Stir. Water (50 ml) was added to the reaction mixture, and the precipitate was filtered off to obtain a white solid. This was then recrystallized from dichloromethane (150 ml) to obtain Compound C as a white solid (0.15 g, 65%).
¹ H-NMR (400 MHz, CDCl ₃ , TMS) δ: 3.62 (s, 6H), 7.86 (t, J7.2, 2H), 8.03 (d, J7.2, 2H), 8 .06 (s, 1H), 8.72-8.76 (m, 6H), 9.67 (s, 1H).

Example 4
Compound D (naphthalimide compound) was synthesized by the following reaction.

Synthesis of Naphthalimide Compound D Intermediate C2 (1.0 g, 3.0 mmol), 4,6-dichloropyrimidine (0.2 g, 1.4 mmol), tetrakis (synthesized in Example 3 (2) under nitrogen atmosphere Triphenylphosphine) palladium (0) (0.1 g, 9.0 × 10 ⁻² mmol) was suspended in 1,2-dimethoxyethane (30 ml), and 2M aqueous sodium carbonate solution (2.1 g, 21 mmol / 10 ml) was added. In addition, the mixture was stirred at 80 ° C. for 6 hours. Water (50 ml) was added to the reaction mixture, and the precipitate was filtered off to obtain a white solid. This was then recrystallized from dichloromethane (150 ml) to obtain Compound D as a white solid (0.65 g, 87%).
¹ H-NMR (400 MHz, CDCl ₃ , TMS) δ: 3.60 (s, 6H), 7.68 (d, J6.8, 2H), 7.69 (d, J6.8, 1H), 7 .75 (d, J7.2, 2H), 7.78 (t, J8.4, 2H), 7.81 (s, 1H), 7.75 (s, 1H), 8.36 (d, J8 .4, 2H), 8.67 (d, J7.6, 2H), 8.69 (d, J7.6, 2H).

Example 5
Compound E (naphthalimide compound) was synthesized by the following reaction.

Under a nitrogen atmosphere, intermediate C2 (1.0 g, 3.0 mmol), 1,4-dibromobenzene (0.32 g, 1.35 mmol), tetrakis (triphenylphosphine) palladium (0) (0.078 g, 6. 74 × 10 ⁻² mmol) was suspended in 1,2-dimethoxyethane (14 ml), 2M aqueous sodium carbonate solution (2.1 g, 21 mmol / 10 ml) was added, and the mixture was stirred at 80 ° C. for 6 hours. Water (50 ml) was added to the reaction mixture, and the precipitate was filtered off to obtain a white solid. This was then recrystallized from dichloromethane (150 ml) to obtain Compound E as a yellow solid (0.61 g, 91%).
¹ H-NMR (400 MHz, CDCl ₃ , TMS) δ: 3.62 (s, 6H), 7.61 (s, 4H), 7.81 (d, J8.0, 2H), 7.86 (d , J8.0, 2H), 8.45 (d, J8.0, 2H), 8.70 (d, J8.0, 2H) 8.72 (d, J8.0, 2H).

Example 6
Compound F (a naphthalic anhydride compound) was synthesized by the following reaction.

Under a nitrogen atmosphere, Compound C (2.0 g, 4.0 mmol), potassium hydroxide (45 g, 800 mmol), and isopropanol (150 ml) were added, and the mixture was heated to reflux with stirring for 6 hours. Thereafter, acetic acid (250 ml) was added to the reaction mixture, and the precipitate was filtered off to obtain Compound F as a yellow solid (1.8 g, 96%).
¹ H-NMR (400 MHz, CDCl ₃ , TMS) δ: 7.61 (s, 1H), 7.67 (s, 1H), 7.71 (d, J7.2, 2H), 7.81 (d , J8.0, 2H), 7.86 (d, J8.0, 2H), 8.45 (d, J8.0, 2H), 8.70 (d, J8.0, 2H) 8.72 ( d, J8.0, 2H).

[Production of organic thin-film solar cells]
Examples 7-12
A glass substrate with an ITO transparent electrode having a thickness of 25 mm × 75 mm × 0.7 mm was subjected to ultrasonic cleaning in isopropyl alcohol for 5 minutes, and then UV ozone cleaning was performed for 30 minutes. A glass substrate with a transparent electrode line after cleaning is mounted on a substrate holder of a vacuum deposition apparatus, and a film having a film thickness of 30 nm is first covered on the surface on the side where the transparent electrode line as the lower electrode is formed so as to cover the transparent electrode. CuPc was deposited at 1 Å / s by resistance heating vapor deposition. Subsequently, C ₆₀ having a film thickness of 60 nm was formed thereon at 1 Å / s by resistance heating vapor deposition.
On the _C60 film, any one of the compounds A to F shown in Table 1 was formed at a thickness of 10 nm and 1 Å / s by resistance heating vapor deposition. Finally, metal Al was deposited in a thickness of 80 nm continuously as a counter electrode to form an organic thin film solar cell. The area was 0.05 cm ² .
The IV characteristic was measured for the produced organic thin film solar cell under AM1.5 conditions (light intensity 100 mW / cm ² ). As a result, open circuit voltage (Voc), short circuit current density (Jsc), fill factor (FF), and conversion efficiency (η) are shown in Table 1.

The photoelectric conversion efficiency was derived from the following formula.

Comparative Example 1
An organic thin film solar cell was prepared and evaluated in the same manner as in Example 1 except that the film of Compound A was not formed. The results are shown in Table 1.

Comparative Example 2
An organic thin-film solar cell was prepared and evaluated in the same manner as in Example 1 except that Compound A in Example 1 was replaced with lithium fluoride (LiF). The results are shown in Table 1.

  As can be seen from Table 1, the conversion efficiency of the compound of the present invention is improved as compared with the comparative example, and it is clear that the solar cell characteristics are excellent.

The compound of the present invention is suitable as a material for a photoelectric conversion element, particularly as an electron transport material. Moreover, it is suitable as an organic thin film solar cell material.
The organic thin film solar cell of the present invention can be used for watches, mobile phones, mobile personal computers and the like.

Claims (7)

A compound represented by the following formula (1).

(Wherein L is a divalent or trivalent group,
Each Rg is a substituted or unsubstituted benzene ring or naphthalene ring;
Each X is an oxygen atom or N—R ¹ ;
R ¹ is a hydrogen atom, a halogen atom, a cyano group, a C _{1 to} C ₂₀ substituted or unsubstituted alkyl group, a C _{2 to} C ₂₀ substituted or unsubstituted alkenyl group, a C _{2 to} C ₂₀ substituted or unsubstituted alkynyl _groups, C substituted or unsubstituted aryl group having 6 _{~C 20, C} 3 substituted or unsubstituted heteroaryl group _{-C 20,} a substituted or unsubstituted alkyl group having C 1 _{-C 20,} substituted or unsubstituted aryloxy group C ₆ -C _20, a substituted or unsubstituted arylamino group C 6 _{-C 20,} a substituted or unsubstituted alkylamino group C 1 _{-C 20,}
n is 2 or 3. ) The compound according to claim 1, which is a compound represented by the following formula (1A).

(In the formula, L is a divalent group, and Rg and X are the same groups as Rg and X in the formula (1), respectively.) The compound according to claim 2, wherein the compound represented by the formula (1) is a compound represented by the following formula (1B) or (1C).

[Wherein, X is a group similar to X in the formula (1), and L is any group represented by the following formulas (L1) to (L12).

Wherein R ^{11 to} R ²⁰ are each a halogen atom, a cyano group, a C _{1 to} C ₂₀ substituted or unsubstituted alkyl group, a C _{2 to} C ₂₀ substituted or unsubstituted alkenyl group, and a C ₂ to C _{20 20} substituted or unsubstituted alkynyl groups, C _{6 to} C ₂₀ substituted or unsubstituted aryl groups, C _{3 to} C ₂₀ substituted or unsubstituted heteroaryl groups, C _{1 to} C ₂₀ substituted or unsubstituted is an alkyl _group, C 6 _{-C 20} substituted or unsubstituted aryloxy _group, C a substituted or unsubstituted arylamino group 6 _{-C 20,} a substituted or unsubstituted alkylamino group C 1 _{-C 20} .
a is an integer of 0 to 4, b is an integer of 0 to 3, c is an integer of 0 to 2, d is an integer of 0 to 2, e is 0 or 1, f is an integer of 0 to 2, and g is 0 to 0 2, h is an integer from 0 to 2, i is an integer from 0 to 2, and j is 0 or 1.
When a to i are 2 or more, two or more R ^{11 to} R ²⁰ may be the same or different. )]   An electron transport material containing the compound according to claim 1.   The organic thin-film solar cell containing the compound in any one of Claims 1-3 between a pair of electrodes.   The organic thin-film solar cell of Claim 5 which has the said compound as a buffer layer by the side of a cathode.   The apparatus which comprises the organic thin-film solar cell of Claim 5 or 6.