WO2017217448A1

WO2017217448A1 - Fullerene derivative, and n-type semiconductor material

Info

Publication number: WO2017217448A1
Application number: PCT/JP2017/021933
Authority: WO
Inventors: 永井　隆文; 足達　健二; 安蘇　芳雄; 家　裕隆; 誠辛川
Original assignee: ダイキン工業株式会社; 国立大学法人大阪大学
Priority date: 2016-06-14
Filing date: 2017-06-14
Publication date: 2017-12-21
Also published as: JPWO2017217448A1; JP6931891B2

Abstract

The present invention addresses the problem of providing a material having excellent properties as an n-type semiconductor, particularly an n-type semiconductor for a photoconverter of an organic thin-film solar battery, and the like. Provided is a fullerene derivative represented by general formula (1) [where X^1a is a hydrogen atom, chlorine atom, bromine atom, iodine atom, alkyl group optionally having one or more substituent groups, alkoxy group optionally having one or more substituent groups, or cyano group; X^1b is a chlorine atom, bromine atom, iodine atom, alkyl group optionally having one or more substituent groups, alkoxy group optionally having one or more substituent groups, or cyano group; R² is an aryl group optionally having one or more substituent groups or heteroaryl group optionally having one or more substituent groups; R³ is a hydrogen atom or organic group; and ring A is a fullerene ring].

Description

Fullerene derivative and n-type semiconductor material

The present invention relates to a fullerene derivative, an n-type semiconductor material, and the like.

An organic thin film solar cell is formed by using an organic compound as a photoelectric conversion material by a coating method from a solution. 1) Low cost for manufacturing a device 2) Easy to enlarge 3) Compared with inorganic materials such as silicon, it has various advantages such as being flexible and widening the place where it can be used, and 4) being less worried about resource depletion. For this reason, in recent years, organic thin film solar cells have been developed, and in particular, conversion efficiency can be greatly improved by employing a bulk heterojunction structure, which has attracted widespread attention.

Among the materials for photoelectric conversion substrates used in organic thin-film solar cells, for p-type semiconductors, poly-3-hexylthiophene (P3HT) is known as an organic p-type semiconductor material having excellent performance. Recently, a compound with a structure that can absorb a wide range of wavelengths of sunlight or a structure in which the energy level is adjusted has been developed aiming at higher functionality (donor acceptor type π-conjugated polymer), which greatly improves performance. Contributing. Examples of such compounds include poly-p-phenylene vinylene, poly [[4,8-bis [(2-ethylhexyl) oxy] benzo [1,2-b: 4,5-b ′] dithiophene-2. , 6-diyl] [3-fluoro-2-[(2-ethylhexyl) carbonyl] thieno [3,4-b] thiophenediyl]] (PTB7).

On the other hand, fullerene derivatives have been actively studied for n-type semiconductors, and [6,6] -phenyl C61-butyric acid methyl ester (PCBM) has been reported as a material having excellent photoelectric conversion performance (described later). (See Patent Documents 1 and 2). However, with respect to fullerene derivatives other than PCBM, there are few examples that have been demonstrated to stably achieve good conversion efficiency.

PCBM is a fullerene derivative having a three-membered ring portion, and most of the fullerene derivatives that have been reported so far are fullerene derivatives having a three-membered ring portion like PCBM.

On the other hand, fullerene derivatives having a 5-membered ring portion are also known as fullerene derivatives other than fullerene derivatives having a 3-membered ring portion, but there are few reports. Non-Patent Document 1 discloses a fullerene derivative having a pyrrolidine ring and having substituents only at the 1-position and 2-position thereof. Patent Document 3 discloses a fullerene derivative having a pyrrolidine ring and having a substituted or unsubstituted phenyl group at the 1-position among the fullerene derivatives having substituents only at the 1-position and 2-position thereof. Has a high conversion efficiency when used as an n-type semiconductor of a solar cell. Patent Document 4 discloses a fullerene derivative having a pyrrolidine ring and having substituents only at the 1-position and the 2-position thereof. Patent Document 5 discloses a fullerene derivative having two or more pyrrolidine rings. Non-Patent Document 2 discloses that a fullerene derivative having a pyrrolidine ring and having a phenyl group at the 1-position is effective as an n-type semiconductor for organic thin-film solar cells.

JP 2009-84264 A JP 2010-92964 A JP 2012-089538 A International Publication No. 2014/185536 JP 2011-181719 A

The device using the fullerene derivative described in Non-Patent Document 1 achieves higher conversion efficiency than the device using PCBM. This is a special device in which the anode (ITO electrode) current collecting material is removed. It is a comparison in configuration.
Thus, a practical organic thin-film solar cell using a fullerene derivative has not yet been developed, and a new fullerene derivative that can be used for n-type semiconductor materials of an organic thin-film solar cell is still available. Development is required.

The main object of the present invention is to provide a material having excellent performance as an n-type semiconductor, particularly an n-type semiconductor for a photoelectric conversion element such as an organic thin film solar cell.

As a performance excellent as an n-type semiconductor for a photoelectric conversion element such as an organic thin film solar cell, typically, high conversion efficiency is exemplified.
Accordingly, one of the objects of the present invention is to provide a new fullerene derivative capable of realizing high conversion efficiency.

Usually, in order to operate an electric device, a driving voltage higher than a certain level is required. For this reason, when the output voltage of one cell of a solar cell is low, many cells are needed. Here, if an n-type semiconductor capable of generating a high voltage is provided, the number of necessary cells can be reduced, and thus the space of the solar cell can be saved.
That is, there is a demand for a material that can easily form a thin film by a coating method in device fabrication and that can exhibit high power generation efficiency.
Accordingly, one of the objects of the present invention is to provide a new fullerene derivative that allows easy device fabrication and enables high voltage output.
Accordingly, an object of the present invention is to provide a fullerene derivative having high conversion efficiency and enabling high voltage output.

The present inventors have found that the above problem can be solved by a fullerene derivative represented by the following formula (1).

The present invention includes the following aspects.

Item 1.
Formula (1):

[Where:
X ^1a is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group optionally having one or more substituents, an alkoxy group optionally having one or more substituents, or cyano Represents a group,
X ^1b represents a chlorine atom, a bromine atom, an iodine atom, an alkyl group optionally having one or more substituents, an alkoxy group optionally having one or more substituents, or a cyano group. ,
R ² represents an aryl group which may have one or more substituents, or a heteroaryl group which may have one or more substituents;
R ³ represents a hydrogen atom or an organic group, and ring A represents a fullerene ring. ]
A fullerene derivative represented by:
Item 2.
Item 2. The fullerene derivative according to Item 1, wherein X ^1a is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, a methyl group, a methoxy group, or a cyano group.
Item 3.
Item 3. The fullerene derivative according to Item 2, wherein X ^1a is a chlorine atom, a bromine atom, an iodine atom, a methyl group, a methoxy group, or a cyano group.
Item 4.
Item 4. The fullerene derivative according to any one of Items 1 to 3, wherein X ^1b is a chlorine atom, a bromine atom, an iodine atom, a methyl group, a methoxy group, or a cyano group.
Item 5.
Item 5. The fullerene derivative according to any one of Items 1 to 4, wherein R ² is an aryl group which may have one or more substituents.
Item 6.
Item 6. The fullerene derivative according to Item 5, wherein R ² is a phenyl group optionally having one or two substituents at the ortho position.
Item 7.
Item 7. The fullerene derivative according to any one of Items 1 to 6, wherein R ³ is a hydrogen atom or an alkyl group.
Item 8.
Item 8. The fullerene derivative according to any one of Items 1 to 7, wherein Ring A is a C ₆₀ fullerene ring.
Item 9.
Item 9. An n-type semiconductor material containing the fullerene derivative according to any one of Items 1 to 8.
Item 10.
Item 10. The n-type semiconductor material according to Item 9, which is for organic thin film solar cells.
Item 11.
Item 11. An organic power generation layer containing the n-type semiconductor material according to Item 10.
Item 12.
Item 12. A photoelectric conversion element comprising the organic power generation layer according to Item 11.
Item 13.
Item 13. The photoelectric conversion element according to Item 12, which is an organic thin film solar cell.

According to the present invention, a fullerene derivative having high conversion efficiency and enabling high voltage output is provided.

Terms Symbols and abbreviations in this specification can be understood within the context of this specification unless otherwise specified, and can be understood as meanings commonly used in the technical field to which the present invention belongs.
In this specification, the phrase “containing” is intended to encompass the phrase “consisting essentially of” and the phrase “consisting of”.
Unless specifically limited, the steps, processes, or operations described herein can be performed at room temperature.
In the present specification, room temperature means a temperature within the range of 10 to 40 ° C.

In the present specification, unless otherwise specified, the “organic group” means a group containing one or more carbon atoms as its constituent atoms.

In the present specification, unless otherwise specified, examples of the “organic group” include a hydrocarbon group.

In this specification, unless otherwise specified, the “hydrocarbon group” means a group containing one or more carbon atoms and one or more hydrogen atoms as its constituent atoms. In the present specification, a hydrocarbon group may be referred to as a hydrocarbyl group.

In the present specification, unless otherwise specified, the “hydrocarbon group” includes an aliphatic hydrocarbon group (eg, benzyl group) optionally substituted with one or more aromatic hydrocarbon groups, and one An aromatic hydrocarbon group (aryl group) which may be substituted with the above aliphatic hydrocarbon group is exemplified.

In the present specification, unless otherwise specified, the “aliphatic hydrocarbon group” may be linear, branched, cyclic, or a combination thereof.

In the present specification, unless otherwise specified, the “aliphatic hydrocarbon group” may be saturated or unsaturated.

In the present specification, unless otherwise specified, examples of the “aliphatic hydrocarbon group” include an alkyl group, an alkenyl group, an alkynyl group, and a cycloalkyl group.

In the present specification, unless otherwise specified, examples of the “alkyl group” include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, and hexyl. And a linear or branched alkyl group having 1 to 10 carbon atoms.

In the present specification, unless otherwise specified, examples of the “alkenyl group” include vinyl, 1-propenyl, isopropenyl, 2-methyl-1-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, -Ethyl-1-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 4-methyl-3-pentenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, and 5- Examples thereof include straight-chain or branched alkenyl groups having 2 to 10 carbon atoms such as hexenyl.

In the present specification, unless otherwise specified, examples of the “alkynyl group” include ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-pentynyl, 2-pentynyl, Linear or branched alkynyl groups having 2 to 6 carbon atoms, such as 3-pentynyl, 4-pentynyl, 1-hexynyl, 2-hexynyl, 3-hexynyl, 4-hexynyl, and 5-hexynyl Is exemplified.

In the present specification, unless otherwise specified, examples of the “cycloalkyl group” include cycloalkyl groups having 3 to 8 carbon atoms such as cyclopentyl group, cyclohexyl group, and cycloheptyl.

In the present specification, unless otherwise specified, the “alkoxy group” is, for example, a group represented by RO— (wherein R is an alkyl group).

In the present specification, unless otherwise specified, the “ester group” means an organic group having an ester bond (that is, —C (═O) —O— or —OC (═O) —). Examples thereof are a group represented by the formula: RCO ₂ — (wherein R is an alkyl group), and a formula: R ^a —CO ₂ —R ^b — (wherein R ^a is an alkyl group. And R ^b is an alkylene group.).

In the present specification, unless otherwise specified, the “ether group” means a group having an ether bond (—O—).

Examples of “ether groups” include polyether groups. Examples of polyether groups are of the formula: R ^a — (O—R ^b ) _n — (wherein R ^a is an alkyl group, R ^b is the same or different at each occurrence, is an alkylene group, and n is an integer of 1 or more). An alkylene group is a divalent group formed by removing one hydrogen atom from the alkyl group.

Examples of “ether groups” also include hydrocarbyl ether groups. The hydrocarbyl ether group means a hydrocarbon group having one or more ether bonds. The “hydrocarbyl group having one or more ether bonds” can be a hydrocarbyl group in which one or more ether bonds are inserted. Examples include the benzyloxy group.

Examples of “hydrocarbon groups having one or more ether bonds” include alkyl groups having one or more ether bonds. The “alkyl group having one or more ether bonds” can be an alkyl group in which one or more ether bonds are inserted. In the present specification, such a group may be referred to as an alkyl ether group.

In the present specification, unless otherwise specified, the “acyl group” includes an alkanoyl group. In the present specification, unless otherwise specified, the “alkanoyl group” is, for example, a group represented by RCO— (wherein R is an alkyl group).

In the present specification, unless otherwise specified, the “aryl group” may be monocyclic, bicyclic, tricyclic, or tetracyclic.
In the present specification, unless otherwise specified, the “aryl group” may be an aryl group having 6 to 18 carbon atoms.
In the present specification, unless otherwise specified, examples of the “aryl group” include phenyl, 1-naphthyl, 2-naphthyl, 2-biphenyl, 3-biphenyl, 4-biphenyl, and 2-anthryl.

In the present specification, unless otherwise specified, the “heteroaryl group” is, for example, a monocyclic, bicyclic, or tricyclic or tetracyclic 5- to 18-membered heteroaryl group. Can do.
In the present specification, unless otherwise specified, the “heteroaryl group” refers to, for example, 1 to 4 heteroatoms selected from an oxygen atom, a sulfur atom, and a nitrogen atom in addition to a carbon atom as a ring-constituting atom. It is a heteroaryl group to be contained. The “heteroaryl group” may have 3 to 17 carbon atoms, for example.
In the present specification, unless otherwise specified, the “heteroaryl group” includes a “monocyclic heteroaryl group” and an “aromatic fused heterocyclic group”.

Unless otherwise specified, in this specification, examples of the “monocyclic heteroaryl group” include pyrrolyl (eg, 1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl), furyl (eg, 2-furyl, 3 -Furyl), thienyl (eg, 2-thienyl, 3-thienyl), pyrazolyl (eg, 1-pyrazolyl, 3-pyrazolyl, 4-pyrazolyl), imidazolyl (eg, 1-imidazolyl, 2-imidazolyl, 4-imidazolyl) , Isoxazolyl (eg, 3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl), oxazolyl (eg, 2-oxazolyl, 4-oxazolyl, 5-oxazolyl), isothiazolyl (eg, 3-isothiazolyl, 4-isothiazolyl, 5-isothiazolyl) ), Thiazolyl (eg, 2-thiazolyl, 4-thiazolyl, 5-thiazolyl) , Triazolyl (eg, 1,2,3-triazol-4-yl, 1,2,4-triazol-3-yl), oxadiazolyl (eg, 1,2,4-oxadiazol-3-yl, 1, 2,4-oxadiazol-5-yl), thiadiazolyl (eg, 1,2,4-thiadiazol-3-yl, 1,2,4-thiadiazol-5-yl), tetrazolyl, pyridyl (eg, 2- Pyridyl, 3-pyridyl, 4-pyridyl), pyridazinyl (eg, 3-pyridazinyl, 4-pyridazinyl), pyrimidinyl (eg, 2-pyrimidinyl, 4-pyrimidinyl, 5-pyrimidinyl), pyrazinyl and the like.

Unless otherwise specified, in this specification, examples of the “aromatic fused heterocyclic group” include isoindolyl (eg, 1-isoindolyl, 2-isoindolyl, 3-isoindolyl, 4-isoindolyl, 5-isoindolyl, 6- Isoindolyl, 7-isoindolyl), indolyl (eg, 1-indolyl, 2-indolyl, 3-indolyl, 4-indolyl, 5-indolyl, 6-indolyl, 7-indolyl), benzo [b] furanyl (eg, 2-indolyl) Benzo [b] furanyl, 3-benzo [b] furanyl, 4-benzo [b] furanyl, 5-benzo [b] furanyl, 6-benzo [b] furanyl, 7-benzo [b] furanyl), benzo [c ] Furanyl (eg, 1-benzo [c] furanyl, 4-benzo [c] furanyl, 5-benzo [c] furanyl), benzo [b Thienyl (eg, 2-benzo [b] thienyl, 3-benzo [b] thienyl, 4-benzo [b] thienyl, 5-benzo [b] thienyl, 6-benzo [b] thienyl, 7-benzo [b ] Thienyl), benzo [c] thienyl (eg, 1-benzo [c] thienyl, 4-benzo [c] thienyl, 5-benzo [c] thienyl), indazolyl (eg, 1-indazolyl, 2-indazolyl, 3 -Indazolyl, 4-indazolyl, 5-indazolyl, 6-indazolyl, 7-indazolyl), benzimidazolyl (eg, 1-benzimidazolyl, 2-benzimidazolyl, 4-benzoimidazolyl, 5-benzimidazolyl), 1,2-benzisoxazolyl (Eg, 1,2-benzisoxazol-3-yl, 1,2-benzisoxazol-4-yl 1,2-benzisoxazol-5-yl, 1,2-benzisoxazol-6-yl, 1,2-benzisoxazol-7-yl), benzoxazolyl (eg, 2-benzoxazolyl , 4-benzoxazolyl, 5-benzoxazolyl, 6-benzoxazolyl, 7-benzoxazolyl), 1,2-benzisothiazolyl (eg, 1,2-benzoisothiazole- 3-yl, 1,2-benzisothiazol-4-yl, 1,2-benzisothiazol-5-yl, 1,2-benzisothiazol-6-yl, 1,2-benzisothiazol-7- Yl), benzothiazolyl (eg, 2-benzothiazolyl, 4-benzothiazolyl, 5-benzothiazolyl, 6-benzothiazolyl, 7-benzothiazolyl), isoquinolyl (eg, 1 -Isoquinolyl, 3-isoquinolyl, 4-isoquinolyl, 5-isoquinolyl), quinolyl (eg, 2-quinolyl, 3-quinolyl, 4-quinolyl, 5-quinolyl, 8-quinolyl), cinnolinyl (eg, 3-cinnolinyl, 4 -Cinnolinyl, 5-cinnolinyl, 6-cinnolinyl, 7-cinnolinyl, 8-cinnolinyl), phthalazinyl (eg, 1-phthalazinyl, 4-phthalazinyl, 5-phthalazinyl, 6-phthalazinyl, 7-phthalazinyl, 8-phthalazinyl), quinazolinyl (Eg, 2-quinazolinyl, 4-quinazolinyl, 5-quinazolinyl, 6-quinazolinyl, 7-quinazolinyl, 8-quinazolinyl), quinoxalinyl (eg, 2-quinoxalinyl, 3-quinoxalinyl, 5-quinoxalinyl, 6-quinoxalinyl, 7- Quinoxalinyl, 8- Noxalinyl), pyrazolo [1,5-a] pyridyl (eg, pyrazolo [1,5-a] pyridin-2-yl, pyrazolo [1,5-a] pyridin-3-yl, pyrazolo [1,5-a] ] Pyridin-4-yl, pyrazolo [1,5-a] pyridin-5-yl, pyrazolo [1,5-a] pyridin-6-yl, pyrazolo [1,5-a] pyridin-7-yl) Imidazo [1,2-a] pyridyl (eg, imidazo [1,2-a] pyridin-2-yl, imidazo [1,2-a] pyridin-3-yl, imidazo [1,2-a] pyridine- 5-yl, imidazo [1,2-a] pyridin-6-yl, imidazo [1,2-a] pyridin-7-yl, imidazo [1,2-a] pyridin-8-yl) and the like. .

Hereinafter, the fullerene derivative of the present invention and the n-type semiconductor material containing the fullerene derivative will be specifically described.

Fullerene derivative The fullerene derivative of the present invention is a fullerene derivative represented by the following formula (1).

Formula (1):

[Where:
X ^1a is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group optionally having one or more substituents, an alkoxy group optionally having one or more substituents, or cyano Represents a group,
X ^1b represents a chlorine atom, a bromine atom, an iodine atom, an alkyl group optionally having one or more substituents, an alkoxy group optionally having one or more substituents, or a cyano group. ,
R ² represents an aryl group which may have one or more substituents, or a heteroaryl group which may have one or more substituents;
R ³ represents a hydrogen atom or an organic group, and ring A represents a fullerene ring. ]

X ^1a is preferably a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, a methyl group, a methoxy group, or a cyano group.

X ^1a is more preferably a chlorine atom, a bromine atom, an iodine atom, a methyl group, a methoxy group, or a cyano group.

X ^1a is more preferably a chlorine atom, a methyl group, a methoxy group, or a cyano group.

X ^1b is preferably a chlorine atom, a bromine atom, an iodine atom, a methyl group, a methoxy group, or a cyano group.

X ^1b is more preferably a chlorine atom, a bromine atom, a methyl group, a methoxy group, or a cyano group.

X ^1b is more preferably a chlorine atom, a methyl group, a methoxy group, or a cyano group.

X ^1a and X ^1b are preferably the same or different and are a chlorine atom, a bromine atom, an iodine atom, a methyl group, a methoxy group, or a cyano group.

X ^1a and X ^1b are more preferably the same or different and are a chlorine atom, a methyl group, a methoxy group, or a cyano group.

Preferred X ^1a and preferred X ^1b may each be an electron-withdrawing group or an electron-donating group.

The fullerene derivative of the present invention can have excellent properties as an n-type semiconductor material, particularly when X ^1a and X ^1b are such groups.
Specifically, for example, when used for an n-type semiconductor for a photoelectric conversion element such as an organic thin film solar cell, a high voltage can be applied.

Examples of the substituent in the “aryl group optionally having one or more substituents” represented by R ² are as follows:
(a) a fluorine atom,
(b) an alkyl group optionally substituted by one or more fluorine atoms,
(c) an alkoxy group optionally substituted by one or more fluorine atoms,
(d) an ester group, and
(e) Including a cyano group.

The number of the substituents is, for example, 0 (unsubstituted), 1, 2, 3, 4, or 5.

Examples of the substituent in the “heteroaryl group optionally having one or more substituents” represented by R ² are as follows:
(a) a fluorine atom,
(b) an alkyl group optionally substituted by one or more fluorine atoms,
(c) an alkoxy group optionally substituted by one or more fluorine atoms,
(d) an ester group, and
(e) Including a cyano group.

R ² is preferably
(a) a fluorine atom,
(b) an alkyl group optionally substituted by one or more fluorine atoms,
(c) an alkoxy group optionally substituted by one or more fluorine atoms,
(d) an ester group, and
(e) optionally substituted with one or more substituents selected from the group consisting of cyano groups,
An aryl group (preferably a phenyl group).

When R ² is a phenyl group having one or more substituents, the position of the substituent can be, for example, an ortho position, a meta position, or a para position.

R ² is preferably a phenyl group which may have one or two substituents at the ortho position.

R ³ is preferably
Hydrogen atom,
An alkyl group optionally substituted with one or more substituents,
An alkenyl group optionally substituted by one or more substituents,
An alkynyl group optionally substituted by one or more substituents,
An aryl group optionally substituted with one or more substituents,
It is an ether group which may be substituted with one or more substituents, or an ester group which may be substituted with one or more substituents.

As R ³ ,
"Alkyl group optionally substituted with one or more substituents",
"Alkenyl group optionally substituted with one or more substituents",
"Alkynyl group optionally substituted with one or more substituents",
"Aryl group optionally substituted with one or more substituents",
“An ether group which may be substituted with one or more substituents” and “an ester group which may be substituted with one or more substituents”
Examples of the substituent in each “substituent” in are a fluorine atom, an alkyl group optionally substituted with one or more fluorine atoms, an alkoxy group optionally substituted with one or more fluorine atoms, and an ester group And a cyano group. The number of the substituents may be 1 or more and not more than the maximum number that can be substituted, and is preferably 1 to 4, 1 to 3, 1 to 2, or 1, for example.

R ³ is more preferably
Hydrogen atom,
An alkyl group having 2 to 18 carbon atoms (preferably 3 to 12, more preferably 4 to 10, more preferably 5 to 10, and still more preferably 5 to 8),
One or more substituents selected from a fluorine atom, an alkyl group optionally substituted with one or more fluorine atoms, an alkoxy group optionally substituted with one or more fluorine atoms, an ester group, and a cyano group An aryl group optionally substituted with (preferably a phenyl group),
An ether group (preferably an alkyl ether group) having 1 to 12 carbon atoms (preferably 1 to 10, more preferably 1 to 8, more preferably 1 to 6), or 2 to 12 carbon atoms (preferably 2 to 10 carbon atoms). More preferably, it is an ester group of 2 to 8, more preferably 2 to 6).

R ³ is more preferably
An alkyl group having 2 to 18 carbon atoms (preferably 3 to 12, more preferably 4 to 10 and even more preferably 5 to 8),
An ether group having 1 to 12 carbon atoms (preferably 1 to 10, more preferably 1 to 8, more preferably 1 to 6), or 2 to 12 carbon atoms (preferably 2 to 10, more preferably 2 to 8 carbon atoms), More preferred is an ester group 2-6).

R ³ is more preferably an alkyl group having 1 to 8 carbon atoms or an ether group having 5 to 6 carbon atoms.

R ³ is particularly preferably a methyl group, a hexyl group, a 2-ethylhexyl group, CH ₃ — (CH ₂ ) ₂ —O—CH ₂ —, or CH ₃ —O— (CH ₂ ) ₂ —O— (CH ₂ ) ₂ —O—CH ₂ —.

In a preferred embodiment of the present invention, R ³ is a hydrogen atom or an alkyl group.
In this correspondence, R ³ is preferably
(1) a hydrogen atom, or
(2) Linear or branched chain having 2 to 18 carbon atoms (preferably 3 to 12, more preferably 4 to 10, still more preferably 5 to 10 and even more preferably 5 to 8) It is an alkyl group.

Ring A is preferably _{a, C 60} fullerene ring, or _{C 70} fullerene ring, more preferably _{C 60} fullerene ring.

Ring A is preferably _{a, C 60} fullerene ring.

Fullerene derivative of the formula (1) is, the fullerene derivative Ring A is _{C 60} fullerene ring _{(hereinafter,} also referred to as _{C 60} fullerene derivatives.), And ring A fullerene derivative is _{C 70} fullerene ring _{(hereinafter, C 70} fullerene It may also be a mixture of a derivative).

The ratio of the content of the C ₆₀ fullerene derivative and the C ₇₀ fullerene derivative in the mixture is, for example, 99.999: 0.001 to 0.001: 99.999, 99.99: 0.01 to molar ratio. 0.01: 99.99, 99.9: 0.1 to 0.1: 99.9, 99: 1 to 1:99, 95: 5 to 5:95, 90:10 to 10:90, or 80 : 20 to 20:80.
The ratio of the content of the C ₆₀ fullerene derivative and the C ₇₀ fullerene derivative is preferably 80:20 to 50:50, more preferably 80:20 to 60:40.
The content of the C ₆₀ fullerene derivative in the mixture is, for example, 0.001 to 99.999 mass%, 0.01 to 99.99 mass%, 0.1 to 99.9 mass%, 1 to 99 mass%. It can be 5 to 95% by weight, 10 to 90% by weight, or 20 to 80% by weight.
The content of the C ₆₀ fullerene derivative can be preferably 50 to 80% by mass, and more preferably 60 to 80% by mass.
The content of the C ₇₀ fullerene derivative in the mixture is, for example, 0.001 to 99.999% by mass, 0.01 to 99.99% by mass, 0.1 to 99.9% by mass, 1 to 99% by mass. It can be 5 to 95% by weight, 10 to 90% by weight, or 20 to 80% by weight.
The content of the C ₇₀ fullerene derivative can be preferably 20 to 50% by mass, and more preferably 20 to 40% by mass.
The mixture, C ₆₀ fullerene derivatives, and may be substantially consisting of C ₇₀ fullerene derivatives.
The mixture _can consist of _{C 60} fullerene derivatives, and _{C 70} fullerene derivatives.
The mixture can be a mixture of C ₆₀ fullerene derivatives, and C ₇₀ fullerene derivatives.

In the present specification, C ₆₀ fullerene (ring) is represented by the following structural formula as often performed in the technical field:

It may be expressed as

Therefore, when Ring A is a C ₆₀ fullerene ring, the fullerene derivative of the formula (1) have the general formula:

Can be expressed as

In a preferred embodiment of the present invention,
X ^1a is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, a methyl group, a methoxy group, or a cyano group,
X ^1b is a chlorine atom, a bromine atom, an iodine atom, a methyl group, a methoxy group, or a cyano group,
R ² is an aryl group that may have one or more substituents, or a heteroaryl group that may have one or more substituents;
R ³ is a hydrogen atom or an alkyl group, and ring A is a C ₆₀ or C ₇₀ fullerene ring (preferably a C ₆₀ fullerene ring).

In another preferred embodiment of the present invention,
X ^1a is a chlorine atom, a methyl group, a methoxy group, or a cyano group,
X ^1b is a chlorine atom, a methyl group, a methoxy group, or a cyano group,
R ² is a phenyl group;
R ³ is a hydrogen atom or an alkyl group having 5 to 10 carbon atoms, and ring A is a C ₆₀ or C ₇₀ fullerene ring (preferably a C ₆₀ fullerene ring).

In yet another preferred embodiment of the present invention,
X ^1a is a linear or branched alkyl group having 2 to 8 carbon atoms,
X ^1b is a linear or branched alkyl group having 2 to 8 carbon atoms,
R ² is an aryl group that may have one or more substituents, or a heteroaryl group that may have one or more substituents;
R ³ is a hydrogen atom or an alkyl group having 5 to 10 carbon atoms, and ring A is a C ₆₀ or C ₇₀ fullerene ring (preferably a C ₆₀ fullerene ring).

Since the fullerene derivative of the present invention exhibits sufficient solubility in various organic solvents, it is easy to form a thin film by a coating method.
Furthermore, the fullerene derivative of the present invention can easily form a bulk heterojunction structure when an organic power generation layer is prepared using an organic p-type semiconductor material as an n-type semiconductor material.
The fullerene derivative of the present invention has a high conversion efficiency and enables a high voltage output.

The fullerene derivative of the present invention preferably has a LUMO level value of −3.65 eV or more.
The LUMO level can be measured by the method described in Karakawa et al., Journal of Materials Chemistry A, 2014, Vol. 2, page 20889.

Production method of fullerene derivative The fullerene derivative of the present invention can be produced by a known production method of a fullerene derivative or a method analogous thereto.
Specifically, the fullerene derivative of the present invention can be synthesized, for example, according to the method of the following scheme. The symbols in the scheme have the same meanings as described above, and as will be apparent to those skilled in the art, the symbols in formula (a) and formula (b) correspond to the symbols in formula (1).

<Process A>
In step A, a glycine derivative (compound (b)) is reacted with an aldehyde compound (compound (a)) and a fullerene (compound (c)) to produce a fullerene derivative represented by formula (1) (compound (1)). Get.

The amount ratio of the aldehyde compound (compound (a)), the glycine derivative (compound (b)) and the fullerene (compound (c)) is arbitrary, but is generally fullerene (compound (c)) 1 from the viewpoint of increasing the yield. The aldehyde compound (compound (a)) and glycine derivative (compound (b)) are each used in an amount of 0.1 to 10 mol, preferably 0.5 to 2 mol, relative to mol.

The reaction is performed without a solvent or in a solvent.
Examples of the solvent include carbon disulfide, chloroform, dichloroethane, toluene, xylene, chlorobenzene, dichlorobenzene and the like. Of these, chloroform, toluene, xylene, chlorobenzene and the like are preferable. These solvents may be mixed and used at an appropriate ratio.

The reaction temperature is usually in the range of room temperature to about 150 ° C, preferably in the range of about 80 to about 120 ° C. Here, the room temperature can be preferably in the range of 15 to 30 ° C.

The reaction time is usually in the range of about 1 hour to about 4 days, preferably in the range of about 10 to about 48 hours.

The obtained compound (1) can be purified by a conventional purification method as necessary.
For example, the obtained compound (1) is purified by silica gel column chromatography (the developing solvent is preferably hexane-chloroform, hexane-toluene, or hexane-carbon disulfide, for example), and then further HPLC ( (Preparative GPC) (As the developing solvent, for example, chloroform or toluene is preferable).

The aldehyde compound (compound (a)), glycine derivative (compound (b)), and fullerene (compound (c)) used in Step A are known compounds, respectively, and are known methods or similar methods. They are synthesized by methods or are commercially available.

Specifically, the aldehyde compound (compound (a)) can be synthesized, for example, by the following method (a1), (a2) or (a3).
In the reaction formulas showing these methods, R ² has the same meaning as R ² in the formula (1) and corresponds to R ² of the target fullerene derivative.

Method (a1): Oxidation of alcohol represented by R ² —CH ₂ OH For the oxidation in this method, for example, (i) a method using chromic acid, manganese oxide or the like as an oxidizing agent, (ii) For example, swern oxidation using dimethyl sulfoxide as an oxidizing agent, or (iii) oxidation using hydrogen peroxide, oxygen, air or the like in the presence of a catalyst can be applied.

Method (a2): Reduction of Carboxylic Acid Represented by R ² —COOH, Its Acid Halide, Its Ester, Its Acid Amide, etc. For the reduction in this method, a known method such as (i) a metal as a reducing agent A method using a hydride, (ii) a method of reducing hydrogen in the presence of a catalyst, or (iii) a method using hydrazine as a reducing agent can be applied.

Method (a3): Carbonylation of a halide represented by R ² —X (X represents halogen) In this method, for example, n-BuLi is used to form an anion from the halide. And a method of introducing a carbonyl group can be applied thereto. As the carbonyl group-introducing reagent here, amide compounds such as N, N-dimethylformamide (DMF); or N-formyl derivatives of piperidine, morpholine, piperazine or pyrrolidine are used.

Specifically, the glycine derivative (compound (b)) can be synthesized, for example, by the following method (b1), (b2) or (b3).
In the following synthetic scheme, R ¹ represents a partial structure in formula (1):

Represents.

Method (b1): Reaction of aniline derivative and halogenated acetic acid

The reaction can be carried out using water, methanol, ethanol, or a mixture thereof as a solvent, and if necessary, in the presence of a base.

Method (b2): Reaction of aniline derivative and halogenated acetic acid ester, and hydrolysis of glycine derivative ester obtained by the reaction

In this method, the reaction between the aniline derivative and the halogenated acetate can be performed in the presence of a base such as acetate, carbonate, phosphate, or tertiary amine using, for example, methanol or ethanol as a solvent. . The hydrolysis of the glycine derivative ester can be usually performed at room temperature in the presence of a water-soluble alkali.

Method (b3): Reaction of aromatic halide with glycine

This reaction can be performed, for example, using monovalent copper as a catalyst and in the presence of a bulky amine, amino acid, amino alcohol or the like. As the reaction solvent, water, methanol, ethanol, or a mixture thereof is preferably used. The reaction temperature is about room temperature to 100 ° C.

Since the fullerene derivative of the present invention can be synthesized by a simple method using a glycine derivative and an aldehyde compound as raw materials in this way, it can be produced at low cost.

Use of fullerene derivative The fullerene derivative of the present invention can be suitably used as an n-type semiconductor material, particularly an n-type semiconductor material for a photoelectric conversion element such as an organic thin film solar cell.
The fullerene derivative of the present invention can also be used as an electron transport material for transistors, perovskite solar cells, and the like.

When the fullerene derivative of the present invention is used as an n-type semiconductor material, it is usually used in combination with an organic p-type semiconductor material (organic p-type semiconductor compound).
Examples of the organic p-type semiconductor material include poly-3-hexylthiophene (P3HT), poly-p-phenylene vinylene, poly-alkoxy-p-phenylene vinylene, poly-9,9-dialkylfluorene, poly-p- Examples include phenylene vinylene.
Since these are many examples of studies as solar cells and are easily available, devices with stable performance can be easily obtained.
In order to obtain higher conversion efficiency, a donor-acceptor type π-conjugated polymer that enables absorption of long-wavelength light by narrowing the band gap (low band gap) is effective.
These donor-acceptor type π-conjugated polymers have a structure in which donor units and acceptor units are arranged alternately.
Examples of the donor unit used here include benzodithiophene, dithienosilol, and N-alkylcarbazole, and examples of the acceptor unit include benzothiadiazole, thienothiophene, and thiophenepyrroldione.
Specifically, these units are combined to produce poly (thieno [3,4-b] thiophene-co-benzo [1,2-b: 4,5-b ′] thiophene) (PTBx series), poly ( Polymer compounds such as dithieno [1,2-b: 4,5-b ′] [3,2-b: 2 ′, 3′-d] silole-alt- (2,1,3-benzothiadiazole) s Is exemplified.
Of these, preferred are:
(1) Poly ({4,8-bis [(2-ethylhexyl) oxy] benzo [1,2-b: 4,5-b ′] dithiophene-2,6-diyl} {3-fluoro-2- [ (2-ethylhexyl) carbonyl] thieno [3,4-b] thiophenediyl}) (PTB7, structural formula shown below),
(2) Poly [(4,8-di (2-ethylhexyloxy) benzo [1,2-b: 4,5-b ′] dithiophene) -2,6-diyl-alt-((5-octylthieno [3 , 4-c] pyrrole-4,6-dione) -1,3-diyl) (PBDTTPD, structural formula is shown below),
(3) Poly [(4,4′-bis (2-ethylhexyl) dithieno [3,2-b: 2 ′, 3′-d] silole) -2,6-diyl-alt- (2,1,3 -Benzothiadiazole) -4,7-diyl] (PSBTBT, structural formula is shown below),
(4) Poly [N-9 ″ -heptadecanyl-2,7-carbazole-alt-5,5- (4 ′, 7′-di-2-thienyl-2 ′, 1 ′, 3′-benzothiadiazole) (PCDTBT, the structural formula is shown below), and (5) poly [1- (6- {4,8-bis [(2-ethylhexyl) oxy] -6-methylbenzo [1,2-b: 4, 5-b ′] dithiophen-2-yl} {3-fluoro-4-methylthieno [3,4-b] thiophen-2-yl} -1-octanone) (PBDTTTT-CF, structural formula is shown below)
Etc. are exemplified.
Among these, more preferred examples include PTB compounds having a fluorine atom at the 3-position of thieno [3,4-b] thiophene as the acceptor unit, and particularly preferred examples include PBDTTTT-CF and PTB7. Is done.

(In the formula, n represents the number of repetitions.)

(In the formula, n represents the number of repetitions.)

(In the formula, n represents the number of repetitions.)

(In the formula, n represents the number of repetitions.)

(In the formula, n represents the number of repetitions.)

An organic power generation layer prepared using the fullerene derivative of the present invention as an n-type semiconductor material in combination with an organic p-type semiconductor material can exhibit high conversion efficiency.
Since the fullerene derivative of the present invention exhibits good solubility in various organic solvents, when it is used as an n-type semiconductor material, an organic power generation layer can be prepared by a coating method, and a large area organic The power generation layer can be easily prepared.

The fullerene derivative of the present invention is a compound having good compatibility with an organic p-type semiconductor material and having appropriate self-aggregation properties. Therefore, an organic power generation layer having a bulk junction structure is easily formed using the fullerene derivative as an n-type semiconductor material (organic n-type semiconductor material). By using this organic power generation layer, an organic thin film solar cell or a photosensor having high conversion efficiency can be obtained.

Therefore, by using the fullerene derivative of the present invention as an n-type semiconductor material, an organic thin film solar cell having excellent performance can be produced at low cost.
Another application of the organic power generation layer containing (or consisting of) the n-type semiconductor material of the present invention is an image sensor for a digital camera. In response to the demand for higher functionality (higher definition) of digital cameras, problems with reduced sensitivity have been pointed out for image sensors made of existing silicon semiconductors. In contrast, an image sensor made of an organic material with high photosensitivity is expected to enable high sensitivity and high definition. A material for constructing the light receiving part of such a sensor is required to absorb light with high sensitivity and to generate an electric signal with high efficiency therefrom. In response to such a requirement, the organic power generation layer containing (or consisting of) the n-type semiconductor material of the present invention can efficiently convert visible light into electrical energy. High function can be expressed.

n-type Semiconductor Material The n-type semiconductor material of the present invention comprises the fullerene derivative of the present invention.

Organic power generation layer The organic power generation layer of the present invention contains the fullerene derivative of the present invention as an n-type semiconductor material (n-type semiconductor compound).
The organic power generation layer of the present invention can be a light conversion layer (photoelectric conversion layer).
The organic power generation layer of the present invention usually contains the organic p-type semiconductor material (organic p-type semiconductor compound) in combination with the fullerene derivative of the present invention, that is, the n-type semiconductor material of the present invention.
The organic power generation layer of the present invention is usually composed of the n-type semiconductor material of the present invention and the organic p-type semiconductor.
In the organic power generation layer of the present invention, preferably, the n-type semiconductor material of the present invention and the organic p-type semiconductor material form a bulk heterojunction structure.

The organic power generation layer of the present invention is prepared, for example, by dissolving the n-type semiconductor material of the present invention and the organic p-type semiconductor material in an organic solvent, and from the obtained solution, a spin coating method, a casting method, a dipping method, an inkjet method, It can prepare by forming a thin film on a board | substrate by employ | adopting well-known thin film formation methods, such as a doctor blade method and a screen printing method.

In the thin film formation of the organic power generation layer, the fullerene derivative of the present invention has good compatibility with an organic p-type semiconductor material (preferably P3HT or PTB7) and has appropriate self-aggregation. An organic power generation layer containing the fullerene derivative of the present invention as an n-type semiconductor material and an organic p-type semiconductor material and having a bulk heterojunction structure can be easily obtained.

Organic Thin Film Solar Cell The organic thin film solar cell of the present invention includes the organic power generation layer of the present invention described above.
For this reason, the organic thin film solar cell of this invention has high conversion efficiency.
The structure of the organic thin film solar cell is not particularly limited, and can be the same structure as a known organic thin film solar cell, and the organic thin film solar cell of the present invention is manufactured according to a known method for manufacturing an organic thin film solar cell. it can.

As an example of the organic thin film solar cell containing the fullerene derivative, for example, a transparent electrode (cathode), a cathode side charge transport layer, an organic power generation layer, an anode side charge transport layer, and a counter electrode (anode) are sequentially laminated on a substrate. Examples of the solar cell having the above structure can be given. The organic power generation layer is preferably a semiconductor thin film layer (that is, a photoelectric conversion layer) containing an organic p-type semiconductor material and the fullerene derivative of the present invention as an n-type semiconductor material and having a bulk heterojunction structure.
In the solar cell having such a structure, a known material can be appropriately used as a material for each layer other than the organic power generation layer. Specifically, examples of the material for the electrode include aluminum, gold, silver, copper, and indium oxide (ITO). As the material for the charge transport layer, for example, PFN (poly [9,9-bis (3 ′-(N, N-dimethylamino) propyl-2,7-fluorene) -alt-2,7- (9,9 -Dioctylfluorene)]), MoO ₃ (molybdenum oxide) and the like.

Photosensor As described above, the photoelectric conversion layer obtained in the present invention effectively functions as a light receiving portion for an image sensor in a high-functional product of a digital camera. Compared to conventional photosensors using silicon photodiodes, white stripes do not occur in bright places, and clear images can be obtained even in dark places. For this reason, it is possible to obtain a higher quality image than a conventional camera. The optical sensor is constructed from a silicon substrate, an electrode, a light receiving part including a photoelectric conversion layer, a color filter, and a microlens. The light receiving portion may have a thickness of about several hundreds of nanometers, and may be configured to be a fraction of the thickness of a conventional silicon photodiode.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

The symbols and abbreviations in the examples are used as follows. In addition, in the present specification, symbols and abbreviations that are normally used in the technical field to which the present invention belongs can be used.

Synthesis example 1

A chlorobenzene solution (150 mL) of N- (2,6-dimethylphenyl) -glycine (90 mg, 0.5 mmol), benzaldehyde (1 mL), and fullerene (360 mg, 0.5 mmol) was heated to reflux for 48 hours.
The reaction product solution is concentrated under reduced pressure, and the reaction product is subjected to column chromatography (SiO2, hexane-toluene = 20: 1 to 10: 1).
Further purification by HPLC (Buckyprep: toluene) gave 120 mg (25.4%) of the desired product.
(Purity: 99% or more)

¹ H-NMR (CDCl ₃ ) δ: 2.57 (3H, s), 2.91 (3H, s), 5.00 (1H, d, J = 9.9 Hz), 5.12 (1H, d, J = 9.9 Hz), 6.41 ( 1H, s), 6.82 (1H, d, J = 7.3 Hz), 6.97 (1H, t, J = 7.3 Hz), 7.01-7.25 (4H, m), 7.50 (2H, bs).
MS (FAB) m / z 944 (M ⁺ ). HRMS calcd for C ₇₆ H ₁₇ N 943.13610; found 943.1340.

Synthesis example 2

A dichlorobenzene solution (300 mL) of N- (2,6-dichlorophenyl) -2-phenylglycine (160 mg, 0.5 mmol), heptanal (1 mL), and fullerene (360 mg, 0.5 mmol) was heated to reflux for 2 weeks.
The reaction product solution was concentrated under reduced pressure, and the reaction product was purified by column chromatography (SiO2, hexane-toluene = 100: 1 to 20: 1) to obtain 42.0 mg (7.9%) of the desired product.

¹ H-NMR (CDCl ₃ ) δ: 0.81 (3H, t, J = 7.3 Hz), 0.80-1.60 (8H, m), 2.24-2.40 (1H, m), 2.60-2.80 (1H, m), 5.36 (1H, dd, J = 7.3, 4.6 Hz), 6.75 (1H, s), 7.00-7.32 (5H, m), 7.50 (1H, d, J = 8.0 Hz), 7.63 (1H, bd, J = 7.3 Hz), 7.79 (1H, bd, J = 6.9 Hz).
MS (FAB) m / z 1067 (M ⁺ ). HRMS calcd for C ₈₀ H ₂₃ Cl ₂ N 1067.1208; found 1067.1202.

Synthesis example 3

A dichlorobenzene solution (200 mL) of N- (2,6-methoxyphenyl) -2-phenylglycine (150 mg, 0.52 mmol), heptanal (2 mL), and fullerene (720 mg, 0.5 mmol) was heated to reflux for 4 days.
The reaction product was concentrated under reduced pressure, and the reaction product was purified by column chromatography (SiO2, hexane-toluene = 20: 1 to 5: 1) to obtain 182 mg (33%: amino acid equivalent) of the desired product.

¹ H-NMR (CDCl ₃ ) δ: 0.80 (3H, t, J = 7.3 Hz), 1.02-1.64 (8H, m), 2.16-2.28 (1H, m), 2.52-2.64 (1H, m), 3.98 (3H, s), 4.04 (3H, s), 5.36 (1H, dd, J = 6.9, 4.6 Hz), 6.50 (1H, d, J = 8.2 Hz), 6.55 (1H, s), 6.63 (1H, d, J = 8.2 Hz), 7.05-7.30 (4H, m), 7.50 (1H, bs), 8.05 (1H, bs).
MS (FAB) m / z 1060 (M ⁺ ). HRMS calcd for C ₈₂ H ₃₀ NO ₂ (M + 1) 1060.2277; found 1060.2281.

Synthesis example 4

A chlorobenzene solution (300 mL) of N- (2-cyanophenyl) -2-phenylglycine (150 mg, 0.60 mmol), heptanal (1 mL), and fullerene (588 mg, 0.82 mmol) was heated to reflux for 8 days.
The reaction product solution was concentrated under reduced pressure, and the reaction product was purified by column chromatography (SiO2, hexane-toluene = 20: 1 to 2: 1) to obtain 210 mg (33.6%: converted to amino acid) of the desired product.

¹ H-NMR (CDCl ₃ ) δ: 0.81 (3H, t, J = 7.3 Hz), 1.10-1.70 (8H, m), 2.16-2.28 (1H, m), 2.80-2.92 (1H, m), 5.90 -6.05 (1H, m), 6.41 (1H, s), 7.10-7.40 (5H, m), 7.44 (1H, t, J = 7.8 Hz), 7.60 (1H, bs), 7.68 (1H, bs), 7.79 (1H, d, J = 7.3 Hz).
MS (FAB) m / z 1025 (M ⁺ ). HRMS calcd for C ₈₁ H ₂₅ N ₂ (M + 1) 1025.2018; found 1025.2014.

Using each fullerene derivative obtained in the above synthesis example and reference compounds 1, 2 and 3 described later as n-type semiconductor materials, solar cells were prepared by the method described later and their functions were evaluated.
PTB7 is used as the organic p-type semiconductor material, and PFN (poly [9,9-bis (3 ′-(N, N-dimethylamino) propyl-2,7-fluorene) -alt-2, 7- (9,9-dioctylfluorene)]) and MoO ₃ (molybdenum oxide), and ITO (indium tin oxide) (cathode) and aluminum (anode) were used as electrodes, respectively.

(1) Production of test solar cell A test solar cell was produced according to the following procedure.
1) Pretreatment of substrate The ITO patterned glass plate was put in a plasma cleaning machine, and the substrate surface was cleaned for 10 minutes by plasma generated while oxygen gas was introduced.
2) Preparation of PFN thin film (cathode-side charge transport layer) Using an ABLE / ASS-301 type spin coat method film forming apparatus, a PFN methanol solution (2% w / v) was used for the pre-treated ITO. A PFN thin film was formed on a glass plate. The film thickness of the formed PFN thin film was about 10 nm.
3) Preparation of organic semiconductor film (organic power generation layer) Using a MIKASA / MS-100 type spin coat film forming apparatus in the glove box, the substrate was previously dissolved in chlorobenzene with PTB7, fullerene derivative, and diiodooctane ( A solution containing 3% v / v with respect to chlorobenzene was spin coated (1000 rpm, 2 minutes) on the PFN thin film to form an organic semiconductor thin film (organic power generation layer) having a thickness of about 90 to 110 nm, A laminate was obtained.
4) Vacuum deposition of anode side charge transport layer and metal electrode Using a small high vacuum deposition apparatus, the laminate prepared above was placed on the mask in the high vacuum deposition apparatus, and MoO ₃ layer as the anode side charge transport layer (10 nm) and an aluminum layer (80 nm) as a metal electrode were sequentially deposited.

(2) Current measurement by simulated sunlight irradiation For current measurement by simulated sunlight irradiation, a source meter, current voltage measurement software, and simulated sunlight irradiation apparatus were used.
Each test solar cell prepared in (1) above was irradiated with 100 mW pseudo-sunlight, the generated current and voltage were measured, and the energy conversion efficiency was calculated according to the following equation.
The measurement results of the open circuit voltage are shown in Table 1. The conversion efficiency is a value obtained by the following formula.
Conversion efficiency η (%) = FF (V _oc × J _sc / P _in ) × 100
FF: fill factor, V _oc : open circuit voltage, J _sc : short circuit current, P _in : incident light intensity (density)
The results are shown in Table 1.

Claims

Formula (1):

[Where:
X 1a is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group optionally having one or more substituents, an alkoxy group optionally having one or more substituents, or cyano Represents a group,
X 1b represents a chlorine atom, a bromine atom, an iodine atom, an alkyl group optionally having one or more substituents, an alkoxy group optionally having one or more substituents, or a cyano group. ,
R 2 represents an aryl group which may have one or more substituents, or a heteroaryl group which may have one or more substituents;
R 3 represents a hydrogen atom or an organic group, and ring A represents a fullerene ring. ]
A fullerene derivative represented by:
The fullerene derivative according to claim 1, wherein X 1a is a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, a methyl group, a methoxy group, or a cyano group.
The fullerene derivative according to claim 2, wherein X 1a is a chlorine atom, a bromine atom, an iodine atom, a methyl group, a methoxy group, or a cyano group.
The fullerene derivative according to any one of claims 1 to 3, wherein X 1b is a chlorine atom, a bromine atom, an iodine atom, a methyl group, a methoxy group, or a cyano group.
The fullerene derivative according to any one of claims 1 to 4, wherein R 2 is an aryl group which may have one or more substituents.
6. The fullerene derivative according to claim 5, wherein R 2 is a phenyl group which may have one or two substituents at the ortho position.
The fullerene derivative according to any one of claims 1 to 6, wherein R 3 is a hydrogen atom or an alkyl group.
The fullerene derivative according to any one of claims 1 to 7, wherein the ring A is a C 60 fullerene ring.
An n-type semiconductor material containing the fullerene derivative according to any one of claims 1 to 8.
The n-type semiconductor material according to claim 9, which is used for an organic thin film solar cell.
An organic power generation layer containing the n-type semiconductor material according to claim 10.
A photoelectric conversion element provided with the organic electric power generation layer of Claim 11.
The photoelectric conversion element according to claim 12, which is an organic thin film solar cell.