JP7700489B2 - Organic Semiconductor Ink - Google Patents

Description

The present invention primarily relates to organic semiconductor inks.

Many of the organic semiconductor inks used in forming bulk heterojunction (BHJ) type photoelectric conversion layers in organic solar cells, organic photodetectors, etc. use halogenated solvents such as chloroform or chlorobenzene, or non-halogenated aromatic solvents such as toluene or xylene, which are designated as non-medicinal hazardous substances, and therefore have issues from the perspectives of ensuring worker safety and environmental impact. For this reason, various non-halogenated and non-hazardous solvents have been investigated for use in organic semiconductor inks.
Patent Documents 1 and 2 disclose examples of using a non-hazardous and non-halogenated solvent such as pseudocumene together with o-xylene as a solvent for an organic semiconductor ink for a photoelectric conversion layer. Non-Patent Document 1 discloses that good photoelectric conversion characteristics can be obtained by using ethylbenzene as the main solvent for an organic semiconductor ink for a photoelectric conversion layer containing PTB7-Th. Non-Patent Document 2 discloses that good photoelectric conversion characteristics can be obtained by using terpyrenone as the main solvent for an organic semiconductor ink for a photoelectric conversion layer containing PTB7-Th.

Patent No. 6718412 Patent No. 6697833

J. Mater. Chem. A, 2018, 6, 23840-23855 J. Phys. Chem. A, 2019, 123, 4, 2105-2113

It is extremely difficult to infer an appropriate solvent for an ink containing an organic semiconductor composition for any photoelectric conversion layer from the above literature. This is because not only does the solubility in various solvents differ depending on the organic semiconductor and its molecular weight, but also the formation of a BHJ-type photoelectric conversion layer with high photoelectric conversion efficiency requires the formation of a nanostructure in which p-type and n-type organic semiconductors are co-continuously intertwined during coating and drying, and many factors such as the difference in solubility between p-type and n-type organic semiconductors and the drying speed are involved in the formation of this structure in addition to solubility. In other words, in order to achieve good photoelectric characteristics, it is important not only to select a semiconductor compound but also to select a solvent suitable for the semiconductor compound. Although the combination of semiconductor compounds and solvents has been widely studied, there is no limit to the number of combinations of the components, and there is ample room for study, especially for combinations when a non-poisonous and non-halogenated solvent is used as the solvent.
Therefore, an object of the present invention is to provide an organic semiconductor ink that can realize good photoelectric characteristics while using a non-hazardous and non-halogen solvent.

As a result of intensive research aimed at solving the above problems, the inventors have found that by using, as the semiconductor compounds, a p-type semiconductor compound that is a copolymer having a specific structure and an n-type semiconductor compound having specific properties, it is possible to provide an organic semiconductor ink that can achieve good photoelectric properties while using a non-hazardous, non-halogenated solvent, and have thus completed the present invention.

（式（１Ａ）、式（１Ｂ）及び式（１Ｃ）中、Ａ^１及びＡ^２は各々独立して、周期表第１６族から選ばれる原子を表し、Ｑは周期表第１４族から選ばれる原子を表し、Ｒ^１は置換基を有していてもよい直鎖アルキル基を表し、Ｒ^２は置換基を有していてもよい分岐アルキル基、置換基を有していてもよいシクロアルキル基、置換基を有していてもよい芳香族炭化水素基又は置換基を有していてもよい複素環基を表す。Ｒ^３及びＲ^４は各々独立して、ヘテロ原子を有していてもよい炭化水素基を表す。）
［２］ 前記アニソール誘導体が、２－メチルアニソール、３－メチルアニソール、４－メチルアニソール、２－エチルアニソール、３－エチルアニソール、４－エチルアニソール、２，３－ジメチルアニソール、２，４－ジメチルアニソール、２，５－ジメチルアニソール、２，６－ジメチルアニソール、３，４－ジメチルアニソール、及び３．５－ジメチルアニソールからなる群より選択される、［１］に記載の有機半導体インク。
［３］ 前記アニソール誘導体が、２－メチルアニソールである、［２］に記載の有機半導体インク。
［４］ 芳香族炭化水素またはハロゲン化アルキルをさらに含む、［１］～［３］のいず
れかに記載の有機半導体インク。
［５］ 前記芳香族炭化水素またはハロゲン化アルキルの融点が２５℃以下である、［４］に記載の有機半導体インク。
［６］ 前記芳香族炭化水素またはハロゲン化アルキルの沸点が前記溶媒の沸点以上である、［４］または［５］に記載の有機半導体インク。
［７］ 前記芳香族炭化水素またはハロゲン化アルキルが、テトラリンまたは１，８－ジヨードオクタンである、［４］～［６］のいずれかに記載の有機半導体インク。 Embodiments of the present invention include, but are not limited to, the following.
[1] A p-type semiconductor compound which is a copolymer including a repeating unit represented by the following formula (1A), a repeating unit represented by the following formula (1B), and a repeating unit represented by the following formula (1C):
an n-type semiconductor compound having an electron affinity of 3.5 eV or more;
a solvent containing an anisole derivative in which a halogen group is not directly bonded to a benzene ring;
1. An organic semiconductor ink comprising:

(In formula (1A), formula (1B), and formula (1C), ^A1 and ^A2 each independently represent an atom selected from Group 16 of the periodic table, Q represents an atom selected from Group 14 of the periodic table, ^R1 represents a linear alkyl group which may have a substituent, and ^R2 represents a branched alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or a heterocyclic group which may have a substituent. ^R3 and ^R4 each independently represent a hydrocarbon group which may have a heteroatom.)
[2] The organic semiconductor ink according to [1], wherein the anisole derivative is selected from the group consisting of 2-methylanisole, 3-methylanisole, 4-methylanisole, 2-ethylanisole, 3-ethylanisole, 4-ethylanisole, 2,3-dimethylanisole, 2,4-dimethylanisole, 2,5-dimethylanisole, 2,6-dimethylanisole, 3,4-dimethylanisole, and 3.5-dimethylanisole.
[3] The organic semiconductor ink according to [2], wherein the anisole derivative is 2-methylanisole.
[4] The organic semiconductor ink according to any one of [1] to [3], further comprising an aromatic hydrocarbon or an alkyl halide.
[5] The organic semiconductor ink according to [4], wherein the aromatic hydrocarbon or alkyl halide has a melting point of 25° C. or lower.
[6] The organic semiconductor ink according to [4] or [5], wherein the boiling point of the aromatic hydrocarbon or alkyl halide is equal to or higher than the boiling point of the solvent.
[7] The organic semiconductor ink according to any one of [4] to [6], wherein the aromatic hydrocarbon or alkyl halide is tetralin or 1,8-diiodooctane.

The present invention provides an organic semiconductor ink that uses a non-hazardous, non-halogenated solvent and yet achieves good photoelectric properties.

1 is a cross-sectional view illustrating a schematic configuration of a photoelectric conversion element according to one embodiment of the present invention.

The present invention will be described in detail below. The following description is an example (representative example) of the present invention, and the present invention is not limited thereto. In addition, the present invention can be modified and carried out as desired without departing from the gist of the present invention.
In this specification, the expression "~" indicates a range including the numbers before and after it.
In addition, when describing two or more objects together, the term "independently" is used to mean that the two or more objects may be the same or different.

1. p-type semiconductor compounds
The copolymer (hereinafter also simply referred to as "copolymer") which is a p-type semiconductor compound in the organic semiconductor ink according to an embodiment of the present invention contains a repeating unit represented by the following formula (1A), a repeating unit represented by (1B), and a repeating unit represented by formula (1C). The copolymer according to this embodiment is suitable for coating and film formation because it is unlikely to gel when dissolved. Furthermore, the copolymer according to this embodiment is preferable because it has a light absorption wavelength range at a longer wavelength, has high light absorbency, and has high mobility. Furthermore, the copolymer according to this embodiment is preferable because it is easy to obtain a high molecular weight copolymer.

In formula (1A) and formula (1B), A ¹ and A ² each independently represent an atom selected from group 16 of the periodic table. Specific examples of ^{A 1} and A ² include an oxygen atom, a sulfur atom, a selenium atom, and a tellurium atom. Among them, from the viewpoint of ease of synthesis, an oxygen atom, a sulfur atom, or a selenium atom is preferable, a sulfur atom or an oxygen atom is more preferable, and a sulfur atom is particularly preferable. ^{A 1} and A ² may be the same or different, and are preferably the same.

In formula (1C), Q represents an atom selected from Group 14 elements of the periodic table. Specific examples of atoms selected from Group 14 elements of the periodic table include carbon atom, silicon atom, germanium atom, tin atom, and lead atom. Q is preferably a carbon atom, silicon atom, germanium atom, or tin atom, more preferably a carbon atom, silicon atom, or germanium atom. More preferably, it is a silicon atom or germanium atom. Since silicon atom and germanium atom have a larger atomic radius than carbon atom, steric hindrance by the substituents R ³ and R ⁴ that inhibit π-π stacking can be reduced. This is preferable in that intermolecular interactions between copolymers can be appropriately maintained.

In formula (1A), ^R1 is a linear alkyl group which may have a substituent. This is preferable from the viewpoint of appropriately strengthening the interaction between the copolymers.
The number of carbon atoms in the linear alkyl group is usually 1 or more, preferably 3 or more, more preferably 4 or more, and is usually 30 or less, preferably 20 or less, more preferably 16 or less, and further preferably 12 or less. It is preferable that the number of carbon atoms in the linear alkyl group is within the above range from the viewpoint of improving solubility.

Examples of the straight-chain alkyl group include a methyl group, an n-propyl group, an n-butyl group, an n-hexyl group, an n-octyl group, an n-decyl group, an n-dodecyl group, an n-tetradecyl group, an n-hexadecyl group, an n-icosyl group, an n-tetracosyl group, and an n-triacontyl group.
Among these, preferred are n-butyl, n-hexyl, n-octyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-icosyl, n-tetracosyl, and n-triacontyl groups, and more preferred are n-butyl, n-hexyl, n-octyl, n-decyl, and n-dodecyl groups, from the viewpoint of promoting charge transfer by not increasing the intermolecular distance of the copolymer too far while maintaining high solubility of the copolymer.

In formula (1B), ^R2 represents a branched alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or a heterocyclic group which may have a substituent. It is believed that such a combination of ^R1 and ^R2 can suppress a decrease in solubility and gelation that occurs due to regular orientation of polymer main chains, and can improve the storage stability of the ink.
^R2 is preferably a branched alkyl group which may have a substituent or an aromatic hydrocarbon group which may have a substituent, and more preferably a branched alkyl group which may have a substituent.

Examples of branched alkyl groups include branched primary alkyl groups, branched secondary alkyl groups, and branched tertiary alkyl groups. A branched primary alkyl group refers to a branched alkyl group having two hydrogen atoms bonded to a carbon atom having a free valence. A branched secondary alkyl group refers to a branched alkyl group having one hydrogen atom bonded to a carbon atom having a free valence. A branched tertiary alkyl group refers to a branched alkyl group having no hydrogen atoms bonded to a carbon atom having a free valence. Here, free valence refers to one that can form a bond with another free valence, as described in Organic Chemistry and Biochemistry Nomenclature (Vol. 1) (Revised 2nd Edition, Nankodo, published in 1992).

Among these, a branched primary alkyl group is preferred in that it moderately strengthens the intermolecular interaction and improves the mobility, and a branched secondary alkyl group is preferred in that it improves the solubility.
The number of carbon atoms in the branched primary alkyl group is usually 3 or more, preferably 6 or more, more preferably 8 or more, and usually 30 or less, preferably 20 or less, more preferably 16 or less, and even more preferably 12 or less. It is preferable that the number of carbon atoms in the branched primary alkyl group is within the above range from the viewpoint of improving solubility.

Examples of branched primary alkyl groups include 2-ethylhexyl, 2-methylpropyl, 2,2-dimethylpropyl, 2-ethylbutyl, 2,4-dimethylhexyl, 2-methylpentyl, 2,3-dimethylbutyl, 2-hexyldecyl, 2,2-dimethylbutyl, 2-methylheptyl, 2-butyloctyl, 2-propylpentyl, 2-methyloctyl, 2-methyldodecyl, and 2,5-dimethylhexyl groups.

Among these, 2-ethylhexyl, 2,4-dimethylhexyl, 2,6-dimethylheptyl, 2-hexyldecyl, 2-methylheptyl, 2-butyloctyl, 2-propylpentyl, 2-methyloctyl, and 2,5-dimethylhexyl groups are preferred, and 2-ethylhexyl, 2-hexyldecyl, 2-butyloctyl, and 2-hexyloctyl groups are more preferred.

The number of carbon atoms in the branched secondary alkyl group is usually 3 or more, preferably 4 or more, more preferably 5 or more, and usually 30 or less, preferably 20 or less, more preferably 16 or less, and even more preferably 12 or less. Having the number of carbon atoms in the branched secondary alkyl group within the above range is preferable in that solubility can be improved.
Examples of branched secondary alkyl groups include a 1-methylpropyl group, a 1-methylheptyl group, a 1-ethylhexyl group, a 1-methylpentyl group, a 1-methyloctyl group, a 1-ethylbutyl group, a 1-butylheptyl group, a 4-methyl-1-propylhexyl group, a 1,3-dimethylpentyl group, a 1-ethyl-2-methylpentyl group, a 1,2-dimethylpentyl group, a 1-butylhexyl group, a 1,3-dimethyldecyl group, and a 1-propylheptyl group.

Of these, preferred are 1-ethylhexyl, 1-ethyl-2-methylpropyl, 1-butylheptyl, 1-ethyloctyl, 1-propylhexyl, 4-ethyl-1-methyloctyl, 4-methyl-1-propylhexyl, 1-ethyl-2-methylpentyl, 1-butylhexyl, and 1-propylheptyl groups.
The branched tertiary alkyl group usually has 4 or more carbon atoms, and usually has 30 or less, preferably 20 or less, more preferably 16 or less, and further preferably 12 or less carbon atoms.

Examples of branched tertiary alkyl groups include t-butyl, 2-ethyl-1,1-dimethylpentyl, 1-ethyl-1,2-dimethylpropyl, 1,1-dibutyldodecyl, 1-butyl-1-ethylhexyl, 1-ethyl-1-propylpentyl, 1,1-dimethylheptyl, 1,1-dimethyldecyl, 1,1-dimethylpentyl, 1,1-dibutylpentyl, 1-butyl-1-propylpentyl, 1-hexyl-1-methylnonyl, 1-ethyl-1-methylpropyl, and 1,1,2,2-tetramethylpropyl groups.
Of these, a t-butyl group or a 1,1-dimethylpropyl group is preferred, and a t-butyl group is more preferred.

The cycloalkyl group has usually 3 or more, more preferably 4 or more, and usually 30 or less, preferably 20 or less, more preferably 16 or less, and further preferably 12 or less.
Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, and a cyclolauryl group. Of these, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group are preferred.

The number of carbon atoms in the aromatic hydrocarbon group is usually 6 or more, and usually 30 or less, preferably 20 or less, more preferably 14 or less. Examples of such aromatic hydrocarbon groups include a phenyl group, a naphthyl group, an indanyl group, an indenyl group, a fluorenyl group, an anthracenyl group, and an azulenyl group. Of these, a phenyl group or a naphthyl group is preferred.
Examples of the heterocyclic group include an aliphatic heterocyclic group and an aromatic heterocyclic group. The number of carbon atoms in the aliphatic heterocyclic group is usually 2 or more, and is usually 20 or less, preferably 14 or less, more preferably 12 or less, further preferably 10 or less, and particularly preferably 6 or less. Examples of such an aliphatic heterocyclic group include an oxetanyl group, a pyrrolidinyl group, a tetrahydrofuryl group, a tetrahydrothienyl group, a piperidinyl group, a tetrahydropyranyl group, and a tetrahydrothiopyranyl group.

The number of carbon atoms in the aromatic heterocyclic group is usually 2 or more, and usually 30 or less, preferably 20 or less, more preferably 14 or less. Examples of such aromatic heterocyclic groups include a thienyl group, a furanyl group, a pyridyl group, a pyrimidyl group, a thiazolyl group, an oxazolyl group, a triazolyl group, a benzothiophenyl group, a benzofuranyl group, a benzothiazolyl group, a benzoxazolyl group, and a benzotriazolyl group. Among these, a thienyl group, a pyridyl group, a pyrimidyl group, a thiazolyl group, and an oxazolyl group are preferred.
The substituents that ^R1 and ^R2 "may have" are not particularly limited as long as they do not impair the effects of the present invention, but are preferably a halogeno group, a hydroxyl group, a carboxyl group, a carbamoyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group, an arylsulfonyl group, a boryl group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an amino group, a substituted amino group, a silyl group, a substituted silyl group, an aliphatic heterocyclic group, an aromatic hydrocarbon group, or an aromatic heterocyclic group. Among these, a halogen atom, an alkoxy group, or an alkylthio group is preferable in terms of being able to control the intramolecular polarity of the copolymer according to this embodiment.

^R3 and ^R4 each independently represent a hydrocarbon group which may have a heteroatom. Specifically, they represent a linear alkyl group which may have a substituent, a branched alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or a heterocyclic group which may have a substituent, and are the same as those defined for ^R1 and ^R2 . ^R3 and ^R4 may be the same or different.

Among these, it is preferable that at least one of ^R3 and ^R4 is an alkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent.
From the viewpoint of improving solubility, it is more preferable that both ^R3 and ^R4 are an alkyl group which may have a substituent, further preferably a branched alkyl group which may have a substituent, and particularly preferably a branched primary alkyl group which may have a substituent.

Alternatively, since Q becomes an asymmetric atom and the resulting copolymer can have a large number of diastereomers, it is more preferable that ^{R3 is a linear alkyl group which may have a substituent and R4 is} a branched alkyl group which may have a substituent, and particularly preferably that ^R3 is a linear alkyl group which may have a substituent and ^R4 is a branched primary alkyl group which may have a substituent, in order to improve the solubility.

The substituents that ^R3 and ^R4 may have are the same as those that ^R1 and ^R2 may have. Among them, a substituent consisting of an atom selected from the group including a hydrogen atom and a heteroatom is preferred, and a halogen atom such as a fluorine atom is more preferred in terms of increasing polarity, or a group having an amide bond such as an aminocarbonyl group or a carbonylamino group in terms of having hydrogen bonding ability.

It is also preferred that at least one of ^R3 and ^R4 is a branched alkyl group having no substituent, particularly preferably a 2-ethylhexyl group, a 2-ethylheptyl group, a 2-ethyloctyl group, a 2-ethylnonyl group, or a 2-ethyldecanyl group.
At least one of ^R3 and ^R4 preferably contains a branched chain alkyl group, and it is also preferable from the viewpoint of improving solubility that both of them are branched chain alkyl groups.

In formula (1A) and formula (1B), the substituents of R ¹ and R ² are different, so that the distance between the polymers can be made non-uniform, and therefore the solubility of the copolymer is improved.
This is preferable because the solubility of the copolymer according to the present embodiment in an organic solvent is easily improved, making it easier to apply the copolymer according to the present embodiment to form a film, and it is also preferable because the copolymer according to the present embodiment is prevented from precipitating or gelling when it is made into a solution, improving storage stability.

It is considered that the repeating unit having a linear alkyl group on the dioxopyrrole condensed ring and the repeating unit having a branched alkyl group on the dioxopyrrole condensed ring are respectively a repeating unit having a linear substituent and a repeating unit having a spatially expanding substituent. Therefore, the copolymers according to the present embodiment having the repeating units can have a part where the intermolecular distance between the molecules is moderately separated and a part where the molecules are close to each other, and can have an irregular distance between the copolymers, which is considered to improve the solubility.

In addition, since the copolymer of this embodiment has a repeating unit having a linear substituent and a repeating unit having a spatially expanding substituent, the intermolecular interactions between the dithieno fused ring and the dioxopyrrole fused ring, and/or between the dithieno fused rings themselves, are appropriately adjusted between the multiple copolymers. Therefore, despite being a high molecular weight substance, the copolymer simultaneously has improved solubility and is inhibited from flocculating, crystallizing, or gelling, and it is believed that this can result in improved stability of the ink containing the copolymer.

The copolymer according to this embodiment may contain two or more types of one or more of the repeating units represented by formula (1A), the repeating units represented by formula (1B), and the repeating units represented by formula (1C).
The copolymer according to this embodiment may contain a repeating unit other than the repeating unit represented by formula (1A), (1B) or (1C) within a range that does not impair the effects of the present invention. The ratio of the repeating unit represented by formula (1A), the repeating unit represented by formula (1B) and the repeating unit represented by formula (1C) to the repeating units constituting the copolymer according to this embodiment is not particularly limited, but is usually 2 mol% or more, preferably 10 mol% or more, more preferably 25 mol% or more, more preferably 50 mol% or more, even more preferably 70 mol% or more, and even more preferably 90% or more. Particularly preferably, the copolymer according to this embodiment contains a repeating unit represented by formula (1A), a repeating unit represented by formula (1B) and a repeating unit represented by formula (1C) and is composed only of these repeating units, or contains a polymer chain containing these repeating units and is composed only of these repeating units.

The proportion of the repeating units represented by formula (1A) in the repeating units constituting the copolymer according to this embodiment is not particularly limited, but is usually 1 mol% or more, preferably 2 mol% or more, more preferably 10 mol% or more, and even more preferably 30 mol% or more. On the other hand, it is usually 99 mol% or less, preferably 90 mol% or less, and more preferably 70 mol% or less.

The proportion of the repeating units represented by formula (1B) in the repeating units constituting the copolymer according to this embodiment is not particularly limited, but is usually 1 mol% or more, preferably 10 mol% or more, and more preferably 30 mol% or more. On the other hand, it is usually 99 mol% or less, preferably 90 mol% or less, and more preferably 70 mol% or less.

The proportion of the repeating units represented by formula (1C) in the repeating units constituting the copolymer according to this embodiment is not particularly limited, but is usually 1 mol% or more, preferably 2 mol% or more, more preferably 10 mol% or more, and even more preferably 30 mol% or more. On the other hand, it is usually 99 mol% or less, preferably 90 mol% or less, and more preferably 70 mol% or less.

In the copolymer according to this embodiment, the ratio of the number of repeating units represented by formula (1C) to the number of repeating units represented by formula (1A) + formula (1B) (1C/1A+1B) is not particularly limited, but is usually 0.01 or more, preferably 0.1 or more, and more preferably 0.5 or more. On the other hand, it is usually 100 or less, preferably 10 or less, and more preferably 2 or less.

In the copolymer according to this embodiment, the arrangement state of the repeating units represented by formula (1A), formula (1B) and formula (1C) may be either block or random. That is, the copolymer according to this embodiment may be either a block copolymer or a random copolymer. Furthermore, among these copolymers, a copolymer having an intermediate structure, for example, a random copolymer having block properties, may also be used. Also included are copolymers having a branched main chain with three or more terminals, and dendrimers. Among these, a block copolymer or a random copolymer is preferred in terms of ease of synthesis and the possibility of further reducing regularity, and a random copolymer is more preferred in terms of improved solubility of the copolymer and further improved storage stability of the ink in which the copolymer is dissolved.

In particular, the copolymer according to this embodiment preferably has repeating units represented by the following formulae (2A) and (2B). The copolymer having repeating units represented by the following formulae (2A) and (2B) is preferred in that it can more easily maintain the charge separation state.

In formula (2A) and formula (2B), A ¹ , A ² , and R ¹ to R ⁴ are as defined above.
In formula (2A) and formula (2B), ^Q1 and ^Q2 each independently represent an atom selected from the elements of Group 14 of the periodic table. ^Q1 and ^Q2 are the same as ^Q1 and ^Q2 in formula (1B) and formula (1C), respectively.
^R5 and ^R6 each independently represent a hydrocarbon group which may have a heteroatom and have the same meaning as ^R3 and ^R4 .

The copolymer according to this embodiment may contain two or more types of one or more repeating units represented by formula (2A) and one or more repeating units represented by formula (2B).
The copolymer according to this embodiment may contain a repeating unit other than the repeating unit represented by formula (2A) or (2B) as long as the effect of the present invention is not impaired. The total ratio of the repeating unit represented by formula (2A) and the repeating unit represented by formula (2B) in the repeating units constituting the copolymer according to this embodiment is not particularly limited, but is usually 2 mol% or more, preferably 10 mol% or more, more preferably 25 mol% or more, more preferably 50 mol% or more, even more preferably 70 mol% or more, and even more preferably 90% or more. Particularly preferably, the copolymer according to this embodiment contains a repeating unit represented by formula (2A) and a repeating unit represented by formula (2B) and is composed only of these repeating units, or contains a polymer chain containing these repeating units and is composed only of these repeating units.

The proportion of the repeating units represented by formula (2A) in the repeating units constituting the copolymer according to the present embodiment is not particularly limited, but is usually 1 mol % or more, preferably 10 mol % or more, more preferably 20 mol % or more, and is usually 99 mol % or less, preferably 90 mol % or less, more preferably 70 mol % or less.
The proportion of the repeating units represented by formula (2B) in the repeating units constituting the copolymer according to the present embodiment is not particularly limited, but is usually 1 mol % or more, preferably 10 mol % or more, more preferably 20 mol % or more, and is usually 99 mol % or less, preferably 90 mol % or less, more preferably 70 mol % or less.

In the copolymer according to this embodiment, the ratio (2A/2B) of the number of repeating units represented by formula (2A) to the number of repeating units represented by formula (2B) is not particularly limited, but is usually 0.01 or more, preferably 0.1 or more, more preferably 0.2 or more, and is usually 100 or less, preferably 10 or less, more preferably 5 or less.
In the copolymer according to this embodiment, the arrangement state of the repeating units represented by formula (2A) and formula (2B) may be any of alternating, block, or random. That is, the copolymer according to this embodiment may be any of alternating, block, or random copolymers. Furthermore, among these copolymers, copolymers having an intermediate structure, such as random copolymers having block properties, may also be used. Also included are copolymers having branches in the main chain and three or more terminals, and dendrimers. Among these, block or random copolymers are preferred in that they are easily synthesized and the regularity can be further reduced, and random copolymers are more preferred in that the solubility of the copolymer is improved and the storage stability of the ink in which the copolymer is dissolved can be improved.

Preferred specific examples of the copolymer according to this embodiment are shown below. However, the copolymer according to the present invention is not limited to the following examples. In the following examples, m and n represent mole fractions and are positive numbers such that m+n=1.

The polystyrene-equivalent weight average molecular weight (Mw) of the copolymer according to this embodiment is usually 2.0 × 10 ⁴ or more, preferably 3.0 × 10 ⁴ or more, more preferably 4.0 × 10 ⁴ or more, even more preferably 5.0 × 10 ⁴ or more, even more preferably 7.0 × 10 ⁴ or more, and particularly preferably 1.0 × 10 ⁵ or more. On the other hand, it is preferably 1.0 × 10 ⁷ or less, more preferably 1.0 × 10 ⁶ or less, and particularly preferably 5.0 × 10 ⁵ or less. From the viewpoint of increasing the light absorption wavelength, realizing high absorbance, realizing high carrier mobility, and solubility in organic solvents, it is preferable that the weight average molecular weight is within this range.

The number average molecular weight (Mn) of the copolymer according to this embodiment in terms of polystyrene is usually 5.0 × 10 ³ or more, preferably 1.0 × 10 ⁴ or more, more preferably 2.0 × 10 ⁴ or more, even more preferably 2.5 ^× 10 ⁴ or more, and particularly preferably 3.0 × 10 4 or more. On the other hand, it is preferably 1.0 × 10 ^{7 or} less, more preferably 1.0 × 10 ⁶ or less, even more preferably 5.0 × 10 ⁵ or less, particularly preferably 2.0 × 10 5 or less, and particularly preferably 1.0 × 10 ⁵ or less. From the viewpoint of increasing the light absorption wavelength, realizing high absorbance, realizing high carrier mobility, and from the viewpoint of solubility in organic solvents, it is preferable that the number average molecular weight is in this range.

The molecular weight distribution (PDI, (weight average molecular weight/number average molecular weight (Mw/Mn))) of the copolymer according to this embodiment is usually 1.0 or more, preferably 1.1 or more, more preferably 1.2 or more, and even more preferably 1.3 or more. On the other hand, it is preferably 20.0 or less, more preferably 15.0 or less, and even more preferably 10.0 or less. It is preferable that the molecular weight distribution is in this range, since the solubility of the copolymer can be in a range suitable for application.

The polystyrene-equivalent weight average molecular weight, number average molecular weight, and molecular weight distribution of the copolymer according to this embodiment can be determined by gel permeation chromatography (GPC). Specifically, the measurement can be performed by using two Polymer Laboratories GPC columns (PLgel MIXED-B 10 μm, inner diameter 7.5 mm, length 30 cm) connected in series as columns, LC-10AT (Shimadzu Corporation) as a pump, CTO-10A (Shimadzu Corporation) as an oven, and a differential refractive index detector (Shimadzu Corporation: RID-10A) and a UV-vis detector (Shimadzu Corporation: SPD-10A) as detectors. The measurement method is to dissolve the copolymer to be measured (1 mg) in chloroform (200 mg) and inject 1 μL of the resulting solution into the column. Measurement is performed using chloroform as the mobile phase at a flow rate of 1.0 mL/min. LC-Solution (Shimadzu Corporation) was used for the analysis.

The copolymer according to this embodiment preferably has a light absorption maximum wavelength (λ _max ) of usually 470 nm or more, preferably 480 nm or more, and usually 1200 nm or less, preferably 1000 nm or less, more preferably 900 nm or less. The half-width of the absorption maximum wavelength on the longest wavelength side in the range of 350 nm to 850 nm is usually 10 nm or more, preferably 20 nm or more, and usually 300 nm or less. When the copolymer according to this embodiment is used for solar cell applications, it is desirable that the absorption wavelength region of the copolymer is as close as possible to the wavelength region of sunlight.

The solubility of the copolymer according to the present embodiment is not particularly limited, but the solubility in chlorobenzene at 25° C. is usually 0.1% by mass or more, preferably 0.5% by mass or more, and more preferably 1% by mass or more, and is usually 30% by mass or less, preferably 20% by mass. High solubility is preferable because a thicker film can be formed by coating.
In the copolymer according to the present embodiment, it is preferable that a moderate interaction occurs between the molecules. In this specification, the interaction between the molecules means that the distance between the polymer chains is shortened by the interaction between the molecules, such as π-π stacking. The stronger the interaction, the higher the mobility and/or crystallinity tends to be exhibited, and therefore it is considered to be suitable as a semiconductor material. That is, since electron transfer between molecules is likely to occur in a copolymer that interacts between molecules, for example, when the copolymer according to the present invention is used in the active layer of a photoelectric conversion element, it is considered that holes generated at the interface between the p-type semiconductor compound and the n-type semiconductor compound in the active layer can be efficiently transported to the electrode (anode).

Methods for measuring crystallinity include X-ray diffraction (XRD). In this specification, "having crystallinity" means that the X-ray diffraction spectrum obtained by XRD measurement has a diffraction peak. "Having crystallinity" is considered to mean that the molecules have a layered structure arranged with each other, which is preferable in that it tends to make it possible to thicken the active layer described below. XRD measurement can be performed based on the method described in a publicly known document (Guide to X-ray Crystal Analysis (Applied Physics Selection 4)).

The hole mobility (sometimes referred to as "Hall mobility") of the copolymer according to this embodiment is usually 1.0×10 ^-7 cm ² /Vs or more, preferably 1.0×10 ^-6 cm ² /Vs or more, more preferably 1.0×10 ^-5 cm ² /Vs or more, and particularly preferably 1.0×10 ^-4 cm ² /Vs or more. On the other hand, the hole mobility of the copolymer according to this embodiment is usually 1.0×10 ⁴ cm ² /Vs or less, preferably 1.0×10 ³ cm ² /Vs or less, more preferably 1.0×10 ² cm ² /Vs or less, and particularly preferably 1.0×10 cm ² /Vs or less. Since the hole mobility is in this range, the copolymer according to this embodiment is preferably used as a semiconductor material. In addition, in order to obtain a high conversion efficiency in a photoelectric conversion element, the balance between the mobility of the n-type semiconductor compound and the mobility of the p-type semiconductor compound is important. The copolymer according to this embodiment is used as a p-type semiconductor compound in a photoelectric conversion element, and from the viewpoint of bringing the hole mobility of the copolymer closer to the electron mobility of the n-type semiconductor compound, it is preferable that the hole mobility of the copolymer is within this range. The hole mobility can be measured by the FET method. The FET method can be performed by the method described in a known document (JP 2010-045186 A).

On the other hand, it is preferable that the copolymer according to this embodiment has high storage stability in a solution state. High storage stability means that the copolymer is less likely to aggregate when in solution. More specifically, when 2 mg of the copolymer according to this embodiment is placed in a 2 mL screw vial, heated and dissolved in o-xylene to a concentration of 1.5% by mass, and then cooled to room temperature, it is preferable that the copolymer does not gel for 5 minutes or more after cooling begins, and more preferably does not gel for 1 hour or more.

It is preferable that the amount of impurities in the copolymer according to this embodiment is as small as possible. In particular, if a transition metal catalyst such as palladium or copper remains, exciton trapping occurs due to the heavy atom effect of the transition metal, inhibiting charge transfer, and as a result, there is a risk of reducing the photoelectric conversion efficiency when the copolymer according to the present invention is used in a photoelectric conversion element. The concentration of the transition metal catalyst is usually 1000 ppm or less, preferably 500 ppm or less, and more preferably 100 ppm or less per 1 g of copolymer. On the other hand, it is usually greater than 0 ppm, and may be 1 ppm or more, or 3 ppm or more.

The amount of atoms remaining that constitute the terminal residues (for example, X and Y in formulae (3A) to (3C) described later) in the copolymer according to this embodiment is not particularly limited, but is usually 6000 ppm or less, preferably 4000 ppm or less, more preferably 3000 ppm or less, even more preferably 2000 ppm or less, even more preferably 1000 ppm or less, particularly preferably 500 ppm or less, and most preferably 200 ppm or less per 1 g of copolymer. On the other hand, it is usually more than 0 ppm, preferably 1 ppm or more, and more preferably 3 ppm or more.

In particular, the residual amount of Sn atoms in the copolymer according to this embodiment is usually 5000 ppm or less, preferably 4000 ppm or less, more preferably 2500 ppm or less, even more preferably 1000 ppm or less, even more preferably 750 ppm or less, particularly preferably 500 ppm or less, and most preferably 100 ppm or less per 1 g of copolymer. On the other hand, it is usually more than 0 ppm, preferably 1 ppm or more, more preferably 3 ppm or more. The residual amount of Sn atoms being 5000 ppm or less means that there are few alkylstannyl groups that are easily thermally decomposed, and it is preferable because it can obtain high performance in terms of stability.

The amount of remaining halogen atoms in the copolymer according to this embodiment is usually 5000 ppm or less, preferably 4000 ppm or less, more preferably 2500 ppm or less, even more preferably 1000 ppm or less, even more preferably 750 ppm or less, particularly preferably 500 ppm or less, and most preferably 100 ppm or less, per 1 g of copolymer. On the other hand, it is usually greater than 0 ppm, preferably 1 ppm or more, more preferably 3 ppm or more. It is preferable to reduce the amount of remaining halogen atoms to 5000 ppm or less, since this tends to improve the performance of the copolymer, such as the photoelectric conversion characteristics and durability.

The remaining amount of atoms constituting the terminal residues (for example, X and Y in formulae (3A) to (3C) described later) in the copolymer can be determined by measuring the amount of the elements. Elemental analysis of the copolymer can be carried out, for example, by ICP mass spectrometry for Pd and Sn, and also by ICP mass spectrometry for bromine ions (Br ⁻ ) and iodine ions (I ⁻ ).

ICP mass spectrometry can be carried out by the method described in a known document ("Plasma Ion Source Mass Analysis" (Academic Society Publishing Center)). Specifically, for Pd and Sn, after wet decomposition of a sample, Pd and Sn in the decomposition solution can be quantified by a calibration curve method using an ICP mass spectrometer (ICP mass spectrometer 7500ce type manufactured by Agilent Technologies). In addition, for Br ^- and I ^- , a sample is burned in a sample combustion device (sample combustion device QF-02 type manufactured by Mitsubishi Chemical Analytech Co., Ltd.), the combustion gas is absorbed in an alkaline absorption solution containing a reducing agent, and then Br ^- and I ^- in the absorption solution can be quantified by a calibration curve method using an ICP mass spectrometer (ICP mass spectrometer 7500ce type manufactured by Agilent Technologies).

2. Method for producing p-type semiconductor compound
The method for producing the p-type semiconductor (copolymer) according to this embodiment is not particularly limited, and for example, it can be produced by a known method using a compound having a dioxopyrrole condensed ring and a compound having a dithieno condensed ring. A preferred method includes a method of polymerizing a compound represented by the following general formula (3A), a compound represented by the following general formula (3B), and a compound represented by the following general formula (3C) in the presence of a suitable catalyst if necessary.

In formula (3A), ^R1 and ^A1 are defined as defined in formula (1A), and in formula (3B), ^R2 and ^A2 are defined as defined in formula (1B). In formula (3C), ^R3 , ^R4 , and Q are defined as defined in formula (1C).
In formulas (3A) to (3C), X and Y can be appropriately selected depending on the type of polymerization reaction. For example, the copolymer according to this embodiment can be produced by a polymerization reaction using a coupling reaction. Usable reactions include the Suzuki-Miyaura cross-coupling reaction method, the Stille coupling reaction method, the Yamamoto coupling reaction method, the Grignard reaction method, the Heck reaction method, the Sonogashira reaction method, or a reaction method using an oxidizing agent such as FeCl ₃ , a method using an electrochemical oxidation reaction, or a reaction method by decomposition of an intermediate compound having a suitable leaving group. Among these, the Suzuki-Miyaura coupling reaction method, the Stille coupling reaction method, the Yamamoto coupling reaction method, or the Grignard reaction method are preferred in that structure control is easy. In particular, the Suzuki-Miyaura cross-coupling reaction method, the Stille coupling reaction method, and the Grignard reaction method are preferred in terms of the availability of materials and the simplicity of the reaction procedure. These reactions can be carried out according to the methods described in known publications such as "Cross-coupling - Basics and Industrial Applications - (CMC Publishing)", "Transition Metal Catalytic Reactions for Organic Synthesis (by Jiro Tsuji: edited by the Society of Organic Synthesis)" and "Catalytic Reactions for Organic Synthesis 103 (by Tamejiro Hiyama: Tokyo Kagaku Dojin)".

Examples of X and Y each independently include a halogen atom, an alkylstannyl group, an alkylsulfo group, an arylsulfo group, an arylalkylsulfo group, a borate ester residue, a sulfonium methyl group, a phosphonium methyl group, a phosphonate methyl group, a monohalogenated methyl group, a boric acid residue (-B(OH) ₂ ), a formyl group, a silyl group, an alkenyl group, or an alkynyl group.

The halogen atom is preferably a bromine atom or an iodine atom. The alkenyl group may, for example, be an alkenyl group having from 2 to 12 carbon atoms.
Examples of the borate ester residue include those represented by the following formula: In the following formula, Me represents a methyl group, and Et represents an ethyl group.

Examples of alkylstannyl groups include those shown in the following formula. In the formula, Me represents a methyl group, and Bu represents an n-butyl group.

From the viewpoint of synthesis of the compounds represented by formulae (3A) to (3C) and ease of reaction, it is preferred that one of X and Y is a halogen atom and the other is an alkylstannyl group, a borate residue, or a boric acid residue (-B(OH) ₂ ).
The polymerization reaction can be carried out according to a known method. For example, when X or Y is an alkylstannyl group, the reaction can be carried out according to the known conditions of the Stille coupling reaction. When X or Y is a borate ester residue or a boric acid residue, the reaction can be carried out according to the known conditions of the Suzuki-Miyaura coupling reaction. When X or Y is a silyl group, the reaction can be carried out according to the known conditions of the Hiyama coupling reaction. As a catalyst for the coupling reaction, for example, a combination of a transition metal such as palladium and a ligand (for example, a phosphine ligand such as triphenylphosphine) can be used.

A method for producing the copolymer according to this embodiment using the Stille coupling reaction method will be described below. When using the Stille coupling reaction method, it is preferable that in formulas (3A) to (3C), X is a halogen atom and Y is an alkylstannyl group, or X is an alkylstannyl group and Y is a halogen atom.
The ratio of the total amount of the compound represented by formula (3C) to the amount of the compounds represented by formula (3A) and formula (3B) used in the polymerization reaction ((3A+3B)/3C) is, in terms of molar ratio, usually 0.90 or more, preferably 0.95 or more, and usually 1.3 or less, preferably 1.2 or less. A ratio within such a range is preferred in terms of being able to obtain a high molecular weight compound in a higher yield.

The ratio (3A/3B) of the amount of the compound represented by formula (3B) to the amount of the compound represented by formula (3A) used in the polymerization reaction is not particularly limited and can be set appropriately depending on the purpose, but is usually 0.01 or more, preferably 0.1 or more, and more preferably 0.5 or more, in terms of molar ratio. On the other hand, it is usually 100 or less, preferably 10 or less, and more preferably 2 or less.

When it is desired that the copolymer according to the present embodiment has a high purity, it is preferable to carry out the polymerization reaction after purifying the monomers (compounds represented by formulae (3A) to (3C)) before polymerization. Examples of the purification method include distillation, sublimation purification, column chromatography, and recrystallization.
For example, when the copolymer according to the present invention is used as a material for an organic photoelectric conversion element, it is desirable that the copolymer has a high purity because the high purity of the copolymer can improve the device characteristics. When the copolymer according to the present invention is used as a material for an organic photoelectric conversion element, the purity of each of the compounds represented by formulas (3A) to (3C) is usually 90% or more, preferably 95% or more.

Examples of catalysts used to promote polymerization in the polymerization reaction include transition metal catalysts. The transition metal catalyst may be selected according to the type of polymerization. Examples of transition metal catalysts include homogeneous transition metal catalysts and heterogeneous transition metal catalysts.
The homogeneous transition metal catalyst is preferably one that is sufficiently soluble in the solvent used in the polymerization reaction.Preferred examples include late transition metal complex catalysts, particularly those containing palladium, nickel, iron, or copper.Specific examples include zero-valent palladium catalysts such as tetrakis(triphenylphosphine)palladium (Pd(PPh ₃ ) ₄ ) or tris(dibenzylideneacetone)dipalladium (Pd ₂ (dba) ₃ ); palladium (Pd) catalysts such as divalent palladium catalysts such as bis(triphenylphosphine)palladium chloride (PdCl ₂ ((PPh ₃ )) ₂ ) or palladium acetate; nickel catalysts such as Ni(dppp)Cl ₂ or Ni(dppe)Cl ₂ ; iron catalysts such as iron chloride; copper catalysts such as copper iodide. Here, dba represents dibenzylideneacetone, dppp represents 1,2-bis(diphenylphosphino)propane, and dppe represents 1,2-bis(diphenylphosphino)ethane.

Specific examples of zero-valent Pd catalysts include Pd( _PPh3 ) ₄ , Pd(P(o-tolyl) ₃ ) ₄ , Pd( _PCy3 ) ₂ , _Pd2 (dba) ₃ , _{and PdCl2(PPh3)2 . When} a divalent Pd catalyst such as _PdCl2 ( _PPh3 ) ₂ or palladium acetate is used, it is preferable to use it in combination with an organic ligand such as _PPh3 or P(o-tolyl) ₃ . Here, Ph represents a phenyl group, Cy represents a cyclohexyl group, and o-tolyl represents a 2-tolyl group.

Heterogeneous transition metal catalysts include catalysts obtained by supporting the above-mentioned homogeneous transition metal catalysts on a carrier. Preferred examples of the transition metals contained in the heterogeneous transition metal catalyst include late transition metals including palladium, nickel, iron, or copper. As organic ligands contained in the heterogeneous transition metal complex catalyst, those similar to those listed for the homogeneous transition metal complex catalyst can be used. In addition, organic ligands described in a known document (Strem, "Heterogeneous Catalysts" (2011)) can also be used. Examples of carriers include metals, nanocolloids, nanoparticles, magnetic compounds, metal oxides, porous substances, clays, polymers such as urea resins, and dendrimers. Specific examples of porous substances include microporous substances, mesoporous substances, activated carbon, silica gel, alumina, and zeolites. In particular, it is preferable to use a heterogeneous transition metal complex catalyst supported on a polymer because the heterogeneous transition metal complex catalyst can be easily recovered. In addition, it is preferable for the polymer to be porous in order to promote the reaction.

In the polymerization reaction, it is preferable to use two or more transition metal complex catalysts, since a high molecular weight copolymer can be obtained. For example, two or more homogeneous transition metal complexes may be used, two or more heterogeneous transition metal complexes may be used, or a homogeneous transition metal complex and a heterogeneous transition metal complex may be used in combination. Among these two or more transition metal complex catalysts,
At least one of the transition metal complex catalysts is preferably a heterogeneous metal complex catalyst, because it can convert monomers into oligomers quickly under coupling reaction conditions. In addition, since the rate of polymerization reaction by heterogeneous metal catalysts tends to decrease when the monomers are oligomerized, it is preferable to use homogeneous metal catalysts to induce the oligomer into a polymer in order to obtain a high molecular weight substance. From this viewpoint, it is more preferable that at least one of the two or more transition metal complex catalysts is a heterogeneous metal complex catalyst, and at least one of the two or more transition metal complex catalysts is a homogeneous metal complex catalyst.

The addition rate of the transition metal complex relative to the total amount of the compounds represented by formulae (3A) to (3C) is usually 1×10 ⁻⁴ mol % or more, preferably 1×10 ⁻³ mol % or more, more preferably 1×10 ⁻² mol % or more, and on the other hand, usually 1×10 ² mol % or less, more preferably 5 mol % or less. A catalyst addition rate in this range is preferred in that a higher molecular weight copolymer tends to be obtained at lower cost and in higher yield.
When a transition metal catalyst is used, an alkali, a cocatalyst or a phase transfer catalyst may be used in combination.

Examples of the alkali include inorganic bases such as potassium carbonate, sodium carbonate, and cesium carbonate; and organic bases such as triethylamine.
Examples of the cocatalyst include inorganic salts such as cesium fluoride, copper oxide, and copper halide. The cocatalyst addition rate is usually 1×10 ⁻⁴ mol % or more, preferably 1×10 −3 mol % or more, and more preferably 1×10 ⁻² mol % or more, based on the total amount of the compounds represented by formulas (3A) to (3C), and is ^{usually 1×10 4 mol} % or less, preferably 1×10 ³ mol % or less, and more preferably 1.5×10 ² mol % or less. The cocatalyst addition rate within this range is preferred because it tends to result in a copolymer that is lower cost and in a higher yield.

Examples of the phase transfer catalyst include tetraethylammonium hydroxide and quaternary ammonium salts such as Aliquat 336 (manufactured by Aldrich). The addition rate of the phase transfer catalyst is usually 1×10 ⁻⁴ mol % or more, preferably 1×10 −3 mol % or more, more preferably 1×10 ⁻² mol % or more, based on the total amount of the compounds represented by formulas ( ^3A ) to (3C), and is usually 5 mol % or less, more preferably 3 mol % or less. The addition rate of the phase transfer catalyst within this range is preferred because it tends to result in a copolymer being obtained at a lower cost and in a higher yield.

Examples of solvents used in the polymerization reaction include saturated hydrocarbons such as pentane, hexane, heptane, octane, or cyclohexane; aromatic hydrocarbons such as benzene, toluene, ethylbenzene, or xylene; halogenated aromatic hydrocarbons such as chlorobenzene, dichlorobenzene, or trichlorobenzene; alcohols such as methanol, ethanol, propanol, isopropanol, butanol, or t-butyl alcohol; water; ethers such as dimethyl ether, diethyl ether, methyl-t-butyl ether, tetrahydrofuran, tetrahydropyran, or dioxane; and aprotic polar organic solvents such as DMF. These solvents may be used alone or in combination of two or more.

The rate of addition of the solvent is usually 1×10 ⁻² mL or more, preferably 1×10 ⁻¹ mL or more, and more preferably 1 mL or more, per 1 g of the total of the compounds represented by formulae (3A) to (3C), and is usually 1×10 ⁵ mL or less, preferably 1×10 ³ mL or less, and more preferably 2×10 ² mL or less. A rate of addition of the solvent within this range is preferred in that it makes it easier to control the reaction.

The reaction temperature of the polymerization reaction is usually 0° C. or higher, preferably 20° C. or higher, more preferably 40° C. or higher, and even more preferably 60° C. or higher. On the other hand, the reaction temperature is usually 300° C. or lower, preferably 250° C. or lower.
° C. or less, more preferably 200 ° C. or less, further preferably 180 ° C. or less, particularly preferably 160 ° C. or less. The heating method is not particularly limited, and examples thereof include oil bath heating, thermocouple heating, infrared heating, microwave heating, and contact heating using an IH heater. The polymerization reaction time is usually 1 minute or more, preferably 10 minutes or more, and on the other hand, usually 160 hours or less, preferably 120 hours or less, more preferably 100 hours or less. The polymerization reaction is preferably carried out under a nitrogen (N ₂ ) or argon (Ar) atmosphere. By carrying out the reaction under these reaction conditions, a copolymer can be obtained in a shorter time and with a higher yield.

It is preferable to further perform terminal treatment on the copolymer obtained by the polymerization reaction. By performing terminal treatment on the copolymer, the amount of remaining terminal residues (X and Y mentioned above) of the copolymer can be reduced. For example, when the copolymer is polymerized by the Stille coupling reaction, the halogen atoms such as bromine (Br) and iodine (I) and alkylstannyl groups present at the terminals of the copolymer can be reduced by terminal treatment. This terminal treatment is preferable because it allows the production of a copolymer with better performance in terms of efficiency and durability.

The method for terminal treatment of the copolymer carried out after the polymerization reaction is not particularly limited, but may be, for example, a method in which the terminal residue is replaced with another substituent such as an aromatic group.
For example, the following methods can be used as terminal treatment methods when the copolymer is polymerized by the Stille coupling reaction. Terminal treatment of halogen atoms in the copolymer can be carried out by adding an aryltrialkyltin as a terminal treatment agent to the reaction system before purification after the polymerization reaction, and then heating and stirring. Examples of aryltrialkyltin include phenyltrimethyltin and thienyltrimethyltin. Substituting the halogen atoms at the terminals of the copolymer with aromatic groups is preferred because it makes the copolymer more stable due to the conjugation stabilization effect.

The amount of the terminal treatment agent to be added is not particularly limited, but is usually 1.0×10 ⁻² molar equivalents or more, preferably 0.1 molar equivalents or more, more preferably 1 molar equivalent or more, relative to the amount of the monomer (3A and 3B, or 3C) having a halogen atom at the end used in the polymerization reaction, and is usually 50 molar equivalents or less, preferably 20 molar equivalents or less, more preferably 10 molar equivalents or less. The reaction temperature for the halogen atom terminal treatment is usually 0° C. or more, preferably 20° C. or more, more preferably 40° C. or more, and even more preferably 60° C. or more. On the other hand, it is usually 300° C. or less, preferably 250° C. or less, more preferably 200° C. or less, even more preferably 180° C. or less, and particularly preferably 160° C. or less. The heating method is not particularly limited, but examples thereof include oil bath heating, thermocouple heating, infrared heating, microwave heating, and contact heating using an IH heater. The reaction time for the halogen atom terminal treatment of the copolymer is not particularly limited, but is usually 30 minutes or more, preferably 1 hour or more, and usually 50 hours or less, preferably 20 hours or less. By carrying out the reaction under these reaction conditions, the terminal treatment can be carried out in a shorter time with a higher conversion rate.

The alkylstannyl groups of the copolymer can be terminated by adding an aryl halide as a terminal treatment agent to the reaction system before purification after the polymerization reaction, followed by heating and stirring. Examples of aryl halides include iodothiophene, iodobenzene, bromothiophene, and bromobenzene. By replacing the alkylstannyl groups at the ends of the copolymer with another substituent, the Sn atoms in the alkylstannyl groups, which are susceptible to thermal decomposition, are no longer present in the copolymer, and deterioration of the copolymer over time can be suppressed. In addition, replacing the alkylstannyl groups at the ends of the copolymer with aryl groups is also preferable in that the copolymer can be made more stable due to the conjugation stabilization effect.

The amount of the terminal treatment agent to be added is not particularly limited, but is usually 1.0×10 ⁻² molar equivalents or more, preferably 0.1 molar equivalents or more, more preferably 1 molar equivalent or more, relative to the amount of the monomer (3A and 3B, or 3C) having an alkylstannyl group at the end used in the polymerization, and is usually 50 molar equivalents or less, preferably 20 molar equivalents or less, more preferably 10 molar equivalents or less. The reaction temperature and reaction conditions for the terminal treatment of the alkylstannyl group can be the same as those for the terminal treatment of the halogen atom of the copolymer. By carrying out the reaction under these reaction conditions, the terminal treatment can be carried out in a shorter time and with a higher conversion rate.

In addition, the following methods can be used for terminal treatment when a copolymer is polymerized by the Suzuki-Miyaura cross-coupling reaction. A method for terminal treatment of halogen atoms in a copolymer can be to add an arylboronic acid, followed by heating and stirring. A method for terminal treatment of boron atom-containing groups in a copolymer can be to add an aryl halide as a terminal treatment agent, followed by heating and stirring.

There is no particular limitation on the method of terminal treatment of the terminal residue X and the method of terminal treatment of the terminal residue Y, but it is preferable to carry out each independently. There is no particular limitation on the order of each terminal treatment, and it can be appropriately selected.
The terminal treatment may be performed before or after the purification of the copolymer. When the terminal treatment is performed after the purification of the copolymer, the copolymer and one of the terminal treatment agents (e.g., aryl halide or aryl trialkyl tin) are dissolved in an organic solvent, and then a transition metal catalyst such as a palladium catalyst is added to react, and the other terminal treatment agent (aryl trialkyl tin or aryl halide) is added to react. From the viewpoint of promoting the reaction, it is preferable to perform heating and stirring during the terminal treatment, as in the case where the terminal treatment is performed before the purification of the copolymer. In addition, from the viewpoint of improving the yield, it is also preferable to perform the reaction under nitrogen conditions. The reaction time is not particularly limited, but is usually 30 minutes or more, preferably 1 hour or more, and is usually 25 hours or less, preferably 10 hours or less.

The amount of the transition metal catalyst added is not particularly limited, but is usually 5.0×10 ^{−3 molar equivalents or more, preferably 1.0×10 −2} molar equivalents or more, and is usually 1.0×10 ⁻¹ molar equivalents or less, preferably 5.0×10 ⁻² molar equivalents or less, relative to the total amount of the compounds represented by formulas ^(3A ) to (3C). By adding the catalyst in this range, terminal treatment can be performed at lower cost and with a higher conversion rate.

The amount of alkylstannyl group terminal treatment agent added during terminal treatment after copolymer purification is not particularly limited, but is usually 1.0×10 ⁻² molar equivalents or more, preferably 1.0×10 ⁻¹ molar equivalents or more, more preferably 1 molar equivalent or more, relative to the amount of alkylstannyl group-terminated monomer (3B and 3C, or 3A) used in polymerization, and is usually 50 molar equivalents or less, preferably 20 molar equivalents or less, more preferably 10 molar equivalents or less. By adding an amount of terminal treatment agent within this range, terminal treatment can be performed at lower cost and with a higher conversion rate.

The amount of the terminal treatment agent for halogen atoms added during terminal treatment after copolymer formation is not particularly limited, but is usually 1.0×10 ⁻² molar equivalents or more, preferably 1.0×10 ⁻¹ molar equivalents or more, more preferably 1 molar equivalent or more, relative to the amount of monomer (3A and 3B, or 3C) having a halogen atom at its end used in polymerization, and is usually 50 molar equivalents or less, preferably 20 molar equivalents or less, more preferably 10 molar equivalents or less. By adding the terminal treatment agent in this range, terminal treatment can be performed at lower cost and with a higher conversion rate.

The step to be performed after the polymerization reaction is not particularly limited, but usually, a step of separating the copolymer is performed. When terminal treatment of the copolymer is performed, it is preferable to perform a step of separating the copolymer after the terminal treatment. If necessary, the copolymer may be further separated and purified before the terminal treatment of the copolymer. From the viewpoint of obtaining the copolymer in a shorter treatment step, it is preferable to perform terminal treatment of the copolymer, separation of the copolymer, and purification of the copolymer in this order after the polymerization reaction.

Examples of methods for separating the copolymer include a method of mixing the reaction solution with a poor solvent to precipitate the copolymer, and a method of quenching active species in the reaction solution with water or hydrochloric acid, followed by extracting the copolymer with an organic solvent and then distilling off the organic solvent.
Methods for purifying the copolymer include known methods such as reprecipitation purification, extraction using a Soxhlet extractor, gel permeation chromatography, or metal removal using a scavenger.

[2-1. Method for producing compounds represented by formulae (3A) to (3C)]
The compounds represented by formulae (3A) and (3B) used as raw materials for the polymerization reaction can be produced in accordance with the method described in J. Am. Chem. Soc., 2010, 132(22), 7595-7597. The compound represented by formula (3C) can be produced in accordance with the method described in J. Mater. Chem., 2011, 21, 3895, and J. Am. Chem. Soc., 2008, 130, 16144-16145.

A particularly preferred method for producing the compound represented by formula (3C) is to use a compound represented by formula (4C) as a raw material. More specifically, the compound represented by formula (3C) can be obtained by reacting a non-nucleophilic base with the compound represented by formula (4C) and then reacting with an electrophilic agent. This method can reduce the amount of by-products, for example those having only one substituent Y, that are generated when producing the compound represented by formula (3C). A small amount of by-products is preferable in that the copolymer according to this embodiment obtained by the polymerization reaction can have a larger molecular weight.

In formula (4C), Q and R ³ to R ⁴ are the same as defined in formula (3C).
Examples of non-nucleophilic bases include metal hydrides, metal alkoxides having bulky substituents, amines, phosphazene bases, metal magnesium reagents having bulky substituents (Grignard reagents), and metal amides. The use of non-nucleophilic bases is preferable in that it can effectively suppress nucleophilic attack on the condensed ring of the compound represented by formula (4C) and suppress the generation of by-products. In terms of high basicity and low nucleophilicity, the non-nucleophilic base is preferably a metal amide, and particularly preferably a metal amide having a bulky substituent.

The compound represented by general formula (3C) can be obtained by deprotonating the compound represented by general formula (4C) using a non-nucleophilic base, and then reacting the generated anion species with an electrophile.
When the substituent Y is an alkylstannyl group, the electrophile is not particularly limited, but for example, a trialkyltin halide compound can be mentioned.When the substituent Y is a boric acid residue or a boric acid ester residue, the electrophile is not particularly limited, but a boric acid triester is preferably used.The compound having a boric acid ester residue obtained by the reaction with the boric acid triester can be isolated as it is, or the boric acid ester residue can be hydrolyzed to a boric acid residue and then the compound can be isolated.

The method for purifying the compound represented by formula (3C) after the reaction is not particularly limited, and any known method can be used. A particularly preferred method is to use a method using zeolite. More specifically, the obtained compound may be brought into contact with zeolite. This method is preferred because it allows the compound to be more easily purified while preventing decomposition of the compound represented by (3C). As the zeolite, aluminosilicate-based zeolites such as aluminosilicate, metallosilicate, or silicalite; or phosphate-based zeolites such as aluminophosphate, gallophosphate, or beryllophosphate are preferred.

Examples of a method for contacting the obtained compound represented by formula (3C) with a zeolite include (1) a method in which a layer containing zeolite is prepared and the compound is passed through the layer, and (2) a method in which zeolite is introduced into the composition and then the zeolite is removed.
There is no particular limit to the amount of non-nucleophilic base added to the compound represented by formula (4C), and usually 2 molar equivalents or more of non-nucleophilic base is used relative to the compound represented by formula (4C). On the other hand, in order to reduce the amount of reagent used, the amount of non-nucleophilic base is usually 20 molar equivalents or less, preferably 10 molar equivalents or less, and more preferably 5 molar equivalents or less. There is no particular limit to the amount of electrophilic reagent added to the compound represented by formula (4C), and usually 2 molar equivalents or more of electrophilic reagent is used relative to the compound represented by formula (4C). On the other hand, in order to reduce the amount of reagent used, the amount of electrophilic reagent is usually 20 molar equivalents or less, preferably 10 molar equivalents or less, and more preferably 5 molar equivalents or less.

The compound represented by formula (4C) can be produced using known methods, but it is particularly preferable to produce it using the method shown below. That is, the compound represented by formula (4C) can be obtained by removing the silyl group from a compound in which a silyl group is added to the compound represented by formula (4C). This method is preferable in that it can produce the compound represented by formula (4C) in a higher yield.

For example, the compound represented by formula (4C) can be produced by subjecting the compound represented by the following formula (5C) to a desilylation reaction using an acid.

In formula (5C), Q and R ³ to R ⁴ are the same as those defined in formula (3C). In (5C), R ⁵ to R ⁶ represent a silyl group which may have a substituent. The two substituents R ⁷ may be different from each other. Examples of the silyl group which may have a substituent include a trialkylsilyl group, a dialkylarylsilyl group, an alkyldiarylsilyl group, and a triarylsilyl group. There is no particular limitation on the acid used in the desilylation reaction, and an inorganic acid or an organic acid can be used. There is no particular limitation on the type of inorganic acid, and hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, or the like can be used. There is no particular limitation on the type of organic acid, and acetic acid, trifluoroacetic acid, oxalic acid, citric acid, benzoic acid, chlorobenzoic acid, p-toluenesulfonic acid, or the like can be used.

When Q is a silicon atom or a germanium atom, the compound represented by formula (5C) can be obtained, for example, by treating a bithiophene compound with a base and reacting it with a silyl halide or a germyl halide. As a more specific example, the compound represented by formula (5C) can be obtained by treating 5,5'-bis(trimethylsilyl)-3,3'-dibromo-2,2'-bithiophene with n-butyllithium and reacting it with R ³ R ⁴ SiCl ₂ , R ³ R ⁴ SiBr ₂ , R ³ R ⁴ GeCl ₂ , or R ³ R ⁴ GeBr ₂ . Compounds represented by formula (3C) or (4C) may also be synthesized using R ³ R ⁴ SiCl ₂ , R ³ R ⁴ SiBr ₂ , R ³ R ⁴ GeCl ₂ , or R ³ R ⁴ GeBr _2. In this case, R ³ R ⁴ SiCl ₂ , R ³ R ⁴ SiBr ₂ , R ³ R ⁴ GeCl ₂ , or R ³ R ⁴ GeBr ₂ is preferably purified by vacuum distillation. In order to perform vacuum distillation at an easily achievable reduced pressure and at a lower temperature, the carbon number of R ³ and R ⁴ is preferably 15 or less, more preferably 8 or less.

3. Organic semiconductor ink
The copolymer according to this embodiment has solubility in a solvent and light absorption properties in the long wavelength region, and is suitable for use as an organic semiconductor ink.
An organic semiconductor ink according to one embodiment of the present invention contains at least the copolymer described above. The organic semiconductor ink according to this embodiment may contain one of the copolymers described above, or may contain two or more of them in any combination. The organic semiconductor ink according to this embodiment may consist of only the copolymer described above, but may also contain other components described below within the scope of the effects of the present invention.

The organic semiconductor ink according to this embodiment is suitable as a material for the organic semiconductor layer or organic active layer of an organic electronic device, which will be described later. In this case, it is preferable to form a film of the organic semiconductor ink and use it. In this case, the physical properties of the copolymer, such as its solubility in organic solvents and its excellent processability, are preferably utilized. A method for using the organic semiconductor according to this embodiment in an organic electronic device will be described later.

The content of the above-mentioned p-type semiconductor compound (copolymer) in the organic semiconductor ink according to this embodiment is not particularly limited, but from the viewpoint of dissolving in a non-hazardous and non-halogenated solvent and from the viewpoint of realizing good photoelectric characteristics, it is usually 0.05% by weight or more, preferably 0.1% by weight or more, more preferably 0.3% by weight or more, even more preferably 0.5% by weight or more, and particularly preferably 1.0% by weight or more, and is usually 8% by weight or less, preferably 5% by weight or less, more preferably 4% by weight or less, even more preferably 3% by weight or less, and particularly preferably 2% by weight or less.

The organic semiconductor ink according to this embodiment may contain a compound other than the above-mentioned copolymer as a p-type semiconductor compound. Examples of the compound include
PTB7 (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 ]]),
PTHB7-Th(Poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6 -diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)]),
P3HT (poly-3-hexylthiophene),
PM6 (Poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-al t-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione)]),
Examples of such anti-inflammatory drugs include PTq10 (Poly[[6,7-difluoro[(2-hexyldecyl)oxy]-5,8-quinoxalinediyl]-2,5-thiophenediyl]) and PCDTBT (Poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)]).

The organic semiconductor ink according to this embodiment exhibits semiconductor properties, and for example, in a field effect mobility measurement of its cured product (in this specification, a product that has dried into a film or the like is also referred to as a cured product), the hole mobility (sometimes referred to as Hall mobility) is usually 1.0×10 ^-7 cm ² /Vs or more, preferably 1.0×10 ^-6 cm ² /Vs or more, more preferably 1.0×10 ^-5 cm ² /Vs or more, and particularly preferably 1.0×10 ^-4 cm ² /Vs or more, while the hole mobility is usually 1.0×10 ⁴ cm ² /Vs or less, preferably 1.0×10 ³ cm ² /Vs or less, more preferably 1.0×10 ² cm ² /Vs or less, and particularly preferably 1.0×10 cm ² /Vs or less. An example of a method for measuring hole mobility is the FET method. The FET method can be carried out by the method described in a known document (JP 2010-045186 A).
The viscosity of the ink is not particularly limited and may be appropriately selected according to the application method to be used.

[n-type semiconductor]
The organic semiconductor ink according to this embodiment contains an n-type semiconductor compound having a high electron affinity of 3.5 eV or more. The type of n-type semiconductor compound is not particularly limited, and examples thereof include perylene-bisimide, [6,6]-phenyl-C ₆₁ -butyric acid methyl ester ([60]PCBM), or PCBM having a larger fullerene such as C ₇₀ ,
fullerene derivatives such as [6,6]-phenyl-C ₆₁ -butyric acid n-butyl ester ([60]PCBNB) or PCBNB with larger fullerenes such as C ₇₀ ;
Perylene diimide,
P(NDI2OD-2T): Poly{[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)},
ITIC: 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']dithiophene, or
Y6: 2,2'-((2Z,2'Z)-((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2",3'':4',5']thieno[2',3':4,5]pyrrolo[3,2-g]thi Examples include eno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile.
Among these, PCBM and ITIC,P(NDI20D-2T) are preferred, and PCBM is particularly preferred, from the viewpoint of being non-hazardous and soluble in a non-halogenated solvent, and being able to realize good photoelectric properties. The n-type semiconductor compound may be used alone or in any combination of two or more kinds in any type and ratio.
The n-type semiconductor compound has an electron affinity of 3.5 eV or more in order to receive excited electrons from the p-type semiconductor. From the viewpoint of providing a sufficient driving force for receiving excited electrons, the electron affinity is preferably 3.6 eV or more, more preferably 3.7 eV or more, even more preferably 3.8 eV or more, and particularly preferably 4.0 eV or more. From the viewpoint of preventing spontaneous reception of electrons not due to photoexcitation from the p-type semiconductor and increasing the open circuit voltage when used as an organic solar cell, the electron affinity is preferably 5.0 eV or less, more preferably 4.5 eV or less, even more preferably 4.3 eV or less, and particularly preferably 4.2 eV or less.

The content of the above-mentioned n-type semiconductor compound in the organic semiconductor ink according to this embodiment is not particularly limited, but from the viewpoint of dissolving in a non-hazardous and non-halogenated solvent, and from the viewpoint of realizing good photoelectric characteristics, it is usually 0.2 wt % or more, preferably 0.5 wt % or more, more preferably 1.0 wt % or more, even more preferably 1.5 wt % or more, and particularly preferably 3.0 wt % or more, and is usually 50 wt % or less, preferably 30 wt % or less, more preferably 20 wt % or less, even more preferably 15 wt % or less, and particularly preferably 10 wt % or less.
In the organic semiconductor ink according to this embodiment, the ratio of the content of the n-type semiconductor compound to the content of the p-type semiconductor compound (n-type semiconductor compound/p-type semiconductor compound) is not particularly limited, but from the viewpoint of realizing good photoelectric characteristics, it is usually 0.5 or more, preferably 0.8 or more, more preferably 1.5 or more, and even more preferably 2.0 or more, in terms of weight ratio, and is usually 10 or less, preferably 8 or less, more preferably 6 or less, and even more preferably 4 or less.

Regarding the measurement of electron affinity, either the known method of indirectly determining it from cyclic voltammetry and optical band gap, or the method of directly determining it using inverse electron spectroscopy, will give roughly equivalent values, but in this invention, the method of determining it from cyclic voltammetry and optical band gap is used. Alternatively, the LUMO energy level relative to the vacuum level can be used as a simple substitute.

[solvent]
The organic semiconductor ink according to this embodiment includes a solvent. The solvent used in this embodiment includes an anisole derivative in which a halogen group is not directly bonded to the benzene ring, and is excellent in terms of ensuring worker safety and reducing environmental burden. The type of anisole derivative in which a halogen group is not directly bonded to the benzene ring is not particularly limited, but from the viewpoint of ensuring worker safety and reducing environmental burden, an anisole derivative that does not have a halogen group is preferable, and specifically, 2-methylanisole, 3-methylanisole, 4-methylanisole, 2-ethylanisole, 3-ethylanisole, 4-ethylanisole, 2,3-dimethylanisole, 2,4-dimethylanisole, 2,5-dimethylanisole, 2,6-dimethylanisole, 3,4-dimethylanisole, and 3.5-dimethylanisole are preferable, and 2-methylanisole is particularly preferable. The anisole derivative may be used alone or in combination of two or more kinds in any type and ratio.

The organic semiconductor ink according to this embodiment may contain a solvent other than anisole derivatives in which a halogen group is not directly bonded to the benzene ring, such as 1,4-dioxane, acetone, and ethylbenzene. From the viewpoint of ensuring worker safety and reducing environmental impact, it is preferable that the above-mentioned anisole derivatives do not have a halogen group, it is more preferable that the compound contained as the solvent does not have a halogen group, and it is even more preferable that the organic semiconductor ink according to this embodiment does not contain a compound having a halogen group.

The boiling point of the above anisole derivative is 150°C or higher from the viewpoint of achieving good coating properties, drying properties, and photoelectric conversion properties, but is preferably 155°C or higher, more preferably 160°C or higher, and even more preferably 170°C or higher, and is preferably 300°C or lower, more preferably 250°C or lower, and even more preferably 200°C or lower.

From the viewpoints of ensuring worker safety and reducing environmental impact, it is preferable that the solvent is substantially free of compounds containing halogen elements (below the detection limit).

The content of the solvent in the organic semiconductor ink according to this embodiment is not particularly limited, but from the viewpoint of improving ease of handling, it is usually 10% by weight or more, preferably 40% by weight or more, more preferably 60% by weight or more, even more preferably 80% by weight or more, and particularly preferably 90% by weight or more, and is usually 99.9% by weight or less, preferably 99.5% by weight or less, more preferably 97% by weight or less, even more preferably 96% by weight or less, and particularly preferably 95% by weight or less.

The content of the anisole derivative having no halogen group directly bonded to the benzene ring in the organic semiconductor solvent according to this embodiment is not particularly limited, but from the viewpoint of ease of handling, it is usually 10% by weight or more, preferably 40% by weight or more, more preferably 50% by weight or more, even more preferably 60% by weight or more, and particularly preferably 70% by weight or more, and is usually 99% by weight or less, preferably 96% by weight or less, more preferably 94% by weight or less, even more preferably 92% by weight or less, and particularly preferably 90% by weight or less.
From the viewpoints of ensuring the safety of workers and reducing the environmental load, the concentration of halogen as an impurity in the solvent is preferably 1% by weight or less, more preferably 0.1% by weight or less, more preferably 0.01% by weight or less, and particularly preferably substantially 0% by weight (below the detection limit).

In the organic semiconductor ink according to this embodiment, the ratio of the content of the anisole derivative in which a halogen group is not directly bonded to the benzene ring to the content of the p-type semiconductor compound (anisole derivative in which a halogen group is not directly bonded to the benzene ring/p-type semiconductor compound) is not particularly limited, but from the viewpoint of improving ease of handling and realizing good photoelectric characteristics, the weight ratio is usually 1 or more, preferably 10 or more, more preferably 30 or more, and even more preferably 50 or more, and is usually 1000 or less, preferably 500 or less, more preferably 200 or less, and even more preferably 100 or less.

[Other ingredients]
The organic semiconductor ink according to this embodiment may further contain components other than the above-mentioned p-type semiconductor, n-type semiconductor, and solvent (also referred to as "other components" or "additives") within the range in which the effects of the present invention can be obtained, such as polymers or monomers other than the polymers or monomers related to the above-mentioned copolymers, thickeners, morphology adjusters, oxidizing agents, reducing agents, heat curing agents, photocuring agents, etc. One type of other component may be used alone, or two or more types may be used in combination in any type and ratio.
The morphology control agent may be selected from aromatic (tetralin, diphenyl ether, etc.), non-aromatic (1,8-diiodooctane, 2-methyltetrahydrofuran, etc.) or solid (polymers such as polystyrene and polydimethylsiloxane) in consideration of the fact that it has a higher boiling point than the main solvent, that it has liquid or similar fluidity during coating and drying, and that it has higher solubility in n-type semiconductors than p-type semiconductors, and from the viewpoint of forming an appropriate phase-separated structure between the p-type semiconductor and the n-type semiconductor when the ink is coated and dried, it is preferable that the agent contains, for example, an aromatic hydrocarbon or an alkyl halide. The type of aromatic hydrocarbon or alkyl halide is not particularly limited, and examples include tetralin, 1,8-diiodooctane, ditolyl ether, diphenyl ether, polystyrene, etc., but from the viewpoint of the solubility of n-type semiconductors, it is preferable that the agent is tetralin or 1,8-diiodooctane.
The melting point of the aromatic hydrocarbon or alkyl halide is not particularly limited, but from the viewpoint of exhibiting a morphology control function as a liquid during coating and drying, it is usually −100° C. or higher, more preferably −50° C. or higher, and even more preferably −20° C. or higher, and is usually 100° C. or lower, preferably 75° C. or lower, more preferably 50° C. or lower, and even more preferably 25° C. or lower.
The boiling point of the aromatic hydrocarbon or alkyl halide is not particularly limited, but from the viewpoint of evaporating slower than the solvent during coating and drying and thereby exhibiting a morphology control function, it is preferably higher than the boiling point of the solvent; specifically, it is usually 50° C. or higher, preferably 100° C. or higher, more preferably 150° C. or higher, and even more preferably 200° C. or higher, and is usually 400° C. or lower, preferably 350° C. or lower, more preferably 300° C. or lower, and even more preferably 280° C. or lower.

4. Electronic device containing organic semiconductor material obtained by using the ink of the present invention
Next, an organic electronic device according to another embodiment of the present invention will be described. The organic electronic device according to this embodiment is produced using the organic semiconductor ink described above. That is, the organic electronic device according to this embodiment includes (or is equipped with) the organic semiconductor ink described above or a cured product thereof. There is no particular limitation on the type of organic electronic device according to this embodiment as long as the organic semiconductor ink can be applied. Examples include a light-emitting element, a switching element, a photoelectric conversion element, and a photosensor utilizing photoconductivity, and an organic photodiode can be preferably used as an example of a photoelectric conversion element.

The form of the cured organic semiconductor ink is not particularly limited, but from the viewpoint of being usable as an active layer in a photoelectric conversion element described later, a sheet or film shape is preferable, and from the viewpoint of obtaining sufficient light absorbance at the target absorption wavelength and transporting the charge generated by photoelectric conversion to the electrode without deactivating it, the thickness in this case may be, for example, 10 nm or more and 2000 nm or less, preferably 50 nm or more and 1000 nm or less, and more preferably 100 nm or more and 600 nm or less.

There are no particular limitations on the method for obtaining a cured product of the organic semiconductor ink, and examples of the method include a method in which the organic semiconductor ink is cured by removing the solvent by natural drying or heating without using a curing agent, a method in which the organic semiconductor ink is cured by reacting the contained components without using a curing agent, and a method in which the organic semiconductor ink contains a heat curing agent or a light curing agent and is cured by heating or irradiating light.
When curing is performed by removing the solvent by heating without using a curing agent, the heating conditions can be appropriately set depending on the components contained, particularly the type of the solvent. The heating temperature may be, for example, 40° C. or higher and 300° C. or lower, or may be 100° C. or higher and 200° C. or lower, and the heating time may be, for example, 1 minute or longer and 72 hours or shorter, or may be 5 minutes or longer and 10 hours or shorter.
When a heat curing agent is used, the heating conditions are not particularly limited, and the heating temperature may be, for example, 40° C. or more and 300° C. or less, or may be 100° C. or more and 200° C. or less, and the heating time may be, for example, 1 minute or more and 72 hours or less, or may be 5 minutes or more and 10 hours or less.
When using a photocuring agent, the heating conditions are not particularly limited, and the type of light that can be used is, for example, gamma rays, X-rays, ultraviolet rays, visible light, or infrared rays, and the light irradiation time can be, for example, from 5 seconds to 72 hours, and can also be from 1 minute to 10 hours.

Examples of the light-emitting element include various light-emitting elements used in display devices, such as a liquid crystal display element, a polymer-dispersed liquid crystal display element, an electrophoretic display element, an electroluminescent element, and an electrochromic element.
Specific examples of switching elements include diodes (pn junction diodes, Schottky diodes, MOS diodes, etc.), transistors (bipolar transistors, field effect transistors (FETs), etc.), thyristors, and further composite elements thereof (e.g., TTL, etc.).

Specific examples of the photoelectric conversion element include a thin-film solar cell, a charge-coupled device (CCD), a photomultiplier tube, a photocoupler, etc. Examples of optical sensors that utilize photoconductivity include those that utilize these photoelectric conversion elements.
There is no particular restriction on which part of an organic electronic device the organic semiconductor ink or its cured product is used in, and it can be used in any part. In order to utilize the semiconductor properties of the organic semiconductor ink, it is preferable to use the organic semiconductor ink or its cured product in the semiconductor layer of an organic electronic device. In particular, in the case of a photoelectric conversion element, the organic semiconductor layer containing the organic semiconductor ink according to the present invention or its cured product is usually used as an organic active layer.

<5. Photoelectric conversion element>
A photoelectric conversion element obtained by using the above organic semiconductor ink is another embodiment of the present invention, and is a photoelectric conversion element comprising a pair of electrodes and an active layer disposed between the electrodes, the active layer comprising a cured product of the organic semiconductor ink containing the above copolymer.

[5-1. Configuration of photoelectric conversion element]
FIG. 1 shows an example of a photoelectric conversion element according to this embodiment. The photoelectric conversion element shown in FIG. 1 is a photoelectric conversion element used in a general organic thin-film solar cell, but the photoelectric conversion element according to this embodiment is not limited to the one shown in FIG. 1. The photoelectric conversion element 107 as an example of this embodiment has a layer structure including a base material 106, an anode 101, a hole extraction layer 102, an active layer 103 (a mixed layer of a p-type semiconductor material (compound) and an n-type semiconductor material (compound)), an electron extraction layer 104, and a cathode 105. Note that FIG. 1 shows an example of a photoelectric conversion element in which each layer is stacked in the above-mentioned order, but the photoelectric conversion element 107 may have a structure having a base material 106, a cathode 105, an electron extraction layer 104, an active layer 103, a hole extraction layer 102, and an anode 101 in this order. In addition, the active layer 103 may have a structure in which a p-type semiconductor material and an n-type semiconductor material are stacked. Furthermore, the hole extraction layer 102 and the electron extraction layer 104 are not essential components and may be provided as an option.

The layer structure of the active layer 103 is preferably a mixed layer of p-type semiconductor material and n-type semiconductor material (sometimes called bulk heterojunction type), but other structures are also possible. For example, it may be a thin-film laminate type in which p-type semiconductor material and n-type semiconductor material are laminated, or a structure having a mixed layer (i-layer) of p-type semiconductor material and n-type semiconductor material in the intermediate layer of the thin-film laminate type. It is preferable to use the above-mentioned copolymer as the compound contained in the p-type semiconductor material of the active layer 103. It is also preferable to use the above-mentioned organic semiconductor ink or its cured product as the active layer 103.

In addition, other layers may be inserted between each layer of the photoelectric conversion element 107 to the extent that they do not affect the function of each layer described below.

The substrate 106, the anode 101, the hole extraction layer 102, the n-type semiconductor material of the active layer 103, the electron extraction layer 104, and the cathode 105 may be formed using known materials and methods. Specifically, they are as described in Solar Energy Materials & Solar Cells 96 (2012) 155-159, International Publication No. 2011/016430, or Japanese Patent Application Laid-Open No. 2012-191194. In addition to the copolymer, the p-type semiconductor material of the active layer 103 may also be used in combination with a p-type semiconductor material (compound) other than the copolymer as described in the above-mentioned known document. The preferred film thicknesses of the layers constituting the substrate 106 and the photoelectric conversion element 107 are also as described in the above-mentioned known document. Among the materials described in the above-mentioned known document, the preferred materials for the layers constituting the substrate 106 and the photoelectric conversion element are described below.

Examples of the substrate 106 include inorganic material substrates such as glass substrates, plastic substrates such as polyethylene terephthalate, polyethylene naphthalate, and polyimide, substrates made of paper materials such as paper or synthetic paper, and substrates made of composite materials such as metals such as stainless steel, copper, titanium, and aluminum whose surfaces are coated or laminated to provide insulation. In terms of obtaining a light-weight and flexible photoelectric conversion element, it is preferable to use a plastic substrate or a substrate made of a composite material as the material for the substrate 106.

Cathode 105 can be, among others, indium tin oxide (ITO), silver, copper, aluminum, etc.

The electron extraction layer 104 may be made of either an inorganic or organic compound, but titanium oxide (TiOx) or zinc oxide (ZnO) are preferred because of their excellent film formation stability and the potential for reduced production costs.

The n-type semiconductor compound of the active layer 103 is not particularly limited in terms of the LUMO energy level, but is preferably a material whose value relative to the vacuum level calculated by, for example, cyclic voltammogram measurement is usually -4.0 eV or more, preferably -3.9 eV or more. Since the open circuit voltage (Voc) depends on the difference between the HOMO energy level of the p-type semiconductor compound and the LUMO energy level of the n-type semiconductor compound, increasing the LUMO energy level of the n-type semiconductor compound tends to increase Voc. On the other hand, if the LUMO energy level is too high, electron transfer from the p-type semiconductor compound becomes difficult, so the LUMO energy level is usually -1.0 eV or less, preferably -2.0 eV or less, more preferably -3.0 eV or less, and even more preferably -3.3 eV or less. By having the LUMO energy level of the n-type semiconductor compound in the above range, the open circuit voltage (Voc) and short-circuit current density (Jsc) can be increased simultaneously.

The HOMO energy level of an n-type semiconductor compound is not particularly limited, but is usually -5.0 eV or less, preferably -5.5 eV or less. On the other hand, it is usually -7.0 eV or more, preferably -6.6 eV or more. The HOMO energy level of an n-type semiconductor compound is -7.0 eV or more, which is preferable because the light absorption of the n-type semiconductor compound can also be used for power generation. The HOMO energy level of an n-type semiconductor compound is -5.0 eV or less, which is preferable because the reverse movement of holes can be prevented.

The electron mobility of the n-type semiconductor compound is not particularly limited, but is usually 1.0×10 ⁻⁶ cm ² /Vs or more, preferably 1.0×10 ⁻⁵ cm ² /Vs or more, more preferably 5.0×10 ⁻⁵ cm ² /Vs or more, and even more preferably 1.0×10 ⁻⁴ cm ² /Vs or more. On the other hand, it is usually 1.0×10 ⁴ cm ² /Vs or less, preferably 1.0×10 ³ cm ² /Vs or less, and more preferably 5.0×10 ² cm ² /Vs or less. The electron mobility of the n-type semiconductor compound is preferably in the above range in that the effect of improving the conversion efficiency can be obtained in combination with the above copolymer. The method for measuring the electron mobility includes the FET method, and can be carried out by the method described in the known literature (JP 2010-045186 A).

Specifically, fullerene derivatives having a substituent are preferred because they are easy to form an ideal phase-separated structure with the above-mentioned copolymer, and PCBM is particularly preferred.

The hole extraction layer 102 is preferably a material having a Fermi level of -5.0 eV or less (or a work function of 5.0 eV or more), although this is not limited thereto. More preferably, the Fermi level is -5.1 eV or less (work function of 5.1 eV or more), and particularly preferably, the Fermi level is -5.2 eV or less (work function of 5.2 eV or more). By having the Fermi level (or work function) in the above range, it becomes easier to extract holes from the copolymer, and a photoelectric conversion element having excellent photoelectric conversion efficiency and durability can be provided. There are no particular limitations as long as the material satisfies such conditions, but examples include conductive polymers in which polythiophene, polypyrrole, polyacetylene, triphenylenediamine, polyaniline, etc. are doped with sulfonic acid and/or iodine, polythiophene derivatives having sulfonyl groups as substituents, conductive organic compounds such as arylamines, and metal oxides such as molybdenum trioxide. are preferred.

There are no particular limitations on the anode 101, and it is possible to use conductive metal oxides such as indium tin oxide (ITO), metals such as silver, gold, platinum, chromium, or cobalt, or alloys thereof.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as they do not exceed the gist of the invention.

<Experiment 1: Evaluation of solubility>
The compound D1 shown below (manufactured by Mitsubishi Chemical Corporation) was used as an anisole compound. The weight average molecular weight of D1 shown below is 299,000, the polydispersity index (PDI) is 4.5, m is 0.6, and n is 0.4.

Example 1
The above D1 was dissolved in 2-methylanisole (Tokyo Chemical Industry Co., Ltd.) and heated at 120° C. for 2 hours to obtain a 8 mg/mL solution. This solution was left to stand at 80° C. and 60° C. for 1 hour each, and the solubility of D1 was visually observed. The observation results are shown in Table 1.

Example 2
The solubility was observed in the same manner as in Example 1, except that the solvent was changed to p-bromoanisole (Tokyo Chemical Industry Co., Ltd.). The observation results are shown in Table 1.

(Comparative Example 1)
The solubility was observed in the same manner as in Example 1, except that the solvent was changed to chlorobenzene (Aldrich). The observation results are shown in Table 1.

(Comparative Example 2)
The solubility was observed in the same manner as in Example 1, except that the solvent was changed to p-cymene. The results are shown in Table 1.

(Comparative Example 3)
The solubility was observed in the same manner as in Example 1, except that the solvent was changed to ethylbenzene (Tokyo Chemical Industry Co., Ltd.). The observation results are shown in Table 1.

(Comparative Example 4)
The solubility was observed in the same manner as in Example 1, except that the solvent was changed to terpinolene (Tokyo Chemical Industry Co., Ltd.). The observation results are shown in Table 1.

From Table 1, at 60°C, the anisole derivatives of Examples 1 and 2 and the chlorobenzene of Comparative Example 1 showed good solubility, but the solubility in aromatic hydrocarbons without heteroatoms of Comparative Examples 2 to 4 was poor. Furthermore, at 80°C, the anisole derivatives of Examples 1 and 2 showed good solubility, but the solubility in chlorobenzene of Comparative Example 1 and the aromatic hydrocarbons without heteroatoms of Comparative Examples 2 to 4 was poor.

<Experiment 2: Evaluation of photoelectric conversion element>
[Evaluation method]
The performance of the organic photodiodes manufactured in the following Examples and Comparative Examples was measured as follows.

Using a PEC-S20 action spectrum measuring device manufactured by Peccell Technology and a Tektronix Keithley 2400 source meter, the external quantum efficiency was obtained when incident light with a wavelength of 700 nm was irradiated and a voltage of -5 V was applied to the element.
In the measurement, light was incident from the ITO substrate side.

Example 3
An organic photodiode was fabricated by the following method.
A transparent conductive film of indium tin oxide (ITO) having a thickness of 70 nm was patterned on a glass substrate as an electrode. The surface of the ITO substrate was treated with an ultraviolet ozone cleaner (NL-UV253, manufactured by Japan Laser Electronics Co., Ltd.) for 10 minutes, and then a hole transport layer was formed as follows.
A composition for forming a hole transport layer was prepared by dissolving 60 mg of a polymer (Mw=64,000, Mn=43,000, Mw/Mn=1.5) represented by the following formula (H4) in 1 mL of anisole.
In the following formula (H4), Ar in the repeating unit contained in a ratio of 0.95 is a 9,9-di-n-hexyl-2-fluorenyl group described below as 0.95, and is not contained randomly in a ratio of 0.95:0.05. The same applies to the repeating unit of 0.05.
This composition was spin-coated on the electrode surface of an ITO substrate at 1000 rpm for 30 seconds under a nitrogen atmosphere, and then dried by heating at 240° C. for 30 minutes to form a hole transport layer having a thickness of 250 nm. Note that the polymer represented by the following formula (H4) is polymerized even when dried by heating at 230° C., and does not cause any problems even if a subsequent coating step is carried out.

A photoelectric conversion layer (active layer) was formed on this hole transport layer as follows.
8 mg of D1 in the above experiment 1 was mixed with mixPCBM (Frontier Carbon, [C
A mixture of 20 mg of [C60]PCBM:[C70]PCBM=1:3 (weight ratio) was mixed, 1.0 mL of 2-methylanisole (Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was heated at 110° C. for 4 hours. While still heated, the mixture was passed through a 5.0 μm PTFE filter to obtain photoelectric conversion ink 1.
This ink 1 was heated to 60° C. and spin-coated at 1000 rpm onto the substrate coated with HTL, and after spin-coating, the element was heated in nitrogen at 120° C. for 10 minutes to obtain a photoelectric conversion layer of 300 nm. A 40 nm film of fullerene (manufactured by Frontier Carbon) and a 100 nm film of aluminum were then formed on the layer using a vacuum deposition apparatus to obtain photoelectric conversion element 1.

(Comparative Example 5)
8 mg of D1 and 20 mg of mixPCBM from the above Experiment 1 were mixed, 1.0 mL of p-bromoanisole was added, and the mixture was heated at 110° C. for 4 hours. While still heated, the mixture was passed through a 5.0 μm PTFE filter to obtain photoelectric conversion ink 2.
Photoelectric conversion element 2 was produced in the same manner as in Example 3, except that ink 2 was used.

(Comparative Example 6)
12 mg of D1 and 30 mg of mixPCBM from Experiment 1 above were mixed, 0.9 mL of xylene (Kanto Chemical) and 0.1 mL of tetralin (Aldrich) were added, and the mixture was heated at 110° C. for 4 hours. While still heated, the mixture was passed through a 1.0 μm PTFE filter to obtain photoelectric conversion ink 3.
Photoelectric conversion element 3 was produced in the same manner as in Example 3, except that ink 3 was used.

As seen from Table 2, it is clear that, among the anisole derivatives, p-bromoanisole having one halogen group on the aromatic ring does not give a good photoelectric conversion film.
It was also revealed that ink 1 using 2-methylanisole gave photoelectric conversion characteristics equivalent to those of ink 3 which mainly contained xylene, a deleterious reagent generally used in organic photoelectric conversion inks.

<Experiment 3: Additives>
Example 4
10 mg of D1 in the above Experiment 1 was mixed with 25 mg of mixPCBM, 0.9 mL of 2-methylanisole and 0.1 mL of tetralin (manufactured by Aldrich) as an additive were added, and the mixture was heated at 110° C. for 4 hours. While still heated, the mixture was passed through a 1.0 μm PTFE filter to obtain photoelectric conversion ink 4.
Photoelectric conversion element 4 was produced in the same manner as in Example 3, except that this ink 3 was used and that the element was heated in nitrogen at 120° C. for 10 minutes after spin-coating with ink 3.

(Example 5)
10 mg of D1 in the above Experiment 1 was mixed with 25 mg of mixPCBM, and 0.98 mL of 2-methylanisole and 0.02 mL of 1,8-diiodooctane (manufactured by Aldrich) as an additive were added. The mixture was heated at 110° C. for 4 hours, and then passed through a 1.0 μm PTFE filter while still heated to obtain photoelectric conversion ink 5.
Photoelectric conversion element 5 was produced in the same manner as in Example 4, except that ink 5 was used.

As described above, it has become clear that the external quantum efficiency of the photoelectric conversion layer obtained from an organic photoelectric conversion ink containing 2-methylanisole as the main solvent is maintained even when using aromatic hydrocarbons or alkyl halides as liquid additives at room temperature (25°C).

The above examples demonstrate that the present invention can improve the heat resistance and light resistance of a photoelectric conversion element having a hole transport layer containing a polytriamine-based semiconductor compound.

101 Anode 102 Hole extraction layer 103 Active layer 104 Electron extraction layer 105 Cathode 106 Substrate 107 Photoelectric conversion element

Claims (7)

a p-type semiconductor compound which is a copolymer including a repeating unit represented by the following formula (1A), a repeating unit represented by the following formula (1B), and a repeating unit represented by the following formula (1C);
an n-type semiconductor compound having an electron affinity of 3.5 eV or more;
a solvent containing anisole which may have a substituent and has no halogen group directly bonded to the benzene ring;
1. An organic semiconductor ink comprising:

(In formula (1A), formula (1B), and formula (1C), ^A1 and ^A2 each independently represent an atom selected from Group 16 of the periodic table, Q represents an atom selected from Group 14 of the periodic table, ^R1 represents a linear alkyl group which may have a substituent, and ^R2 represents a branched alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or a heterocyclic group which may have a substituent. ^R3 and ^R4 each independently represent a hydrocarbon group which may have a heteroatom.) 2. The organic semiconductor ink according to claim 1, wherein the anisole is selected from the group consisting of 2-methylanisole, 3-methylanisole, 4-methylanisole, 2-ethylanisole, 3-ethylanisole, 4-ethylanisole, 2,3-dimethylanisole, 2,4-dimethylanisole, 2,5-dimethylanisole, 2,6-dimethylanisole, 3,4-dimethylanisole, and 3.5-dimethylanisole. The organic semiconductor ink of claim 2, wherein the anisole is 2-methylanisole. The organic semiconductor ink according to any one of claims 1 to 3, further comprising an aromatic hydrocarbon or an alkyl halide. The organic semiconductor ink according to claim 4, wherein the aromatic hydrocarbon or alkyl halide has a melting point of 25°C or less. 6. The organic semiconductor ink according to claim 4, wherein the boiling point of the aromatic hydrocarbon or alkyl halide is equal to or higher than the boiling point of the solvent. The organic semiconductor ink according to any one of claims 4 to 6, wherein the aromatic hydrocarbon or alkyl halide is tetralin or 1,8-diiodooctane.

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