Organic semiconductor ink

Abstract

To provide an organic semiconductor ink that can achieve excellent photoelectric properties while using a solvent that is free from deleterious substances and halogens.SOLUTION: An organic semiconductor ink comprises: a p-type semiconductor compound, as a copolymer that comprises a repeat unit of a heterocyclic compound comprising a nitrogen atom and a repeat unit of a heterocyclic compound comprising a sulfur atom; an n-type semiconductor compound having an electron affinity of 3.5 eV or more; and an anisole derivative comprising a benzene ring with no direct bond with a halogen group.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention mainly relates to organic semiconductor ink.

Background Art

[0002] Many of the organic semiconductor inks used for forming a bulk heterojunction (BHJ) type photoelectric conversion layer such as an organic solar cell or an organic photodetector use a halogen solvent such as chloroform or chlorobenzene, or an aromatic solvent specified as an external medicine for pharmaceuticals such as toluene or xylene even in a non-halogen solvent. Therefore, there have been problems from the viewpoints of ensuring the safety of workers and environmental load. For this reason, various non-halogen and non-drug solvents have been studied for organic semiconductor inks. Patent Documents 1 and 2 disclose examples of using a non-drug and non-halogen solvent such as pseudocumene together with o-xylene or the like 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 a main solvent of 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 terpirenone as a main solvent of an organic semiconductor ink for a photoelectric conversion layer containing PTB7-Th.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] It is extremely difficult to analogize a suitable solvent for an ink containing an organic semiconductor composition for an arbitrary photoelectric conversion layer from the above-mentioned literature and the like. This is because the solubility in various solvents varies not only depending on the organic semiconductor and its molecular weight, but also because in order to form a BHJ-type photoelectric conversion layer having high photoelectric conversion efficiency, it is essential to form a nanostructure in which p-type and n-type organic semiconductors are intertwined co-continuously during coating and drying. For the formation of this structure, many factors such as the difference in solubility between p-type and n-type organic semiconductors and the drying rate are involved in addition to solubility. That is, in order to realize good optoelectronic properties, it is important to select not only a semiconductor compound but also 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 these components, and there is still room for study, especially for combinations when using a non-toxic and non-halogenated solvent as the solvent. Therefore, an object of the present invention is to provide an organic semiconductor ink capable of realizing good optoelectronic properties while using a non-toxic and non-halogenated solvent.

Means for Solving the Problems

[0006] As a result of intensive studies to solve the above problems, the present inventors have found that by using a p-type semiconductor compound which is a copolymer having a specific structure and an n-type semiconductor compound having specific properties as semiconductor compounds, it is possible to realize good optoelectronic properties while using a non-toxic and non-halogenated solvent and have found that an organic semiconductor ink can be provided, thus completing the present invention.

[0007] Embodiments of the present invention include, but are not limited to, the following. [1] A p-type semiconductor compound that is a copolymer containing a repeating unit represented by the following formula (1A), a repeating unit represented by 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 the benzene ring, and an organic semiconductor ink containing the same. [Chemical formula] (In formula (1A), formula (1B), and formula (1C), A 1 and A 2 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, R 1 represents a linear alkyl group which may have a substituent, R 2 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. R 3 and R 4 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 a halogenated alkyl. [5] The organic semiconductor ink according to [4], wherein the melting point of the aromatic hydrocarbon or the halogenated alkyl is 25°C or lower. [6] The organic semiconductor ink according to [4] or [5], wherein the boiling point of the aromatic hydrocarbon or the halogenated alkyl 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 the halogenated alkyl is tetralin or 1,8-diiodooctane.

Advantages of the Invention

[0008] According to the present invention, it is possible to provide an organic semiconductor ink that can achieve good optoelectronic properties while using a non-toxic and non-halogenated solvent.

Brief Description of the Drawings

[0009]

Figure 1

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the present invention will be described in detail. The following description is an example (representative example) of the present invention, and the present invention is not limited thereto. Further, the present invention can be arbitrarily modified and implemented without departing from the gist thereof. In this specification, the description represented by "~" represents a range including the numbers described before and after it. In addition, "independently" used when explaining two or more objects together means that these two or more objects may be the same or different.

[0011] <1.p-type semiconductor compound> The copolymer, which is a p-type semiconductor compound in the organic semiconductor ink according to an embodiment of the present invention (hereinafter, also simply referred to as "copolymer"), includes 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 the present embodiment is less likely to gel when dissolved, and thus is suitable for coating and film formation. Further, the copolymer according to the present embodiment is preferable in that it has a longer light absorption wavelength region, high light absorptivity, and even higher mobility. Further, the copolymer according to the present embodiment is preferable in that it is easy to obtain a high molecular weight one.

[0012]

Chemical formula

[0013] In formula (1A) and formula (1B), A 1 and A 2 each independently represent an atom selected from Group 16 of the periodic table. Specifically, as A 1 and A 2 , an oxygen atom, a sulfur atom, a selenium atom, or a tellurium atom can be mentioned. Among them, from the viewpoint of ease of synthesis, an oxygen atom, a sulfur atom, or a selenium atom is preferable, more preferably a sulfur atom or an oxygen atom, and particularly preferably a sulfur atom. A 1 and A 2 may be the same or different, and are preferably the same.

[0014] In formula (1C), Q represents an atom selected from Group 14 elements of the periodic table. Specifically, as an atom selected from Group 14 elements of the periodic table, a carbon atom, a silicon atom, a germanium atom, a tin atom, or a lead atom can be mentioned. Preferably, Q is a carbon atom, a silicon atom, a germanium atom, or a tin atom, more preferably a carbon atom, a silicon atom, or a germanium atom. Even more preferably, it is a silicon atom or a germanium atom. Since a silicon atom and a germanium atom have a larger atomic radius than a carbon atom, substituents R 3 and R 4Steric hindrance can be reduced. This is preferable in that the intermolecular interaction between the copolymers can be maintained appropriately.

[0015] In formula (1A), R 1 is a linear alkyl group which may have a substituent. It is preferable from the viewpoint of moderately strengthening the interaction between the copolymers. The number of carbon atoms of the linear alkyl group is usually 1 or more, preferably 3 or more, more preferably 4 or more. On the other hand, it is usually 30 or less, preferably 20 or less, more preferably 16 or less, still more preferably 12 or less. That the number of carbon atoms of the linear alkyl group is within the above range is preferable from the viewpoint of improving solubility.

[0016] Examples of the linear alkyl group include a methyl group, n-propyl group, n-butyl group, n-hexyl group, n-octyl group, n-decyl group, n-dodecyl group, n-tetradecyl group, n-hexadecyl group, n-icosyl group, n-tetracosyl group, n-triacontyl group and the like. Among them, preferably, it is an n-butyl group, n-hexyl group, n-octyl group, n-decyl group, n-dodecyl group, n-tetradecyl group, n-hexadecyl group, n-icosyl group, n-tetracosyl group or n-triacontyl group. More preferably, from the viewpoint of maintaining a high solubility of the copolymer and promoting charge transfer without excessively separating the intermolecular distance of the copolymer, it is an n-butyl group, n-hexyl group, n-octyl group, n-decyl group or n-dodecyl group.

[0017] In formula (1B), R 2 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. That R 1 and R 2 are such a combination is considered to be able to suppress a decrease in solubility and gelation caused by the regular orientation of the polymer main chains, and to enhance the ink storage stability. Incidentally, R 2is preferably a branched alkyl group which may have a substituent or an aromatic hydrocarbon group which may have a substituent, more preferably a branched alkyl group which may have a substituent.

[0018] Examples of the branched alkyl group include a branched primary alkyl group, a branched secondary alkyl group, or a branched tertiary alkyl group. The branched primary alkyl group means a branched alkyl group having two hydrogen atoms bonded to a carbon atom having a free valence. The branched secondary alkyl group means a branched alkyl group having one hydrogen atom bonded to a carbon atom having a free valence. The branched tertiary alkyl group means a branched alkyl group having no hydrogen atom bonded to a carbon atom having a free valence. Here, the free valence means one that can form a bond with other free valences as described in the Organic Chemistry and Biochemistry Nomenclature (Part 1) (Revised 2nd Edition, Nankodo, published in 1992).

[0019] Among them, the branched primary alkyl group is preferable in terms of moderately strengthening the intermolecular interaction and improving the mobility, and the branched secondary alkyl group is preferable in terms of improving the solubility. The number of carbon atoms of the branched primary alkyl group is usually 3 or more, preferably 6 or more, more preferably 8 or more, while usually 30 or less, preferably 20 or less, more preferably 16 or less, still more preferably 12 or less. The fact that the number of carbon atoms of the branched primary alkyl group is within the above range is preferable from the viewpoint of improving the solubility.

[0020] Examples of the branched primary alkyl group include 2-ethylhexyl group, 2-methylpropyl group, 2,2-dimethylpropyl group, 2-ethylbutyl group, 2,4-dimethylhexyl group, 2-methylpentyl group, 2,3-dimethylbutyl group, 2-hexyldecyl group, 2,2-dimethylbutyl group, 2-methylheptyl group, 2-butyloctyl group, 2-propylpentyl group, 2-methyloctyl group, 2-methyldodecyl group, 2,5-dimethylhexyl group, and the like.

[0021] Among them, a 2-ethylhexyl group, 2,4-dimethylhexyl group, 2,6-dimethylheptyl group, 2-hexyldecyl group, 2-methylheptyl group, 2-butyloctyl group, 2-propylpentyl group, 2-methyloctyl group, or 2,5-dimethylhexyl group is preferable, and a 2-ethylhexyl group, 2-hexyldecyl group, 2-butyloctyl group or 2-hexyloctyl group is more preferable.

[0022] The number of carbon atoms of the branched secondary alkyl group is usually 3 or more, preferably 4 or more, more preferably 5 or more, while usually 30 or less, preferably 20 or less, more preferably 16 or less, still more preferably 12 or less. It is preferable that the number of carbon atoms of the branched secondary alkyl group is within the above range in terms of improving solubility. Examples of the branched secondary alkyl group include a 1-methylpropyl group, 1-methylheptyl group, 1-ethylhexyl group, 1-methylpentyl group, 1-methyloctyl group, 1-ethylbutyl group, 1-butylheptyl group, 4-methyl-1-propylhexyl group, 1,3-dimethylpentyl group, 1-ethyl-2-methylpentyl group, 1,2-dimethylpentyl group, 1-butylhexyl group, 1,3-dimethyldecyl group, or 1-propylheptyl group.

[0023] Among them, a 1-ethylhexyl group, 1-ethyl-2-methylpropyl group, 1-butylheptyl group, 1-ethyloctyl group, 1-propylhexyl group, 4-ethyl-1-methyloctyl group, 4-methyl-1-propylhexyl group, 1-ethyl-2-methylpentyl group, 1-butylhexyl group or 1-propylheptyl group is preferable. The number of carbon atoms of the branched tertiary alkyl group is usually 4 or more, while usually 30 or less, preferably 20 or less, more preferably 16 or less, still more preferably 12 or less.

[0024] Examples of the branched tertiary alkyl group include a t-butyl group, 2-ethyl-1,1-dimethylpentyl group, 1-ethyl-1,2-dimethylpropyl group, 1,1-dibutyldodecyl group, 1-butyl-1-ethylhexyl group, 1-ethyl-1-propylpentyl group, 1,1-dimethylheptyl group, 1,1-dimethyldecyl group, 1,1-dimethylpentyl group, 1,1-dibutylpentyl group, 1-butyl-1-propylpentyl group, 1-hexyl-1-methylnonyl group, 1-ethyl-1-methylpropyl group, or 1,1,2,2-tetramethylpropyl group, etc. Among them, a t-butyl group or 1,1-dimethylpropyl group is preferable, and a t-butyl group is more preferable.

[0025] The number of carbon atoms of the cycloalkyl group is usually 3 or more, more preferably 4 or more. On the other hand, it is usually 30 or less, preferably 20 or less, more preferably 16 or less, and still more preferably 12 or less. Examples of the cycloalkyl group include a cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclononyl group, cyclodecyl group, or cyclododecyl group, etc. Among them, a cyclopentyl group, cyclohexyl group, cycloheptyl group, or cyclooctyl group is preferable.

[0026] The number of carbon atoms of the aromatic hydrocarbon group is usually 6 or more. On the other hand, it is usually 30 or less, preferably 20 or less, more preferably 14 or less. Examples of such an aromatic hydrocarbon group include a phenyl group, naphthyl group, indanyl group, indenyl group, fluorenyl group, anthracenyl group, or azulhenyl group, etc. Among them, a phenyl group or naphthyl group is preferable. Examples of the heterocyclic group include aliphatic heterocyclic groups and aromatic heterocyclic groups. The number of carbon atoms in the aliphatic heterocyclic group is usually 2 or more, while usually 20 or less, preferably 14 or less, more preferably 12 or less, still more preferably 10 or less, and particularly preferably 6 or less. Examples of such aliphatic heterocyclic groups include an oxetanyl group, a pyrrolidinyl group, a tetrahydrofuryl group, a tetrahydrothienyl group, a piperidinyl group, a tetrahydropyranyl group, or a tetrahydrothiopyranyl group.

[0027] The number of carbon atoms in the aromatic heterocyclic group is usually 2 or more, while usually 30 or less, preferably 20 or less, and 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, or a benzotriazolyl group. Among them, a thienyl group, a pyridyl group , a pyrimidyl group, a thiazolyl group, or an oxazolyl group is preferable. R 1 and R 2 As the "optionally possessed" substituents, there is no particular limitation as long as the effects of the present invention are not impaired, but 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 them, preferably, from the viewpoint of being able to control the intramolecular polarity of the copolymer according to the present embodiment, it is a halogen atom, an alkoxy group, or an alkylthio group.

[0028] R 3 and R 4Each independently represents a hydrocarbon group which may have a heteroatom. Specifically, it represents 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 R 1 and R 2 are synonymous with those defined by. R 3 and R 4 may be the same or different.

[0029] Among them, preferably, at least one of R 3 and R 4 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 R 3 and R 4 are alkyl groups which may have a substituent, still more preferably a branched alkyl group which may have a substituent, and particularly preferably a branched primary alkyl which may have a substituent.

[0030] Also, as another method, since Q becomes an asymmetric atom and the resulting copolymer can have a large number of diastereomers, in terms of improving solubility, R 3 is a linear alkyl group which may have a substituent, and R 4 is a branched alkyl group which may have a substituent is more preferable, and particularly preferably, R 3 is a linear alkyl group which may have a substituent, and R 4 is a branched primary alkyl group which may have a substituent.

[0031] R 3 and R 4 As the "may-have" substituents, R 1 and R 2is synonymous with the "may have" substituent. Among them, a substituent composed of atoms selected from the group consisting of a hydrogen atom and a heteroatom is preferred, and more preferably, a halogen atom such as a fluorine atom 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 a hydrogen bonding ability.

[0032] Also, R 3 and R 4 It is also preferable that at least one of them is a branched alkyl group having no substituent. Particularly preferred are 2-ethylhexyl group, 2-ethylheptyl group, 2-ethyloctyl group, 2-ethylnonyl group or 2-ethyldecanyl group, etc. R 3 and R 4 It is preferable that at least one of R and R contains a branched-chain alkyl group, and it is also preferable from the viewpoint of improving solubility that both are branched-chain alkyl groups.

[0033] In Formula (1A) and Formula (1B), since the substituents of R 1 and R 2 are different, the distance between polymers can be made non-uniform, so the solubility of the copolymer is improved. This is preferable in that the solubility of the copolymer according to the present embodiment in an organic solvent is likely to be improved, and the copolymer according to the present embodiment can be easily coated and formed into a film. Also, when the copolymer according to the present embodiment is made into a solution, precipitation or gelation of the copolymer is suppressed, which is also preferable in terms of improving storage stability.

[0034] The repeating unit having a linear alkyl group on the dioxopyrrole condensed ring and the repeating unit having a branched alkyl group or the like on the dioxopyrrole condensed ring each have a linear substituent It is considered to be a repeating unit having a repeating unit and a substituent having a spatial spread. Therefore, in the copolymer according to this embodiment having the above repeating unit, a portion where the intermolecular distance between the copolymers can be appropriately separated and a portion where they approach each other can coexist, and an irregular distance can be provided between the copolymers. Thus, it is considered that the solubility can be improved.

[0035] Further, since the copolymer of this embodiment has a repeating unit having a linear substituent and a repeating unit having a substituent having a spatial spread, between a dithieno condensed ring and a dioxopyrrole condensed ring, and / or between a plurality of copolymers, the intermolecular interaction between the dithieno condensed rings is appropriately adjusted. Therefore, although it is a high molecular weight substance, at the same time, it becomes a copolymer in which the solubility is improved and the aggregation, crystallization or gelation of the copolymer is suppressed. As a result, it is considered that the stability of the ink containing the copolymer can be improved.

[0036] The copolymer according to this embodiment may contain two or more of each of the repeating unit represented by formula (1A), the repeating unit represented by formula (1B), and the repeating unit 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) as long as the effects of the present invention are not impaired. The total of the repeating unit represented by formula (1A), the repeating unit represented by formula (1B), and the repeating unit represented by formula (1C) in the repeating unit constituting the copolymer according to this embodiment has no particular limitation, but is usually 2 mol% or more, preferably 10 mol% or more, more preferably 25 mol% or more, more preferably 50 mol% or more, still more preferably 70 mol% or more, and even more preferably 90% or more. Particularly preferably, the copolymer according to this embodiment contains the repeating unit represented by formula (1A), the repeating unit represented by formula (1B), and the repeating unit represented by formula (1C) and is composed only of these repeating units, or contains these repeating units and contains a polymer chain composed only of these repeating units.

[0037] The proportion of the repeating unit represented by the formula (1A) in the repeating units constituting the copolymer according to the present embodiment is not particularly limited, but is usually 1 mol% or more, preferably 2 mol% or more, more preferably 10 mol% or more, and still 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.

[0038] The proportion of the repeating unit represented by the formula (1B) 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, 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.

[0039] The proportion of the repeating unit represented by the formula (1C) in the repeating units constituting the copolymer according to the present embodiment is not particularly limited, but is usually 1 mol% or more, preferably 2 mol% or more, more preferably 10 mol% or more, and still 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.

[0040] The number ratio (1C / 1A + 1B) of the repeating unit represented by the formula (1C) to the number of the repeating units represented by the formula (1A) + the formula (1B) in the copolymer according to the present embodiment 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.

[0041] The arrangement state of the repeating units represented by the formula (1A), the formula (1B), and the formula (1C) in the copolymer according to the present embodiment may be either block or random. That is, the present The copolymer according to the embodiment may be either a block copolymer or a random copolymer. Further, a copolymer having an intermediate structure among these copolymers, for example, a random copolymer having a block property, may be used. Further, a copolymer having a branched structure in the main chain and three or more terminal portions, and a dendrimer are also included. Among them, a block copolymer or a random copolymer is preferable in terms of ease of synthesis and further reduction in regularity, and a random copolymer is more preferable in terms of improving the solubility of the copolymer and further improving the storage stability of the ink in which the copolymer is dissolved.

[0042] Among them, the copolymer according to the present embodiment preferably has repeating units represented by the following formulas (2A) and (2B). A copolymer having repeating units represented by the following formulas (2A) and (2B) is preferable in terms of being able to more easily maintain a charge-separated state.

[0043] [Chemical formula]

[0044] In formulas (2A) and (2B), A 1 , A 2 , R 1 ~R 4 have the same meanings as described above. In formulas (2A) and (2B), Q 1 and Q 2 each independently represent an atom selected from Group 14 elements of the periodic table. Q 1 and Q 2 are the same as Q 1 and Q 2 in formulas (1B) and (1C), respectively. R 5 and R 6 each independently represent a hydrocarbon group which may have a hetero atom, and are the same as R 3 and R 4 , respectively.

[0045] The copolymer according to this embodiment may contain two or more of each of the repeating units represented by formula (2A) and the repeating units represented by (2B). The copolymer according to this embodiment may contain repeating units other than the repeating units represented by formula (2A) or (2B) as long as the effects of the present invention are not impaired. The repeating unit represented by formula (2A) and the formula The total proportion of the repeating units represented by (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, still more preferably 70 mol% or more, and even more preferably 90% or more. Particularly preferably, the copolymer according to this embodiment contains the repeating units represented by formula (2A) and the repeating units represented by formula (2B) and is composed only of these repeating units, or contains these repeating units and contains polymer chains composed only of these repeating units.

[0046] The proportion of the repeating unit represented by formula (2A) 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, more preferably 20 mol% or more. On the other hand, it is usually 99 mol% or less, preferably 90 mol% or less, more preferably 70 mol% or less. The proportion of 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 1 mol% or more, preferably 10 mol% or more, more preferably 20 mol% or more. On the other hand, it is usually 99 mol% or less, preferably 90 mol% or less, more preferably 70 mol% or less.

[0047] The number ratio (2A / 2B) of the number of repeating units represented by formula (2A) to the number of repeating units represented by formula (2B) in the copolymer according to this embodiment is not particularly limited, but is usually 0.01 or more, preferably 0.1 or more, more preferably 0.2 or more. On the other hand, it 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 alternating, block, or random. That is, the copolymer according to this embodiment may be any of an alternating copolymer, a block copolymer, or a random copolymer. Further, a copolymer having an intermediate structure among these copolymers, for example, a random copolymer having a certain degree of blockiness, may also be used. Also included are copolymers having a branched main chain and three or more terminal portions, and dendrimers. Among them, a block copolymer or a random copolymer is preferable in terms of ease of synthesis and further possible reduction in regularity, and a random copolymer is more preferable in terms of improving the solubility of the copolymer and the storage stability of the ink in which the copolymer is dissolved.

[0048] Preferable 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.

[0049]

Chemical formula

[0050]

Chemical formula

[0051]

Chemical formula

[0052]

Chemical formula

[0053]

Chemical formula

[0054] The weight-average molecular weight (Mw) in terms of polystyrene 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, still more preferably 5.0×10 4 or more, even more preferably 7.0×10 4 or more, 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, particularly preferably 5.0×10 5 or less. From the viewpoints of shifting the light absorption wavelength to a longer wavelength, realizing a high absorbance, realizing a high carrier mobility, and solubility in an organic solvent, it is preferable that the weight-average molecular weight is within this range.

[0055] The number-average molecular weight (Mn) in terms of polystyrene of the copolymer according to this embodiment is usually 5.0×10 3 or more, preferably 1.0×10 4 or more, more preferably 2.0×10 4 or more, still more preferably 2.5×10 4 or more, 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, still more preferably 5.0×10 5 or less, even more preferably 2.0×10 5 or less, particularly preferably 1.0×10 5 or less. From the viewpoints of shifting the light absorption wavelength to a longer wavelength, realizing a high absorbance, realizing a high carrier mobility, and solubility in an organic solvent, it is preferable that the number-average molecular weight is within this range.

[0056] ​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 still more preferably 1.3 or more. On the other hand, it is preferably 20.0 or less, more preferably 15.0 or less, and still more preferably 10.0 or less. It is preferable that the molecular weight distribution is within this range in that the solubility of the copolymer can be in a range suitable for coating.

[0057] The weight-average molecular weight, number-average molecular weight, and molecular weight distribution of the copolymer according to this embodiment in terms of polystyrene can be determined by gel permeation chromatography (GPC). Specifically, as columns, two Polymer Laboratories GPC columns (PLgel MIXED-B 10 μm inner diameter 7.5 mm, length 30 cm) are connected in series and used. As a pump, LC-10AT (manufactured by Shimadzu Corporation), as an oven, CTO-10A (manufactured by Shimadzu Corporation), as a detector, a differential refractive index detector (manufactured by Shimadzu Corporation: RID-10A), and a UV-vis detector (manufactured by Shimadzu Corporation: SPD-10A) are used for measurement. As a measurement method, the copolymer to be measured (1 mg) is dissolved in chloroform (200 mg), and 1 μL of the obtained solution is injected into the column. Chloroform is used as the mobile phase, and measurement is performed at a flow rate of 1.0 mL / min. LC-Solution (manufactured by Shimadzu Corporation) is used for analysis.

[0058] The copolymer according to this embodiment preferably has an absorption maximum wavelength (λ max ) that is usually 470 nm or more, preferably 480 nm or more, and on the other hand, usually 1200 nm or less, preferably 1000 nm or less, and more preferably 900 nm or less. Also, the half-value 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 on the other hand, usually 300 nm or less. Also, when the copolymer according to this embodiment is used for solar cell applications, the absorption wavelength region of the copolymer is preferably closer to the wavelength region of sunlight.

[0059] The solubility of the copolymer according to this embodiment is not particularly limited, but preferably, the solubility in chlorobenzene at 25°C is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1% by mass or more. On the other hand, it is usually 30% by mass or less, preferably 20% by mass. High solubility is preferable because a thicker film can be formed by coating. It is preferable that moderate intermolecular interactions occur in the copolymer according to this embodiment. In this specification, the term "intermolecular interaction" means that the distance between polymer chains is shortened by interactions such as π-π stacking between molecules. The stronger the interaction, the more likely it is to exhibit high mobility and / or crystallinity, and thus it is considered suitable as a semiconductor material. That is, in a copolymer with intermolecular interactions, intermolecular electron transfer is likely to occur. For example, when the copolymer according to the present invention is used in the active layer of a photoelectric conversion element, 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).

[0060] As a method for measuring crystallinity, X-ray diffraction method (XRD) can be mentioned. In this specification, having crystallinity means that the X-ray diffraction spectrum obtained by XRD measurement has diffraction peaks. Having crystallinity is considered to mean having a stacked structure in which molecules are arranged, and it is preferable in that there is a tendency to be able to thicken the active layer described later. XRD measurement can be performed based on the method described in a known document (Guide to X-ray Crystallography (Selected Books on Applied Physics 4)).

[0061] The hole mobility (sometimes referred to as hole 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, particularly preferably 1.0×10 -4 cm 2is equal to or higher than / Vs. On the other hand, the hole mobility of the copolymer according to the present embodiment is usually 1.0×10 4 cm 2 / Vs or lower, preferably 1.0×10 3 cm 2 / Vs or lower, more preferably 1.0×10 2 cm 2 / Vs or lower, particularly preferably 1.0×10 cm 2 / Vs or lower. Since the hole mobility is within this range, the copolymer according to the present embodiment is suitably used as a semiconductor material. Further, in order to obtain high conversion efficiency in a photoelectric conversion element, it is important to balance the mobility of the n-type semiconductor compound and the mobility of the p-type semiconductor compound. The copolymer according to the present embodiment is used as a p-type semiconductor compound in a photoelectric conversion element, and it is preferable that the hole mobility of the copolymer is within this range from the viewpoint of bringing the hole mobility of the copolymer closer to the electron mobility of the n-type semiconductor compound. Examples of the method for measuring the hole mobility include the FET method. The FET method can be carried out by the method described in a known document (Japanese Patent Application Laid-Open No. 2010-045186).

[0062] On the other hand, it is preferable that the copolymer according to the present embodiment has high storage stability in a solution state. High storage stability means that it is difficult to aggregate when made into a solution. More specifically, when 2 mg of the copolymer according to the present 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 gelation does not occur for 5 minutes or more after the start of cooling, and more preferably gelation does not occur for 1 hour or more.

[0063] It is preferable that the impurities in the copolymer according to this embodiment are as few as possible. In particular, if transition metal catalysts such as palladium and copper remain, exciton traps due to the heavy atom effect of the transition metal will occur, inhibiting charge transfer. As a result, when the copolymer according to the present invention is used in a photoelectric conversion element, the photoelectric conversion efficiency may decrease. The concentration of the transition metal catalyst is usually 1000 ppm or less, preferably 500 ppm or less, more preferably 100 ppm or less per 1 g of the copolymer. On the other hand, it is usually greater than 0 ppm and may be 1 ppm or more, or may be 3 ppm or more.

[0064] There is no particular limitation on the remaining amount of atoms constituting the terminal residues (for example, X and Y in the following formulas (3A) to (3C)) in the copolymer according to this embodiment, but per 1 g of the copolymer, it is usually 6000 ppm or less, preferably 4000 ppm or less, more preferably 3000 ppm or less, still 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. On the other hand, it is usually greater than 0 ppm, preferably 1 ppm or more, and more preferably 3 ppm or more.

[0065] In particular, the remaining 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, still 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 the copolymer. One On the other hand, it is usually greater than 0 ppm, preferably 1 ppm or more, and more preferably 3 ppm or more. The remaining 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 high performance can be obtained in terms of stability.

[0066] In addition, the residual amount of halogen atoms in the copolymer according to the present embodiment is usually 5000 ppm or less, preferably 4000 ppm or less, more preferably 2500 ppm or less, still 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 the copolymer. On the other hand, it is usually greater than 0 ppm, preferably 1 ppm or more, more preferably 3 ppm or more. Setting the residual amount of halogen atoms to 5000 ppm or less is preferable because the performance such as the photoelectric conversion characteristics and durability of the copolymer tends to improve.

[0067] The residual amount of atoms constituting the terminal residues (for example, X and Y in the following formulas (3A) to (3C)) in the copolymer can be determined by measuring the elemental amount. The elemental analysis of the copolymer can be carried out by, for example, ICP mass spectrometry for Pd and Sn, and for bromide ions (Br - ) and iodide ions (I - ), it can also be carried out by ICP mass spectrometry.

[0068] ICP mass spectrometry can be carried out by the method described in a known document ("Plasma Ion Source Mass Spectrometry" (The Society Publishing Center)). Specifically, for Pd and Sn, after wet decomposition of the sample, Pd and Sn in the decomposition solution can be quantified by the calibration curve method using an ICP mass spectrometer (ICP mass spectrometer 7500ce type manufactured by Agilent Technologies). Also, for Br - and I - , the sample is burned in a sample combustion device (sample combustion device QF-02 type manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and the combustion gas is absorbed by an alkaline absorption solution containing a reducing agent. Then, Br in the absorption solution - and I - can be quantified by the calibration curve method using an ICP mass spectrometer (ICP mass spectrometer 7500ce type manufactured by Agilent Technologies).

[0069] <2. Method for manufacturing p-type semiconductor compound> The manufacturing method of the p-type semiconductor (copolymer) according to this embodiment is not particularly limited. For example, it can be manufactured by a known method using a compound having a dioxopyrrole condensed ring and a compound having a dithieno condensed ring. As a preferred method, 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 can be mentioned.

[0070]

Chemical formula

[0071] In formula (3A), R 1 and A 1 are synonymous with those defined in formula (1A). In formula (3B), R 2 and A 2 are synonymous with those defined in formula (1B). In formula (3C), R 3 , R 4 , and Q are synonymous with those defined in formula (1C). In formulas (3A) to (3C), X and Y can be appropriately selected according to the type of polymerization reaction. For example, the copolymer according to the present embodiment can be produced by a polymerization reaction using a coupling reaction. Examples of the 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 FeCl3, 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 is preferable in terms of easy structure control. In particular, the Suzuki-Miyaura cross-coupling reaction method, or the Stille coupling reaction method and the Grignard reaction method are also preferable in terms of easy availability of materials and simplicity of reaction operation. These reactions can be carried out according to the methods described in known documents such as "Cross-Coupling - Basics and Industrial Applications - (CMC Publishing)", "Transition Metal Catalyzed Reactions for Organic Synthesis (by Jiro Tsuji: edited by the Organic Synthesis Chemistry Association)", "Catalytic Reactions for Organic Synthesis 103 (Tamejiro Hiyama: Tokyo Kagaku Dojin)".

[0072] Examples of X and Y include, independently of each other, a halogen atom, an alkylstannyl group, an alkylsulfono group, an arylsulfono group, an arylalkylsulfono group, a borate ester residue, a sulfonium methyl group, a phosphonium methyl group, a phosphonate methyl group, a monohalogenated methyl group, a borate residue (-B(OH)2), a formyl group, a silyl group, an alkenyl group or an alkynyl group, etc.

[0073] As the halogen atom, a bromine atom or an iodine atom is preferable. Examples of the alkenyl group include an alkenyl group having 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.

[0074] [Chemical formula]

[0075] Examples of the alkylstannyl group include those represented by the following formula. In the following formula, Me represents a methyl group and Bu represents an n-butyl group.

[0076] [Chemical formula]

[0077] From the viewpoints of the synthesis of the compounds represented by formulas (3A) to (3C) and the ease of reaction, it is preferable that one of X and Y is a halogen atom and the other is an alkylstannyl group, a borate ester 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 conditions of a known Stille coupling reaction. Also, when X or Y is a borate ester residue or a boric acid residue, the reaction can be carried out according to the conditions of a known Suzuki-Miyaura coupling reaction. Furthermore, when X or Y is a silyl group, the reaction can be carried out according to the conditions of a known Hiyama coupling reaction. As a catalyst for the coupling reaction, for example, a combination of a transition metal such as palladium and a ligand (such as a phosphine ligand such as triphenylphosphine) can be used.

[0078] Hereinafter, a method for producing the copolymer according to the present embodiment using the Stille coupling reaction method will be described. When using the Stille coupling reaction method, in formulas (3A) to (3C), it is preferable that X is a halogen atom and Y is an alkylstannyl group, or X is an alkylstannyl group and Y is a halogen atom. In the polymerization reaction, the total ratio ((3A + 3B) / 3C) of the amount of the compound represented by formula (3C) to the amounts of the compounds represented by formula (3A) and formula (3B) used is usually 0.90 or more, preferably 0.95 or more, and on the other hand, usually 1.3 or less, preferably 1.2 or less, in terms of molar ratio. The fact that the ratio is within such a range is preferable in that a polymer with a higher yield can be obtained.

[0079] In the polymerization reaction, 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 has no particular limitation and can be appropriately set according to the purpose. However, in terms of molar ratio, it is usually 0.01 or more, preferably 0.1 or more, more preferably 0.5 or more. On the other hand, it is usually 100 or less, preferably 10 or less, more preferably 2 or less.

[0080] When it is desired that the copolymer according to this embodiment has high purity, it is preferable to perform the polymerization reaction after purifying the monomers (compounds represented by formulas (3A) to (3C)) before polymerization. Examples of the purification method include distillation, sublimation purification, column chromatography, recrystallization, and the like. For example, when the copolymer according to the present invention is used as a material for an organic optoelectronic conversion element, it is desirable that the copolymer has high purity because the device characteristics can be improved due to its high purity. When the copolymer according to the present invention is used as a material for an organic optoelectronic conversion element, the purity of each of the compounds represented by formulas (3A) to (3C) is usually 90% or more, preferably 95% or more.

[0081] Examples of the catalyst used for promoting polymerization in the polymerization reaction include transition metal catalysts. The transition metal catalyst may be selected according to the type of polymerization. Examples of the transition metal catalyst include homogeneous transition metal catalysts and heterogeneous transition metal catalysts. As the homogeneous transition metal catalyst, those that are sufficiently soluble in the solvent used in the polymerization reaction are preferred. Preferred examples include, in particular, late transition metal complex catalysts containing palladium, nickel, iron, or copper. Specific examples include zerovalent palladium catalysts such as tetrakis(triphenylphosphine)palladium (Pd(PPh3)4) or tris(dibenzylideneacetone)dipalladium (Pd2(dba)3); divalent palladium catalysts such as bis(triphenylphosphine)palladium chloride (PdCl2((PPh3))2) or palladium acetate, etc. (palladium (Pd) catalysts); nickel catalysts such as Ni(dppp)Cl2 or Ni(dppe)Cl2; iron catalysts such as iron chloride; copper catalysts such as copper iodide, etc. Here, dba represents dibenzylideneacetone, dppp represents 1,2-bis(diphenylphosphino)propane, and dppe represents 1,2-bis(diphenylphosphino)ethane.

[0082] Specific examples of the zerovalent Pd catalyst include Pd(PPh3)4, Pd(P(o-tolyl)3)4, Pd(PCy3)2, Pd2(dba)3, or PdCl2(PPh3)2, etc. When using a divalent Pd catalyst such as PdCl2(PPh3)2 or palladium acetate, etc., it is preferably used 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.

[0083] Examples of heterogeneous transition metal catalysts include catalysts obtained by supporting the above-described homogeneous transition metal catalysts on a carrier. Preferred examples of the transition metals contained in the heterogeneous transition metal catalysts include late transition metals containing palladium, nickel, iron, or copper. As the organic ligands of the heterogeneous transition metal complex catalysts, the same ligands as those mentioned for the homogeneous transition metal complex catalysts can be used. Also, organic ligands described in known literature (Strem, "Heterogeneous Catalysts" (2011)) can be used. Examples of the carrier include metals, nanocolloids, nanoparticles, magnetic compounds, metal oxides, porous materials, clays, polymers such as urea resins, and dendrimers. Specific examples of the porous materials include microporous materials, mesoporous materials, activated carbon, silica gel, alumina, and zeolites. In particular, the use of a heterogeneous transition metal complex catalyst supported on a polymer is preferred because the heterogeneous transition metal complex catalyst can be easily recovered. Also, it is more preferred that the polymer is porous in terms of promoting the reaction.

[0084] In the polymerization reaction, it is preferable to use two or more kinds of transition metal complex catalysts in that a high molecular weight copolymer can be obtained. For example, two or more kinds of homogeneous transition metal complexes may be used, two or more kinds of 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 kinds of transition metal complex catalysts, it is preferable that at least one kind is a heterogeneous metal complex catalyst in that the monomer can be quickly converted to an oligomer under the coupling reaction conditions. Also, since the polymerization reaction rate by the heterogeneous metal catalyst tends to decrease when it becomes an oligomer, it is preferable to use a homogeneous metal catalyst to induce the conversion from the oligomer to the polymer in order to obtain a high molecular weight product. From this viewpoint, it is more preferable that among the two or more kinds of transition metal complex catalysts, at least one kind is a heterogeneous metal complex catalyst and at least one kind is a homogeneous metal complex catalyst.

[0085] The addition rate of the transition metal complex relative to the total amount of the compounds represented by formulas (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. On the other hand, it is usually 1×10 2 mol% or less, more preferably 5 mol% or less. The addition rate of the catalyst being within this range is preferable in that a copolymer with a higher molecular weight can be obtained at a lower cost and in a higher yield. When using a transition metal catalyst, an alkali, a cocatalyst or a phase transfer catalyst may be used in combination.

[0086] Examples of the alkali include inorganic bases such as potassium carbonate, sodium carbonate, cesium carbonate; organic bases such as triethylamine; and the like. Examples of the cocatalyst include inorganic salts such as cesium fluoride, copper oxide or copper halide. The addition rate of the cocatalyst is usually 1×10 -4 mol% or more, preferably 1×10 -3 mol% or more, more preferably 1×10 -2 mol% or more with respect to the total amount of the compounds represented by formulas (3A) to (3C). On the other hand, it is usually 1×10 4 mol% or less, preferably 1×10 3 mol% or less, more preferably 1.5×10 2 mol% or less. The addition rate of the cocatalyst being within this range is preferable in that a copolymer can be obtained at a lower cost and in a higher yield.

[0087] Examples of the phase transfer catalyst include quaternary ammonium salts such as tetraethylammonium hydroxide or 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 -2is at least mol%, while usually being 5 mol% or less, more preferably 3 mol% or less. The addition rate of the phase transfer catalyst being within this range is preferable in that a copolymer tends to be obtained at a lower cost and in a higher yield.

[0088] Examples of the solvent 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; aprotic polar organic solvents such as DMF, and the like. These solvents may be used alone or in combination of two or more.

[0089] The addition rate of the solvent is usually 1×10 -2 mL or more, preferably 1×10 -1 mL or more, more preferably 1 mL or more, while usually 1×10 5 mL or less, preferably 1×10 3 mL or less, more preferably 2×10 2 mL or less. The addition rate of the solvent being within this range is preferable in that the reaction control becomes easier.

[0090] 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, it is usually 300°C or lower, preferably 250 It is at or below 0 °C, more preferably at or below 200 °C, still more preferably at or below 180 °C, and particularly preferably at or below 160 °C. There is no particular limitation on the heating method, and examples include oil bath heating, thermocouple heating, infrared heating, microwave heating, and in addition, heating by contact using an IH heater. The polymerization reaction time is usually 1 minute or more, preferably 10 minutes or more. On the other hand, it is usually 160 hours or less, preferably 120 hours or less, and more preferably 100 hours or less. The polymerization reaction is preferably carried out under a nitrogen (N2) 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.

[0091] It is preferable to further perform end treatment on the copolymer obtained by the polymerization reaction. By performing end treatment of the copolymer, the remaining amount of end residues (X and Y described above) of the copolymer can be reduced. For example, when a copolymer is polymerized by a Stille coupling reaction, halogen atoms such as bromine (Br) and iodine (I) and alkylstannyl groups present at the ends of the copolymer can be reduced by end treatment. Performing this end treatment is preferable because a copolymer with better performance can be obtained in terms of efficiency and durability.

[0092] There is no particular limitation on the method for end treatment of the copolymer performed after the polymerization reaction. For example, a method of substituting end residues with other substituents such as aromatic groups can be mentioned. For example, as a method for end treatment when a copolymer is polymerized by a Stille coupling reaction, the following methods can be mentioned. As a method for end treatment of the halogen atoms at the ends of the copolymer, after adding aryltrialkyltin as an end treatment agent to the reaction system before purification after the polymerization reaction, heating and stirring can be carried out. Examples of aryltrialkyltin include phenyltrimethyltin or thienyltrimethyltin. Substituting the halogen atoms at the ends of the copolymer with aromatic groups is preferable because the copolymer becomes more stable due to the conjugated stability effect.

[0093] The amount of the end-capping agent added has no particular limitation, but it is usually 1.0×10 -2 molar equivalents or more, preferably 0.1 molar equivalent or more, more preferably 1 molar equivalent or more, while it 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 end-capping of the halogen atom is usually 0°C or higher, preferably 20°C or higher, more preferably 40°C or higher, still more preferably 60°C or higher. On the other hand, it is usually 300°C or lower, preferably 250°C or lower, more preferably 200°C or lower, still more preferably 180°C or lower, particularly preferably 160°C or lower. As the heating method, there is no particular limitation, and examples include oil bath heating, thermocouple heating, infrared heating, or microwave heating, as well as heating by contact using an IH heater. The reaction time for the end-capping of the halogen atom of the copolymer has no particular limitation, but it is usually 30 minutes or more, preferably 1 hour or more, while it is usually 50 hours or less, preferably 20 hours or less. By carrying out the reaction under these reaction conditions, the end-capping can be performed in a shorter time and with a higher conversion rate.

[0094] Also, as a method for end-capping the alkylstannyl group of the copolymer, it can be carried out by adding an aryl halide as an end-capping agent to the reaction system before purification after the polymerization reaction and then performing heating and stirring. Examples of the aryl halide include iodothiophene, iodobenzene, bromothiophene, or bromobenzene. By substituting the alkylstannyl group at the end of the copolymer with another substituent, the Sn atom in the alkylstannyl group, which is prone to thermal decomposition, no longer exists in the copolymer, and the deterioration of the copolymer over time can be suppressed. Also, substituting the alkylstannyl group at the end of the copolymer with an aryl group is also preferable in that the copolymer can become more stable due to the conjugated stability effect.

[0095] The amount of the end-capping agent added has no particular limitation, but it is usually 1.0×10 -2It is at least a molar equivalent, preferably at least 0.1 molar equivalent, more preferably at least 1 molar equivalent. On the other hand, it is usually at most 50 molar equivalents, preferably at most 20 molar equivalents, more preferably at most 10 molar equivalents. As the reaction temperature and reaction conditions for the end treatment of the alkylstannyl group, the same ones as those for the end treatment of the halogen atom of the copolymer can be used. By carrying out the reaction under these reaction conditions, the end treatment can be carried out in a shorter time and with a higher conversion rate.

[0096] In addition, as methods for end treatment when polymerizing a copolymer by Suzuki-Miyaura cross-coupling reaction, the following methods can be mentioned. As a method for end treatment of the halogen atom of the copolymer, a method of adding arylboronic acid and then performing heating and stirring can be mentioned. As a method for end treatment of the boron atom-containing group of the copolymer, a method of adding an aryl halide as an end treatment agent and then performing heating and stirring can be mentioned.

[0097] There are no particular restrictions on the end treatment method for the terminal residue X and the end treatment method for the terminal residue Y, but it is preferable to carry out each independently. In addition, there are no particular restrictions on the order of each end treatment, and it can be appropriately selected. In addition, the end treatment may be carried out before purification of the copolymer, or may be carried out after purification of the copolymer. When the end treatment is carried out after purification of the copolymer, the copolymer and one end treatment agent (for example, aryl halide or aryltrialkyltin) are dissolved in an organic solvent, and then a transition metal catalyst such as a palladium catalyst is added to carry out the reaction, and then the other end treatment agent (aryl trialkyltin or aryl halide) is added to carry out the reaction. From the viewpoint of promoting the reaction, it is preferable to carry out heating and stirring during the end treatment, as in the case of carrying out the end treatment before purification of the copolymer. Also, from the viewpoint of improving the yield, it is also preferable to carry out 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 on the other hand, is usually 25 hours or less, preferably 10 hours or less.

[0098] The amount of the transition metal catalyst added is not particularly limited, but it is usually 5.0×10 -3 mole equivalents or more, preferably 1.0×10 -2 mole equivalents or more, while usually 1.0×10 -1 mole equivalents or less, preferably 5.0×10 -2 mole equivalents or less, relative to the total amount of the compounds represented by formulas (3A) to (3C). When the addition amount of the catalyst is within this range, terminal treatment can be performed at a lower cost and with a high conversion rate.

[0099] The amount of the terminal treatment agent for the alkylstannyl group during the terminal treatment after copolymer purification is not particularly limited, but it is usually 1.0×10 -2 mole equivalents or more, preferably 1.0×10 -1 mole equivalents or more, more preferably 1 mole equivalent or more, relative to the amount of the monomer (3B and 3C, or 3A) having an alkylstannyl group at the terminal used in the polymerization. While usually 50 mole equivalents or less, preferably 20 mole equivalents or less, more preferably 10 mole equivalents or less. When the addition amount of the terminal treatment agent is within this range, terminal treatment can be performed at a lower cost and with a high conversion rate.

[0100] The amount of the terminal treatment agent for the halogen atom during the terminal treatment after copolymer formation is not particularly limited, but it is usually 1.0×10 -2 mole equivalents or more, preferably 1.0×10 -1 mole equivalents or more, more preferably 1 mole equivalent or more, relative to the amount of the monomer (3A and 3B, or 3C) having a halogen atom at the terminal used in the polymerization. While usually 50 mole equivalents or less, preferably 20 mole equivalents or less, more preferably 10 mole equivalents or less. When the addition amount of the terminal treatment agent is within this range, terminal treatment can be performed at a lower cost and with a high conversion rate.

[0101] The process performed after the polymerization reaction is not particularly limited, but usually a step of separating the copolymer is performed. It is carried out. When performing end treatment of the copolymer, it is preferable to carry out a step of separating the copolymer after the end treatment. If necessary, before the end treatment of the copolymer, separation and purification of the copolymer may be further carried out. From the viewpoint of obtaining the copolymer with shorter processing steps, after the polymerization reaction, it is preferable to carry out end treatment of the copolymer, separation of the copolymer, and purification of the copolymer in this order.

[0102] As a method for separating the copolymer, for example, a method of mixing a reaction solution and a poor solvent to precipitate the copolymer, or a method of quenching active species in the reaction solution with water or hydrochloric acid and then extracting the copolymer with an organic solvent and distilling off this organic solvent can be mentioned. As a method for purifying the copolymer, known methods such as reprecipitation purification, extraction using a Soxhlet extractor, gel permeation chromatography, or metal removal using a scavenger can be mentioned.

[0103] [2-1. Method for producing compounds represented by formulas (3A) to (3C)] The compounds represented by formulas (3A) and (3B) used as raw materials for the polymerization reaction can be produced according to the methods described in J. Am. Chem. Soc., 2010, 132(22), 7595-7597. Also, the compound represented by formula (3C) can be produced according to the methods described in J. Mater. Chem., 2011, 21, 3895, and J. Am. Chem. Soc. 2008, 130, 16144-16145.

[0104] As a particularly preferred method for producing the compound represented by formula (3C), a method using the compound represented by the following formula (4C) as a raw material can be mentioned. More specifically, after reacting the compound represented by formula (4C) with a non-nucleophilic base and then reacting an electrophilic agent, the compound represented by formula (3C) can be obtained. According to this method, the amount of by-products having, for example, only one substituent Y generated when producing the compound represented by formula (3C) can be reduced. The fact that the amount of by-products is small is preferable in that the copolymer according to this embodiment obtained by the polymerization reaction can have a larger molecular weight.

[0105] [Chem.]

[0106] In formula (4C), Q and R 3 ~R 4 are the same as those defined in formula (3C). Examples of the non-nucleophilic base include metal hydrides, metal alkoxides having bulky substituents, amines, phosphazene bases, metal magnesium reagents (Grignard reagents) having bulky substituents, or metal amides. Using a non-nucleophilic base is preferable in that it can effectively suppress the nucleophilic attack on the condensed ring of the compound represented by formula (4C) and can suppress the generation of by-products. From the viewpoints 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.

[0107] After deprotonating the compound represented by general formula (4C) using a non-nucleophilic base, the compound represented by general formula (3C) can be obtained by reacting the generated anion species with an electrophile. When the substituent Y is an alkylstannyl group, the electrophile is not particularly limited, and examples thereof include trialkyltin halide compounds. When the substituent Y is a borate residue or a borate ester residue, the electrophile is not particularly limited, but a trialkyl borate is preferably used. The compound having a borate ester residue obtained by the reaction with the trialkyl borate can be isolated as it is, or the compound may be isolated after hydrolyzing the borate ester residue to lead to a borate residue.

[0108] As a method for purifying the compound represented by the formula (3C) after the reaction, there are no particular limitations, and known methods can be used. Particularly preferred methods include those using zeolite. More specifically, the obtained compound may be brought into contact with zeolite. This method is preferred because the compound can be purified more simply while preventing the 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.

[0109] As a method for bringing the obtained compound represented by the formula (3C) into contact with zeolite, there are mentioned (1) a method of preparing a layer containing zeolite and passing the compound through it, or (2) a method of adding zeolite to the composition and then removing the zeolite, etc. There is no particular limitation on the amount of the non-nucleophilic base added to the compound represented by the formula (4C), and usually a non-nucleophilic base in an amount of 2 molar equivalents or more is used relative to the compound represented by the formula (4C). On the other hand, in order to reduce the amount of the reagent used, the amount of the non-nucleophilic base is usually 20 molar equivalents or less, preferably 10 molar equivalents or less, more preferably 5 molar equivalents or less. There is no particular limitation on the amount of the electrophilic reagent added to the compound represented by the formula (4C), and usually an electrophilic reagent in an amount of 2 molar equivalents or more is used relative to the compound represented by the formula (4C). On the other hand, in order to reduce the amount of the reagent used, the amount of the electrophilic reagent is usually 20 molar equivalents or less, preferably 10 molar equivalents or less, more preferably 5 molar equivalents or less.

[0110] The compound represented by the formula (4C) can be produced using known methods, but it is particularly preferred to produce it using the method shown below. That is, the compound represented by the formula (4C) can be obtained by eliminating the silyl group from the compound to which the silyl group is added in the compound represented by the formula (4C). This method is preferred in that the compound represented by the formula (4C) can be obtained in a higher yield.

[0111] For example, the compound represented by formula (4C) can be produced by a desilylation reaction of the compound represented by the following formula (5C) using an acid.

[0112]

Chemical formula

[0113] In formula (5C), Q and R 3 ~R 4 are the same as those defined in formula (3C). In (5C), R 5 ~R 6 represents 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, or a triarylsilyl group. The acid used in the desilylation reaction is not particularly limited, 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, etc. 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, etc. can be used.

[0114] When Q is a silicon atom or a germanium atom in the compound represented by formula (5C), for example, it can be obtained by treating a bithiophene compound with a base and reacting it with a silyl halide or a germyl halide. As a more specific example, 5,5'-bis(trimethylsilyl)-3,3'-dibromo-2,2'-bithiophene is treated with n-butyllithium, and R 3 R 4 SiCl2, R 3 R 4 SiBr2, R 3 R 4 GeCl2, or R 3 R 4 ​By reacting GeBr2, a compound represented by formula (5C) can be obtained. Also, the compound represented by formula (3C) or (4C) can also be synthesized using R 3 R 4 SiCl2, R 3 R 4 SiBr2, R 3 R 4 GeCl2, or R 3 R 4 GeBr2. In this case, R 3 R 4 SiCl2, R 3 R 4 SiBr2, R 3 R 4 GeCl2, or R 3 R 4 GeBr2 is preferably purified by vacuum distillation. In order to perform vacuum distillation at an easily achievable degree of reduced pressure and at a lower temperature, the number of carbon atoms of R 3 and R 4 is preferably 15 or less, and more preferably 8 or less.

[0115] <3. Organic Semiconductor Ink> The copolymer according to this embodiment has solubility in a solvent and light absorbency in the long wavelength region, and is suitable as an organic semiconductor ink. The organic semiconductor ink according to one embodiment of the present invention contains at least the above copolymer. The organic semiconductor ink according to this embodiment may contain one of the above copolymers, or may contain two or more of them in any combination. Further, the organic semiconductor ink according to this embodiment may consist only of the above copolymer, but may also contain other components described later as long as the effects of the present invention can be obtained.

[0116] The organic semiconductor ink according to this embodiment is suitable as a material for an organic semiconductor layer or an organic active layer of an organic electronic device described later. In this case, it is preferable to form a film using the organic semiconductor ink. At this time, physical properties such as excellent solubility of the above copolymer in an organic solvent and its processability are preferably utilized. A method for using the organic semiconductor according to this embodiment in an organic electronic device will be described later.

[0117] The content of the above p-type semiconductor compound (copolymer) in the organic semiconductor ink according to this embodiment is not particularly limited, but from the viewpoints of being a non-narcotic substance and dissolving it in a non-halogen solvent, and realizing good optoelectronic properties, it is usually 0.05% by weight or more, preferably 0.1% by weight or more, more preferably 0.3% by weight or more, still more preferably 0.5% by weight or more, particularly preferably 1.0% by weight or more, and usually 8% by weight or less, preferably 5% by weight or less, more preferably 4% by weight or less, still more preferably 3% by weight or less, particularly preferably 2% by weight or less.

[0118] The organic semiconductor ink according to this embodiment may contain a compound other than the above copolymer as a p-type semiconductor compound. Examples 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))-alt-(5,5-(1’,3’-di-2-thienyl-5’,7’-bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-c’]dithiophene-4,8-dione)]), PTq10 (Poly[[6,7-difluoro[(2-hexyldecyl)oxy]-5,8-quinoxalinediyl]-2,5-thiophenediyl]), or PCDTBT (Poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)]) and the like can be mentioned.

[0119] The organic semiconductor ink according to this embodiment exhibits semiconductor characteristics. For example, in the measurement of the field-effect mobility of its cured product (in this specification, those formed into a shape such as a film by drying are also called cured products), the hole mobility (sometimes referred to as hole 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, particularly preferably 1.0×10 -4 cm 2 / Vs or more. On the other hand, 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, particularly preferably 1.0×10 cm 2 / Vs or less. As a method for measuring the hole mobility, the FET method can be mentioned. The FET method can be carried out by the method described in a known document (Japanese Patent Application Laid-Open No. 2010-045186). The viscosity and the like of this ink are not particularly limited and may be appropriately selected according to the coating method to be used.

[0120] [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 the n-type semiconductor compound is not particularly limited. For example, perylene-bisimide, [6,6]-phenyl-C 61 -methyl butyrate (

[60] PCBM) or PCBM having a larger fullerene such as C 70 and the like, [6,6]-phenyl-C 61 -n-butyl butyrate (

[60] PCBNB) or a fullerene derivative such as PCBNB having a larger fullerene such as C 70 and the like, 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 Examples include 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]thieno[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 and the like. Among these, from the viewpoints of being a non-toxic substance and being soluble in a non-halogen solvent, and realizing good optoelectronic properties, PCBM, ITIC, and P(NDI20D-2T) are preferable, and PCBM is particularly preferable. The n-type semiconductor compound may be used alone or in combination of two or more in any type and ratio. Since the n-type semiconductor compound receives excited electrons from the p-type semiconductor, it has an electron affinity of 3.5 eV or more. Furthermore, from the viewpoint of providing a sufficient sub-driving force for receiving excited electrons, the electron affinity is preferably 3.6 eV or more, more preferably 3.7 eV or more, further preferably 3.8 eV or more, and particularly preferably 4.0 eV or more. Also, to prevent spontaneous reception of electrons not due to photoexcitation from the p-type semiconductor and to increase the open-circuit voltage when used as an organic solar cell, it is preferably 5.0 eV or less, more preferably 4.5 eV or less, further preferably 4.3 eV or less, and particularly preferably 4.2 eV or less.

[0121] The content of the above n-type semiconductor compound in the organic semiconductor ink according to this embodiment is not particularly limited. However, from the viewpoints of being a non-drug and dissolving in a non-halogen solvent, and realizing good optoelectronic properties, it is usually 0.2% by weight or more, preferably 0.5% by weight or more, more preferably 1.0% by weight or more, still more preferably 1.5% by weight or more, particularly preferably 3.0% by weight or more. Also, it is usually 50% by weight or less, preferably 30% by weight or less, more preferably 20% by weight or less, still more preferably 15% by weight or less, particularly preferably 10% by weight 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. However, from the viewpoint of realizing good optoelectronic properties, in terms of weight ratio, it is usually 0.5 or more, preferably 0.8 or more, more preferably 1.5 or more, still more preferably 2.0 or more. Also, it is usually 10 or less, preferably 8 or less, more preferably 6 or less, still more preferably 4 or less.

[0122] Regarding the measurement of electron affinity, almost the same value can be obtained by either a method of indirectly determining from known cyclic voltammetry and optical band gap or a method of directly determining by inverse electron spectroscopy. In the present invention, the method of obtaining from cyclic voltammetry and optical band gap is used. Also, simply, the LUMO energy level with respect to the vacuum level can be substituted.

[0123] [Solvent] The organic semiconductor ink according to this embodiment contains a solvent. The solvent used in this embodiment includes anisole derivatives in which no halogen group is directly bonded to the benzene ring, and is excellent from the viewpoints of ensuring the safety of workers and reducing the environmental impact. The type of anisole derivative in which no halogen group is directly bonded to the benzene ring is not particularly limited, but from the viewpoints of ensuring the safety of workers and reducing the environmental impact, it is preferably an anisole derivative having no halogen group. 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, 3,5-dimethylanisole are preferable, and particularly preferably 2-methylanisole. The anisole derivative may be used alone or in combination of two or more in any type and ratio.

[0124] The organic semiconductor ink according to this embodiment may contain a solvent other than the anisole derivative in which no halogen group is directly bonded to the benzene ring as the solvent. For example, 1,4-dioxane, acetone, ethylbenzene, etc. may be mentioned. From the viewpoints of ensuring the safety of workers and reducing the environmental impact, it is preferable that the above anisole derivative has no halogen group, more preferably that the compound contained as the solvent has no halogen group, and even more preferably that the organic semiconductor ink according to this embodiment does not contain a compound having a halogen group.

[0125] From the viewpoint of achieving both good coatability, drying property, and photoelectric conversion characteristics, the boiling point of the above anisole derivative is 150 °C or higher, preferably 155 °C or higher, more preferably 160 °C or higher, even more preferably 170 °C or higher, and preferably 300 °C or lower, more preferably 250 °C or lower, even more preferably 200 °C or lower.

[0126] From the viewpoints of ensuring the safety of workers and reducing the environmental impact, it is preferable that the solvent does not substantially contain a compound containing a halogen element (below the detection limit).

[0127] The content of the solvent in the organic semiconductor ink according to this embodiment is not particularly limited, but from the viewpoint of improving handleability, it is usually 10% by weight or more, preferably 40% by weight or more, more preferably 60% by weight or more, still more preferably 80% by weight or more, particularly preferably 90% by weight or more. Also, it is usually 99.9% by weight or less, preferably 99.5% by weight or less, more preferably 97% by weight or less, still more preferably 96% by weight or less, particularly preferably 95% by weight or less.

[0128] The content of the anisole derivative in which no halogen group is directly bonded to the benzene ring in the organic semiconductor solvent according to this embodiment is not particularly limited, but from the viewpoint of handleability, it is usually 10% by weight or more, preferably 40% by weight or more, more preferably 50% by weight or more, still more preferably 60% by weight or more, particularly preferably 70% by weight or more. Also, it is usually 99% by weight or less, preferably 96% by weight or less, more preferably 94% by weight or less, still more preferably 92% by weight or less, particularly preferably 90% by weight or less. The concentration of halogen as an impurity in the solvent is preferably 1% by weight or less, 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) from the viewpoints of ensuring the safety of workers and environmental load.

[0129] In the organic semiconductor ink according to this embodiment, the ratio of the content of the anisole derivative in which no halogen group is directly bonded to the benzene ring to the content of the p-type semiconductor compound (anisole derivative in which no halogen group is directly bonded to the benzene ring / p-type semiconductor compound) is not particularly limited, but from the viewpoint of improving handleability and realizing good optoelectronic characteristics, in terms of weight ratio, it is usually 1 or more, preferably 10 or more, more preferably 30 or more, still more preferably 50 or more, and usually 1000 or less, preferably 500 or less, more preferably 200 or less, and still more preferably 100 or less.

[0130] [Other components] The organic semiconductor ink according to this embodiment may further contain components other than the above p-type semiconductor, n-type semiconductor, and solvent (also referred to as "other components" or "additives") within the range where the effects of the present invention can be obtained. For example, polymers or monomers other than the polymers or monomers related to the above copolymers, thickeners, morphology modifiers, oxidizing agents, reducing agents, thermosetting agents, or photocuring agents, etc. can be mentioned. The other components may be used alone or in combination of two or more in any kind and ratio. As the morphology modifier, considering that it has a higher boiling point than the main solvent, has a fluidity close to that of a liquid during coating and drying, and has a higher solubility in the n-type semiconductor than in the p-type semiconductor, etc., it can be selected from aromatic systems (such as tetralin, diphenyl ether, etc.), non-aromatic systems (such as 1,8-diiodooctane, 2-methyltetrahydrofuran, etc.), or solid systems (such as polymers such as polystyrene, poly dimethylsiloxane, etc.), and from the viewpoint of forming an appropriate phase separation structure between the p-type semiconductor and the n-type semiconductor during coating and drying of the ink, for example, it preferably contains an aromatic hydrocarbon or a halogenated alkyl. The type of the aromatic hydrocarbon or the halogenated alkyl is not particularly limited, and examples include tetralin, 1,8-diiodooctane, ditolyl ether, diphenyl ether, polystyrene, etc. However, from the viewpoint of the solubility of the n-type semiconductor, it is preferable to have tetralin or 1,8-diiodooctane. The melting point of the above aromatic hydrocarbon or alkyl halide is not particularly limited, but from the viewpoint of exhibiting the morphology adjusting 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. Also, it 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 above aromatic hydrocarbon or alkyl halide is not particularly limited, but from the viewpoint of evaporating more slowly than the solvent and exhibiting the morphology adjusting function during coating and drying, 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. Also, it 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.

[0131] <4. Electronic Device Containing Organic Semiconductor Material Obtained by Using 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 manufactured using the above organic semiconductor ink. That is, the organic electronic device according to this embodiment contains (or includes) the above organic semiconductor ink or a cured product thereof. There is no particular limitation on the type of the organic electronic device according to this embodiment as long as the above organic semiconductor ink can be applied. Examples include light-emitting elements, switching elements, photoelectric conversion elements, optical sensors utilizing photoconductivity, etc. As an example of the photoelectric conversion element, an organic photodiode can be preferably used.

[0132] The form of the cured product of the 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, it is preferably in a sheet shape or a film shape. Also, from the viewpoint of sufficiently obtaining the light absorbance at the target absorption wavelength and transporting the charges generated by photoelectric conversion to the electrode without deactivating them, 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.

[0133] The method for obtaining the cured product of the organic semiconductor ink is not particularly limited. For example, there are methods of removing the solvent by natural drying or heating without using a curing agent to cure, methods of reacting the contained components without using a curing agent to cure, or methods of containing a thermosetting agent or a photocuring agent in the organic semiconductor ink and curing by heating or light irradiation, etc. When curing by removing the solvent by heating without using a curing agent, the heating conditions can be appropriately set according to the contained components, particularly the form of the solvent. However, 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. Also, the heating time may be, for example, 1 minute or more and 72 minutes or less, or may be 5 minutes or more and 10 hours or less. The heating conditions when using a thermosetting agent are not particularly limited. 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. Also, 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. The heating conditions when using a photocuring agent are not particularly limited. The type of light that can be used is, for example, gamma rays, X-rays, ultraviolet rays, visible light, or infrared rays, etc. The light irradiation time may be, for example, 5 seconds or more and 72 hours or less, or may be 1 minute or more and 10 hours. Thank you very much.

[0134] Examples of the light-emitting element include various light-emitting elements used in display devices. Specific examples include liquid crystal display elements, polymer-dispersed liquid crystal display elements, electrophoretic display elements, electroluminescent elements, electrochromic elements, etc. Specific examples of the switching element include diodes (pn junction diodes, Schottky diodes, MOS diodes, etc.), transistors (bipolar transistors, field effect transistors (FETs), etc.), thyristors, and furthermore, composite elements thereof (for example, TTL, etc.).

[0135] Specific examples of the photoelectric conversion element include thin film solar cells, charge coupled devices (CCDs), photomultiplier tubes, photocouplers, etc. In addition, as photo sensors utilizing photoconductivity, those using these photoelectric conversion elements can be mentioned. There is no particular limitation on which part of the organic electronic device the above-mentioned organic semiconductor ink or its cured product is used, and it can be used in any part. In order to utilize the semiconductor characteristics of the above-mentioned organic semiconductor ink, it is preferable to use the above-mentioned organic semiconductor ink or its cured product for the semiconductor layer of the organic electronic device. Particularly in the case of a photoelectric conversion element, usually, the organic semiconductor layer containing the organic semiconductor ink or its cured product according to the present invention is used as the organic active layer.

[0136] <5. Photoelectric conversion element> The photoelectric conversion element obtained by using the above-mentioned organic semiconductor ink is another embodiment of the present invention, and is a photoelectric conversion element including a pair of electrodes and an active layer disposed between the electrodes, and the active layer includes a cured product of the organic semiconductor ink containing the above-mentioned copolymer.

[0137] [5-1. Configuration of photoelectric conversion element] FIG. 1 shows an example of a photoelectric conversion element according to the present 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 the present embodiment is not limited to the one shown in FIG. 1. The photoelectric conversion element 107 as an example of the present embodiment has a layer structure including a substrate 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. In FIG. 1, an example of a photoelectric conversion element in which each layer is laminated in the above-described order is shown, but the photoelectric conversion element 107 may have a configuration in which the substrate 106, the cathode 105, the electron extraction layer 104, the active layer 103, the hole extraction layer 102, and the anode 101 are in this order. Further, the active layer 103 may have a configuration in which a p-type semiconductor material and an n-type semiconductor material are laminated. Furthermore, the hole extraction layer 102 and the electron extraction layer 104 are not essential components and may be provided arbitrarily.

[0138] The layer structure of the active layer 103 is preferably a mixed layer of a p-type semiconductor material and an n-type semiconductor material (sometimes referred to as a bulk heterojunction type), but other configurations may also be used. For example, it may be a thin-film laminated type in which a p-type semiconductor material and an n-type semiconductor material are laminated, or a structure having a mixed layer (i-layer) of a p-type semiconductor material and an n-type semiconductor material in an intermediate layer of the thin-film laminated type. As the compound contained in the p-type semiconductor material of the active layer 103, it is preferable to use the above-described copolymer. Further, as the active layer 103, it is preferable to use the above-described organic semiconductor ink or a cured product thereof.

[0139] Also, between each layer of the photoelectric conversion element 107, another layer may be inserted to such an extent that it does not affect the functions of the layers described later.

[0140] 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, it is 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. Regarding the p-type semiconductor material of the active layer 103, in addition to the above copolymer, it may also be used in combination with a p-type semiconductor material (compound) other than the above copolymer as described in the above-known literature. Also, the preferred film thicknesses of the substrate 106 and each layer constituting the photoelectric conversion element 107 are as described in the above-known literature. Among the above-known literature, the preferred materials for the substrate 106 and each layer constituting the photoelectric conversion element will be described below.

[0141] As the substrate 106, an inorganic material substrate such as a glass substrate, a plastic substrate such as polyethylene terephthalate, polyethylene naphthalate, or polyimide, a substrate made of a paper material such as paper or synthetic paper, or a composite material such as a metal such as stainless steel, copper, titanium, or aluminum with its surface coated or laminated to impart insulation can be mentioned. In terms of obtaining a lightweight and flexible photoelectric conversion element, it is preferable to use a plastic substrate or a substrate made of a composite material as the material of the substrate 106. As the cathode 105, in particular, indium tin oxide (ITO), silver, copper, aluminum, etc. can be mentioned.

[0142]

[0143] The electron extraction layer 104 may be either an inorganic compound or an organic compound, but titanium oxide (TiOx) or zinc oxide (ZnO) is preferable in terms of excellent film formation stability and the ability to reduce production costs.

[0144] ​As the n-type semiconductor compound of the active layer 103, the LUMO energy level is not particularly limited. For example, a material whose value with respect to the vacuum level calculated by cyclic voltammetry measurement is usually -4.0 eV or higher, preferably -3.9 eV or higher, is preferred. 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, when the LUMO energy level of the n-type semiconductor compound is increased, Voc tends to increase. On the other hand, if the LUMO energy level is increased too much, electron transfer from the p-type semiconductor compound becomes difficult. Therefore, it is usually -1.0 eV or lower, preferably -2.0 eV or lower, more preferably -3.0 eV or lower, and even more preferably -3.3 eV or lower. When the LUMO energy level of the n-type semiconductor compound is within the above range, the open-circuit voltage (Voc) and the short-circuit current density (Jsc) can be increased simultaneously.

[0145] The HOMO energy level of the n-type semiconductor compound is not particularly limited, but is usually -5.0 eV or lower, preferably -5.5 eV or lower. On the other hand, it is usually -7.0 eV or higher, preferably -6.6 eV or higher. The fact that the HOMO energy level of the n-type semiconductor compound is -7.0 eV or higher is preferable in that the light absorption of the n-type semiconductor compound can also be utilized for power generation. The fact that the HOMO energy level of the n-type semiconductor compound is -5.0 eV or lower is preferable in that the reverse transfer of holes can be blocked.

[0146] The electron mobility of the n-type semiconductor compound is not particularly limited, but is usually 1.0×10 -6 cm 2 / Vs or higher, and 1.0×10 -5 cm 2 / Vs or higher is preferable, 5.0×10 -5 cm 2 / Vs or higher is more preferable, and 1.0×10 -4 cm 2 / Vs or higher is even more preferable. On the other hand, it is usually 1.0×10 4 cm 2 / Vs or lower, and 1.0×10 3 cm 2 / Vs or lower is preferable, 5.0×102 cm 2 More preferably, it is below / Vs. That the electron mobility of the n-type semiconductor compound is within the above range is preferable in that effects such as improvement in conversion efficiency can be obtained in combination with the above copolymer. As a method for measuring the electron mobility, the FET method can be mentioned, and it can be carried out by the method described in a known document (Japanese Patent Application Laid-Open No. 2010-045186).

[0147] Specifically, since it is easy to form an ideal phase separation structure with the above copolymer, a fullerene derivative having a substituent is preferable, and particularly preferably PCBM.

[0148] As the hole extraction layer 102, although not limited, it is preferably a material having a Fermi level of -5.0 eV or less (or a work function of 5.0 eV or more). More preferably, the Fermi level is -5.1 eV or less (work function is 5.1 eV or more), and particularly preferably the Fermi level is -5.2 eV or less (work function is 5.2 eV or more). When the Fermi level (or work function) is within the above range, it becomes easier to extract holes from the above copolymer, and a photoelectric conversion element excellent in photoelectric conversion efficiency and durability can be provided. There is no particular limitation as long as it is a material that satisfies such conditions. For example, conductive polymers doped with sulfonic acid and / or iodine, etc. such as polythiophene, polypyrrole, polyacetylene, triphenylenediamine or polyaniline, polythiophene derivatives having a sulfonyl group as a substituent, conductive organic compounds such as arylamine, and metal oxides such as molybdenum trioxide can be mentioned. are preferred.

[0149] There is no particular limitation on the anode 101, and a conductive metal oxide such as indium tin oxide (ITO), a metal such as silver, gold, platinum, chromium or cobalt, or an alloy thereof can be used.

Examples

[0150] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

[0151] <Experiment 1: Evaluation of Solubility> As the anisole compound, the following D1, a compound manufactured by Mitsubishi Chemical Corporation, was used. The weight average molecular weight of the following D1 is 299,000, the molecular weight dispersity (PDI) is 4.5, m is 0.6, and n is 0.4.

[0152] [Chemical formula]

[0153] (Example 1) The above D1 was dissolved in 2-methylanisole (Tokyo Chemical Industry) and heated at 120 °C for 2 hours to obtain an 8 mg / mL solution. This solution was left standing 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.

[0154] (Example 2) The solubility was observed in the same manner as in Example 1, except that the solvent was p-bromoanisole (Tokyo Chemical Industry). The observation results are shown in Table 1.

[0155] (Comparative Example 1) The solubility was observed in the same manner as in Example 1, except that the solvent was chlorobenzene (Aldrich). The observation results are shown in Table 1.

[0156] (Comparative Example 2) The solubility was observed in the same manner as in Example 1, except that the solvent was p-cymene. The observation results are shown in Table 1.

[0157] (Comparative Example 3) The solubility was observed in the same manner as in Example 1, except that the solvent was ethylbenzene (Tokyo Chemical Industry). The observation results are shown in Table 1.

[0158] (Comparative Example 4) Except for using terpinolene (Tokyo Chemical Industry Co., Ltd.) as the solvent, the solubility was observed in the same manner as in Example 1. The observation results are shown in Table 1.

[0159] [Table 1]

[0160] As can be seen from Table 1, at 60°C, the anisole derivatives according to Examples 1 and 2 and the chlorobenzene according to Comparative Example 1 showed good solubility, but the solubility in aromatic hydrocarbons not having a heteroatom of Comparative Examples 2 to 4 was poor. Furthermore, at 80°C, the anisole derivatives according to Examples 1 and 2 showed good solubility, but the solubility in chlorobenzene of Comparative Example 1 and the solubility in aromatic hydrocarbons not having a heteroatom of Comparative Examples 2 to 4 was poor.

[0161] <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.

[0162] PEC-S20 action spectrum measurement device manufactured by Peccell Technology and Tektronix Using a Threy 2400 source meter, incident light with a wavelength of 700 nm was irradiated and a voltage of -5 V was applied to the element to obtain the external quantum efficiency. In the measurement, light was incident from the ITO substrate side.

[0163] Example 3 An organic photodiode was fabricated by the following method. A 70-nm-thick transparent conductive film of indium tin oxide (ITO) was patterned on a glass substrate as an electrode. The surface of the ITO substrate was treated with an ultraviolet ozone cleaner (NL-UV253, Japan Laser Electronics Co., Ltd.) for 10 minutes, and then a hole transport layer was formed as follows. 60 mg of the polymer shown in the following formula (H4) (Mw = 64000, Mn = 43000, Mw / Mn = 1.5) was dissolved in 1 mL of anisole to prepare a composition for forming a hole transport layer. In the following formula (H4), Ar in the repeating unit contained at a ratio of 0.95 is a 9,9-di-n-hexyl-2-fluorenyl group described as 0.95 below, and is not randomly contained at 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 a rotation speed of 1000 rpm for 30 seconds under a nitrogen atmosphere, and then heated and dried at 240 °C for 30 minutes to form a hole transport layer with a film thickness of 250 nm. The polymer shown in the following formula (H4) also polymerizes by heating and drying at 230 °C, and no problems occur even when the subsequent coating process is performed.

[0164]

Chemical formula

[0165] An optoelectronic conversion layer (active layer) was formed on this hole transport layer as follows. 8 mg of D1 in the above Experiment 1 and 20 mg of mixPCBM (manufactured by Frontier Carbon, [C 60]PCBM:[C70]PCBM = 1:3 (weight ratio)) were mixed, and 1.0 mL of 2-methyl anisole (manufactured by Tokyo Chemical Industry) was added, and after heating at 110 °C for 4 hours, while heating, it was passed through a 5.0 μm PTFE filter to obtain optoelectronic conversion ink 1. This ink 1 was heated to 60 °C, spin-coated on the substrate coated with the HTL at 1000 rpm, and after spin-coating, the device was heated in nitrogen at 120 °C for 10 minutes to obtain an optoelectronic conversion layer of 300 nm. Then, 40 nm of fullerene (manufactured by Frontier Arbor) and 100 nm of aluminum were deposited by a vacuum evaporation device to obtain optoelectronic conversion device 1.

[0166] (Comparative Example 5) In Experiment 1 above, 8 mg of D1 and 20 mg of mixPCBM were mixed, 1.0 mL of p-bromoanisole was added, and after heating at 110 °C for 4 hours, while still heated, Ink 2 for photoelectric conversion was obtained by passing through a 5.0 μm PTFE filter. A photoelectric conversion element 2 was fabricated in the same manner as in Example 3 except that Ink 2 was used.

[0167] (Comparative Example 6) In Experiment 1 above, 12 mg of D1 and 30 mg of mixPCBM were mixed, 0.9 mL of xylene (manufactured by Kanto Chemical) and 0.1 mL of tetralin (manufactured by Aldrich) were added, and after heating at 110 °C for 4 hours, while still heated, Ink 3 for photoelectric conversion was obtained by passing through a 1.0 μm PTFE filter. A photoelectric conversion element 3 was fabricated in the same manner as in Example 3 except that Ink 3 was used.

[0168] [Table 2]

[0169] From Table 2, it became clear that p-bromoanisole having one halogen group in the aromatic ring among anisole derivatives as described above cannot obtain a good photoelectric conversion film. Also, it was revealed that Ink 1 using 2-methylanisole gives photoelectric conversion characteristics equivalent to those of Ink 3 mainly composed of xylene, which is a highly toxic reagent generally used in organic photoelectric conversion inks.

[0170] (Experiment 3: Additive) (Example 4) In Experiment 1 above, 10 mg of D1 and 25 mg of mixPCBM were mixed, 0.9 mL of 2-methylanisole and 0.1 mL of tetralin (manufactured by Aldrich) as an additive were added, and after heating at 110 °C for 4 hours, while still heated, Ink 4 for photoelectric conversion was obtained by passing through a 1.0 μm PTFE filter. A photoelectric conversion element 4 was fabricated in the same manner as in Example 3 except that Ink 3 was used and the element was heated in nitrogen at 120 °C for 10 minutes after spin coating of Ink 3.

[0171] (Example 5) In the above Experiment 1, 10 mg of D1 was mixed with 25 mg of mixPCBM, 0.98 mL of 2-methylanisole was added, and 0.02 mL of 1,8-diiodooctane (manufactured by Aldrich) was added as an additive. After heating at 110°C for 4 hours, while still heated, the photoelectric conversion ink 5 was obtained by passing it through a 1.0 μm PTFE filter. A photoelectric conversion element 5 was fabricated in the same manner as in Example 4 except that this ink 5 was used.

[0172]

Table 3

[0173] As described above, it was clarified that the external quantum efficiency of the photoelectric conversion layer obtained from the organic photoelectric conversion ink using 2-methylanisole as the main solvent is maintained even when aromatic hydrocarbons or alkyl halides of liquid additives are used at room temperature (25°C).

[0174] From the above examples, it was found that according to the present invention, in a photoelectric conversion element provided with a hole transport layer containing a polytriarylamine-based semiconductor compound, the heat resistance and light resistance can be improved.

Explanation of Reference Numerals

[0175] 101 Anode 102 Hole extraction layer 103 Active layer 104 Electron extraction layer 105 Cathode 106 Substrate 107 Photoelectric conversion element

Claims

1. A p-type semiconductor compound which is a copolymer containing a repeating unit represented by the following formula (1A), a repeating unit represented by 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 in which a halogen group is not directly bonded to the benzene ring; An organic semiconductor ink containing the above. 【Chemical 1】 (In Formula (1A), Formula (1B), and Formula (1C), A １ and A ２ each independently represents an atom selected from Group 16 of the periodic table, Q represents an atom selected from Group 14 of the periodic table, R １ represents a linear alkyl group which may have a substituent, and R ２ 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. R ３ and R ４ each independently represents 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.

3. The organic semiconductor ink according to Claim 2, wherein the anisole is 2-methylanisole.

4. The organic semiconductor ink according to any one of Claims 1 to 3, further containing an aromatic hydrocarbon or a halogenated alkyl.

5. The organic semiconductor ink according to Claim 4, wherein the melting point of the aromatic hydrocarbon or the halogenated alkyl is 25°C or lower.

6. The organic semiconductor ink according to Claim 4 or 5, wherein the boiling point of the aromatic hydrocarbon or the halogenated alkyl is equal to or higher than the boiling point of the solvent. The organic semiconductor ink according to Claim 4 or 5, wherein the boiling point of the aromatic hydrocarbon or the halogenated alkyl is equal to or higher than the boiling point of the solvent.

7. The organic semiconductor ink according to any one of Claims 4 to 6, wherein the aromatic hydrocarbon or the halogenated alkyl is tetralin or 1,8-diiodooctane.

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