WO2025094596A1 - Charge-transporting composition - Google Patents

Abstract

As a charge-transporting composition that is suitable for forming a charge-transporting thin film of a photoelectric conversion element, and, in particular, is capable of significantly improving the photoelectric conversion efficiency of an obtained element when used as a hole-trapping layer of a perovskite-type solar cell, provided is a charge-transporting composition for forming a charge-transporting thin film in an organic photoelectric conversion element, the composition comprising a charge-transporting substance, an electron-accepting dopant substance, and an organic solvent, and the charge-transporting substance comprising at least one polyimide-based polymer selected from the group consisting of polyimide precursors obtained from a tetracarboxylic acid component and a diamine component having any structure represented by formulas (1)-(3), esters of the polyimide precursors, and imidized products of the polyimide precursors. (In the formulas, R¹ represents a hydrogen atom or a monovalent organic group, and * indicates a site to be bonded to another group. Any hydrogen atom forming a benzene ring may be substituted with a monovalent organic group.)

Description

Charge transport composition

The present invention relates to a charge transport composition, and more specifically, to a charge transport composition for forming a charge transport thin film used in an organic photoelectric conversion element.

Electronic elements, particularly organic photoelectric conversion elements, are devices that convert light energy into electrical energy using organic semiconductors, and examples thereof include organic solar cells.
Organic solar cells are solar cell elements that use organic materials in the active layer or charge transport material, and well-known examples include the dye-sensitized solar cell developed by M. Graetzel and the organic thin-film solar cell developed by C. W. Tang (Non-Patent Documents 1 and 2).
Both of these solar cells have features that differ from the currently mainstream inorganic solar cells, such as being lightweight, thin, and flexible, and being able to be produced on a roll-to-roll basis, and so are expected to create new markets.

On the other hand, in recent years, research results have been reported showing that solar cells using metal halides as compounds having a perovskite crystal structure (hereinafter referred to as "perovskite semiconductor compounds") can achieve relatively high photoelectric conversion efficiency, and this has attracted attention. For example, Patent Document 1 describes a photoelectric conversion element and solar cell equipped with an active layer containing a perovskite semiconductor compound.

In addition, in photoelectric conversion elements that use perovskite semiconductor compounds in the active layer, further investigations are being conducted into the conditions of not only the active layer but also the other layers that are combined with it in order to further improve the device characteristics.

JP 2016-178193 A

Nature, vol.353, 737-740(1991) Appl. Phys. Lett., Vol.48, 183-185 (1986)

The present invention has been made in consideration of the above circumstances, and aims to provide a charge transport composition that is suitable for forming a charge transport thin film for a photoelectric conversion element, and in particular, when used as a hole collection layer for a perovskite solar cell, can greatly improve the photoelectric conversion efficiency (PCE) of the resulting element.

As a result of extensive research conducted by the inventors in order to achieve the above object, they discovered that a charge transporting composition containing a charge transporting substance, an electron accepting dopant substance, and an organic solvent, and containing a polyimide-based polymer obtained by using a diamine component having a specific structure as the charge transporting substance, is suitable for forming a charge transporting thin film in an organic photoelectric conversion element, and in particular, when used as a hole collection layer in a perovskite solar cell, it can greatly improve the PCE of the resulting element, thereby completing the present invention.

（式中、Ｒ¹は、水素原子または一価の有機基を表す。＊は、他の基に結合する部位を表す。ベンゼン環を形成する任意の水素原子は一価の有機基で置換されていてもよい。）
２．　上記電子受容性ドーパント物質が、下記式（Ａｎ１）で表されるアニオンと、その対カチオンとからなる塩である１の電荷輸送性組成物。

（式中、Ｅは長周期型周期表の第１３族に属する元素を表し、Ａｒ^a1～Ａｒ^a4は、互いに独立して、置換基を有してもよい芳香族炭化水素基または置換基を有してもよい芳香族複素環基を表す。）
３．　上記塩が、オニウム塩である２の電荷輸送性組成物。
４．　上記電子受容性ドーパント物質の含有量が、質量比で、電荷輸送性物質１に対して、０．００１～５０である２の電荷輸送性組成物。
５．　上記Ｒ¹が、水素原子、炭素数１～５のアルキル基、炭素数１～５のフルオロアルキル基またはｔｅｒｔ－ブトキシカルボニル基である１～４のいずれかの電荷輸送性組成物。
６．　ペロブスカイト光電変換素子の正孔捕集層用である１～５のいずれかの電荷輸送性組成物。
７．　１～５のいずれかの電荷輸送性組成物から得られる電荷輸送性薄膜。
８．　上記電荷輸送性薄膜が、ペロブスカイト光電変換素子の正孔捕集層である７の電荷輸送性薄膜。
９．　８の電荷輸送性薄膜を備えるペロブスカイト光電変換素子。
１０．　逆積層型である９のペロブスカイト光電変換素子。
１１．　９のペロブスカイト光電変換素子を備える太陽電池。 That is, the present invention provides the following charge transport composition.
1. A charge transporting composition for forming a charge transporting thin film in an organic photoelectric conversion element, comprising:
A charge transporting material, an electron accepting dopant material, and an organic solvent are included,
The charge transporting material is a charge transporting composition comprising at least one polyimide polymer selected from the group consisting of a polyimide precursor obtained from a diamine component having a structure represented by any one of the following formulas (1) to (3) and a tetracarboxylic acid component, an ester of the polyimide precursor, and an imidized product of the polyimide precursor:

(In the formula, ^R1 represents a hydrogen atom or a monovalent organic group. * represents a bonding site to another group. Any hydrogen atom forming a benzene ring may be substituted with a monovalent organic group.)
2. The charge transport composition of 1, wherein the electron-accepting dopant substance is a salt composed of an anion represented by the following formula (An1) and its counter cation:

(In the formula, E represents an element belonging to Group 13 of the long form periodic table, and Ar ^a1 to Ar ^a4 each independently represent an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent.)
3. The charge transporting composition of 2, wherein the salt is an onium salt.
4. The charge transporting composition of 2, wherein the content of the electron accepting dopant substance is 0.001 to 50 parts by mass per 1 part by mass of the charge transporting substance.
5. The charge transporting composition of any one of 1 to 4, wherein R ¹ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a fluoroalkyl group having 1 to 5 carbon atoms, or a tert-butoxycarbonyl group.
6. The charge transport composition according to any one of 1 to 5, which is for use in a hole collection layer of a perovskite photoelectric conversion element.
7. A charge transporting thin film obtained from any one of the charge transporting compositions 1 to 5.
8. The charge transporting thin film according to 7, wherein the charge transporting thin film is a hole collecting layer of a perovskite photoelectric conversion element.
9. A perovskite photoelectric conversion element comprising the charge transporting thin film of 8.
10. The perovskite photoelectric conversion element of 9, which is of an inverted stacking type.
11. A solar cell comprising 9 perovskite photoelectric conversion elements.

The charge transporting composition of the present invention is suitable for forming a charge transporting thin film for a photoelectric conversion element, and in particular, when the charge transporting thin film is used as a hole collection layer for a perovskite photoelectric conversion element, a perovskite photoelectric conversion element having a high PCE can be obtained.

The present invention will be described in further detail below.
The charge transport composition of the present invention is a charge transport composition for forming a charge transport thin film in an organic photoelectric conversion element, and is characterized in that it comprises a charge transport substance, an electron accepting dopant substance, and an organic solvent, and the charge transport substance comprises at least one polyimide-based polymer selected from the group consisting of a polyimide precursor obtained from a diamine component having a structure represented by any one of the following formulas (1) to (3) and a tetracarboxylic acid component, an ester of the polyimide precursor, and an imidized product of the polyimide precursor:
Generally, the polyimide-based polymer has high heat resistance and excellent mechanical properties, and is widely used in the field of electronic devices. In addition, the polyimide-based polymer has high mass productivity and is suitable as a material for constituting a charge transport thin film of an organic photoelectric conversion element, particularly a perovskite solar cell.

（式中、Ｒ¹は、水素原子または一価の有機基を表す。＊は、他の基に結合する部位を表す。ベンゼン環を形成する任意の水素原子は一価の有機基で置換されていてもよい。）

(In the formula, ^R1 represents a hydrogen atom or a monovalent organic group. * represents a bonding site to another group. Any hydrogen atom forming a benzene ring may be substituted with a monovalent organic group.)

Hereinafter, the diamines having the structures of formulas (1) to (3) may be referred to as "specific diamines." Furthermore, polymers containing the specific diamines of the present invention may be referred to as "specific polymers."

<Specific diamine>
The specific diamine has any of the structures represented by the following formulas (1) to (3).

In the above formulas (1) to (3), R ¹ represents a hydrogen atom or a monovalent organic group. * represents a site for bonding to another group. Any hydrogen atom forming a benzene ring may be substituted with a monovalent organic group. Examples of the monovalent organic group include an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 10 carbon atoms, a fluoroalkenyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, and a tert-butoxycarbonyl group.

Examples of alkyl groups having 1 to 10 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl groups.

Alkenyl groups having 2 to 10 carbon atoms include ethenyl, n-1-propenyl, n-2-propenyl, 1-methylethenyl, n-1-butenyl, n-2-butenyl, n-3-butenyl, 2-methyl-1-propenyl, 2-methyl-2-propenyl, 1-ethylethenyl, 1-methyl-1-propenyl, 1-methyl-2-propenyl, n-1-pentenyl, and n-1-decenyl.

Alkoxy groups having 1 to 10 carbon atoms include methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy, t-butoxy, n-pentoxy, n-hexyloxy, n-heptyloxy, n-octyloxy, n-nonyloxy, and n-decyloxy.

The fluoroalkyl group having 1 to 10 carbon atoms is not particularly limited as long as it is an alkyl group having 1 to 10 carbon atoms in which at least one hydrogen atom on a carbon atom has been replaced with a fluorine atom, and specific examples include a fluoromethyl group, a difluoromethyl group, a perfluoromethyl group, a 1-fluoroethyl group, a 2-fluoroethyl group, a 1,2-difluoroethyl group, a 1,1-difluoroethyl group, a 2,2-difluoroethyl group, a 1,1,2-trifluoroethyl group, a 1,2,2-trifluoroethyl group, a 2,2,2-trifluoroethyl group, a 1,1,2,2-tetrafluoroethyl group, a 1,2,2,2-tetrafluoroethyl group, a perfluoroethyl group, a 1-fluoropropyl group, a 2-fluoropropyl group, a 3-fluoropropyl group, a 1,1-difluoropropyl group, a 1,2-difluoropropyl group, a 1,3-difluoropropyl group, a 2,2-difluoropropyl group, a 2,3-difluoropropyl group, a 3,3-difluoropropyl group, a 1,1,2-trifluoropropyl group, group, 1,1,3-trifluoropropyl group, 1,2,3-trifluoropropyl group, 1,3,3-trifluoropropyl group, 2,2,3-trifluoropropyl group, 2,3,3-trifluoropropyl group, 3,3,3-trifluoropropyl group, 1,1,2,2-tetrafluoropropyl group, 1,1,2,3-tetrafluoropropyl group, 1,2,2,3-tetrafluoropropyl group, 1,3,3,3-tetrafluoropropyl group, 2,2,3,3-tetrafluoropropyl group , 2,3,3,3-tetrafluoropropyl group, 1,1,2,2,3-pentafluoropropyl group, 1,2,2,3,3-pentafluoropropyl group, 1,1,3,3,3-pentafluoropropyl group, 1,2,3,3,3-pentafluoropropyl group, 2,2,3,3,3-pentafluoropropyl group, perfluoropropyl group, perfluorobutyl group, perfluoropentyl group, perfluorohexyl group, perfluoroheptyl group, perfluorooctyl group, etc.

The fluoroalkenyl group having 2 to 10 carbon atoms is not particularly limited as long as it is a fluoroalkenyl group having 2 to 10 carbon atoms in which at least one hydrogen atom on a carbon atom is replaced with a fluorine atom, and specific examples include a 2-fluoroethenyl group, a 2,2-difluoroethenyl group, a 2-fluoro-2-propenyl group, a 3,3-difluoro-2-propenyl group, a 2,3-difluoro-2-propenyl group, a 3,3-difluoro-2-methyl-2-propenyl group, a 3-fluoro-2-butenyl group, a perfluorovinyl group, a perfluoropropenyl group, and a perfluorobutenyl group.

The fluoroalkoxy group having 1 to 10 carbon atoms is not particularly limited as long as it is an alkoxy group having 1 to 10 carbon atoms in which at least one hydrogen atom on a carbon atom is replaced with a fluorine atom, and specific examples include a fluoromethoxy group, a difluoromethoxy group, a perfluoromethoxy group, a 1-fluoroethoxy group, a 2-fluoroethoxy group, a 1,2-difluoroethoxy group, a 1,1-difluoroethoxy group, a 2,2-difluoroethoxy group, and a 1,1,2-trifluoroethoxy group. groups, 1,2,2-trifluoroethoxy groups, 2,2,2-trifluoroethoxy groups, 1,1,2,2-tetrafluoroethoxy groups, 1,2,2,2-tetrafluoroethoxy groups, perfluoroethoxy groups, 1-fluoropropoxy groups, 2-fluoropropoxy groups, 3-fluoropropoxy groups, 1,1-difluoropropoxy groups, 1,2-difluoropropoxy groups, 1,3-difluoropropoxy groups, 2,2-difluoropropoxy groups, 2,3-difluoropropoxy groups, 3,3-difluoropropoxy group, 1,1,2-trifluoropropoxy group, 1,1,3-trifluoropropoxy group, 1,2,3-trifluoropropoxy group, 1,3,3-trifluoropropoxy group, 2,2,3-trifluoropropoxy group, 2,3,3-trifluoropropoxy group, 3,3,3-trifluoropropoxy group, 1,1,2,2-tetrafluoropropoxy group, 1,1,2,3-tetrafluoropropoxy group, 1,2,2,3-tetrafluoropropoxy group, Examples of such groups include 1,3,3,3-tetrafluoropropoxy groups, 2,2,3,3-tetrafluoropropoxy groups, 2,3,3,3-tetrafluoropropoxy groups, 1,1,2,2,3-pentafluoropropoxy groups, 1,2,2,3,3-pentafluoropropoxy groups, 1,1,3,3,3-pentafluoropropoxy groups, 1,2,3,3,3-pentafluoropropoxy groups, 2,2,3,3,3-pentafluoropropoxy groups, and perfluoropropoxy groups.

R ¹ is preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkenyl group having 2 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluoroalkyl group having 1 to 3 carbon atoms, a fluoroalkenyl group having 2 to 3 carbon atoms, a fluoroalkoxy group having 1 to 3 carbon atoms, or a tert-butoxycarbonyl group, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and even more preferably a hydrogen atom or a methyl group.

In the structure of formula (1) above, the bonding position of the benzene ring to the pyrrole ring is preferably the carbon atom next to the nitrogen atom on the pyrrole ring, as shown in formula (1-1) below, in terms of charge transport properties.

（式中、Ｒ¹および＊は、式（１）の場合と同様である。）

(In the formula, ^R1 and * are the same as in formula (1).)

A preferred example of a diamine having the structure of formula (1) above is a diamine represented by formula (1-2) below.

In the above formula (1-2), R ¹ is the same as in formula (1). Two R ^2s each independently represent a single bond or a structure of the following formula (1-3). As in the case of formula (1), any hydrogen atom forming a benzene ring may be substituted with a monovalent organic group.

In formula (1-3), R ³ represents a divalent organic group selected from the group consisting of a single bond, -O-, -COO-, -OCO-, -(CH ₂ ) _i -, -O(CH ₂ ) _j O-, -CONH-, -NHCO-, -CON(CH ₃ )-, -N(CH ₃ )CO-, and -NR ¹ -. Here, i represents an integer of 1 to 14, and j represents an integer of 1 to 14. R ¹ is the same as in formula (1). Among these, from the viewpoint of charge transportability, R ³ is preferably a single bond, -O-, -COO-, -OCO-, -CONH-, -NHCO-, and -N(CH ₃ )-. In addition, * ₁ represents a site bonded to the benzene ring in formula (1-2). * ₂ represents a site bonded to the amino group in formula (1-2). In the formula (1-2), k1 is an integer of 1 to 3, and preferably 1 or 2.

Specific examples of the above formula (1-2) include those represented by the following formulas (1-2-1) to (1-2-17), but are not limited to these. Among these, from the viewpoint of charge transportability, formula (1-2-1), formula (1-2-2), formula (1-2-3), formula (1-2-5), formula (1-2-8), formula (1-2-9), formula (1-2-10), formula (1-2-11), formula (1-2-12), formula (1-2-13), formula (1-2-14), formula (1-2-15), formula (1-2-16) and formula (1-2-17) are preferred, and formula (1-2-1), formula (1-2-2), formula (1-2-3), formula (1-2-11), formula (1-2-12), formula (1-2-13), formula (1-2-14), formula (1-2-15), formula (1-2-16) and formula (1-2-17) are more preferred. In the following formulas (1-2-6) and (1-2-7), x1 is an integer from 1 to 14. Also, Boc represents a tert-butoxycarbonyl group.

In the structure of formula (2) above, the bonding position of other groups to the carbazole ring is preferably bonded as shown in formula (2-1) in terms of steric hindrance.

In the above formula (2-1), R ¹ is as defined above.

The specific diamines include those represented by the following formulas (2-2) to (2-7). In particular, from the viewpoint of charge transport properties, diamines represented by formulas (2-3) to (2-7) are preferred, and diamines represented by formulas (2-4) to (2-7) are more preferred.

In the above formula, the definition of ^R1 is the same as in the above formula (1), ^R4 is independently a hydrogen atom or a monovalent organic group, and ^R5 is independently a single bond or a divalent organic group. k2 is independently 2 or 3. Any hydrogen atom of the benzene ring may be substituted with a monovalent organic group.

Examples of the monovalent organic group in R ⁴ include the same as those exemplified in the description of R ^1. R ⁴ is preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkenyl group having 2 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluoroalkyl group having 1 to 3 carbon atoms, a fluoroalkenyl group having 2 to 3 carbon atoms, a fluoroalkoxy group having 1 to 3 carbon atoms, or a tert-butoxycarbonyl group, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and even more preferably a hydrogen atom or a methyl group.

The divalent organic group for ^R5 includes a group having a structure of the following formula (2-8).

In the above formula, R ⁶ represents a divalent organic group selected from the group consisting of a single bond, -O-, -COO-, -OCO-, -(CH ₂ ) _r -, -O(CH ₂ ) _s O-, -NR ⁶¹ -, -CONR ⁶¹ -, and -NR ⁶¹ CO-, and k3 represents an integer of 1 to 5. R ⁶¹ represents hydrogen or a monovalent organic group, r represents an integer of 1 to 5, and s represents an integer of 1 to 5. As the monovalent organic group, an alkyl group having 1 to 3 carbon atoms is preferable, and a methyl group is more preferable. * ₃ represents a site bonded to a benzene ring in formulas (2-3) to (2-7), and * ₄ represents a site bonded to an amino group in formulas (2-3) to (2-7).

Specific examples of the specific diamine include, but are not limited to, diamines represented by the following formulas (2-1-1) to (2-1-19). Among these, from the viewpoint of charge transport properties, formulas (2-1-1) to (2-1-7) and (2-1-10) to (2-1-17) are preferred, and formulas (2-1-1) to (2-1-7) and (2-1-15) to (2-1-17) are more preferred. In the following formulas, x2 is an integer from 1 to 14.

In the structure of formula (3) above, the bonding position of other groups to the benzene ring is preferably as shown in formula (3-1) in terms of steric hindrance.

In the above formula (3-1), R ¹ is as defined above.

The specific diamines include those represented by the following formulas (3-2) to (3-7). In particular, from the viewpoint of charge transport properties, the diamines represented by the formulas (3-3) to (3-7) are preferred, and the diamines represented by the formulas (3-4) to (3-7) are more preferred.

In the above formula, the definition of R ¹ is the same as in the above formula (1), R ⁷ is independently a hydrogen atom or a monovalent organic group, and R ⁸ is independently a single bond or a divalent organic group. k4 is independently 2 or 3. Any hydrogen atom of the benzene ring may be substituted with a monovalent organic group.

Examples of the monovalent organic group in R ⁷ include the same as those exemplified in the description of R ^1. R ⁷ is preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkenyl group having 2 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluoroalkyl group having 1 to 3 carbon atoms, a fluoroalkenyl group having 2 to 3 carbon atoms, a fluoroalkoxy group having 1 to 3 carbon atoms, or a tert-butoxycarbonyl group, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and even more preferably a hydrogen atom or a methyl group.

The divalent organic group for R ⁸ includes a group having a structure of the following formula (3-8).

In the above formula, R ⁹ represents a divalent organic group selected from the group consisting of a single bond, -O-, -COO-, -OCO-, -(CH ₂ ) _r -, -O(CH ₂ ) _s O-, -NR ⁹¹ -, -CONR ⁹¹ -, and -NR ⁹¹ CO-, and k5 represents an integer of 1 to 5. R ⁹¹ represents hydrogen or a monovalent organic group, r represents an integer of 1 to 5, and s represents an integer of 1 to 5. As the monovalent organic group, an alkyl group having 1 to 3 carbon atoms is preferable, and a methyl group is more preferable. * ₅ represents a site bonded to a benzene ring in formulas (3-3) to (3-7), and * ₆ represents a site bonded to an amino group in formulas (3-3) to (3-7).

Specific examples of the specific diamine include, but are not limited to, diamines represented by the following formulas (3-1-1) to (3-1-19). Among these, from the viewpoint of charge transport properties, formulas (3-1-1) to (3-1-7) and (3-1-10) to (3-1-17) are preferred, and formulas (3-1-1) to (3-1-7) and (3-1-15) to (3-1-17) are more preferred. In the following formulas, x3 is an integer from 1 to 14.

<Method for synthesizing specific diamine>
The specific diamine may be synthesized by a known method and is not particularly limited. For example, the specific diamine may be synthesized by the method described in WO 2018/062197 or WO 2018/110354.

<Other diamines: diamines other than those listed above>
The diamine component for obtaining the specific polymer may contain other diamine components in addition to the specific diamines described above. Examples of the other diamine components include those represented by the following formula (E1).

In the above formula (E1), A ¹ and A ² each independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms, and Y ¹ represents a divalent organic group.

Examples of alkyl groups having 1 to 5 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, i-butyl, s-butyl, t-butyl, and n-pentyl groups.

Alkenyl groups having 2 to 5 carbon atoms include ethenyl, n-1-propenyl, n-2-propenyl, 1-methylethenyl, n-1-butenyl, n-2-butenyl, n-3-butenyl, 2-methyl-1-propenyl, 2-methyl-2-propenyl, 1-ethylethenyl, 1-methyl-1-propenyl, 1-methyl-2-propenyl, and n-1-pentenyl.

Alkynyl groups having 2 to 5 carbon atoms include ethynyl, n-1-propynyl, n-2-propynyl, n-1-butynyl, n-2-butynyl, n-3-butynyl, 1-methyl-2-propynyl, n-1-pentynyl, n-2-pentynyl, n-3-pentynyl, n-4-pentynyl, 1-methyl-n-butynyl, 2-methyl-n-butynyl, 3-methyl-n-butynyl, 1,1-dimethyl-n-propynyl, etc.

Among these, from the viewpoint of the reactivity of the monomer, A ¹ and A ² are preferably a hydrogen atom or a methyl group.

Examples of ^Y1 include groups represented by the following formulas (Y-1) to (Y-170). In the following formulas, x4 is an integer of 1 to 14, and where there is a preferred range, the range is noted. Where there is no description of the range of x4, an integer of 1 to 6 is preferred. In the following formulas, Me represents a methyl group, and Boc represents a tert-butoxycarbonyl group.

The other diamines described above may be used alone or in combination of two or more. When the diamine component contains other diamines, the content of the specific diamine in the diamine component is preferably 10 to 100 mol%, more preferably 30 to 100 mol%, and even more preferably 50 to 100 mol%.

<Tetracarboxylic acid component>
Examples of the tetracarboxylic acid component for obtaining the specific polymer include tetracarboxylic acid, tetracarboxylic dianhydride, tetracarboxylic acid dihalide, tetracarboxylic acid dialkyl ester, and tetracarboxylic acid dialkyl ester dihalide. In the present invention, these are collectively referred to as tetracarboxylic acid component.

As the tetracarboxylic acid component, tetracarboxylic dianhydride and its derivatives, such as tetracarboxylic acid, tetracarboxylic dihalide, tetracarboxylic dialkyl ester, and tetracarboxylic dialkyl ester dihalide (collectively referred to as the first tetracarboxylic acid component) can also be used.

Examples of tetracarboxylic dianhydrides include aliphatic tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides, and aromatic tetracarboxylic dianhydrides. Specific examples of these include those in the following groups [1] to [5].

[1] Examples of aliphatic tetracarboxylic dianhydrides include 1,2,3,4-butanetetracarboxylic dianhydride.

[2] Examples of alicyclic tetracarboxylic acid dianhydrides include acid dianhydrides such as those represented by the following formulas (X1-1) to (X1-13).

In the above formulas (X1-1) to (X1-4), R ^1a to R ^21a each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group. R ^M represents a hydrogen atom or a methyl group. In addition, in the above formula (X1-13), X ^a represents a tetravalent organic group represented by the following formulas (Xa-1) to (Xa-7).

[3] 3-oxabicyclo[3.2.1]octane-2,4-dione-6-spiro-3'-(tetrahydrofuran-2',5'-dione), 3,5,6-tricarboxy-2-carboxymethylnorbornane-2:3,5:6-dianhydride, 4,9-dioxatricyclo[5.3.1.02,6]undecane-3,5,8,10-tetraone, etc.

[4] Examples of aromatic tetracarboxylic dianhydrides include pyromellitic anhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, and acid dianhydrides represented by the following formulas (X2-1) to (X2-10).

[5] Examples include acid dianhydrides represented by the following formulas (X3-1) to (X3-9) and tetracarboxylic acid dianhydrides described in JP 2010-97188 A.

The tetracarboxylic acid components described above may be used alone or in combination of two or more. Depending on the characteristics required for the organic light sensor element or charge transport layer, one may be used alone or two or more may be used in combination, and if two or more are used in combination, the ratio, etc., may be appropriately adjusted.

<Method of Producing Specific Polymer>
As described above, the specific polymer is obtained by a method of reacting a diamine component with a tetracarboxylic acid component. For example, the method includes a method of reacting a diamine component consisting of one or more diamines with at least one tetracarboxylic acid component selected from the group consisting of tetracarboxylic dianhydrides and derivatives of the tetracarboxylic acid to obtain a polyamic acid. Specifically, a method of polycondensing a primary or secondary diamine with a tetracarboxylic dianhydride to obtain a polyamic acid is used.

In order to obtain a polyamic acid alkyl ester, a method of polycondensing a tetracarboxylic acid in which the carboxylic acid group has been dialkyl esterified with a primary or secondary diamine is used, a method of polycondensing a tetracarboxylic acid dihalide in which the carboxylic acid group has been halogenated with a primary or secondary diamine is used, or a method of converting the carboxy group of a polyamic acid into an ester is used. In order to obtain a polyimide, a method of ring-closing the above polyamic acid or polyamic acid alkyl ester to form a polyimide is used.

The reaction between the diamine component and the tetracarboxylic acid component is usually carried out in a solvent. The solvent used is not particularly limited as long as it dissolves the polyimide precursor produced. Examples of the solvent include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, 3-methoxy-N,N-dimethylpropanamide, dimethylsulfoxide, 1,3-dimethyl-imidazolidinone, and the like. In addition, when the polyimide precursor has high solubility in the solvent, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or solvents represented by the following formulas [s1] to [s3], and the like, can also be used.

In formula [s1], D ^s1 represents an alkyl group having 1 to 3 carbon atoms. In formula [s2], D ^s2 represents an alkyl group having 1 to 3 carbon atoms. In formula [s3], D ^s3 represents an alkyl group having 1 to 4 carbon atoms.

Examples of alkyl groups having 1 to 4 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, i-butyl, s-butyl, and t-butyl groups. Examples of alkyl groups having 1 to 3 carbon atoms include those having 1 to 3 carbon atoms among the above alkyl groups having 1 to 4 carbon atoms.

These solvents may be used alone or in combination of two or more. Even if the solvent does not dissolve the polyimide precursor, it may be mixed with the above-mentioned solvents as long as the resulting polyimide precursor does not precipitate. Furthermore, moisture in the solvent inhibits the polymerization reaction and may even cause hydrolysis of the resulting polyimide precursor, so it is preferable to use a solvent that has been dehydrated and dried.

When reacting the diamine component and the tetracarboxylic acid component in a solvent, any of the following methods may be used: a solution in which the diamine component is dispersed or dissolved in a solvent is stirred, and the tetracarboxylic acid component is added as is or dispersed or dissolved in the solvent; conversely, the diamine component is added to a solution in which the tetracarboxylic acid component is dispersed or dissolved in a solvent; or the diamine component and the tetracarboxylic acid component are added alternately. When reacting multiple diamine components or multiple tetracarboxylic acid components, they may be reacted in a premixed state, or may be reacted individually in sequence, or low molecular weight components that have been reacted individually may be mixed and reacted to form a polymer.

The temperature at which the diamine component and the tetracarboxylic acid component are polycondensed can be selected from -20 to 150°C, but is preferably in the range of -5 to 100°C. The reaction can be carried out at any concentration, but if the concentration is too low it becomes difficult to obtain a high molecular weight polymer, and if the concentration is too high the viscosity of the reaction liquid becomes too high, making uniform stirring difficult. For this reason, the concentration is preferably 1 to 50% by mass, and more preferably 5 to 30% by mass. The reaction can be carried out at a high concentration in the early stages, and then solvent can be added.

In the polymerization reaction of the polyimide precursor, the ratio of the total number of moles of the diamine component to the total number of moles of the tetracarboxylic acid component is preferably 0.8 to 1.2. As with a normal polycondensation reaction, the closer this molar ratio is to 1.0, the higher the molecular weight of the resulting polyimide precursor will be.

Polyimide is obtained by ring-closing the polyimide precursor. In this polyimide, the ring-closure rate of the amic acid group (also called the imidization rate) does not necessarily have to be 100% and can be adjusted as desired depending on the application or purpose. Methods for imidizing the polyimide precursor include thermal imidization, in which a solution of the polyimide precursor is heated as is, and catalytic imidization, in which a catalyst is added to a solution of the polyimide precursor.

The temperature for thermally imidizing the polyimide precursor in a solution is 100 to 400°C, preferably 120 to 250°C, and it is preferable to carry out the process while removing the water produced by the imidization reaction from the system. Catalytic imidization of the polyimide precursor can be carried out by adding a basic catalyst and an acid anhydride to a solution of the polyimide precursor and stirring at -20 to 250°C, preferably 0 to 180°C.

The amount of the basic catalyst is 0.5 to 30 times the molar amount of the amide acid group, preferably 2 to 20 times the molar amount, and the amount of the acid anhydride is 1 to 50 times the molar amount of the amide acid group, preferably 3 to 30 times the molar amount. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, etc. Among them, pyridine is preferred because it has an appropriate basicity for promoting the reaction. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, etc. In particular, the use of acetic anhydride is preferred because it makes purification after the reaction is completed easier. The imidization rate by catalytic imidization can be controlled by adjusting the amount of the catalyst, the reaction temperature, and the reaction time.

When recovering the polyimide precursor or polyimide produced from a reaction solution of a polyimide precursor or polyimide, the reaction solution may be poured into a solvent to cause precipitation. Examples of solvents used for precipitation include methanol, ethanol, isopropyl alcohol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene, and water. The polymer precipitated by pouring into a solvent can be recovered by filtration, and then dried at normal or reduced pressure, or at room temperature or by heating. In addition, the polymer precipitated and recovered can be redissolved in a solvent and the reprecipitation and recovery operation repeated 2 to 10 times to reduce impurities in the polymer. Examples of solvents used in this case include alcohols, ketones, and hydrocarbons. It is preferable to use three or more types of solvents selected from these, as this further increases the efficiency of purification.

Specific examples of methods for producing the polyamic acid alkyl ester of the present invention are shown below in (1) to (3).

(1) Production method by esterification reaction of polyamic acid This method is a method in which, for example, polyamic acid is produced from a diamine component and a tetracarboxylic acid component, and its carboxyl group (COOH group) is subjected to a chemical reaction, i.e., an esterification reaction, to produce a polyamic acid alkyl ester. The esterification reaction is a method in which a polyamic acid is reacted with an esterifying agent in the presence of a solvent at −20 to 150° C. (preferably 0 to 50° C.) for 30 minutes to 24 hours (preferably 1 to 4 hours).

The above esterification agent is preferably one that can be easily removed after the esterification reaction, and examples of such agents include N,N-dimethylformamide dimethyl acetal, N,N-dimethylformamide diethyl acetal, N,N-dimethylformamide dipropyl acetal, N,N-dimethylformamide dineopentyl butyl acetal, N,N-dimethylformamide di-t-butyl acetal, 1-methyl-3-p-tolyltriazene, 1-ethyl-3-p-tolyltriazene, 1-propyl-3-p-tolyltriazene, and 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride. The amount of the esterification agent used is preferably 2 to 6 molar equivalents per mole of the repeating unit of polyamic acid. Of these, 2 to 4 molar equivalents are preferred.

The solvent used in the esterification reaction may be the same as that used in the reaction between the diamine component and the tetracarboxylic acid component, in terms of the solubility of the polyamic acid in the solvent. Of these, N,N-dimethylformamide, N,N-diethylformamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-diethylacetamide, 3-methoxy-N,N-dimethylpropanamide, or γ-butyrolactone is preferred. These solvents may be used alone or in combination of two or more. The concentration of polyamic acid in the solvent in the esterification reaction is preferably 1 to 30% by mass, in terms of the low precipitation of polyamic acid. Of these, 5 to 20% by mass is preferred.

(2) Method of producing by reaction of diamine component with tetracarboxylic acid diester dichloride In this method, for example, a diamine component and a tetracarboxylic acid diester dichloride are reacted in the presence of a base and a solvent at −20 to 150° C. (preferably 0 to 50° C.) for 30 minutes to 24 hours (preferably 1 to 4 hours). As the base, pyridine, triethylamine, 4-dimethylaminopyridine, etc. can be used. Among them, pyridine is preferred because the reaction proceeds mildly. The amount of the base used is preferably an amount that can be easily removed after the reaction, and is preferably 2 to 4 times the mol of the tetracarboxylic acid diester dichloride, and more preferably 2 to 3 times the mol.

The solvent may be any of the solvents used in the reaction between the diamine component and the tetracarboxylic acid component, from the viewpoint of the solubility of the resulting polymer, i.e., the polyamic acid alkyl ester, in the solvent. Among these, N,N-dimethylformamide, N,N-diethylformamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-diethylacetamide, 3-methoxy-N,N-dimethylpropanamide, or γ-butyrolactone is preferred. These solvents may be used alone or in combination of two or more.

The concentration of the polyamic acid alkyl ester in the solvent in the reaction is preferably 1 to 30% by mass, since precipitation of the polyamic acid alkyl ester is unlikely to occur. Of these, 5 to 20% by mass is preferable. In addition, in order to prevent hydrolysis of the tetracarboxylic acid diester dichloride, it is preferable that the solvent used to prepare the polyamic acid alkyl ester is as dehydrated as possible. Furthermore, it is preferable to carry out the reaction in a nitrogen atmosphere to prevent the inclusion of outside air.

(3) Production method by reaction of a diamine component with a tetracarboxylic acid diester This method is, for example, a method in which a diamine component and a tetracarboxylic acid diester are subjected to a polycondensation reaction in the presence of a condensing agent, a base and a solvent at 0 to 150° C. (preferably 0 to 100° C.) for 30 minutes to 24 hours (preferably 3 to 15 hours).

Condensing agents that can be used include triphenyl phosphite, dicyclohexylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N,N'-carbonyldiimidazole, dimethoxy-1,3,5-triazinylmethylmorpholinium, O-(benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium tetrafluoroborate, O-(benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and (2,3-dihydro-2-thioxo-3-benzoxazolyl)diphenylphosphonate. The amount of the condensing agent used is preferably 2 to 3 times the molar amount of the tetracarboxylic acid diester, and more preferably 2 to 2.5 times the molar amount.

The base may be a tertiary amine such as pyridine or triethylamine. The amount of base used is preferably an amount that can be easily removed after the polycondensation reaction, and is preferably 2 to 4 times by mole, more preferably 2 to 3 times by mole, relative to the diamine component. From the viewpoint of the solubility of the resulting polymer, i.e., polyamic acid alkyl ester, in the solvent, the solvent used in the polycondensation reaction may be the solvent used in the reaction of the diamine component and the tetracarboxylic acid component. Among these, N,N-dimethylformamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, or γ-butyrolactone is preferred. These solvents may be used alone or in combination of two or more.

In addition, in the polycondensation reaction, the reaction proceeds more efficiently by adding a Lewis acid as an additive. As the Lewis acid, lithium halides such as lithium chloride and lithium bromide are preferred. The amount of Lewis acid used is preferably 0.1 to 10 times the molar amount of the diamine component. Of these, 2.0 to 3.0 times the molar amount is preferred.

When recovering a polyamic acid alkyl ester from a solution of the polyamic acid alkyl ester obtained by the above methods (1) to (3), the reaction solution may be poured into a solvent to cause precipitation. Examples of the solvent used for precipitation include water, methanol, ethanol, 2-propanol, hexane, butyl cellosolve, acetone, and toluene. The polymer precipitated by pouring into the solvent is preferably washed multiple times with the above solvent in order to remove the additives and catalysts used above. After washing and filtration and recovery, the polymer can be dried under normal or reduced pressure, or at normal temperature or by heating. In addition, the polymer precipitated and recovered can be redissolved in a solvent and the reprecipitation and recovery operation repeated 2 to 10 times to reduce impurities in the polymer. The polyamic acid alkyl ester is preferably produced by the above method (2) or (3).

<Other charge transporting substances>
The charge transporting composition of the present invention may contain a conductive polymer such as polythiophene or polyaniline for the purpose of adjusting the charge transporting ability of the charge transport layer.

[Electron-accepting dopant material]
The charge transport composition of the present invention may contain an electron-accepting dopant substance (hereinafter, sometimes simply referred to as a "dopant substance") for the purpose of adjusting the ionization potential or improving the charge transport ability, depending on the application of the resulting thin film.
There are no particular limitations on the dopant substance, so long as it dissolves in at least one solvent used in the charge transporting composition, and both inorganic and organic dopant substances can be used.

As inorganic dopant substances, heteropolyacids are preferred, and specific examples include phosphomolybdic acid, silicomolybdic acid, phosphotungstic acid, phosphotungstomolybdic acid, and silicotungstic acid.

Heteropolyacids are polyacids formed by condensing isopolyacids, which are oxyacids of vanadium (V), molybdenum (Mo), tungsten (W), etc., with oxyacids of different elements, and have a structure in which a heteroatom is located at the center of the molecule, typically represented by the chemical structure of the Keggin type shown in formula (D1) or the Dawson type shown in formula (D2). Examples of oxyacids of different elements include oxyacids of silicon (Si), phosphorus (P), and arsenic (As).

Specific examples of heteropolyacids include phosphomolybdic acid, silicomolybdic acid, phosphotungstic acid, silicotungstic acid, phosphotungstomolybdic acid, etc., which may be used alone or in combination of two or more. The heteropolyacids used in the present invention are commercially available, or may be synthesized by known methods.
In particular, when one type of heteropolyacid is used, the one type of heteropolyacid is preferably phosphotungstic acid or phosphomolybdic acid, and most preferably phosphotungstic acid. When two or more types of heteropolyacids are used, one of the two or more types of heteropolyacids is preferably phosphotungstic acid or phosphomolybdic acid, and more preferably phosphotungstic acid.

Heteropolyacids can be used in the present invention regardless of whether they contain a large or small number of elements in the structure represented by the general formula in quantitative analysis such as elemental analysis, as long as they are commercially available products or have been appropriately synthesized according to known synthesis methods.

That is, for example, phosphotungstic acid is generally _represented by the _chemical formula _H3 ( _PW12O40 ) _nH2O , and phosphomolybdic acid is represented by the chemical formula _H3 ( _PMo12O40 ) _nH2O , but in quantitative analysis, even if the number of P (phosphorus), O (oxygen), W (tungsten), or Mo (molybdenum) in this formula is large or small, they can be used in the present invention as long as they are commercially available or appropriately synthesized according to a known synthesis method. In this case, the mass of the heteropolyacid specified in the present invention does not mean the mass of pure phosphotungstic acid (phosphotungstic acid content) in a synthesized product or a commercially available product, but means the total mass in a state including hydration water and other impurities in a form available as a commercially available product or in a form that can be isolated by a known synthesis method.

When the charge transport composition of the present invention contains a heteropolyacid, the content is preferably about 0.001 to 50 parts by mass per 1 part of the charge transport substance, more preferably about 0.05 to 10 parts, and even more preferably about 0.1 to 5.0 parts.

Also, examples of organic dopant substances include arylsulfonic acid, arylsulfonic acid esters, ionic compounds consisting of a specific anion and its counter cation, borane compounds represented by the formula (Bo1) described below, tetracyanoquinodimethane derivatives, and benzoquinone derivatives. In the present invention, ionic compounds can be preferably used in view of the ease of doping the specific polymer.

As the arylsulfonic acid, a compound represented by the following formula (As1) can be preferably used.

（式中、Ｄ¹は、ナフタレン環またはアントラセン環を表し、Ｄ²は、２～４価のパーフルオロビフェニル基を表し、ｊ¹は、Ｄ¹に結合するスルホン酸基数を表し、１≦ｊ¹≦４を満たす整数であり、ｊ²は、Ｄ²と酸素原子との結合数を示し、２～４を満たす整数である。）

(In the formula, ^D1 represents a naphthalene ring or an anthracene ring, ^D2 represents a divalent to tetravalent perfluorobiphenyl group, ^j1 represents the number of sulfonic acid groups bonded to ^D1 and is an integer satisfying 1≦ ^j1 ≦4, and ^j2 represents the number of bonds between ^D2 and oxygen atoms and is an integer satisfying 2 to 4.)

An example of an arylsulfonic acid that can be suitably used in the present invention is the compound represented by the following formula (As1-1).

The arylsulfonic acid represented by formula (As1) can be synthesized by known methods, for example, by the method described in WO 2006/025342.

When the charge transport composition of the present invention contains an arylsulfonic acid, the content thereof is preferably about 0.001 to 50 parts by mass, more preferably about 0.05 to 10 parts by mass, and even more preferably 0.1 to 5 parts by mass, per 1 part of the charge transport substance.

Examples of the ionic compound include metal salts and onium salts composed of an anion represented by the following formula (An1) or ^Za and its counter cation.

（式中、Ｅは長周期型周期表の第１３族に属する元素を表し、Ａｒ^a1～Ａｒ^a4は、互いに独立して、置換基を有してもよい芳香族炭化水素基または置換基を有してもよい芳香族複素環基を表す。）

(In the formula, E represents an element belonging to Group 13 of the long form periodic table, and Ar ^a1 to Ar ^a4 each independently represent an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent.)

In formula (An1), E is preferably boron or gallium, among the elements belonging to Group 13 of the long-form periodic table, and more preferably boron.

In formula (An1), examples of the aromatic hydrocarbon group and aromatic heterocyclic group include monovalent groups derived from a 5- or 6-membered monocycle or 2- to 4-condensed rings. Among these, from the viewpoints of the stability and heat resistance of the compound, monovalent groups derived from a benzene ring, a naphthalene ring, a pyridine ring, a pyrazine ring, a pyridazine ring, a pyrimidine ring, a triazine ring, a quinoline ring, and an isoquinoline ring are preferred.
Furthermore, it is more preferable that at least one of the groups Ar ^a1 to Ar ^a4 has one or more fluorine or chlorine atoms as a substituent. In particular, it is most preferable that Ar ^a1 to Ar ^a4 are perfluoroaryl groups in which all of the hydrogen atoms are substituted with fluorine atoms. Specific examples of perfluoroaryl groups include pentafluorophenyl, heptafluoro-2-naphthyl, and tetrafluoro-4-pyridyl groups.

Examples of Z ^a include an ion represented by the following formula (An2), a hydroxide ion, a fluoride ion, a chloride ion, a bromide ion, an iodide ion, a cyanide ion, a nitrate ion, a nitrite ion, a sulfate ion, a sulfite ion, a perchlorate ion, a perbromate ion, a periodate ion, a chlorate ion, a chlorite ion, a hypochlorite ion, a phosphate ion, a phosphite ion, a hypophosphite ion, a borate ion, an isocyanate ion, a hydrosulfide ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a hexachloroantimonate ion; a carboxylate ion such as an acetate ion, a trifluoroacetate ion, and a benzoate ion; a sulfonate ion such as a methanesulfonic acid ion and a trifluoromethanesulfonate ion; and an alkoxy ion such as a methoxy ion and a t-butoxy ion.

（式中、Ｅ²は、長周期型周期表の第１５族に属する元素を表し、Ｘⁿ¹は、フッ素原子、塩素原子、臭素原子などのハロゲン原子を表す。）

(In the formula, ^E2 represents an element belonging to Group 15 of the long form periodic table, and ^Xn1 represents a halogen atom such as a fluorine atom, a chlorine atom, or a bromine atom.)

In formula (An2), ^E2 is preferably a phosphorus atom, an arsenic atom, or an antimony atom, and from the standpoint of compound stability, ease of synthesis and purification, and toxicity, a phosphorus atom is preferred.
From the standpoint of compound stability and ease of synthesis and purification, X ⁿ¹ is preferably a fluorine atom or a chlorine atom, and most preferably a fluorine atom.

On the other hand, as the counter cation, a metal ion or an onium ion can be suitably used.
The metal ion is preferably a monovalent metal ion, such as Li ⁺ , Na ⁺ , K ⁺ or Ag ⁺ , with Ag ⁺ being particularly preferred.
Examples of the onium ion include an iodonium ion, a sulfonium ion, an ammonium ion, and a phosphonium ion. In particular, an iodonium ion represented by the following formula (Ct1) is preferred.

In formula (Ct1), R ¹⁰¹ and R ¹⁰² each independently represent an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 2 to 20 carbon atoms, which may be substituted with a halogen atom, a cyano group, a nitro group, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 2 to 20 carbon atoms.

As the counter cation, an ion represented by the following formula (Ct1') can also be used.

In formula (Ct1'), A ⁴ represents an element in the third period or later (third to sixth periods) of the periodic table, and an element belonging to group 16 of the long-form periodic table. Among these, in the present invention, from the viewpoints of electron accepting property and easy availability, an element in the fifth period or earlier (third to fifth periods) of the periodic table is preferred. That is, A ⁴ is preferably any one of a sulfur atom, a selenium atom, and a tellurium atom, and more preferably a sulfur atom.

R ¹⁰³ represents an organic group bonded to A ⁴ via a carbon atom, and R ¹⁰⁴ and R ¹⁰⁵ each independently represent any substituent. Two or more adjacent groups among R ¹⁰³ to R ¹⁰⁵ may be bonded to each other to form a ring.

R ¹⁰³ is not particularly limited in type as long as it is an organic group having a carbon atom at the bonding portion with A ⁴ , as long as it does not go against the spirit of the present invention. The molecular weight of R ¹⁰³ , including its substituent, is usually 1,000 or less, preferably 500 or less. Preferred examples of R ¹⁰³ include alkyl groups, alkenyl groups, alkynyl groups, aromatic hydrocarbon groups, and aromatic heterocyclic groups, from the viewpoint of delocalizing the positive charge. Among them, aromatic hydrocarbons or aromatic heterocyclic groups are preferred, since they delocalize the positive charge and are thermally stable.

Aromatic hydrocarbon groups are monovalent groups derived from a 5- or 6-membered single ring or 2- to 5-condensed rings, and can delocalize a positive charge on the group. Specific examples include monovalent groups derived from a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, and a fluorene ring. More specific examples include a phenyl group, a tolyl group, a 1-naphthyl group, a 2-naphthyl group, a 1-anthryl group, a 2-anthryl group, a 9-anthryl group, a 1-phenanthryl group, a 2-phenanthryl group, a 3-phenanthryl group, a 4-phenanthryl group, and a 9-phenanthryl group, with the phenyl group and the tolyl group being preferred, and the tolyl group being more preferred.

Aromatic heterocyclic groups include monovalent groups derived from a 5- or 6-membered single ring or 2-4 condensed rings, and groups that can delocalize a positive charge on the group. Specific examples of such rings include monovalent groups derived from a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, a triazole ring, an imidazole ring, an oxadiazole ring, an indole ring, a carbazole ring, a pyrroloimidazole ring, a pyrrolopyrazole ring, a pyrrolopyrrole ring, a thienopyrrole ring, a thienothiophene ring, a furopyrrole ring, a furofuran ring, a thienofuran ring, a benzisoxazole ring, a benzisothiazole ring, a benzimidazole ring, a pyridine ring, a pyrazine ring, a pyridazine ring, a pyrimidine ring, a triazine ring, a quinoline ring, an isoquinoline ring, a cinnoline ring, a quinoxaline ring, a phenanthridine ring, a benzimidazole ring, a pyrimidine ring, a quinazoline ring, a quinazolinone ring, and an azulene ring.

The alkyl group may be linear, branched or cyclic, and typically has 1 or more carbon atoms and typically has 12 or less, preferably 6 or less. Specific examples include methyl, ethyl, n-propyl, 2-propyl, n-butyl, isobutyl, tert-butyl and cyclohexyl groups.

The alkenyl group typically has 2 or more carbon atoms, and typically has 12 or less carbon atoms, and preferably has 6 or less carbon atoms. Specific examples include vinyl groups, allyl groups, and 1-butenyl groups.

Alkynyl groups generally have 2 or more carbon atoms, and generally 12 or less, preferably 6 or less. Specific examples include ethynyl and propargyl groups.

R ¹⁰⁴ and R ¹⁰⁵ are not particularly limited as long as they are not contrary to the gist of the present invention. The molecular weight of R ¹⁰⁴ and R ¹⁰⁵ , including the value of its substituent, is usually 1,000 or less, preferably 500 or less. Examples of R ¹⁰⁴ and R ¹⁰⁵ include an alkyl group, an alkenyl group, an alkynyl group, an aromatic hydrocarbon group, an aromatic heterocyclic group, an amino group, an alkoxy group, an aryloxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylcarbonyloxy group, an alkylthio group, an arylthio group, a sulfonyl group, an alkylsulfonyl group, an arylsulfonyl group, a cyano group, a hydroxyl group, a thiol group, and a silyl group. Among them, an organic group having a carbon atom at the bond portion with A ⁴ is preferred from the viewpoint of high electron accepting property, similar to R ¹⁰³ , and for example, an alkyl group, an alkenyl group, an alkynyl group, an aromatic hydrocarbon group, and an aromatic heterocyclic group are preferred. In particular, aromatic hydrocarbon groups and aromatic heterocyclic groups are preferred because they have a large electron-accepting ability and are thermally stable.

Examples of the alkyl group, alkenyl group, alkynyl group, aromatic hydrocarbon group and aromatic heterocyclic group include those described above for R ¹⁰³ .

Examples of the amino group include an alkylamino group, an arylamino group, and an acylamino group. Examples of the alkylamino group include an alkylamino group having one or more alkyl groups, usually having one or more carbon atoms and usually having 12 or less, preferably 6 or less. Specific examples include a methylamino group, a dimethylamino group, a diethylamino group, and a dibenzylamino group.

Arylamino groups include arylamino groups having one or more aromatic hydrocarbon groups or aromatic heterocyclic groups, each of which usually has 3 or more carbon atoms, preferably 4 or more carbon atoms, and usually has 25 or less carbon atoms, preferably 15 or less carbon atoms. Specific examples include phenylamino groups, diphenylamino groups, tolylamino groups, pyridylamino groups, and thienylamino groups.

The acylamino group includes an acylamino group having one or more acyl groups, which usually has 2 or more carbon atoms and usually has 25 or less, preferably 15 or less carbon atoms. Specific examples include an acetylamino group and a benzoylamino group.

The alkoxy group typically has 1 or more carbon atoms and typically has 12 or less carbon atoms, preferably 6 or less carbon atoms. Specific examples include methoxy, ethoxy, and butoxy groups.

Aryloxy groups include aryloxy groups having an aromatic hydrocarbon group or aromatic heterocyclic group, usually having 3 or more carbon atoms, preferably 4 or more carbon atoms, and usually having 25 or less carbon atoms, preferably 15 or less carbon atoms. Specific examples include phenyloxy groups, naphthyloxy groups, pyridyloxy groups, and thienyloxy groups.

The acyl group typically has 1 or more carbon atoms and typically has 25 or less carbon atoms, preferably 15 or less carbon atoms. Specific examples include a formyl group, an acetyl group, and a benzoyl group.

Examples of alkoxycarbonyl groups include those having carbon atoms of typically 2 or more and typically 10 or less, and preferably 7 or less. Specific examples include methoxycarbonyl and ethoxycarbonyl groups.

Aryloxycarbonyl groups include those having an aromatic hydrocarbon group or aromatic heterocyclic group with a carbon number of typically 3 or more, preferably 4 or more, and typically 25 or less, preferably 15 or less. Specific examples include a phenoxycarbonyl group and a pyridyloxycarbonyl group.

Examples of alkylcarbonyloxy groups include alkylcarbonyloxy groups that typically have 2 or more carbon atoms and typically have 10 or less carbon atoms, preferably 7 or less carbon atoms. Specific examples include an acetoxy group and a trifluoroacetoxy group.

The alkylthio group typically has 1 or more carbon atoms and typically has 12 or less carbon atoms, preferably 6 or less carbon atoms. Specific examples include methylthio and ethylthio groups.

Arylthio groups include those having carbon atoms of typically 3 or more, preferably 4 or more, and typically 25 or less, preferably 14 or less. Specific examples include phenylthio groups, naphthylthio groups, and pyridylthio groups.

Specific examples of alkylsulfonyl groups and arylsulfonyl groups include mesyl groups and tosyl groups.

Specific examples of sulfonyloxy groups include mesyloxy and tosyloxy groups.

Specific examples of silyl groups include trimethylsilyl and triphenylsilyl groups.

The groups exemplified as R ¹⁰³ , R ¹⁰⁴ and R ¹⁰⁵ above may be further substituted with other substituents as long as they do not go against the spirit of the present invention. The type of the substituent is not particularly limited, and examples thereof include halogen atoms, cyano groups, thiocyano groups and nitro groups in addition to the groups exemplified as R ¹⁰³ , R ¹⁰⁴ and R ¹⁰⁵ above. Among them, from the viewpoint of not interfering with the heat resistance and electron-accepting ability of the ionic compound (electron-accepting ionic compound), alkyl groups, alkenyl groups, alkynyl groups, alkoxy groups, aryloxy groups, aromatic hydrocarbon groups or aromatic heterocyclic groups are preferred.

Among the above, ionic compounds that are combinations of anions and cations as shown in the following formulas (AC1) to (AC7) (see Patent No. 5381931) can be preferably used.

Furthermore, onium borate salts (which are electrically neutral salts) consisting of a monovalent or divalent anion represented by formula (An3) and a counter cation represented by formulas (Ct2) to (Ct6) can also be suitably used.

In the formula, Ar's each independently represent an aryl group which may have a substituent or a heteroaryl group which may have a substituent, and L represents an alkylene group, -NH-, an oxygen atom, a sulfur atom or -CN ⁺ -.

Aryl groups include aryl groups having 6 to 20 carbon atoms. Specific examples include phenyl, tolyl, 1-naphthyl, 2-naphthyl, 1-anthryl, 2-anthryl, 9-anthryl, 1-phenanthryl, 2-phenanthryl, 3-phenanthryl, 4-phenanthryl, and 9-phenanthryl groups, with phenyl, tolyl, and naphthyl groups being preferred.

The above-mentioned substituents include halogen atoms, nitro groups, cyano groups, alkyl groups having 1 to 20 carbon atoms, alkenyl groups having 2 to 20 carbon atoms, and alkynyl groups having 2 to 20 carbon atoms.

Halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc., with fluorine atoms being preferred.

The alkyl group having 1 to 20 carbon atoms may be linear, branched, or cyclic. Specific examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, and n-eicosanyl groups. However, alkyl groups having 1 to 18 carbon atoms are preferred, and alkyl groups having 1 to 8 carbon atoms are more preferred.

Specific examples of alkenyl groups having 2 to 20 carbon atoms include ethenyl, n-1-propenyl, n-2-propenyl, 1-methylethenyl, n-1-butenyl, n-2-butenyl, n-3-butenyl, 2-methyl-1-propenyl, 2-methyl-2-propenyl, 1-ethylethenyl, 1-methyl-1-propenyl, 1-methyl-2-propenyl, n-1-pentenyl, n-1-decenyl, and n-1-eicosenyl.

Specific examples of alkynyl groups having 2 to 20 carbon atoms include ethynyl, n-1-propynyl, n-2-propynyl, n-1-butynyl, n-2-butynyl, n-3-butynyl, 1-methyl-2-propynyl, n-1-pentynyl, n-2-pentynyl, n-3-pentynyl, n-4-pentynyl, 1-methyl-n-butynyl, 2-methyl-n-butynyl, 3-methyl-n-butynyl, 1,1-dimethyl-n-propynyl, n-1-hexynyl, n-1-decynyl, n-1-pentadecinyl, and n-1-eicosynyl.

Furthermore, among the above-mentioned substituents, the aryl group preferably has one or more electron-withdrawing groups. Examples of the electron-withdrawing groups include halogen atoms, nitro groups, and cyano groups, with halogen atoms being preferred and fluorine atoms being particularly preferred.

Heteroaryl groups preferably include heteroaryl groups having 2 to 20 carbon atoms. Specific examples thereof include oxygen-containing heteroaryl groups such as 2-thienyl, 3-thienyl, 2-furanyl, 3-furanyl, 2-oxazolyl, 4-oxazolyl, 5-oxazolyl, 3-isoxazolyl, 4-isoxazolyl, and 5-isoxazolyl groups; sulfur-containing heteroaryl groups such as 2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 3-isothiazolyl, 4-isothiazolyl, and 5-isothiazolyl groups; 2-imidazolyl, a aryl group, a 4-imidazolyl group, a 2-pyridyl group, a 3-pyridyl group, a 4-pyridyl group, a 2-pyrazyl group, a 3-pyrazyl group, a 5-pyrazyl group, a 6-pyrazyl group, a 2-pyrimidyl group, a 4-pyrimidyl group, a 5-pyrimidyl group, a 6-pyrimidyl group, a 3-pyridazyl group, a 4-pyridazyl group, a 5-pyridazyl group, a 6-pyridazyl group, a 1,2,3-triazin-4-yl group, a 1,2,3-triazin-5-yl group, a 1,2,4-triazin-3-yl group, a 1,2, 4-triazin-5-yl group, 1,2,4-triazin-6-yl group, 1,3,5-triazin-2-yl group, 1,2,4,5-tetrazin-3-yl group, 1,2,3,4-tetrazin-5-yl group, 2-quinolinyl group, 3-quinolinyl group, 4-quinolinyl group, 5-quinolinyl group, 6-quinolinyl group, 7-quinolinyl group, 8-quinolinyl group, 1-isoquinolinyl group, 3-isoquinolinyl group, 4-isoquinolinyl group, 5-isoquinolinyl group, 6-isoquinolinyl group, Examples of nitrogen-containing heteroaryl groups include isoquinolinyl group, 7-isoquinolinyl group, 8-isoquinolinyl group, 2-quinoxanyl group, 5-quinoxanyl group, 6-quinoxanyl group, 2-quinazolinyl group, 4-quinazolinyl group, 5-quinazolinyl group, 6-quinazolinyl group, 7-quinazolinyl group, 8-quinazolinyl group, 3-cinnolinyl group, 4-cinnolinyl group, 5-cinnolinyl group, 6-cinnolinyl group, 7-cinnolinyl group, and 8-cinnolinyl group.

The substituents on the heteroaryl group include the same substituents as those exemplified for the aryl group.

L represents an alkylene group, --NH--, an oxygen atom, a sulfur atom or --CN.sup. ⁺ --, with --CN.sup. ⁺ -- being preferred.

The alkylene group may be linear, branched, or cyclic, and includes alkylene groups having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms. Specific examples include methylene, methylmethylene, dimethylmethylene, ethylene, trimethylene, propylene, tetramethylene, pentamethylene, and hexamethylene groups.

Anions of the above formula (An3) that can be suitably used in the present invention include, but are not limited to, those represented by formula (An3-1).

On the other hand, examples of counter cations include those represented by formulas (Ct2) to (Ct6).

In the present invention, the above onium borate salts may be used alone or in combination of two or more.
If necessary, other known onium borate salts may be used in combination.
The onium borate salt can be synthesized by referring to the known method described in, for example, JP-A-2005-314682.

The onium borate salt may be dissolved in an organic solvent in advance in order to facilitate dissolution in the charge transporting composition.
Examples of such organic solvents include carbonates such as propylene carbonate, ethylene carbonate, 1,2-butylene carbonate, dimethyl carbonate, and diethyl carbonate; ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, and 2-heptanone; polyhydric alcohols and derivatives thereof such as ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, dipropylene glycol, and the monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether, and monophenyl ether of dipropylene glycol monoacetate; cyclic ethers such as dioxane; and formic acid. Examples of the esters include ethyl, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, methyl acetoacetate, ethyl acetoacetate, ethyl pyruvate, ethyl ethoxyacetate, methyl methoxypropionate, ethyl ethoxypropionate, methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, methyl 2-hydroxy-3-methylbutanoate, 3-methoxybutyl acetate, and 3-methyl-3-methoxybutyl acetate; and aromatic hydrocarbons such as toluene, xylene, 3-phenoxytoluene, 4-methoxytoluene, methyl benzoate, cyclohexylbenzene, tetralin, and isophorone. These may be used alone or in combination of two or more.
When an organic solvent is used, the proportion of the organic solvent used is preferably 15 to 1,000 parts by mass, and more preferably 30 to 500 parts by mass, per 100 parts by mass of the onium borate salt.

In addition, when an ionic compound is contained in the charge transport composition of the present invention, the content thereof is preferably about 0.001 to 50 parts by mass, more preferably about 0.05 to 10 parts by mass, and even more preferably about 0.1 to 5 parts by mass, per 1 part of the charge transport substance.

The borane compound represented by formula (Bo1) can be the compound represented by the following formula:

（式中、Ａｒ^b1～Ａｒ^b3は、互いに独立して、置換基を有してもよい芳香族炭化水素基または置換基を有してもよい芳香族複素環基を表す。）

(In the formula, Ar ^b1 to Ar ^b3 each independently represent an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent.)

In formula (Bo1), examples of the aromatic hydrocarbon group and aromatic heterocyclic group include the same as those exemplified in formula (An1).
Furthermore, it is more preferable that at least one of the groups Ar ^b1 to Ar ^b3 has one or more fluorine or chlorine atoms as a substituent. In particular, it is most preferable that Ar ^b1 to Ar ^b3 are perfluoroaryl groups in which all of the hydrogen atoms are substituted with fluorine atoms. Specific examples of perfluoroaryl groups include a pentafluorophenyl group, a heptafluoro-2-naphthyl group, and a tetrafluoro-4-pyridyl group.

Specific examples of borane compounds represented by the above formula (Bo1) include, but are not limited to, those shown below.

The borane compound may be dissolved in an organic solvent in advance to facilitate dissolution in the charge transport composition. Examples of such organic solvents include carbonates such as propylene carbonate, ethylene carbonate, 1,2-butylene carbonate, dimethyl carbonate, and diethyl carbonate; ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, and 2-heptanone; polyhydric alcohols and derivatives thereof such as ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, dipropylene glycol, and monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether, and monophenyl ether of dipropylene glycol monoacetate; cyclic ethers such as dioxane; and formic acid. Examples of the esters include ethyl, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, methyl acetoacetate, ethyl acetoacetate, ethyl pyruvate, ethyl ethoxyacetate, methyl methoxypropionate, ethyl ethoxypropionate, methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, methyl 2-hydroxy-3-methylbutanoate, 3-methoxybutyl acetate, and 3-methyl-3-methoxybutyl acetate; and aromatic hydrocarbons such as toluene, xylene, 3-phenoxytoluene, 4-methoxytoluene, methyl benzoate, cyclohexylbenzene, tetralin, and isophorone. These may be used alone or in combination of two or more.
When an organic solvent is used, the proportion of the organic solvent used is preferably 15 to 1,000 parts by mass, and more preferably 30 to 500 parts by mass, per 100 parts by mass of the borane compound.

In addition, when the charge transport composition of the present invention contains a borane compound, the content thereof is preferably about 0.001 to 50 parts by mass, more preferably about 0.05 to 10 parts by mass, and even more preferably about 0.1 to 5 parts by mass, per 1 part of the charge transport substance.

Specific examples of the tetracyanoquinodimethane derivative include tetracyanoquinodimethanes such as 7,7,8,8-tetracyanoquinodimethane (TCNQ), 2-fluoro-7,7,8,8-tetracyanoquinodimethane, and 2,5-difluoro-7,7,8,8-tetracyanoquinodimethane, and halotetracyanoquinodimethanes (haloTCNQs) such as tetrafluoro-7,7,8,8-tetracyanoquinodimethane.
Specific examples of the benzoquinone derivative include tetrafluoro-1,4-benzoquinone, tetrachloro-1,4-benzoquinone (chloranil), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), and the like.
These inorganic and organic dopant substances may be used alone or in combination of two or more.

Also, examples of halotetracyanoquinodimethane compounds include compounds represented by formula (Tq1).

In the formula, R ^1q to R ^4q each independently represent a hydrogen atom or a halogen atom, at least one of them is a halogen atom, preferably at least two of them are halogen atoms, more preferably at least three of them are halogen atoms, and most preferably all of them are halogen atoms.
Examples of the halogen atom include the same as those mentioned above, but a fluorine atom or a chlorine atom is preferred, and a fluorine atom is more preferred.

Specific examples of halotetracyanoquinodimethane compounds include tetrafluorotetracyanoquinodimethane (F4TCNQ), tetrachlorotetracyanoquinodimethane, 2-fluorotetracyanoquinodimethane, 2-chlorotetracyanoquinodimethane, 2,5-difluorotetracyanoquinodimethane, and 2,5-dichlorotetracyanoquinodimethane, with F4TCNQ being the most suitable in the present invention.

When the charge transport composition of the present invention contains a halotetracyanoquinodimethane compound, the content thereof is preferably about 0.001 to 50 parts by mass, more preferably about 0.05 to 10 parts by mass, and even more preferably about 0.1 to 5 parts by mass, per 1 part of the charge transport substance.

[Organic solvent]
The charge transporting composition generally takes the form of a coating liquid in order to form a uniform thin film. The charge transporting composition of the present invention is also preferably a coating liquid containing the above-mentioned polymer component and an organic solvent capable of dissolving the polymer component.

The organic solvent contained in the charge transport composition is not particularly limited as long as it dissolves the polymer components uniformly. Specific examples include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylsulfoxide, N,N-diethylformamide, N,N-diethylformamide, 3-methoxy-N,N-dimethylpropanamide, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, etc. Among these, it is preferable to use N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, or γ-butyrolactone.

In addition to the above-mentioned solvents, the organic solvent contained in the charge transport composition of the present invention may also be a solvent that improves the coatability of the charge transport composition when applied and the surface smoothness of the coating film. Specific examples of such organic solvents are listed below, but are not limited to these.

For example, ethanol, isopropyl alcohol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, isopentyl alcohol, tert-pentyl alcohol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol ethanol, 2-heptanol, 3-heptanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 2,6-dimethyl-4-heptanol, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1, 5-pentanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, diisopropyl ether, dipropyl ether, dibutyl ether, dihexyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 2-pentanone, 3-pentanone, 2-hexanone, 2-heptanone, 4-heptanone, 2,6-dimethyl-4-heptanone, 4,6-dimethyl-2-heptanone, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene Carbonate, ethylene carbonate, 2-(methoxymethoxy)ethanol, ethylene glycol monobutyl ether (butyl cellosolve), ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, 2-(hexyloxy)ethanol, furfuryl alcohol, diethylene glycol, propylene glycol, propylene glycol monobutyl ether, 1-(butoxyethoxy)propanol, propylene glycol monomethyl ether acetate, dipropylene glycol, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol Examples of the lactic acid lactate include glycerol monoacetate, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene glycol acetate, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, and isoamyl lactate.

Among these, it is preferable to use the following organic solvents: 1-hexanol, cyclohexanol, 1,2-ethanediol, 1,2-propanediol, propylene glycol monobutyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monobutyl ether (butyl cellosolve), or dipropylene glycol dimethyl ether.

These organic solvents can be used alone or in combination of two or more. The type and content of such organic solvents are appropriately selected depending on the coating device, coating conditions, coating environment, etc. of the charge transport composition.

The charge transport composition of the present invention may contain an organosilane compound to improve the stability of the resulting photoelectric conversion element.

As the organic silane compound, alkoxysilane is preferred, and trialkoxysilane and tetraalkoxysilane are more preferred. Examples of the alkoxysilane include tetraethoxysilane (TEOS), tetramethoxysilane, tetraisopropoxysilane, phenyltriethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, dimethyldiethoxysilane, and dimethyldimethoxysilane. Among these, TEOS, tetramethoxysilane, and tetraisopropoxysilane can be preferably used in the present invention. These organic silane compounds can be used alone or in combination of two or more.

The content of the organosilane compound is preferably 0.1 to 10 times, more preferably 0.5 to 7 times, and even more preferably 1.0 to 5 times, the charge transport substance, or, if an electron-accepting dopant substance is included, the total amount of the charge transport substance and the electron-accepting dopant substance, in parts by mass. By setting the amount of the organosilane compound within the above range, the stability of the resulting photoelectric conversion element can be improved.

The composition of the present invention may contain other additives as long as the object of the present invention can be achieved.
The type of additive can be appropriately selected from known additives depending on the desired effect.

The solids concentration of the charge transport composition of the present invention is appropriately set taking into consideration the viscosity and surface tension of the composition and the thickness of the thin film to be produced, but is usually preferably about 0.1 to 20.0 mass%, more preferably 0.5 to 10.0 mass%, and even more preferably 1.0 to 5.0 mass%. The solids in the solids concentration here refer to the components other than the solvent contained in the charge transport composition of the present invention.

The viscosity of the charge transport composition of the present invention is adjusted appropriately according to the coating method, taking into account the thickness of the thin film to be produced and the solids concentration, but is usually about 0.1 to 50 mPa·s at 25°C.

The charge transport composition of the present invention can be prepared by mixing the charge transport material, the electron accepting dopant material, and the organic solvent, and, if necessary, the organosilane compound and other additives, in any order, so long as the solid content is uniformly dissolved or dispersed in the solvent. That is, for example, a method of dissolving a specific polymer as the charge transport material in an organic solvent and then dissolving the electron accepting dopant material in the solution, a method of dissolving the electron accepting dopant material in an organic solvent and then dissolving the specific polymer in the solution, or a method of mixing the specific polymer and the electron accepting dopant material and then putting the mixture into a solvent to dissolve can all be used as long as the solid content is uniformly dissolved or dispersed in the solvent.

The charge transport composition is usually prepared in an inert gas atmosphere at room temperature and pressure, but it may be prepared in air (in the presence of oxygen) or with heating, as long as the compounds in the composition are not decomposed or the composition does not change significantly.

The hole collection layer of the present invention can be formed by applying and baking the charge transport composition described above onto the anode in the case of an inverted stacking type perovskite solar cell, or onto the active layer in the case of a normal stacking type perovskite solar cell. The preferred embodiment of the present invention is the inverted stacking type.
For application, the viscosity and surface tension of the composition, the desired thickness of the thin film, and the like may be taken into consideration, and an optimum method may be selected from various wet process methods such as drop casting, spin coating, blade coating, dip coating, roll coating, bar coating, die coating, inkjet printing, printing methods (relief printing, intaglio printing, planographic printing, screen printing, and the like).
Generally, the coating is carried out under an inert gas atmosphere at room temperature and normal pressure. However, as long as the compounds in the composition are not decomposed or the composition is not significantly changed, the coating may be carried out under air atmosphere (in the presence of oxygen) or while heating.

The film thickness is not particularly limited, but in any case, it is preferably about 0.1 to 500 nm, and more preferably about 1 to 100 nm. Methods for changing the film thickness include changing the solids concentration in the composition and changing the amount of solution when applied.

Hereinafter, a method for producing a perovskite solar cell using the charge transporting composition of the present invention as a composition for forming a hole collection layer will be described, but the present invention is not limited thereto.
(1) Inverted stacking type perovskite solar cell [Formation of anode layer]: A process of forming a layer of an anode material on the surface of a transparent substrate to manufacture a transparent electrode. As the anode material, inorganic oxides such as indium tin oxide (ITO) and indium zinc oxide (IZO), metals such as gold, silver, and aluminum, and highly charge transporting organic compounds such as polythiophene derivatives and polyaniline derivatives can be used. Among these, ITO is the most preferable. As the transparent substrate, a substrate made of glass or transparent resin can be used.
The method for forming the layer of the anode material (anode layer) is appropriately selected depending on the properties of the anode material. In general, in the case of a poorly soluble or poorly dispersible sublimable material, a dry process such as a vacuum deposition method or a sputtering method is selected, while in the case of a solution material or a dispersion material, an optimal method is selected from the above-mentioned various wet processes taking into consideration the viscosity and surface tension of the composition, the desired thickness of the thin film, and the like.

A commercially available transparent anode substrate can also be used, and in this case, from the viewpoint of improving the yield of the device, it is preferable to use a substrate that has been subjected to a smoothing treatment. When a commercially available transparent anode substrate is used, the method for producing a perovskite solar cell of the present invention does not include a step of forming an anode layer.
When forming a transparent anode substrate using an inorganic oxide such as ITO as the anode material, it is preferable to wash the substrate with detergent, alcohol, pure water, etc. before laminating an upper layer. Furthermore, it is preferable to perform a surface treatment such as UV ozone treatment or oxygen plasma treatment immediately before use. When the anode material is mainly composed of an organic substance, it is not necessary to perform the surface treatment.

[Formation of hole-collecting layer]: Step of forming a hole-collecting layer on the formed layer of anode material According to the above-mentioned method, a hole-collecting layer is formed on the layer of anode material using the charge-transporting composition of the present invention.

[Formation of Active Layer]: Step of forming an active layer on the formed hole-collecting layer In the present invention, an active layer containing a perovskite semiconductor compound is used as the active layer.
The perovskite semiconductor compound refers to a semiconductor compound having a perovskite structure. As the perovskite semiconductor compound, a known compound can be used, and is not particularly limited, but examples thereof include those represented by the general formula A ⁺ M ²⁺ X ^- ₃ and those represented by the general formula A ⁺ ₂ M ²⁺ X ^- _4. Here, A ⁺ represents a monovalent cation, M ²⁺ represents a divalent cation, and X ^- represents a monovalent anion.

Examples of the monovalent cation A ⁺ include cations containing elements of Groups 1 and 13 to 16 of the periodic table. Among these, a cesium ion, a rubidium ion, an ammonium ion which may have a substituent, or a phosphonium ion which may have a substituent is preferable.

Examples of ammonium ions that may have a substituent include primary ammonium ions and secondary ammonium ions. There are no particular limitations on the substituents, but alkylammonium ions and arylammonium ions are preferred. In particular, monoalkylammonium ions that form a three-dimensional crystal structure are more preferred in order to avoid steric hindrance. The number of carbon atoms in the alkyl group contained in the alkylammonium ion is preferably 1 to 30, more preferably 1 to 20, and even more preferably 1 to 10. The number of carbon atoms in the aryl group contained in the arylammonium ion is preferably 6 to 30, more preferably 6 to 20, and even more preferably 6 to 12.

Specific examples of the monovalent cation A ⁺ include methylammonium ion, ethylammonium ion, isopropylammonium ion, n-propylammonium ion, isobutylammonium ion, n-butylammonium ion, t-butylammonium ion, dimethylammonium ion, diethylammonium ion, phenylammonium ion, benzylammonium ion, phenethylammonium ion, guanidinium ion, formamidinium ion, acetamidinium ion, and imidazolium ion, etc. The above cation A ⁺ can be used alone or in combination of two or more.

The divalent cation M ²⁺ is preferably a divalent metal cation or semimetal cation, and more preferably a cation of Group 14 of the periodic table. Specific examples of the divalent cation M include lead cation (Pb ²⁺ ), tin cation (Sn ²⁺ ), germanium cation (Ge ²⁺ ), etc. In the present invention, it is preferable to include a lead cation from the viewpoint of obtaining a photoelectric conversion element with excellent stability. The above cation M ²⁺ can be used alone or in combination of two or more kinds.

Examples of the monovalent anion X ⁻ include a halide ion, an acetate ion, a nitrate ion, an acetylacetonate ion, a thiocyanate ion, and a 2,4-pentanedionate ion, and the like, with a halide ion being preferred. The above anion X ⁻ can be used alone or in combination of two or more kinds.

Halide ions include chloride ions, bromide ions, iodide ions, and the like. In the present invention, it is preferable to include iodide ions in order to prevent the band gap of the semiconductor from becoming too wide.

As the perovskite semiconductor compound, for example, an organic-inorganic perovskite semiconductor compound is preferable, and a halide-based organic-inorganic perovskite semiconductor compound is more preferable. Specific examples of perovskite semiconductor compounds include MAPbI3, _MAPbBr3 , _MAPbCl3 , _MASnI3 , _MASnBr3 , _MASnCl3 , MAPbI _{( 3-x) Clx ,} MAPbI(3-x)Brx, MAPbBr _{(3-x) Clx} , MAPb _{(1-y) SnyI3} , MAPb _{(1-y) SnyBr3 ,} MAPb _{(1-y) SnyCl3} , MAPb _{( 1-y) SnyI} ( _{3 -x) Clx} , MAPb _{(1-y) SnyI (3-x) Brx ,} MAPb _{(1-y) SnyBr (3-x) Clx} , and FAPbI3 _. , _FAPbBr3 , FAPbI _{(3-x) Brx} , FA _{(1-V) MAVPbI (3-x) Brx} , Cs _{(1-WV) FAwMAVPbI (3-x) Brx} . In addition, MA represents _{methylammonium} ( _CH3NH3 ⁺ ), and FA represents formamidinium (NH= _{CHNH2 +} ). In addition, x represents ^an arbitrary number from 0 to 3, and y represents an arbitrary number from 0 to 1.

From the viewpoint of improving photoelectric conversion efficiency, it is preferable to use a semiconductor compound having an energy band gap of 1.0 to 3.5 eV as the perovskite semiconductor compound.

The active layer may contain two or more kinds of perovskite semiconductor compounds. For example, the active layer may contain two or more kinds of perovskite semiconductor compounds that are different in at least one of A ⁺ , M ²⁺ , and X ⁻ .

The content of the perovskite semiconductor compound in the active layer is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, from the viewpoint of obtaining good photoelectric conversion characteristics. There is no particular upper limit, but it is usually 100% by mass or less.

As with the above, the method for forming the active layer is determined by taking into consideration the viscosity and surface tension of the composition, the desired thickness of the thin film, etc., and selecting the most suitable method from the various wet process methods mentioned above.

[Formation of Electron Collecting Layer]: Step of Forming an Electron Collecting Layer on the Formed Active Layer If necessary, an electron collecting layer may be formed between the active layer and the cathode layer for the purpose of improving the efficiency of charge transfer, etc.
Materials for forming the electron collection layer include fullerenes, lithium oxide (Li ₂ O), magnesium oxide (MgO), alumina (Al ₂ O ₃ ), lithium fluoride (LiF), sodium fluoride (NaF), magnesium fluoride (MgF ₂ ), strontium fluoride (SrF ₂ ), cesium carbonate (Cs ₂ CO ₃ ), 8-quinolinol lithium salt (Liq), 8-quinolinol sodium salt (Naq), bathocuproine (BCP), 4,7-diphenyl-1,10-phenanthroline (BPhen), polyethyleneimine (PEI), ethoxylated polyethyleneimine (PEIE), etc.

Fullerenes are preferably fullerenes and their derivatives, but are not particularly limited thereto. Specific examples include fullerenes and their derivatives having a basic skeleton of C60, C70, C76, C78, C84, etc. In fullerene derivatives, the carbon atoms in the fullerene skeleton may be modified with any functional group, and these functional groups may be bonded to each other to form a ring. Fullerene derivatives include fullerene-bonded polymers. Fullerene derivatives that have functional groups with high affinity to solvents and are highly soluble in solvents are preferred.

Functional groups in fullerene derivatives include, for example, hydrogen atoms, hydroxyl groups, halogen atoms such as fluorine atoms and chlorine atoms, alkyl groups such as methyl groups and ethyl groups, alkenyl groups such as vinyl groups, alkoxy groups such as cyano groups, methoxy groups and ethoxy groups, aromatic hydrocarbon groups such as phenyl groups and naphthyl groups, and aromatic heterocyclic groups such as thienyl groups and pyridyl groups. Specific examples include hydrogenated fullerenes such as C60H36 and C70H36, oxide fullerenes such as C60 and C70, and fullerene metal complexes. As fullerene derivatives, it is more preferable to use [6,6]-phenyl C61 butyric acid methyl ester ([60]PCBM) or [6,6]-phenyl C71 butyric acid methyl ester ([70]PCBM).

As for the method of forming the electron collection layer, similarly to the above, when the electron collection material is a sparingly soluble sublimable material, the various dry processes mentioned above are selected, and when it is a solution material or dispersion material, the viscosity and surface tension of the composition, the desired thin film thickness, etc. are taken into consideration and the optimum one is selected from the various wet process methods mentioned above.

[Formation of cathode layer]: a step of forming a cathode layer on the formed electron collection layer. Examples of cathode materials include metals such as aluminum, magnesium-silver alloy, aluminum-lithium alloy, lithium, sodium, potassium, cesium, calcium, barium, silver, and gold; inorganic oxides such as indium tin oxide (ITO) and indium zinc oxide (IZO); and organic compounds with high charge transport properties such as polythiophene derivatives and polyaniline derivatives. A plurality of cathode materials can be used by stacking or mixing them.
As for the method of forming the cathode layer, similarly to the above, when the cathode layer material is a poorly soluble or poorly dispersible sublimable material, the various dry processes described above are selected, and when the cathode layer material is a solution material or dispersion material, an optimal one is adopted from the various wet processes described above, taking into consideration the viscosity and surface tension of the composition, the desired thickness of the thin film, and the like.

[Formation of Carrier Block Layer]
If necessary, a carrier block layer may be provided between any layers for the purpose of controlling the rectification of photocurrent, etc. When a carrier block layer is provided, usually, an electron block layer is inserted between the active layer and the hole collecting layer or the anode, and a hole block layer is inserted between the active layer and the electron collecting layer or the cathode, but this is not limited thereto.
Examples of materials for forming the hole blocking layer include titanium oxide, zinc oxide, tin oxide, bathocuproine (BCP), and 4,7-diphenyl-1,10-phenanthroline (BPhen).
Examples of materials for forming the electron blocking layer include triarylamine-based materials such as N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (α-NPD) and poly(triarylamine) (PTAA).

As for the method of forming the carrier block layer, similarly to the above, when the carrier block layer material is a poorly soluble or poorly dispersible sublimable material, the various dry processes mentioned above are selected, and when it is a solution material or dispersion material, the viscosity and surface tension of the composition, the desired thin film thickness, etc. are taken into consideration and the optimum one is selected from the various wet process methods mentioned above.

(2) Normal stacking type perovskite solar cell [Formation of cathode layer]: A step of forming a layer of a cathode material on the surface of a transparent substrate to manufacture a transparent cathode substrate. In addition to those exemplified as the reverse stacking type anode materials above, examples of the cathode material include fluorine-doped tin oxide (FTO). Examples of the transparent substrate include those exemplified as the reverse stacking type anode materials above.
As for the method of forming the layer of the cathode material (cathode layer), in the case of a poorly soluble or poorly dispersible sublimable material, the above-mentioned dry process is selected, and in the case of a solution material or dispersion material, an optimum one is adopted from among the various wet processes described above, taking into consideration the viscosity and surface tension of the composition, the desired thickness of the thin film, and the like.
In this case, a commercially available transparent cathode substrate can be suitably used, and from the viewpoint of improving the yield of the device, it is preferable to use a substrate that has been subjected to a smoothing treatment. When a commercially available transparent cathode substrate is used, the method for producing a perovskite solar cell of the present invention does not include a step of forming a cathode layer.
When an inorganic oxide is used as the cathode material to form a transparent cathode substrate, the substrate may be subjected to the same cleaning treatment and surface treatment as in the case of the inversely laminated anode material.

[Formation of Electron Collecting Layer]: Step of forming an electron collecting layer on the formed cathode If necessary, an electron collecting layer may be formed between the active layer and the cathode layer for the purpose of improving the efficiency of charge transfer, etc.
Examples of materials for forming the electron collection layer include zinc oxide (ZnO), titanium oxide (TiO), tin oxide (SnO), and the like, in addition to the above-mentioned examples of the inversely laminated type materials.
As for the method of forming the electron collection layer, in the case of a poorly soluble or poorly dispersible sublimable material, the above-mentioned dry process is selected, and in the case of a solution material or dispersion material, an optimum one is selected from the above-mentioned various wet process methods taking into consideration the viscosity and surface tension of the composition, the desired thickness of the thin film, etc. Also, a method can be used in which an inorganic oxide precursor layer is formed on the cathode using a wet process (particularly a spin coating method or a slit coating method), and then baked to form an inorganic oxide layer.

[Formation of Active Layer]: Step of forming an active layer on the formed electron-collecting layer An active layer containing the above-mentioned perovskite semiconductor compound is formed as the active layer.
The method for forming the active layer is the same as that described for the inverted laminate type active layer.

[Formation of hole-collecting layer]: Step of forming a hole-collecting layer on the layer of active layer material formed According to the above-mentioned method, a hole-collecting layer is formed on the layer of active layer material using the composition of the present invention.

[Formation of anode layer]: a step of forming an anode layer on the formed hole collection layer. Examples of the anode material include the same materials as those for the above-mentioned reverse stack-type anode material, and the method for forming the anode layer is also the same as that for the reverse stack-type cathode layer.

[Formation of Carrier Block Layer]
As in the inverted stack type element, a carrier block layer may be provided between any layers as necessary for the purpose of controlling the rectification of the photocurrent.
The materials for forming the hole blocking layer and the materials for forming the electron blocking layer are the same as those described above, and the method for forming the carrier blocking layer is also the same as above.

The perovskite solar cell element produced by the method exemplified above can be introduced back into the glove box and sealed in an inert gas atmosphere such as nitrogen to prevent element deterioration due to atmospheric air, and in the sealed state it can be allowed to function as a solar cell or the solar cell characteristics can be measured.
Examples of the sealing method include a method in which a concave glass substrate with a UV-curable resin attached to the edge is attached to the film-forming surface of the perovskite solar cell element in an inert gas atmosphere and the resin is cured by UV irradiation, and a method in which a film-sealing type sealing is performed by a technique such as sputtering in a vacuum.

The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

＜ジアミン＞
　下記式ＤＡ－１～ＤＡ－４で表されるジアミン化合物

＜溶媒＞
　ＮＥＰ：Ｎ－エチル－２－ピロリドン
　ＢＣＳ：ブチルセロソルブ
＜電子受容性ドーパント物質＞
　下記式ＤＰ－１～ＤＰ－４で表される電子受容性ドーパント物質

The abbreviations used in the preparation of the charge transport composition are as follows.
<Synthesis of polyimide precursor>
<Tetracarboxylic acid dianhydride>
Tetracarboxylic acid dianhydrides represented by the following formulae MS-1 to MS-5

<Diamine>
Diamine compounds represented by the following formulae DA-1 to DA-4

<Solvent>
NEP: N-ethyl-2-pyrrolidone BCS: Butyl cellosolve <electron-accepting dopant substance>
Electron-accepting dopant substances represented by the following formulas DP-1 to DP-4

The conditions for measuring the molecular weight of the polyimide precursor (polyamic acid) are as follows.
Apparatus: Room temperature gel permeation chromatography (GPC) apparatus (SSC-7200) manufactured by Senshu Scientific Co., Ltd.
Column: Shodex column (KD-803, KD-805)
Column temperature: 50°C
Eluent: N,N'-dimethylformamide (additives: lithium bromide hydrate (LiBr.H ₂ O) 30 mmol/L, phosphoric acid anhydrous crystal (o-phosphoric acid) 30 mmol/L, tetrahydrofuran (THF) 10 ml/L)
Flow rate: 1.0 ml/min. Standard samples for preparing calibration curves: TSK standard polyethylene oxide (molecular weights: approximately 900,000, 150,000, 100,000, and 30,000) manufactured by Tosoh Corporation, and polyethylene glycol (molecular weights: approximately 12,000, 4,000, and 1,000) manufactured by Polymer Laboratory.

The conditions for measuring the viscosity of the polyimide precursor solution (polyamic acid solution) are as follows.
The measurements were performed using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample volume of 1.1 mL, a cone rotor TE-1 (1°34′, R24), and a temperature of 25° C.

[Synthesis Example 1]
MS-1 (3.36 g, 13.4 mmol) and DA-1 (6.63 g, 14 mmol) were dissolved in NEP (89.94 g) and reacted at 40° C. for 20 hours to obtain a polyamic acid solution (A1).
The viscosity of the resulting polyamic acid solution was 72 mPa·s, and the number average molecular weight of this polyamic acid was 9,500 and the weight average molecular weight was 42,300.

[Synthesis Example 2]
MS-1 (3.53 g, 14.1 mmol) and DA-2 (6.32 g, 15 mmol) were dissolved in NEP (88.66 g) and reacted at 40° C. for 20 hours to obtain a polyamic acid solution (A2).
The viscosity of the resulting polyamic acid solution was 101 mPa·s, and the number average molecular weight of this polyamic acid was 10,100 and the weight average molecular weight was 52,200.

[Synthesis Example 3]
MS-1 (4.71 g, 18.8 mmol) and DA-3 (3.98 g, 20 mmol) were dissolved in NEP (78.2 g) and reacted at 40° C. for 24 hours to obtain a polyamic acid solution (A3).
The viscosity of the resulting polyamic acid solution was 86.3 mPa·s, and the number average molecular weight of this polyamic acid was 10,120 and the weight average molecular weight was 26,357.

[Synthesis Example 4]
MS-1 (4.70 g, 16.3 mmol) and DA-4 (4.27 g, 20 mmol) were dissolved in NEP (80.73 g) and reacted at 40° C. for 24 hours to obtain a polyamic acid solution (A4).
The viscosity of the resulting polyamic acid solution was 100 mPa·s, and the number average molecular weight of this polyamic acid was 9,442 and the weight average molecular weight was 38,736.

[Synthesis Example 5]
MS-2 (9.41 g, 47.51 mmol) and DA-3 (9.96 g, 50 mmol) were dissolved in NEP (77.50 g) and reacted at 25° C. for 6 hours to obtain a polyamic acid solution (A5).
The viscosity of the resulting polyamic acid solution was 1,350 mPa·s, and the number average molecular weight of this polyamic acid was 7,831 and the weight average molecular weight was 16,975.

[Synthesis Example 6]
MS-3 (3.61 g, 18.4 mmol) and DA-3 (3.99 g, 20 mmol) were dissolved in NEP (87.32 g) and reacted at 25° C. for 4 hours to obtain a polyamic acid solution (A6).
The viscosity of the resulting polyamic acid solution was 56.5 mPa·s, and the number average molecular weight of this polyamic acid was 7,984 and the weight average molecular weight was 20,233.

[Synthesis Example 7]
MS-4 (4.01 g, 18.4 mmol) and DA-3 (3.99 g, 20 mmol) were dissolved in NEP (91.98 g) and reacted at 25° C. for 6 hours to obtain a polyamic acid solution (A7).
The viscosity of the resulting polyamic acid solution was 80.4 mPa·s, and the number average molecular weight of this polyamic acid was 7,631 and the weight average molecular weight was 16,587.

[Synthesis Example 8]
MS-5 (4.42 g, 14.1 mmol) and DA-3 (2.99 g, 15 mmol) were dissolved in NEP (83.60 g) and reacted at 25° C. for 6 hours to obtain a polyamic acid solution (A8).
The viscosity of the resulting polyamic acid solution was 29.7 mPa·s, and the number average molecular weight of this polyamic acid was 5,240 and the weight average molecular weight was 10,625.

<Preparation of Charge Transport Composition>
[Example 1-1]
6 g of NEP and 2 g of BCS were added to 2 g of the polyamic acid solution (A1) obtained in Synthesis Example 1, and the mixture was stirred at 25° C. for 1 hour to obtain solution 1. Separately, 200 mg of DP-1 was dissolved in a mixed solvent of 7.84 g of NEP and 1.96 g of BCS to obtain solution 2. Solutions 1 and 2 were mixed so that the mass ratio of DP-1 to charge transporting substance 1 was 0.2, and the mixture was filtered through a syringe filter having a pore size of 0.45 μm to obtain a charge transporting composition (B1a) having a polyamic acid concentration of 2.0 mass %.

[Examples 1-2 to 1-4]
Charge transport compositions (B1b) to (B1d) were obtained in the same manner as in Example 1-1, except that the electron-accepting dopant substance DP-1 was changed to DP-2 to DP-4. The concentration of the polyamic acid in each charge transport composition was adjusted to 2.0% by mass.

[Examples 2-1 to 8-4]
The polyamic acid solution and the dopant substance were changed based on the composition shown in Table 1 below.
Charge transporting compositions B2a to B8d were obtained in the same manner as in Example 1-1.

[Comparative Example 1]
6 g of NEP and 2 g of BCS were added to 2 g of the polyamic acid solution (A1) obtained in Synthesis Example 1, and the mixture was stirred for 1 hour at 25° C. The mixture was filtered through a syringe filter having a pore size of 0.45 μm to obtain a charge transporting composition (C1) having a polyamic acid concentration of 2.0 mass %.

[Comparative Examples 1 to 8]
Charge transport compositions (C2) to (C8) were obtained in the same manner as in Comparative Example 1, except that the polyamic acid solution (A1) was changed to the polyamic acid solutions (A2) to (A8) obtained in Synthesis Examples 2 to 8, respectively.

[Comparative Example 9]
2.48 g of pure water was added to 1.92 g of Clevios P (a 1.3 mass% aqueous solution of PEDOT:PSS manufactured by Heraeus Corporation), and the mixture was stirred for 1 hour at 25° C. The mixture was filtered through a syringe filter having a pore size of 0.45 μm to obtain a charge transport composition (C9) having a concentration of 0.50 mass%.

The ink compositions of charge transport compositions B1a to B8d and charge transport compositions C1 to C9 are summarized in Table 1 below.

<Preparation of organic photoelectric conversion element>
The equipment used is as follows:
(1) Glove box: VAC glove box system manufactured by Yamahachi Bussan Co., Ltd. (2) Evaporation equipment: Vacuum deposition equipment manufactured by Aoyama Engineering Co., Ltd. (3) Solar simulator: OTENTOSUN-III, AM1.5G filter manufactured by Bunkoukeiki Co., Ltd., radiation intensity: 100 mW/cm ²
(4) Source measure unit: Keithley Instruments, Inc., 2612A

[Preparation of active layer precursor liquid]
[Preparation Example 1]
In a glove box, 504 mg of formamidinium iodide, 65 mg of methylammonium bromide, 1,487 mg of lead (II) iodide, and 214 mg of lead (II) bromide were added to a vial. Next, 2,346 μL of dimethyl sulfoxide (DMSO) and 586 μL of N,N-dimethylformamide were added, and the mixture was heated and stirred at 70° C. for 15 minutes to dissolve the mixture. Furthermore, 134 μL of a cesium iodide solution dissolved in DMSO to a concentration of 1.5 mol/L was added to prepare active layer precursor liquid 1.

[Preparation of Coating Solution for Electron Collection Layer]
[Preparation Example 2]
150 mg of [6,6]-phenyl-C ₆₁ -methyl acetate (manufactured by Frontier Carbon Co., Ltd.) was added to a vial, and 5,000 μL of chlorobenzene was further added and stirred for 15 minutes to prepare coating solution 1 for the charge collection layer.

[Preparation Example 3]
2.5 mg of bathocuproine (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the vial, and 5,000 μL of 2-propanol (manufactured by Kanto Chemical Co., Ltd.) was further added and stirred for 1 hour to prepare coating solution 2 for charge collection layer.

[Fabrication of photoelectric conversion element]
[Example 9-1]
A 25 mm x 25 mm glass substrate on which an ITO transparent conductive layer serving as an anode was patterned into a 10 mm x 25 mm stripe shape was subjected to UV/ozone treatment for 15 minutes. The charge transport composition B1a prepared in Example 1-1 was dropped onto this substrate and applied by spin coating (SC). A hole collection layer was formed by heating on a hot plate at 100°C for 10 minutes. The thickness of the hole collection layer was about 30 nm.
The substrate was introduced into a glove box, and the active layer precursor liquid 1 obtained in Preparation Example 1 was dropped onto the formed hole collection layer and applied by SC. Chlorobenzene was dropped onto the substrate in SC. The obtained substrate was heated on a hot plate at 105° C. for 30 minutes to form an active layer. The film thickness of the active layer was about 400 nm.
The coating liquid 1 for electron collection layer obtained in Preparation Example 2 was applied by SC onto the formed active layer. The substrate was heated at 100° C. for 10 minutes on a hot plate. The coating liquid 2 for electron collection layer obtained in Preparation Example 3 was further applied by SC onto the substrate to form an electron collection layer. The thickness of the layer obtained from the coating liquid 1 for electron collection layer was about 30 nm, and the thickness of the layer obtained from the coating liquid 2 for electron collection layer was about 8 nm.
Finally, the substrate on which the above layers were laminated was placed in a vacuum deposition apparatus, and the apparatus was evacuated until the degree of vacuum inside the apparatus reached 1 x ^10-3 Pa or less. A silver layer to serve as the cathode was evaporated to a thickness of 100 nm using a resistance heating method, thereby producing a photoelectric conversion element D1a having an area of 8 mm x 3 mm at the intersection of the striped ITO layer and the silver layer.

[Examples 9-2 to 16-3, Comparative Examples 10 to 18]
Photoelectric conversion elements D1b to D8c and photoelectric conversion elements E1 to E9 were obtained in the same manner as in Example 9-1, except that the charge transporting composition B1a used in forming the hole collection layer was changed to charge transporting compositions B1b to B8c and charge transporting compositions C1 to C9, respectively.

Table 2 below summarizes the photoelectric conversion elements D1a to D8c and the photoelectric conversion elements E1 to E9 and the charge transport compositions used.

<Element characteristic evaluation>
The short-circuit current density (Jsc [mA/ ^cm2 ]), open circuit voltage (Voc [V]), fill factor (FF), and conversion efficiency (PCE [%]) were measured for the photoelectric conversion elements D1a to D8d and E1 to E9 prepared above. The PCE [%] results for each photoelectric conversion element are shown in Table 2. The PCE [%] was calculated using the following formula:
PCE [%] = Jsc [mA/cm ² ] × Voc [V] × FF ÷ Incident light intensity (100 [mW/cm ² ]) × 100

When comparing the PCE of each photoelectric conversion element, the photoelectric conversion element using a charge transport composition containing an electron-accepting dopant substance exhibited a higher PCE than the photoelectric conversion element that did not. Furthermore, the charge transport composition of the present invention exhibited a higher PCE than PEDOT:PSS, a commonly used charge transport composition.

The reason for the improvement in PCE due to the addition of an electron-accepting dopant substance is unclear, but it is speculated that this is due to an increase in carrier density in the charge transport composition caused by interaction between the secondary or tertiary amine in the polyamic acid and the electron-accepting dopant substance. The increase in carrier density is thought to have enabled the efficient extraction of holes generated in the active layer, improving the PCE.

Claims (11)

A charge transporting composition for forming a charge transporting thin film in an organic photoelectric conversion element, comprising:
A charge transporting material, an electron accepting dopant material, and an organic solvent are included,
The charge transporting material is a charge transporting composition comprising at least one polyimide polymer selected from the group consisting of a polyimide precursor obtained from a diamine component having a structure represented by any one of the following formulas (1) to (3) and a tetracarboxylic acid component, an ester of the polyimide precursor, and an imidized product of the polyimide precursor:

(In the formula, ^R1 represents a hydrogen atom or a monovalent organic group. * represents a bonding site to another group. Any hydrogen atom forming a benzene ring may be substituted with a monovalent organic group.) 2. The charge transporting composition according to claim 1, wherein the electron accepting dopant substance is a salt comprising an anion represented by the following formula (An1) and its counter cation:

(In the formula, E represents an element belonging to Group 13 of the long form periodic table, and Ar ^a1 to Ar ^a4 each independently represent an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent.) The charge transport composition according to claim 2, wherein the salt is an onium salt. The charge transport composition according to claim 2, wherein the content of the electron-accepting dopant substance is 0.001 to 50 parts by mass per 1 part by mass of the charge transport substance. 2. The charge transporting composition according to claim 1, wherein R ¹ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a fluoroalkyl group having 1 to 5 carbon atoms, or a tert-butoxycarbonyl group. The charge transport composition according to any one of claims 1 to 5, which is used for a hole collection layer of a perovskite photoelectric conversion element. A charge transporting thin film obtained from the charge transporting composition according to any one of claims 1 to 5. The charge transport thin film according to claim 7, wherein the charge transport thin film is a hole collection layer of a perovskite photoelectric conversion element. A perovskite photoelectric conversion element comprising the charge transport thin film according to claim 8. The perovskite photoelectric conversion element according to claim 9, which is of the inverted stacking type. A solar cell comprising the perovskite photoelectric conversion element according to claim 9.