JP2022108268A - Organic thin film used for photoelectric conversion element, and photoelectric conversion element thereof - Google Patents

Abstract

To provide an organic thin film for use in a photoelectric conversion element using a compound having excellent heat resistance and charge transport properties, and various photoelectric conversion elements to which the organic thin film is applied, especially an imaging device, and a light sensor using the same.SOLUTION: There is provided an organic thin film for use in a photoelectric conversion element, containing a compound represented by the following formula (1). (In the formula, A represents a single bond, a divalent group such as a substituted or unsubstituted aromatic hydrocarbon, Ar1 to Ar3 represent a substituted or unsubstituted aromatic hydrocarbon group, and R1 to R13 represent a hydrogen atom, etc.)SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to an organic thin film used in a photoelectric conversion device and the photoelectric conversion device thereof, and more specifically, an organic thin film containing a compound having an indolotriphenylene structure and various photoelectric conversion devices to which the organic thin film is applied. , and in particular to imaging devices.

Photoelectric conversion elements are widely used in solar cells, light sensors, etc. Among them, image sensors, which are imaging elements, are used not only for television cameras and smartphone cameras, but also for driving support systems. Both markets are expanding.

Until now, inorganic materials such as Si films and Se films have been used as materials for image sensors, and there are two imaging methods: a three-plate type that uses a prism to separate colors, and a single-plate type that uses color filters. was mainstream. However, although the three-plate type has a high light utilization rate, it is difficult to miniaturize because it uses a prism. Resolution and light utilization were poor (Non-Patent Document 1).

Organic matter absorbs light of specific wavelengths better than inorganic matter, so by combining materials that match each wavelength, it is possible to efficiently use each light for each of the three primary colors without using a prism. can be constructed. Therefore, light utilization efficiency is high, and it is possible to manufacture a small-sized imaging device. In addition, it is possible to add values such as flexibility and large area by coating in the production process, which cannot be achieved with inorganic materials (Non-Patent Document 2).

For this reason, photoelectric conversion elements using organic substances are expected to be developed into next-generation imaging elements, and several reports have been made. For example, an example of using a quinacdrine or quinazoline derivative in a photoelectric conversion device (Patent Document 1), an example of using a benzothienobenzothiophene derivative in a photoelectric conversion device (Patent Document 2), an example of using indolocarbazole in a photoelectric conversion device ( Patent Document 3) and the like. It is generally believed that the performance of an organic image pickup device is improved by aiming at high contrast and power saving, and aiming at reduction of dark current. In order to reduce dark current, a method of inserting a hole blocking layer or an electron blocking layer between the photoelectric conversion portion and the electrode portion may be used.

The insertion of this hole blocking layer or electron blocking layer is a technique commonly used in the field of organic electronics. It is placed at the interface of the film other than the film, and the required charge moves quickly while controlling the back migration of holes or electrons.

Thermal stability is another property required for the material used for the block layer. In particular, image sensors have higher thermal stability than other organic electronic devices in order to consider application to manufacturing processes that involve heating processes such as the installation of color filters, the installation of protective films, and the soldering of elements, as well as to improve storage stability. Desired. Patent Document 4 reports that the use of an electron blocking material having a glass transition temperature (Tg) of 140° C. or higher improves the thermal stability of the device. However, this proposed compound has a problem of reduced hole transport ability due to steric hindrance.

Japanese Patent No. 4945146 JP 2018-170487 A JP 2018-085427 A JP 2011-187937 A KR-A-200050897

Institute of Image Information, Media Association Journal, 60, 3, 291 (2006) Adv. Mater. 28, 4766 (2016)

The present invention has been made in view of the above-mentioned current situation, and provides an organic thin film for use in a photoelectric conversion device by utilizing a compound having excellent heat resistance and charge transport properties, and applying the organic thin film. An object of the present invention is to provide various photoelectric conversion elements, particularly an imaging element, and an optical sensor using the same.

Therefore, in order to achieve the above object, the present inventors focused on the fact that the indolotriphenylene ring skeleton has a high charge transport property and is excellent in heat resistance, and aimed at further improvement in heat resistance. As a result, the present inventors have found that an organic thin film containing a compound having a specific indorotriphenylene ring structure can solve the above problems, and have completed the present invention.

That is, the present invention relates to the following items.
1) An organic thin film for use in a photoelectric conversion device, containing a compound represented by the following formula (1).

（式中、Ａは、単結合、置換若しくは無置換の芳香族炭化水素の２価基、置換若しくは無置換の芳香族複素環の２価基又は置換若しくは無置換の縮合多環芳香族の２価基を表し、
Ａｒ_１～Ａｒ_３は、相互に同一でも異なってもよく、置換若しくは無置換の芳香族炭化水素基、置換若しくは無置換の芳香族複素環基又は置換若しくは無置換の縮合多環芳香族基を表し、
ＡとＡｒ_２、ＡとＡｒ_３、及びＡｒ_２とＡｒ_３は、単結合、置換若しくは無置換のメチレン基、酸素原子又は硫黄原子を介して互いに結合して環を形成してもよく、
Ｒ_１～Ｒ_１３は、相互に同一でも異なってもよく、水素原子、重水素原子、フッ素原子、塩素原子、シアノ基、ニトロ基、置換基を有していてもよい炭素原子数１ないし６の直鎖状若しくは分岐状のアルキル基、置換基を有していてもよい炭素原子数５ないし１０のシクロアルキル基、置換基を有していてもよい炭素原子数２ないし６の直鎖状若しくは分岐状のアルケニル基、置換基を有していてもよい炭素原子数１ないし６の直鎖状若しくは分岐状のアルキルオキシ基、置換基を有していてもよい炭素原子数５ないし１０のシクロアルキルオキシ基、置換若しくは無置換の芳香族炭化水素基、置換若しくは無置換の芳香族複素環基、置換若しくは無置換の縮合多環芳香族基又は置換若しくは無置換のアリールオキシ基を表し、
隣接するＲ_１～Ｒ_１３は、単結合、置換若しくは無置換のメチレン基、酸素原子又は硫黄原子を介して互いに結合して環を形成してもよい。）

(Wherein, A is a single bond, a substituted or unsubstituted aromatic hydrocarbon divalent group, a substituted or unsubstituted aromatic heterocyclic divalent group, or a substituted or unsubstituted condensed polycyclic aromatic divalent group represents a valence group,
Ar ₁ to Ar ₃ , which may be the same or different, are substituted or unsubstituted aromatic hydrocarbon groups, substituted or unsubstituted aromatic heterocyclic groups or substituted or unsubstituted condensed polycyclic aromatic groups. represent,
A and Ar ₂ , A and Ar ₃ , and Ar ₂ and Ar ₃ may be bonded to each other through a single bond, a substituted or unsubstituted methylene group, an oxygen atom or a sulfur atom to form a ring;
R ₁ to R ₁₃ , which may be the same or different, are hydrogen atom, deuterium atom, fluorine atom, chlorine atom, cyano group, nitro group, and optionally substituted carbon atoms of 1 to 6 A linear or branched alkyl group, an optionally substituted cycloalkyl group having 5 to 10 carbon atoms, and an optionally substituted linear chain having 2 to 6 carbon atoms or a branched alkenyl group, an optionally substituted C 1-6 linear or branched alkyloxy group, an optionally substituted C 5-10 represents a cycloalkyloxy group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted condensed polycyclic aromatic group or a substituted or unsubstituted aryloxy group,
Adjacent R ₁ to R ₁₃ may be bonded to each other via a single bond, a substituted or unsubstituted methylene group, an oxygen atom or a sulfur atom to form a ring. )

2) The organic thin film according to 1), wherein the compound represented by the formula (1) is a compound represented by the following formula (2).

（式中のＡ、Ａｒ_１～Ａｒ_３、及びＲ_１～Ｒ_１３は、式（１）中の定義と同一である。）

(A, Ar ₁ to Ar ₃ and R ₁ to R ₁₃ in the formula are the same as defined in formula (1).)

3) The organic thin film according to 1), wherein the compound represented by the formula (1) is a compound represented by the following formula (3).

（式中のＡ、Ａｒ_１～Ａｒ_３、及びＲ_１～Ｒ_１３は、式（１）中の定義と同一である。）

(A, Ar ₁ to Ar ₃ and R ₁ to R ₁₃ in the formula are the same as defined in formula (1).)

4) The organic thin film according to 1), wherein the compound represented by the formula (1) is a compound represented by the following formula (4).

（式中のＡ、Ａｒ_１～Ａｒ_３、及びＲ_１～Ｒ_１３は、式（１）中の定義と同一である。）

(A, Ar ₁ to Ar ₃ and R ₁ to R ₁₃ in the formula are the same as defined in formula (1).)

5) The organic thin film according to 2), wherein the compound represented by the formula (2) is a compound represented by the following formula (5).

（式中、Ａは、式（１）のＡの定義と同じであり、Ａｒは、式（１）のＡｒ_１～Ａｒ_３と同じ定義であり、Ｒ_１～Ｒ_２１は、式（１）のＲ_１～Ｒ_１３と同じ定義である。）

(In the formula, A has the same definition as A in formula (1), Ar has the same definition as Ar ₁ to Ar ₃ in formula (1), and R ₁ to R ₂₁ have the same definition as in formula (1). It is the same definition as R ₁ to R ₁₃ of

6) The organic thin film according to 2), wherein the compound represented by the formula (2) is a compound represented by the following formula (6).

（式中、Ａｒ_１及びＡｒ_２は、式（１）のＡｒ_１～Ａｒ_３と同じ定義であり、Ｒ_１～Ｒ_２０は、式（１）のＲ_１～Ｒ_１３と同じ定義である。）

(In the formula, Ar ₁ and Ar ₂ have the same definitions as Ar ₁ to Ar ₃ in formula (1), and R ₁ to R ₂₀ have the same definitions as R ₁ to R ₁₃ in formula (1). )

7) A photoelectric conversion element in which at least an electrode, a buffer layer, a photoelectric conversion layer and an electrode are laminated in this order, the photoelectric conversion element comprising the organic thin film according to any one of 1) to 6).

8) The photoelectric conversion device according to 7), which contains the organic thin film as a buffer layer.

9) The photoelectric conversion element according to 7), which contains the organic thin film as a photoelectric conversion layer.

10) An imaging device comprising the photoelectric conversion device according to any one of 7) to 9) above.

An organic thin film containing a compound having an indolotriphenylene ring structure represented by formula (1) or the like of the present invention is an organic thin film having excellent heat resistance and charge transport properties, and can be applied to various photoelectric conversion devices. As a result, a photoelectric conversion device, particularly an imaging device, having excellent dark current characteristics and conversion efficiency, and a photosensor using the same can be provided.

It is one structural example of the photoelectric conversion element of this invention.

The present invention relates to an organic thin film containing a compound having an indolotriphenylene ring structure represented by the formula (1) or the like, and a photoelectric conversion device using the organic thin film, which is applied to a photoelectric conversion device. It is.

The term "to" used in the present specification and claims indicates a range. For example, the term "5 to 10" means "5 or more and 10 or less". ranges are inclusive of the numbers themselves.

"Substituted or unsubstituted aromatic hydrocarbon divalent group", "substituted or unsubstituted aromatic heterocyclic bivalent group", or "substituted or unsubstituted condensed polycyclic aromatic group" in the formula (1) The “aromatic hydrocarbon divalent group”, “aromatic heterocyclic divalent group” or “condensed polycyclic aromatic divalent group” in the “bivalent group of a group” include a phenylene group, a biphenylene group, a A phenylene group, a naphthylene group, an anthracenylene group, a thienylene group, a furanylene group, a phenanthrenylene group, and the like can be mentioned. Furthermore, it can also be selected from arylene groups having 6 to 30 carbon atoms and heteroarylene groups having 2 to 30 carbon atoms.

"Aromatic Specific hydrocarbon groups, "aromatic heterocyclic groups" or "condensed polycyclic aromatic groups" include phenyl group, biphenylyl group, terphenylyl group, naphthyl group, anthracenyl group, phenanthrenyl group, fluorenyl group, spirobifluorenyl group, indenyl group, pyrenyl group, perylenyl group, fluoranthenyl group, triphenylenyl group, pyridyl group, pyrimidinyl group, triazinyl group, furyl group, pyrrolyl group, thienyl group, quinolyl group, isoquinolyl group, benzofuranyl group , benzothienyl group, indolyl group, carbazolyl group, benzoxazolyl group, benzothiazolyl group, quinoxalinyl group, benzimidazolyl group, pyrazolyl group, dibenzofuranyl group, dibenzothienyl group, naphthyridinyl group, phenanthrolinyl group, acridinyl group and A carbonyl group and the like can be mentioned. Further, it can be selected from aryl groups having 6 to 30 carbon atoms and heteroaryl groups having 2 to 30 carbon atoms.

"Optionally substituted C 1 to C 6 linear or branched alkyl group", "Optionally substituted C 5 to 10 cycloalkyl group" or "linear or branched chain having 1 to 6 carbon atoms" in "optionally substituted linear or branched alkenyl group having 2 to 6 carbon atoms" Alkyl group", "cycloalkyl group having 5 to 10 carbon atoms" or "linear or branched alkenyl group having 2 to 6 carbon atoms" specifically include methyl group, ethyl group, n -propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group, cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-adamantyl groups, vinyl groups, allyl groups, isopropenyl groups and 2-butenyl groups.

"Optionally substituted C 1 to C 6 linear or branched alkyloxy group" or "optionally substituted C 5 The "linear or branched alkyloxy group having 1 to 6 carbon atoms" or "cycloalkyloxy group having 5 to 10 carbon atoms" in "cycloalkyloxy group having 1 to 10" specifically includes methyl oxy group, ethyloxy group, n-propyloxy group, isopropyloxy group, n-butyloxy group, tert-butyloxy group, n-pentyloxy group, n-hexyloxy group, cyclopentyloxy group, cyclohexyloxy group, cycloheptyloxy group , a cyclooctyloxy group, a 1-adamantyloxy group and a 2-adamantyloxy group.

Specific examples of the "aryloxy group" in the "substituted or unsubstituted aryloxy group" in the formula (1) include a phenyloxy group, a biphenylyloxy group, a terphenylyloxy group, a naphthioxyl group, an anthracene An aryloxy group having 6 to 30 carbon atoms such as a nyloxy group and a phenanthrenyloxy group can be mentioned.

"Substituted aromatic hydrocarbon group", "substituted aromatic heterocyclic group", "substituted condensed polycyclic aromatic group", "substituted methylene group", "having substituents" in the above formula (1) A linear or branched alkyl group having 1 to 6 carbon atoms that may be optionally substituted", "cycloalkyl group having 5 to 10 carbon atoms that may be substituted", " A linear or branched alkenyl group having 2 to 6 carbon atoms which may be substituted", "a linear or branched alkyloxy group having 1 to 6 carbon atoms which may be substituted", or " The "substituent" in the "optionally substituted cycloalkyloxy group having 5 to 10 carbon atoms" specifically includes a deuterium atom, a cyano group, a nitro group; a fluorine atom, a chlorine atom, a bromine halogen atoms such as atoms, iodine atoms; silyl groups such as trimethylsilyl group and triphenylsilyl group; linear or branched alkyl groups having 1 to 6 carbon atoms such as methyl group, ethyl group and propyl group; methyloxy linear or branched alkyloxy groups having 1 to 6 carbon atoms such as groups, ethyloxy groups and propyloxy groups; alkenyl groups such as vinyl groups and allyl groups; aryloxy groups such as phenyloxy groups and tolyloxy groups; Arylalkyloxy groups such as benzyloxy and phenethyloxy; phenyl, biphenylyl, terphenylyl, naphthyl, anthracenyl, phenanthrenyl, fluorenyl, spirobifluorenyl, indenyl, pyrenyl, perylenyl , fluoranthenyl group, triphenylenyl group and other aromatic hydrocarbon groups or condensed polycyclic aromatic groups; pyridyl group, thienyl group, furyl group, pyrrolyl group, quinolyl group, isoquinolyl group, benzofuranyl group, benzothienyl group, indolyl group , a carbazolyl group, a benzoxazolyl group, a benzothiazolyl group, a quinoxalinyl group, a benzimidazolyl group, a pyrazolyl group, a dibenzofuranyl group, a dibenzothienyl group, and an aromatic heterocyclic group such as a carbolinyl group. These substituents may be further substituted with the substituents exemplified above.

In the present invention, from the viewpoint of heat resistance and charge mobility, Ar ₁ to Ar ₃ in the formula (1) are substituted or unsubstituted aromatic hydrocarbon groups or substituted or unsubstituted condensed polycyclic aromatic group, more preferably an unsubstituted aromatic hydrocarbon group or an unsubstituted condensed polycyclic aromatic group. Further, A in the formula (1) is preferably a substituted or unsubstituted aromatic hydrocarbon divalent group, more preferably an unsubstituted aromatic hydrocarbon divalent group.

Further, it is preferable that R ₁ to R ₁₃ in the above formula (1) are hydrogen atoms because of ease of synthesis.

In the present invention, preferred compounds having an indolotriphenylene ring structure represented by the formula (1) include two compounds at the 2- and 3-positions of the indole ring represented by the following formulas (2) to (4). A compound having a structure in which two adjacent carbon atoms of a triphenylene ring are covalently bonded to a carbon atom can be mentioned.

A, Ar ₁ to Ar ₃ and R ₁ to R ₁₃ in formulas (2), (3) and (4) are the same as defined in formula (1).

That is, the "substituted or unsubstituted aromatic hydrocarbon divalent group" and "substituted or unsubstituted aromatic heterocyclic divalent group" in the above formulas (2), (3) and (4) , or "aromatic hydrocarbon divalent group" in "substituted or unsubstituted condensed polycyclic aromatic divalent group", "aromatic heterocyclic divalent group" or "condensed polycyclic aromatic divalent "group" has the same definition as in formula (1).

Further, the "substituted or unsubstituted aromatic hydrocarbon group", "substituted or unsubstituted aromatic heterocyclic group", or "substituted or unsubstituted "Aromatic hydrocarbon group", "aromatic heterocyclic group" or "condensed polycyclic aromatic group" in "substituted condensed polycyclic aromatic group" is the same as defined in formula (1).

In the above formula (2), formula (3) and formula (4), "a linear or branched alkyl group having 1 to 6 carbon atoms which may have a substituent", "having a substituent "1 carbon atom" in "optionally substituted cycloalkyl group having 5 to 10 carbon atoms" or "linear or branched alkenyl group having 2 to 6 carbon atoms which may be substituted" Specific examples of a linear or branched alkyl group having 1 to 6", a "cycloalkyl group having 5 to 10 carbon atoms", or a "linear or branched alkenyl group having 2 to 6 carbon atoms" are It is the same as the specific example given in formula (1).

In the formula (2), formula (3) and formula (4), "a linear or branched alkyloxy group having 1 to 6 carbon atoms optionally having a substituent" or "a substituent A "linear or branched alkyloxy group having 1 to 6 carbon atoms" or a "cycloalkyloxy group having 5 to 10 carbon atoms" in the cycloalkyloxy group having 5 to 10 carbon atoms which may have Specific examples of "group" are the same as the specific examples given in formula (1).

Specific examples of the "aryloxy group" in the "substituted or unsubstituted aryloxy group" in formula (2), formula (3) and formula (4) are the same as the specific examples given in formula (1). be.

Further, the "substituted aromatic hydrocarbon group", "substituted aromatic heterocyclic group", "substituted condensed polycyclic aromatic group", "substituted methylene group", "optionally substituted C1-C6 linear or branched alkyl group", "optionally substituted C5-C10 cycloalkyl group", "optionally substituted C2-C6 linear or branched alkenyl group", "optionally substituted C1-C6 linear Specific examples of the "substituent" in the "cyclic or branched alkyloxy group" or "optionally substituted cycloalkyloxy group having 5 to 10 carbon atoms" are also listed in formula (1). Same as the specific example.

In the present invention, from the viewpoint of heat resistance and charge mobility, Ar ₁ to Ar ₃ in the formulas (2), (3) and (4) are substituted or unsubstituted aromatic hydrocarbon groups, or A substituted or unsubstituted condensed polycyclic aromatic group is preferable, and an unsubstituted aromatic hydrocarbon group or an unsubstituted condensed polycyclic aromatic group is more preferable. Further, A in the formulas (2), (3) and (4) is preferably a substituted or unsubstituted aromatic hydrocarbon divalent group, and an unsubstituted aromatic hydrocarbon divalent group more preferably a group.

Further, it is preferable that R ₁ to R ₁₃ in the above formulas (2), (3) and (4) are hydrogen atoms because of ease of synthesis.

In the present invention, preferred compounds are those in which Ar ₂ and Ar ₃ in the formula (2) are substituted or unsubstituted aromatic hydrocarbon groups or condensed polycyclic aromatic groups, and Ar ₂ and Ar ₃ are single A compound represented by the following formula (5), which is a structure formed by combining with each other via a bond to form a ring, can be mentioned. More specifically, for example, compounds (1-7), (1-15), (1-19), (1-30), (1-66), (1-83), (1-128) described later ).

A in formula (5) has the same definition as A in formula (1), Ar has the same definition as Ar ₁ to Ar ₃ in formula (1), and R ₁ to R ₂₁ have the same definition as in formula (1). Same definition as R ₁ to R ₁₃ . That is, all the substituents related to the formula (5) include the groups exemplified in the explanation of the formula (1).

In the present invention, from the viewpoint of heat resistance and charge mobility, Ar in the formula (5) is a substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted condensed polycyclic aromatic group. It is preferably an unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms or an unsubstituted condensed polycyclic aromatic group, more preferably an unsubstituted condensed polycyclic aromatic group having 10 to 18 carbon atoms. Preferably. Further, A in the formula (5) is preferably a substituted or unsubstituted aromatic hydrocarbon divalent group, and is an unsubstituted aromatic hydrocarbon divalent group having 6 to 18 carbon atoms. is more preferred.

Further, it is preferable that R ₁ to R ₁₃ in the above formula (5) are hydrogen atoms because of easy synthesis.

From the viewpoint of heat resistance and charge mobility, one preferred embodiment of the present invention is a compound in which A in the formula (2) is a substituted or unsubstituted aromatic hydrocarbon divalent group.

For example _, the following formula (6 ) can be mentioned. Specific examples include compounds (1-4), (1-29), (1-50), (1-82) and (1-106) described later.

Ar ₁ and Ar ₂ in formula (6) have the same definitions as Ar ₁ to Ar ₃ in formula (1), and R ₁ to R ₂₀ in formula (6) represent R ₁ to R Same definition as ₁₃ . That is, all the substituents related to the formula (6) include the groups exemplified in the explanation of the formula (1).

In the present invention, from the viewpoint of heat resistance and charge mobility, Ar ₁ and Ar ₂ in the formula (6) are substituted or unsubstituted aromatic hydrocarbon groups or substituted or unsubstituted condensed polycyclic aromatic groups. , more preferably an unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms or an unsubstituted condensed polycyclic aromatic group, particularly an unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms A hydrogen group or an unsubstituted condensed polycyclic aromatic group is preferred. Further, A in the formula (6) is preferably a divalent group of a substituted or unsubstituted aromatic hydrocarbon having 6 to 30 carbon atoms, and an unsubstituted aromatic hydrocarbon having 6 to 18 carbon atoms. A divalent group is more preferred.

Further, it is preferable that R ₁ to R ₁₃ in the above formula (6) are hydrogen atoms because of ease of synthesis.

Among the compounds having an indolotriphenylene ring structure represented by Formula (1), Formula (2), Formula (3), Formula (4), Formula (5) or Formula (6) of the present invention, preferable Specific examples of the compounds are shown below, but the present invention is not limited to these compounds.

A compound having an indolotriphenylene ring structure represented by formula (1) or the like of the present invention can be synthesized by a known method. Specifically, the indolotriphenylene derivative, which is the main skeleton of the compound having the indolotriphenylene ring structure represented by the formula (3) of the present invention, is synthesized, for example, by a method known per se as follows. (See Patent Document 5, for example). Further, the synthesized halogenated indolotriphenylene derivative and the arylamine are subjected to a coupling reaction using a copper catalyst, a palladium catalyst, or the like to obtain the indolotriphenylene ring represented by the formula (3) of the present invention. A compound having a structure can be synthesized.

Similarly, the indolotriphenylene derivative, which is the main skeleton of the compound having the indolotriphenylene ring structure represented by the formula (4) of the present invention, can be synthesized, for example, by a method known per se as follows. (see, for example, Patent Document 5). Further, the synthesized halogenated indolotriphenylene derivative and the arylamine are subjected to a coupling reaction using a copper catalyst, a palladium catalyst, or the like to give the indolotriphenylene ring represented by the formula (4) of the present invention. Amine compounds having the structure can be synthesized.

Purification of the compound having an indolotriphenylene ring structure represented by formula (1) or the like is performed by purification by column chromatography, purification by adsorption using silica gel, activated carbon, activated clay, or the like, recrystallization with a solvent, crystallization, or the like. be able to. Identification of compounds can be performed by NMR analysis. As physical property values, it is preferable to measure the glass transition temperature (Tg) and the work function. The glass transition temperature (Tg) is an index of the stability of the thin film state, and the work function is an index of the hole transportability.

The glass transition point (Tg) can be determined using powder with a high-sensitivity differential scanning calorimeter (DSC3100SA, manufactured by Bruker AXS).

The work function can be obtained by forming a thin film of 100 nm on an ITO substrate and using an ionization potential measurement device (PYS-202, manufactured by Sumitomo Heavy Industries, Ltd.).

A compound having an indolotriphenylene ring structure represented by the formula (1) or the like can form an organic thin film by a known method such as a vapor deposition method, a spin coating method, an inkjet method, or the like. In addition, the compound having an indolotriphenylene ring structure represented by the above formula (1) or the like may be used alone to form a film, but it is also possible to form a film by mixing a plurality of compounds. Furthermore, it can be mixed with other compounds to form a film as long as the effect of the present invention is not impaired.

An organic thin film containing a compound having an indorotriphenylene ring structure represented by formula (1) or the like is suitable for use in a photoelectric conversion device, particularly an imaging device.
The structure of the photoelectric conversion element includes, for example, a first electrode (anode), a first buffer layer, a photoelectric conversion layer, and a second electrode (cathode) in that order, and the first buffer layer has the indorotriphenylene ring structure of the present invention. and a structure that is an organic thin film containing a compound having Layers can be added to such a multi-layer structure, and for example, a structure having a first electrode, a first buffer layer, a photoelectric conversion layer, a second buffer layer, and a second electrode in this order can be employed. Moreover, the organic thin film containing the compound which has an indolotriphenylene ring structure of this invention can also be used for a photoelectric conversion layer.

The photoelectric conversion layer in the photoelectric conversion element of the present invention may be made of an organic material or an inorganic material as long as it can generate signal charges according to the amount of light received. When the photoelectric conversion layer is made of an organic material, the organic semiconductor film may be a single layer or a plurality of layers. Mixed films (bulk heterostructures) of organic semiconductors and n-type organic semiconductors are used. In the case of a plurality of layers, it is a structure in which two or more of a p-type organic semiconductor film, an n-type organic semiconductor film, or a p-type organic semiconductor and n-type organic semiconductor mixed film are laminated, and a buffer is provided between the layers. It is also possible to insert layers.

In the photoelectric conversion device of the present invention, stability against heat load can be obtained by using a compound having an indolotriphenylene ring structure represented by the above formula (1) or the like in the first buffer layer included in the device. can.

The p-type semiconductor used in the photoelectric conversion layer is a donor organic semiconductor, which is mainly represented by a hole-transporting organic compound, and is a compound that easily donates electrons.
Examples of p-type semiconductors include, but are not limited to, naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, tetracene derivatives, pentacene derivatives, quinacridone derivatives, chrysene derivatives, fluoranthene derivatives, phthalocyanine derivatives, subphthalocyanine derivatives, Metal Complexes with Heterocyclic Compounds as Ligands, Benzothiophene Derivatives, Dinaphthothienothiophene Derivatives, Dianthracenothienothiophene Derivatives, Benzobisbenzothiophene Derivatives, Thienobisbenzothiophene, Dibenzothienobisbenzothiophene Derivatives, Dithienobenzone Thienoacene-based materials and triarylamine compounds typified by dithiophene derivatives, dibenzothienodithiophene derivatives, benzodithiophene derivatives, naphthodithiophene derivatives, anthracenodithiophene derivatives, tetracenodithiophene derivatives, and pentacenodithiophene derivatives, Examples include amine derivatives such as carbazole compounds, indenocarbazole derivatives, and the like.

The n-type organic semiconductor used in the photoelectric conversion layer is an acceptor organic semiconductor, which is mainly represented by an electron-transporting organic compound, and refers to an organic compound that easily accepts electrons. More specifically, it refers to an organic compound with a larger electron affinity when two organic compounds are brought into contact with each other. Therefore, any organic compound can be used as the acceptor organic compound as long as it is an electron-accepting organic compound. For example, condensed aromatic carbocyclic compounds (naphthalene, anthracene, fullerene, phenanthrene, tetracene, pyrene, perylene, fluoranthene, or derivatives thereof), 5- to 7-membered heterocyclic compounds containing nitrogen, oxygen and sulfur atoms (e.g. pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, quinoxaline, quinazoline, phthalazine, cinnoline, isoquinoline, pteridine, acridine, phenazine, phenanthroline, tetrazole, pyrazole, imidazole, thiazole, oxazole, indazole, benzimidazole, benzotriazole, benzoxazole, benzothiazole, carbazole, purine, triazolopyridazine, triazolopyrimidine, tetrazaindene, oxadiazole, imidazopyridine, pyraridine, pyrrolopyridine, thiadiazolopyridine, dibenzazepine, tribenzazepine, etc.), polyarylene compounds , fluorene compounds, cyclopentadiene compounds, silyl compounds, and metal complexes having nitrogen-containing heterocyclic compounds as ligands. As described above, any organic compound having a higher electron affinity than the organic compound used as the donor organic compound may be used as the acceptor organic semiconductor.

The anode and cathode are not particularly limited as long as they are conductive materials generally used as electrodes, and examples thereof include metals, metal oxides, metal nitrides, metal borides, organic conductive compounds, and mixtures thereof. Specific examples include conductive metal oxides such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), indium tungsten oxide (IWO), molybdenum oxide (MoO), and titanium oxide. , metal nitrides such as titanium oxynitride (TiN _x O _x ), titanium nitride (TiN), gold (Au), platinum (Pt), silver (Ag), chromium (Cr), nickel (Ni), aluminum (Al ), mixtures or laminates of these metals with conductive metal oxides, organic conductive compounds such as polyaniline, polythiophene and polypyrrole, and laminates of these with ITO.

A second buffer layer may be inserted between the second electrode (cathode) and the photoelectric conversion layer, and the material used for this is preferably a material having a larger work function than the material used for the first buffer layer. . For example, organic molecules and organometallic complexes containing nitrogen-containing heterocycles such as pyridine, quinoline, acridine, indole, imidazole benzimidazole, and phenanthroline, and materials with low absorption in the visible light region are preferred. Further, when forming a thin film having a thickness of about 5 nm to 20 nm, fullerene having absorption in the visible light region and derivatives thereof can be used.

Hereinafter, embodiments of the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples.

[Example 1]
<13-{9-(4-biphenylyl)-9H-carbazol-3-yl}-10-(9-phenanthro)-10H-phenanthro[9,10-b]carbazole: synthesis of compound (1-82)>
A reaction vessel purged with nitrogen was charged with 90.8 g of 2-bromotriphenylene, 71.7 g of benzamide, 1.88 g of copper powder, 4.62 g of sodium sulfite, 5.33 g of 1,10-phenanthroline, 61.3 g of potassium carbonate, and 200 mL of dodecylbenzene. was added and stirred at 180° C. for 8 hours. Toluene was added at 85.degree. This washing was carried out twice to obtain 88.8 g of brown powder of N-2-triphenylenebenzamide (88.1% yield).

88.8 g of N-2-triphenylenebenzamide, 480 mL of isoamyl alcohol, 71.7 g of potassium hydroxide, 18 mL of water, and 18 mL of 1,4-dioxane were added to a nitrogen-purged reactor and stirred at 115° C. for 12.5 hours. The reaction solution was cooled, 35% hydrochloric acid was added to adjust the pH of the solution to 7, and the solution was filtered. The obtained solid was dispersed in a mixed solvent of methanol and water and washed by refluxing. Filtration gave 54.5 g (87.6% yield) of 2-triphenyleneamine as a gray solid.

25.8 g of 2-triphenyleneamine, 30.0 g of 1-bromo-2-iodobenzene, 250 mL of toluene, 0.97 g of tris(dibenzylideneacetone) dipalladium, and 1.32 g of BINAP were added to a reaction vessel purged with nitrogen, and the mixture was heated to 90°C. and stirred for 3 hours. After hot filtration using a filter aid, silica gel was added for adsorption purification. After filtration, the filtrate was concentrated. Hexane was added to precipitate a solid, which was purified by crystallization with toluene/acetone to give 16.3 g of (2-bromophenyl)-2-triphenyleneamine as an ocher solid (38.6% yield). rice field.

39.0 g of (2-bromophenyl)-2-triphenyleneamine, 19.2 g of potassium acetate, 350 mL of dimethylacetamide, and 2.26 g of tetrakis(triphenylphosphine)palladium were added to a reaction vessel purged with nitrogen, and the mixture was stirred at 157° C. for 7 hours. Stirred for 5 hours. After allowing to cool to room temperature, water was added to precipitate a solid. After filtration, the resulting solid was dispersed in a mixed solvent of methanol/water and refluxed for washing, and then dispersed in toluene and refluxed for washing to obtain a gray color of 10H-phenanthro[9,10-b]carbazole. 23.6 g of powder (yield 75.9%) was obtained.

18.7 g of 10H-phenanthro[9,10-b]carbazole, 15.2 g of 9-bromophenanthrene, 0.37 g of copper powder, 1.23 g of sodium sulfite and 1.06 g of 1,10-phenanthroline were placed in a reaction vessel purged with nitrogen. , 12.2 g of potassium carbonate and 30 mL of dodecylbenzene were added, and the mixture was stirred at 215° C. for 15 hours. After standing to cool, chlorobenzene was added and hot filtration was performed at 120°C. Silica gel is added to the filtrate for adsorption purification, and after filtration, the filtrate is concentrated, washed with acetone/methanol, and filtered again to obtain 10-(9-phenanthro)-10H-phenanthro[9,10-b]. 21.9 g (75.5% yield) of light brown powder of carbazole were obtained.

20.9 g of 10-(9-phenanthro)-10H-phenanthro[9,10-b]carbazole and 560 mL of chloroform were added to a reaction vessel purged with nitrogen, completely dissolved at 60° C., and allowed to cool to room temperature. , and N-bromosuccinimide (7.46 g) were added and stirred for 1 hour. 400 mL of water was added, and after liquid separation, anhydrous sodium sulfate was added to the organic layer for dehydration and filtration. After concentrating the filtrate, it was purified by crystallization with toluene/acetone to give 13.1 g of beige powder of 13-bromo-10-(9-phenanthro)-10H-phenanthro[9,10-b]carbazole. (yield 53.9%) was obtained.

7.20 g of 13-bromo-10-(9-phenanthro)-10H-phenanthro[9,10-b]carbazole, 9-(4-biphenylyl)-3-(4,4,5 ,5-tetramethyl-[1,3,2]dioxaboran-2-yl)-9H-carbazole 6.72 g, potassium carbonate 3.48 g, tetrakis(triphenylphosphine)palladium 0.29 g, tetrahydrofuran 720 mL, water 110 mL. The mixture was added and stirred at 65° C. for 9.5 hours. Methanol was added at room temperature to precipitate a solid, the solid obtained by filtration was dissolved in toluene, and silica gel was added for adsorption purification. After filtration, the filtrate is concentrated and purified by crystallization with acetone to give 13-{9-(4-biphenylyl)-9H-carbazol-3-yl}-10-(9-phenanthro)-10H- Phenanthro[9,10-b]carbazole: 7.68 g of pale yellow powder of compound (1-82) was obtained (yield 75.3%).

The structure of the resulting pale yellow powder was identified using NMR.
¹ H-NMR (DMSO-d ₆ ) detected the following 38 hydrogen signals. δ (ppm) = 9.98 (1H), 9.14-9.09 (4H), 8.72-8.69 (3H), 8.39-8.34 (3H), 8.26 (1H ), 8.20-8.18 (1H), 7.99-7.12 (25H).

[Example 2]
<13-(9-Phenyl-9H-carbazol-4′-yl)-10-(9-phenanthro)-10H-phenanthro[9,10-b]carbazole: synthesis of compound (1-83)>
8.50 g of 13-bromo-10-(9-phenanthro)-10H-phenanthro[9,10-b]carbazole, 9-[4-(4,4,5,5-tetramethyl -[1,3,2]dioxaborolan-2-yl)phenyl]-9H-carbazole 6.58 g, potassium carbonate 4.10 g, tetrakis(triphenylphosphine) palladium 0.34 g, tetrahydrofuran 850 mL, and water 130 mL are added, and 65 °C for 11 hours. Methanol was added at room temperature to precipitate a solid, the solid obtained by filtration was dissolved in toluene, and silica gel was added for adsorption purification. After filtration, the filtrate was concentrated, acetone and methanol were added to precipitate a solid, which was purified by crystallization using toluene/acetone and toluene/ethyl acetate to give 13-(9-phenyl-9H-carbazole- 4′-yl)-10-(9-phenanthro)-10H-phenanthro[9,10-b]carbazole: 4.62 g (yield 38.5%) of pale yellow powder of compound (1-83) was obtained. rice field.

The structure of the resulting pale yellow powder was identified using NMR.
¹ H-NMR (CDCl ₃ ) detected the following 34 hydrogen signals. δ (ppm) = 9.61 (1H), 8.97-8.91 (3H), 8.77-8.76 (1H), 8.66-8.61 (2H), 8.32-8 .30 (1H), 8.28 (1H), 8.20-8.18 (2H), 8.15 (1H), 8.02-8.00 (3H), 7.89-7.85 ( 1H), 7.79-7.69 (6H), 7.67-7.63 (1H), 7.58-7.53 (3H), 7.48-7.41 (5H), 7.34 -7.30 (2H), 7.21-7.20 (1H).

[Example 3]
<Measurement of glass transition temperature>
The glass transition temperatures of the compound (1-82) of Example 1 and the compound (1-83) of Example 2 were measured with a high-sensitivity differential scanning calorimeter (DSC3100SA, manufactured by Bruker AXS). Similar measurements were also performed on EBL-1 (see Patent Document 1) and EBL-2 (see Patent Document 3) having the following structures, which are compounds with a high glass transition temperature. The results are summarized in Table 1.

The glass transition temperatures of compound (1-82) and compound (1-83) are as high as 215° C. and 214° C., respectively, indicating that the thin film state is stable. In addition, the glass transition temperatures of compounds (1-82) and (1-83) are higher than those of EBL-1 and EBL-2, and instead of EBL-1 and EBL-2, compounds (1-82) and It can be seen that the use of the compound (1-83) makes it possible to manufacture an element with better thermal stability.

[Example 4]
<Measurement of work function>
Using the compound (1-82) of Example 1 and the compound (1-83) of Example 2, and the comparative compounds EBL-1 and EBL-2, a deposited film having a thickness of 100 nm was formed on an ITO substrate. A substrate for evaluation was produced by Using this substrate for evaluation, the work function was measured with an ionization potential measuring device (Sumitomo Heavy Industries, Ltd., PYS-202). Table 2 summarizes the results.

The compound (1-82) and the compound (1-83) have a work function of 5.3 to 6.0 eV and an energy level equivalent to that of a carbazole compound or the like, which is considered to be a suitable hole-transporting material. It can be seen that it has good hole transport ability.

[Example 5]
<Measurement of hole mobility>
Using the compound (1-82) of Example 1, the compound (1-83) of Example 2, and the comparative compound EBL-2, a film thickness of 3 to 4 μm is formed on a glass substrate with ITO by a vacuum deposition method. A film was formed as follows. Subsequently, an aluminum film was formed to a film thickness of about 100 nm to prepare an element for hole mobility measurement. This element was sealed in a nitrogen atmosphere with a glass cap to which a moisture getter sheet for organic EL was adhered so as to prevent deterioration due to adsorption of moisture and oxygen.

Using the device, the hole mobility was measured by a transient photocurrent measuring device under the following conditions. Table 3 summarizes the results.

(Measurement condition)
Device: Time-of-flight measurement device TOF-401 (manufactured by Optel)
Excitation light source: nitrogen laser (337.1 nm)
Optical pulse width: 1 nsec or less Measurement area: 0.04 cm ²
Sample temperature: 25°C
Load resistance: 50Ω
Electric field strength: 0.25MV/cm

The hole mobilities of compound (1-82) and compound (1-83) were as high as 3.1×10 ⁻⁴ and 4.0×10 ⁻⁴ cm ² /Vs, respectively. It was also at least 6 times higher than the hole mobility of comparative compound EBL-2, which was 8.2×10 ⁻⁵ . This is because the indolotriphenylene structure extends the π conjugation and makes the intersite hopping conduction efficient. By using an organic thin film containing a compound having an indorotriphenylene ring structure represented by the formula (1) or the like of the present invention in a photoelectric conversion element, holes generated in the photoelectric conversion layer can be effectively extracted. , responsiveness and conversion efficiency can be improved.

[Example 6]
<Evaluation of Single Charge Transport Device (HOD)>
Molybdenum oxide was formed as a hole injection layer to a thickness of 50 nm by vacuum deposition on a glass substrate on which an ITO electrode was previously formed as a transparent anode. The compound (1-82) of Example 1, the compound (1-83) of Example 2, and the comparative compounds EBL-1 and EBL-2 were deposited by vacuum deposition to a thickness of 100 nm. Subsequently, a HOD was created by vapor-depositing aluminum as a cathode to a thickness of 100 nm.

For the above-described single charge transport device (HOD), a source meter measuring instrument (Keithley 2635B, manufactured by KEITHLEY) was used to measure the leakage current in the dark state under −3V reverse bias conditions. Also, these HODs were heated on a hot plate at 190° C. for 3 hours in a glove box under a nitrogen atmosphere, and then the leak current in the dark state was similarly measured. The results are summarized in Table 4.

HOD using compound (1-82) and compound (1-83) has less leakage current when −3 V is applied than HOD using EBL-1 and EBL-2, and in the element after heating Also, an increase in leakage current is suppressed. This is because compounds having an indolotriphenylene structure have a good hole-transporting ability and a high glass transition temperature.

That is, the organic thin film containing the compound having an indolotriphenylene structure represented by the formula (1) or the like of the present invention is an organic thin film having excellent heat resistance and charge transport properties, and can be applied to various photoelectric conversion devices. .

[Example 7]
<Evaluation of photoelectric conversion element>
As shown in FIG. 1, the photoelectric conversion element is formed by vapor-depositing a first buffer layer 3, a photoelectric conversion layer 4, and a metal cathode 5 in this order on a glass substrate 1 on which an ITO electrode is formed in advance as a transparent anode 2. made.

Specifically, the glass substrate 1 on which ITO, which is the transparent anode 2, was subjected to ultrasonic cleaning in isopropyl alcohol for 20 minutes, and then dried on a hot plate heated to 200° C. for 10 minutes. . Then, after performing UV ozone treatment for 15 minutes, this ITO-coated glass substrate was mounted in a vacuum deposition machine, and the pressure was reduced to 0.0001 Pa or less. Subsequently, as the first buffer layer 3, the compound (1-82) of Example 1 was vapor-deposited to a thickness of 5 nm so as to cover the transparent anode 2. Next, as shown in FIG. On the first buffer layer 3, a p-type semiconductor (SubPC) having the following structural formula and an n-type semiconductor (C60) having the following structural formula were deposited as the photoelectric conversion layer 4 at a deposition rate ratio of SubPC:C60=50:50. Two-source vapor deposition was performed at a vapor deposition rate of 100 nm. Gold was formed as a metal cathode 5 on the photoelectric conversion layer 4 so as to have a film thickness of 100 nm.
Table 5 summarizes the evaluation results of the produced photoelectric conversion elements.

[Example 8]
A photoelectric conversion element was produced in the same manner as in Example 7, except that the compound (1-83) of Example 2 was used instead of the compound (1-82) used as the material for the first buffer layer 3. properties were evaluated. Table 5 summarizes the measurement results.

[Comparative Example 1]
For comparison, a photoelectric conversion element was produced in the same manner as in Example 7, except that the comparative compound EBL-1 was used instead of the compound (1-82) used as the material for the first buffer layer 3, and the electrical characteristics were evaluated. Table 5 summarizes the measurement results.

The spectral sensitivity and bright current of the organic photoelectric conversion elements produced in Examples 7 and 8 and Comparative Example 1 were measured using a spectral sensitivity measuring device under the following measurement conditions. The irradiance at a specific wavelength during measurement was calibrated using a Si photodiode (S1337-1010BQ, manufactured by Hamamatsu Photonics). Regarding the dark current, the spectral irradiance to the photoelectric conversion element was set to zero, and the current value was measured under the same bias conditions.

(Measurement condition)
Apparatus: Spectral sensitivity measurement apparatus SM-250A (manufactured by Spectrometer Co., Ltd.)
Light source: Xenon 150W
Spectral irradiance: 2.0 mW/cm ² (550 nm)
Effective irradiation area: 10 x 10mm
Light receiving area: 0.04 cm ²
In-plane non-uniformity: within ±5% Source meter: Keithley 2635B (manufactured by KEITHLEY)
Applied bias: -1 to -3V

As shown in Table 5, the dark current when −3 V was applied was −5.4×10 ⁻⁷ A/cm ² in the element of Comparative Example 1, and −10 −7 A/cm 2 in the elements of Examples 7 and 8, respectively. A dark current of 1.2×10 ⁻⁸ A/cm ² and −5.1×10 ⁻⁹ A/cm ² , which is one order of magnitude lower, was realized. Also, the conversion efficiency EQE at −3 V application is 58% for the element of Comparative Example 1, and 66% and 67% for the elements of Examples 7 and 8, respectively. Compared to the device of Comparative Example 1, the devices of Example 7 and Example 8 exhibit a lower dark current and a higher conversion efficiency EQE even when a bias of -1 V and -2 V is applied to the device. This indicates that the high electron-blocking property and good hole-transporting property of the compound having the indolotriphenylene structure can significantly improve the dark current characteristics and conversion efficiency of the photoelectric conversion device.

From the above results, the photoelectric conversion element using the organic thin film containing the compound having an indolotriphenylene structure represented by the formula (1) of the present invention has a high HOMO value required for the blocking layer of the organic photoelectric conversion element. It can be seen that it has heat resistance and sufficiently high mobility.

According to the present invention, an organic thin film having high heat resistance and good charge mobility can be applied to various photoelectric conversion devices. We can provide sensors.

Claims (10)

An organic thin film for use in a photoelectric conversion device, containing a compound represented by the following formula (1).

(Wherein, A is a single bond, a substituted or unsubstituted aromatic hydrocarbon divalent group, a substituted or unsubstituted aromatic heterocyclic divalent group, or a substituted or unsubstituted condensed polycyclic aromatic divalent group represents a valence group,
Ar ₁ to Ar ₃ , which may be the same or different, are substituted or unsubstituted aromatic hydrocarbon groups, substituted or unsubstituted aromatic heterocyclic groups or substituted or unsubstituted condensed polycyclic aromatic groups. represent,
A and Ar ₂ , A and Ar ₃ , and Ar ₂ and Ar ₃ may be bonded to each other through a single bond, a substituted or unsubstituted methylene group, an oxygen atom or a sulfur atom to form a ring;
R ₁ to R ₁₃ , which may be the same or different, are hydrogen atom, deuterium atom, fluorine atom, chlorine atom, cyano group, nitro group, and optionally substituted carbon atoms of 1 to 6 A linear or branched alkyl group, an optionally substituted cycloalkyl group having 5 to 10 carbon atoms, and an optionally substituted linear chain having 2 to 6 carbon atoms or a branched alkenyl group, an optionally substituted C 1-6 linear or branched alkyloxy group, an optionally substituted C 5-10 represents a cycloalkyloxy group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted condensed polycyclic aromatic group or a substituted or unsubstituted aryloxy group,
Adjacent R ₁ to R ₁₃ may be bonded to each other via a single bond, a substituted or unsubstituted methylene group, an oxygen atom or a sulfur atom to form a ring. ) 2. The organic thin film according to claim 1, wherein the compound represented by the formula (1) is a compound represented by the following formula (2).

(A, Ar ₁ to Ar ₃ and R ₁ to R ₁₃ in the formula are the same as defined in formula (1).) 2. The organic thin film according to claim 1, wherein the compound represented by the formula (1) is a compound represented by the following formula (3).

(A, Ar ₁ to Ar ₃ and R ₁ to R ₁₃ in the formula are the same as defined in formula (1).) 2. The organic thin film according to claim 1, wherein the compound represented by the formula (1) is a compound represented by the following formula (4).

(A, Ar ₁ to Ar ₃ and R ₁ to R ₁₃ in the formula are the same as defined in formula (1).) 3. The organic thin film according to claim 2, wherein the compound represented by the formula (2) is a compound represented by the following formula (5).

(In the formula, A has the same definition as A in formula (1), Ar has the same definition as Ar ₁ to Ar ₃ in formula (1), and R ₁ to R ₂₁ have the same definition as in formula (1). It is the same definition as R ₁ to R ₁₃ of 3. The organic thin film according to claim 2, wherein the compound represented by the formula (2) is a compound represented by the following formula (6).

(In the formula, Ar ₁ and Ar ₂ have the same definitions as Ar ₁ to Ar ₃ in formula (1), and R ₁ to R ₂₀ have the same definitions as R ₁ to R ₁₃ in formula (1). ) A photoelectric conversion element comprising at least an anode, a buffer layer, a photoelectric conversion layer and a cathode laminated in this order, the photoelectric conversion element comprising the organic thin film according to any one of claims 1 to 6. 8. The photoelectric conversion device according to claim 7, comprising said organic thin film as a buffer layer. 8. The photoelectric conversion device according to claim 7, comprising said organic thin film as a photoelectric conversion layer. An imaging device comprising the photoelectric conversion device according to any one of claims 7 to 9.

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