Compound, hole transport material, and photoelectric conversion element using same

Abstract

A compound, a hole transport material, and a photoelectric conversion element using the hole transport material. Provided is a compound which is useful as a hole transport material for photoelectric conversion elements, said hole transport material being capable of efficiently obtaining an electric current. A compound represented by general formula (1), in general formula (1), L1-L3 are selected from the group consisting of a group represented by general formula (2), a hydrogen atom, an alkyl group, an alkoxy group, an amino group, a thio group, an alkylsulfinyl group, an alkylsulfonyl group, an aromatic hydrocarbon group, a heterocyclic group, or the like, at least one of L1-L3 is a group represented by general formula (2), in general formula (2), R1-R20 are selected from the group consisting of a hydrogen atom, an alkoxy group, or the like, A1-A3 represent a nitrogen atom or C (R1a), any two of A1 to A3 are nitrogen atoms, and R1a is selected from a hydrogen atom, a phenyl group and the like.

Description

Technical Field

[0001] This invention relates to compounds, hole transport materials, and photoelectric conversion elements using the hole transport materials. Background Technology

[0002] In recent years, solar power generation, as a clean energy source, has attracted much attention, and the development of solar cells has become increasingly popular. Among them, the development of perovskite solar cells (hereinafter also referred to as perovskite solar cells), which are low-cost next-generation solar cells that can be manufactured using solution processes, has attracted much attention (e.g., Patent Document 1, Non-Patent Documents 1 and 2).

[0003] Perovskite solar cells mostly utilize hole transport materials within the element. The main purposes are: to improve the selective transport of holes, thereby increasing photoelectric conversion efficiency; and to protect the perovskite material, which is susceptible to moisture and oxygen, by bonding the hole transport material to the perovskite photoelectric conversion layer (e.g., Non-Patent Literature 3). Spiro-OMeTAD, a spirodifluorene-based organic compound, is widely used as a standard hole transport material. However, there are few reports of hole transport materials that are more beneficial to photoelectric conversion characteristics than Spiro-OMeTAD.

[0004] Patent Document 1: International Publication No. 2017 / 104792

[0005] Non-patent literature 1: J. Am. Chem. Soc., 2009, Vol. 131, pp. 6050-6051

[0006] Non-patent literature 2: Science, 2012, Vol. 388, pp. 643-647

[0007] Non-patent literature 3: Chem. Sci., 2019, Vol. 10, pp. 6748-6769 Summary of the Invention

[0008] The purpose of this invention is to provide a compound useful as a hole transport material for a photoelectric conversion element capable of efficiently acquiring current, a hole transport material containing the compound, and a photoelectric conversion element using the hole transport material in a hole transport layer that has excellent photoelectric conversion characteristics and heat resistance.

[0009] To address the aforementioned issues, the inventors conducted in-depth research on improving photoelectric conversion characteristics. Their findings revealed that by designing and developing compounds with specific structures and using hole transport layers containing these compounds in photoelectric conversion elements, photoelectric conversion elements and perovskite solar cells with excellent photoelectric conversion characteristics and heat resistance can be obtained. In other words, the main contents of this invention are as follows.

[0010] 1. A compound represented by the following general formula (1),

[0011] [Chemical Formula 1]

[0012]

[0013] In general formula (1), L 1 ~L 3 Each independently is:

[0014] The groups, hydrogen atoms, halogen atoms, hydroxyl groups, and other elements represented by the following general formula (2)

[0015] Optionally having substituents, straight-chain or branched alkyl groups having 1 to 20 carbon atoms,

[0016] Optionally having substituents, a straight-chain or branched alkenyl group having 2 to 20 carbon atoms,

[0017] Optionally having a substituent, a straight-chain or branched alkoxy group having 1 to 20 carbon atoms,

[0018] aryloxy groups having 6 to 30 carbon atoms optionally having substituents

[0019] optional amino groups having 0 to 50 carbon atoms with substituents

[0020] Optionally having a thio group having 0 to 20 carbon atoms as a substituent,

[0021] Optionally having a substituent of an alkyl sulfinyl group having 1 to 20 carbon atoms,

[0022] Optionally having a substituent of an alkyl sulfonyl group having 1 to 20 carbon atoms, or optionally having a substituent of an aromatic hydrocarbon group having 6 to 30 carbon atoms, or

[0023] Heterocyclic groups having 5 to 30 cyclic atoms optionally having substituents.

[0024] L 1 ~L 3 At least one of them is a group represented by the following general formula (2),

[0025] [Chemical Formula 2]

[0026]

[0027] In general formula (2), R 1 ~R 20 Each independently is:

[0028] hydrogen atom,

[0029] Optionally having substituents, straight-chain or branched alkyl groups having 1 to 20 carbon atoms,

[0030] Optionally having substituents, a straight-chain or branched alkenyl group having 2 to 20 carbon atoms,

[0031] Optionally having a substituent, a cycloalkyl group having 3 to 10 carbon atoms,

[0032] Optionally, a straight-chain or branched alkoxy group having 1 to 20 carbon atoms and a substituent; or an aryloxy group having 6 to 30 carbon atoms and a substituent.

[0033] An amino group having 0 to 20 carbon atoms optionally having a substituent, or

[0034] Optionally, a thio group having 0 to 20 carbon atoms as a substituent.

[0035] A 1 ~A 3 Represents nitrogen atom or C(R) 1a A 1 ~A 3 Any two of them are nitrogen atoms.

[0036] R 1a For hydrogen atoms,

[0037] Optionally having substituents, straight-chain or branched alkyl groups having 1 to 20 carbon atoms,

[0038] Optionally having substituents, a straight-chain or branched alkenyl group having 2 to 20 carbon atoms,

[0039] Optionally having a substituent, a cycloalkyl group having 3 to 10 carbon atoms,

[0040] Optionally, a straight-chain or branched alkoxy group having 1 to 20 carbon atoms and a substituent; or an aryloxy group having 6 to 30 carbon atoms and a substituent.

[0041] An amino group having 0 to 20 carbon atoms optionally having a substituent, or

[0042] Optionally, a thio group having 0 to 20 carbon atoms as a substituent.

[0043] 2. The compound according to claim 1, wherein,

[0044] In the general formula (1), L 1 for

[0045] hydrogen atom,

[0046] optional amino groups having 0 to 50 carbon atoms with substituents

[0047] Optionally having a thio group having 0 to 20 carbon atoms as a substituent,

[0048] Optionally having a substituent of an alkyl sulfinyl group having 1 to 20 carbon atoms,

[0049] Optionally having a substituent of an alkyl sulfonyl group having 1 to 20 carbon atoms,

[0050] Optionally having a substituent of an aromatic hydrocarbon group having 6 to 20 carbon atoms, or

[0051] A heterocyclic group having 5 to 30 cyclic atoms optionally having substituents.

[0052] 3. The compound according to claim 1 or 2, wherein,

[0053] The compound represented by the general formula (1) is a compound represented by the following general formula (3) or general formula (4).

[0054] [Chemical Formula 3]

[0055]

[0056] In general formulas (3) and (4), L 1 L 2 A 1 ~A 3 and R 1 ~R 20 Each is defined as described in general formulas (1) and (2), wherein L in general formula (3) 1 and L 2 The L in general formula (4) represents a group other than the group represented by the general formula (2). 1 This refers to groups other than those represented by the general formula (2).

[0057] 4. The compound according to any one of 1 to 3, wherein, in the general formula (2), R 1 ~R 20 An alkoxy group consisting of 1 to 20 straight-chain or branched carbon atoms, which may be hydrogen atoms or optionally have substituents.

[0058] 5. A hole transport material comprising any one of the compounds in 1 to 4.

[0059] 6. A photoelectric conversion element using the hole transport material described in 5.

[0060] According to the present invention, it is possible to obtain a compound useful as a hole transport material for a photoelectric conversion element capable of efficiently acquiring current, a hole transport material containing the compound, and a photoelectric conversion element having excellent photoelectric conversion characteristics and heat resistance when the hole transport material is used in a hole transport layer. Attached Figure Description

[0061] Figure 1 This is a schematic cross-sectional view showing the structure of a photoelectric conversion element according to one embodiment of the present invention.

[0062] (Explanation of reference numerals in the attached diagram)

[0063] 1. Conductive support

[0064] 2. Electron transport layer

[0065] 3 Photoelectric conversion layer

[0066] 4. Hole transport layer

[0067] 5 pairs of electrodes Detailed Implementation

[0068] The embodiments of the present invention will now be described in detail. The descriptions of the constituent elements described below are sometimes based on representative embodiments or specific examples of the present invention, but the present invention is not limited to such embodiments or specific examples. Furthermore, the numerical range indicated by "~" in this specification refers to the range including the values ​​described before and after "~" as lower and upper limits. When the numerical range is described in stages, the upper and lower limits of each numerical range and the values ​​described in the embodiments can be arbitrarily combined. Additionally, in this specification, "transparent" and "transmittance" refer to the transmittance of light supplied for photoelectric conversion being 50% or more, for example, 80% or more, 90% or more, or 99% or more. The transmittance of light can be measured using a UV-Vis spectrophotometer.

[0069] <Compound>

[0070] Hereinafter, the compounds involved in this invention represented by the above general formula (1) will be specifically described, but the present invention is not limited thereto.

[0071] In general formula (1), L 1 ~L 3Each of the following groups independently represents the group represented by the above general formula (2), hydrogen atom, halogen atom, hydroxyl group, alkyl group with 1 to 20 carbon atoms that optionally has a substituent, alkenyl group with 2 to 20 carbon atoms that optionally has a substituent, alkoxy group with 1 to 20 carbon atoms that optionally has a substituent, aryloxy group with 6 to 30 carbon atoms that optionally has a substituent, amino group with 0 to 50 carbon atoms that optionally has a substituent, thio group with 0 to 20 carbon atoms that optionally has a substituent, alkylsulfinyl group with 1 to 20 carbon atoms that optionally has a substituent, alkylsulfonyl group with 1 to 20 carbon atoms that optionally has a substituent, aromatic hydrocarbon group with 6 to 30 carbon atoms that optionally has a substituent, or heterocyclic group with 5 to 30 cyclic atoms that optionally has a substituent.

[0072] As a result of L 1 ~L 3 The term "halogen atom" can be represented by fluorine, chlorine, bromine, and iodine atoms.

[0073] As a result of L 1 ~L 3 The phrase "a straight-chain or branched alkyl group having 1 to 20 carbon atoms, optionally having substituents" specifically includes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, 2-ethylhexyl, heptyl, octyl, isooctyl, nonyl, and decyl.

[0074] As a result of L 1 ~L 3 The phrase "alkenyl groups with 2 to 20 carbon atoms that optionally have substituents" specifically includes vinyl groups, 1-propenyl groups, 2-propenyl (allyl), 1-methylvinyl groups, 1-butenyl groups, 2-butenyl groups, 1-pentenyl groups, 1-hexenyl groups, 2-methyl-1-propenyl groups, 2-methyl-2-propenyl groups, 1-ethylvinyl groups, and alkenyl groups with 2 to 20 carbon atoms formed by multiple bonds of these alkenyl groups.

[0075] As a result of L 1 ~L 3The phrase "a straight-chain or branched alkoxy group having 1 to 20 carbon atoms, optionally having a substituent" includes, specifically, methoxy, ethoxy, propoxy, n-butoxy, n-pentoxy, n-hexoxy, heptoxy, octoxy, nonoxy, decoxy, isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, isooctoxy, and tert-octoxy.

[0076] As a result of L 1 ~L 3 The "aryloxy group having 6 to 30 carbon atoms" in the phrase "aryloxy group having 6 to 30 carbon atoms optionally having a substituent" can specifically include phenoxy, tolyloxy, biphenyloxy, terphenyloxy, naphthoxy, anthraceneoxy, phenanthroxy, fluorenoxy, indoxy, etc.

[0077] As a result of L 1 ~L 3 The phrase "amino group having 0 to 50 carbon atoms optionally having a substituent" specifically includes: unsubstituted amino groups (-NH2); ethylamino, acetylamino, and phenylamino groups as monosubstituted amino groups; and diethylamino, diphenylamino, and acetylphenylamino groups as disubstituted amino groups. It should be noted that the "substituent" in "unsubstituted amino group," "monosubstituted amino group," and "disubstituted amino group" refers to a substituent that is distinct from the "substituent" in "amino group having 0 to 50 carbon atoms optionally having a substituent." That is, when "amino group having 0 to 50 carbon atoms optionally having a substituent" is "monosubstituted amino group optionally having a substituent," it means that the monosubstituted amino group has hydrogen or that the "substituent" may further have the "substituent" described later. The same applies to the description of thio groups, etc., below. "Amino groups having 0 to 50 carbon atoms optionally having substituents" are preferably unsubstituted amino groups (-NH2), monosubstituted amino groups, or disubstituted amino groups.

[0078] As a result of L 1 ~L 3 The phrase "a thio group with 0 to 20 carbon atoms that optionally has a substituent" can specifically include unsubstituted thio groups (thiol groups: -SH), methylthio, ethylthio, propylthio, phenylthio, and biphenylthio.

[0079] As a result of L 1 ~L 3The "alkyl sulfinyl group having 1 to 20 carbon atoms" in the phrase "optionally having a substituent" can specifically include methyl sulfinyl (―S=O-Me), ethyl sulfinyl, propyl sulfinyl, butyl sulfinyl, pentyl sulfinyl, and hexyl sulfinyl, etc.

[0080] As a result of L 1 ~L 3 The "alkyl sulfonyl group having 1 to 20 carbon atoms" in the phrase "optionally having a substituent" can specifically include methyl sulfonyl (―S(=O)2-Me), ethyl sulfonyl, propyl sulfonyl, butyl sulfonyl, pentyl sulfonyl, and hexyl sulfonyl.

[0081] As a result of L 1 ~L 3 The phrase "aromatic hydrocarbon group having 6 to 30 carbon atoms, optionally having substituents" specifically includes phenyl, biphenyl, terphenyl, naphthyl, anthryl group, phenanthryl, fluorenyl, indene, pyrene, perylene, fluoranyl, benzophenanthryl, etc. Furthermore, in this invention, "aromatic hydrocarbon group" includes "fused polycyclic aromatic groups".

[0082] As a result of L 1 ~L 3 The phrase "heterocyclic groups having 5 to 30 cyclic atoms optionally having substituents" specifically includes pyridyl, pyrimidinyl, triazine, thiophene, furanyl, pyrrole, imidazolyl, pyrazolyl, triazolyl, quinolinyl, isoquinolinyl, naphridinyl, acridine, phenanthroline, benzofuranyl, benzothiophene, oxazolyl, indolyl, carbazolyl, benzooxazolyl, thiazolyl, benzothiazolyl, quinoxolinyl, benzoimidazolyl, dibenzofuranyl, dibenzothiophene, and carbazolyl, etc.

[0083] As a result of L 1 ~L 3The terms "optionally having a substituent, a straight-chain or branched alkyl group having 1 to 20 carbon atoms", "optionally having a substituent, a straight-chain or branched alkenyl group having 2 to 20 carbon atoms", "optionally having a substituent, a straight-chain or branched alkoxy group having 1 to 20 carbon atoms", "optionally having a substituent, an aryloxy group having 6 to 30 carbon atoms", "optionally having a substituent, an amino group having 0 to 50 carbon atoms", "optionally having a substituent, a thio group having 0 to 20 carbon atoms", "optionally having a substituent, an alkylsulfinyl group having 1 to 20 carbon atoms", "optionally having a substituent, an alkylsulfonyl group having 1 to 20 carbon atoms", and "optionally having a substituent, a straight-chain or branched alkoxy group having 1 to 20 carbon atoms" are used to indicate the following: The term "substituent" refers to either an aromatic hydrocarbon group with 6 to 30 carbon atoms or a heterocyclic group with 5 to 30 cyclic atoms, optionally having substituents. Specifically, examples include: halogen atoms such as fluorine, chlorine, bromine, and iodine; cyano; hydroxyl; nitro; nitroso; carboxyl; phosphate; thio (>C=S); trimethylsilyl; carboxylic acid esters such as methyl ester and ethyl ester; straight-chain or branched alkyl groups with 1 to 18 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, 2-ethylhexyl, heptyl, octyl, isooctyl, nonyl, and decyl; and vinyl groups. (group), 1-propenyl, 2-propenyl (allyl), 1-butenyl, 2-butenyl, 1-pentenyl, 1-hexenyl, 2-methyl-1-propenyl, 2-methyl-2-propenyl and 1-ethylvinyl, etc., straight-chain or branched alkenyl groups with 2 to 18 carbon atoms; methoxy, ethoxy, propoxy, tert-butoxy, pentoxy and hexoxy, etc., straight-chain or branched alkoxy groups with 1 to 18 carbon atoms; phenyl, naphthyl, anthracene, phenanthryl and pyrene, etc., aromatic hydrocarbon groups with 6 to 30 carbon atoms; pyridyl, pyrimidinyl, triazine, thiophene, furanyl (furanyl) (group), pyrroleyl, imidazolyl, pyrazolyl, triazolyl, quinolinyl, isoquinolinyl, naphridyl, acridineyl, phenanthrolinel, benzofuranyl, benzothiopheneyl, oxazolyl, indolyl, carbazoleyl, benzooxazolyl, thiazolyl, benzothiazolyl, quinoxolinyl, benzimidazolyl, dibenzofuranyl, dibenzothiopheneyl and carbolinyl and other heterocyclic groups with 5 to 20 ring atoms; amino groups with 0 to 18 carbon atoms: unsubstituted amino groups (-NH2), ethylamino, acetylamino and phenylamino and other monosubstituted amino groups, or disubstituted amino groups such as diethylamino, diphenylamino and acetylphenylamino and other disubstituted amino groups; unsubstituted thio groups (thiols: -SH), methylthio, ethylthio, propylthio, phenylthio and biphenylthio and other thio groups with 0 to 18 carbon atoms; etc. These "substituents" may be of only one type, or optionally multiple types, and when multiple types are included, the multiple substituents may be the same as or different from each other. In addition, these "substituents" may further have the substituents exemplified above.

[0084] L 1 ~L 3 Preferably, the group represented by general formula (2), hydrogen atom, halogen atom, linear or branched alkyl group having 1 to 20 carbon atoms optionally having a substituent, linear or branched alkoxy group having 1 to 20 carbon atoms optionally having a substituent, amino group having 0 to 50 carbon atoms optionally having a substituent, thio group having 0 to 20 carbon atoms optionally having a substituent, alkyl sulfinyl group having 1 to 20 carbon atoms optionally having a substituent, alkyl sulfonyl group having 1 to 20 carbon atoms optionally having a substituent, or aromatic group having 6 to 30 carbon atoms optionally having a substituent. The group may be a group of hydrocarbons, or a heterocyclic group having 5 to 30 cyclic atoms optionally having substituents, more preferably a group represented by general formula (2), a hydrogen atom, a halogen atom, an amino group having 0 to 50 carbon atoms optionally having substituents, a thio group having 0 to 20 carbon atoms optionally having substituents, an alkyl sulfinyl group having 1 to 20 carbon atoms optionally having substituents, an alkyl sulfonyl group having 1 to 20 carbon atoms optionally having substituents, an aromatic hydrocarbon group having 6 to 20 carbon atoms optionally having substituents, or a heterocyclic group having 5 to 30 cyclic atoms optionally having substituents.

[0085] L 1 ~L 3 At least one of them is a group represented by the above general formula (2). In L 1 In the case of groups other than those represented by general formula (2), L 1 Preferably, it comprises hydrogen atoms, halogen atoms, a straight-chain or branched alkyl group having 1 to 20 carbon atoms optionally having substituents, a straight-chain or branched alkoxy group having 1 to 20 carbon atoms optionally having substituents, an amino group having 0 to 50 carbon atoms optionally having substituents, a thio group having 0 to 20 carbon atoms optionally having substituents, an alkylsulfinyl group having 1 to 20 carbon atoms optionally having substituents, an alkylsulfonyl group having 1 to 20 carbon atoms optionally having substituents, an aromatic hydrocarbon group having 6 to 30 carbon atoms optionally having substituents, or a heterocyclic group having 5 to 30 cyclic atoms optionally having substituents. The cyclic group is more preferably a hydrogen atom, an amino group with 0 to 50 carbon atoms optionally having a substituent, a thio group with 0 to 20 carbon atoms optionally having a substituent, an alkyl sulfinyl group with 1 to 20 carbon atoms optionally having a substituent, an alkyl sulfonyl group with 1 to 20 carbon atoms optionally having a substituent, an aromatic hydrocarbon group with 6 to 20 carbon atoms optionally having a substituent, or a heterocyclic group with 5 to 30 cyclic atoms optionally having a substituent, and is even more preferably a hydrogen atom, an amino group with 0 to 50 carbon atoms optionally having a substituent, or an aromatic hydrocarbon group with 6 to 20 carbon atoms optionally having a substituent.

[0086] In general formula (1), A 1 ~A 3 To represent a nitrogen atom or C(R) 1a It should be noted that A 1 ~A 3 Any two of them are nitrogen atoms, and the rest are A atoms. 1 ~A 3 For C(R) 1a ). Here, R 1a The group represents a hydrogen atom, a straight-chain or branched alkyl group having 1 to 20 carbon atoms optionally having a substituent, a straight-chain or branched alkenyl group having 2 to 20 carbon atoms optionally having a substituent, a cycloalkyl group having 3 to 10 carbon atoms optionally having a substituent, a straight-chain or branched alkoxy group having 1 to 20 carbon atoms optionally having a substituent, an aryloxy group having 6 to 30 carbon atoms optionally having a substituent, an amino group having 0 to 20 carbon atoms optionally having a substituent, or a thio group having 0 to 20 carbon atoms optionally having a substituent.

[0087] In the above general formula (2), R 1 ~R 20 Each of the following groups independently represents a hydrogen atom, a straight-chain or branched alkyl group having 1 to 20 carbon atoms optionally having a substituent, a straight-chain or branched alkenyl group having 2 to 20 carbon atoms optionally having a substituent, a cycloalkyl group having 3 to 10 carbon atoms optionally having a substituent, a straight-chain or branched alkoxy group having 1 to 20 carbon atoms optionally having a substituent, an aryloxy group having 6 to 30 carbon atoms optionally having a substituent, an amino group having 0 to 20 carbon atoms optionally having a substituent, or a thio group having 0 to 20 carbon atoms optionally having a substituent.

[0088] As mentioned above, R 1a and in general formula (2) R 1 ~R 20 The terms "alkyl group having 1 to 20 carbon atoms that is optionally substituent" and "alkenyl group having 2 to 20 carbon atoms that is optionally substituent," specifically the "alkyl group having 1 to 20 carbon atoms that is either straight-chain or branched" and the "alkenyl group having 2 to 20 carbon atoms that is either straight-chain or branched," can be exemplified by those relating to the L mentioned above. 1 ~L 3 The group is the same as the group exemplified by "a straight-chain or branched alkyl group having 1 to 20 carbon atoms optionally having a substituent" and "a straight-chain or branched alkenyl group having 2 to 20 carbon atoms optionally having a substituent".

[0089] As mentioned above, R 1a and in general formula (2) R 1 ~R 20The phrase "a cycloalkyl group having 3 to 10 carbon atoms that optionally has a substituent" includes, specifically, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl, and cyclododecyl, etc.

[0090] As mentioned above, R 1a and in general formula (2) R 1 ~R 20 The terms "alkoxy group having 1 to 20 carbon atoms optionally having a substituent" and "aryloxy group having 6 to 30 carbon atoms optionally having a substituent," specifically, can be exemplified by those relating to the L mentioned above. 1 ~L 3 The group is the same as the group exemplified by "an alkoxy group having 1 to 20 carbon atoms optionally having a substituent" and "an aryloxy group having 6 to 30 carbon atoms optionally having a substituent".

[0091] As mentioned above, R 1a and in general formula (2) R 1 ~R 20 The phrase "amino group with 0 to 20 carbon atoms, optionally having substituents" specifically refers to amino groups derived from the aforementioned L. 1 ~L 3 The amino group with 0 to 20 carbon atoms in the term "amino group having 0 to 50 carbon atoms, optionally having substituents" is represented by the group.

[0092] As mentioned above, R 1a and in general formula (2) R 1 ~R 20 The "thiogroup with 0 to 20 carbon atoms" in the phrase "optionally having substituents and a thiogroup with 0 to 20 carbon atoms" can be specifically exemplified by the thiogroup with the carbon atom number of 0 to 20 as described above. 1 ~L 3 The same group as the group exemplified by "a thio group having 0 to 20 carbon atoms optionally having a substituent".

[0093] As mentioned above, R 1a and in general formula (2) R 1 ~R 20The "substituent" in "optionally having a substituent in a straight-chain or branched alkyl group having 1 to 20 carbon atoms", "optionally having a substituent in a straight-chain or branched alkenyl group having 2 to 20 carbon atoms", "optionally having a substituent in a cycloalkyl group having 3 to 10 carbon atoms", "optionally having a substituent in a straight-chain or branched alkoxy group having 1 to 20 carbon atoms", "optionally having a substituent in an aryloxy group having 6 to 30 carbon atoms", "optionally having a substituent in an amino group having 0 to 20 carbon atoms", or "optionally having a substituent in a thio group having 0 to 20 carbon atoms" can be exemplified by L. 1 ~L 3 The group is the same as the group exemplified by the term "substituent" in "optionally having a substituent in a straight-chain or branched alkyl group having 1 to 20 carbon atoms".

[0094] In general formula (2), R 5 With R 6 and R 15 With R 16 Rings can be formed through single bonds or through bonds between oxygen, sulfur, selenium, or nitrogen atoms.

[0095] In general formula (1), R 1a Preferably, it is a hydrogen atom or a substituted or unsubstituted phenyl group, more preferably a hydrogen atom. In general formula (2), R 1 ~R 20 Preferably, it is a hydrogen atom, an amino group having 0 to 20 carbon atoms with a substituent, or a straight-chain or branched alkoxy group having 1 to 20 carbon atoms with a substituent; more preferably, it is a hydrogen atom or a straight-chain or branched alkoxy group having 1 to 20 carbon atoms with a substituent; and even more preferably, R 3 R 8 R 13 and R 18 Each is a straight-chain or branched alkoxy group having 1 to 20 carbon atoms, optionally with substituents, R 1 R 2 R 4 R 5 R 6 R 7 R 9 R 10 R 11 R 12 R 14 R 15 R 16 R 17 R 19 and R 20 All are hydrogen atoms.

[0096] As described above, in general formula (1), the preferred option is: L 1 ~L 3 At least one of them represents a group represented by the above general formula (2), L 1 For groups other than those represented by general formula (2), L 2 and L 3 One or both of them are groups represented by formula (2) above. That is, the compound represented by the general formula (1) above is preferably a compound represented by the general formula (3) or general formula (4) above. It should be noted that in general formulas (3) and (4), L 1 L 2 A 1 ~A 3 and R 1 ~R 20 Each is defined as in general formulas (1) and (2) above. In general formula (3), L... 1 and L 2 The L in general formula (4) represents groups other than those represented by general formula (2). 1 This refers to groups other than those represented by the general formula (2).

[0097] Furthermore, in general formula (2), the diarylamino group is preferably substituted at the 3 and 6 positions of the carbazole. That is, the compounds represented by general formula (3) or (4) are preferably compounds represented by general formula (5) or (6) respectively. It should be noted that in general formulas (5) and (6), L 1 L 2 A 1 ~A 3 and R 1 ~R 20 Each is defined as in general formulas (1) and (2) above. In general formula (5), L... 1 and L 2 The L in general formula (6) represents groups other than those represented by general formula (2). 1 This refers to groups other than those represented by the general formula (2).

[0098] [Chemical Formula 4]

[0099]

[0100] In general formulas (1), (3), (4), (5), and (6), A 1 ~A 3 Any two of them represent nitrogen atoms. Here, it can be either A... 1 and A 2 It can be a nitrogen atom, or it can be an A atom. 2 and A 3It can be a nitrogen atom, or it can be an A atom. 1 and A 3 It is a nitrogen atom.

[0101] The following are specific examples of compounds of the present invention represented by the above general formula (1), but the present invention is not limited to these compounds. In the following exemplary compounds, some hydrogen atoms and carbon atoms are omitted. In addition, the following exemplary compounds represent one example of possible isomers, and the compounds of the present invention include all other isomers. Furthermore, the compounds of the present invention may be mixtures of two or more isomers.

[0102] [Chemical Formula 5]

[0103]

[0104] [Chemical Formula 6]

[0105]

[0106] [Chemical Formula 7]

[0107]

[0108] [Chemical Formula 8]

[0109]

[0110] [Chemical Formula 9]

[0111]

[0112] [Chemical Formula 10]

[0113]

[0114] [Chemical Formula 11]

[0115]

[0116] [Chemical Formula 12]

[0117]

[0118] [Chemical Formula 13]

[0119]

[0120] [Chemical Formula 14]

[0121]

[0122] [Chemical Formula 15]

[0123]

[0124] [Chemical Formula 16]

[0125]

[0126] [Chemical Formula 17]

[0127]

[0128] [Chemical Formula 18]

[0129]

[0130] [Chemical Formula 19]

[0131]

[0132] The compounds of the present invention represented by the above general formula (1) can be synthesized using known methods. For example, the compounds represented by the above general formula (1) can be obtained by a nucleophilic substitution reaction of a dichloropyrimidine derivative with a 3,6-triarylamino-substituted carbazole represented by the following general formula (7). It should be noted that R in the following general formula (7) 1 ~R 20 As defined in general formula (2) above.

[0133] [Chemical Formula 20]

[0134]

[0135] Examples of purification methods for compounds represented by the above general formula (1) include column chromatography, adsorption purification using silica gel, activated carbon, or activated clay, and recrystallization or crystallization using solvents. Furthermore, by combining these methods, compounds with further improved purity can be obtained. It should be noted that the identification of these compounds can be performed using nuclear magnetic resonance (NMR) analysis.

[0136] Hole transport materials

[0137] The compound represented by general formula (1) can be used as a hole transport material. That is, the hole transport material of the present invention comprises the compound represented by general formula (1). Specifically, the compound represented by general formula (1) is suitable for use as a hole transport material in the fields of photoelectric conversion elements and organic electronics. Hereinafter, a preferred embodiment of the photoelectric conversion element of the present invention will be described.

[0138] <Photoelectric conversion element>

[0139] The photoelectric conversion element of the present invention relates to a photoelectric conversion element in which a hole transport material comprising the compound of the present invention represented by general formula (1) is used in a hole transport layer. Hereinafter, the photoelectric conversion element of the present invention will be described with reference to the accompanying drawings.

[0140] Figure 1 This is a schematic cross-sectional view illustrating the structure of a photoelectric conversion element according to one embodiment of the present invention. Figure 1 As shown, a typical photoelectric conversion element includes a conductive support 1, an electron transport layer 2, a photoelectric conversion layer 3, a hole transport layer 4, and a counter electrode 5. The structure of the photoelectric conversion element is not limited to... Figure 1 The structure is shown. Furthermore, the photoelectric conversion element of the present invention is preferably a solar cell, particularly preferably a perovskite solar cell (a perovskite-type photoelectric conversion element), but is not limited thereto. The perovskite-type photoelectric conversion element preferably comprises, in sequence, a conductive support (electrode) 1, an electron transport layer 2, a photoelectric conversion layer (perovskite layer) 3, a hole transport layer 4, and a counter electrode 5. The perovskite-type photoelectric conversion element may be composed of, in sequence, a conductive support, a hole transport layer, a photoelectric conversion layer (perovskite layer), an electron transport layer, and a counter electrode.

[0141] <Conductive support>

[0142] The conductive support 1 needs to have light transmittance that facilitates photoelectric conversion. Furthermore, the conductive support is a component that functions to obtain current from the photoelectric conversion layer, and therefore a conductive substrate is preferred. Examples of conductive materials constituting the conductive substrate include conductive transparent oxide semiconductors such as tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), tungsten-doped indium oxide (IWO), zinc and aluminum oxide (AZO), fluorine-doped tin oxide (FTO), indium oxide (In₂O₃), and indium-tin composite oxides. Among these, tin-doped indium oxide (ITO) and fluorine-doped tin oxide (FTO) are preferred.

[0143] There are no particular limitations on the substrate; glass substrates, plastic substrates, and metal substrates can be used. The substrate can be transparent or opaque. Examples of substrates include polyethylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate, cellulose acetate phthalate, cellulose nitrocellulose, polyvinylidene chloride, polyvinyl alcohol, polyvinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyetherketone, polyimide, polyethersulfone, polyphenylene sulfide, polysulfones, polyetherimide, polyetherketoneimide, polyamide, fluoropolymers, nylon, polymethyl methacrylate, acrylic or polyarylates, and organic-inorganic hybrid resins, as well as inorganic substrates such as glass, quartz, alumina, silicon, silica, tantalum dioxide, tantalum pentoxide, and indium tin oxide, and metal substrates such as gold, copper, chromium, titanium, and aluminum.

[0144] <Electron transport layer>

[0145] The electron transport layer 2 is located between the conductive support 1 and the photoelectric conversion layer (perovskite layer) 3. Preferably, the electron transport layer 2 is formed on the conductive support 1, but this is not particularly limited. The electron transport layer has the function of improving the efficiency of electron movement from the photoelectric conversion layer to the electrode and blocking the movement of holes.

[0146] Specific examples of semiconductors forming the electron transport layer include: metal oxides such as tin oxide (SnO, SnO2, SnO3, etc.), titanium oxide (TiO2, etc.), tungsten oxide (WO2, WO3, W2O3, etc.), zinc oxide (ZnO), niobium oxide (Nb2O5, etc.), tantalum oxide (Ta2O5, etc.), yttrium oxide (Y2O3, etc.), and strontium titanate (SrTiO3, etc.); metal sulfides such as titanium sulfide, zinc sulfide, zirconium sulfide, copper sulfide, tin sulfide, indium sulfide, tungsten sulfide, cadmium sulfide, and silver sulfide; metal selenides such as titanium selenide, zirconium selenide, indium selenide, and tungsten selenide; and monomeric semiconductors such as silicon and germanium. One type of these semiconductors can be used, or two or more types can be used in combination. In this invention, one or more semiconductors selected from tin oxide, titanium oxide, and zinc oxide are preferably used.

[0147] To form the electron transport layer, commercially available slurries containing semiconductor microparticles can be used, as well as slurries prepared by dispersing commercially available semiconductor microparticles in a solvent (electron transport layer coating liquid), etc. Specific examples of solvents used in preparing the slurry include: water; alcohol-based solvents such as methanol, ethanol, and isopropanol; ketone-based solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and hydrocarbon-based solvents such as n-hexane, cyclohexane, benzene, and toluene, but these are not limited to these. Furthermore, these solvents can be used individually or in mixtures of two or more solvents.

[0148] Examples of methods for dispersing semiconductor micropowders in a solvent include: grinding the powder in a mortar or mortar and then dispersing it; and using a disperser such as a ball mill, paint mixer, vertical bead mill, horizontal bead mill, or impact mill. When preparing the slurry, it is preferable to add surfactants or the like to prevent the agglomeration of semiconductor particles. Furthermore, it is preferable to add thickeners such as polyethylene glycol to increase the viscosity of the slurry.

[0149] The electron transport layer can be formed using known film-forming methods, depending on the material constituting the electron transport layer. Any coating method using a coating solution can be employed as a film-forming method for the electron transport layer. Examples of coating methods include: wet coating methods such as spin coating, inkjet coating, doctor blade coating, drop coating, doctor blade coating, screen printing, reverse roller coating, gravure coating, kiss coating, roller brush coating, spraying, air knife coating, screw coating, tube doctor blade coating, dip coating, and curtain coating, where a coating solution is applied to a conductive substrate, and then the solvent and additives are removed by firing (heating) to form a film; sputtering; vapor deposition; electrodeposition; electrolysis; and microwave irradiation, etc., but are not limited to these methods. In this invention, it is preferable to use a coating solution for the electron transport layer prepared by the above methods to form a film by spin coating, but this is not a limitation. It should be noted that the spin coating conditions can be appropriately set. There are no special restrictions on the atmosphere for film formation; it can be in the atmosphere.

[0150] Regarding the thickness of the electron transport layer, from the viewpoint of further improving photoelectric conversion efficiency, when a dense electron transport layer is used, the thickness of the electron transport layer is generally preferably 5 nm to 100 nm, and more preferably 10 nm to 50 nm. In this invention, when a porous (mesoporous) metal oxide is used in addition to the dense electron transport layer, the thickness of the electron transport layer is generally preferably 20 nm to 200 nm, and more preferably 50 nm to 150 nm.

[0151] (Photoelectric conversion layer)

[0152] In the photoelectric conversion element of the present invention, it is preferable to form a photoelectric conversion layer (perovskite layer) 3 on the electron transport layer 2. When the photoelectric conversion element of the present invention is used as a perovskite-type photoelectric conversion element, materials having the structure shown in the general formula ABX3 can be cited as perovskite materials for the photoelectric conversion layer. Here, A, B, and X represent the following: A: organic cation or monovalent metal cation; B: metal cation; and X: halide anion. Specifically, examples include: A: K + 、Rb + Cs + CH3NH3 + (Hereinafter referred to as "MA: methylammonium") NH=CHNH2 + (Hereinafter referred to as "FA: formamidinium") and CH3CH2NH3 + (Hereinafter referred to as "EA: ethylammonium"); B: Pb and Sn; and X: I - and Br - Specifically, ABX3 can be exemplified by perovskite materials with any composition of MAPbI3, FAPbI3, EAPbI3, CsPbI3, MASnI3, FASnI3, EASnI3, MAPbBr3, FAPbBr3, EAPbBr3, MASnBr3, FASnBr3, and EASnBr3, as well as perovskite materials composed of mixed cations and mixed anions with any composition of (FAMA)Pb(IBr)3, K(FAMA)Pb(IBr)3, Rb(FAMA)Pb(IBr)3, and Cs(FAMA)Pb(IBr)3, but is not limited to these. One or more of these perovskite materials can be used. Furthermore, the photoelectric conversion layer may also contain light absorbers other than perovskite materials.

[0153] As a method for forming the photoelectric conversion layer (perovskite layer), any coating method using a coating solution can be employed. Specifically, a method similar to the method for forming the electron transport layer described above can be used. In this method, a perovskite precursor solution prepared by dissolving a perovskite precursor in a solvent is used as the coating solution in the formation of the photoelectric conversion layer.

[0154] The perovskite precursor can be a commercially available material. In this invention, it is preferred, but not limited to, the precursor consisting of lead halide, methylammonium halide, formamidinium halide and cesium halide in any composition.

[0155] From the viewpoint of precursor solubility, solvents that can dissolve perovskite precursors include N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and γ-butyrolactone, but are not limited to these. A single solvent or a mixture of two or more solvents can be used. A mixture of N,N-dimethylformamide and dimethyl sulfoxide is preferred. Furthermore, solvents that have been dehydrated using molecular sieves or the like to a moisture content of less than 10 ppm are preferred.

[0156] From the viewpoint of being able to prevent the ingress of moisture and manufacture high-efficiency perovskite solar cells with good reproducibility, the film-forming atmosphere of the photoelectric conversion layer (perovskite layer) is preferably a dry atmosphere, and more preferably a dry inactive gas atmosphere such as a glove box.

[0157] From the viewpoint of generating perovskite materials from precursors, the heating temperature during the film formation of the photoelectric conversion layer (perovskite layer) is preferably 50°C to 200°C, more preferably 70°C to 150°C. Furthermore, the heating time is preferably 10 minutes to 90 minutes, more preferably 10 minutes to 60 minutes. It should be noted that heating can be performed, for example, using a hot plate.

[0158] From the viewpoint of further suppressing defects and performance degradation caused by peeling, and from the viewpoint of ensuring that the photoelectric conversion layer has sufficient light absorption and suppressing the element resistance from becoming too high, the thickness of the photoelectric conversion layer (perovskite layer) is preferably 50 nm to 1000 nm, more preferably 300 nm to 700 nm.

[0159] To improve the efficiency of charge transfer between layers, the defects on the surface of the photoelectric conversion layer (perovskite layer) can be coated to passivate them. Passivation can be performed by any coating method that uses a coating liquid to coat the surface defects; for example, the same coating method used to form the electron transport layer can be cited.

[0160] In passivation, compounds with quaternary ammonium salt structures are preferred, but not limited to this; multiple compounds can also be used in combination. Specifically, examples include phenylethylammonium bromide, n-hexylammonium bromide, and n-hexyltrimethylammonium bromide.

[0161] The passivation atmosphere is preferably a dry atmosphere. The method for removing the solvent from the coating solution is preferably reduced pressure. There are no particular limitations on the coating thickness, as long as it demonstrates an effect that improves charge transfer efficiency; a thickness of 10 nm or less is preferred, and more preferably 5 nm or less.

[0162] (Hole transport layer)

[0163] The hole transport layer 4 is a layer that functions to transport holes and is located between the photoelectric conversion layer (perovskite layer) 3 and the counter electrode 5. The hole transport layer improves the efficiency of hole movement from the photoelectric conversion layer to the electrode and blocks electron movement. Materials such as conductors, semiconductors, and organic hole transport materials can be used in the hole transport layer. To further improve hole transport characteristics, additives can be included in the hole transport layer.

[0164] In the photoelectric conversion element of the present invention, the hole transport layer contains a compound represented by the above general formula (1) as a hole transport material. One or more compounds represented by general formula (1) may be used in the hole transport layer, and compounds represented by general formula (1) may be used in combination with other hole transport materials not belonging to the present invention.

[0165] Specific examples of hole transport materials not included in this invention include, for example, compound semiconductors containing monovalent copper such as CuI, CuInSe2, and CuS; and compounds containing metals other than copper such as GaP, NiO, CoO, FeO, Bi2O3, MoO2, and Cr2O3. These oxide metals can be used either mixed into the hole transport layer or stacked on top of the hole transport material. In addition, examples of organic hole transport materials include: polythiophene derivatives such as poly-3-hexylthiophene (P3HT) and polyvinyldioxythiophene (PEDOT); fluorene derivatives such as 2,2',7,7'-tetra-(N,N-di-p-methoxyphenylamine)-9,9'-spirodifluorene (Spiro-OMeTAD); carbazole derivatives such as polyvinylcarbazole; triphenylamine derivatives such as poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA); diphenylamine derivatives; polysilane derivatives; and polyaniline derivatives.

[0166] As a method for fabricating a hole transport layer, any coating method using a coating solution can be employed. Specifically, a method similar to the method for fabricating an electron transport layer described above can be used. In this method, a hole transport layer coating solution is used as the coating solution in the fabrication of the hole transport layer.

[0167] Solvents used in the coating solution for the hole transport layer can include: aromatic organic solvents such as benzene, toluene, xylene, mesitylene, tetrahydronaphthalene (1,2,3,4-tetrahydronaphthalene), monochlorobenzene (chlorobenzene), o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, and nitrobenzene; halogenated alkyl organic solvents such as dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, and dichloromethane; and nitrile solvents such as benzonitrile and acetonitrile. Solvents include, but are not limited to, ether solvents such as tetrahydrofuran, dioxane, diisopropyl ether, C-pentyl methyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate and propylene glycol monomethyl ether acetate; and alcohol solvents such as methanol, isopropanol, n-butanol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, cyclohexanol, and 2-n-butoxyethanol. A single solvent or a mixture of two or more solvents can be used. The solvent used should be appropriately selected according to the structure of the material. Solvents selected from aromatic organic solvents and halogenated alkyl organic solvents are preferred. Furthermore, dehydrated solvents with a water content of less than 10 ppm are preferred.

[0168] From the perspective of further improving photoelectric conversion efficiency, the thickness of the hole transport layer is preferably 5nm to 500nm, and more preferably 10nm to 250nm.

[0169] From the viewpoint of preventing moisture contamination and being able to manufacture high-efficiency perovskite solar cells with good reproducibility, the film-forming atmosphere of the hole transport layer is preferably a dry atmosphere.

[0170] The hole transport layer may contain dopants (or oxidants) and basic compounds (or basic additives) as additives. Including additives in the hole transport layer increases the carrier concentration of the hole transport material (doping), which helps improve the conversion efficiency of the photoelectric conversion element. When the hole transport layer contains dopants and basic additives as additives, the total amount of these additives relative to 1 equivalent of the hole transport material is preferably 7.0 equivalents or less, more preferably 4.0 equivalents or less.

[0171] Specific examples of dopants include lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), silver bis(trifluoromethanesulfonyl)imide, zinc (II) bis(trifluoromethanesulfonyl)imide, copper (II) bis(trifluoromethanesulfonyl)imide, magnesium (II) bis(trifluoromethanesulfonyl)imide, calcium (II) bis(trifluoromethanesulfonyl)imide, tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt (III)tris[bis(trifluoromethanesulfonyl)imide](FK209), NOSbF6, SbCl5, and SbF5. Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is preferred, but the method is not limited to it.

[0172] The amount of dopant used is preferably 2.0 equivalents or less, more preferably 0.5 equivalents or less, relative to the hole transport material 1 contained in the hole transport layer.

[0173] Specific examples of basic compounds (basic additives) include 4-tert-butylpyridine (tBP), 2-methylpyridine, and 2,6-dimethylpyridine. Basic compounds are often used in combination with dopants. In this invention, it is also desirable to use basic compounds in combination with dopants, and 4-tert-butylpyridine is particularly preferred.

[0174] The amount of alkaline compound used is preferably 5.0 equivalents or less, more preferably 3.5 equivalents or less, relative to the hole transport material 1 contained in the hole transport layer.

[0175] Including additives in the hole transport layer helps improve the photoelectric conversion efficiency of photoelectric conversion elements. However, there are concerns that using dopants as additives may reduce the durability of photoelectric conversion elements using organic compounds and shorten the overall lifespan of the element (e.g., Non-Patent Document 3). Therefore, it is desirable to develop photoelectric conversion elements with a hole transport layer that has reduced dopant content. Furthermore, if the dopant content can be suppressed, it is possible to reduce additive costs and manufacturing process costs. In the photoelectric conversion element of the present invention, the additives are of arbitrary composition, and the hole transport layer can be free of additives. Even without additives in the hole transport layer, the hole transport layer of the photoelectric conversion element of the present invention exhibits good conductivity, thus achieving high photoelectric conversion characteristics.

[0176] (Counter electrode)

[0177] The counter electrode 5 is formed on the hole transport layer 4 and is arranged opposite to the conductive support 1, thereby enabling charge exchange between them. In the photoelectric conversion element of the present invention, it is preferable to have a metal electrode as the counter electrode on the hole transport layer 4, but an electron blocking layer made of organic material or inorganic compound semiconductor may also be added between the hole transport layer 4 and the counter electrode 5.

[0178] The counter electrode preferably uses a material that can be formed by methods such as vapor deposition. Specifically, materials used in the counter electrode include metals such as platinum, titanium, stainless steel, aluminum, gold, silver, nickel, magnesium, chromium, cobalt, and copper, as well as their alloys. Among these, gold, silver, or silver alloys are preferred, especially considering their high electrical conductivity in the thin film. It should be noted that, as for silver alloys, to reduce susceptibility to sulfidation or chlorination and improve the stability of the thin film, alloys of silver with gold, silver with copper, silver with palladium, silver with copper and palladium, and silver with platinum are preferred.

[0179] When using a metal electrode as the counter electrode, in order to obtain good conductivity, the film thickness is preferably 10 nm or more, and more preferably 50 nm or more.

[0180] In one embodiment of the photoelectric conversion element, a conductive support serves as the cathode, and a counter electrode serves as the anode. Light, such as sunlight, preferably irradiates from the conductive support side. The photoelectric conversion layer (perovskite layer) absorbs the irradiated light and becomes excited, generating electrons and holes. Then, the electrons move towards the electrode via the electron transport layer, and the holes move towards the electrode via the hole transport layer, thereby allowing current to flow and functioning as a photoelectric conversion element.

[0181] When evaluating the performance (characteristics) of a photoelectric conversion element, short-circuit current density, open-circuit voltage, curve factor (fill factor: FF), and photoelectric conversion efficiency are measured. Short-circuit current density represents the current flowing between the two terminals per 1 cm² when the output terminals are short-circuited. 2 The current and open-circuit voltage represent the voltage between the two terminals when the output terminals are open. Additionally, the curve factor (fill factor) is the maximum output (product of current and voltage) divided by the product of the short-circuit current density and the open-circuit voltage, and is primarily affected by internal resistance. The photoelectric conversion efficiency is the maximum output (W) divided by the percentage of current per 1cm². 2 The value obtained by multiplying the light intensity (W) by 100 and expressing it as a percentage. In the component configuration of the present invention, if the initial photoelectric conversion efficiency of the photoelectric conversion element is 10% or more, it can be judged as having good photoelectric conversion efficiency.

[0182] The photoelectric conversion element involved in this invention can be applied to solar cells, various optical sensors, etc. As a solar cell, a perovskite solar cell is preferred. A perovskite solar cell can be manufactured by taking a photoelectric conversion element having a hole transport material containing a compound represented by the above general formula (1) as a hole transport layer as a unit, modularizing the required number of units, and setting up a specified electrical wiring.

[0183] The above describes several preferred embodiments of the present invention in detail. However, the present invention is not limited to the above embodiments and should be understood to allow for various changes and modifications without departing from the spirit or scope of the appended claims.

[0184] Example

[0185] The present invention will now be specifically described with reference to the accompanying drawings and embodiments; however, the present invention is not limited to the following embodiments. It should be noted that the compounds obtained in the synthetic embodiments were identified using a nuclear magnetic resonance (NMR) apparatus. 1 The method is H-NMR (manufactured by Nippon Electronics Corporation, product name: JNM-ECZ400S / L1).

[0186] [Synthetic Example 1] Synthesis of Compound (A-1)

[0187] In a nitrogen atmosphere, N,N,N',N'-tetratetra(4-methoxyphenyl)-9H-carbazole-3,6-diamine (2.3 g, manufactured by Tokyo Chemical Industry Co., Ltd.), DMF (20 mL), and sodium hydride (170 mg, 55% purity, manufactured by Tokyo Chemical Industry Co., Ltd.) represented by formula (8) were added to a reaction vessel, and the mixture was stirred in an ice bath for 30 minutes. 4,6-dichloro-2-phenylpyrimidine (400 mg, manufactured by Tokyo Chemical Industry Co., Ltd.) was then added to the reaction vessel, and the mixture was stirred at room temperature for 8 hours. After the reaction was complete, water (100 mL) was added, and the precipitated solid was filtered off. The obtained solid was recrystallized from ethyl acetate to give the following compound (A-1) as a pale yellow powder (yield: 1.0 g, 40%).

[0188] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 8.51 (2H), 8.32 (5H), 8.17 (4H), 7.78 (1H), 7.66-7.62 (2H), 7.15 (4H), 6.93 (16H), 6.83 (16H), 3.70 (24H).

[0189] [Chemical Formula 21]

[0190]

[0191] [Synthetic Example 2] Synthesis of Compound (A-2)

[0192] In a nitrogen atmosphere, N,N,N',N'-tetratetra(4-methoxyphenyl)-9H-carbazole-3,6-diamine (2.3 g, manufactured by Tokyo Chemical Industry Co., Ltd.), DMF (20 mL), and sodium hydride (170 mg, 55% purity, manufactured by Kanto Chemical Co., Ltd.) represented by the above formula (8) were added to a reaction vessel, and the mixture was stirred in an ice bath for 30 minutes. 2,6-dichloro-4-phenylpyrimidine (400 mg, manufactured by Tokyo Chemical Industry Co., Ltd.) was then added to the reaction vessel, and the mixture was stirred at room temperature for 5 hours. After the reaction was complete, water (60 mL) was added, and the precipitated solid was filtered off. The obtained solid was recrystallized from toluene / acetone to give the following compound (A-2) as a pale yellow powder (yield: 1.6 g, 66%).

[0193] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 8.81 (2H), 8.38 (2H), 8.08 (3H), 7.64 (5H), 7.56(2H), 7.25(1H), 7.17(2H), 7.05(1H), 6.93(16H), 6.83(16H), 3.70(24H).

[0194] [Chemical Formula 22]

[0195]

[0196] [Synthetic Example 3] Synthesis of Compound (A-3)

[0197] In a nitrogen atmosphere, N,N,N',N'-tetratetra(4-methoxyphenyl)-9H-carbazole-3,6-diamine (3.4 g, manufactured by Tokyo Chemical Industry Co., Ltd.), DMF (30 mL), and sodium hydride (258 mg, 55% purity, manufactured by Tokyo Chemical Industry Co., Ltd.) represented by formula (8) above were added to a reaction vessel, and the mixture was stirred in an ice bath for 30 minutes. 4,6-dichloropyrimidine (400 mg, manufactured by Tokyo Chemical Industry Co., Ltd.) was then added to the reaction vessel, and the mixture was stirred at room temperature for 4 hours. After the reaction was complete, methanol (100 mL) was added, and the precipitated solid was filtered off. The obtained solid was recrystallized from toluene to give the following compound (A-3) as a pale yellow powder (yield: 2.4 g, 68%).

[0198] 1H-NMR (400MHz, DMSO-d6): δ (ppm) = 9.21 (1H), 7.04 (4H), 7.70 (1H), 7.52 (4H), 7.06 (4H), 6.81 (16H), 6.76 (16H), 3.69 (24H).

[0199] [Chemical Formula 23]

[0200]

[0201] [Synthetic Example 4] Synthesis of Compound (A-4)

[0202] Under a nitrogen atmosphere, N,N,N',N'-tetratetra(4-methoxyphenyl)-9H-carbazole-3,6-diamine (3.4 g, manufactured by Tokyo Chemical Industry Co., Ltd.), DMF (30 mL), and sodium hydride (258 mg, 55% purity, manufactured by Tokyo Chemical Industry Co., Ltd.) were added to a reaction vessel, and the mixture was stirred in an ice bath for 30 minutes. 2,4-Dichloropyrimidine (400 mg, manufactured by Tokyo Chemical Industry Co., Ltd.) was then added to the reaction vessel, and the mixture was stirred at room temperature for 3 hours. After the reaction was complete, methanol (100 mL) was added, and the precipitated solid was filtered off. The resulting solid was recrystallized from toluene to give the following compound (A-4) as a pale yellow powder (yield: 2.2 g, 61%).

[0203] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 8.98 (1H), 8.69 (2H), 8.02 (2H), 7.64 (1H), 7.63 (2H), 7.52 (2H), 7.01 (4H), 6.88 (16H), 6.82 (16H), 3.69 (24H).

[0204] [Chemical Formula 24]

[0205]

[0206] [Synthetic Example 5] Synthesis of Compound (A-5)

[0207] Under a nitrogen atmosphere, N,N,N',N'-tetratetra(4-methoxyphenyl)-9H-carbazole-3,6-diamine (3.6 g, manufactured by Tokyo Chemical Industry Co., Ltd.), DMF (32 mL), and sodium hydride (270 mg, 55% purity, manufactured by Tokyo Chemical Industry Co., Ltd.) were added to a reaction vessel, and the mixture was stirred in an ice bath for 30 minutes. 4-chloro-2,6-diphenylpyrimidine (1.5 g, manufactured by Tokyo Chemical Industry Co., Ltd.) was then added to the reaction vessel, and the mixture was stirred at room temperature for 3 hours. After the reaction was complete, methanol (100 mL) was added, and the precipitated solid was filtered off. The resulting solid was recrystallized from toluene to give the following compound (A-5) as a pale yellow powder (yield: 3.5 g, 73%).

[0208] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 8.58 (2H), 8.42 (2H), 8.18 (1H), 8.16 (2 H), 7.67(2H), 7.63-7.60(6H), 7.13(2H), 6.94(8H), 6.85(8H), 3.71(12H).

[0209] [Chemical Formula 25]

[0210]

[0211] [Synthetic Example 6] Synthesis of Compound (A-6)

[0212] Under a nitrogen atmosphere, N,N,N',N'-tetratetra(4-methoxyphenyl)-9H-carbazole-3,6-diamine (3.6 g, manufactured by Tokyo Chemical Industry Co., Ltd.), DMF (32 mL), and sodium hydride (270 mg, 55% purity, manufactured by Tokyo Chemical Industry Co., Ltd.) were added to a reaction vessel, and the mixture was stirred in an ice bath for 30 minutes. 2-chloro-4,6-diphenylpyrimidine (1.5 g, manufactured by Tokyo Chemical Industry Co., Ltd.) was then added to the reaction vessel, and the mixture was stirred at room temperature for 3 hours. After the reaction was complete, methanol (100 mL) was added, and the precipitated solid was filtered off. The resulting solid was recrystallized from toluene to give the following compound (A-6) as a pale yellow powder (yield: 2.3 g, 48%).

[0213] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 8.84 (2H), 8.44-8.40 (5H), 7.65-7.62 (6H), 7.57 (2H), 7.15 (2H), 6.92 (8H), 6.83 (8H), 3.71 (12H).

[0214] [Chemical Formula 26]

[0215]

[0216] [Synthetic Example 7] Synthesis of Compound (A-8)

[0217] Under a nitrogen atmosphere, N,N,N',N'-tetratetra(4-methoxyphenyl)-9H-carbazole-3,6-diamine (4.5 g, manufactured by Tokyo Chemical Industry Co., Ltd.), DMF (32 mL), and sodium hydride (335 mg, 55% purity, manufactured by Tokyo Chemical Industry Co., Ltd.) were added to a reaction vessel, and the mixture was stirred in an ice bath for 30 minutes. 2-Chloroprene (0.8 g, manufactured by Tokyo Chemical Industry Co., Ltd.) was then added to the reaction vessel, and the mixture was stirred at room temperature for 3 hours. After the reaction was complete, methanol (100 mL) was added, and the precipitated solid was filtered off. The resulting solid was recrystallized from toluene to give the following compound (A-8) as a pale yellow powder (yield: 1.8 g, 36%).

[0218] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 8.91 (2H), 8.69 (2H), 7.55 (2H), 7.34 (1H), 7.10 (2H), 6.90 (8H), 6.84 (8H), 3.72 (12H).

[0219] [Chemical Formula 27]

[0220]

[0221] [Synthetic Example 8] Synthesis of Compound (A-15)

[0222] Under a nitrogen atmosphere, N,N,N',N'-tetratetra(4-methoxyphenyl)-9H-carbazole-3,6-diamine (2.3 g, manufactured by Tokyo Chemical Industry Co., Ltd.), DMF (32 mL), and sodium hydride (170 mg, 55% purity, manufactured by Tokyo Chemical Industry Co., Ltd.) were added to a reaction vessel, and the mixture was stirred in an ice bath for 30 minutes. 2,4-Dichloro-6-(4-pyridyl)pyrimidine (0.4 g, manufactured by Tokyo Chemical Industry Co., Ltd.) was then added to the reaction vessel, and the mixture was stirred at room temperature for 7 hours. After the reaction was complete, water (100 mL) was added, and the precipitated solid was filtered off. The resulting solid was recrystallized from toluene to give the following compound (A-15) as a yellow powder (yield: 0.6 g, 24%).

[0223] 1H-NMR (400MHz, THF-d8): δ (ppm) = 8.94 (1H), 8.09 (3H), 7.72 (1H), 7.63 (3H), 7.54 (1H), 7.21-7.09 (6H), 7.01-6.92 (18H), 6.75 (16H), 3.71 (24H).

[0224] [Chemical Formula 28]

[0225]

[0226] [Synthetic Example 9] Synthesis of Compound (A-22)

[0227] Under a nitrogen atmosphere, N,N,N',N'-tetratetra(4-methoxyphenyl)-9H-carbazole-3,6-diamine (2.8 g, manufactured by Tokyo Chemical Industry Co., Ltd.), DMF (32 mL), potassium carbonate (670 mg, manufactured by Pure Chemical Industries Co., Ltd.), and 4,6-dichloro-2-(methylthio)pyrimidine (0.4 g, manufactured by Tokyo Chemical Industry Co., Ltd.) were added to a reaction vessel, and the mixture was stirred at 70 °C for 7 hours. After the reaction was completed, water (100 mL) was added, and the precipitated solid was filtered off. The obtained solid was recrystallized from acetone to give the following compound (A-22) as a yellow powder (yield: 1.1 g, 37%).

[0228] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 8.02 (4H), 7.54 (4H), 7.44 (1H), 7.07 (4H), 6.85 (16H), 6.79 (16H), 3.68 (24H), 2.65 (3H).

[0229] [Chemical Formula 29]

[0230]

[0231] [Synthetic Example 10] Synthesis of Compound (A-23)

[0232] In a nitrogen atmosphere, N,N,N',N'-tetratetra(4-methoxyphenyl)-9H-carbazole-3,6-diamine (2.8 g, manufactured by Tokyo Chemical Industry Co., Ltd.), DMF (32 mL), potassium carbonate (670 mg, manufactured by Pure Chemical Industries Co., Ltd.), and 4,6-dichloro-2-(methylthio)pyrimidine (0.4 g, manufactured by Tokyo Chemical Industry Co., Ltd.) were added to a reaction vessel, and the mixture was stirred at 70 °C for 7 hours. After the reaction was complete, water (100 mL) was added, and the precipitated solid was collected by filtration. The obtained solid was subjected to silica gel column chromatography at atmospheric pressure using toluene as a solvent. The fraction containing compound (A-23) was collected and dried to give the following compound (A-23) as a yellow powder (yield: 0.4 g, 13%).

[0233] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 8.03 (4H), 7.58-7.56 (5H), 7.06 (4H), 6.91 (16H), 6.85 (16H), 3.71 (24H), 2.61 (3H).

[0234] [Chemical Formula 30]

[0235]

[0236] [Example 1] Fabrication and Evaluation of Photoelectric Conversion Components

[0237] Glass with a FLAT ITO film (conductive support 1, trade name, manufactured by GEOMATEC) was ultrasonically cleaned with isopropanol and then subjected to UV ozone treatment. Under a dry atmosphere with a relative humidity below 10% RH, a tin(IV) oxide and 15% in H2O colloidal dispersion (trade name, manufactured by Alfa Aesar) was spin-coated onto the ITO film as a coating solution to form a coated film. The coated film was then heated at 150°C for 30 minutes using a hot plate, thereby forming a tin oxide layer (electron transport layer 2) with a thickness of approximately 20 nm.

[0238] Under a dry atmosphere with a relative humidity below 10% RH, formamidinium hydroiodate (1M, manufactured by Tokyo Chemical Industry Co., Ltd.), lead(II) iodide (1.1M, manufactured by Tokyo Chemical Industry Co., Ltd.), methylamine hydrobromide (0.2M, manufactured by Tokyo Chemical Industry Co., Ltd.), and lead(II) bromide (0.2M, manufactured by Tokyo Chemical Industry Co., Ltd.) were dissolved in a mixed solvent of dimethylformamide and dimethyl sulfoxide (volume ratio 4:1). A dimethyl sulfoxide solution of cesium iodide (1.5M, manufactured by Tokyo Chemical Industry Co., Ltd.) was added to prepare a perovskite precursor solution with a cesium content of 5 mol% by composition.

[0239] Under a dry atmosphere with a relative humidity below 10% RH, the prepared perovskite precursor solution was dropwise added and spin-coated onto the tin oxide layer (electron transport layer 2). It should be noted that 0.35 mL of chlorobenzene was added during the spin-coating process, thereby forming the perovskite precursor coating film. Subsequently, the coating film was heated at 100°C for 1 hour using a hot plate, thereby forming a Cs(MAFA)Pb(IBr)3 layer (photoelectric conversion layer 3) with a thickness of approximately 500 nm.

[0240] Under a dry atmosphere with a relative humidity below 10% RH, lithium bis(trifluoromethanesulfonyl)imide, used as a dopant, was dissolved in acetonitrile at a concentration of 1.8 M to prepare a dopant solution. Separately, compound (A-1) obtained in Synthesis Example 1 was added to chlorobenzene at a concentration of 32 mM and dissolved at 80°C to obtain a preparation solution. After cooling the preparation solution, 4-tert-butylpyridine was added to the preparation solution so that the amount of 4-tert-butylpyridine relative to compound (A-1) was 3.3 equivalents. Further addition of the above dopant solution to make the amount of lithium bis(trifluoromethanesulfonyl)imide relative to compound (A-1) 0.5 equivalents prepared a coating solution for a hole transport layer.

[0241] In a dry atmosphere with a relative humidity below 10% RH, a hole transport layer coating solution was spin-coated onto the Cs(MAFA)Pb(IBr)3 layer (photoelectric conversion layer 3) to form a hole transport layer 4 with a film thickness of about 100 nm.

[0242] Vacuum evaporation was used to deposit a hole transport layer 4 at a vacuum level of approximately 1×10⁻⁶. -4 Pa is used to form a gold film of about 80 nm to create a gold electrode (counter electrode 5) and fabricate a photoelectric conversion element.

[0243] Simulated sunlight (AM1.5, 1000W / m²) generated by a white light irradiation device (manufactured by Spectrometer Co., Ltd., trade name: OTENTO-SUN SH type) is irradiated from the conductive support side of the aforementioned photoelectric conversion element. 2 The current-voltage characteristics were measured using a source meter (KEITHLEY, trade name: Model 2400 Series SourceMeter). The short-circuit current density Jsc [mA / cm²] was obtained from this. 2 The initial photoelectric conversion efficiency (PCE) was calculated using the open-circuit voltage Voc[V] and the curve factor FF. The results are shown in Table 1. It should be noted that the results shown in Table 1 are obtained by standardizing the results of each embodiment based on the results of Comparative Example 1 described below.

[0244] [Example 2]

[0245] In the preparation of the coating solution for the hole transport layer, no dopant solution of 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide was added as an additive. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 1, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 2. It should be noted that the results shown in Table 2 were normalized based on the results of Comparative Example 2 described later.

[0246] [Example 3]

[0247] Instead of compound (A-1), compound (A-2) was used and dissolved in chlorobenzene at a concentration of 32 mM. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 1, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 1.

[0248] [Example 4]

[0249] In the preparation of the coating solution for the hole transport layer, no dopant solution of 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide was added. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 3, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 2.

[0250] [Example 5]

[0251] Instead of compound (A-1), compound (A-3) was used and dissolved at room temperature at a concentration of 34 mM. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 1, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 1.

[0252] [Example 6]

[0253] In the preparation of the coating solution for the hole transport layer, no dopant solution of 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide was added. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 5, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 2.

[0254] [Example 7]

[0255] Compound (A-4) was used instead of compound (A-1) and dissolved at room temperature at a concentration of 34 mM. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 1, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 1.

[0256] [Example 8]

[0257] In the preparation of the coating solution for the hole transport layer, no dopant solution of 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide was added. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 7, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 2.

[0258] [Example 9]

[0259] Compound (A-5) was used instead of compound (A-1) and dissolved at room temperature at a concentration of 53 mM. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 1, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 1.

[0260] [Example 10]

[0261] In the preparation of the coating solution for the hole transport layer, no dopant solution of 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide was added. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 9, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 2.

[0262] [Example 11]

[0263] Compound (A-6) was used instead of compound (A-1) and dissolved at room temperature at a concentration of 53 mM. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 1, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 1.

[0264] [Example 12]

[0265] In the preparation of the coating solution for the hole transport layer, no dopant solution of 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide was added. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 11, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 2.

[0266] [Example 13]

[0267] Compound (A-8) was used instead of compound (A-1) and dissolved at room temperature at a concentration of 64 mM. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 1, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 1.

[0268] [Example 14]

[0269] In the preparation of the coating solution for the hole transport layer, no dopant solution of 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide was added. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 13, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 2.

[0270] [Example 15]

[0271] Compound (A-15) was used instead of compound (A-1) and dissolved at room temperature at a concentration of 32 mM. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 1, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 1.

[0272] [Example 16]

[0273] In the preparation of the coating solution for the hole transport layer, no dopant solution of 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide was added. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 15, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 2.

[0274] [Example 17]

[0275] Compound (A-22) was used instead of compound (A-1) and dissolved at room temperature at a concentration of 33 mM. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 1, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 1.

[0276] [Example 18]

[0277] In the preparation of the coating solution for the hole transport layer, no dopant solution of 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide was added. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 17, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 2.

[0278] [Example 19]

[0279] Compound (A-23) was used instead of compound (A-1) and dissolved at room temperature at a concentration of 33 mM. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 1, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 1.

[0280] [Comparative Example 1]

[0281] Instead of compound (A-1), Spiro-OMeTAD (manufactured by Sigma-Aldrich, hereinafter Comparative Compound (B-1)) was used as the standard hole transport material and dissolved at room temperature at a concentration of 70 mM. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Example 1, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 1. As mentioned above, in Table 1, Comparative Example 1 serves as a benchmark example for standardizing the results of each example. Therefore, the result of Comparative Example 1 is "1.00" in all evaluation items.

[0282] [Chemical Formula 31]

[0283]

[0284] [Comparative Example 2]

[0285] In the preparation of the coating solution for the hole transport layer, no dopant solution of 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide was added. Otherwise, the photoelectric conversion element was fabricated in the same manner as in Comparative Example 1, and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results are shown in Table 2. As mentioned above, in Table 2, Comparative Example 2 serves as a benchmark example for standardizing the results of each example. Therefore, the result of Comparative Example 2 is "1.00" in all evaluation items.

[0286] [Table 1]

[0287]

[0288] [Table 2]

[0289]

[0290] As shown in Table 1, the photoelectric conversion elements of the embodiments using the compound of the present invention represented by general formula (1) as the hole transport material exhibit equal or better photoelectric conversion efficiencies compared to the photoelectric conversion elements of the comparative examples using the comparative compound (B-1) as a conventional standard hole transport material. In particular, as shown in Table 2, this tendency is significant when no additives are used. It should be noted that the actual initial photoelectric conversion efficiencies of each embodiment are far greater than 10% compared to the comparative examples, and their initial photoelectric conversion efficiencies are sufficiently high even for results equivalent to those of the comparative examples.

[0291] After obtaining the initial photoelectric conversion efficiency described above, the photoelectric conversion elements involved in Examples 1-8, 11, 12, and 14-18, as well as Comparative Examples 1 and 2, were placed in a vacuum constant temperature desiccator (manufactured by Tokyo Riko Instrument Co., Ltd., trade name: VOS-310C) and stored at 85°C for 1,000 hours. After storage, as in Example 1 above, the current-voltage characteristics were measured again under simulated sunlight irradiation to obtain the photoelectric conversion efficiency after 1,000 hours of heating. Using the initial photoelectric conversion efficiency described above and the obtained photoelectric conversion efficiency after 1,000 hours of heating, the retention rate (%) was calculated using the following formula (a-1). The results are shown in Tables 3 and 4.

[0292] [Mathematical Expression 1]

[0293]

[0294] [Table 3]

[0295] Hole transport materials additive Retention rate [%) Example 1 Compound (A-1) have 43.58 Example 3 Compound (A-2) have 44.76 Example 5 Compound (A-3) have 51.11 Example 7 Compound (A-4) have 48.23 Example 11 Compound (A-6) have 42.43 Example 15 Compound (A-15) have 61.89 Example 17 Compound (A-22) have 50.13 Comparative Example 1 Compare compound (B-1) have 41.20

[0296] [Table 4]

[0297] Hole transport materials additive Retention rate [%) Example 2 Compound (A-1) none 63.48 Example 4 Compound (A-2) none 63.77 Example 6 Compound (A-3) none 63.76 Example 8 Compound (A-4) none 52.09 Example 12 Compound (A-6) none 44.40 Example 14 Compound (A-8) none 67.77 Example 16 Compound (A-15) none 55.48 Example 18 Compound (A-22) none 61.16 Comparative Example 2 Compare compound (B-1) none 40.07

[0298] As shown in Tables 3 and 4, the photoelectric conversion element of the embodiments using the compound of the present invention represented by general formula (1) as the hole transport material maintains a higher photoelectric conversion efficiency and exhibits superior heat resistance even after heating for 1,000 hours, compared to the photoelectric conversion element of the comparative example using the comparative compound (B-1) as a conventional standard hole transport material. In particular, this tendency is significant when no additives are used (Table 4).

[0299] By using the compound of the present invention represented by general formula (1) as a hole transport material for a photoelectric conversion element, a photoelectric conversion element with excellent photoelectric conversion efficiency and heat resistance can be obtained. By using this photoelectric conversion element as a solar cell, solar energy can be efficiently converted into electrical energy, providing clean energy. Therefore, the present invention has high industrial applicability.

Claims

1. A compound represented by the following general formula (1), [Chemical Formula 1] In general formula (1), L 1 ~L 3 Each independently is: The following general formula (2) represents the following groups: hydrogen atom, halogen atom, hydroxyl group, alkyl group having 1 to 20 carbon atoms (optionally having substituents), alkenyl group having 2 to 20 carbon atoms (optionally having substituents), alkoxy group having 1 to 20 carbon atoms (optionally having substituents), aryloxy group having 6 to 30 carbon atoms (optionally having substituents). optional amino groups having 0 to 50 carbon atoms with substituents Optionally having a thio group having 0 to 20 carbon atoms as a substituent, Optionally having a substituent of an alkyl sulfinyl group having 1 to 20 carbon atoms, Optionally having a substituent of an alkyl sulfonyl group having 1 to 20 carbon atoms, An aromatic hydrocarbon group having 6 to 30 carbon atoms optionally having a substituent, or a heterocyclic group having 5 to 30 cyclic atoms optionally having a substituent. L 1 ~L 3 At least one of them is a group represented by the following general formula (2), [Chemical Formula 2] In general formula (2), R 1 ~R 20 Each independently is: hydrogen atom, Optionally, a straight-chain or branched alkyl group having 1 to 20 carbon atoms with substituents; a straight-chain or branched alkenyl group having 2 to 20 carbon atoms with substituents; or a cycloalkyl group having 3 to 10 carbon atoms with substituents. Optionally, a straight-chain or branched alkoxy group having 1 to 20 carbon atoms and a substituent; or an aryloxy group having 6 to 30 carbon atoms and a substituent. An amino group having 0 to 20 carbon atoms optionally having a substituent, or a thio group having 0 to 20 carbon atoms optionally having a substituent, A 1 ~A 3 Represents nitrogen atom or C(R) 1a ), A 1 ~A 3 Any two of them are nitrogen atoms. R 1a for: hydrogen atom, Optionally, a straight-chain or branched alkyl group having 1 to 20 carbon atoms with substituents; a straight-chain or branched alkenyl group having 2 to 20 carbon atoms with substituents; or a cycloalkyl group having 3 to 10 carbon atoms with substituents. Optionally, a straight-chain or branched alkoxy group having 1 to 20 carbon atoms and a substituent; or an aryloxy group having 6 to 30 carbon atoms and a substituent. An amino group having 0 to 20 carbon atoms optionally having a substituent, or a thio group having 0 to 20 carbon atoms optionally having a substituent.

2. The compound according to claim 1, wherein, In the general formula (1), L 1 for: hydrogen atom, optional amino groups having 0 to 50 carbon atoms with substituents Optionally having a thio group having 0 to 20 carbon atoms as a substituent, Optionally having a substituent of an alkyl sulfinyl group having 1 to 20 carbon atoms, Optionally having a substituent of an alkyl sulfonyl group having 1 to 20 carbon atoms, Optionally having a substituent of an aromatic hydrocarbon group having 6 to 20 carbon atoms, or A heterocyclic group having 5 to 30 cyclic atoms optionally having substituents.

3. The compound according to claim 1, wherein, The compound represented by the general formula (1) is a compound represented by the following general formula (3) or general formula (4). [Chemical Formula 3] In general formulas (3) and (4), L 1 L 2 A 1 ~A 3 and R 1 ~R 20 Each is defined as described in general formulas (1) and (2), wherein L in general formula (3) 1 and L 2 The L in general formula (4) represents a group other than the group represented by the general formula (2). 1 This refers to groups other than those represented by the general formula (2).

4. The compound according to claim 1, wherein, In the general formula (2), R 1 ~R 20 An alkoxy group consisting of 1 to 20 straight-chain or branched carbon atoms, which may be hydrogen atoms or optionally have substituents.

5. A hole transport material comprising the compound according to any one of claims 1 to 4.

6. A photoelectric conversion element using the hole transport material as described in claim 5.

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