Compounds having a sulfonic acid base, and photoelectric conversion elements using the compound.

Abstract

The present invention provides: a compound which is useful as a hole transport material for photoelectric conversion elements, and which is represented by general formula (1); and a photoelectric conversion element which uses this compound in a hole transport layer.

Description

[Technical Field]

[0001] The present invention relates to a compound having a sulfonic acid base, a photoelectric conversion element using the compound, and a perovskite solar cell. [Background technology]

[0002] In recent years, solar power generation has attracted attention as a clean energy source, and the development of solar cells is progressing rapidly. Among these, the development of solar cells using perovskite materials in the photoelectric conversion layer (hereinafter referred to as perovskite solar cells) is attracting attention as a next-generation solar cell that is low-cost and can be manufactured using a solution process (for example, Patent Document 1, Non-Patent Documents 1-2).

[0003] Perovskite solar cells often use hole transport materials within the device. The purposes of using them include (1) improving photoelectric conversion efficiency and (2) protecting the perovskite material, which is susceptible to the effects of moisture and oxygen (see, for example, Non-Patent Document 3). Spiro-OMeTAD is often used as a standard hole transport material, and there are few reports of hole transport materials that contribute more to photoelectric conversion characteristics than this material.

[0004] When hole transport materials are used in elements of perovskite solar cells, conventional methods for fabricating elements using organic compounds as hole transport materials involve adding dopants, which are additives, to the hole transport material. These dopants are used to reduce the electrical resistance of the hole transport material (for example, Non-Patent Documents 3-4).

[0005] However, the use of dopants, which are additives, not only complicates the manufacturing process but also leads to increased manufacturing costs. Furthermore, it has been reported that dopants promote moisture absorption, corrode the photoelectric conversion layer, and degrade the hole transport layer due to volatilization, which leads to a decrease in the characteristics of the device (for example, Non-Patent Literature 5). Therefore, there is a need for the development of photoelectric conversion devices that have a hole transport layer without dopants and exhibit high photoelectric conversion characteristics and durability. On the other hand, there are cases where dopants must be used to obtain good photoelectric conversion efficiency. Therefore, there is also a need for the development of photoelectric conversion devices that contain dopants but show little deterioration in device characteristics over time. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2017 / 104792 [Non-patent literature]

[0007] [Non-Patent Document 1] J. Am. Chem. Soc., 2009, Vol. 131, pp. 6050-6051 [Non-Patent Document 2] Science, 2012, Vol. 388, pp. 643-647 [Non-Patent Document 3] Chem. Sci.,2019,10,P.6748-6769 [Non-Patent Document 4] Adv. Funct. Mater., 29, 24,2019,1901296 [Non-Patent Document 5] J. Am. Chem. Soc., 2018, 140, 48, 16720-16730 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The problem that the present invention aims to solve is to provide a compound useful as a hole transport material for photoelectric conversion elements that does not contain dopants as additives, and a photoelectric conversion element and a perovskite solar cell that use the compound in the hole transport layer and have good photoelectric conversion characteristics. Another problem that the present invention aims to solve is to provide a compound useful as a hole transport material for photoelectric conversion elements that does not experience a significant decrease in element characteristics over time, even when it contains dopants. [Means for solving the problem]

[0009] To solve the above problems, the inventors diligently studied ways to improve photoelectric conversion characteristics and found that by using a compound having a specific structure as a hole transport layer, a highly efficient photoelectric conversion element and a perovskite solar cell can be obtained. In other words, the gist of the present invention is as follows.

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

[0011] [ka]

[0012] [In the formula, R 1 teeth, Linear or branched molecules having 1 to 18 carbon atoms, which may have substituents. Alkilen basis, Linear or branched molecules having 2 to 20 carbon atoms, which may have substituents. Alkenirene basis, Linear or branched molecules having 2 to 20 carbon atoms, which may have substituents. Alkinirene basis, A carbon atom having 3 to 12 carbon atoms, which may have substituents. Cycloalkylene basis, A carbon atom having 6 to 36 carbon atoms, which may have substituents. divalent Aromatic hydrocarbon group, Alternatively, ring-forming atoms numbering 5 to 36, which may have substituents divalent It is a heterocyclic group, X represents a monovalent cation excluding hydrogen ions. R 2 ~R 9 Each of them operates independently. hydrogen atom, Linear or branched alkyl groups having 1 to 18 carbon atoms, which may have substituents. A linear or branched alkenyl group having 2 to 20 carbon atoms, which may have substituents. A linear or branched alkynyl group having 2 to 20 carbon atoms, which may have substituents. Cycloalkyl groups having 3 to 12 carbon atoms, which may have substituents. A linear or branched alkoxy group having 1 to 20 carbon atoms, which may have substituents. A cycloalkoxy group having 3 to 10 carbon atoms, which may have substituents. A linear or branched alkoxycarbonyl group having 1 to 18 carbon atoms, which may have substituents. A thio group having 1 to 18 carbon atoms, which may have substituents. A C1-C20 amino group which may have substituents, Aromatic hydrocarbon groups having 6 to 36 carbon atoms, which may have substituents. Alternatively, it represents a heterocyclic group with 5 to 36 ring-forming atoms, which may have substituents.

[0013] 2. In the above general formula (1), R 1 However, linear or branched carbon-1 to 18 carbon atoms may have substituents. Alkilen The compound described in item 1 above, which is the base.

[0014] 3. In the above general formula (1), R 2 ~R 9 The compound according to claim 1 or claim 2, wherein at least one of these is an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have substituents, or an amino group having 1 to 20 carbon atoms which may have substituents.

[0015] 4. The compound according to any one of items 1 to 3 above, wherein in the general formula (1) above, X is an alkali metal ion or an ammonium ion which may have a substituent.

[0016] 5. The compound according to item 4 above, wherein in the general formula (1), the alkali metal ion is at least one selected from the group consisting of sodium ions, potassium ions, rubidium ions, and cesium ions.

[0017] 6. A hole transport material containing any of the compounds described in items 1 to 5 above.

[0018] 7. A hole transport material composition for a photoelectric conversion element, comprising the hole transport material described in 6 above.

[0019] 8. A photoelectric conversion element using the hole transport material composition for photoelectric conversion described in item 7 above. [Effects of the Invention]

[0020] According to the compound having a sulfonic acid base and the hole transport layer using the compound according to the present invention, by using the compound between the photoelectric conversion layer and the electrode, a photoelectric conversion element and a perovskite solar cell with good photoelectric conversion efficiency can be obtained. [Brief explanation of the drawing]

[0021] [Figure 1] This is a schematic cross-sectional view showing the configuration of the photoelectric conversion element in the embodiments and comparative examples of the present invention. [Modes for carrying out the invention]

[0022] Embodiments of the present invention will be described in detail below. The hole transport layer of the present invention is used in photoelectric conversion elements and perovskite-type photoelectric conversion elements.

[0023] The following describes in detail the compounds represented by general formula (1), but the present invention is not limited to these.

[0024] In general formula (1), R 1 is a linear or branched group having 1 to 18 carbon atoms which may have a substituent, Alkilen a group, a linear or branched group having 2 to 20 carbon atoms which may have a substituent, Alkenirene a group, a linear or branched group having 2 to 20 carbon atoms which may have a substituent, Alkinirene a group, a group having 3 to 12 carbon atoms which may have a substituent, Cycloalkylene a group, an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent, divalent or a heterocyclic group having 5 to 36 ring-forming atoms which may have a substituent divalent is represented. In general formula (1), R

[0025] In the "linear or branched group having 1 to 18 carbon atoms which may have a substituent" represented by R<00​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Represented as "a linear or branched chain having 2 to 20 carbon atoms, which may have substituents" Alkenirene "The base" is a linear or branched chain of 2 to 20 carbon atoms. Alkenirene Specifically, the "foundation" is: vinylene group, 1- Propenylene basis, Arilen group, 1- Butenirene group, 2- Butenirene group, 1- Penthenylene group, 1- Hexenilene basis, Isopropenylene basis, Isobutenylene base, or these Alkenirene A linear or branched structure with 2 to 20 carbon atoms bonded together by multiple groups. Alkenirene It is possible to list the base, R 1 In this compound, one of the hydrogen atoms of the substituents mentioned above is substituted with a sulfonic acid base (-SO3X).

[0027] In general formula (1), R 1 Represented as "a linear or branched chain having 2 to 20 carbon atoms, which may have substituents" Alkinirene "The base" is a linear or branched chain of 2 to 20 carbon atoms. Alkinirene Specifically, the "foundation" is: Ethinirene group, 1- Propynylene group, 2- Propynylene group, 1- Butiniren group, 2- Butiniren base, 1-methyl-2- Propynylene group, 1- Pentinirene group, 2- Pentinirene base, 1-methyl-n- Butiniren group, 2-methyl-n- Butiniren group, 3-methyl-n- Butiniren group, 1- Hexynylene It is possible to list the base, R 1 In this compound, one of the hydrogen atoms of the substituents mentioned above is substituted with a sulfonic acid base (-SO3X).

[0028] In general formula (1), R 1 A carbon atom having 3 to 12 atoms which may have substituents, represented as "a carbon atom having 3 to 12 atoms which may have substituents" Cycloalkylene "The group with 3 to 12 carbon atoms" Cycloalkylene Specifically, the basis is cyclo propyleneBase, cyclo Butiren Base, cyclo Pentylene Base, cyclo Hexylene Base, cyclo Heptylene Base, cyclo Octylene Base, cyclo Decilen Base, cyclo Dodecilene It is possible to list the base, R 1 In this compound, one of the hydrogen atoms of the substituents mentioned above is substituted with a sulfonic acid base (-SO3X).

[0029] In general formula (1), R 1 A "carbon species having 6 to 36 atoms which may have substituents" divalent "Aromatic hydrocarbon groups" with "6 to 36 carbon atoms" divalent Specifically, "aromatic hydrocarbon groups" are: Phenylene basis, biphenylene basis, Terphenirene basis, Naphthylene basis, Anthraceniren base( Antrelen basis), Phenanthrylene basis, Fluorenylene basis, Indenirene basis, Pyrene basis, Perilenilen basis, Fluoranthenylene basis, Triphenylenerenine It is possible to list the base, R 1 In this case, one of the hydrogen atoms of the substituents mentioned above is substituted with a sulfonic acid base (-SO3X). In this invention, the aromatic hydrocarbon group includes a "condensed polycyclic aromatic group".

[0030] In general formula (1), R 1 Represented as "a ring-forming atom having 5 to 36 substituents" divalent "Heterocyclic groups" with "5 to 36 ring-forming atoms" divalent Specifically, as for "heterocyclic groups," Pyridylene basis, Pyrimidinylene basis, Triazinylene basis, Chieniren basis, Furiren base( Flanilene basis), Pyrrolylene basis, Imidazorilen basis, Pyrazolylene basis, Triazolylene basis, Kinoriren basis, Isoquinorylene basis, Naphthyldinylene basis, Acridine basis, Phenanthrolinylene basis, Benzofranilene basis, Benzothienylene basis, Oxazolylene basis, Indolilen basis, Carbazoline basis, Benzoxazolylene basis, Thiazolilen basis, Benzothiazolilen basis, Kinokisariniren basis, Benzimidazolylene basis, Pyrazolylene basis, Dibenzofuranylene basis, Dibenzothienylene basis, Carbonirene It is possible to list the base, R 1 In this compound, one of the hydrogen atoms of the substituents mentioned above is substituted with a sulfonic acid base (-SO3X).

[0031] In general formula (1), R 1 Represented as "a linear or branched chain having 1 to 18 carbon atoms, which may have substituents" Alkilen "group", "linear or branched chain having 2 to 20 carbon atoms, which may have substituents" Alkenirene "group", "linear or branched chain having 2 to 20 carbon atoms, which may have substituents" Alkinirene "group", "a group having 3 to 12 carbon atoms which may have substituents" Cycloalkylene "group", "a group having 6 to 36 carbon atoms which may have substituents" divalent Aromatic hydrocarbon group or ring-forming atom number 5 to 36, which may have substituents divalent Specifically, the "substituents" in a "heterocyclic group" are: Halogen atoms such as fluorine, chlorine, bromine, and iodine; cyano groups; hydroxyl groups; nitro groups; nitroso groups; carboxyl groups; phosphate groups; Carboxylic acid ester groups such as methyl ester groups and ethyl ester groups; Linear or branched alkyl groups having 1 to 18 carbon atoms, such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group, isopentyl group, n-hexyl group, 2-ethylhexyl group, heptyl group, octyl group, isooctyl group, nonyl group, and decyl group; Linear or branched alkenyl groups with 2 to 20 carbon atoms, such as vinyl groups, 1-propenyl groups, allyl groups, 1-butenyl groups, 2-butenyl groups, 1-pentenyl groups, 1-hexenyl groups, isopropenyl groups, and isobutenyl groups; Linear or branched alkoxy groups with 1 to 18 carbon atoms, such as methoxy, ethoxy, propoxy, t-butoxy, pentyloxy, and hexyloxy groups; Aromatic hydrocarbon groups with 6 to 30 carbon atoms, such as phenyl, naphthyl, anthryl, phenanthryl, and pyrenyl groups; Heterocyclic groups with 5 to 30 ring-forming atoms, such as pyridyl group, pyrimidylinyl group, triazinyl group, thienyl group, furyl group (furanyl group), pyrrolyl group, imidazolyl group, pyrazolyl group, triazolyl group, quinolyl group, isoquinolyl group, naphthyldinyl group, acridinyl group, phenanthrolinyl group, benzofuranyl group, benzothienyl group, oxazolyl group, indolyl group, carbazolyl group, benzoxazolyl group, thiazolyl group, benzothiazolyl group, quinoxalinyl group, benzimidazolyl group, pyrazolyl group, dibenzofuranyl group, dibenzothienyl group, and carbonillyl group; Amino groups having 0 to 18 carbon atoms, including unsubstituted amino groups (-NH2), monosubstituted amino groups such as ethylamino groups, acetylamino groups, and phenylamino groups, or disubstituted amino groups such as diethylamino groups, diphenylamino groups, and acetylphenylamino groups; Thio groups with 0 to 18 carbon atoms, such as unsubstituted thio groups (thiol groups: -SH), methylthio groups, ethylthio groups, propylthio groups, hexa-5-ene-3-thio groups, phenylthio groups, and biphenylthio groups; Examples include the above. These "substituents" may consist of only one or more, and if there are multiple substituents, they may be identical or different from each other. Furthermore, these "substituents" may have further substituents as exemplified above.

[0032] In general formula (1), R 1In the sulfonic acid base (-SO3X), X represents a monovalent cation excluding the hydrogen ion. Specifically, the monovalent cation is preferably an alkali metal ion, an optionally substituted ammonium ion, or an optionally substituted phosphonium ion, more preferably an alkali metal ion or an optionally substituted ammonium ion, and particularly preferably an alkali metal ion, but is not limited to these.

[0033] Examples of alkali metals include lithium ions, sodium ions, potassium ions, rubidium ions, cesium ions, and francium ions, and it is preferable that the alkali metal be at least one selected from the group consisting of sodium ions, potassium ions, rubidium ions, and cesium ions.

[0034] Furthermore, examples of ammonium ions that may have substituents include methylammonium ion, methylammonium monofluoride ion, methylammonium difluoride ion, methylammonium trifluoride ion, ethylammonium ion, isopropylammonium ion, n-propylammonium ion, isobutylammonium ion, n-butylammonium ion, t-butylammonium ion, dimethylammonium ion, diethylammonium ion, phenylammonium ion, benzylammonium ion, phenethylammonium ion, guanidium ion, formamidinium ion, acetamidinium ion, imidazolium ion, tri-n-butylammonium ion, tetra-n-butylammonium ion, and the like.

[0035] In general formula (1), R 1 This is a linear or branched molecule having 1 to 18 carbon atoms, which may have substituents. Alkilen It is preferable that it be a group. 1 This refers to a molecule with a total number of carbon atoms, including substituents, of 18 or less. Alkilen It is more preferable that it be a group, and that the total number of carbon atoms, including substituents, is 10 or less. AlkilenIt is even more preferable that it be a group, and that the total number of carbon atoms, including substituents, is 6 or less. Alkilen It is particularly preferable that it be a base.

[0036] In general formula (1), R 2 ~R 9 Each of them operates independently. hydrogen atom, Linear or branched alkyl groups having 1 to 18 carbon atoms, which may have substituents. A linear or branched alkenyl group having 2 to 20 carbon atoms, which may have substituents. A linear or branched alkynyl group having 2 to 20 carbon atoms, which may have substituents. Cycloalkyl groups having 3 to 12 carbon atoms, which may have substituents. A linear or branched alkoxy group having 1 to 20 carbon atoms, which may have substituents. A cycloalkoxy group having 3 to 10 carbon atoms, which may have substituents. A linear or branched alkoxycarbonyl group having 1 to 18 carbon atoms, which may have substituents. A thio group having 1 to 18 carbon atoms, which may have substituents. A C1-C20 amino group which may have substituents, Aromatic hydrocarbon groups having 6 to 36 carbon atoms, which may have substituents. Alternatively, it represents a heterocyclic group having 5 to 36 ring-forming atoms, which may have substituents.

[0037] In general formula (1), R 2 ~R 9 In the "linear or branched alkyl group having 1 to 18 carbon atoms that may have substituents" represented by , the "linear or branched alkyl group having 1 to 18 carbon atoms" is as follows: Specifically, examples include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group, isopentyl group, n-hexyl group, 2-ethylhexyl group, heptyl group, octyl group, isooctyl group, nonyl group, decyl group, and the like.

[0038] In general formula (1), R 2 ~R 9In the "linear or branched alkenyl group having 2 to 20 carbon atoms that may have substituents" represented by , the "linear or branched alkenyl group having 2 to 20 carbon atoms" is as follows: Specifically, examples include vinyl groups, 1-propenyl groups, allyl groups, 1-butenyl groups, 2-butenyl groups, 1-pentenyl groups, 1-hexenyl groups, isopropenyl groups, isobutenyl groups, or linear or branched alkenyl groups with 2 to 20 carbon atoms formed by the bonding of multiple of these alkenyl groups.

[0039] In general formula (1), R 2 ~R 9 In the "linear or branched alkynyl group having 2 to 20 carbon atoms, which may have substituents" expressed as, the "linear or branched alkynyl group having 2 to 20 carbon atoms" is as follows: Examples include ethynyl group, 1-propynyl group, 2-propynyl group, 1-butynyl group, 2-butynyl group, 1-methyl-2-propynyl group, 1-pentynyl group, 2-pentynyl group, 1-methyl-n-butynyl group, 2-methyl-n-butynyl group, 3-methyl-n-butynyl group, and 1-hexynyl group.

[0040] In general formula (1), R 2 ~R 9 In the "cycloalkyl group having 3 to 12 carbon atoms that may have substituents" represented by the expression, the "cycloalkyl group having 3 to 12 carbon atoms" is as follows: Specifically, examples include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclodecyl group, and cyclododecyl group.

[0041] In general formula (1), R 2 ~R 9 In the expression "linear or branched alkoxy groups having 1 to 20 carbon atoms that may have substituents," examples of "linear or branched alkoxy groups having 1 to 20 carbon atoms" include methoxy, ethoxy, propoxy, n-butoxy, n-pentyloxy, n-hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, isopropoxy, isobutoxy, s-butoxy, t-butoxy, isooctyloxy, t-octyloxy, phenoxy, tolyloxy, biphenylyloxy, terphenylyloxy, naphthyloxy, anthryloxy, phenanthryloxy, fluorenyloxy, and indenyloxy groups.

[0042] In general formula (1), R 2 ~R 9In the expression "linear or branched cycloalkoxy group having 3 to 10 carbon atoms, which may have substituents," specific examples of "linear or branched cycloalkoxy group having 3 to 10 carbon atoms" include cyclopropoxy group, cyclobutoxy group, cyclopentyloxy group, and cyclohexyloxy group.

[0043] In general formula (1), R 2 ~R 9 In the expression "linear or branched alkoxycarbonyl group having 1 to 18 carbon atoms which may have substituents," specific examples of the "alkoxycarbonyl group having 1 to 18 carbon atoms" include methoxycarbonyl groups and ethoxycarbonyl groups.

[0044] In general formula (1), R 2 ~R 9 In the expression "thio group having 1 to 18 carbon atoms which may have substituents," specific examples of "thio group having 1 to 18 carbon atoms" include methylthio group, ethylthio group, propylthio group, phenylthio group, biphenylthio group, and the like.

[0045] In general formula (1), R 2 ~R 9 In the expression "amino group having 1 to 20 carbon atoms which may have substituents," specific examples of "amino group having 1 to 20 carbon atoms" include monosubstituted amino groups such as ethylamino group, acetylamino group, and phenylamino group, and disubstituted amino groups such as diethylamino group, diphenylamino group, and acetylphenylamino group.

[0046] In general formula (1), R 2 ~R 9 In the "aromatic hydrocarbon group having 6 to 36 carbon atoms that may have substituents" represented by , the "aromatic hydrocarbon group having 6 to 36 carbon atoms" is as follows: Specifically, examples include phenyl group, biphenyl group, terphenyl group, naphthyl group, biphenyl group, anthracenyl group (anthryl group), phenanthryl group, fluorenyl group, indenyl group, pyrenyl group, perilenyl group, fluoranthenyl group, triphenylenyl group, and the like. In this invention, aromatic hydrocarbon groups include "condensed polycyclic aromatic groups".

[0047] In general formula (1), R 2~R 9 In the "heterocyclic group with 5 to 36 ring-forming atoms that may have substituents" expressed as, the "heterocyclic group with 5 to 36 ring-forming atoms" is as follows: Specifically, examples include pyridyl group, pyrimidylinyl group, triazinyl group, thienyl group, furyl group (furanyl group), pyrrolyl group, imidazolyl group, pyrazolyl group, triazolyl group, quinolyl group, isoquinolyl group, naphthyldinyl group, acridinyl group, phenanthrolinyl group, benzofuranyl group, benzothienyl group, oxazolyl group, indolyl group, carbazolyl group, benzoxazolyl group, thiazolyl group, benzothiazolyl group, quinoxalinyl group, benzimidazolyl group, pyrazolyl group, dibenzofuranyl group, dibenzothienyl group, and carbonillyl group.

[0048] In general formula (1), R 2 ~R 9 In the phrase "a linear or branched alkyl group having 1 to 18 carbon atoms which may have substituents," "a linear or branched alkenyl group having 2 to 20 carbon atoms which may have substituents," "a linear or branched alkynyl group having 2 to 20 carbon atoms which may have substituents," "a cycloalkyl group having 3 to 12 carbon atoms which may have substituents," "a linear or branched alkoxy group having 1 to 20 carbon atoms which may have substituents," "a cycloalkoxy group having 3 to 10 carbon atoms which may have substituents," "a linear or branched alkoxycarbonyl group having 1 to 18 carbon atoms which may have substituents," "a thio group having 1 to 18 carbon atoms which may have substituents," "an amino group having 1 to 20 carbon atoms which may have substituents," "an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have substituents," or "a heterocyclic group having 5 to 36 ring-forming atoms which may have substituents," the substituents are as follows: In general formula (1), R 1 Examples of similar terms include "linear or branched alkyl groups having 1 to 18 carbon atoms, which may have substituents," as expressed by .

[0049] In general formula (1), R 2 ~R 9 Of these, at least one is preferably an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have substituents, or an amino group having 1 to 20 carbon atoms which may have substituents. In general formula (1), R 2 ~R 9 Of these, at least two are more preferably aromatic hydrocarbon groups having 6 to 36 carbon atoms, which may have substituents, or amino groups having 1 to 20 carbon atoms, which may have substituents. In general formula (1), R 3 and R8 Each of these is an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have substituents, or an amino group having 1 to 20 carbon atoms which may have substituents, or R 4 and R 7 It is more preferable that each of these is an aromatic hydrocarbon group having 6 to 36 carbon atoms, which may have substituents, or an amino group having 1 to 20 carbon atoms, which may have substituents. In this case, the remaining R 2 , R 4 ~R 7 and R 9 , or the remaining R 2 , R 3 , R 5 , R 6 , R 8 and R 9 It is preferable that it is a hydrogen atom. In general formula (1), R 3 and R 8 Each of these is a diphenylamino group which may have substituents, or an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have substituents or a diphenylamino group or a carbazole group, or R 4 and R 7 It is more preferable that each of these is a diphenylamino group which may have substituents, or an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have substituents or is substituted with a diphenylamino group which may have substituents or a carbazole group. In this case, the remaining R 2 , R 4 ~R 7 and R 9 , or the remaining R 2 , R 3 , R 5 , R 6 , R 8 and R 9 It is preferable that R is a hydrogen atom. In this case, 3 and R 8 or R 4 and R 7 Preferably, the total number of carbon atoms, including substituents, is 50 or less, more preferably 40 or less, and even more preferably 30 or less.

[0050] Specific examples of compounds represented by the general formula (1) of the present invention are shown below, but the present invention is not limited to these. Furthermore, the following exemplary compounds are described with some hydrogen atoms, carbon atoms, etc. omitted, and represent only one example of possible isomers, encompassing all other isomers. In addition, each compound may be a mixture of two or more isomers.

[0051] [ka]

[0052] [ka]

[0053] [ka]

[0054] [ka]

[0055] [ka]

[0056] [ka]

[0057] [ka]

[0058] [ka]

[0059] The compound represented by the general formula (1) of the present invention can be synthesized by known methods such as those described in Japanese Patent Application No. 2018-135255. As an example, the synthesis of compound (A-1) will be described. Compound (A-1) can be obtained by introducing the corresponding substituent to 3,6-dibromocarbazole via a Suzuki-Miyaura coupling reaction or a Buchwald reaction, and then reacting it with the corresponding sultone. Similarly, compounds represented by the general formula (1) can be obtained by known methods using halogenated carbazole derivatives as precursors.

[0060] The compounds represented by the general formula (1) of the present invention can be purified by column chromatography, adsorption purification using silica gel, activated carbon, activated clay, etc., or by recrystallization or crystallization with a solvent. Alternatively, it is effective to use a compound with increased purity obtained by using a combination of these methods. Furthermore, these compounds can be identified by nuclear magnetic resonance analysis (NMR).

[0061] The compound represented by general formula (1) of the present invention can be used as a hole transport material contained in a hole transport layer for organic electronic devices such as photoelectric conversion elements and organic EL elements.

[0062] Preferred embodiments of the photoelectric conversion element of the present invention will be described below.

[0063] <Photoelectric conversion element> The photoelectric conversion element of the present invention typically comprises a conductive support 1, an electron transport layer 2, a photoelectric conversion layer 3, a hole transport layer 4, and a counter electrode 5, as shown in the schematic cross-sectional view of Figure 1. Furthermore, a multilayer structure can be adopted in which a hole transport layer is inserted between the photoelectric conversion layer 3 and the hole transport layer 4, with the aim of preventing the diffusion of dopants.

[0064] The photoelectric conversion element of the present invention preferably comprises a conductive support 1, an electron transport layer 2, a photoelectric conversion layer 3, a hole transport layer 4, and a counter electrode 5, as shown in Figure 1, but is not limited thereto. Furthermore, the photoelectric conversion element of the present invention is preferably used as a solar cell, and is more preferably a perovskite type photoelectric conversion element, but is not limited thereto. In the present invention, the perovskite type photoelectric conversion element preferably comprises 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 in this order. Alternatively, it may be configured in the order of conductive support, hole transport layer, photoelectric conversion layer (perovskite layer), electron transport layer, and counter electrode.

[0065] <Conductive support> In the photoelectric conversion element of the present invention, the conductive support 1 shown in Figure 1 needs to be translucent, capable of transmitting light that contributes to photoelectric conversion. Furthermore, since the conductive support is a component that has the function of extracting current from the photoelectric conversion layer, it is preferable that it be a conductive substrate. Specific examples of conductive materials include conductive transparent oxide semiconductors such as tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), tungsten-doped indium oxide (IWO), zinc-aluminum oxide (AZO), fluorine-doped tin oxide (FTO), indium oxide (In2O3), and indium-tin composite oxide, but it is preferable to use tin-doped indium oxide (ITO) or fluorine-doped tin oxide (FTO).

[0066] <Electron transport layer> In the photoelectric conversion element of the present invention, the electron transport layer 2 shown in Figure 1 is a layer located between the conductive support 1 and the photoelectric conversion layer (perovskite layer) 3. It is preferable, but not limited to, that the electron transport layer 2 be formed on the conductive support 1. The electron transport layer is used to improve the efficiency of electron transfer from the photoelectric conversion layer to the electrode and to block the movement of holes.

[0067] In the present invention, specific examples of semiconductors that form 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 elemental semiconductors such as silicon and germanium. It is preferable to use one or more of these semiconductors. In the present invention, it is preferable to use one or more semiconductors selected from tin oxide, titanium oxide, and zinc oxide.

[0068] In the present invention, the paste containing the semiconductor fine particles may be a commercially available product, or a paste prepared by dispersing commercially available semiconductor fine powder in a solvent (a coating solution for electron transport layers) may be used. Specific examples of solvents used when preparing the paste include, but are not limited to, water; alcohol-based solvents such as methanol, ethanol, and isopropyl alcohol; 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. Furthermore, these solvents can be used individually or as a mixture of two or more solvents.

[0069] In the present invention, the method for dispersing semiconductor fine powder in a solvent may involve grinding the powder in a mortar and pestle, or using a disperser such as a ball mill, paint conditioner, vertical bead mill, horizontal bead mill, or attritor. When preparing the paste, it is preferable to add a surfactant or the like to prevent aggregation of semiconductor fine particles, and it is preferable to add a thickener such as polyethylene glycol to increase the viscosity.

[0070] In the present invention, the electron transport layer can be obtained using a known film-forming method depending on the material to be formed. Any coating method using a coating solution can be used to form the electron transport layer. Examples include, but are not limited to, a wet coating method such as spin coating, inkjet coating, doctor blade coating, drop casting, squeegee coating, screen printing, reverse roll coating, gravure coating, kiss coating, roll brushing, spray coating, air knife coating, wire barber coating, pipe doctor coating, impregnation coating, or curtain coating, which is applied to a conductive substrate and then the solvent and additives are removed by firing; or sputtering, vapor deposition, electrodeposition, photodeposition, microwave irradiation, etc. In the present invention, it is preferable to form the film by spin coating using a coating solution for the electron transport layer prepared by the above method, but is not limited to this. The conditions for spin coating can be set as appropriate. The atmosphere in which the film is formed is not particularly limited and may be in the atmosphere.

[0071] 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 usually preferably 5 nm to 100 nm, and more preferably 10 nm to 50 nm. In the present invention, when a porous (mesoporous) metal oxide is used in addition to the dense layer, the thickness of the electron transport layer is usually preferably 20 to 200 nm or less, and more preferably 50 to 150 nm.

[0072] <Photoelectric conversion layer> In the photoelectric conversion element of the present invention, it is preferable that a photoelectric conversion layer (perovskite layer) 3 is formed on the electron transport layer 2 shown in Figure 1.

[0073] In the present invention, when used as a perovskite-type photoelectric conversion element, the perovskite material which is the photoelectric conversion layer represents a series of materials having a structure represented by the general formula ABX3. Here, A, B, and X represent an organic cation or a monovalent metal cation, a metal cation, and a halide anion, respectively, and as an example, A=K+ , Rb + , Cs + , CH3NH3 + (hereinafter, MA: methylammonium), NH=CHNH2 + (hereinafter, FA: formamidinium), CH3CH2NH3 + (hereinafter, EA: ethylammonium); B = Pb, Sn; X = I - , Br - may be mentioned. Further, specifically, perovskite materials represented by any composition of MAPbI3, FAPbI3, EAPbI3, CsPbI3, MASnI3, FASnI3, EASnI3, MAPbBr3, FAPbBr3, EAPbBr3, MASnBr3, FASnBr3, EASnBr3, and (FAMA)Pb(IBr)3, K(FAMA)Pb(IBr)3, Rb(FAMA)Pb(IBr)3, Cs(FAMA)Pb(IBr)3 perovskite materials of mixed cations and mixed anions represented by any composition can be used, but are not limited thereto. It is preferable to use one or more of these perovskite materials. Further, it may contain a light absorber other than the perovskite material.

[0074] As a method for coating the photoelectric conversion layer (perovskite layer) of the photoelectric conversion element of the present invention, any coating method can be used, and the same method as the film formation method of the electron transport layer can be mentioned.

[0075] The perovskite precursor may use commercially available materials. In the present invention, it is preferable to use a precursor composed of lead halide, methylammonium halide, formamidine halide, and cesium halide in any composition, but is not limited thereto.

[0076] From the viewpoint of precursor solubility, the solvent for the perovskite precursor solution of the present invention can be N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), γ-butyrolactone, etc., but is not limited to these. Furthermore, one or more of these solvents may be used, and a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide is preferred.

[0077] In the present invention, the atmosphere during film formation of the photoelectric conversion layer (perovskite layer) is preferably a dry atmosphere, and more preferably a dry inert gas atmosphere such as a glove box, from the viewpoint of being able to reproducibly manufacture highly efficient perovskite solar cells by preventing the inclusion of moisture. Furthermore, it is preferable to dehydrate the solvent using molecular sieves or the like and use a solvent with a low moisture content.

[0078] In the present invention, the temperature at which the photoelectric conversion layer (perovskite layer) is heated using a hot plate or the like is preferably 50 to 200°C, and more preferably 70 to 150°C, from the viewpoint of generating perovskite material from the precursor. The heating time is preferably about 10 to 90 minutes, and more preferably about 10 to 60 minutes.

[0079] The thickness of the photoelectric conversion layer (perovskite layer) of the present invention is preferably 50 to 1000 nm, and more preferably 300 to 700 nm, from the viewpoint of further suppressing performance degradation due to defects and delamination, and in order to ensure that the photoelectric conversion layer has a sufficient light absorption rate while preventing the element resistance from becoming too high.

[0080] <Hole transport layer> In the photoelectric conversion element of the present invention, the hole transport layer 4 shown in Figure 1 is a layer that has the function of transporting holes and is located between the photoelectric conversion layer (perovskite layer) 3 and the counter electrode 5. The hole transport layer is used to improve the efficiency of hole movement from the photoelectric conversion layer to the electrode and to block electron movement. For example, a conductor, semiconductor, or organic hole transport material can be used for the hole transport layer, and additives may be included for the purpose of further improving the hole transport characteristics. It is desirable to reduce the amount of additives used in the hole transport layer, and the photoelectric conversion element of the present invention has high performance even without additives in the hole transport layer.

[0081] The hole transport layer of the present invention is a layer containing the compound represented by the general formula (1) as a hole transport material. The hole transport layer of the present invention may contain one or more compounds represented by the general formula (1) in combination, and may also be used in combination with other hole transport materials not belonging to the present invention. In the case of a multilayer structure using a layer in which the hole transport layer is inserted (hereinafter also referred to as an intermediate layer) for the purpose of preventing dopant diffusion between the photoelectric conversion layer and the hole transport layer, the compound represented by the general formula (1) may be contained in the intermediate layer, and hole transport materials not belonging to the present invention may also be used as the hole transport layer.

[0082] Specific examples of other hole transport materials not belonging to the present 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 may be mixed in the hole transport layer or laminated on top of the hole transport material. Examples of organic hole transport materials include polythiophene derivatives such as poly-3-hexylthiophene (P3HT) and polyethylenedioxythiophene (PEDOT); fluorene derivatives such as 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (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.

[0083] Any coating method can be used to coat the hole transport layer of the photoelectric conversion element of the present invention using a coating solution, and the same method as the method for forming the electron transport layer can be used.

[0084] In the present invention, the solvents used in the coating solution for the hole transport layer during film formation are aromatic organic solvents such as benzene, toluene, xylene, mesitylene, tetralin (1,2,3,4-tetrahydronaphthalene), monochlorobenzene (chlorobenzene), o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, and nitrobenzene; alkyl halogenated organic solvents such as dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, and dichloromethane; nitrile solvents such as benzonitrile and acetonitrile; and tetrahydrofuran and dioxa. Examples of suitable solvents include ether-based solvents such as diisopropyl ether, c-pentyl methyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol monomethyl ether; ester-based solvents such as ethyl acetate and propylene glycol monomethyl ether acetate; and alcohol-based solvents such as methanol, isopropanol, n-butanol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, cyclohexanol, and 2-n-butoxyethanol, but are not limited to these. Furthermore, one or more of the above solvents may be used, and the solvent to be used can be selected depending on the structure. In particular, the use of aromatic organic solvents and alkyl halogenated organic solvents is preferred.

[0085] In the present invention, the thickness of the hole transport layer is preferably 5 to 500 nm, and more preferably 10 nm to 250 nm, from the viewpoint of further improving the photoelectric conversion efficiency. Even when a multilayer structure of the hole transport layer is used, in which a hole transport layer is inserted between the photoelectric conversion layer 4 and the hole transport layer 5 for the purpose of preventing dopant diffusion, the total thickness is preferably the same.

[0086] In the present invention, a dry atmosphere is preferred during the deposition of the hole transport layer, from the viewpoint of being able to reproducibly manufacture highly efficient perovskite solar cells by preventing the inclusion of moisture. Furthermore, it is preferable to use a dehydrated solvent with a moisture content of 10 ppm or less.

[0087] <Additives> In the present invention, the hole transport layer may contain dopants (or oxidizing agents) or basic compounds (or basic additives) as additives. Including additives in the hole transport layer and improving the carrier concentration of the hole transport material in the hole transport layer (doping) leads to an improvement in the conversion efficiency of the photoelectric conversion element. In the present invention, when the hole transport layer contains dopants and basic additives as additives, it is preferable that the amount of additive is 3.5 equivalents or less per equivalent of hole transport material. On the other hand, when dopants and basic additives are used as additives, it is a concern that the manufacturing process of the photoelectric conversion element will become more complex and the cost will increase, and the durability will decrease and the lifespan of the element will be shortened. For this reason, it is desirable to reduce the amount used, but the photoelectric conversion element of the present invention has high performance even without additives.

[0088] In the present invention, when a dopant is included, specific examples of dopants include bis(trifluoromethylsulfonyl)imide lithium (LiTFSI), bis(trifluoromethanesulfonyl)imide silver, tris(2-(1H-pyrazole-1-yl)-4-tert-butylpyridine)cobalt(III)tri[bis(trifluoromethane)sulfonimide](FK209), NOSbF6, SbCl5, SbF5, etc. In the present invention, it is preferable to use bis(trifluoromethylsulfonyl)imide lithium (LiTFSI), but the invention is not limited thereto.

[0089] In the present invention, when using a dopant, it is preferable that the amount of dopant be 2.0 equivalents or less, and more preferably 0.5 equivalents or less, relative to 1 equivalent of the hole transport material contained in the hole transport layer.

[0090] Furthermore, the present invention may contain a basic compound (basic additive) as an additive to the hole transport layer. Specific examples of basic compounds included in the present invention include 4-tert-butylpyridine (tBP), 2-picoline, and 2,6-lutidine. Basic compounds are often used in combination with dopants. In the present invention, it is desirable to use a basic compound in combination with a dopant, and tert-butylpyridine is preferred.

[0091] In the present invention, when a basic compound is used, it is preferable that the amount is 5 equivalents or less, and more preferably 3 equivalents or less, relative to 1 equivalent of the hole transport material of the present invention.

[0092] <Opposite> In the present invention, the counter electrode 5 shown in Figure 1 is positioned opposite the conductive support 1 and formed on the hole transport layer 4, thereby enabling charge exchange with the hole transport layer. In the photoelectric conversion element of the present invention, it is preferable to have a metal electrode as a counter electrode on the hole transport layer 4, but an electron blocking layer made of an organic material or an inorganic compound semiconductor can also be added between the hole transport layer 4 and the counter electrode 5.

[0093] In the present invention, specific materials used for the counter electrode include metals such as platinum, titanium, stainless steel, aluminum, gold, silver, nickel, magnesium, chromium, cobalt, and copper, or alloys thereof. Among these, gold, silver, or silver alloys are preferred because they exhibit high electrical conductivity even in thin films. As for silver alloys, silver-gold alloys, silver-copper alloys, silver-palladium alloys, silver-copper-palladium alloys, and silver-platinum alloys are used to improve the stability of the thin film by making them less susceptible to sulfidation or chlorination.

[0094] In the present invention, the counter electrode is preferably made of a material that can be formed by methods such as vapor deposition.

[0095] When a metal electrode is used as the counter electrode, its film thickness is preferably 10 nm or more, and more preferably 50 nm or more, in order to obtain good conductivity.

[0096] In the photoelectric conversion element of the present invention, the conductive support acts as the cathode and the counter electrode acts as the anode. It is preferable to irradiate the conductive support with light, such as sunlight, from the conductive support side. Upon irradiation with sunlight or other light, the photoelectric conversion layer (perovskite layer) absorbs the light and enters an excited state, generating electrons and holes. These electrons move through the electron transport layer and the holes move through the hole transport layer to the electrodes, causing an electric current to flow and enabling the element to function as a photoelectric conversion element.

[0097] When evaluating the performance (characteristics) of the photoelectric conversion element of the present invention, the short-circuit current density, open-circuit voltage, fill factor, and photoelectric conversion efficiency are measured. Short-circuit current density is the current that flows between the two terminals when the output terminals are short-circuited. 2 The current per watt is expressed, and the open-circuit voltage is the voltage between the two terminals when the output terminals are open-circuited. The fill factor is the value obtained by dividing the maximum output (product of current and voltage) by the product of the short-circuit current density and the open-circuit voltage, and is mainly affected by the internal resistance. The photoelectric conversion efficiency is calculated by multiplying the maximum output (W) by 1 cm². 2 It can be calculated by dividing the value by the light intensity (W) per unit area, multiplying the result by 100, and expressing it as a percentage.

[0098] The photoelectric conversion element of the present invention can be applied to perovskite solar cells, various light sensors, and the like. The perovskite solar cell of the present invention is obtained by arranging the required number of photoelectric conversion elements, each containing a hole transport material containing the compound represented by the general formula (1) as a hole transport layer, to form a module, and providing predetermined electrical wiring.

[0099] Although preferred embodiments have been described above, the present invention is not limited thereto, and may be modified as appropriate without departing from the scope of the present invention. [Examples]

[0100] Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples. In addition, the identification of the compounds obtained in the synthesis examples was carried out by 1 1H-NMR (1H-NMR, nuclear magnetic resonance apparatus manufactured by JEOL Ltd., JNM-ECZ400S / L1 type).

[0101] [Synthesis Example 1] Synthesis of Compound (A-1) Into a reaction vessel, 3,6-dibromocarbazole (0.65 g, manufactured by TCI), [4-[bis(4-methoxyphenyl)amino]phenyl]boronic acid (1.68 g, manufactured by TCI), 2M aqueous potassium carbonate solution (10 mL), tetrakis(triphenylphosphine)palladium (0.06 g, manufactured by Kanto Chemical Co., Inc.), and THF (30 mL) were charged, and degassing was performed under reduced pressure. The mixture was heated under reflux for 6 hours. After completion of the reaction, the reaction solution was poured into a beaker containing water (150 mL). After adding toluene (30 mL) thereto, liquid separation was carried out. The organic layer was dried over magnesium sulfate and then concentrated. The crude product was purified by a silica gel column (toluene:ethyl acetate = 50:1 (volume ratio)) to obtain the compound represented by the following formula (2) as a white solid (yield: 0.85 g, yield: 55%).

[0102] 1 1H-NMR (400 MHz, THF-d8): δ (ppm) = 3.73 (12H), 6.81 (8H), 6.96 (4H), 7.01 (8H), 7.40 (2H), 7.51 (4H), 7.56 (2H), 8.30 (2H), 10.3 (1H).

[0103] [Chemical Formula]

[0104] 0.40 g of the compound of formula (2) above, 0.03 g of sodium hydride (manufactured by Kanto Chemical Co., Ltd.), and 15 mL of THF were added to a reaction vessel and stirred at room temperature for 3 hours. 0.08 mL of 2,4-butanesultone (manufactured by TCI) was added and the mixture was heated under reflux for 4 hours. The reaction mixture was concentrated, dissolved in toluene (60 mL), filtered, and the filtrate was concentrated. The crude product was purified using a silica gel column (ethyl acetate), and then recrystallized (acetone:methanol) to obtain the compound represented by the following formula (A-1) as a pale green solid (yield: 0.40 g, yield: 86%).

[0105] 1 H-NMR (400MHz, DMSO-d6): δ(ppm)=1.16(3H), 1.76(1H), 2.22(1H), 2.47(1H), 3. 73(12H), 4.57(2H), 6.88-6.95(12H), 7.04(8H), 7.63(4H), 7.70(4H), 8.48(2H)

[0106] [ka]

[0107] [Synthesis Example 2] Synthesis of Compound (A-2) 0.20 g of the compound of formula (2) above, 0.06 g of potassium tert-butoxide (manufactured by Kanto Chemical Co., Ltd.), and 7 mL of THF were added to a reaction vessel and stirred at room temperature for 3 hours. 0.04 mL of 2,4-butanesultone (manufactured by TCI) was added and the mixture was heated under reflux for 4 hours. The reaction mixture was concentrated, dissolved in toluene (30 mL), filtered, and the filtrate was concentrated. The crude product was recrystallized (acetone:methanol) to obtain the compound represented by formula (A-2) below as a milky white solid (yield: 0.15 g, yield: 60%).

[0108] 1 H-NMR (400MHz, DMSO-d6): δ(ppm)=1.16(3H), 1.76(1H), 2.22(1H), 2.40(1H), 3. 75(12H), 4.58(2H), 6.89-6.95(12H), 7.05(8H), 7.63(4H), 7.70(4H), 8.47(2H)

[0109] [ka]

[0110] [Synthesis Example 3] Synthesis of Compound (A-3) 0.20 g of the compound of formula (2) above, cesium carbonate (0.19 g, manufactured by Kanto Chemical Co., Ltd.), and THF (7 mL) were added to a reaction vessel and stirred at room temperature for 3 hours. 2,4-butanesultone (0.04 mL, manufactured by TCI) was added and the mixture was heated under reflux for 4 hours. The reaction mixture was filtered, washed with THF (20 mL), and concentrated. This was dissolved in methanol, filtered, and the filtrate was concentrated. The crude product was recrystallized (acetone:ethanol) to obtain the compound represented by the following formula (A-3) as a pale green solid (yield: 0.09 g, yield: 33%).

[0111] 1 H-NMR (400MHz, DMSO-d6): δ(ppm)=1.15(3H), 1.32(1H), 1.87(1H), 2.32(1H), 3. 77(12H), 4.57(2H), 6.88-6.95(12H), 7.03(8H), 7.63(4H), 7.69(4H), 8.46(2H)

[0112] [ka]

[0113] [Synthesis Example 4] Synthesis of Compound (A-4) 0.20 g of the compound of formula (2) above, 0.13 g of rubidium carbonate (manufactured by Kanto Chemical Co., Ltd.), and 7 mL of THF were added to a reaction vessel and stirred at room temperature for 3 hours. 0.04 mL of 2,4-butanesultone (manufactured by TCI) was added and the mixture was heated under reflux for 4 hours. The reaction mixture was filtered, washed with 20 mL of THF, and concentrated. This was dissolved in methanol, filtered, and the filtrate was concentrated. The crude product was recrystallized (acetone:ethanol) to obtain the compound represented by formula (A-4) below as a pale green solid (yield: 0.07 g, yield: 27%).

[0114] 1 H-NMR (400MHz, DMSO-d6): δ(ppm)=1.16(3H), 1.44(1H), 2.15(1H), 2.33(1H), 3. 73(12H), 4.57(2H), 6.88-6.95(12H), 7.04(8H), 7.63(4H), 7.70(4H), 8.47(2H)

[0115] [ka]

[0116] [Synthesis Example 5] Synthesis of Compound (A-5) The compound represented by formula (A-5) below was obtained as a pale green solid (yield: 0.25 g, yield: 81%) by the same method as in Synthesis Example 1, except that the compound represented by formula (2) above was replaced with the compound represented by formula (3) below.

[0117] 1 H-NMR (400MHz, DMSO-d6): δ(ppm)=1.18(3H), 1.79(1H), 2.23(1H), 2.46(1H) , 3.65(12H), 4.57(2H), 6.81(8H), 6.85(8H), 7.10(2H), 7.50(2H), 7.79(2H)

[0118] [ka]

[0119] [Synthesis Example 6] Synthesis of Compound (A-6) The compound represented by the following formula (A-6) was obtained as a milky white solid (yield: 0.13 g, yield: 63%) by the same method as in Synthesis Example 2, except that the compound represented by formula (2) above was replaced with the compound represented by formula (3) above.

[0120] 1H-NMR (400MHz, DMSO-d6): δ(ppm)=1.18(3H), 1.79(1H), 2.23(1H), 2.40(1H) , 3.63(12H), 4.57(2H), 6.81(8H), 6.85(8H), 7.10(2H), 7.50(2H), 7.78(2H)

[0121] [ka]

[0122] [Synthesis Example 7] Synthesis of Compound (A-7) The compound represented by the following formula (A-7) was obtained as a pale green solid (yield: 0.09 g, yield: 39%) by the same method as in Synthesis Example 3, except that the compound represented by formula (2) above was replaced with the compound represented by formula (3) above.

[0123] 1 H-NMR (400MHz, DMSO-d6): δ(ppm)=1.17(3H), 1.35(1H), 1.88(1H), 2.32(1H) , 3.65(12H), 4.57(2H), 6.81(8H), 6.85(8H), 7.09(2H), 7.49(2H), 7.77(2H)

[0124] [ka]

[0125] [Synthesis Example 8] Synthesis of Compound (A-8) The compound represented by the following formula (A-8) was obtained as a pale green solid (yield: 0.06 g, yield: 28%) by the same method as in Synthesis Example 4, except that the compound represented by formula (2) above was replaced with the compound represented by formula (3) above.

[0126] 1H-NMR (400MHz, DMSO-d6): δ(ppm)=1.18(3H), 1.48(1H), 2.18(1H), 2.33(1H) , 3.65(12H), 4.57(2H), 6.81(8H), 6.85(8H), 7.10(2H), 7.50(2H), 7.79(2H)

[0127] [ka]

[0128] [Synthesis Example 9] Synthesis of compound (A-23) The compound represented by the following formula (A-23) was obtained as a pale green solid (yield: 0.38 g, yield: 81%) by the same method as in Synthesis Example 1, except that the compound represented by formula (2) above was replaced with the compound represented by formula (4) below.

[0129] 1 H-NMR (400MHz, DMSO-d6): δ(ppm)=1.16(3H), 1.76(1H), 2.22(1H), 2.47(1H), 3.73(1 2H), 4.57(2H), 6.88-6.95(12H), 7.00(8H), 7.49(2H), 7.60(4H), 7.85(2H), 7.96(2H)

[0130] [ka]

[0131] [Synthesis Example 10] Synthesis of compound (A-24) The compound represented by the following formula (A-24) was obtained as a milky white solid (yield: 0.16 g, yield: 65%) by the same method as in Synthesis Example 2, except that the compound represented by formula (2) above was replaced with the compound represented by formula (4) above.

[0132] 1H-NMR (400MHz, DMSO-d6): δ(ppm)=1.16(3H), 1.76(1H), 2.22(1H), 2.40(1H), 3.75(1 2H), 4.58(2H), 6.88-6.95(12H), 7.00(8H), 7.49(2H), 7.60(4H), 7.85(2H), 7.96(2H)

[0133] [ka]

[0134] [Synthesis Example 11] Synthesis of compound (A-25) The compound represented by the following formula (A-25) was obtained as a pale green solid (yield: 0.11 g, yield: 40%) by the same method as in Synthesis Example 3, except that the compound represented by formula (2) above was replaced with the compound represented by formula (4) above.

[0135] 1 H-NMR (400MHz, DMSO-d6): δ(ppm)=1.16(3H), 1.76(1H), 2.22(1H), 2.40(1H), 3.75(1 2H), 4.58(2H), 6.88-6.95(12H), 7.00(8H), 7.49(2H), 7.60(4H), 7.85(2H), 7.96(2H)

[0136] [ka]

[0137] [Synthesis Example 12] Synthesis of compound (A-26) The compound represented by the following formula (A-26) was obtained as a pale green solid (yield: 0.08 g, yield: 31%) by the same method as in Synthesis Example 4, except that the compound represented by formula (2) above was replaced with the compound represented by formula (4) above.

[0138] 1H-NMR (400MHz, DMSO-d6): δ(ppm)=1.16(3H), 1.76(1H), 2.22(1H), 2.40(1H), 3.75(1 2H), 4.58(2H), 6.88-6.95(12H), 7.00(8H), 7.49(2H), 7.60(4H), 7.85(2H), 7.96(2H)

[0139] [ka]

[0140] [Synthesis Example 13] Synthesis of compound (A-27) The compound represented by the following formula (A-27) was obtained as a pale green solid (yield: 0.28 g, yield: 72%) by the same method as in Synthesis Example 1, except that the compound represented by formula (2) above was replaced with the compound represented by formula (5) below.

[0141] 1 H-NMR (400MHz, DMSO-d6): δ(ppm)=1.18(3H), 1.79(1H), 2.23(1H), 2.46(1H) , 3.65(12H), 4.57(2H), 6.84(8H), 6.89(8H), 6.95(2H), 7.20(2H), 7.25(2H)

[0142] [ka]

[0143] [Synthesis Example 14] Synthesis of Compound (A-28) The compound represented by the following formula (A-28) was obtained as a milky white solid (yield: 0.12 g, yield: 58%) by the same method as in Synthesis Example 2, except that the compound represented by formula (2) above was replaced with the compound represented by formula (5) above.

[0144] 1H-NMR (400 MHz, DMSO-d6): δ (ppm) = 1.18 (3H), 1.79 (1H), 2.23 (1H), 2.40 (1H), 3.63 (12H), 4.57 (2H), 6.84 (8H), 6.89 (8H), 6.95 (2H), 7.20 (2H), 7.25 (2H)

[0145]

Chem.

[0146] [Synthesis Example 15] Synthesis of Compound (A-29) A compound represented by the following formula (A-29) was obtained as a light green solid (yield: 0.06 g, yield rate: 26%) in the same manner as in Synthesis Example 3, except that the compound represented by the above formula (2) was changed to the compound represented by the above formula (5).

[0147] 1 H-NMR (400 MHz, DMSO-d6): δ (ppm) = 1.17 (3H), 1.35 (1H), 1.88 (1H), 2.32 (1H), 3.65 (12H), 4.57 (2H), 6.84 (8H), 6.89 (8H), 6.95 (2H), 7.20 (2H), 7.25 (2H)

[0148]

Chem.

[0149] [Synthesis Example 16] Synthesis of Compound (A-30) A compound represented by the following formula (A-30) was obtained as a light green solid (yield: 0.07 g, yield rate: 32%) in the same manner as in Synthesis Example 4, except that the compound represented by the above formula (2) was changed to the compound represented by the above formula (5).

[0150] 1H-NMR (400MHz, DMSO-d6): δ(ppm)=1.18(3H), 1.48(1H), 2.18(1H), 2.33(1H ), 3.65(12H), 4.57(2H) 6.84(8H), 6.89(8H), 6.95(2H), 7.20(2H), 7.25(2H)

[0151] [ka]

[0152] [Synthesis Example 17] Synthesis of compound (A-73) The compound represented by the following formula (A-73) was obtained as a pale green solid (yield: 0.29 g, yield: 79%) by the same method as in Synthesis Example 1, except that the compound represented by formula (2) above was replaced with the compound represented by formula (6) below.

[0153] 1 H-NMR (400MHz, DMSO-d6): δ(ppm)=1.18(3H), 1.84(1H), 2.28(1H), 2.53(1H), 3.70(24H), 4.67(2H) )6.83(16H), 6.89(16H), 7.12(4H), 7.40(4H), 7.73(6H), 7.75(2H), 7.94(2H), 8.10(6H), 8.79(2H)

[0154] [ka]

[0155] [Synthesis Example 18] Synthesis of Compound (A-74) The compound represented by the following formula (A-74) was obtained as a pale green solid (yield: 0.22 g, yield: 56%) by the same method as in Synthesis Example 3, except that the compound represented by formula (2) above was replaced with the compound represented by formula (6) above.

[0156] 1H-NMR (400 MHz, DMSO-d6): δ (ppm) = 1.18 (3H), 1.84 (1H), 2.28 (1H), 2.53 (1H), 3.70 (24H), 4.67 (2H), 6.83 (16H), 6.90 (16H), 7.11 (4H), 7.40 (4H), 7.73 (6H), 7.75 (2H), 7.94 (2H), 8.10 (6H), 8.79 (2H)

[0157]

Chem.

[0158] [Synthesis Example 19] Synthesis of Compound (A-75) A compound represented by the following formula (A-75) was obtained as a light green solid (yield: 0.21 g, yield rate: 48%) by the same method as in Synthesis Example 1 except that the compound represented by the above formula (2) was changed to the compound represented by the following formula (7).

[0159] 1 H-NMR (400 MHz, DMSO-d6): δ (ppm) = 1.18 (3H), 1.89 (1H), 2.31 (1H), 2.56 (1H), 3.70 (24H), 4.81 (2H), 6.84 (16H), 6.90 (16H), 7.12 (4H), 7.42 (4H), 7.62 (2H), 7.74 (8H), 8.17 (6H), 8.31 (2H)

[0160]

Chem.

[0161] [Synthesis Example 20] Synthesis of Compound (A-76) A compound represented by the following formula (A-76) was obtained as a light green solid (yield: 0.22 g, yield rate: 60%) by the same method as in Synthesis Example 3 except that the compound represented by the above formula (2) was changed to the compound represented by the above formula (7).

[0162] 1H-NMR (400MHz, DMSO-d6): δ(ppm)=1.19(3H), 1.89(1H), 2.30(1H), 2.53(1H), 3.73(24H), 4.8 1(2H)6.82(16H), 6.90(16H), 7.11(4H), 7.41(4H), 7.63(2H), 7.73(8H), 8.15(6H), 8.28(2H)

[0163] [ka]

[0164] [Comparative Compound 1] Synthesis of Compound (B-1) The compound represented by formula (A-1) above (0.10 g) was subjected to an ion exchange reaction using an ion exchange resin (manufactured by Sigma-Aldrich) to obtain the compound represented by formula (B-1) below as a green solid (yield: 0.07 g, yield: 71%).

[0165] 1 H-NMR (400MHz, DMSO-d6): δ(ppm)=1.16(3H), 1.76(1H), 2.22(1H), 3.73(1 2H), 4.57(2H), 6.88-6.95(12H), 7.04(8H), 7.63(4H), 7.70(4H), 8.48(2H)

[0166] [ka]

[0167] [Example 1] Fabrication of a photoelectric conversion element and evaluation of its photoelectric conversion characteristics A glass substrate (conductive support 1, manufactured by Solaronix) coated with an etched, fluorine-doped tin oxide (FTO) thin film was ultrasonically cleaned with isopropyl alcohol and then treated with UV ozone. A tin(IV) oxide dispersion, 15% in H2O colloidal dispersion (manufactured by Alfa Aesar), and purified water in a volume ratio of 1:3 was applied to this substrate by spin coating. Subsequently, a tin oxide layer (electron transport layer 2) with a thickness of approximately 40 nm was formed by heating at 150°C for 30 minutes using a hot plate.

[0168] Under a nitrogen atmosphere in a glove box, formamidine hydroiodide (1M, Tokyo Chemical Industry Co., Ltd.), lead(II) iodide (1.1M, Tokyo Chemical Industry Co., Ltd.), methylamine hydrobromide (0.2M, Tokyo Chemical Industry Co., Ltd.), and lead(II) bromide (0.2M, Tokyo Chemical Industry Co., Ltd.) were dissolved in a mixed solvent of dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1. A dimethyl sulfoxide solution of cesium iodide (1.5M, Tokyo Chemical Industry Co., Ltd.) was then added to prepare a perovskite precursor solution, with the amount of cesium being 5% of the composition ratio. In a glove box under a nitrogen atmosphere, a perovskite precursor solution was dropped onto a tin oxide layer and spin-coated. During the spin-coating process, 0.3 mL of chlorobenzene was added to form a perovskite precursor film. Subsequently, a Cs(MAFA)Pb(IBr) 3-layer (photoelectric conversion layer 3) with a thickness of approximately 500 nm was formed by heating at 100°C for 1 hour using a hot plate.

[0169] In a glove box under a nitrogen atmosphere, compound (A-1), a hole transport material obtained in Synthesis Example 1, was dissolved in chlorobenzene at a concentration of 50 mM to prepare a coating solution for the hole transport layer. In a glove box under a nitrogen atmosphere, the coating solution for the hole transport layer was spin-coated onto three layers of Cs(MAFA)Pb(IBr) (photoelectric conversion layer 3) to form a hole transport layer 4 with a thickness of approximately 200 nm.

[0170] Gold is deposited onto the hole transport layer 4 by vacuum deposition at a vacuum of 1 × 10⁻⁶ -4 A photoelectric conversion element was fabricated by depositing a 80-100 nm thin film at approximately Pa, thereby setting up a gold electrode (counter electrode 5).

[0171] Simulated sunlight (AM1.5, 100mW / cm²) generated by a white light irradiation device (OTENTO-SUN SH model, manufactured by Spectrometer Co., Ltd.) 2 The photoelectric conversion efficiency was obtained by irradiating the photoelectric conversion element with a light source from the conductive support 1 side and measuring the current-voltage characteristics using a source meter (KEITHLEY, Model 2400 Series SourceMeter). The obtained current-voltage characteristics and photoelectric conversion efficiency are shown in Table 1.

[0172] [Comparative Example 1] A chlorobenzene solution containing 25 mM bis(trifluoromethanesulfonyl)imide lithium (LiTFSI, 0.5 equivalents), an additive dopant, and 150 mM 4-tert-butylpyridine, an additive basic compound, was prepared as a doping solution. A 50 mM chlorobenzene solution was prepared using the prepared doping solution and Spiro-OMeTAD (Sigma-Aldrich), a standard hole transport material represented by the following formula (B-2), and this was prepared as a coating solution for the hole transport layer. A photoelectric conversion element was fabricated in the same manner as in Example 1, except for the use of this coating solution for the hole transport layer, and the photoelectric conversion efficiency was obtained by measuring the current-voltage characteristics. The obtained current-voltage characteristics and photoelectric conversion efficiency are shown in Table 1.

[0173] [ka]

[0174] [Comparative Example 2] A photoelectric conversion element was fabricated in the same manner as in Example 1, except that a compound having a sulfonic acid group that does not form a salt, represented by the above formula (B-1), was used as the hole transport material. The photoelectric conversion efficiency was obtained by measuring the current-voltage characteristics. The obtained current-voltage characteristics and photoelectric conversion efficiency are shown in Table 1.

[0175] [Table 1]

[0176] The results in Table 1 show that by using a hole transport layer containing the compound of the present invention, a photoelectric conversion element with higher performance can be fabricated without using dopants and basic additives, compared to when using compound (B-1) containing dopants and basic additives. This indicates that photoelectric conversion elements containing the compound of the present invention can be manufactured using a simple process that does not require additive addition, and can be manufactured without the need for additive addition. Furthermore, it was found that by using a hole transport layer containing the compound of the present invention, a photoelectric conversion element with higher performance can be fabricated compared to when using compound (B-2), a hole transport material that does not form salts and has sulfonic acid groups. This indicates that hole transport materials that form salts have superior properties as photoelectric conversion elements compared to hole transport materials that do not form salts.

[0177] [Example 2] Fabrication of a photoelectric conversion element and evaluation of its current-voltage characteristics A glass coated with a flat ITO film (conductive support 1, manufactured by Geomatec) was ultrasonically cleaned with isopropyl alcohol and then treated with UV ozone. A tin(IV) oxide dispersion (coating solution for electron transport layer) consisting of 15% in H2O colloidal dispersion (manufactured by Alfa Aesar) and purified water in a volume ratio of 1:9 was applied to this ITO film by spin coating. Subsequently, a tin oxide layer (electron transport layer 2) with a thickness of approximately 20 nm was formed by heating on a hot plate at 150°C for 30 minutes.

[0178] Under a nitrogen atmosphere in a glove box, formamidine hydroiodide (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 in a volume ratio of 4:1. A dimethyl sulfoxide solution of cesium iodide (1.5M, manufactured by Tokyo Chemical Industry Co., Ltd.) was then added to prepare a perovskite precursor solution, with the amount of cesium added reaching 5% of the composition ratio. In a glove box under a nitrogen atmosphere, the prepared perovskite precursor solution was dropped onto a tin oxide layer and spin-coated. During the spin-coating process, 0.3 mL of chlorobenzene was added to form a perovskite precursor film. Subsequently, a Cs(MAFA)Pb(IBr) 3-layer (photoelectric conversion layer 3) with a thickness of approximately 500 nm was formed by heating at 100°C for 1 hour using a hot plate.

[0179] Under a nitrogen atmosphere in a glove box, compound (A-5), which is a hole transport material obtained in Synthesis Example 5, was dissolved in chlorobenzene at 50 mM to prepare a coating solution for the hole transport layer. In a glove box under a nitrogen atmosphere, a hole transport layer coating solution was spin-coated onto three layers of Cs(MAFA)Pb(IBr) (photoelectric conversion layer 3) to form a hole transport layer 4 with a thickness of approximately 200 nm.

[0180] On the hole transport layer, a vacuum deposition method is used to create a vacuum of 1 × 10⁻⁶. -4 A gold electrode (counter electrode 5) was formed by depositing a gold film of approximately 80 nm in thickness at a temperature of around Pa, and a photoelectric conversion element was fabricated.

[0181] Simulated sunlight (AM1.5, 100mW / cm²) generated by a white light irradiation device (OTENTO-SUN SH model, manufactured by Spectrometer Co., Ltd.) 2 The initial photoelectric conversion efficiency was obtained by irradiating the photoelectric conversion element with a light source from the conductive support side and measuring the current-voltage characteristics using a source meter (KEITHLEY Model 2400 Series SourceMeter).

[0182] After measuring the current-voltage characteristics, the photoelectric conversion element was stored in a desiccator containing silica gel for 28 days, and the current-voltage characteristics were measured again under simulated sunlight irradiation to obtain the photoelectric conversion efficiency after 28 days. The obtained photoelectric conversion efficiencies over time (after 28 days) are shown in Table 2.

[0183] Table 2 shows the rate of change (%) calculated using the following formula (a-1) with respect to the initial photoelectric conversion efficiency obtained and the photoelectric conversion efficiency after 28 days.

[0184]

number

[0185] [Example 3] A photoelectric conversion element was fabricated in the same manner as in Example 2, except that compound (A-7) was dissolved in chlorobenzene to a concentration of 50 mM instead of compound (A-5). The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 2. The obtained photoelectric conversion efficiency over time (after 28 days) is shown in Table 2. Furthermore, the rate of change (%) calculated using the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days from the above formula (a-1) is also shown in Table 2.

[0186] [Example 4] A photoelectric conversion element was fabricated in the same manner as in Example 2, except that compound (A-73) was dissolved in chlorobenzene to a concentration of 50 mM instead of compound (A-5). The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 2. The obtained photoelectric conversion efficiency over time (after 28 days) is shown in Table 2. The rate of change (%) calculated using the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days from the above formula (a-1) is also shown in Table 2.

[0187] [Example 5] A photoelectric conversion element was fabricated in the same manner as in Example 2, except that compound (A-74) was dissolved in chlorobenzene to a concentration of 50 mM instead of compound (A-5). The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 2. The obtained photoelectric conversion efficiency over time (after 28 days) is shown in Table 2. Furthermore, the rate of change (%) calculated using the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days from the above formula (a-1) is also shown in Table 2.

[0188] [Example 6] A photoelectric conversion element was fabricated in the same manner as in Example 2, except that compound (A-27) was dissolved in chlorobenzene at 120°C to a concentration of 30 mM instead of compound (A-5). The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 2. The obtained photoelectric conversion efficiency over time (after 28 days) is shown in Table 2. Furthermore, the rate of change (%) calculated using the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days from the above formula (a-1) is also shown in Table 2.

[0189] [Example 7] A photoelectric conversion element was fabricated in the same manner as in Example 2, except that compound (A-29) was dissolved in chlorobenzene at 120°C to a concentration of 30 mM instead of compound (A-5). The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 2. The obtained photoelectric conversion efficiency over time (after 28 days) is shown in Table 2. Furthermore, the rate of change (%) calculated using the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days from the above formula (a-1) is also shown in Table 2.

[0190] [Comparative Example 3] Under a nitrogen atmosphere in a glove box, 4-tert-butylpyridine and bis(trifluoromethanesulfonyl)imide lithium were dissolved in chlorobenzene as dopants. Spiro-OMeTAD (Sigma-Aldrich), a standard hole transport material represented by formula (B-2), was dissolved in this chlorobenzene solution at 50 mM. A solution was prepared so that 3 equivalents of 4-tert-butylpyridine and 0.5 equivalents of bis(trifluoromethanesulfonyl)imide lithium were added relative to (B-2), and this was used as the coating solution for the hole transport layer. A photoelectric conversion element was fabricated in the same manner as in Example 2, and the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 2. The obtained photoelectric conversion efficiencies over time (after 28 days) are shown in Tables 2 and 3. Furthermore, the percentage change (%) calculated using formula (a-1) with the initial and 28-day photoelectric conversion efficiencies is shown in Tables 2 and 3.

[0191] [Table 2]

[0192] The results in Table 2 show that photoelectric conversion elements using compounds (A-5), (A-7), (A-27), (A-29), (A-73), and (A-74) of the present invention as hole transport materials exhibit sufficient photoelectric conversion efficiency even when the hole transport layer does not contain a dopant, and also show less degradation in element characteristics, compared to photoelectric conversion elements using compound (B-2), which is a standard hole transport material.

[0193] [Example 8] Under a nitrogen atmosphere in a glove box, 4-tert-butylpyridine and bis(trifluoromethanesulfonyl)imide lithium were dissolved in chlorobenzene as dopants. Compound (A-5), a hole transport material obtained in Synthesis Example 5, was dissolved in this chlorobenzene solution at 50 mM. The solution was prepared so that 3 equivalents of 4-tert-butylpyridine and 0.5 equivalents of bis(trifluoromethanesulfonyl)imide lithium were added to (A-5), and this was used as the coating solution for the hole transport layer. A photoelectric conversion element was fabricated in the same manner as in Example 2, and the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 2. The obtained photoelectric conversion efficiency over time (after 28 days) is shown in Table 3. The rate of change (%) calculated using the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days from the above formula (a-1) is also shown in Table 3.

[0194] [Example 9] A photoelectric conversion element was fabricated in the same manner as in Example 8, except that compound (A-73) was dissolved in a chlorobenzene solution of the above dopant to a concentration of 50 mM and used instead of compound (A-5). The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 8. The obtained photoelectric conversion efficiency over time (after 28 days) is shown in Table 3. In addition, the rate of change (%) calculated using the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days from the above formula (a-1) is also shown in Table 3.

[0195] [Example 10] A photoelectric conversion element was fabricated in the same manner as in Example 8, except that compound (A-74) was dissolved in a chlorobenzene solution of the above dopant to a concentration of 50 mM and used instead of compound (A-5). The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 8. The obtained photoelectric conversion efficiency over time (after 28 days) is shown in Table 3. In addition, the rate of change (%) calculated using the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days from the above formula (a-1) is also shown in Table 3.

[0196] [Example 11] A photoelectric conversion element was fabricated in the same manner as in Example 8, except that compound (A-27) was dissolved in a chlorobenzene solution of the above dopant at 60°C to a concentration of 50 mM and used instead of compound (A-5). The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 8. The obtained photoelectric conversion efficiency over time (after 28 days) is shown in Table 3. In addition, the rate of change (%) calculated using the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days from the above formula (a-1) is also shown in Table 3.

[0197] [Example 12] A photoelectric conversion element was fabricated in the same manner as in Example 8, except that compound (A-29) was dissolved in a chlorobenzene solution of the above dopant to a concentration of 50 mM and used instead of compound (A-5). The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 8. The obtained photoelectric conversion efficiency over time (after 28 days) is shown in Table 3. In addition, the rate of change (%) calculated using the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days from the above formula (a-1) is also shown in Table 3.

[0198] [Example 13] A photoelectric conversion element was fabricated in the same manner as in Example 8, except that compound (A-75) was dissolved in a chlorobenzene solution of the above dopant to a concentration of 50 mM and used instead of compound (A-5). The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 8. The obtained photoelectric conversion efficiency over time (after 28 days) is shown in Table 3. In addition, the rate of change (%) calculated using the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days from the above formula (a-1) is also shown in Table 3.

[0199] [Example 14] A photoelectric conversion element was fabricated in the same manner as in Example 8, except that compound (A-76) was dissolved in a chlorobenzene solution of the above dopant to a concentration of 50 mM and used instead of compound (A-5). The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 8. The obtained photoelectric conversion efficiency over time (after 28 days) is shown in Table 3. In addition, the rate of change (%) calculated using the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days from the above formula (a-1) is also shown in Table 3.

[0200] [Table 3]

[0201] The results in Table 3 show that photoelectric conversion elements using compounds (A-5), (A-27), (A-29), (A-73), (A-74), (A-75), and (A-76) of the present invention as hole transport materials exhibit sufficient photoelectric conversion efficiency compared to photoelectric conversion elements using compound (B-2), a standard hole transport material, and that the presence of a dopant in the hole transport layer does not cause a degradation in performance.

[0202] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications are possible without departing from the spirit and scope of the invention. This application is based on a Japanese patent application (Patent Application No. 2021-057864) filed on March 30, 2021, which is incorporated by reference in its entirety. All references cited herein are incorporated as a whole. [Industrial applicability]

[0203] The compound having a sulfonic acid base according to the present invention is useful as a photoelectric conversion element with good photoelectric conversion efficiency when used as a hole transport layer, and can provide clean energy as a solar cell that can efficiently convert solar energy into electrical energy, and can also be applied to other applications such as organic EL and image sensors. [Explanation of Symbols]

[0204] 1. Conductive support 2 Electron transport layer 3. Photoelectric conversion layer 4. Hole transport layer 5 Opposites

Claims

1. A compound represented by the following general formula (1). 【Chemistry 1】 [In the formula, R １ teeth, A linear or branched alkylene group having 1 to 18 carbon atoms, which may have substituents. X represents an alkali metal ion. R ２ ~R ９ Each of them operates independently. hydrogen atom, Linear or branched alkyl groups having 1 to 18 carbon atoms, which may have substituents. A linear or branched alkenyl group having 2 to 20 carbon atoms, which may have substituents. A linear or branched alkynyl group having 2 to 20 carbon atoms, which may have substituents. A cycloalkyl group having 3 to 12 carbon atoms, which may have substituents. A linear or branched alkoxy group having 1 to 20 carbon atoms, which may have substituents. A cycloalkoxy group having 3 to 10 carbon atoms, which may have substituents. A linear or branched alkoxycarbonyl group having 1 to 18 carbon atoms, which may have substituents. A thio group having 1 to 18 carbon atoms, which may have substituents. A C1 to C20 amino group which may have substituents, Aromatic hydrocarbon groups having 6 to 36 carbon atoms, which may have substituents. Alternatively, it represents a heterocyclic group having 5 to 36 ring-forming atoms, which may have substituents. Also, R ２ ~R ９ Of these, at least one is a diphenylamino group which may have substituents, or an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have substituents or a diphenylamino group or a carbazole group.

2. The compound according to claim 1, wherein in the general formula (1), the alkali metal ion is at least one selected from the group consisting of sodium ions, potassium ions, rubidium ions, and cesium ions.

3. The compound according to claim 1, wherein in the general formula (1), the alkali metal ion is a sodium ion or a cesium ion.

4. A hole transport material comprising the compound described in any one of claims 1 to 3.

5. A hole transport material composition for a photoelectric conversion element, comprising the hole transport material described in claim 4.

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

Images