Compound, Composition, and Photoelectric Conversion Device

Abstract

To provide a compound which can dope a hole transport compound at a low temperature and with high efficiency.SOLUTION: Provided is a compound represented by the following formula (1). (In the formula (1), R1, R2, and R3 each independently represent a hydrogen atom, a halogen atom, or a monovalent organic group, R4's each independently represent a halogen atom or a monovalent organic group except a carboxylic group, n is an integer of 0 to 5, and Ar represents an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group.)SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to compounds, compositions, and photoelectric conversion devices.

Background Art

[0002] Conventionally, in the technical field of optoelectronic conversion devices such as organic electroluminescence devices, organic solar cells, organic transistors, and electrophotographic photoreceptors, the development of hole transport materials used in these devices has been actively carried out. Although the development of the compounds themselves used as hole transport materials has been widely pursued, in recent years, development aimed at further enhancing the functionality of devices by doping specific compounds has been actively carried out.

[0003] Patent Document 1 discloses a technique related to a hole transport material that uses polyacetylene as a hole transport compound and an organic fluorescent agent as a dopant for the hole transport compound, which has high solubility in a solvent, can be easily applied, and is thus easily made into a thin film. Patent Document 2 discloses a technique related to a hole transport material suitable for providing a thin film solar cell with a high open-circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency by using polythiophene as a hole transport compound and a polymer anion having a specific structure as a dopant for the hole transport compound. Patent Document 3 discloses a technique related to an ink composition for an organic electronic device that enables control of the resistivity and ensures high transparency and low absorbance by using a polymer such as polythiophene as a hole transport compound and a polymer acid as a dopant for the hole transport compound.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

[0005] As shown in the above Patent Documents 1 to 3, the development of technologies related to dopants for hole transport compounds that can be used in photoelectric conversion devices with various excellent characteristics has been widely carried out. However, almost no development has been carried out from the perspective of highly efficient doping at low temperatures. Generally, when improving the efficiency of doping of hole transport compounds, doping is usually carried out at a high temperature. However, when the doping temperature is high, not only does the manufacturing cost increase, but various problems are likely to occur, such as evaporation and decomposition of raw materials, deterioration of the homogeneity of the manufactured product, and increase in defects. In addition, in order to suppress these adverse effects, a complicated manufacturing process is required, which may further increase the manufacturing cost. Furthermore, in various flexible substrates used in devices aiming at weight reduction and designability, excessive heating cannot be performed depending on the heat resistance of the substrate, so the problem may also occur that the characteristics of the hole transport compound cannot be fully exhibited. Therefore, the development of a technology that enables highly efficient doping and can lower the doping temperature of hole transport compounds is important, and there is room for improvement over the prior art.

[0006] Therefore, an object of the present invention is to provide a compound capable of doping a hole transport compound at low temperature and with high efficiency. MEANS FOR SOLVING THE PROBLEMS

[0007] As a result of intensive studies by the present inventors, it has been found that by using a compound having a specific structure, doping of a hole transport compound is possible at low temperature and with high efficiency, and the present invention has been achieved.

[0008] That is, the gist of the present invention is as follows. [1] A compound represented by the following formula (1). [Chemical formula] (In formula (1), R 1 , R 2 , and R 3 each independently represent a hydrogen atom, a halogen atom, or a monovalent organic group, R 4 each independently represent a halogen atom or a monovalent organic group excluding a carboxyl group, n is an integer from 0 to 5, and Ar represents a monovalent aromatic hydrocarbon ring group or an aromatic heterocyclic group which may have a substituent.) [2] The compound according to [1], wherein Ar is an aromatic hydrocarbon ring group or an aromatic heterocyclic group substituted with a fluoro group or a fluoroalkyl group. [3] The compound according to [1] or [2], wherein R 1 is an alkyl group, R 2 and R 3 are hydrogen, and n is 0. [4] A composition comprising the compound according to any one of [1] to [3] and a hole-transporting organic compound. [5] The composition according to [4], wherein the HOMO of the hole-transporting organic compound is -5.7 eV or more and -5.0 eV or less. [6] A film produced using the composition according to [4] or [5]. [7] A photoelectric conversion device comprising at least a photoelectric conversion layer and a hole-transporting layer, wherein the hole-transporting layer is the film according to [6]. [8] A photoelectric conversion device comprising the photoelectric conversion device according to [7]. [Advantages of the Invention]

[0009] According to the present invention, a compound capable of doping a hole-transporting compound at low temperature and with high efficiency can be provided. Furthermore, by using a photoelectric conversion device having a coating film of a composition containing the compound and a hole-transporting organic compound, a photoelectric conversion device having a high photoelectric conversion rate can be provided. [Brief Description of the Drawings]

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0011] Hereinafter, the present invention will be described in detail. The following description is an example (representative example) of the present invention, and the present invention is not limited thereto. Further, the present invention can be arbitrarily modified and implemented without departing from the gist thereof. In this specification, the description represented by "~" represents a range including the numbers described before and after it. In addition, "independently" used when explaining two or more objects together means that these two or more objects may be the same or different.

[0012] <1. Compound> [Structure of Compound] A compound which is one embodiment of the present invention (simply also referred to as "compound") is a compound represented by the following formula (1).

Chemical formula

[0013] R in formula (1) 1 R 2 and R 3 each independently represents a hydrogen atom, a halogen atom, or a monovalent organic group. Examples of the monovalent organic group include an optionally substituted alkyl group having 1 to 20 carbon atoms, an optionally substituted alkenyl group having 1 to 20 carbon atoms, an optionally substituted alkynyl group having 1 to 20 carbon atoms, an optionally substituted alkoxy group having 1 to 20 carbon atoms, a cyano group, an amino group, a carboxyl group, an ester group, an alkylcarbonyl group, an acetyl group, a sulfonyl group, a silyl group, a boryl group, a nitrile group, a thio group, a seleno group, an optionally substituted aromatic hydrocarbon ring group, an optionally substituted aromatic heterocyclic group, and the like.

[0014] Examples of the optionally substituted alkyl group having 1 to 20 carbon atoms include linear or branched alkyl groups having no substituent such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, etc.; and cyclic alkyl groups such as cycloalkyl group, etc.

[0015] Examples of the optionally substituted alkenyl group having 1 to 20 carbon atoms include linear or branched alkenyl groups having no substituent such as vinyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, etc.; and cyclic alkenyl groups such as cycloalkenyl group, etc.

[0016] Examples of the optionally substituted alkynyl group having 1 to 20 carbon atoms include linear or branched alkynyl groups having no substituent such as ethynyl group, propynyl group, butynyl group, pentynyl group, hexynyl group, heptynyl group, octynyl group, nonynyl group, decynyl group, undecynyl group, dodecynyl group, tridecynyl group, tetradecynyl group, pentadecynyl group, hexadecynyl group, heptadecynyl group, octadecynyl group, nonadecynyl group, etc.; and cyclic alkynyl groups such as cycloalkynyl group, etc.

[0017] Examples of the optionally substituted alkoxy group having 1 to 20 carbon atoms include linear or branched alkoxy groups having no substituent such as methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, tert-butoxy group, n-pentyloxy group, isopentyloxy group, neopentyloxy group, n-hexyloxy group, n-heptyloxy group, n-octyloxy group, n-nonyloxy group, n-decyloxy group, etc.

[0018] Examples of the aromatic hydrocarbon group which may have a substituent include monocyclic aromatic hydrocarbon groups such as phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 2,4-xylyl group, p-cumenyl group, mesityl group; condensed ring aromatic hydrocarbon groups such as 1-naphthyl group, 2-naphthyl group, 1-anthryl group, 2-anthryl group, 5-anthryl group, 1-phenanthryl group, 9-phenanthryl group, 1-acephenanthrenyl group, 2-azulenyl group, 1-pyrenyl group, 2-triphenylenyl group, etc.

[0019] Examples of the aromatic heterocyclic group which may have a substituent include 2-furyl group, 3-furyl group, 2-thienyl group, 3-thienyl group, 1-pyrrolyl group, 2-pyrrolyl group, 3-pyrrolyl group, 2-pyridyl group, 3-pyridyl group, 4-pyridyl group, 2-pyrazyl group, 2-oxazolyl group, 3-isoxazolyl group, 2-thiazolyl group, 3-isothiazolyl group, 2-imidazolyl group, 3-pyrazolyl group, 2-quinolyl group, 3-quinolyl group, 4-quinolyl group, 5-quinolyl group, 6-quinolyl group, 7-quinolyl group, 8-quinolyl group, 1-isoquinolyl group, 2-quinoxalyl group, 2-benzofuryl group, 2-benzothienyl group, N-indolyl group, N-carbazolyl group, 9-acridinyl group, etc.

[0020] Examples of the substituent which may be had in the above monovalent organic group include halogen, cyano group, amino group, carboxyl group, ester group, alkylcarbonyl group, acetyl group, sulfonyl group, silyl group, boryl group, nitrile group, thio group, seleno group, etc.

[0021] R 1 、R 2 、and R 3 The combination of is not particularly limited, but from the viewpoint of being able to dope the hole transport compound at low temperature and with high efficiency, it is preferable that at least one of these is a monovalent organic group, and it is more preferable that at least R 1 is a monovalent organic group. As the monovalent organic group, from the viewpoint of being able to dope the hole transport compound at low temperature and with high efficiency, an alkyl group, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkenyl group having 1 to 20 carbon atoms which may have a substituent, an alkynyl group having 1 to 20 carbon atoms which may have a substituent, or an alkoxy group having 1 to 20 carbon atoms which may have a substituent, is more preferably an alkyl group having 1 to 20 carbon atoms which may have a substituent, is even more preferably an alkyl group having 1 to 10 carbon atoms which may have a substituent, is particularly preferably an alkyl group having 1 to 5 carbon atoms which may have a substituent, is even more particularly preferably a methyl group, an ethyl group, an n-propyl group, or an isopropyl group, and is most preferably a methyl group.

[0022] R 1 , R 2 , and R 3 Specific examples of the combination include the following: [R 1 , R 2 , R 3 ]:[Hydrogen, Hydrogen, Hydrogen], [Methyl, Hydrogen, Hydrogen], [Ethyl, Hydrogen, Hydrogen], [Propyl, Hydrogen, Hydrogen], [Isopropyl, Hydrogen, Hydrogen], [Methyl, Methyl, Hydrogen] Among these, the following combinations are preferred from the viewpoint of enabling doping with a hole transport compound at low temperature and with high efficiency. [R 1 , R 2 , R 3 ]:[Methyl, Hydrogen, Hydrogen], [Ethyl, Hydrogen, Hydrogen], [Propyl, Hydrogen, Hydrogen] Among these, the following combinations are more preferable from the viewpoint of being able to dope the hole transport compound at low temperature and with high efficiency. [R 1 , R 2 , R 3 ]:[Methyl group, hydrogen, hydrogen]

[0023] R 4 each independently represents a halogen atom or a monovalent organic group other than a carboxyl group. Examples of the monovalent organic group excluding the carboxyl group include an optionally substituted alkyl group having 1 to 20 carbon atoms, an optionally substituted alkenyl group having 1 to 20 carbon atoms, an optionally substituted alkynyl group having 1 to 20 carbon atoms, an optionally substituted alkoxy group having 1 to 20 carbon atoms, a cyano group, an amino group, an ester group, an alkylcarbonyl group, an acetyl group, a sulfonyl group, a silyl group, a boryl group, a nitrile group, a thio group, a seleno group, an optionally substituted aromatic hydrocarbon ring group, an optionally substituted aromatic heterocyclic group, and the like.

[0024] R 4 Specific examples of the optionally substituted alkyl group having 1 to 20 carbon atoms, the optionally substituted alkenyl group having 1 to 20 carbon atoms, the optionally substituted alkynyl group having 1 to 20 carbon atoms, and the optionally substituted alkoxy group having 1 to 20 carbon atoms in 1 ~R 3 are the same as the specific examples in In addition, examples of the above-mentioned optional substituents include a halogen, a cyano group, an amino group, an ester group, an alkylcarbonyl group, an acetyl group, a sulfonyl group, a silyl group, a boryl group, a nitrile group, a thio group, a seleno group, and the like.

[0025] R 4 is preferably, from the viewpoint of being able to dope a hole transport compound at low temperature and with high efficiency, independently a halogen, an optionally substituted alkyl group having 1 to 20 carbon atoms, an optionally substituted alkenyl group having 1 to 20 carbon atoms, an optionally substituted alkynyl group having 1 to 20 carbon atoms, or an optionally substituted alkoxy group having 1 to 20 carbon atoms, more preferably a halogen or an optionally substituted alkyl group having 1 to 20 carbon atoms, and even more preferably a halogen, a methyl group, an ethyl group, an n-propyl group, or an isopropyl group.

[0026] n is not particularly limited as long as it is an integer from 0 to 5, but for doping a hole transport compound at low temperature and with high efficiency From the perspective of being dopable, it is preferably an integer from 0 to 3, more preferably from 0 to 1, and even more preferably 0. When n is 0, it means that R 4 is not substituted on the benzene ring in formula (1), and all carbons are bonded to hydrogens, that is, R 4 The aromatic hydrocarbon ring group that can be substituted represents a phenyl group having no substituent. When R 4 is bonded to the benzene ring in formula (1), the substitution position is not particularly limited and may be substituted at any of the o-position, m-position, and p-position. However, from the perspective of doping the hole transport compound at low temperature and with high efficiency, it is preferably substituted at the p-position.

[0027] Ar represents a monovalent aromatic hydrocarbon ring or an aromatic heterocyclic ring which may have a substituent. Examples of the aromatic hydrocarbon group which may have a substituent include monocyclic aromatic hydrocarbon ring groups such as phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 2,4-xylyl group, p-cumenyl group, mesityl group; condensed ring aromatic hydrocarbon ring groups such as 1-naphthyl group, 2-naphthyl group, 1-anthryl group, 2-anthryl group, 5-anthryl group, 1-phenanthryl group, 9-phenanthryl group, 1-ace naphthyl group, 2-azulenyl group, 1-pyrenyl group, 2-triphenylenyl group, etc. Examples of the aromatic heterocyclic group which may have a substituent include 2-furyl group, 3-furyl group, 2-thienyl group, 3-thienyl group, 1-pyrrolyl group, 2-pyrrolyl group, 3-pyrrolyl group, 2-pyridyl group, 3-pyridyl group, 4-pyridyl group, 2-pyrazyl group, 2-oxazolyl group, 3-isoxazolyl group, 2-thiazolyl group, 3-isothiazolyl group, 2-imidazolyl group, 3-pyrazolyl group, 2-quinolyl group, 3-quinolyl group, 4-quinolyl group, 5-quinolyl group, 6-quinolyl group, 7-quinolyl group, 8-quinolyl group, 1-isoquinolyl group, 2-quinoxalilyl group, 2-benzofuryl group, 2-benzothienyl group, N-indolyl group, N-carbazolyl group, 9-acridinyl group, etc.

[0028] In addition, examples of the above-mentioned optional substituents include halogen, cyano group, amino group, carboxyl group, ester group, alkylcarbonyl group, acetyl group, sulfonyl group, silyl group, boryl group, nitrile group, thio group, seleno group, alkyl group, halogenated alkyl group, alkenyl group, halogenated alkenyl group, alkynyl group, halogenated alkynyl group, alkoxy group, halogenated alkoxy group, and the like. The number of carbon atoms in the above-mentioned alkyl group, halogenated alkyl group, alkenyl group, halogenated alkenyl group, alkynyl group, halogenated alkynyl group, alkoxy group, and halogenated alkoxy group is preferably 1 to 20.

[0029] From the viewpoint of being able to dope a hole transport compound at low temperature and with high efficiency, Ar is preferably a monovalent aromatic hydrocarbon ring which may have a substituent. As the monovalent aromatic hydrocarbon ring group, a phenyl group, a biphenyl group, or a terphenyl group is preferable, and a phenyl group is more preferable. In addition, from the viewpoint of being able to dope a hole transport compound at low temperature and with high efficiency, the optional substituent in Ar is preferably halogen, halogenated alkyl group, halogenated alkenyl group, or halogenated alkynyl group, more preferably halogen or halogenated alkyl group, even more preferably fluorine (fluoro group) or fluoroalkyl group, and particularly preferably fluorine (fluoro group) or trifluoromethyl group. Furthermore, it is preferable that all the positions where Ar can be substituted are substituted with these preferred substituents. The number of the optional substituents in Ar is not particularly limited as long as it is 1 to 5. For example, when it is a phenyl group which may have a substituent and is substituted with the above-mentioned preferred substituents, from the viewpoint of being able to dope a hole transport compound at low temperature and with high efficiency, the number of the optional substituents is preferably 5, more preferably substituted with a combination of 4 fluoro groups and 1 fluoroalkyl group, and particularly preferably the fluoroalkyl group is substituted at the p-position. It is preferably substituted.

[0030] Typical examples of the compound represented by formula (1) are specifically exemplified below as exemplified compounds (1-1) to (1-21), but are not limited thereto.

[0031] [Chemical formula]

[0032] [Method for producing the compound] The compound represented by formula (1) can be produced by applying known synthesis methods in the technical field to which the present invention pertains. For example, an alkali metal salt of the anion represented by formula (1) and a chloride salt of the cation represented by formula (1) are stirred in a desired solvent, and the precipitate is purified to obtain the compound. When producing the compound by this exemplified method, the type of cation that binds to the anion represented by formula (1) and the type of anion that binds to the cation represented by formula (1) are not particularly limited. Also, the type of each of the above desired solvents is not particularly limited as long as the object to be dissolved can be dissolved.

[0033] [Use of the compound] The compound represented by formula (1) can be used as a dopant that can dope a hole-transporting organic compound used in a photoelectric conversion device at low temperature and with high efficiency. By doping the hole-transporting organic compound with the above compound, the conductivity of the hole-transporting organic compound can be improved, and by using the hole-transporting organic compound, a photoelectric conversion device with high photoelectric conversion efficiency can be manufactured. Also, the compound represented by formula (1) can also be used as a polymerization initiator (compound for polymerization initiator) for a photocurable resin. For example, a composition containing a polymerization initiator containing the above compound and a monomer having a functional group such as an epoxy group or a vinyl group is produced, mixed with the composition, and irradiated with light at an appropriate wavelength to generate an acid and initiate polymerization. Hereinafter, the composition that can be used in a photoelectric conversion device will be described in detail.

[0034] <2. Composition> A composition which is another embodiment of the present invention (also simply referred to as "composition") is a composition comprising the compound represented by the above formula (1) and a hole-transporting organic compound. The above composition can be used in a photoelectric conversion device. As described above, since the compound represented by the above formula (1) can improve the conductivity of the hole-transporting organic compound, by using the composition according to this embodiment, a photoelectric conversion device with high photoelectric conversion efficiency can be manufactured.

[0035] The content of the compound represented by formula (1) in the composition is not particularly limited. However, from the viewpoint of being able to dope the hole-transporting organic compound at low temperature and with high efficiency and ensuring high conductivity, it is usually 0.1% by weight or more, preferably 0.2% by weight or more, more preferably 0.3% by weight or more, further preferably 0.4% by weight or more, particularly preferably 0.5% by weight or more. Also, it is usually 50% by weight or less, preferably 40% by weight or less, more preferably 30% by weight or less, further preferably 20% by weight or less, particularly preferably 10% by weight or less. Also, the compound represented by formula (1) contained in the composition may be used alone or in combination of two or more in any kind and ratio. Also, a dopant other than the compound represented by formula (1) may be included. The content of the hole-transporting organic compound in the composition is not particularly limited. However, from the viewpoint of being able to ensure high conductivity, it is usually 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more, further preferably 80% by weight or more, particularly preferably 90% by weight or more. Also, it is usually 99.9% by weight or less, preferably 99.8% by weight or less, more preferably 99.7% by weight or less, further preferably 99.6% by weight or less, particularly preferably 99.5% by weight or less. Also, the hole-transporting organic compound contained in the composition may be used alone or in combination of two or more in any kind and ratio.

[0036] The compound represented by the above formula (1) is a salt composed of an anion containing boron and a cation containing iodine. In the composition, these may be in a state where they are bonded by an ionic bond, or the above anion and cation may dissociate and exist in a state where they are bonded to other ions in the composition. When the anion and cation in the compound represented by the above formula (1) are present in the composition, it can be presumed that the compound represented by the above formula (1) has been added.

[0037] Doping of the hole-transporting organic compound with the compound represented by the above formula (1) is not particularly limited as long as the doping reaction proceeds. For example, it can be carried out by heating a composition containing these compounds. The heating temperature in this case can be appropriately set according to the compounds used, but doping with the compounds according to this embodiment can be carried out at a lower temperature than doping with conventional dopants.

[0038] [Hole-transporting organic compound] (Structure of hole-transporting organic compound) The hole-transporting organic compound is not particularly limited as long as it has hole-transporting ability, and known compounds can be used. For example, compounds known as organic semiconductor compounds can be used, and low-molecular compounds and high-molecular compounds are known. Examples of low-molecular organic semiconductor compounds include polycyclic aromatic compounds, and specific examples include acene compounds such as tetracene or pentacene, oligothiophene compounds, phthalocyanine compounds, perylene compounds, rubrene compounds, carbazole compounds, or arylamine compounds such as triarylamine compounds, etc. Examples of high-molecular organic semiconductor compounds include conjugated polymers such as polythiophene polymers, polyacetylene polymers, polyaniline polymers, polyphenylene polymers, polyphenylene vinylene polymers, polyfluorene polymers, or polypyrrole polymers, or arylamine polymers such as triarylamine polymers.

[0039] The hole-transporting organic compound is preferably an arylamine compound, more preferably a triarylamine compound. An arylamine compound refers to a compound having an arylamine structure (a bond between an aryl group and a nitrogen atom), and includes arylamine polymers. An arylamine polymer refers to a polymer whose repeating unit contains an arylamine structure, and is also referred to as a polyarylamine compound. A triarylamine compound refers to a compound having a triarylamine structure (a bond of three aryl groups to the same nitrogen atom), and includes triarylamine polymers. A triarylamine polymer refers to a polymer whose repeating unit contains a triarylamine structure, and is also referred to as a polytriarylamine compound. Such an arylamine compound or triarylamine compound is preferably oxidized stably by the compound (dopant) represented by the above formula (1) and can exhibit good hole-transporting ability. Among them, triarylamine compounds are more preferred.

[0040] An aryl group (or aromatic group) refers to an aromatic hydrocarbon ring group or an aromatic heterocyclic group, and includes monocyclic, condensed ring, and those in which monocyclic or condensed rings are linked. The aromatic group is not particularly limited, but preferably has an sp 2 hybridized carbon number of 42 or less, and more preferably an sp 2 hybridized carbon number of 36 or less. Specific examples of the aromatic hydrocarbon ring group include a phenyl group, a biphenyl group, or a fluorenyl group, etc. Specific examples of the aromatic heterocyclic group include a thienyl group, a furyl group, a pyrrolyl group, a pyridyl group, or an imidazolyl group, etc.

[0041] The aromatic group may further have additional substituents. The substituents that the aromatic group may have are not particularly limited, and examples thereof include a halogen atom, a hydroxyl group, a cyano group, an amino group, a carboxyl group, an ester group, an alkylcarbonyl group, an acetyl group, a sulfonyl group, a silyl group, a boryl group, a nitrile group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, a thio group, a seleno group, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, and the like. Preferred substituents that the aryl group has include an alkyl group having 1 to 12 carbon atoms. Here, the amino group is preferably a dialkylamino group having 2 to 12 carbon atoms, an alkylarylamino group having 7 to 20 carbon atoms, or a diarylamino group having 12 to 30 carbon atoms. As the substituents that the aryl group has, an alkyl group having 1 to 12 carbon atoms is preferably mentioned.

[0042] As the hole-transporting organic compound used in this embodiment, as described above, a triarylamine-based compound is suitable. However, from the viewpoint of having high electrochemical stability and high hole-transporting ability and being a compound suitable for the wet film-forming method, a polyarylamine-based compound having a repeating unit represented by the following formula (I) is more preferable.

[0043] [Chemical formula]

[0044] In formula (I), R 5 and R 6 each independently represent a hydrogen atom, an aromatic hydrocarbon ring group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or an alkyl group which may have a substituent. R 5 and R 6 may be bonded to each other to form a ring. n represents an integer of 0 to 3. Ar 2 and Ar 3 each independently represent a direct bond, an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent. Ar 4 ~Ar 6Each independently represents an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent.

[0045] The fluorene ring in the main chain of the above formula (I) is strongly involved in charge transport due to the spread of HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) in this part.

[0046] Ar 2 ~Ar 6 Examples of the aromatic hydrocarbon ring group which may have a substituent in Ar

[0047] ~Ar 2 ~Ar 6 Examples of the aromatic heterocyclic group which may have a substituent in Ar

[0048] From the viewpoints of solubility in an organic solvent and heat resistance, Ar 2 ~Ar 6 Each independently represents Ben A group derived from a ring selected from the group consisting of a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a triphenylene ring, a pyrene ring, a thiophene ring, a pyridine ring, and a fluorene ring is preferred. Also, Ar 1 ~Ar 5 As, a divalent group in which one or more rings selected from the above group are directly bonded or linked by a -CH=CH- group is also preferred, and a biphenylene group and a terphenylene group are more preferred. Ar 2 ~Ar 6 The substituents that the aromatic hydrocarbon group and the aromatic heterocyclic group in Ar~Ar may have are not particularly limited, and examples thereof include one or more selected from the following [Substituent Group Z].

[0049] (Substituent Group Z) An alkyl group having preferably 1 to 24 carbon atoms, more preferably 1 to 12 carbon atoms, such as a methyl group or an ethyl group; an alkenyl group having preferably 2 to 24 carbon atoms, more preferably 2 to 12 carbon atoms, such as a vinyl group; An alkynyl group having preferably 2 to 24 carbon atoms, more preferably 2 to 12 carbon atoms, such as an ethynyl group; An alkoxy group having preferably 1 to 24 carbon atoms, more preferably 1 to 12 carbon atoms, such as a methoxy group or an ethoxy group; An aryloxy group having preferably 4 to 36 carbon atoms, more preferably 5 to 24 carbon atoms, such as a phenoxy group, a naphthoxy group, or a pyridyloxy group; an alkoxycarbonyl group having preferably 2 to 24 carbon atoms, more preferably 2 to 12 carbon atoms, such as a methoxycarbonyl group or an ethoxycarbonyl group; A dialkylamino group having preferably 2 to 24 carbon atoms, more preferably 2 to 12 carbon atoms, such as a dimethylamino group or a diethylamino group; A diarylamino group having preferably 10 to 36 carbon atoms, more preferably 12 to 24 carbon atoms, such as a diphenylamino group, a ditolylamino group, or an N-carbazolyl group; An arylalkylamino group having preferably 6 to 36 carbon atoms, more preferably 7 to 24 carbon atoms, such as a phenylmethylamino group;

[0050] An acyl group such as an acetyl group or a benzoyl group, preferably having 2 to 24 carbon atoms, more preferably 2 to 12 carbon atoms; A halogen atom such as a fluorine atom or a chlorine atom; A haloalkyl group such as a trifluoromethyl group, preferably having 1 to 2 carbon atoms, more preferably 1 to 6 carbon atoms; An alkylthio group such as a methylthio group or an ethylthio group, preferably having 1 to 24 carbon atoms, more preferably 1 to 12 carbon atoms; An arylthio group such as a phenylthio group, a naphthylthio group or a pyridylthio group, preferably having 4 to 36 carbon atoms, more preferably 5 to 24 carbon atoms; A silyl group such as a trimethylsilyl group or a triphenylsilyl group, preferably having 2 to 36 carbon atoms, more preferably 3 to 24 carbon atoms; A siloxy group such as a trimethylsiloxy group or a triphenylsiloxy group, preferably having 2 to 36 carbon atoms, more preferably 3 to 24 carbon atoms; A cyano group; An aromatic hydrocarbon group such as a phenyl group or a naphthyl group, preferably having 6 to 36 carbon atoms, more preferably 6 to 24 carbon atoms; An aromatic heterocyclic group such as a thienyl group or a pyridyl group, preferably having 3 to 36 carbon atoms, more preferably 4 to 24 carbon atoms; Each of the above substituents may further have a substituent, and examples thereof include the groups exemplified in the substituent group Z.

[0051] Ar 2 ~Ar 6 The molecular weight of the substituent that the aromatic hydrocarbon group and the aromatic heterocyclic group in ~ may have is preferably 500 or less, more preferably 250 or less, including the further substituted group. In terms of improving the solubility in an organic solvent, as the substituent that the aromatic hydrocarbon group and the aromatic heterocyclic group in Ar 2 ~Ar 6 may have, an alkyl group having 1 to 12 carbon atoms and an alkoxy group having 1 to 12 carbon atoms are each independently preferred.

[0052] In addition, when n is 2 or more, the repeating unit represented by the above formula (I) has two or more Ars 5 and Ar 6 . In that case, Ar 5 and Ar 6 may be the same or different from each other. Further, Ars 5 and Ars 6 may be bonded to each other directly or via a linking group to form a cyclic structure. Examples of the linking group include an alkylene group having 1 to 20 carbon atoms, an alkenylene group having 1 to 20 carbon atoms, an alkynylene group having 1 to 20 carbon atoms, an arylene group, an ester group, -CO-, -NH-, -O-, -S-, or a combination thereof.

[0053] The method for synthesizing the above poly(triarylamine) compound is not particularly limited. For example, it can be synthesized by the method described in JP-A-2009-263665, and can be synthesized by oxidative polymerization of a triarylamine monomer or a cross-coupling reaction using a transition metal catalyst. The number average molecular weight of this poly(triarylamine) compound can be adjusted by the reaction temperature, reaction time, catalyst, etc., but it is preferably 8,500 or more.

[0054] By setting the number average molecular weight of this poly(triarylamine) compound to 8,500 or more, the durability (maintenance rate of the photoelectric conversion efficiency) of the photoelectric conversion element tends to be improved. More preferably, it is 9,000 or more, and still more preferably 10,000 or more. On the other hand, the upper limit of this number average molecular weight is not particularly limited. For example, setting it to 500,000 or less is preferable in terms of ensuring the solubility of the poly(triarylamine) compound in an organic solvent. More preferably, it is 300,000 or less, and still more preferably 200,000 or less.

[0055] Furthermore, the weight average molecular weight of the poly(triarylamine) compound is preferably 9,000 or more, more preferably 10,000 or more, and even more preferably 15,000 or more. By setting this lower limit, the durability of the photoelectric conversion element tends to improve. On the other hand, the upper limit of the weight average molecular weight is not particularly limited, but is preferably 500,000 or less, more preferably 300,000 or less, and even more preferably 200,000 or less. By setting this upper limit, cost reduction can be achieved and the solubility in the solvent can be ensured. When the poly(triarylamine) compound simultaneously satisfies the above ranges of the number average molecular weight and the weight average molecular weight, the maintenance rate of the photoelectric conversion efficiency may be further improved.

[0056] [Properties of Hole-Transporting Organic Compounds] The HOMO (highest occupied molecular orbital) of the hole-transporting organic compound is not particularly limited. However, since compounds having a low HOMO, which are difficult to dope with existing dopants, can be doped with high efficiency, it is usually -6.0 eV or more, preferably -5.7 eV or more. Also, it is usually -4.5 eV or less, preferably -5.0 eV or less. The HOMO of the hole-transporting organic compound can be controlled by the molecular structure of the main skeleton and various substituents.

[0057] [Other Substances] The composition may contain, within the range where the effects of the present invention can be obtained, the compound represented by the above formula (1) and substances other than the hole-transporting organic compound (other substances). Examples of the other substances include, for example, solvents, crosslinking agents, thickeners, and the like. The content of the solvent in the composition is not particularly limited, but is usually 0.1% by weight or more, preferably 0.2% by weight or more, and more preferably 0.3% by weight or more. Also, the content of the crosslinking agent is not particularly limited, but is usually 0.001% by weight or more, preferably 0.002% by weight or more, and more preferably 0.003% by weight or more. In addition, the content of the thickener is not particularly limited, but is usually 0.001% by weight or more, preferably 0.002% by weight or more, and more preferably 0.003% by weight or more.

[0058] [Method for producing hole transporting organic compound] The method for producing the hole transporting organic compound is not particularly limited, and depending on the type of the compound, it can be produced by appropriately using a known production method.

[0059] [Method for producing composition] The method for producing the composition is not particularly limited. For example, it can be produced by mixing the compound represented by the above formula (1), the hole transporting organic compound, and other substances that can be optionally added.

[0060] [Use of composition] Another embodiment of the present invention is a film produced using the composition. This film can be mainly used as a hole transporting layer for various devices such as OLED elements and photoelectric conversion elements. The film formation conditions are not particularly limited and can be appropriately changed according to the material and applied. However, it is preferable to form a film by coating to obtain a coating film. The thickness of the film is not particularly limited. However, when used as a hole transporting layer for various devices, it is usually 1 nm or more, preferably 5 nm or more, and usually 5 μm or less.

[0061] The above method for producing the film is not particularly limited as long as it is produced using the composition, and any production method including a preparation step of preparing the composition and a film formation step of forming the film from the composition may be used. In the preparation step, the method for obtaining the composition is not particularly limited, and examples include a method of mixing the raw materials that can be included in the above composition to obtain the composition. The mixing method is not particularly limited. In the film-forming step, the method of forming a film from the composition is not particularly limited, and it is preferable to form a film by coating. The coating method is not particularly limited, and examples thereof include a spin coating method, an inkjet method, a doctor blade method, a drop casting method, a reverse roll coating method, a gravure coating method, a kiss coating method, a roll brush method, a spray coating method, an air knife coating method, a wire bar coating method, a pipe doctor method, an impregnation coating method, or a curtain coating method. Among these, the spin coating method is preferable. The film-forming conditions are not particularly limited. For example, the temperature for film formation can be appropriately changed according to the material and the substrate on which the material is coated, but it is preferably 10 to 100°C. The substrate is not particularly limited and may be a material described in the substrate section below. Examples thereof include polyimide, PET, PEN, and glass.

[0062] Further, the method for manufacturing the film may further include a solvent evaporation step. Examples of the solvent evaporation method include heating, reduced pressure, and blowing. The solvent evaporation step may be carried out after the above-mentioned film-forming step, or may be carried out simultaneously, such as by performing coating and heating at the same time.

[0063] <3. Photoelectric conversion element> A photoelectric conversion element (also simply referred to as "photoelectric conversion element") which is another embodiment of the present invention is a photoelectric conversion element including at least a photoelectric conversion layer and the above composition or a film thereof. The photoelectric conversion element is not particularly limited as long as it has a photoelectric conversion layer and the above composition or a film thereof, and a known configuration can be applied. Specifically, as the use of the film of the above composition in the photoelectric conversion element, the above film can be used for the hole transport layer in the photoelectric conversion element. The hole transport layer is a layer that extracts holes from the photoelectric conversion layer (also referred to as "active layer") to the anode. Hereinafter, an example of a specific embodiment of the photoelectric conversion element will be described with reference to FIG. 1, but it is not limited thereto. Further, the photoelectric conversion element in the following description includes a pair of electrodes composed of an upper electrode and a lower electrode, an active layer located between the pair of electrodes, and a hole transport layer located between the active layer and at least one of the pair of electrodes and formed using the above composition. It is a photoelectric conversion element having

[0064] FIG. 1 is a cross-sectional view schematically showing an embodiment of the photoelectric conversion element. The photoelectric conversion element shown in FIG. 1 is a photoelectric conversion element used in a general thin-film solar cell, but the photoelectric conversion element according to this embodiment is not limited to the one shown in FIG. 1. In the photoelectric conversion element 100 shown in FIG. 1, the lower electrode 101, the active layer 103, and the upper electrode 105 are arranged in this order. Further, in the photoelectric conversion element 100, the buffer layer 102 existing between the lower electrode 101 and the active layer 103 can be a hole transport layer which is a film obtained using the above composition. However, the photoelectric conversion element 100 may have a buffer layer 104 between the upper electrode 105 and the active layer 103, and in this case, this buffer layer 104 can also be the above-mentioned hole transport layer. Further, as shown in FIG. 1, the photoelectric conversion element 100 may have a substrate 106, and may also have other layers such as an insulator layer and a work function tuning layer.

[0065] [Photoelectric conversion layer (active layer)] The active layer contains a semiconductor material, and its ionization potential range may be -6.0 eV or more and -5.7 eV or less, and its band gap may be 1.6 eV or more and 2.3 eV or less.

[0066] By setting the ionization potential of the active layer to -6.0 eV or more and -5.7 eV or less and the band gap to 1.6 eV or more and 2.3 eV or less, it is possible to improve the power generation efficiency with respect to fluorescent lamps and LED lamps, which are visible light sources widely used indoors and indoors. This is because when the ionization potential of the active layer is less than -6.0 eV, there is insufficient absorption range in the long wavelength region for a light source in the visible light region that provides white light. Preferably, it is -5.95 eV or more, more preferably -5.9 eV or more. Also, when the ionization potential of the active layer exceeds -5.7 eV, the loss of the obtained voltage becomes large for a light source in the visible light region. Preferably, it is -5.75 eV or less, more preferably -5.8 eV or less. Furthermore, when the band gap of the active layer is less than 1.6 eV, there is insufficient energy required to separate excitons generated in the semiconductor into positive and negative charges when receiving indoor light sources. Preferably, it is 1.65 eV or more, more preferably 1.7 eV or more, and even more preferably 1.75 eV or more. Also, when the band gap of the active layer exceeds 2.3 eV, it becomes excessive energy for excitons generated by indoor light sources, resulting in inferior power generation efficiency. Preferably, it is 2.25 eV or less, more preferably 2.2 eV or less, and even more preferably 2.15 eV or less.

[0067] In the embodiment of FIG. 1, the active layer 103 is a layer where photoelectric conversion occurs. When the photoelectric conversion element 100 receives light, the light is absorbed by the active layer 103 to generate carriers, and the generated carri ers are extracted from the lower electrode 101 and the upper electrode 105.

[0068] The semiconductor material used for the active layer 103 is not particularly limited, and known materials can be used. For example, organic semiconductor materials such as naphthalene and pentacene; silicon-based semiconductor materials such as amorphous silicon (a-Si) and polysilicon (poly-Si); or inorganic semiconductor materials such as compounds having a perovskite structure such as BaTiO3 can be used. Among these, from the perspective of easily manufacturing a flexible and lightweight photoelectric conversion element, an organic semiconductor material is preferred. The semiconductor material used for the active layer may be used alone as one type, or two or more types may be combined in any type and ratio.

[0069] There is no particular limitation on the thickness of the active layer 103. In terms of being able to absorb more light, the thickness of the active layer 103 is 10 nm or more in one embodiment, 50 nm or more in another embodiment, 100 nm or more in yet another embodiment, and 120 nm or more in still another embodiment. On the other hand, in terms of reducing the series resistance or enhancing the charge extraction efficiency, the thickness of the active layer 103 is 1500 nm or less in one embodiment, 1200 nm or less in another embodiment, and 800 nm or less in yet another embodiment.

[0070] The method for forming the active layer 103 is not particularly limited, and any method can be used. Specific examples include a coating method and a vapor deposition method (or co-vapor deposition method). The coating method can be used in terms of being able to easily form the active layer 103. For example, there is a method of forming the active layer 103 by applying a coating solution containing a semiconductor compound or its precursor and heating and drying it as necessary. Also, after applying such a coating solution, a semiconductor compound can be precipitated by further applying a solvent in which the solubility of the semiconductor compound is low.

[0071] Any method can be used as the method for applying the coating solution. For example, spin coating method, inkjet method, doctor blade method, drop casting method, reverse roll coating method, gravure coating method, kiss coating method, roll brush method, spray coating method, air knife coating method, wire bar coating method, pipe doctor method, impregnation coating method, or curtain coating method, etc. can be mentioned.

[0072] [Electrode] The electrode has a function of collecting holes and electrons generated by light absorption in the active layer 103. The photoelectric conversion element 100 according to an embodiment of the present invention has a pair of electrodes, one of the pair of electrodes is called the upper electrode, and the other is called the lower electrode. When the photoelectric conversion element 100 has a substrate or is provided on a substrate, the electrode closer to the substrate can be called the lower electrode, and the electrode farther from the substrate can be called the upper electrode, respectively. Also, the transparent electrode can be called the lower electrode, and the electrode having lower transparency than the lower electrode can be called the upper electrode, respectively. The photoelectric conversion element 100 shown in FIG. 1 has a lower electrode 101 and an upper electrode 105.

[0073] As the pair of electrodes, an anode suitable for hole collection and a cathode suitable for electron collection can be used. In this case, the photoelectric conversion element 100 may have a normal configuration in which the lower electrode 101 is an anode and the upper electrode 105 is a cathode, or may have an inverted configuration in which the lower electrode 101 is a cathode and the upper electrode 105 is an anode.

[0074] Either one of the pair of electrodes may be translucent, and both may be translucent. Having translucency means that sunlight transmits 40% or more. Also, it is preferable that the sunlight transmittance of the transparent electrode is 70% or more so that more light can pass through the transparent electrode and reach the active layer 103. The light transmittance can be measured with a spectrophotometer (for example, U-4100 manufactured by Hitachi High-Tech Corporation).

[0075] There is no particular limitation on the constituent members of the lower electrode 101 and the upper electrode 105, or the anode and the cathode, and their manufacturing methods, and well-known techniques can be used. For example, the members and their manufacturing methods described in known documents such as International Publication No. 2013 / 171517, International Publication No. 2013 / 180230, or Japanese Patent Application Laid-Open No. 2012-191194 can be used.

[0076] [Buffer layer] The buffer layer is a layer located between at least one of the active layer 103 and the pair of electrodes 101 and 105. The buffer layer can be used, for example, to improve the carrier transfer efficiency from the active layer 103 to the lower electrode 101 or the upper electrode 105.

[0077] In this embodiment, as the buffer layer, it has a hole transport layer formed by using the above composition.

[0078] As described above, the photoelectric conversion element 100 can have a buffer layer 102 between the lower electrode 101 and the active layer 103, or can have a buffer layer 104 between the upper electrode 105 and the active layer 103. Further, the photoelectric conversion element 100 can also have both the buffer layer 102 and the buffer layer 104. Here, the buffer layer 102 provided between the lower electrode 101 and the active layer 103 and the buffer layer 104 provided between the upper electrode 105 and the active layer 103 may be composed of different materials. That is, while one buffer layer is a hole transport layer containing the compound represented by the formula (1), the other buffer layer may be an electron transport layer or the like composed of a substance different from this. As described above, the hole transport layer containing the compound represented by the formula (1) may be located between the lower electrode 101 and the active layer 103, or may be located between the active layer 103 and the upper electrode 105. However, when forming the hole transport layer containing the compound represented by the formula (1) by a coating method, since the coating solvent may immerse the active layer 103 and affect the active layer 103, the hole transport layer is preferably located between the lower electrode 101 and the active layer 103.

[0079] The buffer layer provided between the anode and the active layer may be called a hole transport layer, and the buffer layer provided between the cathode and the active layer may be called an electron transport layer. In this embodiment, since it tends to be easy to control the amount of transported charges in the n-i-p stacked type photoelectric conversion element, the buffer layer containing the compound represented by the formula (1) is used as a hole transport layer. In addition, for the hole transport layer containing the compound represented by formula (1), a film prepared using the above-described composition (ink for film formation) can be used. The conditions are not particularly limited, but for example, it can be formed by heat or under reduced pressure. Specifically, when forming a film by heat, the heating conditions are not particularly limited. For example, the heating temperature can be 40 to 200°C, preferably 50 to 150°C, and the heating time can be 0.1 to 100 minutes, preferably 1 to 10 minutes. The heating atmosphere may be air, but is preferably an inert gas such as nitrogen or argon.

[0080] Regarding the electron transport layer, any material that can improve the extraction efficiency of electrons from the active layer to the cathode can be used. Specifically, inorganic compounds, organic compounds, or the organic-inorganic perovskite compounds according to the present invention described in known documents such as International Publication No. 2013 / 171517, International Publication No. 2013 / 180230, or Japanese Patent Application Laid-Open No. 2012-191194 can be mentioned. For example, as the inorganic compounds, salts of alkali metals such as lithium, sodium, potassium, or cesium, and metal oxides such as zinc oxide, titanium oxide, aluminum oxide, or indium oxide can be mentioned. As the organic compounds, bathocuproine (BCP), bathophenanthroline (Bphen), (8-hydroxyquinolinato)aluminum (Alq3), boron compounds, oxadiazole compounds, benzimidazole compounds, naphthalenetetracarboxylic dianhydride (NTCDA), perylenetetracarboxylic dianhydride (PT CDA), fullerene compounds, or phosphine compounds having a double bond with a Group 16 element of the periodic table such as phosphine oxide compounds or phosphine sulfide compounds can be mentioned.

[0081] The film thickness of the buffer layer is not particularly limited as long as it includes the hole transport layer in the present embodiment. In one embodiment, it is 0.5 nm or more, in another embodiment, it is 1 nm or more, and in still another embodiment, it is 5 nm or more. On the other hand, in one embodiment, it is 1 μm or less, in another embodiment, it is 500 nm or less, in still another embodiment, it is 200 nm or less, and in still another embodiment, it is 150 nm or less. When the film thickness of the buffer layer is within the above range, the carrier transfer efficiency is likely to be improved, and the photoelectric conversion efficiency can be improved.

[0082] Further, including the hole transport layer in the present embodiment, there is no limitation on the method for forming the buffer layer, and the forming method can be selected according to the characteristics of the material. For example, a coating solution containing the above-described hole transporting organic compound, the compound represented by the above formula (1), and a solvent is prepared, and the buffer layer can be formed by using a wet film-forming method such as a spin coating method or an inkjet method. Also, the buffer layer can be formed by a dry film-forming method such as a vacuum evaporation method.

[0083] [5. Substrate] The photoelectric conversion element 100 usually has a substrate 106 that serves as a support. However, the photoelectric conversion element according to the present embodiment may not have the substrate 106. The material of the substrate 106 is not particularly limited as long as the effects of the present invention are not significantly impaired. For example, materials described in known documents such as International Publication No. 2013 / 171517, International Publication No. 2013 / 180230, or Japanese Patent Application Laid-Open No. 2012-191194 can be used.

[0084] [6. Method for manufacturing a photoelectric conversion element] According to the above-described method, by forming each layer constituting the photoelectric conversion element 100, the photoelectric conversion element 100 can be manufactured. There is no particular limitation on the method for forming each layer constituting the photoelectric conversion element 100, and it can be formed by a sheet-to-sheet (Manya) method or a roll-to-roll method.

[0085] The roll-to-roll method is a method in which a flexible substrate wound in a roll form is fed out and processed while being intermittently or continuously conveyed until it is wound up by a take-up roll. According to the roll-to-roll method, since it is possible to batch process a long substrate on the order of km, the roll-to-roll method is more suitable for mass production than the sheet-to-sheet method. On the other hand, when attempting to form each layer by the roll-to-roll method, due to its structure, there are cases where the film may be scratched or partially peeled off when the film-forming surface comes into contact with the roll.

[0086] The size of the roll that can be used in the roll-to-roll method is not particularly limited as long as it can be handled by the manufacturing apparatus of the roll-to-roll method. However, the upper limit of the outer diameter is preferably 5 m or less, more preferably 3 m or less, and even more preferably 1 m or less. On the other hand, the lower limit is preferably 10 cm or more, more preferably 20 cm or more, and even more preferably 30 cm or more. The upper limit of the outer diameter of the roll core is preferably 4 m or less, more preferably 3 m or less, and even more preferably 0.5 m or less. On the other hand, the lower limit is preferably 1 cm or more, more preferably 3 cm or more, even more preferably 5 cm or more, particularly preferably 10 cm or more, and even more preferably 20 cm or more. The fact that these diameters are below the above upper limit is preferable in terms of high handleability of the roll, and the fact that they are above the lower limit is preferable in that the possibility of the layer formed in each process being broken by bending stress is reduced. The lower limit of the width of the roll is preferably 5 cm or more, more preferably 10 cm or more, and even more preferably 20 cm or more. On the other hand, the upper limit is preferably 5 m or less, more preferably 3 m or less, and even more preferably 2 m or less. The fact that the width is below the upper limit is preferable in terms of high handleability of the roll, and the fact that it is above the lower limit is preferable because the degree of freedom in the size of the photoelectric conversion element 100 is increased.

[0087] After depositing the upper electrode 105, in one embodiment, the photoelectric conversion device 100 can be heated in a temperature range of 50°C or higher, in another embodiment 80°C or higher, while in one embodiment 300°C or lower, in another embodiment 280°C or lower, and in yet another embodiment 250°C or lower (this step may be referred to as an annealing treatment step). Performing the annealing treatment step at a temperature of 50°C or higher can achieve the effect of improving the adhesion between the layers of the photoelectric conversion device 100, for example, the adhesion between the buffer layer 102 and the lower electrode 101, and between the buffer layer 102 and the active layer 103. By improving the adhesion between the layers, the thermal stability and durability of the photoelectric conversion device can be improved. Keeping the temperature of the annealing treatment step at 300°C or lower reduces the possibility of thermal decomposition of the organic compounds contained in the photoelectric conversion device 100. In the annealing treatment step, stepwise heating using different temperatures within the above temperature range may be performed.

[0088] As the heating time, in order to improve the adhesion while suppressing thermal decomposition, in one embodiment it is 1 minute or longer, in another embodiment 3 minutes or longer, while in one embodiment it is 180 minutes or shorter, and in another embodiment 60 minutes or shorter. The annealing treatment step can be terminated when the open-circuit voltage, short-circuit current, and fill factor, which are parameters of the solar cell performance, reach constant values. Also, the annealing treatment step can be carried out under normal pressure and in an inert gas atmosphere to prevent thermal oxidation of the constituent materials. As the heating method, the photoelectric conversion device may be placed on a heat source such as a hot plate, or the photoelectric conversion device may be placed in a heating atmosphere such as an oven. Also, the heating may be performed in a batch mode or a continuous mode.

[0089] [7. Photoelectric Conversion Characteristics] The photoelectric conversion characteristics of the photoelectric conversion element 100 can be obtained as follows. The photoelectric conversion element 100 is irradiated with light of an appropriate spectrum at a certain irradiation intensity, and the current-voltage characteristics are measured. From the obtained current-voltage curve, photoelectric conversion characteristics such as photoelectric conversion efficiency (PCE), short-circuit current density (Jsc), open-circuit voltage (Voc), fill factor (FF), series resistance, and shunt resistance can be obtained. As an example, by irradiating the photoelectric conversion element 100 with white LED light having a color temperature of 5000K at an appropriate irradiation intensity (illuminance), the current-voltage characteristics at each illuminance can be measured.

[0090] The photoelectric conversion element according to this embodiment is excellent in power generation efficiency in the low illuminance range (10 to 5000 lux). In particular, when a light source such as white LED light is used, the photoelectric conversion efficiency can be 20% or more. Further, the photoelectric conversion efficiency at 200 lux can be 25% or more. There is no particular limitation on the upper limit of this efficiency, and the higher the better. Note that this photoelectric conversion efficiency (PCE) is the output (maximum output) at the optimum operating point of the current-voltage curve of the photoelectric conversion element measured by a predetermined irradiation light divided by the total energy amount of this irradiation light (for example, if it is sunlight with an intensity of AM1.5G, it is 100 mW / cm 2 ).

[0091] [8. Photoelectric conversion device] Another embodiment of the present invention, a photoelectric conversion device (simply referred to as a "photoelectric conversion element"), is a photoelectric conversion device including the above-described composition, a photoelectric conversion device including a film of the above-described composition, or a photoelectric conversion device element including the above-described photoelectric conversion element. The specific aspect of the photoelectric conversion device is not particularly limited, and it can be used for an organic electroluminescence device, an organic transistor, or an electrophotographic photoreceptor, etc. Further, the photoelectric conversion device can be used as a power generation device, for example, as a solar cell. FIG. 2 is a cross-sectional view schematically showing the configuration of a solar cell, particularly a thin-film solar cell. However, it is not limited to this embodiment. As shown in FIG. 2, the thin-film solar cell 14 includes a weather-resistant protection film 1, an ultraviolet cut film 2, a gas barrier film 3, a getter material film 4, a sealing material 5, a solar cell device 6, a sealing material 7, a getter material film 8, a gas barrier film 9, and a backsheet 10 in this order. The thin-film solar cell 14 has a photoelectric conversion element according to the present invention as the solar cell element 6. Light is irradiated from the side where the protection film 1 is formed (lower side in FIG. 2) so that the solar cell element 6 generates electricity. Note that the thin-film solar cell 14 does not necessarily have to have all of these constituent members, and necessary constituent members can be arbitrarily selected.

[0092] There are no particular restrictions on these constituent members constituting the photoelectric conversion device and its manufacturing method, and well-known techniques can be used. For example, the techniques described in known documents such as International Publication No. 2013 / 171517, International Publication No. 2013 / 180230, or Japanese Patent Application Laid-Open No. 2012-191194 can be used.

[0093] There are no restrictions on the use of the solar cell, particularly the thin-film solar cell 14 described above, and it can be used for any application. For example, the solar cell can be used as a solar cell for building materials, a solar cell for automobiles, a solar cell for interiors, a solar cell for railways, a solar cell for ships, a solar cell for airplanes, a solar cell for spacecraft, a solar cell for home appliances, a solar cell for mobile phones, or a solar cell for toys. As described above, since it has excellent conversion efficiency in a low-illumination environment, it can be particularly suitably applied to energy harvesting applications.

[0094] The solar cell, particularly the thin-film solar cell 14 described above, may be used as it is, or may be used as a component of a solar cell module. For example, as shown in FIG. 3, a solar cell module 13 having a solar cell, particularly the solar cell 14 described above, provided on a substrate 12 can be manufactured, and this solar cell module 13 can be installed at a use location and used.

Example

[0095] Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to the following examples.

[0096] <Preparation of Compounds> [Compound 1] As compound 1, a compound represented by the following formula (A-1) (manufactured by Tokyo Chemical Industry Co., Ltd.) was used.

[0097] [ka] [Compound 2] Lithium tetrakis(4-trifluoromethyltetrafluorophenyl)borate 8 80 mg of 4-isopropyl-4'-methyldiphenyliodonium chloride and 373 mg of 4-isopropyl-4'-methyldiphenyliodonium chloride were dissolved in dichloromethane and stirred at room temperature for 10 hours. The filtrate was concentrated, and the crude product was purified by silica gel column chromatography to obtain the compound represented by the following formula (A-2).

[0098] [ka]

[0099] [Compound 3] 825 mg of lithium tetrakispentafluorophenylborate and 468 mg of 4-methylphenyliodonium tosylate were dissolved in dichloromethane and stirred at room temperature for 10 hours. The reaction mixture was filtered and the filtrate was concentrated. The crude product was purified by silica gel column chromatography to obtain a compound represented by the following formula (A-3).

[0100] [ka]

[0101] [Compound 4] 1.0 g of lithium tetrakis(4-trifluoromethyltetrafluorophenyl)borate and 470 mg of 4-methylphenyliodonium tosylate were dissolved in dichloromethane and stirred at room temperature for 10 hours. The reaction mixture was filtered and the filtrate was concentrated. The crude product was purified by silica gel column chromatography to obtain the compound represented by the following formula (A-4).

[0102] [Chemical formula]

[0103] [Preparation of hole-transporting organic compound] [Hole-transporting organic compound 1] Under a nitrogen atmosphere, 2,4,6-trimethylaniline and 4,4′-dibromobiphenyl were placed in a two-necked eggplant flask so that the molar ratio was about 1:1. Further, dichlorobis(di-t-butyl(4-dimethylaminophenyl)phosphine)palladium (2 mol%) was added as a catalyst, and the mixture was stirred at 90 °C in toluene. After the reaction was completed, it was cooled to room temperature, a poor solvent was poured into the reaction solution, and the precipitated precipitate was filtered. The obtained solid was dissolved in toluene and passed through a short column of acidic silica gel. By filtration and concentration, hole-transporting organic compound 1 represented by the following formula (B-1) (number average molecular weight 11,000, weight average molecular weight 15,000) was obtained.

[0104] [Chemical formula]

[0105] [Hole-transporting organic compound 2] By the same method as hole-transporting organic compound 1, hole-transporting organic compound 2 represented by the following formula (B-2) (number average molecular weight 12,000, weight average molecular weight 16,000) was obtained.

[0106] [Chemical formula]

[0107] [Positive hole transporting organic compound 3] As the positive hole transporting organic compound 3, a compound represented by the following formula (B-3) (number average molecular weight 41,000, weight average molecular weight 53,000) was used.

[0108] [Chemical formula]

[0109] [Positive hole transporting organic compound 4] As the positive hole transporting organic compound 4, a compound represented by the following formula (B-4) was used.

[0110] [Chemical formula]

[0111] [Positive hole transporting organic compound 5] As the positive hole transporting organic compound 5, a compound represented by the following formula (B-5) was used.

[0112] [Chemical formula]

[0113] [Experiment 1] [Preparation of composition] According to the combinations described in Table 1 below, for 32 mg each of the positive hole transporting organic compounds 1 to 3, the above compound (1.77 mmol) was weighed, 1.6 mL of 1,2-dichlorobenzene was added, and each composition was obtained. The mixing temperature (doping temperature) of each composition is as shown in Table 1 below. Also, in the absorption spectrum of the solution, the time until the absorption intensity derived from the doped compound became constant was measured, and this time was evaluated as the time required for doping (doping time). The evaluation results of the doping time for each composition are shown in Table 1 below.

[0114] [Measurement of HOMO] Using the above hole-transporting organic compounds 1 to 5, the HOMO was measured by photoelectron yield spectroscopy (PYS). The hole-transporting organic compounds 1 to 5 were dissolved in a suitable solvent, and a thin film for measurement was obtained by forming a film on a measurement substrate and drying it. This thin film was set in the substrate holder of a measurement apparatus (PCR-101 manufactured by Optel), a voltage of -50 V was applied under reduced pressure, the excitation light from a deuterium lamp was monochromatized and incident on the sample, and the photoelectrons emitted from the sample were detected. The ionization potential was determined from the plot of the energy of the monochromatized excitation light and the detected amount.

[0115] As a result of the above measurement, it was found that the HOMO of each hole-transporting organic compound was as shown below. · HOMO of hole-transporting organic compound 1: -5.2 to -5.3 eV · HOMO of hole-transporting organic compound 2: -5.4 eV · HOMO of hole-transporting organic compound 3: -5.5 eV · HOMO of hole-transporting organic compound 4: -5.6 eV · HOMO of hole-transporting organic compound 5: -5.7 eV

[0116]

Table 1

[0117] From Table 1 above, it can be seen that the doping time of the hole-transporting organic compound when using Compounds 3 and 4 according to this embodiment is shorter than the doping time of the hole-transporting organic compound when using Compounds 1 and 2 which are not the compounds according to this embodiment. Also, from the results of using Compound 3 according to this embodiment, it can be seen that even at a low doping temperature of 100 °C, doping can be performed in a short time. Furthermore, it can be seen that even for a hole-transporting organic compound having a small HOMO value of -5.5 eV, the doping rate is improved.

[0118] <Experiment 2> <Preparation of Composition> For 16 mg each of the hole-transporting organic compounds 4 and 5, the above compounds 1, 2, and 4 (1.77 mmol) were weighed, and 1.6 mL of 1,2-dichlorobenzene was added to obtain each composition. The mixing temperature (doping temperature) of each composition was unified at 150 °C.

[0119] <Appearance Evaluation> Figure 4 shows photographs showing the appearance of the solution before heating and the appearance of the solution 3 hours after the start of heating at the above doping temperature for each composition. The photographs in Figure 4 show that the solution containing the compound 4 according to this embodiment has a larger change in color over time, that is, a faster doping rate, compared to the solutions containing the compounds 1 and 2 that are not the compounds according to this embodiment. Therefore, it can be seen that by using the compound according to this embodiment, even a hole-transporting organic compound having a small HOMO value of -5.6 to -5.7 eV can achieve a high doping efficiency.

[0120] <Measurement of Absorbance> For the measurement of absorbance, V-770 manufactured by JASCO Corporation was used. 20 μL of each of the above compositions was sampled at the time points when 30 minutes, 1 hour, 2 hours, 3 hours, and 4 hours of heating time had elapsed under heating at the above doping temperature (the evaluation at 30 minutes of heating time was only for the case using compound 4). A solution diluted with 3 mL of 1,2-dichlorobenzene was used to measure the absorbance using a quartz cell with an optical path length of 1 cm. The measurement results of absorbance are shown in Figures 5 and 6. From Figures 5 and 6, it shows that the solution containing the compound 4 according to this embodiment has a larger change in color over time, that is, a faster doping rate, compared to the solutions containing the compounds 1 and 2 that are not the compounds according to this embodiment. Therefore, it can be seen that by using the compound according to this embodiment, even a hole-transporting organic compound having a small HOMO value of -5.6 to -5.7 eV can achieve a high doping efficiency.

[0121] <Experiment 3> <Preparation of Composition> The above compound 1 was mixed with a hole-transporting organic compound 3 respectively such that the ratio of compound 1 to hole-transporting organic compound 3 was 4:100 (the content of the compound was 4% by weight based on the hole-transporting organic compound), to obtain a composition. The mixing temperature (doping temperature) of the composition was 150°C. Also, with the same combination, the compound 1 and the hole-transporting organic compound 3 were mixed such that the ratio of compound 1 to hole-transporting organic compound 3 was 8:100 (the content of the compound was 8% by weight based on the hole-transporting organic compound), to obtain a composition. Also, the above compound 4 was mixed with a hole-transporting organic compound 3 respectively such that the ratio of compound 4 to hole-transporting organic compound 3 was 6:100 (the content of the compound was 6% by weight based on the hole-transporting organic compound), to obtain a composition. The mixing temperature (doping temperature) of the composition was 150°C. Also, with the same combination, the compound 4 and the hole-transporting organic compound 3 were mixed such that the ratio of compound 4 to hole-transporting organic compound 3 was 18:100 (the content of the compound was 18% by weight based on the hole-transporting organic compound), to obtain a composition. The above compound 2 was mixed with a hole-transporting organic compound 4 respectively such that the ratio of compound 2 to hole-transporting organic compound 4 was 5:100 (the content of the compound was 5 mol% based on the hole-transporting organic compound), to obtain a composition. The mixing temperature (doping temperature) of the composition was 150°C. Also, the above compound 4 was mixed with a hole-transporting organic compound 4 respectively such that the ratio of compound 4 to hole-transporting organic compound 4 was 5:100 (the content of the compound was 5 mol% based on the hole-transporting organic compound), to obtain a composition. The mixing temperature (doping temperature) of the composition was 150°C.

[0122] <Measurement of Conductivity> The conductivity was measured by forming a film of each of the above compositions on a substrate (glass) with an electrode pattern by spin coating, and measuring the resistance between each electrode pattern. By forming patterns with different electrode distances in advance, the resistance of the composition itself with the component of the contact resistance subtracted can be evaluated. First, a film of each composition was spin-coated on the substrate at room temperature, heated at 90°C for 5 minutes, and then the conductivity was measured. Then, after additional heating at 120°C for 5 minutes, the conductivity measurement was performed, and after further additional heating at 150°C for 5 minutes, the conductivity was measured again. Fig. 7 shows the results of the conductivity of the films of the compositions obtained by mixing the above compounds 1 and 4 with the hole-transporting organic compound 3, respectively. Fig. 8 shows the results of the conductivity of the films of the compositions obtained by mixing the above compounds 2 and 4 with the hole-transporting organic compound 4, respectively. From Figs. 7 and 8, it can be seen that the conductivity of the composition when using the compound 4 according to this embodiment is higher than the conductivity of the hole-transporting organic compounds when using the compounds 1 and 2 that are not the compounds according to this embodiment.

[0123] From the above examples, it can be seen that according to the present invention, it is possible to provide a compound capable of doping a hole-transporting compound at low temperature and with high efficiency, a film with high conductivity, and thus a photoelectric conversion device with high photoelectric efficiency.

Explanation of Reference Numerals

[0124] 1 Weather resistance protection film 2 UV cut film 3, 9 Gas barrier film 4, 8 Getter material film 5, 7 Sealing material 6 Solar cell element 10 Backsheet 12 Substrate 13 Solar cell module 14 Thin film solar cell 100 Photoelectric conversion element 101 Lower electrode 102 Buffer layer 103 Active layer 104 Buffer layer 105 Upper electrode 106 Substrate

Claims

1. A compound represented by the following formula (1). 【Chemical Formula 1】 (In formula (1), R １ , R ２ , and R ３ each independently represents a hydrogen atom, a halogen atom, an optionally substituted alkyl group having 1 to 20 carbon atoms, an optionally substituted alkenyl group having 2 to 20 carbon atoms, an optionally substituted alkynyl group having 2 to 20 carbon atoms, an optionally substituted alkoxy group having 1 to 20 carbon atoms, a cyano group, an amino group, a carboxyl group, an ester group, an alkylcarbonyl group, an acetyl group, a sulfonyl group, a silyl group, a boryl group, a nitrile group, a thio group, a seleno group, an optionally substituted aromatic hydrocarbon ring group, or an optionally substituted aromatic heterocyclic group, and R ４ each independently represents a halogen atom, an optionally substituted alkyl group having 1 to 20 carbon atoms, an optionally substituted alkenyl group having 2 to 20 carbon atoms, an optionally substituted alkynyl group having 2 to 20 carbon atoms, an optionally substituted alkoxy group having 1 to 20 carbon atoms, a cyano group, an amino group, an ester group, an alkylcarbonyl group, an acetyl group, a sulfonyl group, a silyl group, a boryl group, a nitrile group, a thio group, a seleno group, an optionally substituted aromatic hydrocarbon ring group, or an optionally substituted aromatic heterocyclic group, n is an integer from 0 to 5, and Ar represents an optionally substituted monovalent aromatic hydrocarbon ring group or an aromatic heterocyclic group.)

2. The compound according to Claim 1, wherein Ar is an aromatic hydrocarbon ring group substituted with a fluoro group or a fluoroalkyl group, or an aromatic heterocyclic group.

3. Said R １ is an alkyl group, R ２ and R ３ are hydrogen, and n is 0, the compound according to claim 1 or 2.

4. A composition comprising the compound according to any one of Claims 1 to 3 and a hole-transporting organic compound.

5. The composition according to Claim 4, wherein the HOMO of the hole-transporting organic compound is -5.7 eV or more and -5.0 eV or less.

6. A film produced using the composition according to Claim 4 or 5.

7. A photoelectric conversion element comprising at least a photoelectric conversion layer and a hole-transporting layer, wherein the hole-transporting layer is the film according to Claim 6.

8. A photoelectric conversion device comprising the photoelectric conversion element according to Claim 7.

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