CN111263982A

CN111263982A - Ink, ink cured film, and photoelectric conversion element

Info

Publication number: CN111263982A
Application number: CN201880068520.2A
Authority: CN
Inventors: 猪口大辅
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2017-10-23
Filing date: 2018-10-22
Publication date: 2020-06-09
Also published as: WO2019082844A1; JPWO2019082844A1; JP7129995B2

Abstract

It is required to improve the external quantum efficiency of the photoelectric conversion element. An ink comprising a p-type semiconductor material, an n-type semiconductor material, a 1 st solvent which is a nitrogen-containing heterocyclic compound, and a 2 nd solvent which is an aromatic hydrocarbon. In the photoelectric conversion element, the active layer is a cured film of ink.

Description

Ink, ink cured film, and photoelectric conversion element

Technical Field

The present invention relates to an ink, a cured film of the ink, and a photoelectric conversion element.

Background

Conventionally, a solar cell having an active layer containing a p-type semiconductor material and an n-type semiconductor material is known, and a technique of forming an active layer using an ink composition containing a combination of these semiconductor materials and a specific solvent is known (patent document 1).

Documents of the prior art

Patent document

Patent document 1: international publication No. 2016/076213

Disclosure of Invention

Problems to be solved by the invention

When the photoelectric conversion element is irradiated with light while a reverse bias voltage is applied, a photocurrent flows, and the photoelectric conversion element can function as a photodetection element. In order to improve the detection sensitivity of the photodetector, it is required to improve the external quantum efficiency of the photoelectric conversion element.

In addition, the photoelectric conversion element can function as a solar cell. The solar cell using natural energy does not consume resources such as fossil fuel and the like during power generation, and does not emit greenhouse gas. Therefore, solar cells are expected as power supply sources utilizing green energy, and improvement in performance is required. Therefore, when the photoelectric conversion element is caused to function as a solar cell, the photoelectric conversion element is also required to have a higher external quantum efficiency.

Means for solving the problems

As a result of intensive studies to solve the above problems, the present inventors have found that the external quantum efficiency of a photoelectric conversion element having an active layer formed thereon can be improved by using an ink containing a specific solvent, and have completed the present invention. Namely, the present invention provides the following.

[1] An ink comprising a p-type semiconductor material, an n-type semiconductor material, a 1 st solvent which is a nitrogen-containing heterocyclic compound, and a 2 nd solvent which is an aromatic hydrocarbon.

[2] The ink according to [1], wherein the n-type semiconductor material is a fullerene derivative.

[3] The ink according to [1] or [2], wherein the nitrogen-containing heterocyclic compound has a 6-membered ring structure, the 6-membered ring structure contains 1 or 2 heteroatoms, and the 1 or 2 heteroatoms are nitrogen atoms, respectively.

[4] The ink according to [3], wherein the 6-membered ring structure is a pyridine ring structure, a tetrahydropyridine ring structure, a piperidine ring structure or a pyrazine ring structure.

[5] The ink according to any one of [1] to [4], wherein the 1 st solvent is 1 or more selected from the group consisting of a substituted or unsubstituted quinoline, a substituted or unsubstituted 1,2,3, 4-tetrahydroquinoline, and a substituted or unsubstituted quinoxaline.

[6] The ink according to any one of [1] to [5], wherein a weight ratio of the 1 st solvent to the 2 nd solvent (1 st solvent/2 nd solvent) is from 1/99 to 20/80.

[7] The ink according to any one of [1] to [6], wherein the total weight percentage of the 1 st solvent and the 2 nd solvent in the ink is 95% by weight or more and 99% by weight or less.

[8] The ink according to any one of [1] to [7], wherein the ink is used for forming an active layer of a photoelectric conversion element.

[9] A cured film of the ink according to any one of [1] to [8 ].

[10] A photoelectric conversion element comprising a 1 st electrode, an active layer comprising a p-type semiconductor material and an n-type semiconductor material, and a 2 nd electrode in this order, wherein the active layer is the cured film described in [9 ].

[11] The photoelectric conversion element according to [10], wherein the photoelectric conversion element is a photodetection element.

[12] An image sensor comprising the photoelectric conversion element of [10] or [11 ].

[13] A fingerprint identification device comprising the photoelectric conversion element of [10] or [11 ].

[14] A method for producing a cured film, comprising the steps (i) and (ii), wherein in the step (i), the ink according to any one of [1] to [8] is applied to an object to be coated to obtain a coating film; in the step (ii), the solvent is removed from the obtained coating film.

[15] A method for manufacturing a photoelectric conversion element comprising a 1 st electrode, an active layer comprising a p-type semiconductor material and an n-type semiconductor material, and a 2 nd electrode in this order,

comprises a step of forming the active layer, the step of forming the active layer comprising a step (i) of applying the ink according to any one of [1] to [8] to an object to be coated to obtain a coating film, and a step (ii); in the step (ii), the solvent is removed from the obtained coating film.

ADVANTAGEOUS EFFECTS OF INVENTION

The invention can improve the external quantum efficiency of the photoelectric conversion element.

Drawings

Fig. 1 is a schematic diagram showing one embodiment of a photoelectric conversion element of the present invention.

Fig. 2 is a diagram schematically showing an example of the configuration of an image detection unit for a solid-state imaging device.

Fig. 3 is a diagram schematically showing an example of the configuration of the fingerprint detection unit integrally configured with the display device.

Detailed Description

The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples described below, and may be modified and implemented as desired without departing from the scope of the claims and their equivalents.

[1. description of common terms ]

In the present specification, the term "polymer compound" means a compound having a molecular weight distribution and a polystyrene-reduced number average molecular weight of 1X 10³ 1X 10 above⁸The following polymers. The total of the structural units contained in the polymer compound is 100 mol%.

In the present specification, the term "structural unit" means that 1 or more units are present in the polymer compound.

In the present specification, the "hydrogen atom" may be a light hydrogen atom or a heavy hydrogen atom.

In the present specification, "halogen atom" includes a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

In the present specification, unless otherwise specified, "alkyl" may be any of linear, branched, and cyclic. The number of carbon atoms of the linear alkyl group not including the substituent is usually 1 to 50, preferably 1 to 30, and more preferably 1 to 20. The number of carbon atoms of the branched or cyclic alkyl group not containing a substituent is usually 3 to 50, preferably 3 to 30, and more preferably 4 to 20.

The alkyl group may have a substituent. Specific examples of the alkyl group include: unsubstituted alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, 2-ethylbutyl, n-hexyl, cyclohexyl, n-heptyl, cyclohexylmethyl, cyclohexylethyl, n-octyl, 2-ethylhexyl, 3-n-propylheptyl, adamantyl, n-decyl, 3, 7-dimethyloctyl, 2-ethyloctyl, 2-n-hexyldecyl, n-dodecyl, tetradecyl, hexadecyl, octadecyl, and eicosyl; substituted alkyl groups such as trifluoromethyl, pentafluoroethyl, perfluorobutyl, perfluorohexyl, perfluorooctyl, 3-phenylpropyl, 3- (4-methylphenyl) propyl, 3- (3, 5-di-n-hexylphenyl) propyl, and 6-ethoxyhexyl.

The "aryl group" refers to an atomic group remaining after removing 1 hydrogen atom directly bonded to a carbon atom constituting a ring from an aromatic hydrocarbon having or not having a substituent.

The aryl group may have a substituent. Specific examples of the aryl group include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 1-anthryl group, a 2-anthryl group, a 9-anthryl group, a 1-pyrenyl group, a 2-pyrenyl group, a 4-pyrenyl group, a 2-fluorenyl group, a 3-fluorenyl group, a 4-fluorenyl group, a 2-phenylphenyl group, a 3-phenylphenyl group, a 4-phenylphenyl group, and groups in which a hydrogen atom in these groups is substituted with an alkyl group, an alkoxy group, an aryl group, a fluorine atom, or the like.

The "alkoxy group" may be linear, branched or cyclic. The number of carbon atoms of the linear alkoxy group not including the substituent is usually 1 to 40, preferably 1 to 10. The branched or cyclic alkoxy group has usually 3 to 40, preferably 4 to 10, carbon atoms not containing a substituent.

The alkoxy group may have a substituent. Specific examples of the alkoxy group include a methoxy group, an ethoxy group, a n-propoxy group, an isopropoxy group, a n-butoxy group, an isobutoxy group, a tert-butoxy group, a n-pentoxy group, a n-hexoxy group, a cyclohexyloxy group, a n-heptoxy group, a n-octoxy group, a 2-ethylhexoxy group, a n-nonyloxy group, a n-decyloxy group, a 3, 7-dimethyloctyloxy group and a lauryloxy group.

The number of carbon atoms of the "aryloxy group" which does not include a substituent is usually 6 to 60, preferably 6 to 48.

Aryloxy groups may or may not have substituents. Specific examples of the aryloxy group include a phenoxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, a 1-anthryloxy group, a 9-anthryloxy group, a 1-pyrenyloxy group, and groups in which a hydrogen atom is substituted with an alkyl group, an alkoxy group, a fluorine atom, or the like.

The "alkylthio group" may be linear, branched or cyclic. The number of carbon atoms of the linear alkylthio group not including a substituent is usually 1 to 40, preferably 1 to 10. The number of carbon atoms of the branched or cyclic alkylthio group not containing a substituent is usually 3 to 40, preferably 4 to 10.

Alkylthio groups have or have no substituents. Specific examples of the alkylthio group include a methylthio group, an ethylthio group, a propylthio group, an isopropylthio group, a butylthio group, an isobutylthio group, a tert-butylthio group, a pentylthio group, a hexylthio group, a cyclohexylthio group, a heptylthio group, an octylthio group, a 2-ethylhexylthio group, a nonylthio group, a decylthio group, a 3, 7-dimethyloctylthio group, a laurylthio group and a trifluoromethylthio group.

The number of carbon atoms of the "arylthio group" which does not include a substituent is usually 6 to 60, preferably 6 to 48.

The arylthio group may have a substituent. Examples of the arylthio group include phenylthio group, C1-C12 alkoxyphenylthio group (C1-C12 represent the following groups and have 1-12 carbon atoms), C1-C12 alkylphenylthio group, 1-naphthylthio group, 2-naphthylthio group and pentafluorophenylthio group.

The "p-valent heterocyclic group" (p represents an integer of 1 or more) means an atomic group remaining after p hydrogen atoms among hydrogen atoms directly bonded to carbon atoms or hetero atoms constituting a ring are removed from a heterocyclic compound having or not having a substituent. Among the p-valent heterocyclic groups, "p-valent aromatic heterocyclic groups" are preferred. The "p-valent aromatic heterocyclic group" refers to an atomic group remaining after p hydrogen atoms among hydrogen atoms directly bonded to carbon atoms or hetero atoms constituting a ring are removed from an aromatic heterocyclic compound having a substituent or not.

Examples of the substituent which the heterocyclic compound may have include a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a 1-valent heterocyclic group, a substituted amino group, an acyl group, an imine residue, an amide group, an imide group, a substituted oxycarbonyl group, an alkenyl group, an alkynyl group, a cyano group, and a nitro group.

The aromatic heterocyclic compound includes, in addition to a compound in which the heterocyclic ring itself exhibits aromaticity, a compound in which an aromatic ring is fused to the heterocyclic ring although the heterocyclic ring itself does not exhibit aromaticity.

Specific examples of the compound in which the heterocycle itself exhibits aromaticity among the aromatic heterocyclic compounds include oxadiazole, thiadiazole, thiazole, oxazole, thiophene, pyrrole, phosphole, furan, pyridine, pyrazine, pyrimidine, triazine, pyridazine, quinoline, isoquinoline, carbazole, and dibenzophosphole.

In the aromatic heterocyclic compound, specific examples of the compound in which the aromatic heterocycle itself does not exhibit aromaticity but an aromatic ring is fused to the heterocycle include phenoxazine, phenothiazine, dibenzoborole, dibenzosilole, and benzopyran.

The number of carbon atoms of the 1-valent heterocyclic group excluding the substituents is usually 2 to 60, preferably 4 to 20.

The 1-valent heterocyclic group may have a substituent, and specific examples of the 1-valent heterocyclic group include a thienyl group, a pyrrolyl group, a furyl group, a pyridyl group, a piperidyl group, a quinolyl group, an isoquinolyl group, a pyrimidyl group, a triazinyl group, and groups in which a hydrogen atom in these groups is substituted with an alkyl group, an alkoxy group, or the like.

"substituted amino" refers to an amino group having 2 substituents. Examples of the substituent group of the amino group include an alkyl group, an aryl group, and a 1-valent heterocyclic group, and an alkyl group, an aryl group, and a 1-valent heterocyclic group are preferable. The number of carbon atoms of the substituted amino group is usually 2 to 30.

Examples of the substituted amino group include dialkylamino groups such as dimethylamino group and diethylamino group; diarylamino groups such as diphenylamino group, bis (4-methylphenyl) amino group, bis (4-tert-butylphenyl) amino group, and bis (3, 5-di-tert-butylphenyl) amino group.

The "acyl group" usually has about 2 to 20 carbon atoms, preferably 2 to 18 carbon atoms. Specific examples of the acyl group include an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, a pivaloyl group, a benzoyl group, a trifluoroacetyl group, and a pentafluorobenzoyl group.

The "imine residue" refers to a residual atomic group obtained by removing 1 hydrogen atom directly bonded to a carbon atom or a nitrogen atom constituting a carbon-nitrogen atom double bond from an imine compound. The "imine compound" refers to an organic compound having a carbon-nitrogen double bond in the molecule. Examples of the imine compound include aldimines, ketimines, and compounds in which a hydrogen atom bonded to a nitrogen atom constituting a carbon atom-nitrogen atom double bond in aldimine is substituted with an alkyl group or the like.

The imine residue usually has about 2 to 20 carbon atoms, preferably 2 to 18 carbon atoms. Examples of the imine residue include groups represented by the following structural formulae.

[ solution 1]

The "amide group" refers to a residual atomic group obtained by removing 1 hydrogen atom bonded to a nitrogen atom from an amide. The carbon number of the amide group is usually about 1 to 20, preferably 1 to 18. Specific examples of the amide group include a carboxamide group, an acetamide group, a propionamide group, a butyrylamino group, a benzamide group, a trifluoroacetamide group, a pentafluorobenzamide group, a dimethylamide group, a diacetamide group, a dipropionamide group, a dibutyrylamino group, a dibenzoylamino group, a bis (trifluoroacetamide) and a bis (pentafluorobenzamide) group.

The "imide group" refers to an atomic group remaining after 1 hydrogen atom bonded to a nitrogen atom is removed from an imide. The number of carbon atoms of the imide group is usually about 4 to 20. Specific examples of the imide group include those shown below.

[ solution 2]

"substituted oxycarbonyl" refers to a group represented by R' -O- (C ═ O) -. Here, R' represents an alkyl group, an aryl group, an aralkyl group or a 1-valent heterocyclic group.

The number of carbon atoms of the substituted oxycarbonyl group is usually about 2 to 60, preferably 2 to 48.

Specific examples of the substituted oxycarbonyl group include a methoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, an isopropoxycarbonyl group, a butoxycarbonyl group, an isobutoxycarbonyl group, a tert-butoxycarbonyl group, a pentoxycarbonyl group, a hexyloxycarbonyl group, a cyclohexyloxycarbonyl group, a heptyloxycarbonyl group, an octyloxycarbonyl group, a 2-ethylhexyloxycarbonyl group, a nonyloxycarbonyl group, a decyloxycarbonyl group, a 3, 7-dimethyloctyloxycarbonyl group, a dodecyloxycarbonyl group, a trifluoromethoxy carbonyl group, a pentafluoroethoxycarbonyl group, a perfluorobutoxycarbonyl group, a perfluorohexyloxycarbonyl group, a perfluorooctyloxycarbonyl group, a phenoxycarbonyl group, a naphthyloxycarbonyl group and a pyridyloxycarbonyl group.

The "alkenyl group" may be linear, branched or cyclic. The number of carbon atoms of the linear alkenyl group not including the substituent is usually 2 to 30, preferably 3 to 20. The number of carbon atoms of the branched or cyclic alkenyl group not containing a substituent is usually 3 to 30, preferably 4 to 20.

The alkenyl group may have a substituent. Specific examples of the alkenyl group include a vinyl group, a 1-propenyl group, a 2-butenyl group, a 3-pentenyl group, a 4-pentenyl group, a 1-hexenyl group, a 5-hexenyl group, a 7-octenyl group, and groups obtained by substituting a hydrogen atom in these groups with an alkyl group, an alkoxy group, or the like.

The "alkynyl group" may be linear, branched or cyclic. The number of carbon atoms of the linear alkynyl group not containing a substituent is usually 2 to 20, preferably 3 to 20. The number of carbon atoms of the branched or cyclic alkynyl group which does not include a substituent is usually 4 to 30, preferably 4 to 20.

The alkynyl group may have a substituent. Specific examples of the alkynyl group include an ethynyl group, a 1-propynyl group, a 2-butynyl group, a 3-pentynyl group, a 4-pentynyl group, a 1-hexynyl group, a 5-hexynyl group, and groups in which a hydrogen atom in these groups is substituted with an alkyl group, an alkoxy group or the like.

In the present specification, the term "ink" refers to a liquid used in a coating method, and is not limited to a colored liquid. In addition, the term "coating method" includes a method of forming a film using a liquid substance, and examples thereof include a slit coating method, a blade coating method, a spin coating method, a casting method, a microgravure coating method, a gravure printing method, a bar coating method, a roll coating method, a wire bar coating method, a dip coating method, a spray coating method, a screen printing method, a gravure printing method, a flexographic printing method, an offset printing method, an inkjet coating method, a dispensing printing method, a nozzle coating method, and a capillary coating method.

The "ink" may be a solution, or may be a dispersion such as a dispersion, emulsion (emulsion), suspension (suspension), or the like.

[2. ink ]

The ink of the present invention includes a p-type semiconductor material, an n-type semiconductor material, a 1 st solvent, and a 2 nd solvent.

[ Components of ink ]

(1 st solvent)

The 1 st solvent is a nitrogen-containing heterocyclic compound. The ink of the present invention can improve the external quantum efficiency of a photoelectric conversion element by containing a nitrogen-containing heterocyclic compound as the 1 st solvent. The reason for this is assumed to be the following mechanism, but the present invention is not limited thereto.

It is considered that the nitrogen-containing heterocyclic compound as the 1 st solvent strongly interacts with an n-type semiconductor material such as a fullerene derivative by hydrogen bonding, dispersion force, or the like. When a coating film is formed from an ink and the solvent is removed from the coating film by drying or the like, it is considered that the n-type semiconductor material can easily move (migrate) in the coating film while the solvent is removed by a strong interaction between the nitrogen-containing heterocyclic compound and the n-type semiconductor material. As a result, it is considered that a network of an n-type semiconductor material functioning as a charge transfer path is sufficiently formed in a cured film obtained by removing the solvent from the coating film, and the external quantum efficiency is improved.

Examples of the nitrogen-containing heterocyclic compound include substituted or unsubstituted pyridine, substituted or unsubstituted quinoline, substituted or unsubstituted quinoxaline, substituted or unsubstituted 1,2,3, 4-tetrahydroquinoline, substituted or unsubstituted pyrimidine, substituted or unsubstituted pyrazine, and substituted or unsubstituted quinazoline. The 1 st solvent may be composed of 1 nitrogen-containing heterocyclic compound, or may be composed of 2 or more nitrogen-containing heterocyclic compounds. Preferably, the 1 st solvent is composed of 1 nitrogen-containing heterocyclic compound.

The nitrogen-containing heterocyclic compound may have a substituent on the ring structure.

Examples of the substituent which may be contained in the ring structure (e.g., quinoline ring structure, 1,2,3, 4-tetrahydroquinoline ring structure, quinoxaline ring structure) of the nitrogen-containing heterocyclic compound include an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a halogen group, and an alkylthio group.

The nitrogen-containing heterocyclic compound as the 1 st solvent is preferably: comprises a 6-membered ring structure, wherein the 6-membered ring structure comprises 1 or 2 heteroatoms, and the 1 or 2 heteroatoms are nitrogen atoms. Examples of the 6-membered ring structure containing 1 heteroatom and the 1 heteroatom being a nitrogen atom include a pyridine ring structure, a tetrahydropyridine ring structure and a piperidine ring structure. Examples of the 6-membered ring structure containing 2 heteroatoms, wherein the 2 heteroatoms are nitrogen atoms include a pyrazine ring structure and a pyrimidine ring structure.

Examples of the nitrogen-containing heterocyclic compound having a pyridine ring structure include substituted or unsubstituted pyridines, substituted or unsubstituted quinolines, and substituted or unsubstituted isoquinolines.

Examples of the nitrogen-containing cyclic compound having a tetrahydropyridine ring structure include 1,2,3, 4-tetrahydroquinoline having or not having a substituent, and 1,2,3, 4-tetrahydroisoquinoline having or not having a substituent.

Examples of the nitrogen-containing cyclic compound having a pyrazine ring structure include substituted or unsubstituted pyrazines and substituted or unsubstituted quinoxalines.

Examples of the nitrogen-containing cyclic compound having a pyrimidine ring structure include a pyrimidine having or not having a substituent, and a quinazoline having or not having a substituent.

The 1 st solvent is preferably a nitrogen-containing heterocyclic compound having a pyridine ring structure, a tetrahydropyridine ring structure, a piperidine ring structure or a pyrazine ring structure, more preferably a nitrogen-containing heterocyclic compound having a pyridine ring structure, a tetrahydropyridine ring structure or a pyrazine ring structure,

further preferably 1 or more selected from the group consisting of a substituted or unsubstituted quinoline, a substituted or unsubstituted 1,2,3, 4-tetrahydroquinoline, and a substituted or unsubstituted quinoxaline,

more preferably 1 or more selected from the group consisting of quinoline having an alkyl group, 1,2,3, 4-tetrahydroquinoline having an alkyl group, and quinoxaline having an alkyl group,

more preferably 1 or more selected from the group consisting of 2-methylquinoline, 3-methylquinoline, 6-methylquinoline, 8-methylquinoline, 1,2,3, 4-tetrahydroquinaldine and 2-methylquinoxaline.

In addition, in other modes, the 1 st solvent is preferably a substituted or unsubstituted quinoline, a substituted or unsubstituted 1,2,3, 4-tetrahydroquinoline, or a substituted or unsubstituted quinoxaline,

more preferably a quinoline having an alkyl group, a 1,2,3, 4-tetrahydroquinoline having an alkyl group or a quinoxaline having an alkyl group,

further preferred is 2-methylquinoline, 3-methylquinoline, 6-methylquinoline, 8-methylquinoline, 1,2,3, 4-tetrahydroquinaldine or 2-methylquinoxaline.

(the 2 nd solvent)

The 2 nd solvent is an aromatic hydrocarbon. As the 2 nd solvent, a solvent capable of dissolving the p-type semiconductor material is preferable.

Examples of the aromatic hydrocarbon include toluene, xylene (e.g., o-xylene, m-xylene, and p-xylene), trimethylbenzene (e.g., mesitylene, 1,2, 4-trimethylbenzene (pseudocumene)), butylbenzene (e.g., n-butylbenzene, sec-butylbenzene, and tert-butylbenzene), methylnaphthalene (e.g., 1-methylnaphthalene), tetrahydronaphthalene, and indane.

The 2 nd solvent may be composed of 1 kind of aromatic hydrocarbon, or may be composed of 2 or more kinds of aromatic hydrocarbons. Preferably, the 2 nd solvent is composed of 1 aromatic hydrocarbon.

The 2 nd solvent is preferably at least 1 selected from the group consisting of toluene, o-xylene, m-xylene, p-xylene, mesitylene, 1,2, 4-trimethylbenzene, n-butylbenzene, sec-butylbenzene, tert-butylbenzene, methylnaphthalene, tetrahydronaphthalene and indane,

more preferably toluene, o-xylene, m-xylene, p-xylene, mesitylene, 1,2, 4-trimethylbenzene, n-butylbenzene, sec-butylbenzene, tert-butylbenzene, methylnaphthalene, tetrahydronaphthalene or indane.

(combination of the 1 st solvent and the 2 nd solvent)

Examples of the combination of the 1 st solvent and the 2 nd solvent include combinations shown in the following tables.

[ Table 1]

1 st solvent	2 nd solvent
		2-methylquinoline	Toluene
2-methylquinoline	Ortho-xylene
		2-methylquinoline	Meta-xylene
2-methylquinoline	Para-xylene
		2-methylquinoline	Mesitylene
2-methylquinoline	Pseudocumene
		3-methylquinoline	Toluene
3-methylquinoline	Ortho-xylene
		3-methylquinoline	Meta-xylene
3-methylquinoline	Para-xylene
		3-methylquinoline	Mesitylene
3-methylquinoline	Pseudocumene
		6-methylquinoline	Toluene
6-methylquinoline	Ortho-xylene
		6-methylquinoline	Meta-xylene
6-methylquinoline	Para-xylene
		6-methylquinoline	Mesitylene
6-methylquinoline	Pseudocumene
		8-methylquinoline	Toluene
8-methylquinoline	Ortho-xylene
		8-methylquinoline	Meta-xylene
8-methylquinoline	Para-xylene
		8-methylquinoline	Mesitylene
8-methylquinoline	Pseudocumene
		1,2,3, 4-tetrahydroquinaldine	Toluene
1,2,3, 4-tetrahydroquinaldine	Ortho-xylene
		1,2,3, 4-tetrahydroquinaldine	Meta-xylene
1,2,3, 4-tetrahydroquinaldine	Para-xylene
		1,2,3, 4-tetrahydroquinaldine	Mesitylene
1,2,3, 4-tetrahydroquinaldine	Pseudocumene
		2-methylquinoxaline	Toluene
2-methylquinoxaline	Ortho-xylene
		2-methylquinoxaline	Meta-xylene
2-methylquinoxaline	Para-xylene
		2-methylquinoxaline	Mesitylene
2-methylquinoxaline	Pseudocumene

(weight ratio of the 1 st solvent to the 2 nd solvent)

From the viewpoint of improving the solubility of the p-type semiconductor material and the n-type semiconductor material, the weight ratio of the 1 st solvent to the 2 nd solvent (1 st solvent/2 nd solvent) is preferably 1/99 or more, more preferably 3/97 or more, further preferably 5/95 or more, preferably 20/80 or less, more preferably 15/85 or less, further preferably 10/90 or less, preferably 1/99 or more and 20/80 or less, more preferably 3/97 or more and 15/85 or less, and further preferably 5/95 or more and 10/90 or less.

(total weight percentage of the 1 st solvent and the 2 nd solvent in the ink)

From the viewpoint of improving the solubility of the p-type semiconductor material and the n-type semiconductor material, the total weight of the 1 st solvent and the 2 nd solvent contained in the ink is preferably 90% by weight or more, more preferably 92% by weight or more, and further preferably 95% by weight or more, based on 100% by weight of the total weight of the ink, and from the viewpoint of facilitating formation of a film having a thickness of a certain value or more, preferably 99% by weight or less, more preferably 98% by weight or less, and further preferably 97.5% by weight or less.

(optional solvent)

The ink may also contain optional solvents other than the 1 st and 2 nd solvents. The content of the optional solvent is preferably 5% by weight or less, more preferably 3% by weight or less, further preferably 1% by weight or less, and particularly preferably 0% by weight, based on 100% by weight of the total weight of all solvents contained in the ink.

(p-type semiconductor Material)

The p-type semiconductor material may be a low molecular compound or a high molecular compound.

Examples of the p-type semiconductor material as the low molecular compound include phthalocyanine, metal phthalocyanine, porphyrin, metal porphyrin, oligothiophene, tetracene, pentacene, and rubrene.

Examples of the p-type semiconductor material as the polymer compound include polyvinylcarbazole and derivatives thereof, polysilane and derivatives thereof, polysiloxane derivatives having an aromatic amine structure in a side chain or a main chain, polyaniline and derivatives thereof, polythiophene and derivatives thereof, polypyrrole and derivatives thereof, polyphenylenevinylene and derivatives thereof, polythienylenevinylene and derivatives thereof, polyfluorene and derivatives thereof, and the like.

The p-type semiconductor material is preferably a polymer compound in view of excellent stability of the ink; the p-type semiconductor material is more preferably a polymer compound containing a structural unit represented by the following formula (I) and/or a structural unit represented by the following formula (II) in order to improve the external quantum efficiency of the photoelectric conversion element.

[ solution 3]

In the formula (I), Ar¹And Ar²Represents a 3-valent aromatic heterocyclic group, and Z represents a group represented by any one of the following formulae (Z-1) to (Z-7).

[ solution 4]

-Ar³-

(II)

In the formula (II), Ar³Represents a 2-valent aromatic heterocyclic group.

[ solution 5]

In the formulae (Z-1) to (Z-7), R represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a 1-valent heterocyclic group, a substituted amino group, an acyl group, an imine residue, an amide group, an imide group, a substituted oxycarbonyl group, an alkenyl group, an alkynyl group, a cyano group or a nitro group. When 2R's are present in each of the formulae (Z-1) to (Z-7), the 2R's may be the same or different from each other.

The structural unit represented by the formula (I) is preferably a structural unit represented by the following formula (I-1).

[ solution 6]

In the formula (I-1), Z has the same meaning as described above.

Examples of the structural unit represented by formula (I-1) include structural units represented by the following formulae (501) to (505).

[ solution 7]

In the formulae (501) to (505), R represents the same meaning as described above. When 2R's are present, the 2R's may be the same or different from each other.

Ar³The 2-valent aromatic heterocyclic group has 2 to 60 carbon atoms, preferably 4 to 60 carbon atoms, and more preferably 4 to 20 carbon atoms. Ar (Ar)³The 2-valent aromatic heterocyclic group may have a substituent. As Ar³Examples of the substituent which the 2-valent aromatic heterocyclic group may have include a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a 1-valent heterocyclic group, a substituted amino group, an acyl group, an imine residue, an amide group, an imide group, a substituted oxycarbonyl group, an alkenyl group, an alkynyl group, a cyano group, and a nitro group.

As Ar³Examples of the 2-valent aromatic heterocyclic group include groups represented by the following formulae (101) to (185).

[ solution 8]

[ solution 9]

[ solution 10]

[ solution 11]

In the formulae (101) to (185), R represents the same meaning as described above. When 2 or more R exist, 2 or more R may be the same or different from each other.

As the structural unit represented by the above formula (II), structural units represented by the following formulae (II-1) to (II-6) are preferable.

[ solution 12]

In the formulae (II-1) to (II-6), X¹And X²Each independently represents an oxygen atom or a sulfur atom, and R represents the same meaning as described above. When 2 or more R exist, 2 or more R may be the same or different from each other.

X in the formulae (II-1) to (II-6) for the reason that the starting compounds are readily available¹And X²Preferably both are sulfur atoms.

The polymer compound as the p-type semiconductor material may contain 2 or more kinds of the structural unit of formula (I) and may also contain 2 or more kinds of the structural unit of formula (II).

The polymer compound as the p-type semiconductor material may contain a structural unit represented by the following formula (III) in order to improve solubility in a solvent.

[ solution 13]

-Ar⁴-

(III)

In the formula (III)，Ar⁴Represents an arylene group.

Ar⁴The arylene group means an atomic group remaining after 2 hydrogen atoms are removed from an aromatic hydrocarbon having or not having a substituent. The aromatic hydrocarbon also includes compounds having condensed rings, and compounds in which 2 or more members selected from the group consisting of independent benzene rings and condensed rings are bonded directly or via a 2-valent group such as a vinylene group.

Examples of the substituent that may be contained in the aromatic hydrocarbon include the same substituents as those listed above as the substituents that may be contained in the heterocyclic compound.

The number of carbon atoms of the arylene group excluding the substituent is usually 6 to 60, preferably 6 to 20. The number of carbon atoms of the arylene group including the substituent is usually about 6 to 100.

Examples of the arylene group include a phenylene group (for example, the following formulas 1 to 3), a naphthalenediyl group (for example, the following formulas 4 to 13), an anthracenediyl group (for example, the following formulas 14 to 19), a biphenyldiyl group (for example, the following formulas 20 to 25), a terphenyldiyl group (for example, the following formulas 26 to 28), a condensed cyclic compound group (for example, the following formulas 29 to 35), a fluorenediyl group (for example, the following formulas 36 to 38), and a benzofluorenediyl group (for example, the following formulas 39 to 46).

[ solution 14]

[ solution 15]

[ solution 17]

[ solution 18]

[ solution 19]

[ solution 20]

[ solution 21]

When the polymer compound as the p-type semiconductor material contains the structural unit represented by formula (I) and/or the structural unit represented by formula (II), the total amount of the structural unit represented by formula (I) and the structural unit represented by formula (II) is usually 20 to 100 mol% and preferably 40 to 100 mol%, more preferably 50 to 100 mol%, from the viewpoint of improving the charge transport property as the p-type semiconductor material, assuming that the amount of all the structural units contained in the polymer compound is 100 mol%.

Specific examples of the polymer compound as the p-type semiconductor material include polymer compounds represented by the following formula.

[ solution 22]

[ solution 23]

The polymer compound as a p-type semiconductor material has a polystyrene-equivalent weight-average molecular weight of usually 1X 10³～1×10⁸From the viewpoint of improving solubility in a solvent, 1 × 10 is preferable³～1×10⁶。

The ink may contain only 1 type of p-type semiconductor material, or may contain 2 or more types of p-type semiconductor materials in combination at an arbitrary ratio.

(n-type semiconductor Material)

The n-type semiconductor material may be a low molecular compound or a high molecular compound.

Examples of the n-type semiconductor material (electron-accepting compound) as the low-molecular compound include oxadiazole derivatives, anthraquinone dimethane and its derivatives, benzoquinone and its derivatives, naphthoquinone and its derivatives, anthraquinone and its derivatives, tetracyanoanthraquinone dimethane and its derivatives, fluorenone derivatives, diphenyldicyanoethylene and its derivatives, diphenoquinone derivatives, metal complexes of 8-hydroxyquinoline and its derivatives, and C₆₀Fullerenes such as fullerene and derivatives thereof, and phenanthrene derivatives such as bathocuproine.

Examples of the n-type semiconductor material (electron accepting compound) as the polymer compound include polyvinylcarbazole and derivatives thereof, polysilane and derivatives thereof, polysiloxane derivatives having an aromatic amine structure in a side chain or a main chain, polyaniline and derivatives thereof, polythiophene and derivatives thereof, polypyrrole and derivatives thereof, polyphenylenevinylene and derivatives thereof, polythienylenevinylene and derivatives thereof, polyquinoline and derivatives thereof, polyquinoxaline and derivatives thereof, and polyfluorene and derivatives thereof.

The n-type semiconductor material is preferably at least 1 kind selected from the group consisting of fullerene and fullerene derivatives, and more preferably a fullerene derivative.

As an example of fullerene, C may be mentioned₆₀Fullerene, C₇₀Fullerene, C₇₆Fullerene, C₇₈Fullerene and C₈₄A fullerene. Examples of the fullerene derivative include derivatives of these fullerenes. The fullerene derivative is a compound in which at least a part of fullerene is modified.

Examples of the fullerene derivative include compounds represented by the following formulae (N-1) to (N-4).

[ solution 24]

In the formulae (N-1) to (N-4),

R^arepresents an alkyl group, an aryl group, a 1-valent heterocyclic group or a group having an ester structure. There being more than 2R^aMay be the same or different from each other.

R^bRepresents an alkyl group or an aryl group. There being more than 2R^bMay be the same or different from each other.

As R^aExamples of the group having an ester structure include a group represented by the following formula (19).

[ solution 25]

In the formula (19), u1 represents an integer of 1 to 6. u2 represents an integer of 0 to 6. R^cRepresents an alkyl group, an aryl group or a 1-valent heterocyclic group.

As C₆₀Examples of the fullerene derivative include the following compounds.

[ solution 26]

As C₇₀Examples of the fullerene derivative include the following compounds.

[ solution 27]

Specific examples of the fullerene derivative include [6,6] -Phenyl-C61-butyric acid methyl ester (C60PCBM, [6,6] -Phenyl C61 butyric acid methyl ester), [6,6] -Phenyl-C71-butyric acid methyl ester (C70PCBM, [6,6] -Phenyl C71 butyric acid methyl ester), [6,6] -Phenyl-C85-butyric acid methyl ester (C84PCBM, [6,6] -Phenyl-C85 butyric acid methyl ester), and [6,6] -Thienyl-C61-butyric acid methyl ester ([6,6] -Thienyl C61 butyric acid methyl ester).

The ink may contain only 1 type of n-type semiconductor material, or may contain 2 or more types of n-type semiconductor materials in combination at an arbitrary ratio.

(composition ratio of p-type semiconductor material to n-type semiconductor material)

The weight ratio of the p-type semiconductor material to the n-type semiconductor material in the ink (p-type semiconductor material: n-type semiconductor material) is preferably 1:9 to 9:1, more preferably 1:9 to 2:1, further preferably 1:9 to 1:1, and particularly preferably 1:5 to 1: 1.

(optional ingredients)

In addition to the 1 st solvent, the 2 nd solvent, the p-type semiconductor material, and the n-type semiconductor material, the ink may contain optional components within limits that do not inhibit the effects of the present invention.

Examples of the optional components include solvents other than the 1 st solvent and the 2 nd solvent, propiophenone, methyl benzoate, ethyl benzoate, and benzyl benzoate.

(concentration of p-type semiconductor material and n-type semiconductor material in ink)

The total concentration of the p-type semiconductor material and the n-type semiconductor material in the ink is preferably 0.01 wt% to 20 wt%, more preferably 0.01 wt% to 10 wt%, further preferably 0.01 wt% to 5 wt%, and particularly preferably 0.1 wt% to 5 wt%. In the ink, the p-type semiconductor material and the n-type semiconductor material may be dissolved or dispersed, preferably at least partially dissolved, and more preferably completely dissolved.

[ method for producing ink ]

The ink can be produced by a known method. For example, it can be produced by the following method: a method of preparing a mixed solvent by mixing the 1 st solvent and the 2 nd solvent, and adding a p-type semiconductor material and an n-type semiconductor material to the mixed solvent; a method of adding a p-type semiconductor material to a 1 st solvent, adding an n-type semiconductor material to a 2 nd solvent, and then mixing the 1 st solvent and the 2 nd solvent to which each material is added; and so on.

The 1 st and 2 nd solvents and the p-type and n-type semiconductor materials may be mixed by heating to a temperature below the boiling point of the solvents.

After mixing the 1 st and 2 nd solvents and the p-type semiconductor material and the n-type semiconductor material, the resulting composition may be filtered using a filter, and the filtrate may be used as an ink. As the filter, for example, a filter made of a fluororesin such as Polytetrafluoroethylene (PTFE) can be used.

[ use of ink ]

The use of the ink of the present invention is arbitrary. The ink of the present invention can be used to form a film containing a p-type semiconductor material and an n-type semiconductor material.

The ink of the present invention is suitably used for forming an active layer included in a photoelectric conversion element. In particular, a photodetector including an active layer formed using the ink of the present invention has an improved EQE when a reverse bias voltage is applied. Therefore, the ink of the present invention is particularly suitable for forming an active layer included in a photodetector.

[3. cured film of ink ]

After the film is formed with the ink, the solvent is removed from the film to cure the film, and at this time, a cured film of the ink is obtained.

The size of the cured film of the ink, such as the thickness, is not particularly limited.

The cured film of the ink is suitably used for the applications described as the applications of the ink.

[4. method for producing cured film of ink ]

The cured film of the ink can be produced by any production method. One embodiment of the method for producing a cured film of ink includes a step (i) of applying ink to an object to be coated to obtain a coating film, and a step (ii) of removing a solvent from the obtained coating film.

[ Process (i) ]

As a method of applying the ink to the object to be coated, any coating method can be used. The coating method is preferably a slit coating method, a doctor blade coating method, a spin coating method, a micro-gravure coating method, a gravure printing method, a bar coating method, an inkjet coating method, a nozzle coating method, or a capillary coating method, more preferably a slit coating method, a spin coating method, a capillary coating method, or a bar coating method, and still more preferably a slit coating method or a spin coating method.

The ink is applied to an arbitrary application object. For example, the ink may be applied to a functional layer of a photoelectric conversion element such as an electrode (anode or cathode), an electron transport layer, or a hole transport layer in a process for manufacturing the photoelectric conversion element.

[ Process (ii) ]

As a method for removing the solvent from the coating film, any method can be used. Examples of the method for removing the solvent include a hot air drying method, an infrared heating drying method, a flash lamp annealing drying method, a reduced pressure drying method, and the like.

[5. photoelectric conversion element ]

The photoelectric conversion element of the present invention includes a 1 st electrode, an active layer including a p-type semiconductor material and an n-type semiconductor material, and a 2 nd electrode in this order, and the active layer is a cured film of ink.

[ elements of photoelectric conversion element ]

(active layer)

The active layer includes a p-type semiconductor material and an n-type semiconductor material. The active layer is a cured film of the ink. Examples and preferred examples of the p-type semiconductor material, the n-type semiconductor material, and the ink are the same as those described in the above item [2. ink ].

In the photoelectric conversion element, EQE is improved by forming the active layer as a cured film of the ink. In particular, EQE when a reverse bias voltage is applied to the photoelectric conversion element is improved. Therefore, the photoelectric conversion element of the present invention is suitable as a photodetection element.

The photoelectric conversion element may have 2 or more active layers.

(electrode)

At least either of the 1 st electrode and the 2 nd electrode is preferably a transparent or translucent electrode. In the case where the substrate is opaque, it is preferable that the electrode farther from the substrate among the 1 st electrode and the 2 nd electrode is transparent or translucent.

Examples of the transparent or translucent electrode include a conductive metal oxide film, a translucent metal thin film, and the like. Specific examples of the transparent or translucent electrode material include indium oxide, zinc oxide, tin oxide, and a composite thereof (e.g., Indium Tin Oxide (ITO) and indium zinc oxide), NESA, gold, platinum, silver, and copper. Among them, as the transparent or translucent electrode material, 1 or more selected from ITO, indium zinc oxide, and tin oxide is preferable.

Examples of the method for producing the electrode include a vacuum deposition method, a sputtering method, an ion plating method, and a plating method.

As the transparent or translucent electrode, a transparent conductive film made of an organic compound such as polyaniline and a derivative thereof, polythiophene and a derivative thereof, or the like can be used.

One of the 1 st electrode and the 2 nd electrode may be an electrode having low light transmittance. Examples of the material of the electrode having low light transmittance include a metal and a conductive polymer. Specific examples of the electrode material include metals such as lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, and ytterbium; and alloys of 2 or more of these metals; an alloy of 1 or more of the above metals with 1 or more metals selected from the group consisting of gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, and tin; graphite; a graphite intercalation compound; polyaniline and derivatives thereof; polythiophenes and derivatives thereof.

More specifically, examples of the alloy include a magnesium-silver alloy, a magnesium-indium alloy, a magnesium-aluminum alloy, an indium-silver alloy, a lithium-aluminum alloy, a lithium-magnesium alloy, a lithium-indium alloy, and a calcium-aluminum alloy.

[ optional elements ]

The photoelectric conversion element may include elements other than the 1 st electrode, the active layer, and the 2 nd electrode. Examples of the optional elements include a substrate, a hole transport layer, an electron transport layer, and a sealing layer.

(substrate)

The photoelectric conversion element is generally formed on a substrate (support substrate). The substrate is preferably made of a material that does not chemically change when forming an electrode or forming an organic layer. Examples of the material of the substrate include glass, plastic, polymer film, and silicon.

The substrate may be low in light transmittance, but in the photoelectric conversion element, in the case where light is absorbed from the substrate, for example, the substrate is preferably transparent or translucent. When a photoelectric conversion element is formed on a substrate having low light transmittance, light cannot be absorbed from the electrode side closer to the substrate, and therefore, it is preferable to use a transparent or semitransparent electrode as the electrode farther from the substrate. By using a transparent or translucent electrode as the electrode far from the substrate, light can be absorbed from the electrode far from the substrate even if a substrate having low light transmittance is used.

(hole transport layer)

The photoelectric conversion element may be provided with a hole transport layer between an electrode as an anode and an active layer. The hole transport layer has a function of transporting holes from the active layer to the electrode.

The hole transport layer provided in contact with the electrode is sometimes referred to as a hole injection layer in particular. The hole transport layer (hole injection layer) provided in contact with the electrode has a function of promoting injection of holes into the electrode. The hole transport layer (hole injection layer) may be in contact with the active layer.

The hole transport layer contains a hole transporting material. Examples of the hole-transporting material include polythiophene and a derivative thereof, an aromatic amine compound, a polymer compound including a structural unit having an aromatic amine residue, CuSCN, CuI, NiO, and molybdenum oxide (MoOx).

(Electron transport layer)

The photoelectric conversion element may be provided with an electron transport layer between an electrode as a cathode and an active layer. The electron transport layer has a function of transporting electrons from the active layer to the electrode. The electron transport layer may be contiguous with the electrode. The electron transport layer may also be contiguous with the active layer.

The electron transport layer includes an electron transport material. Examples of the electron transporting material include nanoparticles of zinc oxide, nanoparticles of gallium-doped zinc oxide, nanoparticles of aluminum-doped zinc oxide, polyethyleneimine, ethoxylated polyethyleneimine, and PFN-P2.

(sealing layer)

The photoelectric conversion element may include an encapsulation layer. The sealing layer is provided, for example, on the electrode side remote from the substrate. The sealing layer may be formed of a material having a property of blocking moisture (water vapor barrier property) or a property of blocking oxygen (oxygen barrier property).

An embodiment of a photoelectric conversion element according to the present invention will be described below with reference to the drawings.

The photoelectric conversion element 10 of the present embodiment is provided on a support substrate 11, and includes a 1 st electrode 12 as an anode, a hole transport layer 13, an active layer 14, an electron transport layer 15, and a 2 nd electrode 16 in this order. The 1 st electrode 12 is provided so as to be in contact with 1 of the 2 principal surfaces of the support substrate 10. The hole transport layer 13 is provided so as to contact the 1 st electrode 12. The active layer 14 is provided in contact with the hole transport layer 13. The electron transport layer 15 is provided so as to be in contact with the active layer 14. The 2 nd electrode 16 as a cathode is provided so as to be in contact with the electron transport layer 15. The material constituting the support substrate 11 and the materials constituting the elements (the 1 st electrode 12, the hole transport layer 13, the active layer 14, the electron transport layer 15, and the 2 nd electrode 16) included in the photoelectric conversion element 10 may be exemplified as the materials constituting the elements.

The photoelectric conversion element of the present invention can be manufactured by any method. The photoelectric conversion element of the present invention can be produced by a method including the method for producing a cured film of ink described in the above item [4. Specifically, for example, the photoelectric conversion element of the present invention can be manufactured by a method including the steps (i) and (ii).

[ use of photoelectric conversion element ]

The photoelectric conversion element of the present invention can generate photoelectromotive force between electrodes by irradiating light such as sunlight, and can operate as a solar cell. In addition, a plurality of solar cells may be integrated and used as a thin film solar cell module.

In the photoelectric conversion element of the present invention, a transparent or translucent electrode is irradiated with light in a state where a voltage is applied between the electrodes, so that a photocurrent can flow therethrough and the photoelectric conversion element can operate as a photosensor (light detection element). It is also possible to use a plurality of photosensors as image sensors by integrating them.

(application example of photoelectric conversion element)

The photoelectric conversion element according to the embodiment of the present invention described above can be suitably used in a detection unit provided in various electronic devices such as a workstation, a personal computer, a portable information terminal, an entrance/exit management system, a digital camera, and medical equipment.

The photoelectric conversion element (light detection element) of the present invention can be suitably applied to, for example, an image detection unit (image sensor) for a solid-state imaging device such as an X-ray imaging device and a CMOS image sensor, a fingerprint detection unit, a face detection unit, a vein detection unit, and an iris detection unit, which are provided in the above-described exemplary electronic device, a detection unit for detecting a partially specific feature of a living body, a detection unit for an optical biosensor such as a pulse oximeter, and the like.

Hereinafter, description will be given of configuration examples of an image detection unit for a solid-state imaging device and a fingerprint detection unit for a biometric information authentication device (fingerprint recognition device) among detection units to which photoelectric conversion elements according to embodiments of the present invention can be suitably applied, with reference to the drawings.

(image detection section)

The image detection unit 1 includes: a CMOS transistor substrate 20; an interlayer insulating film 30 provided so as to cover the CMOS transistor substrate 20; a photoelectric conversion element 10 according to an embodiment of the present invention provided on the interlayer insulating film 30; an interlayer wiring section 32 provided so as to penetrate the interlayer insulating film 30 and electrically connecting the CMOS transistor substrate 20 and the photoelectric conversion element 10; a sealing layer 40 provided so as to cover the photoelectric conversion element 10; and a color filter 50 disposed on the sealing layer.

The CMOS transistor substrate 20 has any suitable structure known in the art in accordance with the design.

The CMOS transistor substrate 20 includes transistors, capacitors, and the like formed in the thickness of the substrate, and includes functional elements such as a CMOS transistor circuit (MOS transistor circuit) for realizing various functions.

Examples of the functional element include a floating diffusion element, a reset transistor, an output transistor, and a selection transistor.

A signal readout circuit and the like are formed on the CMOS transistor substrate 20 by using such functional elements, wirings, and the like.

The interlayer insulating film 30 may be made of any appropriate insulating material known in the art, such as silicon oxide and insulating resin. The interlayer wiring portion 32 may be formed of any appropriate conductive material (wiring material) known in the art, such as copper or tungsten. The interlayer wiring portion 32 may be, for example, a via wiring formed simultaneously with the formation of the wiring layer, or may be a buried plug formed separately from the wiring layer.

The sealing layer 40 may be made of any suitable material known in the art, provided that it is possible to prevent or suppress permeation of harmful substances such as oxygen and water that may deteriorate the function of the photoelectric conversion element 10.

As the color filter 50, for example, a primary color filter made of any suitable material known in the art and corresponding to the design of the image detection unit 1 can be used. As the color filter 50, a complementary color filter that can be thinner than the primary color filter can be used. As the complementary color filter, for example, a color filter in which three types (yellow, cyan, magenta), (yellow, cyan, transparent), (yellow, transparent, magenta), and three types (transparent, cyan, magenta) are combined can be used. They may be configured in any suitable configuration corresponding to the design of the photoelectric conversion element 10 and the CMOS transistor substrate 20, provided that color image data can be generated.

The light received by the photoelectric conversion element 10 via the color filter 50 is converted by the photoelectric conversion element 10 into an electrical signal corresponding to the amount of received light, and the electrical signal is output to the outside of the photoelectric conversion element 10 via the electrodes in the form of a received light signal, i.e., an electrical signal corresponding to the subject.

Next, the received light signal output from the photoelectric conversion element 10 is input to the CMOS transistor substrate 20 through the interlayer wiring portion 32, read by a signal reading circuit formed on the CMOS transistor substrate 20, and subjected to signal processing by another arbitrary conventionally known functional portion, not shown, to generate image information based on the imaging target.

(fingerprint detection section)

The display device 2 of the portable information terminal includes: a fingerprint detection section 100 including the photoelectric conversion element 10 of the embodiment of the present invention as a main component; and a display panel unit 200 provided on the fingerprint detection unit 100 and displaying a predetermined image.

In this configuration example, the fingerprint detection unit 100 is provided in a region substantially matching the display region 200a of the display panel unit 200. In other words, the display panel section 200 is integrally laminated above the fingerprint detection section 100.

When fingerprint detection is performed only in a partial area of the display area 200a, the fingerprint detection unit 100 may be provided corresponding to the partial area.

The fingerprint detection section 100 includes the photoelectric conversion element 10 according to the embodiment of the present invention as a functional section that exerts a substantial function. The fingerprint detection unit 100 may include any suitable conventionally known components such as a protection film (protection film), a support substrate, a sealing member, a barrier film, a bandpass filter, and an infrared cut film (not shown) so as to correspond to a design for obtaining desired characteristics. The fingerprint detection unit 100 may have the configuration of the image detection unit described above.

The photoelectric conversion element 10 may be included in the display region 200a in any manner. For example, 2 or more photoelectric conversion elements 10 may be arranged in a matrix.

As described above, the photoelectric conversion element 10 is provided on the support substrate 11 or the sealing substrate, and the support substrate 11 is provided with electrodes (anodes or cathodes) in a matrix form, for example.

The light received by the photoelectric conversion element 10 is converted into an electric signal according to the amount of received light by the photoelectric conversion element 10, and is output to the outside of the photoelectric conversion element 10 via the electrodes in the form of a received light signal, that is, an electric signal corresponding to a photographed fingerprint.

In this configuration example, the display panel section 200 is configured as an organic electroluminescence display panel (organic EL display panel) including a touch sensor panel. Instead of the organic EL display panel, the display panel section 200 may be formed of a display panel having any suitable conventionally known configuration, such as a liquid crystal display panel including a light source such as a backlight.

The display panel section 200 is provided on the fingerprint detection section 100 described above. The display panel section 200 includes an organic electroluminescent element (organic EL element) 220 as a functional section that exerts a substantial function. The display panel section 200 may further include any suitable conventionally known substrate such as a conventionally known glass substrate (the support substrate 210 or the seal substrate 240), a seal member, a barrier film, a polarizing plate such as a circularly polarizing plate, and any suitable conventionally known member such as the touch sensor panel 230 so as to correspond to desired characteristics.

In the configuration example described above, the organic EL element 220 is used as a light source for the pixels in the display area 200a, and is also used as a light source for fingerprint shooting in the fingerprint detection section 100.

Here, the operation of the fingerprint detection unit 100 will be briefly described.

In performing fingerprint recognition, the fingerprint detection section 100 detects a fingerprint using light emitted from the organic EL element 220 of the display panel section 200. Specifically, the light emitted from the organic EL element 220 is transmitted through the constituent elements present between the organic EL element 220 and the photoelectric conversion element 10 of the fingerprint detection section 100, and is reflected by the skin (finger surface) of the fingertip of the finger placed in contact with the surface of the display panel section 200 in the display region 200 a. At least a part of the light reflected by the finger surface is transmitted through the constituent elements present therebetween to be received by the photoelectric conversion element 10, and is converted into an electric signal according to the received light amount of the photoelectric conversion element 10. Then, image information related to the fingerprint of the finger surface is constructed from the converted electric signals.

The portable information terminal provided with the display device 2 performs fingerprint recognition by comparing the obtained image information with the fingerprint data for fingerprint recognition recorded in advance by any appropriate procedure known in the art.

[6. method for producing photoelectric conversion element ]

The method for manufacturing a photoelectric conversion element of the present invention is a method for manufacturing a photoelectric conversion element including a 1 st electrode, an active layer including a p-type semiconductor material and an n-type semiconductor material, and a 2 nd electrode in this order, the method including a step of forming the active layer, the step of forming the active layer including a step (i) and a step (ii), the step (i) including applying the ink to an object to be coated to obtain a coating film; in the step (ii), the solvent is removed from the obtained coating film.

In the method for manufacturing a photoelectric conversion element according to the present invention, the step of forming the active layer preferably includes the step (i) and the step (ii) in this order.

Examples and preferred examples of the p-type semiconductor material, the n-type semiconductor material, and the ink are the same as those described in the above item [2. ink ].

As a method of applying the ink to the object to be coated, any coating method can be used. The preferable coating method, the more preferable coating method, and the even more preferable coating method include the same methods as those described in the above item [4. method for producing cured film of ink ] [ step (i) ].

As a method for removing the solvent from the obtained coating film, any method can be used. Examples of the method for removing the solvent include the same methods as those described in the above item [4. method for producing cured film of ink ] [ step (ii) ].

The step of forming the active layer may include an optional step in addition to the steps (ii) and (ii).

The ink is coated on the layer on which the active layer is to be formed. Therefore, the object to which the ink is applied differs depending on the layer structure of the photoelectric conversion element to be manufactured and the order of lamination. For example, when the photoelectric conversion element has a layer structure of substrate/anode/hole transport layer/active layer/electron transport layer/cathode and is laminated in the order of the elements described above, the object to which the ink is applied is usually the hole transport layer. For example, when the photoelectric conversion element has a layer structure of substrate/cathode/electron transport layer/active layer/hole transport layer/anode and is laminated in the order of the elements described above, the object to which the ink is applied is usually the electron transport layer.

The method for manufacturing a photoelectric conversion element according to one embodiment may be a method for manufacturing a photoelectric conversion element having 2 or more active layers, or may be a method for repeating the step (i) and the step (ii) a plurality of times.

The method for manufacturing a photoelectric conversion element can improve the EQE of the photoelectric conversion element. In particular, EQE when a reverse bias voltage is applied to the photoelectric conversion element can be increased. Therefore, the method for manufacturing a photoelectric conversion element of the present invention is suitable as a method for manufacturing a photodetector.

Examples

Hereinafter, examples are shown to explain the present invention in further detail. The present invention is not limited to the embodiments described below.

[ evaluation method ]

(method for measuring External Quantum Efficiency (EQE))

A photoelectric conversion element was irradiated with a constant number of photons (1.0X 10) per 10nm in a wavelength range of 300nm to 1200nm using a solar simulator (product name: CEP-2000 model, manufactured by spectrometer) in a state where a reverse bias voltage of 3V was applied to the photoelectric conversion element¹⁶) Measuring the current value of the generated current, and determining the wave by a known methodEQE spectra 300nm to 1200nm long.

[ semiconductor materials used in examples ]

In this example, p-type semiconductor materials and n-type semiconductor materials described in the following table were used.

[ Table 2]

[ Table 3]

As the material P-1, a material synthesized by the method described in reference WO2013/051676 was used.

As the material P-2, a trade name manufactured by 1-material company: PCE 10.

As the material P-3, a trade name manufactured by 1-material company: PDTSTPD.

As material P-4, a trade name manufactured by Lumtec corporation was used: PDPP 3T.

As the material P-5, a material synthesized by the method described in Japanese patent application laid-open No. 2010-74127 is used.

As the material P-6, a material synthesized by the method described in reference WO2011/052709 was used.

As the material N-1, a trade name manufactured by Frontier Carbon corporation: E100.

as the material N-2, a trade name manufactured by American Dye Source was used: ADS71 BFA.

The solvents used in the present example and their boiling points (bp) are shown in the following table.

[ Table 4]

Name of solvent	bp(℃)
		Mesitylene	165
Pseudocumene	169
		Ortho-dichlorobenzene	180
Propiophenone	208
		2-methylquinoline	250
3-methylquinoline	255
		6-methylquinoline	259
8-methylquinoline	248
		1,2,3, 4-tetrahydroquinaldine	250
2-methylquinoxaline	245

< example 1>

[ preparation of ink ]

A mixed solvent was prepared by using 2-methylquinoline as the 1 st solvent and pseudocumene as the 2 nd solvent in a weight ratio of the 1 st solvent to the 2 nd solvent of 10: 90. The P-type semiconductor material P-1 and the N-type semiconductor material N-1 were mixed in the above-mentioned mixed solvent in an amount of 2 wt% based on the total weight of the composition and 3 wt% based on the total weight of the composition, and the mixture was stirred at 80 ℃ for 12 hours and then filtered through a PTFE filter having a pore size of 5 μm to obtain composition (I-1) as an ink.

[ production and evaluation of photoelectric conversion element ]

A glass substrate on which an ITO film was formed in a thickness of 150nm by a sputtering method was prepared. The glass substrate on which the ITO film was formed was subjected to surface treatment based on ozone UV treatment.

(formation of hole transport layer)

A suspension (Clevios P VP AI4083, manufactured by Heraeus) obtained by dissolving poly (3, 4-ethylenedioxythiophene)/polystyrene sulfonic acid in water was filtered through a filter having a pore size of 0.45. mu.m. The filtered suspension was spin-coated on the ITO side surface of the surface-treated substrate to form a film of 40nm thickness. Next, the substrate on which the film was formed was placed on a hot plate in the air, and the film was dried at 200 ℃ for 10 minutes to form a hole transport layer.

(formation of active layer)

Subsequently, after the composition (I-1) was spin-coated on the hole transport layer, drying was carried out in a vacuum drier (0.1mbar) to form an active layer. The thickness of the active layer after drying was about 400 nm.

(formation of Electron transport layer)

Subsequently, a 45 wt% isopropyl alcohol dispersion (HTD-711Z, manufactured by TAYCA) of zinc oxide nanoparticles (particle size 20 to 30nm) was diluted with 10 parts by weight of 3-pentanol to prepare a coating liquid. The coating liquid was applied onto the active layer by spin coating in a film thickness of 40nm, and dried in a nitrogen atmosphere, thereby forming an electron transporting layer.

(formation of electrode and formation of sealing layer)

Then, an Ag film was formed on the electron transport layer in a thickness of about 80nm in a resistance heating deposition apparatus to form an electrode. Next, a UV curable sealing agent was applied around the substrate on which the electrodes were formed, a glass plate was bonded, and then sealing was performed by irradiation with UV light, thereby obtaining a photoelectric conversion element. The shape of the obtained photoelectric conversion element was a square of 1cm × 1 cm.

(evaluation of photoelectric conversion element)

For the resulting element, the external quantum efficiency was determined using the method described above. The maximum External Quantum Efficiency (EQE) is 68% in the wavelength range of 300nm to 1200 nm. The results are shown in Table 6.

< examples 2 to 6 and comparative examples 1 to 3>

Compositions (I-2) to (I-6) and (C-1) to (C-3) were prepared in the same manner as in [ A. preparation of ink ] of example 1 except that the solvents shown in Table 5 were used as the 1 st solvent and the 2 nd solvent.

Photoelectric conversion elements were produced and evaluated in the same manner as described in [ b. production and evaluation of photoelectric conversion elements ] of example 1 except that the compositions (I-2) to (I-6), (C-1) to (C-3) were used in place of the composition (I-1) in (formation of active layer). The results are shown in Table 6.

[ Table 5]

[ Table 6]

The photoelectric conversion elements of examples 1 to 6 have higher external quantum efficiency when a reverse bias voltage of 3V is applied, as compared with the photoelectric conversion elements of comparative examples 1 to 3.

< examples 7 to 11 and comparative examples 4 to 6>

Ink compositions (I-7) to (I-11) and (C-4) to (C-6) were prepared in the same manner as in [ A. preparation of ink ] of example 1 except that the solvents described in the following table were used as the 1 st solvent and the solvent described in the following table was used as the P-type semiconductor material and the material P-6 was used in place of the material P-1.

[ Table 7]

Photoelectric conversion elements were produced and evaluated in the same manner as described in [ b. production and evaluation of photoelectric conversion elements ] of example 1, except that the compositions (I-7) to (I-11), (C-4) to (C-6) were used in place of the composition (I-1) in (formation of active layer). The results are shown in Table 8.

[ Table 8]

The photoelectric conversion elements of examples 7 to 11 had higher external quantum efficiency when a reverse bias voltage of 3V was applied, as compared with the photoelectric conversion elements of comparative examples 4 to 6.

Description of the symbols

1 image detection unit

2 display device

10 photoelectric conversion element

11. 210 support substrate

12 st electrode

13 hole transport layer

14 active layer

15 electron transport layer

16 nd electrode

20 CMOS transistor substrate

30 interlayer insulating film

32 interlayer wiring part

40 sealing layer

50 color filter

100 fingerprint detection unit

200 display panel section

200a display area

220 organic EL element

230 touch sensor panel

240 sealing substrate

Claims

1. An ink comprising a p-type semiconductor material, an n-type semiconductor material, a 1 st solvent which is a nitrogen-containing heterocyclic compound, and a 2 nd solvent which is an aromatic hydrocarbon.

2. The ink of claim 1, wherein the n-type semiconductor material is a fullerene derivative.

3. Ink according to claim 1 or 2, wherein the nitrogen-containing heterocyclic compound comprises a 6-membered ring structure, the 6-membered ring structure comprising 1 or 2 heteroatoms, the 1 or 2 heteroatoms being nitrogen atoms respectively.

4. The ink according to claim 3, wherein the 6-membered ring structure is a pyridine ring structure, a tetrahydropyridine ring structure, a piperidine ring structure, or a pyrazine ring structure.

5. The ink according to any one of claims 1 to 4, wherein the 1 st solvent is 1 or more selected from the group consisting of a substituted or unsubstituted quinoline, a substituted or unsubstituted 1,2,3, 4-tetrahydroquinoline, and a substituted or unsubstituted quinoxaline.

6. The ink according to any one of claims 1 to 5, wherein the weight ratio of the 1 st solvent to the 2 nd solvent, i.e., the 1 st solvent/the 2 nd solvent, is from 1/99 to 20/80.

7. The ink according to any one of claims 1 to 6, wherein the total weight percentage of the 1 st solvent and the 2 nd solvent in the ink is 95 to 99% by weight.

8. The ink according to any one of claims 1 to 7, wherein the ink is used for forming an active layer of a photoelectric conversion element.

9. A cured film of the ink according to any one of claims 1 to 8.

10. A photoelectric conversion element comprising a 1 st electrode, an active layer comprising a p-type semiconductor material and an n-type semiconductor material, and a 2 nd electrode in this order, the active layer being the cured film according to claim 9.

11. The photoelectric conversion element according to claim 10, wherein the photoelectric conversion element is a light detection element.

12. An image sensor comprising the photoelectric conversion element according to claim 10 or 11.

13. A fingerprint recognition device comprising the photoelectric conversion element according to claim 10 or 11.

14. A method for producing a cured film, comprising the steps of (i) applying the ink according to any one of claims 1 to 8 to an object to be coated to obtain a coating film; in the step (ii), the solvent is removed from the obtained coating film.

15. A method for manufacturing a photoelectric conversion element comprising a 1 st electrode, an active layer comprising a p-type semiconductor material and an n-type semiconductor material, and a 2 nd electrode in this order,

a step of forming the active layer, the step of forming the active layer comprising a step (i) of applying the ink according to any one of claims 1 to 8 to an object to be coated to obtain a coating film; in the step (ii), the solvent is removed from the obtained coating film.