阅读说明：本技术 光电转换元件 (Photoelectric conversion element ) 是由 清家崇广 G·费拉拉 于 2019-03-22 设计创作，主要内容包括：本发明提高光电转换元件(10)的比探测率。一种光电转换元件,其包含：一对电极(12、16)；设置于一对电极间的活性层(14)；以及设置于活性层与所述一对电极中的至少一个电极之间的中间层(13、15),中间层的与活性层接合的面的表面粗糙度的绝对值为大于0.22nm且小于1.90nm的值,活性层的厚度为350nm以上且800nm以下。(The invention improves the specific detectivity of a photoelectric conversion element (10). A photoelectric conversion element, comprising: a pair of electrodes (12, 16); an active layer (14) provided between the pair of electrodes; and intermediate layers (13, 15) provided between the active layer and at least one of the pair of electrodes, wherein the absolute value of the surface roughness of the surface of the intermediate layer that is bonded to the active layer is greater than 0.22nm and less than 1.90nm, and the thickness of the active layer is 350nm or more and 800nm or less.)

1. A photoelectric conversion element, comprising: a pair of electrodes; an active layer provided between the pair of electrodes; and an intermediate layer disposed between the active layer and at least one of the pair of electrodes,

the surface roughness of the surface of the intermediate layer that is bonded to the active layer has an absolute value of greater than 0.22nm and less than 1.90nm,

the thickness of the active layer is 350nm to 800 nm.

2. The photoelectric conversion element according to claim 1, wherein the intermediate layer is an electron transport layer.

3. The photoelectric conversion element according to claim 2, wherein the electron transport layer comprises a polyalkyleneimine or a derivative thereof, or a metal oxide.

4. The photoelectric conversion element according to claim 3, wherein the electron transport layer comprises a metal oxide containing zinc.

5. The photoelectric conversion element according to any one of claims 1 to 4, wherein the surface roughness is 0.55nm to 1.24 nm.

6. The photoelectric conversion element according to any one of claims 1 to 5, wherein the thickness of the active layer is 400nm or more and 700nm or less.

7. The photoelectric conversion element according to any one of claims 1 to 6, wherein the photoelectric conversion element is a photodetection element.

8. The photoelectric conversion element according to any one of claims 1 to 7, wherein the active layer comprises an n-type semiconductor material and a p-type semiconductor material, and the n-type semiconductor material is a fullerene or a fullerene derivative.

Technical Field

The present invention relates to a photoelectric conversion element such as a photodetector and a method for manufacturing the same.

Background

Photoelectric conversion elements are extremely useful devices in terms of, for example, energy saving and reduction in carbon dioxide emission, and have received attention.

The photoelectric conversion element includes at least a pair of electrodes including an anode and a cathode, and an active layer provided between the pair of electrodes. In the photoelectric conversion element, either one of the electrodes is made of a transparent or translucent material, and light is made incident on the organic active layer from the transparent or translucent electrode side. Electric charges (holes and electrons) are generated in the organic active layer by the energy (h ν) of light incident on the organic active layer, the generated holes move to the anode, and the electrons move to the cathode. Thereafter, the electric charges that have reached the anode and the cathode are extracted to the outside of the element.

An active layer having a phase separation structure composed of a phase containing an n-type semiconductor material and a phase containing a p-type semiconductor material by mixing an n-type semiconductor material (electron accepting compound) and a p-type semiconductor material (electron donating compound) is called a bulk heterojunction-type active layer.

For example, application of a photoelectric conversion element as a photodetection element in a visible light communication system or the like is being studied (see non-patent document 1).

Disclosure of Invention

Problems to be solved by the invention

However, the conventional photoelectric conversion element, particularly the photodetection element, has a problem that the specific Detectivity (hereinafter, sometimes referred to as "D") is still insufficient. Further, it is required to further improve the specific detectivity in the photoelectric conversion element.

Means for solving the problems

The present inventors have conducted extensive studies to solve the above problems, and as a result, have found that the above problems can be solved by setting the absolute value of the surface roughness of the surface of the intermediate layer bonded to the active layer and the thickness of the active layer within predetermined ranges, and have completed the present invention.

Namely, the present invention provides the following [1] to [8 ].

[1] A photoelectric conversion element, comprising: a pair of electrodes; an active layer provided between the pair of electrodes; and an intermediate layer disposed between the active layer and at least one of the pair of electrodes,

the absolute value of the surface roughness of the surface of the intermediate layer that is bonded to the active layer is a value greater than 0.22nm and less than 1.90nm,

the thickness of the active layer is 350nm to 800 nm.

[2] The photoelectric conversion element according to [1], wherein the intermediate layer is an electron transport layer.

[3] The photoelectric conversion element according to [2], wherein the electron transport layer comprises a polyalkyleneimine or a derivative thereof, or a metal oxide.

[4] The photoelectric conversion element according to [3], wherein the electron transport layer contains a metal oxide containing zinc.

[5] The photoelectric conversion element according to any one of [1] to [4], wherein the surface roughness is 0.55nm to 1.24 nm.

[6] The photoelectric conversion element according to any one of [1] to [5], wherein the thickness of the active layer is 400nm or more and 700nm or less.

[7] The photoelectric conversion element according to any one of [1] to [6], wherein the photoelectric conversion element is a photodetection element.

[8] The photoelectric conversion element according to any one of [1] to [7], wherein the active layer includes an n-type semiconductor material and a p-type semiconductor material, and the n-type semiconductor material is a fullerene or a fullerene derivative.

Effects of the invention

According to the photoelectric conversion element of the present invention, the specific detectivity can be effectively improved.

Drawings

Fig. 1 is a diagram schematically showing an example of the structure of a photoelectric conversion element.

Fig. 2 is a diagram schematically showing an example of the configuration of the image detection unit.

Fig. 3 is a diagram schematically showing an example of the configuration of the fingerprint detection unit.

Fig. 4 is a graph showing the relationship of D × relative value to the thickness of the active layer.

Fig. 5 is a graph showing the relationship of D × relative value to the thickness of the active layer.

Detailed Description

A photoelectric conversion element according to an embodiment of the present invention will be described below with reference to the drawings. The drawings schematically show the shapes, sizes, and arrangements of the constituent elements to an extent that the invention can be understood. The present invention is not limited to the following description, and various components may be appropriately modified within a range not departing from the gist of the present invention. The configuration of the embodiment of the present invention is not necessarily limited to the configuration shown in the drawings.

Terms commonly used in the following description are explained.

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

The term "constituent unit" means that 1 or more units are present in the polymer compound.

The "hydrogen atom" may be a protium atom or a deuterium atom.

Examples of the "halogen atom" include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

The term "may have a substituent" includes both a case where all hydrogen atoms constituting a compound or a group are not substituted and a case where 1 or more hydrogen atoms are partially or completely substituted with a substituent. .

Unless otherwise specified, "alkyl" may be linear, branched, or 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 alkyl groups such as a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a 2-ethylbutyl group, a n-hexyl group, a cyclohexyl group, a n-heptyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a n-octyl group, a 2-ethylhexyl group, a 3-n-propylheptyl group, an adamantyl group, a n-decyl group, a 3, 7-dimethyloctyl group, a 2-ethyloctyl group, a 2-n-hexyldecyl group, a n-dodecyl group, a tetradec; an alkyl group having a further substituent such as a trifluoromethyl group, a pentafluoroethyl group, a perfluorobutyl group, a perfluorohexyl group, a perfluorooctyl group, a 3-phenylpropyl group, a 3- (4-methylphenyl) propyl group, a 3- (3, 5-di-n-hexylphenyl) propyl group, and a 6-ethoxyhexyl group.

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 a group having a substituent group such as an alkyl group, an alkoxy group, an aryl group, a fluorine atom, and 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 a group having a substituent such as an alkyl group, an alkoxy group, or a fluorine atom.

The "alkylthio group" may be any of straight-chain, branched-chain and 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 a phenylthio group, a C1-C12 alkoxyphenylthio group (here, "C1-C12" represents that the number of carbon atoms of the group described immediately below is 1-12. the same applies hereinafter), a C1-C12 alkylphenylthio group, a 1-naphthylthio group, a 2-naphthylthio group and a 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 a compound in which the heterocyclic ring itself does not exhibit aromaticity and an aromatic ring is fused to the heterocyclic ring, in addition to a compound in which the heterocyclic ring itself exhibits 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 a group further having a substituent such as an alkyl group or an alkoxy group.

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

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

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

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. 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 number of carbon atoms of the imine residue is usually 2 to 20, preferably 2 to 18. 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 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 group) 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 4 to 20. Specific examples of the imide group include groups represented by the following structural formulae.

[ 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 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 a group having a substituent such as an alkyl group or an alkoxy group.

The "alkynyl group" may be any of linear, branched and cyclic. The number of carbon atoms of the straight chain alkynyl group which does not include 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 a group having a substituent such as an alkyl group or an alkoxy group.

1. Photoelectric conversion element

The photoelectric conversion element (organic photoelectric conversion element) according to the present embodiment includes: a pair of electrodes; an active layer provided between the pair of electrodes; and an intermediate layer provided between the active layer and at least one of the pair of electrodes, wherein an absolute value of surface roughness of a surface of the intermediate layer, which is bonded to the active layer, is greater than 0.22nm and less than 1.90nm, and a thickness of the active layer is 200nm to 800 nm.

Examples of applications of the photoelectric conversion element of the present embodiment include a solar cell and a photodetector. The photoelectric conversion element of this embodiment mode can be particularly suitably used as a photodetection element.

Here, a description will be given of a configuration example that can be adopted by the photoelectric conversion element of the present embodiment. Fig. 1 is a diagram schematically showing a photoelectric conversion element of the present embodiment.

As shown in fig. 1, the photoelectric conversion element 10 includes: a cathode 12 provided on the support substrate 11 so as to be in contact with the support substrate 11; an electron transport layer 13 provided so as to be in contact with the cathode 12; an active layer 14 provided in contact with the electron transport layer 13; a hole transport layer 15 provided so as to contact the active layer 14; and an anode 16 provided in contact with the hole transport layer 15. In this configuration example, a sealing member 17 is provided so as to contact the anode 16.

Hereinafter, the constituent elements included in the photoelectric conversion element of the present embodiment will be specifically described.

(substrate)

The photoelectric conversion element is generally formed on a substrate (support substrate). A pair of electrodes, which is generally composed of a cathode and an anode, is formed on the substrate. The material of the substrate is not particularly limited as long as it does not chemically change when forming a layer containing an organic compound in particular.

Examples of the material of the substrate include glass, plastic, polymer film, and silicon. In the case of an opaque substrate, it is preferable that an electrode on the opposite side of an electrode provided on the opaque substrate side (i.e., an electrode on the far side from the opaque substrate) is a transparent or semitransparent electrode.

(electrode)

The photoelectric conversion element includes a pair of electrodes, i.e., an anode and a cathode. At least one of the anode and the cathode is preferably a transparent or translucent electrode in order to allow light to be incident.

Examples of the material of the transparent or translucent electrode include a conductive metal oxide film, a translucent metal thin film, and the like. Specific examples thereof include conductive materials such as indium oxide, zinc oxide, tin oxide, and a composite thereof, such as Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), and NESA, and gold, platinum, silver, and copper. As a material of the transparent or translucent electrode, ITO, IZO, tin oxide are preferable. As the electrode, a transparent conductive film using an organic compound such as polyaniline and a derivative thereof, polythiophene and a derivative thereof, or the like as a material can be used. The transparent or translucent electrode may be an anode or a cathode.

As long as one of the pair of electrodes is transparent or translucent, the other electrode may be an electrode having low light transmittance. Examples of the material of the electrode having low light transmittance include metals and conductive polymers. Specific examples of the material of the electrode having low light transmittance include metals such as lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbium, and alloys of 2 or more of these metals; or an alloy of 1 or more of these metals with 1 or more metals selected from the group consisting of gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, and tin; graphite, graphite intercalation compounds, polyaniline and its derivatives, and polythiophene and its derivatives. Examples of the alloy include magnesium-silver alloy, magnesium-indium alloy, magnesium-aluminum alloy, indium-silver alloy, lithium-aluminum alloy, lithium-magnesium alloy, lithium-indium alloy, and calcium-aluminum alloy.

As the method for forming the electrode, any suitable conventionally known method for forming the electrode can be used. Examples of the method of forming the electrode include a vacuum deposition method, a sputtering method, an ion plating method, and a plating method.

(active layer)

The active layer includes a p-type semiconductor material (electron donating compound) and an n-type semiconductor material (electron accepting compound) (details of suitable p-type semiconductor material and n-type semiconductor material will be described later). Which of the p-type semiconductor material and the n-type semiconductor material is determined relatively according to the energy level of HOMO or LUMO of the selected compound.

In this embodiment, the thickness of the active layer is preferably 350nm or more from the viewpoint of reducing a leakage current (dark current) generated in a state where no light is irradiated. On the other hand, when the active layer is too thick, it is difficult to extract a current (photocurrent) generated in a state of being irradiated with light, and therefore the thickness of the active layer is preferably 800nm or less, and more preferably 400nm to 700nm from the viewpoint of making a balance between a dark current and a photocurrent good.

When the thickness of the active layer is adjusted to fall within the above range, the decrease in photocurrent can be reduced, the dark current can be further reduced, and the specific detectivity can be further improved.

(intermediate layer)

As shown in fig. 1, the photoelectric conversion element of the present embodiment preferably includes an intermediate layer such as a charge transport layer (an electron transport layer, a hole transport layer, an electron injection layer, or a hole injection layer) as a component for improving characteristics such as photoelectric conversion efficiency.

In the present embodiment, the absolute value of the surface roughness of the surface of the intermediate layer bonded to the active layer is preferably a value greater than 0.22nm and less than 1.90nm, more preferably 0.33nm to 1.50nm, and even more preferably 0.55nm to 1.24nm, from the viewpoint of improving the specific detectivity.

As the material used for such an intermediate layer, any conventionally known suitable material that contributes to charge transfer in the layer constituting the photoelectric conversion element can be used, for example. Examples of the material of the intermediate layer include halides of alkali metals or alkaline earth metals such as lithium fluoride, and oxides such as molybdenum oxide.

Examples of the material used for the intermediate layer include fine particles of an inorganic oxide semiconductor such as titanium oxide or zinc oxide, and a mixture of PEDOT (poly (3, 4-ethylenedioxythiophene)) and PSS (poly (4-styrenesulfonate)) (PEDOT: PSS).

As shown in fig. 1, the photoelectric conversion element of the present embodiment preferably includes an electron transport layer as an intermediate layer between the cathode and the active layer. The electron transport layer has a function of transporting electrons from the active layer to the cathode. The electron transport layer may be attached to the cathode. The electron transport layer may also be contiguous with the active layer.

The electron transport layer provided in contact with the cathode is sometimes particularly referred to as an electron injection layer. The electron transport layer (electron injection layer) provided in contact with the cathode has a function of promoting injection of electrons generated in the active layer into the cathode.

The electron transport layer includes an electron transport material. Examples of the electron transporting material include polyalkyleneimine and derivatives thereof, a polymer compound having a fluorene structure, and a metal oxide.

The electron transport layer preferably contains polyalkyleneimine or a derivative thereof, or a metal oxide.

Examples of polyalkyleneimines and derivatives thereof include: a polymer obtained by polymerizing 1 or 2 or more species of C2-8 alkyleneimines such as ethyleneimine, propyleneimine, butyleneimine, dimethylethyleneimine, penteneimine, hexeneimine, heptyleneimine, and octenylimine, particularly C2-4 alkyleneimines, and a polymer chemically modified by reacting these with various compounds. As the polyalkyleneimines and derivatives thereof, Polyethyleneimine (PEI) and ethoxylated Polyethyleneimine (PEIE) are preferred.

Examples of the polymer compound having a fluorene structure include poly [ (9, 9-bis (3 '- (N, N-dimethylamino) propyl) -2, 7-fluorene) -o-2, 7- (9, 9' -dioctylfluorene) ] (PFN) and PFN-P2.

Examples of the metal oxide include zinc oxide, gallium-doped zinc oxide, aluminum-doped zinc oxide, titanium oxide, and niobium oxide. As the metal oxide, a metal oxide containing zinc is preferable, and among them, zinc oxide is preferable.

Examples of other electron-transporting materials include poly (4-vinylphenol) and perylene diimide.

In the present embodiment, the absolute value of the surface roughness of the surface of the electron transport layer (electron injection layer) that is bonded to the active layer is preferably a value greater than 0.22nm and less than 1.90nm, more preferably 0.33nm to 1.50nm, and still more preferably 0.55nm to 1.24 nm.

When the absolute value of the surface roughness of the surface of the electron transit layer, which is bonded to the active layer, is adjusted to be within the above range, electrons can be collected from the active layer to the electron transit layer more efficiently, so that the External Quantum Efficiency (EQE) can be further improved, and the specific probe ratio can be further improved.

Here, the EQE specifically refers to a value indicating a ratio (%) of the number of electrons generated that can be extracted to the outside of the photoelectric conversion element to the number of photons absorbed by the photoelectric conversion element.

As shown in fig. 1, the photoelectric conversion element may include a hole transport layer between the anode and the 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 anode is sometimes particularly referred to as a hole injection layer. The hole transport layer (hole injection layer) provided in contact with the anode has a function of promoting injection of holes into the anode. The hole transport layer (hole injection layer) may be in contact with the active layer.

The hole transport layer contains a hole transporting material. As an example of the hole-transporting material, mention may be made ofPolythiophene and its derivative, aromatic amine compound, polymer compound containing constituent unit having aromatic amine residue, CuSCN, CuI, NiO and molybdenum oxide (MoO)₃)。

The intermediate layer can be formed by the same coating method as the formation method of the active layer already described.

The photoelectric conversion element according to the present embodiment preferably has the following configuration: the intermediate layer is an electron transport layer, and a substrate (support substrate), a cathode, an electron transport layer, an active layer, and an anode are laminated in this order so as to be in contact with each other.

(sealing Member)

The photoelectric conversion element of the present embodiment may be sealed by a sealing member. As an example of the sealing member, a combination of a sealing material and a cover glass having a concave portion as a sealing substrate can be given.

The sealing member may be a sealing layer as a layer structure of one or more layers. Examples of the layer constituting the sealing layer include a gas barrier layer and a gas barrier film.

The sealing layer is preferably formed of a material having a property of blocking moisture (water vapor barrier property) or a property of blocking oxygen (oxygen barrier property). Suitable materials for the sealing layer include organic materials such as resins such as trifluoroethylene, Polychlorotrifluoroethylene (PCTFE), polyimide, polycarbonate, polyethylene terephthalate, alicyclic polyolefin, and ethylene-vinyl alcohol copolymer; inorganic materials such as silicon oxide, silicon nitride, aluminum oxide, and diamond-like carbon; and so on.

(use of photoelectric conversion element)

The photoelectric conversion element of the present embodiment can flow a photocurrent by being irradiated with light from a transparent or translucent electrode side in a state where a voltage (reverse bias voltage) is applied between the electrodes, and can operate as a photodetection element (photosensor). In addition, a plurality of photosensors may be integrated and used as an image sensor.

The photoelectric conversion element of the present embodiment can generate a photovoltaic force between the electrodes by irradiating light, and can operate as a solar cell. A solar cell module can also be made by integrating a plurality of solar cells.

(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 specific feature of a part of a living body, a detection unit for an optical biosensor such as a pulse oximeter, and the like.

The following describes 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)

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

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 40.

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 reading 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. The sealing layer 40 may have the same configuration as the sealing member 17 described above.

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)

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

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, and an electrode (anode or cathode) is provided on the support substrate 11 in a matrix, 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.

According to the photoelectric conversion element of the present invention, by adjusting the surface roughness of the electron transport layer to be within the predetermined range and adjusting the thickness of the active layer to be within the predetermined range, it is possible to achieve both an improvement in external quantum efficiency and a reduction in dark current, and as a result, it is possible to effectively improve the specific detectivity.

2. Method for manufacturing photoelectric conversion element

The method for manufacturing the photoelectric conversion element of the present embodiment is not particularly limited. The photoelectric conversion element can be manufactured by combining forming methods suitable for materials selected when forming each constituent element.

The method for manufacturing the photoelectric conversion element includes: a step of forming an intermediate layer, wherein the absolute value of the surface roughness of the surface of the intermediate layer, which is bonded to the active layer, is greater than 0.22nm and less than 1.90 nm; and forming an active layer having a thickness of 200nm to 800 nm.

Hereinafter, as an embodiment of the present invention, a method for manufacturing a photoelectric conversion element having a structure in which a substrate (support substrate), a cathode, an electron transport layer, an active layer, a hole transport layer, and an anode are in contact with each other in this order will be described.

(step of preparing substrate)

In this step, a support substrate provided with a cathode is prepared.

The method of providing the cathode on the support substrate is not particularly limited. The cathode can be formed of the above-described exemplary materials on the support substrate made of the above-described materials by, for example, a vacuum deposition method, a sputtering method, an ion plating method, a plating method, or the like.

Further, a support substrate provided with a cathode can be prepared by obtaining a substrate provided with a conductive thin film formed of the material of the electrode described above from the market, and patterning the conductive thin film as necessary to form the cathode.

(Process for Forming Electron transport layer)

The method of manufacturing a photoelectric conversion element may include: and forming an electron transport layer (electron injection layer) provided between the active layer and the cathode.

Specifically, the method for manufacturing a photoelectric conversion element according to the present embodiment further includes a step of forming an electron transport layer after the step of preparing the support substrate provided with the cathode and before the step of forming the active layer.

The method for forming the electron transporting layer is not particularly limited. From the viewpoint of simplifying the step of forming the electron transporting layer and adjusting the surface roughness to a predetermined value (within a predetermined range), it is preferable to form the electron transporting layer by a coating method. That is, it is preferable that before the formation of the active layer and after the formation of the cathode, a coating liquid containing an electron transporting material and a solvent described later is applied to the cathode, and if necessary, a drying treatment (heating treatment) or the like is performed to remove the solvent, thereby forming the electron transporting layer.

The electron-transporting material used for forming the electron-transporting layer may be an organic compound or an inorganic compound.

The electron-transporting material as the organic compound may be a low-molecular organic compound or a high-molecular organic compound.

Examples of the electron-transporting material as the low-molecular organic 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, polyquinoline and its derivatives, polyquinoxaline and its derivatives, polyfluorene and its derivatives, and C₆₀Fullerenes such as fullerene and derivatives thereof, phenanthrene derivatives such as bathocuproine, and the like.

Examples of the electron-transporting material as the polymer organic 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, and polyfluorene and derivatives thereof.

Examples of the electron-transporting material as the inorganic compound include zinc oxide, titanium oxide, zirconium oxide, tin oxide, indium oxide, GZO (gallium-doped zinc oxide), ATO (antimony-doped tin oxide), and AZO (aluminum-doped zinc oxide). Among these, zinc oxide, gallium-doped zinc oxide, or aluminum-doped zinc oxide is preferable. In forming the electron transporting layer, the electron transporting layer is preferably formed using a coating liquid containing particulate zinc oxide, gallium-doped zinc oxide, or aluminum-doped zinc oxide. As such an electron transporting material, it is preferable to use zinc oxide nanoparticles, gallium-doped zinc oxide nanoparticles, or aluminum-doped zinc oxide nanoparticles, and it is more preferable to form the electron transporting layer using an electron transporting material composed of only zinc oxide nanoparticles, gallium-doped zinc oxide nanoparticles, or aluminum-doped zinc oxide nanoparticles.

The average particle diameter of the equivalent sphere of the nanoparticles of zinc oxide, gallium-doped zinc oxide, and aluminum-doped zinc oxide is preferably 1nm to 1000nm, and more preferably 10nm to 100 nm. The average particle diameter can be measured by, for example, a laser scattering method, an X-ray diffraction method, or the like.

In the method for producing a photoelectric conversion element according to the present invention, the step of forming the electron transport layer preferably includes a step of forming the electron transport layer by applying a coating liquid containing PEIE, perylene diimide, PFN, or PFN-P2.

Examples of the solvent contained in the coating liquid containing an electron-transporting material include water, alcohols, ketones, and hydrocarbons. Specific examples of the alcohol include methanol, ethanol, isopropanol, butanol, ethylene glycol, propylene glycol, butoxyethanol, methoxybutanol, and the like. Specific examples of the ketone include acetone, methyl ethyl ketone, methyl isobutyl ketone, 2-heptanone, and cyclohexanone. Specific examples of the hydrocarbon include n-pentane, cyclohexane, n-hexane, benzene, toluene, xylene, tetrahydronaphthalene, chlorobenzene, o-dichlorobenzene, and the like. The coating liquid may contain 1 kind of solvent alone, may contain 2 or more kinds of solvents, and may contain 2 or more kinds of the above solvents.

The coating liquid used in the coating method for forming the electron transporting layer may be a dispersion liquid such as an emulsion (emulsion) or a suspension (suspension). The coating liquid is preferably a coating liquid that causes little damage to a layer (such as an active layer) to which the coating liquid is applied, and more specifically, is preferably a coating liquid that does not easily dissolve the layer (such as an active layer) to which the coating liquid is applied.

The step of forming the electron transporting layer is performed by a coating method, and the surface roughness of the electron transporting layer can be adjusted to any suitable range by adjusting the size (particle diameter; molecular weight in the case of a polymer compound, etc.) of the electron transporting material used. When the coating method is a spin coating method, the surface roughness of the electron transport layer can be adjusted to any suitable range by adjusting the characteristics of the coating liquid such as the concentration of components in the coating liquid used (the viscosity of the coating liquid), and the execution conditions such as the number of revolutions of the rotation, the rotation time, and the drying (heating) conditions.

Specifically, by increasing the dilution ratio by the solvent, the surface roughness of the side of the electron transport layer which is an intermediate layer, for example, which is in contact with the active layer can be made larger; by reducing the dilution ratio by the solvent, the surface roughness of the side of the electron transport layer in contact with the active layer can be made smaller.

The surface roughness of other intermediate layers such as a hole transport layer that can be formed by a coating method can be similarly adjusted to any appropriate range. When the laminated structure in which the active layer is formed on the surface of the intermediate layer whose surface roughness is adjusted in this manner is employed, the operational effects of the present invention described above can be obtained.

(Process for Forming active layer)

The active layer, which is a main component of the photoelectric conversion element of the present embodiment, can be produced by a coating method using a coating liquid (ink).

The steps (i) and (ii) included in the step of forming the active layer, which is a main component of the photoelectric conversion element of the present invention, will be described below.

Step (i)

As a method of applying the coating liquid to the coating object, any suitable 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 printing 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 coating liquid for forming the active layer is applied to a coating object selected according to the photoelectric conversion element and the method for producing the same. The coating liquid for forming the active layer may be applied to a functional layer which may be present in the active layer of the photoelectric conversion element in the process of manufacturing the photoelectric conversion element. Therefore, the coating target of the coating liquid for forming the active layer differs depending on the layer structure of the produced photoelectric conversion element and the order of layer formation. For example, when the photoelectric conversion element has a layer structure in which a substrate, an anode, a hole transport layer, an active layer, an electron transport layer, and a cathode are laminated, and a layer described on the right side is formed first, the coating liquid for forming the active layer is applied to the electron transport layer. For example, when the photoelectric conversion element has a layer structure in which a substrate, a cathode, an electron transport layer, an active layer, a hole transport layer, and an anode are stacked, and a layer described on the right side is formed first, the coating liquid for forming the active layer is applied to the hole transport layer.

Step (ii)

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

The thickness of the active layer can be adjusted to a desired thickness by appropriately adjusting the solid content concentration in the coating liquid and the conditions of the step (i) and/or the step (ii).

Specifically, for example, when the coating method is a spin coating method, the thickness of the active layer can be adjusted to any appropriate thickness by adjusting the characteristic conditions of the coating liquid such as the concentration of components in the coating liquid used (the viscosity of the coating liquid), and the execution conditions such as the rotation speed and the rotation time in the spin coating method.

For example, in order to adjust the thickness of the active layer in a thicker direction, the concentration of the component in the coating liquid may be made higher and/or the rotation speed in the spin coating method may be made lower.

The step of forming an active layer may include other steps in addition to the steps (i) and (ii) without impairing the object and effect of the present invention.

The method for manufacturing a photoelectric conversion element may be a method for manufacturing a photoelectric conversion element including a plurality of active layers, or a method for repeating the step (i) and the step (ii) a plurality of times.

The coating liquid for forming an active layer may be a solution, or may be a dispersion such as a dispersion, an emulsion (emulsion), or a suspension (suspension). The active layer forming coating liquid according to the present embodiment includes a p-type semiconductor material, an n-type semiconductor material, and a solvent. The components of the active layer forming coating liquid will be described below.

(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 a low molecular compound include phthalocyanine, metal phthalocyanine, porphyrin, metal porphyrin, oligothiophene, tetracene, pentacene, and rubrene.

When the p-type semiconductor material is a polymer compound, the polymer compound has a predetermined polystyrene equivalent weight average molecular weight.

Here, the polystyrene-reduced weight average molecular weight refers to a weight average molecular weight calculated using Gel Permeation Chromatography (GPC) using a standard sample of polystyrene.

From the viewpoint of solubility in a solvent, the polystyrene-equivalent weight average molecular weight of the p-type semiconductor material is preferably 20000 to 200000, more preferably 30000 to 180000, and still more preferably 40000 to 150000.

Examples of the p-type semiconductor material which is a 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 belonging to the polymer compound is preferably a polymer compound containing a constitutional unit having a thiophene skeleton.

The p-type semiconductor material is preferably a polymer compound containing a constituent unit represented by the following formula (I) and/or a constituent unit represented by the following formula (II).

[ solution 3]

In the formula (I), Ar¹And Ar²Represents a 3-valent aromatic heterocyclic group, and Z represents a group represented by 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 constituent unit represented by the formula (I) is preferably a constituent unit represented by the following formula (I-1).

[ solution 6]

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

Examples of the constituent unit represented by formula (I-1) include constituent 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 number of carbon atoms of the 2-valent aromatic heterocyclic group is usually 2 to 60, preferably 4 to 60, and more preferably 4 to 20. 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]

[ chemical formula 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) from the viewpoint of availability of the starting compound¹And X²Preferably both are sulfur atoms.

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

The polymer compound as the p-type semiconductor material may contain a constituent 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 the aromatic hydrocarbon may have include the same substituents as those exemplified as the substituents that the heterocyclic compound may have.

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 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 16]

[ solution 18]

[ solution 19]

[ solution 20]

[ solution 21]

The constituent unit constituting the polymer compound as the p-type semiconductor material may be a constituent unit in which 2 or more constituent units selected from the group consisting of the constituent unit represented by formula (I), the constituent unit represented by formula (II), and the constituent unit represented by formula (III) are combined and connected.

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

Specific examples of the polymer compound as the P-type semiconductor material include polymer compounds represented by the following formulas P-1 to P-6.

[ solution 22]

[ solution 23]

The active layer forming coating liquid 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 is preferably C₆₀A fullerene derivative. C₆₀The fullerene derivative is C₆₀A 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 C₆₀Specific examples of the fullerene derivative include [6, 6]]-phenyl-C61 butyric acid methyl ester (C60PCBM, [6, 6] butyric acid methyl ester]Phenyl C61 butyl acid methyl ester) and [6,6]-thienyl-C61 butyric acid methyl ester ([6, 6)]-Thienyl C61 butyric acid methyl ester)。

The active layer forming coating liquid 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.

(solvent)

The coating liquid for forming an active layer may contain only 1 kind of solvent, or may contain 2 or more kinds of solvents in combination at an arbitrary ratio. When the active layer forming coating liquid contains 2 or more kinds of solvents, it preferably contains a main solvent (referred to as a 1 st solvent) as a main component and another additional solvent (referred to as a 2 nd solvent) added for improving solubility or the like. The 1 st and 2 nd solvents are explained below.

(1) 1 st solvent

The solvent may be selected in consideration of solubility to the selected p-type semiconductor material and n-type semiconductor material and characteristics (boiling point and the like) according to drying conditions in forming the active layer.

The 1 st solvent as the main solvent is preferably an aromatic hydrocarbon (hereinafter, abbreviated as an aromatic hydrocarbon) having or not having a substituent (an alkyl group or a halogen atom). The 1 st solvent is preferably selected in consideration of the solubility of the selected p-type semiconductor material and n-type semiconductor material.

Examples of such aromatic hydrocarbons 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, indane, chlorobenzene, and dichlorobenzene (o-dichlorobenzene).

The 1 st solvent may be composed of only 1 kind of aromatic hydrocarbon, or may be composed of 2 or more kinds of aromatic hydrocarbons. The 1 st solvent is preferably composed of only 1 aromatic hydrocarbon.

The 1 st solvent preferably contains 1 or more selected from the group consisting of toluene, o-xylene, m-xylene, p-xylene, mesitylene, pseudocumene, n-butylbenzene, sec-butylbenzene, tert-butylbenzene, methylnaphthalene, tetrahydronaphthalene, indane, chlorobenzene and o-dichlorobenzene, and more preferably is o-xylene, pseudocumene, chlorobenzene or o-dichlorobenzene.

(2) 2 nd solvent

The 2 nd solvent is preferably a solvent selected from the viewpoint of facilitating the production process and further improving the characteristics of the photoelectric conversion element. Examples of the second solvent 2 include ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone, acetophenone and propiophenone, and ester solvents such as ethyl acetate, butyl acetate, phenyl acetate, ethyl cellosolve acetate, methyl benzoate, butyl benzoate and benzyl benzoate.

From the viewpoint of reducing dark current, the 2 nd solvent is preferably acetophenone, propiophenone, or benzyl benzoate.

(3) Combination of No. 1 solvent and No. 2 solvent

Examples of suitable combinations of the 1 st solvent and the 2 nd solvent include combinations of o-xylene and acetophenone.

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

From the viewpoint of further improving the solubility of the p-type semiconductor material and the n-type semiconductor material, the weight ratio of the 1 st solvent as the main solvent to the 2 nd solvent as the additional solvent (1 st solvent: 2 nd solvent) is preferably 85: 15-99: 1, in the above range.

(4) The total weight percentage of the No. 1 solvent and the No. 2 solvent

When the total weight of the coating liquid is 100 wt%, the total weight of the 1 st solvent and the 2 nd solvent contained in the coating liquid is preferably 90 wt% or more, more preferably 92 wt% or more, and still more preferably 95 wt% or more, from the viewpoint of further improving the solubility of the p-type semiconductor material and the n-type semiconductor material, and is preferably 99 wt% or less, more preferably 98 wt% or less, and still more preferably 97.5 wt% or less, from the viewpoint of improving the concentration of the p-type semiconductor material and the n-type semiconductor material in the coating liquid and easily forming a layer having a constant thickness or more.

(5) Optionally other solvents

The solvent may also include optional solvents other than the 1 st solvent and the 2 nd solvent. The content of the optional other solvent is preferably 5% by weight or less, more preferably 3% by weight or less, and still more preferably 1% by weight or less, assuming that the total weight of all solvents contained in the coating liquid is 100% by weight. As the optional other solvent, a solvent having a boiling point higher than that of the 2 nd solvent is preferable.

(6) 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 coating liquid may contain optional components such as an ultraviolet absorber, an antioxidant, a sensitizer for sensitizing a function of generating a charge by absorbed light, a photostabilizer for increasing stability against ultraviolet rays, and the like within limits not detrimental to the object and effect of the present invention.

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

The total concentration of the p-type semiconductor material and the n-type semiconductor material in the coating liquid 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 coating liquid, the p-type semiconductor material and the n-type semiconductor material may be dissolved or dispersed. The p-type semiconductor material and the n-type semiconductor material are preferably at least partially dissolved, more preferably completely dissolved.

(preparation of coating liquid)

The coating liquid can be prepared by a known method. For example, it can be prepared by the following method: a method of mixing the 1 st solvent and the 2 nd solvent to prepare a mixed 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 in a 1 st solvent, adding an n-type semiconductor material in 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 the 1 st and 2 nd solvents and the p-type semiconductor material and the n-type semiconductor material are mixed, the resulting mixture may be filtered using a filter, and the resulting filtrate may be used as a coating liquid. As the filter, for example, a filter made of a fluororesin such as Polytetrafluoroethylene (PTFE) can be used.

(Process for Forming hole transport layer)

The method of manufacturing a photoelectric conversion element may include: and a step of forming a hole transport layer (hole injection layer) provided between the active layer and the anode. In this embodiment mode, a hole transport layer is formed over an active layer.

The method for forming the hole transport layer is not particularly limited. From the viewpoint of simplifying the step of forming the hole transport layer, it is preferable to form the hole transport layer by a coating method. The hole transport layer can be formed by, for example, applying a coating solution containing the material of the hole transport layer described above and a solvent to the active layer.

Examples of the solvent in the coating liquid used in the coating method include water, alcohols, ketones, and hydrocarbons. Specific examples of the alcohol include methanol, ethanol, isopropanol, butanol, ethylene glycol, propylene glycol, butoxyethanol, and methoxybutanol. Specific examples of the ketone include acetone, methyl ethyl ketone, methyl isobutyl ketone, 2-heptanone, and cyclohexanone. Specific examples of the hydrocarbon include n-pentane, cyclohexane, n-hexane, benzene, toluene, xylene, tetrahydronaphthalene, chlorobenzene, o-dichlorobenzene, and the like. The coating liquid may contain 1 kind of solvent alone, may contain 2 or more kinds of solvents, and may contain 2 or more kinds of solvents exemplified above. The amount of the solvent in the coating liquid is preferably 1 part by weight or more and 10000 parts by weight or less, and more preferably 10 parts by weight or more and 1000 parts by weight or less, relative to 1 part by weight of the material of the hole transport layer.

Examples of a method (coating method) of applying a coating solution containing a material of the hole transport layer and a solvent include a spin coating method, a casting method, a micro-gravure coating 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 flexo printing method, an offset printing method, an ink jet printing method, a dispenser printing method, a nozzle coating method, and a capillary coating method. Among these, spin coating, flexographic printing, inkjet printing, and dispenser printing are preferable.

It is preferable that the coating film obtained by applying a coating solution containing the material of the hole transport layer and the solvent is subjected to a heating treatment, an air drying treatment, a pressure reduction treatment, or the like, thereby removing the solvent from the coating film.

(Process for Forming Anode)

The anode is typically formed on the active layer. When the method of manufacturing a photoelectric conversion element of the present embodiment includes a step of forming a hole transport layer, an anode is formed on the hole transport layer.

The method of forming the anode is not particularly limited. The anode can be formed of the above-described material on a layer (for example, an active layer or a hole transport layer) on which the anode is to be formed by a vacuum evaporation method, a sputtering method, an ion plating method, a coating method, or the like.

When the material of the anode is polyaniline and a derivative thereof, polythiophene and a derivative thereof, nanoparticles of a conductive material, a nanowire of a conductive material, or a nanotube of a conductive material, the anode can be formed by a coating method using an emulsion (emulsion), a suspension (suspension), or the like containing these materials and a solvent.

When the material of the anode contains a conductive material, the anode can be formed by a coating method using a coating liquid containing a conductive material, a metal ink, a metal paste, a low melting point metal in a molten state, or the like. As a method for applying a coating solution containing a material of the anode and a solvent, the same method as in the step of forming the active layer described above can be used.

Examples of the solvent contained in the coating liquid used for forming the anode by the coating method include hydrocarbon solvents such as toluene, xylene, mesitylene, tetralin, decahydronaphthalene, bicyclohexane, n-butylbenzene, sec-butylbenzene, and tert-butylbenzene; halogenated saturated hydrocarbon solvents such as carbon tetrachloride, chloroform, dichloromethane, dichloroethane, chlorobutane, bromobutane, chloropentane, bromopentane, chlorohexane, bromohexane, chlorocyclohexane and bromocyclohexane; halogenated aromatic hydrocarbon solvents such as chlorobenzene, dichlorobenzene, trichlorobenzene and the like; ether solvents such as tetrahydrofuran and tetrahydropyran; water, alcohol, and the like. Specific examples of the alcohol include methanol, ethanol, isopropanol, butanol, ethylene glycol, propylene glycol, butoxyethanol, methoxybutanol, and the like. The coating liquid may contain 1 kind of solvent alone, may contain 2 or more kinds of solvents, and may contain 2 or more kinds of the above solvents.