Light detection element

Abstract

A light detection element with reduced dark current and improved external quantum efficiency. The light detection element comprises: an anode; a cathode; and an active layer disposed between the anode and the cathode and comprising a p-type semiconductor material and an n-type semiconductor material, wherein the thickness of the active layer is greater than 800 nm, and the value obtained by subtracting the absolute value of the LUMO of the n-type semiconductor material from the work function of the surface in contact with the cathode side surface of the active layer is 0.0 to 0.5 eV. In addition, the above-mentioned n-type semiconductor material has an absolute value of the LUMO of 2.0 eV to 10.0 eV.

Description

Technical Field

[0001] The present invention relates to a photoelectric conversion element, in particular to a light detection element, an image sensor and a fingerprint recognition device. Background Art

[0002] Photoelectric conversion elements are extremely useful devices from the perspectives of, for example, saving energy and reducing carbon dioxide emissions, and have attracted attention.

[0003] The photoelectric conversion element at least comprises a pair of electrodes consisting of an anode and a cathode, and an active layer disposed between the pair of electrodes. In the photoelectric conversion element, any one of the electrodes is formed of a transparent or translucent material, so that light is incident on the active layer from the transparent or translucent electrode side. The energy (hν) of the light incident on the active layer generates charges (holes and electrons) in the active layer, and the generated holes move to the anode and the electrons move to the cathode. Afterwards, the charges reaching the anode and the cathode are extracted to the outside of the photoelectric conversion element via the electrodes.

[0004] Among photoelectric conversion elements, light detection elements are particularly used in image sensors, various biometric authentication devices, and the like. High detection sensitivity characteristics are required depending on the application, and various studies have been conducted in recent years.

[0005] When a photoelectric conversion element is used as a light detection element, in order to obtain high detection sensitivity characteristics as the light detection element, it is required to reduce dark current (current generated even when no light is irradiated) and improve external quantum efficiency (EQE).

[0006] It is reported that in a photodetection element, dark current can be reduced by increasing the thickness (film thickness) of an active layer (Non-Patent Document 1).

[0007] Prior art literature

[0008] Non-patent literature

[0009] Non-patent document 1: Adv. Funct. Mater. 2010, 20, 3895-3903 Summary of the invention

[0010] Problems to be solved by the invention

[0011] In order to obtain high detection sensitivity characteristics, a light detection element with reduced dark current and improved external quantum efficiency is required. However, it has been observed that the external quantum efficiency of a light detection element decreases as the thickness of the active layer increases, and thus it is difficult to obtain a light detection element with good characteristics that take into account both dark current and external quantum efficiency.

[0012] Means for solving problems

[0013] The inventors of the present invention have conducted intensive research to solve the above-mentioned problems and have found that, when the value obtained by subtracting the absolute value of the lowest unoccupied molecular orbital (LUMO) of the n-type semiconductor in the active layer from the work function (WF) of the surface in contact with the cathode side surface of the active layer in the photodetecting element is within a predetermined range, a high external quantum efficiency can be maintained even if the thickness of the active layer is increased, thereby completing the present invention. That is, the present invention provides the following [1] to

[14] .

[0014] [1] A light detecting element comprising: an anode; a cathode; and an active layer disposed between the anode and the cathode and comprising a p-type semiconductor material and an n-type semiconductor material, wherein:

[0015] The thickness of the active layer is 800 nm or more.

[0016] The value obtained by subtracting the absolute value of LUMO of the n-type semiconductor material from the work function of the surface in contact with the cathode-side surface of the active layer is 0.0 to 0.5 eV.

[0017] [2] The light detection element according to [1], wherein the n-type semiconductor material has an absolute value of LUMO of 2.0 eV to 10.0 eV.

[0018] [3] The light detection element according to [1] or [2], wherein the n-type semiconductor material is a fullerene derivative.

[0019] [4] The light detection element according to [3], wherein the fullerene derivative is C60PCBM, bisC60PCBM, C70IPH or C70PCBM.

[0020] [5] The photodetection element according to any one of [1] to [4], wherein a work function of a surface in contact with a cathode-side surface of the active layer is 2.0 eV to 10.0 eV.

[0021] [6] The photodetection element according to any one of [1] to [5], wherein an electron transport layer is included between the cathode and the active layer, and the surface in contact with the cathode-side surface of the active layer is a surface of the electron transport layer.

[0022] [7] The light detection element according to [6], wherein the electron transport layer contains a metal oxide, a metal hydroxide, or a metal alkoxide.

[0023] [8] The light detection element according to [7], wherein the electron transport layer includes a metal oxide containing zinc or titanium, a metal hydroxide containing zinc or titanium, or a metal alkoxide containing zinc or titanium.

[0024] [9] The light detecting element according to [6], wherein the electron transport layer contains a compound having an alkylene structure.

[0025]

[10] The light detection element according to [9], wherein the compound having an alkylene structure is a polyalkyleneimine or a derivative thereof.

[0026]

[11] The light detection element according to

[10] , wherein the polyalkyleneimine or its derivative is polyethyleneimine or its derivative.

[0027]

[12] The photodetection element as described in any one of [1] to [5], wherein the cathode is in direct contact with the active layer, and the surface in contact with the cathode-side surface of the active layer is the cathode surface.

[0028]

[13] An image sensor comprising the light detection element according to any one of [1] to

[12] .

[0029]

[14] A fingerprint recognition device comprising a fingerprint detection unit including the light detection element according to any one of [1] to

[12] .

[0030] Effects of the Invention

[0031] According to the present invention, it is possible to provide a photodetection element having reduced dark current and improved external quantum efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of a photoelectric conversion element (light detection element).

[0033] Figure 2 It is a diagram schematically showing a configuration example of an image detection unit.

[0034] Figure 3 It is a diagram schematically showing a configuration example of a fingerprint detection unit.

[0035] Figure 4 It is a graph showing the relationship between the thickness of the active layer and the external quantum efficiency (EQE) and dark current (Jd) of a light detection element (Examples 1 to 7, 48, Comparative Example 1) manufactured using C60PCBM as the n-type semiconductor contained in the active layer and the electron transport layer 1 as the electron transport layer.

[0036] Figure 5 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the light detecting elements (Examples 8, 9, and Comparative Example 3) manufactured using C60PCBM as the n-type semiconductor contained in the active layer and the electron transport layer 2 as the electron transport layer.

[0037] Figure 6It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the photodetection elements (Examples 10 to 13, Comparative Example 4) manufactured using C60PCBM as the n-type semiconductor contained in the active layer and the electron transport layer 3 as the electron transport layer.

[0038] Figure 7 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the photodetection elements (Examples 14 to 16, Comparative Example 5) manufactured using C60PCBM as the n-type semiconductor contained in the active layer and the electron transport layer 4 as the electron transport layer.

[0039] Figure 8 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the light detecting elements (Examples 17 to 20) manufactured using C60PCBM as the n-type semiconductor contained in the active layer and the electron transport layer 5 as the electron transport layer.

[0040] Fig. 9 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the light detection element (Examples 21 and 22) manufactured using C60PCBM as the n-type semiconductor contained in the active layer and the electron transport layer 6 as the electron transport layer.

[0041] Fig.10 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the photodetection elements (Examples 23 to 25, Comparative Example 6) manufactured without an electron transport layer using C60PCBM as the n-type semiconductor contained in the active layer.

[0042] Fig.11 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the light detection elements (Comparative Examples 7 to 10) manufactured using C60PCBM as the n-type semiconductor contained in the active layer and the electron transport layer 7 as the electron transport layer.

[0043] Fig.12 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the light detection elements (Comparative Examples 11 to 13) manufactured using C60PCBM as the n-type semiconductor contained in the active layer and the electron transport layer 8 as the electron transport layer.

[0044] Fig.13 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the light detection elements (Examples 26, 27, and Comparative Example 14) manufactured using bis-C60PCBM as the n-type semiconductor included in the active layer and the electron transport layer 7 as the electron transport layer.

[0045] Fig.14It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the light detection element (Examples 28, 29, Comparative Example 15) manufactured using bis-C60PCBM as the n-type semiconductor contained in the active layer and the electron transport layer 8 as the electron transport layer.

[0046] Fig.15 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the light detection element (Examples 30, 31, Comparative Example 16) manufactured using bis-C60PCBM as the n-type semiconductor contained in the active layer and the electron transport layer 1 as the electron transport layer.

[0047] Fig.16 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the light detection element (Examples 32 to 34, Comparative Example 17) manufactured using bis-C60PCBM as the n-type semiconductor contained in the active layer and the electron transport layer 2 as the electron transport layer.

[0048] Fig.17 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the light detecting element (Examples 35 and 36) manufactured using C70IPH as the n-type semiconductor included in the active layer and the electron transport layer 1 as the electron transport layer.

[0049] Fig.18 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of a light detection element (Examples 37 and 38) manufactured using C70IPH as an n-type semiconductor included in the active layer and using the electron transport layer 2 as the electron transport layer.

[0050] Fig.19 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the light detecting elements (Examples 39 to 41) manufactured in a manner without an electron transport layer using C70IPH as the n-type semiconductor included in the active layer.

[0051] Fig. 20 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the light detecting elements (Comparative Examples 18 to 20) manufactured using C70IPH as the n-type semiconductor included in the active layer and the electron transport layer 7 as the electron transport layer.

[0052] Fig.21 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the light detecting elements (Comparative Examples 21 to 23) manufactured using C70IPH as the n-type semiconductor included in the active layer and the electron transport layer 8 as the electron transport layer.

[0053] Fig. 22It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the light detecting elements (Examples 42, 43, Comparative Example 24) manufactured using C70PCBM as the n-type semiconductor included in the active layer and the electron transport layer 1 as the electron transport layer.

[0054] Fig.23 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the light detecting elements (Examples 44, 45, Comparative Example 25) manufactured using C70PCBM as the n-type semiconductor included in the active layer and the electron transport layer 2 as the electron transport layer.

[0055] Fig.24 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of a light detection element (Examples 46, 47, Comparative Example 26) manufactured without an electron transport layer using C70IPH as an n-type semiconductor included in the active layer.

[0056] Fig.25 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the light detection elements (Comparative Examples 27 to 29) manufactured using C70PCBM as the n-type semiconductor included in the active layer and the electron transport layer 7 as the electron transport layer.

[0057] Fig.26 It is a graph showing the relationship between the thickness of the active layer and EQE and Jd of the photodetection elements (Comparative Examples 2, 30 to 32) manufactured using C70PCBM as the n-type semiconductor included in the active layer and the electron transport layer 8 as the electron transport layer. DETAILED DESCRIPTION

[0058] Hereinafter, the photoelectric conversion element of the embodiment of the present invention will be described with reference to the accompanying drawings. It should be noted that the accompanying drawings are only schematically showing the shape, size and configuration of the constituent elements to the extent that the invention can be understood. The present invention is not limited to the following description, and each constituent element can be appropriately changed within the scope of the gist of the present invention. In addition, the structure of the embodiment of the present invention is not necessarily limited to the manufacture or use of the configuration shown in the accompanying drawings. In each figure described below, the same constituent element is sometimes attached with the same figure mark, and its description is omitted.

[0059] Here, first, terms commonly used in the following description will be described.

[0060] A "polymer compound" refers to a polymer having a molecular weight distribution and a polystyrene-equivalent number average molecular weight of 1×10 3 Above 1×10 8 The following polymers: The total amount of the structural units contained in the polymer compound is 100 mol%.

[0061] The term "structural unit" refers to a unit existing at least one unit in a polymer compound.

[0062] The "hydrogen atom" may be a protium atom or a deuterium atom.

[0063] The "halogen atom" includes a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[0064] The term “having or not having a substituent” includes two aspects: the case where all hydrogen atoms constituting the compound or group are unsubstituted, and the case where part or all of one or more hydrogen atoms are substituted with a substituent.

[0065] Unless otherwise specified, "alkyl" may be any of linear, branched, and cyclic. The number of carbon atoms in a linear alkyl group, excluding the number of carbon atoms in the substituent, is usually 1 to 50, preferably 1 to 30, and more preferably 1 to 20. The number of carbon atoms in a branched or cyclic alkyl group, excluding the number of carbon atoms in the substituent, is usually 3 to 50, preferably 3 to 30, and more preferably 4 to 20.

[0066] The alkyl group may or may not have a substituent. Specific examples of the alkyl group include 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, eicosyl and other alkyl groups, trifluoromethyl, pentafluoroethyl, perfluorobutyl, perfluorohexyl, perfluorooctyl, 3-phenylpropyl, 3-(4-methylphenyl)propyl, 3-(3,5-di-n-hexylphenyl)propyl, 6-ethoxyhexyl and other alkyl groups having substituents.

[0067] The "aryl group" refers to an atomic group remaining after removing one hydrogen atom directly bonded to a carbon atom constituting a ring from an aromatic hydrocarbon which may have a substituent.

[0068] The aryl group may have a substituent. Specific examples of the aryl group include phenyl, 1-naphthyl, 2-naphthyl, 1-anthryl, 2-anthryl, 9-anthryl, 1-pyrenyl, 2-pyrenyl, 4-pyrenyl, 2-fluorenyl, 3-fluorenyl, 4-fluorenyl, 2-phenylphenyl, 3-phenylphenyl, 4-phenylphenyl, and groups having substituents such as alkyl, alkoxy, aryl, and fluorine atoms.

[0069] The "alkoxy group" may be any of linear, branched, and cyclic. The number of carbon atoms in a linear alkoxy group is usually 1 to 40, preferably 1 to 10, excluding the number of carbon atoms in the substituent. The number of carbon atoms in a branched or cyclic alkoxy group is usually 3 to 40, preferably 4 to 10, excluding the number of carbon atoms in the substituent.

[0070] The alkoxy group may be substituted. Specific examples of the alkoxy group include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, n-pentyloxy, n-hexyloxy, cyclohexyloxy, n-heptyloxy, n-octyloxy, 2-ethylhexyloxy, n-nonyloxy, n-decyloxy, 3,7-dimethyloctyloxy and lauryloxy.

[0071] The number of carbon atoms in the "aryloxy group" is usually 6 to 60, preferably 6 to 48, not including the number of carbon atoms in the substituent.

[0072] The aryloxy group may be substituted. Specific examples of the aryloxy group include phenoxy, 1-naphthyloxy, 2-naphthyloxy, 1-anthryloxy, 9-anthryloxy, 1-pyreneoxy, and groups having a substituent such as an alkyl group, an alkoxy group, or a fluorine atom.

[0073] The "alkylthio group" may be any of linear, branched, and cyclic. The number of carbon atoms in a linear alkylthio group excluding the number of carbon atoms in the substituent is usually 1 to 40, preferably 1 to 10. The number of carbon atoms in a branched or cyclic alkylthio group excluding the number of carbon atoms in the substituent is usually 3 to 40, preferably 4 to 10.

[0074] The alkylthio group may be substituted. Specific examples of the alkylthio group include methylthio, ethylthio, propylthio, isopropylthio, butylthio, isobutylthio, tert-butylthio, pentylthio, hexylthio, cyclohexylthio, heptylthio, octylthio, 2-ethylhexylthio, nonylthio, decylthio, 3,7-dimethyloctylthio, laurylthio and trifluoromethylthio.

[0075] The carbon number of the "arylthio group" is usually 6 to 60, preferably 6 to 48, not including the carbon number of the substituent.

[0076] The arylthio group may have a substituent. Examples of the arylthio group include a phenylthio group, a C1-C12 alkoxyphenylthio group (here, "C1-C12" means that the carbon number of the group recorded immediately thereafter is 1-12. The same applies hereinafter), a C1-C12 alkylphenylthio group, a 1-naphthylthio group, a 2-naphthylthio group, and a pentafluorophenylthio group.

[0077] "p-valent heterocyclic group" (p represents an integer greater than 1) refers to an atomic group remaining after removing p hydrogen atoms directly bonded to carbon atoms or heteroatoms constituting the ring from a heterocyclic compound which may or may not have a substituent. Among the p-valent heterocyclic groups, "p-valent aromatic heterocyclic group" is preferred. "p-valent aromatic heterocyclic group" refers to an atomic group remaining after removing p hydrogen atoms directly bonded to carbon atoms or heteroatoms constituting the ring from an aromatic heterocyclic compound which may or may not have a substituent.

[0078] 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 monovalent heterocyclic group, a substituted amino group, an acyl group, an imide residue, an amide group, an imide group, a substituted oxycarbonyl group, an alkenyl group, an alkynyl group, a cyano group, and a nitro group.

[0079] The aromatic heterocyclic compound includes compounds in which the heterocycle itself exhibits aromaticity and compounds in which the heterocycle itself does not exhibit aromaticity but an aromatic ring is fused to the heterocycle.

[0080] Among the aromatic heterocyclic compounds, specific examples of compounds in which the heterocycle itself exhibits aromaticity include oxadiazole, thiadiazole, thiazole, oxazole, thiophene, pyrrole, phosphole, furan, pyridine, pyrazine, pyrimidine, triazine, pyridazine, quinoline, isoquinoline, carbazole and dibenzophosphole.

[0081] Among the aromatic heterocyclic compounds, specific examples of compounds in which the aromatic heterocyclic ring itself does not exhibit aromaticity but an aromatic ring is condensed on the heterocyclic ring include phenoxazine, phenothiazine, dibenzoborole, dibenzosilole and benzopyran.

[0082] The monovalent heterocyclic group has usually 2 to 60 carbon atoms, preferably 4 to 20 carbon atoms, excluding the carbon atoms of the substituent.

[0083] The monovalent heterocyclic group may have a substituent. Specific examples of the monovalent 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 triazine group, and a group having a substituent such as an alkyl group or an alkoxy group.

[0084] "Substituted amino group" 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 monovalent heterocyclic group. As the substituent, an alkyl group, an aryl group, or a monovalent heterocyclic group is preferred. The number of carbon atoms in the substituted amino group is usually 2 to 30.

[0085] Examples of the substituted amino group include dialkylamino groups such as dimethylamino and diethylamino groups, and diarylamino groups such as diphenylamino groups, bis(4-methylphenyl)amino groups, bis(4-tert-butylphenyl)amino groups, and bis(3,5-di-tert-butylphenyl)amino groups.

[0086] The carbon number of the "acyl group" is usually about 2 to 20, preferably 2 to 18. Specific examples of the acyl group include acetyl, propionyl, butyryl, isobutyryl, pivaloyl, benzoyl, trifluoroacetyl and pentafluorobenzoyl.

[0087] "Imine residue" refers to an atomic group remaining after removing a hydrogen atom directly bonded to a carbon atom or a nitrogen atom constituting a carbon-nitrogen double bond from an imine compound. "Imine compound" refers to an organic compound having a carbon-nitrogen double bond in a molecule. Examples of imine compounds include aldimine, ketimines, and compounds in which the hydrogen atom bonded to the nitrogen atom constituting a carbon-nitrogen double bond in aldimine is substituted with an alkyl group or the like.

[0088] The imine residue generally has about 2 to 20 carbon atoms, and preferably has 2 to 18 carbon atoms. Examples of the imine residue include groups represented by the following structural formulas.

[0089] [Chemistry 1]

[0090]

[0091] "Acylamide" refers to an atomic group remaining after removing one hydrogen atom bonded to a nitrogen atom from an amide. The number of carbon atoms in an amide is usually about 1 to 20, preferably 1 to 18. Specific examples of amide include formamide, acetamide, propionamide, butyramide, benzamide, trifluoroacetamide, pentafluorobenzamide, diformamide, diacetamide, dipropionamide, dibutyramide, dibenzamide, di(trifluoroacetamide) and di(pentafluorobenzamide).

[0092] The "acylimido group" refers to an atomic group remaining after removing one hydrogen atom bonded to a nitrogen atom from an imide. The number of carbon atoms in the acylimido group is usually about 4 to 20. Specific examples of the acylimido group include groups represented by the following structural formulas.

[0093] [Chemistry 2]

[0094]

[0095] The "substituted oxycarbonyl group" refers to a group represented by R'-O-(C=O)-.

[0096] Here, R' represents an alkyl group, an aryl group, an aralkyl group or a monovalent heterocyclic group.

[0097] The substituted oxycarbonyl group usually has about 2 to 60 carbon atoms, preferably 2 to 48 carbon atoms.

[0098] Specific examples of the substituted oxycarbonyl group include methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, isobutoxycarbonyl, tert-butoxycarbonyl, pentyloxycarbonyl, hexyloxycarbonyl, cyclohexyloxycarbonyl, heptyloxycarbonyl, octyloxycarbonyl, 2-ethylhexyloxycarbonyl, nonyloxycarbonyl, decyloxycarbonyl, 3,7-dimethyloctyloxycarbonyl, dodecyloxycarbonyl, trifluoromethoxycarbonyl, pentafluoroethoxycarbonyl, perfluorobutoxycarbonyl, perfluorohexyloxycarbonyl, perfluorooctyloxycarbonyl, phenoxycarbonyl, naphthoxycarbonyl and pyridyloxycarbonyl.

[0099] The "alkenyl group" may be any of linear, branched, and cyclic. The number of carbon atoms in a linear alkenyl group is usually 2 to 30, preferably 3 to 20, excluding the number of carbon atoms in the substituent. The number of carbon atoms in a branched or cyclic alkenyl group is usually 3 to 30, preferably 4 to 20, excluding the number of carbon atoms in the substituent.

[0100] The alkenyl group may have a substituent. Specific examples of the alkenyl group include vinyl, 1-propenyl, 2-propenyl, 2-butenyl, 3-butenyl, 3-pentenyl, 4-pentenyl, 1-hexenyl, 5-hexenyl, 7-octenyl, and groups having substituents such as alkyl and alkoxy groups.

[0101] The "alkynyl group" may be any of linear, branched, and cyclic. The number of carbon atoms in a linear alkynyl group, excluding the number of carbon atoms in the substituent, is usually 2 to 20, preferably 3 to 20. The number of carbon atoms in a branched or cyclic alkynyl group, excluding the number of carbon atoms in the substituent, is usually 4 to 30, preferably 4 to 20.

[0102] The alkynyl group may have a substituent. Specific examples of the alkynyl group include ethynyl, 1-propynyl, 2-propynyl, 2-butynyl, 3-butynyl, 3-pentynyl, 4-pentynyl, 1-hexynyl, 5-hexynyl, and groups having substituents such as alkyl and alkoxy groups.

[0103] [1. Light detection element]

[0104] The light detection element (photoelectric conversion element) of this embodiment includes: an anode; a cathode; and an active layer arranged between the anode and the cathode and including a p-type semiconductor material and an n-type semiconductor material, the thickness of the active layer is greater than 800nm, and the work function of the surface in contact with the cathode side surface of the active layer minus the absolute value of the LUMO of the above-mentioned n-type semiconductor material is 0.0~0.5eV.

[0105] Here, "LUMO" (Lowest Unoccupied Molecular Orbital) refers to the lowest unoccupied molecular orbital.

[0106] The LUMO level of an n-type semiconductor material can be estimated from a value measured by cyclic voltammetry (CV). CV measurement for evaluating the LUMO level can be performed, for example, according to the method described in Advanced Materials, Vol. 18, 2006, pp. 789-794.

[0107] <Configuration Example of Photoelectric Conversion Element (Photodetection Element)>

[0108] Hereinafter, the photoelectric conversion element (light detection element) of the embodiment of the present invention will be described with reference to the accompanying drawings. It should be noted that the accompanying drawings are merely schematic illustrations of the shapes, sizes and configurations of the constituent elements to the extent that the invention can be understood. The present invention is not limited to the following description, and each constituent element may be appropriately changed within the scope of the gist of the present invention. In addition, the structure of the embodiment of the present invention is not necessarily limited to being manufactured or used in the configuration shown in the accompanying drawings. In the various figures described below, the same constituent element is sometimes given the same figure mark, and its description is omitted.

[0109] Reference Figure 1 , the following describes possible configuration examples of the photoelectric conversion element (photodetection element) of this embodiment. It should be noted that here, the following describes a configuration example of a photoelectric conversion element (photodetection element) of a so-called reverse stacked structure.

[0110] The light detecting element according to the embodiment of the present invention may or may not include an electron transport layer. The light detecting element according to the embodiment of the present invention including an electron transport layer may have, for example Figure 1 The composition is schematically shown in FIG. Figure 1 In the embodiment, the light detecting element 10 is provided on a supporting substrate 11, for example. The light detecting element 10 comprises: a cathode 12 provided in contact with the supporting substrate 11; an electron transport layer 13 provided 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 in contact with the active layer 14; and an anode 16 provided in contact with the hole transport layer 15. In this configuration example, there is further provided a sealing substrate 17 provided in contact with the anode. In the light detecting element of the embodiment of the present invention without including an electron transport layer, for example Figure 1 In the embodiment, the electron transport layer 13 is not present, and the cathode 12 and the active layer 14 may be in contact with each other.

[0111] Hereinafter, constituent elements that may be included in the photodetection element of the present embodiment will be described in detail.

[0112] (Substrate)

[0113] The light detection element is usually formed on a substrate (support substrate or sealing substrate). A pair of electrodes including a cathode and an anode are usually formed on the substrate. The material of the substrate is not particularly limited as long as it is a material that does not undergo chemical changes when forming a layer including, in particular, an organic compound.

[0114] As the material of the substrate, for example, glass, plastic, polymer film, silicon can be cited. In the case of an opaque substrate, it is preferred that the electrode on the opposite side to the electrode disposed on the opaque substrate side (i.e., the electrode on the side away from the opaque substrate) is a transparent or translucent electrode.

[0115] (electrode)

[0116] The light detection element includes an anode and a cathode as a pair of electrodes. At least one of the anode and the cathode is preferably a transparent or semi-transparent electrode for incident light.

[0117] As the material of the transparent or translucent electrode, for example, conductive metal oxide film, translucent metal film, etc. can be cited. As the material of the electrode, specifically, conductive materials such as indium oxide, zinc oxide, tin oxide and indium tin oxide (ITO), indium zinc oxide (IZO), NESA, gold, platinum, silver, copper can be cited. As the material of the transparent or translucent electrode, ITO, IZO, tin oxide are preferred. In addition, as the electrode, a transparent conductive film using organic compounds such as polyaniline and its derivatives, polythiophene and its derivatives as the material can be adopted. The transparent or translucent electrode can be an anode or a cathode.

[0118] If one of a pair of electrodes is transparent or translucent, the other electrode can be an electrode with low light transmittance. As materials for electrodes with low light transmittance, metals and conductive polymers can be cited, for example. Specific examples of materials for electrodes with 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, and ytterbium, and alloys of two or more of these metals; or alloys of one or more of these metals with one or more of the 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, polythiophene and its derivatives. As alloys, magnesium-silver alloys, magnesium-indium alloys, magnesium-aluminum alloys, indium-silver alloys, lithium-aluminum alloys, lithium-magnesium alloys, lithium-indium alloys, and calcium-aluminum alloys can be cited.

[0119] As a method for forming the electrode, any suitable method known in the art can be used, such as vacuum deposition, sputtering, ion plating, coating methods such as slit coating or spin coating, and plating methods.

[0120] (cathode)

[0121] The cathode can usually be formed on a substrate (such as a supporting substrate or a sealing substrate, preferably a supporting substrate). The cathode can be a transparent or translucent electrode, or an electrode with low light transmittance. When the light detection element needs to be translucent, the cathode is preferably a transparent or translucent electrode. When the cathode is a transparent or translucent electrode, the materials for the cathode include the materials for the above-mentioned transparent or translucent electrodes. When the cathode is an electrode with low light transmittance, the materials for the cathode include the materials for the above-mentioned electrodes with low light transmittance.

[0122] As a method for forming the cathode, for example, the method for forming the above-mentioned electrode can be mentioned.

[0123] There is no special limitation on the thickness of the cathode, for example, it can be 1000nm to 1nm. When extracting light energy in the form of electrical energy, a sufficiently low resistance is required, so the thickness of the cathode is preferably 500nm to 100nm. Especially when used in a photodetector, high transmittance is required rather than resistance, so the thickness of the cathode is more preferably 200nm to 5nm.

[0124] After the cathode is formed, in order to make the work function of the surface in contact with the cathode side surface of the active layer described later be an appropriate value, the cathode on the substrate may be surface treated or not. In the case where the light detection element includes the electron transport layer described later, after the cathode is formed, the cathode on the substrate may be surface treated or not, preferably surface treated. In the case where the light detection element does not include the electron transport layer described later (for example, when the cathode is in direct contact with the active layer described later), after the cathode is formed, the cathode on the substrate may be surface treated or not, preferably not. As a surface treatment, any suitable surface treatment known to the structure may be used, such as corona discharge treatment, oxygen plasma treatment, ultraviolet ozone treatment and other physical treatments, cleaning treatments using water or organic solvents, acid cleaning treatments and other chemical treatments.

[0125] (anode)

[0126] The material and formation method of the anode may be the same as those described above for the electrode.

[0127] (Active layer)

[0128] 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 materials and n-type semiconductor materials are described below). The p-type semiconductor material and the n-type semiconductor material can be relatively determined based on the energy level of the HOMO or the energy level of the LUMO of the selected compound.

[0129] In this embodiment, from the perspective of reducing dark current, the thickness of the active layer is preferably thicker. In addition, the prior art shows a tendency that the external quantum efficiency decreases due to the thickness of the active layer becoming thicker. In this embodiment, unlike the prior art, it is shown that even if the thickness of the active layer becomes thicker, the external quantum efficiency does not decrease. Therefore, from the perspective of obtaining high sensitivity characteristics through low dark current and high external quantum efficiency, the thickness of the active layer is preferably thicker. The thickness of the active layer is 800nm ​​or more, preferably 800nm ​​or more and 10000nm or less. In order to obtain a smooth film after the coating film is dried, it is more preferably 800nm ​​or more and 3500nm or less.

[0130] Here, the “external quantum efficiency (EQE)” specifically refers to a value expressing the ratio (%) of the number of electrons that can be extracted to the outside of the photodetection element among the generated electrons to the number of photons irradiating the photodetection element.

[0131] The external quantum efficiency (EQE) of the photodetection element can be evaluated by, for example, the following method.

[0132] While a voltage (e.g., -2 V) is applied to the light detection element, a spectral sensitivity measuring device is used to irradiate the light detection element with light of a specific wavelength (e.g., light of a wavelength of 850 nm, which is the maximum absorption wavelength of the polymer compound P-1, and a photon number of 1.0×10 16 ), measure the current value of the generated current, and use the following formula to calculate the measured value of EQE.

[0133] EQE(%)=(S×1240 / λ)×100

[0134] S: Light receiving sensitivity (A / W), λ: Wavelength (nm)

[0135] The active layer can be preferably formed by a coating method. Details of the p-type semiconductor material and n-type semiconductor material that can be included in the active layer and the method for forming the active layer are described below.

[0136] (Electron Transport Layer)

[0137] The light detecting element of this embodiment can be Figure 1The electron transport layer may be included as an intermediate layer (a component for improving characteristics) between the cathode and the active layer, or may not be included. When the light detection element of this embodiment does not include an electron transport layer, the cathode and the active layer may be in direct contact.

[0138] The electron transport layer includes an electron transport material. As the electron transport material, any suitable material that helps to move electrons in the layer constituting the light detection element, and any suitable material that adjusts (for example, reduces or increases, preferably reduces) the work function can be cited. As the electron transport material, for example, metal compounds and compounds having an alkylene structure can be cited.

[0139] Examples of metal compounds include metal oxides, metal hydroxides, and metal alkoxides. The metal compound may preferably be a metal oxide, metal hydroxide, or metal alkoxide containing a divalent or higher metal, and more preferably may be a metal oxide, metal hydroxide, or metal alkoxide containing zinc or titanium. Examples of metal alkoxides include metal methoxides, metal ethoxides, metal propoxides, metal isopropoxides, metal n-butoxides, metal sec-butoxides, metal isobutoxides, and metal tert-butoxides.

[0140] 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 preferred, and zinc oxide is preferred among them.

[0141] Examples of the metal hydroxide include zinc hydroxide, titanium hydroxide, and niobium hydroxide. As the metal hydroxide, a metal hydroxide containing zinc or titanium is preferred, and titanium hydroxide is preferred among them.

[0142] As the metal alkoxide, a metal alkoxide containing titanium is preferred, and among them, titanium (IV) isopropoxide is preferred.

[0143] Examples of compounds having an alkylene structure include polyalkyleneimines and their derivatives. Examples of polyalkyleneimines and their derivatives include polymers obtained by polymerizing one or more of alkyleneimines having 2 to 8 carbon atoms, particularly alkyleneimines having 2 to 4 carbon atoms, such as ethyleneimine, propyleneimine, butyleneimine, dimethylethyleneimine, pentyleneimine, hexyleneimine, heptyleneimine, and octyleneimine by conventional methods, and polymers chemically modified by reacting these polymers with various compounds. Polyalkyleneimines and their derivatives are preferably polyethyleneimine ethoxylates (PEIE: ethoxylated polyethyleneimine), which are modified products containing polyethyleneimine (PEI) and polyalkyleneimine as the main chain and having ethylene oxide added to the nitrogen atom in the main chain.

[0144] The electron transport material can be formed by a vacuum film forming method or by coating the cathode on the substrate in a liquid manner (coating liquid for forming an electron transport layer). The coating liquid for forming the electron transport layer can be a solution, an emulsion (emulsion), a suspension (suspension) or a dispersion. In the coating liquid for forming the electron transport layer, the electron transport material can be microparticles or nanoparticles. As a medium for dissolving, emulsifying, suspending, dispersing or diluting the electron transport material (hereinafter collectively referred to as "solvent"), hydrocarbon solvents such as toluene, xylene, mesitylene, tetralin, decalin, bicyclohexane, n-butylbenzene, sec-butylbenzene, tert-butylbenzene, etc. can be cited; halogenated saturated hydrocarbon solvents such as carbon tetrachloride, chloroform, dichloromethane, dichloroethane, chlorobutyl, bromobutyl, chloropentane, bromopentane, hexyl chloride, bromohexane, chlorocyclohexane, bromocyclohexane, etc.; halogenated aromatic hydrocarbon solvents such as chlorobenzene, dichlorobenzene, trichlorobenzene, etc.; ether solvents such as tetrahydrofuran and tetrahydropyran; water, alcohol, etc. As specific examples of alcohol, methanol, ethanol, isopropanol, butanol, 1-pentanol, 2-pentanol, 3-pentanol, ethylene glycol, propylene glycol, butoxyethanol, methoxybutanol, etc. can be cited. The coating solution can contain a single solvent, or it can contain two or more solvents, or it can contain two or more of the above solvents.

[0145] As a method for applying the coating liquid for forming an electron transport layer, any appropriate coating method can be used.

[0146] As the coating method, slit coating, blade coating, spin coating, micro gravure coating, gravure printing, rod coating, inkjet printing, nozzle coating or capillary coating is preferred, slit coating, blade coating, spin coating, capillary coating or rod coating is more preferred, and slit coating, blade coating or spin coating is further preferred.

[0147] After the coating of the coating liquid for forming the electron transport layer, the solvent is removed (dried) from the coating film of the coating liquid for forming the electron transport layer, thereby forming the electron transport layer. As a method for removing the solvent from the coating film of the coating liquid, that is, a method for removing the solvent from the coating film and curing, any suitable method can be used. As an example of a method for removing the solvent, a method of directly heating using a hot plate (for example, heating at 40°C to 300°C for 1 minute to 60 minutes), a hot air drying method, an infrared heating drying method, a flash lamp annealing drying method, a reduced pressure drying method and the like can be cited.

[0148] The thickness of the electron transport layer can be formed to a desired thickness by appropriately adjusting the solid content concentration in the electron transport layer-forming coating liquid and the conditions of coating and / or solvent removal.

[0149] Specifically, for example, when the coating method is a blade coating method, the thickness of the electron transport layer can be adjusted to any appropriate thickness by adjusting the characteristic conditions of the coating liquid such as the concentration of the components in the coating liquid used (viscosity of the coating liquid) and various implementation conditions in the blade coating method.

[0150] For example, in order to adjust the thickness of the electron transport layer to be thicker, the concentration of the components in the coating solution may be increased, and / or the gap between the substrate and the blade in the blade coating method may be increased to increase the coating speed.

[0151] The thickness of the electron transport layer may be, for example, 0.1 nm to 300 nm, preferably 0.1 nm to 100 nm, and more preferably 1 nm to 100 nm.

[0152] After the electron transport layer is formed, the electron transport layer may or may not be subjected to surface treatment. As the surface treatment, any suitable surface treatment method known in the art may be used, such as physical treatment such as corona discharge treatment, oxygen plasma treatment, ultraviolet ozone treatment, cleaning treatment with water or an organic solvent, chemical treatment such as acid cleaning treatment, etc.

[0153] In the light detection element of this embodiment, the work function of the surface in contact with the cathode side surface of the active layer can be appropriately adjusted so that the value obtained by subtracting the absolute value of LUMO of the n-type semiconductor material from the work function of the surface in contact with the cathode side surface of the active layer is 0.0 to 0.5 eV.

[0154] In the case where the light detection element includes an electron transport layer, the surface in contact with the cathode side surface of the active layer is equivalent to the surface of the electron transport layer. In this case, by appropriately selecting the type of coating liquid for forming the electron transport layer, the coating method, the method of removing the solvent, the thickness of the electron transport layer, the surface treatment of the cathode on the substrate before applying the coating liquid for forming the electron transport layer, the surface treatment of the electron transport layer after the electron transport layer is formed, and other various conditions in the formation of the electron transport layer, the work function of the surface in contact with the cathode side surface of the active layer (i.e., the work function of the surface of the electron transport layer) can be adjusted to a desired value.

[0155] In the case where the light detection element does not include the electron transport layer described later (for example, when the cathode is in direct contact with the active layer), the surface in contact with the cathode side surface of the active layer is equivalent to the surface of the cathode. In this case, by appropriately selecting various conditions in the cathode formation such as the type of cathode material, the cathode formation method, the cathode thickness, and the surface treatment, the work function of the surface in contact with the cathode side surface of the active layer (i.e., the work function of the cathode surface) can be adjusted to a desired value.

[0156] The work function of the surface in contact with the cathode-side surface of the active layer may be, for example, 2.0 eV to 10.0 eV, preferably 3.0 eV to 7.5 eV, and more preferably 4.0 eV to 5.0 eV.

[0157] The work function can be evaluated (measured) using, for example, a conventionally known Kelvin probe apparatus (eg, FAC-2 manufactured by Riken Keiki Co., Ltd.) and gold (WF: 5.1 eV) as a calibration reference sample.

[0158] like Figure 1 As shown, the light detection element of this embodiment can have a hole transport layer between the anode and the active layer. The hole transport layer has the function of transporting holes from the active layer to the electrode. Since the hole transport layer has the function of blocking the flow of electrons to the electrode, it is sometimes also called an electron blocking layer.

[0159] 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.

[0160] The hole transport layer contains a hole transport material. Examples of the hole transport material include polythiophene and its derivatives, aromatic amine compounds, polymer compounds containing a structural unit having an aromatic amine residue, CuSCN, CuI, NiO, and molybdenum oxide (MoO3).

[0161] The intermediate layer can be formed by the same coating method as the active layer.

[0162] The light detection element of this embodiment is arranged on a substrate, and preferably has the following so-called reverse stacking structure: the intermediate layer is an electron transport layer and a hole transport layer, and the cathode, electron transport layer, active layer, hole transport layer and anode are stacked in sequence in a mutually contacting manner.

[0163] (other)

[0164] The light detecting element of this embodiment can be sealed by a sealing member such as a sealing substrate and a sealing material. As an example of the sealing member, for example, a combination of a cover glass having a recess and a sealing material can be cited.

[0165] The sealing member may have a layer structure of one or more layers. Therefore, examples of the sealing member include layer structures such as a gas barrier layer and a gas barrier film.

[0166] The layer structure of the sealing member 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). Examples of preferred materials for the layer structure include organic materials such as trifluoroethylene, polychlorotrifluoroethylene (PCTFE), polyimide, polycarbonate, polyethylene terephthalate, alicyclic polyolefin, ethylene-vinyl alcohol copolymer and other resins, and inorganic materials such as silicon oxide, silicon nitride, aluminum oxide, and diamond-like carbon.

[0167] According to the present invention, by making the thickness of the active layer greater than 800 nm and making the work function of the surface in contact with the cathode side surface of the active layer minus the absolute value of the LUMO of the above-mentioned n-type semiconductor material to be 0.0 to 0.5 eV, a light detection element with reduced dark current and improved external quantum efficiency can be realized.

[0168] <Application examples of light detection elements>

[0169] The light detection element according to the embodiment of the present invention described above can be suitably used in detection units included in various electronic devices such as workstations, personal computers, portable information terminals, entry and exit management systems, digital cameras, and medical equipment.

[0170] The light detection element of the present invention can be appropriately applied to image detection units (image sensors) for solid-state imaging devices such as X-ray imaging devices and CMOS image sensors, detection units for detecting specific local features of a biological body such as fingerprint detection units, face detection units, vein detection units and iris detection units, and detection units of optical biosensors such as pulse oximeters, etc., which are possessed by the electronic devices exemplified above.

[0171] Hereinafter, configuration examples of an image detection unit for a solid-state imaging device and a fingerprint detection unit for a biometric authentication device (fingerprint recognition device) among detection units to which the light detection element according to the embodiment of the present invention can be suitably applied will be described with reference to the drawings.

[0172] <Image Detection Unit>

[0173] Figure 2 It is a diagram schematically showing a configuration example of an image detection section for a solid-state imaging device.

[0174] The image detection unit 1 includes: a CMOS transistor substrate 20; an interlayer insulating film 30 arranged in a manner covering the CMOS transistor substrate 20; a photoelectric conversion element (light detection element) 10 of an embodiment of the present invention arranged on the interlayer insulating film 30; an interlayer wiring portion 32 arranged in a manner penetrating the interlayer insulating film 30 and electrically connecting the CMOS transistor substrate 20 and the photoelectric conversion element (light detection element) 10; a sealing layer 40 arranged in a manner covering the photoelectric conversion element (light detection element) 10; and a color filter 50 arranged on the sealing layer.

[0175] The CMOS transistor substrate 20 has any suitable configuration known in the art in accordance with the design.

[0176] The CMOS transistor substrate 20 includes transistors, capacitors, and the like formed within the thickness of the substrate, and includes functional elements such as CMOS transistor circuits (MOS transistor circuits) for realizing various functions.

[0177] Examples of the functional element include a floating diffusion element, a reset transistor, an output transistor, and a selection transistor.

[0178] By using such functional elements, wirings, etc., a signal readout circuit and the like are manufactured on the CMOS transistor substrate 20 .

[0179] The interlayer insulating film 30 may be made of any suitable insulating material known in the art, such as silicon oxide, insulating resin, etc. The interlayer wiring portion 32 may be made of any suitable conductive material (wiring material) known in the art, such as copper, tungsten, etc. The interlayer wiring portion 32 may be, for example, an in-hole wiring formed simultaneously with the formation of the wiring layer, or may be an embedded plug formed separately from the wiring layer.

[0180] The sealing layer 40 can be made of any suitable material known in the art, provided that it can prevent or suppress the penetration of harmful substances such as oxygen and water that may deteriorate the function of the photoelectric conversion element (photodetection element) 10. The sealing layer 40 can also be made of the sealing substrate 17 described above.

[0181] 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. In addition, as the color filter 50, a complementary color filter that can be thinner than the primary color filter can also be used. As the complementary color filter, for example, a color filter composed of three colors (yellow, cyan, magenta), three colors (yellow, cyan, transparent), three colors (yellow, transparent, magenta) and a combination of three colors (transparent, cyan, magenta) can be used. These color filters can adopt any suitable configuration corresponding to the design of the photoelectric conversion element (light detection element) 10 and the CMOS transistor substrate 20 under the condition that color image data can be generated.

[0182] The light received by the photoelectric conversion element (light detection element) 10 via the color filter 50 is converted by the photoelectric conversion element (light detection element) 10 into an electrical signal corresponding to the amount of received light, and is output to the outside of the photoelectric conversion element (light detection element) 10 via the electrode in the form of a received light signal, that is, an electrical signal corresponding to the photographed object.

[0183] Next, the received light signal output from the photoelectric conversion element (light detection element) 10 is input to the CMOS transistor substrate 20 via the interlayer wiring portion 32, is read out by a signal readout circuit made on the CMOS transistor substrate 20, and is processed by any other suitable existing known functional portion not shown, thereby generating image information based on the photographed object.

[0184] <Fingerprint Detection Section>

[0185] Figure 3 FIG. 1 is a diagram schematically showing a configuration example of a fingerprint detection unit integrally configured with a display device.

[0186] The display device 2 of the portable information terminal includes a fingerprint detection unit 100 including the photoelectric conversion element (light detection element) 10 according to 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.

[0187] In this configuration example, the fingerprint detection unit 100 is provided in a region substantially coinciding with the display region 200 a of the display panel unit 200 . In other words, the display panel unit 200 is integrally stacked above the fingerprint detection unit 100 .

[0188] When fingerprint detection is performed only in a partial area of ​​the display area 200 a , the fingerprint detection unit 100 may be provided only corresponding to the partial area.

[0189] The fingerprint detection unit 100 includes the photoelectric conversion element 10 of the embodiment of the present invention as a functional unit that performs substantial functions. The fingerprint detection unit 100 may include any suitable existing known components such as a protection film (not shown), a support substrate, a sealing substrate, a sealing component, a barrier film, a bandpass filter, and an infrared cut-off film in a manner corresponding to the design that can obtain the desired characteristics. The fingerprint detection unit 100 may also adopt the configuration of the image detection unit described above.

[0190] The photoelectric conversion element 10 may be included in the display region 200a in any manner. For example, two or more photoelectric conversion elements 10 may be arranged in a matrix.

[0191] As described above, the photoelectric conversion element 10 is provided on the supporting substrate 11 or the sealing substrate, and electrodes (anodes or cathodes) are provided on the supporting substrate 11 in a matrix form, for example.

[0192] The light received by the photoelectric conversion element 10 is converted into an electrical signal corresponding to the amount of received light by the photoelectric conversion element 10 and output to the outside of the photoelectric conversion element 10 via the electrode in the form of a received light signal, that is, an electrical signal corresponding to the photographed fingerprint.

[0193] In this configuration example, the display panel unit 200 is configured as an organic electroluminescent display panel (organic EL display panel) including a touch sensor panel. Instead of the organic EL display panel, the display panel unit 200 may be configured as a display panel having any suitable existing known configuration, such as a liquid crystal display panel including a light source such as a backlight.

[0194] The display panel unit 200 is provided on the fingerprint detection unit 100 described above. The display panel unit 200 includes an organic electroluminescent element (organic EL element) 220 as a functional unit that performs substantial functions. The display panel unit 200 may further include any suitable existing known components such as a glass substrate (support substrate 210 or sealing substrate 240), a sealing component, a barrier film, a polarizing plate such as a circular polarizing plate, and a touch sensor panel 230 in a manner corresponding to the desired characteristics.

[0195] In the configuration example described above, the organic EL element 220 is used as a light source for pixels in the display region 200 a and is also used as a light source for fingerprint imaging in the fingerprint detection unit 100 .

[0196] Here, the operation of the fingerprint detection unit 100 will be briefly described.

[0197] When performing fingerprint recognition, the fingerprint detection unit 100 detects the fingerprint using the light emitted from the organic EL element 220 of the display panel unit 200. Specifically, the light emitted from the organic EL element 220 is transmitted through the components existing between the organic EL element 220 and the photoelectric conversion element 10 of the fingerprint detection unit 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 unit 200 in the display area 200a. At least a portion of the light reflected by the finger surface is received by the photoelectric conversion element 10 through the components existing therebetween, and is converted into an electrical signal corresponding to the amount of light received by the photoelectric conversion element 10. Then, the converted electrical signal constitutes image information related to the fingerprint on the finger surface.

[0198] The portable information terminal including the display device 2 compares the obtained image information with fingerprint data for fingerprint recognition recorded in advance through any suitable procedure known in the art to perform fingerprint recognition.

[0199] [2. Method for manufacturing light detection element]

[0200] The method for manufacturing the light detection element of the present embodiment is not particularly limited. The light detection element can be manufactured by a forming method suitable for the material selected when forming each component.

[0201] Hereinafter, as an embodiment of the present invention, a method for manufacturing a light detecting element provided on a substrate (support substrate) and having a cathode, an optional electron transport layer, an active layer, a hole transport layer, and an anode in contact with each other in sequence will be described.

[0202] (Step of Preparing a Substrate)

[0203] In this step, a supporting substrate provided with a cathode is prepared.

[0204] The method of providing the cathode on the support substrate is not particularly limited. The cathode can be formed on the support substrate made of the above-mentioned materials by vacuum deposition, sputtering, ion plating, plating, or the like.

[0205] Alternatively, a supporting substrate provided with a cathode can be prepared by obtaining a substrate provided with a thin film made of the material of the electrode described above from the market, and patterning the conductive thin film as necessary to form a cathode.

[0206] (Step of Forming Electron Transport Layer)

[0207] The method for manufacturing a light detecting element including an electron transport layer may include a process of forming an electron transport layer disposed between the active layer and the cathode as an intermediate layer. As an example of an electron transport layer, a layer including the above-mentioned electron transport material can be cited. As an example of a method for forming an electron transport layer, the above-mentioned vacuum film forming method and coating method can be cited. As an example of materials (such as a coating liquid for forming an electron transport layer) and conditions used in the method for forming an electron transport layer, the above-mentioned materials and conditions can be cited.

[0208] The method for manufacturing a light detecting element of the present embodiment may further include a step of forming an electron transport layer after the step of preparing a supporting substrate provided with a cathode and before the step of forming an active layer.

[0209] (Active Layer Formation Step)

[0210] The active layer, which is a main component of the photoelectric conversion element of this embodiment, can be produced by a coating method using a coating liquid (ink).

[0211] Hereinafter, the step (i) and the step (ii) included in the step of forming the active layer which is the main constituent element of the photoelectric conversion element of the present invention will be described.

[0212] (Process (i))

[0213] As a method of applying the coating liquid to the coating object, any appropriate coating method can be used.

[0214] As the coating method, slit coating, blade coating, spin coating, micro gravure coating, gravure printing, rod coating, inkjet printing, nozzle coating or capillary coating is preferred, slit coating, spin coating, capillary coating or rod coating is more preferred, and slit coating or spin coating is further preferred.

[0215] The coating liquid for forming the active layer is applied to a coating object selected according to the photoelectric conversion element and its manufacturing method. The coating liquid for forming the active layer can be applied to the functional layer of the photoelectric conversion element in which the active layer may exist in the manufacturing process of the photoelectric conversion element. Therefore, the coating object of the coating liquid for forming the active layer varies according to the layer structure of the manufactured photoelectric conversion element and the order of layer formation. For example, in the case where the photoelectric conversion element is arranged on a substrate and has a layer structure in which an anode, a hole transport layer, an active layer, an electron transport layer, and a cathode are stacked, and the layer recorded on the right side is formed first, the coating object of the coating liquid for forming the active layer is the electron transport layer. In addition, for example, in the case where the photoelectric conversion element is arranged on a substrate and has a layer structure in which a cathode, an electron transport layer, an active layer, a hole transport layer, and an anode are stacked, and the layer recorded on the right side is formed first, the coating object of the coating liquid for forming the active layer is the hole transport layer.

[0216] (Step (ii))

[0217] As a method for removing the solvent from the coating film of the coating liquid, that is, a method for removing the solvent from the coating film and curing, any appropriate method can be used. Examples of the method for removing the solvent include a method of directly heating using 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.

[0218] The thickness of the active layer can be set to a desired thickness by appropriately adjusting the solid content concentration in the coating solution and the conditions of the above-mentioned step (i) and / or step (ii).

[0219] Specifically, for example, in the case where the coating method is a blade 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 the components in the coating liquid used (viscosity of the coating liquid) and various implementation conditions in the blade coating method.

[0220] For example, in order to adjust the thickness of the active layer to be thicker, the concentration of the components in the coating liquid may be increased, and / or the gap between the substrate and the blade in the blade coating method may be increased to increase the coating speed.

[0221] The process of forming the active layer may include other steps in addition to the above-mentioned steps (i) and (ii) without impairing the object and effect of the present invention.

[0222] The method for manufacturing a photodetecting element may be a method for manufacturing a photodetecting element including two or more active layers, or may be a method for repeating step (i) and step (ii) a plurality of times.

[0223] The coating liquid for forming the active layer may be a solution, or a dispersion such as a dispersion, an emulsion, or a suspension. The coating liquid for forming the active layer of the present embodiment contains a p-type semiconductor material, an n-type semiconductor material, and a solvent. The components of the coating liquid for forming the active layer are described below.

[0224] (p-type semiconductor material)

[0225] The p-type semiconductor material may be a low molecular compound or a high molecular compound.

[0226] Examples of the p-type semiconductor material that is a low molecular weight compound include phthalocyanine, metallophthalocyanine, porphyrin, metalloporphyrin, oligothiophene, tetracene, pentacene, and rubrene.

[0227] When the p-type semiconductor material is a polymer compound, the polymer compound has a predetermined weight average molecular weight in terms of polystyrene.

[0228] Here, the polystyrene-equivalent weight average molecular weight refers to a weight average molecular weight calculated using a standard sample of polystyrene by gel permeation chromatography (GPC).

[0229] From the viewpoint of solubility in a solvent, the polystyrene-equivalent weight average molecular weight of the p-type semiconductor material is preferably 20,000 to 200,000, more preferably 30,000 to 180,000, and even more preferably 40,000 to 150,000.

[0230] As p-type semiconductor materials that are polymer compounds, for example, polyvinylcarbazole and its derivatives, polysilane and its derivatives, polysiloxane derivatives containing an aromatic amine structure in the side chain or the main chain, polyaniline and its derivatives, polythiophene and its derivatives, polypyrrole and its derivatives, polyphenylene vinylene and its derivatives, polythiophenylene vinylene and its derivatives, polyfluorene and its derivatives, and the like can be cited.

[0231] As the p-type semiconductor material which is a polymer compound, a polymer compound including a structural unit having a thiophene skeleton is preferable.

[0232] The p-type semiconductor material is preferably a polymer compound including a structural unit represented by the following formula (I) and / or a structural unit represented by the following formula (II).

[0233] [Chemistry 3]

[0234]

[0235] In formula (I), Ar 1 and Ar 2represents a trivalent aromatic heterocyclic group, and Z represents a group represented by the following formula (Z-1) to formula (Z-7).

[0236] [Chemistry 4]

[0237] -Ar 3 - (II)

[0238] In formula (II), Ar 3 It represents a divalent aromatic heterocyclic group.

[0239] [Chemistry 5]

[0240]

[0241] In formulas (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 monovalent heterocyclic group, a substituted amino group, an acyl group, an imide residue, an amide group, an imide group, a substituted oxycarbonyl group, an alkenyl group, an alkynyl group, a cyano group, or a nitro group. In each of formulas (Z-1) to (Z-7), when there are two Rs, the two Rs may be the same or different from each other.

[0242] The structural unit represented by formula (I) is preferably a structural unit represented by the following formula (I-1).

[0243] [Chemistry 6]

[0244]

[0245] In the formula (I-1), Z has the same meaning as described above.

[0246] Examples of the structural unit represented by formula (I-1) include structural units represented by the following formulae (501) to (505).

[0247] [Chemistry 7]

[0248]

[0249] In the above formulae (501) to (505), R has the same meaning as above. When there are two Rs, the two Rs may be the same as or different from each other.

[0250] Ar 3 The divalent aromatic heterocyclic group represented by is usually 2 to 60 carbon atoms, preferably 4 to 60 carbon atoms, and more preferably 4 to 20 carbon atoms. 3 The divalent aromatic heterocyclic group represented by may have a substituent. 3Examples of substituents that the divalent aromatic heterocyclic group represented 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 monovalent heterocyclic group, a substituted amino group, an acyl group, an imide residue, an amide group, an imide group, a substituted oxycarbonyl group, an alkenyl group, an alkynyl group, a cyano group, and a nitro group.

[0251] As Ar 3 Examples of the divalent aromatic heterocyclic group represented by include groups represented by the following formulae (101) to (185).

[0252] [Chemistry 8]

[0253]

[0254] [Chemistry 9]

[0255]

[0256] [Chemistry 10]

[0257]

[0258] [Chemistry 11]

[0259]

[0260] In formulae (101) to (185), R has the same meaning as above. When there are two or more Rs, the two or more Rs may be the same or different from each other.

[0261] As the structural unit represented by the above formula (II), structural units represented by the following formulae (II-1) to (II-6) are preferred.

[0262] [Chemistry 12]

[0263]

[0264] In formula (II-1) to formula (II-6), X 1 and X 2 Each independently represents an oxygen atom or a sulfur atom, and R has the same meaning as above. When there are two or more Rs, the two or more Rs may be the same or different from each other.

[0265] From the viewpoint of the availability of the raw material compounds, X in Formula (II-1) to Formula (II-6) 1 and X 2 Preferably, they are all sulfur atoms.

[0266] The polymer compound as a p-type semiconductor material may contain two or more structural units of the formula (I), or may contain two or more structural units of the formula (II).

[0267] In order to improve solubility in a solvent, the polymer compound as a p-type semiconductor material may contain a structural unit represented by the following formula (III).

[0268] [Chemistry 13]

[0269] -Ar 4 - (III)

[0270] In formula (III), Ar 4 It represents an arylene group.

[0271] Ar 4 The arylene group represented here refers to the atomic group remaining after removing two hydrogen atoms from an aromatic hydrocarbon with or without a substituent. Aromatic hydrocarbons also include compounds having condensed rings, and compounds in which two or more selected from the group consisting of independent benzene rings and condensed rings are bonded directly or through a divalent group such as vinylene.

[0272] Examples of the substituent which the aromatic hydrocarbon may have include the same substituents as exemplified as the substituent which the heterocyclic compound may have.

[0273] The carbon number of the part excluding the substituent in the arylene group is usually 6 to 60, preferably 6 to 20. The carbon number of the arylene group including the substituent is usually about 6 to 100.

[0274] Examples of arylene groups include phenylene groups (for example, formulas 1 to 3 below), naphthalene diyl groups (for example, formulas 4 to 13 below), anthracene diyl groups (for example, formulas 14 to 19 below), biphenyl diyl groups (for example, formulas 20 to 25 below), terphenyl diyl groups (for example, formulas 26 to 28 below), condensed ring compound groups (for example, formulas 29 to 35 below), fluorene diyl groups (for example, formulas 36 to 38 below), and benzofluorene diyl groups (for example, formulas 39 to 46 below).

[0275] [Chemistry 14]

[0276]

[0277] [Chemistry 15]

[0278]

[0279] [Chemistry 16]

[0280]

[0281] [Chemistry 17]

[0282]

[0283] [Chemistry 18]

[0284]

[0285] [Chemistry 19]

[0286]

[0287] [Chemistry 20]

[0288]

[0289] [Chemistry 21]

[0290]

[0291] In Formulae 1 to 46, R has the same meaning as above. When there are two or more Rs, the two or more Rs may be the same as or different from each other.

[0292] The structural unit constituting the polymer compound serving as a p-type semiconductor material may be a structural unit formed by combining and linking two or more structural units selected from the structural unit represented by formula (I), the structural unit represented by formula (II) and the structural unit represented by formula (III).

[0293] In the case where a polymer compound serving as a p-type semiconductor material contains a structural unit represented by formula (I) and / or a structural unit represented by formula (II), when the amount of all structural units contained in the polymer compound is 100 mol%, the total amount of the structural units represented by formula (I) and the structural units represented by formula (II) is generally 20 mol% to 100 mol%, and is preferably 40 mol% to 100 mol%, and more preferably 50 mol% to 100 mol%, for the purpose of improving the charge transport properties of the p-type semiconductor material.

[0294] Specific examples of the polymer compound as the p-type semiconductor material include the polymer compounds represented by the following P-1 to P-6 (polymer compound P-1 to polymer compound P-6).

[0295] [Chemistry 22]

[0296]

[0297] [Chemistry 23]

[0298]

[0299] The coating liquid for forming the active layer may contain only one p-type semiconductor material, or may contain two or more p-type semiconductor materials in combination at any ratio.

[0300] (n-type semiconductor material)

[0301] The n-type semiconductor material can be appropriately selected as a material having a value of 0.0 to 0.5 eV obtained by subtracting the absolute value of the LUMO of the n-type semiconductor material from the work function of the surface in contact with the cathode side surface of the active layer. The absolute value of the LUMO of the n-type semiconductor material can be, for example, 2.0 eV to 10.0 eV, preferably 3.0 eV to 7.5 eV, and more preferably 4.0 eV to 5.0 eV. The LUMO of the n-type semiconductor material can be evaluated, for example, by the method described in Adv. Mater., 18, 789-794 (2006).

[0302] The n-type semiconductor material is preferably a fullerene derivative. A fullerene derivative refers to fullerene (C 60 Fullerene, C 70 Fullerene, C 84 A compound in which at least a portion of a fullerene is modified.

[0303] Examples of the fullerene derivative include compounds represented by the following formula (N-1) to formula (N-4).

[0304] [Chemistry 24]

[0305]

[0306] In formula (N-1) to formula (N-4), n represents an integer of 1 to 2, and parentheses represent that the number of structures enclosed by the parentheses is n. a represents an alkyl group, an aryl group, a monovalent heterocyclic group or a group having an ester structure. a They may be the same or different from each other. b represents an alkyl group or an aryl group. b They may be the same as or different from each other.

[0307] As R a Examples of the group having an ester structure include a group represented by the following formula (19).

[0308] [Chemistry 25]

[0309]

[0310] In formula (19), u1 represents an integer of 1 to 6. u2 represents an integer of 0 to 6. R c represents an alkyl group, an aryl group or a monovalent heterocyclic group.

[0311] As C 60 Examples of fullerene derivatives include the following compounds.

[0312] [Chemistry 26]

[0313]

[0314] As C 60 Preferred specific examples of fullerene derivatives include [6,6]-phenyl-C61 butyric acid methyl ester (C60PCBM, [6,6]-Phenyl C61 butyric acid methyl ester) and bis(1-[3-(methoxycarbonyl)propyl]-1-phenyl)-[6,6]C62 (bisC60PCBM, Bis(1-[3-(methoxycarbonyl)propyl]-1-phenyl)-[6,6]C62).

[0315] As C 70 Specific examples of the fullerene derivative include compounds represented by the following formula.

[0316] [Chemistry 27]

[0317]

[0318] Preferred specific examples of the C70 fullerene derivative include [6,6]-phenyl-C71-butyric acid methyl ester (C70PCBM, [6,6]-Phenyl-C71-butyric acid methyl ester) and indene-C70-propionic acid hexyl ester (C70IPH, indene-C70-propionic acid hexyl ester).

[0319] In addition, as C 84 Specific examples of fullerene derivatives include [6,6]phenyl-C85 butyric acid methyl ester (C84PCBM, [6,6]-Phenyl C85 butyric acid methyl ester).

[0320] The coating liquid for forming the active layer may contain only one n-type semiconductor material, or may contain two or more n-type semiconductor materials in combination at any ratio.

[0321] (Solvent)

[0322] The coating liquid for forming the active layer may contain only one solvent, or may contain two or more solvents in combination in any ratio. When the coating liquid for forming the active layer contains two or more solvents, it is preferred to contain a main solvent (referred to as the first solvent) as the main component and other additional solvents (referred to as the second solvent) added for the purpose of improving solubility, etc. The first solvent and the second solvent are described below.

[0323] (1) First solvent

[0324] The solvent can be selected in consideration of its solubility in the selected p-type semiconductor material and n-type semiconductor material and its characteristics (boiling point, etc.) corresponding to the drying conditions when forming the active layer.

[0325] The first solvent as the main solvent is preferably an aromatic hydrocarbon (hereinafter referred to as an aromatic hydrocarbon) which may have a substituent (alkyl group, halogen atom). The first solvent is preferably selected in consideration of the solubility of the selected p-type semiconductor material and n-type semiconductor material.

[0326] Examples of such aromatic hydrocarbons include toluene, xylenes (e.g., o-xylene, m-xylene, p-xylene), trimethylbenzenes (e.g., mesitylene, 1,2,4-trimethylbenzene (pseudocumene)), butylbenzenes (e.g., n-butylbenzene, sec-butylbenzene, tert-butylbenzene), methylnaphthalene (e.g., 1-methylnaphthalene), tetralin, indane, chlorobenzene, and dichlorobenzene (o-dichlorobenzene).

[0327] The first solvent may consist of only one kind of aromatic hydrocarbon or may consist of two or more kinds of aromatic hydrocarbons. The first solvent preferably consists of only one kind of aromatic hydrocarbon.

[0328] The first solvent preferably contains one or more selected from the group consisting of toluene, o-xylene, m-xylene, p-xylene, mesitylene, pseudocumene, n-butylbenzene, sec-butylbenzene, tert-butylbenzene, methylnaphthalene, tetralin, indane, chlorobenzene and o-dichlorobenzene, and more preferably o-xylene, pseudocumene, chlorobenzene or o-dichlorobenzene.

[0329] (2) Second solvent

[0330] The second solvent is preferably selected from the viewpoint of facilitating the implementation of the manufacturing process and further improving the characteristics of the light detecting element. Examples of the second solvent 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.

[0331] As the second solvent, acetophenone, propiophenone or benzyl benzoate is preferred.

[0332] (3) Combination of the first solvent and the second solvent

[0333] As a preferred combination of the first solvent and the second solvent, for example, a combination of o-xylene and acetophenone can be mentioned.

[0334] (4) Weight ratio of the first solvent to the second solvent

[0335] From the perspective of further improving the solubility of the p-type semiconductor material and the n-type semiconductor material, the weight ratio of the first solvent as the main solvent to the second solvent as the additional solvent (first solvent: second solvent) is preferably in the range of 85:15 to 99:1.

[0336] (5) Total weight percentage of the first solvent and the second solvent

[0337] When the total weight of the coating liquid is 100 weight %, from the perspective of further improving the solubility of the p-type semiconductor material and the n-type semiconductor material, the total weight of the first solvent and the second solvent contained in the coating liquid is preferably 90 weight % or more, more preferably 92 weight % or more, and further preferably 95 weight % or more. From the perspective of increasing the concentration of the p-type semiconductor material and the n-type semiconductor material in the coating liquid and facilitating the formation of a layer with a certain thickness or more, it is preferably 99 weight % or less, more preferably 98 weight % or less, and further preferably 97.5 weight % or less.

[0338] (6) Optional other solvents

[0339] The solvent may also include an optional solvent other than the first solvent and the second solvent. When the total weight of all solvents included in the coating solution is 100 wt %, the content of the optional other solvent is preferably 5 wt % or less, more preferably 3 wt % or less, and further preferably 1 wt % or less. As the optional other solvent, a solvent having a higher boiling point than the second solvent is preferred.

[0340] (Optional Ingredients)

[0341] The coating liquid may contain, in addition to the first solvent, the second solvent, the p-type semiconductor material and the n-type semiconductor material, optional components such as a UV absorber, an antioxidant, a sensitizer for enhancing the function of generating charges by utilizing the absorbed light, and a light stabilizer for increasing the stability against UV rays, within the limit not impairing the purpose and effect of the present invention.

[0342] (Concentrations of p-type semiconductor material and n-type semiconductor material in coating solution)

[0343] The total concentration of the p-type semiconductor material and the n-type semiconductor material in the coating liquid is preferably 0.01% by weight to 20% by weight, more preferably 0.01% by weight to 10% by weight, further preferably 0.01% by weight to 5% by weight, and particularly preferably 0.1% by weight to 5% by weight. 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, and more preferably completely dissolved.

[0344] (Preparation of coating solution)

[0345] The coating liquid can be prepared by a known method. For example, the coating liquid can be prepared by the following methods: a method of mixing a first solvent and a second 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 to the first solvent, adding an n-type semiconductor material to the second solvent, and then mixing the first solvent and the second solvent to which the materials are added; and the like.

[0346] The first solvent, the second solvent, the p-type semiconductor material, and the n-type semiconductor material may be mixed by heating to a temperature not higher than the boiling point of the solvent.

[0347] After mixing the first solvent and the second solvent and the p-type semiconductor material and the n-type semiconductor material, the obtained mixture can be filtered using a filter, and the obtained filtrate can be used as a coating liquid. As the filter, for example, a filter formed of a fluororesin such as polytetrafluoroethylene (PTFE) can be used.

[0348] (Anode Formation Process)

[0349] In this step, an anode is formed on the active layer. In this embodiment, the anode is formed on the active layer, but when the method for manufacturing a photoelectric conversion element includes a step of forming a hole transport layer as an intermediate layer between the anode and the active layer, the anode is formed on the hole transport layer (hole injection layer).

[0350] The method for forming the anode is not particularly limited. The anode can be formed by forming the electrode material described above on a layer to be formed as the anode by vacuum deposition, sputtering, ion plating, plating, coating, or the like.

[0351] When the material of the anode is polyaniline and its derivatives, polythiophene and its derivatives, nanoparticles of conductive substances, nanowires of conductive substances or nanotubes of conductive substances, the anode can be formed by a coating method using an emulsion (emulsion), suspension (suspension) or the like containing these materials and a solvent.

[0352] In addition, when the anode is formed by a coating method, the anode can be formed using a coating liquid containing a conductive substance, a metal ink, a metal paste, a low melting point metal in a molten state, etc. As a coating method for a coating liquid containing a material of the anode and a solvent, the same method as the formation step of the active layer described above can be cited.

[0353] As the solvent contained in the coating solution used when forming the anode by the coating method, for example, hydrocarbon solvents such as toluene, xylene, mesitylene, tetralin, decalin, bicyclohexane, n-butylbenzene, sec-butylbenzene, and tert-butylbenzene can be cited; halogenated saturated hydrocarbon solvents such as carbon tetrachloride, chloroform, dichloromethane, dichloroethane, chlorobutyl, bromobutyl, chloropentane, bromopentane, hexyl chloride, bromohexane, chlorocyclohexane, and bromocyclohexane; halogenated unsaturated hydrocarbon solvents such as chlorobenzene, dichlorobenzene, and trichlorobenzene; ether solvents such as tetrahydrofuran and tetrahydropyran; water, alcohol, etc. Specific examples of alcohols include methanol, ethanol, isopropanol, butanol, ethylene glycol, propylene glycol, butoxyethanol, methoxybutanol, etc. The coating solution may contain a single solvent, or may contain two or more solvents, or may contain two or more of the above solvents.

[0354] (Hole Transport Layer Formation Step)

[0355] The method for forming the hole transport layer when forming the hole transport layer (hole injection layer) is not particularly limited. From the perspective of making the hole transport layer formation process simpler, it is preferred to form the hole transport layer by a coating method. The hole transport layer can be formed, for example, by applying a coating solution containing the material of the hole transport layer described above and a solvent onto the active layer.

[0356] As the solvent in the coating liquid used in the coating method, for example, water, alcohol, ketone and hydrocarbon can be cited. As specific examples of alcohol, methanol, ethanol, isopropanol, butanol, ethylene glycol, propylene glycol, butoxyethanol and methoxybutanol can be cited. As specific examples of ketones, acetone, methyl ethyl ketone, methyl isobutyl ketone, 2-heptanone and cyclohexanone can be cited. As specific examples of hydrocarbons, n-pentane, cyclohexane, n-hexane, benzene, toluene, xylene, tetralin, chlorobenzene and o-dichlorobenzene can be cited. The coating liquid can contain a single solvent, or it can contain more than two solvents, and it can contain more than two of the above-mentioned solvents. The amount of the solvent in the coating liquid is preferably more than 1 part by weight and less than 10,000 parts by weight, and more preferably more than 10 parts by weight and less than 1,000 parts by weight relative to 1 part by weight of the material of the hole transport layer.

[0357] As a method for applying a coating solution containing a material of a hole transport layer and a solvent (coating method), for example, spin coating, blade coating, casting, micro gravure coating, gravure coating, rod coating, roll coating, wire bar coating, dip coating, spray coating, screen printing, flexographic printing, offset printing, inkjet printing, dispenser printing, nozzle coating, and capillary coating can be mentioned. Among these, spin coating, flexographic printing, inkjet printing, and dispenser printing are preferred.

[0358] It is preferred that the coating film obtained by applying a coating liquid containing a material for the hole transport layer and a solvent is subjected to a heating treatment, an air drying treatment, a reduced pressure treatment, or the like to remove the solvent from the coating film.

[0359] (Anode Formation Process)

[0360] In this embodiment, the anode is usually formed on the active layer. When the method for manufacturing the light detection element of this embodiment includes the step of forming the hole transport layer, the anode is formed on the hole transport layer.

[0361] The method for forming the anode is not particularly limited. The anode can be formed by vacuum deposition, sputtering, ion plating, plating, coating, or the like, by depositing the above-described materials on a layer to be formed as the anode, such as an active layer or a hole transport layer.

[0362] When the material of the anode is polyaniline and its derivatives, polythiophene and its derivatives, nanoparticles of conductive substances, nanowires of conductive substances or nanotubes of conductive substances, the anode can be formed by a coating method using an emulsion (emulsion), suspension (suspension) or the like containing these materials and a solvent.

[0363] In addition, when the material of the anode includes a conductive substance, the anode can be formed by a coating method using a coating liquid including a conductive substance, a metal ink, a metal paste, a molten low melting point metal, etc. As a coating method for a coating liquid including the material of the anode and a solvent, the same method as the formation process of the active layer described above can be cited.

[0364] As the solvent contained in the coating liquid used when forming the anode by the coating method, for example, hydrocarbon solvents such as toluene, xylene, mesitylene, tetralin, decalin, bicyclohexane, n-butylbenzene, sec-butylbenzene, tert-butylbenzene, etc. can be cited; halogenated saturated hydrocarbon solvents such as carbon tetrachloride, chloroform, dichloromethane, dichloroethane, chlorobutyl, bromobutyl, chloropentane, bromopentane, hexyl chloride, bromohexane, chlorocyclohexane, bromocyclohexane, etc.; halogenated aromatic hydrocarbon solvents such as chlorobenzene, dichlorobenzene, trichlorobenzene, etc.; ether solvents such as tetrahydrofuran and tetrahydropyran; water, alcohol, etc. As specific examples of alcohol, methanol, ethanol, isopropanol, butanol, ethylene glycol, propylene glycol, butoxyethanol, methoxybutanol, etc. can be cited. The coating liquid can contain a single solvent, or two or more solvents, or two or more of the above solvents.

[0365] Example

[0366] Hereinafter, examples will be described in order to explain the present invention in further detail. However, the present invention is not limited to the examples described below.

[0367] <Example 1: C60PCBM / Electron Transport Layer 1> Fabrication and Evaluation of Photoelectric Conversion Element

[0368] (Manufacturing of photoelectric conversion elements)

[0369] An ITO thin film (cathode) was formed on a glass substrate by sputtering to a thickness of 150 nm. The surface of the glass substrate was subjected to ozone UV treatment.

[0370] Next, a zinc oxide / isopropyl alcohol dispersion (trade name N-10, manufactured by Avantama) was applied as a coating liquid for forming an electron transport layer onto the ITO thin film of the glass substrate subjected to the ozone UV treatment by spin coating.

[0371] The glass substrate coated with the coating liquid for forming an electron transport layer was heated at 120° C. for 10 minutes using a hot plate to form an electron transport layer 1 on the ITO thin film as a cathode. The thickness of the electron transport layer 1 was 30 nm. The work function of the electron transport layer 1 formed here was measured (details are described below).

[0372] Next, the polymer compound P-1 as a p-type semiconductor and C60PCBM (manufactured by Frontier Carbon, trade name: E100, LUMO energy level: -4.3 eV) as an n-type semiconductor were mixed in a weight ratio of 1:2, added to a mixed solvent of o-xylene as the first solvent and acetophenone as the second solvent (o-xylene:acetophenone=95:5 (weight ratio)), and stirred at 80°C for 10 hours to prepare a coating liquid for forming an active layer.

[0373] The prepared coating liquid for forming an active layer was applied to the electron transport layer of the glass substrate by a doctor blade coating method to form a coating film. The formed coating film was dried for 5 minutes using a hot plate heated to 100° C. to form an active layer a. The thickness of the formed active layer a was 850 nm.

[0374] Next, in a resistance heating evaporation device, molybdenum oxide (MoOx) as a hole transport layer is evaporated on the formed active layer a with a thickness of about 30 nm, and then a silver (Ag) layer as an anode is formed with a thickness of about 80 nm, thereby manufacturing a photoelectric conversion element (light detection element).

[0375] Next, a UV curable sealant was applied to the glass substrate around the manufactured photoelectric conversion element, and after bonding the glass substrate as a sealing substrate, UV light was irradiated to seal the photoelectric conversion element. The planar shape of the obtained photoelectric conversion element when viewed from the thickness direction was a square of 2 mm×2 mm.

[0376] (Evaluation of Characteristics of Photoelectric Conversion Element)

[0377] While applying a voltage of -2 V to the manufactured photoelectric conversion element, the external quantum efficiency (EQE) and the dark current (Jd) were measured using a spectral sensitivity measuring device (CEP-2000, manufactured by Spectrometer Co., Ltd.) and a semiconductor parameter analyzer (Agilent Technology B1500A, manufactured by Agilent Technology), respectively. The photoelectric conversion element was irradiated with light of a wavelength of 850 nm, which is the maximum absorption wavelength of the polymer compound P-1 (photon number: 1.0×10 16 ), the current value of the generated current is measured, and the measured value of EQE is obtained by a known method. The measurement results of EQE and Jd are shown in Tables 1 and Figure 4 .

[0378] (Evaluation of the lowest unoccupied molecular orbital (LUMO) of the n-type semiconductor material included in the active layer)

[0379] The LUMO level of the n-type semiconductor material was estimated from the measured value of cyclic voltammetry (CV). The CV measurement was performed under the same conditions as the method described in Advanced Materials, Vol. 18, 2006, pp. 789-794.

[0380] CV measurement device: Electrochemical Analyzer 600B manufactured by BAS

[0381] Supporting electrolyte: dehydrated acetonitrile solution containing 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6, manufactured by Aldrich)

[0382] Working electrode: platinum foil / n-type semiconductor film (dropping solution dissolved in chloroform)

[0383] Counter electrode: Platinum foil

[0384] Reference electrode: Ag / AgCl electrode

[0385] Standard potential: Ferrocene

[0386] The LUMO of the obtained C60PCBM is -4.3 eV.

[0387] (Evaluation of the work function of the surface in contact with the active layer)

[0388] Using the glass substrate after the electron transport layer was formed as described above, the work function (WF) of the electron transport layer 1 was evaluated using a Kelvin probe apparatus. The Kelvin probe apparatus used was FAC-2 manufactured by Riken Keiki Co., Ltd. Gold (WF: 5.1 eV) was used as a calibration reference sample. The work function of the obtained electron transport layer 1 was 4.4 eV.

[0389] <Examples 2 to 7, 48, Comparative Example 1: C60PCBM / Electron Transport Layer 1>

[0390] Photoelectric conversion elements were prepared by the method described in Example 1 except that the thickness of the active layer was 600, 800, 950, 1100, 1400, 1800, 3000, and 3500 nm, and the measured values ​​of EQE were obtained. The measured results of EQE and Jd are shown in Tables 1 and Figure 4 .

[0391] <Examples 8, 9, Comparative Example 3: C60PCBM / Electron Transport Layer 2>

[0392] A zinc oxide / water dispersion (manufactured by Infinity PV, trade name Doped ZnO ink (water)) was used to form an electron transport layer 2 with a thickness of 30 nm, and the thickness of the active layer was set to 750, 1000, and 1400 nm. Photoelectric conversion elements were prepared by the method described in Example 1, and the measured values ​​of EQE were obtained. The measurement results of EQE and Jd are shown in Tables 1 and Figure 5 The WF of the electron transport layer 2 is 4.6 eV.

[0393] <Examples 10 to 13, Comparative Example 4: C60PCBM / Electron Transport Layer 3>

[0394] The electron transport layer 3 with a thickness of 30 nm was formed using an aluminum-doped zinc oxide / isopropyl alcohol dispersion (manufactured by Avantama, trade name N-10X), and the thickness of the active layer was set to 450, 850, 1100, 1800, and 3100 nm. Photoelectric conversion elements were prepared by the method described in Example 1, and the measured values ​​of EQE were obtained. The measurement results of EQE and Jd are shown in Tables 1 and Figure 6 The WF of the electron transport layer 3 is 4.4 eV.

[0395] <Examples 14 to 16, Comparative Example 5: C60PCBM / Electron Transport Layer 4>

[0396] The electron transport layer 4 was formed to a thickness of 30 nm using titanium (IV) isopropoxide / isopropanol solution (manufactured by Aldrich Corporation), and the thickness of the active layer was set to 550, 1000, 1300, and 3200 nm. Photoelectric conversion elements were prepared by the method described in Example 1, and the measured values ​​of EQE were obtained. The measured results of EQE and Jd are shown in Tables 1 and Figure 7 The WF of the electron transport layer 4 is 4.7 eV.

[0397] <Examples 17 to 20: C60PCBM / Electron Transport Layer 5>

[0398] A solution prepared by diluting a zinc oxide / isopropyl alcohol dispersion (manufactured by TAYCA, product name: HTD-711Z) with 3-pentanol to 1 / 10 times was used to form a film with a thickness of 30 nm. The formed film was subjected to a UV ozone treatment for 2 minutes, thereby obtaining an electron transport layer 5. Electron transport layer 5 was used as the electron transport layer, and the thickness of the active layer was made to be 1000, 1200, 2000, and 3100 nm. In addition, a photoelectric conversion element was made using the method described in Example 1 (also including ozone UV treatment of the surface of the glass substrate), and the measured value of EQE was obtained. The measurement results of EQE and Jd are shown in Tables 1 and Figure 8 The WF of the electron transport layer 5 is 4.6 eV.

[0399] <Examples 21, 22: C60PCBM / Electron Transport Layer 6>

[0400] An ITO thin film (cathode) was formed on a glass substrate, and the surface of the glass substrate was treated with oxygen plasma (150W, 15 minutes). Then, a polyethyleneimine ethoxylate (PEIE) aqueous solution (manufactured by Aldrich, trade name polyethyleneimine, 80% ethoxylated solution, weight average molecular weight 110000) was diluted with water to 1 / 100 times as a coating liquid for forming an electron transport layer to form an electron transport layer 6 with a thickness of 5 nm. The electron transport layer 6 was used as the electron transport layer, and the thickness of the active layer was made to be 600 and 1500 nm. In addition, a photoelectric conversion element was prepared using the method described in Example 1, and the measured value of EQE was obtained. The measurement results of EQE and Jd are shown in Tables 1 and Fig. 9 The WF of the electron transport layer 6 is 4.7 eV.

[0401] <Examples 23 to 25, Comparative Example 6: C60PCBM / No Electron Transport Layer>

[0402] An ITO thin film (cathode) was formed on a glass substrate. The surface of the glass substrate was not subjected to UV ozone treatment or the formation of an electron transport layer. An active layer was directly formed on the surface of the ITO thin film. The thickness of the active layer was 750, 1000, 1300, 2000, and 3200 nm. Photoelectric conversion elements were prepared by the method described in Example 1, and the measured values ​​of EQE were obtained. The measured results of EQE and Jd are shown in Tables 1 and Fig.10 The WF of the surface of the ITO thin film is 4.8 eV.

[0403] <Comparative Examples 7 to 10: C60PCBM / Electron Transport Layer 7>

[0404] An ITO thin film (cathode) was formed on a glass substrate, and the surface of the glass substrate was treated with ozone UV. Then, a polyethyleneimine ethoxylate (PEIE) aqueous solution (manufactured by Aldrich, trade name polyethyleneimine, 80% ethoxylated solution, weight average molecular weight 110000) was diluted 1 / 100 times with water as a coating liquid for forming an electron transport layer to obtain an electron transport layer 7 with a thickness of 5 nm. Electron transport layer 7 was used as the electron transport layer, and the thickness of the active layer was made to be 550, 800, 1000, and 1200 nm. In addition, a photoelectric conversion element was prepared using the method described in Example 1, and the measured value of EQE was obtained. The measurement results of EQE and Jd are shown in Tables 1 and Fig.11 The WF of the electron transport layer 7 is 4.2 eV.

[0405] <Comparative Examples 11 to 13: C60PCBM / Electron Transport Layer 8>

[0406] A solution prepared by diluting a zinc oxide / isopropyl alcohol dispersion (produced by TAYCA, product name: HTD-711Z) with 3-pentanol to 1 / 10 times was used as a coating solution for electron transport layer formation to obtain an electron transport layer 8 having a thickness of 30 nm. Electron transport layer 8 was used as the electron transport layer, and the thickness of the active layer was set to 650, 750, 1100, and 1400 nm. Photoelectric conversion elements were prepared by the method described in Example 1, and the measured value of EQE was obtained. The measurement results of EQE and Jd are shown in Tables 1 and Fig.12 In the table, LUMO is expressed as an absolute value. The WF of the electron transport layer 8 is 4.2 eV.

[0407]

[0408]

[0409] <Examples 26, 27, Comparative Example 14: bis-C60PCBM / Electron Transport Layer 7>

[0410] A photoelectric conversion element was prepared by the method described in Example 1 except that bis-C60PCBM (manufactured by Solenne, trade name: bis[C60]PCBM, LUMO energy level: -4.2 eV) was used as the n-type semiconductor contained in the active layer, and the electron transport layer 7 was used as the electron transport layer, and the thickness of the active layer was set to 600, 1000, and 2000 nm, and the measured value of EQE was obtained. The measurement results of EQE and Jd are shown in Tables 2 and Fig.13 .

[0411] <Examples 28, 29, Comparative Example 15: bis-C60PCBM / Electron Transport Layer 8>

[0412] Photoelectric conversion elements were prepared by the method described in Example 1 except that bis-C60PCBM was used as the n-type semiconductor included in the active layer, the electron transport layer 8 was used as the electron transport layer, and the thickness of the active layer was set to 600, 1000, and 2000 nm, and the measured value of EQE was obtained. The measured results of EQE and Jd are shown in Tables 2 and Fig.14 .

[0413] <Examples 30, 31, Comparative Example 16: bis-C60PCBM / Electron Transport Layer 1>

[0414] Photoelectric conversion elements were prepared by the method described in Example 1 except that bis-C60PCBM was used as the n-type semiconductor included in the active layer, the electron transport layer 1 was used as the electron transport layer, and the thickness of the active layer was set to 450, 1300, and 2000 nm, and the measured value of EQE was obtained. The measured results of EQE and Jd are shown in Tables 2 and Fig.15 .

[0415] <Examples 32 to 34, Comparative Example 17: bis-C60PCBM / Electron Transport Layer 2>

[0416] Photoelectric conversion elements were prepared by the method described in Example 1 except that bis-C60PCBM was used as the n-type semiconductor included in the active layer, the electron transport layer 2 was used as the electron transport layer, and the thickness of the active layer was set to 340, 800, 1500, and 3000 nm, and the measured value of EQE was obtained. The measurement results of EQE and Jd are shown in Tables 2 and Fig.16 .

[0417] <Examples 35 and 36: C70IPH / electron transport layer 1>

[0418] C70IPH (manufactured by Solenne, trade name: [C70]IPH, LUMO energy level: -4.3 eV) was used as the n-type semiconductor contained in the active layer, and the electron transport layer 1 was used as the electron transport layer. The thickness of the active layer was set to 800 and 1400 nm. A photoelectric conversion element was prepared by the method described in Example 1, and the measured value of EQE was obtained. The measurement results of EQE and Jd are shown in Tables 2 and 3. Fig.17 .

[0419] <Examples 37 and 38: C70IPH / Electron Transport Layer 2>

[0420] A photoelectric conversion element was prepared by the method described in Example 1 except that C70IPH was used as the n-type semiconductor included in the active layer, the electron transport layer 2 was used as the electron transport layer, and the thickness of the active layer was set to 1000 and 1500 nm, and the measured value of EQE was obtained. The measurement results of EQE and Jd are shown in Tables 2 and Fig.18 .

[0421] <Examples 39 to 41: C70IPH / No Electron Transport Layer>

[0422] C70IPH was used as an n-type semiconductor included in the active layer, and a glass substrate formed with an ITO thin film (cathode) was prepared. For the surface of the glass substrate, an active layer was directly formed on the surface of the ITO thin film without UV ozone treatment and an electron transport layer. The thickness of the active layer was 800, 1000, and 1500 nm. In addition, a photoelectric conversion element was prepared by the method described in Example 1, and the measured value of EQE was obtained. The measurement results of EQE and Jd are shown in Tables 2 and 3. Fig.19 .

[0423] <Comparative Examples 18 to 20: C70IPH / Electron Transport Layer 7>

[0424] Photoelectric conversion elements were prepared by the method described in Example 1 except that C70IPH was used as the n-type semiconductor included in the active layer, the electron transport layer 7 was used as the electron transport layer, and the thickness of the active layer was set to 500, 850, and 1100 nm, and the measured value of EQE was obtained. The measurement results of EQE and Jd are shown in Tables 2 and Fig. 20 .

[0425] <Comparative Examples 21 to 23: C70IPH / Electron Transport Layer 8>

[0426] Photoelectric conversion elements were prepared by the method described in Example 1 except that C70IPH was used as the n-type semiconductor included in the active layer, the electron transport layer 8 was used as the electron transport layer, and the thickness of the active layer was set to 250, 750, and 1200 nm, and the measured value of EQE was obtained. The measurement results of EQE and Jd are shown in Tables 2 and Fig.21 .

[0427] <Examples 42, 43, Comparative Example 24: C70PCBM / Electron Transport Layer 1>

[0428] C70PCBM (manufactured by American Dye Source, trade name: ADS71BFA, LUMO energy level: -4.3 eV) was used as the n-type semiconductor contained in the active layer, and the electron transport layer 1 was used as the electron transport layer. The thickness of the active layer was set to 300, 800, and 1600 nm. A photoelectric conversion element was prepared by the method described in Example 1, and the measured value of EQE was obtained. The measurement results of EQE and Jd are shown in Tables 2 and Fig. 22 .

[0429] <Examples 44, 45, Comparative Example 25: C70PCBM / Electron Transport Layer 2>

[0430] C70PCBM was used as the n-type semiconductor included in the active layer, the electron transport layer 2 was used as the electron transport layer, and the thickness of the active layer was set to 300, 900, and 1600 nm. A photoelectric conversion element was prepared by the method described in Example 1, and the measured value of EQE was obtained. The measurement results of EQE and Jd are shown in Tables 2 and Fig.23 .

[0431] <Examples 46, 47, Comparative Example 26: C70PCBM / No Electron Transport Layer>

[0432] C70PCBM was used as an n-type semiconductor included in the active layer, and a glass substrate formed with an ITO thin film (cathode) was prepared. For the surface of the glass substrate, an active layer was directly formed on the surface of the ITO thin film without UV ozone treatment and an electron transport layer. The thickness of the active layer was 300, 800, and 1600 nm. In addition, a photoelectric conversion element was prepared using the method described in Example 1, and the measured value of EQE was obtained. The measurement results of EQE and Jd are shown in Tables 2 and 3. Fig.24 .

[0433] <Comparative Examples 27 to 29: C70PCBM / Electron Transport Layer 7>

[0434] C70PCBM was used as the n-type semiconductor included in the active layer, the electron transport layer 7 was used as the electron transport layer, and the thickness of the active layer was set to 300, 750, and 1300 nm. A photoelectric conversion element was prepared by the method described in Example 1, and the measured value of EQE was obtained. The measurement results of EQE and Jd are shown in Tables 2 and Fig.25 .

[0435] <Comparative Examples 2, 30 to 32: Electron Transport Layer 8>

[0436] Photoelectric conversion elements were prepared by the method described in Example 1 except that C70PCBM was used as the n-type semiconductor included in the active layer, the electron transport layer 8 was used as the electron transport layer, and the thickness of the active layer was set to 250, 650, 1500, and 2000 nm, and the measured value of EQE was obtained. The measured results of EQE and Jd are shown in Tables 2 and Fig.26 In the table, LUMO is expressed as an absolute value.

[0437]

[0438]

[0439]

[0440] Table 3 summarizes various formation conditions of the electron transport layer used in Examples and Comparative Examples (electron transport layer forming coating solution, thickness of the electron transport layer, surface treatment) and the work functions obtained as a result.

[0441] [Table 3]

[0442] Table 3. Various formation conditions of the electron transport layer and the resulting work functions

[0443]

[0444] <Evaluation>

[0445] Figures 4 to 26 EQE and dark current (Jd) relative to the thickness of the active layer are shown in FIG. Fig.11 (Comparative Examples 7 to 10), Fig.12 (Comparative Examples 11 to 13), Fig.21 (Comparative Examples 21 to 23), Fig.25 (Comparative Examples 27 to 29) and Fig.26 In (Comparative Examples 2, 30 to 32), as in the prior art, as the thickness of the active layer increases, the dark current decreases and the EQE decreases. However, in the photoelectric conversion element where the value obtained by subtracting the absolute value of the LUMO energy level of the n-type semiconductor from the work function of the cathode-type surface is 0 or more, as the thickness of the active layer increases, the dark current can obtain a sufficiently low value, and the EQE is maintained at a high value, and a high EQE value is maintained even when the thickness of the active layer is 800nm ​​or more. That is, it is shown in the embodiments and comparative examples that high sensitivity characteristics can be obtained by using the technology of the present invention.

[0446] Explanation of symbols

[0447] 1 Image detection unit

[0448] 2 Display device

[0449] 10 Photoelectric conversion element

[0450] 11. 210 Support base plate

[0451] 12 Cathode

[0452] 13 Electron transport layer

[0453] 14 Active layer

[0454] 15. Hole transport layer

[0455] 16 Anode

[0456] 17. 240 sealing substrate

[0457] 20 CMOS transistor substrate

[0458] 30 interlayer insulation film

[0459] 32 Interlayer wiring section

[0460] 40 Sealing layer

[0461] 50 Color Filters

[0462] 100 Fingerprint detection unit

[0463] 200 Display panel unit

[0464] 200a Display area

[0465] 220 Organic EL elements

[0466] 230 Touch sensor panel

Claims

1. A light detection element, comprising: an anode; a cathode; and an active layer disposed between the anode and the cathode and comprising a p-type semiconductor material and an n-type semiconductor material, wherein: The thickness of the active layer is greater than 800 nm. The value obtained by subtracting the absolute value of the LUMO of the n-type semiconductor material from the work function of the surface in contact with the cathode side surface of the active layer is 0.0 to 0.5 eV, The surface in contact with the cathode-side surface of the active layer is not subjected to surface treatment or is subjected to only surface treatment such as oxygen plasma treatment or ultraviolet ozone treatment.

2. The light detecting element according to claim 1, wherein The n-type semiconductor material has an absolute value of LUMO of 2.0 eV to 10.0 eV.

3. The light detecting element according to claim 1 or 2, wherein: The n-type semiconductor material is a fullerene derivative.

4. The light detecting element according to claim 3, wherein: The fullerene derivative is C60PCBM, bisC60PCBM, C70IPH or C70PCBM.

5. The light detecting element according to claim 1 or 2, wherein: The work function of the surface in contact with the cathode-side surface of the active layer is 2.0 eV to 10.0 eV.

6. The light detecting element according to claim 1 or 2, wherein: An electron transport layer is included between the cathode and the active layer, and the surface in contact with the cathode-side surface of the active layer is the surface of the electron transport layer.

7. The light detecting element according to claim 6, wherein: The electron transport layer includes a metal oxide, a metal hydroxide or a metal alkoxide.

8. The light detecting element according to claim 7, wherein: The electron transport layer contains a metal oxide containing zinc or titanium, a metal hydroxide containing zinc or titanium, or a metal alkoxide containing zinc or titanium.

9. The light detecting element according to claim 6, wherein: The electron transport layer contains a compound having an alkylene structure.

10. The light detecting element according to claim 9, wherein The compound having an alkylene structure is a polyalkylene imine or a derivative thereof.

11. The light detecting element according to claim 10, wherein The polyalkyleneimine or its derivative is polyethyleneimine or its derivative.

12. The light detecting element according to claim 1 or 2, wherein: The cathode is in direct contact with the active layer, and the surface in contact with the cathode-side surface of the active layer is the cathode surface. 13 . An image sensor comprising the light detection element according to claim 1 . 14 . A fingerprint recognition device comprising a fingerprint detection unit including the light detection element according to claim 1 .

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