Compound, organic thin film, photoelectric conversion element, imaging element, optical sensor, and solid-state imaging device

Abstract

A compound represented by formula (1) (X is an oxygen atom or NR6, and R1-R6 are each independently a hydrogen atom, a halogen atom, a cyano group, a linear, branched or cyclic alkyl group, an aryl group, or the like. ). # imgabs0 #

Description

Technical Field

[0001] The present invention relates to compounds, organic thin films, photoelectric conversion elements, imaging elements, optical sensors, and solid-state imaging devices. Background Art

[0002] Conventionally, techniques for photoelectrically converting visible light into an electrical signal have been known and are used, for example, in imaging elements. Such imaging elements are provided in solid-state imaging devices such as CCD (Charge Coupled Device) image sensors and CMOS (Complementary Metal Oxide Semiconductor) image sensors. In recent years, in solid-state imaging devices, as the pixel size has been reduced, organic photoelectric conversion films for coping with this have been studied. For example, Patent Documents 1 and 2 disclose organic photoelectric conversion films composed of subphthalocyanine and imide compounds.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2018-32754

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2018-512423

[0007] Patent Document 3: Japanese Patent Application Laid-Open No. 2014-506736 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] For solid-state imaging devices, high spectral selectivity and a high S / N ratio are required. Therefore, it is desired that solid-state imaging devices have a high external quantum efficiency (EQE) and low dark current characteristics. In order to achieve both of these, a method of disposing an electron transport layer and a hole blocking layer, and / or disposing a hole transport layer and an electron blocking layer between the photoelectric conversion portion and the electrode portion is known. Here, in the field of organic electronic devices, the electron transport layer, hole blocking layer, electron blocking layer, etc., which are widely used, are disposed at the interface between the electrode or a conductive film and other films in the films constituting the device. These layers respectively function to control the reverse movement of holes or electrons and adjust unnecessary hole or electron leakage. As a material for such a layer, for example, Patent Document 3 discloses an example of using naphthalene-1,4,5,8-tetracarboxylic dianhydride (NTCDA).

[0010] However, in the conventional hole-blocking layers and electron-blocking layers represented by the substances disclosed in Patent Document 3, there is room for further improvement in suppressing leakage current in the dark.

[0011] An object of the present invention is to provide a novel compound and a photoelectric conversion element material that can suppress leakage current in the dark, are particularly useful for photoelectric conversion element materials, an organic thin film containing the compound, a photoelectric conversion element, an imaging element, a light sensor, and a solid-state imaging device.

[0012] Means for Solving the Problems

[0013] The present invention is as follows.

[0014] [1] A compound represented by the following formula (1).

[0015]

[0016] (X is an oxygen atom or NR 6 ,

[0017] R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, a mercapto group, an amino group, a cyano group, a carboxyl group, a nitro group, and a linear, branched or cyclic alkyl group, a thioalkyl group, a thioaryl group, an arylsulfonyl group, an aryloxy group, an alkylsulfonyl group, an alkylamino group, an arylamino group, an alkoxy group, an acylamino group, an acyloxy group, an aryl group, a carboxamido group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyl group, and a monovalent heterocyclic group, and any adjacent R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are optionally part of a fused aliphatic ring or a fused aromatic ring. Two R 1 , R 2 , R 3 , R 4 , R 5 and X may be the same as or different from each other. The aforementioned fused aliphatic ring and fused aromatic ring optionally contain one or more atoms other than carbon.)

[0018] [2] The above compound, wherein the energy level of the lowest unoccupied orbital of the compound represented by the formula (1) obtained by density functional theory is -6.00 eV or more and -3.40 eV or less.

[0019] [3]The above compound, wherein the energy difference between the lowest unoccupied molecular orbital and the highest occupied molecular orbital of the compound represented by the foregoing formula (1) obtained by density functional theory is 3.00 eV or more and 4.00 eV or less.

[0020] [4]The above compound, which is a material for a photoelectric conversion element.

[0021] [5]An organic thin film, which contains the above compound.

[0022] [6]The above organic thin film, which has a maximum absorption wavelength in the light absorption band at 450 nm or less.

[0023] [7]A photoelectric conversion element, which includes a first electrode film, a second electrode film, and a photoelectric conversion film located between the foregoing first electrode film and the foregoing second electrode film,

[0024] The foregoing photoelectric conversion film contains the above material for a photoelectric conversion element.

[0025] [8]A photoelectric conversion element, which includes a first electrode film, a second electrode film, and a photoelectric conversion film located between the foregoing first electrode film and the foregoing second electrode film,

[0026] The foregoing photoelectric conversion film contains the above organic thin film.

[0027] [9]The above photoelectric conversion element, wherein the foregoing photoelectric conversion film contains a photoelectric conversion layer and an auxiliary layer,

[0028] The foregoing auxiliary layer is formed only of the foregoing organic thin film or is formed of a plurality of films including the foregoing organic thin film.

[0029]

[10] An imaging element, which includes the above photoelectric conversion element.

[0030]

[11] The above imaging element, which is formed by stacking two or more of the foregoing photoelectric conversion elements.

[0031]

[12] An imaging element, which is formed by arranging a plurality of the above photoelectric conversion elements in an array.

[0032]

[13] An optical sensor, which includes the above imaging element.

[0033]

[14] A solid-state imaging device, which includes the above imaging element.

[0034] Effects of the Invention

[0035] According to the present invention, a novel compound and a material for a photoelectric conversion element that are particularly useful for a material for a photoelectric conversion element, an organic thin film containing the compound, a photoelectric conversion element, an imaging element, an optical sensor, and a solid-state imaging device can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 FIG. is a schematic cross-sectional view showing an example of a photoelectric conversion element of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0037] Hereinafter, embodiments of the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail with reference to the accompanying drawings as needed. However, the present invention is not limited to the following embodiments. The present invention can be variously modified without departing from its gist. It should be noted that in the drawings, the same reference numerals are assigned to the same elements, and repeated descriptions are omitted. In addition, unless otherwise specified, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios in the drawings are not limited to the ratios shown.

[0038] (Compound)

[0039] The compound of the present embodiment is represented by the following formula (1) (hereinafter, this compound will also be referred to as "compound (1)").

[0040]

[0041] Here, X is an oxygen atom or NR 6 , R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, a mercapto group, an amino group, a cyano group, a carboxyl group, a nitro group, and an optionally substituted straight-chain, branched-chain or cyclic alkyl group, thioalkyl group, thioaryl group, arylsulfonyl group, aryloxy group, alkylsulfonyl group, alkylamino group, arylamino group, alkoxy group, acylamino group, acyloxy group, aryl group, carboxamide group, alkoxycarbonyl group, aryloxycarbonyl group, acyl group and a monovalent heterocyclic group, and any adjacent R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are optionally part of a fused aliphatic ring or a fused aromatic ring. Two R 1 , R 2 , R 3 , R 4 , R 5 and X may be the same as or different from each other. The aforementioned fused aliphatic ring and fused aromatic ring optionally contain one or more atoms other than carbon.

[0042] This compound (1) can suppress the leakage current in the dark and exhibits excellent properties particularly as a material for a photoelectric conversion element. The reason is not yet determined, but the present inventors consider it as follows. Herein, the reason is not limited to the following content. That is, by having two aryloxy groups in the molecular structure of compound (1), and the two aryloxy groups being diagonal to the naphthyl group, the energy level of the lowest unoccupied orbital of compound (1) decreases, and the leakage current in the dark can be suppressed. In addition, by having two aryloxy groups in compound (1), the crystallinity becomes low, and it is easy to have multiple structures with similar and stable energy levels. Therefore, it is difficult to exhibit a highly regular molecular arrangement as a solid. Thereby, the occurrence of film thickness disorder and electrical short circuit (pinholes) that may occur due to local aggregation in the thin film can be suppressed. Furthermore, when compound (1) is compared with the case where it does not have two aryloxy groups, it has a low molecular orientation in the thin film with respect to the layer direction, so high electron transportability can be obtained, and excellent properties can be obtained as a material for a photoelectric conversion element.

[0043] Examples of the halogen atom include a fluorine atom (F), a chlorine atom (Cl), a bromine atom (Br), and an iodine atom (I).

[0044] The straight-chain alkyl group may be a straight-chain alkyl group having 1 to 12 carbon atoms in the alkyl group. For example, it includes a methyl group (Me), an ethyl group (Et), a n-propyl group (n-Pr), a n-butyl group (n-Bu), a n-pentyl group, a n-hexyl group, a n-heptyl group, a n-octyl group, a n-nonyl group, a n-decyl group, and a n-dodecyl group. Among these, from the viewpoint of more effectively and reliably achieving the effects described in the present invention, a straight-chain alkyl group having 1 to 3 carbon atoms is preferred, a methyl group or an ethyl group is more preferred, and a methyl group is further preferred.

[0045] The branched-chain alkyl group may be a branched-chain alkyl group having 1 to 12 carbon atoms in the alkyl group. For example, it includes an isopropyl group (i-Pr), a sec-butyl group (s-Bu), a tert-butyl group (t-Bu), an isopentyl group, a sec-pentyl group, a 3-pentyl group, a neopentyl group, an isohexyl group, an isooctyl group, an isononyl group, an isodecyl group, and an isododecyl group. In addition, the straight-chain or branched-chain alkyl group may have a substituent. Examples of the substituent include a halogen atom such as a fluorine atom, a monovalent group having an aromatic ring such as a benzyl group, a naphthyl group, and a phenoxy group, a monovalent group having a heteroatom such as an alkoxy group, an aminoalkyl group, and a thioalkyl group, a monovalent group having a heterocycle such as a pyridyl group, a hydroxyl group, a carboxyl group, an amino group, and a thiol group.

[0046] As the cyclic alkyl group, it can be a cyclic alkyl group with 3 to 10 carbon atoms in the alkyl group. For example, it can be exemplified by cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. In addition, the cyclic alkyl group can have heteroatoms such as nitrogen atoms, oxygen atoms, and sulfur atoms in its ring. As such a cyclic alkyl group, for example, it can be exemplified by pyrrolidinyl, oxazolidinyl, pyrazolidinyl, thiazolidinyl, imidazolidinyl, dioxolanyl, tetrahydrofuranyl, tetrahydrothienyl, piperazinyl, dioxanyl, and morpholinyl. Further, a monovalent group such as a hydroxyl group, a carboxyl group, an amino group, and a thiol group can be bonded to the cyclic alkyl group.

[0047] As the thioalkyl group (-SR; hereinafter, R represents an alkyl group) and the thioaryl group (-SAr; hereinafter, Ar represents an aryl group), it can be a thioalkyl group with 1 to 12 carbon atoms in the alkyl group and a thioaryl group with 6 to 16 carbon atoms in the aryl group. In addition, the thioalkyl group and the thioaryl group can also have substituents such as an amino group, a hydroxyl group, a halogen atom, an alkoxy group, and a thioalkyl group. As such a thioalkyl group and thioaryl group, for example, it can be exemplified by methylthio, ethylthio, phenylthio, tolylthio, aminophenylthio, hydroxyphenylthio, fluorophenylthio, dimethylphenylthio, and methylthiophenylthio.

[0048] As the arylsulfonyl group (-SO 2 -Ar), it can be an arylsulfonyl group with 6 to 16 carbon atoms in the aryl group. For example, it can be exemplified by benzenesulfonyl, toluenesulfonyl, dimethylbenzenesulfonyl, mesitylenesulfonyl, octylbenzenesulfonyl, and naphthalenesulfonyl.

[0049] As the aryloxy group (-O-Ar), it can be an aryloxy group with 6 to 16 carbon atoms in the aryl group. In addition, the aryloxy group can also have substituents such as a cyano group, a halogen atom such as a fluorine atom, a hydroxyl group, an alkoxy group such as a methoxy group, an amino group, an alkylamino group, a thiol group, and an aryloxy group. As such an aryloxy group, for example, it can be exemplified by phenoxy, cyanophenoxy, methylcyanophenoxy, dimethylcyanophenoxy, fluorocyanophenoxy, dicyanophenoxy, methoxycyanophenoxy, tricyanophenoxy, cyanonaphthoxy, dicyanonaphthoxy, 2-methylphenoxy, 3-methylphenoxy, 4-methylphenoxy, fluoromethylphenoxy, dimethylphenoxy, 3-hydroxyphenoxy, fluoro-3-hydroxyphenoxy, 2-hydroxyphenoxy, fluoro-2-hydroxyphenoxy, methoxyphenoxy, ethoxyphenoxy, fluorophenoxy, perfluorophenoxy, dimethoxyphenoxy, aminophenoxy, N,N-dimethylaminophenoxy, thiophenoxy, (trifluoromethyl)phenoxy, naphthoxy, methoxynaphthoxy, fluoronaphthoxy, and phenoxyphenoxy.

[0050] As the alkylsulfonyl group (-SO 2-R), which may be an alkylsulfonyl group having 1 to 12 carbon atoms in the alkyl group, such as methylsulfonyl group, ethylsulfonyl group, and n-butylsulfonyl group.

[0051] As the alkylamino group (here, the alkylamino group is -NHR or -NR 2 , and the two Rs may be the same as or different from each other), it may be an alkylamino group having 1 to 12 carbon atoms in the alkyl group, such as methylamino group, ethylamino group, n-propylamino group, n-butylamino group, n-pentylamino group, n-hexylamino group, n-heptylamino group, n-octylamino group, n-nonylamino group, n-decylamino group, n-dodecylamino group, isopropylamino group, sec-butylamino group, tert-butylamino group, isopentylamino group, sec-pentylamino group, 3-pentylamino group, neopentylamino group, isohexylamino group, isoheptylamino group, isooctylamino group, isononylamino group, isodecylamino group, and isododecylamino group, dimethylamino group, diethylamino group, diisopropylamino group, and isopropyl ethylamino group.

[0052] As the arylamino group (here, the arylamino group is -NHAr or -NAr 2 , and the two Ars may be the same as or different from each other), it may be an arylamino group having 6 to 16 carbon atoms in the aryl group, such as anilino group, toluidino group, dimethylanilino group, isopropylanilino group, tert-butylanilino group, fluoroanilino group, trifluoromethylanilino group, bis(trifluoromethyl)anilino group, pyridylamino group, methylpyridylamino group, fluoropyridylamino group, pyrimidinylamino group, and biphenylamino group.

[0053] As the alkoxy group (-OR), it may be an alkoxy group having 1 to 12 carbon atoms, such as methoxy group, ethoxy group, n-propoxy group, n-butoxy group, n-pentyloxy group, n-hexyloxy group, n-heptyloxy group, n-octyloxy group, n-nonyloxy group, n-decyloxy group, and n-dodecyloxy group, isopropoxy group, sec-butoxy group, tert-butoxy group, isopentyloxy group, sec-pentyloxy group, 3-pentyloxy group, neopentyloxy group, isohexyloxy group, isooctyloxy group, isononyloxy group, isodecyloxy group, and isododecyloxy group.

[0054] As the acylamino group (-NH-COR or -NH-COAr), the number of carbon atoms in the alkyl group may be 1 to 12 or the number of carbon atoms in the aryl group may be 6 to 16, and it may also have substituents such as halogen atoms like fluorine atoms, alkoxy groups, and cyano groups. As such acylamino groups, for example, acetylamino group, propionylamino group, benzoylamino group, methylbenzoylamino group, dimethylbenzoylamino group, methoxybenzoylamino group, cyanobenzoylamino group, and bis(trifluoromethyl)benzoylamino group can be cited.

[0055] As the acyloxy group (-O-COR or -O-COAr), the number of carbon atoms in the alkyl group can be 1 to 12 or the number of carbon atoms in the aryl group can be 6 to 16. The acyloxy group can also have substituents such as halogen atoms like fluorine atoms and cyano groups, and can also have heteroatoms such as nitrogen atoms within the aromatic ring. Examples of such acyloxy groups include: benzoyloxy, methylbenzoyloxy, dimethylbenzoyloxy, cyanobenzoyloxy, fluorobenzoyloxy, bis(trifluoromethyl)benzoyloxy, pyridinecarboxy, and methylpyridinecarboxy.

[0056] As the aryl group (-Ar), it can be an aryl group having 6 to 16 carbon atoms. The aryl group can also have substituents such as amino group, hydroxyl group, mercapto group, halogen atoms like fluorine atoms, nitro group, and cyano group, and can also have heteroatoms such as nitrogen atoms within the aromatic ring. Examples of such aryl groups include: phenyl, methylphenyl, ethylphenyl, dimethylphenyl, trimethylphenyl, methoxyphenyl, dimethoxyphenyl, trimethoxyphenyl, methoxymethylphenyl, aminophenyl, diaminophenyl, aminomethylphenyl, hydroxyphenyl, dihydroxyphenyl, hydroxymethylphenyl, hydroxyethylphenyl, thiophenyl, methylthiophenyl, dithiophenyl, fluorophenyl, fluoromethylphenyl, trifluoromethylphenyl, perfluorophenyl, fluoro(trifluoromethyl)phenyl, bis(trifluoromethyl)phenyl, cyanophenyl, methylcyanophenyl, dimethylcyanophenyl, dicyanophenyl, methoxycyanophenyl, tricyanophenyl, dicyanophenyl, methylcyanopyridyl, (trifluoromethyl)cyanopyridyl, dimethylcyanopyridyl, dicyanopyridyl, methoxycyanopyridyl, tricyanopyridyl, cyanopyridyl, naphthyl, nitrophenyl, dinitrophenyl, nitrofluorophenyl, methylnaphthyl, ethylnaphthyl, dimethylnaphthyl, trimethylnaphthyl, methoxynaphthyl, dimethoxynaphthyl, trimethoxynaphthyl, aminonaphthyl, diaminonaphthyl, aminomethylnaphthyl, hydroxynaphthyl, dihydroxynaphthyl, hydroxymethylnaphthyl, hydroxyethylnaphthyl, thionaphthyl, methylthionaphthyl, dithionaphthyl, fluoronaphthyl, trifluoromethylnaphthyl, perfluoronaphthyl, bis(trifluoromethyl)naphthyl, biphenyl, cyanobiphenyl.

[0057] As the carboxamido group (here, the carboxamido group is -CO-NH 2 、-CO-NHR、-CONR 2 , the two Rs can be the same as each other, can be different from each other, or can be -CONHAr or -CONAr 2 , and the two Ars can be the same as each other or can be different from each other), it can be a carboxamido group having 1 to 12 carbon atoms in the alkyl group or 6 to 16 carbon atoms in the aryl group. Examples include: dimethylcarboxamido group and diphenylcarboxamido group.

[0058] As the alkoxycarbonyl or aryloxycarbonyl (-COOR or -COOAr), it may be an alkoxycarbonyl in which the number of carbon atoms in the alkyl group is 1 to 12 or an aryloxycarbonyl in which the number of carbon atoms in the aryl group is 6 to 16. For example, it may include: methoxycarbonyl, phenoxycarbonyl.

[0059] As the monovalent heterocyclic group, it may be a monovalent heterocyclic group having 3 to 14 carbon atoms. For example, it may include: furyl, thienyl, pyrrolyl, pyrazolyl, imidazolyl, triazolyl, oxazolyl, dioxazolyl, isoxazolyl, oxadiazolyl, thiazolyl, isothiazolyl, thiadiazolyl, triazolyl, indolyl, indolinyl, indolinazinyl, indazolyl, indoleninyl, benzofuryl, benzothienyl, carbazolyl, dibenzofuryl, dibenzothienyl, pyridyl, diazinyl, oxazinyl, thiazinyl, dioxazinyl, dithienyl, triazinyl, pyrimidinyl, pyrazinyl, pyridazinyl, quinolinyl, isoquinolinyl, cinnolinyl, phthalazinyl, quinazolinyl, naphthyridinyl, purinyl, pteridinyl, acridinyl, phenanthridinyl, phenanthrolinyl, xanthenyl, phenoxazinyl, thianthrenyl, morpholinyl and phenazinyl.

[0060] In the compound (1) of the present embodiment, there is no particular limitation on R 1 、R 2 、R 3 、R 4 and R 5 Preferably, they are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, a mercapto group, an amino group, a cyano group, a carboxyl group, a nitro group, and a linear, branched or cyclic alkyl group, a thioalkyl group, a thioaryl group, an arylsulfonyl group, an aryloxy group, an alkylsulfonyl group, an alkylamino group, an arylamino group, an alkoxy group, an acylamino group, an acyloxy group, an aryl group, a carboxamide group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyl group and a monovalent heterocyclic group, which may be substituted. More preferably, they are selected from the group consisting of a hydrogen atom, a halogen atom, a nitro group, a cyano group, and a linear, branched or cyclic alkyl group, which may be substituted. Further preferably, they are selected from the group consisting of a hydrogen atom, a halogen atom, a nitro group, a cyano group, an unsubstituted alkyl group and an alkyl group substituted with a halogen atom. Particularly preferably, they are selected from the group consisting of a cyano group and an unsubstituted alkyl group. Most preferably, it is a cyano group. By making the compound (1) have the above structure, the leakage current in the dark can be further suppressed.

[0061] In the present embodiment, R 1 、R 2 、R 3 、R 4 and R 5 May be the same or different. From the viewpoint of more effectively and reliably achieving the effects of the present invention, there is no particular limitation, and it is preferably selected from R 1 、R 2 、R3 , R 4 and R 5 are at least two identical, more preferably selected from R 1 , R 2 , R 3 , R 4 and R 5 are at least four identical. It should be noted that the two Rs 1 , R 2 , R 3 , R 4 , R 5 in compound (1) are optionally identical or different from each other, preferably identical to each other.

[0062] The compound (1) of this embodiment is not particularly limited. From the viewpoint of more effectively and reliably achieving the effects described in the present invention, preferably R 1 , R 2 , R 3 , R 4 and R 5 is at least one not being a hydrogen atom, more preferably R 1 , R 2 , R 3 , R 4 and R 5 is at least one selected from the group consisting of a halogen atom, a nitro group, a cyano group, and an optionally substituted linear, branched or cyclic alkyl group. Further, more preferably R 1 , R 2 , R 3 , R 4 and R 5 is at least one selected from the group consisting of a halogen atom, a nitro group, a cyano group, an unsubstituted alkyl group and an alkyl group substituted by a halogen atom, particularly preferably R 1 , R 2 , R 3 , R 4 and R 5 is at least one selected from the group consisting of a cyano group and an unsubstituted alkyl group, extremely preferably R 1 , R 2 , R 3 , R 4 and R 5 is at least one cyano group.

[0063] The compound (1) of this embodiment is not particularly limited. From the viewpoint of more effectively and reliably achieving the effects described in the present invention, preferably R 1 , R 2 , R 3 , R 4 and R5 At least two of them are hydrogen atoms, more preferably R 1 , R 2 , R 3 , R 4 and R 5 At least two or at least three of them are hydrogen atoms, particularly preferably R 1 , R 2 , R 3 , R 4 and R 5 At least four of them are hydrogen atoms.

[0064] In this embodiment, when at least four of R 1 , R 2 , R 3 , R 4 and R 5 are hydrogen atoms, there is no particular limitation. From the viewpoint of more effectively and reliably achieving the effects of the present invention, R 2 , R 3 , R 4 and R 5 are preferably hydrogen atoms.

[0065] In addition, when R 2 , R 3 , R 4 and R 5 are hydrogen atoms, R 1 is preferably a group selected from the group consisting of a halogen atom, a hydroxyl group, a mercapto group, an amino group, a cyano group, a carboxyl group, a nitro group, and an optionally substituted straight-chain, branched-chain or cyclic alkyl group, thioalkyl group, thioaryl group, arylsulfonyl group, aryloxy group, alkylsulfonyl group, alkylamino group, arylamino group, alkoxy group, acylamino group, acyloxy group, aryl group, carboxamido group, alkoxycarbonyl group, aryloxycarbonyl group, acyl group and a monovalent heterocyclic group, more preferably a group selected from the group consisting of a halogen atom, a nitro group, a cyano group, and an optionally substituted straight-chain, branched-chain or cyclic alkyl group, further preferably a group selected from the group consisting of a halogen atom, a nitro group, a cyano group, an unsubstituted alkyl group and an alkyl group substituted with a halogen atom, particularly preferably a group selected from the group consisting of a cyano group and an unsubstituted alkyl group, and most preferably a cyano group.

[0066] In the compound (1) of this embodiment, X is an oxygen atom or NR 6 , and the two Xs present are optionally the same or different from each other. From the viewpoint of more effectively and reliably achieving the effects of the present invention, they are preferably the same. When X is NR 6 , there is no particular limitation, and R 6Preferably selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, a mercapto group, an amino group, a cyano group, a carboxyl group, a nitro group, and an optionally substituted straight-chain, branched-chain or cyclic alkyl group, thioalkyl group, thioaryl group, arylsulfonyl group, aryloxy group, alkylsulfonyl group, alkylamino group, arylamino group, alkoxy group, acylamino group, acyloxy group, aryl group, carboxamido group, alkoxycarbonyl group, aryloxycarbonyl group, acyl group and a monovalent heterocyclic group, more preferably selected from the group consisting of an optionally substituted straight-chain, branched-chain or cyclic alkyl group, aryl group and a monovalent heterocyclic group, particularly preferably an aryl group optionally substituted by a group selected from the group consisting of a halogen atom, a nitro group, a cyano group and an alkyl group substituted by a halogen atom. By making the compound (1) have the above structure, the leakage current in the dark can be further suppressed. It should be noted that both of the two Xs present in the compound (1) are NR 6 When, from the viewpoint of more effectively and reliably achieving the effects of the present invention, the two Rs present 6 are optionally the same or different from each other, and are preferably the same as each other.

[0067] From the viewpoint of more effectively and reliably achieving the effects of the present invention, the energy level of the lowest unoccupied molecular orbital (LUMO: Lowest Unoccupied Molecular Orbital) of the compound (1) of the present embodiment obtained by density functional theory is preferably -6.00 eV or more and -3.40 eV or less, more preferably -5.50 eV or more and -3.45 eV or less. It should be noted that this energy level can be -6.00 eV or more and -3.80 eV or less, or can be -5.50 eV or more and -3.80 eV or less. For the compound (1) of the present embodiment, by performing structural optimization through molecular simulation using density functional theory (for example, molecular simulation using the quantum chemistry calculation program Gaussian manufactured by Gaussian Inc.), the energy level of the lowest unoccupied molecular orbital of the compound (1) can be obtained. In addition, the energy level of the lowest unoccupied molecular orbital of the compound (1) of the present embodiment obtained by density functional theory can be adjusted by changing R 1 ~R 6 . From the viewpoint of setting the energy level of the lowest unoccupied molecular orbital within the above range, preferably at least one of R 1 , R 2 , R 3 , R 4 and R 5 is an electron-withdrawing group, and R 6 is preferably an aryl group substituted by an electron-withdrawing group.

[0068] From the viewpoint of more effectively and reliably achieving the effects of the present invention, the energy level of the highest occupied molecular orbital (HOMO: Highest Occupied Molecular Orbital) of the compound (1) of the present embodiment obtained by density functional theory is preferably -8.00 eV or more and -6.00 eV or less, more preferably -7.90 eV or more and -6.10 eV or less. For the compound (1) of the present embodiment, structural optimization can be carried out by molecular simulation using density functional theory (for example, molecular simulation using the quantum chemistry calculation program Gaussian manufactured by Gaussian Inc.), and the energy level of the highest occupied molecular orbital can be obtained. In addition, the energy level of the highest occupied molecular orbital of the compound (1) of the present embodiment obtained by density functional theory is not particularly limited, and can be adjusted by changing R 1 ~R 6 There is no particular limitation from the viewpoint of setting the energy level of the highest occupied molecular orbital within the above range. Preferably, at least one of R 1 、R 2 、R 3 、R 4 and R 5 is an electron-withdrawing group, and R 6 is preferably an aryl group substituted with an electron-withdrawing group.

[0069] The difference (eV) between the energy level of the lowest unoccupied molecular orbital and the energy level of the highest occupied molecular orbital ([highest occupied molecular orbital energy level] - [lowest unoccupied molecular orbital energy level]) of the compound (1) of the present embodiment obtained by density functional theory is preferably 3.00 eV or more and 4.00 eV or less. By setting the energy level difference within the above range, when used as a material for a photoelectric conversion element, there is a tendency to reduce the dark leakage current.

[0070] The molecular weight of the compound (1) of the present embodiment is preferably 400 or more, more preferably 430 or more, and further preferably 450 or more. If the molecular weight is 400 or more, physical property changes caused by molecular thermal motion that may occur during the heating operation and in a high-temperature use environment in the manufacturing process of the organic film using the compound (1) can be further suppressed. In addition, particularly when the compound (1) is formed by vacuum evaporation, the molecular weight of the compound (1) is preferably 1000 or less, more preferably 950 or less, and further preferably 900 or less. If the molecular weight is 1000 or less, the thermal energy required for sublimation when forming the organic film of the compound (1) by vacuum evaporation can be suppressed to a lower level. Thus, a good film can be formed without thermal degradation of the compound (1). However, when forming a film by solution coating, since such problems are less likely to occur, the molecular weight of the compound (1) can be greater than 1000.

[0071] The temperature at which the weight ratio of the weight loss caused by heating the compound (1) of the present embodiment in an inert gas atmosphere becomes within 5% of that before heating (hereinafter, sometimes referred to as "5% weight loss temperature") is preferably 200 °C or higher, more preferably 250 °C or higher. When the 5% weight loss temperature is 200 °C or higher, physical property changes caused by molecular thermal motion that may occur during heating operations or in high-temperature usage environments in the organic thin film manufacturing process using the compound (1) can be further suppressed. The 5% weight loss temperature can be measured by differential thermal analysis.

[0072] The compound (1) of the present embodiment can be obtained, for example, by synthesis as described below. In the product (100% by mass) obtained by synthesis, the content rate of the compound (1) is preferably 90% by mass or higher, more preferably 93% by mass or higher, and further preferably 97% by mass or higher. By making the content rate of the compound (1) 90% by mass or higher, the capture of carriers by impurity energy levels caused by unwanted impurities can be more effectively and reliably avoided when the compound (1) is used in a photoelectric conversion element. As a result, the recombination of carriers can be suppressed, and a photoelectric conversion element with more excellent performance can be obtained. For the measurement of the content rate, examples include liquid chromatography, gas chromatography, and elemental analysis, as long as they are known methods.

[0073] Hereinafter, there is shown a preferred combination of R when both or any one of the two Xs present in the compound (1) of the present embodiment is NR 6 at that time 1 , R 2 , R 3 , R 4 , R 5 and R 6 . Among them, the compound (1) is not limited to them.

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081] Hereinafter, there is shown R when X in the compound (1) of the present embodiment is an oxygen atom 1 , R 2 , R3 , R 4 and R 5 The preferred combinations of. Among them, the compounds (1) are not limited to them.

[0082] <![CDATA[R 1 > <![CDATA[R 2 > <![CDATA[R 3 > <![CDATA[R 4 > <![CDATA[R 5 > H H H H H CN H H H H CN CN H H H H CN CN H H CN CN H H CN CN H H CN CN F H H H H F F H H H H F F H H F F H H F F H H F F Cl H H H H Cl Cl H H H H Cl Cl H H Cl Cl H H Cl Cl H H Cl Cl <![CDATA[CF 3 > H H H H <![CDATA[CF 3 > <![CDATA[CF 3 > H H H H <![CDATA[CF 3 > <![CDATA[CF 3 > H H <![CDATA[CF 3 > <![CDATA[CF 3 > H H <![CDATA[CF 3 > <![CDATA[CF 3 > H H <![CDATA[CF 3 > <![CDATA[CF 3 > <![CDATA[NO 2 > H H H H <![CDATA[NO 2 > <![CDATA[NO 2 > H H H H <![CDATA[NO 2 > <![CDATA[NO 2 > H H <![CDATA[NO 2 > <![CDATA[NO 2 > H H <![CDATA[NO 2 > <![CDATA[NO 2 > H H <![CDATA[NO 2 > <![CDATA[NO 2 > <![CDATA[CH 3 > H H H H <![CDATA[CH 3 > <![CDATA[CH 3 > H H H H <![CDATA[CH 3 > <![CDATA[CH 3 > H H <![CDATA[CH 3 > <![CDATA[CH 3 > H H <![CDATA[CH 3 > <![CDATA[CH 3 > H H <![CDATA[CH 3 > <![CDATA[CH 3 >

[0083] Specific examples of the compound (1) are shown below. Among them, the compound (1) is not limited to them.

[0084]

[0085]

[0086]

[0087]

[0088] The compound (1) of the present embodiment is particularly preferably a compound represented by the following formula.

[0089]

[0090] By making such a compound have 4 cyano groups, it is possible to suppress the leakage current in the dark, and in particular, it exhibits excellent characteristics as a material for a photoelectric conversion element. As the reason, it can be considered as follows. The energy level of the lowest unoccupied orbital of this compound decreases, and at the same time, the energy level of the highest occupied orbital also decreases, maintaining both a low energy level of the lowest unoccupied orbital and a high energy gap. It is considered that thereby, the above compound can suppress the leakage current in the dark and can obtain excellent characteristics as a material for a photoelectric conversion element. However, the reason is not limited to this.

[0091] The compound (1) can be synthesized by, for example, the following route.

[0092]

[0093] More specifically, by, for example, a side chain addition reaction derived from a commercially available compound (α), a compound (1) in which X is an oxygen atom can be obtained. In addition, by further performing an imide reaction, a compound (1) in which X is NR 6 can be obtained. Alternatively, by passing through an intermediate obtained by imidizing a commercially available compound (α) and performing a side chain addition reaction, a compound (1) in which X is NR 6 can be obtained. It should be noted that by adjusting the equivalent amount of the reagent in the imide reaction, one of the two Xs present in the formula (1) can be an oxygen atom and the other can be NR 6compound. More specifically, imidization can be synthesized by the method described in, for example, Organic Electronics, 63, 250 (2018). In addition, a compound into which R 1 ~R 5 is introduced can be used to carry out a side-chain addition reaction, or R 1 ~R 5 can be introduced after the side-chain addition reaction. The side-chain addition reaction can be carried out by a coupling reaction or the method described in Asian Journal of Organic Chemistry, 2, 779 (2013).

[0094] (Material for photoelectric conversion element)

[0095] The compound (1) of the present embodiment can be used as a material for a photoelectric conversion element. More specifically, it can be used as a material contained in each layer of the photoelectric conversion element described later. Among them, from the viewpoint of more effectively and reliably exerting the effects described in the present invention, the compound (1) is preferably contained in the auxiliary layer, and more preferably contained in at least one of the electron transport layer and the hole blocking layer.

[0096] In addition, the compound (1) of the present embodiment can be directly used as a photosensitive material, or can be mixed with other materials to be used as a photosensitive composition. The content of the compound (1) in the photosensitive composition can be 50% by mass or more based on the total amount of the composition. In addition, the content can be 95% by mass or less, can be 90% by mass or less, or can be 80% by mass or less. The materials other than the compound (1) in the above photosensitive composition are not particularly limited as long as they are materials usually contained in a photosensitive composition. Examples of such materials include: the n-type semiconductor material, p-type semiconductor material, and light absorption material described later. These can be used alone or in combination of two or more.

[0097] (Organic thin film)

[0098] The organic thin film of the present embodiment contains the compound (1) of the present embodiment or the above-described material for a photoelectric conversion element. Such an organic thin film can be produced by a general dry film-forming method or wet film-forming method. Specifically, examples include: resistance heating evaporation, electron beam evaporation, sputtering, and molecular layer deposition as vacuum processes; casting, spin coating, dip coating, knife coating, bar coating, and spray coating as solution processes; printing methods such as inkjet printing, screen printing, offset printing, and letterpress printing; and soft lithography methods such as microcontact printing. Generally, for materials for photoelectric conversion elements, from the viewpoint of ease of processing, it is desirable to use them in a process of coating the compound in a solution state. However, in the case of a photoelectric conversion element in which organic thin films are laminated, since there is a risk that the coating solution may erode the underlying film, a dry film-forming method such as resistance heating evaporation is preferred.

[0099] For example, in the dry film-forming method, a composition is prepared by mixing the material for a photoelectric conversion element of the present embodiment and, if necessary, other materials corresponding to the use of the photoelectric conversion element, and the composition is evaporated onto a substrate or other film under vacuum, whereby an organic thin film can be obtained. Further, in the wet film-forming method, a liquid composition is prepared by mixing the photoelectric conversion film of the present embodiment and, if necessary, other materials corresponding to the use of the photoelectric conversion element with a solvent, and the composition is coated and printed onto a substrate or other film and then dried, whereby an organic thin film can be obtained.

[0100] The organic thin film of the present embodiment may also contain materials other than the material for a photoelectric conversion element, i.e., the compound (1), of the present embodiment. The content of the compound (1) in the organic thin film of the present embodiment is not particularly limited as long as it exhibits the performance required for use as a material for a photoelectric conversion element. For example, the content of the compound (1) may be 50% by mass or more based on the total amount of the organic thin film, and from the viewpoint of more effectively and reliably exerting the effects produced by the present invention, it is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. The upper limit of the content of the compound (1) may be 100% by mass. When the organic thin film of the present embodiment contains a material other than the compound (1), the material is not particularly limited as long as it is generally used as a material for a photoelectric conversion element. Examples of such materials include: an n-type semiconductor material, a p-type semiconductor material, and a light absorption material described later, and molybdenum oxide, an alkali metal, and an alkali metal compound called a doping material, and these may be used alone or in combination of two or more.

[0101] The thickness of the organic thin film depends on the resistance value / charge mobility of each substance and is not particularly limited, but is generally 0.5 nm or more and 5000 nm or less, may be 1 nm or more and 1000 nm or less, or may be 5 nm or more and 500 nm or less.

[0102] From the viewpoint of more effectively and reliably achieving the effects of the present invention, the organic film of the present embodiment preferably has a maximum absorption wavelength of the light absorption band at 450 nm or less.

[0103] (Photoelectric conversion element)

[0104] The photoelectric conversion element of the present embodiment refers to an element that generates charges corresponding to the amount of incident light, passes through a capacitor (hereinafter also referred to as a "cumulative portion") for accumulating the generated charges, a transistor circuit for reading (hereinafter also referred to as a "reading portion"), and outputs to the outside of the photoelectric conversion element. Here, in the photoelectric conversion element, a photoelectric conversion film that absorbs at least a part of the incident light is disposed between a pair of opposing electrodes, and light is incident on the photoelectric conversion element from above the electrodes. In addition, the photoelectric conversion film is a photosensitive film containing a material that absorbs at least a part of the incident light in the infrared region, and holes and electrons are generated as a result of the incident light. In addition, the photoelectric conversion element of the present embodiment may also have a photoelectric conversion element (hereinafter also referred to as an "infrared photoelectric conversion element") that generates charges corresponding to the amount of incident light in the infrared region. Here, in the infrared photoelectric conversion element, a photoelectric conversion film that absorbs infrared rays (hereinafter also referred to as an "infrared photoelectric conversion film") is disposed between a pair of opposing electrodes, and light is incident on the infrared photoelectric conversion element from above the electrodes. In addition, the infrared photoelectric conversion film is a photosensitive film containing a material that absorbs at least a part of the incident light in the infrared region (hereinafter also referred to as an "infrared absorption material"), and holes and electrons are generated as a result of the incident light.

[0105] Appropriately refer to Figure 1 The photoelectric conversion element of the present embodiment will be described. The photoelectric conversion element 100 includes a lower electrode 102 as a first electrode film, an upper electrode 106 as a second electrode film, and a photoelectric conversion film 110 disposed between the lower electrode 102 and the upper electrode 106. The photoelectric conversion element 100 may include a substrate 101 that is generally insulating on the side opposite to the photoelectric conversion film 110 of the upper electrode 106.

[0106] When the photoelectric conversion film 110 has hole transportability or electron transportability, the lower electrode 102 and the upper electrode 106 function as follows: extracting holes from the photoelectric conversion film 110 and trapping them, or extracting electrons and discharging them. The materials that can be used as these electrodes are not particularly limited as long as they have a certain degree of conductivity, and are preferably selected considering the adhesion to the adjacent photoelectric conversion film 110, electron affinity, ionization potential, and stability. Examples of materials that can be used as electrodes include conductive metal oxides such as tin oxide (NESA), indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); metals such as gold, silver, platinum, chromium, aluminum, iron, cobalt, nickel, and tungsten; inorganic conductive substances such as copper iodide and copper sulfide; conductive polymers such as polythiophene, polypyrrole, and polyaniline; and carbon. These materials can be used alone or in combination of multiple kinds.

[0107] The lower electrode 102 as the first electrode film includes a conductive film having light transmissibility, for example, indium tin oxide (ITO). The material constituting the lower electrode 102 is not limited to ITO. For example, it can be listed as: tin oxide (SnO 2 )-based materials doped with a dopant, and zinc oxide-based materials doped with a dopant in zinc oxide (ZnO). Examples of zinc oxide-based materials include aluminum zinc oxide (AZO) doped with aluminum (Al) as a dopant, gallium zinc oxide (GZO) doped with gallium (Ga), and indium zinc oxide (IZO) doped with indium (In). Or as the material constituting the lower electrode 102, for example, it can be listed as: CuI, InSbO 4 , ZnMgO, CuInO 2 , MgIN 2 O 4 , CdO, and ZnSnO 3 . The thickness of the lower electrode 102 can be, for example, 5 nm or more and 3000 nm or less, 5 nm or more and 500 nm or less, or 10 nm or more and 300 nm or less.

[0108] The upper electrode 106 as the second electrode film can be composed of a conductive film having the same light transmissibility as the lower electrode 102, or can be composed of a metal such as aluminum commonly used in the electrodes of photoelectric conversion elements. In addition, in a solid-state imaging device using a solid-state imaging element as a single pixel, the upper electrode 106 can be separated according to each pixel, or can be formed as a common electrode for each pixel. The thickness of the upper electrode 106 is, for example, 5 nm or more and 3000 nm or less, 5 nm or more and 500 nm or less, or 10 nm or more and 300 nm or less.

[0109] The conductivity of the material used for the electrodes such as the first electrode film and the second electrode film is not particularly limited as long as it does not excessively hinder the light reception of the photoelectric conversion element, but from the perspective of the signal strength and power consumption of the photoelectric conversion element, the conductivity is preferably as high as possible. For example, as a transparent electrode, if it is an ITO film with a sheet resistance value of less than 300Ω / □, it can fully function as an electrode. However, commercial products of substrates having an ITO film with a conductivity of about several Ω / □ (for example, 5 to 9Ω / □) can also be obtained, and substrates with such high conductivity are desired.

[0110] The thickness of the electrode when using the ITO film can be arbitrarily selected in consideration of conductivity, but is usually more than 5nm and less than 3000nm, preferably more than 10nm and less than 300nm. As a method for forming a film such as ITO, it can be listed: a conventionally known vapor deposition method, an electron beam method, a sputtering method, a chemical reaction method, and a coating method. The ITO film disposed on the substrate can be subjected to UV-ozone treatment or plasma treatment as required.

[0111] In addition, when stacking a plurality of photoelectric conversion films with different detected wavelengths, the electrode film used between each photoelectric conversion film must be able to transmit light of wavelengths other than the light detected by each photoelectric conversion film. From this point of view, the electrode film preferably uses a material that can transmit more than 90% of the incident light, and more preferably uses a material that can transmit more than 95% of the light. It should be noted that the above-mentioned electrode film is a film of an electrode other than the above-mentioned pair of electrodes.

[0112] In addition, when the lower part of the photoelectric conversion element in this embodiment is further provided with a visible light photoelectric conversion unit that senses infrared light or light in different visible light regions, the electrode used in the above-mentioned photoelectric conversion element preferably has a transmittance of visible light and infrared light of more than 90%, and more preferably more than 95%.

[0113] As an electrode material that meets such conditions, a transparent conductive oxide (TCO) with high transmittance to visible light and infrared light and low resistance is preferred. Although metal thin films such as gold can be used as electrodes, if the transmittance is set to more than 90%, the resistance value will increase extremely. Therefore, TCO is preferred as an electrode. As TCO, ITO, IZO, AZO, FTO, SnO 2 、TiO 2 and ZnO 2 .

[0114] The method for forming the electrode is not particularly limited and can be appropriately selected in consideration of the suitability with the electrode material. When using a transparent electrode, as its forming method, specifically, wet methods such as printing method and coating method, physical methods such as vacuum evaporation method, sputtering method and ion plating method, and chemical methods such as CVD and plasma CVD method can be cited. In addition, when the electrode material is a transparent conductive metal oxide such as ITO, as its forming method, for example, electron beam method, sputtering method, resistance heating evaporation method, chemical reaction method (such as sol-gel method, etc.) and the method of coating the dispersion of the metal oxide can be cited. Furthermore, UV-ozone treatment and plasma treatment can also be performed on the transparent conductive metal oxide film such as ITO.

[0115] The photoelectric conversion film 110 may contain the material for the photoelectric conversion element of the present embodiment, or may contain the above-mentioned organic film. More specifically, for example, the photoelectric conversion film 110 includes a photoelectric conversion layer 104, a first auxiliary layer 103 on the lower electrode film 102 side of the photoelectric conversion layer 104, and a second auxiliary layer 105 on the upper electrode film 106 side of the photoelectric conversion layer 104. It should be noted that Figure 1 The shown photoelectric conversion film 110 has a first auxiliary layer 103 and a second auxiliary layer 105, but the photoelectric conversion film may only have any one of these auxiliary layers. Or, the photoelectric conversion film may not have any auxiliary layer and only have the photoelectric conversion layer 104. When the photoelectric conversion film does not have an auxiliary layer, the photoelectric conversion layer 104 is the above-mentioned organic film. When the photoelectric conversion film has an auxiliary layer, at least one of the photoelectric conversion layer 104 and the auxiliary layer is the above-mentioned organic film. However, from the viewpoint of more effectively and reliably achieving the effects produced by the present invention, the auxiliary layer is preferably the above-mentioned organic film containing the material for the photoelectric conversion element of the present embodiment.

[0116] The photoelectric conversion layer 104 may be an organic semiconductor film commonly used as a photoelectric conversion layer, or may be the above-mentioned organic film. In addition, in the photoelectric conversion layer 110, these organic semiconductor films and organic films may be one layer or multiple layers. When it is one layer, a p-type organic semiconductor film, an n-type organic semiconductor film or a mixed film thereof (hereinafter may be "bulk heterojunction structure") is used. On the other hand, when it is multiple layers, the number of layers may be about 2 to 10 layers, and may be a structure formed by laminating any of a p-type organic semiconductor film, an n-type organic semiconductor film or a mixed film thereof (hereinafter may be "bulk heterojunction structure"), and a buffer layer may be inserted between the layers.

[0117] The photo-electric conversion layer 104 of the present embodiment may contain the material for the photo-electric conversion element of the present embodiment, may not contain it, or may contain materials other than the material for the photo-electric conversion element of the present embodiment. Among them, when the photo-electric conversion layer 104 contains at least one of an organic p-type semiconductor, an organic n-type semiconductor, and a light absorption material, it is preferable because the incident light energy of a desired wavelength can be converted into an electric signal more efficiently. Among them, for the light absorption material, if it is an organic p-type semiconductor, it is easy to supply electrons (that is, the ionization potential is small), or if it is an organic n-type semiconductor, it is easy to accept electrons (that is, the electron affinity is large), and it is preferable because the incident light energy can be converted into an electric signal more efficiently. Here, the ionization potential (HOMO level) is a value measured by a photoelectron yield spectroscopy or a photoelectron spectroscopy. In addition, the electron affinity (LUMO level) is a band gap value calculated from the longest wavelength absorption end of the near-infrared light spectroscopy, and is a value obtained by subtracting the above HOMO level, or a value measured by a reverse photoelectron spectroscopy.

[0118] When using an organic semiconductor film, the film may be one layer or two or more layers. The organic semiconductor film may be an organic p-type semiconductor film, an organic n-type semiconductor film, a light absorption material film, or a mixed film (bulk heterojunction structure) of these. In particular, the organic semiconductor film preferably has a bulk heterojunction bonding structure layer. In such a case, by making the photo-electric conversion film contain the bulk heterojunction bonding structure, the disadvantage of the short carrier diffusion length of the photo-electric conversion film can be compensated, and the photo-electric conversion efficiency can be improved.

[0119] The thickness of the photo-electric conversion layer 104 can be, for example, 0.5 nm or more and 5000 nm or less, 1 nm or more and 1000 nm or less, or 5 nm or more and 500 nm or less.

[0120] Hereinafter, the organic semiconductor will be described in detail.

[0121] The organic p-type semiconductor is a donor-type organic semiconductor (hereinafter also referred to as "donor-type organic compound"), and mainly refers to an organic compound having a property of easily supplying electrons, typified by a hole-transporting organic compound. More specifically, it is an organic compound having a small ionization potential when two organic materials are used in contact. Therefore, as the donor-type organic compound, any organic compound can be used as long as it is an organic compound having an electron-donating property.

[0122] Examples of such donor organic compounds include: triarylamine compounds, benzidine compounds, pyrazoline compounds, styrylamine compounds, hydrazone compounds, triphenylmethane compounds, carbazole compounds, polysilane compounds, thiophene compounds, phthalocyanine compounds, cyanine compounds, merocyanine compounds, oxonol compounds, polyamine compounds, indole compounds, pyrrole compounds, pyrazole compounds, polyarylene compounds, fused aromatic carbocyclic compounds (e.g., naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, and fluoranthene derivatives), and metal complexes having a nitrogen-containing heterocyclic compound as a ligand. It should be noted that these are not limited thereto. As described above, any organic compound can be used as a donor organic semiconductor as long as its ionization potential is smaller than that of the organic compound used as an acceptor organic compound.

[0123] An organic n-type semiconductor refers to an acceptor organic semiconductor (hereinafter also referred to as "acceptor organic compound"), mainly an organic compound having a property of easily accepting electrons, represented by an electron-transporting organic compound. More specifically, it is an organic compound having a larger electron affinity when two organic compounds are brought into contact and used. Therefore, as an acceptor organic compound, any organic compound can be used as long as it is an organic compound having an electron-accepting property.

[0124] Examples of such acceptor organic compounds include: fused aromatic carbocyclic compounds (e.g., naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives, fullerene derivatives), 5- to 7-membered heterocyclic compounds containing a nitrogen atom, an oxygen atom, or a sulfur atom (e.g., pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, quinoxaline, quinazoline, phthalazine, cinnoline, isoquinoline, pteridine, acridine, phenazine, phenanthroline, tetrazole, pyrazole, imidazole, thiazole, oxazole, indazole, benzimidazole, benzotriazole, benzoxazole, benzothiazole, carbazole, purine, triazolopyridazine, triazolopyrimidine, tetrazaindene, oxadiazole, imidazopyridine, pyrrolidine, pyrrolopyridine, thiadiazolopyridine, dibenzoazepine, and tribenzoazepine), polyarylene compounds, fluorene compounds, cyclopentadiene compounds, silyl compounds, and metal complexes having a nitrogen-containing heterocyclic compound as a ligand. It should be noted that these are not limited thereto. As described above, any organic compound can be used as an acceptor organic semiconductor as long as its electron affinity is higher than that of the organic compound used as a donor organic compound.

[0125] A light-absorbing material is a compound having a maximum light absorption wavelength in the visible light region, particularly in the range above 450 nm and below 650 nm. It is desirable that the absorption intensity of the light-absorbing material at the maximum light absorption wavelength is greater than the absorption intensity of a donor organic compound or an acceptor organic compound at the maximum light absorption wavelength. By having such an absorption intensity, incident light can be selectively absorbed at the maximum light absorption wavelength of the light-absorbing material. After the incident light is absorbed by the light-absorbing material and photons are converted into excitons, exciton separation occurs at the interface between the donor organic compound and the acceptor organic compound, whereby carriers of holes and electrons can be efficiently generated.

[0126] As such a light-absorbing material, compounds generally referred to as pigments can be used. For example, phthalocyanine derivatives, subphthalocyanine derivatives, quinacridone derivatives, porphyrin derivatives, naphthalene or perylene derivatives, phthaloperylene derivatives, styryl derivatives, cyanine derivatives, hemicyanine derivatives, merocyanine derivatives, Rhodacyanine derivatives, oxonol derivatives, hemioxonol derivatives, croconium derivatives, squarylium derivatives, azamethine derivatives, arylene derivatives, azo derivatives, azomethine derivatives, metallocene derivatives, fulgide derivatives, phenazine derivatives, phenothiazine derivatives, polyene derivatives, acridine derivatives, acridone derivatives, diphenylamine derivatives, triarylamine derivatives such as triphenylamine, naphthylamine, and styrylamine, quinophthalone derivatives, phenoxazine derivatives, chlorophyll derivatives, rhodamine derivatives, diphenylmethane or triphenylmethane derivatives, xanthene derivatives, acridine derivatives, phenoxazine derivatives, quinoline derivatives, oxazine derivatives, thiazine derivatives, quinone derivatives, benzoquinone derivatives, naphthoquinone derivatives, anthraquinone derivatives, indigo or thioindigo derivatives, pyrrole derivatives, pyridine derivatives, dipyrromethene derivatives, indole derivatives, diketopyrrolopyrrole derivatives, coumarin derivatives, fluorene derivatives, fluorenone derivatives, fluoranthene derivatives, anthracene derivatives, pyrene derivatives, carbazole derivatives, phenylenediamine derivatives, benzidine derivatives, phenanthroline derivatives, imidazole derivatives, oxazoline derivatives, thiazoline derivatives, triazole derivatives, thiadiazole derivatives, oxazole derivatives, thiazole derivatives, oxadiazole derivatives, thiophene derivatives, selenophene derivatives, silole derivatives, germole derivatives, stilbene derivatives, phenylene vinylene derivatives, pentacene derivatives, rubrene derivatives, thienothiophene derivatives, benzodithiophene derivatives, xanthene-xanthene derivatives, and fullerene derivatives can be cited. It should be noted that the present invention is not limited to these. As described above, as long as the absorption intensity of a compound is greater than the absorption intensity of a donor-type organic compound or an acceptor-type organic compound at the maximum absorption wavelength, the compound can be used as a light-absorbing material. In addition, the light-absorbing material may also serve as a donor-type organic compound or an acceptor-type organic compound.

[0127] The first auxiliary layer 103 includes at least one of, for example, a hole blocking layer and an electron transport layer. When the first auxiliary layer 103 includes both of them, the electron transport layer and the hole blocking layer are usually stacked in this order from the side of the photoelectric conversion layer 104. The electron transport layer functions to transport electrons generated by the photoelectric conversion layer 104 to the first electrode 102 and to block the movement of holes from the first electrode 102 at the electron transport end to the photoelectric conversion layer 104. The hole blocking layer functions to prevent the movement of holes from the first electrode 102 to the photoelectric conversion layer 104, prevent recombination in the photoelectric conversion layer 104, reduce dark current, reduce noise, and expand the dynamic range. In addition, one layer can have the functions of both a hole blocking layer and an electron transport layer.

[0128] The second auxiliary layer 105 includes at least one of, for example, an electron blocking layer and a hole transport layer. When the second auxiliary layer 105 includes both of them, the hole transport layer and the electron blocking layer are usually stacked in this order from the side of the photoelectric conversion layer 104. The hole transport layer functions to transport generated holes from the photoelectric conversion layer 104 to the second electrode 106 and to block the movement of electrons from the second electrode 106 at the hole transport end to the photoelectric conversion layer 104. The electron blocking layer functions to prevent the movement of electrons from the second electrode 106 to the photoelectric conversion layer 104, prevent recombination in the photoelectric conversion layer 104, reduce dark current, reduce noise, and expand the dynamic range. In addition, one layer can have the functions of both an electron blocking layer and a hole transport layer.

[0129] The material for the photoelectric conversion element of the present embodiment may also be included in any one of these first auxiliary layer 103 and second auxiliary layer 105, and is preferably included in the first auxiliary layer 103. In the photoelectric conversion element of the present embodiment, among these first auxiliary layer 103 and second auxiliary layer 105, it is preferred that the first auxiliary layer 103 includes the above-mentioned organic thin film. In addition, the material for the photoelectric conversion element of the present embodiment is more preferably included in at least one of the hole blocking layer and the electron transport layer in the first auxiliary layer 103. In the photoelectric conversion element of the present embodiment, it is preferred that at least one of the hole blocking layer and the electron transport layer is the above-mentioned organic thin film. Thereby, the effects produced by the present invention can be exerted more effectively and reliably.

[0130] Hereinafter, materials other than the material for the photoelectric conversion element of the present embodiment that can be included in each layer of the auxiliary layer will be described.

[0131] As the material for the hole transport layer, there is no particular limitation as long as it is known as a hole transport layer in a photoelectric conversion element such as a solid-state imaging element. For example, polyaniline and its doping materials, and cyanide compounds described in International Publication No. 2006 / 019270 can be cited.

[0132] As materials constituting the hole transport layer, more specifically, for example, selenium, iodides such as copper iodide (CuI), cobalt complexes such as layered cobalt oxides, CuSCN, molybdenum oxide (MoO 3 etc.), nickel oxide (NiO etc.), 4CuBr·3S(C 4 H 9 ) and organic hole transport materials. Among them, as iodides, for example, copper iodide (CuI) can be cited. As layered cobalt oxides, for example, A x CoO 2 (where A represents Li, Na, K, Ca, Sr or Ba, 0 ≤ X ≤ 1). In addition, as organic hole transport materials, for example, poly-3-hexylthiophene (P3HT), polythiophene derivatives such as poly(3,4-ethylenedioxythiophene) (PEDOT; trade name "BaytronP" manufactured by Starck V-tec Co., Ltd. for example), fluorene derivatives such as 2,2',7,7'-tetra-(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-MeO-TAD), carbazole derivatives such as polyvinylcarbazole, triphenylamine derivatives, diphenylamine derivatives, polysilane derivatives and polyaniline derivatives. Further, as materials for the hole transport layer, for example, CuInSe 2 and compound semiconductors with monovalent copper such as copper sulfide (CuS), gallium phosphide (GaP), nickel oxide (NiO), cobalt oxide (CoO), iron oxide (FeO), bismuth oxide (Bi 2 O 3 ), molybdenum oxide (MoO 2 ) and chromium oxide (Cr 2 O 3 ).

[0133] In addition, if the hole transport layer has a LUMO energy level higher than that of the photoactive layer, it can be given an electron blocking function with a rectifying effect that inhibits the movement of electrons generated in the photoactive layer toward the electrode side, so it is preferred. Such a hole transport layer is also called an electron blocking layer.

[0134] Among the materials constituting the electron blocking layer, as low-molecular organic compounds, for example, the following can be cited: aromatic diamine compounds such as N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD) and 4,4'-bis[N-(naphthyl)-N-phenylamino]biphenyl (α-NPD), oxazole, oxadiazole, triazole, imidazole, imidazolone, stilbene derivatives, pyrazoline derivatives, tetrahydroimidazole, polyarylalkane, butadiene, 4,4',4''-tris(N-(3-methylphenyl)N-phenylamino)triphenylamine (m-MTDATA), porphyrin, copper tetraphenylporphyrin, phthalocyanine, copper phthalocyanine, and titanium oxyphthalocyanine and other porphyrin compounds, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styryl anthracene derivatives, fluorenone derivatives, hydrazone derivatives, and silazane derivatives. In addition, as high-molecular organic compounds, for example, the following can be cited: polymers of phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, methylpyridine, thiophene, acetylene, and diacetylene and their derivatives. Even if it is not an electron-donating compound, as long as it is a compound with sufficient hole transportability, it can be used as a material for constituting the electron blocking layer. Further, among the materials constituting the electron blocking layer, as inorganic compounds, for example, the following can be cited: metal oxides such as calcium oxide, chromium oxide, copper chromium oxide, manganese oxide, cobalt oxide, nickel oxide, copper oxide, copper gallium oxide, copper strontium oxide, niobium oxide, molybdenum oxide, copper indium oxide, silver indium oxide, and indium oxide, selenium, tellurium, and antimony sulfide. These can be used alone or in combination of two or more.

[0135] From the viewpoint of suppressing dark current and preventing the reduction of photoelectric conversion efficiency, the thickness of the hole transport layer is preferably 10 nm or more and 300 nm or less, more preferably 30 nm or more and 250 nm or less, and further preferably 50 nm or more and 200 nm or less.

[0136] As a method for forming the hole transport layer and the electron blocking layer, it can be a conventionally known method, and it can be either a dry film-forming method such as a vacuum evaporation method or a wet film-forming method such as a solution coating method. However, from the viewpoint of leveling the coating surface, a wet film-forming method is preferred. As the dry film-forming method, for example, the following can be cited: evaporation methods such as a vacuum evaporation method and a sputtering method. Evaporation can be either physical vapor deposition (PVD) or chemical vapor deposition (CVD), but physical vapor deposition such as vacuum evaporation is preferred. As the wet film-forming method, for example, the following can be cited: inkjet method, spray method, nozzle printing method, spin coating method, dip coating method, casting method, die coating method, roll coating method, bar coating method, and gravure coating method.

[0137] As the material constituting the electron transport layer, there is no particular limitation as long as it is known as an electron transport layer in a photoelectric conversion element such as a solid-state imaging element. For example, octaazaporphyrin, perfluorides of p-type semiconductors (such as perfluoropentacene, perfluorophthalocyanine, etc.), fullerenes, fullerene derivatives (such as [6,6]-phenyl-C61-butyric acid methyl ester; PCBM, etc.), organic compounds such as perylene, indenoindene and indenoindene derivatives, titanium oxide (TiO 2 etc.), nickel oxide (NiO), tin oxide (SnO 2 ), tungsten oxides (WO 2 , WO 3 , W 2 O 3 etc.), zinc oxide (ZnO), niobium oxide (Nb 2 O 5 etc.), tantalum oxide (Ta 2 O 5 etc.), yttrium oxide (Y 2 O 3 etc.) and inorganic oxides such as strontium titanate (SrTiO 3 etc.). The electron transport layer can be porous or dense. When these are laminated, it is preferable to laminate and dispose a porous electron transport layer and a dense electron transport layer in this order from the side of the photoelectric conversion film.

[0138] In addition, if the electron transport layer has a HOMO level lower than the HOMO level of the photoelectric conversion film, a hole blocking function having a rectifying effect of suppressing the movement of holes generated in the photoelectric conversion film toward the counter electrode side can be imparted, and thus it is preferable. Such an electron transport layer is also called a hole blocking layer.

[0139] Examples of the material constituting the hole blocking layer include oxadiazole derivatives such as 1,3-bis(4-tert-butylphenyl-1,3,4-oxadiazolyl)benzene (OXD-7), anthraquinone dimethane derivatives, diphenylquinone derivatives, bathocuproine, bathophenanthroline and their derivatives, triazine compounds, triazole compounds, tris(8-hydroxyquinoline)aluminum complex, bis(4-methyl-8-quinolinolato)aluminum complex, silafluorene compounds, porphyrin compounds, styrene compounds such as DCM (4-dicyanomethylene-2-methyl-6-(4-(dimethylaminostyryl))-4H-pyran), n-type semiconductor materials such as naphthalene tetracarboxylic dianhydride (NTCDA), naphthalene tetracarboxylic diimide, perylene tetracarboxylic dianhydride (PTCDA), perylene tetracarboxylic diimide, n-type inorganic oxides such as titanium oxide, zinc oxide and gallium oxide, and alkali metal fluorides such as lithium fluoride, sodium fluoride and cesium fluoride. Further, those obtained by doping an alkali metal compound into an organic semiconductor molecule have a function of improving the electrical junction with the counter electrode, and thus are preferred. These may be used alone or in combination of two or more.

[0140] From the viewpoint of suppressing dark current and preventing reduction in photoelectric conversion efficiency, the thickness of the electron transport layer is preferably 10 nm or more and 300 nm or less, more preferably 30 nm or more and 250 nm or less, and still more preferably 50 nm or more and 200 nm or less.

[0141] As a method for forming the electron transport layer and the hole blocking layer, a conventionally known method may be used, and any of a dry film-forming method such as a vacuum evaporation method and a wet film-forming method such as a solution coating method may be used. However, from the viewpoint of leveling the coating surface, a wet film-forming method is preferred. Examples of the dry film-forming method include vapor deposition methods such as vacuum evaporation method and sputtering method. The vapor deposition may be either physical vapor deposition (PVD) or chemical vapor deposition (CVD), but physical vapor deposition such as vacuum evaporation is preferred. Examples of the wet film-forming method include inkjet method, spraying method, nozzle printing method, spin coating method, dip coating method, casting method, die coating method, roll coating method, bar coating method and gravure coating method.

[0142] The photoelectric conversion element of the present embodiment may include a single layer or two or more auxiliary layers different from the first auxiliary layer 103 between the first auxiliary layer 103 and the lower electrode 102. Examples of such an auxiliary layer include a hole injection layer that improves the hole injection property from the lower electrode 102 to the first auxiliary layer 103. Examples of the material constituting the hole injection layer include phthalocyanine derivatives, starburst amine compounds such as m-MTDATA (4,4’,4”-tris[ phenyl(m-tolyl)amino]triphenylamine), polythiophenes such as PEDOT (poly(3,4-ethylenedioxythiophene)), and polymer materials such as polyvinylcarbazole derivatives. The thickness of this auxiliary layer may be the same as that of the first auxiliary layer 103.

[0143] The photoelectric conversion element of the present embodiment may include a single layer or two or more auxiliary layers different from the second auxiliary layer 105 between the second auxiliary layer 105 and the upper electrode 106. Examples of such an auxiliary layer include an electron injection layer and an electron transport layer that improve the electron injection property from the upper electrode 106 to the second auxiliary layer 105. Examples of the material constituting the electron injection layer include metals such as cesium, lithium, and strontium, and lithium fluoride. The material constituting the electron transport layer may be the same as above. In addition, the thickness of this auxiliary layer may be the same as that of the second auxiliary layer 105.

[0144] The photoelectric conversion element of the present embodiment may further include at least one of an interlayer contact improvement layer and a crystallization prevention layer located between these layers in addition to the above-described layers.

[0145] The interlayer contact improvement layer functions to reduce the damage caused to the closest underlying film, such as the photoelectric conversion film 110, during the film formation of the upper electrode 106. In particular, high-energy particles present in the apparatus used for the film formation of the upper electrode 106, for example, in the case of the sputtering method, sputtering particles, secondary electrons, Ar particles, oxygen anions, etc. collide with the closest underlying film and deteriorate, sometimes resulting in performance degradation such as an increase in leakage current and a decrease in sensitivity. As one method of preventing this, it is preferable to provide an interlayer contact improvement layer on the upper layer of the closest underlying film. The material of the interlayer contact improvement layer is preferably an organic substance such as copper phthalocyanine, NTCDA, PTCDA, [dipyrazino[2,3-f:2’,3’-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile] (HATCN), acetylacetonate complex, BCP, an organic-metal compound, or an inorganic substance such as MgAg or MgO. The thickness of the interlayer contact improvement layer varies within an appropriate range depending on the composition of the photoelectric conversion film, the thickness of the electrode film, etc., but particularly from the viewpoint of selecting a material that does not absorb in the visible light region or using it with a relatively thin thickness, it is preferably 2 nm or more and 500 nm or less.

[0146] As described above, on the photoelectric conversion element of the present embodiment, a capacitor for accumulating the generated charges, i.e., an accumulation unit, and a transistor circuit for reading out, i.e., a readout unit, are connected via a connection portion formed of a conductive material. In addition, as needed, the photoelectric conversion element includes a protective structure such as a protective film to avoid external air, a substrate for maintaining strength, and a microlens for condensing light, etc.

[0147] A readout unit is provided to read out a signal corresponding to the charges generated in the photoelectric conversion film. The readout unit is constituted by, for example, a CCD, a CMOS circuit, or a TFT circuit, etc., and is preferably shielded from light by a light-shielding layer disposed in the insulating layer. The readout circuit is electrically connected to the corresponding electrode via the connection portion. It should be noted that, in order to ensure the amount of charges required during readout, an accumulation unit constituted by a capacitor or the like may be interposed between the electrode and the connection portion. The connection portion is buried in the insulating layer and is a plug or the like for electrically connecting an electrode (for example, a transparent electrode or a counter electrode) to the readout unit. When the component thus constituted is a solid-state imaging element, if light is incident, the light is incident on the photoelectric conversion film, and charges are generated there. Electrons among the generated charges are captured (and accumulated) by one electrode, and holes are captured by the other electrode. A voltage signal corresponding to this amount is output to the outside of the solid-state imaging element through the readout unit.

[0148] (Imaging element)

[0149] If the imaging element of the present embodiment includes the photoelectric conversion element of the present embodiment, the other configurations can be the same as those of the conventional imaging element. For example, a plurality of the photoelectric conversion elements of the present embodiment are arranged in an array for the imaging element of the present embodiment. That is, by arranging a plurality of photoelectric conversion elements in an array, a solid-state imaging element that shows not only the incident light amount but also the incident position information is constituted.

[0150] The imaging element of the present embodiment may include one photoelectric conversion element of the present embodiment, or two or more may be stacked. In the case where two or more photoelectric conversion elements of the present embodiment are stacked, each photoelectric conversion element can selectively detect light in mutually different wavelength bands and perform photoelectric conversion. For example, in the case where three or more photoelectric conversion elements of the present embodiment are stacked, at least one can obtain a green signal, at least one of the others can obtain a blue signal, at least one of the others can obtain a red signal, and at least one of the others can obtain a color signal of infrared light. Thus, the imaging element can obtain a variety of color signals in one pixel without using a color filter. In addition, color signals other than the color signals detected by the photoelectric conversion element of the present embodiment can also be sensed by a device having a conventionally known silicon photodiode.

[0151] In an imaging element, when a photoelectric conversion element disposed closer to a light source does not block (i.e., transmits) the absorption wavelength of another photoelectric conversion element disposed behind it when viewed from the light source side, it is also possible to stack a device having a plurality of photoelectric conversion elements and silicon photodiodes.

[0152] In the imaging element, from the viewpoint of ease of molding, a part of the photoelectric conversion element can be configured as a thin film on the same plane without structural partitioning between adjacent photoelectric conversion elements.

[0153] The imaging element of the present embodiment may further include a substrate. The substrate is used to stack each layer thereon to manufacture the imaging element or to improve the mechanical strength of the imaging element. The type of the substrate is not particularly limited, and examples thereof include a semiconductor substrate, a glass substrate, and a plastic substrate.

[0154] (Optical sensor)

[0155] The optical sensor of the present embodiment only needs to include the imaging element of the present embodiment, and the other configurations may be the same as those of the conventional optical sensor. The optical sensor can receive light in the imaging element of the present embodiment and output an electrical signal corresponding to the amount of received light of the light.

[0156] (Solid-state imaging device)

[0157] The solid-state imaging device of the present embodiment only needs to include the imaging element of the present embodiment, and the other configurations may be the same as those of the conventional solid-state imaging device. The solid-state imaging device of the present embodiment can be, for example, a CMOS image sensor, and may have a pixel portion as an imaging region on a semiconductor substrate, and further may have a peripheral circuit portion in a peripheral region or directly below the pixel portion. The peripheral circuit portion has a row scanning portion, a horizontal selection portion, a column scanning portion, and a system control portion. The pixel portion includes the imaging element of the present embodiment.

[0158] The photoelectric conversion element of the present embodiment has the following advantages by using the material for the photoelectric conversion element of the present embodiment. That is, the photoelectric conversion element of the present embodiment is less likely to cause a short circuit or generate pinholes, so the dark current value is reduced. As a result, the photoelectric conversion element of the present embodiment has excellent leakage prevention properties (especially in the dark). Furthermore, the photoelectric conversion element of the present embodiment tends to easily exhibit a high contrast ratio, and in this case, has more excellent leakage prevention properties. In addition, although the material for the photoelectric conversion element is not likely to aggregate in the photoelectric conversion element of the present embodiment, its hole and electron transport properties are still excellent, so the photoelectric conversion efficiency is increased. Furthermore, the photoelectric conversion element of the present embodiment has good heat resistance by using the material for the photoelectric conversion element of the present embodiment, and the durability in the manufacturing process and practical environment is improved.

[0159] Examples

[0160] Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. It should be noted that the synthesized compound can be further purified by sublimation as needed.

[0161] <Synthesis Example 1>

[0162]

[0163] A mixture of 1.5 g of 2,6-dibromonaphthalene-1,4,5,8-tetracarboxylic dianhydride (manufactured by Tokyo Chemical Industry Co., Ltd.), 1.0 g of 4-cyanophenol (manufactured by Tokyo Chemical Industry Co., Ltd.), and 7 mL of isoquinoline (manufactured by Tokyo Chemical Industry Co., Ltd.) was stirred at 180 °C for 5 hours. Then, after cooling to room temperature, methanol was added, and the precipitated mixture was filtered. Further, it was washed with methanol to obtain Compound (2).

[0164]

[0165] A mixture obtained by adding 1.0 g of Compound (2) and 0.5 g of 4-aminobenzonitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) (2.1 molar equivalents relative to Compound (2)) to 10 mL of acetic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was stirred at 125 °C for 8 hours. Thereafter, it was cooled to room temperature, methanol was added, and the precipitated mixture was filtered. Further, it was washed with methanol to obtain Compound (3). The results of its NMR measurement are as follows.

[0166] 1 HNMR (500 MHz, DMSO-d6): 8.35 (s, 2H), 8.02 (d, 4H), 7.91 (d, 4H), 7.63 (d, 4H), 7.21 (d, 4H)

[0167] <Synthesis Example 2>

[0168]

[0169] Using m-cresol (manufactured by Fujifilm Wako Pure Chemical Corporation) instead of 4-cyanophenol, and otherwise operating in the same manner as in Synthesis Example 1, Compound (4) was obtained. The results of its NMR measurement are as follows.

[0170] 1 HNMR (500 MHz, DMSO-d6): 8.06 (s, 2H), 8.02 (d, 4H), 7.65 (d, 4H), 7.37 (m, 1H), 7.11 (d, 1H), 7.00 (s, 1H), 6.96 (dd, 1H), 2.32 (s, 6H)

[0171] <Synthesis Example 3>

[0172]

[0173] A mixture obtained by adding 2.0 g of 1,4,5,8-naphthalenetetracarboxylic dianhydride (hereinafter referred to as "Compound (5)") (manufactured by Tokyo Chemical Industry Co., Ltd.) and 1.5 g of aniline (manufactured by Tokyo Chemical Industry Co., Ltd.) (2.2 molar equivalents relative to Compound (5)) to 15 mL of acetic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was stirred under reflux at 125 °C for 8 hours. Thereafter, it was cooled to room temperature, methanol was added thereto, and the precipitated mixture was filtered. Further, after washing with methanol, pyridine was added and stirred for 5 minutes. Then, after filtration, it was washed with methanol and purified by sublimation to obtain Compound (6) as a white solid. The results of its NMR measurement are as follows.

[0174] 1 HNMR(500MHz,DMSO-d6): 8.73(s,4H),7.58~7.45(m,10H)

[0175] <Synthesis Example 4>

[0176]

[0177] A mixture obtained by adding 6.0 g of Compound (5), 6.1 g of isoquinoline (manufactured by Tokyo Chemical Industry Co., Ltd.) (2.1 molar equivalents relative to Compound (5)), and 6.6 g of 4-aminobenzonitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) (2.5 molar equivalents relative to Compound (5)) to 90 mL of m-cresol (manufactured by Tokyo Chemical Industry Co., Ltd.) was stirred at 180 °C for 8 hours. Thereafter, it was cooled to room temperature, methanol was added thereto, and the precipitate was filtered. Further, after washing with methanol, an aqueous potassium carbonate solution was added and stirred for 5 minutes. Then, after filtration, it was washed with water and methanol and purified by sublimation to obtain Compound (7) as a white solid. The results of its NMR measurement are as follows.

[0178] 1 HNMR(500MHz,HFIP-d2): 8.93(s,4H),8.77(dm,4H),7.55(dm,4H)

[0179] [Evaluation of Crystallinity of Compound]

[0180] The crystallinity of the synthesized compound was evaluated. The crystallinity evaluation was performed using a bench-top X-ray diffractometer (manufactured by Rigaku Corporation, product name (MiniFlex600)). The X-ray source was set to CuKα, and the maximum peak intensity of X-ray diffraction (XRD) was measured based on the spectrum obtained at a scanning speed of 20° / min. The results are shown in Table 1. It should be noted that the maximum peak intensity is represented by a relative value with the value of compound (4) set to 1.

[0181] [Fabrication and Evaluation of Organic Thin Films and Photoelectric Conversion Elements]

[0182] In the following Examples and Comparative Examples, an evaporation apparatus was used to fabricate organic thin films and photoelectric conversion elements, and current-voltage application measurements were performed under atmospheric conditions. The fabricated photoelectric conversion element was placed in a measurement chamber, and current-voltage application measurements were carried out. During the current-voltage application measurements, a semiconductor parameter analyzer (manufactured by Keithley) was used. The irradiation of light was performed using a light source device (manufactured by Asahi Spectra Co., Ltd., product name (PVL-3300)) under the conditions of an irradiation light wavelength of 550 nm and an irradiation light half-value width of 20 nm. The light-dark ratio is the value obtained by dividing the current value during light irradiation by the current value in the dark.

[0183] (Example 1)

[0184] On ITO transparent conductive glass (ITO manufactured by GEOMATEC Co., Ltd., thickness 100 nm), phthalocyanine boron chloride (purified product manufactured by Sigma Aldrich, purity > 99%, LUMO: -2.6 eV, energy level difference: 2.7 eV) as a photoelectric conversion layer was vacuum-deposited with a thickness of 100 nm. On top of it, tris(8-hydroxyquinoline) aluminum (Alq 3 ) as sublimated purified product (manufactured by Tokyo Chemical Industry Co., Ltd.) was vacuum-deposited with a thickness of 25 nm as auxiliary layer 1 by resistance heating evaporation. Then, compound (3) as auxiliary layer 2 was vacuum-deposited with a thickness of 25 nm by resistance heating evaporation. Then, aluminum as an electrode was fabricated with a thickness of 100 nm by vacuum deposition on auxiliary layer 2, thereby obtaining a photoelectric conversion element.

[0185] For the obtained photoelectric conversion element, with ITO and aluminum as electrodes, a voltage of 5 V was applied, and the current value in the dark and the current value during light irradiation were measured. The light-dark ratio was calculated based on the measurement results. The results are shown in Table 1. It should be noted that the dark current value is represented by a relative value with the value of Comparative Example 1 described later set to 1.

[0186] (Example 2)

[0187] Compound (4) was used in place of compound (3), and otherwise, the same operations as in Example 1 were carried out to fabricate a single-layer organic thin film and a photoelectric conversion element. The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0188] (Comparative Example 1)

[0189] Compound (5) was used in place of compound (3), and otherwise, the same operations as in Example 1 were carried out to fabricate a single-layer organic thin film and a photoelectric conversion element. The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0190] (Comparative Example 2)

[0191] Compound (6) was used in place of compound (3), and otherwise, the same operations as in Example 1 were carried out to fabricate a single-layer organic thin film and a photoelectric conversion element. The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0192] (Comparative Example 3)

[0193] Compound (7) was used in place of compound (3), and otherwise, the same operations as in Example 1 were carried out to fabricate a single-layer organic thin film and a photoelectric conversion element. The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0194] [Table 1]

[0195]

[0196] From the results shown in Table 1, it can be seen that: the dark current value of the photoelectric conversion element of the present invention shows a low value, and thus, it has excellent leakage prevention performance (especially in the dark). In particular, it can be seen that: in Example 1, due to the small maximum peak intensity of XRD, the crystallinity is low, it has a low LUMO and a large energy level difference, and thus, it shows a high on / off ratio and has more excellent leakage prevention performance. In summary, it can be known that: the compound of the present invention is suitable as a material for a photoelectric conversion element, especially suitable as a material contained in the electron transport layer and the hole blocking layer of a photoelectric conversion element.

[0197] Industrial Applicability

[0198] By using the material for a photoelectric conversion element containing the compound (1) of the present invention, a photoelectric conversion element excellent in required properties such as prevention of hole or electron leakage, transportability, and further heat resistance and visible light transparency can be provided. Therefore, the compound (1) of the present invention, the material for a photoelectric conversion element, the organic film, and the photoelectric conversion element have industrial availability in fields requiring such properties. Specifically, as a solid-state imaging element, it has industrial availability in imaging elements in security cameras, in-vehicle cameras, cameras for unmanned aerial vehicles, agricultural cameras, industrial cameras, medical cameras such as endoscope cameras, gaming cameras, digital still cameras, digital video cameras, mobile phone cameras, and cameras for other mobile devices; image reading elements in fax machines, scanners, copiers, etc.; and light sensors in biological and chemical sensors, etc. In addition, as a display using electroluminescence, it has industrial availability in television displays, touch displays, digital signage, wearable displays, electronic paper, head-up displays for mobile applications, etc.

[0199] This application is based on Japanese Patent Application (Japanese Patent Application No. 2023-069028) filed on April 20, 2023, the content of which is incorporated herein by reference.

[0200] Explanation of reference numerals

[0201] 100... Photoelectric conversion element, 101... Substrate, 102... Lower electrode, 103... First auxiliary layer, 104... Photoelectric conversion layer, 105... Second auxiliary layer, 106... Upper electrode, 110... Photoelectric conversion film.

Claims

1. A compound represented by the following formula (1): X is an oxygen atom or NR6, R1, R2, R3, R4, R5 and R6 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, a thiol group, an amino group, a cyano group, a carboxyl group, a nitro group, and an optionally substituted linear, branched or cyclic alkyl group, a thioalkyl group, a thioaryl group, an arylsulfonyl group, an aryloxy group, an alkylsulfonyl group, an alkylamino group, an arylamino group, an alkoxy group, an acylamino group, an acyloxy group, an aryl group, a carboxamide group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyl group and a monovalent heterocyclic group, and any adjacent R1, R2, R3, R4, R5 and R6 are optionally part of a fused aliphatic ring or a fused aromatic ring, and two R1, R2, R3, R4, R5 and X are optionally the same or different from each other, and the fused aliphatic ring and the fused aromatic ring optionally contain one or more atoms other than carbon.

2. The compound according to claim 1, wherein The energy level of the lowest unoccupied orbital of the compound represented by the formula (1) obtained by density functional theory is -6.00 eV or more and -3.40 eV or less.

3. The compound according to claim 1, wherein The difference between the energy level of the lowest unoccupied orbital and the energy level of the highest occupied orbital obtained by density functional theory of the compound represented by the formula (1) is 3.00 eV or more and 4.00 eV or less. The compound according to claim 1 , which is a material for a photoelectric conversion element. An organic thin film comprising the compound according to claim 1 . The organic thin film according to claim 5 , which has a light absorption band with a maximum absorption wavelength of 450 nm or less.

7. A photoelectric conversion element comprising a first electrode film, a second electrode film, and a photoelectric conversion film located between the first electrode film and the second electrode film, The photoelectric conversion film comprises the photoelectric conversion element material according to claim 4 .

8. A photoelectric conversion element comprising a first electrode film, a second electrode film, and a photoelectric conversion film located between the first electrode film and the second electrode film, The photoelectric conversion film comprises the organic thin film according to claim 5 .

9. The photoelectric conversion element according to claim 7 or 8, wherein: The photoelectric conversion film comprises a photoelectric conversion layer and an auxiliary layer. The auxiliary layer is formed of only the organic thin film, or is formed of a plurality of films including the organic thin film. 10 . An imaging element comprising the photoelectric conversion element according to claim 7 or 8 . 11 . The imaging element according to claim 10 , wherein two or more of the photoelectric conversion elements are stacked. 12 . An imaging element, comprising a plurality of the photoelectric conversion elements according to claim 7 or 8 arranged in an array. 13 . A photosensor comprising the imaging element according to claim 10 . 14 . A solid-state imaging device comprising the imaging element according to claim 10 .

Images