Materials for photoelectric conversion elements for imaging

Abstract

Provided are: a material with which the high sensitivity and high resolution of a photoelectric conversion element for imaging are achieved; and a photoelectric conversion element for imaging using the same. This material for a photoelectric conversion element for imaging has a structure represented by general formula (1). L's each independently represent a single bond, a C6-C30 aromatic hydrocarbon group, or the like. a represents the number of substitutions and represents an integer of 1-6.　Ar1's each independently represent a group represented by formula (2).　Ar2's each independently represent a C3-C30 aromatic heterocyclic group containing a nitrogen-containing six-membered ring structure or the like, where a group bonded to L is an aromatic heterocyclic group. A ring B represents a heterocycle represented by formula (2a) and condensed with an adjacent ring at an arbitrary position. * in formula (2) represents a bonding position to L in formula (1). X represents O, S, or N-Ar3.

Description

[Technical Field]

[0001] The present invention relates to a material for a photoelectric conversion element and a photoelectric conversion element using the same, and particularly to a material for a photoelectric conversion element that is useful for an imaging device.

[0002] In recent years, the development of organic electronics devices using thin films formed from organic semiconductors (also called organic charge transport materials) has progressed. Examples include electroluminescent devices, solar cells, transistor devices, and photoelectric conversion devices. In particular, the development of organic electroluminescent devices, which are electroluminescent devices made from organic materials, has progressed the most. As their application to smartphones, TVs, and other devices progresses, development aimed at further improving their functionality is also ongoing.

[0003] In the field of photoelectric conversion elements, progress has been made in the development and practical application of elements using PN junctions of inorganic semiconductors such as silicon. Studies are being conducted to improve the functionality of digital cameras and smartphone cameras, as well as for applications such as surveillance cameras and automotive sensors. However, challenges to meeting these diverse applications include increasing sensitivity and miniaturizing pixels (higher resolution). Photoelectric conversion elements using inorganic semiconductors typically employ a method of placing color filters corresponding to the three primary colors of light, RGB, on the light-receiving section of the photoelectric conversion element to obtain color images. This method, which requires the RGB color filters to be placed on a flat surface, poses challenges in terms of the efficiency of incident light utilization and resolution (Non-Patent Documents 1 and 2).

[0004] As one solution to these issues with photoelectric conversion elements, development is underway on photoelectric conversion elements that use organic semiconductors instead of inorganic semiconductors (Non-Patent Documents 1 and 2). This takes advantage of the property of organic semiconductors, which allows them to selectively absorb only light in a specific wavelength range with high sensitivity, and it has been proposed to solve the problem of high sensitivity and high resolution by stacking photoelectric conversion elements made of organic semiconductors corresponding to the three primary colors of light. In addition, an element has been proposed in which a photoelectric conversion element made of an organic semiconductor and a photoelectric conversion element made of an inorganic semiconductor are stacked (Non-Patent Document 3).

[0005] Here, an organic semiconductor photoelectric conversion element is an element constructed by having a photoelectric conversion layer made of a thin organic semiconductor film between two electrodes, with a hole-blocking layer and / or electron-blocking layer disposed between the photoelectric conversion layer and the two electrodes as needed. In a photoelectric conversion element, excitons are generated by absorbing light of a desired wavelength in the photoelectric conversion layer, followed by charge separation of the excitons, generating holes and electrons. The holes and electrons then migrate to the respective electrodes, converting light into an electrical signal. To accelerate this process, a bias voltage is typically applied between the two electrodes, but reducing the leakage current from the electrodes caused by the bias voltage application presents a challenge. For these reasons, controlling the movement of holes and electrons within the photoelectric conversion element is key to achieving the desired characteristics.

[0006] The organic semiconductors used in each layer of a photoelectric conversion element can be roughly divided into P-type organic semiconductors and N-type organic semiconductors, with P-type organic semiconductors being used as hole transport materials and N-type organic semiconductors being used as electron transport materials. In order to control the movement of holes and electrons within the above-mentioned photoelectric conversion element, various organic semiconductors with appropriate physical properties, such as hole mobility, electron mobility, energy value of the highest occupied molecular orbital (HOMO), and energy value of the lowest unoccupied molecular orbital (LUMO), have been developed. However, they do not yet have sufficient properties and have not yet been put to commercial use.

[0007] Patent Document 1 proposes a device that uses quinacridone as a P-type organic semiconductor in a photoelectric conversion layer, subphthalocyanine chloride as an N-type organic semiconductor, and an indolocarbazole derivative in a first buffer layer (considered to be synonymous with an electron blocking layer) disposed between the photoelectric conversion layer and an electrode. The application of the indolocarbazole derivative here is limited to the first buffer layer, and its applicability in the photoelectric conversion layer was unclear.

[0008] Patent Document 2 proposes a device in which a chrysenodithiophene derivative is used as a P-type organic semiconductor in a photoelectric conversion layer, and a fullerene or a subphthalocyanine derivative is used as an N-type organic semiconductor.

[0009] Patent Document 3 proposes a device in which a benzodifuran derivative is used in an electron blocking layer disposed between a photoelectric conversion layer and an electrode. Patent Document 4 proposes a device in which a photoelectric conversion layer contains a hydrocarbon-based condensed aromatic derivative having an electron-donating group as a P-type organic semiconductor and a hydrocarbon-based condensed aromatic derivative having an electron-withdrawing group as an N-type organic semiconductor. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 2018-85427 [Patent Document 2] Japanese Patent Application Publication No. 2019-54228 [Patent Document 3] Japanese Patent Application Publication No. 2019-57704 [Patent Document 4] WO2016-111140 publication [Non-patent literature]

[0011] [Non-Patent Document 1] NHK STRL R&D No.132, pp.4-11(2012.3) [Non-patent document 2] NHK STRL R&D No.174, pp.4-17(2019.3) [Non-patent document 3] 2019 IEEE International Electron Devices Meeting (IEDM), pp.16.6.1-16.6.4(2019) Summary of the Invention

[0012] Further improvements in sensitivity and resolution are required for imaging photoelectric conversion elements to improve the functionality of digital cameras and smartphone cameras, and to advance their application in surveillance cameras, automotive sensors, etc. In light of this current situation, the present invention aims to provide a material that achieves high sensitivity and high resolution in imaging photoelectric conversion elements, and an imaging photoelectric conversion element using the same.

[0013] As a result of extensive research, the present inventors have found that the process of generating holes and electrons due to charge separation of excitons in a photoelectric conversion layer and the process of moving holes and electrons within a photoelectric conversion element can be efficiently carried out by using a compound represented by the above formula (1), and have thus completed the present invention.

[0014] The present invention provides a material for a photoelectric conversion element for imaging, which is a compound having a structure represented by the following general formula (1). [ka] Each L independently represents a single bond, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 4 to 30 carbon atoms and containing a 5-membered heterocyclic structure, or a substituted or unsubstituted linking aromatic group in which 2 to 6 of one or more of the aromatic hydrocarbon groups or aromatic heterocyclic groups are linked together. a represents the number of substitutions and is an integer of 1 to 6. Ar 1 each independently represents a group represented by the following formula (2): Ar 2 each independently represents a substituted or unsubstituted aromatic heterocyclic group having 3 to 30 carbon atoms and containing a nitrogen-containing 6-membered ring structure, or a substituted or unsubstituted linking aromatic group containing at least one such aromatic heterocyclic group in which 2 to 7 of one or more of the aromatic heterocyclic groups or aromatic hydrocarbon groups having 6 to 30 carbon atoms are linked together, provided that the group bonded to L is the aromatic heterocyclic group. [ka] Ring B represents a heterocycle represented by formula (2a) which is fused to an adjacent ring at any position. * in formula (2) indicates the bonding position with L in formula (1). X represents O, S, or N-Ar 3 Represents. Ar 3 each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 4 to 30 carbon atoms and containing a 5-membered heterocyclic structure, or a substituted or unsubstituted linking aromatic group in which 2 to 6 of one or more of the aromatic hydrocarbon groups or aromatic heterocyclic groups are linked together, or L-Ar 2 Shows. R 1 , R 2 , and R 3 represents a substituent, each independently representing an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 4 to 30 carbon atoms and containing a 5-membered heterocyclic structure, or a substituted or unsubstituted linked aromatic group in which 2 to 6 of one or more of the aromatic hydrocarbon groups or heteroaromatic groups are linked together. R 1 , R 2 , and R 3 may be bonded to any adjacent substituent to form a ring or a condensed ring with the adjacent ring. c represents an integer of 0 to 4, d represents an integer of 0 to 2, and e represents an integer of 0 to 4. where Ar 2 preferably contains at least one substituted or unsubstituted azine skeleton, more preferably contains at least one substituted or unsubstituted pyridine, pyrimidine, or triazine skeleton, and even more preferably contains at least one substituted or unsubstituted triazine skeleton.

[0015] The material for photoelectric conversion elements preferably has an energy level of the highest occupied molecular orbital (HOMO) of −4.5 eV or less, or an energy level of the lowest unoccupied molecular orbital (LUMO) of −2.5 eV or more, as obtained by a structural optimization calculation using density functional theory calculation B3LYP / 6-31G(d).

[0016] The photoelectric conversion element material is 1×10-6 cm 2 It is preferable that the material has a hole mobility of 1 / Vs or more, or is amorphous.

[0017] The material for the photoelectric conversion element is L, Ar 2 The substituents of Ar 3 , Ar 3 The substituents, R 1 , R 2 , R 3 In the aromatic heterocyclic group having 4 to 30 carbon atoms and containing a five-membered heterocyclic structure used in the above, the five-membered heterocyclic structure may be a pyrrole ring, a furan ring or a thiophene ring.

[0018] The material for a photoelectric conversion element can be used as a hole transport material.

[0019] The present invention provides an imaging photoelectric conversion element having a photoelectric conversion layer and an electron blocking layer between two electrodes, characterized in that at least one of the photoelectric conversion layer and the electron blocking layer contains the above-described material for photoelectric conversion elements.

[0020] The photoelectric conversion element of the present invention may contain an electron transporting material in the photoelectric conversion layer, and may contain the above-mentioned material for photoelectric conversion elements in the electron blocking layer.

[0021] The use of the material for a photoelectric conversion element for imaging of the present invention allows for appropriate movement of holes and electrons within the photoelectric conversion element, thereby reducing the leakage current that occurs when a bias voltage is applied during the conversion of light into electrical energy, thereby enabling the production of a photoelectric conversion element that achieves a low dark current value and a high contrast ratio. Therefore, it is useful as a material for a photoelectric conversion element of a photoelectric conversion film stacked type imaging device. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a cross-sectional view showing a structural example of a photoelectric conversion element used in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] The imaging photoelectric conversion element of the present invention is a photoelectric conversion element that converts light into electrical energy and has at least one organic layer between two electrodes. The organic layer contains a material for imaging photoelectric conversion elements represented by the above general formula (1). If necessary, the organic layer containing the material for imaging photoelectric conversion elements represented by the above general formula (1) can be multiple layers.

[0024] The compound represented by the above general formula (1) will be explained below.

[0025] Each L as a linking group independently represents a single bond, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 4 to 30 carbon atoms and containing a 5-membered heterocyclic structure, or a substituted or unsubstituted linking aromatic group in which 2 to 6 of one or more of the aromatic hydrocarbon groups or aromatic heterocyclic groups are linked together. Preferably, a single bond, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, an aromatic heterocyclic group having 4 to 20 carbon atoms and containing a 5-membered heterocyclic structure having at least one nitrogen, sulfur, or oxygen atom, or a substituted or unsubstituted linking aromatic group in which 2 to 4 aromatic groups selected from the aromatic hydrocarbon groups and aromatic heterocyclic groups are linked together can be used. More preferably, a single bond, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, an aromatic heterocyclic group having 4 to 12 carbon atoms and containing a pyrrole ring, a furan ring, or a thiophene ring as a five-membered heterocyclic structure, or a substituted or unsubstituted linking aromatic group formed by linking 2 to 4 aromatic groups selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups can be used.

[0026] The hydrocarbon aromatic group having 6 to 30 carbon atoms for L can be a group obtained by removing two hydrogen atoms from a known aromatic hydrocarbon, and examples thereof include monocyclic aromatic hydrocarbons such as benzene, bicyclic aromatic hydrocarbons such as naphthalene, tricyclic aromatic hydrocarbons such as indacene, biphenylene, phenalene, anthracene, phenanthrene, and fluorene, tetracyclic aromatic hydrocarbons such as fluoranthene, acephenanthrylene, aceanthrylene, triphenylene, pyrene, chrysene, tetraphene, tetracene, and pleiadene, and pentacyclic aromatic hydrocarbons such as picene, perylene, pentaphene, pentacene, tetraphenylene, and naphthaanthracene. Preferred are benzene, naphthalene, anthracene, and triphenylene.

[0027] In the aromatic heterocyclic group having 4 to 30 carbon atoms and containing a 5-membered heterocyclic structure of L, the 5-membered heterocyclic structure is preferably one in which two hydrogen atoms have been removed from a known 5-membered heterocyclic structure. A pyrrole ring, a furan ring, or a thiophene ring can be preferably used, and a group in which two hydrogen atoms have been removed from an aromatic heterocyclic group having 4 to 30 carbon atoms and containing a 5-membered heterocyclic structure constituted by these rings is preferred. Examples thereof include nitrogen-containing aromatic groups having a pyrrole ring such as pyrrole, pyrrolopyrrole, indole, pyrroloindole, benzoindole, naphthopyrrole, isoindole, pyrroloisoindole, benzoisoindole, naphthisopyrrole, carbazole, benzocarbazole, indoloindole, carbazolocarbazole, and carboline, thiophene, benzoindole, naphthisopyrrole, carbazole, benzocarbazole, indoloindole, carbazolocarbazole, and carboline. Examples include sulfur-containing aromatic groups having a thiophene ring such as thiophene, naphthothiophene, dibenzothiophene, benzothienonaphthalene, benzothienobenzothiophene, benzothienodibenzothiophene, dinaphthothiophene, dinaphthothienothiophene, and naphthobenzothiophene; and oxygen-containing aromatic groups having a furan ring such as furan, benzofuran, naphthofuran, dibenzofuran, benzofuronaphthalene, benzofurobenzofuran, benzofurodibenzofuran, dinaphthofuran, dinaphthofuranofuran, and naphthobenzofuran.

[0028] Here, in the aromatic heterocyclic group of L, containing a five-membered heterocyclic structure may mean a structure in which a five-membered heterocyclic ring such as a pyrrole ring, a furan ring, or a thiophene ring exists alone, or a structure in which a five-membered heterocyclic ring such as a benzene ring or a carbazole ring exists condensed with an aromatic ring.

[0029] The aromatic ring may be a condensed group of two or more groups selected from the nitrogen-containing aromatic groups, sulfur-containing aromatic groups, oxygen-containing aromatic groups, etc., such as a group in which an aromatic ring having a pyrrole ring is condensed with an aromatic ring having a furan ring, such as benzofurocarbazole and benzofurobenzocarbazole, a group in which an aromatic ring having a pyrrole ring is condensed with an aromatic ring having a thiophene ring, such as benzothienocarbazole and benzothienobenzocarbazole, or a group in which an aromatic ring having a furan ring is condensed with an aromatic ring having a thiophene ring, such as benzofurodibenzothiophene and benzofurobenzocarbazole.

[0030] More preferably, the aromatic heterocyclic group containing a 5-membered heterocyclic structure of L is a nitrogen-containing aromatic group having a pyrrole ring, such as carbazole, benzocarbazole, indoloindole, or carbazolocarbazole; a sulfur-containing aromatic group having a thiophene ring, such as thiophene, dibenzothiophene, benzothienonaphthalene, benzothienobenzothiophene, benzothienodibenzothiophene, dinaphthothiophene, dinaphthothienothiophene, or naphthobenzothiophene; and an oxygen-containing aromatic group having a furan ring, such as dibenzofuran, benzofuronaphthalene, benzofurobenzofuran, benzofurodibenzofuran, dinaphthofuranofuran, or naphthobenzofuran.

[0031] L may have a substituent, and examples of the substituent include an alkyl group having 1 to 20 carbon atoms. The alkyl group having 1 to 20 carbon atoms may be any of linear, branched, and cyclic alkyl groups, and is preferably a linear, branched, or cyclic alkyl group having 1 to 10 carbon atoms. Specific examples include linear saturated hydrocarbon groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-octyl, n-dodecyl, n-tetradecyl, and n-octadecyl groups; branched saturated hydrocarbon groups such as isopropyl, isobutyl, neopentyl, 2-ethylhexyl, and 2-hexyloctyl groups; and saturated alicyclic hydrocarbon groups such as cyclopentyl, cyclohexyl, cyclooctyl, 4-butylcyclohexyl, and 4-dodecylcyclohexyl groups.

[0032] In the general formula (1), Ar 1 each independently represents a group represented by formula (2). Ring B in formula (2) represents a heterocycle represented by formula (2a) which is fused with an adjacent ring at any position. [ka]

[0033] In formula (2a), X is O, S, or N-Ar. 3 and preferably represents N-Ar 3 is.

[0034] Ar 3 each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 4 to 30 carbon atoms and containing a 5-membered heterocyclic structure, a linked aromatic group in which 2 to 6 of one or more of the aromatic hydrocarbon groups or the aromatic heterocyclic groups are linked together, or L-Ar 2 Shows. Preferably, it is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, an aromatic heterocyclic group having 4 to 20 carbon atoms and containing a 5-membered heterocyclic structure, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 4 aromatic groups selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups. More preferred are substituted or unsubstituted aromatic hydrocarbon groups having 6 to 18 carbon atoms, aromatic heterocyclic groups having 4 to 12 carbon atoms and containing a pyrrole ring, a furan ring, or a thiophene ring as a five-membered heterocyclic structure, and substituted or unsubstituted linked aromatic groups formed by linking 2 to 4 aromatic groups selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups.

[0035] Ar 3 The aromatic hydrocarbon group having 6 to 30 carbon atoms is preferably one in which one hydrogen atom has been removed from a known aromatic hydrocarbon, and examples thereof include monocyclic aromatic hydrocarbons such as benzene, bicyclic aromatic hydrocarbons such as naphthalene, tricyclic aromatic hydrocarbons such as indacene, biphenylene, phenalene, anthracene, phenanthrene, and fluorene, tetracyclic aromatic hydrocarbons such as fluoranthene, acephenanthrylene, aceanthrylene, triphenylene, pyrene, chrysene, tetraphene, tetracene, and pleiadene, and pentacyclic aromatic hydrocarbons such as picene, perylene, pentaphene, pentacene, tetraphenylene, and naphthaanthracene. Preferred are benzene, naphthalene, anthracene, and triphenylene.

[0036] Ar 3In the aromatic heterocyclic group having 4 to 30 carbon atoms and containing the above five-membered heterocyclic structure, the five-membered heterocyclic structure is preferably one in which two hydrogen atoms have been removed from a known five-membered heterocyclic structure.Preferably, the five-membered heterocyclic structure is a pyrrole ring, a furan ring, or a thiophene ring, and preferably one in which one hydrogen atom has been removed from any of these aromatic heterocyclic groups having 4 to 30 carbon atoms and containing a five-membered heterocyclic structure. Examples of such aromatic groups include nitrogen-containing aromatic groups having a pyrrole ring such as pyrrole, pyrrolopyrrole, indole, pyrroloindole, benzoindole, naphthopyrrole, isoindole, pyrroloisoindole, benzisoindole, naphthoisopyrrole, carbazole, benzocarbazole, indoloindole, carbazolocarbazole, and carboline; sulfur-containing aromatic groups having a thiophene ring such as thiophene, benzothiophene, naphthothiophene, dibenzothiophene, benzothienonaphthalene, benzothienobenzothiophene, benzothienodibenzothiophene, dinaphthothiophene, dinaphthothienothiophene, and naphthobenzothiophene; and oxygen-containing aromatic groups having a furan ring such as furan, benzofuran, naphthofuran, dibenzofuran, benzofuronaphthalene, benzofurobenzofuran, benzofurodibenzofuran, dinaphthofuranofuran, and naphthobenzofuran.

[0037] Ar 3 More preferably, the aromatic heterocyclic group having 4 to 30 carbon atoms and a 5-membered heterocyclic ring structure described above is a nitrogen-containing aromatic group having a pyrrole ring, such as carbazole, benzocarbazole, indoloindole, or carbazolocarbazole; a sulfur-containing aromatic group having a thiophene ring, such as thiophene, dibenzothiophene, benzothienonaphthalene, benzothienobenzothiophene, benzothienodibenzothiophene, dinaphthothiophene, dinaphthothienothiophene, or naphthobenzothiophene; and an oxygen-containing aromatic group having a furan ring, such as dibenzofuran, benzofuronaphthalene, benzofurobenzofuran, benzofurodibenzofuran, dinaphthofuranofuran, or naphthobenzofuran.

[0038] Ar 3may have a substituent, and an example of the substituent is an alkyl group having 1 to 20 carbon atoms. The alkyl group having 1 to 20 carbon atoms may be a linear, branched, or cyclic alkyl group, and is preferably a linear, branched, or cyclic alkyl group having 1 to 10 carbon atoms. Specific examples thereof include linear saturated hydrocarbon groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-octyl, n-dodecyl, n-tetradecyl, and n-octadecyl groups; branched saturated hydrocarbon groups such as isopropyl, isobutyl, neopentyl, 2-ethylhexyl, and 2-hexyloctyl groups; and saturated alicyclic hydrocarbon groups such as cyclopentyl, cyclohexyl, cyclooctyl, 4-butylcyclohexyl, and 4-dodecylcyclohexyl groups.

[0039] In formula (2a), X is N-Ar 3 In this case, the five-ring fused ring represented by general formula (2) represents an indolocarbazole skeleton, and there are six isomers represented by the following formulae (U), (V), (W), (X), (Y), and (Z). Formula (U), (V), (W), or (Y) is preferred. When X is O or S, there are isomers similar to those of the indolocarbazole skeleton. [ka]

[0040] In equation (2), R 1 , R 2 , and R 3 represents a substituent, and represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 4 to 30 carbon atoms and containing a 5-membered heterocyclic structure, or a substituted or unsubstituted linked aromatic group in which 2 to 6 of one or more of the aromatic hydrocarbon groups or aromatic heterocyclic groups are linked together; R 1 , R 2 , and R 3 may be bonded to any adjacent substituent to form a ring or a condensed ring with the adjacent ring. Preferred are alkyl groups having 1 to 10 carbon atoms, alkenyl groups having 1 to 10 carbon atoms, substituted or unsubstituted aromatic hydrocarbon groups having 6 to 20 carbon atoms, substituted or unsubstituted aromatic heterocyclic groups having 4 to 20 carbon atoms and containing a five-membered heterocyclic structure, and substituted or unsubstituted linked aromatic groups formed by linking 2 to 6 of one or more of the aromatic hydrocarbon groups or aromatic heterocyclic groups. More preferred are substituted or unsubstituted aromatic hydrocarbon groups having 6 to 18 carbon atoms, aromatic heterocyclic groups having 4 to 12 carbon atoms and containing a pyrrole ring, furan ring, or thiophene ring as a five-membered heterocyclic structure, and substituted or unsubstituted linked aromatic groups formed by linking 2 to 4 of one or more of the aromatic hydrocarbon groups or aromatic heterocyclic groups.

[0041] R 1 , R 2 , and R 3 The alkyl group having 1 to 20 carbon atoms may be any of a linear, branched, or cyclic alkyl group, and is preferably a linear, branched, or cyclic alkyl group having 1 to 10 carbon atoms. Specific examples thereof include linear saturated hydrocarbon groups such as a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, an n-dodecyl group, an n-tetradecyl group, and an n-octadecyl group; branched saturated hydrocarbon groups such as an isopropyl group, an isobutyl group, a neopentyl group, a 2-ethylhexyl group, and a 2-hexyloctyl group; and saturated alicyclic hydrocarbon groups such as a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, a 4-butylcyclohexyl group, and a 4-dodecylcyclohexyl group.

[0042] R 1 , R 2 , and R 3 Examples of the alkenyl group having 1 to 20 carbon atoms include groups in which a single bond is converted into a double bond by eliminating hydrogen from the alkyl groups exemplified above as the alkyl groups having 1 to 20 carbon atoms.

[0043] R 1 , R 2 , and R 3Examples of the aromatic hydrocarbon group having 6 to 30 carbon atoms or the aromatic heterocyclic group having 4 to 30 carbon atoms and containing a 5-membered heterocyclic structure include the above-mentioned Ar 3 Examples of the aromatic hydrocarbon group include an aromatic hydrocarbon group having 6 to 30 carbon atoms and an aromatic heterocyclic group having 4 to 30 carbon atoms and containing a 5-membered heterocyclic ring structure, as shown in the following formula: Preferred examples also include the same groups.

[0044] When the above-mentioned aromatic hydrocarbon group, aromatic heterocyclic group containing a 5-membered heterocyclic structure, or linked aromatic group formed by linking 2 to 6 of at least one of the aromatic hydrocarbon groups or aromatic heterocyclic groups has a substituent, the substituent can be an alkyl group having 1 to 20 carbon atoms. The alkyl group having 1 to 20 carbon atoms may be any of a linear, branched, or cyclic alkyl group, and is preferably a linear, branched, or cyclic alkyl group having 1 to 10 carbon atoms. Specific examples thereof include linear saturated hydrocarbon groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-octyl, n-dodecyl, n-tetradecyl, and n-octadecyl groups; branched saturated hydrocarbon groups such as isopropyl, isobutyl, neopentyl, 2-ethylhexyl, and 2-hexyloctyl groups; and saturated alicyclic hydrocarbon groups such as cyclopentyl, cyclohexyl, cyclooctyl, 4-butylcyclohexyl, and 4-dodecylcyclohexyl groups.

[0045] In formula (2), c is R 1 is the number of substitutions and is an integer between 0 and 4, and d is R 2 The number of substitutions is an integer between 0 and 2, and e is R 3 represents an integer of 0 to 4, and preferably, c, d, and e are all integers of 0 to 2.

[0046] In the general formula (1), Ar 2 each independently represents a substituted or unsubstituted aromatic heterocyclic group having 3 to 30 carbon atoms and containing a nitrogen-containing 6-membered ring structure, or a substituted or unsubstituted linking aromatic group containing at least one such aromatic heterocyclic group in which 2 to 7 of one or more of the aromatic heterocyclic groups or hydrocarbon aromatic groups having 6 to 30 carbon atoms are linked together, provided that the group bonded to L is the aromatic heterocyclic group. Preferably, it is a substituted or unsubstituted aromatic heterocyclic group having 3 to 20 carbon atoms and containing a nitrogen-containing 6-membered ring structure, or a substituted or unsubstituted linked aromatic group in which an aromatic heterocyclic group having 3 to 20 carbon atoms and at least one nitrogen-containing 6-membered ring structure is linked to 2 to 4 aromatic hydrocarbon groups having 6 to 20 carbon atoms, provided that the group bonded to L is the aromatic heterocyclic group.

[0047] Ar 2 Examples of the aromatic heterocyclic group having 3 to 30 carbon atoms and containing a nitrogen-containing 6-membered ring structure include groups in which one or more carbon atoms of a hydrocarbon aromatic group having 6 to 30 carbon atoms and a 6-membered ring hydrocarbon aromatic as a partial structure are substituted with nitrogen. As the aromatic hydrocarbon group having 6 to 30 carbon atoms, known aromatic hydrocarbons can be used, and examples thereof include groups in which one or more carbon atoms of an aromatic hydrocarbon group are substituted with nitrogen, such as a monocyclic aromatic hydrocarbon group such as benzene, a bicyclic aromatic hydrocarbon group such as naphthalene, a tricyclic aromatic hydrocarbon group such as indacene, biphenylene, phenalene, anthracene, and phenanthrene, a tetracyclic aromatic hydrocarbon group such as fluoranthene, acephenanthrylene, aceanthrylene, triphenylene, pyrene, chrysene, tetraphene, tetracene, and pleiadene, and a pentacyclic aromatic hydrocarbon group such as picene, perylene, pentaphene, pentacene, tetraphenylene, and naphthaanthracene. Preferably, a group in which one or more carbon atoms are substituted with nitrogen can be used, and more preferably, a group having 1 to 4 nitrogen atoms. Specific examples include monocyclic nitrogen-containing aromatic ring groups such as pyridine, pyrazine, pyrimidine, pyridazine, and triazine, bicyclic nitrogen-containing aromatic ring groups such as quinoline, isoquinoline, naphthyridine, phthalazine, quinoxaline, quinazoline, cinnoline, and pteridine, tricyclic nitrogen-containing aromatic ring groups such as phenanthridine, acridine, phenanthroline, phenazine, anthridine, and phenazone, and tetracyclic nitrogen-containing aromatic ring groups such as thebenidine, and particularly preferred examples include monocyclic nitrogen-containing aromatic ring groups such as pyridine, pyrazine, pyrimidine, pyridazine, and triazine.

[0048] where Ar 2In the aromatic heterocyclic group, containing a nitrogen-containing 6-membered ring structure may mean a structure in which a nitrogen-containing 6-membered ring structure such as a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, or a triazine ring exists alone, or a structure in which the nitrogen-containing 6-membered ring structure exists in a condensed state with an aromatic ring such as a benzene ring.

[0049] Also Ar 2 It is also preferable that Ar contains at least one substituted or unsubstituted azine skeleton. In this case, the unsubstituted azine ring skeleton can be represented by an aromatic heterocycle containing at least one N as shown in the following formulas (3) to (7), and examples thereof include quinoline, quinoxaline, pyridine, pyrimidine, and triazine. Preferably, Ar contains at least one pyridine, pyrimidine, or triazine skeleton, and more preferably, it contains at least one triazine skeleton. The phrase "containing at least one substituted or unsubstituted azine skeleton" means that Ar 2 represents a substituted or unsubstituted aromatic heterocyclic group having 3 to 30 carbon atoms and containing a nitrogen-containing 6-membered ring structure, or a substituted or unsubstituted linked aromatic group containing at least one aromatic heterocyclic group in which 2 to 7 of one or more of the aromatic heterocyclic groups or aromatic hydrocarbon groups having 6 to 30 carbon atoms are linked together, refers to a case in which at least one substituted or unsubstituted tricyclic fused ring skeleton is contained. [ka] In the above formulas (3) to (7), * represents the bonding position with L in formula (1), Y represents N, CH, or C—, and at least one Y represents N. Here, C— indicates a case where the group is linked to another aromatic heterocyclic group or an aromatic hydrocarbon group. The above formulas (3) to (7) may have a substituent, and in that case, the substituent is Ar 2 The substituents are the same as those that may be possessed by the group.

[0050] Ar 2 However, examples of the aromatic heterocyclic group having 3 to 30 carbon atoms containing at least one nitrogen-containing 6-membered ring structure and the linked aromatic group having 6 to 30 carbon atoms in which 2 to 7 hydrocarbon aromatic groups having 6 to 30 carbon atoms are the above-mentioned Ar 3Examples of aromatic hydrocarbon groups include those having 6 to 30 carbon atoms shown in the following formula.

[0051] Ar 2 Examples of the substituent that may be possessed by include alkyl groups having 1 to 20 carbon atoms, which are the same as the alkyl groups having 1 to 20 carbon atoms described above.

[0052] In formula (1), a represents the number of substitutions and is an integer of 1 to 6, preferably an integer of 1 to 4, more preferably an integer of 1 to 3, and even more preferably an integer of 1 to 2.

[0053] Preferred specific examples of the material for an imaging photoelectric conversion element of the present invention represented by general formula (1) are shown below, but the material is not limited to these.

[0054] [ka] [ka] [ka]

[0055] [ka] [ka] [ka]

[0056] [ka] [ka] [ka]

[0057] [ka] [ka] [ka]

[0058] [ka] [ka] [ka] [ka]

[0059] The material for a photoelectric conversion element for imaging represented by general formula (1) of the present invention can be synthesized by various organic synthesis reaction methods established in the field of organic synthetic chemistry, including coupling reactions such as Suzuki coupling, Stille coupling, Grignard coupling, Ullmann coupling, Buchwald-Hartwig reaction, and Heck reaction, using commercially available reagents as raw materials, and then purified by known methods such as recrystallization, column chromatography, and sublimation purification, but the method is not limited to this.

[0060] The material for an imaging photoelectric conversion element of the present invention preferably has an energy level of the highest occupied molecular orbital (HOMO) obtained by a structural optimization calculation using density functional theory calculation B3LYP / 6-31G(D) of −4.5 eV or less, more preferably in the range of −4.5 eV to −6.0 eV.

[0061] The material for an imaging photoelectric conversion element of the present invention preferably has an energy level of the lowest unoccupied molecular orbital (LUMO) obtained by a structural optimization calculation using density functional theory calculation B3LYP / 6-31G(D) of -2.5 eV or higher, more preferably in the range of -2.5 eV to -0.5 eV.

[0062] In the material for an imaging photoelectric conversion element of the present invention, the difference (absolute value) between the HOMO energy level and the LUMO energy level is preferably in the range of 2.0 to 5.0 eV, more preferably in the range of 2.5 to 4.0 eV.

[0063] The material for an imaging photoelectric conversion element of the present invention is preferably 1×10 -6 cm 2 / Vs~1cm 2 / Vs, and more preferably 1×10 -5 cm 2 / Vs~1×10 -1 cm 2 The hole mobility can be evaluated by known methods such as a method using a FET transistor element, a time-of-flight method, or an SCLC method.

[0064] The material for an imaging photoelectric conversion element of the present invention is preferably amorphous. The amorphous nature can be confirmed by various methods, for example, by the absence of a peak detected by XRD or the absence of an endothermic peak detected by DSC.

[0065] Next, an imaging photoelectric conversion element using the imaging photoelectric conversion element material of the present invention will be described, but the structure of the imaging photoelectric conversion element of the present invention is not limited thereto.

[0066] 1 is a cross-sectional view schematically illustrating the structure of an imaging photoelectric conversion element using the imaging photoelectric conversion element material of the present invention, where 1 represents a substrate, 2 an electrode, 3 an electron blocking layer, 4 a photoelectric conversion layer, 5 a hole blocking layer, and 6 an electrode. The structure is not limited to that shown in FIG. 1, and layers can be added or omitted as necessary.

[0067] Each member and each layer of the photoelectric conversion element of the present invention will be described below. -substrate- A photoelectric conversion element using the material for a photoelectric conversion element of the present invention is preferably supported on a substrate. The substrate is not particularly limited, and may be made of, for example, glass, transparent plastic, quartz, or the like.

[0068] -electrode- The electrodes used in an imaging photoelectric conversion element using the imaging photoelectric conversion element material of the present invention have the function of collecting holes and electrons generated in the photoelectric conversion layer. They also need the function of allowing light to enter the photoelectric conversion layer. Therefore, it is desirable that at least one of the two electrodes is transparent or translucent. The material used as the electrode is not particularly limited as long as it is conductive. Examples include conductive transparent materials such as ITO, IZO, SnO2, ATO (antimony-doped tin oxide), ZnO, AZO (Al-doped zinc oxide), GZO (gallium-doped zinc oxide), TiO2, and FTO; metals such as gold, silver, platinum, chromium, aluminum, iron, cobalt, nickel, and tungsten; inorganic conductive materials such as copper iodide and copper sulfide; and conductive polymers such as polythiophene, polypyrrole, and polyaniline. These materials may be used in combination as needed. Two or more layers may also be stacked.

[0069] -Photoelectric conversion layer- The photoelectric conversion layer is a layer in which holes and electrons are generated by charge separation of excitons generated by incident light. It may be formed of a single photoelectric conversion material, or may be formed in combination with a P-type organic semiconductor material, which is a hole-transporting material, or an N-type organic semiconductor material, which is an electron-transporting material. Two or more P-type organic semiconductors may be used, or two or more N-type organic semiconductors may be used. It is desirable that one or more of these P-type organic semiconductors and / or N-type semiconductors be a dye material that has the function of absorbing light of a desired wavelength in the visible region. The compound represented by the above formula (1) of the present invention can be used as the P-type organic semiconductor material, which is a hole-transporting material.

[0070] The P-type organic semiconductor material may be any material having hole transport properties, and is preferably a material represented by the above formula (1), but other P-type organic semiconductor materials may also be used. Two or more materials represented by the above formula (1) may also be mixed and used. Furthermore, the above formula (1) may also be mixed with other P-type organic semiconductor materials. Other p-type organic semiconductor materials may be any material having hole transport properties, and examples thereof include compounds having a condensed polycyclic aromatic group such as naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene, fluoranthene, fluorene, and indene; compounds having a π-excess aromatic group such as cyclopentadiene derivatives, furan derivatives, thiophene derivatives, pyrrole derivatives, benzofuran derivatives, benzothiophene derivatives, dinaphthothienothiophene derivatives, indole derivatives, pyrazoline derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, carbazole derivatives, and indolocarbazole; aromatic amine derivatives, styrylamine derivatives, benzidine derivatives, porphyrin derivatives, phthalocyanine derivatives, and quinacridone derivatives.

[0071] Examples of polymer-type P-type organic semiconductor materials include polyphenylene vinylene derivatives, polyparaphenylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, and polythiophene derivatives. Two or more selected from the compound represented by formula (1) of the present invention, P-type organic semiconductor materials, and polymer-type P-type organic semiconductor materials may be mixed and used.

[0072] The N-type organic semiconductor material may be any material having electron transport properties, such as naphthalene tetracarboxylic acid diimide, perylene tetracarboxylic acid diimide, fullerenes, and azole derivatives such as imidazole, thiazole, thiadiazole, oxazole, oxadiazole, and triazole. Two or more N-type organic semiconductor materials may be mixed and used.

[0073] -Electron Blocking Layer- The electron blocking layer is provided to suppress dark current generated by electron injection from one electrode into the photoelectric conversion layer when a bias voltage is applied between the two electrodes. It also functions as a hole transporter, transporting holes generated by charge separation in the photoelectric conversion layer to the electrode. A single layer or multiple layers can be arranged as needed. The electron blocking layer can be made of a P-type organic semiconductor material, which is a hole transport material. Any material with hole transport properties can be used as the P-type organic semiconductor material. The material represented by the above formula (1) is preferably used, but other P-type organic semiconductor materials may also be used. Furthermore, the material represented by the above formula (1) may be mixed with other P-type organic semiconductor materials. Other p-type organic semiconductor materials may be any material having hole transport properties, and examples thereof include compounds having a condensed polycyclic aromatic group such as naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene, fluoranthene, fluorene, and indene; compounds having a π-excess aromatic group such as cyclopentadiene derivatives, furan derivatives, thiophene derivatives, pyrrole derivatives, benzofuran derivatives, benzothiophene derivatives, dinaphthothienothiophene derivatives, indole derivatives, pyrazoline derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, and carbazole derivatives; aromatic amine derivatives, styrylamine derivatives, benzidine derivatives, porphyrin derivatives, phthalocyanine derivatives, and quinacridone derivatives.

[0074] -Hole blocking layer- The hole-blocking layer is provided to suppress dark current generated by holes being injected from one electrode into the photoelectric conversion layer when a bias voltage is applied between the two electrodes. It also functions as an electron transport layer, transporting electrons generated by charge separation in the photoelectric conversion layer to the electrode. A single layer or multiple layers can be arranged as needed. An N-type organic semiconductor with electron transport properties can be used for the hole-blocking layer. The N-type organic semiconductor material may be any material having electron transport properties, and examples thereof include polycyclic aromatic polycarboxylic acid anhydrides and imidized products thereof, such as naphthalene tetracarboxylic acid diimide and perylene tetracarboxylic acid diimide, fullerenes such as C60 and C70, azole derivatives such as imidazole, thiazole, thiadiazole, oxazole, oxadiazole, and triazole, tris(8-quinolinolato)aluminum(III) derivatives, phosphine oxide derivatives, nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, bipyridine derivatives, quinoline derivatives, and indolocarbazole derivatives. Two or more N-type organic semiconductor materials may also be used in combination.

[0075] When producing the imaging photoelectric conversion element of the present invention, the method for forming each layer is not particularly limited, and they may be produced by either a dry process or a wet process. [Example]

[0076] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0077] Calculation example Calculation of HOMO and LUMO values The HOMO and LUMO of the above compounds W1, W2, W3, W4, W5, Wd1, Wd2, Y1, U1, U2, U3, Z1, X1, G1, and Hd1 were calculated. The calculations were performed using density functional theory (DFT), Gaussian, and structural optimization calculations using density functional calculation B3LYP / 6-31G(d). The results are shown in Table 1. It can be said that all of the materials for photoelectric conversion elements for imaging of the present invention have preferable HOMO and LUMO values.

[0078] [Table 1]

[0079] The synthesis of compounds Wd2, W4, and U3 is shown below as representative examples. Other compounds were also synthesized in a similar manner.

[0080] Synthesis example 1 (synthesis of Wd2) [ka] A 2000 ml three-neck flask was charged with R1 (101.4 mmol), iodobenzene (601.4 mmol), copper iodide (287.2 mmol), and potassium carbonate (482.6 mmol), and 800 ml of quinoline was added. The mixture was then stirred at 190°C for 72 hours. After cooling to room temperature, 500 ml of water and 500 ml of dichloromethane were added, and the resulting yellow precipitate was collected by filtration. The filtrate was transferred to a 2000 ml separatory funnel and separated into organic and aqueous layers. The organic layer was washed three times with 500 ml of water, dehydrated over magnesium sulfate, and then concentrated under reduced pressure. The resulting residue was purified by column chromatography to obtain M1 (a white solid). The yield was 80%. Next, 55% sodium hydride (49.5 mmol) was placed in a degassed, nitrogen-purged 500 mL three-neck flask, and 70 mL of anhydrous N,N-dimethylformamide (DMF) was added. The mixture was stirred under a nitrogen stream. A separately prepared solution of Intermediate 1 (38.3 mmol) in 70 mL of anhydrous DMF was added dropwise to the DMF solution over 15 minutes. After the addition, stirring was continued for 1 hour. Then, a solution of 3.54 g (19.2 mmol) of cyanuric chloride in 70 mL of anhydrous DMF was added dropwise to the same flask over 15 minutes. After the addition, stirring was continued for 2 hours. 350 g of water was added, and the precipitate was collected by filtration to obtain M2. The yield was 86%.

[0081] Next, a 1000 ml three-neck flask was charged with the above-obtained M2 (12.9 mmol), 4-biphenylboronic acid (16.4 mmol), tetrakis(triphenylphosphine)palladium (1.3 mmol), 50 ml of ethanol, 100 ml of toluene, and sodium carbonate (47.0 mmol) dissolved in 50 ml of water. The mixture was then heated to 85 °C and stirred for 5 hours. After cooling to room temperature, 100 ml of water and 100 ml of toluene were added. After stirring, the insoluble material was filtered off. The filtrate was transferred to a 1000 ml separatory funnel and separated into an organic layer and an aqueous layer. The organic layer was washed three times with 100 ml of water, and then concentrated under reduced pressure. The residue was subjected to column chromatography to obtain compound Wd2 (yellow solid). The yield was 93%. The obtained yellow solid was evaluated by XRD; however, no peaks were detected, indicating that this compound was amorphous.

[0082] Synthesis Example 2 (Synthesis of W4) [ka] M1 (71.9 mmol) obtained from R1 by the method of Synthesis Example 1 and sodium hydride (78.8 mmol) were added to DMF (100 ml) and stirred at room temperature under a nitrogen atmosphere. After 30 minutes, phenylchlorotriazine (79.2 mmol) was added and the mixture was stirred at room temperature. After 1 hour, 100 ml of distilled water was added. The precipitate was collected by filtration, recrystallized, and subjected to column chromatography to obtain compound W4 (yellow crystals). The yield was 90%. The obtained yellow solid was evaluated by XRD, but no peaks were detected, indicating that this compound was amorphous.

[0083] Synthesis Example 4 (Synthesis of U3) [ka] The same procedure was carried out as in Synthesis Example 1, except that R2 was used instead of R1, to obtain M3. The yield was 85%. Next, the same procedure was carried out as in Synthesis Example 2, except that M3 was used instead of M1, to obtain compound U3 (yellow crystals). The yield was 91%. The obtained yellow solid was evaluated by XRD, but no peak was detected, indicating that this compound was amorphous.

[0084] Physical property evaluation example On a glass substrate with a transparent electrode made of ITO with a thickness of 110 nm, a film of compound W1 was formed as an organic layer by vacuum deposition under conditions of a film thickness of approximately 3 μm. Next, using a device with an aluminum (Al) electrode formed to a thickness of 70 nm, charge mobility was measured by the time-of-flight method. The hole mobility was 7 × 10 -5 cm 2 / Vs.

[0085] The hole mobility was evaluated in the same manner except that compound W1 was replaced with W4, Wd1, Y1, and U1. The results are shown in Table 2.

[0086] [Table 2]

[0087] Example 1 A glass substrate with an ITO electrode of 70 nm thickness was formed on it, and a vacuum of 4.0 × 10 -5 Compound W1 was deposited as an electron blocking layer to a thickness of 100 nm using Pa. Next, a quinacridone thin film was deposited as a photoelectric conversion layer to a thickness of 100 nm. Finally, aluminum was deposited as an electrode to a thickness of 70 nm to complete a photoelectric conversion element. When a voltage of 2 V is applied to ITO and aluminum electrodes, the current in the dark is 5.3 × 10 -12 A / cm 2 When a voltage of 2 V was applied and the ITO electrode was irradiated from a height of 10 cm with an LED adjusted to 1.6 μW and a wavelength of 500 nm, the current was 4.3 × 10 -6 A / cm 2 The light-dark ratio when a voltage of 2 V was applied was 8.1 × 10 5 It was.

[0088] Comparative Example 1 A glass substrate with an ITO electrode of 70 nm thickness was formed on it, and a vacuum of 4.0 × 10 -5 A 100 nm quinacridone film was formed as a photoelectric conversion layer at 100 Pa. Finally, a 70 nm aluminum film was formed as an electrode to create a photoelectric conversion element. When a voltage of 2 V was applied to the ITO and aluminum electrodes, the current in the dark was 6.3 × 10 -8 A / cm 2 When a voltage of 2 V was applied and the ITO electrode was irradiated from a height of 10 cm with an LED adjusted to 1.6 μW and a wavelength of 500 nm, the current was 8.6 × 10 -6 A / cm 2 The light-dark ratio when a voltage of 2 V was applied was 1.4 × 10 2 It was. The results of Example 1 and Comparative Example 1 are also shown in Table 3.

[0089] [Table 3]

[0090] Example 2 A glass substrate with an ITO electrode of 70 nm thickness was formed on it, and a vacuum of 4.0 × 10 -5 Compound W1 was deposited as an electron blocking layer to a thickness of 10 nm at 1000 kJ / cm². Next, a 200 nm thick film of 2Ph-BTBT, F6-SubPc-OC6F5, and fullerene (C60) was co-deposited at a deposition rate ratio of 4:4:2 to form a photoelectric conversion layer. Subsequently, dpy-NDI was deposited to a thickness of 10 nm to form a hole blocking layer. Finally, a 70 nm thick aluminum film was deposited as an electrode to fabricate a photoelectric conversion element. When a voltage of 2.6 V was applied to ITO and aluminum electrodes, the current in the dark (dark current) was 6.9 x 10 -10 A / cm 2 In addition, when a voltage of 2.6 V was applied and the ITO electrode was irradiated from a height of 10 cm with an LED adjusted to 1.6 μW and a wavelength of 500 nm, the current (light current) was 3.0 × 10 -7 A / cm 2 The light-dark ratio when a voltage of 2.6 V was applied was 4.4 × 10 2 It was. [ka]

[0091] Examples 3 to 5, Comparative Example 2 Photoelectric conversion elements were fabricated in the same manner as in Example 2, except that the compounds shown in Table 4 below were used in the electron blocking layer. Note that CzBDF used in Comparative Example 2 is a material disclosed in Prior Patent Document 3. [ka]

[0092] [Table 4] [Industrial Applicability]

[0093] The present invention is useful as a material for a photoelectric conversion element of a photoelectric conversion film stacked imaging device. [Explanation of symbols]

[0094] 1 electrode 2. Hole-blocking layer 3 Photoelectric conversion layer 4 Electron Blocking Layer 5 electrodes 6 PCB

Claims

1. 1. An imaging photoelectric conversion element having a photoelectric conversion layer and an electron blocking layer between two electrodes, characterized in that at least one of the photoelectric conversion layer and the electron blocking layer contains a material for an imaging photoelectric conversion element having a structure represented by the following general formula (1): 【Chemistry 1】 Each L independently represents a single bond, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 4 to 30 carbon atoms and containing a 5-membered heterocyclic structure selected from the group consisting of a pyrrole ring, a furan ring, and a thiophene ring, or a substituted or unsubstituted linking aromatic group in which 2 to 6 of one or more of the aromatic hydrocarbon groups or aromatic heterocyclic groups are linked together. a represents the number of substitutions and is an integer of 1 to 6. Ar １ each independently represents a group represented by the following formula (2): Ar ２ each independently represents a substituted or unsubstituted aromatic heterocyclic group having 3 to 30 carbon atoms and containing at least one azine skeleton represented by any one of the following formulas (3) to (7), or a substituted or unsubstituted linking aromatic group containing at least one aromatic heterocyclic group in which 2 to 7 of one or more of the aromatic heterocyclic groups or aromatic hydrocarbon groups having 6 to 30 carbon atoms are linked together, provided that the group bonded to L is the aromatic heterocyclic group. 【Chemistry 2】 Ring B represents a heterocycle represented by formula (2a) which is fused to an adjacent ring at any position. * in formula (2) indicates the bonding position with L in formula (1). X represents O, S, or N-Ar ３ Represents. Ar ３ each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 4 to 30 carbon atoms and containing any 5-membered heterocyclic structure selected from the group consisting of a pyrrole ring, a furan ring, and a thiophene ring, a substituted or unsubstituted linking aromatic group in which 2 to 6 of one or more of the aromatic hydrocarbon groups or the aromatic heterocyclic groups are linked together, or L-Ar ２ Shows. R １ , R ２ , and R ３ represents a substituent, each independently representing an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 4 to 30 carbon atoms and containing a 5-membered heterocyclic structure, or a substituted or unsubstituted linked aromatic group in which 2 to 6 of one or more of the aromatic hydrocarbon groups or heteroaromatic groups are linked together. １ , R ２ , and R ３ may be bonded to any adjacent substituent to form a ring or a condensed ring with the adjacent ring. c represents an integer of 0 to 4, d represents an integer of 0 to 2, and e represents an integer of 0 to 4. 【Transformation 3】 * represents the bonding position with L in the general formula (1), Y represents N, CH, or C—, and at least one Y represents N. Here, C— indicates a case where the group is linked to another aromatic heterocyclic group or an aromatic hydrocarbon group.

2. Ar in the general formula (1) ２ 2. The photoelectric conversion element for imaging according to claim 1, wherein the group comprises at least one of a substituted or unsubstituted pyridine, pyrimidine, or triazine skeleton.

3. Ar in the general formula (1) ２ 2. The photoelectric conversion element for imaging according to claim 1, wherein the compound (I) contains at least one substituted or unsubstituted triazine skeleton.

4. 2. The photoelectric conversion element for imaging according to claim 1, wherein the energy level of the highest occupied molecular orbital (HOMO) of the material for the photoelectric conversion element obtained by a structural optimization calculation using density functional theory calculation B3LYP / 6-31G(d) is −4.5 eV or less.

5. The photoelectric conversion element for imaging according to claim 4, characterized in that the energy level of the lowest unoccupied molecular orbital (LUMO) of the material for the photoelectric conversion element obtained by a structural optimization calculation using density functional theory calculation B3LYP / 6-31G(d) is −2.5 eV or higher.

6. The material for the photoelectric conversion element is 1×10 －６ cm ２ 6. The imaging photoelectric conversion element according to claim 1, wherein the element has a hole mobility of at least 1 / Vs.

7. R in the general formula (1) １ , R ２ , R ３ represents an aromatic heterocyclic group having 4 to 30 carbon atoms containing a five-membered heterocyclic structure, the five-membered heterocyclic structure being a pyrrole ring, a furan ring, or a thiophene ring.

8. 8. The photoelectric conversion element for imaging according to claim 1, wherein the material for the photoelectric conversion element is amorphous.

9. 9. The photoelectric conversion element for imaging according to claim 1, wherein the material for the photoelectric conversion element is used as a hole transport material.

10. 2. The image pickup photoelectric conversion element according to claim 1, wherein the photoelectric conversion layer contains an electron transporting material.

11. 2. The imaging photoelectric conversion element according to claim 1, wherein the electron blocking layer contains the material for the imaging photoelectric conversion element.

Images