Photoelectric conversion element

Abstract

Provided is a photoelectric conversion element for imaging, which uses a material that achieves high sensitivity and high resolution of the photoelectric conversion element for imaging. Specifically, the photoelectric conversion element for imaging has one or more organic layers between two electrodes, and in the photoelectric conversion element, at least one organic layer contains a material for photoelectric conversion elements represented by any one of general formulae (1)-(3). [Formula 1] X is N-Ar4 or the like, Ar1-Ar4 are each independently an aromatic hydrocarbon group having 6-30 carbon atoms or the like, L1 are each independently an aromatic hydrocarbon group having 6-30 carbon atoms or the like, and a-c are each independently an integer of 0-3. Ring A is an aromatic ring selected from any one of formulae (4a)-(4d), and is condensed with the aromatic ring at an arbitrary position. In general formulae (1) to (3), when ring A is represented by formula (4c), c = 0. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to a photoelectric conversion element material and a photoelectric conversion element using the photoelectric conversion element material, and particularly to a photoelectric conversion element for imaging using the photoelectric conversion element material that is effective for imaging equipment.

[0002] In recent years, the development of organic electronic devices using thin films formed from organic semiconductors has been advancing. For example, electroluminescent elements, solar cells, transistor elements, and photoelectric conversion elements can be exemplified. Among these, the development of organic electroluminescence (EL) elements, which are organic-based electroluminescent elements, is particularly advanced. While promoting their application in smartphones, televisions, and the like, development continues with the goal of achieving higher functionality.

[0003] In photoelectric conversion element, before, the development / practicality of the element using the PN junction of inorganic semiconductors such as silicon was promoted, and the research on the high-functionalization of digital cameras, smart phone cameras, the application in surveillance cameras, automotive sensors, etc. was being carried out, and as the subject in order to cope with these various uses, high sensitivity and pixel miniaturization (high resolution) were listed. In the photoelectric conversion element using inorganic semiconductors, in order to obtain a color image, the method of configuring a color filter corresponding to the red, green, blue (red, green, blue, RGB) as the three primary colors of light on the light receiving portion of the photoelectric conversion element was mainly adopted. In the described method, since the color filter of RGB is configured on a plane, there is a subject (non-patent document 1, non-patent document 2) in terms of the utilization efficiency or resolution of the incident light.

[0004] As one of the solutions to the problem of such photoelectric conversion elements, the development of photoelectric conversion elements using organic semiconductors instead of inorganic semiconductors is underway (Non-Patent Documents 1 and 2). This utilizes the property of organic semiconductors that they can selectively absorb only light in a specific wavelength range with high sensitivity, and proposes to solve the problem of high sensitivity and high resolution by stacking photoelectric conversion elements obtained by using organic semiconductors corresponding to the three primary colors of light. In addition, an element obtained by stacking a photoelectric conversion element containing an organic semiconductor and a photoelectric conversion element containing an inorganic semiconductor has also been proposed (Non-Patent Document 3).

[0005] Here, the photoelectric conversion element using an organic semiconductor is an element constructed in the following manner, that is, a photoelectric conversion layer having a thin film containing an organic semiconductor between two electrodes, and a hole blocking layer and / or an electron blocking layer is configured between the photoelectric conversion layer and the two electrodes as needed. In the photoelectric conversion element, excitons are generated by utilizing the photoelectric conversion layer to absorb light with a desired wavelength, and then holes and electrons are generated by charge separation of the excitons. Thereafter, the holes and electrons migrate to each electrode to convert the light into an electrical signal. In order to promote the process, a method of applying a bias voltage between the two electrodes is generally used, but reducing the leakage current from the two electrodes caused by applying the bias voltage has become one of the issues. In this case, it can be said that controlling the migration of holes or electrons in the photoelectric conversion element is the key to the manifestation of the characteristics of the photoelectric conversion element.

[0006] The organic semiconductors used in each layer of a photoelectric conversion element can be broadly divided into P-type organic semiconductors and N-type organic semiconductors. P-type organic semiconductors serve as hole-transporting materials, while N-type organic semiconductors serve as electron-transporting materials. To control the migration of holes and electrons within the photoelectric conversion element, various organic semiconductors with appropriate physical properties, such as hole mobility, electron mobility, highest occupied molecular orbital (HOMO) energy, and lowest unoccupied molecular orbital (LUMO) energy, have been developed. However, these organic semiconductors do not yet possess sufficient properties and are not commercially viable.

[0007] Patent Document 1 proposes a device in which a derivative in which phenoxazine is substituted at both ends of a biscarbazole is used in an electron blocking layer disposed between a photoelectric conversion layer and an electrode.

[0008] Patent Documents 2 and 3 propose devices in which a naphthalene derivative having a carbazole skeleton linked as a tricyclic condensed ring structure is used in an electron blocking layer disposed between a photoelectric conversion layer and an electrode.

[0009] Patent Document 4 proposes a device in which a carbazole derivative having a carbazole skeleton linked as a tricyclic condensed ring structure is used in an electron blocking layer disposed between a photoelectric conversion layer and an electrode.

[0010] Patent Document 5 proposes a device in which a spirofluorene derivative having an acridine skeleton linked as a tricyclic condensed ring structure is used in an electron blocking layer disposed between a photoelectric conversion layer and an electrode.

[0011] Patent Document 6 proposes a device using a compound having a condensed carbazole ring structure in an electron blocking layer disposed between a photoelectric conversion layer and an electrode, but does not disclose specific device characteristics of the compound having a benzocarbazole ring structure.

[0012] Patent Document 7 proposes an element in which a compound having a condensed carbazole ring structure in which an indole ring is condensed with triphenylene is used in an electron blocking layer disposed between a photoelectric conversion layer and an electrode, and a compound having a substituent in the condensed carbazole ring structure is used.

[0013] Prior art literature

[0014] Patent Literature

[0015] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-228614

[0016] Patent Document 2: Japanese Patent Application Laid-Open No. 2019-055919

[0017] Patent Document 3: WO2018 / 235780

[0018] Patent Document 4: Japanese Patent Application Laid-Open No. 2015-153910

[0019] Patent Document 5: Japanese Patent Application Laid-Open No. 2011-82507

[0020] Patent Document 6: Japanese Patent Application Laid-Open No. 2022-115832

[0021] Patent Document 7: Japanese Patent Application Laid-Open No. 2022-108268

[0022] Non-patent literature

[0023] Non-patent literature 1: NHK R&D No. 132, pp. 4-11 (March 2012)

[0024] Non-patent literature 2: NHK R&D No. 174, pp. 4-17 (March 2019)

[0025] Non-patent document 3: 2019 Institute of Electrical and Electronics Engineers (IEEE) International Electron Devices Meeting (IEDM), pp. 16.6.1-16.6.4 (2019) Summary of the Invention

[0026] Problems to be solved by the invention

[0027] Photoelectric conversion elements for imaging are facing challenges in achieving higher sensitivity and resolution, as they advance the functionality of digital cameras and smartphone cameras, as well as their application in surveillance cameras and automotive sensors. In light of this current situation, the present invention aims to provide a photoelectric conversion element for imaging that utilizes a material that achieves both higher sensitivity and higher resolution.

[0028] Technical means to solve the problem

[0029] The present inventors conducted diligent research and discovered that by using a compound having a specific condensed carbazole ring structure, the process of generating holes and electrons by charge separation of excitons in the photoelectric conversion layer and the migration of holes and electrons within the photoelectric conversion element are carried out efficiently, thereby completing the present invention.

[0030] The present invention is a photoelectric conversion element for imaging, comprising one or more organic layers between two electrodes, wherein at least one organic layer comprises a photoelectric conversion element material represented by any one of the following general formulae (1) to (3).

[0031] [Chemistry 1]

[0032]

[0033] In the general formulas (1) to (3), X is O, S or N-Ar 4 , X is preferably O or N-Ar 4 ,Ar 1 ~Ar 4Each of the above is independently deuterium, cyano, a substituted or unsubstituted diarylamino group having 12 to 30 carbon atoms, a substituted or unsubstituted arylheteroarylamino group having 12 to 30 carbon atoms, a substituted or unsubstituted diheteroarylamino group having 12 to 30 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which two to six aromatic groups of the aromatic hydrocarbon groups and aromatic heterocyclic groups are linked. Each of the above is preferably independently deuterium, substituted or unsubstituted An aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking two or three of the aromatic groups of these aromatic hydrocarbon groups and aromatic heterocyclic groups, more preferably a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking two or three of the aromatic groups of these aromatic hydrocarbon groups and aromatic heterocyclic groups, each of which is independently deuterated. Ar 1 ~Ar 3 More preferably, each of them is independently deuterium, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms. 1 Each of the above groups is independently a direct bond, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking two to six of these aromatic groups. Each of the above groups is preferably independently a direct bond, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking two or three of the aromatic groups of these aromatic hydrocarbon groups and aromatic heterocyclic groups. Each of the above groups is more preferably independently a direct bond, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or each of which is independently a direct bond, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which two or three aromatic groups of the aromatic hydrocarbon group and the aromatic heterocyclic group are linked, and more preferably each of which is independently a direct bond, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms.

[0034] a to c are each independently an integer of 0 to 3, preferably 0 to 1. Here, ring A is an aromatic ring selected from any one of the following formulae (4a) to (4d), and ring A is condensed with the aromatic ring of the following formulae (4a) to (4d) at any position.

[0035] [Chemistry 2]

[0036]

[0037] When ring A is represented by the formula (4c), c=0 in the general formulas (1) to (3).

[0038] The compounds represented by the general formulae (1) to (3) are preferably represented by the following formulae (1a) to (3a), respectively.

[0039] [Chemistry 3]

[0040]

[0041] Here, B is independently any condensed carbazole ring structure represented by the following formula (5a) to formula (5s), preferably (5a), (5b), (5c), (5d), (5e), ​​(5h), (5l), (5m), (5n), (5o), and (5s), and more preferably (5a), (5c), (5d), (5h), (5l), (5m), and (5s). * indicates the same as L 1 The bond position.

[0042] [Chemistry 4]

[0043]

[0044] In the photoelectric conversion element materials represented by the general formulae (1) to (3), when represented by the general formula (3), ring A is preferably represented by the formulae (4b) to (4d).

[0045] The photoelectric conversion element material preferably satisfies any one of the following conditions: the energy level of the highest occupied molecular orbital (HOMO) obtained by structure optimization calculation based on density functional calculation B3LYP / 6-31G(d) is -4.0 eV or less, the energy level of the lowest unoccupied molecular orbital (LUMO) obtained by the structure optimization calculation is -2.5 eV or more, and the material has a 1.0×10 -6 cm 2 / Vs or higher hole mobility, or is amorphous.

[0046] The photoelectric conversion element material can be used as a hole transport material.

[0047] In addition, the present invention is a photoelectric conversion element for imaging, comprising a photoelectric conversion layer and an electron blocking layer between two electrodes. The photoelectric conversion element for imaging is characterized in that at least one of the photoelectric conversion layer and the electron blocking layer contains the photoelectric conversion element material.

[0048] The photoelectric conversion element material is preferably an electron blocking layer or a photoelectric conversion layer included in the photoelectric conversion element, and is preferably included as a hole transport material. The photoelectric conversion element material is preferably used for the electron blocking layer. In addition, when the photoelectric conversion element material is included in the electron blocking layer, the photoelectric conversion layer preferably includes an electron transport material, wherein the photoelectric conversion layer is more preferably a fullerene derivative. It is preferable that the photoelectric conversion layer further includes the following material as a hole transport material, the material having a skeleton comprising at least two thiophene rings.

[0049] Effects of the Invention

[0050] The photoelectric conversion element material for imaging represented by any of the general formulae (1) to (3) can achieve appropriate migration of holes or electrons within the photoelectric conversion element, thereby reducing leakage current generated by applying a bias voltage when converting light into electrical energy. As a result, a photoelectric conversion element having a low dark current value and a high light-to-dark ratio can be obtained. The photoelectric conversion element material is effectively used as a photoelectric conversion element material for imaging in a photoelectric conversion film stacked imaging device. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] [ Figure 1 ] is a cross-sectional schematic diagram showing a structural example of a photoelectric conversion element for imaging. DETAILED DESCRIPTION

[0052] The imaging photoelectric conversion element of the present invention has at least one organic layer between two electrodes. The organic layer contains a photoelectric conversion element material represented by any one of the general formulae (1) to (3). Specifically, in an imaging photoelectric conversion element having a photoelectric conversion layer and an electron blocking layer between two electrodes, at least one of the photoelectric conversion layer and the electron blocking layer contains a photoelectric conversion element material represented by any one of the general formulae (1) to (3).

[0053] Hereinafter, the photoelectric conversion element material represented by any one of the general formulae (1) to (3) may be simply referred to as a photoelectric conversion element material, the material of the present invention, or a compound represented by the general formulae (1) to (3).

[0054] The compounds represented by the general formulae (1) to (3) are described below.

[0055] In the general formulas (1) to (3), X is O, S or N-Ar 4 , preferably O or N-Ar 4 .

[0056] Ar 1 ~Ar 4 Each of the above groups is independently deuterium, cyano, a substituted or unsubstituted diarylamino group having 12 to 30 carbon atoms, a substituted or unsubstituted arylheteroarylamino group having 12 to 30 carbon atoms, a substituted or unsubstituted diheteroarylamino group having 12 to 30 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which two to six aromatic groups of the above aromatic hydrocarbon groups and aromatic heterocyclic groups are linked.

[0057] As Ar 1 ~Ar 4 Specific examples of an unsubstituted diarylamino group having 12 to 30 carbon atoms, an unsubstituted arylheteroarylamino group having 12 to 30 carbon atoms, or an unsubstituted diheteroarylamino group having 12 to 30 carbon atoms include diphenylamino, dibiphenylamino, phenylbiphenylamino, naphthylphenylamino, dinaphthylamino, dianthrylamino, diphenanthrenylamino, dibenzofuranylphenylamino, dibenzofuranylbiphenylamino, or bisdibenzofuranylamino. Preferred examples include diphenylamino, dibiphenylamino, phenylbiphenylamino, naphthylphenylamino, dinaphthylamino, dibenzofuranylphenylamino, dibenzofuranylbiphenylamino, and bisdibenzofuranylamino. More preferred examples include diphenylamino, phenylbiphenylamino, dibenzofuranylphenylamino, or dibenzofuranylbiphenylamino. The aryl group constituting the amino group is preferably an aryl group having 6 to 18 carbon atoms, and the heteroaryl group is preferably a heteroaryl group having 6 to 15 carbon atoms. The number of carbon atoms in these amino groups is preferably 12 to 24. The heteroatom in the heteroaryl group is preferably N, S, or O.

[0058] About Ar 1 ~Ar 4 It is an unsubstituted aromatic hydrocarbon compound having 6 to 30 carbon atoms, and preferably has 6 to 18 carbon atoms. The aromatic hydrocarbon group in the case of an unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms has a group obtained by removing one hydrogen atom from an aromatic hydrocarbon. Examples of the aromatic hydrocarbon compound having 6 to 30 carbon atoms include monocyclic aromatic hydrocarbons such as benzene, bicyclic aromatic hydrocarbons such as naphthalene, tricyclic aromatic hydrocarbons such as indene, biphenylene, phenanthracene, anthracene, phenanthrene, and fluorene, fluoranthene, acephenanthrylene, aceanthrylene, triphenylene, pyrene, A radical derived from tetracyclic aromatic hydrocarbons such as tetraphene, condensed tetraphenylene, and pleiadene, or pentacyclic aromatic hydrocarbons such as phenanthracene, perylene, pentaphene, condensed pentaphene, tetraphenylene, and naphthoanthracene by removing one hydrogen atom. Preferably, the radical is benzene, naphthalene, anthracene, phenanthrene, triphenylene, or pyrene, and more preferably, the radical is derived from benzene, naphthalene, anthracene, phenanthrene, pyrene, or triphenylene.

[0059] About Ar 1 ~Ar 4 An unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, preferably having 4 to 12 carbon atoms, and more preferably having 6 to 12 carbon atoms. The unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms includes a group obtained by removing one hydrogen atom from an aromatic heterocyclic group. Examples of aromatic heterocyclic groups having 3 to 17 carbon atoms include nitrogen-containing aromatic compounds having a pyrrole ring, such as pyrrole, pyrrolopyrrole, indole, isoindole, pyrroloisoindole, and carboline; and groups obtained by removing one hydrogen atom from thiophene, benzothiophene, dibenzothiophene, furan, benzofuran, dibenzofuran, carbazole, pyridine, pyrimidine, quinoline, isoquinoline, quinazoline, or quinoxaline. Preferred is a group derived from thiophene, benzothiophene, dibenzothiophene, furan, benzofuran, dibenzofuran, or carbazole, and more preferred is a dibenzothiophene group, a dibenzofuran group, or a carbazolyl group.

[0060] L 1 Each of them is independently a direct bond, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which two to six of these aromatic groups are linked. 1 It is an unsubstituted aromatic hydrocarbon compound having 6 to 30 carbon atoms, preferably 6 to 18 carbon atoms. 1 is an unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, preferably 4 to 12 carbon atoms, and more preferably 6 to 12 carbon atoms. 1 In the case of an unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms or an unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, Ar 1 ~Ar 4 The same applies to the case of an unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms or an unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms.

[0061] In this specification, the unsubstituted linked aromatic group refers to a group selected from Ar 1 ~Ar 4An aromatic group in which two or more aromatic groups among the aromatic hydrocarbon groups and aromatic heterocyclic groups specifically listed are linked by a direct bond at the position of the aromatic hydrocarbon group or aromatic heterocyclic group. These linked aromatic groups may be straight-chain or branched. In addition, the linking position when the benzene rings are linked together may be any of ortho, meta, or para. The aromatic group may be an aromatic hydrocarbon group or an aromatic heterocyclic group, and the multiple aromatic groups may be the same or different.

[0062] In the present specification, examples of the substituents possessed by the aromatic hydrocarbon group, aromatic heterocyclic group, linked aromatic group, diarylamino group, arylheteroarylamino group, and diheteroarylamino group include deuterium and an alkyl group having 1 to 20 carbon atoms.

[0063] When the substituent is an alkyl group having 1 to 20 carbon atoms, the alkyl group may be any of linear, branched, and cyclic, 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; branched saturated hydrocarbon groups such as isopropyl, isobutyl, tert-butyl, neopentyl, 2-ethylhexyl, and 2-hexyloctyl; and saturated alicyclic hydrocarbon groups such as cyclopentyl, cyclohexyl, cyclooctyl, 4-butylcyclohexyl, and 4-dodecylcyclohexyl.

[0064] In the present invention, a substituent is bonded to a carbon atom or a different atom constituting the aromatic ring.

[0065] Preferred specific examples of the photoelectric conversion element material represented by general formulae (1) to (3) of the present invention are shown below, but the present invention is not limited thereto.

[0066] [Chemistry 5]

[0067]

[0068] [Chemistry 6]

[0069]

[0070] [Chemistry 7]

[0071]

[0072] [Chemistry 8]

[0073]

[0074] [Chemistry 9]

[0075]

[0076] [Chemistry 10]

[0077]

[0078] [Chemistry 11]

[0079]

[0080] [Chemistry 12]

[0081]

[0082] [Chemistry 13]

[0083]

[0084] [Chemistry 14]

[0085]

[0086] [Chemistry 15]

[0087]

[0088] [Chemistry 16]

[0089]

[0090] The photoelectric conversion element material represented by any of the general formulae (1) to (3) can be obtained by synthesizing the material by a method based on various organic synthesis reactions 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 purifying the material by a known method such as recrystallization, column chromatography, and sublimation purification, but the method is not limited to the above methods.

[0091] Regarding the material for the photoelectric conversion element, the energy level of the highest occupied molecular orbital (HOMO) obtained by structure optimization calculation based on density functional calculation B3LYP / 6-31G(d) is preferably below -4.0 eV, more preferably in the range of -6.0 eV to -4.5 eV, and even more preferably in the range of -5.5 eV to -4.5 eV.

[0092] The energy level of the lowest unoccupied molecular orbital (LUMO) obtained by the structure optimization calculation is preferably not less than -2.5 eV, more preferably -2.0 eV to -0.5 eV, and even more preferably -2.0 eV to -1.0 eV.

[0093] The photoelectric conversion element material preferably has a difference (absolute value) between the HOMO level and the LUMO level in the range of 2.5 eV to 5.0 eV, more preferably in the range of 3.0 eV to 4.5 eV, and even more preferably in the range of 3.5 eV to 4.0 eV.

[0094] The photoelectric conversion element material preferably has a 1.0×10 -6 cm 2 / Vs~1.0cm 2 / Vs, more preferably 2.0×10 -5 cm 2 / Vs~1.0×10 -1 cm 2 The hole mobility can be evaluated by a known method such as a method based on a field effect transistor (FET) transistor element, a method based on a time-of-flight method, or a space charge limited current (SCLC) method.

[0095] The photoelectric conversion element material is preferably amorphous. Amorphousness can be confirmed by various methods, such as by detecting no peak using X-ray diffraction (XRD) or no endothermic peak using differential scanning calorimetry (DSC).

[0096] Next, an imaging photoelectric conversion element using the above-mentioned photoelectric conversion element material will be described, but the structure of the imaging photoelectric conversion element of the present invention is not limited thereto.

[0097] Figure 1 This is a cross-sectional view schematically showing the structure of an imaging photoelectric conversion element using a material for imaging photoelectric conversion elements represented by any one of the general formulas (1) to (3), wherein 1 represents a substrate, 2 represents an electrode, 3 represents an electron blocking layer, 4 represents a photoelectric conversion layer, 5 represents a hole blocking layer, and 6 represents an electrode. Figure 1 The structure can add or omit layers as needed. Figure 1In the opposite structure, the electrode 6, hole blocking layer 5, photoelectric conversion layer 4, electron blocking layer 3, and electrode 2 are stacked on the substrate 1 in this order. In this case, additional layers or omissions may be made as needed. In the aforementioned imaging photoelectric conversion element, the layers constituting the stacked structure on the substrate, excluding electrodes such as the anode and cathode, are sometimes collectively referred to as organic layers.

[0098] Hereinafter, each member and each layer of the photoelectric conversion element of the present invention will be described.

[0099] -Substrate-

[0100] The photoelectric conversion element is preferably supported by a substrate. There are no particular limitations on the substrate, and for example, substrates made of glass, transparent plastic, quartz, and the like can be used.

[0101] -electrode-

[0102] The electrode has the function of capturing holes and electrons generated in the photoelectric conversion layer. In addition, it is also necessary to have the function of allowing light to enter the photoelectric conversion layer. Therefore, it is ideal that at least one of the two electrodes is transparent or translucent. In addition, the material used as the electrode is not particularly limited as long as it is a conductive material. For example, conductive transparent materials such as indium tin oxide (ITO), indium zinc oxide (IZO), SnO2, antimony doped tin oxide (ATO), ZnO, Al doped zinc oxide (AZO), gallium doped zinc oxide (GZO), TiO2 and fluorine doped tin oxide (FTO), 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, etc. can be exemplified. Regarding these materials, multiple types can also be mixed and used as needed. In addition, two or more layers may be laminated.

[0103] -Photoelectric conversion layer-

[0104] The photoelectric conversion layer is a layer that generates holes and electrons by charge separation of excitons generated by incident light. It can be formed by a single photoelectric conversion material, or it can be formed by combining with a P-type organic semiconductor material as a hole transport material, or an N-type organic semiconductor material as an electron transport material. In addition, two or more P-type organic semiconductors can be used, and two or more N-type organic semiconductors can also be used. It is ideal that one or more of these P-type organic semiconductors and / or N-type organic semiconductors use a pigment material having the function of absorbing light of a desired wavelength in the visible region. Regarding the P-type organic semiconductor material as a hole transport material, a photoelectric conversion element material represented by any one of the general formulas (1) to (3) can be used.

[0105] As the P-type organic semiconductor material, any material having hole transport properties may be used. The aforementioned photoelectric conversion element material is preferably used, but other P-type organic semiconductor materials may also be used. Furthermore, two or more compounds represented by the aforementioned general formulas (1) to (3) (the aforementioned photoelectric conversion element materials) may be mixed and used. Furthermore, the compounds represented by the aforementioned general formulas (1) to (3) may be mixed and used with other P-type organic semiconductor materials.

[0106] As other P-type organic semiconductor materials, any material having hole transport properties may be used, and examples thereof include naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, pyrene derivatives, Derivatives, fused tetracene derivatives, triphenylene derivatives, perylene derivatives, fluoranthene derivatives, fluorene derivatives, cyclopentadiene derivatives, furan derivatives, thiophene derivatives, pyrrole derivatives, benzofuran derivatives, benzothiophene derivatives, dinaphthothienothiophene derivatives, indole derivatives, pyrazoline derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, carbazole derivatives, indolocarbazole and other aromatic compounds, aromatic amine derivatives, styrylamine derivatives, benzidine derivatives, porphyrin derivatives, phthalocyanine derivatives, or quinacridone derivatives. Thiophene derivatives are preferred, and materials having a skeleton containing at least two thiophene rings are preferred. For example, 2Ph-BTBT (2,7-diphenyl[1]benzothieno[3,2-b][1]benzothiophene) can be mentioned.

[0107] Furthermore, as a P-type organic semiconductor material, a polymer-type one can be used. Examples of such polymer-type P-type organic semiconductor materials include polyphenylene vinylene derivatives, polyparaphenylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, and polythiophene derivatives. Furthermore, a mixture of two or more selected from the compounds represented by the general formulas (1) to (3) of the present invention, P-type organic semiconductor materials, or polymer-type P-type organic semiconductor materials can also be used.

[0108] As N-type organic semiconductor materials, any material having electron transport properties may be used. Examples include naphthalenetetracarboxylic acid diimide, perylenetetracarboxylic acid diimide, fullerenes (fullerene derivatives), azole derivatives such as imidazole, thiazole, thiadiazole, oxazole, oxadiazole, and triazole. Fullerene derivatives are preferred. Furthermore, a mixture of two or more materials selected from N-type organic semiconductor materials may be used.

[0109] -Electron blocking layer-

[0110] The electron blocking layer is provided to suppress the dark current generated by injecting electrons from one of the electrodes into the photoelectric conversion layer when a bias voltage is applied between the two electrodes. In addition, it also has a hole transport function of transporting holes generated by charge separation in the photoelectric conversion layer to the electrode, and can be configured as a single layer or multiple layers as needed. A P-type organic semiconductor material as a hole transport material can be used in the electron blocking layer. As a P-type organic semiconductor material, any material with hole transport properties can be used, preferably a compound represented by the general formula (1) to the general formula (3), and other P-type organic semiconductor materials or polymeric P-type organic semiconductor materials can also be used. Specific examples of other P-type organic semiconductor materials and polymeric P-type organic semiconductor materials are the same as those exemplified in the item of the photoelectric conversion layer. In addition, the compounds represented by the general formula (1) to the general formula (3) and the other P-type organic semiconductor materials or polymeric P-type organic semiconductor materials can also be used in combination.

[0111] -Hole blocking layer-

[0112] The hole-blocking layer is provided to suppress dark current caused by hole injection from one electrode into the photoelectric conversion layer when a bias voltage is applied between two electrodes. It also serves as an electron transport layer, transferring electrons generated by charge separation in the photoelectric conversion layer to the electrodes. It can be configured as a single layer or multiple layers as needed. N-type organic semiconductors with electron-transport properties can be used in the hole-blocking layer. As N-type organic semiconductor materials, any material having electron transport properties may be used. Examples thereof include polycyclic aromatic polycarboxylic acid anhydrides such as naphthalenetetracarboxylic acid diimide or perylenetetracarboxylic acid diimide, or imides thereof; fullerenes such as C60 or C70 (fullerene derivatives); azole derivatives such as imidazole, thiazole, thiadiazole, oxazole, oxadiazole, and triazole; tris(8-hydroxyquinolinolato)aluminum(III) derivatives; phosphine oxide derivatives; nitro-substituted fluorene derivatives; diphenylquinone derivatives; thiopyran dioxide derivatives; carbodiimides; fluorenylidenemethane derivatives; anthraquinone dimethane and anthrone derivatives; bipyridine derivatives; quinoline derivatives; and indolocarbazole derivatives. Furthermore, two or more materials selected from N-type organic semiconductor materials may be used in combination.

[0113] The hydrogen in the photoelectric conversion element material represented by any one of the general formulae (1) to (3) may be deuterium. That is, in addition to the hydrogen on the aromatic ring in the general formulae (1), (2), (3), (1a), (2a), (3a), (4a), (4b), (4c), (4d), (5a), (5b), (5c), (5d), (5e), ​​(5f), (5g), (5h), (5i), (5j), (5l), (5m), (5n), (5o), (5p), (5r), and (5s), Ar may be included. 1 、Ar 2 、Ar 3 、Ar 4 , and L 1 In the case of substituents such as the above or any of the substituents possessed by them, part or all of the hydrogen atoms on the alkyl group or the aromatic ring may be deuterium.

[0114] Furthermore, part or all of the hydrogen contained in the compound used as the N-type organic semiconductor material and the P-type organic semiconductor material may be deuterium.

[0115] The film-forming method of each layer when producing the imaging photoelectric conversion element of the present invention is not particularly limited, and the element can be produced by either a dry process or a wet process.

[0116] If necessary, the organic layer containing the photoelectric conversion element material represented by any one of the general formulae (1) to (3) may be formed into a plurality of layers.

[0117] Example

[0118] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[0119] Calculation Example

[0120] Calculation of HOMO and LUMO values

[0121] The HOMO and LUMO values ​​of the compounds (1), (13), (22), (34), (45), (51), (58), (74), (84), (89), (94), (95), (101), (107), and (109) represented by the general formulae (1) to (3) of the present invention were calculated. The calculations were performed using density functional theory (DFT) and Gaussian as a calculation program, and by structure optimization calculations based on density functional theory B3LYP / 6-31G(d). The results are shown in Table 1. It can be said that all the materials of the present invention have preferred HOMO and LUMO values.

[0122] For comparison, HOMO and LUMO were calculated for Compound H1, Compound H2, Compound H3, Compound H4, and Compound H5 using the same method as for the compounds represented by General Formulae (1) to (3) of the present invention. The results are shown in Table 1.

[0123] [Chemistry 17]

[0124]

[0125] [Table 1]

[0126] Compound HOMO[eV] LUMO[eV] (1) -4.9 -1.1 (13) -5.0 -1.4 (22) -5.0 -1.1 (34) -5.1 -1.4 (45) -5.1 -1.3 (51) -5.0 -1.3 (58) -5.0 -1.1 (74) -5.1 -1.1 (84) -5.0 -1.2 (89) -5.0 -1.3 (94) -5.0 -1.0 (95) -5.0 -1.1 (101) -5.0 -1.0 (107) -5.2 -1.2 (109) -5.2 -1.3 H1 -4.9 -0.7 H2 -5.0 -1.3 H3 -4.5 -1.4 H4 -5.1 -1.5 H5 -4.9 -1.4

[0127] The following are synthesis examples of compound (1), compound (13), compound (58), and compound (107) as representative examples. Other compounds were synthesized by similar methods.

[0128] Synthesis Example 1 (Synthesis of Compound (1))

[0129] [Chemistry 18]

[0130]

[0131] Into a 200ml three-necked flask that had been degassed and replaced with nitrogen, T1 (15.1mmol), T2 (19.2mmol), copper iodide (4.1mmol), potassium carbonate (48.5mmol), and 8-quinolinephenol (3.1mmol) were added, and 35ml of 1,3-dimethyl-2-imidazolidinone (DMI) was added thereto, followed by stirring at 190°C for 8 hours. After temporarily cooling to room temperature, 100ml of water was added, and the resulting white precipitate was filtered out. The obtained residue was purified by column chromatography to obtain compound (1) (white solid). The yield was 75%. The obtained solid was evaluated by XRD method, but no peak was detected. Thus, it was confirmed that compound (1) was amorphous. APCI-TOFMSm / z 674[M+1]

[0132] Synthesis Example 2 (Synthesis of Compound (13))

[0133] [Chemistry 19]

[0134]

[0135] Compound (13) (white solid) was obtained in the same manner as in Synthesis Example 1 except that T2 was replaced by T3. The yield was 81%. The obtained solid was evaluated by XRD, but no peak was detected. Therefore, it was confirmed that compound (13) was amorphous. APCI-TOFMS m / z 599 [M+1]

[0136] Synthesis Example 3 (Synthesis of Compound (58))

[0137] [Chemistry 20]

[0138]

[0139] Compound (58) (white solid) was obtained in the same manner as in Synthesis Example 1 except that T1 was changed to T4 and T2 was changed to T5. The yield was 53%. The obtained solid was evaluated by XRD, but no peak was detected. Therefore, it was confirmed that compound (58) was amorphous. APCI-TOFMS m / z 737 [M+1]

[0140] Synthesis Example 4 (Synthesis of Compound (107))

[0141] [Chemistry 21]

[0142]

[0143] Compound (107) (white solid) was obtained in the same manner as in Synthesis Example 1 except that T1 and T2 were replaced with T6 (30.2 mmol) and T7 (15.0 mmol). The yield was 67%. The obtained solid was evaluated by XRD, but no peak was detected. Therefore, it was confirmed that compound (107) was amorphous. APCI-TOFMS m / z 735 [M+1]

[0144] Determination of charge mobility

[0145] Compound (1) was deposited as an organic layer by vacuum deposition to a thickness of approximately 3 μm on an electrode composed of 110 nm thick ITO formed on a glass substrate. Subsequently, charge mobility was measured by time-of-flight using an element formed of 70 nm thick aluminum (Al) as an electrode. The hole mobility was 1.1×10 -4 cm 2 / Vs.

[0146] The hole mobility of each compound was measured in the same manner as in the case of compound (1), except that compound (1) was replaced by the compounds shown in Table 2.

[0147] The results are shown in Table 2.

[0148] [Table 2]

[0149] Compound <![CDATA[Hole mobility [cm 2 / Vs]]]> (1) <![CDATA[1.3×10 -4 ]]> (13) <![CDATA[3.6×10 -4 ]]> (58) <![CDATA[9.1×10 -5 ]]> (84) <![CDATA[3.0×10 -5 ]]> (89) <![CDATA[4.9×10 -5 ]]> (101) <![CDATA[2.1×10 -5 ]]> (107) <![CDATA[6.2×10 -4 ]]> H1 <![CDATA[1.2×10 -5 ]]> H2 <![CDATA[9.3×10 -6 ]]> H3 <![CDATA[1.1×10 -5 ]]> H5 <![CDATA[3.8×10 -5 ]]>

[0150] Example 1

[0151] On an electrode composed of 70 nm thick ITO formed on a glass substrate, a vacuum of 4.0 × 10 -5 Pa deposited compound (1) with a thickness of 10 nm as an electron blocking layer. Then, as a photoelectric conversion layer, 2Ph-BTBT, F6-SubPc-OC6F5, and fullerene (C60) were co-evaporated at a deposition rate ratio of 4:4:2 to form a 200 nm film. Next, dpy-NDI was evaporated to 10 nm to form a hole blocking layer. Finally, aluminum was deposited with a thickness of 70 nm as an electrode to make a photoelectric conversion element. When a voltage of 2.6 V was applied using ITO and aluminum as electrodes, the current in the dark (dark current) was 2.1×10 -10 A / cm 2 In addition, when a voltage of 2.6 V was applied and the ITO electrode side was irradiated from a height of 10 cm by a 1.6 μW LED with a wavelength of 500 nm, the current (bright current) was 2.8×10 -7 A / cm 2 The light-dark ratio when a voltage of 2.6 V is applied is 1.3×10 3These results are shown in Table 3.

[0152] Examples 2 to 7

[0153] A photoelectric conversion element was produced in the same manner as in Example 1 except that the compound shown in Table 3 was used as the electron blocking layer.

[0154] Comparative Examples 1 to 5

[0155] A photoelectric conversion element was produced in the same manner as in Example 1, except that the compound shown in Table 3 was used as the electron blocking layer. Table 3 shows the results of Examples 1 to 7 and Comparative Examples 1 to 5.

[0156] The compounds used in Examples and Comparative Examples are shown below.

[0157] [Chemistry 22]

[0158]

[0159] [Table 3]

[0160]

[0161] The results in Table 3 show that the photoelectric conversion element using the compound of the present invention exhibits a low dark current value and a high light-dark ratio.

[0162] Industrial applicability

[0163] The photoelectric conversion element material for imaging represented by any of the general formulae (1) to (3) can achieve appropriate migration of holes or electrons within the photoelectric conversion element, thereby reducing leakage current generated by applying a bias voltage when converting light into electrical energy. As a result, the photoelectric conversion element of the present invention can achieve a low dark current value and a high light-to-dark ratio. The photoelectric conversion element material used in the photoelectric conversion element of the present invention is effectively used as a photoelectric conversion element material for an imaging device of a photoelectric conversion film stack type.

[0164] Explanation of Figure Numbers

[0165] 1: Substrate

[0166] 2: Electrode

[0167] 3: Electron blocking layer

[0168] 4: Photoelectric conversion layer

[0169] 5: Hole blocking layer

[0170] 6: Electrode

Claims

1. A photoelectric conversion element for imaging, comprising one or more organic layers between two electrodes, wherein at least one organic layer comprises a photoelectric conversion element material represented by any one of the following general formulae (1) to (3). [Chemistry 1] In the general formulas (1) to (3), X is O, S or N-Ar 4 ,Ar 1 ~Ar 4 are each independently deuterium, cyano, a substituted or unsubstituted diarylamino group having 12 to 30 carbon atoms, a substituted or unsubstituted arylheteroarylamino group having 12 to 30 carbon atoms, a substituted or unsubstituted diheteroarylamino group having 12 to 30 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which two to six aromatic groups of the aromatic hydrocarbon groups and aromatic heterocyclic groups are linked, and L 1 Each of a to c is independently a direct bond, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking two to six of these aromatic groups; a to c are independently an integer from 0 to 3; wherein ring A is an aromatic ring selected from any one of the following formulae (4a) to (4d), and ring A is condensed with the aromatic ring of the following formulae (4a) to (4d) at any position. [Chemistry 2] in, When ring A is represented by the formula (4c), c=0 in the general formulas (1) to (3).

2. The imaging photoelectric conversion element according to claim 1, wherein The compounds represented by the general formulae (1) to (3) are represented by the following formulae (1a) to (3a), respectively. [Chemistry 3] Here, B is independently any condensed carbazole ring structure represented by the following formula (5a) to formula (5s), and * represents the structure of L. 1 The bonding position of X, Ar 1 、Ar 2 , L 1 , a and b have the same meanings as in claim 1. [Chemistry 4] 3. The imaging photoelectric conversion element according to claim 1, wherein The L 1 Each independently represents a direct bond, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms.

4. The imaging photoelectric conversion element according to claim 1, wherein The Ar 1 ~Ar 4 Each of the above is independently deuterium, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which two or three aromatic groups of the above aromatic hydrocarbon groups and aromatic heterocyclic groups are linked.

5. The imaging photoelectric conversion element according to claim 1, wherein In the photoelectric conversion element material represented by the general formula (3), ring A is represented by the formulas (4b) to (4d).

6. The imaging photoelectric conversion element according to claim 1, wherein In the photoelectric conversion element material represented by any one of the general formulae (1) to (3), the energy level of the highest occupied molecular orbital (HOMO) obtained by structure optimization calculation based on density functional calculation B3LYP / 6-31G(d) is -4.0 eV or less.

7. The photoelectric conversion element according to claim 1, wherein In the photoelectric conversion element material represented by any one of the general formulae (1) to (3), the energy level of the lowest unoccupied molecular orbital (LUMO) obtained by structure optimization calculation based on density functional calculation B3LYP / 6-31G(d) is -2.5 eV or higher.

8. The photoelectric conversion element according to claim 1, wherein The photoelectric conversion element material represented by any one of the general formulas (1) to (3) has a 1.0×10 -6 cm 2 / Vs and above hole mobility.

9. The photoelectric conversion element according to claim 1, wherein The photoelectric conversion element material represented by any one of the general formulae (1) to (3) is amorphous.

10. The photoelectric conversion element according to claim 1, wherein The photoelectric conversion element material represented by any one of the general formulae (1) to (3) is used as a hole-transporting material of the photoelectric conversion element.

11. A photoelectric conversion element for imaging, comprising a photoelectric conversion layer and an electron blocking layer between two electrodes, wherein the electron blocking layer contains a photoelectric conversion element material represented by any one of the general formulae (1) to (3).

12. The imaging photoelectric conversion element according to claim 11, wherein The photoelectric conversion layer contains an electron transport material.

13. The imaging photoelectric conversion element according to claim 12, wherein: The photoelectric conversion layer contains a fullerene derivative as an electron transport material.

14. The imaging photoelectric conversion element according to claim 13, wherein: The photoelectric conversion layer contains a material having a skeleton including at least two thiophene rings as a hole-transporting material.

Images