Fused polycyclic aromatic compound

Abstract

To provide a material for a photoelectric conversion element for an excellent imaging device capable of efficiently absorbing light in a blue light region near 450nm and showing a large light-dark current ratio, and to provide an organic photoelectric conversion element using the photoelectric conversion material.SOLUTION: Formula (1) In the formula (1), X each independently represents an oxygen atom, a sulfur atom or a selenium atom, and R1 to R12 each independently represent a hydrogen atom or a residue obtained by removing one hydrogen atom from an aromatic compound. The condensed polycyclic aromatic compound according to claim 1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a novel fused polycyclic aromatic compound and its use. More specifically, the present invention relates to a fused polycyclic aromatic compound that is an anthracene derivative, an organic thin film containing the compound, and an organic photoelectric conversion element having the organic thin film.

[0002] In recent years, organic thin-film devices such as field-effect transistors and organic photoelectric conversion elements have attracted attention, and various organic electronic materials, such as fused polycyclic aromatic compounds, which are used in these thin-film devices, have been researched and developed. For example, Patent Document 1 discloses a photoelectric conversion element in which an N-type organic semiconductor is used as a photoelectric conversion layer, but the dark current cannot be reduced sufficiently.

[0003] To address this issue, Patent Document 2 discloses a photoelectric conversion element that reduces dark current by using an organic photoelectric conversion material having a specific structure. However, this photoelectric conversion element has an electron blocking layer and a hole blocking layer as constituent elements of the element, and there is a problem in that the dark current cannot be sufficiently reduced by using only a single photoelectric conversion layer.

[0004] Patent Document 3 shows that a thin film of an anthracene derivative has organic semiconductor properties. Patent Document 4 studies the application of an anthracene derivative to a P-type organic semiconductor in an organic photoelectric conversion element.

[0005] However, the anthracene derivative constituting the organic photoelectric conversion layer of Patent Document 4 is transparent to visible light, and an organic dye that selectively absorbs green light in the vicinity of 560 nm functions as the photoelectric conversion material. Therefore, there was a problem in that it was not an organic semiconductor material that had high photoelectric conversion characteristics in the blue light region and could obtain a sufficient light-to-dark current ratio. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5520560 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-174921 [Patent Document 3] U.S. Patent No. 7,781,761 [Patent Document 4] WO2019 / 150988 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in view of the above-mentioned conventional problems, and aims to provide a material for an organic photoelectric conversion element that has excellent photoelectric conversion characteristics in the blue light region and can obtain a sufficient light-to-dark current ratio, an organic thin film containing the material for an organic photoelectric conversion element, and an organic semiconductor device having the organic thin film (a photoelectric conversion element with a large light-to-dark current ratio in the blue light region). [Means for solving the problem]

[0008] As a result of extensive research, the present inventors have found that the above problems can be solved by using a novel fused polycyclic aromatic compound having a specific structure, and have thus completed the present invention. That is, the present invention provides: [1] General formula (1)

[0009] [ka]

[0010] (In formula (1), X each independently represents an oxygen atom, a sulfur atom, or a selenium atom; R to R 12 each independently represents a hydrogen atom or a residue obtained by removing one hydrogen atom from an aromatic compound. a condensed polycyclic aromatic compound represented by [2] The condensed polycyclic aromatic compound according to the above item [1], wherein X is each independently an oxygen atom or a sulfur atom. [3]R1 to R 12each independently represents a hydrogen atom or a residue obtained by removing one hydrogen atom from an aromatic hydrocarbon compound; [4] R3 to R6 and R9 to R 12

[0023] The condensed polycyclic aromatic compound according to any one of [1] to [3] above, wherein [5] The condensed polycyclic aromatic compound according to the above item [4], wherein R2 and R8 are hydrogen atoms. [6] The condensed polycyclic aromatic compound according to the above item [5], wherein R1 and R7 are each independently a hydrogen atom, a phenyl group, a biphenyl group, or a naphthyl group. [7] The condensed polycyclic aromatic compound according to the above item [6], wherein R1 and R7 are the same. [8] A material for an organic photoelectric conversion element, comprising the fused polycyclic aromatic compound according to any one of [1] to [7] above. [9] An organic thin film containing the condensed polycyclic aromatic compound according to any one of [1] to [7] above.

[10] An organic photoelectric conversion element having the organic thin film according to the preceding item [9], and

[11] An organic photoelectric conversion element having the organic thin film according to the above item [9] in a photoelectric conversion layer. Regarding. [Effects of the Invention]

[0011] The organic photoelectric conversion element using the fused polycyclic aromatic compound represented by formula (1) of the present invention has an absorption band in the blue light region around 450 nm and exhibits a large light-to-dark current ratio, and therefore can be used in organic photoelectric conversion elements for blue light, organic imaging elements, and materials therefor. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 shows a cross-sectional view illustrating an embodiment of the organic photoelectric conversion element of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described in detail below. The description of the constituent elements described herein is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to such embodiments and specific examples.

[0014] The fused polycyclic aromatic compound of the present invention is represented by the above general formula (1). In formula (1), X each independently represents an oxygen atom, a sulfur atom, or a selenium atom; R to R 12 each independently represents a hydrogen atom or a residue obtained by removing one hydrogen atom from an aromatic compound.

[0015] R1 to R in formula (1) 12 The aromatic compound that can be the residue represented by is not particularly limited as long as it is a compound having aromaticity, and examples thereof include benzene, biphenyl, naphthalene, triphenyl, anthracene, phenanthrene, chrysene, pyrene, triphenylene, fluorene, pyridine, thiophene, furan, benzothiophene, benzofuran, dibenzothiophene, dibenzofuran, thienothiophene, naphthofuran, and naphthothiophene.

[0016] R1 to R in formula (1) 12 The residue obtained by removing a hydrogen atom from an aromatic compound represented by the formula (I) is preferably a residue obtained by removing one hydrogen atom from an aromatic hydrocarbon compound, more preferably a residue obtained by removing one hydrogen atom from benzene, biphenyl, naphthalene, triphenyl, anthracene, or phenanthrene, and even more preferably a residue obtained by removing one hydrogen atom from benzene, biphenyl, or naphthalene.

[0017] It is preferable that X in formula (1) is each independently an oxygen atom or a sulfur atom, and it is more preferable that the two X in formula (1) are the same oxygen atom or sulfur atom.

[0018] R1 to R in formula (1) 12are preferably each independently a hydrogen atom or a residue obtained by removing one hydrogen atom from an aromatic hydrocarbon compound, R1, R2, R7 and R8 are each independently a hydrogen atom or a residue obtained by removing one hydrogen atom from an aromatic hydrocarbon compound, and R3 to R6 and R9 to R 12 is more preferably a hydrogen atom, R1 and R7 are each independently a hydrogen atom or a residue obtained by removing one hydrogen atom from an aromatic hydrocarbon compound, and R2 to R6 and R8 to R 12 is more preferably a hydrogen atom, and R1 and R7 are each independently a hydrogen atom, a phenyl group, a biphenyl group, or a naphthyl group, and R2 to R6 and R8 to R 12 is particularly preferably a hydrogen atom, and R1 and R7 are the same hydrogen atom, a phenyl group, a biphenyl group, or a naphthyl group, and R2 to R6 and R8 to R 12 is most preferably a hydrogen atom.

[0019] The fused polycyclic aromatic compound represented by formula (1) of the present invention is preferably a compound having the above-mentioned preferable X and preferable R1 to R2. 12 The combination of is more preferred.

[0020] Next, a method for synthesizing the fused polycyclic aromatic compound represented by general formula (1) of the present invention will be described in detail. The fused polycyclic aromatic compound represented by general formula (1) can be synthesized by various conventionally known methods, but as an example, the synthesis method according to the following scheme will be described.

[0021] The compound represented by formula (1) can be synthesized by known methods such as those disclosed in Patent Document 3 and ACS Appl. Energy Mater. 2020, 3(11), 10752. For example, a synthesis method according to the following scheme can be mentioned. 2,6-diaminoanthraquinone (A) is used as a raw material to form 2,6-dibromoanthraquinone (B) by a Sandmeyer reaction, and this is reduced to obtain 2,6-dibromoanthracene (C). (In the following scheme, a bromide is shown as an example of the halide (B), but the halide (B) is not limited to this.) The compound represented by formula (1) can also be synthesized by a known method such as that disclosed in J. Am. Chem. Soc., 2017, 139(48), 17261. 2,6-Dihydroxyanthraquinone (D) is reduced as a raw material to form 2,6-dihydroxyanthracene (E), which is then trifluoromethylsulfonylated to obtain trifluoromethylsulfonylated product (F). Next, the fused polycyclic aromatic compound of the present invention represented by general formula (1) is synthesized using the compound (C) or (F) obtained above and compound (G) or (G') as starting materials. Here, the reaction between compound (C) or (F) and compound (G) can be carried out by a known method similar to the Suzuki-Miyaura coupling reaction, and the reaction between compound (C) or (F) and compound (G') can be carried out by a known method similar to the Migita-Kosugi-Stiel cross-coupling reaction. For details of these coupling reactions, see, for example, "Metal-Catalyzed Cross-Coupling Reactions - Second, Completely Revised and Enlarged Edition."

[0022] [ka]

[0023] In the above coupling reaction, it is preferable to use 2 to 10 moles, and more preferably 2 to 4 moles, of compound (G) or (G') per mole of compound (C) or (F). The reaction temperature for the above coupling reaction is usually −10 to 200° C., preferably 20 to 160° C., and more preferably 30 to 120° C. The reaction time is not particularly limited, but is usually 1 to 72 hours, and preferably 2 to 48 hours. Depending on the type of catalyst described below, the reaction temperature can be lowered or the reaction time can be shortened. The above coupling reaction is preferably carried out in an inert gas atmosphere such as an argon atmosphere, a nitrogen-substituted atmosphere, a dry argon atmosphere, or a dry nitrogen stream.

[0024] It is preferable to use a catalyst in the coupling reaction using compound (G). Examples of catalysts that can be used in the coupling reaction include tri-tert-butylphosphine, triadamantylphosphine, 1,3-bis(2,4,6-trimethylphenyl)imidazolidinium chloride, 1,3-bis(2,6-diisopropylphenyl)imidazolidinium chloride, 1,3-diadamantylimidazolidinium chloride, or a mixture thereof; metallic Pd, Pd / C (hydrated or non-hydrated), palladium acetate, palladium trifluoroacetate, palladium methanesulfonate, palladium toluenesulfonate, palladium chloride, palladium bromide, palladium iodide, bis(acetonitrile)palladium(II) dichloride, bis( Examples of suitable catalysts include benzonitrile (benzonitrile) palladium(II) dichloride, tetrakis(acetonitrile) palladium(II) tetrafluoroborate, tris(dibenzylideneacetone)dipalladium(0), tris(dibenzylideneacetone)dipalladium(0) chloroform complex, bis(dibenzylideneacetone)palladium(0), bis(triphenylphosphino)palladium dichloride (Pd(PPh3)2Cl2), (1,1'-bis(diphenylphosphino)ferrocene)palladium dichloride (Pd(dppf)Cl2), and tetrakis(triphenylphosphine)palladium (Pd(PPh3)4). Palladium-based catalysts are preferred. Pd(dppf)Cl2, Pd(PPh3)2Cl2, and Pd(PPh3)4 are more preferred, with Pd(PPh3)2Cl2 and Pd(PPh3)4 being even more preferred. A mixture of two or more of these catalysts may be used, or one of these catalysts may be mixed with another catalyst. The amount of the catalyst used in the coupling reaction is preferably 0.001 to 0.500 mol, more preferably 0.001 to 0.100 mol, and even more preferably 0.001 to 0.060 mol, per 1 mol of compound (F).

[0025] In the coupling reaction using compound (G), it is preferable to use a basic compound. Examples of basic compounds include hydroxides such as lithium hydroxide, barium hydroxide, sodium hydroxide, and potassium hydroxide; carbonates such as lithium carbonate, lithium hydrogen carbonate, sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, and cesium carbonate; acetates such as lithium acetate, sodium acetate, and potassium acetate; phosphates such as trisodium phosphate and tripotassium phosphate; alkoxides such as sodium methoxide, sodium ethoxide, and potassium tert-butoxide; metal hydrides such as sodium hydride and potassium hydride; and organic bases such as pyridine, picoline, lutidine, triethylamine, tributylamine, diisopropylethylamine, and N,N-dicyclohexylmethylamine. Phosphates or hydroxides are preferred, and trisodium phosphate, tripotassium phosphate, sodium hydroxide, or potassium hydroxide is more preferred. These basic compounds may be used alone or in combination of two or more. The amount of these basic compounds used in the coupling reaction is preferably 2 to 100 moles, more preferably 2 to 10 moles, per mole of compound (C) or (F).

[0026] In the coupling reaction using compound (G'), it is preferable to use a Pd or Ni catalyst, and any Pd or Ni catalyst can be used without any particular limitation. Examples of the Pd-based catalyst include the same catalysts as those described in the section on catalysts that can be used in the coupling reaction using compound (G). Examples of Ni-based catalysts include tetrakis(triphenylphosphine)nickel (Ni(PPh3)4), nickel(II) acetylacetonate (Ni(acac)2), dichloro(2,2'-bipyridine)nickel (Ni(bpy)Cl2), dibromobis(triphenylphosphine)nickel (Ni(PPh3)2Br2), bis(diphenylphosphino)propanenickel dichloride (Ni(dppp)Cl2), and bis(diphenylphosphino)ethanenickel dichloride (Ni(dppe)Cl2), with Pd(dppf)Cl2, Pd(PPh3)2Cl2, and Pd(PPh3)4 being preferred, and Pd(PPh3)2Cl2 and Pd(PPh3)4 being more preferred. A mixture of two or more of these catalysts may be used, or one of these catalysts may be mixed with another catalyst. The amount of the catalyst used in the coupling reaction is preferably 0.001 to 0.500 moles, more preferably 0.001 to 0.100 moles, and even more preferably 0.001 to 0.060 moles, per mole of compound (C) or (F).

[0027] In the coupling reaction using compound (G'), an alkali metal salt may be used in combination. The alkali metal salt that can be used in combination is not particularly limited as long as it is a salt containing an alkali metal, and examples thereof include lithium chloride, lithium bromide, and lithium iodide, with lithium chloride being preferred. The amount of the alkali metal salt added is preferably 0.001 to 5.0 moles per mole of compound (F).

[0028] The above coupling reaction may be carried out in a solvent. Any solvent can be used as long as it can dissolve the necessary raw materials, Compound (C) or (F) and Compound (G) or (G'), as well as any optional catalysts, basic compounds, alkali metal salts, etc. Specific examples of the solvent include aromatic compounds such as chlorobenzene, o-dichlorobenzene, bromobenzene, nitrobenzene, toluene, and xylene; saturated aliphatic hydrocarbons such as n-hexane, n-heptane, and n-pentane; alicyclic hydrocarbons such as cyclohexane, cycloheptane, and cyclopentane; saturated aliphatic halogenated hydrocarbons such as n-propyl bromide, n-butyl chloride, n-butyl bromide, dichloromethane, dibromomethane, dichloropropane, dibromopropane, dichlorobutane, chloroform, bromoform, carbon tetrachloride, carbon tetrabromide, trichloroethane, tetrachloroethane, and pentachloroethane; halogenated cyclic hydrocarbons such as chlorocyclohexane, chlorocyclopentane, and bromocyclopentane; and ethyl acetate. Examples of suitable solvents include esters such as propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, and butyl butyrate; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ethers such as diethyl ether, dipropyl ether, dibutyl ether, cyclopentyl methyl ether, dimethoxyethane, tetrahydrofuran, 1,4-dioxane, and 1,3-dioxane; amides such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide; glycols such as ethylene glycol, propylene glycol, and polyethylene glycol; and sulfoxides such as dimethyl sulfoxide. These solvents may be used alone or in combination.

[0029] The method for purifying the fused polycyclic aromatic compound represented by general formula (1) is not particularly limited, and known methods such as recrystallization, column chromatography, and vacuum sublimation purification can be used. These methods can also be combined as necessary.

[0030] In the above synthesis scheme, R in compound (G) 13 and R 14 each independently represents a hydrogen atom or an alkyl group, or R 13 and R 14are bonded to form an alkylene group. R 13 and R 14 Examples of the alkyl group represented by include alkyl groups having 1 to 6 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, and an n-hexyl group. R 13 and R 14 Examples of the alkylene group formed by bonding include a methylene group, an ethane-1,2-diyl group, a butane-2,3-diyl group, a 2,3-dimethylbutane-2,3-diyl group, and a propane-1,3-diyl group. R in compound (G) 13 and R 14 Preferably, both R3 and R4 are hydrogen atoms, or R3 and R4 are combined to form a 2,3-dimethylbutane-2,3-diyl group.

[0031] In the above synthesis scheme, R in compound (G') 15 ~R 17 R each independently represents a linear or branched alkyl group. 15 ~R 17 The number of carbon atoms in the alkyl group represented by is usually 1 to 8, and preferably 1 to 4. Specific examples of the linear alkyl group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an isobutyl group, an n-pentyl group, and an n-hexyl group, and specific examples of the branched alkyl group include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, and an isohexyl group. R in compound (G') 15 ~R 17 are each independently preferably a methyl group or a butyl group, and more preferably all are methyl groups or all are butyl groups. In addition, R1 to R2 in compounds (G) and (G') 12 represents R1 to R2 in general formula (1). 12 is synonymous with.

[0032] Specific examples of the fused polycyclic aromatic compound of the present invention represented by general formula (1) are shown below, but the present invention is not limited to these specific examples.

[0033] [ka]

[0034] [ka]

[0035] [ka]

[0036] [ka]

[0037] [ka]

[0038] [ka]

[0039] The organic thin film of the present invention contains a fused polycyclic aromatic compound represented by formula (1). The thickness of the organic thin film varies depending on its application, but is usually 1 nm to 1 μm, preferably 5 nm to 500 nm, and more preferably 10 nm to 300 nm.

[0040] The organic thin film forming method of the present invention includes general dry film forming methods and wet film forming methods, specifically, vacuum processes such as resistance heating evaporation, electron beam evaporation, sputtering, and molecular lamination, solution processes such as casting, spin coating, dip coating, blade coating, wire bar coating, and spray coating, printing methods such as inkjet printing, screen printing, offset printing, and relief printing, and soft lithography methods such as microcontact printing, and a combination of these methods may be used to form each layer.

[0041] The fused polycyclic aromatic compound represented by general formula (1) or a thin film thereof can be used to fabricate an organic electronic device, such as a thin film transistor, an organic photoelectric conversion element, an organic solar cell element, an organic EL element, an organic light-emitting transistor element, or an organic semiconductor laser element. Next, the material for an organic photoelectric conversion element and the organic photoelectric conversion element (including a photosensor and an organic imaging element) of the present invention will be described.

[0042] The material for organic photoelectric conversion elements of the present invention contains a fused polycyclic aromatic compound represented by the above formula (1). The content of the compound represented by formula (1) in the material for organic photoelectric conversion elements of the present invention is not particularly limited as long as the required performance in the application in which the material for organic photoelectric conversion elements is used is exhibited, but is usually 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The material for an organic photoelectric conversion element of the present invention may be used in combination with a compound other than the compound represented by formula (1) (for example, a material for an organic photoelectric conversion element other than the compound represented by formula (1)), an additive, etc. The compound, additive, etc. that can be used in combination is not particularly limited as long as the performance required for the application of the organic photoelectric conversion element material is exhibited.

[0043] The organic photoelectric conversion element of the present invention includes the organic thin film of the present invention. The organic photoelectric conversion element is an element in which a photoelectric conversion unit (film) is disposed between a pair of opposing electrode films, and light is incident on the photoelectric conversion unit from above the electrode films. The photoelectric conversion unit generates electrons and holes in response to the incident light, and a signal corresponding to the charge is read out by a semiconductor, indicating the amount of incident light corresponding to the absorption wavelength of the photoelectric conversion film. A readout transistor may be connected to the electrode film on the side where light is not incident. When multiple organic photoelectric conversion elements are arranged in an array, they can indicate not only the amount of incident light but also the incident position information, thereby functioning as an imaging element. Furthermore, if an organic photoelectric conversion element located closer to the light source does not block (transmits) the absorption wavelength of an organic photoelectric conversion element located behind it when viewed from the light source side, multiple organic photoelectric conversion elements may be stacked.

[0044] The organic photoelectric conversion element of the present invention uses an organic thin film containing the fused polycyclic aromatic compound represented by the above formula (1) as a constituent material of the photoelectric conversion section. The photoelectric conversion section often comprises a photoelectric conversion layer and one or more organic thin film layers other than the photoelectric conversion layer selected from the group consisting of an electron transport layer, a hole transport layer, an electron blocking layer, a hole blocking layer, a crystallization prevention layer, and an interlayer contact improving layer. The fused polycyclic aromatic compound of the present invention is preferably used as the organic thin film layer of the photoelectric conversion layer, but it can also be used as the above-mentioned organic thin film layers (particularly, an electron transport layer, a hole transport layer, an electron blocking layer, and a hole blocking layer). The electron blocking layer and the hole blocking layer are also referred to as carrier blocking layers. Furthermore, when used in a photoelectric conversion layer, the fused polycyclic aromatic compound of the present invention may be composed solely of the fused polycyclic aromatic compound of the present invention, or may contain an organic semiconductor material in addition to the fused polycyclic aromatic compound of the present invention. These organic thin film layers may have a laminate structure, or may include an organic thin film formed by co-evaporation of materials, or may be a functional organic thin film formed by forming multiple co-evaporation films, single films, or separate co-evaporation films.

[0045] The electrode film used in the organic photoelectric conversion element of the present invention plays a role of extracting holes from the photoelectric conversion layer or other organic thin film layers and collecting them when the photoelectric conversion layer included in the photoelectric conversion section described below has hole transport properties or when an organic thin film layer other than the photoelectric conversion layer is a hole transport layer having hole transport properties, and also plays a role of extracting electrons from the photoelectric conversion layer or other organic thin film layers and ejecting them when the photoelectric conversion layer included in the photoelectric conversion section has electron transport properties or when an organic thin film layer is an electron transport layer having electron transport properties. Therefore, materials that can be used as the electrode film are not particularly limited as long as they have a certain degree of conductivity, but are preferably selected in consideration of adhesion to adjacent photoelectric conversion layers and other organic thin film layers, electron affinity, ionization potential, stability, etc. Materials that can be used as electrode films include, for example, conductive metal oxides such as tin oxide (NESA), indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); metals such as gold, silver, platinum, chromium, aluminum, iron, cobalt, nickel, and tungsten; inorganic conductive materials such as copper iodide and copper sulfide; conductive polymers such as polythiophene, polypyrrole, and polyaniline; and carbon. These materials may be used in combination, or in two or more layers. The conductivity of the material used for the electrode film is not particularly limited as long as it does not unnecessarily interfere with the light reception of the organic photoelectric conversion element. However, it is preferable to use a substrate with as high a conductivity as possible from the viewpoint of the signal strength and power consumption of the organic photoelectric conversion element. For example, an ITO film with a sheet resistance of 300 Ω / □ or less functions adequately as an electrode film. However, since commercially available substrates with ITO films with conductivities of only a few Ω / □ are available, it is desirable to use a substrate with such high conductivity. The thickness of the ITO film (electrode film) can be selected arbitrarily taking into account conductivity, but is usually about 5 to 500 nm, preferably about 10 to 300 nm. Methods for forming films such as ITO include conventionally known vapor deposition methods, electron beam methods, sputtering methods, chemical reaction methods, and coating methods. The ITO film provided on the substrate may be subjected to UV-ozone treatment, plasma treatment, or the like, as needed.

[0046] Examples of materials for the transparent electrode film used on at least one of the electrode films on the light-incident side include ITO, IZO, SnO2, ATO (antimony-doped tin oxide), ZnO, AZO (Al-doped zinc oxide), GZO (gallium-doped zinc oxide), TiO2, and FTO (fluorine-doped tin oxide).The transmittance of light incident through the transparent electrode film at the absorption peak wavelength of the photoelectric conversion layer is preferably 60% or more, more preferably 80% or more, and particularly preferably 95% or more.

[0047] The electrode film is preferably produced in a plasma-free environment. By producing these electrode films in a plasma-free environment, the influence of plasma on the substrate on which the electrode film is formed is reduced, thereby improving the photoelectric conversion characteristics of the photoelectric conversion element. Here, plasma-free means a state in which no plasma is generated during the deposition of the electrode film, or the distance from the plasma generation source to the substrate is 2 cm or more, preferably 10 cm or more, and more preferably 20 cm or more, thereby reducing the amount of plasma that reaches the substrate.

[0048] Examples of devices that do not generate plasma when forming an electrode film include electron beam deposition devices (EB deposition devices), pulsed laser deposition devices, etc. A method of forming a transparent electrode film using an EB deposition device is called an EB deposition method, and a method of forming a transparent electrode film using a pulsed laser deposition device is called a pulsed laser deposition method.

[0049] Apparatuses that can realize a state in which plasma can be reduced during film formation include, for example, a facing target sputtering apparatus and an arc plasma deposition apparatus.

[0050] When a transparent conductive film is used as an electrode film (e.g., the first conductive film), DC shorts or increased leakage current may occur. One of the reasons for this is thought to be that fine cracks that occur in the photoelectric conversion layer are covered by a dense film such as TCO (Transparent Conductive Oxide), increasing the conductivity between the transparent conductive film and the electrode film on the opposite side. Therefore, when a material with inferior film quality, such as Al, is used for the electrode, an increase in leakage current is unlikely to occur. By controlling the film thickness of the electrode film according to the film thickness (depth of the cracks) of the photoelectric conversion layer, the increase in leakage current can be suppressed.

[0051] Typically, if the conductive film is made thinner than a predetermined value, a rapid increase in resistance occurs. The sheet resistance of the conductive film in the organic photoelectric conversion element for a photosensor of this embodiment is typically 100 to 10,000 Ω / □, allowing for a high degree of freedom in film thickness. Furthermore, the thinner the transparent conductive film, the less light it absorbs, and generally the higher the light transmittance. Higher light transmittance is highly desirable because it increases the amount of light absorbed by the photoelectric conversion layer and improves photoelectric conversion performance.

[0052] The photoelectric conversion section of the organic photoelectric conversion element of the present invention may include a photoelectric conversion layer and an organic thin film layer other than the photoelectric conversion layer. An organic semiconductor film is generally used for the photoelectric conversion layer constituting the photoelectric conversion section, and the organic semiconductor film may be a single layer or multiple layers. In the case of a single layer, a P-type organic semiconductor film, an N-type organic semiconductor film, or a mixed film thereof (bulk heterostructure) is used. On the other hand, in the case of multiple layers, the organic semiconductor film has a structure in which either a P-type organic semiconductor film, an N-type organic semiconductor film, or a mixed film thereof (bulk heterostructure) is stacked, with a buffer layer inserted between the layers. The thickness of the photoelectric conversion layer is usually 50 to 500 nm.

[0053] The organic semiconductor film of the photoelectric conversion layer can be, depending on the wavelength band to be absorbed, a triarylamine compound, a benzidine compound, a pyrazoline compound, a styrylamine compound, a hydrazone compound, a triphenylmethane compound, a carbazole compound, a polysilane compound, a thiophene compound, a phthalocyanine compound, a cyanine compound, a merocyanine compound, an oxonol compound, a polyamine compound, an indole compound, a pyrrole compound, a pyrazole compound, a polyarylene compound, a carbazole derivative, a naphthalene derivative, an anthracene derivative, a chrysene derivative, a phenanthrene derivative, a pentacene derivative, a phenylbutadiene derivative, a styryl derivative, a quinoline derivative, a tetracene derivative, a pyrene derivative, a perylene derivative, a fluoranthene derivative, a quinacridone derivative, a coumarin derivative, a porphyrin derivative, a fullerene derivative, or a metal complex (Ir complex, Pt complex, Eu complex, etc.). In combination with the condensed polycyclic aromatic compound of the present invention, it functions as a P-type organic semiconductor or an N-type organic semiconductor.

[0054] When the fused polycyclic aromatic compound of the present invention is used as a photoelectric conversion layer, it preferably has a HOMO (Highest Occupied Molecular Orbital) level shallower than the HOMO level of the organic semiconductor to be combined with it, which not only suppresses the generation of dark current but also improves the photoelectric conversion efficiency.

[0055] In the organic photoelectric conversion element of the present invention, the organic thin film layer other than the photoelectric conversion layer constituting the photoelectric conversion part can also be used as a layer other than the photoelectric conversion layer, for example, an electron transport layer, a hole transport layer, an electron blocking layer, a hole blocking layer, a crystallization preventing layer, or an interlayer contact improving layer. In particular, by using it as one or more thin film layers selected from the group consisting of an electron transport layer, a hole transport layer, an electron blocking layer, and a hole blocking layer, it is preferable to obtain an element that can efficiently convert even weak light energy into an electric signal.

[0056] The electron transport layer transports electrons generated in the photoelectric conversion layer to the electrode film and blocks holes from moving from the electrode film to which the electrons are transported to the photoelectric conversion layer. The hole transport layer transports generated holes from the photoelectric conversion layer to the electrode film and blocks electrons from moving from the electrode film to which the holes are transported to the photoelectric conversion layer. The electron blocking layer prevents electrons from moving from the electrode film to the photoelectric conversion layer, preventing recombination within the photoelectric conversion layer and reducing dark current. The hole blocking layer prevents holes from moving from the electrode film to the photoelectric conversion layer, preventing recombination within the photoelectric conversion layer and reducing dark current. The hole-blocking layer is formed by laminating or mixing two or more types of hole-blocking substances. The hole-blocking substance is not limited as long as it is a compound that can prevent holes from flowing out of the electrode to the outside of the device. Compounds that can be used in the hole-blocking layer include phenanthroline derivatives such as bathophenanthroline and bathocuproine, silole derivatives, quinolinol derivative metal complexes, oxadiazole derivatives, oxazole derivatives, and quinoline derivatives, and one or more of these can be used.

[0057] Figure 1 shows a typical device structure of an organic photoelectric conversion element of the present invention, but the present invention is not limited to this structure. In the embodiment shown in Figure 1, 1 represents an insulating portion, 2 represents one electrode film, 3 represents an electron blocking layer, 4 represents a photoelectric conversion layer, 5 represents a hole blocking layer, 6 represents the other electrode film, and 7 represents an insulating substrate or another organic photoelectric conversion element. Although a readout transistor is not shown in the figure, it may be connected to the electrode film 2 or 6. Furthermore, if the photoelectric conversion layer 4 is transparent, it may be formed on the outside of the electrode film on the side opposite to the light incident side. Light may be incident on the photoelectric conversion element from either the top or bottom, as long as the components other than the photoelectric conversion layer 4 do not excessively obstruct the incidence of light of the main absorption wavelength of the photoelectric conversion layer. [Example]

[0058] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" means "parts by mass" and "%" means "% by mass" unless otherwise specified. "M" means molar concentration. Furthermore, the reaction temperature described is the internal temperature of the reaction system unless otherwise specified. In the examples, EI-MS was measured using ISQ7000 manufactured by Thermo Scientific, and nuclear magnetic resonance (NMR) was measured using JNM-EC400 manufactured by JEOL. The applied current and voltage measurements of the organic photoelectric conversion elements in the examples were performed using a Semiconductor Parameter Analyzer 4200-SCS (manufactured by Keithley Instruments). Incident light was irradiated using a PVL-3300 (manufactured by Asahi Spectroscopy) with an irradiated light half-width of 20 nm. The light-dark ratio in the examples refers to the current when irradiated with light divided by the current in a dark place.

[0059] Example 1 (Synthesis of condensed polycyclic aromatic compound represented by specific example No. 1) (Step 1) Synthesis of condensed polycyclic aromatic compound represented by specific example No. 1 To DMF (120 parts), 2,6-dibromoanthracene (1.5 parts), 2-trimethylstannyl (naphtho[2,3-b]thiophene) (4.7 parts), copper (I) iodide (0.09 parts), and tetrakis (triphenylphosphine) palladium (0.15 parts) synthesized by the method described in ACS Appl. Energy Mater. 2020, 3 (11), 10752 were added, and the mixture was stirred at 80 ° C. for 4 hours under a nitrogen atmosphere. After the resulting reaction solution was cooled to room temperature, water (100 parts) was added, and the solid was separated by filtration. The resulting solid was washed with acetone and DMF, dried, and then purified by sublimation to obtain the compound represented by specific example No. 1 (1.9 parts, yield 78%).

[0060] [ka]

[0061] The results of EI-MS measurement of the compound represented by No. 1, a specific example obtained above, were as follows. EI-MS m / z: Calcd for C 38 H 22 S2[M + ]: 542.71. Found: 542.16

[0062] Example 2 (Synthesis of condensed polycyclic aromatic compound represented by specific example No. 2) (Step 2) Synthesis of an intermediate compound represented by the following formula 2 Naphtho[2,3-b]furan (5.0 parts) synthesized by the method described in Chemical Communications. 2012, 48(47), 5892 was added to anhydrous THF (140 parts) and cooled to -78°C under a nitrogen atmosphere. A 1.0M THF / hexane solution of lithium diisopropylamide (50.0 parts) was added and stirred for 1 hour. Trimethyltin chloride (7.5 parts) was then added and stirred for 1 hour. The mixture was then warmed to room temperature and stirred for an additional 2 hours. The resulting reaction solution was quenched with water (100 parts), washed with aqueous potassium fluoride solution, and then separated and extracted with ethyl acetate. The resulting organic layer was dried over sodium sulfate, and the solvent was distilled off under reduced pressure. The resulting solid was purified using a silica gel column (developing solvent: hexane) to obtain the intermediate compound represented by the following formula 2 (6.0 parts, yield 61%).

[0063] [ka]

[0064] (Step 3) Synthesis of condensed polycyclic aromatic compound represented by specific example No. 2 To toluene (120 parts), 2,6-dibromoanthracene (1.0 parts) synthesized by the method described in ACS Appl. Energy Mater. 2020, 3(11), 10752, the intermediate compound represented by formula 2 obtained in step 2 (2.9 parts), and tetrakis(triphenylphosphine)palladium (0.10 parts) were added and stirred at 80 ° C. for 6 hours under a nitrogen atmosphere. After the resulting reaction solution was cooled to room temperature, water (100 parts) was added and the solid was separated by filtration. The resulting solid was washed with acetone and DMF, dried, and then purified by sublimation to obtain the compound represented by No. 2 (0.84 parts, yield 55%).

[0065] [ka]

[0066] The results of EI-MS measurement of the compound represented by No. 2, a specific example obtained above, were as follows. EI-MS m / z: Calcd for C 38 H 22 O2[M + ]: 510.59. Found: 510.36

[0067] Example 3 (Synthesis of condensed polycyclic aromatic compound represented by specific example No. 4) (Step 4) Synthesis of condensed polycyclic aromatic compound represented by specific example No. 4 To DMF (150 parts), 2,6-dibromoanthracene (1.5 parts) synthesized by the method described in ACS Appl. Energy Mater. 2020, 3 (11), 10752, 2-trimethylstannyl-6-phenyl (naphtho [2,3-b] thiophene) (5.7 parts) synthesized by the method described in JP-A-2020-189793, copper (I) iodide (0.09 parts), tetrakis (triphenylphosphine) palladium (0.15 parts) were added and stirred at 80 ° C. for 5 hours under a nitrogen atmosphere. After the resulting reaction solution was cooled to room temperature, water (100 parts) was added and the solid was separated by filtration. The obtained solid was washed with acetone and DMF, dried, and then purified by sublimation to obtain the compound represented by No. 4 (1.1 parts, yield 35%).

[0068] [ka]

[0069] The results of EI-MS measurement of the compound represented by No. 4, a specific example obtained above, were as follows. EI-MS m / z: Calcd for C 50 H 30 S2[M + ]: 694.91. Found: 694.56

[0070] Example 4 (Synthesis of condensed polycyclic aromatic compound represented by specific example No. 5) (Step 5) Synthesis of an intermediate compound represented by the following formula 3 To anhydrous THF (120 parts) was added 6-phenyl(naphtho[2,3-b]furan) (3.0 parts) synthesized by the method described in Chemical Communications. 2012, 48(47), 5892. The mixture was cooled to -78°C under a nitrogen atmosphere, and a 1.0M THF / hexane solution (21.0 parts) of lithium diisopropylamide was added and stirred for 1 hour. Subsequently, trimethyltin chloride (3.2 parts) was added and stirred for 1 hour. After warming to room temperature, the mixture was stirred for an additional 2 hours. The resulting reaction solution was quenched with water (100 parts), washed with aqueous potassium fluoride solution, and then separated and extracted with ethyl acetate. The resulting organic layer was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The resulting solid was purified using a silica gel column (developing solvent: hexane) to obtain the intermediate compound represented by the following formula 3 (1.8 parts, yield 37%).

[0071] [ka]

[0072] (Step 6) Synthesis of condensed polycyclic aromatic compound represented by specific example No. 5 To toluene (120 parts), 2,6-dibromoanthracene (0.5 parts) synthesized by the method described in ACS Appl. Energy Mater. 2020, 3(11), 10752, the intermediate compound represented by formula 3 obtained in step 5 (1.8 parts), and tetrakis(triphenylphosphine)palladium (0.09 parts) were added and stirred at 90 ° C for 5 hours under a nitrogen atmosphere. After the resulting reaction solution was cooled to room temperature, water (100 parts) was added and the solid was separated by filtration. The resulting solid was washed with acetone and DMF, dried, and then purified by sublimation to obtain the compound represented by No. 5 (0.43 parts, 44% yield).

[0073] [ka]

[0074] The results of EI-MS measurement of the compound represented by No. 5, a specific example obtained above, were as follows. EI-MS m / z: Calcd for C 50 H 30 O2[M + ]: 662.79. Found: 662.26

[0075] Example 6 (Preparation and Evaluation of Organic Photoelectric Conversion Device Using Compound Represented by Specific Example No. 1 Obtained in Example 1) A fused polycyclic aromatic compound represented by specific example No. 1 obtained in Example 1 was formed into a film of 85 nm thickness on ITO transparent conductive glass (manufactured by Geomatec Co., Ltd., ITO film thickness 150 nm) by resistance heating vacuum deposition. Next, a 100 nm aluminum film was formed into an electrode under vacuum to produce organic photoelectric conversion element 1 of the present invention. When a voltage of 5 V was applied to the ITO and aluminum electrodes and light irradiation was performed with a wavelength of 450 nm, the light-to-dark ratio was 640,000.

[0076] Example 7 (Preparation and Evaluation of Organic Photoelectric Conversion Device Using Compound Represented by Specific Example No. 2 Obtained in Example 2) Organic photoelectric conversion element 2 was produced in the same manner as in Example 6, except that the fused polycyclic aromatic compound represented by specific example No. 1 obtained in Example 1 was changed to the fused polycyclic aromatic compound represented by specific example No. 2 obtained in Example 2. When ITO and aluminum were used as electrodes, a voltage of 5 V was applied, and light irradiation was performed at a wavelength of 450 nm, the light-to-dark ratio was 410,000.

[0077] Example 8 (Preparation and Evaluation of Organic Photoelectric Conversion Device Using Compound Represented by No. 4, Specific Example Obtained in Example 3) Organic photoelectric conversion element 3 was produced in the same manner as in Example 6, except that the fused polycyclic aromatic compound represented by specific example No. 1 obtained in Example 1 was changed to the fused polycyclic aromatic compound represented by specific example No. 4 obtained in Example 3. When ITO and aluminum were used as electrodes, a voltage of 5 V was applied, and light irradiation was performed with a wavelength of 450 nm, the light-to-dark ratio was 310,000.

[0078] Example 9 (Preparation and Evaluation of Organic Photoelectric Conversion Device Using Compound Represented by No. 5, Specific Example Obtained in Example 4) Organic photoelectric conversion element 4 was produced in the same manner as in Example 6, except that the fused polycyclic aromatic compound represented by specific example No. 1 obtained in Example 1 was changed to the fused polycyclic aromatic compound represented by specific example No. 5 obtained in Example 4. When ITO and aluminum were used as electrodes, a voltage of 5 V was applied, and light irradiation was performed at a wavelength of 450 nm, the light-to-dark ratio was 570,000.

[0079] Comparative Example 1 (Synthesis of condensed polycyclic aromatic compound represented by the following formula R1) (Step 7) Synthesis of a condensed polycyclic aromatic compound represented by the following formula R1 DMF (100 parts), 2,6-dibromobenzo [1,2-b: 4,5-b'] dithiophene (1.2 parts) synthesized by the method described in WO2017 / 159025A1, 2-trimethylstannyl (naphtho [2,3-b] thiophene) (3.6 parts), copper (I) iodide (0.17 parts), tetrakis (triphenylphosphine) palladium (0.20 parts) was added and stirred at 80 ° C. for 5 hours under a nitrogen atmosphere. After the resulting reaction solution was cooled to room temperature, water (100 parts) was added and the solid was separated by filtration. The resulting solid was washed with acetone and DMF and dried, and then purified by sublimation to obtain a compound represented by the following formula R1 (1.3 parts, yield 69%).

[0080] [ka]

[0081] The results of EI-MS measurement of the compound represented by formula R1 obtained above are as follows. EI-MS m / z: Calcd for C 34 H 18 S4[M + ]: 554.76. Found: 554.12

[0082] Comparative Example 2 (Preparation and Evaluation of Organic Photoelectric Conversion Device Using Compound Represented by R1 Obtained in Comparative Example 1) An organic photoelectric conversion element R1D was produced in the same manner as in Example 6, except that the fused polycyclic aromatic compound represented by specific example No. 1 obtained in Example 1 was changed to the fused polycyclic aromatic compound represented by formula R1 obtained in Comparative Example 1. When ITO and aluminum were used as electrodes, a voltage of 5 V was applied, and light irradiation was performed at a wavelength of 450 nm, the light-to-dark ratio was 2,100.

[0083] Comparative Example 3 (Preparation and Evaluation of Organic Photoelectric Conversion Device Using Compound Represented by Formula R2 Below) An organic photoelectric conversion element R2D was produced in the same manner as in Example 6, except that the fused polycyclic aromatic compound represented by specific example No. 1 obtained in Example 1 was changed to a fused polycyclic aromatic compound represented by the following formula R2. An attempt was made to apply a voltage of 5 V using ITO and aluminum as electrodes, but the voltage resistance was low and the brightness ratio could not be measured.

[0084] [ka]

[0085] The organic photoelectric conversion element using the fused polycyclic aromatic compound represented by formula (1) of the present invention has an absorption band in the blue light region around 450 nm and exhibits a large light-to-dark current ratio, and therefore can be used as an organic photoelectric conversion element for blue light, an organic imaging element, a material thereof, etc. [Explanation of symbols]

[0086] (Figure 1) 1 Insulation section 2 Upper electrode 3 Electron Blocking Layer 4 Photoelectric conversion layer 5. Hole-blocking layer 6 Lower electrode 7. Insulating substrate or other photoelectric conversion element

Claims

1. General formula (1) 【Chemistry 1】 (In formula (1), each X independently represents an oxygen atom, a sulfur atom, or a selenium atom; R １ ~R １２ each independently represents a hydrogen atom or a residue obtained by removing one hydrogen atom from an aromatic compound. A condensed polycyclic aromatic compound represented by the formula:

2. 2. The condensed polycyclic aromatic compound according to claim 1, wherein each X is independently an oxygen atom or a sulfur atom.

3. R １ ~R １２ 3. The condensed polycyclic aromatic compound according to claim 1, wherein each of the groups independently represents a hydrogen atom or a residue obtained by removing one hydrogen atom from an aromatic hydrocarbon compound.

4. R ３ ~R ６ and R ９ ~R １２ The condensed polycyclic aromatic compound according to any one of claims 1 to 3, wherein is a hydrogen atom.

5. R ２ and R ８ The condensed polycyclic aromatic compound according to claim 4, wherein is a hydrogen atom.

6. R １ and R ７ The condensed polycyclic aromatic compound according to claim 5, wherein each of the groups independently represents a hydrogen atom, a phenyl group, a biphenyl group, or a naphthyl group.

7. R １ and R ７ The condensed polycyclic aromatic compound according to claim 6 , wherein

8. A material for an organic photoelectric conversion element, comprising the fused polycyclic aromatic compound according to claim 1 .

9. An organic thin film comprising the fused polycyclic aromatic compound according to claim 1 .

10. An organic photoelectric conversion element comprising the organic thin film according to claim 9 .

11. An organic photoelectric conversion element comprising the organic thin film according to claim 9 in a photoelectric conversion layer.

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