Photoelectric conversion element for imaging element and photoelectric conversion element material for imaging element

Abstract

Provided is a photoelectric conversion element for an imaging element that reduces dark current and has excellent responsiveness. A photoelectric conversion element (100) for an imaging element according to the present disclosure comprises a first electrode (1), a second electrode (6), a photoelectric conversion layer (3), an electron blocking layer (4), and a hole transport promoting layer (5). The electron blocking layer (4) contains a compound represented by formula (1).　

Description

Photoelectric conversion elements for image sensors and materials for photoelectric conversion elements for image sensors

[0001] The present invention relates to a photoelectric conversion element for an image sensor and a material for a photoelectric conversion element for an image sensor.

[0002] In recent years, the development of organic photoelectric elements has been anticipated as photoelectric elements for image sensors. For example, Patent Document 1 discloses a material for an imaging photoelectric element consisting of a specific aromatic amine compound.

[0003] International Publication No. 2023 / 286816

[0004] Image sensors require reduced dark current and improved responsiveness, necessitating further development of photoelectric conversion elements for image sensors.

[0005] One aspect of the present invention aims to realize a photoelectric conversion element for an image sensor that has reduced dark current and excellent responsiveness.

[0006] To solve the aforementioned problems, a photoelectric conversion element for an image sensor according to one aspect of the present invention is a photoelectric conversion element for an image sensor comprising a first electrode, a second electrode, a photoelectric conversion layer, an electron blocking layer, and a hole transport promoting layer, wherein the photoelectric conversion layer is disposed between the first electrode and the second electrode, the electron blocking layer is disposed between the photoelectric conversion layer and the second electrode, the hole transport promoting layer is disposed between the electron blocking layer and the second electrode and is adjacent to the electron blocking layer, and the electron blocking layer comprises a compound represented by the following formula (1). (In formula (1), A １ ~A ３ and R １ ~R ２８are each independently selected from a hydrogen atom, a nitro group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group, a phosphoryl group, an amino group, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a bicycloalkyl group having 4 to 20 carbon atoms, a tricycloalkyl group having 5 to 20 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms, and a heteroaryl group having 3 to 30 carbon atoms, and a group formed by combining them, L １ and L ２ each independently represent a single bond, a 1,4-phenylene group, or a 4,4'-biphenylene, L １ and L ２ When is a single bond, A １ ~A ３ at least one of is an aromatic hydrocarbon group having 6 to 30 carbon atoms, a heteroaryl group having 3 to 30 carbon atoms, or a group formed by combining them, R ２１ ~R ２８ and A ３ Among two adjacent ones of, R ２２ and R ２３ or, R ２６ and R ２７ may be linked to each other to form a ring.)

[0007] Further, the material for a photoelectric conversion element for an imaging device according to one aspect of the present invention is a material for a photoelectric conversion element for an imaging device, which contains a compound represented by the following formula (2) or (3). (In formulas (2) and (3), Ar １ and Ar ２ each independently represent a 4-biphenyl group, a 1,1':4',1''-terphenyl-4-yl group, a naphthylphenyl-4-yl group, a 2-phenanthrenyl group, or a 2-triphenylene group.)

[0008] According to one aspect of the present invention, it is possible to provide a photoelectric conversion element for an imaging device, which has a reduced dark current and excellent responsiveness.

[0009] It is a cross-sectional view showing an outline of a laminated structure of a photoelectric conversion element for an imaging device including a material for a photoelectric conversion element according to one aspect of the present invention.

[0010] One aspect of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to the configurations described below, and various modifications are possible within the scope shown in this specification. Furthermore, embodiments and examples obtained by appropriately combining the technical means disclosed in the embodiments and examples, respectively, are also included in the technical scope of the present invention. In this specification, "A to B" indicates an A or greater and B or less, unless otherwise specified.

[0011] [Photoelectric conversion element for image sensor containing a compound represented by formula (1) in the electron blocking layer] A photoelectric conversion element for an image sensor according to one aspect of the present invention (hereinafter sometimes referred to as "this photoelectric conversion element") includes a first electrode, a second electrode, a photoelectric conversion layer, an electron blocking layer, and a hole transport promoting layer. The electron blocking layer contains a compound represented by the following formula (1).

[0012] In formula (1), A １ ~A ３ and R １ ~R ２８ Each is independently selected from hydrogen atoms, nitro groups, halogen atoms, alkyl halides, acyl groups, sulfonyl groups, phosphoryl groups, amino groups, C1-C20 alkyl groups, C2-C20 alkenyl groups, C3-C20 cycloalkyl groups, C4-C20 bicycloalkyl groups, C5-C20 tricycloalkyl groups, C1-C10 alkoxy groups, C6-C30 aromatic hydrocarbon groups, and C3-C30 heteroaryl groups, as well as combinations thereof, L １ and L ２ Each of these independently represents a single bond, a 1,4-phenylene group, or a 4,4'-biphenylene group, L １ and L ２ If it is a single bond, A １ ~A ３ At least one of them is an aromatic hydrocarbon group having 6 to 30 carbon atoms, a heteroaryl group having 3 to 30 carbon atoms, or a group combining the two. ２１ ~R ２８ and A３ Of these, two adjacent ones, R ２２ and R ２３ , or R ２６ and R ２７ These may be connected to each other to form a ring.

[0013] The C1-C20 alkyl group may be a linear alkyl group or a branched alkyl group. Examples of C1-C20 alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-eicosyl group, and the like. In the alkyl group, the number of carbon atoms is preferably 1 to 10, and more preferably 1 to 6.

[0014] The C2-C20 alkenyl group may be a linear alkenyl group, a branched alkenyl group, or a cyclic alkenyl group. Examples of C2-C20 alkenyl groups include vinyl, allyl, propenyl, isopropenyl, butenyl, isobutenyl, pentenyl, isopentenyl, hexenyl, isohexenyl, heptenyl, octenyl, cyclopropenyl, cyclobutenyl, cyclopentenyl, cyclohexenyl, cycloheptanyl, and cyclooctenyl groups. In the alkenyl group, the number of carbon atoms is preferably 1-10, and more preferably 1-6.

[0015] Examples of the cycloalkyl groups having 3 to 20 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, and cyclodecyl groups. In these cycloalkyl groups, the number of carbon atoms is preferably 3 to 10, and more preferably 3 to 6.

[0016] Examples of the bicycloalkyl groups having 4 to 20 carbon atoms include bicyclobutyl, bicyclopentyl, bicyclohexyl, bicycloheptyl, bicyclooctyl, bicyclononyl, and bicyclodecyl groups. In these bicycloalkyl groups, the number of carbon atoms is preferably 4 to 15, and more preferably 4 to 10.

[0017] Examples of the tricycloalkyl group having 5 to 20 carbon atoms include the adamantyl group. In this tricycloalkyl group, the number of carbon atoms is preferably 5 to 15, and more preferably 10 to 15.

[0018] The alkoxy group having 1 to 10 carbon atoms may be a linear alkoxy group, a branched alkoxy group, or a cyclic alkoxy group. Examples of alkoxy groups having 1 to 10 carbon atoms include methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, n-pentyloxy group, n-hexyloxy group, n-heptyloxy group, n-octyloxy group, n-nonyloxy group, n-decyloxy group, cyclopropyloxy group, cyclobutyloxy group, cyclopentyloxy group, cyclohexyloxy group, cycloheptyloxy group, cyclooctyloxy group, cyclononyloxy group, and cyclodecyloxy group. In the alkoxy group, the number of carbon atoms is preferably 1 to 8, and more preferably 1 to 6.

[0019] Examples of the aforementioned aromatic hydrocarbon group having 6 to 30 carbon atoms include phenyl group, naphthyl group, biphenyl group, terphenyl group, anthracenyl group, phenantrenyl group, triphenylenyl group, and the like. In this aromatic hydrocarbon group, the number of carbon atoms is preferably 6 to 24, and more preferably 6 to 18.

[0020] Examples of the heteroaryl group having 3 to 30 carbon atoms include thiophenyl, furanyl, pyrrolyl, furyl, thienyl, pyrazolyl, imidazolyl, triazilyl, triazolyl, tetrazolyl, oxazolyl, thiazolyl, benzothiazolyl, oxadiazolyl, thiadiazolyl, pyridyl, bipyridyl, pyridadinyl, pyrimidinyl, pyrazinyl, indolyl, and quinolyl groups. In the heteroaryl group, the number of carbon atoms is preferably 3 to 25, and more preferably 3 to 17.

[0021] R ２１ ~R ２８ and A ３ Of these, two adjacent ones, R ２２ and R ２３ , or R ２６ and R ２７ These may be linked together to form rings such as naphthylene, phenanthrene, triphenylene, fluorenyl, dibenzofuranyl, carbazolyl, and dibenzothiophenyl. ２１ ~R ２８ and A ３ Of these, two adjacent ones, R ２２ and R ２３ , or R ２６ and R ２７ It contains a benzene ring to which it is bonded.

[0022] A １ ~A ３ Preferably, at least one of them is an aromatic hydrocarbon group having 6 to 12 carbon atoms, A ３ It is more preferable that the group is an aromatic hydrocarbon group having 6 to 12 carbon atoms.

[0023] In terms of heat resistance, R １ ~R ２０ Preferably, all of these are hydrogen atoms.

[0024] In terms of heat resistance, R ２１ ~R ２８ and A ３Each is independently a hydrogen atom or an aromatic hydrocarbon group having 6 to 12 carbon atoms, or a hydrogen atom, an alkenyl group having 2 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 12 carbon atoms, R ２１ ~R ２８ and A ３ Of these, two adjacent ones, R ２２ and R ２３ , or R ２６ and R ２７ However, it is preferable that they are connected to each other to form a ring.

[0025] In terms of ease of manufacture, L １ and L ２ It is preferable that they are the same, L １ and L ２ It is more preferable that each of these represents a single bond or a 1,4-phenylene group.

[0026] <Preferred Specific Examples of Compounds Represented by Formula (1)> The following are preferred specific examples (A001 to A049) of compounds represented by formula (1), but are not limited to these.

[0027]

[0028] This photoelectric conversion element exhibits excellent responsiveness due to the inclusion of a compound represented by formula (1) in its electron blocking layer, which reduces dark current.

[0029] [Photoelectric element material for image sensor containing a compound represented by formula (2) or (3)] A photoelectric element material for an image sensor according to one aspect of the present invention contains a compound represented by formula (2) or (3). The photoelectric element material may be a material consisting of a compound represented by formula (2) or (3).

[0030] In equations (2) and (3), Ar １ and Ar ２ Each of these independently represents a 4-biphenyl group, a 1,1':4',1''-terphenyl-4-yl group, a naphthylphenyl-4-yl group, a 2-phenantrenyl group, or a 2-triphenylene group.

[0031] A photoelectric conversion element material for an image sensor containing a compound represented by formula (2) or (3) provides the image sensor with excellent responsiveness and reduced dark current. Therefore, this photoelectric conversion element material can be used, for example, as a material for the photoelectric conversion layer in an image sensor, or as a material for the electron blocking layer in the image sensor.

[0032] <Regarding HOMO Levels> For photoelectric conversion elements, it may be necessary to rapidly transfer the charge generated in the photoelectric conversion layer in order to improve dark current and response speed. For rapid charge transfer, it is preferable that the HOMO levels of the p-type semiconductor material in the photoelectric conversion layer and the material used in the electron block layer are close. The HOMO level of the electron block layer, as a quantum calculation value obtained by density functional theory (DFT) as described later, is preferably -5.5 eV or higher, and more preferably -4.0 eV or lower. More preferably -5.00 eV or higher and -4.5 eV or lower. The LUMO level of the electron block layer is not limited, but it may be -2.0 eV or higher, and preferably -1.6 eV or higher.

[0033] The HOMO level of a photoelectric conversion element material containing a compound represented by formula (1), more preferably a compound represented by formula (2) or (3), is not particularly limited, but from the viewpoint of compatibility with image sensors, a HOMO level of -5.5 eV or higher is preferred, and -5.0 eV or higher is more preferred.

[0034] In a photoelectric conversion element according to one aspect of the present invention, the HOMO level and LUMO level of the material for the photoelectric conversion element are numerical values ​​calculated by quantum chemical calculations, and the optimization of the molecular structure and the calculation of the HOMO level and LUMO level can be obtained using density functional theory (DFT) with calculation conditions of the B3LYP functional and 6-31G(d) basis function using a Gaussian program.

[0035] <Regarding the glass transition temperature> The glass transition temperature of a photoelectric conversion element material containing the compound represented by formula (1), more preferably the compound represented by formula (2) or (3), is not particularly limited. However, from the viewpoint of compatibility with image sensors, i.e., photoelectric conversion elements for image sensors, it is preferable that the glass transition temperature be 155°C or higher, and more preferably 160°C or higher. This glass transition temperature is a value obtained from differential scanning calorimetry.

[0036] The differential scanning calorimeter and test conditions are as follows: Differential scanning calorimeter model: Hitachi High-Tech DSC702; Operating conditions: The glass transition temperature was determined from the peak obtained after two scans under the conditions of heating rate of 10°C / min and temperature range of 40°C to 380°C.

[0037] <Regarding Amorphous Properties> In one aspect of the present invention, the material for a photoelectric conversion element as an image sensor preferably has a vapor-deposited film that forms an amorphous layer. If the vapor-deposited film is a crystalline layer, the interface with adjacent layers will not be uniform, which can lead to defects in the element.

[0038] There are no particular limitations on how to determine whether a deposited film is an amorphous layer or not, but it can be determined by visual inspection to see if crystallization is present or by XRD measurement of the deposited film, where no sharp diffraction peaks are observed.

[0039] [Configuration of the photoelectric conversion element for the image sensor] In the photoelectric conversion element for the image sensor, the photoelectric conversion layer is located between the first electrode and the second electrode. The electron blocking layer is located between the photoelectric conversion layer and the second electrode. The hole transport enhancement layer is located between the electron blocking layer and the second electrode, and is also adjacent to the electron blocking layer. In this specification, when A is located between B and C, it does not prevent the presence of other members other than A between B and C.

[0040] The configuration of the photoelectric conversion elements for the image sensor is not particularly limited, but for example, the configuration shown in Figure 1 can be cited. Figure 1 is a schematic cross-sectional view showing an example of a stacked configuration of photoelectric conversion elements for an image sensor.

[0041] The image sensor 100 comprises a first electrode 1, a hole blocking layer 2, a photoelectric conversion layer 3, an electron blocking layer 4, a hole transport enhancement layer 5, and a second electrode 6 in this order. However, some of these layers may be omitted, or other layers may be added. Of the above layers, the hole blocking layer 2, the photoelectric conversion layer 3, the electron blocking layer 4, and the hole transport enhancement layer 5 constitute the organic layer 10.

[0042] The image sensor 100 shown in Figure 1 may specifically be an imaging photoelectric conversion element. Light enters the image sensor 100 from below the transparent first electrode 1 and is received by the photoelectric conversion layer 3, which is a light-receiving layer. The direction of light incidence is not particularly limited; the second electrode 6 may be transparent, and light may be incident from the second electrode 6.

[0043] The image sensor 100, due to the difference in carrier density in each layer, or the difference in work function between the first electrode 1 and the second electrode 6, causes electrons to move to the first electrode 1 and holes to the second electrode 6 from the charge (holes and electrons) generated by light reception in the photoelectric conversion layer 3. Alternatively, charge can be moved by applying a voltage between the first electrode 1 and the second electrode 6. Thus, the first electrode 1 acts as an electron collection electrode, and the second electrode 6 acts as a hole collection electrode.

[0044] Each layer may be replaced with another layer having a different name or function, as needed. Examples of layers with different names or functions include an electron transport layer as an alternative name for a hole blocking layer, a hole transport layer as an alternative name for an electron blocking layer, a hole injection layer as an alternative name for a hole transport enhancement layer, a work function adjustment layer, and so on.

[0045] Note that in Figure 1, the substrate provided on the lower surface of the first electrode 1 is omitted. There are no particular limitations on the substrate here, and examples include a glass plate, a quartz plate, a plastic plate, etc. Also, in the configuration where light is incident from the substrate side, the substrate is transparent to the wavelength of light. Note that the substrate may be provided on the side of the second electrode 6. The above layers will be described below. The above layers will be described below.

[0046] [Layer containing material for photoelectric conversion element] An image sensor, which is one embodiment of a photoelectric conversion element, may contain a compound represented by formula (1), (2), or (3) above in one or more layers selected from the group consisting of a photoelectric conversion layer and a layer between the photoelectric conversion layer and a second electrode. In the example configuration shown in Figure 1, the image sensor 100 contains a material for photoelectric conversion element in at least one layer selected from the group consisting of an electron block layer 4 and a photoelectric conversion layer 3. In an image sensor according to one embodiment of the present invention, it is preferable that the electron block layer 4 contains a material for photoelectric conversion element. This has the effect of rapidly moving the necessary charge while controlling the reverse movement of electrons.

[0047] The compounds represented by formulas (1), (2), or (3) described above may be included in multiple layers of the photoelectric conversion element.

[0048] The following describes an imaging photoelectric conversion element 100 in which the electron block layer 4 contains a material for photoelectric conversion elements.

[0049] [First electrode 1] A first electrode 1 is provided on the substrate.

[0050] In the case of an image sensor configured such that light passes through the first electrode 1 and is incident on the photoelectric conversion layer 3, the first electrode 1 should be made of a transparent material that allows the light to pass through or substantially allows the light to pass through.

[0051] The transparent material used for the lower electrode, which is the first electrode 1, is not particularly limited, but examples include indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide, aluminum-doped tin oxide, magnesium-indium oxide, nickel-tungsten oxide, other metal oxides, metal nitrides such as gallium nitride, metal selenides such as zinc selenide, and metal sulfides such as zinc sulfide.

[0052] Furthermore, if the image sensor 100 is configured such that light enters the photoelectric conversion layer 3 only from the second electrode 6 side, the light transmission characteristics of the first electrode 1 are not important. Therefore, examples of materials that can be used for the first electrode 1 in this case include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, silver, gold, magnesium / silver mixture, aluminum, magnesium / aluminum mixture, magnesium / indium mixture, and aluminum / aluminum oxide (Al ２ O ３ Examples include mixtures, lithium / aluminum mixtures, iridium, molybdenum, palladium, platinum, and rare earth metals.

[0053] [Hole Blocking Layer 2] A hole blocking layer 2 is provided between the first electrode 1 and the photoelectric conversion layer 3, which is a light-receiving layer and will be described later.

[0054] The hole blocking layer 2 has the role of transporting electrons generated in the photoelectric conversion layer 3 to the first electrode 1, and blocking the movement of holes from the photoelectric conversion layer 3 to the first electrode 1, which is the destination for electron transport. Depending on the application, it may also have the role of blocking hole injection from the first electrode 1.

[0055] The hole blocking layer 2 may contain a conventionally known hole blocking material (electron transport material). Conventionally known hole-blocking materials (electron transport materials) include, for example, bis(8-hydroxyquinolinate)manganese, tris(8-hydroxyquinolinate)aluminum, tris(2-methyl-8-hydroxyquinolinate)aluminum, BCP(2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), Bphen(4,7-diphenyl-1,10-phenanthroline), BAlq(bis(2-methyl-8-quinolinolate)-4-(phenylphenolate)aluminum), 4,6-bis(3,5-di(pyridine-4-yl)phenyl)-2-methylpyrimidine, N,N'-diphenyl-1,4,5,8-naphthalenetetracarboxylic acid diimide, and N,N'-di(4-pyridyl)-1,4,5,8-naphthalenetetracarboxylic acid diimide.

[0056] The hole blocking layer 2 may be a single-layer structure made of one or more materials, or it may be a laminated structure made of multiple layers of the same or different compositions. The hole blocking layer (electron transport layer) 2 may be a two-layer structure including, for example, a layer made of a material specialized for hole blocking and adjacent to the photoelectric conversion layer 3, and a layer made of a material specialized for electron transport and adjacent to the first electrode 1.

[0057] [Photoelectric Conversion Layer 3] A photoelectric conversion layer 3, which is a light-receiving layer, is provided between the hole blocking layer 2 and the electron blocking layer 4, which will be described later. The material for the photoelectric conversion layer 3 is a material that has a photoelectric conversion function.

[0058] The photoelectric conversion layer 3 may be a single-layer structure made of one or more materials, or a laminated structure made of multiple layers of the same or different compositions. In particular, to increase the photoelectric conversion efficiency, it is preferable that the photoelectric conversion layer 3 consists of layers containing at least two types of materials (organic components). Materials used in the photoelectric conversion layer 3 include n-type semiconductors and p-type semiconductors. The n-type semiconductor is an acceptor-type organic semiconductor, and compounds that readily accept electrons and have high electron transport properties are used. The p-type semiconductor is a donor-type organic semiconductor, and compounds that readily donate electrons and have high hole transport properties are used. When multiple materials are used in the photoelectric conversion layer 3, possible combinations include, for example, an n-type semiconductor and a p-type semiconductor, an n-type semiconductor and a compound with lower acceptor properties than the n-type semiconductor, or a p-type semiconductor and a compound with lower donor properties than the p-type semiconductor. Each material may be one type, or two or more materials may be used. The photoelectric conversion layer 3 may also contain a dye compound that is excellent at absorbing specific light. The dye compound may be a compound with lower acceptor properties than the n-type semiconductor, or a compound with lower donor properties than the p-type semiconductor. In terms of increasing photoelectric conversion efficiency, it is desirable that the photoelectric conversion layer 3 further contains a dye compound in addition to the n-type and p-type semiconductors. Examples of compounds to be included in the photoelectric conversion layer 3 include coumarin and its derivatives, quinacridone and its derivatives, phthalocyanine and its derivatives, fullerene and its derivatives, azole derivatives such as imidazole, thiazole, thiadiazole, oxazole, oxadiazole, and triazole, naphthalenetetracarboxylic acid diimide, and hole transport materials. Among these, it is preferable that the photoelectric conversion layer 3 contains fullerene and two compounds selected from the group consisting of phthalocyanine and its derivatives and hole transport materials, and it is even more preferable that it contains fullerene, phthalocyanine derivatives, and hole transport materials. The photoelectric conversion layer 3 made of these materials may be formed by pre-mixing the powders and then depositing them, or by co-depositing them in any proportion.

[0059] Specific examples of coumarin derivatives include coumarin 6 and coumarin 30. Specific examples of quinacridone derivatives include N,N-dimethylquinacridone. Specific examples of phthalocyanine derivatives include boron subphthalocyanine chloride, boron subnaphthalocyanine chloride (SubNC), F6-SubPC-OC6F5, and Cl6-SubPC-OC6.

[0060] Specific examples of fullerenes and their derivatives include

[60] fullerene,

[70] fullerene, and [6,6]-phenyl-C61-methyl butyrate (

[60] PCBM).

[0061] The hole transport material may be any known hole transport material. Examples of hole transport materials include aromatic tertiary amine compounds, naphthalene compounds, anthracene compounds, tetracene compounds, pentacene compounds, phenanthrene compounds, pyrene compounds, perylene compounds, fluorene compounds, carbazole compounds, indole compounds, pyrrole compounds, picene compounds, thiophene compounds, benzotrifuran compounds, benzotrithiophene compounds, naphthodithiophene compounds, naphthiothiophene compounds, benzodithiophene compounds, benzothiophene compounds, naphthobisbenzothiophene compounds, crisenodithiophene compounds, benzothienobenzothiophene compounds, indolocarbazole compounds, and the like. Among these, fluorene compounds, naphthodithiophene compounds, naphthothienothiophene compounds, benzodifuran compounds, benzothiophene compounds, naphthobisbenzothiophene compounds, crisenodithiophene compounds, benzothienobenzothiophene compounds, and indolocarbazole compounds are preferred, with fluorene compounds, crisenodithiophene compounds, benzothienobenzothiophene compounds, and indolocarbazole compounds being more preferred.

[0062] Specific examples of hole transport materials include 9,9'-(9,9'-spirobi[9H-fluorene]-2,7'-diyl)bis[9H-carbazole], 2,7-diphenyl[1]benzothieno[3,2-b][1]benzothiophene (DiPh-BTBT), benzo[1,2-b:3,4-b':5,6-b'']trifuran compounds, benzo[1,2-b:3,4-b':5,6-b'']trithiophene compounds, naphtho[1,2-b:5,6-b']dithiophene, and naphtho[2,3-b]naphtho[2' Examples include [3':4,5]thieno[2,3-d]thiophene, benzo[1,2-b:4,5-b']difuran, benzo[1,2-b:4,5-b']dithiophene, benzo[1,2-b:4,5-b']bis[1]benzothiophene, naphtho[1,2-b:5,6-b']bis[1]benzothiophene, criseno[1,2-b:8,7-b']dithiophene, [1]benzothieno[3,2-b][1]benzothiophene, and the following compounds (ic-1), (ic-2), and (ic-3).

[0063]

[0064] Furthermore, the material for the photoelectric conversion element is not limited to being contained only in the photoelectric conversion layer. For example, the material for the photoelectric conversion element may also be contained in a layer adjacent to the photoelectric conversion layer 3 (hole block layer 2 or electron block layer 4).

[0065] In terms of increasing photoelectric conversion efficiency, it is preferable that the photoelectric conversion layer 3 includes a layer containing fullerene.

[0066] [Electron Blocking Layer 4] An electron blocking layer 4 is provided between the photoelectric conversion layer 3 and the hole transport enhancement layer 5.

[0067] The electron blocking layer 4 has the role of transporting holes generated in the photoelectric conversion layer 3 from the photoelectric conversion layer 3 to the second electrode 6, and blocking the movement of electrons generated in the photoelectric conversion layer 3 towards the second electrode 6. Depending on the application, it may also have the role of blocking electron injection from the second electrode 6.

[0068] The electron blocking layer 4 may be a single-layer structure made of one or more materials, or it may be a laminated structure made of multiple layers of the same or different compositions. For example, it may be a two-layer structure including a layer adjacent to the photoelectric conversion layer 3 made of a material specialized for electron blocking, and a layer adjacent to the hole transport promotion layer 5 made of a material specialized for hole transport.

[0069] The electron blocking layer 4 uses a compound represented by formula (1), (2), or (3) described above. In addition, it may also contain a conventionally known hole transport material. Preferred compounds and specific examples of conventionally known hole transport materials are the same as those described in the section on the photoelectric conversion layer 3.

[0070] [Hole Transport Promotion Layer 5] A hole transport promotion layer 5 is provided between the electron blocking layer 4 and the second electrode 6, which will be described later. The hole transport promotion layer 5 is provided to promote hole transport from the electron blocking layer 4 to the second electrode 6. The promotion of hole transport is brought about by the hole transport material changing the internal electric field through interaction with the surrounding material. In addition, when the second electrode 6 is formed by the sputtering method, the hole transport promotion layer 5 plays a role in reducing damage to the organic layer (e.g., the electron blocking layer 4) during sputtering.

[0071] The promotion of hole transport by the hole transport-enhancing layer depends on its interaction with the hole transport material, and this interaction strength varies depending on the strength of the interaction between the two materials. It is expected that the compound represented by formulas (1), (2), or (3) above will have a stronger interaction with the highly acceptor compound used in the hole transport-enhancing layer as its conjugation length increases, thereby promoting carrier transfer between the hole transport layer and the hole transport-enhancing layer.

[0072] The hole transport-promoting layer 5 may be a known material, for example, naphthalene-1,4,5,8-tetracarboxylic dianhydride (NTCDA) or its derivatives, or aromatic compounds having a cyano group such as 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HATCN).

[0073] [Second electrode 6] A second electrode 6 is provided on the hole transport promoting layer 5.

[0074] The material for the second electrode 6 includes sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, and aluminum / aluminum oxide (Al ２ O ３ Examples include mixtures, indium, lithium / aluminum mixtures, silver, gold, molybdenum, palladium, platinum, rare earth metals, etc. In the case of a photoelectric conversion element for an image sensor in which light is incident on the photoelectric conversion layer 3 from the second electrode 6 side, the material constituting the second electrode 6 may be, for example, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide, aluminum-doped tin oxide, magnesium-indium oxide, nickel-tungsten oxide, other metal oxides, metal nitrides such as gallium nitride, metal selenides such as zinc selenide, metal sulfides such as zinc sulfide, etc.

[0075] [Method for forming each layer] Each layer, excluding the first electrode 1 and the second electrode 6 described above, can be formed by thinning the material of each layer (along with binder resin and other materials and solvents as needed) using known methods such as vacuum deposition, spin coating, casting, or the LB (Langmuir-Blodgett method).

[0076] There are no particular restrictions on the thickness of each layer formed in this way, and it can be selected as appropriate depending on the situation, but it is usually in the range of 5 nm to 5 μm.

[0077] The first electrode 1, which is the lower electrode, and the second electrode 6, which is the upper electrode, can be formed by thinning the electrode material using methods such as vapor deposition or sputtering. A pattern may be formed through a mask of a desired shape during vapor deposition or sputtering, or a pattern of a desired shape may be formed by photolithography after the thin film has been formed by vapor deposition or sputtering.

[0078] The film thickness of the first electrode 1 and the second electrode 6 is preferably 1 μm or less, and more preferably 10 nm to 200 nm.

[0079] An image sensor equipped with a photoelectric conversion element according to one aspect of the present invention can be applied, for example, to image sensors in digital cameras and digital video cameras, and to image sensors built into mobile phones and the like.

[0080] [Summary] The photoelectric conversion element for an image sensor according to embodiment 1 of the present invention is a photoelectric conversion element for an image sensor comprising a first electrode, a second electrode, a photoelectric conversion layer, an electron blocking layer, and a hole transport promoting layer, wherein the photoelectric conversion layer is disposed between the first electrode and the second electrode, the electron blocking layer is disposed between the photoelectric conversion layer and the second electrode, the hole transport promoting layer is disposed between the electron blocking layer and the second electrode and is adjacent to the electron blocking layer, and the electron blocking layer contains a compound represented by the following formula (1). (In formula (1), A １ ~A ３ and R １ ~R ２８ Each is independently selected from hydrogen atoms, nitro groups, halogen atoms, alkyl halides, acyl groups, sulfonyl groups, phosphoryl groups, amino groups, C1-C20 alkyl groups, C2-C20 alkenyl groups, C3-C20 cycloalkyl groups, C4-C20 bicycloalkyl groups, C5-C20 tricycloalkyl groups, C1-C10 alkoxy groups, C6-C30 aromatic hydrocarbon groups, and C3-C30 heteroaryl groups, as well as combinations thereof, L １ and L ２ Each of these independently represents a single bond, a 1,4-phenylene group, or a 4,4'-biphenylene group, L １ and L ２ If it is a single bond, A １ ~A ３ At least one of them is an aromatic hydrocarbon group having 6 to 30 carbon atoms, a heteroaryl group having 3 to 30 carbon atoms, or a group combining the two. ２１ ~R２８ and A ３ Among two adjacent ones of them, R ２２ and R ２３ , or R ２６ and R ２７ may be connected to each other to form a ring. )

[0081] The photoelectric conversion element for an image pickup device according to Embodiment 2 of the present invention is, in the above Embodiment 1, R １ to R ２０ is preferably a hydrogen atom.

[0082] The photoelectric conversion element for an image pickup device according to Embodiment 3 of the present invention is, in the above Embodiment 1 or 2, A １ to A ３ at least one of which is preferably an aromatic hydrocarbon group having 6 to 12 carbon atoms.

[0083] The photoelectric conversion element for an image pickup device according to Embodiment 4 of the present invention is, in any one of the above Embodiments 1 to 3, R ２１ to R ２８ and A ３ are each independently a hydrogen atom or an aromatic hydrocarbon group having 6 to 12 carbon atoms, or a hydrogen atom, an alkenyl group having 2 to 20 carbon atoms or an aromatic hydrocarbon group having 6 to 12 carbon atoms, and R ２１ to R ２８ and A ３ Among two adjacent ones of them, R ２２ and R ２３ or R ２６ and R ２７ are preferably connected to each other to form a ring.

[0084] The photoelectric conversion element for an image pickup device according to Embodiment 5 of the present invention is, in any one of the above Embodiments 1 to 4, L １ and L ２ are the same and preferably represent a single bond or a 1,4-phenylene group.

[0085] The photoelectric conversion element for an image pickup device according to Embodiment 6 of the present invention is the photoelectric conversion element for an image pickup device according to claim 1, which comprises a layer containing fullerene in the photoelectric conversion layer, in any one of the above Embodiments 1 to 5.

[0086] The photoelectric conversion element material for an image sensor according to embodiment 7 of the present invention includes a compound represented by the following formula (2) or (3). (In equations (2) and (3), Ar １ and Ar ２ Each of these independently represents a 4-biphenyl group, a 1,1':4',1''-terphenyl-4-yl group, a naphthylphenyl-4-yl group, a 2-phenantrenyl group, or a 2-triphenylene group.

[0087] In the embodiment 8 of the present invention, the material for the photoelectric conversion element for the image sensor is preferably the material for the electron block layer in embodiment 7.

[0088] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0089] The present invention will be described in more detail below based on examples, but the present invention is not to be limited in any way by these examples.

[0090] [Synthesis Example 1] Synthesis of Compound A001

[0091] Under an argon stream, in a 200 mL two-necked flask, [1,1':4',1''-terphenyl]-4-amine (1.96 g, 8.00 mmol), 2-bromotriphenylene (5.41 g, 17.6 mmol), and NaO2 were added. ｔBu (2.31 g, 24.0 mmol), palladium acetate (53.9 mg, 240 μmol), a xylene solution of 25 wt% tritert-butylphosphine (388 mg, 480 μmol), and xylene (80 mL) were added and heated and stirred at 140°C for 4 hours. After cooling to room temperature, the mixture was quenched with water, and then hexane was added to crystallize and the solid was recovered. The obtained solid was dissolved in toluene solution at 100°C, activated carbon was added and stirred, and then the activated carbon was removed using Celite. After concentrating the filtrate, recrystallization was performed in a mixed solvent of toluene and ethanol to obtain 4.38 g (6.28 mmol, yield 78%) of the white solid (compound A001).

[0092] The identification of the compound is １ This was performed using H-NMR measurement. １ H-NMR (DMSO-d ６ ) δ (ppm): 8.79 (dd, J = 9.2Hz, 5.2Hz, 6H), 8.69-8.72 (m, 2H), 8.50 (d, J = 2.4Hz, 2H), 8.36 (d, J =7.6Hz, 2H), 7.64-7.72 (m, 10H), 7.50-7.56 (m, 4H), 7.45 (t, J = 7.6Hz, 2H), 7.32-7.35 (m, 3H)

[0093] [Synthesis Reference Example - 1] Synthesis of N-(4-chlorophenyl)-N-2-triphenylenyl-2-triphenyleneamine

[0094] Under an argon stream, in a 200 mL two-necked flask, add 1-chloro-4-iodobenzene (1.31 g, 5.51 mmol), N-2-triphenylenyl-2-triphenyleneamine (2.35 g, 5.01 mmol), and NaO2. ｔBu (626 mg, 6.51 mmol), palladium acetate (22.7 mg, 101 μmol), a xylene solution of 25% by weight of tritert-butylphosphine (162 mg, 202 μmol), and xylene (50 mL) were added and the mixture was heated and stirred at 110°C for 4 hours. After cooling to room temperature and quenching with water, the crystallized solid was collected. The obtained solid was dissolved in toluene solution at 110°C, activated carbon was added and stirred, and then the activated carbon was removed using Celite. After concentrating the filtrate, recrystallization was performed in a mixed solvent of toluene and ethanol to obtain 2.37 g (4.09 mmol, yield 82%) of a white solid of N-(4-chlorophenyl)-N-2-triphenylenyl-2-triphenyleneamine.

[0095] The identification of the compound is １ This was performed using H-NMR measurement. １ H-NMR (CDCl ３ ) δ (ppm): 8.65-8.63 (m, 4H), 8.59-8.57 (m, 4H), 8.44 (d, J = 2.3Hz, 2H), 8.30 (d, J = 7. 6Hz, 2H), 7.68-7.60 (m, 6H), 7.54-7.48 (m, 4H), 7.32-7.24 (m, 3H), 7.19-7.14 (m, 1H)

[0096] [Synthesis Example 2] Synthesis of Compound A003

[0097] Under an argon stream, 4,4,5,5-tetramethyl-2-(2-phenantrenyl)-1,3,2-dioxaborolane (0.66 g, 2.17 mmol), N-(4-chlorophenyl)-N-2-triphenylenyl-2-triphenyleneamine (1.05 g, 1.81 mmol), 2 M aqueous potassium phosphate solution (1.35 mL, 2.70 mmol), palladium acetate (8.60 mg, 38.3 μmol), XPhos (35.9 mg, 75.0 mmol), and 1,4-dioxane (20 mL) were added to a 200 mL two-necked flask and heated and stirred at 60°C for 20 hours. After cooling to room temperature and quenching with water, the crystallized solid was collected. The obtained solid was dissolved in chlorobenzene at 140°C, activated carbon was added and stirred, and then the activated carbon was removed using Celite. After concentrating the filtrate, recrystallization with toluene and chlorobenzene yielded 517 mg (0.72 mmol, 40% yield) of a pale yellow solid of compound A003.

[0098] The identification of the compound is １ This was performed using H-NMR measurement. １ H-NMR (CDCl ３ ) δ (ppm): 8.76 (d, J = 8.8 Hz, 1H), 8.71 (d, J = 8.2 Hz, 1H), 8.67-8.59 (m, 8H), 8.54 (d, J = 2.2 Hz, 2H), 8.35 (d, J = 7.6 Hz, 2H), 8.16 (d, J = 2.0 Hz, 1H), 7.98 ( dd, J=8.0Hz, 2.0Hz, 1H), 7.91 (d, J=6.6Hz, 1H), 7.83-7.76 (m, 4H), 7.70-7 .58 (m, 10H), 7.52 (td, J=8.0Hz, 1.1Hz, 2H), 7.45 (dt, J=8.7Hz, 2.0Hz, 2H)

[0099] [Synthesis Example 3] Synthesis of Compound A006

[0100] Under an argon stream, in a 200 mL two-necked flask, add 2-(4-bromophenyl)triphenylene (959 mg, 2.50 mmol), N-2-triphenylenyl-2-triphenyleneamine (1.17 g, 2.50 mmol), and NaO2. ｔBu (317 mg, 3.30 mmol), palladium acetate (11.5 mg, 51.2 μmol), a xylene solution of 25 wt% tritert-butylphosphine (18.9 mg, 102 μmol), and xylene (25 mL) were added and the mixture was heated and stirred at 140°C for 4 hours. After cooling to room temperature and quenching with water, hexane was added and the crystallized solid was collected. The obtained solid was dissolved in chlorobenzene at 140°C, activated carbon was added and stirred, and then the activated carbon was removed using Celite. After concentrating the filtrate, recrystallization with chlorobenzene was performed to obtain 1.75 g (2.27 mmol, yield 91%) of a pale yellow solid of (compound A006).

[0101] The identification of the compound is １ This was performed using H-NMR measurement. １ H-NMR (CDCl ３ ) δ (ppm): 8.92 (d, J = 1.8 Hz, 1H), 8.80-8.78 (m, 1H), 8.74 (d, J = 8.7Hz, 1H), 8.70-8.60 (m, 11H), 8.56 (d, J = 2.2Hz, 2H) , 8.37 (d, J=7.7Hz, 2H), 7.97 (dd, J=8.0Hz, 1.4Hz, 1H), 7.83 (d, J=8.6Hz, 2H), 7.71-7.60 (m, 12H), 7.55-7.47 (m, 4H)

[0102] [Synthesis Example 4] Synthesis of Compound A009

[0103] Under an argon stream, [1,1':4',1''-terphenyl]-4-boronic acid (0.59 g, 2.16 mmol), N-(4-chlorophenyl)-N-2-triphenylenyl-2-triphenyleneamine (1.04 g, 1.79 mmol), 2 M aqueous potassium phosphate solution (1.35 mL, 2.70 mmol), palladium acetate (8.10 mg, 36.1 μmol), XPhos (35.3 mg, 74.0 mmol), and 1,4-dioxane (20 mL) were added to a 200 mL two-necked flask and heated and stirred at 100 °C for 20 hours. After cooling to room temperature and quenching with water, the crystallized solid was collected. The obtained solid was dissolved in chlorobenzene at 140 °C, activated carbon was added and stirred, and then the activated carbon was removed using Celite. After concentrating the filtrate, recrystallization with chlorobenzene yielded 993 mg (6.28 mmol, yield 74%) of a white solid (compound A009). The compound was identified as follows: １ This was performed using H-NMR measurement. １ H-NMR (CDCl ３ ) δ (ppm): 8.66-8.59 (m, 8H), 8.52 (d, J = 2.3Hz, 2H), 8.34 (d, J = 7.8Hz, 2H), 7.76-7.35 (m, 27H)

[0104] [Synthesis Example 5] Synthesis of Compound A017

[0105] Under an argon stream, 2-triphenyleneboronic acid (2.00 g, 7.30 mmol), 4,4'-dibromo-4''-phenyltriphenylamine (1.68 g, 3.50 mmol), 2 M potassium carbonate aqueous solution (2.63 mL, 5.26 mmol), tetrakistriphenylphosphine palladium (0) (167 mg, 144 μmol), toluene (35 mL), and 1-butanol (3.5 mL) were added to a 200 mL two-necked flask and heated and stirred at 100 °C for 16 hours. After cooling to room temperature and quenching with water, hexane was added and the crystallized solid was collected. The obtained solid was dissolved in chlorobenzene at 140 °C, activated carbon was added and stirred, and then the activated carbon was removed using Celite. After concentrating the filtrate, recrystallization with chlorobenzene yielded 1.35 g (1.74 mmol, 50% yield) of a pale yellow solid of (compound A017).

[0106] The identification of the compound is １ This was performed using H-NMR measurement. １ H-NMR (CDCl ３ ) δ (ppm): 8.88 (d, J = 1.7Hz, 2H), 8.79-8.67 (m, 10H), 7.93 (dd, J = 8.0Hz, 1.8Hz, 2H), 7.78 (d, J = 8.7Hz, 4H), 7.70-7.58 (m, 12H), 7.46 (t, J = 7.4Hz, 2H), 7.40-7.33 (m, 7H)

[0107] [Synthesis Example 6] Synthesis of Compound A021

[0108] Under an argon stream, in a 100 mL two-necked flask, add 2-(4-bromophenyl)triphenylene (1.97 g, 5.13 mmol), 4-(naphthalene-2-yl)phenylamine (544 mg, 2.48 mmol), and NaO2. ｔBu (578 mg, 6.01 mmol), palladium acetate (11.6 mg, 51.7 μmol), a xylene solution of 25 wt% tritert-butylphosphine (18.9 mg, 103 μmol), and xylene (25 mL) were added and heated and stirred at 140°C for 30 hours. After cooling to room temperature and quenching with water, toluene was added and the crystallized solid was collected. The obtained solid was dissolved in chlorobenzene at 140°C, activated carbon was added and stirred, and then the activated carbon was removed using Celite. After concentrating the filtrate, recrystallization with chlorobenzene was performed to obtain 1.44 g (1.75 mmol, yield 70%) of a pale yellow solid of (compound A021).

[0109] The identification of the compound is １ This was performed using H-NMR measurement. １ H-NMR (CDCl ３ ) δ (ppm): 8.89 (dd, J=1.6Hz, 2H), 8.80-8.67 (m, 10H), 8.08 (m, 1H), 7.96-7.87 (m, 5H), 7.81-7.79 (m, 5H), 7.74-7.66 (m, 10H), 7.54-7.47 (m, 2H), 7.42-7.36 (m, 6H)

[0110] [Synthesis Comparison Example 1] Synthesis of Comparative Compound X1

[0111] Comparative compound X1 was synthesized with reference to synthesis examples 1 to 4 of the aforementioned Patent Document 1. The identification of the compound was １ This was performed using H-NMR measurement. １ H-NMR (DMSO-d ６ ) δ (ppm): 8.80-8.85 (m, 6H), 8.75 (d, J = 8.8Hz, 2H), 8.54 (d, J = 2.4Hz, 2H), 8.40 (d, 8.0H) z, 2H), 7.65-7.84 (m, 14H), 7.55-7.60 (m, 4H), 7.49 (t, J=7.6Hz, 2H), 7.36-7.40 (m, 3H)

[0112] [Synthesis Comparative Example 2] Synthesis of Comparative Compound X2

[0113] Comparative compound X2 was synthesized with reference to synthesis examples 1 to 4 of Patent Document 1. The identification of the compound was１ This was performed using H-NMR measurement. １ H-NMR (DMSO-d ６ ) δ (ppm): 8.78-8.82 (m, 6H), 8.71 (d, J = 7.6Hz, 2H), 8.56 (d, J = 2.4Hz, 2H), 8.39 (d, J = 7.6Hz, 2H), 7.82 (s, 1H), 7.52-7.72 (m, 17H), 7.47 (t, J=7.8Hz, 1H), 7.30-7.36 (m, 4H)

[0114] [Synthesis Comparison Example 3] Synthesis of Comparative Compound X3

[0115] Under an argon stream, in a 200 mL two-necked flask, add 4-chloro-1,1':4',1'':4'',1''''-quarterphenyl (1.53 g, 4.50 mmol), bis(dibenzo(b,d)furan-4-yl)amine (1.73 g, 4.95 mmol), and NaO2. ｔ Bu (0.649 g, 6.75 mmol), palladium acetate (30.3 mg, 135 μmol), SPhos (111 mg, 270 μmol), and xylene (150 mL) were added and the mixture was heated and stirred at 140°C for 2 hours. After cooling to room temperature and quenching with water, hexane was added to crystallize the solid, which was then collected. The obtained solid was dissolved in a chlorobenzene solution at 140°C, activated carbon was added and stirred, and then the activated carbon was removed using Celite. After concentrating the filtrate, recrystallization was performed in a mixed solvent of chlorobenzene and butanol to obtain 0.970 g (1.50 mmol, yield 33%) of compound X3 as a white solid.

[0116] The identification of the compound is １ This was performed using H-NMR measurement. １ H-NMR (DMSO-d ６ ) δ (ppm): 7.72 (d, J=7.6Hz, 2H), 7.67 (dd, J=6.0Hz, 3.2Hz, 2H), 7.46-7.57 (m, 10H), 7.37 (d, J=9.2Hz, 2H), 7.09-7.24 (m, 13H), 6.79 (d, J=8.4Hz, 2H)

[0117] [Synthesis Comparative Example 4] Synthesis of Comparative Compound X4

[0118] Under an argon stream, 2-triphenyleneboronic acid (2.00 g, 7.36 mmol), 4,4'-dibromotriphenylamine (1.41 g, 3.51 mmol), 2 M potassium carbonate aqueous solution (2.63 mL, 5.26 mmol), tetrakistriphenylphosphine palladium (0) (167 mg, 144 μmol), toluene (35 mL), and 1-butanol (3.5 mL) were added to a 200 mL two-necked flask and heated and stirred at 100 °C for 20 hours. After cooling to room temperature and quenching with water, hexane was added and the crystallized solid was collected. The obtained solid was dissolved in chlorobenzene at 140 °C, activated carbon was added and stirred, and then the activated carbon was removed using Celite. After concentrating the filtrate, recrystallization with chlorobenzene was performed to obtain 1.36 g (1.95 mmol, yield 56%) of a pale yellow solid of compound X4.

[0119] The identification of the compound is １ This was performed using H-NMR measurement. １ H-NMR (CDCl ３ ) δ (ppm): 8.87 (d, J = 1.7Hz, 2H), 8.78-8.67 (m, 10H), 7.92 (dd, J = 1.8Hz, 8.0Hz, 2H ), 7.77-7.75 (m, 4H), 7.72-7.65 (m, 8H), 7.38-7.24 (m, 8H), 7.12 (t, J=7.3Hz, 1H)

[0120] <Glass Transition Temperature (Tg)> The glass transition temperatures of the compounds obtained in Synthesis Examples 1 to 6 and comparative compounds 1 to 4 were measured using a differential scanning calorimeter (Hitachi High-Tech DSC702) with an aluminum pan at a sweep rate of 10°C / min. The obtained glass transition temperature results are summarized in Table 1.

[0121]

[0122] <Example of Element - 1 (See Figure 1)> As shown in Figure 1, an image sensor 100 was fabricated as a photoelectric conversion element having a laminated structure consisting of a first electrode 1, a hole blocking layer 2, a photoelectric conversion layer 3, an electron blocking layer 4, a hole transport promoting layer 5, and a second electrode 6, and the dark current and responsiveness of the image sensor were evaluated.

[0123] (Preparation of the first electrode 1) As a substrate on which the first electrode was mounted, a glass substrate with a transparent ITO electrode was prepared, on which a 2 mm wide indium-tin (ITO) film (thickness 110 nm) was patterned in stripes. Next, this substrate was cleaned with isopropyl alcohol and then surface-treated by ozone ultraviolet cleaning.

[0124] (Preparation for vacuum deposition) After cleaning and surface treatment, each layer was deposited using the vacuum deposition method on the substrate to form a laminated structure.

[0125] First, the glass substrate is introduced into the vacuum deposition chamber, and 7.0 × 10 －５ The pressure was reduced to Pa. Then, each layer was fabricated according to the deposition conditions for each layer, in the following order.

[0126] (Preparation of Hole Block Layer 2) 4,6-bis(3,5-di(pyridine-4-yl)phenyl)-2-methylpyrimidine, purified by sublimation, was deposited at a rate of 0.10 nm / second to a thickness of 10 nm to prepare Hole Block Layer 2.

[0127] (Fabrication of photoelectric conversion layer (light-receiving layer) 3) The photoelectric conversion layer 3 was fabricated by depositing Ph-BTBT, F6-SubPc-OC6F5, and fullerene (C60) at a deposition rate ratio of 4:4:2 to a thickness of 200 nm. The deposition rate was 0.15 nm / second.

[0128] (Fabrication of electron blocking layer 4) Compound A001 obtained in Synthesis Example-1 was deposited as a 10 nm film at a rate of 0.10 nm / second to fabricate electron blocking layer 4.

[0129] (Preparation of hole transport-promoting layer 5) Compound 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HATCN) was deposited at a rate of 0.10 nm / second to a thickness of 10 nm to prepare hole transport-promoting layer 5.

[0130] (Fabrication of the second electrode 6) Finally, a metal mask was positioned perpendicular to the ITO stripes on the substrate, and the second electrode 6, which is the upper electrode, was deposited. Specifically, gold was deposited at a rate of 0.1 nm / second to a thickness of 80 nm to fabricate the second electrode 6, which is the upper electrode.

[0131] As a result, the area is 4 mm² as shown in Figure 1. ２ A photoelectric conversion element 100 for imaging was fabricated. The film thickness of each element was measured using a stylus-type film thickness gauge (DEKTAK, Bruker).

[0132] Furthermore, this element was sealed in a nitrogen atmosphere glove box with an oxygen and moisture concentration of 1 ppm or less. The sealing was performed using bisphenol F type epoxy resin (manufactured by Nagase ChemteX Corporation) to seal the glass sealing cap and the film-deposited substrate (element).

[0133] The dark current and response time were evaluated when a voltage of 2.6V was applied to the image sensor fabricated as described above. Dark current was measured using a Keithley 2636B source measure unit. Response time was measured by irradiating the sensor with a light pulse and measuring the time it took for the current value to return to its pre-irradiation state.

[0134] Note that the dark current and response time are relative values, with the results from Comparative Example 1 set as the baseline value (1.0). A lower dark current value indicates better performance, and a shorter response time indicates better performance. The obtained measurement results are shown in Table 2.

[0135] <Element Examples 2 to 6 and Element Comparative Examples 1 to 4> In Element Example 1, instead of compound A001 obtained in Synthesis Example 1, compounds A003, A006, A009, A017, A021, comparative compound X1, comparative compound X2, comparative compound X3, and comparative compound X4 were used in order, respectively. Otherwise, an imaging photoelectric conversion element was fabricated and evaluated in the same manner as in Element Example 1. The obtained measurement results are shown in Table 2.

[0136]

[0137] From a comparison of Element Examples 1 to 6 and Element Comparative Examples 1, 2, and 4, it was found that for the triarylamine compound used in the electron blocking layer, the length of the conjugated system of all three arylamine structures is p-biphenyl or longer, and the length of one or more of these conjugated systems is p-terphenyl or longer, which reduces the dark current and improves responsiveness.

[0138] From a comparison of Element Examples 1 to 6 and Element Comparative Example 3, it was found that the dark current is significantly reduced by forming an electron blocking layer using a compound having at least two triphenylene structures.

[0139] Based on the results in Table 2, when forming an electron blocking layer using a triarylamine compound represented by formula (1), (2), or (3), which has (i) a conjugated system length of p-biphenyl or longer, (ii) a conjugated system length of at least one p-terphenyl group or longer, and (iii) at least two triphenylene structures, the dark current was reduced and the responsiveness was further improved compared to when the layer was formed using the comparative compound.

[0140] An image sensor equipped with a photoelectric conversion element according to one aspect of the present invention can be applied, for example, to image sensors in digital cameras and digital video cameras, image sensors built into mobile phones and the like, and image input devices in driver assistance systems.

[0141] 1. First electrode 2. Hole blocking layer 3. Photoelectric conversion layer (light receiving layer) 4. Electron blocking layer 5. Hole transport enhancement layer 6. Second electrode 10. Organic layer 100. Image sensor (photoelectric conversion element)

Claims

1. A photoelectric conversion element for an imaging device, comprising a first electrode, a second electrode, a photoelectric conversion layer, an electron blocking layer, and a hole transport promoting layer, wherein the photoelectric conversion layer is disposed between the first electrode and the second electrode, the electron blocking layer is disposed between the photoelectric conversion layer and the second electrode, the hole transport promoting layer is disposed between the electron blocking layer and the second electrode and is adjacent to the electron blocking layer, and the electron blocking layer contains a compound represented by the following formula (1). (In formula (1), １ A ３ to A １ and R ２８ to R １ are each independently selected from a hydrogen atom, a nitro group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group, a phosphoryl group, an amino group, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a bicycloalkyl group having 4 to 20 carbon atoms, a tricycloalkyl group having 5 to 20 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms, and a heteroaryl group having 3 to 30 carbon atoms, and a group formed by combining them, L ２ and L １ each independently represent a single bond, a 1,4-phenylene group, or 4,4'-biphenylene, and when L ２ and L １ are single bonds, at least one of A ３ to A ２１ is an aromatic hydrocarbon group having 6 to 30 carbon atoms, a heteroaryl group having 3 to 30 carbon atoms, or a group formed by combining them, and two adjacent ones among R ２８ and A ３ , R ２２ and R ２３ or R ２６ and R ２７ may be connected to each other to form a ring.) 2. R １ ~R ２０ A photoelectric conversion element for an image sensor according to claim 1, wherein is a hydrogen atom.

3. A １ ~A ３ The photoelectric conversion element for an image sensor according to claim 1, wherein at least one of the elements is an aromatic hydrocarbon group having 6 to 12 carbon atoms.

4. R ２１ ~R ２８ and A ３ However, each is independently a hydrogen atom or an aromatic hydrocarbon group having 6 to 12 carbon atoms, or a hydrogen atom, an alkenyl group having 2 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 12 carbon atoms, R ２１ ~R ２８ and A ３ Of these, two adjacent ones, R ２２ and R ２３ or R ２６ and R ２７ The photoelectric conversion element for an image sensor according to claim 1, which may be connected to each other to form a ring.

5. L １ and L ２ The photoelectric conversion element for an image sensor according to claim 1, wherein the two are identical and represent a single bond or a 1,4-phenylene group.

6. The photoelectric conversion element for an image sensor according to claim 1, wherein the photoelectric conversion layer comprises a layer containing fullerene.

7. A material for a photoelectric element for an image sensor, comprising a compound represented by the following formula (2) or (3). (In equations (2) and (3), Ar １ and Ar ２ Each of these independently represents a 4-biphenyl group, a 1,1':4',1''-terphenyl-4-yl group, a naphthylphenyl-4-yl group, a 2-phenantrenyl group, or a 2-triphenylene group.

8. A material for an image sensor photoelectric conversion element according to claim 7, which is a material for an electron blocking layer.

Images