Photodetector and image sensor

Abstract

To provide a photodetector with reduced dark current. [Solution] A photodetector having a first electrode layer 11, a photoelectric conversion layer 13, and a second electrode layer 12 in that order, an electron transport layer 21 located between the first electrode layer 11 and the photoelectric conversion layer 13, and a hole transport layer 22 located between the photoelectric conversion layer 13 and the second electrode layer 12, wherein the photoelectric conversion layer 13 contains quantum dots, the electron transport layer 21 contains an n-type organic semiconductor, the glass transition temperature (Tg) is 140°C or higher, and the water contact angle is 25 degrees or more and 75 degrees or less.

Description

[Technical Field]

[0001] This invention relates to a photodetector and an image sensor. [Background technology]

[0002] In recent years, photodetectors capable of detecting light in the infrared region have been attracting attention in areas such as smartphones, surveillance cameras, and in-vehicle cameras. Conventionally, silicon photodiodes, which use silicon wafers as the material for the photoelectric conversion layer, have been used as photodetectors in image sensors and other applications. However, silicon photodiodes have low sensitivity in the infrared region with wavelengths above 900 nm. Furthermore, semiconductor materials such as InGaAs and Ge, known as near-infrared light receiving elements, require extremely costly manufacturing processes, including epitaxial growth to achieve high quantum efficiency and bonding with readout circuits. This has been a challenge, hindering their widespread adoption. Furthermore, research on semiconductor quantum dots has been progressing in recent years. Patent documents 1 and 2 describe photodetectors having a photoelectric conversion film containing semiconductor quantum dots. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2022 / 054736 [Patent Document 2] International Publication No. 2021 / 161941 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In recent years, with the increasing demand for improved performance in image sensors and other devices, there has been a growing need for further improvements in the various characteristics required of the photodetectors used in them. For example, one characteristic required of photodetectors is high external quantum efficiency for light of the target wavelength to be detected. Increasing external quantum efficiency can improve the accuracy of light detection by the photodetector. Furthermore, it is preferable for the photodetector element to have a low dark current. By reducing the dark current of the photodetector element, a higher signal-to-noise ratio (S / N ratio) can be obtained in the image sensor. Dark current refers to the current that flows when light is not irradiated. The present inventors investigated the photodetectors described in Patent Documents 1 and 2 and found that the dark current is relatively high for light within a specific range of wavelengths. Therefore, the object of the present invention is to provide a photodetector and an image sensor with reduced dark current. [Means for solving the problem]

[0005] According to the inventors' research, it was found that the above objective can be achieved by the following configuration, and thus the present invention was completed. The photodetector element of the present invention is It has a first electrode layer, a photoelectric conversion layer, and a second electrode layer in this order, and has an electron transport layer located between the first electrode layer and the photoelectric conversion layer, and a hole transport layer located between the photoelectric conversion layer and the second electrode layer, The aforementioned photoelectric conversion layer contains quantum dots, The electron transport layer is characterized by containing an n-type organic semiconductor, having a glass transition temperature (Tg) of 140°C or higher, and a water contact angle of 25 degrees or more and 75 degrees or less. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a photodetector and an image sensor with reduced dark current. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic cross-sectional view of the photodetector according to this embodiment. [Figure 2] This is a diagram showing an example of an imaging system using the photodetector according to this embodiment. [Figure 3] This is a diagram showing the configurations of the imaging system and the moving body according to this embodiment.

Mode for Carrying Out the Invention

[0008] Hereinafter, the present invention will be described in detail with reference to preferred embodiments.

[0009] ≪Photodetector≫ The photodetector according to this embodiment has a first electrode layer, a photoelectric conversion layer, and a second electrode layer in this order, and has an electron transport layer located between the first electrode layer and the photoelectric conversion layer, and a hole transport layer located between the photoelectric conversion layer and the second electrode layer. The photoelectric conversion layer contains quantum dots, the electron transport layer contains an n-type organic semiconductor, has a glass transition temperature (Tg) of 140 ° C or higher, and a water contact angle of 25 ° or more and 75 ° or less.

[0010] According to this embodiment, a photodetector with a low dark current can be provided. In particular, a photodetector with a reduced dark current for light having a wavelength in the short-wave near-infrared region, and a photodetector with a reduced dark current from the initial stage through long-term use can be provided. The detailed reason for obtaining such an effect is unknown, but it is presumed to be as follows.

[0011] It is known that high photoelectric conversion and electron transfer characteristics can be obtained by integrating quantum dots at high density. However, the integration of quantum dots can easily be disrupted by external influences. When quantum dots are used as the photoelectric conversion layer of a photodetector, they come into contact with other layers that have different physical properties. Furthermore, the photodetector is subjected to a heating process due to annealing during fabrication and generates heat during prolonged use, resulting in an environment with large temperature fluctuations. In such cases, differences in the physical properties of the photoelectric conversion layer containing quantum dots and the other layers in contact with it due to heat can disrupt the integration of the quantum dots, worsening the aforementioned characteristics and potentially leading to an increase in dark current.

[0012] When an electron transport layer containing an n-type organic semiconductor is placed in contact with a photoelectric conversion layer containing quantum dots, an electron transport layer with a relatively high glass transition temperature (Tg) of 140°C or higher and a contact angle of 25°C to 75°C is used. By using such an electron transport layer, the state change due to heat is small and the adhesion between layers is high, so the integrated state of the quantum dots can be maintained without disruption. As a result, the above characteristics are maintained from the initial stage to long-term use, and as a result, a low dark current can be maintained.

[0013] In this specification, the glass transition temperature (Tg) of the electron transport layer is measured using a differential scanning calorimetry analyzer "Q1000" (manufactured by TA Instruments). The temperature correction of the instrument's detection unit uses the melting points of indium and zinc, and the heat correction uses the heat of fusion of indium. Specifically, approximately 5 mg of powdered electron transport layer is accurately weighed and placed in an aluminum pan. An empty aluminum pan is used as a reference, and measurements are taken within the measurement range of 30°C to 400°C at a heating rate of 10°C / min. During this heating process, the change in specific heat is obtained. The intersection point of the differential heat curve and the midpoint of the baseline before and after the change in specific heat is defined as Tg.

[0014] Furthermore, the contact angle of water with respect to the electron transport layer surface will be determined according to the droplet method described on page 97 of "New Experimental Chemistry Course 18 - Interfaces and Colloids" edited by the Chemical Society of Japan (Maruzen, published in 1977). The contact angle will be measured using "DropMaster 701" (Kyowa Interface Science Co., Ltd.). Specifically, a 1 μL water droplet will be formed on the tip of a needle, brought into contact with the surface of the electron transport layer to create a droplet, and the measured value will be taken as the water contact angle. In this specification, the temperature during contact angle measurement will be 25°C.

[0015] The details of the photodetector element of this embodiment will be described below. Figure 1 is a schematic cross-sectional view of the photodetector element of this embodiment, showing one embodiment of a photodiode type photodetector element. The arrows in the figure represent incident light to the photodetector element. The photodetector element 1 in Figure 1 includes a first electrode layer 11, a second electrode layer 12 facing the first electrode layer 11, a photoelectric conversion layer 13 provided between the first electrode layer 11 and the second electrode layer 12, an electron transport layer 21 provided between the first electrode layer 11 and the photoelectric conversion layer 13, and a hole transport layer 22 provided between the second electrode layer 12 and the photoelectric conversion layer 13. The photodetector element 1 in Figure 1 is used such that light is incident from above the first electrode layer 11. A transparent substrate may be placed on the surface of the first electrode layer 11. Examples of transparent substrates include glass substrates, resin substrates, ceramic substrates, etc.

[0016] <First electrode layer 11> The first electrode layer 11 is preferably a transparent electrode formed of a conductive material that is substantially transparent to the wavelength of light to be detected by the photodetector. In this specification, "substantially transparent" means that the light transmittance is 50% or more, preferably 60% or more, and particularly preferably 80% or more. Examples of materials for the first electrode layer 11 include conductive metal oxides. Specific examples include tin oxide, zinc oxide, indium oxide, indium tungsten oxide, indium zinc oxide (IZO), indium tin oxide (ITO), and fluorine-doped tin oxide (FTO).

[0017] The thickness of the first electrode layer 11 is not particularly limited, but is preferably 0.01 μm or more and 100 μm or less, more preferably 0.01 μm or more and 1 μm or less, and particularly preferably 0.01 μm or more and 1 μm or less.

[0018] In this invention, the film thickness of each layer can be measured by observing the cross-section of the photodetector using a scanning electron microscope (SEM) or the like.

[0019] <Second electrode layer 12> The second electrode layer 12 is preferably composed of a metallic material containing at least one metal atom selected from Au, Pt, Ir, Pd, Cu, Pb, Sn, Zn, Ti, W, Mo, Ta, Ge, Ni, Cr, and In. By composing the second electrode layer 12 of such a metallic material, a photodetector with high external quantum efficiency and low dark current can be obtained.

[0020] The second electrode layer 12 is more preferably composed of a metallic material containing at least one metal atom selected from Au, Cu, Mo, Ni, Pd, W, Ir, Pt, and Ta, and is even more preferably composed of a metallic material containing at least one metal atom selected from Au, Pd, Ir, and Pt, because it has a large work function and is less prone to migration.

[0021] The work function of the second electrode layer 12 is preferably 4.6 eV or higher, more preferably 4.8 eV to 5.7 eV, and even more preferably 4.9 eV to 5.3 eV, for the reasons that it enhances the electron blocking properties by the hole transport layer and facilitates the collection of holes generated in the device.

[0022] The thickness of the second electrode layer 12 is not particularly limited, but is preferably 0.01 μm or more and 100 μm or less, more preferably 0.01 μm or more and 1 μm or less, and particularly preferably 0.01 μm or more and 1 μm or less.

[0023] <Photoelectric conversion layer 13> The photoelectric conversion layer 13 contains quantum dots. Preferably, the photoelectric conversion layer 13 contains an aggregate of semiconductor quantum dots containing metal atoms and ligands that coordinate to the semiconductor quantum dots. That is, preferably, the photoelectric conversion layer 13 is composed of a semiconductor film containing an aggregate of semiconductor quantum dots containing metal atoms and ligands that coordinate to the semiconductor quantum dots. Note that the aggregate of semiconductor quantum dots is a large number (for example, 1 μm) 2 This refers to a configuration in which semiconductor quantum dots (100 or more per unit area) are arranged in close proximity to each other. Furthermore, in this invention, "semiconductor" refers to a semiconductor with a resistivity of 10 -2 Ωcm or more 10 8 This refers to substances with a size of Ωcm or less.

[0024] Semiconductor quantum dots are semiconductor particles having metal atoms. In this invention, metal atoms also include semimetallic atoms, such as Si atoms. Examples of semiconductor quantum dot materials that constitute semiconductor quantum dots include nanoparticles (particles with a size of 0.5 nm or more and less than 100 nm) of general semiconductor crystals [a) group IV semiconductors, b) compound semiconductors of group IV-IV, group III-V, or group II-VI, c) compound semiconductors consisting of a combination of three or more elements from group II, group III, group IV, group V, and group VI].

[0025] The semiconductor quantum dot preferably contains at least one metal atom selected from Pb, In, Ge, Si, Cd, Zn, Hg, Al, Sn, and Ga atoms, and more preferably contains at least one metal atom selected from Pb, In, Ge, and Si atoms. It is even more preferable that it contains a Pb atom because the effects of the present invention are more easily obtained. Furthermore, lead-free In atoms are also preferred from a safety standpoint.

[0026] Specific examples of semiconductor quantum dot materials that constitute semiconductor quantum dots include semiconductor materials with relatively narrow band gaps such as PbS, PbSe, PbTe, InN, InAs, Ge, InAs, InGaAs, CuInS, CuInSe, CuInGaSe, InSb, HgTe, HgCdTe, Ag2S, Ag2Se, Ag2Te, SnS, SnSe, SnTe, Si, and InP. Among these, semiconductor quantum dots are preferably made of materials containing PbS or PbSe, and more preferably of PbS, because they efficiently convert infrared light (preferably light with a wavelength of 700 nm to 2500 nm) into electrons. Furthermore, materials containing InAs, Ag2S, or Ag2Se are preferred, and more preferably of InAs, as lead-free and safe semiconductor quantum dots that efficiently convert infrared light into electrons.

[0027] The detailed reason why semiconductor quantum dots containing PbS and InAs can be converted into electrons more efficiently in the photodetector element configuration of this embodiment is unknown. However, it is thought that this is because the interaction between the n-type organic semiconductor contained in the electron transport layer adjacent to the photoelectric conversion layer and the quantum dots is strong, and electron transfer at the interface is smooth.

[0028] A semiconductor quantum dot may be a core-shell structure material in which a semiconductor quantum dot material forms the core and the semiconductor quantum dot material is covered with a coating compound. Examples of coating compounds include ZnS, ZnSe, ZnTe, ZnCdS, CdS, and GaP.

[0029] The band gap Eg1 of the semiconductor quantum dot is preferably between 0.5 eV and 2.0 eV. If the band gap Eg1 of the semiconductor quantum dot is within the above range, it can be used as a photodetector capable of detecting light of various wavelengths depending on the application. For example, it can be used as a photodetector capable of detecting light in the infrared region. The upper limit of the band gap Eg1 of the semiconductor quantum dot is preferably 1.9 eV or less, more preferably 1.8 eV or less, and even more preferably 1.5 eV or less. The lower limit of the band gap Eg1 of the semiconductor quantum dot is preferably 0.5 eV or more.

[0030] The average particle size of the semiconductor quantum dots is preferably between 2 nm and 15 nm. The average particle size of the semiconductor quantum dots is the average of the particle sizes of 10 arbitrarily selected semiconductor quantum dots. A transmission electron microscope can be used to measure the particle size of the semiconductor quantum dots.

[0031] Generally, semiconductor quantum dots contain particles of various sizes ranging from a few nanometers to tens of nanometers. When the average particle size of semiconductor quantum dots is reduced to a size smaller than the Bohr radius of the electrons contained within them, a phenomenon occurs where the band gap of the semiconductor quantum dot changes due to the quantum size effect. If the average particle size of semiconductor quantum dots is 15 nm or less, it is easier to control the band gap using the quantum size effect.

[0032] The photoelectric conversion layer 13 of the photodetector in this embodiment preferably contains ligands that coordinate to semiconductor quantum dots. Examples of ligands include ligands containing carboxyl groups, thiol groups, amino groups, etc., and polydentate ligands containing two or more coordinating parts. The ligand may be an aromatic compound. Specific examples of ligands include aromatic compounds having thiol groups such as 1,3-benzenedithiol. The photoelectric conversion layer 13 may contain only one type of ligand, or it may contain two or more types.

[0033] <Electron transport layer 21> As shown in Figure 1, the electron transport layer 21 is provided between the first electrode layer 11 and the photoelectric conversion layer 13. The electron transport layer 21 is a layer that has the function of transporting electrons generated in the photoelectric conversion layer 13 to the electrode layer. The electron transport layer 21 is also called a hole blocking layer. The electron transport layer 21 is formed of an electron transport material that can perform this function. In the photodetector element of this embodiment, the electron transport layer 21 contains an n-type organic semiconductor as the electron transport material. Preferably, the electron transport layer 21 is a semiconductor film composed of an n-type organic semiconductor.

[0034] [n-type organic semiconductor] Examples of n-type organic semiconductors include perylenediimide derivatives, fullerene derivatives, naphthalenediimide derivatives, anthraquinone derivatives, fluorenone derivatives, phenanthrenequinone derivatives, benzimidazoperylene derivatives, benzimidazonaphthalene derivatives, diphenoquinone derivatives, and naphthoquinone derivatives. Among these, perylenediimide derivatives, naphthalenediimide derivatives, and fullerene derivatives are particularly preferred, with perylenediimide derivatives being even more preferred.

[0035] Perylenediimide derivatives can be synthesized using known synthesis methods described in, for example, the Journal of the American Chemical Society, Vol. 129, No. 49, 15259-78 (2007), and the New Journal of Chemistry, Vol. 34, No. 11, 2337-2684 (2010). They can also be synthesized by the reaction of perylenetetracarboxylic dianhydride, which is available as a reagent from companies such as Tokyo Chemical Industry Co., Ltd., Sigma-Aldrich Japan Co., Ltd., and Johnson Matthey Japan, Inc., with a monoamine derivative.

[0036] Methods for introducing polymerizable functional groups into derivatives include, for example, directly introducing polymerizable functional groups into the synthesized skeleton, introducing a structure having a polymerizable functional group or a functional group that can serve as a precursor to a polymerizable functional group (for example, using a halide of a perylenediimide derivative and employing a cross-coupling reaction using a palladium catalyst and a base, or a cross-coupling reaction using an FeCl3 catalyst and a base), and using a perylenetetracarboxylic dianhydride derivative or monoamine derivative having a polymerizable functional group or a functional group that can serve as a precursor to a polymerizable functional group as a starting material when synthesizing perylenediimide derivatives.

[0037] Naphthalene diimide derivatives can be synthesized using known synthesis methods described, for example, U.S. Patent No. 4,442,193, U.S. Patent No. 4,992,349, U.S. Patent No. 5,468,583, and in Chemistry of Materials, Vol. 19, No. 11, 2703-2705 (2007). They can also be synthesized by the reaction of naphthalenetetracarboxylic dianhydride, which is available as a reagent from companies such as Tokyo Chemical Industry Co., Ltd., Sigma-Aldrich Japan Ltd., and Johnson Matthey Japan, Inc., with a monoamine derivative.

[0038] Methods for introducing polymerizable functional groups into derivatives include, for example, directly introducing polymerizable functional groups into the synthesized skeleton, introducing structures having polymerizable functional groups or functional groups that can serve as precursors to polymerizable functional groups (for example, using a halide of a naphthalene diimide derivative as a base, for example, by using a cross-coupling reaction with a palladium catalyst and a base to introduce a functional group-containing alkyl group, or by using a cross-coupling reaction with an FeCl3 catalyst and a base to introduce a hydroxyalkyl group or carboxyl group after lithiation by reacting with an epoxy compound or CO2), and using a naphthalenetetracarboxylic dianhydride derivative or monoamine derivative having polymerizable functional groups or functional groups that can serve as precursors to polymerizable functional groups as a starting material when synthesizing naphthalene diimide derivatives.

[0039] Fullerene derivatives can be purchased as reagents from companies such as Tokyo Chemical Industry Co., Ltd., Sigma-Aldrich Japan Co., Ltd., and Johnson Matthey Japan, Inc. They can also be synthesized using methods described in, for example, International Publication No. 2010 / 101241.

[0040] n-type organic semiconductors may have polymerizable functional groups. Examples of polymerizable functional groups in n-type organic semiconductors include functional groups containing active hydrogen groups (highly reactive hydrogen atoms bonded to oxygen, sulfur, nitrogen, etc.) such as hydroxyl groups, carboxyl groups, amino groups, and thiol groups, and functional groups polymerizable with them; unsaturated hydrocarbon groups (hydrocarbon groups containing double or triple bonds as carbon-carbon bonds in the carbon skeleton) such as acryloyloxy groups and methacryloyloxy groups, and functional groups polymerizable with them; and cyclic ether groups such as epoxy groups, and functional groups polymerizable with them. Among these, hydroxyl groups, amino groups, and carboxyl groups are preferred.

[0041] The n-type organic semiconductor is preferably a compound represented by any of the following formulas (1) to (3). In formulas (1) to (3), the "group having a polymerizable functional group" may be the polymerizable functional group itself, or a group that partially contains a polymerizable functional group.

[0042] [ka]

[0043] In formula (1), R 1 , R 2 Each of these is independently selected from a group having a polymerizable functional group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted alkyl group.

[0044] R 3 ~R 10is independently selected from a group having a polymerizable functional group, a hydrogen atom, a halogen atom, a nitro group, a cyano group, a trifluoromethyl group, a hydroxyl group, a thiol group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted thiol group, a substituted or unsubstituted amino group, a substituted sulfonyl group, and a substituted sulfinyl group.

[0045]

Chemical formula

[0046] In formula (2), R 11 , R 12 is independently selected from a group having a polymerizable functional group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted alkyl group.

[0047] R 13 to R 16 is independently selected from a group having a polymerizable functional group, a hydrogen atom, a halogen atom, a nitro group, a cyano group, a trifluoromethyl group, a hydroxyl group, a thiol group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted thiol group, a substituted or unsubstituted amino group, a substituted sulfonyl group, and a substituted sulfinyl group.

[0048]

Chemical formula

[0049] In formula (3), R 21 , R 22 is a group having a polymerizable functional group.

[0050] R 23 , R 24Each of these is independently selected from substituted or unsubstituted alkyl groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted aralkyl groups, substituted or unsubstituted aryl groups, substituted or unsubstituted heteroaryl groups, and substituted or unsubstituted silyl groups.

[0051] Only one hemispherical portion of the spherical fullerene structure is shown, and the other hemispherical portion is omitted. 21 , R 23 A first substituent including and R 22 , R 24 The position in which the second substituent, including the compound, attaches to the fullerene structure is arbitrary, and the second substituent may be omitted.

[0052] The following are specific examples of n-type organic semiconductors, but the examples are not limited to these.

[0053] [Table 1]

[0054] [Table 2]

[0055] [Table 3]

[0056] [Table 4]

[0057] [Table 5]

[0058] The content of n-type organic semiconductor in the electron transport layer 21 is preferably 40% by mass or more, and more preferably 50% by mass or more, relative to the total mass of the electron transport layer 21. The electron transport layer may consist only of n-type semiconductors, or it may contain compounds in addition to n-type semiconductors. The content of such other compounds may be less than 50% by mass, 10% by mass or less, or 5% by mass or less.

[0059] [A polymer having a polymer chain containing structural units derived from n-type organic semiconductors] It is preferable for the electron transport layer 21 to contain a polymer (hereinafter sometimes simply referred to as "polymer") having polymer chains containing structural units derived from an n-type organic semiconductor, as this allows for the maintenance of high external quantum efficiency even when irradiated with light for a long period of time.

[0060] Polymers can be formed, for example, by polymerization of n-type organic semiconductors having polymerizable functional groups, or by polymerization of an n-type organic semiconductor having polymerizable functional groups, a crosslinking agent having polymerizable functional groups that can polymerize with the n-type organic semiconductor, and a resin having polymerizable functional groups that can polymerize with the crosslinking agent.

[0061] Various forms of bonding are known to be formed by the polymerization of polymerizable functional groups. Examples of bonds formed by the polymerization of polymerizable functional groups in n-type organic semiconductors include urethane bonds (-NH-CO-O-) formed by the reaction of isocyanate groups and hydroxyl groups, urea bonds formed by the reaction of isocyanate groups and amino groups, amide bonds formed by the reaction of isocyanate groups and carboxyl groups, >N-CH2-O- bonds formed by the reaction of N-methylol groups with hydroxyl or carboxyl groups, bonds formed by the addition polymerization of unsaturated hydrocarbon groups, and bonds formed by ring-opening polymerization or addition polymerization of cyclic ether groups. Among these, urethane bonds (-NH-CO-O-) and >N-CH2-O- bonds are preferred.

[0062] The polymer content in the electron transport layer is preferably 50% by mass or more, and more preferably 80% by mass or more, relative to the total mass of the electron transport layer. Furthermore, the n-type organic semiconductor content in the polymer is preferably 25% by mass or more, and more preferably 50% by mass or more, relative to the total mass of the polymer.

[0063] [A crosslinking agent having functional groups that can polymerize with n-type organic semiconductors] The crosslinking agent having polymerizable functional groups that can polymerize with n-type organic semiconductors is not particularly limited as long as it is a compound that can react with the polymerizable functional groups of the n-type organic semiconductor, but compounds having multiple polymerizable functional groups are preferred, and low molecular weight compounds or oligomers are preferred. Examples of crosslinking agents having polymerizable functional groups that can polymerize with n-type organic semiconductors include compounds containing isocyanate groups or blocked isocyanate groups, compounds containing N-methylol groups or alkyl etherified N-methylol groups, compounds containing unsaturated hydrocarbon groups, and compounds containing epoxy groups.

[0064] Compounds containing isocyanate groups or blocked isocyanate groups are preferably compounds having multiple isocyanate groups or blocked isocyanate groups. Examples include triisocyanate benzene, triisocyanate methylbenzene, triphenylmethane triisocyanate, lysine triisocyanate, as well as isocyanurate modified, biuret modified, allophanate modified, and adduct modified with trimethylolpropane or pentaerythritol.

[0065] Examples of products available for purchase include Asahi Kasei's Duranate MFK-60B and SBA-70B, and Sumika Bayer Urethane's Desmodule BL3175 and BL3475.

[0066] Compounds containing an N-methylol group or an alkyl etherified N-methylol group are preferably compounds having multiple N-methylol groups or alkyl etherified N-methylol groups. Examples include methylolated melamine, methylolated guanamine, methylolated urea derivatives, methylolated ethyleneurea derivatives, methylolated glycoluryl, and these compounds and their derivatives in which the methylol moiety is alkyl etherified.

[0067] Examples of products available for purchase include Super Melami No. 90 (manufactured by Nippon Oil & Fats Co., Ltd.), Super Beccamine(R) TD-139-60, L-105-60, L127-60, L110-60, J-820-60, G-821-60 (manufactured by DIC Corporation), Yuban 2020 (Mitsui Chemicals), Sumitex Resin M-3 (Sumitomo Chemical Industries), Nikalac MW-30, MW-3 Examples include 90, MX-750LM (manufactured by Nippon Carbide Co., Ltd.), "Super Beckamine(R) L-148-55, 13-535, L-145-60, TD-126 (manufactured by DIC Corporation), Nikalac BL-60, BX-4000 (manufactured by Nippon Carbide Co., Ltd.), Nikalac MX-280, Nikalac MX-270, Nikalac MX-290 (manufactured by Nippon Carbide Co., Ltd.), and others.

[0068] Compounds containing unsaturated hydrocarbon groups are preferably those having multiple acrylic or methacrylic groups. Examples of commercially available products include Funcryl FA-129AS and FA-731A manufactured by Hitachi Chemical Co., Ltd.

[0069] Compounds containing epoxy groups are preferably those having multiple epoxy groups. Examples of commercially available products include Epiclon 840 manufactured by DIC Corporation.

[0070] [A resin having a crosslinking agent and polymerizable functional groups] In this embodiment, the electron transport layer can also use a resin having polymerizable functional groups that can polymerize with a crosslinking agent. The resin having polymerizable functional groups that can polymerize with a crosslinking agent may also be polymerized with an n-type organic semiconductor. Preferred polymerizable functional groups in the resin having polymerizable functional groups that can polymerize with a crosslinking agent include hydroxyl groups, thiol groups, amino groups, carboxyl groups, methoxy groups, and the like. Examples of resins having polymerizable functional groups that can polymerize with a crosslinking agent include polyether polyol resins, polyester polyol resins, polyacrylic polyol resins, polyvinyl alcohol resins, polyvinyl acetal resins, polyamide resins, carboxyl group-containing resins, polyamine resins, and polythiol resins.

[0071] Examples of commercially available crosslinking agents and polymerizable functional groups include polyether polyol resins such as AQD-457 and AQD-473 from Nippon Polyurethane Industries, Ltd., and Sannix GP-400 and GP-700 from Sanyo Chemical Industries, Ltd.; polyester polyol resins such as Phthalkid W2343 from Hitachi Chemical Co., Ltd., Watersol S-118 and CD-520 from DIC Corporation, and Haridip WH-1188 from Harima Chemicals, Ltd.; and polyacrylic polyol resins such as Barnock WE-300 and WE-304 from DIC Corporation. Examples include polyvinyl alcohol-based resins such as Kuraray's Kuraray Poval PVA-203, polyvinyl acetal-based resins such as S-Rec BX-1, BM-1, KS-1, and KS-5 from Sekisui Chemical Co., Ltd., polyamide-based resins such as Trezin FS-350 from Nagase ChemteX Corporation, carboxyl group-containing resins such as Aquaric from Nippon Shokubai Co., Ltd., Finelex SG2000 from Namari Corporation, and Alphaon UC3920 and UF5080 from Toagosei Co., Ltd., polyamine resins such as Laccamide from DIC Corporation, and polythiol resins such as QE-340M from Toray Industries, Inc.

[0072] [Partial structure] The polymer preferably has a substructure in which a polymerizable functional group of any of the compounds represented by formulas (1) to (3) above serves as a bonding site with the polymerization chain, as a structural unit derived from an n-type organic semiconductor.

[0073] [Other ingredients] The electron transport layer may contain resins other than polymers (resins without polymerizable functional groups), organic particles, inorganic particles, leveling agents, etc., in order to improve film-forming properties and electrical characteristics. However, the content of these in the electron transport layer 21 is preferably 50% by mass or less, and more preferably 20% by mass or less, relative to the total mass of the electron transport layer 21.

[0074] The electron transport layer 21 may be a single layer or a multilayer film of two or more layers. When the photodetector element of this embodiment includes two or more electron transport layers, it is preferable that the electron transport layer containing an n-type organic semiconductor is located on the photoelectric conversion layer 13 side.

[0075] The thickness of the electron transport layer is preferably 10 nm to 200 nm, more preferably 20 nm to 100 nm, and even more preferably 20 nm to 50 nm.

[0076] The glass transition temperature (Tg) of the electron transport layer is preferably 140°C or higher, and more preferably 180°C or higher, due to its stability against temperature changes.

[0077] The contact angle of water in the electron transport layer is preferably 25 degrees to 75 degrees, and more preferably 30 degrees to 65 degrees, in order to ensure good adhesion with the photoelectric conversion layer.

[0078] The electron transport layer can be formed by a solution process. For example, an electron transport layer can be formed by forming a coating film of a solution containing an n-type organic semiconductor having polymerizable functional groups (a coating liquid for the electron transport layer) and then drying this coating film. After the coating film is formed, the compound having polymerizable functional groups polymerizes through a chemical reaction. Applying energy such as heat at this time is preferable because it accelerates the chemical reaction and promotes polymerization. Examples of solvents used in the coating liquid for the electron transport layer include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon solvents.

[0079] <Hole transport layer 22> As shown in Figure 1, the hole transport layer 22 is provided between the second electrode layer 12 and the photoelectric conversion layer 13. The hole transport layer is a layer that has the function of transporting holes generated in the photoelectric conversion layer to the electrode layer. The hole transport layer is also called an electron blocking layer. In the photodetector element of this embodiment, it is preferable that the hole transport layer 22 is arranged on the surface of the photoelectric conversion layer 13.

[0080] In the photodetector of this embodiment, the hole transport layer 22 preferably contains a p-type organic semiconductor. The hole transport layer 22 is preferably a semiconductor film composed of a p-type organic semiconductor. Specifically, examples include compounds represented by any of the following formulas P1 to P3.

[0081] [ka]

[0082] The hole transport layer 22 may be a single layer or a laminate of two or more layers. When the photodetector element of this embodiment includes two or more hole transport layers, it is preferable that the hole transport layer containing a p-type organic semiconductor is located on the photoelectric conversion layer 13 side.

[0083] The thickness of the hole transport layer 22 is preferably 5 nm to 100 nm, and more preferably 10 nm to 50 nm.

[0084] Image Sensor The image sensor of this embodiment includes the photodetector element of this embodiment described above. If the photodetector element of this embodiment has excellent sensitivity to light in the infrared region, it can be used particularly preferably as an infrared image sensor. The configuration of the image sensor is not particularly limited as long as it includes the photodetector element of this embodiment and functions as an image sensor.

[0085] The image sensor may include an infrared transmission filter layer. The infrared transmission filter layer preferably has low transmittance of light in the visible wavelength range, and more preferably has an average transmittance of 10% or less, 7.5% or less, and particularly preferably 5% or less for light in the wavelength range of 400 nm to 650 nm.

[0086] Examples of infrared transmission filter layers include those composed of a resin film containing a colorant. Examples of colorants include chromatic colorants such as red, green, blue, yellow, purple, and orange, as well as black colorants. Preferably, the colorant included in the infrared transmission filter layer is formed by a combination of two or more chromatic colorants to form black, or contains a black colorant. When black is formed by a combination of two or more chromatic colorants, examples of combinations of chromatic colorants include the following embodiments (C1) to (C7).

[0087] (C1) An embodiment containing a red colorant and a blue colorant. (C2) An embodiment containing a red colorant, a blue colorant, and a yellow colorant. (C3) A form containing a red colorant, a blue colorant, a yellow colorant, and a purple colorant. (C4) A form containing red pigment, blue pigment, yellow pigment, purple pigment, and green pigment. (C5) A form containing red pigment, blue pigment, yellow pigment, and green pigment. (C6) An embodiment containing a red colorant, a blue colorant, and a green colorant. (C7) An embodiment containing a yellow colorant and a purple colorant.

[0088] The above-mentioned chromatic colorants may be pigments or dyes. They may contain both pigments and dyes. The black colorant is preferably an organic black colorant. Examples of organic black colorants include bisbenzofuranone compounds, azomethine compounds, perylene compounds, and azo compounds.

[0089] The infrared transmission filter layer may further contain an infrared absorbent. By including an infrared absorbent in the infrared transmission filter layer, the wavelength of transmitted light can be shifted to a longer wavelength side. Examples of infrared absorbents include pyrrolopyrrole compounds, cyanine compounds, squarylium compounds, phthalocyanine compounds, naphthalocyanine compounds, quaterylene compounds, merocyanine compounds, crokonium compounds, oxonol compounds, iminium compounds, dithiol compounds, triarylmethane compounds, pyromethene compounds, azomethine compounds, anthraquinone compounds, dibenzofuranone compounds, dithiolene metal complexes, metal oxides, and metal borides.

[0090] The spectral characteristics of the infrared transmission filter layer can be appropriately selected depending on the application of the image sensor. For example, a filter layer that satisfies any of the spectral characteristics (1) to (5) below is an example.

[0091] (1) A filter layer in which the maximum value of the light transmittance in the thickness direction of the film in the wavelength range of 400 nm to 750 nm is 20% or less (preferably 15% or less, more preferably 10% or less), and the minimum value of the light transmittance in the thickness direction of the film in the wavelength range of 900 nm to 1500 nm is 70% or more (preferably 75% or more, more preferably 80% or more).

[0092] (2) A filter layer in which the maximum value of the light transmittance in the thickness direction of the film in the wavelength range of 400 nm to 830 nm is 20% or less (preferably 15% or less, more preferably 10% or less), and the minimum value of the light transmittance in the thickness direction of the film in the wavelength range of 1000 nm to 1500 nm is 70% or more (preferably 75% or more, more preferably 80% or more).

[0093] (3) A filter layer in which the maximum value of the light transmittance in the thickness direction of the film in the wavelength range of 400 nm to 950 nm is 20% or less (preferably 15% or less, more preferably 10% or less), and the minimum value of the light transmittance in the thickness direction of the film in the wavelength range of 1100 nm to 1500 nm is 70% or more (preferably 75% or more, more preferably 80% or more).

[0094] (4) A filter layer in which the maximum value of the light transmittance in the thickness direction of the film is 20% or less (preferably 15% or less, more preferably 10% or less) in the wavelength range of 400 nm to 1100 nm, and the minimum value in the wavelength range of 1400 nm to 1500 nm is 70% or more (preferably 75% or more, more preferably 80% or more).

[0095] (5) A filter layer in which the maximum value of the light transmittance in the thickness direction of the film is 20% or less (preferably 15% or less, more preferably 10% or less) in the wavelength range of 400 nm to 1300 nm, and the minimum value in the wavelength range of 1600 nm to 2000 nm is 70% or more (preferably 75% or more, more preferably 80% or more).

[0096] Furthermore, the infrared transmission filter can be one of the films described in Japanese Patent Publication No. 2013-077009, Japanese Patent Publication No. 2014-130173, Japanese Patent Publication No. 2014-130338, International Publication No. 2015 / 166779, International Publication No. 2016 / 178346, International Publication No. 2016 / 190162, International Publication No. 2018 / 016232, Japanese Patent Publication No. 2016-177079, Japanese Patent Publication No. 2014-130332, and International Publication No. 2016 / 027798. In addition, the infrared transmission filter may be a combination of two or more filters, or a dual bandpass filter that transmits two or more specific wavelength regions with a single filter may be used.

[0097] The image sensor may include an infrared shielding filter to improve various performance aspects, such as noise reduction. Specific examples of infrared shielding filters include those described in International Publication No. 2016 / 186050, International Publication No. 2016 / 035695, Japanese Patent No. 6248945, International Publication No. 2019 / 021767, Japanese Patent Application Publication No. 2017-067963, and Japanese Patent No. 6506529.

[0098] The image sensor may include a dielectric multilayer film. Examples of dielectric multilayer films include those in which multiple layers of high-refractive-index dielectric thin films (high-refractive-index material layers) and low-refractive-index dielectric thin films (low-refractive-index material layers) are alternately stacked. While there are no particular limitations on the number of layers of dielectric thin films in the dielectric multilayer film, 2 to 100 layers are preferred, 4 to 60 layers are more preferred, and 6 to 40 layers are even more preferred. Materials with a refractive index of 1.7 to 2.5 are preferred for forming the high-refractive-index material layers. Specific examples include Sb2O3, Sb2S3, Bi2O3, CeO, CeF3, HfO2, La2O3, Nd2O3, and Pr6O 11Examples include Sc2O, SiO, Ta2O5, TiO2, TlCl, Y2O3, ZnSe, ZnS, and ZrO2. Materials with a refractive index of 1.2 to 1.6 are preferred for forming the low refractive index layer. Specific examples include Al2O3, BiF3, CaF2, LaF3, PbCl2, PbF2, LiF, MgF2, MgO, NdF3, SiO2, Si2O3, NaF, ThO2, ThF4, and Na3AlF6. While there are no particular restrictions on the method for forming the dielectric multilayer film, examples include ion plating, vacuum deposition methods such as ion beam deposition, physical vapor deposition (PVD) methods such as sputtering, and chemical vapor deposition (CVD). The thickness of each layer of the high refractive index layer and the low refractive index layer is preferably 0.1λ to 0.5λ when the wavelength of light to be blocked is λ (nm). Specific examples of dielectric multilayer films include, for example, the dielectric multilayer films described in Japanese Patent Publication No. 2014-130344 and Japanese Patent Publication No. 2018-010296.

[0099] The dielectric multilayer film preferably has a transmission wavelength band in the infrared region (preferably a wavelength region above 700 nm, more preferably a wavelength region above 800 nm, and even more preferably a wavelength region above 900 nm). The maximum transmittance in the transmission wavelength band is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. The maximum transmittance in the light-shielding wavelength band is preferably 20% or less, more preferably 10% or less. The average transmittance in the transmission wavelength band is preferably 60% or more, more preferably 70% or more, and even more preferably 80% or more. The wavelength range of the transmission wavelength band is centered on the wavelength that shows the maximum transmittance, λ. t1 In that case, the central wavelength λ t1 Preferably, the central wavelength is ±100 nm, and the center wavelength λ t1 It is more preferable that the center wavelength be ±75 nm. t1 A more preferable value is ±50 nm.

[0100] The dielectric multilayer film may have only one transmission wavelength band (preferably a transmission wavelength band with a maximum transmittance of 90% or more), or it may have multiple transmission wavelength bands.

[0101] The image sensor may include a color separation filter layer. An example of a color separation filter layer is a filter layer containing colored pixels. Examples of colored pixels include red pixels, green pixels, blue pixels, yellow pixels, cyan pixels, and magenta pixels. The color separation filter layer may contain two or more colored pixels, or only one color. This can be appropriately selected depending on the application and purpose. For example, a filter described in International Publication No. 2019 / 039172 can be used as the color separation filter layer.

[0102] Furthermore, if the color separation filter layer includes two or more colored pixels, the colored pixels of each color may be adjacent to each other, and partitions may be provided between each colored pixel. There are no particular limitations on the material of the partitions. Examples include organic materials such as siloxane resin and fluororesin, and inorganic particles such as silica particles. The partitions may also be made of metals such as tungsten and aluminum.

[0103] When an image sensor includes an infrared transmission filter layer and a color separation filter layer, it is preferable that the color separation filter layer is located on a separate optical path from the infrared transmission filter layer. It is also preferable that the infrared transmission filter layer and the color separation filter layer are arranged in two dimensions. Two-dimensional arrangement of the infrared transmission filter layer and the color separation filter layer means that at least a portion of both lies on the same plane.

[0104] The image sensor may include intermediate layers such as a planarization layer, a base layer, and an adhesion layer, an anti-reflective coating, and a lens. As the anti-reflective coating, for example, a film made from the composition described in International Publication No. 2019 / 017280 can be used. As the lens, for example, a structure described in International Publication No. 2018 / 092600 can be used.

[0105] If the photodetector element of this embodiment has excellent sensitivity to light in the infrared wavelength range, the image sensor of this embodiment can be preferably used as an infrared image sensor. Furthermore, the image sensor of this embodiment can be preferably used to sense light with wavelengths of 900 nm to 2000 nm, and more preferably to sense light with wavelengths of 900 nm to 1600 nm.

[0106] <<Imaging device>> A photodetector according to one embodiment of the present invention may be used in an imaging device. The imaging device includes an optical system having a plurality of lenses and an image sensor that receives light transmitted through the optical system, and the image sensor has a photodetector. Specifically, the imaging device may be a digital still camera or a digital video camera.

[0107] Figure 2 shows an example of an imaging system using a photodetector according to one embodiment of the present invention. As shown in Figure 2, the imaging system 200 includes an image sensor 201, an imaging optical system 202, a CPU 210, a lens control unit 212, an image sensor control unit 214, an image processing unit 216, an aperture shutter control unit 218, a display unit 220, an operation switch 222, and a recording medium 224.

[0108] The imaging optical system 202 is an optical system for forming an optical image of a subject, and includes a lens group, an aperture 204, etc. The aperture 204 has the function of adjusting the amount of light during shooting by adjusting its aperture diameter, and also functions as a shutter for adjusting the exposure time when shooting still images. The lens group and the aperture 204 are held so as to be able to move back and forth along the optical axis, and their coordinated movement realizes a variable magnification function (zoom function) and a focus adjustment function. The imaging optical system 202 may be integrated into the imaging system, or it may be an imaging lens that can be attached to the imaging system.

[0109] An image sensor 201 is positioned in the image space of the imaging optical system 202 such that its imaging plane is located there. The image sensor 201 has a photodetector element according to one embodiment of the present invention and is composed of a CMOS sensor (pixel portion) and its peripheral circuit (peripheral circuit region). The image sensor 201 is configured as a two-dimensional single-chip color sensor by arranging pixels, each having a plurality of photoelectric conversion units, in a two-dimensional arrangement, and arranging color filters for these pixels. The image sensor 201 photoelectrically converts the subject image formed by the imaging optical system 202 and outputs it as an image signal and a focus detection signal.

[0110] The lens control unit 212 controls the forward and backward movement of the lens group of the imaging optical system 202 to perform magnification and focus adjustment, and is composed of circuits and processing units configured to realize this function. The aperture shutter control unit 218 adjusts the amount of light to be captured by changing the aperture diameter of the aperture 204 (making the aperture value variable), and is composed of circuits and processing units configured to realize this function.

[0111] The CPU 210 is an internal control unit that manages various aspects of the camera body, and includes an arithmetic unit, ROM, RAM, A / D converter, D / A converter, communication interface circuit, etc. The CPU 210 controls the operation of each part of the camera according to computer programs stored in the ROM, etc., and executes a series of shooting operations such as AF (autofocus), imaging, image processing, and recording, including detection of the focus state of the imaging optical system 202 (focus detection). The CPU 210 also functions as a signal processing unit.

[0112] The image sensor control unit 214 controls the operation of the image sensor 201 and performs A / D conversion on the signal output from the image sensor 201 and transmits it to the CPU 210. It is composed of circuits and control devices configured to realize these functions. The A / D conversion function may be provided by the image sensor 201. The image processing unit 216 generates an image signal by performing image processing such as gamma conversion and color interpolation on the A / D converted signal. It is composed of circuits and control devices configured to realize this function. The display unit 220 is a display device such as a liquid crystal display (LCD) and displays information related to the camera's shooting mode, a preview image before shooting, a confirmation image after shooting, the focus status when focus is detected, etc. The operation switches 222 consist of a power switch, a release (shooting trigger) switch, a zoom operation switch, a shooting mode selection switch, etc. The recording medium 224 is for recording captured images, etc., and may be built into the imaging system or may be a removable memory card, etc.

[0113] In this way, by configuring an imaging system 200 to which an image sensor 201 having a photodetector element according to one embodiment of the present invention is applied, a high-performance imaging system can be realized.

[0114] ≪Mobile≫ An imaging device according to one embodiment of the present invention may be used in a mobile body. The mobile body has a body on which the imaging device is installed and means for moving the body. Specific examples of mobile bodies include automobiles, aircraft, ships, and drones. By installing the imaging device on the mobile body, the surrounding environment can be imaged to support the operation of the mobile body. The body can be made of metal or carbon fiber. Polycarbonate or the like may be used as the carbon fiber. Examples of means for moving include tires, magnetic levitation, and a mechanism for vaporizing and injecting fuel.

[0115] Figures 3(A) and 3(B) show the configuration of the imaging system and moving object according to this embodiment. Figure 3(A) shows an example of an imaging system 300 related to an in-vehicle camera. The imaging system 300 has an imaging device 310. The imaging device 310 is an imaging device described in one embodiment of the present invention. The imaging system 300 has an image processing unit 312, which is an image processing device that performs image processing on a plurality of image data acquired by the imaging device 310, and a parallax acquisition unit 314, which is an image processing device that calculates parallax (phase difference of parallax images) from a plurality of image data acquired by the imaging device 310. The imaging system 300 also has a distance acquisition unit 316, which is an image processing device that calculates the distance to an object based on the calculated parallax, and a collision determination unit 318, which is an image processing device that determines whether or not there is a possibility of collision based on the calculated distance. Here, the parallax acquisition unit 314 and the distance acquisition unit 316 are examples of information acquisition means that acquire information such as distance information to an object. That is, distance information is information such as parallax, defocus amount, distance to an object. The collision determination unit 318 may use any of this distance information to determine the possibility of a collision. The various processing units described above may be implemented by specially designed hardware, or by general-purpose hardware that performs calculations based on software modules. Furthermore, the processing units may be implemented by FPGAs (Field Programmable Gate Arrays), ASICs (Application Specific Integrated Circuits), etc., or by a combination thereof.

[0116] The imaging system 300 is connected to the vehicle information acquisition device 320 and can acquire vehicle information such as vehicle speed, yaw rate, and steering angle. The imaging system 300 is also connected to a control ECU 330, which is a control device that outputs a control signal to generate braking force on the vehicle based on the judgment result of the collision judgment unit 318. In other words, the control ECU 330 is an example of a mobile body control means that controls a moving object based on distance information. The imaging system 300 is also connected to a warning device 340 that issues a warning to the driver based on the judgment result of the collision judgment unit 318. For example, if the collision judgment unit 318 determines that there is a high probability of collision, the control ECU 330 performs vehicle control to avoid a collision or mitigate damage by applying the brakes, releasing the accelerator, or suppressing engine output. The warning device 340 warns the user by sounding a warning, displaying warning information on a screen such as a car navigation system, or vibrating the seat belt or steering wheel.

[0117] In this embodiment, the imaging system 300 captures images of the area around the vehicle, for example, the front or rear. Figure 3(B) shows the imaging system 300 when capturing images of the area in front of the vehicle (imaging range 350). The vehicle information acquisition device 320 sends an instruction to the imaging system 300 to operate and perform imaging. By using an imaging device according to one embodiment of the present invention as the imaging device 310, the imaging system 300 of this embodiment can further improve the accuracy of distance measurement.

[0118] The above explanation described an example of control to prevent collisions with other vehicles, but it can also be applied to control systems that automatically follow other vehicles, or control systems that automatically stay within their lanes. Furthermore, the imaging system can be applied not only to vehicles such as automobiles, but also to mobile objects (transportation equipment) such as ships, aircraft, or industrial robots. The moving devices in mobile objects (transportation equipment) include various means of movement such as engines, motors, wheels, and propellers. In addition, it can be applied not only to mobile objects, but also to a wide range of devices that utilize object recognition, such as intelligent transportation systems (ITS). [Examples]

[0119] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited in any way by the following examples, unless it exceeds the gist of the invention. In the following descriptions of examples, "parts" refers to mass unless otherwise specified.

[0120] The following are the crosslinking agents having functional groups that can polymerize with n-type organic semiconductors and the resins having polymerizable functional groups that can polymerize with the crosslinking agents, which were used in the manufacture of the electron transport layer coating liquid.

[0121] (A) Crosslinking agents having functional groups polymerizable with n-type organic semiconductors [Table 6]

[0122] (B) Resins having polymerizable functional groups that can be polymerized with crosslinking agents [Table 7]

[0123] (Example 1) [Manufacturing of photodetectors] The glass substrate with the ITO film was cleaned, and the ITO film was used as the first electrode layer.

[0124] <Fabrication of the electron transport layer> As an n-type organic semiconductor, 6.00 parts of example compound 1-1 from Table 1, 8.20 parts of A-1 as a crosslinking agent, and 0.10 parts of B-1 and 0.10 parts of B-2 as resins were dissolved in a mixed solvent of 670 parts THF / 330 parts orthoxylene. Subsequently, the mixture was pressure filtered using an ADVANTEC Teflon® filter (product name: PF020) to produce an electron transport layer coating solution.

[0125] The obtained electron transport layer coating solution was spin-coated onto an ITO film at 2000 rpm. Then, it was heated at 180°C for 30 minutes to form an electron transport layer with a thickness of approximately 20 nm.

[0126] <Measurement of glass transition temperature> The glass transition temperature (Tg) of the electron transport layer prepared as described above was measured using a differential scanning calorimetry analyzer "Q1000" (TA Instruments). The temperature correction for the instrument's detection unit was performed using the melting points of indium and zinc, and the heat correction was performed using the heat of fusion of indium. After scraping the electron transport layer into powder, approximately 5 mg was accurately weighed and placed in an aluminum pan. An empty aluminum pan was used as a reference, and measurements were taken within the measurement range of 30°C to 400°C at a heating rate of 10°C / min. During this heating process, a change in specific heat was obtained, and the intersection point of the differential heat curve and the midpoint of the baseline before and after the specific heat change was defined as Tg.

[0127] The sample used for Tg measurement was used solely for that measurement; subsequent operations used samples prepared simultaneously using the same method but without Tg measurement.

[0128] <Measuring the contact angle> The contact angle of water with respect to the surface of the electron transport layer formed as described above was measured using "DropMaster701" (manufactured by Kyowa Interface Science Co., Ltd.). A 1 μL water droplet was formed on the tip of a needle, and the droplet was brought into contact with the surface of the electron transport layer for measurement. This measurement was repeated at three points at a distance of 5 mm or more, and the average of these measurements was taken as the contact angle at the surface of the electron transport layer.

[0129] The sample used for contact angle measurement was used solely for that measurement; subsequent operations used samples prepared simultaneously using the same method but without contact angle measurement.

[0130] <Fabrication of photoelectric conversion layer> Next, a PbS quantum dot dispersion with oleic acid coordinated to it (product name: QDot PbS Quantum Dots, oleic acid capped 1500-abs, manufactured by Quantum Solutions) was concentrated and then subjected to pressure filtration using an ADVANTEC Teflon® filter (product name: PF020).

[0131] The obtained quantum dot dispersion was dropped onto an electron transport layer and then spin-coated at 2500 rpm to obtain a quantum dot aggregate film (Step 1).

[0132] Next, a solution of 1,3-benzenedithiol propylene glycol 1-monomethyl ether 2-acetate (PGMEA) (concentration 3 mg / mL) was added dropwise as a ligand solution onto the quantum dot assembly membrane, and after standing for 30 seconds, the ligand was exchanged. Then, PEGMEA was added dropwise as a rinse solution onto the quantum dot assembly membrane while spinning at 500 rpm for 60 seconds to rinse it. Furthermore, it was spin-dried at 2500 rpm for 60 seconds. Next, a solution of PbI2 N,N-dimethylformamide (concentration 9 mg / mL) was added dropwise, and after standing for 3 minutes, PEGMEA was added dropwise as a rinse solution onto the quantum dot assembly membrane while spinning at 500 rpm for 60 seconds to rinse it. Furthermore, it was spin-dried at 2500 rpm for 60 seconds (Step 2).

[0133] The process of combining steps 1 and 2 was repeated for 6 cycles to form a 200 nm thick photoelectric conversion layer in which 1,3-benzenedithiol was coordinated as a ligand to PbS quantum dots.

[0134] <Preparation of a hole transport layer> Next, a toluene solution (concentration 10 mg / mL) of the compound (Mw20000) represented by formula (P1) was spin-coated onto the photoelectric conversion layer at 2000 rpm for 60 seconds to form a hole transport layer with a thickness of approximately 10 nm.

[0135] Next, a 15 nm thick MoO3 film was deposited on the hole transport layer using a vacuum deposition method via a metal mask, and then a 100 nm thick Au film (second electrode layer) was deposited to fabricate a photodiode-type photodetector element.

[0136] [evaluation] The dark current of the manufactured photodetector was evaluated using a semiconductor parameter analyzer (4156B, manufactured by Agilent).

[0137] First, the current-voltage characteristics (IV characteristics) were measured while sweeping the voltage from 0V to -3V without light irradiation to evaluate the dark current. Here, the current value at -1V was defined as the initial dark current. Next, after irradiating with 1550nm monochromatic light for 24 hours, the IV characteristics were measured again while sweeping the voltage from 0V to -3V without light irradiation. The current value at -1V was defined as the endurance-based dark current. The results are shown in Table 8. The initial dark current was 3.6 × 10⁻⁶. ー8 A / cm 2 The dark current after endurance is 5.5 × 10 ー8 A / cm 2 That was the case.

[0138] [Content of n-type organic semiconductors] Table 8 shows the proportion of n-type organic semiconductors in all materials constituting the electron transport layer as "content (wt%)".

[0139] (Examples 2 to 16) Except for changing the type and content of the n-type organic semiconductor mixed in the coating solution for the electron transport layer, and the type of p-type organic semiconductor used for the hole transport layer, as shown in Table 8, a photodetector element was manufactured and evaluated in the same manner as in Example 1. The results are shown in Table 8.

[0140] (Comparative Example 1) An electron transport layer coating solution was prepared in the same manner as in Example 1, except that 4.00 parts of example compound 1-1 from Table 1 were used as the n-type organic semiconductor, 5.90 parts of A-2 as the crosslinking agent, and 0.10 parts of B-1 as the resin. Using this electron transport layer coating solution, a device was fabricated and evaluated in the same manner as in Example 1. The results are shown in Table 8.

[0141] (Comparative Example 2) An electron transport layer coating solution was prepared in the same manner as in Example 1, except that 4.00 parts of the compound represented by formula (N1) in Table 1 was dissolved as an n-type organic semiconductor, 5.90 parts of A-3 as a crosslinking agent, and 0.10 parts of B-1 as a resin in a mixed solvent of 670 parts methanol and 330 parts butanol. An electron transport layer coating solution was used to create and evaluate a device in the same manner as in Example 1. The results are shown in Table 8.

[0142] [ka]

[0143] (Comparative Example 3) An electron transport layer coating solution was prepared in the same manner as in Example 1, except that 6.00 parts of the compound represented by formula (N2) in Table 1 was dissolved as an n-type organic semiconductor, 8.20 parts of A-4 as a crosslinking agent, and 0.20 parts of B-2 as a resin in a mixed solvent of 670 parts THF / 330 parts butanol. An electron transport layer coating solution was used to create and evaluate a device in the same manner as in Example 1. The results are shown in Table 8.

[0144] [ka]

[0145] (Comparative Example 4) As described in the example in Patent Document 1, a solution of 1 g zinc acetate dihydrate and 284 μl ethanolamine dissolved in 10 ml of methoxyethanol was spin-coated at 3000 rpm. The device was then prepared and evaluated in the same manner as in Example 1, except that it was heated at 200°C for 30 minutes to form a zinc oxide film (electron transport layer) with a thickness of approximately 50 nm. The results are shown in Table 8.

[0146] (Comparative Example 5) The device was constructed and evaluated in the same manner as in Example 1, except that a titanium oxide film was deposited by 20 nm sputtering to form the electron transport layer, as described in the example in Patent Document 2. The results are shown in Table 8.

[0147] [Table 8]

[0148] (Example 17) [Manufacturing of photodetectors] A photodetector element was manufactured in the same manner as in Example 1, except that the photoelectric conversion layer was fabricated using an InAs quantum dot dispersion with coordinated fatty acids (product name: QDot InAs Quantum Dots, fatty acid capped 1400-abs, manufactured by Quantum Solutions).

[0149] [evaluation] The evaluation was performed in the same manner as in Example 1, except that the monochromatic light was changed to 1400 nm monochromatic light. The results are shown in Table 9.

[0150] (Examples 18 to 21) Except for changing the type of n-type organic semiconductor mixed into the electron transport layer coating solution as shown in Table 9, a photodetector element was manufactured and evaluated in the same manner as in Example 17. The results are shown in Table 9.

[0151] (Comparative Example 6) Except for fabricating the photoelectric conversion layer in the same manner as in Example 17, the photodetector element was manufactured in the same manner as in Comparative Example 1 and evaluated in the same manner as in Example 17. The results are shown in Table 9.

[0152] (Comparative Example 7) Except for fabricating the photoelectric conversion layer in the same manner as in Example 17, the photodetector element was manufactured in the same manner as in Comparative Example 2 and evaluated in the same manner as in Example 17. The results are shown in Table 9.

[0153] (Comparative Example 8) Except for fabricating the photoelectric conversion layer in the same manner as in Example 17, the photodetector element was manufactured in the same manner as in Comparative Example 3 and evaluated in the same manner as in Example 17. The results are shown in Table 9.

[0154] [Table 9]

[0155] By using the photodetector elements obtained in the examples, an image sensor can be fabricated using a known method and incorporated into a solid-state image sensor to obtain an image sensor with good visible and infrared imaging performance.

[0156] ≪Included components≫ This embodiment includes the following configuration. (Composition 1) It has a first electrode layer, a photoelectric conversion layer, and a second electrode layer in this order, and has an electron transport layer located between the first electrode layer and the photoelectric conversion layer, and a hole transport layer located between the photoelectric conversion layer and the second electrode layer, The aforementioned photoelectric conversion layer contains quantum dots, The aforementioned electron transport layer contains an n-type organic semiconductor, has a glass transition temperature (Tg) of 140°C or higher, and has a water contact angle of 25 degrees or more and 75 degrees or less, making it a photodetector element. (Configuration 2) The photodetector according to configuration 1, characterized in that the contact angle of the water is 30 degrees or more and 65 degrees or less. (Composition 3) The photodetector element according to configuration 1 or 2, characterized in that the n-type organic semiconductor is one of a perylenediimide derivative, a naphthalenediimide derivative, or a fullerene derivative. (Composition 4) The photodetector element according to any one of configurations 1 to 3, characterized in that the n-type organic semiconductor is a compound represented by any one of formulas (1) to (3). (Composition 5) The photodetector element according to any one of configurations 1 to 4, characterized in that the electron transport layer contains a polymer having a polymer chain containing structural units derived from the n-type organic semiconductor. (Composition 6) The photodetector element according to configuration 5, characterized in that the n-type organic semiconductor is bonded to the polymerization chain via a urethane bond (-NH-CO-O-) or an >N-CH2-O- bond. (Composition 7) The photodetector element according to configuration 5, characterized in that the polymer is obtained by polymerizing or crosslinking an n-type organic semiconductor having a functional group selected from a hydroxyl group, an amino group, and a carboxyl group.

[0157] (Composition 8) The photodetector element according to configuration 5, characterized in that the polymer is a polymer of an n-type organic semiconductor having polymerizable functional groups, a crosslinking agent having polymerizable functional groups that can polymerize with the n-type organic semiconductor, and a resin having polymerizable functional groups that can polymerize with the crosslinking agent. (Composition 9) The photodetector element according to any one of configurations 1 to 8, characterized in that the electron transport layer contains a resin other than a polymer having a polymer chain containing structural units derived from the n-type organic semiconductor. (Composition 10) The photodetector element according to any one of configurations 1 to 9, characterized in that the hole transport layer contains a p-type organic semiconductor. (Composition 11) The photodetector element according to any one of configurations 1 to 10, characterized in that the quantum dot is a PbS quantum dot or an InAs quantum dot. (Composition 12) The photodetector according to any one of configurations 1 to 11, characterized in that the quantum dot has a ligand. (Composition 13) The photodetector according to configuration 12, characterized in that the ligand is an aromatic compound having a thiol group.

[0158] (Composition 14) An image sensor characterized by including a photodetector element as described in any of configurations 1 to 13. (Composition 15) An imaging device comprising an optical system having multiple lenses and an image sensor that receives light transmitted through the optical system, wherein the image sensor has a photodetector element as described in any of configurations 1 to 13. (Composition 16) A mobile body comprising a body equipped with an imaging device and a means for moving the body, wherein the imaging device is the imaging device described in configuration 15. [Explanation of symbols]

[0159] 1: Photodetector, 11: First electrode layer, 12: Second electrode layer, 13: Photoelectric conversion layer, 21: Electron transport layer, 22: Hole transport layer

Claims

1. It has a first electrode layer, a photoelectric conversion layer, and a second electrode layer in this order, and has an electron transport layer located between the first electrode layer and the photoelectric conversion layer, and a hole transport layer located between the photoelectric conversion layer and the second electrode layer, The aforementioned photoelectric conversion layer contains quantum dots, The photodetector is characterized in that the electron transport layer contains an n-type organic semiconductor, has a glass transition temperature (Tg) of 140°C or higher, and has a water contact angle of 25 degrees or more and 75 degrees or less.

2. The photodetector according to claim 1, characterized in that the water contact angle is 30 degrees or more and 65 degrees or less.

3. The photodetector element according to claim 1 or 2, characterized in that the n-type organic semiconductor is one of a perylenediimide derivative, a naphthalenediimide derivative, or a fullerene derivative.

4. The photodetector element according to claim 1 or 2, characterized in that the n-type organic semiconductor is a compound represented by any one of the following formulas (1) to (3). 【Chemistry 1】 In formula (1), R 1 , R 2 Each of these is independently selected from a group having a polymerizable functional group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted alkyl group. R 3 ~R 10 Each of these is independently selected from a group having a polymerizable functional group, a hydrogen atom, a halogen atom, a nitro group, a cyano group, a trifluoromethyl group, a hydroxyl group, a thiol group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted thiol group, a substituted or unsubstituted amino group, a substituted sulfonyl group, or a substituted sulfinyl group. 【Chemistry 2】 In formula (2), R 11 , R 12 Each of these is independently selected from a group having a polymerizable functional group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted alkyl group. R 13 ~R 16 Each of these is independently selected from a group having a polymerizable functional group, a hydrogen atom, a halogen atom, a nitro group, a cyano group, a trifluoromethyl group, a hydroxyl group, a thiol group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted thiol group, a substituted or unsubstituted amino group, a substituted sulfonyl group, or a substituted sulfinyl group. 【Transformation 3】 In formula (3), R 21 , R 22 is a group having a polymerizable functional group. R 23 , R 24 Each of these is independently selected from substituted or unsubstituted alkyl groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted aralkyl groups, substituted or unsubstituted aryl groups, substituted or unsubstituted heteroaryl groups, and substituted or unsubstituted silyl groups. Only one hemispherical portion of the spherical fullerene structure is shown, and the other hemispherical portion is omitted. 21 , R 23 A first substituent including and R 22 , R 24 The position in which the second substituent, including the compound, attaches to the fullerene structure is arbitrary, and the second substituent may be omitted.

5. The photodetector element according to claim 1 or 2, characterized in that the electron transport layer contains a polymer having a polymer chain containing structural units derived from the n-type organic semiconductor.

6. The aforementioned n-type organic semiconductor has a urethane bond (-NH-CO-O-) or >N-CH 2 The photodetector element according to claim 5, characterized in that it is bonded to the polymerization chain via an -O- bond.

7. The photodetector element according to claim 5, characterized in that the polymer is obtained by polymerizing or crosslinking an n-type organic semiconductor having a functional group selected from a hydroxyl group, an amino group, and a carboxyl group.

8. The photodetector element according to claim 5, characterized in that the polymer is a polymer of an n-type organic semiconductor having polymerizable functional groups, a crosslinking agent having polymerizable functional groups that can polymerize with the n-type organic semiconductor, and a resin having polymerizable functional groups that can polymerize with the crosslinking agent.

9. The photodetector element according to claim 1 or 2, characterized in that the electron transport layer contains a resin other than a polymer having a polymer chain containing structural units derived from the n-type organic semiconductor.

10. The photodetector element according to claim 1 or 2, characterized in that the hole transport layer contains a p-type organic semiconductor.

11. The photodetector according to claim 1 or 2, characterized in that the quantum dot is a PbS quantum dot or an InAs quantum dot.

12. The photodetector according to claim 1 or 2, characterized in that the quantum dot has a ligand.

13. The photodetector according to claim 12, characterized in that the ligand is an aromatic compound having a thiol group.

14. An image sensor characterized by including the photodetector element described in claim 1 or 2.

15. An imaging device comprising an optical system having multiple lenses and an image sensor that receives light transmitted through the optical system, wherein the image sensor has the photodetector element described in claim 1 or 2.

16. A mobile body comprising a body equipped with an imaging device and a means for moving the body, wherein the imaging device is the imaging device described in claim 15.

Images