Photodetection element, photodetection device, and electronic apparatus

Abstract

A photodetection element (10) of one embodiment of the present disclosure is provided with: a first electrode (11); a second electrode (14) disposed facing the first electrode (11); a photoelectric conversion layer (13) disposed between the first electrode (11) and the second electrode (14); and a buffer layer (12) disposed between the photoelectric conversion layer (13) and the first electrode (11) and containing a plurality of nanoparticles (120) on the surfaces of which a plurality of organic ligands are modified.

Description

Photodetector element, photodetector device, and electronic device

[0001] The present disclosure relates to a photodetector element and a photodetector device including the photodetector element.

[0002] For example, Patent Document 1 discloses a photoelectric conversion element provided with a buffer layer in which organic molecules or halogen elements are coordinated at the interface with the photoelectric conversion layer.

[0003] International Publication No. 2017 / 061174

[0004] In a photodetector device having a photodetector element including a photoelectric conversion layer and a buffer layer, it is required to reduce dark current as well as suppress lateral leakage current.

[0005] Therefore, it is desirable to provide a photodetector and electronic equipment that can suppress lateral leakage current while keeping dark current low.

[0006] An optical detection element according to one embodiment of the present disclosure includes a first electrode, a second electrode disposed opposite the first electrode, a photoelectric conversion layer disposed between the first electrode and the second electrode, and a buffer layer disposed between the photoelectric conversion layer and the first electrode and containing a plurality of nanoparticles whose surfaces are modified with a plurality of organic ligands.

[0007] The photodetector according to one embodiment of the present disclosure includes a photodetector element, and the photodetector element includes the photodetector element according to one embodiment of the present disclosure.

[0008] An electronic device according to an embodiment of the present disclosure includes a photodetector device having a photodetector element, and the photodetector element includes the photodetector element according to the embodiment of the present disclosure.

[0009] In a photodetector element according to an embodiment of the present disclosure, a photodetector device according to an embodiment of the present disclosure, and an electronic device according to an embodiment of the present disclosure, a buffer layer is formed using a plurality of nanoparticles whose surfaces are modified with a plurality of organic ligands, thereby suppressing the occurrence of defects inside the buffer layer.

[0010] FIG. 1 is a cross-sectional schematic diagram illustrating an example of a configuration of a photodetector element according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram illustrating an example of a configuration of nanoparticles constituting a buffer layer shown in FIG. 1. FIG. 3 is a schematic diagram illustrating an example of a configuration of nanoparticles constituting a photoelectric conversion layer shown in FIG. 1. FIG. 4 is a block diagram illustrating an overall configuration of a photodetector according to the present disclosure. FIG. 5 is a cross-sectional schematic diagram illustrating a configuration of each unit pixel of the photodetector shown in FIG. 4. FIG. 6 is an equivalent circuit diagram of each unit pixel of the photodetector shown in FIG. 4. FIG. 7 is a cross-sectional schematic diagram illustrating a configuration of each unit pixel of a photodetector according to a modified example of the present disclosure. FIG. 8 is a block diagram illustrating an example of a configuration of an electronic device using the photodetector shown in FIG. 4. FIG. 9A is a schematic diagram illustrating an example of an overall configuration of a photodetection system using the photodetector shown in FIG. 4. FIG. 9B is a diagram illustrating an example of a circuit configuration of the photodetection system shown in FIG. 9A. FIG. 10 is a diagram illustrating an example of a schematic configuration of an endoscopic surgery system. FIG. 11 is a block diagram illustrating an example of a functional configuration of a camera head and a CCU. FIG. 12 is a block diagram illustrating an example of a schematic configuration of a vehicle control system. Fig. 13 is an explanatory diagram showing an example of the installation positions of the vehicle outside information detection unit and the imaging unit. Fig. 14 is a flow chart explaining an example of a method for evaluating film peeling of the photodetector element shown in Fig. 1. Fig. 15 is a diagram showing the profile of current passed through the photodetector elements of Experimental Examples 14 to 17. Fig. 16 is a characteristic diagram showing the relationship between the current decay time and the energy gap in the photodetector elements of Experimental Examples 14 to 17.

[0011] An embodiment of the present disclosure will be described in detail below with reference to the drawings. The following description is one specific example of the present disclosure, and the present disclosure is not limited to the following aspects. Furthermore, the present disclosure is not limited to the arrangement, dimensions, dimensional ratios, etc. of each component shown in each drawing. The description will be given in the following order: 1. Embodiment (Example of a photodetector having a buffer layer containing nanoparticles coordinated with organic ligands) 1-1. Configuration of photodetector element 1-2. Manufacturing method of photodetector element 1-3. Configuration of photodetector element 1-4. Actions and effects 2. Modifications 3. Application examples 4. Application examples 5. Examples

[0012] 1 is a schematic diagram illustrating an example of a cross-sectional configuration of a photodetector (photodetector element 10) according to an embodiment of the present disclosure. The photodetector element 10 constitutes one pixel (unit pixel P) in a photodetector device (photodetector device 1; see FIG. 4 , for example) such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor used in electronic devices such as digital still cameras and video cameras.

[0013] The photodetector element 10 has a configuration in which a lower electrode 11, a buffer layer 12, a photoelectric conversion layer 13, and an upper electrode 14 are stacked in this order. The lower electrode 11 corresponds to a specific example of a "first electrode" according to one aspect of the present disclosure. The buffer layer 12 corresponds to a specific example of a "buffer layer" according to one aspect of the present disclosure. The photoelectric conversion layer 13 corresponds to a specific example of a "photoelectric conversion layer" according to one aspect of the present disclosure. The upper electrode 14 corresponds to a specific example of a "second electrode" according to one aspect of the present disclosure.

[0014] In the photodetector element 10, electrons or holes among carriers generated by photoelectric conversion in the photoelectric conversion layer 13 are read out as signal charges from the lower electrode 11 side.

[0015] The lower electrode 11 is made of, for example, a light-transmitting conductive film. The material of the lower electrode 11 is, for example, InP doped with tin (Sn). ２ O ３ Examples of the material for the lower electrode 11 include indium tin oxide (ITO), crystalline ITO, and amorphous ITO. In addition to the above, the material for the lower electrode 11 may also include tin oxide (SnO ２)-based materials, for example, ATO with Sb added as a dopant, and FTO with fluorine added as a dopant. Furthermore, zinc oxide (ZnO) or a zinc oxide-based material with a dopant added thereto may be used as the constituent material of the lower electrode 11. Examples of ZnO-based materials include aluminum zinc oxide (AZO) with aluminum (Al) added as a dopant, gallium zinc oxide (GZO) with gallium (Ga) added, boron zinc oxide with boron (B) added, and indium zinc oxide (IZO) with indium (In) added. Furthermore, zinc oxide with indium and gallium added as dopants (IGZO, In-GaZnO ４ In addition, the lower electrode 11 may be made of CuI, InSbO ４ , ZnMgO, CuInO ２ , MgIN ２ O ４ , CdO, ZnSnO ３ or TiO ２ Alternatively, spinel oxides or YbFe ２ O ４ Oxides having such a structure may also be used.

[0016] Furthermore, when optical transparency is not required for the lower electrode 11, a single metal or alloy having a low work function (e.g., φ=3.5 eV to 4.5 eV) can be used. Specific examples include alkali metals (e.g., lithium (Li), sodium (Na), and potassium (K)) and their fluorides or oxides, and alkaline earth metals (e.g., magnesium (Mg) and calcium (Ca)) and their fluorides or oxides. Other examples include aluminum (Al), Al—Si—Cu alloys, zinc (Zn), tin (Sn), thallium (Tl), Na—K alloys, Al—Li alloys, Mg—Ag alloys, and rare earth metals such as In and ytterbium (Yb), as well as alloys thereof.

[0017] Furthermore, examples of materials constituting the lower electrode 11 include metals such as platinum (Pt), gold (Au), palladium (Pd), chromium (Cr), nickel (Ni), aluminum (Al), silver (Ag), tantalum (Ta), tungsten (W), copper (Cu), titanium (Ti), indium (In), tin (Sn), iron (Fe), cobalt (Co), and molybdenum (Mo), alloys containing these metal elements, conductive particles made of these metals, conductive particles of alloys containing these metals, nitrides and oxides containing these metal elements, polysilicon containing impurities, carbon-based materials, oxide semiconductors, carbon nanotubes, and graphene. Specific examples include titanium nitride (TiN) and titanium oxide (TiO). Other examples of materials constituting the lower electrode 11 include organic materials (conductive polymers) such as poly(3,4-ethylenedioxythiophene) / polystyrenesulfonic acid (PEDOT / PSS). Furthermore, the above materials may be mixed with a binder (polymer) to form a paste or ink, which may then be hardened and used as an electrode.

[0018] The lower electrode 11 can be formed as a single layer film or a laminated film made of the above materials. The film thickness of the lower electrode 11 in the lamination direction (hereinafter simply referred to as thickness) is, for example, 20 nm to 200 nm. Furthermore, the thickness of the lower electrode 11 is preferably, for example, 30 nm to 150 nm.

[0019] The buffer layer 12 functions as a so-called electron transport / hole blocking layer that selectively transfers electrons to the lower electrode 11 and inhibits the movement of holes toward the lower electrode 11 when electrons are read out as signal charges from among the charges generated in the photoelectric conversion layer 13. Alternatively, when holes are read out as signal charges, the buffer layer 12 may function as a so-called hole transport / electron blocking layer that selectively transports holes from among the charges generated in the photoelectric conversion layer 13 to the lower electrode 11 and inhibits the movement of electrons toward the lower electrode 11. The buffer layer 12 is disposed between the photoelectric conversion layer 13 and the lower electrode 11 and includes a plurality of nanoparticles 120 whose surfaces are modified with a plurality of ligands L1. The ligand L1 corresponds to a specific example of an "organic ligand" according to one aspect of the present disclosure.

[0020] 2 is a schematic diagram showing the cross-sectional structure of a nanoparticle 120. The nanoparticle 120 is a core-shell nanoparticle composed of a core portion 121 and a shell layer 122. In the buffer layer 12 formed in a layered structure using a plurality of nanoparticles 120, the plurality of nanoparticles 120 in the layer are adjacent to each other via a ligand L1.

[0021] The core portion 121 is an oxide nanoparticle formed of a metal oxide. Specifically, the core portion 121 is formed of, for example, nickel oxide (NiO), titanium oxide (TiO ２ ), zinc oxide (ZnO), tin oxide (SnO, SnO ２ The core portion 121 is an oxide nanoparticle containing at least one of zinc oxide (ZnS) and zinc sulfide (ZnS). The primary particle diameter of the core portion 121 is, for example, 1 nm or more and 100 nm or less. Furthermore, the primary particle diameter of the core portion 121 is preferably, for example, 1 nm or more and 10 nm or less.

[0022] The shell layer 122 is composed of a plurality of ligands L1, each of which is made of an organic molecule coordinated to the surface of the core portion 121. The ligand L1 is, for example, an organic molecule having a structure including a main chain R1 and two functional groups, at least one of which is a mercapto group. The ligand L1 is, for example, represented by the following general formula (1) or (2):

[0023] (Each R1 is independently a linear alkyl group having 1 to 6 carbon atoms, a chain alkyl group having 3 to 9 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, or a derivative thereof.)

[0024] (Each R1 is independently a linear alkyl group having 1 to 6 carbon atoms, a chain alkyl group having 3 to 9 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, or a derivative thereof. R2 is an amino group, a dimethylamino group, or a carboxyl group.)

[0025] The ligand L1 may be, for example, an aromatic hydrocarbon containing one or more halogen atoms in the molecule. The ligand L1 is represented, for example, by the following general formula (3). Examples of the ligand L1 represented by general formula (3) include organic molecules represented by the following general formula (4) or general formula (5). It is more preferable that the halogen atom contained in the ligand L1 is a fluorine atom.

[0026] (R3 is a monocyclic or polycyclic aromatic hydrocarbon group containing one or more halogen atoms and having 6 to 20 carbon atoms, or a derivative thereof.)

[0027] (R4 to R7 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 3 carbon atoms, a cyano group, or a derivative thereof.)

[0028] (R8 to R13 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 3 carbon atoms, a cyano group, or a derivative thereof.)

[0029] The plurality of ligands L1 coordinated to the surface of the core 121 do not need to be a single ligand, but may contain two or more of the above organic compounds.

[0030] In the photoresponsiveness characteristic evaluation described below, the current flowing through the element after light irradiation is stopped is required to decay sharply. This steep decay of the current flowing through the element after light irradiation is stopped can be achieved by reducing the energy difference between the Fermi level and the bottom energy level of the conduction band of the buffer layer 12. For example, by setting the energy difference between the Fermi level and the bottom energy level of the conduction band of the buffer layer 12 to 0.5 eV or less, the current flowing through the element after light irradiation is stopped can be steeply decayed. Furthermore, it is more preferable that the energy difference between the Fermi level and the bottom energy level of the conduction band of the buffer layer 12 be 0.3 eV or less. The energy level of the bottom energy level of the conduction band of the buffer layer 12 can be controlled by doping one or more elements into the oxide nanoparticles constituting the core region 121. Examples of elements to be doped into the oxide nanoparticles include pentavalent elements such as phosphorus (P) and arsenic (As).

[0031] The energy difference between the Fermi level and the bottom energy level of the conduction band of the buffer layer 12 can be analyzed, for example, from the Fermi level and the bottom of the valence band (VBM) obtained by ultraviolet photoelectron spectroscopy (UPS) and the bottom of the conduction band (CBM) obtained by inverse photoelectron spectroscopy (IPES) after removing the upper electrode 14 and etching the surface of the photoelectric conversion layer 13. In addition, when a luminescent material is used in the buffer layer 12, the energy difference can be confirmed by analyzing the optical energy from the emission spectrum.

[0032] The photoelectric conversion layer 13 converts light energy into electrical energy and separates charges by absorbing predetermined wavelengths at least in the visible light to near-infrared light range. The photoelectric conversion layer 13 absorbs light of some or all wavelengths in the visible light range and near-infrared light range, for example, from 900 nm to 1600 nm. The photoelectric conversion layer 13 is composed of a plurality of quantum dots 130.

[0033] 3 is a schematic diagram showing the cross-sectional structure of a quantum dot 130. The quantum dot 130 is a core-shell quantum dot composed of a core 131 and a shell layer 132. The shell layer 132 has a plurality of ligands L2 coordinated to the surface of the core 131. In the photoelectric conversion layer 13 formed in a layered configuration using a plurality of quantum dots 130, the quantum dots 130 in the layer are adjacent to each other via the ligands L2.

[0034] The core 131 is a semiconductor nanoparticle formed of a compound semiconductor. The particle diameter of the core 131 is 2 nm to 15 nm. The core 131 is made of at least one of lead sulfide (PbS), lead selenide (PbSe), indium nitride (InN), indium arsenide (InAs), indium antimonide (InSb), and indium phosphide (InP), for example.

[0035] The shell layer 132 is composed of a plurality of ligands L2. The ligands L2 are organic compounds, inorganic compounds, and ionized forms thereof. The ligands L2 inactivate highly reactive defects (dangling bonds) present on the surface of the core portion 131, for example, by forming coordinate bonds with the surface of the core portion 131. The ligands L2 have one or both of a basic group and a weakly acidic group. The ligands L2 have, for example, one or both of a thiol group and a carboxyl group having 5 or fewer carbon atoms. Examples of such ligands L2 include 1,3-benzenedithiol, 1,4-benzenedithiol, 3-mercaptopropionic acid (MPA), 1,2-ethanedithiol, malonic acid, succinic acid, 3-mercaptobenzoic acid, 4-mercaptobenzoic acid, 3-aminobenzenethiol, 4-aminobenzenethiol, inorganic halogen compounds, and organic halogen compounds.

[0036] The plurality of ligands L2 coordinated to the surface of the core 131 do not need to be a single ligand, but may contain two or more of the above organic compounds. If the length of the ligand L2 is too long, the mobility of charge carriers between the quantum dots 130 may decrease. Therefore, the length of the ligand L2 is preferably, for example, 10 nm or less.

[0037] The upper electrode 14, like the lower electrode 11, is made of, for example, a conductive film having optical transparency. In particular, the upper electrode 14 preferably has a transmittance of 50% or more and 100% or less for wavelengths of 900 nm or more and 1600 nm or less. The resistivity of the upper electrode 14 is preferably 0 mΩ·m or more and 3.8 mΩ·m or less. The material constituting the upper electrode 14 may be, for example, InP doped with tin (Sn) as a dopant. ２ O ３ Examples of the material for the upper electrode 14 include indium tin oxide (ITO), crystalline ITO, and amorphous ITO. In addition to the above, the material for the upper electrode 14 may also include tin oxide (SnO ２ )-based materials, for example, ATO with Sb added as a dopant, and FTO with fluorine added as a dopant. Zinc oxide (ZnO) or a zinc oxide-based material with a dopant added thereto may also be used. Examples of ZnO-based materials include aluminum zinc oxide (AZO) with aluminum (Al) added as a dopant, gallium zinc oxide (GZO) with gallium (Ga) added, boron zinc oxide with boron (B) added, and indium zinc oxide (IZO) with indium (In) added. Furthermore, zinc oxide with indium and gallium added as dopants (IGZO, In-GaZnO ４ In addition, the upper electrode 14 may be made of CuI, InSbO ４ , ZnMgO, CuInO ２ , MgIN ２ O ４ , CdO, ZnSnO ３ or TiO ２ Alternatively, spinel oxides or YbFe ２ O ４ Oxides having such a structure may also be used.

[0038] Furthermore, if optical transparency is not required for the upper electrode 14, a single metal or alloy having a high work function (for example, φ=4.5 eV to 5.5 eV) can be used. Specific examples include Au, Ag, Cr, Ni, Pd, Pt, Fe, iridium (Ir), germanium (Ge), osmium (Os), rhenium (Re), tellurium (Te), and alloys thereof.

[0039] Furthermore, examples of materials that can be used to form the upper electrode 14 include metals such as Pt, Au, Pd, Cr, Ni, Al, Ag, Ta, W, Cu, Ti, In, Sn, Fe, Co, and Mo, alloys containing these metal elements, conductive particles made of these metals, conductive particles of alloys containing these metals, polysilicon containing impurities, carbon-based materials, oxide semiconductors, carbon nanotubes, and graphene. Other examples of materials that can be used to form the upper electrode 14 include organic materials (conductive polymers) such as PEDOT / PSS. Alternatively, the above materials can be mixed with a binder (polymer) to form a paste or ink, which can then be cured and used as an electrode.

[0040] The upper electrode 14 can be formed as a single layer or a laminated film made of the above materials. The thickness of the upper electrode 14 is, for example, 10 nm to 300 nm, and preferably 10 nm to 100 nm.

[0041] It should be noted that another layer may be provided between the lower electrode 11 and the upper electrode 14. For example, when electrons are read out as signal charges, a layer may be provided between the photoelectric conversion layer 13 and the upper electrode 14 that functions as a so-called hole transport / electron blocking layer, which selectively transports holes, among the charges generated in the photoelectric conversion layer 13, to the upper electrode 14 and inhibits the movement of electrons toward the upper electrode 14. Alternatively, when holes are read out as signal charges, a layer may be provided between the photoelectric conversion layer 13 and the upper electrode 14 that selectively transports electrons, among the charges generated in the photoelectric conversion layer 13, to the upper electrode 14 and inhibits the movement of holes toward the upper electrode 14.

[0042] [1-2. Manufacturing Method of Photodetector] An example of a manufacturing process for the photodetector 10 shown in Fig. 1 will be described below. Note that the numerical values ​​are merely examples and will vary depending on the materials and amounts used.

[0043] First, a lower electrode 11 with an ITO film is prepared, subjected to UV ozone treatment, and then annealed at 150°C for 5 minutes. Next, a 1 mg / mL solution of ligand-exchanged nanoparticles (e.g., ZnO) is dropped onto a silicon substrate, and a film is formed, for example, by spin coating at 200 rpm. The substrate is then rinsed with acetonitrile. After drying at 1500 rpm, the substrate is annealed at 150°C for 10 minutes. The buffer layer 12 is obtained by the above operations.

[0044] Next, quantum dots (e.g., InAs) that have been subjected to ligand exchange treatment are dropped onto the surface of the buffer layer 12, and a quantum dot layer is formed by, for example, spin coating at 1000 rpm for 1 minute. Annealing is then performed at 120°C for 10 minutes. This quantum dot layer formation process is repeated twice.

[0045] Subsequently, the quantum dot layer is formed by spin coating using, for example, PTB7-Th at 1000 rpm for 1 minute, thereby obtaining the photoelectric conversion layer 13.

[0046] Next, an ITO film is laminated on the photoelectric conversion layer 13 by, for example, sputtering to obtain the upper electrode 14. By the above method, the photodetector element 10 is completed.

[0047] 4 shows an example of the overall configuration of a photodetector (photodetector 1) according to the present disclosure. The photodetector 1 is used in an electronic device (electronic device 1000, see FIG. 8) described below.

[0048] The photodetector 1 captures incident light (image light) from a subject via, for example, an optical lens system (not shown), converts the amount of incident light imaged on an imaging surface into an electrical signal on a pixel-by-pixel basis, and outputs the signal as a pixel signal. The photodetector 1 has a pixel section 100A as an imaging area on a semiconductor substrate 20, and also has, in a peripheral region of the pixel section 100A, for example, a vertical drive circuit 111, a column signal processing circuit 112, a horizontal drive circuit 113, an output circuit 114, a control circuit 115, and input / output terminals 116.

[0049] The pixel section 100A has, for example, a plurality of unit pixels P arranged two-dimensionally in a matrix. In the unit pixels P, for example, a pixel drive line Lread (specifically, a row selection line and a reset control line) is wired for each pixel row, and a vertical signal line Lsig is wired for each pixel column. The pixel drive line Lread transmits a drive signal for reading out signals from the unit pixels P. One end of the pixel drive line Lread is connected to an output terminal of the vertical drive circuit 111 corresponding to each row.

[0050] The vertical drive circuit 111 is a pixel drive unit that includes a shift register, an address decoder, etc., and drives each unit pixel P of the pixel unit 100A, for example, row by row. Signals output from each unit pixel P of a pixel row selected and scanned by the vertical drive circuit 111 are supplied to a column signal processing circuit 112 through each vertical signal line Lsig. The column signal processing circuit 112 is configured with an amplifier, a horizontal selection switch, etc., provided for each vertical signal line Lsig.

[0051] The horizontal drive circuit 113 is configured with a shift register, an address decoder, etc., and scans and sequentially drives each horizontal selection switch of the column signal processing circuit 112. By selective scanning by this horizontal drive circuit 113, signals of each pixel transmitted through each vertical signal line Lsig are output in sequence to horizontal signal lines 117 and transmitted to the outside of the semiconductor substrate 20 through the horizontal signal lines 117.

[0052] The output circuit 114 processes and outputs signals sequentially supplied from each of the column signal processing circuits 112 via a horizontal signal line 117. The output circuit 114 may perform only buffering, or may perform black level adjustment, column variation correction, various digital signal processing, and the like, for example.

[0053] The circuit portion consisting of the vertical drive circuit 111, the column signal processing circuit 112, the horizontal drive circuit 113, the horizontal signal line 117, and the output circuit 114 may be formed directly on the semiconductor substrate 20, or may be disposed on an external control IC. Furthermore, these circuit portions may be formed on another substrate connected by a cable or the like.

[0054] The control circuit 115 receives a clock and data instructing an operation mode from outside the semiconductor substrate 20, and outputs data such as internal information of the photodetector 1. The control circuit 115 further has a timing generator that generates various timing signals, and controls the driving of peripheral circuits such as the vertical drive circuit 111, the column signal processing circuit 112, and the horizontal drive circuit 113 based on the various timing signals generated by the timing generator.

[0055] The input / output terminal 116 is used to exchange signals with the outside.

[0056] Fig. 5 is a schematic diagram showing an example of a cross-sectional configuration of each unit pixel P of the photodetector 1 shown in Fig. 4. Fig. 6 is an equivalent circuit diagram of each unit pixel P of the photodetector 1 shown in Fig. 4.

[0057] The photodetector 1 includes, for example, a semiconductor substrate 20 having a pair of opposing surfaces (surfaces 20S1 and 20S2), and a photoelectric conversion unit provided on the surface 20S1, which is the light incident side S1, for absorbing light corresponding to some or all of the wavelengths in a selective wavelength range (for example, the visible light region and near-infrared region of 900 nm or more and less than 1600 nm) to generate excitons (electron-hole pairs). The photoelectric conversion unit is the above-mentioned photodetector element 10, and includes a buffer layer 12 and a photoelectric conversion layer 13 between a lower electrode 11 and an upper electrode 14 arranged opposite each other.

[0058] In the photodetector element 10, light incident on the photodetector element 10 from the upper electrode 14 side is absorbed in the photoelectric conversion layer 13. The resulting excitons dissociate into electrons and holes. The charge carriers (electrons and holes) generated here are transported to different electrodes by diffusion due to the difference in charge carrier concentration and by an internal electric field due to the difference in work function between the anode (e.g., upper electrode 14) and the cathode (e.g., lower electrode 11), and are detected as photocurrent. The transport direction of the electrons and holes is controlled by applying a potential between the lower electrode 11 and the upper electrode 14.

[0059] The semiconductor substrate 20 is made of, for example, an n-type silicon (Si) substrate. A surface 20S1 of the semiconductor substrate 20 is provided with, for example, a floating diffusion FD (region 21C in the semiconductor substrate 20), an amplifier transistor (modulation element) AMP, a reset transistor RST, a selection transistor SEL, and an element isolation region 24. In addition, a peripheral circuit (not shown) including a logic circuit and the like is provided on the periphery of the semiconductor substrate 20.

[0060] Between the surface 20S1 of the semiconductor substrate 20 and the lower electrode 11 of the photodetector element 10, for example, an insulating layer 25 and interlayer insulating layers 26, 27, and 28 are provided in this order on the surface 20S1 side. A planarizing layer 17 is provided on the upper electrode 14 of the photodetector element 10, and an optical member such as an on-chip lens 18 is disposed on the planarizing layer 17.

[0061] The reset gate 21 of the reset transistor RST is disposed next to the floating diffusion FD (region 21B), which allows the charge carriers stored in the floating diffusion FD to be reset by the reset transistor RST.

[0062] The reset transistor RST resets the charge carriers transferred from the photodetector element 10 to the floating diffusion FD, and is composed of, for example, a MOS transistor. Specifically, the reset transistor RST is composed of a reset gate 21, a channel formation region 21A, and source / drain regions 21B and 21C. The reset gate 21 is connected to a reset line, and one source / drain region 21C of the reset transistor RST also serves as the floating diffusion FD. The other source / drain region 21B constituting the reset transistor RST is connected to a power supply VDD.

[0063] The amplifier transistor AMP is a modulation element that modulates the amount of charge generated in the photodetector element 10 into a voltage and is composed of, for example, a MOS transistor. Specifically, the amplifier transistor AMP is composed of an amplifier gate 22, a channel formation region 22A, and source / drain regions 22B and 22C. The amplifier gate 22 is connected to the lower electrode 11 and one of the source / drain regions 21C (floating diffusion FD) of the reset transistor RST via a via and through-wiring 31 provided in the interlayer insulating layer 26, wiring 32 and through-wiring 33 provided in the interlayer insulating layer 27, and wiring 34 and contacts 35 provided in the interlayer insulating layer 28. The one of the source / drain regions 22C shares an area with the other of the source / drain regions 21B constituting the reset transistor RST and is connected to the power supply VDD.

[0064] The select transistor SEL is composed of a select gate 23, a channel formation region 23A, and source / drain regions 23B and 23C. The select gate 23 is connected to a select line. One source / drain region 23V shares an area with the other source / drain region 22B that constitutes the amplifier transistor AMP, and the other source / drain region 23B is connected to a signal line (data output line) VSL.

[0065] The reset line and the selection line are each connected to a row scanning unit 134 that constitutes a driving circuit. The signal line (data output line) VSL is connected to a horizontal selection unit 133 that constitutes a driving circuit.

[0066] The element isolation region 24 has an STI (Shallow Trench Isolation) structure and is made of, for example, silicon oxide.

[0067] The insulating layer 25 may be a film having a positive fixed charge or a film having a negative fixed charge. Examples of materials for films having a negative fixed charge include hafnium oxide, aluminum oxide, zirconium oxide, tantalum oxide, and titanium oxide. Materials other than those mentioned above include lanthanum oxide, praseodymium oxide, cerium oxide, neodymium oxide, promethium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, thulium oxide, ytterbium oxide, lutetium oxide, yttrium oxide, an aluminum nitride film, a hafnium oxynitride film, and an aluminum oxynitride film.

[0068] The interlayer insulating layers 26, 27, and 28 are each formed of a single layer film made of one of silicon oxide, silicon nitride, silicon oxynitride (SiON), or a laminated film made of two or more of these materials, for example.

[0069] The reset gate 21, the amplifier gate 22, the select gate 23, the through wirings 31 and 33, the wirings 32 and 34, and the contacts 35 are made of, for example, a doped silicon material such as PDAS (Phosphorus Doped Amorphous Silicon) or a metal material such as aluminum (Al), tungsten (W), titanium (Ti), cobalt (Co), hafnium (Hf), or tantalum (Ta).

[0070] The planarization layer 17 is made of a light-transmitting material, and is made of, for example, a single layer film made of any of silicon oxide, silicon nitride, and silicon oxynitride, or a laminate film made of two or more of these materials. The thickness of the planarization layer 17 is, for example, 100 nm to 30,000 nm. Like the planarization layer 17, the on-chip lens 18 is made of a light-transmitting material.

[0071] [1-4. Actions and Effects] In the photodetector element 10 according to an embodiment of the present disclosure, the surfaces of the nanoparticles 120 that make up the buffer layer 12 are modified with a plurality of ligands L1 made of organic molecules, thereby suppressing the occurrence of defects on the surfaces of the nanoparticles 120. Furthermore, in the photodetector element 10, the buffer layer 12 is formed using nanoparticles 120 whose surfaces have been modified with ligands L1 made of organic molecules, thereby suppressing the occurrence of defects inside the buffer layer 12. This will be described below.

[0072] As mentioned above, suppression of dark current is an issue in a photodetector element having a stacked structure of a buffer layer and a photoelectric conversion layer between two electrodes arranged opposite to each other.Furthermore, in a photodetector device in which a photoelectric conversion layer is formed continuously for multiple pixels, crosstalk due to lateral leakage current is an issue.

[0073] In the photoelectric conversion element described above, dark current is suppressed by coordinating organic molecules or halogen elements at the interface between the buffer layer and the photoelectric conversion layer, but this does not achieve sufficient dark current suppression, and the lateral leakage current remains high.

[0074] In contrast, in the photodetector element 10 of the present embodiment, a buffer layer 12 containing a plurality of nanoparticles 120 with organic molecules coordinated to their surfaces is provided between the photoelectric conversion layer 13 provided between the opposing lower electrode 11 and upper electrode 14 and the lower electrode 11. As described above, the surfaces of the plurality of nanoparticles 120 constituting the buffer layer 12 are modified with a plurality of ligands L1 composed of organic molecules, thereby suppressing the occurrence of defects on the surfaces of the nanoparticles 120. The buffer layer 12 is formed including a plurality of nanoparticles 120 whose surfaces are modified with ligands L1 composed of organic molecules. In other words, in the photodetector element 10 of the present embodiment, defects are terminated not only at the interface between the buffer layer 12 and the photoelectric conversion layer 13 but also within the buffer layer 12. As a result, it is possible to suppress lateral leakage current due to defects while keeping dark current low.

[0075] Furthermore, in the photodetector element 10 of the present embodiment, as described above, the buffer layer 12 is formed using a plurality of nanoparticles 120 whose surfaces are modified with a plurality of ligands L1 made of organic molecules, thereby suppressing water adsorption to the nanoparticles 120. This improves adhesion between the buffer layer 12 and the photoelectric conversion layer 13, making film peeling between the buffer layer 12 and the photoelectric conversion layer 13 less likely to occur compared to a typical photodetector element. This makes it possible to improve reliability.

[0076] Furthermore, when defects on the surface of nanoparticles are terminated by surface treatment, the carrier concentration of the buffer layer formed using the nanoparticles tends to decrease, increasing the difference between the Fermi level and the bottom energy level of the conduction band of the buffer layer. If the difference between the Fermi level and the bottom energy level of the conduction band of the buffer layer increases, an energy barrier is formed at the interface between the photoelectric conversion layer and the buffer layer, which may result in a decrease in photoresponsiveness. In contrast, in the photodetector element 10 of the present embodiment, the nanoparticles 120 are surface-treated while being doped with, for example, n-type impurities, thereby suppressing the increase in the energy difference between the Fermi level and the bottom energy level of the conduction band of the buffer layer 12. Therefore, it is possible to provide a photodetector element that suppresses dark current and lateral leakage current due to defects, and has good photoresponsiveness.

[0077] 7 is a schematic diagram illustrating an example of a cross-sectional configuration of a photodetector (photodetector 1A) according to a modification of the present disclosure. Like the photodetector 1 described above, the photodetector 1A is used in electronic devices (electronic device 1000, see FIG. 8 ) such as CMOS image sensors used in electronic devices such as digital still cameras and video cameras. The photodetector 1A of this modification differs from the photodetector 1 in that the lower electrode 11 is made up of multiple electrodes (e.g., two electrodes: a readout electrode 11A and a storage electrode 11B) and an insulating film 19 is provided between the lower electrode 11 and the buffer layer 12.

[0078] The readout electrode 11A is for transferring charges generated in the photoelectric conversion layer 13 to the floating diffusion FD (region 21C). The readout electrode 11A is connected to the floating diffusion FD via, for example, through-wires 31 and 33, wires 32 and 34, and contacts 35.

[0079] The storage electrode 11B is used to store electrons as signal charges above it, among the charge carriers generated in the photoelectric conversion layer 13. The storage electrode 11B is preferably larger than the readout electrode 11A, which allows it to store a larger amount of charge. The storage electrode 11B is connected to a voltage application unit (not shown) via wiring such as wiring 36 and contact 37.

[0080] The insulating film 19 serves to electrically separate the storage electrode 11B from the buffer layer 12. The insulating film 19 is provided, for example, on the interlayer insulating layer 28 so as to cover the lower electrode 11. An opening is provided in the insulating film 19 above the read electrode 11A, thereby electrically connecting the read electrode 11A and the buffer layer 12.

[0081] The insulating film 19 is, for example, a single layer film made of one of silicon oxide, silicon nitride, silicon oxynitride, etc., or a laminated film made of two or more of these materials. The thickness of the insulating film 19 is, for example, 20 nm to 500 nm.

[0082] Note that another layer may be provided between the insulating film 19 and the buffer layer 12. For example, a semiconductor layer having a higher charge mobility and a larger band gap than the buffer layer 12 may be provided between the insulating film 19 and the buffer layer 12. Examples of materials for the semiconductor layer include oxide semiconductors such as IGZO and organic semiconductors. Examples of organic semiconductors include transition metal dichalcogenides, silicon carbide, diamond, graphene, carbon nanotubes, condensed polycyclic hydrocarbon compounds, and condensed heterocyclic compounds. By providing a semiconductor layer made of the above materials, signal charges generated in the photoelectric conversion layer 13 are accumulated in the semiconductor layer, reducing charge recombination during charge accumulation and improving transfer efficiency.

[0083] In this way, the configuration of the photodetector is not limited to the photodetector 1 of the above embodiment, and the photodetector 1A of this modified example can also achieve the same effects as those of the above embodiment.

[0084] 3. Application Examples (Application Example 1) The above-described light detection device 1, for example, can be applied to various electronic devices, such as imaging systems such as digital still cameras and digital video cameras, mobile phones with imaging functions, or other devices with imaging functions.

[0085] FIG. 8 is a block diagram showing an example of the configuration of electronic device 1000. As shown in FIG.

[0086] As shown in FIG. 8 , electronic device 1000 includes an optical system 1001, a photodetector 1, and a DSP (Digital Signal Processor) 1002. DSP 1002, memory 1003, a display device 1004, a recording device 1005, an operation system 1006, and a power supply system 1007 are connected via a bus 1008, and is capable of capturing still images and moving images.

[0087] The optical system 1001 is configured to have one or more lenses, and receives incident light (image light) from a subject and forms an image on the imaging surface of the photodetector 1 .

[0088] The above-described photodetection device 1 or photodetection device 1A is applied as the photodetection device 1. The photodetection device 1 converts the amount of incident light imaged on an imaging surface by an optical system 1001 into an electrical signal on a pixel-by-pixel basis and supplies the signal as a pixel signal to a DSP 1002.

[0089] The DSP 1002 performs various signal processing on the signal from the photodetector 1 to acquire an image, and temporarily stores the image data in the memory 1003. The image data stored in the memory 1003 is recorded in the recording device 1005 or supplied to the display device 1004 to display the image. In addition, the operation system 1006 accepts various operations by the user and supplies operation signals to each block of the electronic device 1000, and the power supply system 1007 supplies the power necessary to drive each block of the electronic device 1000.

[0090] (Application Example 2) Fig. 9A schematically illustrates an example of the overall configuration of a light detection system 2000 including, for example, the light detection device 1. Fig. 9B illustrates an example of the circuit configuration of the light detection system 2000. The light detection system 2000 includes a light emitting device 2001 serving as a light source unit that emits infrared light LH2, and a light detection device 2002 serving as a light receiving unit. The light detection device 2002 may be, for example, the light detection device 1 described above. The light detection system 2000 may further include a system control unit 2003, a light source driving unit 2004, a sensor control unit 2005, a light source side optical system 2006, and a camera side optical system 2007.

[0091] The photodetector 2002 can detect light LH1 and light LH2. Light LH1 is external ambient light reflected by a subject (object to be measured) 2100 ( FIG. 9A ). Light LH2 is light emitted by the light-emitting device 2001 and then reflected by the subject 2100. Light LH1 is, for example, visible light, and light LH2 is, for example, infrared light. Light LH1 can be detected by a photoelectric conversion unit in the photodetector 2002, and light LH2 can be detected by a photoelectric conversion region in the photodetector 2002. Image information of the subject 2100 can be obtained from light LH1, and distance information between the subject 2100 and the photodetector system 2000 can be obtained from light LH2. The photodetector system 2000 can be mounted on, for example, an electronic device such as a smartphone or a mobile object such as a car. The light-emitting device 2001 can be configured, for example, with a semiconductor laser, a surface-emitting semiconductor laser, or a vertical-cavity surface-emitting laser (VCSEL). The detection method of the light LH2 emitted from the light-emitting device 2001 by the photodetector 2002 can be, for example, an iTOF system, but is not limited to this. In the iTOF system, the photoelectric conversion unit can measure the distance to the subject 2100 using, for example, the time-of-flight (TOF). The detection method of the light LH2 emitted from the light-emitting device 2001 by the photodetector 2002 can also be, for example, a structured light system or a stereo vision system. For example, in the structured light system, a predetermined pattern of light is projected onto the subject 2100, and the distance between the light detection system 2000 and the subject 2100 can be measured by analyzing the distortion of the pattern. In addition, in the stereo vision method, for example, two or more cameras are used to acquire two or more images of the subject 2100 viewed from two or more different viewpoints, thereby making it possible to measure the distance between the light detection system 2000 and the subject. Note that the light emitting device 2001 and the light detection device 2002 can be synchronously controlled by a system control unit 2003.

[0092] 4. Application Example Application Example to an Endoscopic Surgery System The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be applied to an endoscopic surgery system.

[0093] FIG. 10 is a diagram showing an example of a schematic configuration of an endoscopic surgery system to which the technology according to the present disclosure (the present technology) can be applied.

[0094] 10 shows an operator (doctor) 11131 performing surgery on a patient 11132 on a patient bed 11133 using an endoscopic surgery system 11000. As shown in the figure, the endoscopic surgery system 11000 is composed of an endoscope 11100, other surgical tools 11110 such as an insufflation tube 11111 and an energy treatment tool 11112, a support arm device 11120 that supports the endoscope 11100, and a cart 11200 on which various devices for endoscopic surgery are mounted.

[0095] The endoscope 11100 is composed of a lens barrel 11101, a region of a predetermined length from the tip of which is inserted into a body cavity of a patient 11132, and a camera head 11102 connected to the base end of the lens barrel 11101. In the example shown, the endoscope 11100 is configured as a so-called rigid scope having a rigid lens barrel 11101, but the endoscope 11100 may also be configured as a so-called flexible scope having a flexible lens barrel.

[0096] An opening into which an objective lens is fitted is provided at the tip of the lens barrel 11101. A light source device 11203 is connected to the endoscope 11100, and light generated by the light source device 11203 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 11101, and is irradiated via the objective lens toward an object to be observed inside the body cavity of the patient 11132. The endoscope 11100 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0097] An optical system and an image sensor are provided inside the camera head 11102, and light reflected from the object of observation (observation light) is collected by the optical system onto the image sensor. The observation light is photoelectrically converted by the image sensor to generate an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observed image. The image signal is sent to a camera control unit (CCU) 11201 as RAW data.

[0098] The CCU 11201 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and comprehensively controls the operations of the endoscope 11100 and the display device 11202. Furthermore, the CCU 11201 receives an image signal from the camera head 11102 and performs various types of image processing on the image signal, such as development processing (demosaic processing), to display an image based on the image signal.

[0099] Under the control of the CCU 11201, the display device 11202 displays an image based on an image signal that has been subjected to image processing by the CCU 11201.

[0100] The light source device 11203 is composed of a light source such as an LED (light emitting diode), and supplies irradiation light to the endoscope 11100 when photographing the surgical site, etc.

[0101] The input device 11204 is an input interface for the endoscopic surgery system 11000. A user can input various information and instructions to the endoscopic surgery system 11000 via the input device 11204. For example, the user inputs an instruction to change the imaging conditions (type of irradiation light, magnification, focal length, etc.) of the endoscope 11100.

[0102] The treatment tool control device 11205 controls the driving of the energy treatment tool 11112 for cauterizing tissue, incising, sealing blood vessels, etc. The insufflation device 11206 inflates the body cavity of the patient 11132 through the insufflation tube 11111 in order to ensure a clear field of view for the endoscope 11100 and a working space for the surgeon. The recorder 11207 is a device capable of recording various types of information related to the surgery. The printer 11208 is a device capable of printing various types of information related to the surgery in various formats such as text, images, or graphs.

[0103] The light source device 11203, which supplies illumination light to the endoscope 11100 when photographing the surgical site, can be configured from a white light source, such as an LED, a laser light source, or a combination of these. When the white light source is configured from a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, allowing the light source device 11203 to adjust the white balance of the captured image. In this case, it is also possible to time-share images corresponding to each RGB by irradiating the object of observation with laser light from each RGB laser light source and controlling the drive of the image sensor of the camera head 11102 in synchronization with the irradiation timing. According to this method, color images can be obtained without providing a color filter to the image sensor.

[0104] Furthermore, the light source device 11203 may be controlled to change the intensity of light it outputs at predetermined time intervals. By controlling the driving of the image sensor of the camera head 11102 in synchronization with the timing of the change in light intensity to acquire images in a time-division manner and combining the images, it is possible to generate an image with a high dynamic range that is free from so-called blocked-up shadows and blown-out highlights.

[0105] The light source device 11203 may also be configured to supply light in a predetermined wavelength range compatible with special light observation. Special light observation, for example, utilizes the wavelength dependence of light absorption in body tissues to irradiate light with a narrower band than the light irradiated during normal observation (i.e., white light), thereby capturing high-contrast images of specific tissues, such as blood vessels on the surface of mucous membranes, in what is known as narrow band imaging. Alternatively, special light observation may involve fluorescence observation, in which images are obtained using fluorescence generated by irradiating excitation light onto the body tissue. Fluorescence observation may involve irradiating excitation light onto the body tissue and observing the fluorescence from the body tissue (autofluorescence observation), or irradiating the body tissue with excitation light corresponding to the fluorescent wavelength of a reagent such as indocyanine green (ICG) to obtain a fluorescent image. The light source device 11203 may be configured to supply narrow band light and / or excitation light compatible with such special light observation.

[0106] FIG. 11 is a block diagram showing an example of the functional configuration of the camera head 11102 and the CCU 11201 shown in FIG.

[0107] The camera head 11102 has a lens unit 11401, an imaging unit 11402, a drive unit 11403, a communication unit 11404, and a camera head control unit 11405. The CCU 11201 has a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera head 11102 and the CCU 11201 are connected to each other via a transmission cable 11400 so that they can communicate with each other.

[0108] The lens unit 11401 is an optical system provided at the connection portion with the lens barrel 11101. Observation light taken in from the tip of the lens barrel 11101 is guided to the camera head 11102 and enters the lens unit 11401. The lens unit 11401 is composed of a combination of multiple lenses including a zoom lens and a focus lens.

[0109] The imaging unit 11402 may include one imaging element (a so-called single-chip type) or multiple imaging elements (a so-called multi-chip type). When the imaging unit 11402 is configured as a multi-chip type, for example, each imaging element may generate an image signal corresponding to each of RGB, and a color image may be obtained by combining these signals. Alternatively, the imaging unit 11402 may be configured to have a pair of imaging elements for acquiring image signals for the right eye and the left eye corresponding to 3D (dimensional) display. The 3D display allows the surgeon 11131 to more accurately grasp the depth of the biological tissue at the surgical site. Note that when the imaging unit 11402 is configured as a multi-chip type, multiple lens units 11401 may be provided corresponding to each imaging element.

[0110] Furthermore, the imaging unit 11402 does not necessarily have to be provided in the camera head 11102. For example, the imaging unit 11402 may be provided inside the lens barrel 11101, immediately after the objective lens.

[0111] The driving unit 11403 is configured by an actuator, and moves the zoom lens and focus lens of the lens unit 11401 by a predetermined distance along the optical axis under the control of the camera head control unit 11405. This allows the magnification and focus of the image captured by the imaging unit 11402 to be adjusted appropriately.

[0112] The communication unit 11404 is configured by a communication device for transmitting and receiving various types of information to and from the CCU 11201. The communication unit 11404 transmits the image signal obtained from the imaging unit 11402 to the CCU 11201 via the transmission cable 11400 as RAW data.

[0113] Furthermore, the communication unit 11404 receives a control signal for controlling the driving of the camera head 11102 from the CCU 11201 and supplies the control signal to the camera head control unit 11405. The control signal includes information on the imaging conditions, such as information specifying the frame rate of the captured image, information specifying the exposure value at the time of imaging, and / or information specifying the magnification and focus of the captured image.

[0114] The image capturing conditions such as the frame rate, exposure value, magnification, and focus may be appropriately specified by the user, or may be automatically set by the control unit 11413 of the CCU 11201 based on the acquired image signal. In the latter case, the endoscope 11100 is equipped with a so-called AE (Auto Exposure) function, AF (Auto Focus) function, and AWB (Auto White Balance) function.

[0115] The camera head control unit 11405 controls the driving of the camera head 11102 based on a control signal received from the CCU 11201 via the communication unit 11404 .

[0116] The communication unit 11411 is configured by a communication device for transmitting and receiving various information to and from the camera head 11102. The communication unit 11411 receives an image signal transmitted from the camera head 11102 via the transmission cable 11400.

[0117] Furthermore, the communication unit 11411 transmits to the camera head 11102 a control signal for controlling the driving of the camera head 11102. The image signal and the control signal can be transmitted by electrical communication, optical communication, or the like.

[0118] The image processing unit 11412 performs various image processing operations on the image signal, which is RAW data transmitted from the camera head 11102 .

[0119] The control unit 11413 performs various controls related to the imaging of the surgical site, etc. by the endoscope 11100 and the display of the captured image obtained by imaging the surgical site, etc. For example, the control unit 11413 generates a control signal for controlling the driving of the camera head 11102.

[0120] Furthermore, the control unit 11413 displays the captured image showing the surgical site, etc., on the display device 11202 based on the image signal subjected to image processing by the image processing unit 11412. At this time, the control unit 11413 may recognize various objects in the captured image using various image recognition technologies. For example, the control unit 11413 can recognize surgical tools such as forceps, specific biological parts, bleeding, mist generated when using the energy treatment tool 11112, etc., by detecting the shape and color of the edges of objects included in the captured image. When displaying the captured image on the display device 11202, the control unit 11413 may use the recognition results to superimpose various surgical support information on the image of the surgical site. By superimposing the surgical support information and presenting it to the surgeon 11131, the burden on the surgeon 11131 can be reduced and the surgeon 11131 can proceed with the surgery reliably.

[0121] The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 is an electrical signal cable for electrical signal communication, an optical fiber for optical communication, or a composite cable of these.

[0122] In the illustrated example, communication is performed wired using a transmission cable 11400, but communication between the camera head 11102 and the CCU 11201 may also be performed wirelessly.

[0123] The above describes an example of an endoscopic surgery system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to the imaging unit 11402 among the components described above. By applying the technology according to the present disclosure to the imaging unit 11402, detection accuracy is improved.

[0124] Although an endoscopic surgery system has been described as an example here, the technology according to the present disclosure may also be applied to other systems, such as a microsurgery system.

[0125] (Application Example to Mobile Object) The technology according to the present disclosure can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of mobile object, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, a robot, construction machinery, or agricultural machinery (tractor).

[0126] FIG. 12 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile object control system to which the technology according to the present disclosure can be applied.

[0127] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 13, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. Also shown as functional components of the integrated control unit 12050 are a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (interface) 12053.

[0128] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating a braking force of the vehicle.

[0129] The body system control unit 12020 controls the operation of various devices equipped in the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as headlamps, backup lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves transmitted from a portable device that serves as a key or signals from various switches can be input to the body system control unit 12020. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0130] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture images outside the vehicle and receives the captured images. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for people, cars, obstacles, signs, characters on the road surface, etc. based on the received images.

[0131] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0132] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

[0133] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, steering mechanism, or braking device based on the information inside and outside the vehicle acquired by the outside-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane departure warning, etc.

[0134] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle obtained by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0135] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the outside information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside information detection unit 12030, and perform cooperative control aimed at preventing glare, such as switching from high beams to low beams.

[0136] The audio / video output unit 12052 transmits at least one of audio and video output signals to an output device capable of visually or audibly notifying the passengers of the vehicle or the outside of the vehicle of information. In the example of Fig. 12, the output devices are exemplified by an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

[0137] FIG. 13 is a diagram showing an example of the installation position of the imaging unit 12031.

[0138] In FIG. 13, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0139] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided on the front nose and the imaging unit 12105 provided on the top of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 provided on the top of the windshield inside the vehicle cabin is mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0140] 13 shows an example of the imaging ranges of the imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, by overlaying the image data captured by the imaging units 12101 to 12104, an overhead image of the vehicle 12100 viewed from above can be obtained.

[0141] At least one of the image capturing units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image capturing units 12101 to 12104 may be a stereo camera made up of multiple image capturing elements, or may be an image capturing element having pixels for phase difference detection.

[0142] For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 can calculate the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100), thereby extracting as a preceding vehicle, in particular, the three-dimensional object that is the closest three-dimensional object on the path of the vehicle 12100 and traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or higher). Furthermore, the microcomputer 12051 can set a vehicle-to-vehicle distance to be maintained in advance in front of the preceding vehicle, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. In this way, cooperative control can be performed for the purpose of autonomous driving, which runs autonomously without relying on driver operation.

[0143] For example, the microcomputer 12051 classifies and extracts three-dimensional object data regarding three-dimensional objects into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from the imaging units 12101 to 12104, and can use the data for automatic obstacle avoidance. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 then determines a collision risk that indicates the risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drive system control unit 12010.

[0144] At least one of the image capturing units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether a pedestrian is present in the images captured by the image capturing units 12101 to 12104. Such pedestrian recognition is performed, for example, by extracting feature points from the images captured by the image capturing units 12101 to 12104 as infrared cameras and performing pattern matching on a series of feature points that indicate the outline of an object to determine whether the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the image capturing units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular outline on the recognized pedestrian for emphasis. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating the pedestrian at a desired position.

[0145] The foregoing has described an example of a mobile object control system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to the image capture unit 12031 of the above-described configuration. Specifically, the photodetection device according to the above-described embodiment and its modified example (e.g., photodetection device 1A) can be applied to the image capture unit 12031. By applying the technology according to the present disclosure to the image capture unit 12031, it is possible to obtain a high-resolution captured image with little noise, thereby enabling high-precision control using the captured image in the mobile object control system.

[0146] 5. Examples Experiment 1 In Experiment 1, as Experimental Examples 1 to 13, the photodetector element 10 was fabricated using the method described above, and its device characteristics were evaluated. In the device characteristic evaluation, the dark current characteristic (Jdk), external quantum efficiency (EQE), leakage current amount (Leak (A)), and film peeling of the photodetector element 10 were evaluated.

[0147] In Experimental Example 1, a buffer layer 12 was formed as a comparative example without performing surface treatment. In Experimental Example 2, a buffer layer 12 was formed using an organic molecule represented by the following formula (6-1) as the ligand L1. In Experimental Example 3, a buffer layer 12 was formed using an organic molecule represented by the following formula (1-1), which corresponds to general formula (1), as the ligand L1. In Experimental Example 4, a buffer layer 12 was formed using an organic molecule represented by the following formula (1-2), which corresponds to general formula (1), as the ligand L1. In Experimental Example 5, a buffer layer 12 was formed using an organic molecule represented by the following formula (6-2), which corresponds to general formula (2), as the ligand L1. In Experimental Example 6, a buffer layer 12 was formed using an organic molecule represented by the following formula (2-1), which corresponds to general formula (2), as the ligand L1. In Experimental Example 7, a buffer layer 12 was formed using an organic molecule represented by the following formula (2-2), which corresponds to general formula (2), as the ligand L1. In Experimental Example 8, a buffer layer 12 was formed using an organic molecule represented by the following formula (6-2), which corresponds to general formula (2), as the ligand L1. In Experimental Example 9, a buffer layer 12 was formed using an organic molecule represented by the following formula (2-3), which corresponds to general formula (2), as the ligand L1. In Experimental Example 10, a buffer layer 12 was formed using an organic molecule represented by the following formula (2-4), which corresponds to general formula (2), as the ligand L1. In Experimental Example 11, a buffer layer 12 was formed using an organic molecule represented by the following formula (3-1), which corresponds to general formula (3), as the ligand L1. In Experimental Example 12, a buffer layer 12 was formed using bromine represented by the following formula (6-4), as the ligand L1. In Experimental Example 13, a buffer layer 12 was formed using bromine represented by formula (6-4) and zinc bromide represented by the following formula (6-5), as the ligand L1.

[0148]

[0149] (Evaluation of Dark Current Characteristics and External Quantum Efficiency) First, the wavelength of light irradiated onto the photodetector element 10 from a green LED light source through a bandpass filter was set to 940 nm, and the light intensity was set to 1.62 μW / cm ２The bias voltage applied between the electrodes of the photodetector element 10 was controlled using a semiconductor parameter analyzer, and the voltage applied to the lower electrode 11 relative to the upper electrode 14 was swept to obtain a current-voltage curve. The dark current value and the bright current value in a reverse bias state (a state in which a voltage of +1.0 V was applied) were obtained, and the external quantum efficiency (EQE) was calculated by subtracting the dark current value from the bright current value and dividing the result by the number of incident photons.

[0150] (Evaluation of Leakage Current Amount) First, a buffer layer 12, a photoelectric conversion layer 13, and an upper electrode 14 were sequentially formed on each of electrode patterns (lower electrodes 11) that were set to have a width of 100 μm and an inter-electrode distance of 10 μm, thereby obtaining a plurality of photodetector elements 10. A voltage of 1.0 V was applied between the electrodes of the plurality of photodetector elements 10 in a dark place, and the resulting current value was evaluated as the amount of leakage current.

[0151] 14 is a flow chart illustrating an example of a method for evaluating film peeling of the light-detecting element 10 fabricated using the methods described above as Experimental Examples 1 to 13. Film peeling here refers to film peeling that occurs at the interface between the buffer layer 12 and the photoelectric conversion layer 13 in an atmospheric or water vapor environment.

[0152] Table 1 shows the criteria for classifying the evaluation results obtained in Experiment 1 into A to C. The values ​​in Table 1 are relative values ​​normalized with the value of Example 1 set to 1. Table 2 summarizes the types of ligand L1 used in Experimental Examples 2 to 13, as well as the A to C evaluations based on Table 1 for the dark current characteristics (Jdk), external quantum efficiency (EQE), leakage current amount (Leak (A)), and film peeling.

[0153]

[0154]

[0155] In Experimental Examples 3, 4, 6, 7, 9 to 11, in which organic molecules corresponding to the above general formulas (1), (2), and (3) were used as ligands L1, the dark current characteristics, external quantum efficiency, leakage current amount, and film peeling were evaluated as either A or B in the A to C evaluations. In other words, it was found that by using ligands L1 composed of organic molecules represented by the above general formulas (1) to (3), the dark current characteristics and external quantum efficiency were improved and the leakage current amount was suppressed.

[0156] It was found that film peeling did not occur in Experimental Examples 2 to 10, which used ligands L1 made of organic molecules. This is presumably because the surface of the nanoparticles 120 was modified with a plurality of ligands L1 made of organic molecules, making it difficult for water to be adsorbed, and improving the adhesion between the buffer layer 12 and the photoelectric conversion layer 13.

[0157] [Experiment 2] In Experiment 2, as Experimental Examples 14 to 17, the photodetector element 10 was fabricated using the above-described method, and the energy difference (Egap) between the bottom energy level of the conduction band of the buffer layer 12 and the Fermi level was measured, and film peeling, external quantum efficiency (EQE), leakage current amount (Leak (A)), and photoresponsiveness were evaluated.

[0158] (Evaluation of Photoresponse) First, the wavelength of light irradiated onto the photodetector element 10 from an LED light source through a bandpass filter was set to 940 nm, and the light intensity was set to 100 μW / cm ２ The voltage applied to the LED driver was controlled by a function generator, and pulsed light with a pulse width of 10 ms was irradiated from the upper electrode 14 side. The bias voltage applied between the electrodes of the photodetector element 10 was set to +1.0 V with respect to the upper electrode 14 and the lower electrode 11, and the pulsed light was irradiated, and the current decay waveform was observed using an oscilloscope. The faster the current decay after light irradiation, the faster the photoresponsiveness.

[0159] In Experimental Example 14, as a comparative example, the buffer layer 12 was formed without performing surface treatment. In Experimental Example 15, the buffer layer 12 was formed using an organic molecule represented by the following formula (1-1) as the ligand L1. In Experimental Example 16, the buffer layer 12 was formed using an organic molecule represented by the following formula (3-2), which corresponds to general formula (3), as the ligand L1. In Experimental Example 17, the buffer layer 12 was formed using an organic molecule represented by the following formula (3-3), which corresponds to general formula (3), as the ligand L1.

[0160]

[0161] FIG. 15 shows the current profile passed through the photodetector elements of Experimental Examples 14 to 17. Here, the decay time was defined as the time required for the current to decay from 90% to 10% after light irradiation was stopped. FIG. 16 shows the relationship between the current decay time and the energy gap in the photodetector elements of Experimental Examples 14 to 17. Table 3 shows the criteria for classifying the evaluation results obtained in Experiment 2 into categories A to C. The values ​​in Table 3 are relative values ​​normalized with the value in Example 14 set to 1. Table 4 summarizes the types of ligand L1 used in Experimental Examples 14 to 17, the energy difference (Egap) between the bottom energy level of the conduction band of the buffer layer 12 and the Fermi level, the external quantum efficiency (EQE), the leakage current (Leak (A)), and the film peeling ratings A to C based on Table 1, as well as the photoresponsiveness ratings A to C.

[0162]

[0163]

[0164] In Experimental Examples 15 to 17, in which organic molecules corresponding to the above general formula (1), general formula (2), and general formula (3) were used as ligands L1, the external quantum efficiency, leakage current, and film peeling were evaluated as A in the A to C ratings. Furthermore, in Experimental Examples 14 to 17, it was found that the smaller the energy difference (E gap) between the bottom energy level of the conduction band of the buffer layer 12 and the Fermi level, the better the photoresponse.

[0165] Although the present technology has been described above by way of embodiments, modifications, application examples, applied examples, and examples, the present technology is not limited to the above embodiments, etc., and various modifications are possible. For example, it is not necessary to include all of the components described in the above embodiments, etc., and conversely, other components may be included.

[0166] Furthermore, in the above embodiments, each component constituting the photodetector 1 etc. has been specifically listed and described, but it is not necessary to include all components, and other components may also be included.

[0167] The effects described in this specification are merely examples and are not limited to those described, and other effects may also be obtained.

[0168] The present disclosure may also be configured as follows. According to the present disclosure configured as follows, the surfaces of the nanoparticles are modified with organic ligands, thereby suppressing the occurrence of defects on the surfaces of the nanoparticles. In a photodetector, the buffer layer contains nanoparticles whose surfaces are modified with organic ligands, thereby suppressing the occurrence of defects inside the buffer layer. This makes it possible to suppress lateral leakage current while maintaining the carrier concentration of the buffer layer and keeping the dark current low. [1] A photodetector comprising: a first electrode; a second electrode arranged opposite the first electrode; a photoelectric conversion layer arranged between the first electrode and the second electrode; and a buffer layer arranged between the photoelectric conversion layer and the first electrode, the buffer layer including a plurality of nanoparticles whose surfaces are modified with a plurality of organic ligands. [2] The photodetector according to [1], wherein the plurality of nanoparticles are oxides doped with one or more elements. [3] The photodetector according to [1] or [2], wherein the plurality of nanoparticles include at least one of nickel oxide, titanium oxide, zinc oxide, and zinc sulfide. [4] The light-detecting element according to any one of [1] to [3], wherein each of the plurality of organic ligands has a main chain, a first functional group, and a second functional group, and the first functional group is a mercapto group. [5] The light-detecting element according to any one of [1] to [4], wherein each of the plurality of organic ligands is an organic molecule represented by the following general formula (1): (Each R1 is independently a linear alkyl group having 1 to 6 carbon atoms, a chain alkyl group having 3 to 9 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, or a derivative thereof.) [6] The light detection element according to any one of [1] to [4] above, wherein each of the plurality of organic ligands is an organic molecule represented by the following general formula (2): (Each R1 is independently a linear alkyl group having 1 to 6 carbon atoms, a chain alkyl group having 3 to 9 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, or a derivative thereof. R2 is an amino group, a dimethylamino group, or a carboxyl group.) [7] The photodetector according to any one of [1] to [3] above, wherein each of the plurality of organic ligands is an organic molecule represented by the following general formula (3): (R3 is a monocyclic or polycyclic aromatic hydrocarbon group having 6 to 20 carbon atoms, or a derivative thereof, containing one or more halogen atoms.) [8] The photodetector according to any one of [1] to [3] and [7], wherein each of the plurality of organic ligands is an organic molecule represented by the following general formula (4) and containing one or more halogen atoms: (R4 to R7 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 3 carbon atoms, a cyano group, or a derivative thereof.) [9] The light-detecting element according to [8] above, wherein one or more halogen atoms contained in each of the plurality of organic ligands represented by the general formula (4) are fluorine atoms.

[10] The light-detecting element according to any one of [1] to [3] and [7] above, wherein each of the plurality of organic ligands is an organic molecule represented by the following general formula (5) and containing one or more halogen atoms: (R8 to R13 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 3 carbon atoms, a cyano group, or a derivative thereof.)

[11] The photodetector according to

[10] above, wherein one or more halogen atoms contained in each of the plurality of organic ligands represented by general formula (5) are fluorine atoms.

[12] The photodetector according to any one of [1] to

[11] above, wherein a primary particle radius of each of the plurality of nanoparticles is 1 nm or more and 100 nm or less.

[13] The photodetector according to any one of [1] to

[12] above, wherein a primary particle radius of each of the plurality of nanoparticles is 1 nm or more and 10 nm or less.

[14] The photodetector according to any one of [1] to

[13] above, wherein an energy difference between the energy level of the bottom of the conduction band of the buffer layer and the Fermi level is 0.5 eV or less.

[15] The photodetector according to any one of [1] to

[14] , wherein the energy difference between the bottom energy level of the conduction band of the buffer layer and the Fermi level is 0.3 eV or less.

[16] The photodetector according to any one of [1] to

[15] , wherein the photoelectric conversion layer is composed of a plurality of quantum dots, and the particle diameter of the plurality of quantum dots is 2 nm to 15 nm.

[17] The photodetector according to

[16] , wherein the plurality of quantum dots include at least one of lead sulfide, lead selenide, indium nitride, indium arsenide, indium antimonide, and indium phosphide.

[18] A photodetector device comprising a plurality of pixels each provided with a photodetector element, wherein the photodetector element includes: a first electrode; a second electrode disposed opposite the first electrode; a photoelectric conversion layer disposed between the first electrode and the second electrode; and a buffer layer disposed between the photoelectric conversion layer and the first electrode, the buffer layer including a plurality of nanoparticles having surfaces modified with a plurality of organic ligands.

[19] An electronic device including a photodetector device comprising a plurality of pixels each provided with a photodetector element, wherein the photodetector element has: a first electrode; a second electrode arranged opposite to the first electrode; a photoelectric conversion layer arranged between the first electrode and the second electrode; and a buffer layer arranged between the photoelectric conversion layer and the first electrode and including a plurality of nanoparticles whose surfaces are modified with a plurality of organic ligands.

Claims

1. A photodetector comprising: a first electrode; a second electrode disposed opposite the first electrode; a photoelectric conversion layer disposed between the first electrode and the second electrode; and a buffer layer disposed between the photoelectric conversion layer and the first electrode, the buffer layer including a plurality of nanoparticles whose surfaces are modified with a plurality of organic ligands.

2. The photodetector element according to claim 1, wherein the plurality of nanoparticles are oxide nanoparticles formed from a metal oxide.

3. The photodetector element according to claim 1, wherein the plurality of nanoparticles include at least one of nickel oxide, titanium oxide, zinc oxide, and zinc sulfide.

4. The light-detecting element according to claim 1, wherein each of the plurality of organic ligands has a main chain, a first functional group, and a second functional group, and the first functional group is a mercapto group.

5. The light-detecting element according to claim 1, wherein each of the plurality of organic ligands is an organic molecule represented by the following general formula (1): (Each R1 is independently a linear alkyl group having 1 to 6 carbon atoms, a chain alkyl group having 3 to 9 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, or a derivative thereof.) 6. The light-detecting element according to claim 1, wherein each of the plurality of organic ligands is an organic molecule represented by the following general formula (2): (Each R1 is independently a linear alkyl group having 1 to 6 carbon atoms, a chain alkyl group having 3 to 9 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, or a derivative thereof. R2 is an amino group, a dimethylamino group, or a carboxyl group.) 7. The light-detecting element according to claim 1, wherein each of the plurality of organic ligands is an organic molecule represented by the following general formula (3): (R3 is a monocyclic or polycyclic aromatic hydrocarbon group containing one or more halogen atoms and having 6 to 20 carbon atoms, or a derivative thereof.) 8. The light-detecting element according to claim 1, wherein each of the plurality of organic ligands is an organic molecule represented by the following general formula (4) and contains one or more halogen atoms: (R4 to R7 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 3 carbon atoms, a cyano group, or a derivative thereof.) 9. The light-detecting element according to claim 8, wherein one or more halogen atoms contained in each of the plurality of organic ligands represented by the general formula (4) are fluorine atoms.

10. The light-detecting element according to claim 1, wherein each of the plurality of organic ligands is an organic molecule represented by the following general formula (5) and contains one or more halogen atoms: (R8 to R13 are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 3 carbon atoms, a cyano group, or a derivative thereof.) 11. The light-detecting element according to claim 10, wherein one or more halogen atoms contained in each of the plurality of organic ligands represented by the general formula (5) are fluorine atoms.

12. The photodetector according to claim 1, wherein the primary particle radius of each of the plurality of nanoparticles is 1 nm or more and 100 nm or less.

13. The photodetector according to claim 1, wherein the primary particle radius of each of the plurality of nanoparticles is 1 nm or more and 10 nm or less.

14. The photodetector according to claim 2, wherein the plurality of nanoparticles are doped with one or more elements.

15. The photodetector according to claim 1, wherein the energy difference between the bottom energy level of the conduction band of the buffer layer and the Fermi level is 0.5 eV or less.

16. The photodetector according to claim 1, wherein the energy difference between the bottom energy level of the conduction band of the buffer layer and the Fermi level is 0.3 eV or less.

17. The photodetector according to claim 1, wherein the photoelectric conversion layer is made of a plurality of quantum dots, and the particle diameter of the plurality of quantum dots is 2 nm or more and 15 nm or less.

18. The photodetector element according to claim 17, wherein the plurality of quantum dots include at least one of lead sulfide, lead selenide, indium nitride, indium arsenide, indium antimonide, and indium phosphide.

19. A photodetection device comprising a plurality of pixels each having a photodetection element, wherein the photodetection element comprises: a first electrode; a second electrode disposed opposite the first electrode; a photoelectric conversion layer disposed between the first electrode and the second electrode; and a buffer layer disposed between the photoelectric conversion layer and the first electrode and containing a plurality of nanoparticles having a plurality of organic ligands modified on their surfaces.

20. An electronic device comprising a photodetector device having a plurality of pixels each provided with a photodetector element, wherein the photodetector element has: a first electrode; a second electrode arranged opposite the first electrode; a photoelectric conversion layer arranged between the first electrode and the second electrode; and a buffer layer arranged between the photoelectric conversion layer and the first electrode and containing a plurality of nanoparticles whose surfaces are modified with a plurality of organic ligands.

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