Light detection device and electronic equipment

Abstract

A light detection device according to an embodiment of the present disclosure is provided with: a first electrode (11); a second electrode (15) disposed so as to face the first electrode (11); a photoelectric conversion layer (13) disposed between the first electrode (11) and the second electrode (15) and including semiconductor quantum dots; and a first charge transport layer (14) disposed between the photoelectric conversion layer (13) and the second electrode (15), and containing an organic material that has, within each molecule thereof, a donor unit and an acceptor unit and exhibits crystallinity.

Description

Photodetector and electronic equipment

[0001] The present disclosure relates to a photodetector and an electronic device having a photoelectric conversion layer including quantum dots.

[0002] For example, Patent Document 1 discloses a solid-state imaging device including a photoelectric conversion layer and a buffer layer made of semiconductor quantum dots.

[0003] International Publication No. 2022 / 234806

[0004] However, there is a demand for improved characteristics in photodetectors using quantum dots.

[0005] It would be desirable to provide photodetectors and electronic devices that can provide improved performance.

[0006] A first photodetector 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 including semiconductor quantum dots, and a first charge transport layer disposed between the photoelectric conversion layer and the second electrode and including an organic material having donor and acceptor moieties in its molecules and having crystallinity.

[0007] An electronic device according to an embodiment of the present disclosure includes the first photodetector according to the embodiment of the present disclosure.

[0008] In the first photodetector and the electronic device according to the embodiment of the present disclosure, a first charge transport layer including a crystalline organic material having donor and acceptor moieties in its molecules is provided between the photoelectric conversion layer including the semiconductor quantum dots and the second electrode, thereby suppressing charge recombination at the interface between the photoelectric conversion layer and the first charge transport layer.

[0009] A second photodetector 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 including first semiconductor quantum dots, and an intermediate layer disposed between the photoelectric conversion layer and the second electrode and including second semiconductor quantum dots having a particle diameter smaller than that of the first semiconductor quantum dots.

[0010] In a second photodetector according to an embodiment of the present disclosure, an intermediate layer including second semiconductor quantum dots having a particle size smaller than that of the first semiconductor quantum dots is provided between the photoelectric conversion layer including the first semiconductor quantum dots and the second electrode, thereby improving the smoothness of the upper surface of the photoelectric conversion layer facing the second electrode.

[0011] FIG. 1 is a cross-sectional view schematically illustrating an example of the configuration of a photodetector according to a first embodiment of the present disclosure. FIG. 2 is a cross-sectional view schematically illustrating the configuration of quantum dots constituting the photoelectric conversion layer shown in FIG. 1. FIG. 3 is a view illustrating a three-dimensional model of PTB7-Th. FIG. 4 is a view illustrating the configuration of molecules constituting each layer at the interface between the photoelectric conversion layer and the hole transport layer shown in FIG. 1. FIG. 5 is a block diagram illustrating the overall configuration of a photodetector according to the present disclosure. FIG. 6 is a cross-sectional view schematically illustrating the configuration of each unit pixel of the photodetector shown in FIG. 5. FIG. 7 is an equivalent circuit diagram of each unit pixel of the photodetector shown in FIG. 5. FIG. 8 is a cross-sectional view schematically illustrating an example of the configuration of a photodetector according to a first modification of the present disclosure. FIG. 9 is a cross-sectional view schematically illustrating the configuration of each unit pixel of the photodetector according to the first modification of the present disclosure. FIG. 10 is a cross-sectional view schematically illustrating the configuration of each unit pixel of the photodetector according to a second modification of the present disclosure. FIG. 11 is a cross-sectional view schematically illustrating an example of the configuration of a photodetector according to a second embodiment of the present disclosure. FIG. 12 is a schematic diagram illustrating the surface structure of the photoelectric conversion layer shown in FIG. 11 . FIG. 13 is a block diagram illustrating an example of the configuration of an electronic device using the photodetector shown in FIG. 5 . FIG. 14A is a schematic diagram illustrating an example of the overall configuration of a photodetection system using the photodetector shown in FIG. 5 . FIG. 14B is a diagram illustrating an example of the circuit configuration of the photodetection system shown in FIG. 14A . FIG. 15 is a diagram illustrating an example of the general configuration of an endoscopic surgery system. FIG. 16 is a block diagram illustrating an example of the functional configuration of a camera head and a CCU. FIG. 17 is a block diagram illustrating an example of the general configuration of a vehicle control system. FIG. 18 is an explanatory diagram illustrating an example of the installation positions of an outside vehicle information detection unit and an imaging unit. FIG. 19 shows the vacuum levels of the organic materials used in Experimental Examples 1 to 4 and 6 to 9. FIG. 20 is a characteristic diagram illustrating the evaluation results of dark current in Experimental Examples 1 to 9. FIG. 21 is a distribution diagram illustrating the relationship between dark current and crystallinity in Experimental Examples 1 to 9. FIG. 22 is a characteristic diagram illustrating the evaluation results of dark current in Experimental Examples 10 to 15. FIG. 23 is a characteristic diagram showing the evaluation results of the external quantum efficiency of Experimental Examples 10 to 15.

[0012] Hereinafter, embodiments of the present disclosure will be described in detail 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 order of description is as follows: 1. First embodiment (an example of a photodetector in which a hole transport layer containing an organic material having donor and acceptor moieties in the molecule and having crystallinity is provided on a photoelectric conversion layer using quantum dots) 2. Modifications 2-1. Modification 1 (another example of the hole transport layer configuration) 2-2. Modification 2 (another example of a photodetector) 2-3. Modification 3 (another example of a photodetector) 3. Second embodiment (an example of a photodetector in which an intermediate layer made of quantum dots with a particle size smaller than that of the quantum dots used in the photoelectric conversion layer is provided on the photoelectric conversion layer) 4. Application example 5. Application example 6. Working example

[0013] 1. First Embodiment FIG. 1 is a schematic diagram illustrating an example of a cross-sectional configuration of a photodetector element (photodetector element 10) according to a first embodiment of the present disclosure. The photodetector element 10 constitutes one pixel (unit pixel P) in a photodetector device (photodetector device 1; see FIG. 5 , for example) such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor used in electronic devices such as digital still cameras and video cameras. The photodetector element 10 includes a photoelectric conversion layer 13 between a lower electrode 11 and an upper electrode 15, which are disposed opposite each other, and a hole transport layer 14 between the photoelectric conversion layer 13 and the upper electrode 15. In this embodiment, the photoelectric conversion layer 13 includes semiconductor nanoparticles, and the hole transport layer 14 is formed using a crystalline organic material having intramolecular donor and acceptor moieties.

[0014] [Configuration of Photodetection Element] The photodetection element 10 has a configuration in which a lower electrode 11, an electron transport layer 12, a photoelectric conversion layer 13, a hole transport layer 14, and an upper electrode 15 are stacked in this order. In the photodetection element 10, of electron-hole pairs generated by photoelectric conversion, for example, electrons are read out as signal charges from the lower electrode 11 side. Below, the configuration, materials, etc. of each part will be described using as an example a case in which electrons are read out as signal charges from the lower electrode 11 side.

[0015] Here, the lower electrode 11 corresponds to a specific example of a "first electrode" in an embodiment of the present disclosure, and the upper electrode 15 corresponds to a specific example of a "second electrode" in an embodiment of the present disclosure. The photoelectric conversion layer 13 corresponds to a specific example of a "photoelectric conversion layer" in an embodiment of the present disclosure. The hole transport layer 14 corresponds to a specific example of a "first charge transport layer" in an embodiment of the present disclosure, and the electron transport layer 12 corresponds to a specific example of a "second charge transport layer" in an embodiment of the present disclosure.

[0016] 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 In addition to the above, the lower electrode 11 may be made of tin oxide (SnO ２ )-based materials, for example, ATO with Sb added as a dopant, and FTO with fluorine (F) 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 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.

[0017] 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.

[0018] 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, polysilicon containing impurities, carbon-based materials, oxide semiconductors, carbon nanotubes, and graphene. Other examples of materials constituting the lower electrode 11 include organic materials (conductive polymers) such as poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate (PEDOT / PSS). Alternatively, the above materials may be mixed with a binder (polymer) to form a paste or ink, which may then be cured and used as an electrode.

[0019] The lower electrode 11 can be formed as a single layer 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, and preferably 30 nm to 150 nm.

[0020] The electron transport layer 12 selectively transports electrons, among the charge carriers generated in the photoelectric conversion layer 13, to the lower electrode 11, while inhibiting the injection of holes from the lower electrode 11 side. The electron transport layer 12 can be formed using an organic compound, an oxide semiconductor, or semiconductor nanoparticles. An n-type semiconductor is preferable as the organic compound, and examples thereof include organometallic dyes formed as complexes of transition metal ions, such as zinc phthalocyanine (II), with an organic material. Other examples of n-type semiconductors include fullerenes or derivatives thereof, and non-fullerene acceptors, such as ITIC derivatives and BTP derivatives. Examples of oxide semiconductors and semiconductor nanoparticles include titanium oxide (TiO ２ ), zinc oxide (ZnO), zinc sulfide (ZnS), SrTiO ３ , niobium oxide (Nb ２ O ５ ), tungsten oxide (WO ３ ), indium oxide (In ２ O ３ ), CuTiO ３ , tin oxide (SnO ２ ), InGaZnO4, InTiO ２ and β-Ga ２ O ３ and other inorganic materials.

[0021] The thickness of the electron transport layer 12 is, for example, 10 nm to 300 nm, and preferably 10 nm to 150 nm. The electron transport layer 12 may be omitted.

[0022] The photoelectric conversion layer 13 converts light energy into electrical energy and absorbs, for example, 60% or more of a predetermined wavelength included at least in the visible light to near-infrared light range, thereby separating charges. The photoelectric conversion layer 13 absorbs, for example, 20% or more of light of some or all wavelengths in the near-infrared light range of 900 nm to 1600 nm. The photoelectric conversion layer 13 is configured to contain a plurality of semiconductor nanoparticles. The semiconductor nanoparticles are, for example, semiconductor substances having a crystalline structure of several nanometers in size. The semiconductor nanoparticles contained in the photoelectric conversion layer may be, for example, semiconductor quantum dots having a quantum confinement effect.

[0023] 2 is a schematic diagram showing the cross-sectional structure of a semiconductor quantum dot 130. The semiconductor quantum dot 130 has, for example, a plurality of ligands L coordinated to the surface of a core portion 131. In the photoelectric conversion layer 13 formed in a layered configuration using a plurality of semiconductor quantum dots 130, the plurality of semiconductor quantum dots 130 in the layer are adjacent to each other via the ligands L.

[0024] The core portion 131 is a semiconductor nanoparticle formed of a compound semiconductor. The core portion 131 includes, for example, a III-V group, I-VI group, I-III-V group, or IV-VI group compound semiconductor. As an example, the core portion 131 is made of a binary semiconductor nanoparticle containing indium (In) having n-type conductivity. Specifically, the core portion 131 is made of indium arsenide (InAs).

[0025] The ligand L is an inorganic or organic compound that forms a coordinate bond with a metal ion. The ligand L inactivates highly reactive defects (dangling bonds) present on the surface of the core 131 made of InAs by forming a coordinate bond with the surface. The ligand L has, for example, a chloride ion, a bromide ion, or an iodide ion, or one or both of a thiol group and a carboxyl group having 5 or fewer carbon atoms. Examples of such a ligand L 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, and 4-aminobenzenethiol.

[0026] The plurality of ligands L 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 inorganic or organic compounds. Furthermore, if the length of the ligand L is long, there is a risk of a decrease in the mobility of charge carriers between the semiconductor quantum dots 130. Therefore, the length of the ligand L is preferably, for example, 10 nm or less.

[0027] The thickness of the photoelectric conversion layer 13 is, for example, 10 nm or more and 1000 nm or less, and preferably 30 nm or more and 700 nm or less.

[0028] The hole transport layer 14 selectively transports holes, among the charge carriers generated in the photoelectric conversion layer 13, to the upper electrode 15 while inhibiting the injection of electrons from the upper electrode 15. The hole transport layer 14 has an intramolecular electron-donating molecular structure (donor portion D) and an electron-donating molecular structure (acceptor portion A), and can be formed using an organic material with high crystallinity. For example, the organic material constituting the hole transport layer 14 has a crystallinity of, for example, 57 times or more (a mixture of PTB7-Th and PBDB-T-2F) or 187 times or less (PTB7-Th) compared to the peak intensity when an ITO film with a thickness of 50 nm that has been heat-treated at 150°C for 210 minutes is subjected to XRD measurement using the method described below for measuring crystallinity. The organic material constituting the hole transport layer 14 can be formed, for example, using an organic polymer material with a weight-average molecular weight of 5,000 or more. Examples of such organic polymer materials include copolymers containing, as repeating units, a molecular structure represented by the following formula (1) as the donor moiety D and a molecular structure represented by the following formula (2) as the acceptor moiety A:

[0029] (X is any one of oxygen (O), sulfur (S), selenium (Se), and tellurium (Te). Ar1 is an aryl group.)

[0030] A specific example of the compound represented by the formula (1) above is a benzodithiophene skeleton represented by the following formula (1)′.

[0031]

[0032] Specific organic materials containing the molecular structures represented by the formulas (1) and (2) as repeating units include, for example, Poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7) represented by the following formula (1-1), and Poly([2,6'-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,3-b] dithiophene]{3-fluoro-2[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}) (PTB7-Th), Poly[[4,8-bis[5-(2-ethylhexyl)-2-thienyl] represented by the following formula (1-3) ]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl]-2,5-thiophenediyl[5,7-bis(2-ethylhexyl)-4,8-dioxo-4H,8H-benzo[1,2-c:4,5-c′]dithiophene-1,3-diyl]] polymer (PBDB-T) and benzodithiophene derivatives such as Poly[[4,8-bis[5-(2-ethylhexyl)-4-fluoro-2-thienyl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]-2,5-thiophenediyl[5,7-bis(2-ethylhexyl)-4,8-dioxo-4H,8H-benzo[1,2-c:4,5-c']dithiophene-1,3-diyl]-2,5-thiophenediyl] (PBDB-T-2F) represented by the following formula (1-4).

[0033]

[0034]

[0035] 3 shows a three-dimensional model of PTB7-Th represented by formula (1-1). In the organic material having a benzodithiophene skeleton, the benzodithiophene skeleton portion X has planarity, as shown in FIG.

[0036] In the photoelectric conversion layer 13 made of semiconductor quantum dots (e.g., InAs quantum dots), defects are likely to occur on the surface of the InAs quantum dots where no ligands are present, which causes dark current. As shown in FIG. 4, the organic material (e.g., PTB7-Th) having the donor portion D and the acceptor portion A in the molecule has a defect-causing property that the In of the InAs quantum dots exposed from the ligand at the interface K34 with the photoelectric conversion layer 13 made of InAs quantum dots. ＋ The electron transport layer 14 is coordinated to the electron transport layer 14 via, for example, the donor moiety D. This suppresses the generation of defects on the surface of the photoelectric conversion layer 13 and suppresses the recombination of charges at the interface K34. This reduces dark current. Furthermore, since the above-mentioned organic material has even higher crystallinity and planarity, the benzodithiophene skeleton moiety X, which is responsible for the high planarity, is stacked in the hole transport layer 14. This results in the formation of a hole transport layer 14 with fewer traps and which allows charge carriers to flow more easily.

[0037] The upper electrode 15, like the lower electrode 11, is made of, for example, a conductive film having optical transparency. In particular, the upper electrode 15 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 15 is preferably 0 mΩ·m or more and 3.8 mΩ·m or less. The material constituting the upper electrode 15 may be, for example, InP doped with tin (Sn) as a dopant. ２ O ３ The crystallinity of the ITO thin film may be high or low (approaching amorphous). In addition to the above, the upper electrode 15 may also be made of tin oxide (SnO ２)-based materials, for example, ATO with Sb added as a dopant, and FTO with fluorine (F) 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 15 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 15, 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 15 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 15 include organic materials (conductive polymers) such as PEDOT / PSS. Furthermore, 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 15 can be formed as a single layer or a multilayer film made of the above materials. The thickness of the upper electrode 15 is, for example, 10 nm to 300 nm, and preferably 10 nm to 100 nm.

[0041] It should be noted that other layers may be provided between the lower electrode 11 and the upper electrode 15. For example, a work function adjustment layer may be provided between the hole transport layer 14 and the upper electrode 15. The work function adjustment layer has an electron affinity or work function greater than the work function of the upper electrode 15. The work function adjustment layer also improves the electrical connection between the hole transport layer 14 and the upper electrode 15. The work function adjustment layer may be formed using an organic compound, an oxide semiconductor, or semiconductor nanoparticles. Examples of organic compounds include dipyrazino[2,3-f:2',3'v-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT-CN), PEDOT / PSS, and polyaniline. Examples of oxide semiconductors and semiconductor nanoparticles include MoO ３ , RuO ４ , V １ O ５ and W.O. ３ etc.

[0042] 5 illustrates 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. 13 ) described below.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] The input / output terminal 116 is used to exchange signals with the outside.

[0051] Fig. 6 is a schematic diagram showing an example of a cross-sectional configuration of each unit pixel P of the photodetector 1 shown in Fig. 5. Fig. 7 is an equivalent circuit diagram of each unit pixel P of the photodetector 1 shown in Fig. 6.

[0052] The photodetector 1 has, 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 side, which is the light incident side S1, that absorbs 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 between a lower electrode 11 and an upper electrode 15 arranged opposite each other, an electron transport layer 12, a photoelectric conversion layer 13, and a hole transport layer 14 are stacked in this order from the lower electrode 11 side.

[0053] In the photodetector element 10, light incident on the photodetector element 10 from the upper electrode 15 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 15) 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 15.

[0054] 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.

[0055] 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 planarization layer 16 is provided on the upper electrode 15 of the photodetector element 10, and an optical member such as an on-chip lens 17 is disposed on the planarization layer 16.

[0056] 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.

[0057] 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.

[0058] 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 a pad portion 34 and contact 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.

[0059] 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.

[0060] The reset line and the selection line are each connected to a row scanning section 131 that constitutes a driving circuit. The signal line (data output line) VSL is connected to a horizontal selection section 133 that constitutes a driving circuit.

[0061] The element isolation region 24 has an STI (Shallow Trench Isolation) structure and is made of, for example, silicon oxide.

[0062] 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.

[0063] 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.

[0064] The reset gate 21, the amplifier gate 22, the select gate 23, the through wirings 31 and 33, the wiring 32, the pad portion 34, and the contact 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).

[0065] The planarization layer 16 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 16 is, for example, 100 nm to 30,000 nm. Like the planarization layer 16, the on-chip lens 17 is made of a light-transmitting material.

[0066] [Actions and Effects] In the photodetector element 10 of this embodiment, the hole transport layer 14 containing a crystalline organic material having donor moieties D and acceptor moieties A in its molecules is provided between the photoelectric conversion layer 13 containing semiconductor quantum dots and the upper electrode 15. This suppresses recombination of charges at the interface between the photoelectric conversion layer 13 and the hole transport layer 14. This is described below.

[0067] In recent years, imaging devices using quantum dots in the photoelectric conversion layer have been developed, and improving the heat resistance of semiconductor quantum dots has become an issue. To address this issue, imaging devices using lead sulfide (PbS) quantum dots have been developed. It has been found that by forming an interface layer between the photoelectric conversion layer using PbS quantum dots and the upper electrode, which has a glass transition temperature of 100°C or higher and a hole mobility 10 times higher than that of the photoelectric conversion layer, it is possible to improve the thermal resistance and image retention characteristics.

[0068] However, PbS is subject to the Restriction of Hazardous Substances (RoHS) regulation, which limits its industrial applicability. Therefore, efforts are being made to replace lead-free semiconductor quantum dots. However, when semiconductor quantum dots other than PbS quantum dots are used to form a photoelectric conversion layer, it is unclear what materials are suitable for the interface layer.

[0069] In contrast, in this embodiment, a hole transport layer 14 containing an organic material having the following characteristics is provided between the photoelectric conversion layer 13 containing lead-free semiconductor quantum dots (e.g., InAs quantum dots) and the upper electrode 15. The organic material constituting the hole transport layer 14 has donor moieties D and acceptor moieties A in its molecules and is crystalline. This allows the organic material to coordinate with the semiconductor quantum dots exposed from the ligand at the interface K34 with the photoelectric conversion layer 13, suppressing the generation of defects on the surface of the photoelectric conversion layer 13 and suppressing charge recombination at the interface between the photoelectric conversion layer 13 and the hole transport layer 14. Furthermore, because the organic material has high crystallinity, it stacks within the hole transport layer 14. This reduces traps and facilitates the flow of charge carriers.

[0070] As a result, the photodetector element 10 according to this embodiment can improve its characteristics. Specifically, it can provide a photodetector device 1 that is lead (Pb)-free and has a reduced dark current.

[0071] Next, Modifications 1 to 3, a second embodiment, an application example, an applied example, and examples of the present disclosure will be described. Note that components corresponding to the light-detecting element 10 and the light-detecting device 1 of the above embodiment will be assigned the same reference numerals and will not be described again.

[0072] 8 is a schematic diagram illustrating an example of a cross-sectional configuration of a photodetector element (photodetector element 40) according to Modification 1 of the present disclosure. As in the above embodiment, the photodetector element 40 constitutes one pixel (unit pixel P) in a photodetector device (e.g., photodetector device 1) such as a CMOS image sensor used in electronic devices such as digital still cameras and video cameras. The photodetector element 40 has a configuration in which a lower electrode 41, an electron transport layer 42, a photoelectric conversion layer 43, a hole transport layer 44, and an upper electrode 45 are stacked in this order.

[0073] Here, the lower electrode 41 corresponds to a specific example of a "first electrode" in an embodiment of the present disclosure, and the upper electrode 45 corresponds to a specific example of a "second electrode" in an embodiment of the present disclosure. The photoelectric conversion layer 43 corresponds to a specific example of a "photoelectric conversion layer" in an embodiment of the present disclosure. The hole transport layer 44 corresponds to a specific example of a "first charge transport layer" in an embodiment of the present disclosure, and the electron transport layer 42 corresponds to a specific example of a "second charge transport layer" in an embodiment of the present disclosure.

[0074] The lower electrode 41 is made of, for example, a conductive film having optical transparency. As in the above embodiment, the constituent material of the lower electrode 41 may be, for example, ITO to which Sn is added as a dopant. In addition to the above, the constituent material of the lower electrode 41 may be tin oxide (SnO ２ )-based materials, for example, ATO with Sb added as a dopant, and FTO with F added as a dopant. ZnO or zinc oxide-based materials with dopants added may also be used. ZnO-based materials include, for example, AZO with Al added as a dopant, GZO with Ga added, boron zinc oxide with B added, and IZO with In added. IGZO and In-GaZnO with indium and gallium added as dopants are also suitable. ４ In addition, the lower electrode 41 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.

[0075] Furthermore, when light transmission is not required for the lower electrode 41, a single metal or alloy having a low work function (e.g., φ=3.5 eV to 4.5 eV) can be used, as in the above embodiment. Specific examples include alkali metals (e.g., Li, Na, K, etc.) and their fluorides or oxides, and alkaline earth metals (e.g., Mg, Ca, etc.) and their fluorides or oxides. Other examples include rare earth metals such as Al, Al-Si-Cu alloys, Zn, Sn, Tl, Na-K alloys, Al-Li alloys, Mg-Ag alloys, In, Yb, etc., and alloys thereof.

[0076] Furthermore, examples of materials that can be used to form the lower electrode 41 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 lower electrode 41 include organic materials (conductive polymers) such as poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate (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.

[0077] The lower electrode 41 can be formed as a single layer or a laminated film made of the above materials. The film thickness of the lower electrode 41 in the lamination direction (hereinafter simply referred to as thickness) is, for example, 20 nm to 200 nm, and preferably 30 nm to 150 nm.

[0078] The electron transport layer 42 selectively transports electrons, among the charge carriers generated in the photoelectric conversion layer 43, to the lower electrode 41, while inhibiting the injection of holes from the lower electrode 41. As in the above-described embodiment, the electron transport layer 42 can be formed using an organic compound, an oxide semiconductor, or semiconductor nanoparticles. An n-type semiconductor is preferable as the organic compound, and examples thereof include organometallic dyes formed as complexes between transition metal ions, such as zinc phthalocyanine (II), and organic materials. Other examples of n-type semiconductors include fullerenes or their derivatives, and non-fullerene acceptors, such as ITIC derivatives and BTP derivatives. Examples of oxide semiconductors and semiconductor nanoparticles include TiO ２ , ZnO, ZnS, SrTiO ３ , Nb ２ O ５ , W.O. ３ , In ２ O ３ , CuTiO ３ , SnO ２ , InGaZnO4, InTiO ２ , β-Ga ２ O ３ and other inorganic materials.

[0079] The thickness of the electron transport layer 42 is, for example, 10 nm to 300 nm, and preferably 10 nm to 150 nm. The electron transport layer 42 may be omitted.

[0080] The photoelectric conversion layer 43 converts light energy into electrical energy and absorbs, for example, 60% or more of a predetermined wavelength included at least in the visible light region to the near-infrared region, thereby separating charges. The photoelectric conversion layer 43 absorbs, for example, 20% or more of light having wavelengths in the visible light region and some or all of the near-infrared region, from 900 nm to 1600 nm. As in the above embodiment, the photoelectric conversion layer 43 is configured to include a plurality of semiconductor nanoparticles. The semiconductor nanoparticles are, for example, semiconductor substances having a crystalline structure of several nanometers in size. The semiconductor nanoparticles included in the photoelectric conversion layer may be, for example, semiconductor quantum dots having a quantum confinement effect.

[0081] 2 , the semiconductor quantum dots are, for example, core-shell quantum dots composed of a core 131 and a shell layer 132, and the shell layer 132 has a plurality of ligands L coordinated to the surface of the core 131. In the photoelectric conversion layer 43 formed in a layered configuration using a plurality of semiconductor quantum dots 130, the plurality of semiconductor quantum dots 130 in the layer are adjacent to each other via the ligands L.

[0082] The core portion is a semiconductor nanoparticle formed of a compound semiconductor. The core portion includes, for example, a III-V group, I-VI group, I-III-V group, IV-VI group, or IV-VI group compound semiconductor. As an example, the core portion is made of a binary semiconductor nanoparticle containing In and having n-type conductivity. Specifically, the core portion is made of InAs.

[0083] The shell layer is composed of a plurality of ligands L. The ligands L are organic compounds that form coordinate bonds with metal ions. By forming coordinate bonds with the surface of the core portion made of InAs, the ligands L inactivate highly reactive defects (dangling bonds) present on the surface of the core portion. The ligands L have one or both of a basic group and a weakly acidic group. The ligands L have, for example, one or both of a thiol group and a carboxyl group having 5 or fewer carbon atoms. Examples of such ligands L 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, and 4-aminobenzenethiol.

[0084] The ligands L coordinated to the surface of the core do not have to be a single ligand, but may contain two or more of the above organic compounds. Furthermore, if the length of the ligand L is too long, the mobility of charge carriers between the semiconductor quantum dots may decrease. Therefore, the length of the ligand L is preferably, for example, 10 nm or less.

[0085] The thickness of the photoelectric conversion layer 43 is, for example, 10 nm or more and 1000 nm or less, and preferably 30 nm or more and 700 nm or less.

[0086] The hole transport layer 44 selectively transports holes, among the charge carriers generated in the photoelectric conversion layer 43, to the upper electrode 15 while inhibiting the injection of electrons from the upper electrode 15. As in the above-described embodiment, the hole transport layer 44 has an intramolecular electron-donating molecular structure (donor portion D) and an electron-donating molecular structure (acceptor portion A), and can be formed using an organic material with high crystallinity. For example, the organic material constituting the hole transport layer 14 has a crystallinity of, for example, 57 times or more (a mixture of PTB7-Th and PBDB-T-2F) or 187 times or less (PTB7-Th) compared to the peak intensity obtained when an ITO film with a thickness of 50 nm that has been heat-treated at 150°C for 210 minutes is subjected to XRD measurement using the method described below for measuring crystallinity. The organic material constituting the hole transport layer 44 can be formed, for example, using an organic polymer material with a weight-average molecular weight of 5,000 or more. Examples of such organic polymer materials include copolymers containing, as repeating units, a molecular structure represented by the above formula (1) as the donor portion D and a molecular structure represented by the above formula (2) as the acceptor portion A.

[0087] A specific example of the compound represented by the formula (1) above is the benzodithiophene skeleton represented by the formula (1)′ above.

[0088] Specific examples of organic materials containing the molecular structures represented by the above formulas (1) and (2) as repeating units include benzodithiophene derivatives such as PTB7 represented by the above formula (1-1), PTB7-Th represented by the above formula (1-2), PBDB-T represented by the above formula (1-3), and PBDB-T-2F represented by the above formula (1-4). The hole transport layer 44 of this modified example is formed by mixing two or more of these organic materials.

[0089] The upper electrode 45 is made of, for example, a conductive film having optical transparency, as in the above embodiment. In particular, the upper electrode 45 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 45 is preferably 0 mΩ·m or more and 3.8 mΩ·m or less. Examples of materials constituting the upper electrode 45 include ITO doped with Sn as a dopant. The crystallinity of the ITO thin film may be high or low (approaching amorphous). In addition to the above, other materials constituting the upper electrode 45 include SnO doped with a dopant. ２ Examples of the zinc oxide-based materials include ATO with Sb added as a dopant and FTO with F added as a dopant. ZnO or zinc oxide-based materials with a dopant added may also be used. Examples of the ZnO-based materials include AZO with Al added as a dopant, GZO with Ga added, boron zinc oxide with B added, and IZO with In added. Furthermore, zinc oxide with In and Ga added as dopants (IGZO, In-GaZnO) ４ In addition, the upper electrode 45 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.

[0090] Furthermore, if optical transparency is not required for the upper electrode 45, 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, Ir, Ge, Os, Re, Te, and alloys thereof.

[0091] Furthermore, examples of materials for the upper electrode 45 include metals such as Pt, Au, Pd, Cr, Ni, Al, Ag, Ta, W, Cu, Ti, In, Sn, Fe, Co, and Mo, or alloys containing these metal elements, or 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 for the upper electrode 45 include organic materials (conductive polymers) such as PEDOT / PSS. Alternatively, the above materials may be mixed with a binder (polymer) to form a paste or ink, which may then be cured and used as an electrode.

[0092] The upper electrode 45 can be formed as a single layer or a multilayer film made of the above materials. The thickness of the upper electrode 45 is, for example, 10 nm to 300 nm, and preferably 10 nm to 100 nm.

[0093] Note that other layers may be provided between the lower electrode 41 and the upper electrode 45. For example, a work function adjustment layer may be provided between the hole transport layer 44 and the upper electrode 45, as in the above embodiment.

[0094] In this way, even when a hole transport layer 44 formed by mixing two or more organic materials having donor and acceptor moieties in the molecule and having crystallinity is provided between a photoelectric conversion layer 43 containing lead-free semiconductor quantum dots (e.g., InAs quantum dots) and an upper electrode 45, the same effects as those of the above embodiment can be obtained.

[0095] (2-2. Modification 2) FIG. 9 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. 13 ) 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 (for example, two electrodes: a readout electrode 11A and a storage electrode 11B) and that, for example, an insulating film 18 and an oxide semiconductor layer 19 are provided between the lower electrode 11 and the photoelectric conversion layer 13.

[0096] 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, a wire 32, a pad portion 34, and a contact 35.

[0097] The storage electrode 11B stores 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 a pad unit 36 ​​and a contact 37.

[0098] The insulating film 18 serves to electrically separate the storage electrode 11B from the photoelectric conversion layer 13. The insulating film 18 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 18 above the readout electrode 11A, thereby electrically connecting the readout electrode 11A and the photoelectric conversion layer 13.

[0099] The insulating film 18 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 18 is, for example, 20 nm to 500 nm.

[0100] The oxide semiconductor layer 19 accumulates signal charges generated in the photoelectric conversion layer 13. The oxide semiconductor layer 19 is preferably formed using a material with higher charge mobility and a larger band gap than the photoelectric conversion layer 13. Examples of materials for the oxide semiconductor layer 19 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. The thickness of the oxide semiconductor layer 19 is, for example, 10 nm to 300 nm. By providing the oxide semiconductor layer 19 made of the above materials, signal charges generated in the photoelectric conversion layer 13 are accumulated in the oxide semiconductor layer 19, preventing charge recombination during charge accumulation and improving transfer efficiency.

[0101] 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.

[0102] Although the photodetector 1A has the photodetector element 10 of the embodiment as the photoelectric conversion section, the photodetector element 40 of the first modification can also be used, as in the photodetector 1A.

[0103] (2-3. Modification 3) Figure 10 is a schematic diagram illustrating an example of a cross-sectional configuration of a photodetector (photodetector 1B) according to a modification of the present disclosure. Like the photodetector 1 described above, the photodetector 1B is used in electronic devices (electronic device 1000, see Figure 13) such as CMOS image sensors used in electronic devices such as digital still cameras and video cameras. The photodetector 1B of this modification differs from the above embodiment in that inorganic photodiodes (photoelectric conversion regions 52R, 52B) that detect light in a wavelength range different from that of the photodetector element 10 are provided in the semiconductor substrate 50.

[0104] The semiconductor substrate 50 is, for example, an n-type silicon (Si) substrate and has a p-well 51 in a predetermined region. A second surface 50S2 (the surface of the semiconductor substrate 50) of the p-well 51 is provided with, for example, various floating diffusions (FD) (e.g., FD1, FD2, FD3) and various transistors Tr (e.g., a vertical transistor (transfer transistor) Tr2, a transfer transistor Tr3, an amplifier transistor (modulation element) AMP, and a reset transistor RST). A multilayer wiring layer 60 is further provided on the second surface 50S2 of the semiconductor substrate 50 via a gate insulating layer 68. The multilayer wiring layer 60 has, for example, a configuration in which wiring layers 61, 62, and 63 are stacked within an insulating layer 64. A peripheral circuit (not shown) consisting of a logic circuit or the like is provided on the periphery of the semiconductor substrate 50.

[0105] Between the semiconductor substrate 50 and the lower electrode 11, for example, a layer having a fixed charge (fixed charge layer) 25A, a dielectric layer 25B having insulating properties, and an interlayer insulating layer 28 are provided in this order from the first surface 50S1 side of the semiconductor substrate 50.

[0106] The fixed charge layer 25A may be a film having a positive fixed charge or a film having a negative fixed charge. The fixed charge layer 25A is preferably formed using a semiconductor or conductive material having a wider band gap than the semiconductor substrate 50. This makes it possible to suppress the generation of dark current at the interface of the semiconductor substrate 50. The fixed charge layer 25A may be formed using, for example, hafnium oxide (HfO ｘ ), aluminum oxide (AlO ｘ ), zirconium oxide (ZrO ｘ ), tantalum oxide (TaO ｘ ), titanium oxide (TiO ｘ ), lanthanum oxide (LaO ｘ ), praseodymium oxide (PrO ｘ ), cerium oxide (CeO ｘ ), neodymium oxide (NdO ｘ ), promethium oxide (PmO ｘ ), samarium oxide (SmO ｘ ), europium oxide (EuO ｘ), gadolinium oxide (GdO ｘ ), terbium oxide (TbO ｘ ), dysprosium oxide (DyO ｘ ), holmium oxide (HoO ｘ ), thulium oxide (TmO ｘ ), ytterbium oxide (YbO ｘ ), lutetium oxide (LuO ｘ ), yttrium oxide (YO ｘ ), hafnium nitride (HfN ｘ ), aluminum nitride (AlN ｘ ), hafnium oxynitride (HfO ｘ N ｙ ) and aluminum oxynitride (AlO ｘ N ｙ ) etc.

[0107] The dielectric layer 25B is intended to prevent light reflection caused by the difference in refractive index between the semiconductor substrate 50 and the interlayer insulating layer 28. The constituent material of the dielectric layer 25B is preferably a material having a refractive index between the refractive index of the semiconductor substrate 50 and the refractive index of the interlayer insulating layer 28. The constituent material of the dielectric layer 25B is, for example, SiO ｘ , TEOS, SiN ｘ and SiO ｘ N ｙ etc.

[0108] The photoelectric conversion regions 52B and 52R are configured, for example, by PIN (Positive Intrinsic Negative) type photodiodes, and each has a pn junction in a predetermined region of the semiconductor substrate 50. The photoelectric conversion regions 52B and 52R are capable of splitting light in the vertical direction by utilizing the fact that the wavelength range absorbed varies depending on the depth of incidence of light in the silicon substrate.

[0109] The photoelectric conversion region 52B selectively detects, for example, blue light and accumulates signal charges corresponding to the blue color, and is formed at a depth that allows efficient photoelectric conversion of the blue light. The photoelectric conversion region 52R selectively detects, for example, red light and accumulates signal charges corresponding to the red color, and is formed at a depth that allows efficient photoelectric conversion of the red light. Note that blue (B) corresponds to, for example, a wavelength range of 400 nm or more and less than 495 nm, and red (R) corresponds to, for example, a wavelength range of 620 nm or more and less than 750 nm. Each of the photoelectric conversion regions 52B and 52R may be capable of detecting light in some or all of the wavelength ranges.

[0110] 10, the photoelectric conversion regions 52B and 52R each have, for example, a p+ region that serves as a hole accumulation layer and an n region that serves as an electron accumulation layer (having a p-n-p stacked structure). The n region of the photoelectric conversion region 52B is connected to the vertical transistor Tr2. The p+ region of the photoelectric conversion region 52B bends along the vertical transistor Tr2 and is connected to the p+ region of the photoelectric conversion region 52R.

[0111] The gate insulating layer 68 is made of, for example, SiO ｘ , SiN ｘ and SiO ｘ N ｙ It is composed of a single layer film made of one of the above or a laminated film made of two or more of these.

[0112] A through electrode 53 is provided between the first surface 50S1 and the second surface 50S2 of the semiconductor substrate 50. The through electrode 53 functions as a connector between the photodetection element 10 and the gate Gamp of the amplifier transistor AMP and the floating diffusion FD1, and also serves as a transmission path for charges generated in the photodetection element 10. A reset gate Grst of the reset transistor RST is disposed adjacent to the floating diffusion FD1 (one of the source / drain regions 56B of the reset transistor RST). This allows the charges accumulated in the floating diffusion FD1 to be reset by the reset transistor RST.

[0113] The upper end of the through electrode 53 is connected to the read electrode 11A via, for example, a pad portion 34 and a contact 35 provided in the interlayer insulating layer 28. The lower end of the through electrode 53 is connected to a connection portion 61A in the wiring layer 61, and the connection portion 61A and the gate Gamp of the amplifier transistor AMP are connected via a contact 65. The connection portion 61A and the floating diffusion FD1 (region 56B) are connected via, for example, a contact 66.

[0114] The contacts 35, 37, pad portions 34, 36, wiring layers 61, 62, 63, contacts 65, 66, and gate wiring layer 67 can be formed using, for example, a doped silicon material such as PDAS (Phosphorus Doped Amorphous Silicon), or a metal material such as Al, W, Ti, Co, Hf, and Ta.

[0115] The insulating layer 64 is made of, for example, SiO ｘ , SiN ｘ and SiO ｘ N ｙ It is composed of a single layer film made of one of the above or a laminated film made of two or more of these.

[0116] A light-shielding film 69 is provided in the planarization layer 16. The light-shielding film 69 is provided, for example, so as to cover at least the region of the readout electrode 11A that is in direct contact with the oxide semiconductor layer 19, but not to cover the storage electrode 11B. The light-shielding film 69 can be formed using, for example, W, Al, an alloy of Al and Cu, or the like.

[0117] As described above, the configuration of the photodetector is not limited to the photodetector 1 of the above embodiment, and the semiconductor substrate 20 may be provided with one or more photoelectric conversion units (e.g., photoelectric conversion regions 52B, 52R) that detect light in a wavelength range different from that of the photodetector element 10. The photodetector 1B of this modification can also achieve the same effects as those of the above embodiment. In addition, the photodetector 1B of this modification can expand the detectable wavelength range.

[0118] Although the photodetector 1B has the photodetector element 10 of the embodiment as a photoelectric conversion unit, the photodetector element 40 of the modified example 1 can also be used, as in the photodetectors 1 and 1A.

[0119] 3. Second Embodiment FIG. 11 is a schematic diagram illustrating an example of a cross-sectional configuration of a photodetector (photodetector element 70) according to a second embodiment of the present disclosure. The photodetector element 70 constitutes one pixel (unit pixel P) in a photodetector device (photodetector device 1, see FIG. 5 ), such as a CMOS image sensor used in electronic devices such as digital still cameras and video cameras. The photodetector element 70 includes a photoelectric conversion layer 74 between a lower electrode 71 and an upper electrode 75, which are arranged opposite each other. An intermediate layer 76 and a hole transport layer 74 are sequentially arranged between the photoelectric conversion layer 74 and the upper electrode 75. In this embodiment, similar to the above-described embodiments, the photoelectric conversion layer 74 includes semiconductor nanoparticles, and the hole transport layer 74 is formed using a crystalline organic material having intramolecular donor and acceptor moieties. The intermediate layer 76 is formed using semiconductor nanoparticles having a particle diameter smaller than that of the semiconductor nanoparticles used in the photoelectric conversion layer 74.

[0120] [Configuration of Photodetection Element] The photodetection element 70 has a configuration in which a lower electrode 71, an electron transport layer 72, a photoelectric conversion layer 74, an intermediate layer 76, a hole transport layer 74, and an upper electrode 75 are stacked in this order. In the photodetection element 70, of electron-hole pairs generated by photoelectric conversion, for example, electrons are read out as signal charges from the lower electrode 71 side. Below, the configuration, materials, etc. of each part will be described using as an example a case in which electrons are read out as signal charges from the lower electrode 71 side.

[0121] Here, the lower electrode 71 corresponds to a specific example of a "first electrode" in an embodiment of the present disclosure, and the upper electrode 75 corresponds to a specific example of a "second electrode" in an embodiment of the present disclosure. The photoelectric conversion layer 74 corresponds to a specific example of a "photoelectric conversion layer" in an embodiment of the present disclosure. The intermediate layer 76 corresponds to a specific example of an "intermediate layer" in an embodiment of the present disclosure. The hole transport layer 74 corresponds to a specific example of a "first charge transport layer" in an embodiment of the present disclosure, and the electron transport layer 72 corresponds to a specific example of a "second charge transport layer" in an embodiment of the present disclosure.

[0122] The lower electrode 71 is made of, for example, a light-transmitting conductive film. The material of the lower electrode 71 is, for example, InP doped with tin (Sn). ２ O ３ In addition to the above, the lower electrode 71 may be made of tin oxide (SnO ２ )-based materials, for example, ATO with Sb added as a dopant, and FTO with fluorine (F) 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 lower electrode 71 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.

[0123] Furthermore, if the lower electrode 71 does not require optical transparency, 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.

[0124] Furthermore, examples of materials that can be used to form the lower electrode 71 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, polysilicon containing impurities, carbon-based materials, oxide semiconductors, carbon nanotubes, and graphene. Other examples of materials that can be used to form the lower electrode 71 include organic materials (conductive polymers) such as poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate (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.

[0125] The lower electrode 71 can be formed as a single layer or a laminated film made of the above materials. The film thickness of the lower electrode 71 in the lamination direction (hereinafter simply referred to as thickness) is, for example, 20 nm to 200 nm, and preferably 30 nm to 150 nm.

[0126] The electron transport layer 72 selectively transports electrons, among the charge carriers generated in the photoelectric conversion layer 74, to the lower electrode 71, while inhibiting the injection of holes from the lower electrode 71 side. The electron transport layer 72 can be formed using an organic compound, an oxide semiconductor, or semiconductor nanoparticles. An n-type semiconductor is preferable as the organic compound, and examples thereof include organometallic dyes formed as complexes between transition metal ions, such as zinc phthalocyanine (II), and organic materials. Other examples of n-type semiconductors include fullerenes or derivatives thereof, and non-fullerene acceptors, such as ITIC derivatives and BTP derivatives. Examples of oxide semiconductors and semiconductor nanoparticles include titanium oxide (TiO ２ ), zinc oxide (ZnO), zinc sulfide (ZnS), SrTiO ３ , niobium oxide (Nb ２ O ５ ), tungsten oxide (WO ３ ), indium oxide (In ２ O ３ ), CuTiO ３ , tin oxide (SnO ２ ), InGaZnO4, InTiO ２ and β-Ga ２ O ３ and other inorganic materials.

[0127] The thickness of the electron transport layer 72 is, for example, 10 nm to 300 nm, and preferably 10 nm to 150 nm. The electron transport layer 72 may be omitted.

[0128] The photoelectric conversion layer 74 converts light energy into electrical energy and absorbs, for example, 60% or more of a predetermined wavelength included at least in the visible light to near-infrared light range, thereby separating charges. The photoelectric conversion layer 74 absorbs, for example, 20% or more of light of some or all wavelengths in the near-infrared light range of 900 nm to 1600 nm. The photoelectric conversion layer 74 is configured to contain a plurality of semiconductor nanoparticles. The semiconductor nanoparticles are, for example, semiconductor substances having a crystalline structure of several nanometers in size. The semiconductor nanoparticles contained in the photoelectric conversion layer may be, for example, semiconductor quantum dots having a quantum confinement effect.

[0129] The thickness of the photoelectric conversion layer 74 is, for example, 10 nm or more and 1000 nm or less, and preferably 30 nm or more and 700 nm or less.

[0130] The intermediate layer 76 is intended to reduce the surface roughness of the photoelectric conversion layer 74 and form a good interface between the photoelectric conversion layer 74 and, for example, the hole transport layer 74. The intermediate layer 76 is composed of semiconductor nanoparticles having a particle size smaller than that of the semiconductor nanoparticles constituting the photoelectric conversion layer 74. For example, the semiconductor nanoparticles constituting the intermediate layer 76 have a particle size distribution of 2 nm to 4 nm. The intermediate layer 76 is preferably larger than the band gap (Bg) of the photoelectric conversion layer 74. The intermediate layer 76 is preferably at or shallower than the valence band rear end (VBM) of the photoelectric conversion layer 74. The intermediate layer 76 can be formed using the same material as the photoelectric conversion layer 74.

[0131] The thickness of the intermediate layer 76 is, for example, 10 nm or more and 100 nm or less, and preferably 10 nm or more and 50 nm or less.

[0132] The hole transport layer 74 selectively transports holes, among the charge carriers generated in the photoelectric conversion layer 74, to the upper electrode 75 while inhibiting the injection of electrons from the upper electrode 75. The hole transport layer 74 has an intramolecular electron-donating molecular structure (donor portion D) and an electron-donating molecular structure (acceptor portion A), and can be formed using an organic material with high crystallinity. For example, the organic material constituting the hole transport layer 74 has a crystallinity of, for example, 57 times or more (a mixture of PTB7-Th and PBDB-T-2F) or 187 times or less (PTB7-Th) compared to the peak intensity when an ITO film with a thickness of 50 nm that has been heat-treated at 150°C for 210 minutes is subjected to XRD measurement using the method described below for measuring crystallinity. The organic material constituting the hole transport layer 74 can be formed, for example, using an organic polymer material with a weight-average molecular weight of 5,000 or more. As in the first embodiment, such an organic polymer material may be, for example, a copolymer containing, as repeating units, a molecular structure represented by the above formula (1) as the donor moiety D and a molecular structure represented by the above formula (2) as the acceptor moiety A. The hole transport layer 74 may be omitted.

[0133] The upper electrode 75, like the lower electrode 71, is made of, for example, a conductive film having optical transparency. In particular, the upper electrode 75 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 75 is preferably 0 mΩ·m or more and 3.8 mΩ·m or less. The material constituting the upper electrode 75 may be, for example, InP doped with tin (Sn) as a dopant. ２ O ３ The crystallinity of the ITO thin film may be high or low (approaching amorphous). In addition to the above, the upper electrode 75 may also be made of tin oxide (SnO ２ )-based materials, for example, ATO with Sb added as a dopant, and FTO with fluorine (F) 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 75 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.

[0134] Furthermore, if optical transparency is not required for the upper electrode 75, 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.

[0135] Furthermore, examples of materials that can be used to form the upper electrode 75 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 75 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.

[0136] The upper electrode 75 can be formed as a single layer or a laminated film made of the above materials. The thickness of the upper electrode 75 is, for example, 10 nm to 300 nm, and preferably 10 nm to 100 nm.

[0137] It should be noted that other layers may be provided between the lower electrode 71 and the upper electrode 75. For example, a work function adjustment layer may be provided between the hole transport layer 74 and the upper electrode 75. The work function adjustment layer has an electron affinity or work function greater than the work function of the upper electrode 75. The work function adjustment layer also improves the electrical connection between the hole transport layer 74 and the upper electrode 75. The work function adjustment layer may be formed using an organic compound, an oxide semiconductor, or semiconductor nanoparticles. Examples of organic compounds include dipyrazino[2,3-f:2',3'v-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT-CN), PEDOT / PSS, and polyaniline. Examples of oxide semiconductors and semiconductor nanoparticles include MoO３ , RuO ４ , V １ O ５ and W.O. ３ etc.

[0138] [Actions and Effects] In the photodetector element 70 of this embodiment, an intermediate layer 76 containing semiconductor nanoparticles with a particle size smaller than that of the semiconductor quantum dots constituting the photoelectric conversion layer 74 is provided between the photoelectric conversion layer 74 containing semiconductor quantum dots and the hole transport layer 74 containing an organic material having donor moieties D and acceptor moieties A in the molecules and having crystallinity. This improves the smoothness of the upper surface of the photoelectric conversion layer 74 facing the upper electrode 75. In this embodiment, a good interface is formed between the photoelectric conversion layer 74 and the hole transport layer 74. This will be described below.

[0139] A photoelectric conversion layer formed using semiconductor nanoparticles of several nanometers in size (e.g., an average particle size of 5 nm or more) has unevenness on the surface, resulting in large surface roughness (e.g., arithmetic mean roughness Ra = ±3 nm). When a hole transport layer is formed on a photoelectric conversion layer with large surface roughness, the hole transport layer cannot enter the recessed portions of the photoelectric conversion layer surface, resulting in voids. As a result, there is a risk of a decrease in external quantum efficiency (EQE) or a decrease in reliability, such as film peeling due to a decrease in adhesion. Furthermore, even if the hole transport layer enters the recessed portions of the photoelectric conversion layer surface, the thickness of the hole transport layer in the in-plane direction varies greatly. For example, the thickness of the hole transport layer becomes too thick in the recessed portions, which may result in a decrease in EQE. On the other hand, the thickness of the hole transport layer becomes thin in the protruding portions, making it impossible to obtain sufficient performance as a hole transport layer, which may, for example, worsen dark current or cause a short circuit. Furthermore, when a photoelectric conversion layer is formed using semiconductor nanoparticles with even larger particle sizes, the gaps between the particles become larger, causing the hole transport layer to penetrate into the inside of the photoelectric conversion layer, and if it reaches the electron transport layer, for example, it may cause a short circuit.

[0140] In contrast, in the present embodiment, an intermediate layer 76 containing semiconductor nanoparticles having a particle size smaller than that of the semiconductor quantum dots constituting the photoelectric conversion layer 74 is provided between the photoelectric conversion layer 74 containing semiconductor quantum dots and the hole transport layer 74. FIG. 12 is a schematic representation of the surface structure of the photoelectric conversion layer 74, showing the intermediate layer 76 and hole transport layer 74 stacked on the photoelectric conversion layer 74. For example, a photoelectric conversion layer 74 formed using semiconductor quantum dots 730 with an average particle size of 5 nm or more has an uneven surface as shown in FIG. 12. When an intermediate layer 76 using semiconductor nanoparticles 760 having a particle size smaller than that of the semiconductor quantum dots 730 is formed on this photoelectric conversion layer 74, the semiconductor nanoparticles 760 penetrate into the uneven surface of the photoelectric conversion layer 74, suppressing the formation of voids. As a result, a decrease in EQE is suppressed, and the adhesion between the photoelectric conversion layer 74 and the hole transport layer 74 is improved. Furthermore, the semiconductor nanoparticles 760 constituting the intermediate layer 76 have a particle size distribution smaller than that of the semiconductor quantum dots 730 constituting the photoelectric conversion layer 74, for example, 2 nm to 4 nm. Therefore, the surface roughness is smaller than that of the photoelectric conversion layer 74 (for example, arithmetic mean roughness Ra = ±0.52 nm). Therefore, a hole transport layer 74 of a desired thickness can be formed on the intermediate layer 76. This prevents deterioration of EQE and dark current and the occurrence of short circuits. Furthermore, because the intermediate layer 76 has small gaps between particles formed on the photoelectric conversion layer 74, penetration of the hole transport layer 74 into the photoelectric conversion layer 74 can be prevented. This prevents the occurrence of short circuits.

[0141] As a result, the photodetector element 70 of this embodiment can have improved characteristics compared to the photodetector element 10 of the first embodiment. Specifically, it is possible to provide a photodetector device 1 that is lead (Pb)-free and has excellent electrical characteristics such as suppressed dark current and improved EQE. In addition, it is possible to improve reliability.

[0142] 4. Application Examples Application Example 1 The photodetector according to the present disclosure (e.g., photodetector 1) can be applied to various electronic devices, such as imaging systems such as digital still cameras and digital video cameras, mobile phones with an imaging function, or other devices with an imaging function.

[0143] FIG. 13 is a block diagram showing an example of the configuration of electronic device 1000. As shown in FIG.

[0144] As shown in FIG. 13, electronic device 1000 includes an optical system 1001, a photodetector (e.g., photodetector 1), and a DSP (Digital Signal Processor) 1002, and is configured by connecting DSP 1002, memory 1003, display device 1004, recording device 1005, operation system 1006, and power supply system 1007 via a bus 1008, and is capable of capturing still images and moving images.

[0145] 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 .

[0146] 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.

[0147] 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.

[0148] 14A is a schematic diagram illustrating an example of the overall configuration of a light detection system 2000 including a light detection device (e.g., the light detection device 1). FIG. 14B is a diagram illustrating 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 L2, 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.

[0149] The photodetector 2002 can detect light L1 and light L2. Light L1 is external ambient light reflected by a subject (object to be measured) 2100 ( FIG. 14A ). Light L2 is light emitted by the light-emitting device 2001 and then reflected by the subject 2100. Light L1 is, for example, visible light, and light L2 is, for example, infrared light. Light L1 can be detected by a photoelectric conversion unit in the photodetector 2002, and light L2 can be detected by a photoelectric conversion region in the photodetector 2002. Image information of the subject 2100 can be obtained from light L1, and distance information between the subject 2100 and the photodetector system 2000 can be obtained from light L2. The photodetector system 2000 can be mounted, for example, on 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, by a semiconductor laser, a surface-emitting semiconductor laser, or a vertical-cavity surface-emitting laser (VCSEL). The method of detecting the light L2 emitted from the light-emitting device 2001 by the photodetector 2002 can be, for example, an iTOF method, but is not limited to this. In the iTOF method, the photoelectric conversion unit can measure the distance to the subject 2100, for example, by using the time-of-flight (TOF) of light. The method of detecting the light L2 emitted from the light-emitting device 2001 by the photodetector 2002 can also be, for example, a structured light method or a stereo vision method. For example, in the structured light method, a predetermined pattern of light is projected onto the subject 2100, and the distance between the photodetector 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 measuring the distance between the photodetector system 2000 and the subject. The light emitting device 2001 and the light detecting device 2002 can be controlled synchronously by a system control unit 2003 .

[0150] 5. 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.

[0151] FIG. 15 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.

[0152] 15 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.

[0153] 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.

[0154] 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.

[0155] 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 onto the image sensor by the optical system. 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.

[0156] 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 image processing on the image signal, such as development processing (demosaic processing), to display an image based on the image signal.

[0157] 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.

[0158] 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.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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, 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. Fluorescence observation can involve irradiating excitation light onto body tissues and observing the fluorescence from the tissues (autofluorescence observation), or by locally injecting a reagent such as indocyanine green (ICG) into the body tissue and irradiating the tissue with excitation light corresponding to the fluorescent wavelength of the reagent 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.

[0164] FIG. 16 is a block diagram showing an example of the functional configuration of the camera head 11102 and the CCU 11201 shown in FIG.

[0165] 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.

[0166] 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.

[0167] 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 a 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.

[0168] 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.

[0169] 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.

[0170] 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.

[0171] 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.

[0172] 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.

[0173] 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 .

[0174] 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.

[0175] 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.

[0176] The image processing unit 11412 performs various image processing operations on the image signal, which is RAW data transmitted from the camera head 11102 .

[0177] 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.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] The above describes an example of an endoscopic surgery system to which the technology disclosed herein can be applied. The technology disclosed herein can be applied to the imaging unit 11402 among the components described above. Applying the technology disclosed herein to the imaging unit 11402 improves detection accuracy.

[0182] Although an endoscopic surgery system has been described as an example here, the technology disclosed herein may also be applied to other systems, such as a microsurgery system.

[0183] (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).

[0184] FIG. 17 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.

[0185] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 17, 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.

[0186] 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.

[0187] 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.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] 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 distance between vehicles, maintaining vehicle speed, vehicle collision warning, vehicle lane departure warning, etc.

[0192] 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.

[0193] 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.

[0194] 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. 17, 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.

[0195] FIG. 18 is a diagram showing an example of the installation position of the imaging unit 12031.

[0196] In FIG. 18, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0197] 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.

[0198] 18 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.

[0199] 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.

[0200] 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.

[0201] 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.

[0202] 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.

[0203] 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 devices according to the above-described embodiments and their modifications (e.g., photodetection device 1) 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 high-resolution captured images with little noise, thereby enabling high-precision control using the captured images in the mobile object control system.

[0204] 6. Examples [Experiment 1] (Experimental Example 1) First, a 50-nm-thick ITO film was formed on a silicon substrate using a sputtering device, and then processed by photolithography and etching to form a lower electrode. Next, the silicon substrate was subjected to UV / ozone treatment, and then an electron transport layer, a photoelectric conversion layer, and a hole transport layer were sequentially formed on the lower electrode using, for example, a spin coater. Specifically, a 100-nm-thick ZnO film was formed, which served as the electron transport layer. A 150-nm-thick layer composed of InAs quantum dots was formed, which served as the photoelectric conversion layer. A 30-50-nm-thick film composed of PTB7 represented by the above formula (1-1) was formed, which served as the hole transport layer. Finally, the silicon substrate was transferred to a sputtering device, and a 50-nm-thick ITO film was formed on the hole transport layer, which served as the upper electrode. This was used as an evaluation device.

[0205] (Experimental Example 2) An evaluation element was fabricated in the same manner as in Experimental Example 1, except that the hole transport layer was formed using PTB7-Th represented by the above formula (1-2) instead of PTB7 used in Experimental Example 1.

[0206] Experimental Example 3 An evaluation element was produced in the same manner as in Experimental Example 1, except that the hole transport layer was formed using PBDB-T represented by the above formula (1-3) instead of PTB7 used in Experimental Example 1.

[0207] (Experimental Example 4) An evaluation element was produced in the same manner as in Experimental Example 1, except that the hole transport layer was formed using PBDB-T-2F shown in the above formula (1-4) instead of PTB7 used in Experimental Example 1.

[0208] (Experimental Example 5) An evaluation element was produced using the same method as in Experimental Example 1, except that a hole transport layer was formed by mixing PTB7-Th shown in the above formula (1-2) and PBDB-T-2F shown in the above formula (1-4) instead of PTB7 used in Experimental Example 1.

[0209] (Experimental Example 6) Instead of PTB7 used in Experimental Example 1, N 2 ,N 2 ,N 2′ ,N 2′ ,N 7 ,N 7 ,N7′ ,N 7′ An evaluation element was fabricated using the same method as in Experimental Example 1, except that the hole transport layer was formed using 4-octakis(4-methoxyphenyl)-9,9'-spirobi[9H-fluorene]-2,2',7,7'-tetramine (Spiro-MeOTAD).

[0210]

[0211] (Experimental Example 7) Instead of PTB7 used in Experimental Example 1, 9,9'-[1,2-Phenylenebis(methylene)]bis[N 3 ,N 3 ,N 6 ,N 6 An evaluation element was prepared in the same manner as in Experimental Example 1, except that the hole transport layer was formed using -tetrakis(4-methoxyphenyl)-9H-carbazole-3,6-diamine (V886).

[0212]

[0213] (Experimental Example 8) An evaluation element was fabricated in the same manner as in Experimental Example 1, except that the hole transport layer was formed using Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) represented by the following formula (4) instead of PTB7 used in Experimental Example 1.

[0214]

[0215] Experimental Example 9 An evaluation element was produced in the same manner as in Experimental Example 1, except that a hole transport layer was formed by mixing Poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine] (Poly-TPD) shown in the following formula (5) and PBDB-T-2F shown in the above formula (1-4) instead of PTB7 used in Experimental Example 1.

[0216]

[0217] 19 summarizes the vacuum levels of InAs, PTB7 (Experimental Example 1), PTB7-Th (Experimental Example 2), PBDB-T (Experimental Example 3), PBDB-T-2F (Experimental Example 4), Spiro-MeOTAD (Experimental Example 6), V886 (Experimental Example 7), PTAA (Experimental Example 8), and Poly-TPD (Experimental Example 9) used in Experimental Examples 1 to 9. FIG. 20 summarizes the dark current results for Experimental Examples 1 to 9. FIG. 21 summarizes the relationship between dark current and crystallinity for Experimental Examples 1 to 9.

[0218] [Method for Measuring Dark Current] Dark current was measured using a semiconductor parameter analyzer for Experimental Examples 1 to 9. Specifically, a bias voltage applied between the electrodes of the evaluation element in the dark was controlled, and the voltage applied to the lower electrode relative to the upper electrode was swept to obtain a current-voltage curve.

[0219] [Method for Measuring Crystallinity] XRD was measured for PTB7 (Experimental Example 1), PTB7-Th (Experimental Example 2), PBDB-T (Experimental Example 3), PBDB-T-2F (Experimental Example 4), Spiro-MeOTAD (Experimental Example 6), V886 (Experimental Example 7), PTAA (Experimental Example 8), and Poly-TPD (Experimental Example 9) used in Experimental Examples 1 to 4 and 6 to 9.

[0220] Specifically, each of the organic materials was first dissolved in chlorobenzene to a concentration of 10 mg / mL to prepare an ink containing each organic material. Next, a 100 nm ITO film was formed on a 1-inch quartz substrate using sputtering, and the quartz substrate was then heat-treated at 150°C for 210 minutes. The quartz substrate was then subjected to UV ozone treatment at 80°C for 10 minutes in a nitrogen atmosphere. Subsequently, 80 μL of each ink at a concentration of 10 mg / mL (solvent: chlorobenzene) was used to form a coating film using a spin coater in a nitrogen atmosphere. The coating film was then dried on a hot plate at 100°C for 10 minutes. The resulting coating film was subjected to XRD measurement under the following conditions.

[0221] (XRD measurement conditions) X-ray target: Cu Wavelength: 1.54A Measurement method: Thin film method, θ angle is fixed and 2θ is scanned. θ: 0.18° (fixed) 2θ: 2° to 35° (XRD pattern fitting method) The XRD pattern was fitted using the nonlinear least squares method. The reference ITO peak is a peak that appears around 30° to 31°, and the peak of the organic material is a halo peak that appears around 15° to 30°. (Area calculation method) The peak area was calculated using Simpson's integral method.

[0222] In each experimental example, the peak intensity (peak area) of each organic material obtained by the above calculation method divided by the peak intensity (peak area) of ITO obtained by the above calculation method corresponds to the horizontal axis shown in FIG. 21 (a value normalized based on the peak area of ​​the ITO XRD spectrum).

[0223] 20, Experimental Examples 1 to 5, which used organic materials having a benzodithiophene skeleton that have donor and acceptor moieties in the molecule and are crystalline, were confirmed to have reduced dark current compared to Experimental Examples 6 to 9, which used non-benzodithiophene organic materials. Also, as can be seen from Fig. 21, Experimental Examples 1 to 5, which have a high degree of crystallinity, were confirmed to have reduced dark current compared to Experimental Examples 6 to 9, which used non-benzodithiophene organic materials.

[0224] [Experiment 2] (Experimental Example 10) First, a 50 nm thick ITO film was formed on a silicon substrate using a sputtering device, and then processed by photolithography and etching to form a lower electrode. Next, the silicon substrate was subjected to UV / ozone treatment, and then an electron transport layer, a photoelectric conversion layer, and a hole transport layer were sequentially formed on the lower electrode using, for example, a spin coater. Specifically, a 100 nm thick ZnO film was formed, which served as the electron transport layer. A 150 nm thick layer of InAs quantum dots A was formed, which served as the photoelectric conversion layer. A 30-50 nm thick film of PTB7-Th represented by the above formula (1-2) was formed, which served as the hole transport layer. Finally, the silicon substrate was transferred to a sputtering device, and a 50 nm thick ITO film was formed on the hole transport layer, which served as the upper electrode. This was used as an evaluation device.

[0225] (Experimental Example 11) An evaluation element was fabricated using the same method as in Experimental Example 10, except that an intermediate layer made of InAs quantum dots D having a smaller particle diameter than the InAs quantum dots A used in the photoelectric conversion layer was formed between the photoelectric conversion layer and the hole transport layer.

[0226] Experimental Example 12 An evaluation element was fabricated using the same method as in Experimental Example 10, except that the photoelectric conversion layer was formed using InAs quantum dots B instead of the InAs quantum dots A used in Experimental Example 10.

[0227] (Experimental Example 13) An evaluation element was fabricated using the same method as in Experimental Example 12, except that an intermediate layer made of InAs quantum dots D having a smaller particle diameter than the InAs quantum dots B used in the photoelectric conversion layer was formed between the photoelectric conversion layer and the hole transport layer.

[0228] Experimental Example 14 An evaluation element was fabricated using the same method as in Experimental Example 10, except that a photoelectric conversion layer was formed using InAs quantum dots C instead of the InAs quantum dots A used in Experimental Example 10, an intermediate layer was formed using InAs quantum dots D having a smaller particle diameter than the InAs quantum dots C used in the photoelectric conversion layer, and the hole transport layer was omitted.

[0229] Experimental Example 15 An evaluation element was fabricated using the same method as in Experimental Example 14, except that a hole transport layer made of PTB7-Th represented by formula (1-2) was formed on the intermediate layer between the photoelectric conversion layer and the upper electrode in the same manner as in Experimental Example 10.

[0230] The InAs quantum dots A, B, C, and D are InAs quantum dots having different compositions, and the InAs quantum dots D used in the intermediate layer have a smaller particle diameter than the InAs quantum dots A, B, and C used in the photoelectric conversion layer.

[0231] [Evaluation of Dark Current and External Quantum Efficiency] Dark current was measured for Experimental Examples 10 to 15 using a semiconductor parameter analyzer. Specifically, the bias voltage applied between the electrodes of the evaluation device in the dark was controlled, and the voltage applied to the lower electrode relative to the upper electrode was swept to obtain a current-voltage curve. The dark current value and the bright current value were obtained under a reverse bias condition (a condition in which a voltage of +2.6 V was applied), 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.

[0232] FIG. 22 shows the evaluation results of dark current for Experimental Examples 10 to 15. Experimental Examples 11 and 13, which included an intermediate layer containing semiconductor nanoparticles with a particle size smaller than that of the semiconductor quantum dots constituting the photoelectric conversion layer, were found to have reduced dark current compared to Experimental Examples 10 and 12, which did not include an intermediate layer. Furthermore, Experimental Example 14, which included an intermediate layer on the photoelectric conversion layer without a hole transport layer, and Experimental Example 15, which also included a hole transport layer, showed a reduction in dark current. This indicates that the addition of a hole transport layer improves dark current. Although not shown in FIG. 22, a device in which a photoelectric conversion layer was formed using InAs quantum dots C and a hole transport layer made of PTB7-Th represented by formula (1-2) was provided on the photoelectric conversion layer, showed a reduction in dark current between that of Experimental Example 14 and Experimental Example 15.

[0233] Figure 23 shows the evaluation results of the EQE for Experimental Examples 10 to 13. Experimental Examples 11 and 13, which included an intermediate layer containing semiconductor nanoparticles with a particle size smaller than that of the semiconductor quantum dots constituting the photoelectric conversion layer, were found to have improved EQE compared to Experimental Examples 10 and 12, which did not include an intermediate layer. Although not shown in Figure 23, an improvement in EQE was confirmed in Experimental Example 15, which further included a hole transport layer on the intermediate layer, compared to Experimental Example 14 and Experimental Example 15. Furthermore, in a device in which a photoelectric conversion layer was formed using InAs quantum dots C and a hole transport layer made of PTB7-Th shown in formula (1-2) was provided on the photoelectric conversion layer without an intermediate layer, an improvement in EQE was confirmed to be approximately between that of Experimental Example 14 and Experimental Example 15.

[0234] The present technology has been described above using the first and second embodiments, Modifications 1 to 3, application examples, and examples. However, the present disclosure is not limited to the above-described embodiments and can be modified in various ways. For example, while the above-described embodiments and examples illustrate examples in which electrons are read out from the lower electrode 11 as signal charges, this is not limiting. Holes may also be read out from the lower electrode 11 as signal charges. In this case, the stacking order of the layers of the photodetector element 10 shown in FIG. 1 is reversed. That is, the layers are stacked in order from the upper electrode 15 toward the light incident side S1.

[0235] Furthermore, the photodetector 1 and electronic device 1000 of the present disclosure do not need to include all of the components described in the above embodiments, etc. Conversely, other components may be included. For example, the electronic device 1000 may be provided with a shutter for controlling the incidence of light on the photodetector 1, or may be provided with an optical cut filter depending on the purpose of the electronic device 1000.

[0236] Furthermore, although the above-described embodiments and the like have shown examples in which the photodetector element 10 is applied to the photodetector device 1, the photodetector element 10 of the present disclosure may also be applied to a solar cell. When applied to a solar cell, the photoelectric conversion layer 13 formed of an aggregate of semiconductor quantum dots 130 is preferably designed to broadly absorb wavelengths of, for example, 400 nm to 800 nm.

[0237] The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0238] The present technology can also be configured as follows. According to the present technology configured as follows, a first charge transport layer having donor and acceptor moieties in its molecules and containing a crystalline organic material is provided between a photoelectric conversion layer containing semiconductor quantum dots and a second electrode, thereby suppressing charge recombination at the interface between the photoelectric conversion layer and the first charge transport layer. Furthermore, an intermediate layer containing second semiconductor quantum dots having a particle size smaller than the first semiconductor quantum dots is provided between the photoelectric conversion layer containing first semiconductor quantum dots and the second electrode, thereby improving the smoothness of the upper surface of the photoelectric conversion layer facing the second electrode. This enables improved characteristics. [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 containing semiconductor quantum dots; and a first charge transport layer disposed between the photoelectric conversion layer and the second electrode, the first charge transport layer having donor and acceptor moieties in its molecules and containing a crystalline organic material. [2] The photodetector according to [1], wherein the semiconductor quantum dots are semiconductor nanoparticles of a group III-V, a group I-VI, a group I-III-V, a group I-V-VI, or a group IV-VI. [3] The photodetector according to [1] or [2], wherein the organic material is a copolymer containing, as repeating units, a molecular structure represented by the following formula (1) and a molecular structure represented by the following formula (2): [4] The photodetector according to [3], wherein the first charge transport layer contains a plurality of types of the copolymer. [5] The photodetector according to any one of [1] to [4], wherein the organic material has a benzodithiophene skeleton. [6] The photodetector according to any one of [1] to [5], wherein the organic material is a polymer material having a weight-average molecular weight of 5,000 or more. [7] The photodetector according to any one of [1] to [6], wherein the organic material has a crystallinity that is 57 to 187 times higher than that of an indium tin oxide film having a thickness of 50 nm that has been heat-treated at 150°C for 210 minutes. [8] The photodetector according to any one of [1] to [7], wherein the semiconductor quantum dots are semiconductor nanoparticles having an indium arsenide core. [9] The photodetector according to any one of [1] to [8], wherein the first electrode, the photoelectric conversion layer, the first charge transport layer, and the second electrode are stacked in this order toward the light incident side.

[10] The photodetector according to any one of [1] to [9], further comprising a second charge transport layer between the first electrode and the photoelectric conversion layer.

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

[10] , wherein the photoelectric conversion layer has a light absorption rate of 20% or more in a part or all of the wavelength band of 900 nm to 1600 nm.

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

[11] , further comprising an intermediate layer between the photoelectric conversion layer and the first charge transport layer.

[13] The photodetector according to

[12] , wherein the intermediate layer is a semiconductor nanoparticle layer shallower than the end of the valence band of the photoelectric conversion layer.

[14] The photodetector according to

[12] or

[13] , wherein the intermediate layer is a semiconductor nanoparticle layer having a band gap larger than that of the photoelectric conversion layer.

[15] 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 including first semiconductor quantum dots, and an intermediate layer disposed between the photoelectric conversion layer and the second electrode and including second semiconductor quantum dots having a particle diameter smaller than that of the first semiconductor quantum dots.

[16] The photodetector according to

[15] , further comprising a charge transport layer between the intermediate layer and the second electrode, the charge transport layer containing a crystalline organic material having donor and acceptor moieties in its molecules.

[17] An electronic device comprising a photodetector, the 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 containing semiconductor quantum dots, and a first charge transport layer disposed between the photoelectric conversion layer and the second electrode, the first charge transport layer containing a crystalline organic material having donor and acceptor moieties in its molecules.

Claims

1. A photodetector comprising a first electrode, a second electrode disposed opposite to the first electrode, a photoelectric conversion layer disposed between the first electrode and the second electrode and containing semiconductor quantum dots, and a first charge transport layer disposed between the photoelectric conversion layer and the second electrode and containing an organic material having a donor portion and an acceptor portion in the molecule and having crystallinity.

2. The photodetector according to claim 1, wherein the semiconductor quantum dots are semiconductor nanoparticles of group III-V, I-VI, I-III-V, I-V-VI or IV-VI.

3. The photodetection device according to claim 1, wherein the organic material is a copolymer including, as repeating units, a molecular structure represented by the following formula (1) and a molecular structure represented by the following formula (2).

4. The photodetector according to claim 3, wherein the first charge transport layer contains a plurality of types of the copolymer.

5. The photodetector according to claim 1, wherein the organic material has a benzodithiophene skeleton.

6. The photodetector according to claim 1, wherein the organic material is a polymer material having a weight average molecular weight of 5000 or more.

7. The photodetector according to claim 1, wherein the organic material has a crystallinity of 57 times or more and 187 times or less as compared with an indium tin oxide film having a thickness of 50 nm heat-treated at 150 ° C. for 210 minutes.

8. The photodetector according to claim 1, wherein the semiconductor quantum dots are semiconductor nanoparticles having indium arsenide as a core.

9. The photodetector according to claim 1, wherein the first electrode, the photoelectric conversion layer, the first charge transport layer, and the second electrode are laminated in this order toward the light incident side.

10. The photodetector according to claim 1, further comprising a second charge transport layer between the first electrode and the photoelectric conversion layer.

11. The photodetector according to claim 1, wherein the photoelectric conversion layer has a light absorption rate of 20% or more in a part or all of the wavelength band of 900 nm or more and 1600 nm or less.

12. The photodetector according to claim 1, further comprising an intermediate layer between the photoelectric conversion layer and the first charge transport layer.

13. The photodetector according to claim 12, wherein the intermediate layer is a semiconductor nanoparticle layer shallower than the last part of the valence band of the photoelectric conversion layer.

14. The photodetector according to claim 12, wherein the intermediate layer is a semiconductor nanoparticle layer having a larger band gap than the photoelectric conversion layer.

15. A photodetector comprising a first electrode, a second electrode disposed opposite to the first electrode, a photoelectric conversion layer disposed between the first electrode and the second electrode and including first semiconductor quantum dots, and an intermediate layer disposed between the photoelectric conversion layer and the second electrode and including second semiconductor quantum dots having a smaller particle size than the first semiconductor quantum dots.

16. The photodetector according to claim 15, further comprising a charge transport layer disposed between the intermediate layer and the second electrode and including an organic material having a donor portion and an acceptor portion in the molecule and having crystallinity.

17. An electronic device including a photodetector, the photodetector including a first electrode, a second electrode disposed opposite to the first electrode, a photoelectric conversion layer disposed between the first electrode and the second electrode and including semiconductor quantum dots, and a first charge transport layer disposed between the photoelectric conversion layer and the second electrode and including an organic material having a donor portion and an acceptor portion in the molecule and having crystallinity.

Images