WO2023008353A1 - 光検出素子およびイメージセンサ - Google Patents

光検出素子およびイメージセンサ Download PDF

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WO2023008353A1
WO2023008353A1 PCT/JP2022/028564 JP2022028564W WO2023008353A1 WO 2023008353 A1 WO2023008353 A1 WO 2023008353A1 JP 2022028564 W JP2022028564 W JP 2022028564W WO 2023008353 A1 WO2023008353 A1 WO 2023008353A1
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atoms
photodetector
semiconductor quantum
quantum dots
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French (fr)
Japanese (ja)
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雅司 小野
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Fujifilm Corp
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Fujifilm Corp
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F30/00—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors
    • H10F30/20—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F39/00—Integrated devices, or assemblies of multiple devices, comprising at least one element covered by group H10F30/00, e.g. radiation detectors comprising photodiode arrays
    • H10F39/10—Integrated devices
    • H10F39/12—Image sensors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F77/00—Constructional details of devices covered by this subclass
    • H10F77/10—Semiconductor bodies
    • H10F77/12—Active materials

Definitions

  • the present invention relates to a photodetector having a photoelectric conversion layer containing semiconductor quantum dots, and an image sensor.
  • silicon photodiodes that use silicon wafers as the material for the photoelectric conversion layer have been used for photodetection elements used in image sensors and the like.
  • silicon photodiodes have low sensitivity in the infrared region with a wavelength of 900 nm or more.
  • InGaAs-based semiconductor materials which are known as light-receiving elements for near-infrared light, require extremely high-cost processes such as epitaxial growth and substrate bonding processes in order to achieve high quantum efficiency.
  • the problem is that the
  • Non-Patent Document 1 describes a solar cell having a photoelectric conversion film containing AgBiS 2 quantum dots.
  • characteristics required for a photodetector include a small dark current, a high external quantum efficiency for light of a target wavelength to be detected by the photodetector, and an increase in the external quantum efficiency of the photodetector over time. Therefore, it is required to have a small dynamic change and a small dark current.
  • a higher signal-to-noise ratio (SN ratio) can be obtained in the image sensor by reducing the dark current of the photodetector.
  • a dark current is a current that flows when light is not applied. Further, by increasing the external quantum efficiency of the photodetector and suppressing temporal fluctuations in the external quantum efficiency, it is possible to improve the light detection accuracy of the photodetector.
  • Non-Patent Document 1 only describes inventions related to solar cells, and does not describe light detection elements.
  • an object of the present invention is to provide a photodetector and an image sensor that have high external quantum efficiency, small temporal fluctuations in external quantum efficiency, and reduced dark current.
  • the inventor of the present invention has extensively studied a photodetector using a semiconductor quantum dot containing Ag atoms, Bi atoms, and chalcogen atoms in a photoelectric conversion layer.
  • the inventors have found that the above object can be achieved by reducing the number ratio, and have completed the present invention. Accordingly, the present invention provides the following.
  • ⁇ 1> A photodetector having a photoelectric conversion layer containing an assembly of semiconductor quantum dots containing Ag atoms, Bi atoms, and chalcogen atoms, and ligands coordinated to the semiconductor quantum dots,
  • the photodetector, wherein the semiconductor quantum dot has a ratio of the number of Ag atoms to the number of chalcogen atoms of 0.85 or less.
  • ⁇ 2> The photodetector according to ⁇ 1>, wherein the semiconductor quantum dots have a ratio of the number of Ag atoms to the number of chalcogen atoms of 0.75 or less.
  • ⁇ 3> The photodetector according to ⁇ 1> or ⁇ 2>, wherein the chalcogen atom includes at least one selected from an S atom and a Te atom.
  • ⁇ 4> The photodetector according to ⁇ 1> or ⁇ 2>, wherein the chalcogen atom includes an S atom and a Te atom.
  • X A1 and X A2 each independently represent a thiol group, an amino group, a hydroxy group, a carboxy group, a sulfo group, a phospho group, or a phosphonic acid group;
  • L A1 represents a hydrocarbon group;
  • X B1 and X B2 each independently represent a thiol group, an amino group, a hydroxy group, a carboxy group, a sulfo group, a phospho group or a phosphonic acid group;
  • X B3 represents S, O
  • ⁇ 7> The photodetector according to any one of ⁇ 1> to ⁇ 6>, wherein the semiconductor quantum dots have a bandgap of 1.0 eV or less.
  • the present invention it is possible to provide a photodetector and an image sensor that have a high external quantum efficiency, a small change over time in the external quantum efficiency, and a reduced dark current.
  • FIG. 11 illustrates an embodiment of a photodetector
  • ⁇ is used to include the numerical values before and after it as lower and upper limits.
  • a description that does not describe substitution or unsubstituted includes a group (atomic group) having no substituent as well as a group (atomic group) having a substituent.
  • an "alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).
  • the photodetector of the present invention is a photodetector having a photoelectric conversion layer containing an assembly of semiconductor quantum dots containing Ag atoms, Bi atoms and chalcogen atoms, and ligands coordinated to the semiconductor quantum dots.
  • the photodetector of the present invention can be a photodetector that has a high external quantum efficiency, a small change over time in the external quantum efficiency, and a reduced dark current. Although the detailed reason why such an effect is obtained is unknown, it is presumed to be due to the following.
  • the ratio of the number of Ag atoms to the number of chalcogen atoms in the semiconductor quantum dots is set to 0.85 or less, that is, the ratio of chalcogen atoms in the semiconductor quantum dots is increased.
  • the value of the ratio of the number of Ag atoms to the number of chalcogen atoms of the semiconductor quantum dots can be calculated by measuring the elemental composition ratio of the semiconductor quantum dots by energy dispersive X-ray spectroscopy.
  • a film is formed using a dispersion of semiconductor quantum dots, and the element composition ratio of the semiconductor quantum dots can be measured and calculated by energy dispersive X-ray spectroscopy for this film.
  • a ligand containing a chalcogen atom is coordinated to the semiconductor quantum dot, for example, after removing or replacing the ligand on the surface of the semiconductor quantum dot by heating or washing with a coordinating solvent
  • energy dispersive X-ray spectroscopy it is possible to measure the ratio of the number of Ag atoms to the number of chalcogen atoms in the semiconductor quantum dots.
  • the semiconductor quantum dots are, for example, a compound containing an Ag atom (hereinafter also referred to as an Ag compound) and a compound containing a Bi atom (hereinafter also referred to as a Bi compound) in a precursor solution containing a ligand, and a chalcogen atom. It can be produced by adding a solution containing a compound (hereinafter referred to as a chalcogen compound) and a solvent (hereinafter also referred to as a chalcogen source) to react an Ag compound, a Bi compound and a chalcogen compound.
  • the Ag compound is not particularly limited as long as it contains an Ag atom, and examples thereof include silver acetate, silver nitrate, silver oxide, and other silver carboxylates.
  • the Bi compound is not particularly limited as long as it contains a Bi atom, and examples thereof include bismuth acetate, bismuth nitrate, bismuth oxide, and other bismuth carboxylates.
  • Examples of chalcogen compounds include solutions in which chalcogen elements are dissolved in coordinating solvents such as hexamethyldisilathiane, trimethylsilyltelluride, and trioctylphosphine.
  • the molar amount of Ag atoms in the Ag compound is preferably 0.6 to 1.4 with respect to the molar amount of Bi atoms in the Bi compound.
  • the lower limit is preferably 0.65 or more, more preferably 0.7 or more.
  • the upper limit is preferably 1.35 or less, more preferably 1.3 or less.
  • the ratio of the Ag compound and the chalcogen compound is the molar amount of the chalcogen atoms of the chalcogen compound (when two or more kinds of chalcogen compounds are included, the total molar amount of the chalcogen atoms of each chalcogen compound) to the Ag compound. is preferably 0.5 to 1.2.
  • the lower limit is preferably 0.55 or more, more preferably 0.6 or more.
  • the upper limit is preferably 1.1 or less, more preferably 1.0 or less.
  • the reaction temperature between the precursor solution and the chalcogen source is preferably 60-160°C, more preferably 70-120°C.
  • the surface of the particle is terminated with either a cation atom or an anion atom, and the crystal structure and lattice constant are ideal due to crystal defects, element substitution, crystal distortion, etc.
  • the atomic composition does not conform to the structural formula, as deviations occur from the crystal.
  • the photoelectric conversion layer in the photodetector of the present invention will be described in more detail.
  • the photoelectric conversion layer of the photodetector of the present invention has an aggregate of semiconductor quantum dots containing Ag atoms, Bi atoms and chalcogen atoms.
  • the aggregate of semiconductor quantum dots refers to a form in which a large number (for example, 100 or more per 1 ⁇ m 2 ) of semiconductor quantum dots are arranged close to each other.
  • semiconductor used herein means a substance having a resistivity value of 10 ⁇ 2 ⁇ cm or more and 10 8 ⁇ cm or less.
  • the ratio of the number of Ag atoms to the number of chalcogen atoms is 0.85 or less, preferably 0.80 or less, and more preferably 0.75 or less.
  • the lower limit is preferably 0.2 or more, more preferably 0.3 or more.
  • a semiconductor quantum dot material that constitutes a semiconductor quantum dot includes a compound semiconductor containing Ag atoms, Bi atoms, and chalcogen atoms.
  • a compound semiconductor is a semiconductor composed of two or more kinds of atoms. Therefore, in this specification, "a compound semiconductor containing Ag atoms, Bi atoms, and chalcogen atoms" means a compound semiconductor containing Ag atoms, Bi atoms, and chalcogen atoms as atoms constituting the compound semiconductor. .
  • Chalcogen atoms include S (sulfur) atoms and Te (tellurium) atoms.
  • the semiconductor quantum dots preferably contain S atoms, more preferably S atoms and Te atoms.
  • Semiconductor quantum dots are semiconductor quantum dots containing Ag atoms, Bi atoms and S atoms (hereinafter also referred to as Ag-Bi-S based semiconductor quantum dots), or Ag atoms, Bi atoms, Te atoms and S atoms. It is preferably a semiconductor quantum dot (hereinafter also referred to as an Ag--Bi--Te--S based semiconductor quantum dot).
  • the ratio of the number of Te atoms to the total number of S atoms and Te atoms is preferably 0.05 to 0.5, more preferably 0.1 to 0.45.
  • the lower limit is preferably 0.15 or more, more preferably 0.2 or more.
  • the upper limit is preferably 0.40 or less.
  • crystal structure of semiconductor quantum dots there are no particular restrictions on the crystal structure of semiconductor quantum dots. Various crystal structures can be formed depending on the types and composition ratios of the elements that make up the semiconductor quantum dots. A crystalline or hexagonal crystal structure is preferred. The crystal structure of semiconductor quantum dots can be measured by X-ray diffraction or electron diffraction.
  • the bandgap of semiconductor quantum dots is preferably 1.2 eV or less, more preferably 1.0 eV or less.
  • the lower limit of the bandgap of the semiconductor quantum dots is not particularly limited, but is preferably 0.3 eV or more, more preferably 0.5 eV or more.
  • the average particle size of semiconductor quantum dots is preferably 3 to 20 nm.
  • the lower limit of the average particle size of the semiconductor quantum dots is preferably 4 nm or more, more preferably 5 nm or more.
  • the upper limit of the average particle size of the semiconductor quantum dots is preferably 15 nm or less, more preferably 10 nm or less. If the average particle size of the semiconductor quantum dots is within the above range, the photodetector can have a higher external quantum efficiency for light with wavelengths in the infrared region.
  • the value of the average particle size of semiconductor quantum dots is the average value of the particle sizes of 10 arbitrarily selected semiconductor quantum dots.
  • a transmission electron microscope may be used to measure the particle size of semiconductor quantum dots.
  • the photoelectric conversion layer of the photodetector of the present invention contains ligands that coordinate to the semiconductor quantum dots.
  • the above ligands include ligands containing halogen atoms and multidentate ligands containing two or more coordinating moieties.
  • the photoelectric conversion layer may contain only 1 type of ligands, and may contain 2 or more types.
  • the photoelectric conversion layer preferably contains a multidentate ligand, and more preferably contains a ligand containing a halogen atom and a multidentate ligand.
  • the photodetector can have a higher external quantum efficiency, a smaller temporal change in the external quantum efficiency, and a lower dark current.
  • Multidentate ligands are presumed to chelate coordinate with semiconductor quantum dots, and are presumed to be able to more effectively suppress peeling of ligands from semiconductor quantum dots.
  • steric hindrance between semiconductor quantum dots can be suppressed by chelate coordination. Therefore, it is considered that the steric hindrance between the semiconductor quantum dots is reduced, the semiconductor quantum dots are closely arranged, and the overlap of the wave functions between the semiconductor quantum dots can be strengthened.
  • the photodetector can have a higher external quantum efficiency, a smaller change over time in the external quantum efficiency, and a lower dark current.
  • the photoelectric conversion layer contains a ligand containing a halogen atom and a multidentate ligand, their molar ratio is preferably 1:99 to 99:1, and 10:90 to 90:10. is more preferred, and 20:80 to 80:20 is even more preferred.
  • halogen atom contained in the ligand includes fluorine atom, chlorine atom, bromine atom and iodine atom, and iodine atom is preferable from the viewpoint of coordinating power.
  • a ligand containing a halogen atom may be an organic halide or an inorganic halide.
  • inorganic halides are preferable because they are easily coordinated to both the cationic site and the anionic site of the semiconductor quantum dots.
  • an inorganic halide is used, the effect of coordinating with both the cationic site and the anionic site of the semiconductor quantum dot can be expected.
  • an inorganic halide is used, it is preferably a compound containing a metal element selected from Zn (zinc) atoms, In (indium) atoms and Cd (cadmium) atoms, more preferably a compound containing a Zn atom.
  • the inorganic halide is preferably a salt of a metal atom and a halogen atom because it is easily ionized and easily coordinated to the semiconductor quantum dots.
  • ligands containing halogen atoms include zinc iodide, zinc bromide, zinc chloride, indium iodide, indium bromide, indium chloride, cadmium iodide, cadmium bromide, cadmium chloride, gallium iodide, gallium bromide, gallium chloride, tetrabutylammonium iodide, tetramethylammonium iodide and the like.
  • the halogen ion may be dissociated from the ligand described above and coordinated to the surface of the semiconductor quantum dot.
  • the sites other than the halogen atoms of the aforementioned ligands may also be coordinated to the surface of the semiconductor quantum dots.
  • zinc iodide zinc iodide may be coordinated to the surface of the semiconductor quantum dot, and iodine ions and zinc ions may be coordinated to the surface of the semiconductor quantum dot.
  • Coordinating moieties included in the polydentate ligand include thiol groups, amino groups, hydroxy groups, carboxy groups, sulfo groups, phospho groups, and phosphonic acid groups.
  • Multidentate ligands include ligands represented by any one of formulas (A) to (C).
  • X A1 and X A2 each independently represent a thiol group, an amino group, a hydroxy group, a carboxy group, a sulfo group, a phospho group, or a phosphonic acid group;
  • L A1 represents a hydrocarbon group.
  • X B1 and X B2 each independently represent a thiol group, an amino group, a hydroxy group, a carboxy group, a sulfo group, a phospho group or a phosphonic acid group;
  • X B3 represents S, O or NH,
  • L B1 and L B2 each independently represent a hydrocarbon group.
  • X C1 to X C3 each independently represent a thiol group, an amino group, a hydroxy group, a carboxy group, a sulfo group, a phospho group or a phosphonic acid group;
  • X C4 represents N, L C1 to L C3 each independently represent a hydrocarbon group.
  • the amino groups represented by X A1 , X A2 , X B1 , X B2 , X C1 , X C2 and X C3 are not limited to —NH 2 but also include substituted amino groups and cyclic amino groups.
  • Substituted amino groups include monoalkylamino groups, dialkylamino groups, monoarylamino groups, diarylamino groups, alkylarylamino groups and the like.
  • the amino group represented by these groups is preferably -NH 2 , a monoalkylamino group or a dialkylamino group, more preferably -NH 2 .
  • the hydrocarbon group represented by L A1 , L B1 , L B2 , L C1 , L C2 and L C3 is preferably an aliphatic hydrocarbon group or a group containing an aromatic ring, more preferably an aliphatic hydrocarbon group. .
  • the aliphatic hydrocarbon group may be a saturated aliphatic hydrocarbon group or an unsaturated aliphatic hydrocarbon group.
  • the number of carbon atoms in the hydrocarbon group is preferably 1-20.
  • the upper limit of the number of carbon atoms is preferably 10 or less, more preferably 6 or less, and even more preferably 3 or less.
  • Specific examples of hydrocarbon groups include alkylene groups, alkenylene groups, alkynylene groups, and arylene groups.
  • the alkylene group includes a linear alkylene group, a branched alkylene group and a cyclic alkylene group, preferably a linear alkylene group or a branched alkylene group, more preferably a linear alkylene group.
  • the alkenylene group includes a linear alkenylene group, a branched alkenylene group and a cyclic alkenylene group, preferably a linear alkenylene group or a branched alkenylene group, more preferably a linear alkenylene group.
  • the alkynylene group includes a linear alkynylene group and a branched alkynylene group, preferably a linear alkynylene group.
  • Arylene groups may be monocyclic or polycyclic.
  • a monocyclic arylene group is preferred.
  • Specific examples of the arylene group include a phenylene group and a naphthylene group, with the phenylene group being preferred.
  • the alkylene group, alkenylene group, alkynylene group and arylene group may further have a substituent.
  • the substituent is preferably a group having 1 to 10 atoms.
  • groups having 1 to 10 atoms include alkyl groups having 1 to 3 carbon atoms [methyl group, ethyl group, propyl group and isopropyl group], alkenyl groups having 2 to 3 carbon atoms [ethenyl group and propenyl group], an alkynyl group having 2 to 4 carbon atoms [ethynyl group, propynyl group, etc.], a cyclopropyl group, an alkoxy group having 1 to 2 carbon atoms [methoxy group and ethoxy group], an acyl group having 2 to 3 carbon atoms [ acetyl group and propionyl group], alkoxycarbonyl group having 2 to 3 carbon atoms [methoxycarbonyl group and ethoxycarbonyl group], acyloxy group having 2 carbon atoms [acetyloxy group], acylamino group having 2 carbon atoms [acetylamino group] , hydroxyalkyl group having 1
  • X A1 and X A2 are preferably separated by 1 to 10 atoms, more preferably by 1 to 6 atoms, and more preferably by 1 to 4 atoms, by L A1 . is more preferable, more preferably 1 to 3 atoms apart, and particularly preferably 1 or 2 atoms apart.
  • X B1 and X B3 are preferably separated by 1 to 10 atoms, more preferably by 1 to 6 atoms, and more preferably by 1 to 4 atoms, by L B1 . is more preferable, more preferably 1 to 3 atoms apart, and particularly preferably 1 or 2 atoms apart.
  • X B2 and X B3 are preferably separated by 1 to 10 atoms, more preferably 1 to 6 atoms, even more preferably 1 to 4 atoms, by L B2 , More preferably, they are separated by 1 to 3 atoms, and particularly preferably separated by 1 or 2 atoms.
  • X C1 and X C4 are preferably separated by 1 to 10 atoms, more preferably by 1 to 6 atoms, and further by 1 to 4 atoms by L C1 . is more preferable, more preferably 1 to 3 atoms apart, and particularly preferably 1 or 2 atoms apart.
  • X C2 and X C4 are preferably separated by 1 to 10 atoms, more preferably by 1 to 6 atoms, even more preferably by 1 to 4 atoms, by L C2 , More preferably, they are separated by 1 to 3 atoms, and particularly preferably separated by 1 or 2 atoms.
  • X C3 and X C4 are preferably separated by 1 to 10 atoms, more preferably 1 to 6 atoms, even more preferably 1 to 4 atoms, by L C3 , More preferably, they are separated by 1 to 3 atoms, and particularly preferably separated by 1 or 2 atoms.
  • X A1 and X A2 are separated by L A1 by 1 to 10 atoms means that the number of atoms forming the shortest molecular chain connecting X A1 and X A2 is 1 to 10.
  • X A1 and X A2 are separated by two atoms
  • X A1 and X A2 are separated by three atoms. ing.
  • the numbers added to the following structural formulas represent the order of arrangement of atoms forming the shortest molecular chain connecting X A1 and X A2 .
  • 3-mercaptopropionic acid has a structure in which the site corresponding to X A1 is a carboxy group, the site corresponding to X A2 is a thiol group, and the site corresponding to L A1 is an ethylene group. (a compound having the following structure).
  • X A1 carboxy group
  • X A2 thiol group
  • L A1 ethylene group
  • X B1 and X B3 are separated by 1 to 10 atoms by L B1
  • X B2 and X B3 are separated by 1 to 10 atoms by L B2
  • X C1 and X C4 are separated by L C1
  • X C2 and X C4 are separated by 1 to 10 atoms by L C2
  • X C3 and X C4 are separated by L C3 by 1 to 10 atoms.
  • the meaning is also the same as above.
  • multidentate ligands include 1,2-ethanedithiol, 3-mercaptopropionic acid, thioglycolic acid, 2-aminoethanol, 2-aminoethanethiol, 2-mercaptoethanol, glycolic acid, ethylene glycol, Ethylenediamine, aminosulfonic acid, glycine, aminomethylphosphoric acid, guanidine, diethylenetriamine, tris(2-aminoethyl)amine, 4-mercaptobutanoic acid, 3-aminopropanol, 3-mercaptopropanol, N-(3-aminopropyl) -1,3-propanediamine, 3-(bis(3-aminopropyl)amino)propan-1-ol, 1-thioglycerol, dimercaprol, 1-mercapto-2-butanol, 1-mercapto-2-pen Tanol, 3-mercapto-1-propanol, 2,3-dimercapto-1-propanol, 2-
  • the polydentate ligand is preferably a compound having a boiling point of 90°C or higher.
  • the thickness of the photoelectric conversion layer is preferably 10-1000 nm.
  • the lower limit of the thickness is preferably 20 nm or more, more preferably 30 nm or more.
  • the upper limit of the thickness is preferably 600 nm or less, more preferably 550 nm or less, even more preferably 500 nm or less, and particularly preferably 450 nm or less.
  • the refractive index of the photoelectric conversion layer with respect to the light of the target wavelength to be detected by the photodetector can be 1.5 to 5.0.
  • the photoelectric conversion layer is a dispersion containing semiconductor quantum dots containing Ag atoms, Bi atoms, and chalcogen atoms, ligands that coordinate to the semiconductor quantum dots, and a solvent (hereinafter also referred to as quantum dot dispersion). on a substrate to form a film of semiconductor quantum dot aggregates (semiconductor quantum dot aggregate forming step).
  • Coating methods such as a spin coating method, a dipping method, an inkjet method, a dispenser method, a screen printing method, a letterpress printing method, an intaglio printing method, and a spray coating method can be mentioned.
  • the thickness of the film of the semiconductor quantum dot aggregate formed by the semiconductor quantum dot aggregate forming step is preferably 3 nm or more, more preferably 10 nm or more, and more preferably 20 nm or more.
  • the upper limit is preferably 200 nm or less, more preferably 150 nm or less, and even more preferably 100 nm or less.
  • a ligand exchange process may be further performed to exchange the ligands coordinated to the semiconductor quantum dots with other ligands.
  • a ligand exchange step a ligand different from the ligand contained in the dispersion liquid (hereinafter referred to as a ligand (also referred to as A) and a solvent to exchange the ligands that coordinate to the semiconductor quantum dots with the ligands A contained in the ligand solution.
  • the semiconductor quantum dot assembly formation step and the ligand exchange step may be alternately repeated multiple times.
  • ligand A examples include ligands containing halogen atoms and multidentate ligands containing two or more coordinating moieties. The details thereof are as described above, and the preferred ranges are also the same.
  • the ligand solution used in the ligand exchange step may contain only one type of ligand A, or may contain two or more types. Also, two or more ligand solutions may be used.
  • the solvent contained in the ligand solution is preferably selected as appropriate according to the type of ligand contained in each ligand solution, and is preferably a solvent that easily dissolves each ligand.
  • the solvent contained in the ligand solution is preferably an organic solvent having a high dielectric constant. Specific examples include ethanol, acetone, methanol, acetonitrile, dimethylformamide, dimethylsulfoxide, butanol, propanol and the like.
  • the solvent contained in the ligand solution is preferably a solvent that hardly remains in the photoelectric conversion layer.
  • the solvent contained in the ligand solution is preferably immiscible with the solvent contained in the quantum dot dispersion.
  • the solvent contained in the quantum dot dispersion is an alkane such as hexane or octane, or when toluene is used, the solvent contained in the ligand solution is a polar solvent such as methanol or acetone. is preferred.
  • a step of rinsing the film after the ligand exchange step by contacting a rinse solution may be performed.
  • a rinse solution By performing the rinsing step, excess ligands contained in the film and ligands detached from the semiconductor quantum dots can be removed. In addition, residual solvent and other impurities can be removed.
  • As a rinsing liquid it is easier to remove excess ligands contained in the film and ligands detached from the semiconductor quantum dots more effectively, and the film surface is made uniform by rearranging the semiconductor quantum dot surface.
  • Aprotic solvents are preferred because they are easier to maintain.
  • aprotic solvents include acetonitrile, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, diethyl ether, tetrahydrofuran, cyclopentyl methyl ether, dioxane, ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, hexane, octane. , cyclohexane, benzene, toluene, chloroform, carbon tetrachloride and dimethylformamide, preferably acetonitrile and tetrahydrofuran, more preferably acetonitrile.
  • the rinsing process may be performed multiple times using two or more rinsing liquids with different polarities (relative dielectric constants). For example, first rinse with a rinse solution having a higher relative dielectric constant (also referred to as a first rinse solution), and then rinse with a rinse solution having a lower relative dielectric constant than the first rinse solution (also referred to as a second rinse solution). It is preferable to perform rinsing using By performing rinsing in this way, the surplus component of ligand A used for ligand exchange is first removed, and then the desorbed ligand component (originally bound to the particles) generated during the ligand exchange process is removed. By removing the ligand component), both the surplus/or desorbed ligand component can be removed more efficiently.
  • the dielectric constant of the first rinse is preferably 15-50, more preferably 20-45, and even more preferably 25-40.
  • the dielectric constant of the second rinse is preferably 1-15, more preferably 1-10, and even more preferably 1-5.
  • a drying step may be included in the production of the photoelectric conversion layer.
  • the solvent remaining in the photoelectric conversion layer can be removed by performing the drying step.
  • the drying time is preferably 1 to 100 hours, more preferably 1 to 50 hours, even more preferably 5 to 30 hours.
  • the drying temperature is preferably 10 to 100°C, more preferably 20 to 90°C, even more preferably 20 to 60°C.
  • Types of photodetecting elements include photoconductor type photodetecting elements and photodiode type photodetecting elements. Among them, a photodiode type photodetector is preferable because a high signal-to-noise ratio (SN ratio) can be easily obtained.
  • SN ratio signal-to-noise ratio
  • FIG. 1 shows one embodiment of a photodetector.
  • FIG. 1 is a diagram showing an embodiment of a photodiode-type photodetector.
  • the arrows in the drawing represent incident light to the photodetector.
  • the photodetector 1 shown in FIG. 1 includes a second electrode layer 12, a first electrode layer 11 provided to face the second electrode layer 12, the second electrode layer 12 and the first electrode.
  • the photoelectric conversion layer 13 provided between the layer 11, the electron transport layer 21 provided between the first electrode layer 11 and the photoelectric conversion layer 13, the second electrode layer 12 and the photoelectric conversion layer 13 and a hole transport layer 22 disposed between.
  • the photodetector 1 shown in FIG. 1 is used so that light enters from above the first electrode layer 11 .
  • a transparent substrate may be arranged on the surface of the first electrode layer 11 on the light incident side. Types of transparent substrates include glass substrates, resin substrates, ceramic substrates, and the like.
  • the first electrode layer 11 is preferably a transparent electrode made of a conductive material substantially transparent to the wavelength of light to be detected by the photodetector.
  • substantially transparent means that the light transmittance is 50% or more, preferably 60% or more, and particularly preferably 80% or more.
  • materials for the first electrode layer 11 include conductive metal oxides. Specific examples include tin oxide, zinc oxide, indium oxide, indium tungsten oxide, indium zinc oxide (IZO), indium tin oxide (ITO), and fluorine-doped tin oxide (ITO). tin oxide: FTO) and the like.
  • the film thickness of the first electrode layer 11 is not particularly limited, and is preferably 0.01 to 100 ⁇ m, more preferably 0.01 to 10 ⁇ m, particularly preferably 0.01 to 1 ⁇ m.
  • the film thickness of each layer can be measured by observing the cross section of the photodetector 1 using a scanning electron microscope (SEM) or the like.
  • the electron transport layer 21 is a layer having a function of transporting electrons generated in the photoelectric conversion layer 13 to the electrode layer.
  • the electron transport layer is also called a hole blocking layer.
  • the electron-transporting layer is formed of an electron-transporting material capable of performing this function.
  • electron transport materials examples include fullerene compounds such as [6,6]-Phenyl-C61-Butyric Acid Methyl Ester (PC 61 BM), perylene compounds such as perylenetetracarboxydiimide, tetracyanoquinodimethane, titanium oxide, and tin oxide. , zinc oxide, indium oxide, indium tungsten oxide, indium zinc oxide, indium tin oxide, and fluorine-doped tin oxide.
  • the electron transport material may be particles.
  • the electron-transporting layer contains zinc oxide doped with metal atoms other than Zn.
  • zinc oxide doped with metal atoms other than Zn is also referred to as doped zinc oxide.
  • the metal atom other than Zn in the doped zinc oxide is preferably a monovalent to trivalent metal atom, and more preferably contains at least one selected from Li, Mg, Al and Ga. Li, Mg, Al or Ga is more preferred, and Li or Mg is particularly preferred.
  • the ratio of metal atoms other than Zn to the total of Zn and metal atoms other than Zn is preferably 1 atomic % or more, more preferably 2 atomic % or more, and 4 atomic % or more. is more preferable. From the viewpoint of suppressing an increase in crystal defects, the upper limit is preferably 20 atomic % or less, more preferably 15 atomic % or less, and even more preferably 12 atomic % or less.
  • the proportion of metal atoms other than Zn in the doped zinc oxide can be measured by a high frequency inductively coupled plasma (ICP) method.
  • ICP inductively coupled plasma
  • the doped zinc oxide is preferably particles (doped zinc oxide particles) from the viewpoint of reducing residual organic components and increasing the contact area with the photoelectric conversion layer.
  • the average particle size of the doped zinc oxide particles is preferably 2 to 30 nm.
  • the lower limit of the average particle size of the doped zinc oxide particles is preferably 3 nm or more, more preferably 5 nm or more.
  • the upper limit of the average particle diameter of the doped zinc oxide particles is preferably 20 nm or less, more preferably 15 nm or less.
  • the value of the average particle size of the doped zinc oxide particles is the average value of the particle sizes of 10 arbitrarily selected quantum dots. A transmission electron microscope may be used to measure the particle size of the doped zinc oxide particles.
  • the electron transport layer may be a single layer film or a laminated film of two or more layers.
  • the thickness of the electron transport layer is preferably 10-1000 nm.
  • the upper limit is preferably 800 nm or less.
  • the lower limit is preferably 20 nm or more, more preferably 50 nm or more.
  • the thickness of the electron transport layer is preferably 0.05 to 10 times the thickness of the photoelectric conversion layer 13, more preferably 0.1 to 5 times, and 0.2 to 2 times. It is even more preferable to have
  • Ultraviolet ozone treatment may be performed on the electron transport layer.
  • the electron transport layer is a layer made of nanoparticles
  • ultraviolet ozone treatment By performing ultraviolet ozone treatment, the wettability of the quantum dot dispersion to the electron transport layer can be improved, and residual organic substances in the electron transport layer can be decomposed and removed, resulting in high device performance.
  • the wavelength of the ultraviolet rays to be irradiated can be selected from a wavelength of 100 to 400 nm.
  • the irradiation intensity of ultraviolet rays is not particularly limited, but is preferably 1 to 100 mW/cm 2 , more preferably 10 to 50 mW/cm, because the above effects can be easily obtained and excessive damage to the film can be avoided. 2 is more preferred.
  • the treatment time is not particularly limited, but for the same reason, it is preferably 1 to 60 minutes, more preferably 1 to 20 minutes, and even more preferably 3 to 15 minutes.
  • the photoelectric conversion layer 13 is the photoelectric conversion layer described above. That is, the photoelectric conversion layer 13 includes an aggregate of semiconductor quantum dots including Ag atoms, Bi atoms, and chalcogen atoms, and ligands coordinated to the semiconductor quantum dots. In this semiconductor quantum dot, the ratio of the number of Ag atoms to the number of chalcogen atoms is 0.85 or less, preferably 0.75 or less.
  • the thickness of the photoelectric conversion layer 13 is preferably 10-1000 nm.
  • the lower limit of the thickness is preferably 20 nm or more, more preferably 30 nm or more.
  • the upper limit of the thickness is preferably 600 nm or less, more preferably 550 nm or less, even more preferably 500 nm or less, and particularly preferably 450 nm or less.
  • the photoelectric conversion layer 13 can have a refractive index of 1.5 to 5.0 with respect to light of a target wavelength to be detected by the photodetector.
  • the hole transport layer 22 is a layer having a function of transporting holes generated in the photoelectric conversion layer 13 to the electrode layer.
  • a hole transport layer is also called an electron blocking layer.
  • the hole-transporting layer 22 is made of a hole-transporting material capable of performing this function.
  • hole transport materials include PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonic acid)), PTB7 (poly ⁇ 4,8-bis[(2-ethylhexyl) oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-lt-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4 -b]thiophene-4,6-diyl ⁇ ), PTB7-Th(poly([2,6′-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,3-b]dithiophene] ⁇ 3-fluoro-2[(2-ethylhexyl l) carbonyl]thieno[
  • Organic hole-transporting materials described in paragraphs 0209 to 0212 of JP-A-2001-291534 can also be used.
  • Semiconductor quantum dots can also be used as the hole transport material.
  • As a semiconductor quantum dot material constituting a semiconductor quantum dot general semiconductor crystals [a) Group IV semiconductors, b) Group IV-IV, III-V, or II-VI compound semiconductors, c) Group II , III-, IV-, V-, and VI-group compounds] nanoparticles (particles with a size of 0.5 nm or more and less than 100 nm).
  • a ligand may be coordinated to the surface of the semiconductor quantum dot.
  • an organic semiconductor having a structure represented by any one of formulas 3-1 to 3-5 can also be used as the hole-transporting material.
  • X 1 and X 2 each independently represent S, O, Se, NR X1 or CR X2 R X3 , and R X1 to R X3 each independently represent a hydrogen atom or a substituent represent, Z 1 and Z 2 each independently represent N or CR Z1 , R Z1 represents a hydrogen atom or a substituent, R 1 to R 4 each independently represent a hydrogen atom or a substituent, n1 represents an integer from 0 to 2, * represents a bond.
  • R 1 and R 2 is a halogen atom, hydroxy group, cyano group, acylamino group, acyloxy group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, silyl group, alkyl group, alkenyl group, alkynyl group , an aryl group, an aryloxy group, an alkylthio group, an arylthio group, a heteroaryl group, a group represented by formula (R-100), or a group containing an inner salt structure.
  • L 100 represents a single bond or a divalent group
  • R 100 represents an acid group, a basic group, a group having an anion or a group having a cation.
  • X 3 to X 8 each independently represent S, O, Se, NR X4 or CR X5 R X6 , and R X4 to R X6 each independently represent a hydrogen atom or a substituent.
  • Z 3 and Z 4 each independently represent N or CR Z2
  • R Z2 represents a hydrogen atom or a substituent
  • R 5 to R 8 each independently represent a hydrogen atom or a substituent
  • n2 represents an integer from 0 to 2
  • * represents a bond.
  • X 9 to X 16 each independently represent S, O, Se, NR X7 or CR X8 R X9 , and R X7 to R X9 each independently represent a hydrogen atom or a substituent.
  • Z5 and Z6 each independently represent N or CRZ3, RZ3 represents a hydrogen atom or a substituent, * represents a bond.
  • R 9 to R 16 each independently represent a hydrogen atom or a substituent, n3 represents an integer of 0 to 2, * represents a bond.
  • X 17 to X 23 each independently represent S, O, Se, NR X10 or CR X11 R X12 , and R X10 to R X12 each independently represent a hydrogen atom or a substituent.
  • Z 7 to Z 10 each independently represent N or CR Z4 , R Z4 represents a hydrogen atom or a substituent, * represents a bond.
  • the thickness of the hole transport layer 22 is preferably 5 to 100 nm.
  • the lower limit is preferably 10 nm or more.
  • the upper limit is preferably 50 nm or less, more preferably 30 nm or less.
  • the second electrode layer 12 contains at least one metal atom selected from Au, Pt, Ir, Pd, Cu, Pb, Sn, Zn, Ti, W, Mo, Ta, Ge, Ni, Cr and In. It is preferably made of a metal material. By forming the second electrode layer 12 from such a metal material, a photodetector element with high external quantum efficiency and low dark current can be obtained.
  • the second electrode layer 12 is made of a metal material containing at least one metal atom selected from Au, Cu, Mo, Ni, Pd, W, Ir, Pt and Ta. It is more preferable to use a metal material containing at least one metal atom selected from Au, Pd, Ir, and Pt for the reason that it is large and migration is easily suppressed.
  • the Ag atom content in the second electrode layer 12 is preferably 98% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less. It is also preferable that the second electrode layer 12 does not substantially contain Ag atoms.
  • the case where the second electrode layer 12 does not substantially contain Ag atoms means that the content of Ag atoms in the second electrode layer 12 is 1% by mass or less, and 0.1% by mass or less. preferably contains no Ag atoms, and more preferably contains no Ag atoms.
  • the work function of the second electrode layer 12 is preferably 4.6 eV or more for the reason that the electron blocking property of the hole transport layer is enhanced and the holes generated in the device are easily collected. It is more preferably 5.7 eV, and even more preferably 4.9 to 5.3 eV.
  • the film thickness of the second electrode layer 12 is not particularly limited, and is preferably 0.01-100 ⁇ m, more preferably 0.01-10 ⁇ m, and particularly preferably 0.01-1 ⁇ m.
  • the photodetector of the present invention may have a blocking layer between the first electrode layer 11 and the electron transport layer 21 .
  • a blocking layer is a layer having a function of preventing reverse current.
  • a blocking layer is also called an anti-short circuit layer.
  • Materials forming the blocking layer include, for example, silicon oxide, magnesium oxide, aluminum oxide, calcium carbonate, cesium carbonate, polyvinyl alcohol, polyurethane, titanium oxide, tin oxide, zinc oxide, niobium oxide, and tungsten oxide.
  • the blocking layer may be a single layer film or a laminated film of two or more layers.
  • the wavelength ⁇ of the light to be detected by the photodetector and the surface of the second electrode layer 12 on the side of the photoelectric conversion layer 13 to the side of the first electrode layer 11 of the photoelectric conversion layer 13 It is preferable that the optical path length L ⁇ of the light of the wavelength ⁇ to the surface of the surface satisfies the relationship of the following formula (1-1), and more preferably satisfies the relationship of the following formula (1-2) preferable.
  • the wavelength ⁇ and the optical path length L ⁇ satisfy such a relationship, in the photoelectric conversion layer 13, the light (incident light) incident from the first electrode layer 11 side and the second electrode layer 12 As a result, the light is strengthened by the optical interference effect, and a higher external quantum efficiency can be obtained.
  • ⁇ is the wavelength of light to be detected by the photodetector
  • L ⁇ is the optical path length of light of wavelength ⁇ from the surface of the second electrode layer 12 on the side of the photoelectric conversion layer 13 to the surface of the photoelectric conversion layer 13 on the side of the first electrode layer
  • m is an integer of 0 or more.
  • m is preferably an integer of 0 to 4, more preferably an integer of 0 to 3, and even more preferably an integer of 0 to 2. According to this aspect, the transport characteristics of charges such as holes and electrons are excellent, and the external quantum efficiency of the photodetector can be further increased.
  • the optical path length means a value obtained by multiplying the physical thickness of a substance through which light passes by the refractive index.
  • d 1 be the thickness of the photoelectric conversion layer
  • N 1 be the refractive index of the photoelectric conversion layer for light of wavelength ⁇ 1 .
  • the optical path length of 1 light is N 1 ⁇ d 1 .
  • the photodetector of the present invention Since the photodetector of the present invention has excellent sensitivity to light with wavelengths in the infrared region, it is preferably used for detecting light with wavelengths in the infrared region. That is, the photodetector of the present invention is preferably an infrared photodetector. Moreover, it is preferable that the above-mentioned "target light to be detected by the photodetector" is light having a wavelength in the infrared region.
  • the light with a wavelength in the infrared region is preferably light with a wavelength exceeding 700 nm, more preferably light with a wavelength of 800 nm or longer, still more preferably light with a wavelength of 900 nm or longer, and a wavelength of 1000 nm or longer. is more preferable.
  • the light with a wavelength in the infrared region is preferably light with a wavelength of 2000 nm or less, more preferably light with a wavelength of 1800 nm or less, and even more preferably light with a wavelength of 1600 nm or less.
  • the photodetector of the present invention may simultaneously detect light with a wavelength in the infrared region and light with a wavelength in the visible region (preferably light with a wavelength in the range of 400 to 700 nm).
  • An image sensor of the present invention includes the photodetector of the present invention described above. Since the photodetector of the present invention has excellent sensitivity to light with wavelengths in the infrared region, it can be particularly preferably used as an infrared image sensor. Further, the image sensor of the present invention can be preferably used for sensing light with a wavelength of 900 to 2000 nm, and more preferably for sensing light with a wavelength of 900 to 1600 nm.
  • the configuration of the image sensor is not particularly limited as long as it includes the photodetector of the present invention and functions as an image sensor.
  • the image sensor may include an infrared transmission filter layer.
  • the infrared transmission filter layer preferably has low transmittance for light in the visible wavelength band, and more preferably has an average transmittance of 10% or less for light in the wavelength range of 400 to 650 nm. 0.5% or less is more preferable, and 5% or less is particularly preferable.
  • Examples of the infrared transmission filter layer include those composed of a resin film containing a coloring material.
  • Colorants include chromatic colorants such as red colorants, green colorants, blue colorants, yellow colorants, purple colorants, and orange colorants, and black colorants.
  • the colorant contained in the infrared transmission filter layer preferably forms a black color by combining two or more chromatic colorants or contains a black colorant.
  • the combination of chromatic colorants includes, for example, the following modes (C1) to (C7).
  • (C1) A mode containing a red colorant and a blue colorant.
  • C2 A mode containing a red colorant, a blue colorant, and a yellow colorant.
  • C3 A mode containing a red colorant, a blue colorant, a yellow colorant, and a purple colorant.
  • C4 A mode containing a red colorant, a blue colorant, a yellow colorant, a purple colorant, and a green colorant.
  • C5 A mode containing a red colorant, a blue colorant, a yellow colorant, and a green colorant.
  • C6 A mode containing a red colorant, a blue colorant, and a green colorant.
  • C7 An embodiment containing a yellow colorant and a purple colorant.
  • the chromatic colorant may be a pigment or a dye. It may contain pigments and dyes.
  • the black colorant is preferably an organic black colorant. Examples of organic black colorants include bisbenzofuranone compounds, azomethine compounds, perylene compounds, and azo compounds.
  • the infrared transmission filter layer may further contain an infrared absorber.
  • an infrared absorbing agent in the infrared transmission filter layer, the wavelength of light to be transmitted can be shifted to a longer wavelength side.
  • infrared absorbers include pyrrolopyrrole compounds, cyanine compounds, squarylium compounds, phthalocyanine compounds, naphthalocyanine compounds, quaterrylene compounds, merocyanine compounds, croconium compounds, oxonol compounds, iminium compounds, dithiol compounds, triarylmethane compounds, pyrromethene compounds, and azomethine. compounds, anthraquinone compounds, dibenzofuranone compounds, dithiolene metal complexes, metal oxides, metal borides, and the like.
  • the spectral characteristics of the infrared transmission filter layer can be appropriately selected according to the application of the image sensor.
  • a filter layer that satisfies any one of the following spectral characteristics (1) to (5) may be used.
  • the maximum value of the light transmittance in the thickness direction of the film in the wavelength range of 400 to 830 nm is 20% or less (preferably 15% or less, more preferably 10% or less), and the light in the thickness direction of the film. of 70% or more (preferably 75% or more, more preferably 80% or more) in the wavelength range of 1000 to 1500 nm.
  • the maximum value of the light transmittance in the thickness direction of the film in the wavelength range of 400 to 950 nm is 20% or less (preferably 15% or less, more preferably 10% or less), and the light in the film thickness direction of 70% or more (preferably 75% or more, more preferably 80% or more) in the wavelength range of 1100 to 1500 nm.
  • the maximum value of the light transmittance in the thickness direction of the film in the wavelength range of 400 to 1100 nm is 20% or less (preferably 15% or less, more preferably 10% or less), and the wavelength range is 1400 to 1500 nm. is 70% or more (preferably 75% or more, more preferably 80% or more).
  • the maximum value of the light transmittance in the thickness direction of the film in the wavelength range of 400 to 1300 nm is 20% or less (preferably 15% or less, more preferably 10% or less), and the wavelength range is 1600 to 2000 nm. is 70% or more (preferably 75% or more, more preferably 80% or more).
  • the infrared transmission filter JP 2013-077009, JP 2014-130173, JP 2014-130338, International Publication No. 2015/166779, International Publication No. 2016/178346, International Publication
  • the films described in WO 2016/190162, WO 2018/016232, JP 2016-177079, 2014-130332, and WO 2016/027798 can be used.
  • the infrared transmission filter may be used in combination of two or more filters, or a dual bandpass filter that transmits two or more specific wavelength regions with one filter may be used.
  • the image sensor may include an infrared shielding filter for the purpose of improving various performances such as noise reduction.
  • Specific examples of the infrared shielding filter include, for example, International Publication No. 2016/186050, International Publication No. 2016/035695, Patent No. 6248945, International Publication No. 2019/021767, JP 2017-067963, Patent A filter described in Japanese Patent No. 6506529 and the like are included.
  • the image sensor may include a dielectric multilayer film.
  • the dielectric multilayer film include those obtained by alternately laminating dielectric thin films with a high refractive index (high refractive index material layers) and dielectric thin films with a low refractive index (low refractive index material layers).
  • the number of laminated dielectric thin films in the dielectric multilayer film is not particularly limited, but is preferably 2 to 100 layers, more preferably 4 to 60 layers, and even more preferably 6 to 40 layers.
  • a material having a refractive index of 1.7 to 2.5 is preferable as the material used for forming the high refractive index material layer.
  • Specific examples include Sb2O3 , Sb2S3 , Bi2O3 , CeO2 , CeF3 , HfO2 , La2O3 , Nd2O3 , Pr6O11 , Sc2O3 , SiO , Ta 2 O 5 , TiO 2 , TlCl, Y 2 O 3 , ZnSe, ZnS, ZrO 2 and the like.
  • a material having a refractive index of 1.2 to 1.6 is preferable as the material used for forming the low refractive index material layer.
  • the method for forming the dielectric multilayer film is not particularly limited, but examples include vacuum deposition methods such as ion plating and ion beam, physical vapor deposition methods (PVD methods) such as sputtering, and chemical vapor deposition methods. (CVD method) and the like.
  • each of the high refractive index material layer and the low refractive index material layer is preferably 0.1 ⁇ to 0.5 ⁇ when the wavelength of light to be blocked is ⁇ (nm).
  • dielectric multilayer films include dielectric multilayer films described in JP-A-2014-130344 and JP-A-2018-010296.
  • the dielectric multilayer film preferably has a transmission wavelength band in the infrared region (preferably a wavelength region exceeding 700 nm, more preferably a wavelength region exceeding 800 nm, still more preferably a wavelength region exceeding 900 nm).
  • the maximum transmittance in the transmission wavelength band is preferably 70% or more, more preferably 80% or more, even more preferably 90% or more.
  • the maximum transmittance in the light shielding wavelength band is preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less.
  • the average transmittance in the transmission wavelength band is preferably 60% or more, more preferably 70% or more, and even more preferably 80% or more.
  • the wavelength range of the transmission wavelength band is preferably center wavelength ⁇ t1 ⁇ 100 nm, more preferably center wavelength ⁇ t1 ⁇ 75 nm, where ⁇ t1 is the wavelength showing the maximum transmittance. More preferably, the center wavelength ⁇ t1 ⁇ 50 nm.
  • the dielectric multilayer film may have only one transmission wavelength band (preferably a transmission wavelength band with a maximum transmittance of 90% or more), or may have a plurality of transmission wavelength bands.
  • the image sensor may include a color separation filter layer.
  • the color separation filter layer includes a filter layer containing colored pixels. Types of colored pixels include red pixels, green pixels, blue pixels, yellow pixels, cyan pixels, and magenta pixels.
  • the color separation filter layer may contain colored pixels of two or more colors, or may contain only one color. It can be appropriately selected according to the application and purpose.
  • a filter described in International Publication No. 2019/039172 can be used as the color separation filter layer.
  • the colored pixels of each color may be adjacent to each other, and partition walls may be provided between the colored pixels.
  • the material of the partition is not particularly limited. Examples include organic materials such as siloxane resins and fluorine resins, and inorganic particles such as silica particles.
  • the partition may be made of a metal such as tungsten or aluminum.
  • the color separation layer is preferably provided on a separate optical path from the infrared transmission filter layer. It is also preferable that the infrared transmission filter layer and the color separation layer are two-dimensionally arranged. In addition, the two-dimensional arrangement of the infrared transmission filter layer and the color separation layer means that at least a part of both of them are present on the same plane.
  • the image sensor may include an intermediate layer such as a flattening layer, a base layer, an adhesion layer, an antireflection film, and a lens.
  • an antireflection film for example, a film produced from the composition described in International Publication No. 2019/017280 can be used.
  • the lens for example, the structure described in International Publication No. 2018/092600 can be used.
  • Quantum dot dispersion liquid 1 After measuring 0.8 mmol of silver acetate, 1 mmol of bismuth acetate, and 30 mL of oleic acid in a three-necked flask, degassing was performed at 100° C. for 3 hours to dissolve the silver acetate and bismuth acetate to obtain a precursor solution. Obtained. While maintaining the temperature of the obtained precursor solution at 100° C., the system was switched to a nitrogen flow state, and 5 mL of an octadecene solution obtained by mixing 1.15 mmol of hexamethyldisilathiane in the mixed solution was added to obtain nuclei. formed.
  • Quantum dot dispersion liquid 2 After measuring 0.8 mmol of silver acetate, 1 mmol of bismuth acetate, and 30 mL of oleic acid in a three-necked flask, degassing was performed at 100° C. for 3 hours to dissolve the silver acetate and bismuth acetate to obtain a precursor solution. Obtained. While maintaining the temperature of the obtained precursor solution at 100° C., the system was switched to a nitrogen flow state, and 5 mL of an octadecene solution mixed with 1.20 mmol of hexamethyldisilathiane was added to form nuclei. After that, the temperature of the liquid in the flask was cooled to room temperature.
  • Quantum dot dispersion liquid 4 After measuring 0.8 mmol of silver acetate, 1 mmol of bismuth acetate, 5.4 mL of oleic acid, and 25 mL of octadecene in a three-necked flask, deaeration was performed at 100° C. for 3 hours to remove silver acetate and bismuth acetate. It was dissolved to obtain a precursor solution.
  • a drop cast film having a thickness of about 500 nm was produced using each of the above quantum dot dispersions.
  • the elemental composition ratio of the obtained drop cast film was measured, and the number of Ag atoms with respect to the number of chalcogen atoms. The number ratio (Ag ratio) was calculated.
  • the quantum dot dispersions 3 and 4 the ratio of the number of Te atoms to the total number of S atoms and Te atoms (Te ratio) was also calculated.
  • the elemental composition ratio was measured at three points in the same drop-cast film, and the average value thereof was calculated as the elemental composition ratio of the drop-cast film.
  • Zinc oxide particle dispersion liquid 1 1.5 mmol of zinc acetate dihydrate and 15 ml of dimethylsulfoxide (DMSO) were weighed into a flask and stirred to obtain a zinc acetate solution.
  • DMSO dimethylsulfoxide
  • a TMACl solution of 4 mmol of tetramethylammonium chloride (TMACl) dissolved in 4 ml of methanol and a KOH solution of 4 mmol of potassium hydroxide (KOH) dissolved in 4 ml of methanol were prepared.
  • TMAH tetramethylammonium hydroxide
  • ITO Indium Tin Oxide
  • the ITO film was spin-coated at 3000 rpm with a solution of 1 g of zinc acetate dihydrate and 284 ⁇ l of ethanolamine dissolved in 10 ml of methoxyethanol. After that, it was heated at 200° C. for 30 minutes to form a zinc oxide sol-gel film having a thickness of about 40 nm. Then, the zinc oxide particle dispersion 1 was dropped onto the sol-gel film, spin-coated at 2500 rpm, and heated at 70° C. for 30 minutes. , and 30 mW/cm 2 (wavelength peak 254 nm) for 5 minutes, a zinc oxide particle film having a thickness of about 130 nm was formed to form an electron transport layer.
  • the quantum dot dispersion liquid described in the following table was dropped onto the electron transport layer thus formed, followed by spin coating at 2000 rpm to obtain a quantum dot assembly film (step 1).
  • a quantum dot assembly film as a ligand solution, a methanol solution (concentration of 0.02 vol%) or an acetonitrile solution (concentration of 0.02 vol%) of the ligand described in the table below is dropped. , 20 seconds, and spin-dried at 2000 rpm for 20 seconds. After dropping the ligand solution again, it was allowed to stand still for 20 seconds and spin-dried at 2000 rpm for 20 seconds.
  • step 2 methanol or acetonitrile (selected according to the solvent of the ligand solution) was dropped onto the quantum dot assembly film as a rinsing liquid and spin-dried at 2000 rpm for 20 seconds.
  • octane was dropped onto the quantum dot assembly film and spin-dried at 2000 rpm for 20 seconds (step 2).
  • the operation of step 1 and step 2 as one cycle is repeated four times to form a photoelectric conversion layer with a thickness of about 70 nm in which the ligands of the ligand solution described in the table below are coordinated to the semiconductor quantum dots. bottom.
  • the photoelectric conversion layer was dried at 100° C. for 10 minutes in a nitrogen atmosphere, and then dried at room temperature for 10 hours in a nitrogen atmosphere under light-shielding conditions.
  • a hole transport layer was formed on the photoelectric conversion layer by spin coating a chlorobenzene solution of PTB7-Th (10 mg/mL) and PC71BM (10 mg/mL) at 2000 rpm for 60 seconds.
  • PC71BM [6,6]-phenyl-C71-methyl butyrate
  • PTB7-Th Poly([2,6′-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,3-b ]dithiophene] ⁇ 3-fluoro-2[(2-ethylhexyl l)carbonyl]thieno[3,4-b]thiophenediyl ⁇ )
  • a 15 nm-thick MoO 3 film was formed on the hole-transporting layer by vacuum deposition through a metal mask, and then a 100 nm-thick Au film (second electrode layer) was formed.
  • a photodiode-type photodetector was manufactured using the above method.
  • TMAI tetramethylammonium iodide
  • EDT 1,2-ethanedithiol MeOH: methanol
  • ACN acetonitrile
  • the IV characteristics were measured while sweeping the voltage from 0V to -2V while irradiating monochromatic light (50 ⁇ W/cm 2 ) of 940 nm.
  • a photocurrent value was obtained by subtracting the above dark current value from the current value when ⁇ 0.5 V was applied, and the external quantum efficiency (EQE) was calculated from this value.
  • the photodetector elements of Examples had a higher external quantum efficiency (EQE) and a lower dark current than the photodetector elements of Comparative Examples. Furthermore, ⁇ EQE was small and stability was excellent.
  • the external quantum efficiency of the photodetector of Example 5 was 5.2%, indicating a high external quantum efficiency. Further, the dark current of the photodetector of Example 5 was as low as that of Example 1. Also, the ⁇ EQE of the photodetector of Example 5 was 7.1%, indicating excellent stability. Moreover, the external quantum efficiency of the photodetector of Example 6 was 5.6%, indicating a high external quantum efficiency. Further, the dark current of the photodetector of Example 6 was as low as that of Example 1. In addition, the ⁇ EQE of the photodetector of Example 6 was 6.7%, indicating excellent stability.
  • Examples 5 and 6 had higher external quantum efficiencies than those of Examples 1 to 4 and Comparative Example 1 for light with a wavelength of 1100 nm.
  • the photodetector elements of Examples 5 and 6 can be preferably used as detector elements for light having a wavelength exceeding 1100 nm.
  • an image sensor was produced by a known method together with an optical filter produced according to the methods described in WO 2016/186050 and WO 2016/190162. , it is possible to obtain an image sensor having good visible/infrared imaging performance by incorporating it into a solid-state imaging device.
  • Photodetector 11 First electrode layer 12: Second electrode layer 13: Photoelectric conversion layer 21: Electron transport layer 22: Hole transport layer

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  • Solid State Image Pick-Up Elements (AREA)
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