Semiconductor quantum dot, dispersion liquid, semiconductor film, light detection element, image sensor, and method for manufacturing semiconductor quantum dot

Abstract

The present invention provides: a semiconductor quantum dot which contains an In element, an Sb element, and a P element, wherein the ratio of the molar amount of the P element to the molar amount of the Sb element is 0.20 or more and less than 1.00; and a method for manufacturing the semiconductor quantum dot. The present invention also provides a dispersion liquid, a semiconductor film, a light detection element, and an image sensor comprising the quantum dot.

Description

Semiconductor quantum dots, dispersion, semiconductor film, photodetector, image sensor, and method for producing semiconductor quantum dots

[0001] The present invention relates to semiconductor quantum dots and semiconductor films containing semiconductor quantum dots, and also to a photodetector, an image sensor, and a method for manufacturing semiconductor quantum dots.

[0002] In recent years, photodetectors capable of detecting light in the infrared region have been attracting attention in the fields of smartphones, surveillance cameras, in-vehicle cameras, and the like.

[0003] Conventionally, silicon photodiodes, which use silicon wafers as the material for the photoelectric conversion layer, have been used as photodetectors for image sensors, etc. However, silicon photodiodes have low sensitivity in the infrared region with wavelengths of 900 nm or more.

[0004] Furthermore, InGaAs-based semiconductor materials, which are known as near-infrared light receiving elements, have the problem of requiring very costly processes, such as epitaxial growth and substrate bonding processes, to achieve high quantum efficiency, and this has prevented them from becoming widely used.

[0005] In recent years, the use of semiconductor quantum dots in photoelectric conversion elements has also been considered. For example, Patent Document 1 describes the use of PbS quantum dots in the photoelectric conversion layer of a photoelectric conversion element.

[0006] Japanese Patent Application Laid-Open No. 2020-150251

[0007] In recent years, with the demand for improved performance of image sensors and the like, further improvements are being demanded in the characteristics required of the photodetector elements used therein. For example, one of the characteristics required of a photodetector element is that it has a high external quantum efficiency for light of the target wavelength to be detected by the photodetector element, and that the external quantum efficiency of the photodetector element has little variation within its surface. By increasing the external quantum efficiency of the photodetector element, it is possible to improve the light detection accuracy of the photodetector element. Furthermore, by reducing the variation within the surface of the external quantum efficiency of the photodetector element, it is possible to suppress the generation of noise and the like.

[0008] Furthermore, it is preferable for the dark current of the photodetector element to be small. By reducing the dark current of the photodetector element, a higher signal-to-noise ratio (S / N ratio) can be obtained in the image sensor. Dark current is the current that flows when no light is irradiated.

[0009] The present inventors have conducted further studies on a photodetector element using semiconductor quantum dots containing In and Sb elements in a photoelectric conversion layer, and have found that there is room for further improvement in these characteristics.

[0010] Therefore, an object of the present invention is to provide semiconductor quantum dots that can form a semiconductor film having high external quantum efficiency, excellent in-plane uniformity of the external quantum efficiency, and reduced dark current. Another object of the present invention is to provide a dispersion, a semiconductor film, a photodetector, an image sensor, and a method for producing the semiconductor quantum dots.

[0011] The present invention provides the following. <1> Semiconductor quantum dots containing In, Sb, and P, wherein the molar ratio of P to Sb is 0.20 or more and less than 1.00. <2> The semiconductor quantum dots according to <1>, wherein the molar ratio of In to the sum of Sb and P is 1.00 or more and 1.70 or less. <3> The semiconductor quantum dots according to <1> or <2>, wherein the band gap of the semiconductor quantum dots is 1.0 eV or less. <4> The semiconductor quantum dots according to any one of <1> to <3>, wherein the average primary particle size of the semiconductor quantum dots is 3 to 10 nm. <5> A dispersion comprising the semiconductor quantum dots according to any one of <1> to <4>, a ligand, and a solvent. <6> A semiconductor film comprising an aggregate of semiconductor quantum dots according to any one of <1> to <4>, and a ligand coordinated to the semiconductor quantum dots. <7> The semiconductor film according to <6>, wherein the ligand includes an inorganic ligand. <8> A photodetector including the semiconductor film according to <6> or <7>. <9> An image sensor including the photodetector according to <8>. <10> A method for producing semiconductor quantum dots according to <1>, comprising the steps of: adding a reducing agent to precursor solution A containing a compound containing In and a compound containing Sb, and reacting them in the presence of the reducing agent to obtain reaction solution B containing a reaction product of the compound containing In and the compound containing Sb; and adding precursor solution C containing a compound containing P to reaction solution B to react the reaction product with the compound containing P. <11> A method for producing semiconductor quantum dots according to <10>, wherein precursor solution C is added to reaction solution B at 230°C or higher. <12> A method for producing semiconductor quantum dots according to <10> or <11>, wherein the compound containing In is an indium halide. <13> The method for producing semiconductor quantum dots according to any one of <10> to <12>, wherein the compound containing Sb is an antimony halide. <14> The method for producing semiconductor quantum dots according to any one of <10> to <13>, wherein the precursor solution A contains an amine compound having 12 to 20 carbon atoms.<15> The method for producing semiconductor quantum dots according to any one of <10> to <14>, wherein the compound containing P includes at least one selected from the group consisting of tris(dimethylamino)phosphine, tris(diethylamino)phosphine, tris(dipropylamino)phosphine, and tris(dibutylamino)phosphine.

[0012] According to the present invention, it is possible to provide semiconductor quantum dots that can form a semiconductor film having high external quantum efficiency, excellent in-plane uniformity of the external quantum efficiency, and reduced dark current. The present invention also provides a dispersion, a semiconductor film, a photodetector, an image sensor, and a method for manufacturing the semiconductor quantum dots.

[0013] FIG. 2 illustrates an embodiment of a photodetector element.

[0014] The present invention will be described in detail below. In this specification, the term "to" is used to mean that the numerical values ​​before and after it are included as the lower and upper limits. In the description of groups (atomic groups) in this specification, a notation that does not specify whether they are substituted or unsubstituted includes both groups (atomic groups) that have no substituents and groups (atomic groups) that have substituents. For example, the term "alkyl group" includes not only alkyl groups that have no substituents (unsubstituted alkyl groups) but also alkyl groups that have substituents (substituted alkyl groups).

[0015] <Semiconductor Quantum Dots> The semiconductor quantum dots of the present invention are semiconductor quantum dots containing In, Sb, and P, characterized in that the molar ratio of P to Sb is 0.20 or more and less than 1.00.

[0016] The semiconductor quantum dots of the present invention can form a semiconductor film with high external quantum efficiency, excellent in-plane uniformity of external quantum efficiency, and reduced dark current. The reason for this effect is presumed to be as follows. Specifically, the semiconductor quantum dots of the present invention contain a P element, and the molar ratio of the P element to the Sb element is 0.20 or more and less than 1.00. This presumably allows the P element to be appropriately distributed unevenly in the surface layer of the semiconductor quantum dots. It is presumed that the P element is more likely to be coordinated with a ligand than the Sb element, and the uneven distribution of the P element in the surface layer facilitates coordination of the ligand to the surface of the semiconductor quantum dots and can suppress detachment of the ligand from the surface of the semiconductor quantum dots. Therefore, it is presumed that a semiconductor film using the semiconductor quantum dots of the present invention can maintain an appropriate distance between the semiconductor quantum dots in the semiconductor film and reduce surface defects of the semiconductor quantum dots. For these reasons, it is presumed that the semiconductor quantum dots of the present invention have a high external quantum efficiency, excellent in-plane uniformity of the external quantum efficiency, and a semiconductor film with reduced dark current.

[0017] Furthermore, when the semiconductor quantum dots of the present invention are used as a dispersion, the dispersion also has excellent dispersibility. As described above, it is presumed that this is because the ligands of the semiconductor quantum dots of the present invention are easily coordinated to the surface of the semiconductor quantum dots, and therefore the ligands coordinated to the semiconductor quantum dots can efficiently suppress aggregation of the semiconductor quantum dots in the dispersion.

[0018] In the semiconductor quantum dots, the ratio of the molar amount of P element to the molar amount of Sb element is preferably 0.20 or more and 0.90 or less, more preferably 0.20 or more and 0.80 or less, and even more preferably 0.20 or more and 0.60 or less.

[0019] In the semiconductor quantum dots, the ratio of the molar amount of In element to the sum of the molar amounts of Sb element and P element is preferably 1.00 to 1.70, the upper limit is preferably 1.50 or less, and the lower limit is preferably 1.20 or more.

[0020] In this specification, the "ratio of the molar amount of P element to the molar amount of Sb element" and the "ratio of the molar amount of In element to the sum of the molar amounts of Sb element and P element" for semiconductor quantum dots can be calculated by measuring the element composition ratio by X-ray photoelectron spectroscopy.

[0021] The "ratio of the molar amount of P element to the molar amount of Sb element" and the "ratio of the molar amount of In element to the sum of the molar amounts of Sb element and P element" for semiconductor quantum dots can be adjusted by changing the reaction ratio of each raw material during synthesis of the semiconductor quantum dots, reaction conditions, etc.

[0022] The band gap of the semiconductor quantum dots is preferably 1.2 eV or less, more preferably 1.0 eV or less. The lower limit of the band gap of the semiconductor quantum dots is not particularly limited, but is preferably 0.3 eV or more, more preferably 0.5 eV or more.

[0023] The average primary particle diameter of the semiconductor quantum dots is preferably 3 to 10 nm. The lower limit is preferably 4 nm or more. The upper limit is preferably 8 nm or less. In this specification, the average primary particle diameter of the semiconductor quantum dots is the average (arithmetic mean) of the equivalent circle diameters of the primary particles of 500 randomly selected semiconductor quantum dots. The equivalent circle diameter of the primary particle of the semiconductor quantum dots is determined by measuring the particle area S of one particle in an electron micrograph taken with a transmission electron microscope, and calculating the diameter of a perfect circle corresponding to this area S (equivalent circle diameter = 2(S / π) ０．５ The particle size of the semiconductor quantum dots can be measured by diluting a dispersion of the semiconductor quantum dots with a non-polar solvent, dropping it onto a microgrid, and then drying the film formed, and measuring the film using a transmission electron microscope.

[0024] The crystal structure of the semiconductor quantum dots is not particularly limited, but is preferably a cubic or hexagonal crystal structure because it is easy to achieve high crystallinity. The crystal structure of the semiconductor quantum dots can be measured by X-ray diffraction or electron beam diffraction.

[0025] The semiconductor quantum dots of the present invention may further contain elements other than In, Sb, and P. Examples of other elements include Mg, Ca, Sr, Ba, Zn, Cd, Hg, B, Al, Ga, N, As, and Bi.

[0026] Specific examples of the semiconductor quantum dots of the present invention include InSbP. The semiconductor quantum dots of the present invention may also be semiconductor quantum dots with a core-shell structure having a core containing In and Sb and a shell containing P that covers the core. Examples of the core containing In and Sb include InSb.

[0027] <Method for Producing Semiconductor Quantum Dots> The method for producing semiconductor quantum dots of the present invention is the method for producing semiconductor quantum dots of the present invention described above, and is characterized by comprising: a step (first step) of adding a reducing agent to precursor solution A containing a compound containing In element and a compound containing Sb element, and causing a reaction in the presence of the reducing agent to obtain reaction solution B containing a reaction product of the compound containing In element and the compound containing Sb element; and a step (second step) of adding precursor solution C containing a compound containing P element to reaction solution B, and causing a reaction between the reaction product and the compound containing P element.

[0028] (First Step) In the first step, a precursor solution A containing a compound containing an In element and a compound containing an Sb element is reacted in the presence of a reducing agent to obtain a reaction solution B containing a reaction product of the compound containing an In element and the compound containing an Sb element.

[0029] The compound containing In element contained in precursor solution A is preferably an indium halide. Specific examples of indium halides include indium chloride, indium bromide, indium iodide, and indium fluoride, and indium chloride is preferred.

[0030] The compound containing Sb element contained in precursor solution A is preferably an antimony halide. Specific examples of antimony halides include antimony chloride, antimony bromide, antimony iodide, and antimony fluoride, and antimony chloride is preferred.

[0031] In the precursor solution A, the ratio of the compound containing In and the compound containing Sb is preferably 0.1 to 1.0 moles of the compound containing Sb per mole of the compound containing In. The upper limit is preferably 0.75 moles or less, and more preferably 0.6 moles or less. The lower limit is preferably 0.2 moles or more, and more preferably 0.4 moles or more.

[0032] The precursor solution A preferably contains an amine compound, which is preferably an amine compound having 12 to 20 carbon atoms, and more preferably an amine compound having 14 to 20 carbon atoms.

[0033] The molecular weight of the amine compound is preferably 100 to 500. The upper limit is preferably 400 or less, more preferably 350 or less. The lower limit is preferably 150 or more, more preferably 200 or more.

[0034] The amine compound is preferably a compound represented by formula (Am-1). ａｍ１ -NH ２ ...(Am-1) In the formula, R ａｍ１ represents a hydrocarbon group having 12 to 20 carbon atoms. ａｍ１ is preferably a hydrocarbon group having 14 to 20 carbon atoms. The hydrocarbon group is preferably an aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be a saturated aliphatic hydrocarbon group or an unsaturated aliphatic hydrocarbon group. An unsaturated aliphatic hydrocarbon group is preferred.

[0035] The amine compound is preferably in a liquid state at 25° C. In this specification, the phrase "in a liquid state at 25° C." means that the amine compound has a pour point at a temperature of 25° C. or lower and exhibits fluidity at 25° C.

[0036] Specific examples of the amine compound include oleylamine, 1-aminodecane, dodecylamine, and stearylamine.

[0037] The content of the amine compound in the precursor solution A is preferably 0.1 to 500 mmol / L, and more preferably 0.5 mmol / L to 100 mmol / L.

[0038] The precursor solution A is preferably prepared by adding a compound containing In and a compound containing Sb to an amine compound and mixing them. The order of adding the compound containing In and the compound containing Sb is not particularly limited. The compound containing In may be added first, the compound containing Sb may be added first, or the compound containing In and the compound containing Sb may be added simultaneously. From the viewpoint of productivity, it is preferable to add the compound containing In first, and then add the compound containing Sb.

[0039] Examples of the reducing agent include a boron hydride-based reducing agent, a silicon hydride-based reducing agent, an aluminum hydride-based reducing agent, a calcium hydride-based reducing agent, a hydrazine-based reducing agent, and hydrogen. A boron hydride-based reducing agent, a silicon hydride-based reducing agent, or an aluminum hydride-based reducing agent is preferred, and a boron hydride-based reducing agent is more preferred.

[0040] Examples of boron hydride reducing agents include diborane, borane-tetrahydrofuran complex, sodium borohydride, lithium borohydride, lithium tri(sec-butyl)borohydride, potassium tri(sec-butyl)borohydride, lithium triethylborohydride, and catecholborane.

[0041] Examples of silicon hydride reducing agents include triethylsilane, dimethylphenylsilane, and diphenylsilane.

[0042] Examples of aluminum hydride reducing agents include lithium aluminum hydride, sodium bis(2-methoxyethoxy)aluminum hydride, diisobutylaluminum hydride, alkoxyaluminum hydride, and aluminum hydride.

[0043] Examples of calcium hydride reducing agents include calcium hydride.

[0044] Examples of the hydrazine-based reducing agent include hydrazine and its derivatives.

[0045] The reducing agent is preferably at least one selected from lithium aluminum hydride, sodium bis(2-methoxyethoxy)aluminum hydride, and lithium triethylborohydride, and more preferably lithium triethylborohydride.

[0046] The amount of reducing agent added is preferably 1.3 to 4.5 moles per mole of the total of the In-containing compound and the Sb-containing compound. The upper limit is preferably 3.9 moles or less, and more preferably 3.2 moles or less. The lower limit is preferably 1.6 moles or more, and more preferably 1.9 moles or more.

[0047] The reaction temperature is preferably 260 to 300° C. The upper limit is preferably 295° C. or less, more preferably 290° C. or less. The lower limit is preferably 250° C. or more, more preferably 270° C. or more.

[0048] The reaction time is preferably 1 minute or more, more preferably 5 minutes or more, and even more preferably 15 minutes or more. There is no particular upper limit, but from the viewpoint of productivity, it is preferably 100 minutes or less, more preferably 90 minutes or less, and even more preferably 40 minutes or less.

[0049] The reaction may be carried out in air, vacuum, or an inert gas atmosphere. To prevent oxidation of the resulting semiconductor quantum dots, the reaction is preferably carried out in an inert gas atmosphere. Examples of inert gases include nitrogen gas and argon gas.

[0050] (Second Step) In the second step, a precursor solution C containing a compound containing a phosphorus element is added to the reaction solution B, and the reactant and the compound containing a phosphorus element are reacted with each other.

[0051] Examples of the compound containing P element contained in the precursor solution C include trisdimethylaminophosphine, trisdiethylaminophosphine, trisdipropylaminophosphine, and trisdibutylaminophosphine.

[0052] The precursor solution C preferably contains an amine compound. The amine compound is preferably an amine compound having 12 to 20 carbon atoms, and more preferably an amine compound having 14 to 20 carbon atoms. The amine compound is preferably a compound represented by the above formula (Am-1). Specific examples of the amine compound include oleylamine, 1-aminodecane, dodecylamine, and stearylamine.

[0053] The content of the amine compound in the precursor solution C is preferably 0.1 to 500 mmol / L, and more preferably 0.5 mmol / L to 100 mmol / L.

[0054] In the second step, it is preferable to add the precursor solution C to the reaction solution B at 230° C. or higher (preferably 260 to 300° C., more preferably 270 to 290° C.). According to this embodiment, the reaction between the reactant and the compound containing P can be moderately advanced, and the molar ratio of P to Sb in the resulting semiconductor quantum dots can be easily adjusted to a range of 0.20 or higher and less than 1.00.

[0055] The mixing ratio of the reaction solution B and the precursor solution C is preferably such that the amount of the compound containing P contained in the precursor solution C is 0.1 to 1.0 moles per mole of the total of In and Sb contained in the reaction solution B. The upper limit is preferably 0.8 moles or less, and more preferably 0.4 moles or less. The lower limit is preferably 0.2 moles or more.

[0056] After the reaction is completed, it is preferable to cool the reaction mixture to 40° C. or less. The cooling may be natural cooling or forced cooling.

[0057] The semiconductor quantum dots of the present invention can be produced through the above steps. The semiconductor quantum dots obtained by the production method of the present invention may be semiconductor quantum dots with a core-shell structure having a core containing In and Sb and a shell containing P that covers the core.

[0058] <Dispersion> The dispersion of the present invention contains the semiconductor quantum dots of the present invention described above, a ligand, and a solvent.

[0059] The content of the semiconductor quantum dots in the dispersion is preferably 1 to 500 mg / mL, more preferably 10 to 200 mg / mL, and even more preferably 20 to 100 mg / mL.

[0060] Examples of the ligand contained in the dispersion include ligands that function as ligands that coordinate to the semiconductor quantum dots and have a molecular structure that easily causes steric hindrance, and that also serve as dispersants that disperse the semiconductor quantum dots in the solvent. Examples of such ligands include ligands having at least 6 or more carbon atoms in the main chain, and preferably ligands having 10 or more carbon atoms in the main chain. The ligands may be either saturated or unsaturated compounds. Specific examples include decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, erucic acid, oleylamine, stearylamine, 1-aminodecane, dodecylamine, aniline, dodecanethiol, 1,2-hexadecanethiol, tributylphosphine, trihexylphosphine, trioctylphosphine, tributylphosphine oxide, trioctylphosphine oxide, and cetrimonium bromide.

[0061] The ligand contained in the dispersion may be an organic ligand or an inorganic ligand, which is explained as the ligand contained in the semiconductor film described later.

[0062] The content of the ligand in the dispersion is preferably 0.2 mol / L to 3.0 mol / L, and more preferably 0.2 mol / L to 0.5 mol / L.

[0063] The solvent contained in the dispersion is not particularly limited, but is preferably a solvent that hardly dissolves the semiconductor quantum dots and easily dissolves the ligands. Organic solvents are preferred. Specific examples include alkanes (n-hexane, n-octane, etc.), alkenes (octadecene, etc.), benzene, toluene, etc. The solvent contained in the dispersion of the present invention may be a single solvent or a mixed solvent of two or more solvents.

[0064] The content of the solvent in the dispersion is preferably from 50 to 99% by mass, more preferably from 70 to 99% by mass, and even more preferably from 90 to 98% by mass.

[0065] The dispersion may further contain other components to the extent that the effects of the present invention are not impaired.

[0066] <Semiconductor Film> The semiconductor film of the present invention contains the above-described aggregate of semiconductor quantum dots of the present invention and ligands that coordinate to the semiconductor quantum dots.

[0067] The term "assembly of semiconductor quantum dots" refers to a large number of semiconductor quantum dots (for example, 1 μm ２ In this specification, the term "semiconductor" refers to a semiconductor having a resistivity of 10 －２ Ωcm or more 10 ８ This refers to a substance with a resistivity of Ωcm or less.

[0068] The semiconductor film of the present invention contains a ligand that coordinates to the semiconductor quantum dots. Examples of the ligand include organic and inorganic ligands. The ligand preferably contains an inorganic ligand, because this allows for the production of a semiconductor film with lower dark current, higher external quantum efficiency, and superior in-plane uniformity of external quantum efficiency.

[0069] The organic ligand may be a monodentate organic ligand having one coordination moiety, or a polydentate organic ligand having two or more coordination moieties. Examples of the coordination moiety contained in the organic ligand include a thiol group, an amino group, a hydroxyl group, a carboxyl group, a sulfo group, a phospho group, and a phosphonic acid group.

[0070] The polydentate ligand may be a ligand represented by any one of formulas (A) to (C).

[0071] In formula (A), X Ａ１ and X Ａ２ each independently represents 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.

[0072] In formula (B), X Ｂ１ and X Ｂ２ each independently represents a thiol group, an amino group, a hydroxy group, a carboxy group, a sulfo group, a phospho group, or a phosphonic acid group; Ｂ３ represents S, O or NH; L Ｂ１ and L Ｂ２ each independently represents a hydrocarbon group.

[0073] In formula (C), X Ｃ１ ~X Ｃ３ each independently represents a thiol group, an amino group, a hydroxy group, a carboxy group, a sulfo group, a phospho group, or a phosphonic acid group; Ｃ４ represents N, and L Ｃ１ ~L Ｃ３ each independently represents a hydrocarbon group.

[0074] X Ａ１ , X Ａ２ , X Ｂ１ , X Ｂ２ , X Ｃ１ , X Ｃ２ and X Ｃ３ The amino group represented by is -NH ２The amino group is not limited to the above, and also includes a substituted amino group and a cyclic amino group. Examples of the substituted amino group include a monoalkylamino group, a dialkylamino group, a monoarylamino group, a diarylamino group, and an alkylarylamino group. The amino group represented by these groups includes -NH ２ , a monoalkylamino group, or a dialkylamino group is preferred, and —NH ２ It is more preferable that:

[0075] X in formula (A) Ａ１ and X Ａ２ At least one of the groups is preferably a thiol group. The other may be a thiol group or a group other than a thiol group. The group other than a thiol group is preferably a carboxy group, an amino group, or a hydroxy group.

[0076] X in formula (B) Ｂ１ and X Ｂ２ At least one of the groups is preferably a thiol group. The other may be a thiol group or a group other than a thiol group. The group other than a thiol group is preferably a carboxy group, an amino group, or a hydroxy group.

[0077] X in formula (C) Ｃ１ ~X Ｃ３ At least one of the groups is preferably a thiol group. The other may be a thiol group or a group other than a thiol group. The group other than a thiol group is preferably a carboxy group, an amino group, or a hydroxy group.

[0078] L Ａ１ , L Ｂ１ , L Ｂ２ , L Ｃ１ , L Ｃ２ and L Ｃ３The hydrocarbon group represented by is preferably an aliphatic hydrocarbon group or a group containing an aromatic ring, and more preferably an aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be a saturated aliphatic hydrocarbon group or an unsaturated aliphatic hydrocarbon group. The hydrocarbon group preferably has 1 to 20 carbon atoms. The upper limit of the carbon number is preferably 10 or less, more preferably 6 or less, and even more preferably 3 or less. Specific examples of the hydrocarbon group include an alkylene group, an alkenylene group, an alkynylene group, and an arylene group.

[0079] Examples of the alkylene group include a linear alkylene group, a branched alkylene group, and a cyclic alkylene group, and are preferably a linear alkylene group or a branched alkylene group, and more preferably a linear alkylene group. Examples of the alkenylene group include a linear alkenylene group, a branched alkenylene group, and a cyclic alkenylene group, and are preferably a linear alkenylene group or a branched alkenylene group, and more preferably a linear alkenylene group. Examples of the alkynylene group include a linear alkynylene group and a branched alkynylene group, and are preferably a linear alkynylene group. The arylene group 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, and are preferably a phenylene group. 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. Specific preferred examples of the group having 1 to 10 atoms include alkyl groups having 1 to 3 carbon atoms [methyl, ethyl, propyl, and isopropyl], alkenyl groups having 2 to 3 carbon atoms [ethenyl and propenyl], alkynyl groups having 2 to 4 carbon atoms [ethynyl, propynyl, etc.], cyclopropyl groups, alkoxy groups having 1 to 2 carbon atoms [methoxy and ethoxy], acyl groups having 2 to 3 carbon atoms [acetyl and propionyl], alkoxycarbonyl groups having 2 to 3 carbon atoms [methoxycarbonyl and ethoxycarbonyl], acyloxy groups having 2 carbon atoms [acetyloxy], Examples of such an alkyl group include an acylamino group (acetylamino group), a hydroxyalkyl group having 1 to 3 carbon atoms (hydroxymethyl group, hydroxyethyl group, hydroxypropyl group), an aldehyde group, a hydroxy group, a carboxy group, a sulfo group, a phospho group, a carbamoyl group, a cyano group, an isocyanate group, a thiol group, a nitro group, a nitroxy group, an isothiocyanate group, a cyanate group, a thiocyanate group, an acetoxy group, an acetamido group, a formyl group, a formyloxy group, a formamido group, a sulfamino group, a sulfino group, a sulfamoyl group, a phosphono group, an acetyl group, a halogen atom, and an alkali metal atom.

[0080] In formula (A), X Ａ１and X Ａ２ Is L Ａ１ Preferably, they are separated by 1 to 10 atoms, more preferably by 1 to 6 atoms, even more preferably by 1 to 4 atoms, even more preferably by 1 to 3 atoms, and particularly preferably by 1 or 2 atoms.

[0081] In formula (B), X Ｂ１ and X Ｂ３ Is L Ｂ１ Preferably, they are separated by 1 to 10 atoms, more preferably 1 to 6 atoms, even more preferably 1 to 4 atoms, still more preferably 1 to 3 atoms, and particularly preferably 1 or 2 atoms. Ｂ２ and X Ｂ３ Is L Ｂ２ Preferably, they are separated by 1 to 10 atoms, more preferably by 1 to 6 atoms, even more preferably by 1 to 4 atoms, even more preferably by 1 to 3 atoms, and particularly preferably by 1 or 2 atoms.

[0082] In formula (C), X Ｃ１ and X Ｃ４ Is L Ｃ１ Preferably, they are separated by 1 to 10 atoms, more preferably 1 to 6 atoms, even more preferably 1 to 4 atoms, still more preferably 1 to 3 atoms, and particularly preferably 1 or 2 atoms. Ｃ２ and X Ｃ４ Is L Ｃ２ Preferably, they are separated by 1 to 10 atoms, more preferably 1 to 6 atoms, even more preferably 1 to 4 atoms, still more preferably 1 to 3 atoms, and particularly preferably 1 or 2 atoms. Ｃ３ and X Ｃ４ Is L Ｃ３Preferably, they are separated by 1 to 10 atoms, more preferably by 1 to 6 atoms, even more preferably by 1 to 4 atoms, even more preferably by 1 to 3 atoms, and particularly preferably by 1 or 2 atoms.

[0083] In addition, X Ａ１ and X Ａ２ Is L Ａ１ The term "separated by 1 to 10 atoms" means that X Ａ１ and X Ａ２ This means that the number of atoms constituting the molecular chain with the shortest distance connecting X is 1 to 10. For example, in the case of the following formula (A1), X Ａ１ and X Ａ２ and are separated by two atoms, and in the case of the following formula (A2) and formula (A3), X Ａ１ and X Ａ２ The numbers in the following structural formulas represent X Ａ１ and X Ａ２ It represents the order of the arrangement of atoms that make up the shortest molecular chain connecting the

[0084] To explain this by taking a specific compound, 3-mercaptopropionic acid is X Ａ１ The site corresponding to X is a carboxy group. Ａ２ The site corresponding to is a thiol group, and L Ａ１ In 3-mercaptopropionic acid, the site corresponding to X is an ethylene group (compound with the following structure). Ａ１ (carboxy group) and X Ａ２ (thiol group) and L Ａ１ (ethylene group) separates them by two atoms.

[0085] X Ｂ１ and X Ｂ３ Is L Ｂ１ are separated by 1 to 10 atoms, Ｂ２ and X Ｂ３ Is L Ｂ２ are separated by 1 to 10 atoms, Ｃ１ and X Ｃ４ Is L Ｃ１ are separated by 1 to 10 atoms,Ｃ２ and X Ｃ４ Is L Ｃ２ are separated by 1 to 10 atoms, Ｃ３ and X Ｃ４ Is L Ｃ３ The meaning of being separated by 1 to 10 atoms is the same as above.

[0086] Specific examples of the polydentate ligand include 3-mercaptopropionic acid, thioglycolic acid, 2-aminoethanol, 2-aminoethanethiol, 2-mercaptoethanol, glycolic acid, ethylene glycol, ethylenediamine, aminosulfonic acid, glycine, aminomethylphosphate, 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-pentanol, 3-mercapto-1-propanol, 2,3-dimercapto-1-propanol, diethanolamine, 2-(2 2-[(2-aminoethyl)amino]ethanethiol, bis(2-mercaptoethyl)amine, 2-aminoethane-1-thiol, 1-amino-2-butanol, 1-amino-2-pentanol, L-cysteine, D-cysteine, 3-amino-1-propanol, L-homoserine, D-homoserine, aminohydroxyacetic acid, L-lactic acid, D-lactic acid, L-malic acid, D-malic acid, glyceric acid, 2-hydroxybutyric acid, L-tartaric acid, D-tartaric acid, tartronic acid, 1,2-benzenedithiol, 1,3-benzenedithiol, 1,4-benzenedithiol, 2-mercaptobenzoic acid, 3-mercaptobenzoic acid, 4-mercaptobenzoic acid, and derivatives thereof.

[0087] The inorganic ligand is preferably an inorganic ligand containing a halogen element. Inorganic ligands containing a halogen element are easily coordinated to semiconductor quantum dots and can suppress the occurrence of surface defects. The inorganic ligand is also preferably an inorganic ligand containing an In element. Inorganic ligands containing an In element are thought to be easily coordinated to the Sb site of semiconductor quantum dots and can further suppress the occurrence of surface defects. For the reasons that a semiconductor film having lower dark current, higher external quantum efficiency, and superior in-plane uniformity of external quantum efficiency can be obtained, the semiconductor film preferably contains inorganic ligands each containing a halogen element and an In element.

[0088] Examples of the halogen element contained in the inorganic ligand include a fluorine element, a chlorine element, a bromine element, and an iodine element, and a bromine element is preferred.

[0089] Specific examples of inorganic ligands 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 ammonium sulfide, with indium bromide being preferred.

[0090] In the case of inorganic ligands containing halogen elements, halogen ions may dissociate from the inorganic ligands and be coordinated to the surface of the semiconductor quantum dots. Furthermore, a portion of the inorganic ligand other than the halogen atom may also be coordinated to the surface of the semiconductor quantum dots. To give a specific example, in the case of indium bromide, indium bromide may be coordinated to the surface of the semiconductor quantum dots, or bromine ions or indium ions may be coordinated to the surface of the semiconductor quantum dots.

[0091] The total content of the semiconductor quantum dots and the ligands in the semiconductor film is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0092] The thickness of the semiconductor film is not particularly limited, but is preferably 10 to 1000 nm from the viewpoint of obtaining high electrical conductivity. The lower limit of the thickness is preferably 20 nm or more, and 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.

[0093] The semiconductor film of the present invention can be used in a photodetector or an image sensor. More specifically, the semiconductor film can be used as a photoelectric conversion layer of a photodetector or an image sensor. Therefore, the semiconductor film of the present invention is preferably used for the photoelectric conversion layer of a photodetector or an image sensor.

[0094] Since the semiconductor film of the present invention has excellent sensitivity to light having wavelengths in the infrared region, an image sensor using the semiconductor film of the present invention as a photoelectric conversion layer can be particularly preferably used as an infrared sensor. Therefore, the semiconductor film of the present invention is preferably used as a photoelectric conversion layer for an infrared sensor.

[0095] <Method for Producing Semiconductor Film> The semiconductor film of the present invention can be produced by applying the above-described dispersion of the present invention onto a substrate.

[0096] There are no particular limitations on the shape, structure, size, etc. of the substrate to which the dispersion is applied, and these can be appropriately selected depending on the purpose. The substrate structure may be a single-layer structure or a multilayer structure. For example, the substrate may be made of an inorganic material such as silicon, glass, or YSZ (Yttrium-Stabilized Zirconia), a resin, a resin composite material, or the like. Furthermore, electrodes, insulating films, etc. may be formed on the substrate. In this case, the dispersion is also applied to the electrodes and insulating films on the substrate.

[0097] The method for applying the dispersion onto the substrate is not particularly limited, and examples thereof include spin coating, dipping, inkjet printing, dispenser printing, screen printing, letterpress printing, intaglio printing, and spray coating.

[0098] After forming a film of an aggregate of semiconductor quantum dots by applying the dispersion liquid, a step of applying a ligand solution to the film may be performed. By performing this step, the ligands coordinated to the semiconductor quantum dots can be replaced with ligands contained in the ligand solution, or the ligands contained in the ligand solution can be coordinated to the semiconductor quantum dots, thereby suppressing the occurrence of surface defects of the semiconductor quantum dots. The step of applying the dispersion liquid and the step of applying the ligand solution may be alternately repeated multiple times.

[0099] Examples of the ligand contained in the ligand solution include the ligands described in the section on the semiconductor film above. The ligand contained in the ligand solution may be the same as or different from the ligand contained in the dispersion. The ligand solution may contain only one type of ligand, or may contain two or more types. Furthermore, two or more types of ligand solutions may be used in the step of applying the ligand solution.

[0100] The solvent contained in the ligand solution is preferably selected appropriately depending on the type of ligand contained in each ligand solution, and is preferably a solvent that easily dissolves each ligand. Furthermore, the solvent contained in the ligand solution is preferably an organic solvent with a high dielectric constant. Specific examples include ethanol, acetone, methanol, acetonitrile, dimethylformamide, dimethyl sulfoxide, butanol, propanol, etc. Furthermore, the solvent contained in the ligand solution is preferably a solvent that is unlikely to remain in the semiconductor film to be formed. From the viewpoint of ease of drying and ease of removal by washing, low-boiling alcohols, ketones, and nitriles are preferred, and methanol, ethanol, acetone, or acetonitrile are more preferred. The solvent contained in the ligand solution is preferably one that is immiscible with the solvent contained in the quantum dot dispersion. As a preferred solvent combination, when the solvent contained in the quantum dot dispersion is an alkane such as hexane or octane, or toluene, the solvent contained in the ligand solution is preferably a polar solvent such as methanol or acetone.

[0101] After the step of applying the ligand solution, a step of rinsing the film by contacting it with a rinse liquid (rinsing step) may be performed. By performing the rinsing step, excess ligands contained in the semiconductor film and ligands detached from the semiconductor quantum dots can be removed. The rinsing step may also be performed multiple times using two or more rinse liquids with different polarities (dielectric constants). For example, it is preferable to first rinse using a rinse liquid with a high dielectric constant (also referred to as a first rinse liquid), and then rinse using a rinse liquid with a lower dielectric constant than the first rinse liquid (also referred to as a second rinse liquid). The dielectric constant of the first rinse liquid is preferably 15 to 50, more preferably 20 to 45, and even more preferably 25 to 40. The dielectric constant of the second rinse liquid is preferably 1 to 15, more preferably 1 to 10, and even more preferably 1 to 5.

[0102] The method for producing a semiconductor film may include a drying step. By performing the drying step, residual solvent in the semiconductor film can be removed. The drying time is preferably 1 to 100 hours, more preferably 1 to 50 hours, and even more preferably 5 to 30 hours. The drying temperature is preferably 10 to 100°C, more preferably 20 to 90°C, and even more preferably 20 to 60°C. The drying step may be performed in an oxygen-containing atmosphere or a nitrogen atmosphere. The amount of residual solvent in the semiconductor film is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less, based on the total amount of the semiconductor film. The lower limit can be, for example, 0.0001% by mass. The semiconductor film may contain water, which is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less, based on the total amount of the semiconductor film. The lower limit can be, for example, 0.0001% by mass. During the semiconductor film production process, the semiconductor quantum dots and ligands may be oxidized.

[0103] <Photodetector> The photodetector of the present invention includes the semiconductor film of the present invention described above. Preferably, the photodetector includes the semiconductor film of the present invention as a photoelectric conversion layer.

[0104] The types of photodetector elements include photoconductor-type photodetectors and photodiode-type photodetectors, of which photodiode-type photodetectors are preferred because they tend to provide a high signal-to-noise ratio (SN ratio).

[0105] Since the semiconductor film of the present invention has excellent sensitivity to light having a wavelength in the infrared region, a photodetector using this semiconductor film as a photoelectric conversion layer is preferably used as a photodetector for detecting light having a wavelength in the infrared region, i.e., the photodetector is preferably used as an infrared light detecting element.

[0106] The infrared wavelength light is preferably light having a wavelength of more than 700 nm, more preferably light having a wavelength of 800 nm or more, and even more preferably light having a wavelength of 900 nm or more. The infrared wavelength light is preferably light having a wavelength of 3000 nm or less, more preferably light having a wavelength of 2000 nm or less, and even more preferably light having a wavelength of 1600 nm or less.

[0107] The photodetector may be a photodetector that simultaneously detects 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).

[0108] FIG. 1 shows one embodiment of a photodetector element. FIG. 1 is a diagram illustrating one embodiment of a photodiode-type photodetector element. Note that arrows in the figure indicate incident light on the photodetector element. The photodetector element 1 shown in FIG. 1 includes a second electrode 12, a first electrode 11 provided opposite the second electrode 12, a photoelectric conversion layer 13 provided between the second electrode 12 and the first electrode 11, an electron transport layer 21 provided between the first electrode 11 and the photoelectric conversion layer 13, and a hole transport layer 22 provided between the second electrode 12 and the photoelectric conversion layer 13. The photodetector element 1 shown in FIG. 1 is used so that light is incident from above the first electrode 11. Note that, although not shown, a transparent substrate may be disposed on the light-incident surface of the first electrode 11. Examples of transparent substrates include glass substrates, resin substrates, and ceramic substrates.

[0109] (First Electrode) The first electrode 11 is preferably a transparent electrode formed of a conductive material that is substantially transparent to the wavelength of light to be detected by the photodetector. In this specification, "substantially transparent" means that the light transmittance is 50% or more, preferably 60% or more, and more preferably 80% or more. Examples of materials for the first electrode 11 include conductive metal oxides. Specific examples include tin oxide, zinc oxide, indium oxide, indium tungsten oxide, indium zinc oxide (IZO), indium tin oxide (ITO), and fluorine-doped tin oxide (FTO).

[0110] The film thickness of the first electrode 11 is not particularly limited, but is preferably 0.01 to 100 μm, more preferably 0.01 to 10 μm, and even more preferably 0.01 to 1 μm. The film thickness of each layer can be measured by observing a cross section of the photodetector element 1 using a scanning electron microscope (SEM) or the like.

[0111] (Electron Transport Layer) The electron transport layer 21 is a layer having a function of transporting electrons generated in the photoelectric conversion layer 13 to the electrode. The electron transport layer is also called a hole blocking layer. The electron transport layer is formed of an electron transport material that can exhibit this function.

[0112] Examples of electron transport materials include fullerene compounds such as [6,6]-phenyl-C61-butylic acid methyl ester (PC61BM), perylene compounds such as perylene tetracarboxydiimide, tetracyanoquinodimethane, titanium oxide, 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 in the form of particles. The electron transport material is preferably zinc oxide. Furthermore, from the viewpoints of reducing residual organic components and increasing the contact area with the photoelectric conversion layer, the zinc oxide is preferably in the form of particles (zinc oxide particles).

[0113] The zinc oxide may be zinc oxide doped with metal atoms other than Zn. Hereinafter, zinc oxide doped with metal atoms other than Zn will also be referred to as doped zinc oxide.

[0114] The metal atoms other than Zn in the doped zinc oxide are preferably monovalent to trivalent metal atoms, more preferably at least one selected from Li, Mg, Al, and Ga, further preferably Li, Mg, Al, or Ga, and particularly preferably Li or Mg.

[0115] In the doped zinc oxide, 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 even more preferably 4 atomic % or more. 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 ratio of metal atoms other than Zn in the doped zinc oxide can be measured by a high-frequency inductively coupled plasma (ICP) method.

[0116] The average particle size of the zinc oxide particles is preferably 2 to 30 nm. The upper limit of the average particle size of the zinc oxide particles is preferably 20 nm or less, and more preferably 15 nm or less. When the average particle size of the zinc oxide particles is within the above range, a film having a large contact area with the photoelectric conversion layer and high flatness is likely to be obtained. In this specification, the average particle size of the zinc oxide particles is the average value of the particle sizes of 10 arbitrarily selected particles. The particle size of the zinc oxide particles can be measured using a transmission electron microscope.

[0117] 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 to 1000 nm. The upper limit is preferably 800 nm or less. The lower limit is preferably 20 nm or more, and more preferably 50 nm or more. The thickness of the electron transport layer is preferably 0.05 to 10 times, more preferably 0.1 to 5 times, and even more preferably 0.2 to 2 times the thickness of the photoelectric conversion layer 13.

[0118] The electron transport layer may be subjected to ultraviolet ozone treatment. In particular, when the electron transport layer is a layer made of nanoparticles, ultraviolet ozone treatment is desirable. By performing ultraviolet ozone treatment, the wettability of the quantum dot dispersion liquid to the electron transport layer can be improved, and residual organic matter in the electron transport layer can be decomposed or removed, resulting in high device performance. The wavelength of the ultraviolet light to be irradiated can be selected between 100 and 400 nm. In particular, because the above-mentioned effects can be easily obtained and excessive damage to the film can be avoided, it is preferable for the peak intensity to be between 200 and 300 nm, and more preferably between 240 and 270 nm. There are no particular restrictions on the ultraviolet light irradiation intensity, but because the above-mentioned effects can be easily obtained and excessive damage to the film can be avoided, it is preferable for the peak intensity to be between 1 and 100 mW / cm. ２ is preferably 10 to 50 mW / cm ２ 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.

[0119] (Photoelectric Conversion Layer) The photoelectric conversion layer 13 is composed of the semiconductor film of the present invention described above. The thickness of the photoelectric conversion layer 13 is preferably 10 to 1000 nm. The lower limit of the thickness is preferably 20 nm or more, and 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 13 for light of the target wavelength to be detected by the photodetector element can be 1.5 to 5.0.

[0120] (Hole Transport Layer) The hole transport layer 22 is a layer having a function of transporting holes generated in the photoelectric conversion layer 13 to the electrode. The hole transport layer is also called an electron blocking layer.

[0121] The hole transport layer 22 is formed of a hole transport material that can perform this function. Examples of hole transport materials include PEDOT:PSS (a composite of poly(3,4-ethylenedioxythiophene) and 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) and thieno[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-1)carbonyl]thieno[3,4-b]thiophenediyl})), poly(3-hexylthiophene-2,5-diyl), poly(3-n-octyl oxythiophene), poly(9,9'-dioctyl-fluorene-co-bithiophene), poly(3,3'''-didodecyl-quaterthiophene), poly(3,6-dioctylthieno[3,2-b]thiophene), poly(2,5-bis(3-decylthiophen-2-yl)thieno[3,2-b]thiophene), poly(3,4-didecylthiophene-co-thieno[3,2-b]thiophene), poly(3,6-dioctylthieno[3,2-b]thiophene-co-thieno[3,2-b]thiophene), poly(3,6-dioctylthieno[3,2-b]thiophene-co-thiophene), poly(3,6-dioctylthieno[3,2-b]thiophene-co-bithiophene), PC71BM ([6,6]-phenyl-C71-methyl butyrate). Alternatively, organic hole transport materials such as those described in paragraphs 0209 to 0212 of JP-A-2001-291534 can be used. Quantum dots can also be used as the hole transport material. Examples of quantum dot materials that constitute quantum dots include nanoparticles (particles with a size of 0.5 nm or more and less than 100 nm) of common semiconductor crystals (a) Group IV semiconductors, b) Group IV-IV, III-V, or II-VI compound semiconductors, and c) compound semiconductors formed from a combination of three or more of Group II, III, IV, V, and VI elements).Specifically, PbS, PbSe, PbSeS, InN, Ge, InAs, InGaAs, CuInS, CuInSe, CuInGaSe, InSb, HgTe, HgCdTe, and Ag. ２ S, Ag ２ Se, Ag ２ Examples of such semiconductor materials include Te, SnS, SnSe, SnTe, Si, InP, etc. Ligands may be coordinated to the surface of the quantum dots.

[0122] 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, and more preferably 30 nm or less.

[0123] (Second Electrode) The second electrode 12 is preferably composed of a metal material containing at least one metal atom selected from Ag, Au, Pt, Ir, Pd, Cu, Pb, Sn, Zn, Ti, W, Mo, Ta, Ge, Ni, Al, Cr, and In. By using such a metal material for the second electrode 12, a photodetector element with high external quantum efficiency and reduced dark current can be obtained. The second electrode 12 can also be made of the above-mentioned conductive metal oxides, carbon materials, conductive polymers, and the like. The carbon material may be any conductive material, such as fullerene, carbon nanotube, graphite, or graphene.

[0124] The work function of the second electrode 12 is preferably 4.6 eV or more, more preferably 4.8 to 5.7 eV, and even more preferably 4.9 to 5.3 eV, for the reasons that this enhances the electron blocking property of the hole transport layer and makes it easy to collect holes generated in the device.

[0125] The film thickness of the second electrode 12 is not particularly limited, but is preferably 0.01 to 100 μm, more preferably 0.01 to 10 μm, and even more preferably 0.01 to 1 μm.

[0126] (Charge Extraction Layer) Although not shown, the photodetector of the present invention may have a charge extraction layer between the second electrode 12 and the hole transport layer 22. By having the charge extraction layer, high external quantum efficiency can be obtained at a low applied voltage.

[0127] Materials for forming the charge extraction layer include metal oxides and organic semiconductors, with metal oxides being preferred. Metal oxides include molybdenum oxide, titanium oxide, vanadium oxide, chromium oxide, cobalt oxide, nickel oxide, copper oxide, zirconium oxide, molybdenum oxide, silver oxide, tantalum oxide, and tungsten oxide, with molybdenum oxide being preferred. Organic semiconductors include polythiophene compounds, with the materials mentioned above being specific examples of polythiophene compounds. The charge extraction layer may be a single-layer film or a laminated film of two or more layers.

[0128] The thickness of the charge extraction layer is preferably 1 to 100 nm, with the lower limit being preferably 5 nm or more and the upper limit being preferably 50 nm or less.

[0129] (Blocking Layer) Although not shown, the photodetector element may have a blocking layer between the first electrode 11 and the electron transport layer 21. The blocking layer has the function of preventing reverse current. The blocking layer is also called a short-circuit prevention layer. Examples of materials that form the blocking layer include 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 film thickness of the blocking layer is preferably 5 to 100 nm. The lower limit is preferably 10 nm or more. The upper limit is preferably 50 nm or less, and more preferably 30 nm or less.

[0130] In the photodetector element, the wavelength λ of the light to be detected by the photodetector element and the optical path length L of the light of the wavelength λ from the surface of the second electrode 12 on the photoelectric conversion layer 13 side to the surface of the photoelectric conversion layer 13 on the first electrode 11 side are λ and preferably satisfy the relationship of the following formula (1-1), and more preferably satisfy the relationship of the following formula (1-2): λWhen these relationships are satisfied, the phases of the light incident from the first electrode 11 side (incident light) and the light reflected from the surface of the second electrode 12 (reflected light) can be aligned in the photoelectric conversion layer 13, and as a result, the light is reinforced by the optical interference effect, thereby achieving a higher external quantum efficiency.

[0131] 0.05+m / 2≦L λ / λ≦0.35+m / 2 ... (1-1) 0.10+m / 2≦L λ / λ≦0.30+m / 2 ... (1-2)

[0132] In the above formula, λ is the wavelength of the light to be detected by the light detection element, and L λ is the optical path length of light of wavelength λ from the surface of the second electrode 12 on the photoelectric conversion layer 13 side to the surface of the photoelectric conversion layer 13 on the first electrode 11 side, and m is an integer of 0 or more.

[0133] 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 embodiment, the transport properties of charges such as holes and electrons are good, and the external quantum efficiency of the photodetector can be further increased.

[0134] Here, the optical path length means the product of the physical thickness of the material through which light passes and the refractive index. Taking the photoelectric conversion layer 13 as an example, the thickness of the photoelectric conversion layer is d １ , the wavelength λ of the photoelectric conversion layer １ The refractive index of the light is N １ When the wavelength λ transmitted through the photoelectric conversion layer 13 is １ The optical path length of the light is N １ ×d １ When the photoelectric conversion layer 13 or the hole transport layer 22 is composed of a laminated film of two or more layers, or when an intermediate layer is present between the hole transport layer 22 and the second electrode 12, the integrated value of the optical path lengths of the respective layers is the above-mentioned optical path length L λ is.

[0135] <Image Sensor> The image sensor of the present invention includes the photodetector element of the present invention described above. Since the photodetector element of the present invention has excellent sensitivity to light with wavelengths in the infrared region, this image sensor can be particularly preferably used as an infrared sensor. Furthermore, the image sensor can be preferably used to sense light with a wavelength of 900 to 3000 nm, more preferably used to sense light with a wavelength of 900 to 2000 nm, and even more preferably used to sense light with a wavelength of 900 to 1600 nm.

[0136] The configuration of the image sensor is not particularly limited as long as it has a photodetector element and functions as an image sensor. Examples of the photodetector element include those described above.

[0137] The image sensor may include an infrared-transmitting filter layer, which preferably has low transmittance for light in the visible wavelength range, and more preferably has an average transmittance of 10% or less, even more preferably 7.5% or less, and particularly preferably 5% or less for light in the wavelength range of 400 to 650 nm.

[0138] The infrared transmission filter layer may be formed of a resin film containing a colorant. Examples of the colorant include chromatic colorants such as red, green, blue, yellow, purple, and orange, as well as black colorants. The colorant contained in the infrared transmission filter layer preferably comprises a combination of two or more chromatic colorants to form a black color, or a black colorant. Examples of combinations of chromatic colorants when a black color is formed by combining two or more chromatic colorants include the following (C1) to (C7): (C1) A configuration containing a red colorant and a blue colorant; (C2) A configuration containing a red colorant, a blue colorant, and a yellow colorant; (C3) A configuration containing a red colorant, a blue colorant, a yellow colorant, and a purple colorant; (C4) A configuration containing a red colorant, a blue colorant, a yellow colorant, a purple colorant, and a green colorant; and (C5) A configuration containing a red colorant, a blue colorant, a yellow colorant, and a green colorant. (C6) An embodiment containing a red color material, a blue color material, and a green color material. (C7) An embodiment containing a yellow color material and a purple color material.

[0139] The chromatic colorant may be a pigment or a dye. It may contain both a pigment and a dye. The black colorant is preferably an organic black colorant. Examples of organic black colorants include bisbenzofuranone compounds, azomethine compounds, perylene compounds, and azo compounds.

[0140] The infrared transmission filter layer may further contain an infrared absorber. By incorporating an infrared absorber into the infrared transmission filter layer, the wavelength of light to be transmitted can be shifted to a longer wavelength side. Examples of the infrared absorber 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, azomethine compounds, anthraquinone compounds, dibenzofuranone compounds, dithiolene metal complexes, metal oxides, and metal borides.

[0141] The spectral characteristics of the infrared transmission filter layer can be appropriately selected depending on the application of the image sensor. Examples include filter layers satisfying any one of the following spectral characteristics (1) to (5): (1): A filter layer in which the maximum light transmittance in the thickness direction of the film in the wavelength range of 400 to 750 nm is 20% or less (preferably 15% or less, more preferably 10% or less), and the minimum light transmittance in the thickness direction of the film in the wavelength range of 900 to 1500 nm is 70% or more (preferably 75% or more, more preferably 80% or more). (2): A filter layer in which the maximum 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 minimum light transmittance in the thickness direction of the film in the wavelength range of 1000 to 1500 nm is 70% or more (preferably 75% or more, more preferably 80% or more). (3): A filter layer in which the maximum 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 minimum light transmittance in the thickness direction of the film in the wavelength range of 1100 to 1500 nm is 70% or more (preferably 75% or more, more preferably 80% or more). (4): A filter layer in which the maximum 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 minimum light transmittance in the wavelength range of 1400 to 1500 nm is 70% or more (preferably 75% or more, more preferably 80% or more). (5) A filter layer having a maximum light transmittance in the thickness direction of the film in the wavelength range of 400 to 1300 nm of 20% or less (preferably 15% or less, more preferably 10% or less), and a minimum light transmittance in the wavelength range of 1600 to 2000 nm of 70% or more (preferably 75% or more, more preferably 80% or more).Further, as the infrared transmission filter, films described in JP 2013-077009 A, JP 2014-130173 A, JP 2014-130338 A, WO 2015 / 166779 A, ​​WO 2016 / 178346 A, WO 2016 / 190162 A, WO 2018 / 016232 A, JP 2016-177079 A, ​​JP 2014-130332 A, and WO 2016 / 027798 can be used. The infrared transmission filter may be a combination of two or more filters, or a dual bandpass filter that transmits two or more specific wavelength regions with one filter may be used.

[0142] The image sensor may include an infrared shielding filter for the purpose of improving various performances such as noise reduction, etc. Specific examples of the infrared shielding filter include the filters described in International Publication No. 2016 / 186050, International Publication No. 2016 / 035695, Japanese Patent No. 6248945, International Publication No. 2019 / 021767, Japanese Patent Laid-Open No. 2017-067963, and Japanese Patent No. 6506529.

[0143] The image sensor may include a dielectric multilayer film. Examples of the dielectric multilayer film include a multilayer film in which a high refractive index dielectric thin film (high refractive index material layer) and a low refractive index dielectric thin film (low refractive index material layer) are alternately stacked. The number of dielectric thin films stacked 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 with a refractive index of 1.7 to 2.5 is preferred as a material used to form the high refractive index material layer. Specific examples include Sb ２ O ３ , Sb ２ S ３ , Bi ２ O ３ , CeO ２ , CeF ３ , HfO ２ , La ２ O ３ , Nd ２ O ３ , Pr ６ O １１ , Sc ２ O３ , SiO, Ta ２ O ５ , TiO ２ , TlCl, Y ２ O ３ , ZnSe, ZnS, ZrO ２ The material used to form the low refractive index material layer is preferably a material having a refractive index of 1.2 to 1.6. ２ O ３ , BiF ３ , CaF ２ , LaF ３ , PbCl ２ , PbF ２ , LiF, MgF ２ , MgO, NdF ３ , SiO ２ , Si ２ O ３ , NaF, ThO ２ , ThF ４ , Na ３ AlF ６ and the like. The method for forming the dielectric multilayer film is not particularly limited, and examples thereof 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 methods). The thickness of each of the high refractive index material layer and the low refractive index material layer is preferably 0.1λ to 0.5λ, where λ (nm) is the wavelength of the light to be blocked. Specific examples of the dielectric multilayer film that can be used include the films described in JP 2014-130344 A and JP 2018-010296 A.

[0144] 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, and even 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, and even more preferably 90% or more. The maximum transmittance in the light-shielding wavelength band is preferably 20% or less, more preferably 10% or less, 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 determined by dividing the wavelength showing the maximum transmittance by the center wavelength λ ｔ１ In this case, the central wavelength λ ｔ１ ±100 nm, and the central wavelength λ ｔ１ More preferably, the central wavelength λ ｔ１ It is more preferably ±50 nm.

[0145] 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.

[0146] The image sensor may include a color separation filter layer. Examples of the color separation filter layer include a filter layer containing colored pixels. Examples of the colored pixels include red, green, blue, yellow, cyan, and magenta pixels. The color separation filter layer may include colored pixels of two or more colors, or may include only one color. The filter layer may be appropriately selected depending on the application and purpose. For example, the filter described in International Publication No. 2019 / 039172 may be used.

[0147] Furthermore, when the color separation layer includes color pixels of two or more colors, the color pixels of each color may be adjacent to each other, and a partition wall may be provided between each color pixel. The material of the partition wall is not particularly limited. Examples include organic materials such as siloxane resin and fluororesin, and inorganic particles such as silica particles. The partition wall may also be made of a metal such as tungsten or aluminum.

[0148] When the image sensor includes an infrared transmission filter layer and a color separation layer, it is preferable that the color separation layer is provided on a different optical path from the infrared transmission filter layer. It is also preferable that the infrared transmission filter layer and the color separation layer are arranged two-dimensionally. The two-dimensional arrangement of the infrared transmission filter layer and the color separation layer means that at least a portion of each layer exists on the same plane.

[0149] The image sensor may include an intermediate layer such as a planarization layer, a base layer, or an adhesion layer, an anti-reflection film, and a lens. The anti-reflection film may be, for example, a film made from a composition described in International Publication No. 2019 / 017280. The lens may be, for example, a structure described in International Publication No. 2018 / 092600.

[0150] The present invention will be explained in more detail below with reference to examples. The materials, amounts used, ratios, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

[0151] <Production of Semiconductor Quantum Dots and Quantum Dot Dispersion> (Example 1) (Quantum Dot Dispersion 1) In a glove box, 10 mmol of indium chloride was added to 100 mL of oleylamine, and the mixture was heated and stirred at 60° C. to dissolve the indium chloride. 5 mmol of antimony chloride was then added, and the mixture was heated and stirred at 60° C. to dissolve the antimony chloride, thereby preparing precursor solution A1. In a glove box, 100 mL of a tetrahydrofuran (THF) solution of lithium triethylborohydride (lithium triethylborohydride concentration: 1.0 mol / L, manufactured by Aldrich) was mixed with 50 mL of dioctyl ether, and the THF was distilled off to prepare a reducing agent solution, which was a dioctyl ether solution of lithium triethylborohydride (lithium triethylborohydride concentration: approximately 2.0 mol / L). In a glove box, 5 mmol of tris(dimethylamino)phosphine was dissolved in 50 mL of oleylamine and heated at 110 °C for 2 hours to prepare precursor solution C1. In the glove box, 30 mL of precursor solution A1 and 3 mL of oleylamine were added to a three-neck flask to obtain a mixed solution. The three-neck flask was then removed from the glove box, and after repeated evacuation and nitrogen purging, the mixture was switched to a nitrogen flow state. Here, 4.0 mL of reducing agent solution was injected into the mixed solution, and the temperature was raised to 290 °C at a rate of 3 °C / min. After the liquid temperature reached 290 °C, the mixture was maintained for 20 minutes to obtain reaction solution B1. Next, 7.5 mL of precursor solution C1 was added to reaction solution B1 while maintaining the temperature of reaction solution B1 at 290 °C, and the mixture was maintained at 290 °C for 20 minutes to obtain reaction solution D1. The resulting reaction solution D1 was cooled. The three-neck flask containing Reaction Solution D1 was placed back into the glove box, and 90 mL of toluene and 6 mL of oleic acid were added and stirred. This solution was centrifuged at approximately 7,800 rpm, and the precipitate was removed. 60 mL of acetonitrile was added to the supernatant, and the mixture was centrifuged again at 7,800 rpm. The target particles, semiconductor quantum dots (InSbP quantum dots), were then precipitated. Toluene was then added to the precipitate, and quantum dot dispersion 1 (InSbP quantum dot dispersion) was obtained.A quantum dot thin film was prepared using the obtained quantum dot dispersion 1, and the band gap estimated from the wavelength at which an inflection point of absorption was observed in absorption measurements of the quantum dot thin film was approximately 0.95 eV. The average primary particle diameter of the InSbP quantum dots contained in quantum dot dispersion 1 was 5.0 nm. The average primary particle diameter of the InSbP quantum dots was determined by measuring the circle-equivalent diameters of 500 randomly selected particles from electron micrographs taken with a transmission electron microscope (TEM) and calculating the average (arithmetic mean) of the diameters.

[0152] (Example 2) (Quantum dot dispersion 2) Quantum dot dispersion 2 (a dispersion of InSbP quantum dots) was obtained in the same manner as in Production Example 1, except that the amount of precursor solution C1 added in Example 1 was changed to 3.75 mL. A quantum dot thin film was produced using the obtained quantum dot dispersion 2, and the band gap estimated from the wavelength at which an inflection point of absorption was observed in absorption measurements of the quantum dot thin film was approximately 0.95 eV. The average primary particle diameter of the InSbP quantum dots contained in quantum dot dispersion 2 was 5.0 nm.

[0153] (Example 3) (Quantum dot dispersion 3) Quantum dot dispersion 3 (a dispersion of InSbP quantum dots) was obtained in the same manner as in Production Example 1, except that the amount of precursor solution C1 added in Example 1 was changed to 15 mL. A quantum dot thin film was produced using the obtained quantum dot dispersion 3, and the band gap estimated from the wavelength at which an inflection point of absorption was observed in absorption measurements of the quantum dot thin film was approximately 0.95 eV. The average primary particle diameter of the InSbP quantum dots contained in quantum dot dispersion 3 was 5.0 nm.

[0154] The quantum dot dispersions of Examples 1 to 3 (Quantum Dot Dispersions 1 to 3) were stored at 23°C in a nitrogen environment for 3 months, and the dispersibility of the semiconductor quantum dots was good for all dispersions, but the quantum dot dispersions of Examples 1 and 2 (Quantum Dot Dispersions 1 and 2) had better dispersibility of the semiconductor quantum dots than the quantum dot dispersion of Example 3 (Quantum Dot Dispersion 3). There was slight sedimentation in the quantum dot dispersions of Example 3 (Quantum Dot Dispersion 3), but almost no sedimentation was observed in the quantum dot dispersions of Examples 1 and 2 (Quantum Dot Dispersions 1 and 2).

[0155] (Comparative Example 1) (Quantum Dot Dispersion r1) In a glove box, 10 mmol of indium chloride was added to 100 mL of oleylamine and stirred to dissolve the indium chloride, preparing precursor solution a1. In a glove box, 5 mmol of antimony chloride was added to 100 mL of oleylamine and stirred to dissolve the antimony chloride, preparing precursor solution a2. In a glove box, 100 mL of a tetrahydrofuran (THF) solution of lithium triethylborohydride (lithium triethylborohydride concentration 1.0 mol / L, manufactured by Aldrich) was mixed with 50 mL of dioctyl ether, and the THF was distilled off to prepare a reducing agent solution, which was a dioctyl ether solution of lithium triethylborohydride (lithium triethylborohydride concentration approximately 2.0 mol / L). In a glove box, 15 mL of precursor solution a1 and 15 mL of precursor solution a2 were added to a three-neck flask to obtain a mixed solution. The three-neck flask was then removed from the glove box, and after repeated evacuation and nitrogen purging, the mixture was placed under a nitrogen flow. 4.0 mL of reducing agent solution was then poured into the mixed solution, followed by heating to 290°C at a rate of 3°C / min. After the liquid temperature reached 290°C, the mixture was held for 20 minutes to cool. The three-neck flask was then returned to the glove box, and 90 mL of toluene and 6 mL of oleic acid were added and stirred. This solution was centrifuged at approximately 7,800 rpm, after which the precipitate was removed. 60 mL of acetonitrile was added to the supernatant, and the mixture was centrifuged again at 7,800 rpm. The target particles, semiconductor quantum dots (InSb quantum dots), were then precipitated. Toluene was then added to the precipitate to obtain quantum dot dispersion r1 (InSb quantum dot dispersion). A quantum dot thin film was prepared using the obtained quantum dot dispersion r1, and the band gap estimated from the wavelength at which the absorption inflection point was observed in the absorption measurement of the quantum dot thin film was approximately 0.95 eV. The average primary particle size of the InSbP quantum dots contained in the quantum dot dispersion r1 was 5.0 nm. The average primary particle size of the InSb quantum dots was measured in the same manner as for the InSbP quantum dots.

[0156] <Method for Measuring the Elemental Composition Ratio of Semiconductor Quantum Dots> Using quantum dot dispersions 1 to 3 and r1, a film approximately 0.1 μm thick was formed on a gold-coated silicon substrate, and the elemental composition ratio of the semiconductor quantum dots was measured under the following conditions by X-ray photoelectron spectroscopy using an XPS (X-ray Photoelectron Spectroscopy) device. In the table below, the P / Sb column indicates the value of the "ratio of the molar amount of P to the molar amount of Sb," and the In / (Sb+P) column indicates the value of the "ratio of the molar amount of In to the sum of the molar amount of Sb and the molar amount of P." The elemental composition ratio was measured at three points on the same film, and the average value was calculated as the elemental composition ratio of the semiconductor quantum dots. The measurement conditions were as follows: X-ray source: Monochromated Al-K line (100 mmf, 25 W, 15 kV) Measurement area: 300 mm x 300 mm (area measurement) Pass energy: 46.95 eV Charge correction: Yes (electron gun and low-energy ion gun used together) Photoelectron take-off angle: 45°

[0157]

[0158] <Fabrication of Photodetector> (Example 11) A 200 nm zinc oxide film was formed by sputtering on a quartz glass substrate with a fluorine-doped tin oxide film to form an electron transport layer. Next, quantum dot dispersion liquid 1 was dropped onto the zinc oxide film and spin-coated at 2500 rpm to form a quantum dot assembly film (Step 1). Next, a mercaptopropionic acid solution (concentration: 0.01 v / v%, solvent: methanol) was dropped onto the quantum dot assembly film as a ligand exchange solution, and the film was left to stand for 20 seconds and then spin-dried at 2500 rpm for 10 seconds (Step 2). Next, acetonitrile was dropped onto the quantum dot assembly film as a rinse solution, and the film was spin-dried at 2500 rpm for 20 seconds to exchange the ligands coordinated to the quantum dots with mercaptopropionic acid (Step 3). The operation of steps 1 to 3 as one cycle was repeated two times to form a quantum dot assembly film (semiconductor film) with a thickness of 100 nm, in which the ligands had been exchanged with mercaptopropionic acid, to form a photoelectric conversion layer. Next, a toluene solution (concentration: 10 mg / ml) of poly(3-hexylthiophene-2,5-diyl) (P3HT) was spin-coated on the photoelectric conversion layer at 2000 rpm to form a hole transport layer. Next, a 10-nm-thick MoO ３ After the film was formed, a 100 nm thick Au film (second electrode) was formed to form three element portions, thereby manufacturing a photodiode type light detecting element.

[0159] (Example 12) As a ligand exchange solution, indium iodide (InI ３ A photodiode-type light-detecting element was manufactured in the same manner as in Example 11, except that a solution containing indium iodide added to a concentration of 7 mmol / L was used.

[0160] Examples 13 and 14, Comparative Example 11 Photodiode-type light-detecting elements were manufactured in the same manner as in Example 11, except that quantum dot dispersion liquids shown in the table below were used instead of quantum dot dispersion liquid 1.

[0161] <Performance Evaluation> The dark current and external quantum efficiency (EQE) of each photodetector element were evaluated using a semiconductor parameter analyzer (C4156, Agilent). First, the current-voltage characteristics (IV characteristics) were measured while sweeping the voltage from 0 V to -2 V in the absence of light irradiation, and the dark current was evaluated. Here, the current value at -2 V was taken as the dark current value. Next, the dark current was evaluated by irradiating the photodetector element with 1250 nm monochrome light (irradiation dose 50 μW / cm ２ ) was irradiated, the I-V characteristics were measured while sweeping the voltage from 0 V to -2 V. The photocurrent value was determined by subtracting the dark current value from the current value when -2 V was applied, and the external quantum efficiency (EQE) was calculated from this value. Note that the values ​​listed in the external quantum efficiency (EQE) and dark current columns in the table below are values ​​for the central element among the three element parts. Furthermore, for the in-plane uniformity of the external quantum efficiency (EQE), the external quantum efficiency of each of the three element parts was measured, and the difference between the highest and lowest external quantum efficiency values ​​was divided by the external quantum efficiency of the element with the median performance to calculate ΔEQE, and the in-plane uniformity of the external quantum efficiency was evaluated based on ΔEQE. A smaller ΔEQE value indicates better in-plane uniformity. ΔEQE (%) = (highest external quantum efficiency value - lowest external quantum efficiency value) / median external quantum efficiency x 100

[0162]

[0163] As shown in the above table, the photodetector element of the example had a lower dark current, a higher external quantum efficiency (EQE), and an excellent in-plane uniformity of the external quantum efficiency (ΔEQE) than the comparative example.

[0164] An image sensor having good visible-infrared imaging performance can be produced by using the photodetector element obtained in the above examples and an optical filter produced according to the methods described in WO 2016 / 186050 and WO 2016 / 190162 together with a known method.

[0165] 1: Photodetector element 11: First electrode 12: Second electrode 13: Photoelectric conversion layer 21: Electron transport layer 22: Hole transport layer

Claims

1. A semiconductor quantum dot containing In, Sb and P elements, wherein the ratio of the molar amount of P to the molar amount of Sb is 0.20 or more and less than 1.

00.

2. The semiconductor quantum dot according to claim 1, wherein the ratio of the molar amount of In element to the sum of the molar amounts of Sb element and P element is 1.00 or more and 1.70 or less.

3. The semiconductor quantum dot according to claim 1 or 2, wherein the band gap of the semiconductor quantum dot is 1.0 eV or less.

4. The semiconductor quantum dots according to claim 1 or 2, wherein the average primary particle size of the semiconductor quantum dots is 3 to 10 nm.

5. A dispersion comprising the semiconductor quantum dot according to claim 1 or 2, a ligand, and a solvent.

6. A semiconductor film comprising an aggregate of semiconductor quantum dots according to claim 1 or 2 and ligands that are coordinated to the semiconductor quantum dots.

7. The semiconductor film of claim 6, wherein said ligands include inorganic ligands.

8. A photodetector comprising the semiconductor film according to claim 6.

9. An image sensor comprising the photodetector element according to claim 8.

10. A method for producing semiconductor quantum dots as described in claim 1, comprising the steps of: adding a reducing agent to precursor solution A containing a compound containing an In element and a compound containing an Sb element, and reacting them in the presence of the reducing agent to obtain reaction solution B containing a reactant between the compound containing the In element and the compound containing the Sb element; and adding precursor solution C containing a compound containing a P element to reaction solution B to react the reactant with the compound containing the P element.

11. The method for producing semiconductor quantum dots according to claim 10, wherein the precursor solution C is added to the reaction solution B at 230° C. or higher.

12. The method for producing semiconductor quantum dots according to claim 10 or 11, wherein the compound containing the In element is an indium halide.

13. The method for producing semiconductor quantum dots according to claim 10 or 11, wherein the compound containing Sb element is an antimony halide.

14. The method for producing semiconductor quantum dots according to claim 10 or 11, wherein the precursor solution A contains an amine compound having 12 to 20 carbon atoms.

15. The method for producing semiconductor quantum dots described in claim 10 or 11, wherein the compound containing P element includes at least one selected from the group consisting of trisdimethylaminophosphine, trisdiethylaminophosphine, trisdipropylaminophosphine, and trisdibutylaminophosphine.

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