WO2021070858A1 - Quantum dot and method for producing same - Google Patents

Quantum dot and method for producing same Download PDF

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WO2021070858A1
WO2021070858A1 PCT/JP2020/037980 JP2020037980W WO2021070858A1 WO 2021070858 A1 WO2021070858 A1 WO 2021070858A1 JP 2020037980 W JP2020037980 W JP 2020037980W WO 2021070858 A1 WO2021070858 A1 WO 2021070858A1
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quantum dots
quantum dot
raw material
quantum
tellurium
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French (fr)
Japanese (ja)
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俊明 島崎
惣一朗 荷方
幹大 ▲高▼▲崎▼
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Ｎｓマテリアルズ株式会社
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B19/00—Selenium; Tellurium; Compounds thereof
    • C01B19/04—Binary compounds including binary selenium-tellurium compounds
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/58—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing copper, silver or gold
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/88—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing selenium, tellurium or unspecified chalcogen elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors

Definitions

  • the present invention relates to quantum dots that emit light in the near infrared region and a method for producing the same.
  • Quantum dots are nanoparticles with a particle size of several nm to several tens of nm, which are composed of hundreds to thousands of atoms. Quantum dots are also called fluorescent nanoparticles, semiconductor nanoparticles, or nanocrystals.
  • Quantum dots can have various absorption / emission wavelengths depending on the particle size and composition of nanoparticles.
  • examples of the performance of quantum dots include fluorescence quantum yield (Quantum Yield: QY) and particle size control.
  • Non-Patent Document 1 and Non-Patent Document 2 have a description regarding silver chalcogenide quantum dots.
  • Non-Patent Document 1 reports a method for synthesizing Ag 2 Te quantum dots by a cation exchange method from CdTe. Further, Non-Patent Document 2 reports a method for synthesizing Ag 2 Te quantum dots via silver silylamide.
  • Non-Patent Document 1 it is a synthetic method via a cadmium intermediate, which is a toxic regulated heavy metal, and is not practically used. Further, the silver silylamide used in Non-Patent Document 2 is a reactant having high reactivity when used in the atmosphere, and there is a problem that care must be taken in its handling.
  • the direct synthesis method does not use toxic regulated heavy metals or reactants that show high reactivity when used in the atmosphere, but it produces Ag 2 Te quantum dots.
  • the average particle size is about 2.0 to 3.0 nm, which is quite small for a quantum dot.
  • Light with a wavelength of 1400 nm or more is called "eye safe" and is expected to be used in various fields as light that is safe for the eyes. Therefore, Ag 2 Te that selectively absorbs light of this wavelength
  • the above-mentioned direct synthesis method can obtain only an absorption wavelength up to about 1200 nm, and cannot obtain light having a near-infrared wavelength longer than that.
  • the present invention has been made in view of this point, and is represented by Ag 2 E (E is at least one of Te, Se, and S) exhibiting near-infrared light absorption having a wavelength of 1300 nm or more. It is an object of the present invention to provide a quantum dot and a method for manufacturing a quantum dot that can be mass-produced and has high safety.
  • the quantum dot in the present invention is a nanocrystal represented by Ag 2 E (E is at least one of tellurium, selenium, or sulfur) containing silver and chalcogen, and has an absorption wavelength of 1300 to 1. It is characterized in that it is in the near infrared region of 1500 nm.
  • the method for producing quantum dots in the present invention is a step of obtaining a CuE (E is at least one of tellurium, selenium, or sulfur) intermediate prepared from a copper raw material and a chalcogen raw material, and the CuE intermediate is used.
  • a CuE is at least one of tellurium, selenium, or sulfur
  • it is characterized by having a step of synthesizing quantum dots represented by Ag 2 E (E is at least one of tellurium, selenium, or sulfur) through a cation exchange reaction using an Ag raw material.
  • Ag 2 E E is at least one of tellurium, selenium, or sulfur
  • the quantum dots of the present invention it is possible to obtain absorption characteristics having an absorption wavelength in the near infrared region of 1300 nm or more and 1500 nm or less.
  • the particle size can be precisely made uniform by undergoing a cation exchange reaction, and a spectrum showing absorption derived from quantum dots can be obtained in the near infrared region. ..
  • quantum dots of the present invention when the quantum dots are handled in the atmosphere, they can be synthesized by a method that can be mass-produced without using a highly reactive reactant or a toxic regulated heavy metal. It is possible.
  • FIG. 9 is an Absorption spectrum of Ag 2 Te in Example 1.
  • FIG. 3 is a scanning transmission electron microscope (STEM) photograph of Ag 2 Te in Example 1. It is a partial schematic view of FIG. 3A. It is a particle size analysis result based on the STEM photograph of Ag 2 Te in Example 1. It is an X-ray diffraction (XRD spectrum) of Ag 2 Te in Example 1.
  • FIG. 3 is a scanning transmission electron microscope (STEM) photograph of Ag 2 Te in Example 1. It is a partial schematic view of FIG. 3A. It is a particle size analysis result based on the STEM photograph of Ag 2 Te in Example 1. It is an X-ray diffraction (XRD spectrum) of Ag 2 Te in Example 1.
  • STEM scanning transmission electron microscope
  • near-infrared luminescent quantum dots that do not contain heavy metals subject to toxic regulation such as Cd and Pb have been attracting attention.
  • a toxic regulated heavy metal or a reactant showing high reactivity in use in the atmosphere is not used, but Ag 2 Te quantum is produced.
  • the average particle size of the dots was about 2.0 to 3.0 nm, which was considerably small for a quantum dot, and the absorption wavelength of the generated Ag 2 Te quantum dots was about 1100-1200 nm.
  • the present inventors have come to produce quantum dots having an absorption wavelength in the near infrared region of 1300 nm to 1500 nm, which is larger than the direct synthesis method by undergoing a cation exchange reaction.
  • quantum dots when they are handled in the atmosphere, it has become possible to synthesize them by a method that can be mass-produced without using a reactant showing high reactivity or a toxic regulated heavy metal.
  • the present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof.
  • the notation "-" includes both the lower limit value and the upper limit value.
  • FIG. 1 is a schematic diagram of quantum dots in this embodiment.
  • Quantum dot 1 shown in FIG. 1A is a nanocrystal containing silver (Ag) and chalcogen (referring to at least one of tellurium (Te), selenium (Se), and sulfur (S)). ..
  • the chemical formula of the quantum dot of this embodiment is represented by Ag 2 E (E is at least one of Te, Se, and S).
  • the quantum dots in this embodiment have a very uniform particle size, and the quantum size effect is exhibited from the size of the particles.
  • nanoclaystal refers to nanoparticles having a particle size of about several nm to several tens of nm.
  • the average particle size of the quantum dots of the present embodiment is preferably 5 nm or more and 8 nm or less. Further, in the present embodiment, it is possible to satisfy the above average particle size and generate a large number of quantum dots with a very uniform particle size.
  • Uniform refers to a state in which 95% or more of the particles are contained within ⁇ 6% of the average particle size. As described above, in the present embodiment, it is possible to mass-produce fine and very uniform high-quality quantum dots.
  • Ag and Te, Ag and Se, or Ag and S contained in the quantum dots of the present embodiment are main components, and elements other than these elements may be contained.
  • a reactant such as a metal amide or an organolithium compound, which exhibits high reactivity when handled in the atmosphere, is not used, and Cd or Pb is used as a reaction intermediate.
  • Cd or Pb is used as a reaction intermediate.
  • Cadmium-containing and lead-containing compounds are toxic and regulated heavy metals, and are likely to cause cost increases, handling restrictions, and complicated manufacturing processes.
  • the quantum dots of the present embodiment do not contain substances derived from highly reactive reactants or regulated heavy metals.
  • the quantum dots of this embodiment have an absorption wavelength in the near infrared region of 1300 m to 1500 nm.
  • the "absorption wavelength” refers to the wavelength of the peak of the absorption spectrum.
  • the absorption wavelength of the quantum dots of the present embodiment is preferably 1350 nm or more and 1500 nm or less, and more preferably 1400 nm or more and 1500 nm or less.
  • a reaction system for synthesizing quantum dots first, a copper compound is used as a precursor, and chalcogen is introduced into the precursor.
  • the resulting CUE (E is, S, Se, refers to at least any one of Te) against a silver raw material is reacted at a suitable temperature, to synthesize the Ag 2 E quantum dots.
  • E is, S, Se, refers to at least any one of Te
  • the quantum dots by producing the quantum dots based on the synthesis method via the CuE intermediate, it is possible to produce quantum dots having an absorption wavelength in the near infrared region of 1300 nm to 1500 nm and having a uniform particle size. Specifically, as shown in the experimental results described later, it is possible to obtain quantum dots having a very uniform average particle size in the range of 6.0 to 6.5 nm.
  • ligands 2 are coordinated on the surface of the quantum dots. As a result, aggregation of quantum dots can be suppressed and the desired optical characteristics are exhibited.
  • the ligand that can be used in the reaction is not particularly limited, and examples thereof include the following ligands.
  • the average particle size of the quantum dots in this embodiment is 5.0 nm or more and 8.0 nm or less, preferably 5.5 nm or more, and more preferably 6.0 nm or more. In the experiment described later, the average particle size was 6.4 nm.
  • the absorption wavelength of the quantum dots can be freely controlled in the range of 1300 nm or more and 1500 nm or less.
  • the quantum dots in this embodiment are Ag 2 E-based solid solutions using an element of chalcogen in addition to silver.
  • the absorption wavelength can be appropriately controlled by adjusting the average particle size of the quantum dots and the composition of the quantum dots.
  • the absorption wavelength is preferably 1300 nm or more, and more preferably 1400 nm or more.
  • the quantum dot 1 may have a core-shell structure including a core 1a and a shell 1b coated on the surface of the core 1a. As shown in FIG. 1B, it is preferable that a large number of organic ligands 2 are coordinated on the surface of the quantum dots 1.
  • the core 1a shown in FIG. 1B is Ag 2 E.
  • the shell 1b does not contain regulated heavy metals such as Cd, Hg, and Pd, and substances derived from highly reactive reactants such as metal amides and organolithium compounds.
  • the shell 1b may be in a state of being dissolved on the surface of the core 1a.
  • the boundary between the core 1a and the shell 1b is shown by a dotted line, which means that the boundary between the core 1a and the shell 1b may or may not be confirmed by analysis.
  • quantum dots represented as Ag 2 E (E is at least one of Te, Se, or S) are synthesized from the silver raw material and the dicalcogen compound.
  • Copper acetylacetonate Cu ( acac) 2
  • a divalent compound can be used as a halide
  • copper (II) chloride CuCl 2
  • copper iodide (II): CuI 2, etc. can be used. it can.
  • the Ag raw material is not particularly limited, but for example, the following inorganic silver compound can be used. That is, a monovalent compound can be used as the halide, and silver (I) chloride: AgCl, silver bromide (I): AgBr, silver iodide (I): AgI and the like can be used.
  • an organic tellurium compound (organotellurium compound) or an inorganic tellurium compound dissolved in a high boiling point solvent can be used as a raw material.
  • the structure of the compound is not limited, but for example, tellurium is dissolved in Te-TOP in which tellurium is dissolved in trioctylphosphine, or tellurium is dissolved in a high boiling point solvent which is a long-chain hydrocarbon such as octadecene at a high temperature.
  • a solution or the like can be used.
  • an organic selenium compound (organoselenium compound) or an inorganic selenium compound dissolved in a high boiling point solvent is used as a raw material.
  • the structure is not particularly limited, for example, Se-TOP in which selenium is dissolved in trioctylphosphine, or a solution in which selenium is dissolved in a high boiling point solvent which is a long-chain hydrocarbon such as octadecene at a high temperature is used. Can be used.
  • an organic sulfur compound organic interchalcogen compound
  • an inorganic sulfur compound dissolved in a high boiling point solvent is used as a raw material.
  • the structure is not limited, for example, S-TOP in which sulfur is dissolved in trioctylphosphine, or a solution in which sulfur is dissolved at a high temperature in a high boiling point solvent which is a long-chain hydrocarbon such as octadecene, etc. Can be used.
  • a chalcogen solution as a precursor is obtained from the above-mentioned organic chalcogen or inorganic chalcogen.
  • the reaction temperature is preferably 100 ° C. or higher and 250 ° C. or lower at a lower temperature, more preferably 80 ° C. or higher and 230 ° C. or lower at a lower temperature, and 60 ° C. or higher and 200 ° C. or lower at a lower temperature. More preferred.
  • octadecene can be used as a saturated hydrocarbon having a high boiling point or an unsaturated hydrocarbon.
  • dodecylbenzene is used as an aromatic high-boiling solvent, and butyl butyrate: C 4 H 9 COOC 4 H 9 , benzyl butyrate: C 3 H 7 COOCH as a high-boiling ester-based solvent.
  • a silver raw material is quickly added to this intermediate solution, and the mixture is heated at 120 ° C. or higher and 300 ° C. or lower.
  • the reaction temperature at this time is preferably 120 ° C. or higher and 250 ° C. or lower at a lower temperature, more preferably 100 ° C. or higher and 230 ° C. or lower at a lower temperature, and 80 ° C. or higher and 200 ° C. or lower at a lower temperature. Is more preferable.
  • Ag 2 Te, Ag 2 Se, and Ag 2 S having a uniform average particle size can be synthesized.
  • the thiol is not limited, but for example, octadecane thiol: C 18 H 37 SH, hexane decane thiol: C 16 H 33 SH, tetradecane thiol: C 14 H 29 SH, dodecane thiol: C 12 H 25 SH, decan.
  • Thiol C 10 H 21 SH, octane thiol: C 8 H 17 SH and the like.
  • TOP trioctylphosphine
  • TOP is added in an amount of several mL to a dozen mL. This makes it possible to efficiently extract Cu into the solvent during the cation exchange reaction.
  • the present embodiment is not particularly limited in synthesis, in order to obtain the quantum dot having an absorption band in the near infrared wavelength, average particle size uniform Ag 2 Te, Ag 2 Se and,, Ag 2 It is important to synthesize S. Therefore, it is preferable to quickly add a silver raw material to CuE, which is an intermediate at room temperature, and heat the mixture to 120 ° C. or higher and 300 ° C. or lower.
  • Examples of the compound having the above-mentioned role include a ligand capable of forming a complex with silver.
  • a ligand capable of forming a complex with silver For example, a phosphorus-based ligand, an amine-based ligand, a thiol-based ligand, and a carboxylic acid-based ligand are preferable, and among them, a phosphorus-based ligand is particularly preferable because of its high efficiency.
  • the cation exchange reaction between Ag and Cu is appropriately carried out, and it is possible to produce quantum dots having a uniform particle size and having an absorption wavelength in the near infrared region based on Ag and chalcogen.
  • quantum dots of the present embodiment a heavy metal subject to regulation represented by Cd, Hg, Pb, a metal amide, and a reactant exhibiting a high reaction in the atmosphere represented by an organolithium compound. It is possible to synthesize quantum dots having a uniform particle size without including and as an intermediate. As a result, quantum dots can be synthesized by a manufacturing method that can be put into practical use, can be mass-produced, and has excellent safety.
  • Example 1 182.0 mg of copper acetate, 20.0 mL of octadecene (ODE), 1.26 mL of dodecanethiol (DDT), and 1.26 mL of trioctylphosphine (TOP) were placed in a 100 mL reaction vessel. Then, the raw material was dissolved by heating at 200 ° C. for 10 minutes while stirring under the atmosphere of an inert gas (N 2).
  • ODE octadecene
  • DDT dodecanethiol
  • TOP trioctylphosphine
  • the obtained dispersion was measured by an ultraviolet-visible absorption spectrum.
  • absorption maximums were obtained in the vicinity of 1200.0 nm and 1400.0 nm.
  • each particle size of 95% or more of the quantum dots was included in the average particle size ⁇ 0.5 nm. That is, it was found that each particle size of 95% or more of the quantum dots was included in the average particle size of ⁇ 6%, and the particle size of a large number of quantum dots could be generated very uniformly.
  • Example 2 In a 100 mL reaction vessel, 91.0 mg of copper acetate, 10.0 mL of octadecene (ODE), 0.63 mL of dodecanethiol (DDT), and 0.63 mL of trioctylphosphine (TOP) were placed. Then, the raw material was dissolved by heating at 200 ° C. for 10 minutes while stirring under the atmosphere of an inert gas (N 2).
  • ODE octadecene
  • DDT dodecanethiol
  • TOP trioctylphosphine
  • the obtained dispersion was measured by an ultraviolet-visible absorption spectrum.
  • the absorption maximums were obtained in the vicinity of 1200.0 nm and 1400.0 nm, as in the measurement result of the ultraviolet-visible near-infrared absorption spectrum of FIG. 2 of Example 1.
  • the average particle size of a large number of quantum dots is 6.4 nm, which is 5 nm or more and 8 nm or less, as in FIGS. 3A and 3B of Example 1. all right. Further, as in FIG. 4 of Example 1, each particle size of 95% or more of the quantum dots was included in the average particle size of ⁇ 0.5 nm. That is, it was found that each particle size of 95% or more of the quantum dots was included in the average particle size of ⁇ 6%, and the particle size of a large number of quantum dots could be generated very uniformly.
  • Example 3 In a 100 mL reaction vessel, 91.0 mg of copper acetate, 10.0 mL of octadecene (ODE), 0.63 mL of dodecanethiol (DDT), and 0.63 mL of trioctylphosphine (TOP) were placed. Then, the raw material was dissolved by heating at 200 ° C. for 10 minutes while stirring under the atmosphere of an inert gas (N 2).
  • ODE octadecene
  • DDT dodecanethiol
  • TOP trioctylphosphine
  • the obtained dispersion was measured by an ultraviolet-visible absorption spectrum.
  • the absorption maximums were obtained in the vicinity of 1200.0 nm and 1400.0 nm, as in the measurement result of the ultraviolet-visible near-infrared absorption spectrum of FIG. 2 of Example 1.
  • the average particle size of a large number of quantum dots is 6.4 nm, which is 5 nm or more and 8 nm or less, as in FIGS. 3A and 3B of Example 1. all right. Further, as in FIG. 4 of Example 1, each particle size of 95% or more of the quantum dots was included in the average particle size of ⁇ 0.5 nm. That is, it was found that each particle size of 95% or more of the quantum dots was included in the average particle size of ⁇ 6%, and the particle size of a large number of quantum dots could be generated very uniformly.
  • the obtained dispersion was measured by an ultraviolet-visible absorption spectrum.
  • no absorption derived from quantum dots could be confirmed in the ultraviolet-visible near-infrared absorption spectrum.
  • Quantum dot particles could not be confirmed in STEM, and diffraction peaks could not be confirmed in XRD. From these facts, it became clear that the selection of silver raw materials is very important in this synthetic method. That is, as in the examples, silver chloride is used as the silver raw material, or like silver chloride, a monovalent compound as a halide (silver bromide (I): AgBr, silver iodide (I): AgI, etc. ) Is preferable.
  • reaction solution (Ag 2 Te) was cooled to room temperature.
  • Ethanol was added to the obtained reaction solution to generate a precipitate, which was centrifuged to recover the precipitate. Then, toluene was added to the precipitate and dispersed to obtain a dispersion solution of Ag 2 Te quantum dots.
  • the average particle size of many quantum dots was 2.4 to 2.7 nm, and the average particle size was 5 nm or less.
  • silver chalcogenide quantum dots having an absorption wavelength in the near infrared region and having a very uniform particle size can be handled in the atmosphere without using a reactant showing high reactivity. It can be stably synthesized without passing through intermediates containing toxic regulated heavy metals. Then, by applying the quantum dots of the present invention to an optical communication device or the like, excellent eye-safe near-infrared light absorption characteristics can be obtained in the device.
  • the quantum dots of the present invention can be applied to the quantum dot layer of the eye-safe near-infrared light absorption layer of the infrared sensor.

Abstract

The purpose of the present invention is to provide: a quantum dot which absorbs near infrared light having wavelengths of 1300 nm or more and which is represented by the formula Ag2E (E is at least one of Te, Se and S); and a method for producing a quantum dot, the method enabling mass production and being highly safe. This quantum dot is characterized by: being a nanocrystal represented by the formula Ag2E (E is at least one of tellurium, selenium and sulfur), which contains silver and a chalcogen; and the absorption wavelength of the quantum dot falling within the near infrared region of 1300-1500 nm. This method for producing a quantum dot is characterized by having a step for obtaining a CuE intermediate (E is at least one of tellurium, selenium and sulfur) prepared from a silver raw material and a chalcogen raw material; and a step for subjecting the CuE intermediate to a cation exchange reaction using the Ag raw material so as to synthesize a quantum dot represented by Ag2E (E is at least one of tellurium, selenium and sulfur).

Description

量子ドット、及び、その製造方法Quantum dots and their manufacturing methods
　本発明は、近赤外領域で発光する量子ドット、及び、その製造方法に関する。 The present invention relates to quantum dots that emit light in the near infrared region and a method for producing the same.
　量子ドットは、数百～数千個程度の原子から構成された、粒径が数ｎｍ～数十ｎｍ程度のナノ粒子である。量子ドットは、蛍光ナノ粒子、半導体ナノ粒子、または、ナノクリスタルとも呼ばれる。 Quantum dots are nanoparticles with a particle size of several nm to several tens of nm, which are composed of hundreds to thousands of atoms. Quantum dots are also called fluorescent nanoparticles, semiconductor nanoparticles, or nanocrystals.
　量子ドットは、ナノ粒子の粒径や組成によって、吸収・発光波長を種々変更することができる。また、量子ドットの性能を表すものとして、蛍光量子収率（Ｑｕａｎｔｕｍ　Ｙｉｅｌｄ：ＱＹ）や粒子サイズ制御が挙げられる。 Quantum dots can have various absorption / emission wavelengths depending on the particle size and composition of nanoparticles. In addition, examples of the performance of quantum dots include fluorescence quantum yield (Quantum Yield: QY) and particle size control.
　例えば、下記の非特許文献１及び、非特許文献２には、銀カルコゲニド量子ドットに関する記載がある。 For example, the following Non-Patent Document 1 and Non-Patent Document 2 have a description regarding silver chalcogenide quantum dots.
　非特許文献１には、ＣｄＴｅからのカチオン交換法によるＡｇ２Ｔｅ量子ドットの合成法が報告されている。また、非特許文献２には、銀シリルアミドを経由するＡｇ２Ｔｅ量子ドットの合成法が報告されている。 Non-Patent Document 1 reports a method for synthesizing Ag 2 Te quantum dots by a cation exchange method from CdTe. Further, Non-Patent Document 2 reports a method for synthesizing Ag 2 Te quantum dots via silver silylamide.
　しかしながら、非特許文献１では、有毒性の規制対象重金属であるカドミウム中間体を経由する合成法であり、実用化に乏しい。また、非特許文献２で用いる銀シリルアミドは、大気下での使用において高い反応性を有する反応剤であり、その取扱いに注意を要することが問題である。 However, in Non-Patent Document 1, it is a synthetic method via a cadmium intermediate, which is a toxic regulated heavy metal, and is not practically used. Further, the silver silylamide used in Non-Patent Document 2 is a reactant having high reactivity when used in the atmosphere, and there is a problem that care must be taken in its handling.
　また、Ａｇ２Ｔｅ量子ドットの合成法として直接的合成法では、有毒性の規制対象重金属や大気下での使用において高い反応性を示す反応剤は用いないものの、生成するＡｇ２Ｔｅ量子ドットの平均粒径は、２．０～３．０ｎｍ程度となり、量子ドットとしてはかなり小さい。そして、１４００ｎｍ以上の波長の光は「アイセーフ」と呼ばれ、目に対して安全な光として多方面での用途が期待されていることから、この波長の光を選択的に吸収するＡｇ２Ｔｅ量子ドットの開発が望まれているが、上記の直接的合成法では、１２００ｎｍ程度までの吸収波長しか得られず、それよりも長い近赤外波長の光を得ることができなかった。 In addition, as a method for synthesizing Ag 2 Te quantum dots, the direct synthesis method does not use toxic regulated heavy metals or reactants that show high reactivity when used in the atmosphere, but it produces Ag 2 Te quantum dots. The average particle size is about 2.0 to 3.0 nm, which is quite small for a quantum dot. Light with a wavelength of 1400 nm or more is called "eye safe" and is expected to be used in various fields as light that is safe for the eyes. Therefore, Ag 2 Te that selectively absorbs light of this wavelength Although the development of quantum dots is desired, the above-mentioned direct synthesis method can obtain only an absorption wavelength up to about 1200 nm, and cannot obtain light having a near-infrared wavelength longer than that.
　本発明は、かかる点に鑑みてなされたものであり、１３００ｎｍ以上の波長の近赤外光吸収を示すＡｇ２Ｅ（Ｅは、Ｔｅ、Ｓｅ、Ｓの少なくともいずれか１種）で表される量子ドット、及び、量産可能であり、安全性の高い量子ドットの製造方法を提供することを目的とする。 The present invention has been made in view of this point, and is represented by Ag 2 E (E is at least one of Te, Se, and S) exhibiting near-infrared light absorption having a wavelength of 1300 nm or more. It is an object of the present invention to provide a quantum dot and a method for manufacturing a quantum dot that can be mass-produced and has high safety.
　本発明における量子ドットは、銀とカルコゲンとを含有するＡｇ２Ｅ（Ｅは、テルル、セレン、或いは、硫黄の少なくともいずれか１種）で表されるナノクリスタルであり、吸収波長が、１３００～１５００ｎｍの近赤外領域の範囲であることを特徴とする。 The quantum dot in the present invention is a nanocrystal represented by Ag 2 E (E is at least one of tellurium, selenium, or sulfur) containing silver and chalcogen, and has an absorption wavelength of 1300 to 1. It is characterized in that it is in the near infrared region of 1500 nm.
　本発明における量子ドットの製造方法は、銅原料とカルコゲン原料とから調整されるＣｕＥ（Ｅは、テルル、セレン、或いは、硫黄の少なくともいずれか１種）中間体を得る工程、前記ＣｕＥ中間体に対して、Ａｇ原料を用いたカチオン交換反応を経てＡｇ２Ｅ（Ｅは、テルル、セレン、或いは、硫黄の少なくともいずれか１種）で表される量子ドットを合成する工程、を有することを特徴とする。 The method for producing quantum dots in the present invention is a step of obtaining a CuE (E is at least one of tellurium, selenium, or sulfur) intermediate prepared from a copper raw material and a chalcogen raw material, and the CuE intermediate is used. On the other hand, it is characterized by having a step of synthesizing quantum dots represented by Ag 2 E (E is at least one of tellurium, selenium, or sulfur) through a cation exchange reaction using an Ag raw material. And.
　本発明の量子ドットによれば、１３００ｎｍ以上１５００ｎｍ以下の近赤外領域の吸収波長もつ吸収特性を得ることができる。 According to the quantum dots of the present invention, it is possible to obtain absorption characteristics having an absorption wavelength in the near infrared region of 1300 nm or more and 1500 nm or less.
　また、本発明の量子ドットの合成法によれば、カチオン交換反応を経ることで粒子サイズを精密に均一化でき、また、近赤外領域において量子ドット由来の吸収を示すスペクトルを得ることができる。 Further, according to the quantum dot synthesis method of the present invention, the particle size can be precisely made uniform by undergoing a cation exchange reaction, and a spectrum showing absorption derived from quantum dots can be obtained in the near infrared region. ..
　また、本発明の量子ドットの製造方法によれば、大気下にて取り扱うにあたり、高い反応性を示す反応剤や、有毒性の規制対象重金属を用いることなく、量産可能な方法で合成することが可能である。 Further, according to the method for producing quantum dots of the present invention, when the quantum dots are handled in the atmosphere, they can be synthesized by a method that can be mass-produced without using a highly reactive reactant or a toxic regulated heavy metal. It is possible.
本発明の実施形態における量子ドットの模式図である。It is a schematic diagram of the quantum dot in the embodiment of this invention. 実施例１におけるＡｇ２Ｔｅの吸収（Ａｂｓｏｒｐｔｉｏｎ）スペクトルである。9 is an Absorption spectrum of Ag 2 Te in Example 1. 実施例１におけるＡｇ２Ｔｅの走査透過電子顕微鏡（Ｓｃａｎｎｉｎｇ　ｔｒａｎｓｍｉｓｓｉｏｎ　ｅｌｅｃｔｒｏｎ　ｍｉｃｒｏｓｃｏｐｅ：ＳＴＥＭ）写真である。FIG. 3 is a scanning transmission electron microscope (STEM) photograph of Ag 2 Te in Example 1. 図３Ａの部分模式図である。It is a partial schematic view of FIG. 3A. 実施例１におけるＡｇ２ＴｅのＳＴＥＭ写真に基づいた粒子径解析結果である。It is a particle size analysis result based on the STEM photograph of Ag 2 Te in Example 1. 実施例１におけるＡｇ２ＴｅのＸ線回折（Ｘ－ｒａｙ　Ｄｉｆｆｒａｃｔｉｏｎ：ＸＲＤスペクトルである。It is an X-ray diffraction (XRD spectrum) of Ag 2 Te in Example 1. FIG.
　近年、ＣｄやＰｂなどの有毒性規制対象重金属を含まない近赤外発光性量子ドットが注目を集めている。例えば、Ａｇ２Ｔｅ量子ドットの合成法として直接的合成法によれば、有毒性の規制対象重金属や大気下での使用において高い反応性を示す反応剤は用いないものの、生成するＡｇ２Ｔｅ量子ドットの平均粒径は、２．０～３．０ｎｍ程度と量子ドットとしてはかなり小さくなり、それに由来して、生成したＡｇ２Ｔｅ量子ドットの吸収波長は、１１００～１２００ｎｍ程度であった。 In recent years, near-infrared luminescent quantum dots that do not contain heavy metals subject to toxic regulation such as Cd and Pb have been attracting attention. For example, according to the direct synthesis method as a method for synthesizing Ag 2 Te quantum dots, a toxic regulated heavy metal or a reactant showing high reactivity in use in the atmosphere is not used, but Ag 2 Te quantum is produced. The average particle size of the dots was about 2.0 to 3.0 nm, which was considerably small for a quantum dot, and the absorption wavelength of the generated Ag 2 Te quantum dots was about 1100-1200 nm.
　そこで本発明者らは、カチオン交換反応を経ることで粒子サイズを、直接的合成法よりも大きく、１３００ｎｍ～１５００ｎｍの近赤外領域の吸収波長を有する量子ドットを製造するに至った。また、量子ドットの製造の際、大気下にて取り扱うにあたり、高い反応性を示す反応剤や、有毒性の規制対象重金属を用いることなく、量産可能な方法で合成することを可能とした。 Therefore, the present inventors have come to produce quantum dots having an absorption wavelength in the near infrared region of 1300 nm to 1500 nm, which is larger than the direct synthesis method by undergoing a cation exchange reaction. In addition, in the production of quantum dots, when they are handled in the atmosphere, it has become possible to synthesize them by a method that can be mass-produced without using a reactant showing high reactivity or a toxic regulated heavy metal.
　以下、本発明の一実施形態（以下、「実施形態」と略記する）について、詳細に説明する。尚、本発明は以下の実施形態に限定されるものではなく、その要旨の範囲内で種々変形して実施することができる。なお、本実施の形態において、「～」の表記は、下限値及び上限値の双方を含む。 Hereinafter, one embodiment of the present invention (hereinafter, abbreviated as “embodiment”) will be described in detail. The present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof. In the present embodiment, the notation "-" includes both the lower limit value and the upper limit value.
　図１は、本実施形態における量子ドットの模式図である。図１Ａに示す量子ドット１は、銀（Ａｇ）と、カルコゲン（テルル（Ｔｅ）、セレン（Ｓｅ）、及び、硫黄（Ｓ）の少なくともいずれか１種を指す）とを含有するナノクリスタルである。以下では、本実施形態の量子ドットの化学式を、Ａｇ２Ｅ（Ｅは、Ｔｅ、Ｓｅ、Ｓの少なくともいずれか１種）で表す。 FIG. 1 is a schematic diagram of quantum dots in this embodiment. Quantum dot 1 shown in FIG. 1A is a nanocrystal containing silver (Ag) and chalcogen (referring to at least one of tellurium (Te), selenium (Se), and sulfur (S)). .. In the following, the chemical formula of the quantum dot of this embodiment is represented by Ag 2 E (E is at least one of Te, Se, and S).
　本実施形態における量子ドットは、非常に均一な粒子径を有し、その粒子の大きさから量子サイズ効果を発現する。 The quantum dots in this embodiment have a very uniform particle size, and the quantum size effect is exhibited from the size of the particles.
　ここで、「ナノクリスタル」とは、数ｎｍ～数十ｎｍ程度の粒径を有するナノ粒子を指す。本実施形態の量子ドットの平均粒径は、５ｎｍ以上８ｎｍ以下であることが好ましい。また、本実施の形態では、上記の平均粒径を満たすとともに、多数の量子ドットを、非常に均一な粒径にて生成することができる。「均一」とは、平均粒径の±６％以内に、９５％以上の粒子が含まれる状態を指す。このように、本実施形態では、微細で且つ非常に均一な良質の量子ドットを量産することができる。 Here, "nanocrystal" refers to nanoparticles having a particle size of about several nm to several tens of nm. The average particle size of the quantum dots of the present embodiment is preferably 5 nm or more and 8 nm or less. Further, in the present embodiment, it is possible to satisfy the above average particle size and generate a large number of quantum dots with a very uniform particle size. “Uniform” refers to a state in which 95% or more of the particles are contained within ± 6% of the average particle size. As described above, in the present embodiment, it is possible to mass-produce fine and very uniform high-quality quantum dots.
　本実施形態の量子ドットに含まれるＡｇとＴｅ、ＡｇとＳｅ、或いは、ＡｇとＳは、主成分であり、これら元素以外の元素が含まれていてもよい。ただし、後述するように、本実施形態の量子ドットの製法では、大気下で取り扱うにあたり高い反応性を示す、金属アミドや有機リチウム化合物等の反応剤を用いず、反応中間体にＣｄやＰｂに代表される規制対象重金属を含まない。含カドミウム・含鉛化合物は、有毒性の規制対象重金属であり、コストの上昇や取り扱いの制限、製造工程の煩雑性を招きやすくなる。本実施形態の量子ドットには、高反応性反応剤由来の物質や規制対象重金属が含まれない。 Ag and Te, Ag and Se, or Ag and S contained in the quantum dots of the present embodiment are main components, and elements other than these elements may be contained. However, as will be described later, in the method for producing quantum dots of the present embodiment, a reactant such as a metal amide or an organolithium compound, which exhibits high reactivity when handled in the atmosphere, is not used, and Cd or Pb is used as a reaction intermediate. Does not include heavy metals subject to regulation. Cadmium-containing and lead-containing compounds are toxic and regulated heavy metals, and are likely to cause cost increases, handling restrictions, and complicated manufacturing processes. The quantum dots of the present embodiment do not contain substances derived from highly reactive reactants or regulated heavy metals.
　本実施形態の量子ドットは、吸収波長が、１３００ｍ～１５００ｎｍの近赤外領域の範囲である。ここで「吸収波長」は、吸収スペクトルのピークの波長をいう。本実施形態の量子ドットの吸収波長は、１３５０ｎｍ以上１５００ｎｍ以下であることが好ましく、１４００ｎｍ以上１５００ｎｍ以下であることがより好ましい。 The quantum dots of this embodiment have an absorption wavelength in the near infrared region of 1300 m to 1500 nm. Here, the "absorption wavelength" refers to the wavelength of the peak of the absorption spectrum. The absorption wavelength of the quantum dots of the present embodiment is preferably 1350 nm or more and 1500 nm or less, and more preferably 1400 nm or more and 1500 nm or less.
　本実施形態では、後述するように、量子ドットを合成する反応系として、まず銅化合物を前駆体として、前駆体に対してカルコゲンの導入を行う。生成したＣｕＥ（Ｅは、Ｓ、Ｓｅ、Ｔｅの少なくともいずれか１種を指す）に対して、銀原料を適切な温度にて反応させて、Ａｇ２Ｅ量子ドットを合成する。このように、ＣｕＥ中間体を経る合成法に基づいて量子ドットを製造することで、１３００ｎｍ～１５００ｎｍの近赤外領域に吸収波長を有する、粒子サイズの均一な量子ドットを製造することができる。後述する実験結果に示すように、具体的には、６．０～６．５ｎｍの範囲で平均粒子径が非常に均一な量子ドットを得ることができる。 In the present embodiment, as will be described later, as a reaction system for synthesizing quantum dots, first, a copper compound is used as a precursor, and chalcogen is introduced into the precursor. The resulting CUE (E is, S, Se, refers to at least any one of Te) against a silver raw material is reacted at a suitable temperature, to synthesize the Ag 2 E quantum dots. As described above, by producing the quantum dots based on the synthesis method via the CuE intermediate, it is possible to produce quantum dots having an absorption wavelength in the near infrared region of 1300 nm to 1500 nm and having a uniform particle size. Specifically, as shown in the experimental results described later, it is possible to obtain quantum dots having a very uniform average particle size in the range of 6.0 to 6.5 nm.
　図１Ａに示すように、量子ドットの表面には、多数の有機配位子２が配位していることが好ましい。これにより、量子ドット同士の凝集を抑制でき、目的とする光学特性が発現する。反応に用いることのできる配位子は、特に限定されないが、例えば、以下の配位子が代表的なものとして挙げられる。 As shown in FIG. 1A, it is preferable that a large number of organic ligands 2 are coordinated on the surface of the quantum dots. As a result, aggregation of quantum dots can be suppressed and the desired optical characteristics are exhibited. The ligand that can be used in the reaction is not particularly limited, and examples thereof include the following ligands.
（１）脂肪族１級アミン系
　オレイルアミン：Ｃ１８Ｈ３５ＮＨ２、ステアリル（オクタデシル）アミン：Ｃ１８Ｈ３７ＮＨ２、ドデシル（ラウリル）アミン：Ｃ１２Ｈ２５ＮＨ２、デシルアミン：Ｃ１０Ｈ２１ＮＨ２、オクチルアミン：Ｃ８Ｈ１７ＮＨ２
（２）脂肪酸系
　オレイン酸：Ｃ１７Ｈ３３ＣＯＯＨ、ステアリン酸：Ｃ１７Ｈ３５ＣＯＯＨ、パルミチン酸：Ｃ１５Ｈ３１ＣＯＯＨ、ミリスチン酸：Ｃ１３Ｈ２７ＣＯＯＨ、ラウリル酸：Ｃ１１Ｈ２３ＣＯＯＨ、デカン酸：Ｃ９Ｈ１９ＣＯＯＨ、オクタン酸：Ｃ７Ｈ１５ＣＯＯＨ
（３）チオール系
　オクタデカンチオール：Ｃ１８Ｈ３７ＳＨ、ヘキサンデカンチオール：Ｃ１６Ｈ３３ＳＨ、テトラデカンチオール：Ｃ１４Ｈ２９ＳＨ、ドデカンチオール：Ｃ１２Ｈ２５ＳＨ、デカンチオール：Ｃ１０Ｈ２１ＳＨ、オクタンチオール：Ｃ８Ｈ１７ＳＨ
（４）ホスフィン系
　トリオクチルホスフィン：（Ｃ８Ｈ１７）３Ｐ、トリフェニルホスフィン：（Ｃ６Ｈ５）３Ｐ、トリブチルホスフィン：（Ｃ４Ｈ９）３Ｐ
（５）ホスフィンオキシド系
　トリオクチルホスフィンオキシド：（Ｃ８Ｈ１７）３Ｐ＝Ｏ、トリフェニルホスフィンオキシド：（Ｃ６Ｈ５）３Ｐ＝Ｏ、トリブチルホスフィンオキシド：（Ｃ４Ｈ９）３Ｐ＝Ｏ (1) Aliphatic primary amine-based oleyl amine: C 18 H 35 NH 2 , stearyl (octadecyl) amine: C 18 H 37 NH 2 , dodecyl (lauryl) amine: C 12 H 25 NH 2 , decyl amine: C 10 H 21 NH 2 , octylamine: C 8 H 17 NH 2
(2) Fatty acid-based oleic acid: C 17 H 33 COOH, stearic acid: C 17 H 35 COOH, palmitic acid: C 15 H 31 COOH, myristic acid: C 13 H 27 COOH, lauric acid: C 11 H 23 COOH, Decanoic acid: C 9 H 19 COOH, Octanoic acid: C 7 H 15 COOH
(3) Thiol-based octadecane thiol: C 18 H 37 SH, hexane decane thiol: C 16 H 33 SH, tetradecane thiol: C 14 H 29 SH, dodecane thiol: C 12 H 25 SH, decane thiol: C 10 H 21 SH , Octadecane Thiol: C 8 H 17 SH
(4) Phosphine-based trioctylphosphine: (C 8 H 17 ) 3 P, triphenylphosphine: (C 6 H 5 ) 3 P, tributyl phosphine: (C 4 H 9 ) 3 P
(5) Phosphine oxide-based trioctylphosphine oxide: (C 8 H 17 ) 3 P = O, triphenylphosphine oxide: (C 6 H 5 ) 3 P = O, tributylphosphine oxide: (C 4 H 9 ) 3 P = O
　本実施形態における量子ドットの平均粒径は、５．０ｎｍ以上８．０ｎｍ以下であり、好ましくは、５．５ｎｍ以上であり、より好ましくは６．０ｎｍ以上である。後述する実験では、平均粒径は、６．４ｎｍであった。 The average particle size of the quantum dots in this embodiment is 5.0 nm or more and 8.0 nm or less, preferably 5.5 nm or more, and more preferably 6.0 nm or more. In the experiment described later, the average particle size was 6.4 nm.
　また、本実施形態では、量子ドットの吸収波長を、１３００ｎｍ以上１５００ｎｍ以下の範囲で自由に制御することができる。本実施形態における量子ドットは、銀以外にカルコゲン元素を用いたＡｇ２Ｅをベースとする固溶体である。本実施形態では、量子ドットの平均粒径、及び、量子ドットの組成を調整することによって、吸収波長を適宜制御することが可能である。吸収波長は、１３００ｎｍ以上であることが好ましく、１４００ｎｍ以上であることがより好ましい。 Further, in the present embodiment, the absorption wavelength of the quantum dots can be freely controlled in the range of 1300 nm or more and 1500 nm or less. The quantum dots in this embodiment are Ag 2 E-based solid solutions using an element of chalcogen in addition to silver. In the present embodiment, the absorption wavelength can be appropriately controlled by adjusting the average particle size of the quantum dots and the composition of the quantum dots. The absorption wavelength is preferably 1300 nm or more, and more preferably 1400 nm or more.
　本実施形態では、図１Ｂに示すように、量子ドット１は、コア１ａと、コア１ａの表面に被覆されたシェル１ｂと、を有するコアシェル構造であってもよい。図１Ｂに示すように、量子ドット１の表面には多数の有機配位子２が配位していることが好ましい。 In the present embodiment, as shown in FIG. 1B, the quantum dot 1 may have a core-shell structure including a core 1a and a shell 1b coated on the surface of the core 1a. As shown in FIG. 1B, it is preferable that a large number of organic ligands 2 are coordinated on the surface of the quantum dots 1.
　図１Ｂに示すコア１ａが、Ａｇ２Ｅである。シェル１ｂは、コア１ａと同様に、ＣｄやＨｇ、Ｐｄ等の規制対象重金属や、金属アミドや有機リチウム化合物に代表される高反応性反応剤由来の物質を含まない。 The core 1a shown in FIG. 1B is Ag 2 E. Like the core 1a, the shell 1b does not contain regulated heavy metals such as Cd, Hg, and Pd, and substances derived from highly reactive reactants such as metal amides and organolithium compounds.
　なお、シェル１ｂは、コア１ａの表面に固溶化した状態であってもよい。図１Ｂでは、コア１ａとシェル１ｂとの境界を点線で示したが、これは、コア１ａとシェル１ｂとの境界を分析により確認できてもできなくてもどちらでもよいことを指す。 The shell 1b may be in a state of being dissolved on the surface of the core 1a. In FIG. 1B, the boundary between the core 1a and the shell 1b is shown by a dotted line, which means that the boundary between the core 1a and the shell 1b may or may not be confirmed by analysis.
　ただし、本実施形態では、シェル１ｂを用いずにコア１ａのみ、すなわち図１Ａのコア単体の量子ドット１にて、１３００～１５００ｎｍの近赤外領域の吸収波長もつ吸収特性を得ることができる。 However, in the present embodiment, it is possible to obtain an absorption characteristic having an absorption wavelength in the near infrared region of 1300 to 1500 nm with only the core 1a, that is, the quantum dot 1 of the core alone in FIG. 1A without using the shell 1b.
　次に、本実施形態の量子ドットの製造方法について説明する。本実施形態では、銀原料と、ジカルコゲン化合物とから、Ａｇ２Ｅ（Ｅは、Ｔｅ、Ｓｅ、或いは、Ｓの少なくともいずれか１種）として表される量子ドットを合成する。 Next, the method for manufacturing the quantum dots of the present embodiment will be described. In the present embodiment, quantum dots represented as Ag 2 E (E is at least one of Te, Se, or S) are synthesized from the silver raw material and the dicalcogen compound.
　本実施形態では、Ｃｕ原料として、特に限定はしないが、例えば、下記の有機銅化合物や無機銅化合物を用いることができる。すなわち、酢酸塩として酢酸銅（ＩＩ）：Ｃｕ（ＯＡｃ）２、脂肪酸塩として、ステアリン酸銅：Ｃｕ（ＯＣ（＝Ｏ）Ｃ１７Ｈ３５）２、オレイン酸銅：Ｃｕ（ＯＣ（＝Ｏ）Ｃ１７Ｈ３３）２、ミリスチン酸銅：Ａｇ（ＯＣ（＝Ｏ）Ｃ１３Ｈ２７）２、ドデカン酸銅：Ｃｕ（ＯＣ（＝Ｏ）Ｃ１１Ｈ２３）２、銅アセチルアセトネート：Ｃｕ（ａｃａｃ）２、ハロゲン化物として２価の化合物が使用可能であり、塩化銅（ＩＩ）：ＣｕＣｌ２、臭化銅（ＩＩ）：ＣｕＢｒ２、ヨウ化銅（ＩＩ）：ＣｕＩ２などを用いることができる。 In the present embodiment, the Cu raw material is not particularly limited, but for example, the following organic copper compounds and inorganic copper compounds can be used. That is, copper acetate (II): Cu (OAc) 2 as an acetate, copper stearate: Cu (OC (= O) C 17 H 35 ) 2 as a fatty acid salt, copper oleate: Cu (OC (= O)). C 17 H 33 ) 2 , Copper myristate: Ag (OC (= O) C 13 H 27 ) 2 , Copper dodecanoate: Cu (OC (= O) C 11 H 23 ) 2 , Copper acetylacetonate: Cu ( acac) 2 , a divalent compound can be used as a halide, and copper (II) chloride: CuCl 2 , copper bromide (II): CuBr 2 , copper iodide (II): CuI 2, etc. can be used. it can.
　本実施形態では、Ａｇ原料として、特に限定はしないが、例えば、下記の無機銀化合物を用いることができる。すなわち、ハロゲン化物として１価の化合物が使用可能であり、塩化銀（Ｉ）：ＡｇＣｌ、臭化銀（Ｉ）：ＡｇＢｒ、ヨウ化銀（Ｉ）：ＡｇＩなどを用いることができる。 In the present embodiment, the Ag raw material is not particularly limited, but for example, the following inorganic silver compound can be used. That is, a monovalent compound can be used as the halide, and silver (I) chloride: AgCl, silver bromide (I): AgBr, silver iodide (I): AgI and the like can be used.
　本実施形態では、テルルを固溶させる場合、有機テルル化合物（有機カルコゲン化合物）、又は、無機テルル化合物を高沸点溶媒に溶解したものを原料として用いることができる。特に、化合物の構造を限定するものではないが、例えば、テルルをトリオクチルホスフィンに溶解したＴｅ－ＴＯＰ、又は、オクタデセンのような長鎖の炭化水素である高沸点溶媒にテルルを高温で溶解させた溶液等を用いることができる。 In the present embodiment, when tellurium is dissolved as a solid solution, an organic tellurium compound (organotellurium compound) or an inorganic tellurium compound dissolved in a high boiling point solvent can be used as a raw material. In particular, the structure of the compound is not limited, but for example, tellurium is dissolved in Te-TOP in which tellurium is dissolved in trioctylphosphine, or tellurium is dissolved in a high boiling point solvent which is a long-chain hydrocarbon such as octadecene at a high temperature. A solution or the like can be used.
　また、本実施形態では、セレンを固溶させる場合、有機セレン化合物（有機カルコゲン化合物）、又は、無機セレン化合物を高沸点溶媒に溶解したものを原料として用いる。特に構造を限定するものでないが、例えば、セレンをトリオクチルホスフィンに溶解したＳｅ－ＴＯＰ、又は、オクタデセンのような長鎖の炭化水素である高沸点溶媒にセレンを高温で溶解させた溶液等を用いることができる。 Further, in the present embodiment, when selenium is dissolved in solid form, an organic selenium compound (organoselenium compound) or an inorganic selenium compound dissolved in a high boiling point solvent is used as a raw material. Although the structure is not particularly limited, for example, Se-TOP in which selenium is dissolved in trioctylphosphine, or a solution in which selenium is dissolved in a high boiling point solvent which is a long-chain hydrocarbon such as octadecene at a high temperature is used. Can be used.
　また、本実施形態では、硫黄を固溶させる場合、有機硫黄化合物（有機カルコゲン化合物）、又は、無機硫黄化合物を高沸点溶媒に溶解したものを原料として用いる。特に、構造を限定するものでないが、例えば、硫黄をトリオクチルホスフィンに溶解したＳ－ＴＯＰ、又は、オクタデセンのような長鎖の炭化水素である高沸点溶媒に硫黄を高温で溶解させた溶液等を用いることができる。 Further, in the present embodiment, when sulfur is solid-dissolved, an organic sulfur compound (organic interchalcogen compound) or an inorganic sulfur compound dissolved in a high boiling point solvent is used as a raw material. In particular, although the structure is not limited, for example, S-TOP in which sulfur is dissolved in trioctylphosphine, or a solution in which sulfur is dissolved at a high temperature in a high boiling point solvent which is a long-chain hydrocarbon such as octadecene, etc. Can be used.
　本実施形態では、上記した有機カルコゲンや無機カルコゲンより、前駆体としてのカルコゲン溶液を得る。本実施形態では、前駆体としてのカルコゲン溶液を、１２０℃以上で３００℃以下の範囲で合成することが好ましい。また、反応温度を、より低温の１００℃以上２５０℃以下とすることが好ましく、更に低温の８０℃以上２３０℃以下とすることがより好ましく、更に低温の６０℃以上２００℃以下とすることが更に好ましい。 In the present embodiment, a chalcogen solution as a precursor is obtained from the above-mentioned organic chalcogen or inorganic chalcogen. In the present embodiment, it is preferable to synthesize a chalcogen solution as a precursor at 120 ° C. or higher and 300 ° C. or lower. Further, the reaction temperature is preferably 100 ° C. or higher and 250 ° C. or lower at a lower temperature, more preferably 80 ° C. or higher and 230 ° C. or lower at a lower temperature, and 60 ° C. or higher and 200 ° C. or lower at a lower temperature. More preferred.
　そして、銅原料と、カルコゲン溶液とを混合し、溶解・反応させる。溶媒としては、高沸点の飽和炭化水素または不飽和炭化水素として、オクタデセンを用いることができる。これ以外にも芳香族系の高沸点溶媒として、ドデシルベンゼン（ｄｏｄｅｃｙｌｂｅｎｚｅｎｅ）、高沸点のエステル系の溶媒として、ブチルブチレート：Ｃ４Ｈ９ＣＯＯＣ４Ｈ９、ベンジルブチレート：Ｃ３Ｈ７ＣＯＯＣＨ２Ｃ６Ｈ５などを用いることが可能であるが、脂肪族チオール系、脂肪族アミン系、又は、脂肪酸系の化合物や脂肪族リン系の化合物を溶媒として用いることも可能である。これにより、反応中間体としてＣｕＥ（Ｅは、Ｔｅ、Ｓｅ、或いは、Ｓの少なくともいずれか１種）を得る。 Then, the copper raw material and the chalcogen solution are mixed, dissolved and reacted. As the solvent, octadecene can be used as a saturated hydrocarbon having a high boiling point or an unsaturated hydrocarbon. In addition to this, dodecylbenzene is used as an aromatic high-boiling solvent, and butyl butyrate: C 4 H 9 COOC 4 H 9 , benzyl butyrate: C 3 H 7 COOCH as a high-boiling ester-based solvent. 2 C 6 H 5 and the like can be used, but an aliphatic thiol-based compound, an aliphatic amine-based compound, a fatty acid-based compound, or an aliphatic phosphorus-based compound can also be used as a solvent. As a result, CuE (E is at least one of Te, Se, or S) is obtained as a reaction intermediate.
　この中間体溶液に対し、銀原料を手早く添加し、１２０℃以上３００℃以下で加熱する。このときの反応温度を、より低温の１２０℃以上２５０℃以下とすることが好ましく、更に低温の１００℃以上２３０℃以下とすることがより好ましく、更に低温の８０℃以上２００℃以下とすることが更に好ましい。この操作を二回以上繰り返すことで、平均粒径が均一なＡｇ２Ｔｅ、Ａｇ２Ｓｅ、及び、Ａｇ２Ｓを合成することができる。 A silver raw material is quickly added to this intermediate solution, and the mixture is heated at 120 ° C. or higher and 300 ° C. or lower. The reaction temperature at this time is preferably 120 ° C. or higher and 250 ° C. or lower at a lower temperature, more preferably 100 ° C. or higher and 230 ° C. or lower at a lower temperature, and 80 ° C. or higher and 200 ° C. or lower at a lower temperature. Is more preferable. By repeating this operation twice or more, Ag 2 Te, Ag 2 Se, and Ag 2 S having a uniform average particle size can be synthesized.
　特に、平均粒径が均一なＡｇ２Ｅを得るために、前駆体であるカルコゲン化合物と銅原料との反応において、チオールをＴｅ、Ｓｅ或いはＳに対して１～５当量添加することが好ましく、３～５当量添加することがより好ましい。特に、チオールを限定するものでないが、例えば、オクタデカンチオール：Ｃ１８Ｈ３７ＳＨ、ヘキサンデカンチオール：Ｃ１６Ｈ３３ＳＨ、テトラデカンチオール：Ｃ１４Ｈ２９ＳＨ、ドデカンチオール：Ｃ１２Ｈ２５ＳＨ、デカンチオール：Ｃ１０Ｈ２１ＳＨ、オクタンチオール：Ｃ８Ｈ１７ＳＨ等である。 In particular, in order to obtain Ag 2 E having a uniform average particle size, it is preferable to add 1 to 5 equivalents of thiol to Te, Se or S in the reaction between the precursor chalcogen compound and the copper raw material. It is more preferable to add 3 to 5 equivalents. In particular, the thiol is not limited, but for example, octadecane thiol: C 18 H 37 SH, hexane decane thiol: C 16 H 33 SH, tetradecane thiol: C 14 H 29 SH, dodecane thiol: C 12 H 25 SH, decan. Thiol: C 10 H 21 SH, octane thiol: C 8 H 17 SH and the like.
　また、本実施の形態では、ホスフィンを含む溶媒中で、量子ドットを合成することが好ましい。ホスフィンを含む溶媒としては、トリオクチルホスフィン（ＴＯＰ）を例に挙げることができる。例えば、トリオクチルホスフィン（ＴＯＰ）を数ｍＬ～十数ｍＬ程度添加する。これにより、カチオン交換反応の際、Ｃｕを効率的に溶媒中に引き抜くことが可能になる。 Further, in the present embodiment, it is preferable to synthesize quantum dots in a solvent containing phosphine. As the solvent containing phosphine, trioctylphosphine (TOP) can be mentioned as an example. For example, trioctylphosphine (TOP) is added in an amount of several mL to a dozen mL. This makes it possible to efficiently extract Cu into the solvent during the cation exchange reaction.
　また、本実施形態では、合成法に特に限定はないが、近赤外波長に吸収帯を有する量子ドットを得るために、平均粒径が均一のＡｇ２Ｔｅ、Ａｇ２Ｓｅ、及び、Ａｇ２Ｓを合成することが重要である。このため、室温で中間体であるＣｕＥに対して、銀原料を手早く添加し、１２０℃以上３００度以下まで加熱するのが好ましい。 Further, in the present embodiment is not particularly limited in synthesis, in order to obtain the quantum dot having an absorption band in the near infrared wavelength, average particle size uniform Ag 2 Te, Ag 2 Se and,, Ag 2 It is important to synthesize S. Therefore, it is preferable to quickly add a silver raw material to CuE, which is an intermediate at room temperature, and heat the mixture to 120 ° C. or higher and 300 ° C. or lower.
　また、本実施形態では、反応を行う際に、中間体の金属を配位またはキレートなどにより反応溶液中に遊離させる補助的な役割をもつ化合物が必要である。 Further, in the present embodiment, when the reaction is carried out, a compound having an auxiliary role of releasing the intermediate metal into the reaction solution by coordination or chelation is required.
　上述の役割を有する化合物としては、銀と錯形成可能なリガンドが挙げられる。例えば、リン系リガンド、アミン系リガンド、チオール系リガンド、カルボン酸系リガンドが好ましく、その中でも、その効率の高さからリン系リガンドが特に好ましい。 Examples of the compound having the above-mentioned role include a ligand capable of forming a complex with silver. For example, a phosphorus-based ligand, an amine-based ligand, a thiol-based ligand, and a carboxylic acid-based ligand are preferable, and among them, a phosphorus-based ligand is particularly preferable because of its high efficiency.
　これにより、ＡｇとＣｕとのカチオン交換反応が適切に行われ、Ａｇとカルコゲンとをベースとし、近赤外領域に吸収波長を有する均一な粒子径の量子ドットを製造することができる。 As a result, the cation exchange reaction between Ag and Cu is appropriately carried out, and it is possible to produce quantum dots having a uniform particle size and having an absorption wavelength in the near infrared region based on Ag and chalcogen.
　また、本実施形態の量子ドットの製造方法によれば、Ｃｄ、Ｈｇ、Ｐｂに代表される規制対象重金属と、金属アミド、及び、有機リチウム化合物に代表される大気下で高反応を示す反応剤と、を中間体として含むことなく、均一な粒子径をもつ量子ドットを合成することができる。これにより、実用化でき、量産可能で、且つ安全性に優れた製法で、量子ドットを合成することができる。 Further, according to the method for producing quantum dots of the present embodiment, a heavy metal subject to regulation represented by Cd, Hg, Pb, a metal amide, and a reactant exhibiting a high reaction in the atmosphere represented by an organolithium compound. It is possible to synthesize quantum dots having a uniform particle size without including and as an intermediate. As a result, quantum dots can be synthesized by a manufacturing method that can be put into practical use, can be mass-produced, and has excellent safety.
　以下、本発明の実施例及び比較例により本発明の効果を説明する。なお、本発明は、以下の実施例によって何ら限定されるものではない。 Hereinafter, the effects of the present invention will be described with reference to Examples and Comparative Examples of the present invention. The present invention is not limited to the following examples.
＜原料＞
　実験では、近赤外領域に吸収波長を有する銀カルコゲニド化合物（Ａｇ２Ｅ系）量子ドットを合成するにあたり以下の原料を用いた。
（溶媒）
　オクタデセン：Ａｌｄｒｉｃｈ株式会社製、出光興産株式会社製
　ドデカンチオール：アルケマ社製
　オレイルアミン：花王株式会社製
　トリオクチルホスフィン：北興化学株式会社製
（銅原料）
　酢酸銅：キシダ化学株式会社製
（銀原料）
　硝酸銀：キシダ化学株式会社製
　塩化銀：キシダ化学株式会社製
（テルル原料）
　テルル（４Ｎ：９９．９９％）：新興化学株式会社製
＜測定機器＞
　紫外－可視光分光光度計：日立株式会社製　Ｖ－７７０
　Ｘ線回折装置（ＸＲＤ）：Ｂｒｕｋｅｒ社製　Ｄ２　ＰＨＡＳＥＲ
　走査透過電子顕微鏡（ＳＴＥＭ）：日立株式会社製　ＳＵ９０００ <Raw materials>
In the experiment, using the following ingredients Upon synthesizing silver chalcogenide compound (Ag 2 E system) quantum dots having an absorption wavelength in the near infrared region.
(solvent)
Octadesen: Aldrich Co., Ltd., Idemitsu Kosan Co., Ltd. Dodecane Thiol: Alchema Co., Ltd. Oleylamine: Kao Corporation Trioctylphosphine: Hokuko Chemical Co., Ltd. (copper raw material)
Copper acetate: manufactured by Kishida Chemical Co., Ltd. (silver raw material)
Silver nitrate: Made by Kishida Chemical Co., Ltd. Silver chloride: Made by Kishida Chemical Co., Ltd. (Tellurium raw material)
Tellurium (4N: 99.99%): Made by Shinko Kagaku Co., Ltd. <Measuring equipment>
Ultraviolet-Visible Light Spectrophotometer: Hitachi, Ltd. V-770
X-ray diffractometer (XRD): Bruker D2 PHASER
Scanning Transmission Electron Microscope (STEM): SU9000 manufactured by Hitachi, Ltd.
　［実施例１］
　１００ｍＬ反応容器に、酢酸銅を１８２．０ｍｇ、オクタデセン（ＯＤＥ）を２０．０ｍＬ、ドデカンチオール（ＤＤＴ）を１．２６ｍＬ、トリオクチルホスフィン（ＴＯＰ）を１．２６ｍＬ入れた。そして、不活性ガス（Ｎ２）雰囲気下で攪拌しながら、２００℃で１０分間加熱し、原料を溶解させた。 [Example 1]
182.0 mg of copper acetate, 20.0 mL of octadecene (ODE), 1.26 mL of dodecanethiol (DDT), and 1.26 mL of trioctylphosphine (TOP) were placed in a 100 mL reaction vessel. Then, the raw material was dissolved by heating at 200 ° C. for 10 minutes while stirring under the atmosphere of an inert gas (N 2).
　この溶液に対し、反応温度を保ったまま０．５ｍｏｌ／Ｌのテルル－ＴＯＰ溶液を１．８ｍＬ、オレイルアミンを０．２６ｍＬ添加し、引き続き２００℃で１５分間、攪拌しつつ加熱した。得られた反応溶液（ＣｕＴｅ）を、室温まで冷却した。 To this solution, 1.8 mL of a 0.5 mol / L tellurium-TOP solution and 0.26 mL of oleylamine were added while maintaining the reaction temperature, and the mixture was subsequently heated at 200 ° C. for 15 minutes with stirring. The obtained reaction solution (CuTe) was cooled to room temperature.
　得られた反応液に、塩化銀７１６．６ｍｇ、ＴＯＰを１５．０ｍＬ、オレイルアミンを０．５０ｍＬ、ＤＤＴを１．２６ｍＬ添加し、２００℃まで昇温して３０分間加熱し、その後、室温まで冷却した。 To the obtained reaction solution, 716.6 mg of silver chloride, 15.0 mL of TOP, 0.50 mL of oleylamine, and 1.26 mL of DDT were added, the temperature was raised to 200 ° C., heated for 30 minutes, and then cooled to room temperature. did.
　この溶液にトルエンとエタノールを加え沈殿を発生させ、遠心分離を施して沈殿を回収した。そして、その沈殿を再度２０ｍＬのＯＤＥに分散させた。 Toluene and ethanol were added to this solution to generate a precipitate, and centrifugation was performed to recover the precipitate. Then, the precipitate was dispersed again in 20 mL of ODE.
　この分散液に、塩化銀７１６．６ｍｇ、ＴＯＰを１５．０ｍＬ、オレイルアミンを０．５０ｍＬ、ＤＤＴを１．２６ｍＬ添加し、２００℃まで昇温して３０分間加熱し、その後、室温まで冷却した。 To this dispersion, 716.6 mg of silver chloride, 15.0 mL of TOP, 0.50 mL of oleylamine, and 1.26 mL of DDT were added, the temperature was raised to 200 ° C., heated for 30 minutes, and then cooled to room temperature.
　この溶液にトルエンとエタノールを加え沈殿を発生させ、遠心分離を施して沈殿を回収した。この沈殿に対してトルエンを加えて分散液とした。 Toluene and ethanol were added to this solution to generate a precipitate, and centrifugation was performed to recover the precipitate. Toluene was added to this precipitate to prepare a dispersion.
　得られた分散液を、紫外可視吸収スペクトルで測定した。その結果、図２の紫外可視近赤外吸収スペクトルの測定結果に示すように、１２００．０ｎｍ、および、１４００．０ｎｍ付近に吸収極大が得られた。 The obtained dispersion was measured by an ultraviolet-visible absorption spectrum. As a result, as shown in the measurement result of the ultraviolet-visible-near-infrared absorption spectrum of FIG. 2, absorption maximums were obtained in the vicinity of 1200.0 nm and 1400.0 nm.
　また、図３Ａ及び図３Ｂ（図３Ａの部分模式図）に示すＳＴＥＭ写真より、多数の量子ドットの平均粒径は６．４ｎｍであり、５ｎｍ以上８ｎｍ以下であることがわかった。また、図４に記載の粒径解析結果から、９５％以上の量子ドットの各粒径が平均粒径±０．５ｎｍに含まれていた。すなわち、９５％以上の量子ドットの各粒径が平均粒径±６％に含まれており、多数の量子ドットの粒径を非常に均一に生成できたことがわかった。 Further, from the STEM photographs shown in FIGS. 3A and 3B (partial schematic view of FIG. 3A), it was found that the average particle size of a large number of quantum dots was 6.4 nm, which was 5 nm or more and 8 nm or less. Further, from the particle size analysis results shown in FIG. 4, each particle size of 95% or more of the quantum dots was included in the average particle size ± 0.5 nm. That is, it was found that each particle size of 95% or more of the quantum dots was included in the average particle size of ± 6%, and the particle size of a large number of quantum dots could be generated very uniformly.
　また、図５に示すＡｇ２ＴｅのＸＲＤスペクトルのピーク値より、Ａｇ２Ｔｅ固溶体が生成していることが証明された。 Further, from the peak value of the XRD spectrum of Ag 2 Te shown in FIG. 5, it was proved that the Ag 2 Te solid solution was formed.
　［実施例２］
　１００ｍＬ反応容器に、酢酸銅を９１．０ｍｇ、オクタデセン（ＯＤＥ）を１０．０ｍＬ、ドデカンチオール（ＤＤＴ）を０．６３ｍＬ、トリオクチルホスフィン（ＴＯＰ）を０．６３ｍＬ入れた。そして、不活性ガス（Ｎ２）雰囲気下で攪拌しながら、２００℃で１０分間加熱し、原料を溶解させた。 [Example 2]
In a 100 mL reaction vessel, 91.0 mg of copper acetate, 10.0 mL of octadecene (ODE), 0.63 mL of dodecanethiol (DDT), and 0.63 mL of trioctylphosphine (TOP) were placed. Then, the raw material was dissolved by heating at 200 ° C. for 10 minutes while stirring under the atmosphere of an inert gas (N 2).
　この溶液に、反応温度を保ったまま０．５Ｍのテルル－ＴＯＰ溶液を０．９ｍＬ、オレイルアミンを０．１３ｍＬ添加し、２００℃で１５分間、攪拌しつつ加熱した。得られた反応溶液（ＣｕＴｅ）を、室温まで冷却した。 To this solution, 0.9 mL of a 0.5 M tellurium-TOP solution and 0.13 mL of oleylamine were added while maintaining the reaction temperature, and the mixture was heated at 200 ° C. for 15 minutes with stirring. The obtained reaction solution (CuTe) was cooled to room temperature.
　得られた反応液に、塩化銀３５８．３ｍｇ、ＴＯＰを７．５ｍＬ、オレイルアミンを０．２５ｍＬ、ＤＤＴを０．６３ｍＬ添加し、２００℃まで昇温して３０分間加熱し、その後、室温まで冷却した。 To the obtained reaction solution, 358.3 mg of silver chloride, 7.5 mL of TOP, 0.25 mL of oleylamine and 0.63 mL of DDT were added, the temperature was raised to 200 ° C., heated for 30 minutes, and then cooled to room temperature. did.
　この溶液にトルエンとエタノールを加え沈殿を発生させ、遠心分離を施して沈殿を回収した。そして、その沈殿を再度１０ｍＬのＯＤＥに分散させた。 Toluene and ethanol were added to this solution to generate a precipitate, and centrifugation was performed to recover the precipitate. Then, the precipitate was dispersed again in 10 mL of ODE.
　この分散液に、塩化銀３５８．３ｍｇ、ＴＯＰを７．５ｍＬ、オレイルアミンを０．２５ｍＬ、ＤＤＴを０．６３ｍＬ添加し、２００℃まで昇温して３０分間加熱し、その後、室温まで冷却した。 358.3 mg of silver chloride, 7.5 mL of TOP, 0.25 mL of oleylamine, and 0.63 mL of DDT were added to this dispersion, the temperature was raised to 200 ° C., heated for 30 minutes, and then cooled to room temperature.
　この溶液にトルエンとエタノールを加え沈殿を発生させ、遠心分離を施して沈殿を回収した。この沈殿に対してトルエンを加えて分散液とした。 Toluene and ethanol were added to this solution to generate a precipitate, and centrifugation was performed to recover the precipitate. Toluene was added to this precipitate to prepare a dispersion.
　得られた分散液を、紫外可視吸収スペクトルで測定した。その結果、実施例１の図２の紫外可視近赤外吸収スペクトルの測定結果と同様に、１２００．０ｎｍ、および、１４００．０ｎｍ付近に吸収極大が得られた。 The obtained dispersion was measured by an ultraviolet-visible absorption spectrum. As a result, the absorption maximums were obtained in the vicinity of 1200.0 nm and 1400.0 nm, as in the measurement result of the ultraviolet-visible near-infrared absorption spectrum of FIG. 2 of Example 1.
　本実施例で得た量子ドットをＳＴＥＭで観察すると、実施例１の図３Ａ、図３Ｂと同様に、多数の量子ドットの平均粒径は６．４ｎｍであり、５ｎｍ以上８ｎｍ以下であることがわかった。また、実施例１の図４と同様に、９５％以上の量子ドットの各粒径が平均粒径±０．５ｎｍに含まれていた。すなわち、９５％以上の量子ドットの各粒径が平均粒径±６％に含まれており、多数の量子ドットの粒径を非常に均一に生成できたことがわかった。 When the quantum dots obtained in this example are observed by STEM, the average particle size of a large number of quantum dots is 6.4 nm, which is 5 nm or more and 8 nm or less, as in FIGS. 3A and 3B of Example 1. all right. Further, as in FIG. 4 of Example 1, each particle size of 95% or more of the quantum dots was included in the average particle size of ± 0.5 nm. That is, it was found that each particle size of 95% or more of the quantum dots was included in the average particle size of ± 6%, and the particle size of a large number of quantum dots could be generated very uniformly.
　また、本実施例で得た量子ドットのＸＲＤスペクトルには、実施例１の図５と同様のピークが観察されたことから、用いる試薬量を半分にしても、Ａｇ２Ｔｅ固溶体が生成することが確認された。 Further, since the same peak as in FIG. 5 of Example 1 was observed in the XRD spectrum of the quantum dots obtained in this example, even if the amount of the reagent used was halved, an Ag 2 Te solid solution was produced. Was confirmed.
　［実施例３］
　１００ｍＬ反応容器に、酢酸銅を９１．０ｍｇ、オクタデセン（ＯＤＥ）を１０．０ｍＬ、ドデカンチオール（ＤＤＴ）を０．６３ｍＬ、トリオクチルホスフィン（ＴＯＰ）を０．６３ｍＬ入れた。そして、不活性ガス（Ｎ２）雰囲気下で攪拌しながら、２００℃で１０分間加熱し、原料を溶解させた。 [Example 3]
In a 100 mL reaction vessel, 91.0 mg of copper acetate, 10.0 mL of octadecene (ODE), 0.63 mL of dodecanethiol (DDT), and 0.63 mL of trioctylphosphine (TOP) were placed. Then, the raw material was dissolved by heating at 200 ° C. for 10 minutes while stirring under the atmosphere of an inert gas (N 2).
　この溶液に、反応温度を保ったまま０．５Ｍのテルル－ＴＯＰ溶液を０．９ｍＬ、オレイルアミンを０．１３ｍＬ添加し、引き続き２００℃で１５分間、攪拌しつつ加熱した。得られた反応溶液（ＣｕＴｅ）を、室温まで冷却した。 To this solution, 0.9 mL of a 0.5 M tellurium-TOP solution and 0.13 mL of oleylamine were added while maintaining the reaction temperature, and the mixture was subsequently heated at 200 ° C. for 15 minutes with stirring. The obtained reaction solution (CuTe) was cooled to room temperature.
　得られた反応液に、塩化銀３５８．３ｍｇ、ＴＯＰを７．５ｍＬ、オレイルアミンを０．２５ｍＬ、ＤＤＴを０．６３ｍＬ添加し、２２０℃まで昇温して３０分間加熱し、その後、室温まで冷却した。 To the obtained reaction solution, 358.3 mg of silver chloride, 7.5 mL of TOP, 0.25 mL of oleylamine and 0.63 mL of DDT were added, the temperature was raised to 220 ° C., heated for 30 minutes, and then cooled to room temperature. did.
　この溶液にトルエンとエタノールを加え沈殿を発生させ、遠心分離を施して沈殿を回収した。そして、その沈殿を再度１０ｍＬのＯＤＥに分散させた。 Toluene and ethanol were added to this solution to generate a precipitate, and centrifugation was performed to recover the precipitate. Then, the precipitate was dispersed again in 10 mL of ODE.
　この分散液に、塩化銀３５８．３ｍｇ、ＴＯＰを７．５ｍＬ、オレイルアミンを０．２５ｍＬ、ＤＤＴを０．６３ｍＬ添加し、２２０℃まで昇温して３０分間加熱し、その後、室温まで冷却した。 358.3 mg of silver chloride, 7.5 mL of TOP, 0.25 mL of oleylamine, and 0.63 mL of DDT were added to this dispersion, the temperature was raised to 220 ° C., heated for 30 minutes, and then cooled to room temperature.
　この溶液にトルエンとエタノールを加え沈殿を発生させ、遠心分離を施して沈殿を回収した。この沈殿に対してトルエンを加えて分散液とした。 Toluene and ethanol were added to this solution to generate a precipitate, and centrifugation was performed to recover the precipitate. Toluene was added to this precipitate to prepare a dispersion.
　得られた分散液を、紫外可視吸収スペクトルで測定した。その結果、実施例１の図２の紫外可視近赤外吸収スペクトルの測定結果と同様に、１２００．０ｎｍ、および、１４００．０ｎｍ付近に吸収極大が得られた。 The obtained dispersion was measured by an ultraviolet-visible absorption spectrum. As a result, the absorption maximums were obtained in the vicinity of 1200.0 nm and 1400.0 nm, as in the measurement result of the ultraviolet-visible near-infrared absorption spectrum of FIG. 2 of Example 1.
　本実施例で得た量子ドットをＳＴＥＭで観察すると、実施例１の図３Ａ、図３Ｂと同様に、多数の量子ドットの平均粒径は６．４ｎｍであり、５ｎｍ以上８ｎｍ以下であることがわかった。また、実施例１の図４と同様に、９５％以上の量子ドットの各粒径が平均粒径±０．５ｎｍに含まれていた。すなわち、９５％以上の量子ドットの各粒径が平均粒径±６％に含まれており、多数の量子ドットの粒径を非常に均一に生成できたことがわかった。 When the quantum dots obtained in this example are observed by STEM, the average particle size of a large number of quantum dots is 6.4 nm, which is 5 nm or more and 8 nm or less, as in FIGS. 3A and 3B of Example 1. all right. Further, as in FIG. 4 of Example 1, each particle size of 95% or more of the quantum dots was included in the average particle size of ± 0.5 nm. That is, it was found that each particle size of 95% or more of the quantum dots was included in the average particle size of ± 6%, and the particle size of a large number of quantum dots could be generated very uniformly.
　また、本実施例で得た量子ドットのＸＲＤスペクトルには、実施例１の図５と同様のピークが観察されたことにより、カチオン交換反応の反応温度を２０℃上昇させてもＡｇ２Ｔｅ固溶体が生成することが確認された。 Further, since the same peak as in FIG. 5 of Example 1 was observed in the XRD spectrum of the quantum dots obtained in this example, even if the reaction temperature of the cation exchange reaction was raised by 20 ° C., the Ag 2 Te solid solution Was confirmed to be generated.
［比較例１］
　１００ｍＬ反応容器に、酢酸銅を９１．０ｍｇ、オクタデセン（ＯＤＥ）を１０．０ｍＬ、ドデカンチオール（ＤＤＴ）を０．６３ｍＬ、トリオクチルホスフィン（ＴＯＰ）を０．６３ｍＬ入れた。そして、不活性ガス（Ｎ２）雰囲気下で攪拌しながら、２００℃で１０分間加熱し、原料を溶解させた。 [Comparative Example 1]
In a 100 mL reaction vessel, 91.0 mg of copper acetate, 10.0 mL of octadecene (ODE), 0.63 mL of dodecanethiol (DDT), and 0.63 mL of trioctylphosphine (TOP) were placed. Then, the raw material was dissolved by heating at 200 ° C. for 10 minutes while stirring under the atmosphere of an inert gas (N 2).
　この溶液に、反応温度を保ったまま０．５Ｍのテルル－ＴＯＰ溶液を０．９ｍＬ、オレイルアミンを０．１３ｍＬ添加し、２００℃で１５分間、攪拌しつつ加熱した。得られた反応溶液（ＣｕＴｅ）を、室温まで冷却した。 To this solution, 0.9 mL of a 0.5 M tellurium-TOP solution and 0.13 mL of oleylamine were added while maintaining the reaction temperature, and the mixture was heated at 200 ° C. for 15 minutes with stirring. The obtained reaction solution (CuTe) was cooled to room temperature.
　得られた反応液に、硝酸銀４２４．７ｍｇ、ＴＯＰを７．５ｍＬ、オレイルアミンを０．２５ｍＬ、ＤＤＴを０．６３ｍＬ添加し、２００℃まで昇温して３０分間加熱し、その後、室温まで冷却した。 To the obtained reaction solution, 424.7 mg of silver nitrate, 7.5 mL of TOP, 0.25 mL of oleylamine, and 0.63 mL of DDT were added, the temperature was raised to 200 ° C., the mixture was heated for 30 minutes, and then cooled to room temperature. ..
　この溶液にトルエンとエタノールを加え沈殿を発生させ、遠心分離を施して沈殿を回収した。そして、その沈殿を再度１０ｍＬのＯＤＥに分散させた。 Toluene and ethanol were added to this solution to generate a precipitate, and centrifugation was performed to recover the precipitate. Then, the precipitate was dispersed again in 10 mL of ODE.
　この分散液に、硝酸銀４２４．７ｍｇ、ＴＯＰを７．５ｍＬ、オレイルアミンを０．２５ｍＬ、ＤＤＴを０．６３ｍＬ添加し、２００℃で３０分間加熱し、室温まで冷却した。 To this dispersion, 424.7 mg of silver nitrate, 7.5 mL of TOP, 0.25 mL of oleylamine, and 0.63 mL of DDT were added, heated at 200 ° C. for 30 minutes, and cooled to room temperature.
　この溶液にトルエンとエタノールを加え沈殿を発生させ、遠心分離を施して沈殿を回収した。この沈殿に対してトルエンを加えて分散液とした。 Toluene and ethanol were added to this solution to generate a precipitate, and centrifugation was performed to recover the precipitate. Toluene was added to this precipitate to prepare a dispersion.
　得られた分散液を、紫外可視吸収スペクトルで測定した。その結果、紫外可視近赤外吸収スペクトルには量子ドット由来の吸収は全く確認できなかった。ＳＴＥＭにおいても量子ドット粒子を確認することはできず、また、ＸＲＤにおいても回折ピークを確認することができなかった。これらの事実により、本合成法において、銀原料の選定が非常に重要であることが明らかとなった。すなわち実施例のように、銀原料としては塩化銀を用い、或いは、塩化銀と同様に、ハロゲン化物として１価の化合物（臭化銀（Ｉ）：ＡｇＢｒ、ヨウ化銀（Ｉ）：ＡｇＩなど）を用いることが好適である。 The obtained dispersion was measured by an ultraviolet-visible absorption spectrum. As a result, no absorption derived from quantum dots could be confirmed in the ultraviolet-visible near-infrared absorption spectrum. Quantum dot particles could not be confirmed in STEM, and diffraction peaks could not be confirmed in XRD. From these facts, it became clear that the selection of silver raw materials is very important in this synthetic method. That is, as in the examples, silver chloride is used as the silver raw material, or like silver chloride, a monovalent compound as a halide (silver bromide (I): AgBr, silver iodide (I): AgI, etc. ) Is preferable.
［比較例２］
　１００ｍＬ反応容器に、ジフェニルジテルリドを１２３．０ｍｇ、ドデカンチオール（ＤＤＴ）を１５．０ｍＬ、オクタデセン（ＯＤＥ）を１５．０ｍＬ入れた。そして、不活性ガス（Ｎ２）雰囲気下で攪拌しながら加熱し、原料を溶解させた。 [Comparative Example 2]
123.0 mg of diphenyl ditelluride, 15.0 mL of dodecanethiol (DDT), and 15.0 mL of octadecene (ODE) were placed in a 100 mL reaction vessel. Then, the raw material was dissolved by heating while stirring in an atmosphere of an inert gas (N 2).
　この溶液に、酢酸銀を２０４．０ｍｇ添加し、１８５℃で１０分間、攪拌しつつ加熱した。得られた反応溶液（Ａｇ２Ｔｅ）を、室温まで冷却した。 To this solution was added 204.0 mg of silver acetate and heated at 185 ° C. for 10 minutes with stirring. The obtained reaction solution (Ag 2 Te) was cooled to room temperature.
　得られた反応液に、エタノールを加え沈殿を発生させ、遠心分離を施して沈殿を回収した。そして、その沈殿にトルエンを加えて分散させ、Ａｇ２Ｔｅ量子ドットの分散溶液を得た。 Ethanol was added to the obtained reaction solution to generate a precipitate, which was centrifuged to recover the precipitate. Then, toluene was added to the precipitate and dispersed to obtain a dispersion solution of Ag 2 Te quantum dots.
　ＳＴＥＭを測定したところ、多数の量子ドットの平均粒径は２．４～２．７ｎｍであり、平均粒径が５ｎｍ以下になることがわかった。 When STEM was measured, it was found that the average particle size of many quantum dots was 2.4 to 2.7 nm, and the average particle size was 5 nm or less.
　以上のように、実施例１～３によれば、近赤外領域に吸収波長を有する、非常に均一な粒子径を有する量子ドットが効率よく合成可能であるとわかった。 As described above, according to Examples 1 to 3, it was found that quantum dots having an absorption wavelength in the near infrared region and having a very uniform particle size can be efficiently synthesized.
　本発明によれば、近赤外領域に吸収波長を有し、かつ、非常に均一な粒子径を有する銀カルコゲニド量子ドットを、大気下で取り扱うにあたって高い反応性を示す反応剤を用いず、かつ有毒性の規制対象重金属を含む中間体を経ずに安定して合成することができる。そして本発明の量子ドットを、光通信装置等に適用することで、装置において優れたアイセーフ近赤外光吸収特性を得ることができる。特に、本発明の量子ドットを、赤外線センサのアイセーフ近赤外光吸収層の量子ドット層に適用することが可能である。 According to the present invention, silver chalcogenide quantum dots having an absorption wavelength in the near infrared region and having a very uniform particle size can be handled in the atmosphere without using a reactant showing high reactivity. It can be stably synthesized without passing through intermediates containing toxic regulated heavy metals. Then, by applying the quantum dots of the present invention to an optical communication device or the like, excellent eye-safe near-infrared light absorption characteristics can be obtained in the device. In particular, the quantum dots of the present invention can be applied to the quantum dot layer of the eye-safe near-infrared light absorption layer of the infrared sensor.
　本出願は、２０１９年１０月９日出願の特願２０１９－１８６２７８に基づく。この内容は全てここに含めておく。
 
 
 
 
 
                                         This application is based on Japanese Patent Application No. 2019-186278 filed on October 9, 2019. All this content is included here.

Claims (8)

  1. 　銀とカルコゲンとを含有するＡｇ２Ｅ（Ｅは、テルル、セレン、或いは、硫黄の少なくともいずれか１種）で表されるナノクリスタルであり、吸収波長が、１３００～１５００ｎｍの近赤外領域の範囲であることを特徴とする量子ドット。 It is a nanocrystal represented by Ag 2 E (E is at least one of tellurium, selenium, or sulfur) containing silver and interchalcogen, and has an absorption wavelength in the near infrared region of 1300 to 1500 nm. A quantum dot characterized by being a range.
  2. 　平均粒径が、５．０ｎｍ以上８．０ｎｍ以下であることを特徴とする請求項１に記載の量子ドット。 The quantum dot according to claim 1, wherein the average particle size is 5.0 nm or more and 8.0 nm or less.
  3. 　前記量子ドットの表面が、配位子で覆われていることを特徴とする請求項１又は請求項２に記載の量子ドット。 The quantum dot according to claim 1 or 2, wherein the surface of the quantum dot is covered with a ligand.
  4. 　前記配位子は、ホスフィン系、脂肪族チオール系、脂肪族アミン系、及び、脂肪族カルボン酸系の少なくともいずれか１種または２種から選択されることを特徴とする請求項３に記載の量子ドット。 The third aspect of claim 3, wherein the ligand is selected from at least one or two of phosphine-based, aliphatic thiol-based, aliphatic amine-based, and aliphatic carboxylic acid-based. Quantum dots.
  5. 　銅原料とカルコゲン原料とから調整されるＣｕＥ（Ｅは、テルル、セレン、或いは、硫黄の少なくともいずれか１種）中間体を得る工程、
    　前記ＣｕＥ中間体に対して、Ａｇ原料を用いたカチオン交換反応を経てＡｇ２Ｅ（Ｅは、テルル、セレン、或いは、硫黄の少なくともいずれか１種）で表される。量子ドットを合成する工程、
    　を有することを特徴とする量子ドットの製造方法。     A step of obtaining a CuE (E is at least one of tellurium, selenium, or sulfur) intermediate prepared from a copper raw material and a chalcogen raw material.
    To the CuE intermediate, via a cation exchange reaction using Ag material Ag 2 E (E is tellurium, selenium, or at least one kind of sulfur) represented by. The process of synthesizing quantum dots,
    A method for producing quantum dots, which comprises.
  6. 　ホスフィンを含む溶媒中で、前記量子ドットを合成することを特徴とする請求項５に記載の量子ドットの製造方法。 The method for producing quantum dots according to claim 5, wherein the quantum dots are synthesized in a solvent containing phosphine.
  7. 　前記ＣｕＥ中間体を、１２０℃以上３００℃以下で反応させて得た後、１２０℃以上３００℃以下でＡｇ原料を用いたカチオン交換反応を行うことを特徴とする請求項５又は請求項６に記載の量子ドットの製造方法。 According to claim 5 or 6, the CuE intermediate is obtained by reacting at 120 ° C. or higher and 300 ° C. or lower, and then a cation exchange reaction using an Ag raw material is carried out at 120 ° C. or higher and 300 ° C. or lower. The method for manufacturing quantum dots described.
  8. 　カドミウム、水銀、及び、鉛に代表される規制対象重金属と、金属アミド、及び、有機リチウム化合物に代表される大気下で高い反応性を示す反応剤と、を中間体として含むことなく、前記量子ドットを合成することを特徴とする請求項５から請求項７のいずれかに記載の量子ドットの製造方法。 The quantum is not contained as an intermediate between a regulated heavy metal such as cadmium, mercury and lead, and a metal amide and a reactant having high reactivity in the atmosphere such as an organolithium compound. The method for producing a quantum dot according to any one of claims 5 to 7, wherein the dots are synthesized.
PCT/JP2020/037980 2019-10-09 2020-10-07 Quantum dot and method for producing same WO2021070858A1 (en)

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