A quantum dot and its preparation method and application

Abstract

The present invention relates to quantum dots, their preparation method, and applications. The preparation method comprises the following steps: mixing an indium salt, a first zinc source, a copper source, and a manganese source, and then sequentially reacting the mixture with a multidentate ligand, a phosphorus source, a selenium source, and / or a second zinc source, a sulfur source, and / or a third zinc source to produce the quantum dots. The preparation method is cadmium-free, has low biotoxicity, and is environmentally friendly. The quantum dots produced by this method exhibit excellent optical properties and stability in quantum dot glue.

Description

Technical Field

[0001] The present invention relates to the technical field of quantum dot materials, and in particular to a quantum dot and a preparation method and application thereof. Background Art

[0002] Quantum dots (QDs), a novel semiconductor material, have attracted significant attention for their tunable band gap and excellent photoluminescence properties, and are widely used in biomedicine, cell imaging, and other fields. In recent years, cadmium-based QDs have gained popularity in display and lighting applications due to their excellent optical properties. However, the biotoxicity of the element Cd has limited its application in immunoassays, biomedicine, and other fields, posing significant risks to both the environment and humans.

[0003] CN111434750A discloses cadmium-free quantum dots, a preparation method, and a cadmium-free quantum dot composition. The cadmium-free quantum dots disclosed herein include a quantum dot core comprising a chemically bonded group III element, a group V element, and a group VI element, wherein the group III element serves as a cation and the group V and group VI elements serve as anions. The introduction of a group VI anion into the existing group III-V quantum dot core helps reduce the full width at half maximum (FWHM) of the quantum dot core and improves quantum efficiency.

[0004] CN113637469A discloses a cadmium-free quantum dot and a preparation method thereof. The method comprises: mixing a phosphorus precursor, a fatty acid indium precursor, and a non-coordinating solvent at a first temperature, and heating the mixture to a second temperature for reaction to obtain an indium phosphide quantum dot core; adding an indium halide precursor dropwise into the reaction system of the indium phosphide quantum dot core, and performing surface treatment on the indium phosphide quantum dot core to obtain a cadmium-free quantum dot. The disclosed method can reduce surface defects of the cadmium-free quantum dots, significantly improve the morphology, luminous efficiency, and stability of the indium phosphide quantum dots, and the cadmium-free indium phosphide quantum dots prepared in a simple and low-cost manner have a narrow half-peak width and a high fluorescence yield.

[0005] Cadmium-free InP quantum dots have become a research hotspot. They possess comparable optical properties to cadmium-based quantum dots, but currently, there are significant gaps between these and cadmium-based quantum dots in terms of quantum yield, half-width (FWHM), and stability. Quantum dots combined with glue have long been a research focus, and while combining the two has broadened the application of quantum dots, this system still faces challenges such as stability and solubility.

[0006] In summary, it is crucial to develop a method for preparing quantum dots that can solve the above technical problems. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a quantum dot and its preparation method and application, wherein the preparation method is a cadmium-free, low-biotoxic and environmentally friendly process; the quantum dots obtained by the preparation method have excellent optical properties and stability in quantum dot glue.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for preparing quantum dots, the method comprising the following steps:

[0010] The indium salt, the first zinc source, the copper source and the manganese source are mixed, and then reacted with the multidentate ligand, the phosphorus source, the selenium source and / or the second zinc source, the sulfur source and / or the third zinc source in sequence to obtain the quantum dots.

[0011] In the present invention, the preparation method uses a multidentate ligand with a large number of side chains, which effectively improves the solubility and dispersibility of the formed quantum dots in the quantum dot glue. Moreover, when the multidentate ligand is bonded and modified on the surface of the quantum dot, it is equivalent to the effect of multiple monodentate ligands. Therefore, when the entire surface of the quantum dot is coated and modified, relatively few multidentate ligands are required, reducing the density of surface organic chains. Since organic matter is an insulator, it will hinder the transmission efficiency of holes and electrons in the device. Therefore, when the use of organic matter is reduced, the efficiency of the device can be improved.

[0012] In the preparation method of the present invention, the use of copper source, manganese source, phosphorus source, selenium source, etc. forms a ZnCuMnSe transition layer, which compensates for the lattice mismatch between the core layer and the shell layer of the quantum dot, reduces surface defects, and can make the quantum dot material structure stable. 2+ It can emit light with a wavelength of 600nm, broadening the application of quantum dots in the field of lighting.

[0013] Therefore, the preparation method is a cadmium-free, low-biotoxic and environmentally friendly process; the quantum dots obtained by the preparation method have excellent optical properties and stability in quantum dot glue.

[0014] Preferably, the multidentate ligand comprises any one of ethylenediaminetetraacetic acid, a salt of ethylenediaminetetraacetic acid, triethanolamine, a salt of triethanolamine, nitrilotriacetic acid, a salt of nitrilotriacetic acid, diethylenetriamine, a salt of diethylenetriamine or a dialkyldimethyl complex quaternary ammonium salt, or a combination of at least two thereof. Typical but non-limiting combinations include: a combination of ethylenediaminetetraacetic acid and a salt of ethylenediaminetetraacetic acid, triethanolamine, a salt of triethanolamine, nitrilotriacetic acid, a salt of nitrilotriacetic acid, a combination of triethanolamine, a salt of triethanolamine, nitrilotriacetic acid, a salt of nitrilotriacetic acid, diethylenetriamine, a salt of diethylenetriamine and a dialkyldimethyl complex quaternary ammonium salt, and more preferably a combination of ethylenediaminetetraacetic acid, a salt of ethylenediaminetetraacetic acid, a salt of nitrilotriacetic acid or a salt of diethylenetriamine or a combination of at least two thereof.

[0015] In the present invention, the multidentate ligand is further preferably any one of ethylenediaminetetraacetic acid, salts of ethylenediaminetetraacetic acid, salts of nitrilotriacetic acid, and salts of diethylenetriamine, or a combination of at least two thereof; the reason is that the multidentate ligand is more likely to provide an amine-rich environment, modify the surface of quantum dots, and serve as a coordination solvent, thereby making the performance of the synthesized quantum dots more stable and improving the lifespan for subsequent device applications.

[0016] Preferably, the preparation method further comprises a monodentate ligand, including but not limited to oleylamine.

[0017] In the present invention, the multidentate ligand can also be used in combination with a monodentate ligand.

[0018] Preferably, the indium salt includes any one of indium chloride, indium bromide, indium iodide, indium acetate or indium sulfate, or a combination of at least two thereof, wherein typical but non-limiting combinations include: a combination of indium chloride and indium bromide, a combination of indium iodide, indium acetate and indium sulfate, a combination of indium chloride, indium bromide, indium iodide, indium acetate and indium sulfate, and the like.

[0019] Preferably, the first zinc source, the second zinc source and the third zinc source each independently comprise a zinc-containing compound.

[0020] Preferably, the zinc-containing compound includes any one of diethyl zinc, zinc stearate, zinc sulfate, zinc chloride or zinc bromide, or a combination of at least two thereof, wherein typical but non-limiting combinations include: a combination of diethyl zinc and zinc stearate, a combination of zinc sulfate, zinc chloride and zinc bromide, a combination of diethyl zinc, zinc stearate, zinc sulfate, zinc chloride and zinc bromide, and the like.

[0021] Preferably, the second zinc source and the third zinc source each independently further comprise a solvent.

[0022] Preferably, in the second zinc source and the third zinc source, the solvent comprises octyldecanoate (ODE) and / or octadecene, more preferably ODE.

[0023] Preferably, the copper source comprises a copper salt and a ligand.

[0024] Preferably, the copper salt includes any one or a combination of at least two of copper decanoate, copper dodecanoate, copper hexadecanoate, copper oleate, copper isopropoxide or copper halide, wherein typical but non-limiting combinations include: a combination of copper decanoate and copper dodecanoate, a combination of copper oleate, copper isopropoxide and copper halide, a combination of copper decanoate, copper dodecanoate, copper hexadecanoate, copper oleate, copper isopropoxide and copper halide, and the like.

[0025] Preferably, the manganese source comprises a manganese-containing compound and a ligand.

[0026] Preferably, the manganese-containing compound includes any one of manganese isopropoxide, manganese-containing decanoate, manganese-containing dodecanoate, manganese-containing hexadecanoate, manganese-containing oleate, manganese isopropoxide or manganese halide, or a combination of at least two thereof. Typical but non-limiting combinations include: a combination of manganese isopropoxide and manganese-containing decanoate, a combination of manganese-containing hexadecanoate, manganese oleate, manganese isopropoxide and manganese halide, a combination of manganese isopropoxide, manganese-containing decanoate, manganese-containing dodecanoate, manganese-containing hexadecanoate, manganese oleate, manganese isopropoxide and manganese halide, and the like.

[0027] Preferably, the phosphorus source comprises a phosphorus-containing compound and a ligand.

[0028] Preferably, the phosphorus-containing compound comprises tris(trimethylsilyl)phosphine and / or tris(dimethyl)amidophosphine.

[0029] Preferably, the ligands each independently include any one or a combination of at least two of ethylenediaminetetraacetic acid, triethanolamine, diethylenetriamine, nitrilotriacetic acid and related salts thereof, wherein typical but non-limiting combinations include: a combination of ethylenediaminetetraacetic acid and triethanolamine, a combination of ethylenetriamine and nitrilotriacetic acid, a combination of ethylenediaminetetraacetic acid, triethanolamine, diethylenetriamine, nitrilotriacetic acid and related salts thereof, etc.

[0030] Preferably, the selenium source comprises a selenium-containing substance and a solvent.

[0031] Preferably, the selenium-containing substance is elemental selenium.

[0032] Preferably, in the selenium source, the solvent includes any one of trioctylphosphine (TOP), tri-n-octylphosphine oxide (TOPO), tributylphosphine (TBP) or trihexylphosphine oxide, or a combination of at least two thereof, wherein typical but non-limiting combinations include: a combination of trioctylphosphine and tri-n-octylphosphine oxide, a combination of tributylphosphine and trihexylphosphine oxide, a combination of trioctylphosphine, tri-n-octylphosphine oxide, tributylphosphine and trihexylphosphine oxide, and the like.

[0033] Preferably, the sulfur source comprises dodecanethiol and / or octadecanethiol.

[0034] Preferably, based on 100 parts by total mass of the indium salt, the mass fraction of the first zinc source is 300-500 parts, for example, 350 parts, 400 parts, 450 parts, etc., more preferably 400 parts.

[0035] Preferably, based on 100 parts by total mass of the indium salt, the total mass of the copper source and the manganese source is 5-20 parts, for example, 5 parts, 10 parts, 15 parts, or 20 parts.

[0036] Preferably, in the mixture of the copper source and the manganese source, the concentrations of copper ions and manganese elements are independently 5-100 mmol / L, for example, 10 mmol / L, 20 mmol / L, 30 mmol / L, 40 mmol / L, 50 mmol / L, 60 mmol / L, 70 mmol / L, 80 mmol / L, 90 mmol / L, etc.

[0037] Preferably, based on 100 parts of the total mass of the indium salt, the mass fraction of the multidentate ligand is 200-300 parts, for example, 200 parts, 210 parts, 220 parts, 230 parts, 240 parts, 250 parts, 260 parts, 270 parts, 280 parts, 290 parts, or 300 parts.

[0038] Preferably, based on 100 parts by total mass of the indium salt, the mass fraction of the phosphorus source is 80-120 parts, for example, 80 parts, 90 parts, 100 parts, 110 parts, or 120 parts.

[0039] Preferably, in the phosphorus source, the volume ratio of the phosphorus-containing compound to the ligand is (1-5):10, wherein 1-5 can be 2, 3, 4, etc.

[0040] Preferably, the mass concentration of the zinc-containing compound in the second zinc source and the third zinc source is independently 0.1-0.5 g / mL, such as 0.2 g / mL, 0.3 g / mL, 0.4 g / mL, etc.

[0041] Preferably, in the selenium source, the mass concentration of the selenium-containing substance is 50-90 g / L, for example, 55 g / L, 60 g / L, 65 g / L, 70 g / L, 75 g / L, 80 g / L, 85 g / L, etc.

[0042] Preferably, when the indium salt, the first zinc source, the copper source and the manganese source are mixed, the indium salt and the first zinc source are first mixed, and then further mixed with the mixture of the copper source and the manganese source.

[0043] Preferably, the indium salt, the first zinc source, the copper source and the manganese source are mixed, and then mixed with the multidentate ligand, and then vacuuming and heating are performed for the first time.

[0044] Preferably, the first heating is to 80-100°C, such as 85°C, 90°C, 95°C, etc.

[0045] Preferably, the first heating is followed by passing a protective gas and a second heating.

[0046] Preferably, the second heating is to 160-220°C, such as 170°C, 180°C, 190°C, 200°C, 210°C, etc.

[0047] Preferably, after the second heating, a phosphorus source is added to the system to carry out the first reaction.

[0048] Preferably, the first reaction time is 20-40 min, such as 25 min, 30 min, 35 min, etc.

[0049] Preferably, after the first reaction, a selenium source and / or a second zinc source is added to the system, and the system is heated for a third time under a protective atmosphere.

[0050] Preferably, the third heating is to 280-320°C, such as 290°C, 300°C, 310°C, etc.

[0051] Preferably, after the third heating, a second reaction is carried out.

[0052] Preferably, the temperature of the second reaction is 30-60 min, such as 35 min, 40 min, 45 min, 50 min, 55 min, etc.

[0053] Preferably, the second reaction is followed by cooling.

[0054] Preferably, the cooling is to 60-85°C, such as 65°C, 0°C, 75°C, 80°C, etc.

[0055] Preferably, the cooling further includes purification.

[0056] In the present invention, the purification is to remove excess impurities and zinc sources that may affect subsequent experiments. The purification method includes mixing the system with a centrifugal solvent such as n-hexane and / or ethanol and centrifuging to allow the second zinc source and impurities to settle.

[0057] Preferably, the purification is performed by evacuating, passing protective gas and heating for the fourth time.

[0058] Preferably, the fourth heating is to 180-220°C, such as 190°C, 200°C, 210°C, etc.

[0059] Preferably, after the fourth heating, a sulfur source and / or a third zinc source is added to the system and the fifth heating is performed.

[0060] Preferably, the fifth heating is performed to a temperature of 280-320°C, such as 290°C, 300°C, 310°C, etc.

[0061] Preferably, after the fifth heating, a third reaction is performed.

[0062] Preferably, the third reaction time is 30-60 min, such as 35 min, 40 min, 45 min, 50 min, 55 min, etc.

[0063] Preferably, the third reaction further includes purification.

[0064] In the present invention, the purification is to remove excess impurities and the third zinc source that may affect subsequent experiments. The purification method includes mixing the system with a centrifugal solvent such as n-hexane and / or ethanol and centrifuging.

[0065] As a preferred technical solution, the preparation method comprises the following steps:

[0066] (1) mixing an indium salt, a first zinc source, a copper source, and a manganese source, and then mixing with the multidentate ligand, evacuating the mixture, and heating the mixture to 80-100° C. for the first time until all water and oxygen are exhausted, and then introducing a protective gas;

[0067] (2) After introducing protective gas, heat to 160-220°C for the second time, add a phosphorus source to the system, and keep warm for 20-40 minutes to complete the first reaction;

[0068] (3) After the first reaction, a selenium source and / or a second zinc source is added to the system, and the system is heated to 280-320° C. for a third time under a protective atmosphere and kept warm for 30-60 minutes to complete the second reaction;

[0069] (4) After the second reaction, the mixture was cooled to 60-85°C, purified, evacuated, and heated to 180-220°C for the fourth time.

[0070] (5) After the fourth heating, a sulfur source and / or a third zinc source is added to the system, and the system is heated to 280-320° C. for a fifth time, kept warm for 30-60 minutes, to complete the third reaction, and purified to obtain the quantum dots.

[0071] In a second aspect, the present invention provides a quantum dot, which is obtained by the preparation method described in the first aspect;

[0072] The quantum dots include a core layer, a transition layer and a shell layer;

[0073] The core layer includes indium phosphide;

[0074] The transition layer includes zinc, copper, manganese and selenium;

[0075] The shell layer includes zinc sulfide.

[0076] In a third aspect, the present invention provides a quantum dot glue, comprising the quantum dots described in the second aspect and a diluent monomer.

[0077] In the present invention, when the quantum dots of the structure are used in combination with UV glue, since the ligand is a multi-tooth chain, it has a good chelation effect with the metal particles, resulting in a more stable surface structure, which is not easy to fall off in the quantum dot glue and can be more stable and dispersed and dissolved in the glue for a long time.

[0078] Preferably, the diluent monomer comprises an acrylamide reactive diluent (ACMO) and / or isobornyl acrylate (IBOA).

[0079] Preferably, the quantum dots include red quantum dots and green quantum dots in a mass ratio of 1:(5-12), wherein 5-12 can be 6, 7, 8, 9, 10, 11, etc.

[0080] Preferably, the solid content of the quantum dots in the diluent monomer is 20%-40%, for example, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, etc.

[0081] Preferably, based on the total mass of the quantum dot glue being 100%, the mass percentage of the quantum dots is 0.5%-2%, for example, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, etc.

[0082] Preferably, the quantum dot glue further comprises oligomers, photoinitiators, light diffusers or other additives.

[0083] Compared with the prior art, the present invention has the following beneficial effects:

[0084] (1) In the present invention, the preparation method is a cadmium-free, low-biotoxic and environmentally friendly process; the quantum dots obtained by the preparation method have excellent optical properties and stability in quantum dot glue.

[0085] (2) In the present invention, the fluorescence emission peak range of the quantum dots obtained by the preparation method is between 510-560 nm, the quantum yield is above 90%, the half-peak width is below 38 nm, the complete dissolution time in the quantum dot glue is within 10 min, the quantum dot glue is clear, and the quantum dots will not settle in the quantum dot glue. DETAILED DESCRIPTION

[0086] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0087] Example 1

[0088] This embodiment provides a method for preparing quantum dots, which includes the following steps:

[0089] (1) Metallic manganese and copper precursors: manganese isopropoxide, copper chloride and ethylenediaminetetraacetic acid are mixed to form a manganese and copper solution, and the manganese concentration is maintained within the range of 10 mmol / L and the copper concentration is maintained within the range of 10 mmol / L to obtain the metallic manganese and copper precursors;

[0090] Second zinc source and third zinc source: In a 250 mL three-necked flask, add 30 g of zinc stearate and 120 mL of ODE, introduce nitrogen, stir, and heat to 120°C to completely mix the zinc stearate and ODE to form a suspension without sedimentation, thereby obtaining the second zinc source and the third zinc source;

[0091] Selenium source: 7.896 g of selenium powder and 100 mL of TOP were added to a 250 mL three-necked flask, nitrogen was introduced, and the mixture was stirred and heated to 120°C to completely disperse the selenium powder to obtain the selenium source;

[0092] Phosphorus source: In a 50 mL three-necked flask, add 4.5 mL of tris(dimethylamino)phosphine [(DMA)3P] and 10 mL of ethylenediaminetetraacetic acid and mix thoroughly to obtain the phosphorus source;

[0093] (2) 120 mg of indium bromide and 490 mg of zinc bromide were added to a 50 mL three-necked flask, and then 10.0 mL of metallic manganese and copper precursors were added thereto, and then mixed with 20 mL of a mixture of oleylamine and ethylenediaminetetraacetic acid with a volume ratio of 1:2, and the volume ratio was evacuated for 30 minutes, maintaining the vacuum degree at -0.05 to -0.1 MPa, and heated to 100 ° C for the first time until all water and oxygen were exhausted, and then protective gas Ar was introduced;

[0094] (3) After introducing protective gas, heat to 200°C for the second time, inject 1.45 mL of phosphorus source into the system, stir, and keep warm for 20 minutes to complete the first reaction;

[0095] (4) After the first reaction, 6.6 mL of selenium source and 6 mL of the second zinc source were quickly injected into the system, and the system was heated to 300 °C for the third time under a protective atmosphere and kept at this temperature for 45 min to complete the second reaction;

[0096] (5) After the second reaction, the mixture was cooled to 80°C, and n-hexane was added and centrifuged at 10,000 rpm to allow the zinc stearate to settle. The mixture was then evacuated, filled with protective gas Ar, and heated to 200°C for the fourth time.

[0097] (6) After the fourth heating, 1.5 mL of dodecanethiol and 6 mL of the third zinc source were quickly injected into the system, and the system was heated to 300 ° C for the fifth time and kept warm for 45 minutes to complete the third reaction. The system was cooled to 80 ° C, and n-hexane was added and centrifuged at 10,000 rpm to precipitate the zinc stearate. Then, n-hexane and anhydrous ethanol were added at a volume ratio of 1:1, and centrifuged at 10,000 rpm to precipitate the InP / ZnCuMnSe / ZnS nanocrystals. The system was dried with nitrogen to obtain the quantum dots (InP / ZnCuMnSe / ZnS).

[0098] Example 2

[0099] This embodiment provides a method for preparing quantum dots, which includes the following steps:

[0100] (1) Metallic manganese and copper precursors: manganese sulfate, copper chloride and ethylenediaminetetraacetic acid are mixed to form a manganese and copper solution, with the manganese concentration being 15 mmol / L and the copper concentration being 15 mmol / L, to obtain the metallic manganese and copper precursors;

[0101] Second zinc source and third zinc source: In a 250 mL three-necked flask, add 30 g of zinc stearate and 120 mL of ODE, introduce nitrogen, stir, and heat to 120°C to completely mix the zinc stearate and ODE to form a suspension without sedimentation, thereby obtaining the second zinc source and the third zinc source;

[0102] Selenium source: 7.896g of selenium powder and 100mL of TOP were added to a 250mL three-necked flask, nitrogen was introduced, and the mixture was stirred and heated to 120°C to completely disperse the selenium powder to obtain the selenium source;

[0103] Phosphorus source: In a 50 mL three-necked flask, add 4.5 mL of tris(dimethylamino)phosphine [(DMA)3P] and 10 mL of ethylenediaminetetraacetic acid and mix thoroughly to obtain the phosphorus source;

[0104] (2) 150 mg of indium acetate and 500 mg of diethyl zinc were added to a 50 mL three-necked flask, and then 10.0 mL of metal manganese and copper precursors were added thereto. The mixture was then mixed with 30 mL of ethylenediaminetetraacetic acid, and the mixture was evacuated for 30 min, maintaining the vacuum degree at -0.05 to -0.1 MPa. The mixture was heated to 80°C for the first time until all water and oxygen were expelled, and then protective gas Ar was introduced.

[0105] (3) After introducing protective gas, heat to 160°C for the second time, inject 1.45 mL of phosphorus source into the system, stir, and keep warm for 40 minutes to complete the first reaction;

[0106] (4) After the first reaction, 6.6 mL of selenium source and 6 mL of the second zinc source were quickly injected into the system, and the system was heated to 280 °C for the third time under a protective atmosphere and kept warm for 60 min to complete the second reaction;

[0107] (5) After the second reaction, the mixture was cooled to 60°C, and n-hexane was added and centrifuged at 10,000 rpm to allow the zinc stearate to settle. The mixture was then evacuated, and protective gas Ar was passed through the mixture, and the mixture was heated to 180°C for the fourth time.

[0108] (6) After the fourth heating, 1.5 mL of dodecanethiol and 6 mL of the third zinc source were quickly injected into the system, and the system was heated to 280° C. for the fifth time and kept warm for 30 min to complete the third reaction. The system was cooled to 60° C., and n-hexane was added and centrifuged at 10,000 rpm to precipitate the zinc stearate. Then, n-hexane and anhydrous ethanol were added at a volume ratio of 1:1, and centrifuged at 10,000 rpm to precipitate the InP / ZnCuMnSe / ZnS nanocrystals. The system was dried with nitrogen to obtain the quantum dots (InP / ZnCuMnSe / ZnS).

[0109] Example 3

[0110] This embodiment provides a method for preparing quantum dots, which includes the following steps:

[0111] (1) Metallic manganese and copper precursors: manganese isopropoxide, copper chloride and ethylenediaminetetraacetic acid are mixed to form a manganese and copper solution, and the manganese concentration is maintained within the range of 30 mmol / L and the copper concentration is maintained within the range of 30 mmol / L to obtain the metallic manganese and copper precursors;

[0112] Second zinc source and third zinc source: In a 250 mL three-necked flask, add 30 g of zinc stearate and 120 mL of ODE, introduce nitrogen, stir, and heat to 120°C to completely mix the zinc stearate and ODE to form a suspension without sedimentation, thereby obtaining the second zinc source and the third zinc source;

[0113] Selenium source: 7.896g of selenium powder and 100mL of TOP were added to a 250mL three-necked flask, nitrogen was introduced, and the mixture was stirred and heated to 120°C to completely disperse the selenium powder to obtain the selenium source;

[0114] Phosphorus source: In a 50 mL three-necked flask, add 4.5 mL of tris(dimethylamino)phosphine [(DMA)3P] and 10 mL of ethylenediaminetetraacetic acid and mix thoroughly to obtain the phosphorus source;

[0115] (2) 120 g of indium sulfate and 490 g of zinc sulfate were added to a 50 mL three-necked flask, and then 10.0 mL of metal manganese and copper precursors were added thereto. The mixture was then mixed with 35 mL of nitrilotriacetic acid, and the mixture was evacuated for 30 min, maintaining the vacuum degree at -0.05 to -0.1 MPa. The mixture was heated to 90°C for the first time until all water and oxygen were expelled, and then protective gas Ar was introduced.

[0116] (3) After introducing protective gas, heat to 220°C for the second time, inject 1.45 mL of phosphorus source into the system, stir, and keep warm for 30 minutes to complete the first reaction;

[0117] (4) After the first reaction, 6.6 mL of selenium source and 6 mL of the second zinc source were quickly injected into the system, and the system was heated to 320 °C for the third time under a protective atmosphere and kept warm for 30 min to complete the second reaction;

[0118] (5) After the second reaction, the mixture was cooled to 70°C, and n-hexane was added and centrifuged at 10,000 rpm to allow the zinc stearate to settle. The mixture was then evacuated, and a protective gas Ar was passed through the mixture, and the mixture was heated to 220°C for the fourth time.

[0119] (6) After the fourth heating, 1.5 mL of dodecanethiol and 6 mL of the third zinc source were quickly injected into the system, and the system was heated to 320° C. for the fifth time and kept warm for 60 min to complete the third reaction. The system was cooled to 70° C., and n-hexane was added and centrifuged at 10,000 rpm to precipitate the zinc stearate. Then, n-hexane and anhydrous ethanol were added at a volume ratio of 1:1, and the system was centrifuged at 10,000 rpm to precipitate the InP / ZnCuMnSe / ZnS nanocrystals. The system was dried with nitrogen to obtain the quantum dots (InP / ZnCuMnSe / ZnS).

[0120] Example 4

[0121] The difference between this embodiment and embodiment 1 is that the multidentate ligand is replaced by 2,3-butanedione dioxime of equal mass, and the rest is the same as embodiment 1.

[0122] Comparative Example 1

[0123] The difference between this comparative example and Example 1 is that the multidentate ligand is replaced by a monodentate ligand (oleylamine) of equal mass, and the rest are the same as Example 1.

[0124] Comparative Example 2

[0125] The difference between this comparative example and Example 1 is that copper salt is not included, and the rest is the same as Example 1.

[0126] Comparative Example 3

[0127] The difference between this comparative example and Example 1 is that the manganese-containing compound is not included, and the rest is the same as Example 1.

[0128] Performance Testing

[0129] The quantum dots described in Examples 1-4 and Comparative Examples 1-3 were tested as follows:

[0130] (1) Fluorescence emission peak range: tested using absolute quantum yield spectrometer C11347;

[0131] (2) Quantum yield: tested using the absolute quantum yield spectrometer C11347;

[0132] (3) Half-peak width: measured using the absolute quantum yield spectrometer C11347;

[0133] (4) Stability of quantum dot glue: After double 85 and 1000 hours stability test;

[0134] Among them, quantum dot glue: the obtained red and green InP / ZnCuMnSe / ZnS are mixed with IBOA dilution monomers respectively with a mass fraction of 30%. After configuration, they are matched according to the red-green ratio of 1:10. The total mass of the above-mentioned mixed liquid is 100 parts, and then 125 parts by weight of oligomer (named special modified polyurethane acrylic resin, purchased from Nanxiong Dinghao Photochemical Technology Co., Ltd.), 5 parts by weight of photoinitiator (named trimethylbenzoyl-diphenylphosphine oxide, purchased from Shanghai Yinchang New Materials Co., Ltd.), 0.5 parts by weight of auxiliary agent (named defoamer / leveling agent, purchased from Walker VOL, Germany) and 4.5 parts by weight of light diffuser (named non-alkaline hindered amine radical scavenger, purchased from Walker VOK, Germany) are added to configure quantum dot glue.

[0135] The test results are summarized in Table 1.

[0136] Table 1

[0137]

[0138] Analysis of the data in Table 1 shows that, in the present invention, the fluorescence emission peak range of the quantum dots obtained by the preparation method is between 510-560 nm, the quantum yield is above 95%, the half-peak width is below 38 nm, the dissolution time in the quantum dot glue is within 15 min 36 s, the quantum dot glue is clear, and the quantum dots do not settle in the quantum dot glue; in the present invention, the preparation method is a cadmium-free, low biotoxicity and environmentally friendly process; the quantum dots obtained by the preparation method have excellent optical properties and stability in the quantum dot glue.

[0139] Analysis of comparative examples 1-3 and embodiment 1 shows that the performance of comparative examples 1-3 is not as good as that of embodiment 1, which proves that the quantum dots prepared by the method of the present invention have better performance.

[0140] Analysis of Example 4 and Example 1 shows that the performance of Example 4 is not as good as that of Example 1, which proves that the quantum dots formed by the preferred multidentate ligand have better performance.

[0141] While the present invention is described through the above-described embodiments, the present invention is not limited to the above-described detailed methods, nor does it necessarily rely on the above-described detailed methods for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent substitutions for raw materials in the products of the present invention, addition of auxiliary ingredients, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing quantum dots, characterized in that: The preparation method comprises the following steps: (1) After mixing the indium salt, the first zinc source, the copper source and the manganese source, the mixture is mixed with the multidentate ligand, vacuumed, and heated to 80-100°C for the first time until all water and oxygen are exhausted, and then a protective gas is introduced; (2) After introducing protective gas, heat to 160-220°C for the second time, add phosphorus source to the system, and keep warm for 20-40 minutes to complete the first reaction; (3) After the first reaction, a selenium source and / or a second zinc source is added to the system, and the system is heated to 280-320°C for a third time under a protective atmosphere and kept warm for 30-60 minutes to complete the second reaction; (4) After the second reaction, cool to 60-85°C, purify, evacuate, pass protective gas, and heat to 180-220°C for the fourth time; (5) After the fourth heating, a sulfur source and / or a third zinc source is added to the system, and the system is heated to 280-320°C for a fifth time, kept warm for 30-60 minutes to complete the third reaction, and purified to obtain the quantum dots; The multidentate ligand includes any one or a combination of at least two of ethylenediaminetetraacetic acid, a salt of ethylenediaminetetraacetic acid, triethanolamine, a salt of triethanolamine, nitrilotriacetic acid, a salt of nitrilotriacetic acid, diethylenetriamine, a salt of diethylenetriamine, or a dialkyldimethyl complex quaternary ammonium salt; Based on 100 parts by weight of the indium salt, the mass fraction of the multidentate ligand is 200-300 parts by weight.

2. The preparation method according to claim 1, characterized in that The preparation method also includes a monodentate ligand.

3. The preparation method according to claim 1, characterized in that The indium salt includes any one of indium chloride, indium bromide, indium iodide, indium acetate or indium sulfate, or a combination of at least two thereof.

4. The preparation method according to claim 1, characterized in that The first zinc source, the second zinc source, and the third zinc source each independently comprise a zinc-containing compound.

5. The preparation method according to claim 4, characterized in that The zinc-containing compound includes any one of diethyl zinc, zinc stearate, zinc sulfate, zinc chloride or zinc bromide, or a combination of at least two thereof.

6. The preparation method according to claim 4, characterized in that The second zinc source and the third zinc source each independently further comprise a solvent.

7. The preparation method according to claim 6, characterized in that In the second zinc source and the third zinc source, the solvent includes caprylic decanoic acid glyceride and / or octadecene.

8. The preparation method according to claim 1, characterized in that The copper source includes a copper salt and a ligand.

9. The preparation method according to claim 8, characterized in that The copper salt includes any one or a combination of at least two of copper decanoate, copper dodecanoate, copper hexadecanoate, copper oleate, copper isopropoxide or copper halide.

10. The preparation method according to claim 1, characterized in that The manganese source includes a manganese-containing compound and a ligand.

11. The preparation method according to claim 10, characterized in that: The manganese-containing compound includes any one of manganese isopropoxide, manganese decanoate, manganese dodecanoate, manganese hexadecanoate, manganese oleate, manganese isopropoxide or manganese halide, or a combination of at least two thereof.

12. The preparation method according to claim 1, characterized in that The phosphorus source includes a phosphorus-containing compound and a ligand.

13. The preparation method according to claim 12, characterized in that The phosphorus-containing compound includes tris(trimethylsilyl)phosphine and / or tris(dimethyl)amidophosphine.

14. The preparation method according to any one of claims 8, 10 or 12, characterized in that The ligands independently include any one or a combination of at least two of ethylenediaminetetraacetic acid, triethanolamine, diethylenetriamine, nitrilotriacetic acid and related salts thereof.

15. The preparation method according to claim 1, characterized in that The selenium source includes a selenium-containing substance and a solvent.

16. The preparation method according to claim 15, characterized in that The selenium-containing substance is selenium element.

17. The preparation method according to claim 15, characterized in that In the selenium source, the solvent includes any one of trioctylphosphine, tri-n-octylphosphine oxide, tributylphosphine or trihexylphosphine oxide, or a combination of at least two thereof.

18. The preparation method according to claim 1, characterized in that The sulfur source includes dodecyl mercaptan and / or octadecanethiol.

19. The preparation method according to claim 1, characterized in that Based on 100 parts by total mass of the indium salt, the mass fraction of the first zinc source is 300-500 parts.

20. The preparation method according to claim 1, characterized in that Based on 100 parts by total mass of the indium salt, the total mass of the copper source and the manganese source is 5-20 parts.

21. The preparation method according to claim 20, characterized in that In the mixture of the copper source and the manganese source, the concentrations of copper ions and manganese elements are independently 5-100 mmol / L.

22. The preparation method according to claim 1, characterized in that Based on 100 parts by weight of the indium salt, the weight fraction of the phosphorus source is 80-120 parts by weight.

23. The preparation method according to claim 12, characterized in that In the phosphorus source, the volume ratio of the phosphorus-containing compound to the ligand is (1-5):

10.

24. The preparation method according to claim 4, characterized in that In the second zinc source and the third zinc source, the mass concentration of the zinc-containing compound is independently 0.1-0.5 g / mL.

25. The preparation method according to claim 15, characterized in that In the selenium source, the mass concentration of the selenium-containing substance is 50-90 g / L.

26. The preparation method according to claim 1, characterized in that When the indium salt, the first zinc source, the copper source and the manganese source are mixed, the indium salt and the first zinc source are first mixed, and then further mixed with the mixture of the copper source and the manganese source.

27. A quantum dot, characterized in that The quantum dots are obtained by the preparation method according to any one of claims 1 to 26; The quantum dots include a core layer, a transition layer and a shell layer; The core layer includes indium phosphide; The transition layer includes zinc, copper, manganese and selenium; The shell layer includes zinc sulfide.

28. A quantum dot glue, characterized in that The quantum dot glue comprises the quantum dots according to claim 27 and a diluent monomer.

29. The quantum dot glue according to claim 28, characterized in that The quantum dots include red quantum dots and green quantum dots in a mass ratio of 1:(5-12).

30. The quantum dot glue according to claim 28, characterized in that Taking the total mass of the quantum dot glue as 100%, the mass percentage of the quantum dots is 0.5%-2%.

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