Composite nanoparticles, preparation methods and applications

Abstract

This application discloses a composite nanoparticle, its preparation method, and its application. The composite nanoparticle includes a quantum dot core, a first barrier layer coating the quantum dot core, and a second barrier layer coating the first barrier layer. The first barrier layer is an oxide, and the second barrier layer is a fluoropolymer. The composite nanoparticle of this application exhibits good water barrier, oxygen barrier, and thermal insulation properties, which can effectively improve the stability of quantum dots and extend the lifespan of devices.

Description

Technical Field

[0001] This application relates to the field of nano-semiconductor materials, specifically to a composite nanoparticle, its preparation method, and its application. Background Technology

[0002] Quantum dots are inorganic semiconductor light-emitting nanocrystals with three-dimensional dimensions ranging from 1 nm to 20 nm. Due to their particle size being smaller than or close to the exciton Bohr radius, quantum dots have advantages such as a wide excitation wavelength range, controllable particle size, narrow half-peak width, large Stokes shift, and strong photostability. Therefore, they are widely used in display, biological labeling, solar cell and other fields.

[0003] Two major challenges exist in the application of quantum dot materials. First, quantum dots exhibit low tolerance to water, oxygen, and heat. In the structure of quantum dots, ligands maintain structural stability and high luminescence efficiency. However, adverse factors such as light, heat, and water can cause ligands on the quantum dot surface to detach or become ineffective due to chemical reactions. The instability of quantum dots leads to reduced fluorescence emission intensity, peak shift, and broadened full width at half maximum (FWHM). These factors significantly impact the application of quantum dots in devices.

[0004] Secondly, the aggregation of quantum dots is also an important factor affecting quantum dot luminescence. Since the principle of quantum dot luminescence is based on the quantum confinement effect, stable luminescence characteristics can only be maintained when the quantum dots are small in size. When quantum dots aggregate, they change their size, causing the quantum dots to quench and fail.

[0005] Existing technologies utilize epitaxial coating to form a core-shell structure of quantum dots / coatings to enhance their stability. Commonly used shells include aluminosilicate silicon (ASi), polyacrylate, and polyethylene glycol. ASiSi-coated quantum dots possess a certain ability to isolate water and oxygen, thus improving their chemical stability. However, the surface of the ASiSi layer contains numerous hydroxyl groups, which have strong water absorption capabilities. This causes water molecules to gradually accumulate on the ASiSi surface, eventually affecting the luminescence efficiency of the quantum dots. Current common improvement methods involve passivating the ASiSi surface with methylsilanes, phenylsilanes, and nitrosilanes, but this approach offers limited improvement to the material's water-blocking ability. Summary of the Invention

[0006] The purpose of this application is to improve the stability of quantum dots and maintain their excellent luminescent properties.

[0007] To achieve the above objectives, the technical solution adopted in this application is as follows: a composite nanoparticle is provided, comprising a quantum dot core, a first barrier layer covering the quantum dot core, and a second barrier layer covering the first barrier layer, wherein the first barrier layer is an oxide and the second barrier layer is a fluoropolymer.

[0008] As a preferred embodiment, the oxide is Si. x Al y O 2x+3 / 2y Zn x Mg y O x+y A mixture of one or more of TiO2, ZrO2, Al2O3, ZnO, and SnO2.

[0009] As another preferred embodiment, the density of the first barrier layer is 1.2 g / cm³. 3 ~2.5g / cm 3 .

[0010] As another preferred option, the raw materials for preparing the second barrier layer include fluorinated monomers, wherein the fluorinated monomers contain carbon-carbon double bonds.

[0011] As another preferred option, the fluorinated monomer is selected from one or more of the following:

[0012]

[0013]

[0014] As another preferred option, the fluorinated monomer is a fluorinated polyacrylate monomer.

[0015] As another preferred embodiment, the raw materials for preparing the second barrier layer also include styrene, isobornyl methacrylate, vinyl acetate, and acrylate monomers or methacrylate monomers represented by formula (Ⅰ).

[0016] R4 is H or CH3, and R5 is a C1-C12 aliphatic straight-chain or branched alkyl group.

[0017] This application provides a method for preparing composite nanoparticles, comprising the following preparation steps: S100, providing a first solution containing quantum dot cores; S200, performing an oxide synthesis reaction in the first solution, such that the oxide coats the quantum dot cores, and obtaining a first composition after purification; S300, performing a polymerization reaction in a second solution containing the first composition, wherein the monomers participating in the polymerization reaction include fluorinated monomers, such that after the polymerization reaction, the fluorinated polymer coats the first composition, and obtaining the composite nanoparticles after purification.

[0018] As another preferred option, step S200 uses a sol-gel method to synthesize the oxide on the surface of the quantum dot core.

[0019] As another preferred option, the sol-gel method in step S200 specifically involves dissolving an ester compound or a metal alkoxide in an organic solvent, adding an acid or base as a catalyst, then adding a second ligand to the solution to react and form a gel. After filtration, washing, and drying, the first composition is obtained.

[0020] As another preferred option, the second ligand is selected from one or more of the following mixtures:

[0021]

[0022]

[0023] As another preferred embodiment, in step S100, the quantum dot nucleus and the first ligand are mixed in a solvent to obtain the first solution, wherein the amount of the quantum dot nucleus is 2% to 30% of the mass of the solvent, and the amount of the first ligand is 2% to 80% of the mass of the quantum dot nucleus.

[0024] As another preferred option, the first ligand is selected from one or more of the following:

[0025]

[0026]

[0027] As another preferred embodiment, step S300 specifically involves: preparing an aqueous solution containing an emulsifier; mixing the first composition, a fluorine-free monomer, and a fluorine-containing monomer with a solvent to obtain an oil phase mixture; and adding an initiator to allow the aqueous solution containing the emulsifier to undergo emulsion polymerization with the oil phase mixture to form the fluorine-containing polymer.

[0028] As another preferred embodiment, the aqueous solution containing the emulsifier is mixed with the oil phase mixture to obtain the second solution, and a water-soluble initiator is added to the second solution to carry out emulsion polymerization, wherein the amount of the water-soluble initiator is 0.05% to 5% of the total mass of the second solution.

[0029] Further preferably, the fluorine-free monomer is selected from one or more of methyl methacrylate, styrene, and isobornyl methacrylate; the fluorine-containing monomer is a fluorine-containing polyacrylic acid monomer.

[0030] This application provides a composition comprising any of the above-described composite nanoparticles, or composite nanoparticles prepared by any of the above-described preparation methods.

[0031] This application also provides a light conversion device, comprising any of the above-mentioned composite nanoparticles, or composite nanoparticles prepared by any of the above-mentioned preparation methods.

[0032] Compared with the prior art, the beneficial effects of this application are as follows:

[0033] (1) The composite nanoparticles of this application are designed with a fluoropolymer as a second barrier layer on the outer layer, which effectively blocks water, oxygen and heat, improves the stability of quantum dots, and effectively extends the life of quantum dots, thereby extending the life of devices.

[0034] (2) The composite nanoparticles of this application separate individual quantum dots through the structural design of the first barrier layer and the second barrier layer, so as to avoid the aggregation of quantum dots and affect their luminescence properties.

[0035] (3) This application achieves double-layer synergistic coating of the quantum dot core by coating the quantum dot core with a first barrier layer and a second barrier layer layer by layer, which is beneficial to further improve its water vapor barrier performance and prevent the failure of the single barrier layer. Attached Figure Description

[0036] Figure 1 This is a schematic diagram illustrating the synthesis of composite nanoparticles according to an embodiment of this application;

[0037] Figure 2 This is a schematic diagram illustrating the application of composite nanoparticles according to an embodiment of this application;

[0038] In the figure: 1. Quantum dot core; 2. First barrier layer; 20. First composite material; 3. Second barrier layer; 100 composite nanoparticles. Detailed Implementation

[0039] The present application will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0040] In the description of this application, it should be noted that the directional terms such as "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this application.

[0041] It should be noted that the terms "first," "second," etc., in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0042] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0043] One embodiment of this application provides a composite nanoparticle 100, including a quantum dot core 1, a first barrier layer 2 covering the quantum dot core 1, and a second barrier layer 3 covering the first barrier layer 2, wherein the first barrier layer 2 is an oxide and the second barrier layer 3 contains a fluoropolymer.

[0044] Figure 1 A synthetic route for composite nanoparticles 100 is illustrated.

[0045] The quantum dot core 1 referred to in this application means a single quantum dot particle. In other words, the part encased inside the first barrier layer 2 is not multiple quantum dots, but a single quantum dot. This helps to prevent the optical and electrical properties of the quantum dot from being affected by aggregation and precipitation, and to avoid quantum dot quenching failure.

[0046] The first barrier layer 2 is designed as an oxide layer, which can be a metal oxide or a non-metal oxide, or an inorganic oxide. Oxides have a relatively stable structure, and the resulting coating layer can block the entry of water molecules and oxygen, thereby improving the photostability of the quantum dots.

[0047] The second barrier layer 3 utilizes the hydrophobicity of fluoropolymers to effectively prevent water molecules from accumulating, thereby isolating water from the outer layer of the second barrier layer 3 and preventing water molecules from entering the interior of the composite nanoparticles 100 and causing the quantum dots to fail.

[0048] Fluoropolymers exhibit good heat resistance; compared to other polymers, they remain intact even at temperatures up to 260°C, demonstrating high resistance to long-term thermal degradation. Furthermore, fluoropolymers possess excellent chemical stability, typically exhibiting no chemical reaction with acids and alkalis, making them excellent corrosion-resistant materials. Finally, fluoropolymers are non-absorbent, non-swelling, non-conductive, and unaffected by ultraviolet light, providing highly efficient protection for quantum dots. Compared to methods where quantum dot nuclei are directly dispersed in fluoropolymers (as a matrix), the composite nanoparticles of this application ensure complete coverage of the quantum dot nuclei by the fluorinated material during use; moreover, there are no compatibility issues between the quantum dot nuclei and the fluoropolymer, preventing aggregation and expansion of the quantum dot nuclei or phase separation from the fluoropolymer during use.

[0049] Figure 2 This is a schematic diagram illustrating the protective effect of the composite nanoparticles 100 in one embodiment of this application.

[0050] In some embodiments, the composite nanoparticles 100 prepared in this application have a size of 20 nm to 60 nm.

[0051] In some embodiments, the thickness of the first barrier layer 2 is 2 nm to 30 nm, and the thickness of the second barrier layer 3 is 1 nm to 15 nm. A thicker second barrier layer 3 can provide better water-blocking performance.

[0052] In some embodiments, the oxide of the first barrier layer 2 is Si. x Al y O 2x+3 / 2y Zn x Mg y O x+y The mixture is one or more of TiO2, ZrO2, Al2O3, ZnO, and SnO2; preferably, x = 1 and y is a value from 0 to 0.8.

[0053] In some embodiments, the density of the first barrier layer 2 is 1.2 g / cm³. 3 ~2.5g / cm 3 .

[0054] In some embodiments, the second barrier layer 3 is prepared from raw materials including fluorinated monomers, wherein the fluorinated monomers contain carbon-carbon double bonds, so that the fluorinated monomers can polymerize through the double bonds to form a polymer.

[0055] Furthermore, the fluorinated monomer is selected from one or more of the following:

[0056]

[0057]

[0058] In some preferred embodiments, the fluorinated monomer is a fluorinated polyacrylate monomer.

[0059] In some embodiments, the raw materials for preparing the second barrier layer 3 further include: methyl methacrylate, vinyl monomer, and isobornyl methacrylate.

[0060] The vinyl monomer is selected from one or more of the following: acrylate monomers or methacrylate monomers represented by formula (I), styrene, and vinyl acetate.

[0061]

[0062] R4 is H or CH3, and R5 is a C1-C12 aliphatic straight-chain or branched alkyl group.

[0063] Adding the above-mentioned second barrier layer 3 raw material can dissolve fluorinated monomers and enhance the polymerization ability of fluorinated monomers.

[0064] This application does not impose any particular limitation on the quantum dot core 1 (also known as a semiconductor nanocrystal), which can be prepared by any known method or is commercially available. For example, the quantum dot core 1 can be a group II-VI compound, a group III-V compound, a group IV-VI compound, a group IV element or compound, a group I-III-VI compound, a group I-II-IV-VI compound, or a combination thereof.

[0065] In some embodiments, quantum dot core 1 is a group II-VI compound:

[0066] It can be selected from binary compounds such as CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, and MgS;

[0067] It can also be selected from ternary compounds such as CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS, etc.

[0068] It can also be selected from quaternary compounds such as HgZnTeS, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe.

[0069] Quantum dot core 1 can also be a group II-VI compound doped with group III metals.

[0070] In some embodiments, quantum dot core 1 is a group III-V compound:

[0071] It can be selected from binary compounds such as GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, and InSb;

[0072] It can be selected from ternary compounds such as GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, and InZnP.

[0073] It can also be selected from quaternary compounds such as GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb.

[0074] Group III-V compounds may further include Group II metals, such as InZnP.

[0075] In some embodiments, quantum dot core 1 is a group IV-VI compound:

[0076] It can be selected from binary compounds such as SnS, SnSe, SnTe, PbS, PbSe, and PbTe;

[0077] It can be selected from ternary compounds such as SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, and SnPbTe;

[0078] It can also be selected from quaternary compounds such as SnPbSSe, SnPbSeTe, and SnPbSTe.

[0079] Group I-III-VI compounds can be, but are not limited to, CuInSe2, CuInS2, CuInGaSe, and CuInGaS.

[0080] Group I-II-IV-VI compounds can be, but are not limited to, CuZnSnSe and CuZnSnS.

[0081] In some embodiments, the quantum dot core 1 is a group IV element or compound:

[0082] It can be selected from elemental substances such as Si and Ge;

[0083] It can be selected from binary compounds such as SiC and SiGe.

[0084] In some embodiments, the quantum dot core 1 may have a particle diameter of about 1 nm to about 100 nm (in the case of non-spherical particles, the longest length of a straight line across the particle). For example, the quantum dot core 1 may have a particle diameter of about 1 nm to about 20 nm, such as 2 nm (or 3 nm) to 15 nm. In some embodiments, the quantum dot core 1 has a diameter greater than or equal to about 2 nm, greater than or equal to about 3 nm, greater than or equal to about 4 nm, or greater than or equal to about 5 nm and less than or equal to about 50 nm, less than or equal to about 45 nm, less than or equal to about 40 nm, less than or equal to about 35 nm, less than or equal to about 30 nm, less than or equal to about 25 nm, less than or equal to about 20 nm, less than or equal to about 15 nm, less than or equal to about 10 nm, less than or equal to about 9 nm, less than or equal to about 8 nm, or less than or equal to about 7 nm.

[0085] The quantum dot core 1 may have shapes commonly used in the art and is not particularly limited. For example, the quantum dot core 1 may include spherical, elliptical, pyramidal, multi-armed, or cubic nanoparticles, nanotubes, nanowires, nanofibers, nanosheet particles, or combinations thereof.

[0086] The quantum dot core 1 is commercially available or synthesized by any method. For example, several nanometer-sized quantum dots can be synthesized by a wet chemical process. In a wet chemical process, the precursor reacts in an organic solvent to grow nanocrystal particles, and the organic solvent or ligand compound can coordinate (or bind) to the surface of the semiconductor nanocrystal, thereby controlling the growth of the nanocrystal. Examples of organic solvents and ligand compounds are known in the art. The organic solvent coordinated to the surface of the quantum dots can affect their stability, and therefore, excess organic material not coordinated to the surface of the quantum dots can be removed by pouring the quantum dots into an excess of a non-solvent (such as a common polar solvent) and centrifuging the resulting mixture. Examples of non-solvents include, but are not limited to, acetone, ethanol, methanol, etc.

[0087] One embodiment of this application also provides a method for preparing composite nanoparticles 100, comprising the following preparation steps:

[0088] S100 provides a first solution containing quantum dot core 1;

[0089] S200, the oxide synthesis reaction is carried out in the first solution so that the oxide is coated on the quantum dot core 1, and after purification, the first composition 20 is obtained;

[0090] S300, a polymerization reaction is carried out in a second solution containing the first composition 20, wherein the monomers participating in the polymerization reaction include fluorinated monomers, so that after the polymerization reaction, a fluorinated polymer is formed to coat the first composition 20, and after purification, the composite nanoparticles 100 of this application are obtained.

[0091] The bonding strength between the oxide-coated quantum dot core 1 and the fluoropolymer obtained by the above method is stronger than that between the quantum dot 1 and the fluorinated ligand, and the surface coverage of the quantum dot core 1 is more complete and larger, thus resulting in better environmental stability.

[0092] In some embodiments, step 200 uses a sol-gel method to synthesize oxides on the surface of the modified water-soluble quantum dot core 1 to form a first barrier layer 2.

[0093] Furthermore, the first barrier layer 2 is Si. x Al y O 2x+3 / 2y The S200 step specifically involves dissolving an ester compound or a metal alkoxide in an organic solvent to form a homogeneous solution, using an acid or base as a catalyst, adding a second ligand to the solution, reacting to form a gel, and then filtering, washing, and drying to obtain the first composition 20.

[0094] The second ligand can be, but is not limited to:

[0095]

[0096]

[0097] The addition of the second ligand enriches the outer side of the synthesized first barrier layer 2 with carbon-carbon double bonds, which is beneficial for the stable bonding of the fluorine-containing monomer to the surface of the first composition 20 in step S300.

[0098] In some embodiments, the first solution is prepared by mixing the quantum dot core 1 and the first ligand in a solvent to obtain a first solution containing the quantum dot core 1.

[0099] In some preferred embodiments, the quantum dot core 1 accounts for 2% to 30% of the solvent mass, and the first ligand accounts for 2% to 80% of the quantum dot core 1 mass.

[0100] The first ligand can be, but is not limited to:

[0101]

[0102]

[0103] Adding the first ligand to the first solution can change the solubility of quantum dot core 1, increase its hydrophilicity, and make it easier to dissolve in the solvent.

[0104] In some embodiments, step S300 specifically involves: preparing an aqueous solution containing an emulsifier, mixing the first composition 20, a fluorine-free monomer, and a fluorine-containing monomer in a solvent to obtain an oil phase mixture, and adding an initiator to polymerize the aqueous solution containing the emulsifier and the oil phase mixture.

[0105] In a preferred embodiment, the mass of the oil phase mixture is 5% to 80% of the mass of water in the aqueous solution containing the emulsifier; the amount of emulsifier is 10% to 200% of the total mass of the oil phase mixture; the amount of the first composition 20 is 10% to 70% of the total mass of the oil phase mixture; the amount of the fluorine-free monomer is 20% to 60% of the total mass of the oil phase mixture; and the amount of the fluorine-containing monomer is 10% to 70% of the total mass of the oil phase mixture.

[0106] This application uses emulsion polymerization to prepare the second barrier layer 3. By adjusting the ratio of emulsifier to oil phase mixture, the size of each composite nanoparticle 100 is controlled to ensure that each composite nanoparticle 100 contains only one quantum dot, thereby ensuring that the surface of the single quantum dot core 1 is coated with the first barrier layer 2 and the second barrier layer 3.

[0107] The emulsifier is at least one of anionic emulsifiers, cationic emulsifiers, amphoteric emulsifiers, and nonionic emulsifiers.

[0108] Anionic emulsifiers include, but are not limited to: alkyl sulfate emulsifier R4-OSO3M and alkylbenzene sulfonate emulsifier R5-C6H4-SO3M, wherein R3 and R4 are each independently a C10-C20 aliphatic chain alkyl group, R5 is a C10-C18 aliphatic chain alkyl group, and M is Na. + or K + .

[0109] Cationic emulsifiers include, but are not limited to: alkyltrimethylammonium halide emulsifier R6N + (CH3)3X – R6 is a C12-C20 aliphatic alkyl group, and X is Cl or Br.

[0110] Amphoteric emulsifiers may be selected from at least one of the following: carboxylic acid betaine R7N + (CH3)2CH2COO – , sulfonyl betaine R8N + (CH3)2CH2CH2CH2SO3, wherein R7 and R8 are each independently C12 to C18 aliphatic alkyl groups.

[0111] Nonionic emulsifiers include, but are not limited to: OP series emulsifiers, AEO series emulsifiers and Tween series emulsifiers.

[0112] The OP series emulsifier can be at least one of OP-9, OP-10, and OP-15. The AEO series emulsifier can be at least one of AEO-7, AEO-9, AEO-15, and AEO-23. The Tween series emulsifier can be at least one of Tween-20, Tween-40, Tween-60, Tween-80, and Tween-85.

[0113] Furthermore, in step S300, an oil-soluble initiator can be added to the oil phase mixture, and the aqueous solution containing the emulsifier is mixed with the oil phase mixture to obtain a second solution, wherein the amount of the oil-soluble initiator is 0.05% to 5% of the total mass of the fluorinated monomer and the non-fluorinated monomer;

[0114] Alternatively, an aqueous solution containing an emulsifier is mixed with an oil phase mixture to obtain a second solution, and a water-soluble initiator is added to the second solution, wherein the amount of the water-soluble initiator is 0.05% to 5% of the total mass of the fluorinated monomer and the non-fluorinated monomer.

[0115] Oil-soluble initiators include, but are not limited to: azobisisobutyronitrile, azobisisoheptanenitrile, azobisisovalerate, dimethyl azobisisobutyrate, benzoyl peroxide, dilauryl peroxide, and diethylhexyl peroxide.

[0116] Water-soluble initiators include, but are not limited to: azobisisobutylamidine dihydrochloride, azobiscyanopentanoic acid, and persulfate.

[0117] In some embodiments, the fluorine-free monomers include, but are not limited to: methyl methacrylate, styrene, and isobornyl methacrylate.

[0118] In some preferred embodiments, the fluorinated monomer is a fluorinated acrylate monomer.

[0119] The preparation method of this application is simple and reproducible, and has the potential for large-scale production.

[0120] This application also provides a composition comprising the composite nanoparticles 100 of any of the above embodiments, or the composite nanoparticles 100 prepared by any of the preparation methods of the embodiments.

[0121] The composition may also include organic solvents, such as curable resins.

[0122] This application also provides a light conversion device, including the composite nanoparticles 100 of any of the above embodiments, or the composite nanoparticles 100 prepared by any of the preparation methods of the embodiments. The light conversion device can be a quantum dot LED, a quantum dot film, a quantum dot diffuser plate, or a quantum dot color filter.

[0123] Example 1

[0124] The composite nanoparticle A of this application was prepared according to the following steps:

[0125] S100: Weigh 1.3g of quantum dots and dissolve them in 20mL of toluene solution to obtain the first solution containing quantum dot core 1;

[0126] S200: Add 400 μL of the first ligand-1 to the first solution under magnetic stirring, heat to 70 °C and stir continuously for 3 h. After the liquid cools, inject 200 mL of anhydrous ethanol and stir magnetically to obtain a homogeneous mixed solution A.

[0127] Add 20 mL of water and 3 mL of sodium hydroxide with a concentration of 25%–28% to 20 mL of anhydrous ethanol, and mix well to obtain mixed solution B;

[0128] Mixed solution B, 15 mL of tetraethyl orthosilicate, and 5 mL of aluminum isopropoxide were added to mixed solution A. After stirring at room temperature for 24 h, 1.5 mL of the second ligand-1 was added. After stirring for another 12 h, the solution gradually became turbid and a precipitate was formed. The reaction product was centrifuged and washed three times with a mixed solution of toluene and methanol. After vacuum drying, the first composition 20 was obtained.

[0129] S300: Weigh 10g sodium dodecylbenzenesulfonate and 3g AEO-9 and dissolve them in 150g deionized water to obtain an aqueous solution containing emulsifier; weigh 1.2g of the first composition 20, 9g of styrene, and 6g of fluorinated monomer-1 and mix them in 0.3g of n-hexadecane to obtain an oil phase mixture;

[0130] An aqueous solution containing emulsifier was mixed with an oil phase mixture and pre-emulsified by magnetic stirring at 600 rpm to obtain a crude emulsion. The crude emulsion was then placed in an ultrasonic oscillator and sonicated for 15 minutes to obtain a stable second solution.

[0131] 0.12 g of potassium persulfate was added to the second solution, nitrogen was purged to remove oxygen, the temperature was raised to 70 °C, and the reaction was carried out for 6 h under nitrogen protection. After the emulsification reaction was completed, 10 mL of ethanol was added to break the emulsion, and the product was obtained by centrifugation and drying to obtain a composite nanoparticle A of this application. The particle size of composite nanoparticle A is 28–35 nm, the thickness of the first barrier layer is 4–8 nm, and the thickness of the second barrier layer is 2–4 nm.

[0132] Comparative Example 1

[0133] The first composition 20 was prepared according to the preparation steps of S100 and S200 in Example 1, which is used as the composite nanoparticle B prepared in Comparative Example 1.

[0134] Performance testing

[0135] Weigh 80 parts by weight of thermosetting methyl-phenyl silicone resin and mix it evenly with 20 parts by weight of composite nanoparticle A or composite nanoparticle B. Then place the mixture in a vacuum stirrer and degas it for 5 to 10 minutes under the conditions of revolution speed of 600 rpm and rotation speed of 500 rpm to obtain a mixed sealant.

[0136] The mixed adhesive is poured into the encapsulation cavity of the LED bracket using a dispensing machine. The LED bracket is then placed in an oven at 100℃~200℃ for 1 to 2 hours. The LED chip is then placed in an oven at 65℃ and RH95% for aging. The LED chip is periodically removed and its optical performance is tested using an integrating sphere.

[0137] The aging time and quantum efficiency test results of the composite nanoparticles in Example 1 and Comparative Example 1 are recorded in Table 1 below.

[0138] Table 1. Quantum efficiency test results of composite nanoparticles

[0139]

[0140] Analysis of the test results in Table 1 shows that the composite nanoparticles prepared in Example 1 have good stability, with a quantum efficiency loss of only 0.62% after aging for 504 hours, and can maintain the luminescence efficiency of quantum dots. In contrast, the composite nanoparticles prepared in Comparative Example 1 showed a quantum efficiency loss of up to 16.99% after aging for 504 hours.

[0141] The test data above indicate that the oxide layer on the outside of the quantum dots is insufficient to resist moisture erosion in the long term, resulting in a decrease in the luminescence efficiency of the quantum dots. This application addresses this by designing a fluorine-containing polymer layer outside the oxide layer to perform a secondary coating on the oxide-coated quantum dot core, endowing the composite nanoparticles with higher water-blocking, oxygen-blocking, and heat-insulating properties, effectively extending the luminescence lifetime of the quantum dots, and thus extending the lifespan of the device.

[0142] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing composite nanoparticles, characterized in that, The preparation steps include the following: S100 provides a first solution containing quantum dot cores; S200, an oxide synthesis reaction is carried out in the first solution so that the oxide is coated on the quantum dot core, and after purification, a first composition is obtained; S300, a polymerization reaction is carried out in a second solution containing the first composition, wherein the monomers participating in the polymerization reaction include fluorinated monomers, so that the fluorinated polymer is coated on the first composition after the polymerization reaction, and the composite nanoparticles are obtained after purification; the step of forming the fluorinated polymer is as follows: preparing an aqueous solution containing an emulsifier, mixing the first composition, a non-fluorinated monomer and a fluorinated monomer in a solvent to obtain an oil phase mixture, adding an initiator to cause the aqueous solution containing the emulsifier to undergo emulsion polymerization with the oil phase mixture to form the fluorinated polymer; the fluorinated monomer is a fluorinated acrylic monomer; Step S200 uses a sol-gel method to synthesize the oxide on the surface of the quantum dot core; The sol-gel method described in step S200 is as follows: an ester compound or metal alkoxide is dissolved in an organic solvent, an acid or base is added as a catalyst, a second ligand is added to the solution, a gel is formed by reaction, and the first composition is obtained after filtration, washing and drying. The second ligand is selected from one or more of the following mixtures:

2. The preparation method according to claim 1, characterized in that, In step S100, the quantum dot nucleus and the first ligand are mixed in a solvent to obtain the first solution. The amount of the quantum dot nucleus is 2% to 30% of the mass of the solvent, and the amount of the first ligand is 2% to 80% of the mass of the quantum dot nucleus.

3. The preparation method according to claim 2, characterized in that, The first ligand is selected from one or more of the following mixtures:

4. The preparation method according to claim 1, characterized in that, The aqueous solution containing the emulsifier is mixed with the oil phase mixture to obtain the second solution. A water-soluble initiator is added to the second solution to carry out emulsion polymerization. The amount of the water-soluble initiator is 0.05% to 5% of the total mass of the second solution.

5. The preparation method according to claim 1, characterized in that, The fluorine-free monomer is selected from one or more of methyl methacrylate, styrene, and isobornyl methacrylate.

6. A composition comprising composite nanoparticles prepared by any one of the preparation methods of claims 1 to 5.

7. A light conversion device, characterized in that, This includes composite nanoparticles prepared by any of the preparation methods described in claims 1 to 5.

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