Composite structure quantum dot nanoparticles and preparation method and application thereof
By using a two-layer structure of rare earth halide modification and metal oxide coating, the problem of simultaneously optimizing optical performance and stability of quantum dot surface modification is solved, achieving high-efficiency optical performance and stability improvement of quantum dots and expanding their application range.
Patent Information
- Application Number
- CN202610392943.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-27
- Publication Date
- 2026-07-14
AI Technical Summary
Existing quantum dot surface modification techniques cannot simultaneously achieve optical performance optimization and stability improvement. Traditional coating techniques can only physically isolate water and oxygen but cannot passivate surface defects, and have poor interface compatibility, leading to quantum dot fluorescence quenching.
A dual-layer structure of rare earth halide modification layer and metal oxide coating layer is adopted. Rare earth halide fills the surface electronic defects and optimizes the interface compatibility, while metal oxide provides dense coating to isolate water, oxygen and heavy metal ions.
Significantly improves the optical performance and stability of quantum dots, increasing quantum yield by 10%-20%, photostability by over 40%, water and oxygen stability by over 50%, and reducing heavy metal leakage rate by over 90%, thus expanding the application of quantum dots in high-end optoelectronics and biomarking fields.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of quantum dot materials technology, and in particular to a composite structure quantum dot nanoparticle, its preparation method, and its application. Background Technology
[0002] Quantum dots, as novel semiconductor nanocrystals, have wide applications in optoelectronics due to their advantages such as tunable emission spectra, high quantum yield, and narrow half-maximum width at half-maximum (WHM). However, their surfaces contain numerous electronic defects and are highly sensitive to water, oxygen, and ultraviolet light. Some quantum dots containing heavy metals are also prone to ion leakage, which limits their practical applications.
[0003] In related technologies, to address the aforementioned issues, the surface of quantum dots can be coated or modified. However, traditional silica coating technology can only achieve physical water and oxygen barrier, failing to passivate surface defects of quantum dots and thus offering no improvement in optical performance. While single metal oxide coating can optimize stability to some extent, the poor compatibility between quantum dots and oxides leads to coating layer aggregation and quantum dot fluorescence quenching. Furthermore, existing quantum dot surface modification techniques often employ organic ligands, which have limited modification effects and poor binding with subsequent inorganic coating layers, making it difficult to achieve the dual goals of "optimized optical performance + improved stability."
[0004] Therefore, solving the problem that current quantum dot surface modification methods cannot simultaneously achieve "optical performance optimization + stability improvement" has significant practical implications and production value. Summary of the Invention
[0005] This invention aims to address at least one of the technical problems existing in the prior art. To this end, this invention proposes a composite structure quantum dot nanoparticle, its preparation method, and its application, aiming to solve the problem that current quantum dot surface modification methods struggle to simultaneously achieve "optical performance optimization + stability improvement."
[0006] In a first aspect, the present invention provides a composite structure quantum dot nanoparticle comprising: a quantum dot at the core, a rare earth halide modification layer on the surface of the quantum dot, and a metal oxide coating layer on the outermost layer.
[0007] The composite quantum dot nanoparticles according to embodiments of the present invention have at least the following beneficial effects: The composite quantum dot nanoparticles provided by the present invention include a quantum dot core and a two-layer structure consisting of a rare earth halide modification layer and a metal oxide coating layer. Rare earth halides are used to passivate the surface of the quantum dots, filling electronic defects on the quantum dot surface and optimizing interfacial compatibility. Then, the modified quantum dots are densely coated with metal oxides to form quantum dot nanoparticles with a rare earth halide-metal oxide double-layer protection. The surface modification with rare earth halides can significantly improve the intrinsic quantum yield of the quantum dots, while the metal oxide coating achieves efficient water and oxygen barrier properties. The double-layer modification synergistically enhances the optical performance and stability of the quantum dots. The present invention has the following beneficial effects: 1) Rare earth halide-metal oxide bilayer synergistic modification: rare earth halide surface modification improves the inherent quantum yield of quantum dots, and metal oxide coating achieves high efficiency and stability improvement, solving the problem of traditional coating technology "only protects, not optimizes"; 2) The rare earth halide modification layer optimizes the interfacial compatibility between quantum dots and metal oxides, avoids coating layer aggregation and fluorescence quenching, and shortens the subsequent coating reaction time; 3) The bilayer structure achieves multiple protections, which not only passivates the surface defects of quantum dots, but also isolates water, oxygen and ultraviolet light, and can also fix heavy metal ions, greatly expanding the application scope of quantum dots in high-end optoelectronics, biolabeling and other fields.
[0008] In some embodiments of the present invention, the rare earth halide includes at least one of LaCl3, CeBr3, CeCl3, or YF3, but is not limited thereto. Rare earth halides possess unique electronic structures that can effectively fill hole defects on the surface of quantum dots, reduce nonradiative recombination, and improve quantum yield. Furthermore, the halide ions of rare earth halides can form coordination bonds with metal ions on the quantum dot surface, optimizing the surface interface properties of the quantum dots and enhancing the bonding force with subsequent inorganic oxide coating layers, thus providing the possibility for achieving bilayer synergistic modification. Therefore, developing a quantum dot modification method involving rare earth halide surface modification followed by stepwise metal oxide coating can achieve a dual improvement in the optical performance and stability of quantum dots.
[0009] In some embodiments of the present invention, the rare earth halide is a mixture of LaCl3 and YF3 in a 1:1 mass ratio. Rare earth halides can be used in combination, and the 1:1 mass ratio of LaCl3 and YF3 provides the optimal surface passivation effect for quantum dots.
[0010] In some embodiments of the present invention, the metal oxide includes at least one of TiO2, Al2O3, or ZrO2, but is not limited thereto.
[0011] In some embodiments of the present invention, the metal oxide is a mixture of Al2O3 and ZrO2 in a mass ratio of 1:1. In this case, the water and oxygen barrier properties of the coating layer are optimal.
[0012] Surface modification can increase the original quantum yield of quantum dots by 10% to 20%; subsequent metal oxide coating has no significant effect on the emission wavelength and full width at half maximum of quantum dots, and after double-layer modification, the photostability (under ultraviolet irradiation) of quantum dots is increased by more than 40%, the water and oxygen stability (under high temperature and high humidity) is increased by more than 50%, and the heavy metal leakage rate is reduced by more than 90%.
[0013] In some embodiments of the present invention, the particle size of the composite quantum dot nanoparticles is 40~380nm. For example, it can be 40nm, 60nm, 80nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 380nm, or within any two of the above values.
[0014] In some embodiments of the present invention, the thickness of the rare earth halide modification layer is 4-6 nm. For example, it can be 4 nm, 4.5 nm, 5 nm, 5.5 nm, 6 nm, or within any two of the above values. Preferably, it is 5 nm.
[0015] In some embodiments of the present invention, the thickness of the metal oxide coating layer is 15-25 nm. For example, it can be 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, or within any two of the above values. Preferably, it is 20 nm.
[0016] In some embodiments of the present invention, the quantum dot includes a core-shell quantum dot or a non-core-shell quantum dot.
[0017] In some embodiments of the present invention, the nucleus of the core-shell quantum dot is selected from one of ZnS, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe, GaNSb, GaPSb, AlNSb, AlPSb, InNSb, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb, but is not limited thereto.
[0018] In some embodiments of the present invention, the shell of the core-shell quantum dot is selected from CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe, Ga One of N, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, but not limited to these.
[0019] Specifically, the core-shell structured quantum dots include CdSe / ZnS quantum dots. Specifically, the non-core-shell quantum dots include CsPbBr3 quantum dots and AgInS2 quantum dots.
[0020] In some embodiments of the present invention, ligands may also be attached to the surface of the quantum dots. The ligands may be ligands commonly found in the art, including but not limited to one or more of the following: C1-C30 aliphatic carboxylic acid ligands, C6-C30 aromatic carboxylic acid ligands, C1-C30 aliphatic thiol ligands, C6-C30 aromatic thiol ligands, C1-C30 aliphatic amine ligands, C6-C30 aromatic amine ligands, C1-C30 aliphatic phosphine ligands, C6-C30 aromatic phosphine ligands, and C6-C30 aromatic phosphate ligands and halogen ligands.
[0021] The C1-C30 aliphatic carboxylic acid ligands include, but are not limited to, one or more of octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, eicosanoic acid, teicosanoic acid, oleic acid, linoleic acid, arachidic acid, arachidonic acid, erucic acid, and docosahexaenoic acid; the C6-C30 aromatic carboxylic acid ligands include, but are not limited to, one or more of benzoic acid, biphenylcarboxylic acid, and 1-naphthoic acid. The C1-C30 aliphatic thiol ligands include, but are not limited to, one or more of hexamethylenetetramine, octanethiol, nonanethiol, decanethiol, undecylthiol, dodecanethiol, hexadecylthiol, and octadecylthiol; the C6-C30 aromatic thiol ligands include, but are not limited to, one or more of benzenethiol and triphenylmethanethiol. C1-C30 aliphatic amine ligands include, but are not limited to, one or more of hexylamine, octylamine, dioctylamine, trioctylamine, nonylamine, decylamine, dodecylamine, tridecanamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecanamine, octadecylamine, and oleylamine. C6-C30 aromatic amine ligands include, but are not limited to, one or more of aniline, indolepropylamine, 4-octylaniline, and benzidine. C1-C30 aliphatic phosphine ligands include, but are not limited to, one or more of trimethylphosphine, triethylphosphine, tripropylphosphine, tributylphosphine, trihexylphosphine, trioctylphosphine, tridecylphosphine, tributylphosphine oxide, trihexylphosphine oxide, trioctylphosphine oxide, and tridecylphosphine oxide. C6-C30 aromatic phosphine ligands include, but are not limited to, one or more of bis(2-diphenylphosphineethyl)phenylphosphine and triphenylphosphine oxide. C6-C30 aromatic phosphate ligands include, but are not limited to, one or more of tetraethyl p-xylene diphosphate and ethyl p-phenylphosphate. Halogen ligands include, but are not limited to, one or more of -Cl, -F, -I, and -Br.
[0022] The composite quantum dot nanoparticles provided by this invention are modified and coated with oil-soluble quantum dots, using oleic acid, oleylamine, etc. as ligands, and are soluble in organic solvents such as toluene, hexane, and chloroform. The core quantum dots can be core-shell structures (such as CdSe / ZnS quantum dots) or non-core-shell structures (such as CsPbBr3 and AgInS2 quantum dots). The resulting bilayer quantum dot nanoparticles have a particle size of 40~380nm, with the quantum dots uniformly dispersed within them. Rare earth halide surface modification increases the original quantum yield of the quantum dots by 10%-20%. Subsequent metal oxide coating has no significant effect on the emission wavelength and full width at half maximum (FWHM) of the quantum dots. Furthermore, the photostability and water-oxygen stability of the quantum dots are significantly improved after bilayer modification, and the heavy metal leakage rate is significantly reduced.
[0023] Figure 1 The figure shows a schematic diagram of the bilayer structure of quantum dots with rare earth halide surface modification and metal oxide coating in this invention; in the figure, a) is a schematic diagram of quantum dots after rare earth halide modification; and b) is a schematic diagram of quantum dots coated with metal oxide after modification.
[0024] In a second aspect, the present invention provides a method for preparing composite structure quantum dot nanoparticles, comprising the steps of: S100. Dissolve quantum dots in an organic solvent to obtain a quantum dot solution; S200. Add an alcoholic solution of rare earth halides to the quantum dot solution and react under predetermined conditions. The rare earth halides modify the surface of the quantum dots to obtain a mixture of rare earth halide-modified quantum dots. S300. Add a metal oxide precursor and a dispersant to the mixture of rare earth halide-modified quantum dots, stir and mix evenly to obtain a precursor solution. S400. The precursor solution is reacted under predetermined condition two, and the surface of the rare earth halide modified quantum dots is coated with metal oxide to obtain a solution of composite structure quantum dot nanoparticles.
[0025] The method for preparing composite quantum dot nanoparticles according to embodiments of the present invention has at least the following beneficial effects: The present invention proposes a method for preparing composite quantum dot nanoparticles by rare earth halide surface modification and stepwise metal oxide coating. The method adopts a two-step approach of "modification first, coating later". First, the surface of the quantum dots is passivated by rare earth halides to improve their inherent optical properties and optimize interface compatibility. Then, dense coating is performed by metal oxides to achieve efficient water and oxygen barrier and heavy metal isolation. Both steps are carried out under mild conditions, the raw materials are simple, the cost is low, the environmental pollution is small, the preparation process is controllable, and it is suitable for large-scale production. The method of this invention has the following beneficial effects: 1) The two-step modification works synergistically, with rare earth halide surface modification improving the inherent quantum yield of quantum dots and metal oxide coating achieving high efficiency and stability improvement, solving the problem of traditional coating technology "only protecting, not optimizing"; 2) The rare earth halide modification layer optimizes the interfacial compatibility between quantum dots and metal oxides, avoiding coating layer aggregation and fluorescence quenching, and shortening the subsequent coating reaction time; 3) All reactions are carried out under mild conditions, without the need for high temperature and high pressure, the raw materials are readily available and low in cost, the operation is simple, the preparation process is controllable, and it is suitable for large-scale industrial production; 4) The double-layer structure achieves multiple protections, which not only passivates the surface defects of quantum dots, but also isolates water, oxygen, and ultraviolet light, and can also fix heavy metal ions, greatly expanding the application range of quantum dots in high-end optoelectronics, biolabeling and other fields.
[0026] In some embodiments of the present invention, after obtaining a solution of composite structure quantum dot nanoparticles, the method further includes step S500: centrifuging at a rate of 3000~12000 r / min for 3~10 min to obtain the composite structure quantum dot nanoparticles.
[0027] Preferably, the product coated with a single metal oxide is centrifuged at a rate of 8000 r / min for 6 min, while the product coated with a composite metal oxide is centrifuged at a rate of 10000 r / min for 8 min.
[0028] In some embodiments of the present invention, the rare earth halide includes at least one of LaCl3, CeBr3, CeCl3, or YF3, but is not limited thereto. Rare earth halides possess unique electronic structures that can effectively fill hole defects on the surface of quantum dots, reduce nonradiative recombination, and improve quantum yield. Furthermore, the halide ions of rare earth halides can form coordination bonds with metal ions on the quantum dot surface, optimizing the surface interface properties of the quantum dots and enhancing the bonding force with subsequent inorganic oxide coating layers, thus providing the possibility for achieving bilayer synergistic modification. Therefore, developing a quantum dot modification method involving rare earth halide surface modification followed by stepwise metal oxide coating can achieve a dual improvement in the optical performance and stability of quantum dots.
[0029] In some embodiments of the present invention, the rare earth halide is a mixture of LaCl3 and YF3 in a 1:1 mass ratio. Rare earth halides can be used in combination, and the 1:1 mass ratio of LaCl3 and YF3 provides the optimal surface passivation effect for quantum dots.
[0030] In some embodiments of the present invention, the metal oxide precursor includes at least one of tetrabutyl titanate, aluminum isopropoxide, or zirconium oxychloride. The present invention uses single or composite metal oxides of TiO2, Al2O3, and ZrO2 generated by the decomposition of the metal oxide precursor to densely coat the modified quantum dots. When Al2O3 and ZrO2 generated from the decomposition of the metal oxide precursor are combined in a 1:1 mass ratio, the water and oxygen barrier properties of the coating layer are optimal.
[0031] Surface modification can increase the original quantum yield of quantum dots by 10% to 20%; subsequent metal oxide coating has no significant effect on the emission wavelength and full width at half maximum of quantum dots, and after double-layer modification, the photostability (under ultraviolet irradiation) of quantum dots is increased by more than 40%, the water and oxygen stability (under high temperature and high humidity) is increased by more than 50%, and the heavy metal leakage rate is reduced by more than 90%.
[0032] In some embodiments of the present invention, the particle size of the composite quantum dot nanoparticles is 40~380nm. For example, it can be 40nm, 60nm, 80nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 380nm, or within any two of the above values.
[0033] In some embodiments of the present invention, the method for preparing the composite structure quantum dot nanoparticles includes at least one of (a1) to (a7): (a1) The quantum dots include core-shell quantum dots or non-core-shell quantum dots; (a2) The organic solvent includes at least one of toluene, hexane, or chloroform; (a3) The alcohol solution of the rare earth halide is prepared by dissolving the rare earth halide in an alcohol solution, and the concentration of the rare earth halide is 0.05~0.2 mol / L; (a4) The mass ratio of the rare earth halide to the quantum dot is 1:10 to 1:50; (a5) The mass ratio of the metal oxide precursor to the quantum dots is 1:150 to 1:200; (a6) The dispersant includes at least one of triethanolamine or triethyl citrate.
[0034] (a7) The amount of the dispersant added is 1% to 3% of the mass of the metal oxide precursor.
[0035] In some embodiments of the present invention, the quantum dots are as described above and will not be repeated here. Preferably, the quantum dots can be core-shell structures (such as CdSe / ZnS quantum dots) or non-core-shell structures (such as CsPbBr3 and AgInS2 quantum dots). The quantum dots are oil-soluble quantum dots, with oleic acid, oleylamine, etc. as ligands, and can be dissolved in organic solvents such as toluene, hexane, and chloroform.
[0036] In some embodiments of the present invention, the organic solvent includes one or more of toluene, hexane, and chloroform, but is not limited thereto.
[0037] In some embodiments of the present invention, the alcohol solution of the rare earth halide is prepared by dissolving the rare earth halide in an alcohol solution, and the concentration of the rare earth halide is 0.05~0.2 mol / L, for example, it can be 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, or within any two of the above values; the alcohol solution is a mixture of anhydrous ethanol and isopropanol.
[0038] In some embodiments of the present invention, the mass ratio of the rare earth halide to the quantum dot is 1:10 to 1:50, for example, it can be 1:10, 1:20, 1:30, 1:40, 1:50, or within any two of the above values. Preferably, it is 1:30.
[0039] In some embodiments of the present invention, the mass ratio of the metal oxide precursor to the quantum dot is 1:150 to 1:200, for example, it can be 1:150, 1:160, 1:170, 1:180, 1:190, 1:200, or within any two of the above values.
[0040] In some embodiments of the present invention, the dispersant includes at least one of triethanolamine or triethyl citrate, but is not limited thereto.
[0041] In some embodiments of the present invention, the amount of the dispersant added is 1% to 3% of the mass of the metal oxide precursor. Preferably, it is 2%.
[0042] In some embodiments of the present invention, the predetermined conditions include: the reaction is carried out under stirring conditions, with a stirring rate of 300-500 r / min, a reaction temperature of 20-30°C, and a reaction time of 1-3 h. Preferably, the stirring rate is 400 r / min, the temperature is 25°C, and the modification time is 2 h.
[0043] In some embodiments of the present invention, the second predetermined condition includes: the reaction is carried out under stirring conditions, with a stirring rate of 200-1000 r / min, a reaction temperature of 15-60°C, a reaction humidity of 30-70% RH, and a reaction time of 4-30 h. Preferably, for single TiO2 coating, the stirring rate is 500 r / min, the temperature is 30°C, and the humidity is 50% RH; for Al2O3-ZrO2 composite coating, the stirring rate is 600 r / min, the temperature is 40°C, and the humidity is 60% RH. The coating reaction time of rare earth halide-modified quantum dots with metal oxides is shortened by 20%-30% compared to direct coating.
[0044] In one specific embodiment of the present invention, a method for preparing composite structure quantum dot nanoparticles is provided, specifically including two core processes: rare earth halide surface modification and metal oxide coating. The detailed steps are as follows: a) Take oil-soluble quantum dots modified with oleic acid or oleylamine ligands, dissolve them in one or more organic solvents such as toluene, hexane, and chloroform, and disperse them evenly by ultrasonication to obtain solution A; b) Dissolve rare earth halides in a mixture of anhydrous ethanol / isopropanol to prepare a rare earth halide alcohol solution with a concentration of 0.05~0.2mol / L. Add the alcohol solution to solution A at a mass ratio of rare earth halide to quantum dots of 1:10~1:50. Stir for 1~3h at 20~30℃ and 300~500r / min to complete the passivation modification of the quantum dot surface and obtain a rare earth halide modified quantum dot mixture C. c) Add a metal oxide precursor (one or more of tetrabutyl titanate, aluminum isopropoxide, and zirconium oxychloride) to the mixture C, and add 1% to 3% of a dispersant (triethanolamine or triethyl citrate) by mass of the metal oxide precursor. Stir and mix evenly to obtain solution B, wherein the mass ratio of the metal oxide precursor to the quantum dots is 1:150 to 1:200. d) Stir the B solution under the set conditions (stirring rate 200~1000r / min, temperature 15~60℃, humidity 30~70RH) for 4~30h to hydrolyze the metal oxide precursor and form a dense metal oxide coating layer on the surface of the quantum dots modified with rare earth halides, thus obtaining a solution of bilayer structure quantum dot nanoparticles. e) Centrifuge the above solution at 3000~12000 r / min for 3~10 min, collect the precipitate, wash it 3 times with the corresponding organic solvent, and dry it to obtain the rare earth halide surface modified-metal oxide coated composite quantum dot nanoparticles.
[0045] The preparation method of this invention uses core-shell quantum dots (such as CdSe / ZnS quantum dots) or non-core-shell quantum dots (such as CsPbBr3 and AgInS3 quantum dots) as the core quantum dots. The surface ligands of the quantum dots are oil-soluble ligands such as oleic acid or oleylamine. The quantum dots are first surface-modified with rare earth halides, and then coated with metal oxides (TiO2, Al2O3, ZrO2, single or combined) generated by the decomposition of precursors such as tetrabutyl titanate, aluminum isopropoxide, and zirconium oxychloride. This forms a bilayer structure of rare earth halide-coated quantum dot nanoparticles with a particle size of 40-380 nm, in which the quantum dots are uniformly dispersed. The surface modification effect is controlled by the amount of rare earth halide and the reaction time, and the coating layer thickness, nanoparticle size, and number of coated quantum dots are controlled by the ratio of metal oxide precursors and the reaction conditions.
[0046] In a third aspect, the present invention proposes the application of the above-mentioned composite structure quantum dot nanoparticles and the preparation method of the above-mentioned composite structure quantum dot nanoparticles in LED lighting, flexible optoelectronic displays, solar cells, biofluorescent labeling, and quantum dot anti-counterfeiting materials.
[0047] In a fourth aspect, the present invention provides a quantum dot light-emitting diode comprising the above-described composite structure quantum dot nanoparticles or the composite structure quantum dot nanoparticles prepared by the above-described preparation method.
[0048] In some embodiments of the present invention, the quantum dot light-emitting diode includes an anode layer, a cathode layer, and a light-emitting layer disposed between the anode layer and the cathode layer; wherein the material of the light-emitting layer includes the composite structure quantum dot nanoparticles described above or the composite structure quantum dot nanoparticles prepared by the above preparation method.
[0049] In some embodiments of the present invention, a hole functional layer is disposed between the anode layer and the light-emitting layer; and an electron functional layer is disposed between the cathode layer and the light-emitting layer. The hole functional layer includes a hole injection layer and / or a hole transport layer; the electron functional layer includes an electron injection layer and / or an electron transport layer.
[0050] The aforementioned anode layer, light-emitting layer, hole functional layer, electron functional layer, cathode layer, etc., are all conventional configurations in this field and will not be described in detail here.
[0051] Unless otherwise specified, the term "volume" in this invention refers to the volume of the material in its natural state. "Natural state" means under no stress (compression or tension), at one atmosphere of pressure, and without heat (room temperature). Attached Figure Description
[0052] Figure 1 is a schematic diagram of the bilayer structure of rare earth halide surface modification-metal oxide coated quantum dots of the present invention; Figure 2 The fluorescence emission spectra of CsPbBr3 quantum dots before and after LaBr3 modification and Al2O3-ZrO2 coating in Example 1 of this invention are shown. Figure 3 is a transmission electron microscope image of the nanoparticles of CsPbBr3 quantum dots modified with LaBr3 and coated with Al2O3-ZrO2 in Example 1 of the present invention. Figure 4 is a comparison of the aging stability of CdSe / ZnS quantum dots without modification, coated with a single metal oxide, and modified with a rare earth halide-metal oxide bilayer in Example 2 of the present invention. Figure 5 is a bar chart of fluorescence quantum yield at different stages of YF3 surface-modified ZrO2-coated AgInS2 quantum dot nanoparticles in Example 3 of the present invention. Detailed Implementation
[0053] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.
[0054] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0055] Unless otherwise specified in the following examples, the techniques or conditions described in the literature in this field or in accordance with the product instructions shall apply. All reagents or instruments without a specified manufacturer are commercially available conventional products.
[0056] Example 1: LaBr3 surface modification / Al2O3-ZrO2 composite coating / CsPbBr3 quantum dot nanoparticles 1. Synthesis of CsPbBr3 quantum dots Add 0.25 mmol of CsCO3, 0.25 ml of oleic acid (OA), and 4 ml of octadecene (ODE) to a three-necked flask. Vacuum at 90°C for 30 min, then purge with nitrogen. Heat to 150°C until a colorless solution 1 is formed. Add 0.188 mmol of PbBr2, 0.5 ml of oleic acid (OA), 0.5 ml of oleylamine (OLA), and 5 ml of octadecene (ODE) to a three-necked flask. Vacuum at 90°C for 30 min, then purge with nitrogen. Heat to 180°C and rapidly inject solution 1. React for 5 s, then cool in a water bath to obtain CsPbBr3 quantum dot slurry. Mix the slurry with isopropanol at a volume ratio of 1:1, centrifuge to remove the supernatant, wash the precipitate three times, and dissolve in toluene to obtain a CsPbBr3 quantum dot toluene solution.
[0057] 2. LaBr3 surface modified with CsPbBr3 quantum dots Take 2 ml of the above CsPbBr3 quantum dot toluene solution as solution A and add it to a 50 ml single-necked flask; dissolve LaCl3 in anhydrous ethanol to prepare a 0.1 mol / L LaBr3 ethanol solution. According to the mass ratio of LaBr3 to CsPbBr3 quantum dots of 1:30, take an appropriate amount of this ethanol solution and add it to solution A. Stir at 25℃ and 400 r / min for 2 h to complete the surface modification and obtain the LaBr3-modified CsPbBr3 quantum dot mixture C.
[0058] 3. Quantum dots modified with Al2O3-ZrO2 composite coating Add 17.6 ml of toluene to the mixture C for dilution, then add 0.1 g of aluminum isopropoxide, 0.1 g of zirconium oxychloride, and 4 μl of triethanolamine (a dispersant), and stir to obtain solution B. Adjust the reaction conditions to 600 r / min, 40 ℃, and 60 RH, and stir for 20 h (6 h shorter than direct coating). After stirring, centrifuge at 10000 r / min for 8 min, wash the precipitate three times with toluene, and dry to obtain LaBr3 modified / Al2O3-ZrO2 coated / CsPbBr3 quantum dot nanoparticles.
[0059] Example 2: LaCl3-ErBr3 composite modification / TiO2-Al2O3 composite coating / CdSe / ZnS quantum dot nanoparticles 1. Synthesis of CdSe / ZnS core-shell quantum dots 0.1 mmol CdO, 0.5 ml oleic acid, and 5 ml octadecene were added to a three-necked flask. The mixture was evacuated at 150 °C for 1 h, then purged with nitrogen. The temperature was raised to 300 °C, and 1 ml of a 0.5 mol / L trioctylphosphine solution of selenium was injected. The reaction was allowed to proceed for 5 min to obtain CdSe core quantum dots. The temperature was lowered to 200 °C, and 0.2 mmol of an octadecene solution of zinc diethyldithiocarbamate was injected dropwise. The reaction was allowed to proceed for 1 h to obtain CdSe / ZnS core-shell quantum dots. After cooling, isopropanol was added and the mixture was centrifuged. The precipitate was washed three times and dissolved in chloroform to obtain a CdSe / ZnS quantum dot chloroform solution.
[0060] 2. LaCl3-ErBr3 composite surface-modified CdSe / ZnS quantum dots Take 2 ml of the above CdSe / ZnS quantum dot chloroform solution as solution A and add it to a 50 ml single-necked flask; dissolve LaCl3 and ErBr3 in anhydrous isopropanol at a mass ratio of 1:1 to prepare a 0.15 mol / L compound rare earth halide isopropanol solution, and add it to solution A at a mass ratio of compound to quantum dots of 1:20. Stir at 28℃ and 450 r / min for 1.5 h to obtain C mixed solution C of compound rare earth halide modified CdSe / ZnS quantum dots.
[0061] 3. Quantum dots modified with TiO2-Al2O3 composite coating Add 17.6 ml of chloroform to the mixture C for dilution, then add 0.067 g of tetrabutyl titanate, 0.134 g of aluminum isopropoxide, and 4 μl of triethyl citrate. Stir and mix thoroughly to obtain solution B. Adjust the reaction conditions to 500 r / min, 35 ℃, and 55 RH, and stir for 18 h. After stirring, centrifuge at 10000 r / min for 8 min, wash the precipitate three times with chloroform, and dry to obtain the target product.
[0062] Example 3: YF3 surface modification / ZrO2 single coating / AgInS2 quantum dot nanoparticles 1. Synthesis of AgInS2 quantum dots Add 0.4 mmol zinc stearate, 0.4 mmol S powder, and 2 ml trioctylphosphine (TOP) to a 25 ml three-necked flask, evacuate for 20 min, and heat to 100 °C to form a transparent solution 2. Add 0.1 mmol AgNO3, 0.4 mmol In(OAc)3, 0.5 ml oleic acid, and 8 ml octadecene to a three-necked flask, evacuate at room temperature for 20 min, heat to 90 °C and inject 1 ml dodecyl mercaptan, continue heating to 130 °C, inject 1.3 ml oleylamine containing 0.8 mmol, react for 3 min, then inject solution 2, and keep warm for 2 h to obtain AgInS2 quantum dots. Cool to room temperature, add anhydrous ethanol at a volume ratio of 1:1, centrifuge, wash the precipitate 3 times, dissolve in toluene, and obtain an AgInS2 quantum dot toluene solution.
[0063] 2. YF3 surface modified with AgInS2 quantum dots Take 2 ml of the above AgInS2 quantum dot toluene solution as solution A and add it to a 50 ml single-necked flask; prepare a 0.08 mol / L YF3 ethanol solution and add it to solution A at a YF3 to quantum dot mass ratio of 1:40. Stir at 22℃ and 350 r / min for 2.5 h to obtain YF3 modified AgInS2 quantum dot mixture C.
[0064] 3. Quantum dots modified with ZrO2 single coating Add 17.8 ml of toluene to the mixture C for dilution, then add 0.2 g of zirconium oxychloride and 4 μl of triethanolamine, and stir to obtain solution B. Adjust the reaction conditions to 400 r / min, 30 ℃, and 50 RH, and stir for 16 h. After stirring, centrifuge at 9000 r / min for 7 min, wash the precipitate three times with toluene, and dry to obtain the target product.
[0065] Test case The absorption and emission spectra of CsPbBr3 quantum dots, LaBr3-modified CsPbBr3 quantum dots, and LaBr3-modified and Al2O3-ZrO2-coated CsPbBr3 quantum dots in Example 1 were detected using a fluorescence spectrometer. Figure 2 The figures show the absorption and emission spectra of CsPbBr3 quantum dots, LaBr3-modified CsPbBr3 quantum dots, and LaBr3-modified and Al2O3-ZrO2-coated CsPbBr3 quantum dots in Example 1. As can be seen from the figures, the absorption peaks of the surface-modified and coated CsPbBr3 quantum dots shift towards larger wavelengths, and the fluorescence intensity is enhanced.
[0066] The product obtained in Example 1 was observed using a transmission electron microscope. Figure 3 The image shows a high-magnification transmission electron microscope (TEM) image of the nanoparticles of CsPbBr3 quantum dots modified with LaBr3 and coated with Al2O3-ZrO2 in Example 1. As can be seen from the image, a clear oxide matrix appears around the CsPbBr3 quantum dots.
[0067] The fluorescence intensity change of the quantum dots in the product of Example 2 was detected by the following steps: the fluorescence spectrum of the quantum dots was tested using an FLS980 steady-state / transient fluorescence spectrometer with a 450W xenon lamp as the light source. Figure 4 The graph shows the fluorescence intensity changes of quantum dots at 0 / 0.5h / 2h / 5h in a 65% RH environment. It compares the aging stability of unmodified CdSe / ZnS quantum dots (the product obtained in step 1), single metal oxide coated quantum dots (i.e., the products prepared only in steps 1 and 3), and quantum dots modified with a rare earth halide-metal oxide bilayer (the products prepared in steps 1-3) in Example 2. As can be seen from the graph, the quantum dots modified with a rare earth halide-metal oxide bilayer retain the greatest fluorescence intensity.
[0068] The fluorescence quantum yield of the product in Example 3 was tested using an FLS980 steady-state / transient fluorescence spectrometer with a 450W xenon lamp as the light source. Figure 5 shows a bar chart of the fluorescence quantum yield at different stages of the YF3 surface-modified ZrO2-coated AgInS2 quantum dot nanoparticles in Example 3. As can be seen from the figure, the fluorescence quantum yield of AgInS2 quantum dots was significantly improved after rare earth halide surface modification.
[0069] In summary, this invention provides a method for preparing quantum dots through rare earth halide surface modification and stepwise metal oxide coating. First, the quantum dots are passivated with rare earth halides to fill surface electronic defects and optimize interfacial compatibility. Then, single or composite metal oxides such as TiO2, Al2O3, and ZrO2 are generated by decomposing a metal oxide precursor to densely coat the modified quantum dots, forming rare earth halide-metal oxide bilayer protected quantum dot nanoparticles. The advantages of this invention are: both modification steps are carried out under mild conditions (room temperature 60℃), the raw materials are readily available, the operation is simple, the surface modification with rare earth halides significantly improves the inherent quantum yield of quantum dots, the subsequent metal oxide coating achieves efficient water and oxygen barrier properties, the bilayer modification synergistically enhances the optical performance and stability of the quantum dots, the preparation process is controllable, and it is suitable for large-scale production. The core technology of this invention lies in: 1) utilizing the halide ions of rare earth halides (LaCl3, CeBr3, CeCl3, YF3, etc.) to form coordination bonds with metal ions on the surface of quantum dots. Rare earth ions fill electronic defects on the quantum dot surface, achieving surface passivation and improving quantum yield. Simultaneously, a rare earth halide modification layer is formed on the quantum dot surface, optimizing the interfacial compatibility between the quantum dots and the subsequent metal oxide coating layer, preventing coating layer aggregation and fluorescence quenching; 2) using tetrabutyl titanate, aluminum isopropoxide, zirconium oxychloride, etc., as metal oxide precursors, hydrolyzing / The decomposition generates single or composite metal oxides such as TiO2, Al2O3, and ZrO2, which are used to densely coat the quantum dots modified with rare earth halides, forming a double-layer protective structure. This achieves water and oxygen barrier, ultraviolet shielding, and heavy metal fixation. Furthermore, due to the optimization of the interface by the previous surface modification, the coating reaction time is shortened by 20% to 30% compared to direct coating. 3) By controlling the type, amount, and modification time of rare earth halides, as well as the ratio of metal oxide precursors and reaction conditions, the modification effect of quantum dots, the thickness of the coating layer, and the particle size of nanoparticles can be precisely controlled to meet the needs of different application scenarios.
[0070] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.
Claims
1. A composite structure quantum dot nanoparticle, characterized in that, include: The quantum dot is located at the core, a rare earth halide modification layer is located on the surface of the quantum dot, and a metal oxide coating layer is located on the outermost layer.
2. The composite structure quantum dot nanoparticles according to claim 1, characterized in that, The rare earth halides include at least one of LaCl3, CeBr3, CeCl3, or YF3; And / or, the metal oxide includes at least one of TiO2, Al2O3, or ZrO2.
3. The composite structure quantum dot nanoparticles according to claim 1, characterized in that, The particle size of the composite quantum dot nanoparticles is 40~380nm.
4. A method for preparing composite structure quantum dot nanoparticles, characterized in that, Including the following steps: Quantum dots are dissolved in an organic solvent to obtain a quantum dot solution; An alcoholic solution of rare earth halides is added to the quantum dot solution, and the reaction is carried out under predetermined conditions. The rare earth halides modify the surface of the quantum dots, resulting in a mixture of rare earth halide-modified quantum dots. A metal oxide precursor and a dispersant are added to the mixture of rare earth halide-modified quantum dots, and the mixture is stirred and mixed evenly to obtain a precursor solution. The precursor solution is reacted under predetermined condition two, and the surface of the rare earth halide-modified quantum dots is coated with metal oxide to obtain a solution of composite structure quantum dot nanoparticles.
5. The method for preparing composite structure quantum dot nanoparticles according to claim 4, characterized in that, The rare earth halides include at least one of LaCl3, CeBr3, CeCl3, or YF3; And / or, the metal oxide precursor includes at least one of tetrabutyl titanate, aluminum isopropoxide, or zirconium oxychloride.
6. The method for preparing composite structure quantum dot nanoparticles according to claim 4, characterized in that, After obtaining a solution of the composite structure quantum dot nanoparticles, centrifuge at a rate of 3000~12000 r / min for 3~10 min to obtain the composite structure quantum dot nanoparticles. And / or, the particle size of the composite structure quantum dot nanoparticles is 40~380nm.
7. The method for preparing composite structure quantum dot nanoparticles according to any one of claims 4-6, characterized in that, Including at least one of (a1) to (a7): (a1) The quantum dots include core-shell quantum dots or non-core-shell quantum dots; (a2) The organic solvent includes at least one of toluene, hexane, or chloroform; (a3) The alcohol solution of the rare earth halide is prepared by dissolving the rare earth halide in an alcohol solution, and the concentration of the rare earth halide is 0.05~0.2 mol / L; (a4) The mass ratio of the rare earth halide to the quantum dot is 1:10 to 1:50; (a5) The mass ratio of the metal oxide precursor to the quantum dots is 1:150 to 1:200; (a6) The dispersant includes at least one of triethanolamine or triethyl citrate; (a7) The amount of the dispersant added is 1% to 3% of the mass of the metal oxide precursor.
8. The method for preparing composite structure quantum dot nanoparticles according to any one of claims 4-6, characterized in that, The predetermined conditions include: the reaction is carried out under stirring conditions, the stirring rate is 300~500 r / min, the reaction temperature is 20~30℃, and the reaction time is 1~3h; And / or, the second predetermined condition includes: the reaction is carried out under stirring conditions, the stirring rate is 200~1000 r / min, the reaction temperature is 15~60℃, the reaction humidity is 30~70RH, and the reaction time is 4~30h.
9. The application of a method for preparing composite structure quantum dot nanoparticles as described in any one of claims 1-3 or as described in any one of claims 4-8 in LED lighting, flexible optoelectronic displays, solar cells, biofluorescent labeling, and quantum dot anti-counterfeiting materials.
10. A quantum dot light-emitting diode, characterized in that, This includes composite structure quantum dot nanoparticles as described in any one of claims 1-3 or composite structure quantum dot nanoparticles prepared by the preparation method described in any one of claims 4-8.