A multi-layered quantum dot material and preparation method thereof

Abstract

The present application discloses a multi-layer coated quantum dot material and a preparation method thereof, wherein the multi-layer coated quantum dot material comprises quantum dot / polymer composite microparticles, the surface of the quantum dot / polymer composite microparticles is coated with a protective layer, and the outer side of the protective layer is coated with a metal oxide film. After the perovskite quantum dot / polymer microspheres are coated with the protective layer, the defects on the surface of the microspheres can be significantly improved, a dense spherical shell can be formed, and the micropowders can be evenly dispersed, which is conducive to subsequent atomic layer deposition coating. The coated perovskite quantum dot / polymer micropowder has excellent luminescence properties, and the dense coating layer formed on the surface improves the water and oxygen barrier properties of the material and improves the stability of the perovskite quantum dot / polymer micropowder. The method is simple and has the advantages of low preparation cost and maintaining the optical properties of the powder.

Description

Technical Field

[0001] The present application relates to a multi-layer coated quantum dot material and a preparation method thereof, belonging to the field of display technology. Background Art

[0002] Perovskite quantum dots have excellent characteristics such as simple preparation process, low cost, high quantum yield, and high color purity. They can greatly improve the display color gamut of display devices, and therefore have received widespread attention. At present, the light-emitting film prepared in situ based on perovskite quantum dots has been successfully commercialized in the display field, and the color gamut can be increased to more than 100% NTSC. However, there is still a certain gap between perovskite quantum dot materials and the realization of large-scale industrial applications, that is, there are certain problems with long-term stability in practical applications. The main reason for the poor long-term stability of perovskite quantum dot materials is the intrusion of water and oxygen in the actual environment, which causes fluorescence quenching of quantum dots, resulting in brightness attenuation and color point changes. Therefore, a method to improve the stability of perovskite quantum dot materials is urgently needed.

[0003] The synthesis methods of perovskite quantum dots that have been reported so far, including the hot injection method, all have the problem of using a large amount of solvents and additives during synthesis, resulting in a waste of raw materials; and a high temperature or high temperature and high pressure environment is required during synthesis, and multiple cleaning steps are required after synthesis to obtain quantum dots. The process is cumbersome and wastes a large amount of solvent, which is not conducive to large-scale preparation; in addition, the traditional synthesis method is to prepare quantum dots first, and then carry out subsequent treatments to improve stability, such as inorganic shell coating, organic polymer coating, etc. The by-products produced by these processes will cause the ligands on the surface of the quantum dots to fall off, affecting the optical properties and stability of the quantum dots. Moreover, the post-processing process uses a large amount of solvent again, and the purification process is still complicated and cumbersome, requiring drying, grinding and other steps, which is not conducive to large-scale use. Therefore, new preparation and surface treatment technologies are crucial to improving the stability of perovskite quantum dots. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a two-layer coating treatment technology for perovskite quantum dot / polymer composite micropowder, including solution coating and atomic layer deposition coating of perovskite quantum dot / polymer composite micropowder. The technology first adopts a spray drying method to prepare perovskite quantum dot / polymer luminescent microspheres, which can achieve the preparation of quantum dots and polymer coating in one step. The process is simple and stable, which is far superior to the process of liquid phase synthesis of quantum dots. After obtaining the perovskite quantum dot / polymer microspheres, a protective layer is uniformly coated on the surface of the microspheres by a solution coating method, so that the microsphere particles are evenly dispersed. Finally, a layer of dense inorganic oxide is deposited on the surface of the evenly dispersed particles by atomic layer deposition technology to hinder the intrusion of water and oxygen, thereby improving the stability of the perovskite quantum dot / polymer micropowder. The technology of spraying to prepare perovskite quantum dots / polymer luminescent microspheres and two-layer coated composite materials of the present invention avoids the waste of resources and complicated synthesis procedures of the traditional liquid phase synthesis method, and effectively and evenly performs the polymer coating process and the subsequent two-layer coating process, thereby improving the stability of the luminescent micropowder and promoting the commercial application of perovskite quantum dots.

[0005] As one aspect of the present application, the present application provides a multi-layer coated quantum dot material. In the invention of the present application, a method for composite coating of perovskite quantum dots / polymer microspheres prepared by spray drying is used by using a two-layer coating method of solution coating and atomic layer deposition, which improves the water and oxygen barrier effect, improves the stability and solvent resistance of the perovskite quantum dot material, and can be dispersed in multiple solvent systems. The perovskite quantum dots / polymer micropowders after two layers of coating show ultra-high corrosion resistance, and can be blended with various materials such as photoresists, UV glues, pressure-sensitive adhesives and various organic solvents. Various processes such as dispensing, inkjet printing, screen printing, casting, and photolithography are used to prepare luminous materials in various forms such as luminous dots, lines, and films, which are applied to various fields such as display backlights, broadening the application range of quantum dot composite materials.

[0006] A multi-layer coated quantum dot material comprises quantum dot / polymer composite particles, the surface of the quantum dot / polymer composite particles is coated with a protective layer, and the outer side of the protective layer is coated with a metal oxide film.

[0007] Optionally, the protective layer quantum dot / polymer composite microparticles include a spatial network structure formed by a polymer, and the quantum dots are embedded in the spatial network structure;

[0008] Optionally, the quantum dots are perovskite quantum dots;

[0009] Optionally, the polymer includes at least one of polyvinylidene fluoride, polyvinylidene fluoride and trifluoroethylene copolymer, polyacrylonitrile, polyvinyl acetate, cellulose acetate, cyanocellulose, polysulfone, aromatic polyamide, polyimide, polycarbonate, polystyrene, polymethyl methacrylate, and polylauryl methacrylate.

[0010] Optionally, the protective layer is silicon dioxide and / or amphoteric hydroxide;

[0011] Optionally, the amphoteric hydroxide includes at least one of aluminum hydroxide, titanium hydroxide, and zirconium hydroxide.

[0012] Optionally, the metal oxide film includes at least one of an Al2O3 film, a TiO2 film, a HfO2 film, and a ZrO2 film;

[0013] Optionally, the particle size of the quantum dot / polymer composite particles is 1 to 100 μm;

[0014] The thickness of the protective layer is 10 to 500 nm;

[0015] The thickness of the metal oxide film coating protective layer is 1nm to 100nm.

[0016] As another aspect of the present application, the present application also provides a method for preparing a multi-layer coated quantum dot material. The method for preparing perovskite quantum dots / polymer microspheres by spray drying in the present invention has a simple process and is easy to prepare on an industrial scale. Moreover, the prepared powder and the polymer completely wrap the perovskite quantum dots to form a protective layer, thereby improving the stability of the perovskite quantum dot material. The solution coating in the present invention coats the powder surface with a protective layer through a hydrolysis reaction. After the perovskite quantum dots / polymer microspheres are coated with the protective layer, the defects on the surface of the microspheres can be significantly improved, a dense spherical shell can be formed, and the stability can be improved. At the same time, the solution coating makes the micropowders evenly dispersed, which is conducive to the subsequent atomic layer deposition coating and improves the coating rate. The solvents used for coating can be recycled, greatly reducing the production cost. The atomic layer deposition method in the present invention has a wide range of applications in the industry, and the process is mature. The atomic layer deposition method can continue to deposit nanometer-thickness or submicron-thickness metal oxide films on the surface of evenly dispersed perovskite quantum dots / polymer microspheres to complete the surface coating process of the entire microsphere. The entire coating process does not affect the optical properties of the perovskite quantum dots / polymer microspheres themselves.

[0017] A method for preparing a multi-layer coated quantum dot material comprises the following steps:

[0018] (a) obtaining quantum dot / polymer composite particles;

[0019] (b) reacting a solution containing quantum dot / polymer composite particles, a protective layer raw material compound and a catalyst to obtain quantum dot / polymer composite particles coated with a protective layer;

[0020] (c) forming a metal oxide thin film on the quantum dot / polymer composite particles coated with the protective layer obtained in step (b) by atomic layer deposition.

[0021] Optionally, in step (a), the perovskite quantum dot precursor polymer solution is formed into atomized micro-droplets by a two-fluid atomizer through an infusion pipeline and enters a drying tower. After being dried by hot air blown in from an air inlet, perovskite quantum dot / polymer microspheres are formed, and the perovskite quantum dot polymer powder enters a cyclone separator through an air outlet at the bottom of the drying tank to achieve powder collection.

[0022] Optionally, the quantum adopts perovskite quantum dots.

[0023] Optionally, the raw materials for synthesizing perovskite quantum dots include AX, BX t and a CX precursor; wherein A is selected from NH2CHNH2 + (FA + )、CH3NH3 + (MA + ), Cs + , Rb + , K + At least one of; B is selected from Pb 2+ Sn 2+ 、Bi 3+ 、Ti 3+ 、Zn 2+ 、Ni 2+ 、Cd 2+ 、Al 3+ , Mn 2+ , Mn 4+ ,Ge 3+ At least one of; C is selected from an aromatic group or an alkyl organic amine cation having a carbon number of not less than 3; X is selected from Br - ,I - 、SCN - , carboxylate; m = 2, 3 or 4;

[0024] Optionally, the perovskite quantum dots have the structural formula AMX3, A3M2X9, A2MX6, Q2A m-1 M m X 3m+1 At least one of;

[0025] Where A is NH2CHNH2 + 、CH3NH3 + , Cs+ At least one of;

[0026] M is Pb 2+ 、Cd 2+ , Mn 2+ 、Zn 2+ Sn 2+ ,Ge 2+ 、Bi 3+ At least one of;

[0027] X is at least one of the halogen anions;

[0028] Q is an aromatic group or an alkyl organic amine cation having a carbon number of not less than 3;

[0029] m is any value between 1 and 100.

[0030] Optionally, the perovskite quantum dot precursors AX, BX m The molar ratio of CX is 0.5-10:1:0.5-10;

[0031] Optionally, the solvent includes at least one of dimethyl sulfoxide, n-hexane, cyclohexane, n-octane, octadecene, ethanol, methanol, trimethyl phosphate, triethyl phosphate, N-methylpyrrolidone, dimethylacetamide, N,N-dimethylformamide, isopropanol, ethyl acetate, toluene and acetone.

[0032] Optionally, the mass ratio of the solvent to the polymer matrix in the perovskite quantum dot precursor polymer solution is 100:1 to 100. The mass ratio of the quantum dot precursor material to the polymer matrix is ​​1:1 to 200.

[0033] Optionally, the spray drying process is achieved by a spray drying device with a two-fluid atomizer. The main process parameters include: solution feed rate: 50ml / h~50000ml / h; corresponding atomizer inlet pressure: 0.02~1MPa, inlet speed: 15L / min~100L / min; dryer inlet air temperature: 50~200℃.

[0034] Optionally, in step (b), the quantum dot / polymer composite microparticles coated with a protective layer are first vigorously stirred and evenly dispersed in a large amount of solvent, and fully stirred to obtain a powder mixed solution; a surfactant, a hydrolysis raw material, a catalyst, and deionized water are added to the mixed solution in sequence to allow a hydrolysis reaction to occur fully, at which point the surface of each powder particle is covered with a layer of product, which is coated with a dense protective layer.

[0035] Optionally, the protective layer raw material compound in step (b) includes at least one of an aluminum source compound, a silicon source compound, a titanium source compound, and a zirconium source compound;

[0036] Optionally, the mass ratio of the powder to the protective layer raw material compound is 1:0.1-100;

[0037] Optionally, the aluminum source compound includes at least one of triethylaluminum, aluminum sec-butoxide, and aluminum isopropoxide;

[0038] Optionally, the silicon source compound includes at least one of (3-mercaptopropyl)trimethoxysilane, bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, 3-aminopropyltriethoxysilane, methyl orthosilicate, ethyl orthosilicate, and octadecyltrimethoxysilane;

[0039] Optionally, the titanium source compound includes at least one of tetrabutyl titanate, isopropyl titanate, and tetraethyl titanate;

[0040] Optionally, the zirconium source compound includes at least one of zirconium n-butoxide, zirconium tert-butoxide, and zirconium isopropoxide.

[0041] Optionally, the catalyst includes at least one of methylamine, ammonia, and dimethylamine;

[0042] Optionally, the mass ratio of powder to catalyst is 1:0.1-10.

[0043] Optionally, the solution in step (b) further comprises a surfactant;

[0044] Optionally, the surfactant includes at least one of 6-mercaptohexanol, 1-hexadecanethiol, hexanethiol, oleic acid, and stearic acid;

[0045] Optionally, the mass ratio of the powder to the surfactant is 1:0.1-50.

[0046] Optionally, in step (b), a solution containing quantum dot / polymer composite particles, a protective layer raw material compound, a catalyst and water is reacted at a temperature of 20 to 50° C. and a stirring speed of 100 to 1000 rpm to obtain quantum dot / polymer composite particles coated with a protective layer;

[0047] Optionally, in step (b), the quantum dot / polymer composite particles coated with the protective layer are separated from the solution by suction filtration.

[0048] Optionally, the vacuum filtration step includes: cleaning the filtration bottle, assembling the filtration bottle and the vacuum pump, placing the filter membrane, pouring the mixed solution, starting filtration, and collecting powder.

[0049] Optionally, a pressure regulating valve is provided between the filtration bottle and the vacuum pump, which can adjust the vacuum degree and the filtration speed to ensure that the filtration speed is not too fast and causes damage to the filter membrane.

[0050] Optionally, an anti-backflow bottle is installed between the vacuum pump and the filtration bottle.

[0051] Optionally, the filter membrane is a microporous filter membrane with a pore size of 0.1 to 5 microns.

[0052] Optionally, in the atomic layer deposition of step (c), a compound raw material containing a metal element is reacted with an oxidant to form a metal oxide film;

[0053] Optionally, in step (c), the microparticles are first placed in a centrifugal rotatable cavity to maintain the powder in a continuously moving dispersed state; a compound containing metal elements is introduced into the cavity to fully react with the surface of the microparticles, and then an inert gas is introduced to remove excess compounds containing metal elements and byproducts; an oxidant is introduced into the cavity to fully react with the compound containing metal elements on the surface of the microparticles, and the two react to generate a first atomic layer. The operation is repeated, and the thickness of the oxide layer gradually increases until the surface coating process of the entire microparticle is completed.

[0054] Optionally, the compound raw material containing metal elements includes at least one of trimethylaluminum, aluminum trichloride, titanium tetrachloride, titanium isopropoxide, tetrakis(dimethylamino)zirconium, hafnium tetrachloride, hafnium nitrate, and dimethylaminozirconium;

[0055] Optionally, the oxide includes at least one of water, ozone, and oxygen plasma.

[0056] Optionally, the flow rates of the metal element-containing compound and the oxidant are 10 to 500 standard milliliters per minute, and the flow rate of the carrier gas is 10 to 1000 standard milliliters per minute.

[0057] Optionally, in each atomic layer deposition reaction, the reaction time of the metal element-containing compound and the oxidant with the particles is 0.1s to 10s, and the cavity outlet pressure is 50Pa to 500Pa.

[0058] Optionally, the flushing time after each reaction is 0.1s to 10s, and the flow rate of the flushing gas is 10 to 1000 standard milliliters per minute.

[0059] The beneficial effects that the present invention can produce include:

[0060] 1. The present invention uses a method for composite coating of perovskite quantum dots / polymer microspheres prepared by spray drying by using a two-layer coating method of solution coating and atomic layer deposition, which improves the water and oxygen barrier effect, enhances the stability and solvent resistance of perovskite quantum dot materials, and can be dispersed in multiple solvent systems. The two-layer coated perovskite quantum dots / polymer micropowders show ultra-high corrosion resistance and can be blended with various materials such as photoresists, UV adhesives, pressure-sensitive adhesives, and various organic solvents. Various processes such as dispensing, inkjet printing, screen printing, casting, and photolithography are used to prepare luminous materials in various forms such as luminous dots, lines, and films, which are applied to various fields such as display backlights, broadening the application range of quantum dot composite materials.

[0061] 2. The method for preparing perovskite quantum dots / polymer microspheres by spray drying in the present invention is simple in process and easy to prepare on an industrial scale. Moreover, the prepared powder and the polymer completely wrap the perovskite quantum dots to form a protective layer, thereby improving the stability of the perovskite quantum dot material. The solution coating in the present invention coats the powder surface with a protective layer through a hydrolysis reaction. After the perovskite quantum dots / polymer microspheres are coated with the protective layer, the defects on the surface of the microspheres can be significantly improved, a dense spherical shell can be formed, and the stability can be improved. At the same time, the solution coating makes the micropowders evenly dispersed, which is conducive to the subsequent atomic layer deposition coating and improves the coating rate. In addition, the solvents used for coating can be recycled, greatly reducing the production cost. The atomic layer deposition method in the present invention is widely used in the industry and has a mature process. The atomic layer deposition method can continue to deposit a nanometer-thick or submicron-thick metal oxide film on the surface of the evenly dispersed perovskite quantum dots / polymer microspheres to complete the surface coating process of the entire microsphere. The entire coating process does not affect the optical properties of the perovskite quantum dots / polymer microspheres themselves. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 Schematic diagram of the structure of the micropowder coated with perovskite quantum dots / polymer microspheres by two layers of solution coating and atomic layer deposition. 1 represents the perovskite quantum dots; 2 represents the polymer matrix, which completely encapsulates the perovskite quantum dots; 3 represents the protective layer coated by the solution method; 4 represents the nano- or submicron-scale oxide layer coated by atomic layer deposition;

[0063] Figure 2 It is a schematic diagram of the process flow of the present invention;

[0064] Figure 3 Photo of perovskite quantum dot polymer micropowder prepared by spray drying;

[0065] Figure 4 This is the fluorescence emission spectrum of the perovskite quantum dot polymer powder prepared by spray drying;

[0066] Figure 5 .Scanning electron microscope image of perovskite quantum dot polymer powder prepared by spray drying;

[0067] Figure 6 This is a scanning electron microscope image of the powder after atomic layer deposition coating;

[0068] Figure 7 This is a comparison curve of the brightness attenuation of uncoated and coated green micropowders with aging time. DETAILED DESCRIPTION

[0069] The present application is described in detail below with reference to the examples, but the present application is not limited to these examples. The materials used in the examples were purchased through commercial channels.

[0070] The SEM images were obtained using a Hitachi SU8220 cold field emission scanning electron microscope.

[0071] The fluorescence emission spectrum was obtained by using a spectrocolorimeter from Admesy, and the excitation light source was a 455nm blue LED.

[0072] Example 1

[0073] The structure of multi-layered quantum dot materials Figure 1 As shown, its preparation method is as follows Figure 2 As shown. In this embodiment, MAPbBr3 perovskite raw material and polymer polyvinylidene fluoride are selected for spray drying to prepare composite powder. The quantum dot material precursors MABr, PbBr2, and tetrapropylammonium bromide are dissolved in 200 ml of anhydrous N, N dimethylformamide (DMF) at a molar ratio of 0.6 mmol: 0.6 mmol: 0.3 mmol, and 10 g of polyvinylidene fluoride (PVDF) is added to form a perovskite quantum dot precursor polymer solution. After 2 hours of stirring and dissolving, spray drying is performed to prepare powder. The spray drying parameters are set as a solution feed rate of 500 ml / h, an air intake pressure of 0.08 MPa, an air intake rate of 60 L / min, and a dryer inlet air temperature of 85 degrees Celsius. The prepared perovskite / polymer microsphere powder is as shown Figure 3 As shown, the powder is bright green and its luminescence spectrum is Figure 4 As shown in Figure 2, the emission peak is located at 523nm. The scanning electron microscope photo of the perovskite quantum dot / polymer powder is shown in Figure 2. Figure 5 As shown in the figure, it can be seen that the micro powder is basically round in shape and distributed in micron size.

[0074] Weigh 10 g of powder, slowly pour it into 2000 ml of n-hexane, stir, and evenly disperse the powder in the solvent, add 10 mL of oleic acid, 0.1 mol of methyl orthosilicate, and 100 μL of water in sequence, then stir for 3 hours to fully hydrolyze, and obtain a solution-coated powder, then use a vacuum pump with a maximum vacuum degree of 0.1 MPa to perform vacuum filtration, separate the powder from the solvent, dry the residual solvent, and obtain a uniformly distributed powder. The vacuum filtration method of the subsequent embodiments is consistent.

[0075] Then, atomic layer deposition coating is performed. The powdered product is placed in a centrifugal holder, and the holder is controlled to rotate while being evacuated, and then the cavity is heated to 80-100 degrees Celsius; trimethylaluminum is introduced into the powder cavity for an adsorption time of 5 seconds, so that it can fully contact and adsorb with the powder surface, and then an inert gas is passed for 60 seconds to remove excess trimethylaluminum and by-products; water is introduced into the cavity for a reaction time of 5 seconds, and is allowed to fully react with the trimethylaluminum on the surface of the particles. At this time, the two precursors react to generate the first atomic layer. The operation is repeated, and the thickness of the oxide layer gradually increases until the surface coating process of the entire microsphere is completed. The scanning electron microscope photograph of the powder after coating is shown in FIG. Figure 6 As shown, it can be seen from the figure that the microspheres show a rough surface, which is the coated oxide layer.

[0076] The uncoated and double-coated green powders were loaded between two layers of glass and placed in an environmental test chamber at 60 degrees Celsius and 90% RH for aging experiments. After 240 hours of aging, the brightness decay is as follows: Figure 7 As shown in the figure, after 240 hours of aging, the brightness of the coated green micropowder decayed by only 5%, while the decay rate of the uncoated sample exceeded 15%. This proves that the two layers of oxide film coated on the surface of the perovskite / polymer microparticles significantly improved the stability of the material.

[0077] Example 2

[0078] In this embodiment, FAPbBr3 perovskite raw materials and polymer polymethyl methacrylate are selected for spray drying, and the quantum dot material precursors FABr, PbBr2, and tetrabutylammonium bromide are in a molar ratio of 0.7mmol: 0.6mmol: 0.3mmol, and the dryer temperature is 85 degrees Celsius to prepare perovskite quantum dot polymer composite powder. The prepared perovskite / polymer microsphere powder is bright green. Solution coating process: weigh 10g of powder, slowly pour it into 2000ml of n-hexane, stir, and evenly disperse the powder in the solvent, add 5mL oleic acid, 0.2mol3-aminopropyltriethoxysilane, and 200μL deionized water in turn, then stir for 3h to fully hydrolyze, and obtain a solution-coated powder, followed by filtration and drying of the residual solvent to obtain a uniformly distributed powder. Subsequently, the atomic layer deposition coating Al2O3 process is carried out to complete the surface coating process of the entire microsphere.

[0079] Example 3

[0080] In this embodiment, CsPbBr3 perovskite raw materials and polymer polyvinylidene fluoride are selected for spray drying, and the quantum dot material precursors CsBr, PbBr2, and dodecyl dimethyl benzyl ammonium bromide are used in a molar ratio of 0.6mmol: 0.6mmol: 0.4mmol, and the dryer temperature is 100 degrees Celsius to prepare perovskite quantum dot polymer composite powder. The prepared perovskite / polymer microsphere powder is bright green. Solution coating process: weigh 10g of powder, slowly pour it into 2000ml of n-hexane, stir, and evenly disperse the powder in the solvent, add 10mL of oleic acid, 0.5mol of tetrabutyl titanate, and 300μL of deionized water in turn, then stir for 5h to fully hydrolyze, and obtain a solution-coated powder, followed by filtration and drying of the residual solvent to obtain a uniformly distributed powder. Subsequently, the atomic layer deposition coating TiO2 process is carried out to complete the surface coating process of the entire microsphere.

[0081] Example 4

[0082] In this example, MA is selected 0.9 Cs 0.1PbBr3 perovskite raw materials and polymers, polymer polyvinylidene fluoride and polymethyl methacrylate were mixed and spray dried. The quantum dot material precursors MABr, CsBr, PbBr2, and octylamine bromide were mixed at a molar ratio of 0.6mmol: 0.1mmol: 0.6mmol: 0.18mmol, and the dryer temperature was 90 degrees Celsius to prepare perovskite quantum dot polymer composite powder. The prepared perovskite / polymer microsphere powder was bright green. Solution coating process: weigh 10g of powder, slowly pour it into 2000ml of n-hexane, stir, and evenly disperse the powder in the solvent, add 0.3mol of ethyl orthosilicate in turn, and then stir it open for 5h to fully hydrolyze, obtain solution-coated powder, and then filter and dry the residual solvent to obtain a uniformly distributed powder. Then, the atomic layer deposition ZrO2 coating process is carried out to complete the surface coating process of the entire microsphere.

[0083] Example 5

[0084] In this example, MA is selected 0.8 FA 0.2 The PbBr3 perovskite raw material and the polymer polymethyl methacrylate were spray dried, and the quantum dot material precursors MABr, FABr, PbBr2, and tetraoctylammonium bromide were prepared at a molar ratio of 0.48mmol: 0.12mmol: 0.6mmol: 0.3mmol, and the dryer temperature was 90 degrees Celsius to prepare the perovskite quantum dot polymer composite powder. The prepared perovskite / polymer microsphere powder was bright green. Solution coating process: weigh 10g of powder, slowly pour it into 2000ml of n-hexane, stir, and evenly disperse the powder in the solvent, add 5mL of stearic acid, 0.5mol of zirconium n-butoxide, and 400μL of deionized water in turn, then stir open for 5h to fully hydrolyze, obtain the solution-coated powder, and then filter and dry the residual solvent to obtain a uniformly distributed powder. Then, the atomic layer deposition coating Al2O3 process is carried out to complete the surface coating process of the entire microsphere.

[0085] Example 6

[0086] In this embodiment, MAPbI3 perovskite raw materials and polymer polymethyl methacrylate are selected for spray drying, and the quantum dot material precursors MAI, PbI2, and tetrabutylammonium iodide are used in a molar ratio of 0.6mmol: 0.6mmol: 0.3mmol, and the dryer temperature is 120 degrees Celsius to prepare perovskite quantum dot polymer composite powder. The prepared perovskite / polymer microsphere powder is bright red. Solution coating process: weigh 10g of powder, slowly pour it into 2000ml of n-hexane, stir, and evenly disperse the powder in the solvent, add 10mL of hexanethiol and 0.2mol of ethyl orthosilicate in turn, and then stir in an open state for 3h to fully hydrolyze to obtain a solution-coated powder, and then filter and dry the residual solvent to obtain a uniformly distributed powder. Subsequently, the atomic layer deposition coating Al2O3 process is carried out to complete the surface coating process of the entire microsphere.

[0087] Example 7

[0088] In this embodiment, MAPb(Br / I)3 perovskite raw materials and polymer polymethyl methacrylate are selected for spray drying, and the quantum dot material precursors MAI, PbI2, octylamine iodine, and hydrobromic acid are in a molar ratio of 0.6mmol: 0.6mmol: 0.3mmol: 0.3mmol, and the dryer temperature is 110 degrees Celsius to prepare perovskite quantum dot polymer composite powder. The prepared perovskite / polymer microsphere powder is bright red. Solution coating process: weigh 10g of powder, slowly pour it into 2000ml of n-hexane, stir, and evenly disperse the powder in the solvent, add 10mL of oleic acid and 0.5mol of ethyl orthosilicate in turn, and then stir in an open state for 3h to fully hydrolyze, and obtain a solution-coated powder, and then filter and dry the residual solvent to obtain a uniformly distributed powder. Then, the atomic layer deposition coating TiO2 process is carried out to complete the surface coating process of the entire microsphere.

[0089] Example 8

[0090] In this embodiment, CsPbI3 perovskite raw materials and polymer polymethyl methacrylate are selected for spray drying, and the quantum dot material precursors CsI, PbI2, and octylamine iodine are in a molar ratio of 0.6mmol: 0.6mmol: 0.3mmol, and the dryer temperature is 120 degrees Celsius to prepare perovskite quantum dot polymer composite powder. The prepared perovskite / polymer microsphere powder is bright red. Solution coating process: weigh 10g of powder, slowly pour it into 2000ml of n-hexane, stir, and evenly disperse the powder in the solvent, add 20ml oleic acid and 0.5mol3-aminopropyltriethoxysilane in turn, and then stir in an open state for 5h to fully hydrolyze, and obtain a solution-coated powder, and then filter and dry the residual solvent to obtain a uniformly distributed powder. Then, the atomic layer deposition coating Al2O3 process is carried out to complete the surface coating process of the entire microsphere.

[0091] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a multi-layer coated quantum dot material, characterized in that: The steps include: Step (a) obtaining quantum dot / polymer composite particles; Step (b) reacting a solution containing quantum dot / polymer composite particles, a protective layer raw material compound, a catalyst and water to obtain quantum dot / polymer composite particles coated with a protective layer; Step (c) forming a metal oxide film on the quantum dot / polymer composite particles coated with a protective layer obtained in step (b) by atomic layer deposition; The quantum dots in step (a) are perovskite quantum dots; The polymer in step (a) includes at least one of polyvinylidene fluoride, polyvinylidene fluoride and trifluoroethylene copolymer, polyacrylonitrile, polyvinyl acetate, cellulose acetate, cyanocellulose, polysulfone, aromatic polyamide, polyimide, polycarbonate, polystyrene, polymethyl methacrylate, and polylauryl methacrylate; The quantum dot / polymer composite particles in step (a) are prepared by spray drying; The protective layer raw material compound in step (b) is silicon dioxide and / or amphoteric hydroxide; The catalyst in step (b) comprises at least one of methylamine, aqueous ammonia and dimethylamine; In step (b), the mass ratio of quantum dots / polymer composite particles to the protective layer raw material compound is 1:0.1-100; In step (b), the mass ratio of quantum dots / polymer composite particles to catalyst is 1:0.1-10; In step (b), the reaction is carried out at a temperature of 20 to 50° C. and a stirring speed of 100 to 1000 rpm; In the step (c) of atomic layer deposition, a compound raw material containing a metal element is reacted with an oxidant to form a metal oxide film; The metal oxide film includes at least one of an Al2O3 film, a TiO2 film, a HfO2 film, and a ZrO2 film.

2. The preparation method according to claim 1, characterized in that: The protective layer raw material compound in step (b) includes at least one of an aluminum source compound, a silicon source compound, a titanium source compound, and a zirconium source compound.

3. The preparation method according to claim 2, characterized in that: The aluminum source compound includes at least one of triethylaluminum, aluminum sec-butoxide, and aluminum isopropoxide.

4. The preparation method according to claim 2, characterized in that: The silicon source compound includes at least one of (3-mercaptopropyl)trimethoxysilane, bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, 3-aminopropyltriethoxysilane, methyl orthosilicate, ethyl orthosilicate, and octadecyltrimethoxysilane.

5. The preparation method according to claim 2, characterized in that: The titanium source compound includes at least one of tetrabutyl titanate, isopropyl titanate, and tetraethyl titanate.

6. The preparation method according to claim 2, characterized in that: The zirconium source compound includes at least one of zirconium n-butoxide, zirconium tert-butoxide, and zirconium isopropoxide.

7. The preparation method according to claim 1, characterized in that: The quantum dots are perovskite quantum dots, and the raw materials for synthesizing the perovskite quantum dots include AX, BX m and a CX precursor; wherein A is selected from NH2CHNH2 + (FA + )、CH3NH3 + (MA + )、Cs + , Rb + , K + At least one of; B is selected from Pb 2+ Sn 2+ 、Bi 3+ 、Ti 3+ 、Zn 2+ 、Ni 2+ 、Cd 2+ 、Al 3+ , Mn 2+ , Mn 4+ ,Ge 3+ At least one of; C is selected from an aromatic group or an alkyl organic amine cation having a carbon number of not less than 3; X is selected from Br - ,I - 、SCN - , carboxylate; m=2, 3 or 4.

8. The preparation method according to claim 7, characterized in that: The perovskite quantum dot precursors AX and BX m The molar ratio of CX is 0.5~10: 1: 0.5~10.

9. The preparation method according to claim 1, characterized in that: The raw material of the spray drying method is a perovskite quantum dot precursor polymer solution, and the solvent in the perovskite quantum dot precursor polymer solution includes at least one of dimethyl sulfoxide, n-hexane, cyclohexane, n-octane, octadecene, ethanol, methanol, trimethyl phosphate, triethyl phosphate, N-methylpyrrolidone, dimethylacetamide, N,N-dimethylformamide, isopropanol, ethyl acetate, toluene, and acetone.

10. The preparation method according to claim 9, characterized in that: The mass ratio of the solvent to the polymer matrix in the perovskite quantum dot precursor polymer solution is 100:1-100; the mass ratio of the quantum dot precursor material to the polymer matrix is ​​1:1-200.

11. The preparation method according to claim 1, characterized in that: The spray drying method is achieved by a spray drying device with a two-fluid atomizer; the process parameters of the spray drying include: solution feed rate: 50 ml / h~50000 ml / h; corresponding atomizer inlet pressure: 0.02~1 MPa, inlet speed: 15 L / min~100 L / min; dryer inlet air temperature: 50~200 °C.

12. The preparation method according to claim 1, characterized in that: The solution in step (b) further comprises a surfactant.

13. The preparation method according to claim 12, characterized in that: The surfactant includes at least one of 6-mercaptohexanol, 1-hexadecanethiol, hexanethiol, oleic acid, and stearic acid.

14. The preparation method according to claim 12, characterized in that: The mass ratio of quantum dots / polymer composite particles to surfactant is 1:0.1~50.

15. The preparation method according to claim 1, characterized in that: In step (b), the quantum dot / polymer composite particles coated with the protective layer are separated from the solution by suction filtration.

16. The preparation method according to claim 1, characterized in that: The compound raw material containing metal elements includes at least one of trimethylaluminum, aluminum trichloride, titanium tetrachloride, titanium isopropoxide, tetrakis(dimethylamino)zirconium, hafnium tetrachloride, hafnium nitrate, and dimethylaminozirconium.

17. The preparation method according to claim 1, characterized in that: The oxidant includes at least one of water, ozone and oxygen plasma.

18. A multi-layer coated quantum dot material, characterized in that: The multi-layer coated quantum dot material includes quantum dot / polymer composite particles, a protective layer and a metal oxide film; The protective layer covers the quantum dot / polymer composite particles; The metal oxide film is coated with a protective layer; The protective layer is silicon dioxide and / or amphoteric hydroxide; The amphoteric hydroxide includes at least one of aluminum hydroxide, titanium hydroxide, and zirconium hydroxide; The multi-layer coated quantum dot material is obtained by the preparation method described in any one of claims 1 to 17.

19. The multi-layer coated quantum dot material according to claim 18, characterized in that: The particle size of the quantum dot / polymer composite particles is 1-100 μm; The thickness of the protective layer is 10-500 nm; The thickness of the metal oxide film coating protective layer is 1nm to 100nm.

20. The multi-layer coated quantum dot material according to claim 18, characterized in that: The protection layer quantum dot / polymer composite particles include a spatial network structure formed by a polymer, and the quantum dots are embedded in the spatial network structure.

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