CN115852333A - A kind of multi-layer coated quantum dot material and preparation method thereof - Google Patents

Abstract

The present application discloses a multilayer coated quantum dot material and a preparation method thereof. The multilayer coated quantum dot material includes quantum dot/polymer composite particles, and the surface of the quantum dot/polymer composite particle is coated There is a protective layer, and the outer side of the protective layer is coated with a metal oxide film. After the perovskite quantum dots/polymer microspheres are coated with a protective layer, it can significantly improve the defects on the surface of the microspheres, form a dense spherical shell, and at the same time disperse the micropowder evenly, which is beneficial to the subsequent atomic layer deposition coating. The coated perovskite quantum dots/polymer micropowders have excellent luminescent 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 dots/polymer micropowders , the method is simple, has the advantages of low preparation cost and maintaining the optical properties of the powder.

Description

A kind of multi-layer coated quantum dot material and preparation method thereof

technical field

The application relates to a multilayer coated quantum dot material and a preparation method thereof, which belong to the field of display technology.

Background technique

Perovskite quantum dots have excellent characteristics such as simple preparation process, low cost, high quantum yield, and high color purity, which can greatly improve the display color gamut of display devices, so they have received extensive attention. At present, the in-situ preparation of luminescent films based on perovskite quantum dots has successfully achieved commercial application in the display field, which can increase the color gamut to above 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 in long-term stability in practical applications. The most important reason for the poor long-term stability of perovskite quantum dot materials is the intrusion of water and oxygen in the actual environment, which leads to 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.

In the synthesis methods of perovskite quantum dots that have been reported so far, including methods such as hot injection method, there is a problem that a large amount of solvents and additives are used in the synthesis methods, resulting in waste of raw materials; and it is necessary to provide high temperature or high temperature and high pressure during synthesis. Environment, multiple cleaning steps are required after synthesis to obtain quantum dots. The process is cumbersome and a large amount of solvent is wasted, which is not conducive to large-scale preparation; in addition, the traditional synthesis method is to prepare quantum dots first, and then follow-up to improve stability. Treatment, such as inorganic shell coating, organic polymer coating and other processes, the by-products produced in these processes will cause the ligands on the surface of quantum dots to fall off, affecting the optical properties and stability of quantum dots, and the post-treatment process again A large amount of solvent is used, and the purification process is still complicated and cumbersome, requiring steps such as drying and grinding, which is not conducive to large-scale use. Therefore, new fabrication and surface treatment techniques are crucial to improve the stability of PQDs.

Contents of the invention

In order to solve the above problems, the present invention provides a two-layer coating treatment technology of perovskite quantum dots/polymer composite micropowders, including solution coating and atomic layer deposition of perovskite quantum dots/polymer composite micropowders clad. This technology first uses the spray drying method to prepare perovskite quantum dots/polymer luminescent microspheres, which can realize the preparation of quantum dots and the coating of polymers in one step. The process is simple and stable, and it is far superior to the process of liquid phase synthesis of quantum dots. . After the perovskite quantum dots/polymer microspheres are obtained, a protective layer is evenly coated on the surface of the microspheres by the method of solution coating, so that the particles of the microspheres are uniformly dispersed. Finally, through atomic layer deposition technology, a layer of dense inorganic oxide is deposited on the surface of uniformly dispersed particles to prevent the intrusion of water and oxygen, thereby improving the stability of perovskite quantum dots/polymer micropowders. The spray preparation technology of perovskite quantum dots/polymer luminescent microspheres and the two-layer coating composite material of the present invention avoids the waste of resources and complicated synthesis procedures of the traditional liquid phase synthesis method, and effectively and uniformly synthesizes the polymer The coating process and the subsequent two-layer coating process improve the stability of the luminescent micropowder and promote the commercial application of perovskite quantum dots.

As one aspect of the present application, the present application provides a multi-layer coated quantum dot material. In the invention of this application, the method of composite coating the perovskite quantum dots/polymer microspheres prepared by spray drying by using the method of solution coating and atomic layer deposition two-layer coating can improve the effect of water blocking and oxygen blocking, and increase the calcium The stability and solvent resistance of titanium ore quantum dot materials 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 photoresists, UV adhesives, pressure-sensitive adhesives, and various organic solvents. Glue, inkjet printing, screen printing, casting, photolithography and other processes to prepare luminescent materials in various forms such as dots, lines, films, etc. Applications of composite materials.

A multilayer coated quantum dot material, the multilayer coated quantum dot material includes quantum dots/polymer composite particles, the surface of the quantum dots/polymer composite particles is coated with a protective layer, and the protective layer The outside is coated with a metal oxide film.

Optionally, the quantum dot/polymer composite particle of the protective layer includes a spatial network structure formed by a polymer, and the quantum dots are embedded in the spatial network structure;

Optionally, the quantum dots are perovskite quantum dots;

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

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

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

Optionally, _the metal oxide film includes at least one of _Al2O3 film, _TiO2 film, _HfO2 film, _ZrO2 film;

Optionally, the particle size of the quantum dot/polymer composite particle is 1-100 μm;

The thickness of the protective layer is 10-500nm;

The thickness of the protective layer covered by the metal oxide film is 1nm-100nm.

As another aspect of the present application, the present application also provides a method for preparing a multilayer coated quantum dot material. In the present application, the spray drying method for preparing perovskite quantum dots/polymer microspheres has a simple process. It is easy to industrially prepare on a large scale, and the prepared powder and polymer completely wrap the perovskite quantum dots to form a protective layer, which improves the stability of the perovskite quantum dot material. The solution method coating in the invention of the present application is to coat 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, forming a dense The spherical shell improves the stability; at the same time, the solution method coating makes the micro powder evenly dispersed, which is beneficial to the subsequent atomic layer deposition coating and improves the coating rate. All the solvents used in coating can be recycled, which greatly reduces the production cost. The method of atomic layer deposition in the invention of the present application is widely used in the industry, and the process is mature. The method of atomic layer deposition can continue to deposit nanometer thickness or submicron on the surface of uniformly dispersed perovskite quantum dots/polymer microspheres The thickness of the metal oxide film completes 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.

A method for preparing a multilayer coated quantum dot material, comprising the steps of:

(a) obtaining quantum dot/polymer composite particles;

(b) reacting the solution containing the quantum dot/polymer composite particle, the protective layer raw material compound and the catalyst to obtain the quantum dot/polymer composite particle coated with the protective layer;

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

Optionally, in the step (a), the perovskite quantum dot precursor polymer solution forms atomized micro-droplets from the two-fluid atomizer through the infusion pipeline and enters the drying tower, and passes through the hot air blown in from the air inlet. After drying, perovskite quantum dots/polymer microspheres are formed, and the perovskite quantum dot polymer micropowder enters the cyclone separator through the air outlet below the drying tank to realize powder collection.

Optionally, Quantum uses perovskite quantum dots.

Optionally, raw materials for the synthesis of perovskite quantum dots include AX, BX _t and CX precursors; wherein, A is selected from NH ₂ CHNH ₂ ⁺ (FA ⁺ ), CH ₃ NH ₃ ⁺ (MA ⁺ ), Cs ⁺ , Rb ⁺ , at least one of K ⁺ ; B is selected from Pb ²⁺ , Sn ²⁺ , Bi ³⁺ , Ti ³⁺ , Zn ²⁺ , Ni ²⁺ , Cd ²⁺ , Al ³⁺ , Mn ²⁺ , Mn At least one of ⁴⁺ and Ge ³⁺ ; C is selected from aromatic groups or alkyl organic amine cations with not less than 3 carbon atoms; X is selected from at least one of Br ^- , I ^- , SCN ^- and carboxylate ;m=2, 3 or 4;

Optionally, the perovskite quantum dot has at least one of the structural formulas AMX ₃ , A ₃ M ₂ X ₉ , A ₂ MX ₆ , Q ₂ A _m-1 M _m X _3m+1 ;

Wherein, A is at least one of NH ₂ CHNH ₂ ⁺ , CH ₃ NH ₃ ⁺ , and Cs ⁺ ;

M is at least one of Pb ²⁺ , Cd ²⁺ , Mn ²⁺ , Zn ²⁺ , Sn ²⁺ , Ge ²⁺ , Bi ³⁺ ;

X is at least one of the halide anions;

Q is an aromatic group or an alkyl organic amine cation with not less than 3 carbon atoms;

m is any value between 1 and 100.

Optionally, the molar ratio of the perovskite quantum dot precursors AX, BX _m and CX is 0.5-10:1:0.5-10;

Optionally, the solvent includes dimethyl sulfoxide, n-hexane, cyclohexane, n-octane, octadecene, ethanol, methanol, trimethyl phosphate, triethyl phosphate, N-methyl At least one of pyrrolidone, dimethylacetamide, N,N-dimethylformamide, isopropanol, ethyl acetate, toluene, and acetone.

Optionally, 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.

Optionally, the spray drying process is realized by spray drying equipment 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; Wind temperature: 50～200℃.

Optionally, in the step (b), the quantum dots/polymer composite particles coated with the protective layer are vigorously stirred and evenly dispersed in a large amount of solvent, and fully stirred to obtain a powder mixed solution; Active agent, hydrolysis raw material, catalyst, and deionized water fully undergo hydrolysis reaction. At this time, the surface of each powder particle is covered with a layer of product, covering a dense protective layer.

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

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

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

Optionally, the silicon source compound includes (3-mercaptopropyl)trimethoxysilane, bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, 3-aminopropyltriethyl At least one of oxysilane, methyl orthosilicate, ethyl orthosilicate, octadecyltrimethoxysilane;

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

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

Optionally, the catalyst includes at least one of methylamine, ammonia water, and dimethylamine;

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

Optionally, the solution in the step (b) also includes a surfactant;

Optionally, the surfactant includes at least one of 6-mercaptohexanol, 1-hexadecanthiol, hexanethiol, oleic acid, and stearic acid;

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

Optionally, in the step (b), the solution containing the quantum dot/polymer composite particle, the protective layer raw material compound, the catalyst and water is heated at a temperature of 20-50°C and a stirring speed of 100-1000 rpm. The reaction is carried out to obtain quantum dots/polymer composite particles coated with a protective layer;

Optionally, in the step (b), the quantum dot/polymer composite particle coated with the protective layer is separated from the solution by suction filtration.

Optionally, the step of vacuum filtration includes: cleaning the filtration flask, assembling the filtration flask and a vacuum pump, placing the filter membrane, pouring the mixed solution, starting the suction filtration, and collecting the powder.

Optionally, there is a pressure regulating valve between the suction filtration bottle and the vacuum pump, which can adjust the vacuum degree and suction filtration speed, so as to ensure that the suction filtration speed will not be too fast, causing damage to the filter membrane.

Optionally, an anti-suckback bottle is installed between the vacuum pumps and the filter bottles.

Optionally, the filter membrane refers to a microporous filter membrane with a pore size of 0.1-5 microns.

Optionally, in the step (c) atomic layer deposition, a metal element-containing compound raw material is used to react with an oxidant to form a metal oxide film;

Optionally, in the step (c), the particles are firstly placed in a centrifuge rotatable cavity to maintain the continuous movement and dispersion of the powder; a compound containing metal elements is introduced into the cavity to fully react with the surface of the particles, and then pass The inert gas removes excess metal element-containing compounds and by-products; the oxidant is introduced into the chamber to fully react with the metal element-containing compound on the particle surface, and the two react to form the first atomic layer. The operation is repeated, and the thickness of the oxide layer is gradually increased until the surface coating process of the entire particle is completed.

Optionally, the raw material of the metal element-containing compound includes trimethylaluminum, aluminum trichloride, titanium tetrachloride, titanium isopropoxide, zirconium tetrakis (dimethylamino) base, hafnium tetrachloride, hafnium nitrate , at least one of zirconium dimethylamide;

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

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

Optionally, in each atomic layer deposition reaction, the reaction time of the metal element-containing compound, the oxidizing agent and the particles is 0.1s-10s, and the chamber outlet pressure is 50Pa-500Pa.

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

The beneficial effects that the present invention can produce include:

1. In the invention of this application, the method of composite coating of perovskite quantum dots/polymer microspheres prepared by spray drying by using solution method coating and atomic layer deposition two-layer coating method improves the effect of water blocking and oxygen blocking, Improve the stability and solvent resistance of perovskite quantum dot materials, which 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 photoresists, UV adhesives, pressure-sensitive adhesives, and various organic solvents. Glue, inkjet printing, screen printing, casting, photolithography and other processes to prepare luminescent materials in various forms such as dots, lines, films, etc. Applications of composite materials.

2. The method for preparing perovskite quantum dots/polymer microspheres by spray drying in the invention of this application has a simple process and is easy to produce on a large scale in industry, and the prepared powder and polymer completely wrap the perovskite quantum dots to form a protective layer, improving the stability of the perovskite quantum dot material. The solution method coating in the invention of the present application is to coat 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, forming a dense The spherical shell improves the stability; at the same time, the solution method coating makes the micro powder evenly dispersed, which is beneficial to the subsequent atomic layer deposition coating and improves the coating rate. In addition, the solvent used for coating can be recycled, which greatly reduces the production cost. The atomic layer deposition method in the invention of the present application is widely used in the industry, and the process is mature. The atomic layer deposition method can continue to deposit nanometer-thick or submicron-thick metal oxide films on the surface of uniformly dispersed perovskite quantum dots/polymer microspheres to complete the surface coating process of the entire microspheres. The entire coating process does not affect the optical properties of the perovskite quantum dots/polymer microspheres themselves.

Description of drawings

Figure 1 is a schematic diagram of the structure of a micropowder coated with two layers of perovskite quantum dots/polymer microspheres by solution coating and atomic layer deposition. Among them, 1 represents perovskite quantum dots; 2 represents polymer matrix, and the polymer matrix completely wraps perovskite quantum dots; 3 represents the protective layer coated by solution method; 4 represents nanometer or submicron quantum dots coated by atomic layer deposition. oxide layer;

Fig. 2 is the technological process schematic diagram of the present invention;

Fig. 3 is the photo of the perovskite quantum dot polymer micropowder prepared by spray drying;

Fig. 4 is the fluorescence emission spectrogram of the perovskite quantum dot polymer micropowder prepared by spray drying;

Fig. 5. is the scanning electron microscope picture of the perovskite quantum dot polymer micropowder prepared for spray drying;

Figure 6 is a scanning electron microscope picture of the powder coated by atomic layer deposition;

Fig. 7 is a comparison curve of decay of brightness with aging time based on uncoated and coated green micropowders.

Detailed ways

The present application is described in detail below in conjunction with the examples, but the present application is not limited to these examples. All materials used in the examples were purchased from commercial sources.

SEM photos were obtained by Hitachi SU8220 cold field emission scanning electron microscope.

The fluorescence emission spectrum is obtained by testing with a spectrocolorimeter of Admesy Company, and the excitation light source is a blue LED with a wavelength of 455 nm.

Example 1

The structure of the multilayer coated quantum dot material is shown in FIG. 1 , and its preparation method is shown in FIG. 2 . In this example, MAPbBr ₃ perovskite raw material and polymer polyvinylidene fluoride were selected for spray drying to prepare composite powder. The quantum dot material precursor MABr, PbBr ₂ , tetrapropylammonium bromide are dissolved in the anhydrous N, N dimethylformamide (DMF) of 200ml with the ratio of molar ratio 0.6mmol: 0.6mmol: 0.3mmol, and then 10 g of polyvinylidene fluoride (PVDF) was added to form a perovskite quantum dot precursor polymer solution, and after stirring and dissolving for 2 hours, spray drying was carried out to prepare powder. The spray-drying parameters were set to be 500ml/h for the feed rate of the solution, 0.08MPa for the inlet pressure, 60L/min for the inlet speed, and 85°C for the dryer inlet air temperature. The prepared perovskite/polymer microsphere powder is shown in Figure 3, the powder is bright green, and its luminescence spectrum is shown in Figure 4, with a luminescence peak at 523nm. At this time, the scanning electron microscope photo of the perovskite quantum dot/polymer powder is shown in Figure 5. It can be seen from the figure that the micropowder basically presents a circular shape and a micron size distribution.

Weigh 10g of powder, slowly pour it into 2000ml of n-hexane, stir, disperse the powder evenly in the solvent, add 10mL of oleic acid, 0.1mol of orthosilicate, 100μL of water in sequence, and then stir for 3h to fully hydrolyze to obtain the solution method The coated powder was then subjected to vacuum filtration using a vacuum pump with a maximum vacuum degree of 0.1 MPa to separate the powder from the solvent, and dry the residual solvent to obtain a uniformly distributed powder. The vacuum filtration methods in the subsequent examples were all the same.

Subsequent atomic layer deposition cladding. Put the powdered product into the centrifugal holder, vacuumize while controlling the rotation of the holder, and then heat the cavity to 80-100 degrees Celsius; pass trimethylaluminum into the powder cavity, and the adsorption time is 5 seconds. Make it fully contact with the surface of the powder for adsorption, and then pass an inert gas to remove excess trimethylaluminum and by-products for 60 seconds; pass water into the cavity, the reaction time is 5 seconds, and make it fully contact with the trimethylaluminum on the particle surface reaction, where the two precursors react to form the first atomic layer. The operation is repeated, and the thickness of the oxide layer is gradually increased until the surface coating process of the entire microsphere is completed. The scanning electron micrograph of the coated powder is shown in Fig. 6. From the figure, it can be seen that the microspheres show a rough surface, which is the coated oxide layer.

The uncoated and double-coated green powders were loaded in the interlayer of two layers of glass, and placed in an environmental test chamber at 60 degrees Celsius and 90% RH humidity for aging experiments. After 240 hours of aging, its brightness attenuation is shown in Figure 7. After 240 hours of aging, the coated green micropowder has a luminance attenuation of only 5%, while the attenuation ratio of the uncoated sample has exceeded 15%. It is proved that the perovskite/polymer particles are coated with two oxide films on the surface, which significantly improves the stability of the material.

Example 2

In this example, FAPbBr ₃ perovskite raw materials and polymer polymethyl methacrylate are selected for spray drying, and the quantum dot material precursors FABr, PbBr ₂ , and tetrabutylammonium bromide are used in a molar ratio of 0.7mmol: 0.6mmol: 0.3 mmol, the temperature of the dryer is 85 degrees Celsius, and the perovskite quantum dot polymer composite powder is prepared. The prepared perovskite/polymer microsphere powder is bright green in color. Coating process of solution method: Weigh 10g powder, slowly pour it into 2000ml n-hexane, stir, disperse the powder evenly in the solvent, add 5mL oleic acid, 0.2mol 3-aminopropyltriethoxysilane, 200μL to Ionized water, followed by stirring for 3 hours to fully hydrolyze to obtain a solution-coated powder, followed by suction filtration and drying of the residual solvent to obtain a uniformly distributed powder. Subsequently, the process of coating Al ₂ O ₃ by atomic layer deposition is carried out to complete the surface coating treatment process of the entire microsphere.

Example 3

In this example, CsPbBr ₃ perovskite raw material and polymer polyvinylidene fluoride are selected for spray drying, and the quantum dot material precursors CsBr, PbBr ₂ , and dodecyldimethylbenzyl ammonium bromide are in a molar ratio of 0.6mmol: 0.6mmol: 0.4mmol, the temperature of the dryer is 100 degrees Celsius, and the perovskite quantum dot polymer composite powder is prepared. The prepared perovskite/polymer microsphere powder is bright green in color. Coating process of solution method: Weigh 10g of powder, slowly pour it into 2000ml of n-hexane, stir, disperse the powder in the solvent evenly, add 10mL of oleic acid, 0.5mol of tetrabutyl titanate, 300μL of deionized water in sequence, and then Stir for 5 hours to fully hydrolyze to obtain a solution-coated powder, and then filter and dry the residual solvent to obtain a uniformly distributed powder. Subsequent atomic layer deposition coating TiO ₂ process is carried out to complete the surface coating process of the entire microsphere.

Example 4

In this example, MA _0.9 Cs _0.1 PbBr ₃ perovskite raw material and polymer, polymer polyvinylidene fluoride and polymethyl methacrylate are selected for spray drying. Quantum dot material precursor MABr, CsBr, PbBr ₂ , octane The perovskite quantum dot polymer composite powder was prepared with amine bromide at a molar ratio of 0.6mmol: 0.1mmol: 0.6mmol: 0.18mmol, and a dryer temperature of 90 degrees Celsius. The prepared perovskite/polymer microsphere powder is bright green in color. Coating process of solution method: Weigh 10g of powder, slowly pour it into 2000ml of n-hexane, stir, disperse the powder in the solvent evenly, add 0.3mol tetraethyl orthosilicate in sequence, then stir in the open for 5 hours to fully hydrolyze to obtain a solution The powder coated by the method was then suction filtered and dried to obtain a uniformly distributed powder. Subsequent atomic layer deposition coating ZrO ₂ process is carried out to complete the surface coating treatment process of the entire microsphere.

Example 5

In this embodiment, MA _0.8 FA _0.2 PbBr ₃ perovskite raw materials and polymer polymethyl methacrylate _are selected for spray drying. mmol: 0.12mmol: 0.6mmol: 0.3mmol, the temperature of the dryer is 90 degrees Celsius, and the perovskite quantum dot polymer composite powder is prepared. The prepared perovskite/polymer microsphere powder is bright green in color. Coating process of solution method: Weigh 10g of powder, slowly pour it into 2000ml of n-hexane, stir, disperse the powder in the solvent evenly, add 5mL of stearic acid, 0.5mol of zirconium n-butoxide, 400μL of deionized water in sequence, and then Open and stirred for 5 hours to fully hydrolyze to obtain a solution-coated powder, and then through suction filtration and drying of the residual solvent to obtain a uniformly distributed powder. Subsequently, the process of coating Al ₂ O ₃ by atomic layer deposition is carried out to complete the surface coating treatment process of the entire microsphere.

Example 6

In this embodiment, MAPbI ₃ perovskite raw materials and polymer polymethyl methacrylate are selected for spray drying, and the quantum dot material precursors MAI, PbI ₂ , and tetrabutylammonium iodide are used in a molar ratio of 0.6mmol: 0.6mmol: 0.3 mmol, the temperature of the dryer is 120 degrees Celsius, and the perovskite quantum dot polymer composite powder is prepared. The prepared perovskite/polymer microsphere powder is bright red. Coating process of solution method: Weigh 10g of powder, slowly pour it into 2000ml of n-hexane, stir, disperse the powder in the solvent evenly, add 10mL of hexanethiol, 0.2mol of ethyl orthosilicate in sequence, and then stir for 3h Fully hydrolyzed to obtain a solution-coated powder, followed by suction filtration and drying of the residual solvent to obtain a uniformly distributed powder. Subsequently, the process of coating Al ₂ O ₃ by atomic layer deposition is carried out to complete the surface coating treatment process of the entire microsphere.

Example 7

In this embodiment, MAPb(Br/I) ₃ perovskite raw materials and polymer polymethyl methacrylate are selected for spray drying, and the quantum dot material precursor MAI, PbI ₂ , octylamine iodine, and hydrobromic acid are mixed at a molar ratio of 0.6 mmol: 0.6mmol: 0.3mmol: 0.3mmol, the temperature of the dryer is 110 degrees Celsius, and the perovskite quantum dot polymer composite powder is prepared. The prepared perovskite/polymer microsphere powder is bright red. Coating process of solution method: Weigh 10g of powder, slowly pour it into 2000ml of n-hexane, stir, disperse the powder in the solvent evenly, add 10mL of oleic acid, 0.5mol ethyl orthosilicate in sequence, and then stir for 3 hours in the open to fully Hydrolyzed to obtain solution-coated powder, followed by suction filtration and drying of residual solvent to obtain evenly distributed powder. Subsequent atomic layer deposition coating TiO ₂ process is carried out to complete the surface coating process of the entire microsphere.

Example 8

In this embodiment, CsPbI ₃ perovskite raw materials and polymer polymethyl methacrylate are selected for spray drying. Quantum dot material precursors CsI, PbI ₂ , and octylamine iodine are dried at a molar ratio of 0.6mmol:0.6mmol:0.3mmol. The temperature of the device is 120 degrees Celsius, and the perovskite quantum dot polymer composite powder is prepared. The prepared perovskite/polymer microsphere powder is bright red. Coating process of solution method: Weigh 10g of powder, slowly pour it into 2000ml of n-hexane, stir, disperse the powder in the solvent evenly, add 20ml of oleic acid, 0.5mol of 3-aminopropyltriethoxysilane in sequence, and then open Stirring for 5 hours to fully hydrolyze to obtain a solution-coated powder, and then through suction filtration and drying of the residual solvent to obtain a uniformly distributed powder. Subsequently, the process of coating Al ₂ O ₃ by atomic layer deposition is carried out to complete the surface coating treatment process of the entire microsphere.

The above are only a few embodiments of the application, and do not limit the application in any form. Although the application is disclosed as above with preferred embodiments, it is not intended to limit the application. Any skilled person familiar with this field, Without departing from the scope of the technical solution of the present application, any changes or modifications made using the technical content disclosed above are equivalent to equivalent implementation cases, and all belong to the scope of the technical solution.

Claims (10)

1. A multi-layer coated quantum dot material is characterized in that the multi-layer coated quantum dot material comprises quantum dot/polymer composite particles, a protective layer and a metal oxide film;

the protective layer coats the quantum dot/polymer composite particles;

the metal oxide film is coated with a protective layer.

2. The multi-layered quantum dot material of claim 1, wherein the protective layer is silica and/or amphoteric hydroxide;

preferably, the amphoteric hydroxide comprises at least one of aluminum hydroxide, titanium hydroxide and zirconium hydroxide.

3. The multi-layer coated quantum dot material of claim 1, wherein the particle size of the quantum dot/polymer composite particle 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 1 nm-100 nm.

4. The multi-layered quantum dot material as claimed in claim 1, wherein the protective layer quantum dot/polymer composite particle comprises a spatial network structure formed by polymer, and the quantum dot is embedded in the spatial network structure;

preferably, the quantum dots are perovskite quantum dots;

preferably, the polymer comprises at least one of polyvinylidene fluoride, polyvinylidene fluoride and trifluoroethylene copolymer, polyacrylonitrile, polyvinyl acetate, cellulose acetate, cyano cellulose, polysulfone, aromatic polyamide, polyimide, polycarbonate, polystyrene, polymethyl methacrylate, polylauryl methacrylate;

preferably, the metal oxide thin film includes Al ₂ O ₃ Film, tiO ₂ Film, hfO ₂ Film, zrO ₂ At least one of the films.

5. A preparation method of a quantum dot material with multilayer coating is characterized by comprising the following steps:

obtaining quantum dot/polymer composite particles;

reacting a solution containing quantum dot/polymer composite particles, a protective layer raw material compound, a catalyst and water to obtain the quantum dot/polymer composite particles coated with the protective layer;

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

6. The method according to claim 5, wherein the protective layer raw material compound in the step (b) includes at least one of an aluminum source compound, a silicon source compound, a titanium source compound, and a zirconium source compound;

preferably, the mass ratio of the quantum dot/polymer composite particles to the protective layer raw material compound is 1:0.1 to 100;

preferably, the aluminum source compound comprises at least one of triethylaluminum, aluminum sec-butoxide, and aluminum isopropoxide;

preferably, the silicon source compound comprises at least one of (3-mercaptopropyl) trimethoxysilane, bis- [3- (triethoxysilyl) -propyl ] -tetrasulfide, 3-aminopropyltriethoxysilane, methyl orthosilicate, ethyl orthosilicate and octadecyl trimethoxysilane;

preferably, the titanium source compound comprises at least one of tetrabutyl titanate, isopropyl titanate and tetraethyl titanate;

preferably, the zirconium source compound comprises at least one of zirconium n-butoxide, zirconium t-butoxide and zirconium i-propoxide;

preferably, the quantum dot/polymer composite particles are obtained by a spray drying method in the step (a);

preferably, the quantum dots are perovskite quanta, and the perovskite isThe quantum dot synthetic raw materials comprise AX and BX _m And a CX precursor; wherein A is selected from NH ₂ CHNH ₂ ⁺ (FA ⁺ )、CH ₃ NH ₃ ⁺ (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 aryl or alkyl organic amine cation with carbon atom number not less than 3; x is selected from Br ^- 、I ^- 、SCN ^- At least one of carboxylic acid groups; m =2, 3 or 4;

preferably, the perovskite quantum dot precursors AX and BX _m And CX is 0.5-10;

preferably, the solvent comprises at least one of dimethyl sulfoxide, N-hexane, cyclohexane, N-octane, octadecene, ethanol, methanol, trimethyl phosphate, triethyl phosphate, N-methylpyrrolidone, dimethylacetamide, N-dimethylformamide, isopropanol, ethyl acetate, toluene and acetone;

preferably, 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;

preferably, the spray drying process is carried out by a spray drying apparatus having a two-fluid atomizer; the technological parameters of spray drying include: feed rate of the solution: 50 ml/h-50000 ml/h; intake pressure of the corresponding atomizer: 0.02-1 MPa, air inlet speed: 15L/min to 100L/min; inlet air temperature of the dryer: 50-200 ℃.

7. The method of claim 5, wherein the catalyst comprises at least one of methylamine, ammonia, dimethylamine;

preferably, the mass ratio of the quantum dot/polymer composite particles to the catalyst is 1:0.1 to 10.

8. The method according to claim 5, wherein the solution in the step (b) further comprises a surfactant;

preferably, the surfactant comprises at least one of 6-mercaptohexanol, 1-hexadecanethiol, hexanethiol, oleic acid and stearic acid;

preferably, the mass ratio of the quantum dot/polymer composite particles to the surfactant is 1:0.1 to 50.

9. The preparation method according to claim 5, wherein the solution containing the quantum dot/polymer composite particles, the protective layer raw material compound, the catalyst and water in the step (b) is reacted at a temperature of 20 to 50 ℃ and a stirring speed of 100 to 1000 rpm to obtain the quantum dot/polymer composite particles coated with the protective layer;

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

10. The method according to claim 5, wherein in the step (c), the compound raw material containing the metal element is reacted with an oxidant to form a metal oxide film;

preferably, the raw material of the metal element-containing compound includes at least one of trimethylaluminum, aluminum trichloride, titanium tetrachloride, titanium isopropoxide, tetrakis (dimethylamino) zirconium, hafnium tetrachloride, hafnium nitrate, and dimethylaminobenzonium;

preferably, the oxide comprises at least one of water, ozone, and oxygen plasma.

Images