Perovskite quantum dot material as well as preparation method, preparation device and application thereof

Abstract

The invention provides a perovskite quantum dot material as well as a preparation method, a preparation device and application thereof. The preparation method comprises the following steps: (1) mixing and melting an A-site precursor material, a B-site precursor material and a coating raw material of perovskite quantum dots to obtain a first mixture; (2) mixing the X-site halogen material of the perovskite quantum dots with the coating raw material, and melting to obtain a second mixture; and (3) mixing the first mixture and the second mixture, and then performing atomization and cooling to obtain the perovskite quantum dot material. The preparation method is simple, efficient and low in cost, energy consumption is reduced, continuous production operation can be achieved, large-scale amplification production is easy, the quantum dots are coated, direct contact between the quantum dots and air is avoided, and the instability problem of the quantum dots is solved. In addition, the method does not generate organic harmful solvents, and is environment-friendly, energy-saving, high in efficiency and good in safety.

Description

Technical Field

[0001] The present invention belongs to the technical field of displays, and particularly relates to a perovskite quantum dot material, a preparation method thereof, a preparation device thereof, and an application thereof. Background Art

[0002] As an emerging semiconductor material, quantum dots are nanoparticles with a size smaller than or close to the exciton Bohr radius of bulk materials, exhibiting quantum effects. Due to the special structure of quantum dots, they have quantum size effects (referring to the phenomenon that when the particle size drops to a certain value, the electron energy levels near the Fermi level change from quasi-continuous to discrete energy levels, that is, energy level splitting or energy gap broadening. When the degree of energy level change is greater than the changes in thermal energy, light energy, and electromagnetic energy, it leads to significant differences in the magnetic, optical, acoustic, thermal, electrical, and superconducting properties of nanometer particles compared with conventional materials), macroscopic quantum tunneling effects, dielectric confinement effects, and surface effects, thus generating unique physical and chemical properties and unique luminescent properties. Due to the existence of size confinement effects, they have advantages such as narrow emission peaks and adjustable wavelengths. Therefore, compared with traditional fluorescent materials, quantum dot materials exhibit great advantages and are a more excellent luminescent material. In recent years, quantum dot luminescent materials have been applied to the backlight sources of liquid crystal display devices, which can significantly improve the color gamut of liquid crystal display devices and more truly restore colors.

[0003] Different from traditional luminescent materials, quantum dot materials are very fragile, and their performance will significantly decay in an air environment without protection. Therefore, the main obstacles to the large-scale industrialization of quantum dot materials (such as cadmium selenide, indium phosphide, or perovskite, etc.) are the fragile stability of the materials and the high packaging costs. The existing quantum dot materials on the market are mainly cadmium selenide and indium phosphide quantum dot materials. Due to their performance stability problems, they need to be encapsulated by a water and oxygen high-barrier film plus UV glue, and the cost has always been high, so they have not been widely promoted and applied on a large scale; perovskite quantum dots are not yet very mature in mass production due to their more unstable physical and chemical properties. The general method is to perform matrix coating (including organic coating and inorganic coating) and then encapsulate with a water and oxygen barrier film to ensure meeting the requirements of stability tests.

[0004] All of the above-mentioned schemes adopt the form of multiple coatings plus barrier films, protecting the quantum dot materials in UV glue through a sandwich structure. This scheme has characteristics such as high cost, complex process, and poor batch stability.

[0005] In addition, the preparation methods of quantum dot materials also include solution injection method, glass sintering and grinding method, and in-situ solution method. Thermal injection method: The AB-site precursor materials and X-site halogen materials of quantum dots are separately dissolved in advance in an organic solvent and physically separated. At a certain temperature and stirring and dispersion speed, the AB and X-site mixed solutions are quickly formed into a mixed solution by injection, and the reaction is terminated by cooling, followed by washing, purification, and drying to prepare powder. The thermal injection method for preparing quantum dot powder has disadvantages such as a complex process route, the use of multiple organic solvents during the process, and low material utilization rate; the glass sintering and grinding method is to prepare quantum dot powder by crushing and grinding. The stability of the glass-sintered and ground quantum dots is relatively good, but glass sintering itself is a high-energy-consuming production and preparation method. For the preparation of quantum dot glass by the glass method, the selection of raw materials is narrow, and the volume concentration of quantum dots is relatively low. Therefore, only an all-inorganic solution can be selected for the quantum dot precursor materials, and the wavelength is difficult to adjust. For the preparation of red and green quantum dots, the wavelength can only be changed by adjusting the halogen, and the efficiency is relatively low (the efficiency of red quantum dots can reach 100%, and the efficiency of green quantum dots that meet the wavelength does not exceed 50%); the in-situ solution method has a large amount of toxic solvents during the preparation process (the proportion of DMF is about 90%). It is necessary to dissolve the perovskite precursor materials with either DMF or DMSO or a mixed solution of them, and dissolve the polymer with DMF. After dissolution, the precursor materials and the polymer solution are mixed together, atomized into fine particles through an atomization device, and dried in a hot air drying chamber at 60-120°C to form quantum dot powder. This production process is complex, the route is long, a large amount of toxic organic gases are generated during the process, and the boiling points of the organic solvents used are relatively high, the drying time is long, and the output is low.

[0006] Therefore, the existing thermal injection method and in-situ solution method both have the problem of low material utilization rate. A large amount of unreacted organic solvents will exist during the generation process, and there will also be unreacted precursor materials mixed in, which is inefficient and not environmentally friendly. The glass sintering and grinding method belongs to a high-energy-consuming preparation route, and the volume concentration of the prepared quantum dots is relatively low, and the wavelength adjustment is limited.

[0007] In summary, there is an urgent need to design a preparation method for perovskite quantum dots, which can not only reduce energy consumption, have a large output and can be continuously produced, but also has a simple process, high efficiency, low cost and no pollution. Summary of the Invention

[0008] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a perovskite quantum dot material, a preparation method thereof, a preparation device thereof, and an application. The present invention provides a simple, efficient, and low-cost preparation method for perovskite quantum dot materials. Compared with the glass method, it reduces energy consumption, has a large output and can be continuously produced, which is conducive to mass production and standardization, and is easy to scale up production; compared with the thermal injection method, the process is simple, solving the problems of non-continuous operation and batch stability differences in the thermal injection method. Moreover, this method coats the quantum dots to form a physical isolation, preventing the ligand from falling off, and can avoid the direct contact of the quantum dot material with air. In the application, it can be directly encapsulated with quantum dot glue, which well solves the stability problem of the quantum dot material; compared with the in-situ solution method, this method does not produce organic harmful solvents, is environmentally friendly and energy-saving, has high efficiency and good safety.

[0009] To achieve the purpose of this invention, the following technical solutions are adopted:

[0010] In the first aspect, the present invention provides a preparation method for a perovskite quantum dot material, and the preparation method includes the following steps:

[0011] (1) Mix the A-site precursor material, B-site precursor material, and coating raw material of the perovskite quantum dot, and after melting, obtain a first mixture;

[0012] (2) Mix the X-site halogen material of the perovskite quantum dot and the coating raw material, and after melting, obtain a second mixture;

[0013] (3) Mix the first mixture and the second mixture, then perform atomization and cooling to obtain the perovskite quantum dot material.

[0014] The present invention provides a simple, efficient, and low-cost preparation method for perovskite quantum dot materials. During the preparation process, the coating raw material and the quantum dot precursor material (A and B-site precursor materials and X-site halogen materials) are melted to form a low-viscosity high-temperature molten liquid. The low-viscosity coating raw material serves as the reaction liquid at high temperature, avoiding the use of organic solvents. In the molten mixing state, the two mixtures are mixed and stirred. After the precursor materials come into contact with each other, quantum dots are generated. At this time, the quantum dots are completely dispersed into the high-temperature melt of the coating raw material, and the quantum dots grow in-situ in the coating raw material melt. Under the action of ligands, quantum dots with better performance can be obtained; subsequently, the quantum dots in the low-viscosity liquid state are atomized into small droplets through an atomization device and can form quantum dot powders uniformly dispersed in the coating raw material particles after cooling. The quantum dots dispersed in the coating layer can spatially limit the quantum dots, thereby improving the stability of the quantum dots.

[0015] Compared with the glass method for preparing quantum dot materials, this method reduces energy consumption, has a large output and can be produced continuously, which is conducive to mass production and standardization, and is easy to scale up production; compared with the hot injection method, the process is simple, which solves the problem of the hot injection method not being able to operate continuously and the batch stability difference, and this method encapsulates the quantum dots to form a physical isolation, which can prevent the quantum dot materials from directly contacting the air and water vapor. Compared with the in-situ solution method, this method does not require the use of organic solvents, and no organic harmful solvents are produced, which is environmentally friendly and energy-saving, with high efficiency and good safety; this method can be directly encapsulated by quantum dot glue in material application, which solves the stability problem of quantum dot materials very well.

[0016] As a preferred technical solution of the present invention, the A-site precursor material in step (1) includes any one of MA salt, FA salt or Cs salt, or a combination of at least two of them.

[0017] Preferably, the MA salt comprises any one or a combination of at least two of MACl, MABr, MAI or MAAc.

[0018] Preferably, the FA salt comprises any one of FACl, FABr, FAI or FAAc, or a combination of at least two thereof.

[0019] Preferably, the Cs salt includes any one of CsCl, CsBr, CsI, CsAc, cesium nitrate or cesium stearate having 2 to 18 carbon atoms, or a combination of at least two thereof.

[0020] Preferably, the B-site precursor material in step (1) is a lead salt.

[0021] Preferably, the lead salt comprises PbCl2, PbBr2, PbI2, lead stearate, lead nitrate or PbC 2～18 Any one or a combination of at least two of organic lead acids.

[0022] Preferably, the coating raw material in step (1) is a polyol, and the polyol includes any one of erythritol, mannitol, dipentaerythritol, neopentyl glycol or trimethylolpropane, or a combination of at least two thereof.

[0023] In the present invention, quantum dots are coated in polyol materials to form physical isolation. Due to the properties of polyols themselves, the quantum materials can be densely wrapped to prevent them from being corroded by harmful substances, and the quantum dot materials can be prevented from direct contact with air. The quantum dot materials can directly contact UV glue during application. Most monomer materials are non-polar lipid materials and have no swelling effect on polyols. Polyols can well protect the quantum dot materials from being destroyed in UV glue.

[0024] In addition, the polyol material is a polyol that is not easily hygroscopic, has a very high material density, and has strong crystallinity. It can well block the erosion of air and water vapor on quantum dots under certain temperature and humidity conditions.

[0025] Preferably, the molar ratio of the A-site precursor material to the B-site precursor material in step (1) is 1:(0.8 - 1.2), for example, it can be 1:0.8, 1:0.9, 1:1, 1:1.1, or 1:1.2, etc.

[0026] Preferably, the mass ratio of the A-site precursor material, the B-site precursor material, and the coating raw material in step (1) is (1.5 - 4.5):(3 - 8):(500 - 1000). Among them, the selection range of the A-site precursor material "1.5 - 4.5" can be, for example, 1.5, 2, 2.5, 3, 3.5, 4, or 4.5, etc.; the selection range of the B-site precursor material "3 - 8" can be, for example, 3, 4, 5, 6, 7, or 8, etc.; the selection range of the coating raw material "500 - 1000" can be, for example, 500, 750, or 1000, etc., and preferably it is 1.92:3.25:(500 - 1000).

[0027] In the present invention, if the mass ratio of the A-site precursor material to the coating raw material is too small, that is, the amount of the coating raw material used is too large, the volume content of the quantum dots is relatively low, and a relatively large amount needs to be added in the subsequent product preparation, which is not conducive to the bonding performance of the product; if the mass ratio of the A-site precursor material to the coating raw material is too large, that is, the amount of the coating raw material used is too small, the volume content of the quantum dots is relatively high, the spatial distance between the quantum dots is relatively close, the concentration is relatively high, and the luminescence self-absorption reduces the luminescence performance, which will have a negative impact on the stability.

[0028] As a preferred technical solution of the present invention, a first ligand material is further added during the mixing process in step (1), and the first ligand material includes an organic acid with 2 - 18 carbon atoms and / or an organic amine with 2 - 18 carbon atoms.

[0029] Preferably, the organic acid includes C 2-18 fatty acid and / or C 4-16 benzenesulfonic acid.

[0030] Preferably, the first ligand material includes any one or a combination of at least two of octylamine bromide, octylamine iodide, DBSA, dodecylamine bromide, stearic acid, dodecylbenzenesulfonic acid, or 3-sulfopropyltetradecyldimethylbetaine.

[0031] Preferably, the number of carbon atoms of the amine compound is 6 - 18, for example, it can be 6, 10, 14, or 18, etc.

[0032] In the present invention, an organic acid having 2 to 18 carbon atoms and / or an organic amine having 2 to 18 carbon atoms is added to the first mixture as the first ligand material to coordinate the defective portions of the quantum dots, which can improve the stability of the quantum dots.

[0033] Preferably, based on the mass of the first mixture, the mass fraction of the first ligand material is 0 to 2%, for example, it can be 0%, 0.5%, 1%, 1.5% or 2%, etc.

[0034] Preferably, the molar amount of the first ligand is 1 / 10 of the cesium atomic weight.

[0035] In the present invention, if the content of the first ligand material is too high, it will affect the generation of quantum dots. The ligand will limit the growth of the quantum dot material during the generation of quantum dots. Too much first ligand material will cause the quantum dots not to be generated, or the generated quantum dots to have a small size and fail to achieve good luminescence performance.

[0036] Preferably, the melting temperature in step (1) is 80 to 300 °C, for example, it can be 80 °C, 100 °C, 150 °C, 200 °C, 250 °C or 300 °C, etc.

[0037] In the present invention, the melting temperature of 80 - 300 °C can make all the mixed substances completely melt. This temperature is set according to the material characteristics and melt viscosity selected, that is, above the softening point. If the temperature is too high, it will cause the ligand coating material to oxidize and decompose, and the production equipment will have problems such as carbon deposition due to material aging.

[0038] As a preferred technical solution of the present invention, the X-site halogen material in step (2) is a halogen salt.

[0039] Preferably, the halogen salt includes any one or a combination of at least two of methylamine hydrochloride, methylamine hydrobromide, ethylamine hydrobromide, propylamine hydrobromide, n-butylamine hydrobromide, n-hexylamine hydrobromide, n-octylamine hydrobromide, formamidine hydrobromide, methylamine hydroiodide, ethylamine hydroiodide, propylamine hydroiodide, n-butylamine hydroiodide, n-hexylamine hydroiodide, n-octylamine hydroiodide, formamidine hydroiodide, cesium chloride, cesium bromide or cesium iodide.

[0040] Preferably, a second ligand material is further added during the mixing process in step (2), and the second ligand material includes any one or a combination of at least two of octylamine bromide, octylamine iodide, DBSA, dodecylamine bromide, dodecylbenzenesulfonic acid or 3-sulfopropyltetradecyldimethylbetaine.

[0041] Preferably, based on the mass of the second mixture described in step (2), the mass fraction of the second ligand material is 0-2%, for example, it can be 0%, 0.5%, 1%, 1.5% or 2%, etc.

[0042] Preferably, the molar amount of the second ligand is 1 / 10 of the cesium atomic weight.

[0043] Preferably, a reducing material is further added during the mixing process of step (2), and the reducing material includes any one or a combination of at least two of sodium hypophosphite monohydrate, aluminum hypophosphite or calcium hypophosphite.

[0044] In the present invention, sodium hypophosphite monohydrate is a reducing material, which can prevent the mixture from being oxidized before the reaction.

[0045] Preferably, the coating raw material in step (2) is a polyol, and the polyol includes any one or a combination of at least two of erythritol, mannitol, dipentaerythritol, neopentyl glycol or trimethylolpropane.

[0046] Preferably, the types of the coating raw material in step (2) and the coating raw material in step (1) are the same.

[0047] Preferably, the mass ratio of the X-site halogen material to the coating raw material in step (2) is (12-15):(500-1000), where the selection range of the X-site halogen material "12-15" can be, for example, 12, 12.5, 13, 13.5, 14 or 14.5, etc., and the selection range of the coating raw material "500-1000" can be, for example, 500, 725 or 1000, etc.

[0048] In the present invention, if the mass ratio of the X-site halogen material to the coating raw material is too small, that is, the dosage of the coating raw material is too much, the volume content of the quantum dots is relatively low, and a large amount needs to be added in the subsequent product preparation, which is not conducive to the performance of the product; if the mass ratio of the X-site halogen material to the coating raw material is too large, that is, the dosage of the coating raw material is too small, the volume content of the quantum dots is relatively high, the spatial distance of the quantum dots is relatively close, and the self-absorption of light emission at a high concentration reduces the light emission performance, which will have a negative impact on the stability.

[0049] Preferably, the first mixture and / or the second mixture further contains a reducing material, and the mass ratio of the reducing material to the coating raw material is (0-0.2):(100-1000). The selection range of the reducing material "0-0.2" can be, for example, 0, 0.1 or 0.2, etc. By adding a trace amount of the reducing material, the oxidation of the precursor material can be prevented.

[0050] As a preferred technical solution of the present invention, during the mixing process in step (3), the volume ratio of the first mixture and the second mixture is 1:(0.1 - 10), for example, it can be 1:0.1, 1:0.5, 1:1, 1:3, 1:5, 1:7 or 1:9, etc.

[0051] Preferably, the mixing time in step (3) is 3 - 15 s, for example, it can be 3 s, 5 s, 7 s, 9 s, 11 s, 13 s or 15 s, etc. If the mixing time is too short, quantum dots have not been formed yet. If the mixing time is too long, the generated quantum dots will continue to grow and form non-luminescent perovskite crystals, resulting in a decrease in fluorescence efficiency and prone to generating a certain amount of precipitation to block the spray nozzle.

[0052] Preferably, stirring is accompanied during the mixing process in step (3).

[0053] Preferably, the atomization method in step (3) includes any one or a combination of at least two of ultrasonic atomization, centrifugal atomization, two-fluid atomization or pressure atomization.

[0054] Preferably, the droplet size D50 formed after atomization in step (3) is 20 - 40 μm, for example, it can be 20 μm, 30 μm or 40 μm, etc.

[0055] Preferably, the cooling time in step (3) is 20 - 40 s, for example, it can be 20 s, 25 s, 30 s, 35 s or 40 s, etc., preferably 30 s, so that the droplets after spraying can be quickly cooled and the polyol can quickly form a coating shell to coat the quantum dots.

[0056] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0057] (1) Mix the A-site precursor material, B-site precursor material and polyol of the perovskite quantum dots, and melt them at a temperature of 80 - 300 °C to obtain the first mixture;

[0058] Among them, the molar ratio of the A-site precursor material and the B-site precursor material is 1:(0.8 - 1.2), and the mass ratio of the A-site precursor material, the B-site precursor material and the polyol is (1.5 - 4.5):(3 - 8):(500 - 1000);

[0059] (2) Mix the X-site halogen material, reducing material and polyol of the perovskite quantum dots, and melt them at a temperature of 80 - 300 °C to obtain the second mixture;

[0060] Among them, the mass ratio of the X-site halogen material, the reducing material and the polyol is (12 - 15):(0 - 0.2):(500 - 1000);

[0061] (3) Mix the first mixture and the second mixture to generate a quantum dot material, then atomize it to form atomized melt droplets, and then cool to form solid particles, thereby obtaining the perovskite quantum dot material;

[0062] Among them, during the mixing process, the volume ratio of the first mixture to the second mixture is 1:(0.1 - 10).

[0063] In a second aspect, the present invention provides a perovskite quantum dot material prepared by the preparation method described in the first aspect. The perovskite quantum dot material includes a quantum dot core and a coating layer coated on the surface of the quantum dot core.

[0064] Preferably, the particle size D50 of the perovskite quantum dot material is 20 - 40 μm, for example, it can be 20 μm, 30 μm, 40 μm, etc.

[0065] Preferably, the material of the coating layer is a small molecule polyol with less than 10 carbon atoms.

[0066] Preferably, the thickness of the coating layer is 0 - 15 μm, for example, it can be 5 μm, 10 μm, 15 μm, etc.

[0067] It should be noted that generally, the core particle size D50 of the perovskite quantum dot is about 10 μm, the coating layer thickness is about 10 μm, and the particle size D50 of the finally formed perovskite quantum dot material is about 30 μm. The volume change from the droplet form to the powder form is very small and can be ignored.

[0068] In a third aspect, the present invention provides a preparation device for the perovskite quantum dot material described in the second aspect. The preparation device includes a first melt device, a second melt device, a mixing device, an atomizing device, and a cooling container;

[0069] The first melt device is connected to the mixing device through a first transfer pump. The first melt device transports the first mixture to the mixing device. The second melt device is connected to the mixing device through a second transfer pump. The second melt device transports the second mixture to the mixing device;

[0070] The mixing device, the atomizing device, and the cooling container are sequentially connected along the direction of material movement;

[0071] The mixing device is used to receive and mix the first mixture and the second mixture;

[0072] The atomizing device is connected to the mixing device, and the mixed material in the mixing device is sprayed into the cooling container through the atomizing device;

[0073] The cooling container includes a cooling chamber for receiving the spray, and the cooling container is used to cool the spray into powder.

[0074] In the present invention, various materials are first heated into a mixed liquid by a melt device and isolated physically, which can prevent premature contact and reaction of different precursor materials. Then, they are quickly and evenly mixed by a mixing device before the atomizing device, and quantum dots are nucleated. Subsequently, they are atomized by the atomizing device and cooled to form quantum dot powder coated with polyol. Compared with the glass method, the temperature of the quantum dots in this method is low, energy consumption is reduced, the output is large, and continuous production operation is possible, which is beneficial to mass production and standardization; compared with the solution injection method, the process is simple, and the problems of non - continuous operation and batch stability difference in the thermal injection method are solved; compared with the in - situ solution method, this method can solve the problems of low spray granulation efficiency and generation of organic harmful solvents.

[0075] As a preferred technical solution of the present invention, a cooling device is connected to the bottom of the cooling container.

[0076] Preferably, the cooling device is connected to a nitrogen blower through a pipeline.

[0077] In the present invention, since nitrogen is an inert gas and has little influence on quantum dots, a nitrogen blower can be used to cool high - temperature droplets to form solid powder particles.

[0078] Preferably, a discharging device is connected to the side wall of the cooling container.

[0079] Preferably, a cyclone separator is arranged between the discharging device and the cooling container.

[0080] Fourthly, the present invention provides an application of the perovskite quantum dot material as described in the second aspect in a liquid crystal display device.

[0081] The numerical ranges described in the present invention not only include the above - listed point values, but also any point values between the above - mentioned numerical ranges not listed. Due to space limitations and for the sake of brevity, the specific point values included in the ranges of the present invention are not exhaustively listed.

[0082] Compared with the prior art, the present invention has the following beneficial effects:

[0083] The present invention provides a method for preparing perovskite quantum dot materials that is simple, efficient, and low-cost. Compared with the glass method, it reduces energy consumption, has a large output, can be continuously produced, is conducive to mass production and standardization, and is easy to scale up production. Compared with the thermal injection method, the process is simple, solving the problems of non-continuous operation and batch stability differences in the thermal injection method. Moreover, this method coats the quantum dots to form a physical isolation, which can prevent the direct contact of the quantum dot materials with air. In applications, it can be directly encapsulated with quantum dot glue, well solving the stability problem of the quantum dot materials. Compared with the in-situ solution method, this method does not produce organic harmful solvents, is environmentally friendly and energy-saving, has high efficiency, and good safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Figure 1 It is a schematic diagram of the device for preparing perovskite quantum dot materials in Example 1 of the present invention.

[0085] Among them, 1 - mixing reaction kettle; 2 - atomizing device; 3 - cooling container; 4 - first melt device; 5 - second melt device; 6 - first transfer pump; 7 - second transfer pump; 8 - cooling device; 9 - discharging device; 10 - cyclone separator; 11 - nitrogen blower. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0086] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0087] Example 1

[0088] This example provides a method for preparing perovskite quantum dot materials. The preparation method is carried out in the device as shown in Figure 1 and includes the following steps:

[0089] (1) Add the A-site precursor material, B-site precursor material, and polyol of the perovskite quantum dots into the first melt device 4 under a nitrogen atmosphere for mixing, and perform a melting treatment at a temperature of 160 °C. After complete melting, a first mixture is obtained;

[0090] Among them, the molar ratio of the A-site precursor material to the B-site precursor material is 1:1, the mass ratio of the A-site precursor material, B-site precursor material, and polyol is 1.92:3.25:1000. The A-site precursor material is cesium acetate, the B-site precursor material is PbAc2, and the polyol is erythritol;

[0091] (2) Add the X-site halogen material of the perovskite quantum dots and the polyol into the second melt device 5 under a nitrogen atmosphere for mixing, and perform a melting treatment at a temperature of 160 °C. After complete melting, a second mixture is obtained;

[0092] Among them, the mass ratio of the X-site halogen material to the polyol is 12.6:1000. The X-site halogen material is octylamine bromide, and the polyol is erythritol;

[0093] (3) Inject the first mixture and the second mixture into the mixing reaction kettle 1 through the first delivery pump 6 (metering high-temperature liquid pump) and the second delivery pump 7 (metering high-temperature liquid pump) respectively for stirring and mixing to generate quantum dot materials. Then, convey the generated quantum dot materials to the atomizing device 2 for ultrasonic atomization. The atomized molten liquid droplets with a particle size D50 of 30 μm are formed, and then sprayed into the cooling container 3, that is, solid particles are formed in the cooling and drying tower. The bottom of the cooling container 3 is connected with a cooling device 8. The cooling device 8 is connected with a nitrogen blower 11 through a pipeline. After the solid particles are collected by the cyclone separator 10, they are transferred to the discharging device 9 for standby, and the perovskite quantum dot material, that is, green quantum dot micropowder, is obtained;

[0094] Among them, the volume ratio of the first mixture to the second mixture during mixing is 1:1.

[0095] This embodiment also provides a perovskite quantum dot material prepared by the above preparation method. The perovskite quantum dot material includes a quantum dot core and a coating layer coated on the surface of the quantum dot core;

[0096] The particle size D50 of the perovskite quantum dot material is 30 μm. The material of the coating layer is erythritol, and the thickness of the coating layer is 10 μm.

[0097] Example 2

[0098] This embodiment provides a preparation method of a perovskite quantum dot material. The preparation method includes the following steps:

[0099] (1) Add the A-site precursor material, B-site precursor material and polyol of the perovskite quantum dot into the first melting device under a nitrogen atmosphere for mixing, and perform melting treatment at a temperature of 150 °C. After complete melting, the first mixture is obtained;

[0100] Among them, the molar ratio of the A-site precursor material to the B-site precursor material is 1:1. The mass ratio of the A-site precursor material, B-site precursor material and polyol is 4.16:7.74:1000. The A-site precursor material is cesium stearate, the B-site precursor material is lead stearate, and the polyol is neopentyl glycol;

[0101] (2) Add the X-site halogen material and polyol of the perovskite quantum dot into the second melting device under a nitrogen atmosphere for mixing, and perform melting treatment at a temperature of 150 °C. After complete melting, the second mixture is obtained;

[0102] Among them, the mass ratio of the X-site halogen material to the polyol is 14.68:1000. The X-site halogen material includes octylamine bromide and dodecylamine iodide with a molar ratio of 2:1, that is, the mass ratio of octylamine bromide:dodecylamine iodide:polyol is 8.4:6.26:1000, and the polyol is neopentyl glycol;

[0103] (3) Inject the first mixture and the second mixture into a mixing device through a first delivery pump (a metering high-temperature liquid pump) and a second delivery pump (a metering high-temperature liquid pump) respectively for stirring and mixing to generate quantum dot materials. Then, convey the generated quantum dot materials to an atomizing device for ultrasonic atomization to form atomized molten droplets with a particle size D50 of 30 μm, and then spray them into a cooling container, that is, a cooling and drying tower, to form solid particles. The bottom of the cooling container is connected with a cooling device, and the cooling device is connected with a nitrogen blower through a pipeline. After collecting the solid particles through a cyclone separator, transfer them to a discharging device for standby to obtain the perovskite quantum dot materials, that is, red quantum dot fine powder;

[0104] Among them, during the mixing process, the volume ratio of the first mixture to the second mixture is 1:1.

[0105] This embodiment also provides a perovskite quantum dot material prepared by the above preparation method. The perovskite quantum dot material includes a quantum dot core and a coating layer coated on the surface of the quantum dot core;

[0106] The particle size D50 of the perovskite quantum dot material is 30 μm, the material of the coating layer is neopentyl glycol, and the thickness of the coating layer is 10 μm.

[0107] Example 3

[0108] The difference between this embodiment and Example 1 is that in step (1), 3-sulfopropyltetradecyldimethylbetaine is also added as a ligand material during the mixing process, and its mass fraction is 1%.

[0109] The remaining preparation methods and parameters are the same as those in Example 1.

[0110] Example 4

[0111] The difference between this embodiment and Example 1 is that in step (2), 3-sulfopropyltetradecyldimethylbetaine is also added as a ligand material during the mixing process, and its mass fraction is 1%.

[0112] The remaining preparation methods and parameters are the same as those in Example 1.

[0113] Example 5

[0114] The difference between this example and Example 1 is that in step (1), the mass ratio of the A-site precursor material, the B-site precursor material, and the polyol is 1.92:3.25:1200.

[0115] The remaining preparation methods and parameters are the same as those in Example 1.

[0116] Example 6

[0117] The difference between this example and Example 1 is that in step (1), the mass ratio of the A-site precursor material, the B-site precursor material, and the polyol is 1.92:3.25:500.

[0118] The remaining preparation methods and parameters are the same as those in Example 1.

[0119] Example 7

[0120] The difference between this example and Example 1 is that during the mixing process in step (2), a reducing material is further added. The reducing material is sodium hypophosphite monohydrate, and based on the mass of the second mixture, the mass fraction of the reducing material is 0.1%.

[0121] The remaining preparation methods and parameters are the same as those in Example 1.

[0122] Example 8

[0123] The difference between this example and Example 1 is that in step (2), the mass ratio of the X-site halogen material and the polyol is 11:1000.

[0124] The remaining preparation methods and parameters are the same as those in Example 1.

[0125] Example 9

[0126] The difference between this example and Example 1 is that in step (2), the mass ratio of the X-site halogen material and the polyol is 16:500.

[0127] The remaining preparation methods and parameters are the same as those in Example 1.

[0128] Comparative Example 1

[0129] The difference between this comparative example and Example 1 is that the X-site halogen material and the polyol in step (2) are directly added to the first melting device for mixing.

[0130] The remaining preparation methods and parameters are the same as those in Example 1.

[0131] Comparative Example 2

[0132] The difference between this comparative example and Example 1 is that the quantum dot material is prepared by using the traditional thermal injection method and no coating material is added.

[0133] Performance Test

[0134] The perovskite quantum dots prepared in the above examples and comparative examples were encapsulated in UV glue to form a quantum dot film layer with a thickness of 100 μm, and its performance was tested.

[0135] The test conditions were as follows: in an incubator at 25 °C, a fluorescence spectrometer was used for testing and data analysis, and the model of the test and analysis instrument was FLS1000; 1500 nits of blue light was used as the light source for irradiation, and the photoluminescence efficiency was recorded, as well as the stability after irradiation for 100 h.

[0136] The test results are shown in Table 1.

[0137] Table 1

[0138]

[0139]

[0140] Analysis:

[0141] As can be seen from the above table, the present invention provides a simple, efficient and low-cost method for preparing perovskite quantum dot materials. This method has a large output and can be continuously produced. The process is simple, solving the problems of non-continuous operation and batch stability differences in the thermal injection method. Moreover, this method coats the quantum dots to form a physical isolation, which can avoid the direct contact of the quantum dot materials with air. In applications, it can be directly encapsulated with quantum dot glue, well solving the stability problem of the quantum dot materials; in addition, this method does not produce organic harmful solvents, is environmentally friendly, energy-saving, efficient and safe.

[0142] From Examples 1-2 and Comparative Examples 1-2, it can be seen that Example 1 is for preparing green light quantum dots, and Example 2 is for preparing red light quantum dots. Through the preparation methods of Examples 1-2, very high photoluminescence efficiency and ultra-high stability under blue light irradiation can be obtained. In Comparative Example 1, the three groups of elements at the ABX position and the coating material were mixed and melted together. Since it would continue to grow after the formation of quantum dots, it would cause all to become non-luminescent perovskite materials in the end, and precipitate would be generated, resulting in very low fluorescence efficiency of the prepared quantum dots. Even so, it still has a certain anti-blue light stability through irradiation. Comparative Example 2 uses the traditional thermal injection method to prepare quantum dots, but due to the lack of the coating effect of the coating material, its stability under blue light irradiation is extremely poor.

[0143] From Example 1 and Examples 3-4, it can be seen that if a ligand material is added during the mixing process in step (1) or step (2), by increasing the ligand material, the vacancies in the quantum dot synthesis process can be coordinated, and the fluorescence efficiency of the synthesized quantum dots can be improved.

[0144] As can be seen from Example 1 and Examples 5-6, when the ratios of the respective precursor materials remain unchanged, if the content of several coating materials is too large, the volume content of the quantum dots is relatively low; if the amount of the coating raw materials used is too small, then not all of the quantum dots can be coated, and the overall blue light stability decreases.

[0145] As can be seen from Example 1 and Example 7, if a reducing material is added in step (2), it can prevent the melt mixture from aging and oxidizing, thereby improving the fluorescence efficiency.

[0146] As can be seen from Example 1 and Examples 8-9, if the mass ratio of the X-site halogen material to the coating raw material is too small, the volume content of the quantum dots is relatively low, and a relatively large amount needs to be added in the subsequent product preparation, which is not conducive to the performance of the product; if the mass ratio of the X-site halogen material to the coating raw material is too large, that is, the amount of the coating raw material used is too small, the volume content of the quantum dots is relatively high, the spatial distance between the quantum dots is relatively close, the concentration is relatively high, and the self-absorption of luminescence reduces the luminescence performance, and the stability will be negatively affected.

[0147] The applicant declares that the present invention uses the above examples to illustrate the process method of the present invention, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of the raw materials selected for the present invention, the addition of auxiliary components, the selection of specific methods, etc. all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A preparation method of a perovskite quantum dot material, characterized in that, The preparation method includes the following steps: (1) Mix the A-site precursor material, B-site precursor material, and coating raw material of the perovskite quantum dots, and obtain a first mixture after melting; (2) Mix the X-site halogen material and coating raw material of the perovskite quantum dots, and obtain a second mixture after melting; (3) Mix the first mixture and the second mixture, then perform atomization and cooling to obtain the perovskite quantum dot material.

2. The preparation method according to claim 1, characterized in that, The A-site precursor material in step (1) includes any one or a combination of at least two of MA salt, FA salt, or Cs salt; Preferably, the B-site precursor material in step (1) is a lead salt; Preferably, the coating raw material in step (1) is a polyol, and the polyol includes any one or a combination of at least two of erythritol, mannitol, dipentaerythritol, neopentyl glycol, or trimethylolpropane; Preferably, the molar ratio of the A-site precursor material to the B-site precursor material in step (1) is 1:(0.8 - 1.2); Preferably, the mass ratio of the A-site precursor material, B-site precursor material, and coating raw material in step (1) is (1.5 - 4.5):(3 - 8):(500 - 1000).

3. The preparation method according to claim 1 or 2, characterized in that, A first ligand material is further added during the mixing process in step (1), and the first ligand material includes an organic acid with 2 - 18 carbon atoms and / or an organic amine with 2 - 18 carbon atoms; Preferably, based on the mass of the first mixture, the mass fraction of the first ligand material is 0 - 2%; Preferably, the melting temperature in step (1) is 80 - 300 °C.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The X-site halogen material in step (2) is a halogen salt; Preferably, a second ligand material is further added during the mixing process in step (2), and the second ligand material includes any one or a combination of at least two of octylamine bromide, octylamine iodide, DBSA, dodecylamine bromide, stearic acid, dodecylbenzenesulfonic acid, or 3-sulfopropyltetradecyldimethylbetaine; Preferably, based on the mass of the second mixture in step (2), the mass fraction of the second ligand material is 0 - 2%; Preferably, a reducing material is further added during the mixing process in step (2), and the reducing material includes sodium hypophosphite monohydrate; Preferably, the coating raw material in step (2) is a polyol, and the polyol includes any one or a combination of at least two of erythritol, mannitol, dipentaerythritol, neopentyl glycol, or trimethylolpropane; Preferably, the types of the coating raw material in step (2) and the coating raw material in step (1) are the same; Preferably, the mass ratio of the X-site halogen material to the coating raw material in step (2) is (12 - 15):(500 - 1000).

5. The preparation method according to any one of claims 1-4, characterized in that, During the mixing process in step (3), the volume ratio of the first mixture to the second mixture is 1:(0.1 - 10); Preferably, stirring is accompanied during the mixing process in step (3); Preferably, the atomization method in step (3) includes any one or a combination of at least two of ultrasonic atomization, centrifugal atomization, two-fluid atomization, or pressure atomization; Preferably, the droplet size D50 formed after atomization in step (3) is 20 - 40 μm.

6. The preparation method according to any one of claims 1-5, characterized in that, The preparation method includes the following steps: (1) Mix the A-site precursor material, B-site precursor material and polyol of the perovskite quantum dots, and melt them at a temperature of 80 - 300 °C to obtain a first mixture; Among them, the molar ratio of the A-site precursor material to the B-site precursor material is 1:(0.8 - 1.2), and the mass ratio of the A-site precursor material, B-site precursor material and polyol is (1.5 - 4.5):(3 - 8):(500 - 1000); (2) Mix the X-site halogen material, reducing material and polyol of the perovskite quantum dots, and melt them at a temperature of 80 - 300 °C to obtain a second mixture; Among them, the mass ratio of the X-site halogen material, reducing material and polyol is (12 - 15):(0 - 0.2):(500 - 1000); (3) Stir and mix the first mixture and the second mixture to generate a quantum dot material, then atomize it to form atomized molten droplets, and then cool to form solid particles to obtain the perovskite quantum dot material; Among them, the volume ratio of the first mixture to the second mixture during the mixing process is 1:(0.1 - 10).

7. A perovskite quantum dot material prepared by the preparation method according to any one of claims 1-6, characterized in that, The perovskite quantum dot material includes a quantum dot core and a coating layer coated on the surface of the quantum dot core; Preferably, the particle size D50 of the perovskite quantum dot material is 20 - 40 μm; Preferably, the material of the coating layer is a small molecule polyol with less than 10 carbon atoms; Preferably, the thickness of the coating layer is 0 - 15 μm.

8. A preparation device for the perovskite quantum dot material as described in claim 7, characterized in that, The preparation device includes a first melting device, a second melting device, a mixing device, an atomizing device and a cooling container; The first melting device is connected to the mixing device through a first delivery pump, and the first melting device delivers the first mixture to the mixing device; the second melting device is connected to the mixing device through a second delivery pump, and the second melting device delivers the second mixture to the mixing device; The mixing device, the atomizing device and the cooling container are sequentially connected along the movement mode of the material; The mixing device is used to receive and mix the first mixture and the second mixture; The atomizing device is connected to the mixing device, and the mixed material in the mixing device is sprayed into the cooling container through the atomizing device; The cooling container includes a cooling chamber for receiving the spray, and the cooling container is used to cool the spray into powder.

9. The preparation device according to claim 8, characterized in that The bottom of the cooling container is connected with a cooling device; Preferably, the side wall of the cooling container is connected with a discharging device; Preferably, a cyclone separator is arranged between the discharging device and the cooling container.

10. An application of the perovskite quantum dot material as claimed in claim 7 in a liquid crystal display device.

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