Preparation method of perovskite quantum dots capable of inhibiting phase separation and application thereof

Abstract

The application provides a perovskite quantum dot for inhibiting phase separation and a preparation method and application thereof, and comprises the following steps: S1: mixing perovskite precursors, inorganic phosphorus flame retardants and micro / intermediate pore templates to obtain a mixture; S2: calcining the mixture obtained in step S1 under conditions higher than the melting point of perovskite nanocrystals and lower than the failure temperature of the micro / intermediate pore templates, and then cooling to room temperature; the inorganic phosphorus flame retardants are decomposed by heat to form a buffer layer in the pore channels of the micro / intermediate pore templates, and the perovskite nanocrystals are anchored to the inner walls of the pore channels of the micro / intermediate pore templates through the buffer layer. The application realizes the inhibition of phase separation by adding inorganic phosphorus flame retardants with thermal expansion characteristics, and can also improve the PLQY of perovskite nanocrystals.

Description

Technical Field

[0001] This invention relates to the field of perovskite display luminescence technology, specifically to a perovskite quantum dot for suppressing phase separation, its preparation method, and its applications. Background Technology

[0002] Perovskite nanocrystals are a new type of semiconductor quantum dot material. Due to their excellent optical and electrical properties, such as high quantum efficiency, high carrier transport, and tunable spectrum, coupled with simple preparation and low cost, they have a wide range of applications in physics, chemistry, biology, and especially in the fields of LED and photovoltaics. They are a star material that has attracted much attention in both research and industrialization.

[0003] Chinese patent CN110734758A discloses a method for preparing semiconductor nanocrystalline fluorescent materials, the semiconductor nanocrystalline fluorescent materials prepared by the method, and their applications. This patent uses calcination to coat perovskite nanocrystals with micro / mesoporous materials to achieve better stability. However, this single coating allows the perovskite nanocrystals to directly contact the micro / mesoporous material, creating a potential barrier. The presence of this surface barrier causes relative movement between the perovskite nanocrystals and the coating layer (micro / mesoporous material), leading to breakage and phase separation issues, which require further improvement. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a perovskite quantum dot for suppressing phase separation, its preparation method, and its application. By adding an inorganic phosphorus-based flame retardant with thermal expansion properties, phase separation can be suppressed while simultaneously improving the PLQY of perovskite nanocrystals.

[0005] The technical solution adopted in this invention is as follows: a perovskite quantum dot for suppressing phase separation, comprising a micro / mesoporous template and perovskite nanocrystals located in the pores of the micro / mesoporous template, wherein a phosphate-containing buffer layer is disposed between the perovskite nanocrystals and the micro / mesoporous template, and the perovskite nanocrystals are anchored to the inner wall of the pores of the micro / mesoporous template through the buffer layer;

[0006] The perovskite nanocrystals have an ABX3 perovskite structure, or ABX y X' 3-y The structure is perovskite, and B is a metal cation.

[0007] By adopting the above technical solutions: the existing all-solid-state perovskite quantum dots directly encapsulate perovskite nanocrystals through a micro / mesoporous template, and the micro / mesoporous template has relatively high hardness. Once a large number of perovskite nanocrystals are accommodated in the channels of the micro / mesoporous template, pressure-induced disintegration of perovskite is prone to occur, thereby reducing the luminescence performance. In the present application, a soft buffer layer is creatively introduced between the perovskite nanocrystals and the micro / mesoporous template, which has a buffering effect, so that the perovskite nanocrystals do not come into excessive contact with the micro / mesoporous template, thereby reducing the occurrence of pressure-induced disintegration of perovskite.

[0008] In addition, regarding the problem of phase separation. Since the perovskite nanocrystals defined in the present application have metal cations, the metal cations will combine with phosphate radicals in the buffer layer to form coordination bonds, thereby forming a protective layer (i.e., the buffer layer) on the surface of the perovskite nanocrystals, so as to achieve microscopic regulation of the growth law and limitation of perovskite crystals, modify the surface properties of perovskite nanocrystals and repair defects. At the same time, the micro / mesoporous template can effectively adsorb phosphate radicals in the buffer layer and form bonds, which strengthens the structural stability of quantum dots, effectively inhibits perovskite phase separation, and improves the photoelectric performance and stability.

[0009] Further, in terms of said ABX3 perovskite structure, the molar ratio of A, B and X is 1:1:3, A is Cs, B is Pb, Sn or Cu, and X is Cl, Br or I.

[0010] Further, said ABX y X' 3-y perovskite structure, the molar ratio of A, B, X and X' is 1:1:y:3-y, where 0<y<3, A is Cs, B is Pb, Sn or Cu, X and X' are different, and each is independently Cl, Br or I.

[0011] Further, the buffer layer is made of an inorganic phosphorus-based flame retardant with thermal expansion property during calcination.

[0012] Further, the mass ratio of the buffer layer to the perovskite nanocrystals is a, 0.02<a<2.

[0013] If the proportion of the buffer layer is too high, it will occupy the growth space of perovskite nanocrystals in the channels of the micro / mesoporous template, resulting in a decrease in the content of perovskite nanocrystals, thus weakening luminescence. If the proportion of the buffer layer is too low, the perovskite nanocrystals cannot be effectively anchored to the inner wall of the channels of the micro / mesoporous template through the buffer layer.

[0014] A preparation method for perovskite quantum dots with inhibited phase separation, comprising the following steps:

[0015] S1: mixing a perovskite precursor, an inorganic phosphorus-based flame retardant and a micro / mesoporous template to obtain a mixture;

[0016] S2: The mixture obtained in step S1 is calcined under conditions above the melting point of perovskite nanocrystals and below the failure temperature of the micro / mesoporous template, and then cooled to room temperature;

[0017] The inorganic phosphorus-based flame retardant decomposes upon heating to form a buffer layer containing phosphate groups within the pores of the micro / mesoporous template.

[0018] By adopting the above scheme, the inorganic phosphorus-based flame retardant will decompose thermally during calcination and form a buffer layer. The principle of thermal decomposition of intumescent inorganic phosphorus-based flame retardants to form a buffer layer is existing technology, which should be known to those skilled in the art, and will not be elaborated here.

[0019] This application innovatively introduces an expandable inorganic phosphorus-based flame retardant into the preparation process of all-solid-state perovskite nanocrystals. Utilizing its expandable property, it expands the channels of the micro / mesoporous template, allowing for the adsorption of more perovskite precursors within the channels. During the cooling stage, crystallization occurs to form more perovskite nanocrystals, thereby improving the PLQY (Plasticity, Quality, and Availability) of the perovskite nanocrystals. Secondly, since the perovskite nanocrystals defined in this application possess metal cations, these cations combine with phosphate groups in the buffer layer to form coordination bonds, thereby forming a protective layer on the surface of the perovskite nanocrystals. This allows for microscopic control over the growth pattern and constraints of the perovskite crystals, modifying the surface properties of the perovskite nanocrystals and repairing defects. Thirdly, the micro / mesoporous template can effectively adsorb phosphate groups in the buffer layer, forming bonds that enhance the structural stability of the quantum dots, effectively suppressing perovskite phase separation, and improving photoelectric performance and stability.

[0020] Example 1: When ammonium polyphosphate is selected as the inorganic phosphorus-based flame retardant in this application, its thermal decomposition temperature is:

[0021] At temperatures above 280℃, phosphoric acid, pyrophosphate, and gaseous ammonia are generated, forming a gel-like substance that adheres to the surface, while thermal expansion also occurs. At this point, the buffer layer consists of the gel-like substance, phosphoric acid, and pyrophosphate, and contains phosphate ions.

[0022] Example 2: When aluminum dihydrogen phosphate is selected as the inorganic phosphorus-based flame retardant in this application, its thermal decomposition temperature is...

[0023] At temperatures above 230℃, phosphoric acid and aluminum phosphate are formed, resulting in a gel-like substance that adheres to the surface, and thermal expansion occurs. At this point, the buffer layer contains phosphate ions.

[0024] Example 3: When ammonium dihydrogen phosphate is selected as the inorganic phosphorus-based flame retardant in this application, its thermal decomposition temperature is:

[0025] At temperatures above 300℃, phosphoric acid and gaseous ammonia are generated, forming a gel-like substance that adheres to the surface, and thermal expansion occurs. At this point, the buffer layer contains phosphate ions.

[0026] Example 4: When piperazine pyrophosphate is selected as the inorganic phosphorus-based flame retardant in this application, its thermal decomposition temperature is...

[0027] ≥300℃. Thermal expansion will occur, at which point the buffer layer contains phosphate ions.

[0028] Furthermore, the calcination process in step S2 includes a heating stage and a cooling stage;

[0029] During the heating phase, the inorganic phosphorus flame retardant decomposes thermally to form a buffer layer within the pores of the micro / mesoporous template, the buffer layer containing phosphate ions.

[0030] During the cooling phase, perovskite nanocrystals are subsequently grown within the pores of the micro / mesoporous template, and the metal cations on the perovskite nanocrystals form coordination bonds with the phosphate groups on the buffer layer.

[0031] By adopting the above technical solution, the inorganic phosphorus-based flame retardant of this application undergoes thermal decomposition to form a buffer layer, and then cools and crystallizes within the pores of the micro / mesoporous template to form perovskite nanocrystals. These two processes do not occur simultaneously, but rather sequentially. During calcination and gradual heating to the preset temperature, the inorganic phosphorus-based flame retardant first undergoes thermal decomposition to form a buffer layer, thereby opening the pores of the micro / mesoporous template. At this time, the pores continue to adsorb the molten perovskite precursor, thus accommodating more perovskite precursor within the pores. During the subsequent cooling process, it then cools and crystallizes to form perovskite nanocrystals.

[0032] Furthermore, the perovskite precursor includes a cesium halide perovskite precursor, which is an ABX3 perovskite structure precursor, wherein the molar ratio of A, B and X is 1:1:3, and A is Cs, B is Pb, Sn or Cu, and X is Cl, Br or I.

[0033] Among them, the CsPbX perovskite precursor includes a Cs source precursor, a Pb source precursor, and an X source precursor.

[0034] CsSnX perovskite precursors include Cs-source precursors, Sn-source precursors, and X-source precursors;

[0035] CsCuX perovskite precursors include Cs-source precursors, Cu-source precursors, and X-source precursors;

[0036] The X-source precursor is a halogen-source precursor.

[0037] Furthermore, the perovskite precursor includes a mixed halide perovskite precursor, wherein the mixed halide perovskite precursor is ABX. y X' 3-yA perovskite-structured precursor, wherein the molar ratio of A, B, X and X' is 1:1:y:3-y, where 0<y<3, A is Cs, B is Pb, Sn or Cu, X and X' are different from each other and are each independently Cl, Br or I;

[0038] wherein, the CsPbXX' perovskite precursor comprises a Cs source precursor, a Pb source precursor, an X source precursor and an X' source precursor;

[0039] the CsSnXX' perovskite precursor comprises a Cs source precursor, a Sn source precursor, an X source precursor and an X' source precursor;

[0040] the CsCuXX' perovskite precursor comprises a Cs source precursor, a Cu source precursor, an X source precursor and an X' source precursor;

[0041] the X source precursor and the X' source precursor are different halogen source precursors.

[0042] further, the Cs source precursor is one or more of cesium halide and cesium carbonate;

[0043] the Pb source precursor is one or more of lead halide and lead acetate;

[0044] the Sn source precursor is tin halide;

[0045] the Cu source precursor is copper halide;

[0046] the halogen source precursor is one or more of cesium halide, lead halide, zinc halide, potassium halide, sodium halide, lithium halide, ammonium halide, calcium halide, strontium halide and barium halide.

[0047] further, the micro / mesoporous template comprises microporous materials and / or mesoporous materials;

[0048] the microporous material is microporous molecular sieve, microporous silica, microporous titanium dioxide, microporous alumina, microporous transition metal oxide, microporous sulfide, microporous silicate, microporous aluminate or microporous transition metal nitride;

[0049] the mesoporous material is mesoporous molecular sieve, mesoporous silica, mesoporous titanium dioxide, mesoporous alumina, mesoporous carbon, mesoporous transition metal oxide, mesoporous sulfide, mesoporous silicate, mesoporous aluminate or mesoporous transition metal nitride.

[0050] By adopting the above technical solution: this application limits the calcination temperature to below the failure temperature of the micro / mesoporous template, that is, the temperature at which the micro / mesoporous template collapses. Therefore, the pores of the template do not collapse throughout the entire calcination process. Through the adsorption capacity of the micro / mesoporous template's pore structure, the perovskite precursor and inorganic phosphorus-based flame retardant are adsorbed into the spatial pores of the micro / mesoporous template. In particular, the adsorption of the inorganic phosphorus-based flame retardant by the pores of the micro / mesoporous template occurs at a temperature lower than the thermal decomposition temperature of the inorganic phosphorus-based flame retardant.

[0051] The calcination temperature needs to be higher than the melting point of perovskite to obtain a molten liquid. For example, the melting point of the all-inorganic lead halide perovskite CsPbX3 (X = Br, I, Cl) is <570℃, so it is beneficial to maintain a calcination temperature >570℃. Different growth templates have different failure temperatures. For example, the pores of mesoporous silica (i.e., mesoporous silicon dioxide) collapse at temperatures above 600℃, so the calcination temperature when using mesoporous silica as a growth template for perovskite nanocrystals needs to be <600℃. As another example, mesoporous titanium dioxide begins to collapse at 800℃, so the calcination temperature when using mesoporous titanium dioxide as a growth template for perovskite nanocrystals needs to be <800℃.

[0052] Furthermore, the inorganic phosphorus-based flame retardant with thermal expansion properties includes at least one or more of ammonium polyphosphate, aluminum dihydrogen phosphate, ammonium dihydrogen phosphate, and piperazine pyrophosphate.

[0053] By adopting the above technical solution, the inorganic phosphorus-based flame retardant of this application has two requirements:

[0054] 1. It can decompose and expand when heated;

[0055] 2. The buffer layer formed after thermal decomposition must contain phosphate.

[0056] All inorganic phosphorus-based flame retardants that meet the above requirements should fall within the protection scope of this invention and conform to the same inventive concept.

[0057] Furthermore, in step S1, the mass ratio of inorganic phosphorus flame retardant to perovskite precursor is 1:(5-20).

[0058] The mass ratio of inorganic phosphorus flame retardant to micro / mesoporous template is 1:(5-20).

[0059] By adopting the above technical solution: First, if the specific gravity of the inorganic phosphorus-based flame retardant is too high, it will crowd out the growth space of the perovskite precursor within the micro / mesoporous template pores, resulting in a decrease in perovskite content and thus weakened luminescence. Conversely, if the specific gravity of the inorganic phosphorus-based flame retardant is too low, it cannot form an effective buffer layer within the micro / mesoporous template pores, preventing the perovskite nanocrystals from effectively anchoring to the inner wall of the micro / mesoporous template pores through the buffer layer. Therefore, it can only alleviate phase separation but cannot suppress it.

[0060] Furthermore, step S1 includes the following two steps:

[0061] A1 Pretreatment: Inorganic phosphorus flame retardant and micro / mesoporous template are mixed in water and stirred, and then the powder is dried by rotary evaporation. At this time, inorganic phosphorus flame retardant is adsorbed in the pores of the micro / mesoporous template to obtain pre-adsorbed material.

[0062] A2 Mixture: The pre-adsorbate obtained from A1 and the perovskite precursor are mixed to obtain a mixture.

[0063] By adopting the above technical solution: through pretreatment, the inorganic phosphorus flame retardant can be loaded onto the pore wall of the micro / mesoporous template so that thermal expansion can be carried out on the pore wall of the micro / mesoporous template during the subsequent calcination process.

[0064] An application of perovskite quantum dots for suppressing phase separation, wherein the perovskite nanocrystals are used in perovskite masterbatches, perovskite diffusers, quantum dot films, wavelength conversion films, brightness enhancement films, light-emitting devices, and light-emitting diodes.

[0065] In summary, this invention has the following beneficial effects: Firstly, this application creatively introduces an expandable inorganic phosphorus-based flame retardant into the preparation of all-solid-state perovskite nanocrystals. Its expandable properties are used to expand the channels of the micro / mesoporous template, allowing more perovskite precursors to be adsorbed within the channels. Crystallization occurs during the cooling stage to form more perovskite nanocrystals, thereby improving the PLQY (Plasticity, Quality, and Availability) of the perovskite nanocrystals. Secondly, since the perovskite nanocrystals defined in this application possess metal cations, these cations combine with phosphate groups in the buffer layer to form coordination bonds, thereby forming a protective layer on the surface of the perovskite nanocrystals. This allows for microscopic control over the growth pattern and constraints of the perovskite crystals, modifying the surface properties of the perovskite nanocrystals and repairing defects. Thirdly, the micro / mesoporous template can effectively adsorb phosphate groups in the buffer layer, forming bonds, strengthening the structural stability of the quantum dots, effectively suppressing perovskite phase separation, and improving photoelectric performance and stability. Attached Figure Description

[0066] Figure 1 The image shows the infrared spectrum of the perovskite nanocrystals, which indicates the presence of phosphate groups in the perovskite quantum dots prepared in this application.

[0067] Figure 2 The images show the fluorescence quantum yield of perovskite quantum dots in Examples 1-5 and Comparative Examples 1-3 of this invention.

[0068] Figure 3 This image shows a comparison of the in-situ normalized luminescence intensity of perovskite quantum dots from Example 1 and Comparative Example 1 when heated to 130°C. (Red light)

[0069] Figure 4 This is a comparison of the in-situ normalized luminescence intensity of the perovskite quantum dots in Example 5 and Comparative Example 3 when heated to 130°C. (Green light) Detailed Implementation

[0070] Examples 1-4 all pertain to the preparation method of mixed halide perovskite nanocrystals, and add inorganic phosphorus flame retardants that can inhibit phase separation.

[0071] Example 1:

[0072] 2.2 g of cesium bromide, 4.6 g of lead iodide, 1.8 g of lead bromide, 10 g of MCM-41 molecular sieve (mesoporous silica), and 1 g of ammonium polyphosphate were weighed and mixed in 900 ml of ultrapure water. The mixture was stirred and reacted in a 70 °C water bath for 20 min. The powder was then rapidly dried by rotary evaporation and sintered at 580 °C for half an hour under a nitrogen atmosphere, followed by cooling to room temperature. Finally, CsPbI was obtained. y Br 3-y Quantum dot / molecular sieve composite materials.

[0073] In the above, cesium bromide, lead iodide, and lead bromide are all perovskite precursors;

[0074] It also includes post-processing:

[0075] CsPbI y Br 3-y The quantum dot / molecular sieve composite material was washed with water, 1g of aminosulfonic acid was added to the water and mixed, and stirred at 60℃. Finally, it was centrifuged and dried.

[0076] The dried CsPbI y Br 3-y The fluorescence quantum yield (PLQY) of the quantum dot / molecular sieve composite material was tested to be 65%.

[0077] Example 2:

[0078] 2.2 g of cesium bromide, 4.6 g of lead iodide, 1.8 g of lead bromide, 10 g of MCM-41 molecular sieve, 0.5 g of ammonium polyphosphate, and 0.5 g of aluminum dihydrogen phosphate were weighed and mixed in 900 ml of ultrapure water. The mixture was stirred and reacted in a 70 °C water bath for 20 min. The powder was then rapidly dried by rotary evaporation and sintered at 580 °C for half an hour under a nitrogen atmosphere, followed by cooling to room temperature. Finally, CsPbI was obtained. y Br 3-y Quantum dot / molecular sieve composite materials.

[0079] It also includes post-processing:

[0080] CsPbI y Br 3-y The quantum dot / molecular sieve composite material was washed with water, 1g of aminosulfonic acid was added to the water and mixed, and stirred at 60℃. Finally, it was centrifuged and dried.

[0081] The dried CsPbI y Br 3-y The fluorescence quantum yield (PLQY) of the quantum dot / molecular sieve composite material was 68%.

[0082] Example 3:

[0083] 2.2g of cesium bromide, 4.6g of lead iodide, 1.8g of lead bromide, 10g of MCM-41 molecular sieve (mesoporous silica), and 1g of ammonium dihydrogen phosphate were weighed and blended to obtain a mixture; the mixture was sintered at 580℃ for half an hour under a nitrogen atmosphere, and then cooled to room temperature; finally, CsPbI was obtained. y Br 3-y Quantum dot / molecular sieve composite materials.

[0084] It also includes post-processing:

[0085] CsPbI y Br 3-y The quantum dot / molecular sieve composite material was washed with water, 1g of aminosulfonic acid was added to the water and mixed, and stirred at 60℃. Finally, it was centrifuged and dried.

[0086] The dried CsPbI y Br 3-y The fluorescence quantum yield (PLQY) of the quantum dot / molecular sieve composite material was 62%.

[0087] Example 4:

[0088] Weigh 1g of ammonium polyphosphate and 10g of MCM-41 molecular sieve and mix them in water. Stir the mixture in a 70℃ water bath for 20 minutes, then rapidly dry the powder by rotary evaporation to obtain the pre-adsorbent.

[0089] The pre-adsorbate was mixed with 2.2 g of cesium bromide, 4.6 g of lead iodide, and 1.8 g of lead bromide, and sintered at 580 °C for half an hour under a nitrogen atmosphere, followed by cooling to room temperature; finally, CsPbI was obtained. y Br 3-y Quantum dot / molecular sieve composite materials.

[0090] It also includes post-processing:

[0091] CsPbI y Br 3-y The quantum dot / molecular sieve composite material was washed with water, 1g of aminosulfonic acid was added to the water and mixed, and stirred at 60℃. Finally, it was centrifuged and dried.

[0092] The dried CsPbI y Br 3-y The fluorescence quantum yield (PLQY) of the quantum dot / molecular sieve composite material was 71%.

[0093] Example 5: Preparation method of cesium halide perovskite nanocrystals

[0094] The difference from Example 1 is that the perovskite precursor is selected as 5 mmol CsBr and 5 mmol PbBr2.

[0095] The obtained CsPbBr3 quantum dot / molecular sieve composite material was tested and found to have a fluorescence quantum yield (PLQY) of 75%.

[0096] Comparative Example 1:

[0097] The difference from Example 1 is that no inorganic phosphorus flame retardant is added.

[0098] The obtained CsPbI y Br 3-y The fluorescence quantum yield (PLQY) of the quantum dot / molecular sieve composite material was 54%.

[0099] Comparative Example 2:

[0100] The difference from Example 1 is that the inorganic phosphorus flame retardant (ammonium polyphosphate) is replaced with a commercially available organic phosphorus flame retardant (xylene phosphate).

[0101] The obtained CsPbI y Br 3-y The fluorescence quantum yield (PLQY) of the quantum dot / molecular sieve composite material was 34%.

[0102] Because this application uses calcination (sintering at 580℃) to prepare all-solid perovskite, and organophosphorus flame retardants are easily decomposed at high temperatures, they are ineffective. Furthermore, the decomposition process can cause them to turn black, which can even reduce PLQY (Power Level Quality).

[0103] Comparative Example 3:

[0104] The difference from Example 5 is that no inorganic phosphorus flame retardant is added.

[0105] The fluorescence quantum yield (PLQY) of the obtained CsPbBr3 quantum dot / molecular sieve composite material was tested to be 67%.

[0106] Comparative Example 4:

[0107] The difference from Example 1 is that the inorganic phosphorus flame retardant (ammonium polyphosphate) is replaced with an inorganic intumescent graphite flame retardant (expanded graphite EG).

[0108] The obtained CsPbI y Br 3-y The fluorescence quantum yield (PLQY) of the quantum dot / molecular sieve composite material was 48%.

[0109] In summary, this invention provides a method for growing high-performance perovskite nanocrystals in molecular sieves, and adds an additive that can suppress phase separation. The additive adsorbs and forms phosphate groups on the surface of quantum dots, which combine with cations on the surface of perovskite to form coordination bonds, thereby regulating the charge distribution. At the same time, the channels of the molecular sieve can effectively adsorb and fix phosphate groups to form bonds, thereby enhancing the structural stability of quantum dots, effectively suppressing perovskite phase separation, and improving the photoelectric properties and stability of quantum dots.

[0110] The above-described embodiments provide a detailed explanation of the preparation method of the present invention. It should be understood that these embodiments are only for illustrating the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing perovskite quantum dots with suppressed phase separation, characterized in that, Includes the following steps: S1: A mixture is obtained by mixing perovskite precursor, inorganic phosphorus flame retardant with thermal expansion properties and micro / mesoporous template; S2: The mixture obtained in step S1 is calcined under conditions above the melting point of perovskite nanocrystals and below the failure temperature of the micro / mesoporous template, and then cooled to room temperature; The inorganic phosphorus-based flame retardant with thermal expansion properties includes at least one of ammonium polyphosphate, aluminum dihydrogen phosphate, ammonium dihydrogen phosphate, and piperazine pyrophosphate. The inorganic phosphorus-based flame retardant decomposes upon heating to form a buffer layer containing phosphate groups within the pores of the micro / mesoporous template.

2. The method for preparing perovskite quantum dots with phase separation suppression according to claim 1, characterized in that, The calcination process in step S2 includes a heating stage and a cooling stage; During the heating phase, the inorganic phosphorus flame retardant decomposes upon heating to form a phosphate-containing buffer layer within the pores of the micro / mesoporous template. During the cooling phase, perovskite nanocrystals are subsequently grown within the pores of the micro / mesoporous template, and the metal cations on the perovskite nanocrystals form coordination bonds with the phosphate groups on the buffer layer.

3. The method for preparing perovskite quantum dots with phase separation suppression according to claim 1, characterized in that, The perovskite nanocrystals have an ABX3 perovskite structure or ABX y X' 3-y Perovskite structure; When the perovskite nanocrystals have an ABX3 perovskite structure, the molar ratio of A, B and X is 1:1:3, and A is Cs, B is Pb, Sn or Cu, and X is Cl, Br or I. When the perovskite nanocrystal has ABX y X' 3-y perovskite structure, the molar ratio of A, B, X and X' is 1:1:y:3-y, where 0<y<3, A is Cs, B is Pb, Sn or Cu, X and X' are different, and each is independently Cl, Br or I.

4. The method for preparing perovskite quantum dots with phase separation suppression according to claim 3, characterized in that, The perovskite precursor includes a cesium halide perovskite precursor, which is an ABX3 perovskite structure precursor, wherein the molar ratio of A, B and X is 1:1:3, and A is Cs, B is Pb, Sn or Cu, and X is Cl, Br or I. Among them, the CsPbX perovskite precursor includes a Cs source precursor, a Pb source precursor, and an X source precursor. CsSnX perovskite precursors include Cs-source precursors, Sn-source precursors, and X-source precursors; CsCuX perovskite precursors include Cs-source precursors, Cu-source precursors, and X-source precursors; The X-source precursor is a halogen-source precursor.

5. The method for preparing perovskite quantum dots with phase separation suppression according to claim 3, characterized in that, The perovskite precursor comprises a mixed halogen perovskite precursor, and the mixed halogen perovskite precursor is ABX y X' 3-y a precursor having a perovskite structure, wherein the molar ratio of A, B, X and X' is 1:1:y:3-y, 0<y<3, A is Cs, B is Pb, Sn or Cu, X and X' are different, and each is independently Cl, Br or I; Among them, the CsPbXX' perovskite precursor includes Cs source precursor, Pb source precursor, X source precursor and X' source precursor; The CsSnXX' perovskite precursor includes Cs-source precursor, Sn-source precursor, X-source precursor and X'-source precursor; The CsCuX X' perovskite precursor includes Cs source precursor, Cu source precursor, X source precursor and X' source precursor; The X-source precursor and the X'-source precursor are different halogen source precursors.

6. A method for preparing perovskite quantum dots with suppressed phase separation according to claim 4 or 5, characterized in that, The Cs source precursor is one or more of cesium halide and cesium carbonate; The Pb source precursor is one or more of lead halide and lead acetate. The Sn source precursor is tin halide; The Cu source precursor is copper halide; The halogen source precursor is one or more of the following: cesium halide, lead halide, zinc halide, potassium halide, sodium halide, lithium halide, ammonia halide, calcium halide, strontium halide, and barium halide.

7. The method for preparing perovskite quantum dots with suppressed phase separation according to claim 1, characterized in that, In step S1, the mass ratio of inorganic phosphorus flame retardant to perovskite precursor is 1:(5-20). The mass ratio of inorganic phosphorus flame retardant to micro / mesoporous template is 1:(5-20).

8. The method for preparing perovskite quantum dots with phase separation suppression according to claim 1, characterized in that, Step S1 includes the following two steps: A1 Pretreatment: Inorganic phosphorus flame retardant and micro / mesoporous template are mixed in water and stirred, and then the powder is dried by rotary evaporation. At this time, inorganic phosphorus flame retardant is adsorbed in the pores of the micro / mesoporous template to obtain pre-adsorbed material. A2 Mixture: The pre-adsorbate obtained from A1 and the perovskite precursor are mixed to obtain a mixture.

9. The method for preparing perovskite quantum dots with suppressed phase separation according to claim 1, characterized in that, The micro / mesoporous template includes microporous materials and / or mesoporous materials; The microporous material is a microporous molecular sieve, microporous silica, microporous titanium dioxide, microporous alumina, microporous transition metal oxide, microporous sulfide, microporous silicate, microporous aluminate, or microporous transition metal nitride. The mesoporous material is a mesoporous molecular sieve, mesoporous silica, mesoporous titanium dioxide, mesoporous alumina, mesoporous carbon, mesoporous transition metal oxide, mesoporous sulfide, mesoporous silicate, mesoporous aluminate, or mesoporous transition metal nitride.

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