A meso-entropy halogen double perovskite fluorescent powder, a preparation method and application thereof

Abstract

The application discloses a medium-entropy halogen double perovskite fluorescent powder and a preparation method and application thereof, and has the following chemical composition: Cs2(Sn x Hf y Pt z )Cl6:nSb 3+ , wherein x+y+z+n=1, 0.20<=x<=0.50, 0.20<=y<=0.50, 0.20<=z<=0.50, and 0<n<=0.15. The preparation method comprises the following steps: weighing raw materials, preparing a solution; mixing solution A and solution D, stirring and keeping the temperature at 40-65 DEG C; dropwise adding solution C, stirring and keeping the temperature unchanged; adding solution B by using a peristaltic pump, stirring and keeping the temperature unchanged; stirring, centrifugal separation, washing; and drying and cooling. The obtained medium-entropy fluorescent powder takes Cs2(Sn x Hf y Pt z )Cl6 as a matrix, has strong absorption in a near-ultraviolet region, has good matching property with a near-ultraviolet chip, and is easy to be packaged into a white light LED device.

Description

Technical Field

[0001] This invention relates to phosphors, their preparation methods and applications, specifically a medium-entropy halide double perovskite phosphor, its preparation method and applications. Background Technology

[0002] White light-emitting diodes (white LEDs), as the fourth generation of lighting appliances, have advantages such as high energy efficiency, environmental friendliness, and easy adjustment, and have gradually replaced incandescent lamps as the mainstream lighting source. Traditional commercial white LEDs are achieved by coating yellow phosphor onto a blue chip, or by encapsulating red, green, and blue phosphors on an ultraviolet chip. However, these two methods suffer from problems such as low color rendering index and poor color stability. Therefore, the development of single-matrix white phosphors that can be excited by ultraviolet or near-ultraviolet light has become a research hotspot.

[0003] Over the past decade, halide perovskites have gained widespread attention in the field of optoelectronic functional materials due to their excellent optical properties and relatively low preparation costs. However, the reported APbX3 (A=Cs) + CH3NH3 + ;X=Cl - , Br - I - Perovskites contain lead, which causes significant environmental pollution. To address this issue, researchers have attempted to replace the +2 valence Pb with +4 valence M (Zr, Sn, Te, Hf) elements, leaving 50% of the octahedral vacancies at the B sites, thus synthesizing Cs₂MCl₆ (M = Zr, Sn, Te, Hf) vacancy-ordered lead-free halide bis-perovskites. Compared to traditional organic-inorganic composite perovskites, these inorganic halide perovskites exhibit excellent thermal stability and high structural tunability, making them highly competitive as matrices for luminescent materials.

[0004] Cs₂MCl₆ type halide double perovskites exhibit broad self-trapped exciton (STE) emission in the blue light region due to their unique ordered vacancy structure. After doping with luminescent centers, their spectral characteristics can be tunable, making them a promising candidate for white LEDs. Among the many luminescent centers, Sb... 3+ It possesses unique singlet and triplet states, exhibiting broad emission peaks in the blue to red light range. Sb 3+ The outermost electron structure is 5s 2 Its luminescence properties are significantly affected by the crystal field. Sb is doped into Cs₂MCl₆ type halide double perovskites. 3+ The spectrum can be regulated by controlling the structure of Cs2MCl6, thereby obtaining a single-matrix white phosphor with tunable spectrum.

[0005] The structure of Cs2MCl6 is often modulated by doping ions at the A and B sites of Cs2MCl6, but the preparation of entropy phosphors by multi-component doping at the B site of Cs2MCl6 has not yet been reported. Summary of the Invention

[0006] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the purpose of this invention is to provide a medium-entropy halogen double perovskite phosphor with tunable spectrum and good stability. Another purpose of this invention is to provide a convenient and controllable preparation method of medium-entropy halogen double perovskite phosphor. A further purpose of this invention is to provide an application of medium-entropy halogen double perovskite phosphor in white LED devices.

[0007] Technical solution: The chemical composition of the medium-entropy halide double perovskite phosphor of the present invention is as follows:

[0008] Cs2(Sn x Hf y Pt z Cl6:nSb 3+

[0009] Where x + y + z + n = 1, and 0.20 ≤ x ≤ 0.50, 0.20 ≤ y ≤ 0.50, 0.20 ≤ z ≤ 0.50, 0 <n≤0.15。

[0010] The present invention discloses a method for preparing a medium-entropy halide double perovskite phosphor, comprising the following steps:

[0011] Step 1: Weigh the raw materials according to the stoichiometric ratio. Dissolve the Sn-containing compound and the Hf-containing compound in concentrated hydrochloric acid to prepare a solution A with a concentration of 0.1–0.2 mol / L; dissolve the Cs-containing compound in concentrated hydrochloric acid to prepare a solution B with a concentration of 0.2–0.4 mol / L; dissolve the Sb-containing compound in concentrated hydrochloric acid to prepare a solution C with a concentration of 0.05–0.1 mol / L; dissolve the Pt-containing compound in a mixed solution of concentrated hydrochloric acid and anhydrous ethanol to prepare a solution D with a concentration of 0.05–0.1 mol / L.

[0012] Step 2: Mix solutions A and D, stirring continuously throughout the process and maintaining the temperature between 40 and 65°C.

[0013] Step 3: Add solution C dropwise to the product obtained in Step 2, stirring and keeping the temperature constant;

[0014] Step 4: Add solution B to the product obtained in step 3 using a peristaltic pump, stir and keep the temperature constant;

[0015] Step 5: Maintain the temperature at 30-40℃, stir for 15-30 minutes, then centrifuge and wash the resulting mixture.

[0016] Step six: Dry the product obtained in step five at 40–60°C and cool it to obtain a medium-entropy halide double perovskite phosphor.

[0017] Preferably, in step one, the Sn-containing compound is SnCl4, the Hf-containing compound is HfCl4, the Cs-containing compound is CsCl, the Sb-containing compound is SbCl3, and the Pt-containing compound is PtCl4. The mass percentage of HCl in the concentrated hydrochloric acid is 37 wt%. The volume percentage of concentrated hydrochloric acid in the mixed solution of concentrated hydrochloric acid and anhydrous ethanol is 40%-60%.

[0018] Furthermore, in step two, the stirring speed is 100–500 r / min.

[0019] Furthermore, in step three, the stirring time is 5 to 10 minutes.

[0020] Furthermore, in step four, the stirring speed is 300-500 r / min, and the rate of adding solution B is 1-5 mL / min.

[0021] Furthermore, in step five, the stirring speed is 100-500 r / min, the centrifugation rate is 6000-10000 r / min, and the washing is performed multiple times with one or more of concentrated hydrochloric acid and isopropanol.

[0022] Furthermore, in step six, the drying time is 1 to 3 hours.

[0023] The present invention relates to the application of a medium-entropy halide double perovskite phosphor in white LED devices.

[0024] Medium-entropy halide double perovskites, as the matrix of luminescent materials, have a combination of elements with different properties at their B sites, providing a rich chemical environment for doping of the luminescent centers, and have great research value and application potential in solid-state lighting.

[0025] Preparation principle: Selecting intermediate-entropy halogen double perovskite Cs2(Sn) x Hf y Pt z Cl6 is the matrix, Sb 3+ A single-matrix white phosphor was prepared using Cs2(Sn) as the luminescent center. x Hf y Pt z Cl6:nSb 3+The B-site is a combination of three elements, which allows for spectral modulation of the phosphor, resulting in a spectrally tunable single-matrix white phosphor. The intermediate-entropy halogen double perovskite phosphor is synthesized using a solution method, with strict temperature control and the use of a mixed solution of hydrochloric acid and ethanol as the solvent, thus improving the stability of the sample solution.

[0026] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0027] 1. The intermediate-entropy phosphor obtained in this invention uses Cs2(Sn) x Hf y Pt z Cl6 is used as a matrix, which has strong absorption in the near-ultraviolet region, has good matching with near-ultraviolet chips, and is easy to encapsulate into white LED devices.

[0028] 2. The phosphor has good stability and maintains good luminescence performance even after repeated temperature changes;

[0029] 3. The spectrum of phosphor can be modulated by changing the doping concentration of the three elements at the B site, thus obtaining a single-matrix white phosphor with tunable spectrum. Attached Figure Description

[0030] Figure 1 It is the Cs2(Sn) obtained in Example 1 0.2 Hf 0.45 Pt 0.3 Cl6:0.05Sb 3+ Excitation spectrum of phosphor at a monitoring wavelength of 660 nm;

[0031] Figure 2 It is the Cs2(Sn) obtained in Example 3 0.2 Hf 0.5 Pt 0.2 Cl6:0.1Sb 3+ Graph showing the change in luminescence intensity of phosphor at different temperatures;

[0032] Figure 3 It is the Cs2(Sn) obtained in Example 4 0.3 Hf 0.2 Pt 0.35 Cl6:0.15Sb 3+ Scanning electron microscope image of the phosphor;

[0033] Figure 4 These are the emission spectra of the phosphors obtained in Examples 1-5 at an excitation wavelength of 254 nm. Detailed Implementation

[0034] In the following embodiments, the Cs raw material is high-purity (99.99%) CsCl powder; the Sb raw material is high-purity (99.99%) SbCl3 powder; the Sn raw material is high-purity liquid anhydrous SnCl4 (99.99%); the Hf raw material is high-purity (99.99%) HfCl4 powder; the Pt raw material is high-purity (99.99%) PtCl4 powder; and the solvents are anhydrous ethanol and concentrated hydrochloric acid with a concentration of approximately 37 wt%.

[0035] Table 1 Ingredient List

[0036]

[0037] The present invention uses a solution method to synthesize a medium-entropy halogen double perovskite phosphor. The formulations of the following examples are shown in Table 1 above.

[0038] Example 1

[0039] A medium-entropy halogen double perovskite phosphor Cs2(Sn) 0.2 Hf 0.45 Pt 0.3 Cl6:0.05Sb 3+ The preparation method includes the following steps:

[0040] (1) Weigh the raw materials according to the composition in Table 1.

[0041] (2) Dissolve SnCl4 and HfCl4 in concentrated hydrochloric acid to prepare SnCl4 solution with a concentration of 0.10 mol / L and HfCl4 solution with a concentration of 0.15 mol / L, respectively. Dissolve PtCl4 in a mixed solution of concentrated hydrochloric acid and anhydrous ethanol (volume ratio 4:6) to prepare PtCl4 solution with a concentration of 0.07 mol / L. Mix the above solutions and stir continuously throughout the process at a speed of 500 r / min, while maintaining the temperature at 60℃.

[0042] (3) Dissolve SbCl3 in concentrated hydrochloric acid to prepare a SbCl3 solution with a concentration of 0.09 mol / L. Add the solution dropwise to the above mixed solution while keeping the magnetic stirrer speed and temperature constant for 8 min.

[0043] (4) Dissolve CsCl in concentrated hydrochloric acid to prepare a CsCl solution with a concentration of 0.20 mol / L. Adjust the speed of the magnetic stirrer to 450 r / min, and use a peristaltic pump to add the prepared CsCl solution to the above mixed solution at a rate of 3 mL / min. The temperature remains constant throughout the process.

[0044] (5) Continue stirring with a magnetic stirrer at a speed of 500 r / min and a temperature of 33°C. After stirring for 15 min, turn off the magnetic stirrer and centrifuge the resulting mixture.

[0045] (6) The obtained solution was centrifuged and washed 6 times at a centrifugation rate of 8000 r / min. The solvents used for centrifugation and washing were in the following order: a mixture of concentrated hydrochloric acid and isopropanol, concentrated hydrochloric acid, isopropanol, isopropanol, concentrated hydrochloric acid and isopropanol.

[0046] (7) The product obtained by centrifugation is placed in a drying oven at 60°C for 3 hours and then cooled to room temperature to obtain the medium-entropy halogen double perovskite phosphor Cs2(Sn). 0.2 Hf 0.45 Pt 0.3 Cl6:0.05Sb 3+ .

[0047] The test results are as follows:

[0048] The obtained powder sample was subjected to fluorescence spectroscopy (Hitachi F-4600, Japan). The excitation spectrum was measured at a monitoring wavelength of 625 nm. The test results are shown below. Figure 1 .Depend on Figure 1 It can be seen that the phosphor has a broad excitation peak in the near-ultraviolet band, indicating that the phosphor has good compatibility with near-ultraviolet LED chips and can be packaged onto near-ultraviolet chips to make white LED devices.

[0049] Example 2

[0050] A medium-entropy halogen double perovskite phosphor Cs2(Sn) 0.5 Hf 0.25 Pt 0.2 Cl6:0.05Sb 3+ The preparation method includes the following steps:

[0051] (1) Weigh the raw materials according to the composition in Table 1.

[0052] (2) Dissolve SnCl4 and HfCl4 in concentrated hydrochloric acid to prepare SnCl4 solutions with a concentration of 0.15 mol / L and HfCl4 solutions with a concentration of 0.13 mol / L, respectively. Dissolve PtCl4 in a mixed solution of concentrated hydrochloric acid and anhydrous ethanol (volume ratio 4.5:5.5) to prepare PtCl4 solutions with a concentration of 0.09 mol / L. Mix the above solutions and stir continuously throughout the process at a speed of 300 r / min, while maintaining the temperature at 55℃.

[0053] (3) Dissolve SbCl3 in concentrated hydrochloric acid to prepare a SbCl3 solution with a concentration of 0.05 mol / L. Add the solution dropwise to the above mixed solution while keeping the magnetic stirrer speed and temperature constant for 5 min.

[0054] (4) Dissolve CsCl in concentrated hydrochloric acid to prepare a CsCl solution with a concentration of 0.35 mol / L. Adjust the speed of the magnetic stirrer to 300 r / min, and use a peristaltic pump to add the prepared CsCl solution to the above mixed solution at a rate of 1 mL / min. The temperature remains constant throughout the process.

[0055] (5) Continue stirring with a magnetic stirrer at a speed of 300 r / min and a temperature of 40°C. After stirring for 25 min, turn off the magnetic stirrer and centrifuge the resulting mixture.

[0056] (6) The obtained solution was centrifuged and washed 6 times at a centrifugation rate of 6500 r / min. The solvents used for centrifugation and washing were in the following order: a mixture of concentrated hydrochloric acid and isopropanol, concentrated hydrochloric acid, isopropanol, isopropanol, concentrated hydrochloric acid and isopropanol.

[0057] (7) The product obtained by centrifugation is placed in a drying oven at 45°C and dried for 2 hours. After cooling to room temperature, the intermediate-entropy halogen double perovskite phosphor Cs2(Sn) is obtained. 0.5 Hf 0.25 Pt 0.2 Cl6:0.05Sb 3+ .

[0058] Example 3

[0059] A medium-entropy halogen double perovskite phosphor Cs2(Sn) 0.2 Hf 0.5 Pt 0.2 Cl6:0.1Sb 3+ The preparation method includes the following steps:

[0060] (1) Weigh the raw materials according to the composition in Table 1.

[0061] (2) Dissolve SnCl4 and HfCl4 in concentrated hydrochloric acid to prepare SnCl4 solution with a concentration of 0.20 mol / L and HfCl4 solution with a concentration of 0.10 mol / L, respectively. Dissolve PtCl4 in a mixed solution of concentrated hydrochloric acid and anhydrous ethanol (volume ratio 5:5) to prepare PtCl4 solution with a concentration of 0.05 mol / L. Mix the above solutions and stir continuously throughout the process at a speed of 400 r / min, while maintaining the temperature at 40℃.

[0062] (3) Dissolve SbCl3 in concentrated hydrochloric acid to prepare a SbCl3 solution with a concentration of 0.10 mol / L. Add the solution dropwise to the above mixed solution while keeping the magnetic stirrer speed and temperature constant for 7 min.

[0063] (4) Dissolve CsCl in concentrated hydrochloric acid to prepare a CsCl solution with a concentration of 0.27 mol / L. Set the speed of the magnetic stirrer to 400 r / min and use a peristaltic pump to add the prepared CsCl solution to the above mixed solution at a rate of 4 mL / min. The temperature remains constant throughout the process.

[0064] (5) Continue stirring with a magnetic stirrer at a speed of 400 r / min and a temperature of 37°C. After stirring for 20 min, turn off the magnetic stirrer and centrifuge the resulting mixture.

[0065] (6) The obtained solution was centrifuged and washed 6 times at a centrifugation rate of 10000 r / min. The solvents used for centrifugation and washing were in the following order: a mixture of concentrated hydrochloric acid and isopropanol, concentrated hydrochloric acid, isopropanol, isopropanol, concentrated hydrochloric acid and isopropanol.

[0066] (7) The product obtained by centrifugation is placed in a drying oven at 55°C and dried for 1 hour. After cooling to room temperature, the intermediate-entropy halogen double perovskite phosphor Cs2(Sn) is obtained. 0.2 Hf 0.5 Pt 0.2 Cl6:0.1Sb 3+ .

[0067] The test results are as follows:

[0068] The obtained powder samples were subjected to fluorescence spectroscopy (Hitachi F-4600, Japan). The luminescence intensity of the phosphor at different temperatures was measured with an excitation wavelength of 310 nm. The test results are shown in [Figure number missing]. Figure 2 .Depend on Figure 2 It can be seen that the luminescence intensity of the phosphor decreases to some extent as the temperature increases, but recovers to its original value as the temperature decreases. After multiple heating and cooling cycles, the luminescence intensity of the phosphor can still maintain its initial intensity, demonstrating good cycling stability.

[0069] Example 4

[0070] A medium-entropy halogen double perovskite phosphor Cs2(Sn) 0.3 Hf 0.2 Pt 0.35 Cl6:0.15Sb 3+ The preparation method includes the following steps:

[0071] (1) Weigh the raw materials according to the composition in Table 1.

[0072] (2) Dissolve SnCl4 and HfCl4 in concentrated hydrochloric acid to prepare SnCl4 solutions with a concentration of 0.18 mol / L and HfCl4 solutions with a concentration of 0.20 mol / L, respectively. Dissolve PtCl4 in a mixed solution of concentrated hydrochloric acid and anhydrous ethanol (volume ratio 6:4) to prepare PtCl4 solutions with a concentration of 0.10 mol / L. Mix the above solutions and stir continuously throughout the process at a speed of 100 r / min, while maintaining the temperature at 45℃.

[0073] (3) Dissolve SbCl3 in concentrated hydrochloric acid to prepare a SbCl3 solution with a concentration of 0.05 mol / L. Add the solution dropwise to the above mixed solution while keeping the magnetic stirrer speed and temperature constant and stirring for 10 min.

[0074] (4) Dissolve CsCl in concentrated hydrochloric acid to prepare a CsCl solution with a concentration of 0.40 mol / L. Set the speed of the magnetic stirrer to 500 r / min and use a peristaltic pump to add the prepared CsCl solution to the above mixed solution at a rate of 5 mL / min. The temperature remains constant throughout the process.

[0075] (5) Continue stirring with a magnetic stirrer at a speed of 100 r / min and a temperature of 30°C. After stirring for 15 min, turn off the magnetic stirrer and centrifuge the resulting mixture.

[0076] (6) The obtained solution was centrifuged and washed 6 times at a centrifugation rate of 7500 r / min. The solvents used for centrifugation and washing were in the following order: a mixture of concentrated hydrochloric acid and isopropanol, concentrated hydrochloric acid, isopropanol, isopropanol, concentrated hydrochloric acid and isopropanol.

[0077] (7) The product obtained by centrifugation is placed in a drying oven at 40°C and dried for 1.5 hours. After cooling to room temperature, the intermediate-entropy halogen double perovskite phosphor Cs2(Sn) is obtained. 0.3 Hf 0.2 Pt 0.35 Cl6:0.15Sb 3+ .

[0078] The test results are as follows:

[0079] The obtained powder sample was subjected to scanning electron microscopy (SEM) analysis, and the results are shown below. Figure 3 .Depend on Figure 3 It can be seen that the particle size of the phosphor is less than 1μm, which is beneficial for subsequent encapsulation applications.

[0080] Example 5

[0081] A medium-entropy halogen double perovskite phosphor Cs2(Sn) 0.25 Hf 0.2 Pt 0.5 Cl6:0.05Sb 3+ The preparation method includes the following steps:

[0082] (1) Weigh the raw materials according to the composition in Table 1.

[0083] (2) Dissolve SnCl4 and HfCl4 in concentrated hydrochloric acid to prepare SnCl4 solutions with a concentration of 0.12 mol / L and HfCl4 solutions with a concentration of 0.18 mol / L, respectively. Dissolve PtCl4 in a mixed solution of concentrated hydrochloric acid and anhydrous ethanol (volume ratio 5:5) to prepare PtCl4 solutions with a concentration of 0.06 mol / L. Mix the above solutions, stirring continuously at a speed of 200 r / min throughout the process, and maintain the temperature at 65℃.

[0084] (3) Dissolve SbCl3 in concentrated hydrochloric acid to prepare a SbCl3 solution with a concentration of 0.08 mol / L. Add the solution dropwise to the above mixed solution while keeping the magnetic stirrer speed and temperature constant for 9 min.

[0085] (4) Dissolve CsCl in concentrated hydrochloric acid to prepare a CsCl solution with a concentration of 0.30 mol / L. Adjust the speed of the magnetic stirrer to 350 r / min, and use a peristaltic pump to add the prepared CsCl solution to the above mixed solution at a rate of 2 mL / min. The temperature remains constant throughout the process.

[0086] (5) Continue stirring with a magnetic stirrer at a speed of 200 r / min and a temperature of 34°C. After stirring for 30 min, turn off the magnetic stirrer and centrifuge the resulting mixture.

[0087] (6) The obtained solution was centrifuged and washed 6 times at a centrifugation rate of 6000 r / min. The solvents used for centrifugation and washing were in the following order: a mixture of concentrated hydrochloric acid and isopropanol, concentrated hydrochloric acid, isopropanol, isopropanol, concentrated hydrochloric acid and isopropanol.

[0088] (7) The product obtained by centrifugation is placed in a drying oven at 50°C and dried for 2.5 hours. After cooling to room temperature, the intermediate-entropy halogen double perovskite phosphor Cs2(Sn) is obtained. 0.25 Hf 0.2 Pt 0.5 Cl6:0.05Sb 3+ .

[0089] The samples obtained in Examples 1-5 were subjected to fluorescence spectroscopy (Hitachi F-4600, Japan). The emission spectra were measured with an excitation wavelength of 254 nm. The test results are shown in [Figure 1]. Figure 4 .Depend on Figure 4 It can be seen that changing the proportion of the element at position B and Sb 3+ The content of [specific element] can be used to control the emission spectrum of the phosphor. The sample prepared in Example 4 has color coordinates of (0.27, 0.36) and a color temperature of 8034 K, suitable for lighting in industrial plants. The sample prepared in Example 3 has color coordinates of (0.29, 0.39) and a color temperature of 5337 K, suitable for lighting in offices, schools, and hospitals.

[0090] Comparative Example 1

[0091] This comparative example aims to investigate the effect of the volume ratio of concentrated hydrochloric acid to anhydrous ethanol on the purity of phosphor. The remaining steps of this comparative example are the same as those in Example 1, except that the volume ratios of concentrated hydrochloric acid and anhydrous ethanol are 9:1, 7:3, 3:7, and 1:9, respectively.

[0092] XRD analysis of the obtained powder showed that the sample contained a small amount of impurities that could not be removed by centrifugation and washing.

[0093] Comparative Example 2

[0094] The remaining steps of this comparative example are the same as those in Example 1, except that the drying temperature of 60°C in step (8) is replaced with 30°C. Fluorescence spectroscopy tests revealed that the luminescence intensity of the phosphor was weak.

[0095] Comparative Example 3

[0096] The remaining steps of this comparative example are the same as those in Example 1, except that the drying temperature of 60°C in step (8) is replaced with 80°C. The powder turned yellow, and XRD testing revealed that the powder contained a small amount of impurities.

[0097] Comparative Example 4

[0098] The remaining steps in this comparative example are the same as in Example 1, except that Sn and Pt at the B site are removed, leaving only element Hf, to obtain the low-entropy halide double perovskite phosphor Cs₂HfCl₆:0.05Sb. 3+ Fluorescence spectroscopy testing failed to yield a white luminescent phosphor.

Claims

1. A mid-entropy halide double perovskite phosphor, characterized in that: The chemical composition is as follows: Cs2(Sn x Hf y Pt z )Cl6:nSb 3+ Wherein, x+y+z+n=1, and 0.20≤x≤0.50, 0.20≤y≤0.50, 0.20≤z≤0.50, 0<n≤0.

15.

2. A method for preparing the mid-entropy halogen double perovskite phosphor of claim 1, characterized in that, The method comprises the following steps: Step one, according to the stoichiometric ratio, the raw materials are weighed, the Sn-containing compound, the Hf-containing compound are dissolved in concentrated hydrochloric acid to prepare solution A with a concentration of 0.10-0.20 mol / L; The Cs-containing compound is dissolved in concentrated hydrochloric acid to prepare solution B with a concentration of 0.20-0.4 mol / L; the Sb-containing compound is dissolved in concentrated hydrochloric acid to prepare solution C with a concentration of 0.05-0.10 mol / L; The Pt-containing compound is dissolved in a mixed solution of concentrated hydrochloric acid and anhydrous ethanol to prepare solution D with a concentration of 0.05-0.10 mol / L; Step two, mix solution A and solution D, and continuously stir the whole process while keeping the temperature at 40-65℃; Step three, add solution C drop by drop to the product obtained in step two, and stir while keeping the temperature unchanged; Step four, use a peristaltic pump to add solution B to the product obtained in step three, and stir while keeping the temperature unchanged; Step five, keep the temperature at 30-40℃, stir for 15-30 min, and then centrifugally separate the obtained mixture and wash it; Step six, dry the product obtained in step five at 40-60℃, cool it, and obtain the meso-entropy halogen double perovskite fluorescent powder.

3. The method according to claim 2, wherein the method is characterized by: In step one, the Sn-containing compound is SnCl4, the Hf-containing compound is HfCl4, the Cs-containing compound is CsCl, the Sb-containing compound is SbCl3, and the Pt-containing compound is PtCl4.

4. The method according to claim 2, wherein the method is characterized by: In step one, the mass percentage of HCl in the concentrated hydrochloric acid is 37wt%, and the volume percentage of the concentrated hydrochloric acid in the mixed solution of concentrated hydrochloric acid and anhydrous ethanol is 40%-60%.

5. The method according to claim 2, wherein the method is characterized by: In step two, the stirring speed is 100-500 r / min.

6. The method according to claim 2, wherein the method is characterized by: In step three, the stirring time is 5-10 min.

7. The method according to claim 2, wherein the method is characterized by: In step four, the stirring speed is 300-500 r / min, and the adding speed of solution B is 1-5 mL / min.

8. The method according to claim 2, wherein the method is characterized by: In step five, the stirring speed is 100-500 r / min, the centrifugal separation speed is 6000-10000 r / min, and the washing is carried out by one or more of concentrated hydrochloric acid and isopropyl alcohol for multiple times.

9. The method according to claim 2, wherein the method is characterized by: In step six, the drying time is 1-3 h.

10. Application of the meso-entropy halogen double perovskite fluorescent powder according to claim 1 in a white light LED device.

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