Preparation method of multi-doped perovskite fluorescent material

Abstract

A multi-doped, multi-emission perovskite fluorescent material is prepared by adding Sc2O3, Bi2O3, Sb2O3, and Yb2O3 to a mixture of concentrated HCl and NH4Cl to prepare precursor solution I. Precursor solution II is obtained by adding precursor solution I, CsCl, NaCl, AgCl, and MnCl2 to a mixed solvent of ethanol and deionized water. The fluorescent material Cs2Na is then prepared by a hydrothermal reaction. 0.8 Ag 0.2 Sc (0.98‑x‑y‑z) Bi 0.02 Cl6:xSb 3+ ,yMn 2+ ,zYb 3+ The fluorescent material prepared by this invention has good crystallinity, high purity, and uniform morphology. It has good luminescent properties and physical and chemical stability, and can effectively absorb near-ultraviolet light in the range of 200-400nm. It can be applied to full-spectrum warm white LED lighting and near-infrared night vision detection systems excited by current near-ultraviolet chips.

Description

[0001] This patent is a divisional application of invention number 202511255789.X, entitled "A multifunctional application of a multi-emission double perovskite phosphor and its preparation method". Technical Field

[0002] This invention relates to the field of luminescent materials technology, specifically to a method for preparing a multi-doped perovskite fluorescent material. Background Technology

[0003] In the field of lighting and display technology, commercial white LEDs dominate the market due to their advantages such as energy saving and long lifespan. Currently, the mainstream solution is GaInN blue LED chips paired with YAG:Ce LEDs. 3+ Yellow phosphors are widely used in everyday lighting, display backlights, and other applications due to their mature technology and controllable costs.

[0004] However, existing technologies still have significant limitations. In commercial white LEDs, GaInN blue LED chips have a narrow emission angle, resulting in poor illumination uniformity, and the YAG:Ce... 3+ Yellow phosphors lack red light components and have an incomplete spectrum, making it difficult to achieve a warm white light effect with high color rendering, thus failing to meet the demanding requirements of places with stringent light quality requirements, such as museums and photography studios. While near-infrared phosphors possess unique functions, their low luminous efficiency and poor thermal stability limit their large-scale application and make it difficult to achieve high brightness and long-term stable operation. Full-spectrum phosphors, through optimized multicolor phosphor ratios or the development of novel single-matrix materials, achieve continuous spectral emission from the ultraviolet to near-infrared bands, with a color rendering index (CRI) exceeding 95 and a special color rendering index (R9) exceeding 90, enabling accurate reproduction of the true colors of objects. Near-infrared co-emission phosphors, through energy level modulation technology, achieve the coordinated emission of visible and near-infrared light. LED devices made from these phosphors not only meet daily lighting needs but also possess near-infrared light capabilities. In the field of security monitoring, they can achieve clear imaging in low-light environments; in biosensing, the strong penetrating power of near-infrared light makes it suitable for in vivo tissue detection, providing a new means for early disease diagnosis; in the field of communications, they can serve as a light signal emission source, improving the concealment and anti-interference capabilities of data transmission. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-doped, multi-emission double perovskite fluorescent material.

[0006] Another objective of this invention is to provide a method for preparing the aforementioned multi-doped, multi-emission dual perovskite fluorescent material. This method effectively solves the problems encountered in the process of multi-electrode ion doping, such as impurity phase formation, poor crystal grain size uniformity, and numerous defects leading to unsatisfactory luminescent properties and physical and chemical stability of the product. This preparation method represents a breakthrough in full-spectrum and near-infrared co-emission fluorescence technology, opening up new directions for the LED lighting and display industry and promising to drive the industry towards high-quality and multi-functional development.

[0007] The objective of this invention is achieved through the following technical solution: A method for preparing a multi-doped perovskite fluorescent material, characterized in that: Sc2O3, Bi2O3, Sb2O3, and Yb2O3 are added to a mixture of concentrated HCl and NH4Cl to prepare precursor solution I; precursor solution I, CsCl, NaCl, AgCl, and MnCl2 are added to a mixed solvent of ethanol and deionized water to obtain precursor solution II; and then a hydrothermal reaction is carried out.

[0008] Furthermore, the aforementioned multi-doped perovskite fluorescent material uses Cs₂NaScCl₆ as the matrix and Ag₂ as the substrate. + Bi 3+ As a sensitizer, Sb 3+ , Mn 2+ , Yb 3+ The activating ion has the composition Cs₂Na. 0.8 Ag 0.2 Sc (0.98-x-y-z) Bi 0.02 Cl6: xSb 3+ yMn 2+ ,zYb 3+ In the formula, 0 < x <1.5%, 0< y <5%, 0< z <10%.

[0009] Furthermore, the solid-liquid ratio in the precursor solution I is 1:10, the molar ratio of HCl to NH4Cl in the mixed solution is 0.05:0.95~0.1:0.9, and the concentration of concentrated HCl is 37%wt.

[0010] Furthermore, in the mixed solvent, the volume ratio of ethanol to deionized water is 1~3:1, and the volume ratio of the mixed solvent to precursor solution I is 1:1.8~2.2.

[0011] Furthermore, the hydrothermal reaction is first heated from room temperature to 100-120°C and held for 3-4 hours, then heated to 150-170°C and held for 5-7 hours, and finally heated to 210-220°C and held for 20-24 hours, and then naturally cooled to room temperature.

[0012] During the segmented hydrothermal process, in the low-temperature stage, under the low polarity environment of ethanol, Cl in NH4Cl... - This effectively maintains the complexed state of the dopant ions, preventing the complex from dissociating due to excessively high temperatures and inducing ion aggregation. In the second temperature stage, it promotes the preferential formation of Cs₂NaScCl₆ crystal nuclei by matrix ions and NH₄⁺. + Ethanol accelerates the diffusion of matrix ions to the crystal nucleus surface. The weakly polar environment of ethanol lowers the surface energy of the crystal nucleus, thereby regulating the doping sequence of the dopant particles and reducing lattice distortion caused by disordered substitution. At the third temperature, NH4Cl provides Cl... - The process effectively fills vacancies caused by charge mismatch during the reaction, reducing defect generation. In addition, due to the varying degrees of solvent evaporation during the segmented heating process, the lattice repairs local distortions through atomic rearrangement. At the same time, the segmented heating process allows the lattice sufficient time to adapt to multi-element dopant ions, enabling the dopant ions to fully enter the lattice and reducing the generation of dislocations and defects.

[0013] Ethanol weakens the solvation effect of water, allowing Cl to... - It binds more readily to metal ions, reducing the concentration of free ions and mitigating lattice defects caused by ion aggregation at the source. NH4 + By competing for protons to suppress hydrolysis and reduce the precipitation of impurity phases, the high ionic strength generated by this process increases the matrix ion concentration (Cs) through the "salt effect". + Na + ,Sc 3+ The activity of NH4+ promotes the preferential formation of Cs2NaScCl6 crystal nuclei and reduces the probability of impurity phases (such as BiOCl, Yb(OH)Cl2, MnO2, etc.) precipitating due to local overconcentration of dopant ions. Simultaneously, NH4+... + There are hydrogen bonds between it and ethanol molecules, which can inhibit NH4+. + Hydrolysis reduces pH fluctuations in the reaction system, thereby further enhancing the inhibition of impurity phase formation.

[0014] A Cs2Na 0.8 Ag 0.2 Sc (0.98-x-y-z) Bi 0.02 Cl6: xSb 3+ yMn 2+ , zYb 3+ The preparation method of [the substance] is characterized by comprising the following steps: (1) Based on the molecular formula of the target product, Cs2Na 0.8 Ag 0.2 Sc (0.98-x-y-z) Bi 0.02 Cl6: xSb 3+ yMn 2+ , zYb3 + ,0< x <1.5%, 0< y <5%, 0< z <10%, weigh appropriate amounts of CsCl, NaCl, Sc2O3, AgCl, Bi2O3, Sb2O3, MnCl2 and Yb2O3 according to stoichiometric ratio; (2) Add Sc2O3, Bi2O3, Sb2O3, and Yb2O3 to a mixture of HCl solution and NH4Cl, with a solid-liquid ratio of 1:10, a hydrochloric acid concentration of 37%wt, and a molar ratio of NH4Cl to HCl of 0.05:0.95~0.1:0.9. Stir at 70~80℃ for 1h and sonicate for 30min until completely dissolved to obtain mixed precursor solution I; (3) Mix ethanol and deionized water in a volume ratio of 1 to 3:1 to form a mixed solvent, add mixed precursor solution I, and then add CsCl, NaCl, AgCl and MnCl2 in sequence. Stir magnetically at 450 to 550 rpm for 30 min until a homogeneous precursor solution II is formed. The volume ratio of mixed precursor solution I to mixed solvent is 1:1.8 to 2.2. (4) Hydrothermal reaction: Transfer the precursor liquid II from step (3) to a polytetrafluoroethylene-lined reactor (70% filling). First, heat the reactor from room temperature to 100-120°C and keep it at that temperature for 3-4 hours. Then, heat the reactor to 150-170°C and keep it at that temperature for 5-7 hours. Finally, heat the reactor to 210-220°C and keep it at that temperature for 20-24 hours. Cool the reactor to room temperature naturally, filter the crude product, and wash it with anhydrous ethanol. After washing, dry the product at 65-75°C.

[0015] A multi-doped, multi-emission dual perovskite fluorescent material, characterized in that: the fluorescent material is based on Cs₂NaScCl₆ with added Ag + Bi 3+ As a sensitizer, with Sb 3+ , Mn 2+ , Yb 3+ The activating ion has the composition Cs₂Na. 0.8 Ag 0.2 Sc (0.98-x-y-z) Bi 0.02 Cl6: xSb 3+ yMn 2+ , zYb 3+ In the formula, 0 < x <1.5%, 0< y <5%, 0< z <10%.

[0016] Furthermore, the aforementioned multi-emission double perovskite fluorescent material is prepared by adding Sc2O3, Bi2O3, Sb2O3, and Yb2O3 to a mixture of concentrated HCl and NH4Cl to prepare precursor solution I, adding precursor solution I, CsCl, NaCl, AgCl, and MnCl2 to a mixed solvent of ethanol and deionized water to obtain precursor solution II, and then carrying out a hydrothermal reaction.

[0017] Furthermore, the solid-liquid ratio in the precursor solution I is 1:10, the molar ratio of HCl to NH4Cl in the mixed solution is 0.05:0.95~0.1:0.9, the concentration of concentrated HCl is 37%wt, and the volume ratio of ethanol to deionized water in the mixed solvent is 1~3:1, and the volume ratio of the mixed solvent to precursor solution I is 1:1.8~2.2.

[0018] Furthermore, the hydrothermal reaction is first heated from room temperature to 100-120°C and held for 3-4 hours, then heated to 150-170°C and held for 5-7 hours, and finally heated to 210-220°C and held for 20-24 hours, and then naturally cooled to room temperature.

[0019] The present invention has the following technical effects: Cs2Na prepared by this invention 0.8 Ag 0.2 Sc (0.98-x-y-z) Bi 0.02 Cl6: xSb 3+ yMn 2+ , zYb 3+ It has good crystallinity, high purity, and uniform morphology. It has good luminescent properties and physical and chemical stability. It can effectively absorb near-ultraviolet light in the range of 200-400nm and can be used in both full-spectrum warm white LED lighting and near-infrared night vision detection systems excited by near-ultraviolet chips. Attached Figure Description

[0020] Figure 1 The Cs2Na double perovskite phosphor prepared in Example 1 and Comparative Example 1 of this invention 0.8 Ag 0.2 Sc 894 Bi 0.02 Cl6: 0.6%Sb 3+ 3%Mn 2+ 5%Yb 3+ Scanning electron microscope image.

[0021] Figure 2 The double perovskite phosphor Cs2Na prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention 0.8 Ag 0.2 Sc 0.894 Bi 0.02Cl6: 0.6% Sb 3+ 3%Mn 2+ 5%Yb 3+ The X-ray diffraction pattern.

[0022] Figure 3 The double perovskite phosphor Cs2Na prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention 0.8 Ag 0.2 Sc 894 Bi 0.02 Cl6: 0.6% Sb 3+ 3%Mn 2+ 5%Yb 3+ EDS map.

[0023] Figure 4 The double perovskite phosphor Cs2Na prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention 0.8 Ag 0.2 Sc 894 Bi 0.02 Cl6: 0.6% Sb 3+ 3%Mn 2+ 5%Yb 3+ X-ray diffraction pattern after 180 days.

[0024] Figure 5 Example 1 of this invention and various proportions of prepared double perovskite phosphors Cs2Na 0.8 Ag 0.2 Sc 894 Bi 0.02 Cl6: 0.6% Sb 3+ 3%Mn 2+ 5%Yb 3+ The excitation and emission spectra of [the sample]. Detailed Implementation

[0025] The present invention will be specifically described below through embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0026] Example 1 A multi-doped, multi-emission double perovskite fluorescent material Cs2Na 0.8 Ag 0.2 Sc 0.894 Bi 0.02 Cl6: 0.6% Sb 3+ 3%Mn 2+ 5%Yb3+ The preparation method includes the following steps: (1) Based on the molecular formula of the target product, Cs2Na 0.8 Ag 0.2 Sc 0.894 Bi 0.02 Cl6: 0.6% Sb 3+ 3%Mn 2+ 5%Yb 3+ Weigh out the following amounts according to stoichiometric ratios: CsCl (AR) 0.006 mol, NaCl (AR) 0.0024 mol, Sc2O3 (AR) 0.00294 mol, AgCl (AR) 0.0006 mol, Bi2O3 (AR) 0.00003 mol, Sb2O3 (AR) 0.000009 mol, MnCl2 (AR) 0.00009 mol, and Yb2O3 (AR) 0.000075 mol. (2) Add Sc2O3, Bi2O3, Sb2O3 and Yb2O3 to a mixture of concentrated HCl and NH4Cl, with a solid-liquid ratio of 1:10, a concentration of HCl of 37%wt, and a molar ratio of NH4Cl to HCl of 0.05:0.95. Stir at 75℃ for 1h and sonicate for 30min until completely dissolved to obtain mixed precursor solution I; (3) Ethanol and deionized water are mixed in a volume ratio of 2:1 to form a mixed solvent. Mixed precursor solution I is added, and then CsCl, NaCl, AgCl and MnCl2 are added in sequence. The mixture is magnetically stirred at 500 rpm for 30 min until a homogeneous precursor solution II is formed. The volume ratio of the mixed precursor solution I to the mixed solvent is 1:2. (4) Hydrothermal reaction: The precursor liquid II in step (3) is transferred to a polytetrafluoroethylene-lined reactor with a filling degree of 70%. The temperature is first raised from room temperature to 110°C and kept at that temperature for 3 hours, then raised to 160°C and kept at that temperature for 6 hours, and finally raised to 215°C and kept at that temperature for 21 hours. The mixture is then naturally cooled to room temperature, filtered to obtain the crude product, and washed with anhydrous ethanol. After washing, the product is dried at 70°C.

[0027] Comparative Example 1: The difference from Example 1 is that NH4Cl was not added in step (2), while the rest of the steps are the same as in Example 1.

[0028] Comparative Example 2: The difference from Example 1 is that the solvent used in step (3) is an equal volume of deionized water, while the rest of the steps are the same as in Example 1.

[0029] Cs2Na double perovskite phosphors prepared in Example 1 and Comparative Example 1 0.8 Ag 0.2 Sc 0.894 Bi 0.02 Cl6: 0.6% Sb 3 + 3%Mn 2+ 5%Yb 3+ SEM image as follows Figure 1 As shown, the double perovskite phosphor prepared in Example 1 has a uniform grain size with an average particle size of 500 nm ((a) a single particle with a particle size of approximately 500 nm, (b) a large particle composed of multiple single particles with a uniform particle size distribution). In contrast, the double perovskite phosphor prepared in Comparative Example 1 has a generally larger grain size, with a particle size distribution between 0.8 and 2 μm ((c) a single particle in Comparative Example 1 with a particle size greater than 1 μm, (d) a large particle composed of single small particles with an uneven diameter distribution). The size uniformity is poor. Furthermore, when the particle size range is large, the emission peak shifts of different sized grains are inconsistent, which will broaden the overall emission spectrum, disperse the color coordinates (such as exceeding the LED color tolerance standard), and reduce the color temperature stability.

[0030] Cs2Na double perovskite phosphors prepared in Example 1 and various comparative examples 0.8 Ag 0.2 Sc 0.894 Bi 0.02 Cl6: 0.6% Sb 3 + 3%Mn 2+ 5%Yb 3+ The X-ray diffraction pattern is as follows Figure 2 As shown in the figure, the double perovskite phosphor prepared in Example 1 has high crystallinity, no impurity phase formation, and high purity. In contrast, impurity phases appeared in all comparative examples. Comparative Example 1 showed obvious characteristic peaks of the impurity phases BiOCl (2θ=46.7°) and SbOCl (2θ=32.5°). Comparative Example 2 showed Mn... 2+ / Ag + Oxidation produces impurity phases MnO2 (2θ=37.2°) and Ag2O (2θ=31.7°).

[0031] Figure 3 These are the EDS spectra corresponding to Example 1 and Comparative Examples 1 and 2. It can be seen that the elements in Example 1 are evenly distributed, while the comparative examples show that the intensities of some elements are too low, indicating that the experimental steps affected the doping efficiency of the elements.

[0032] Figure 4 It is a double perovskite phosphor Cs2Na 0.8 Ag0.2 Sc 894 Bi 0.02 Cl6: 0.6% Sb 3+ 3%Mn 2+ 5%Yb 3+ The XRD pattern after 180 days shows that the diffraction angle of Example 1 did not change after 180 days, while the diffraction peak shifted in the comparative example, indicating that the product generated by the reaction is unstable in air.

[0033] Comparative Example 3 Compared with Example 1, the difference is that in the hydrothermal reaction process in step (4), a one-step hydrothermal process is used, directly raising the temperature from room temperature to 215°C and holding it for 30 hours. The remaining steps are the same as in Example 1.

[0034] Figure 5 The images show the excitation and emission spectra of the double perovskite phosphors prepared in Example 1 and the comparative examples. It can be seen that Example 1 exhibits the highest excitation and emission spectral intensity. Comparative Examples 1 and 2 show weakened overall luminescence intensity due to insufficient doping and the presence of impurities. Furthermore, Comparative Example 2 shows a new excitation peak, mainly due to intermediate products generated from incomplete reactions during the doping process. Comparative Example 3 also shows unsatisfactory luminescence characteristics due to the presence of numerous dislocations and defects.

[0035] Example 2 A Cs2Na 0.8 Ag 0.2 Sc 0.815 Bi 0.02 Cl6: 1.5% Sb 3+ 5%Mn 2+ 10%Yb 3+ The preparation method includes the following steps: (1) Based on the molecular formula of the target product, Cs2Na 0.8 Ag 0.2 Sc 0.815 Bi 0.02 Cl6: 1.5% Sb 3+ 5%Mn 2+ 10%Yb 3+Weigh out the following amounts according to stoichiometric ratios: CsCl (AR) 0.006 mol, NaCl (AR) 0.0024 mol, Sc2O3 (AR) 0.00294 mol, AgCl (AR) 0.0006 mol, Bi2O3 (AR) 0.00003 mol, Sb2O3 (AR) 0.0000225 mol, MnCl2 (AR) 0.00015 mol, and Yb2O3 (AR) 0.00015 mol. (2) Add Sc2O3, Bi2O3, Sb2O3, and Yb2O3 to a mixture of concentrated HCl and NH4Cl, with a solid-liquid ratio of 1:10 and a molar ratio of NH4Cl to HCl of 0.05:0.95~0.1:0.9. Stir at 70~80℃ for 1 h and sonicate for 30 min until completely dissolved to obtain mixed precursor solution I; (3) Ethanol and deionized water are mixed in a volume ratio of 3:1 to form a mixed solvent. Mixed precursor solution I is added, and then CsCl, NaCl, AgCl and MnCl2 are added in sequence. The mixture is magnetically stirred at 550 rpm for 30 min until a homogeneous precursor solution II is formed. The volume ratio of the mixed precursor solution I to the mixed solvent is 1:1.8. (4) Hydrothermal reaction: The precursor liquid II in step (3) is transferred to a polytetrafluoroethylene-lined reactor (70% filling degree). The temperature is first raised from room temperature to 100°C and kept at that temperature for 3.5 h, then raised to 170°C and kept at that temperature for 5 h, and finally raised to 220°C and kept at that temperature for 20 h. The mixture is then naturally cooled to room temperature, filtered to obtain the crude product, and washed with anhydrous ethanol. After washing, the product is dried at 65°C.

[0036] Example 3 A Cs2Na 0.8 Ag 0.2 Sc 0.968 Bi 0.02 Cl6: 0.1%Sb 3+ 0.1%Mn 2+ 1%Yb 3+ The preparation method includes the following steps: (1) Based on the molecular formula of the target product, Cs2Na 0.8 Ag 0.2 Sc 0.968 Bi 0.02 Cl6: 0.1%Sb 3+ 0.1%Mn 2+ 1%Yb 3+Weigh out the following amounts according to stoichiometric ratios: CsCl (AR) 0.006 mol, NaCl (AR) 0.0024 mol, Sc2O3 (AR) 0.00294 mol, AgCl (AR) 0.0006 mol, Bi2O3 (AR) 0.00003 mol, Sb2O3 (AR) 0.0000015 mol, MnCl2 (AR) 0.00003 mol, and Yb2O3 (AR) 0.000015 mol. (2) Add Sc2O3, Bi2O3, Sb2O3, and Yb2O3 to a mixture of concentrated HCl and NH4Cl, with a solid-liquid ratio of 1:10 and a molar ratio of NH4Cl to HCl of 0.05:0.95~0.1:0.9. Stir at 70~80℃ for 1 h and sonicate for 30 min until completely dissolved to obtain mixed precursor solution I; (3) Ethanol and deionized water are mixed in a volume ratio of 1:1 to form a mixed solvent. Mixed precursor solution I is added, and then CsCl, NaCl, AgCl and MnCl2 are added in sequence. The mixture is magnetically stirred at 450 rpm for 30 min until a homogeneous precursor solution II is formed. The volume ratio of mixed precursor solution I to mixed solvent is 1:2.2. (4) Hydrothermal reaction: The precursor liquid II in step (3) is transferred to a polytetrafluoroethylene-lined reactor (70% filling degree). The temperature is first raised from room temperature to 120°C and kept at that temperature for 3 hours, then raised to 150°C and kept at that temperature for 7 hours, and finally raised to 210°C and kept at that temperature for 24 hours. The mixture is then naturally cooled to room temperature, filtered to obtain the crude product, and washed with anhydrous ethanol. After washing, the product is dried at 75°C.

Claims

1. A method for preparing a multi-doped perovskite fluorescent material, characterized in that: The precursor solution I is prepared by adding Sc2O3, Bi2O3, Sb2O3, and Yb2O3 to a mixture of concentrated HCl and NH4Cl. Precursor solution II is obtained by adding precursor solution I, CsCl, NaCl, AgCl, and MnCl2 to a mixed solvent of ethanol and deionized water. Then, a hydrothermal reaction is carried out to prepare a precursor solution with Cs2NaScCl6 as the matrix and Ag... + Bi 3+ As a sensitizer, Sb 3+ , Mn 2+ , Yb 3+ Fluorescent materials for activating ions.

2. The method for preparing a multi-doped perovskite fluorescent material as described in claim 1, characterized in that: The fluorescent material has the composition Cs2Na. 0.8 Ag 0.2 Sc (0.98-x-y-z) Bi 0.02 Cl6: xSb 3+ yMn 2+ , zYb 3+ In the formula, 0 < x <1.5%, 0< y <5%, 0< z <10%.

3. The method for preparing a multi-doped perovskite fluorescent material as described in claim 2, characterized in that: The solid-liquid ratio in the precursor solution I is 1:10, the molar ratio of HCl to NH4Cl in the mixture is 0.05:0.95~0.1:0.9, and the concentration of concentrated HCl is 37%wt.

4. A method for preparing a multi-doped perovskite fluorescent material as described in any one of claims 1-3, characterized in that: In the mixed solvent, the volume ratio of ethanol to deionized water is 1~3:1, and the volume ratio of the mixed solvent to precursor solution I is 1:1.8~2.

2.

5. A method for preparing a multi-doped perovskite fluorescent material as described in any one of claims 1-4, characterized in that: The hydrothermal reaction involves first raising the temperature from room temperature to 100-120°C and holding it there for 3-4 hours, then raising the temperature to 150-170°C and holding it there for 5-7 hours, and finally raising the temperature to 210-220°C and holding it there for 20-24 hours, followed by natural cooling to room temperature.

6. A multi-emission double perovskite phosphor Cs2Na 0.8 Ag 0.2 Sc 0.894 Bi 0.02 Cl6: 0.6% Sb 3+ 3%Mn 2+ 5%Yb 3+ The preparation method of the [method] is characterized by, Includes the following steps: (1) Based on the molecular formula of the target product, Cs2Na 0.8 Ag 0.2 Sc 0.894 Bi 0.02 Cl6: 0.6% Sb 3+ 3%Mn 2+ 5%Yb 3+ Weigh CsCl, NaCl, Sc2O3, AgCl, Bi2O3, Sb2O3, MnCl2 and Yb2O3 according to their stoichiometric ratios. (2) Add Sc2O3, Bi2O3, Sb2O3 and Yb2O3 to a mixture of concentrated HCl and NH4Cl, with a solid-liquid ratio of 1:10, a concentration of HCl of 37%wt, and a molar ratio of NH4Cl to HCl of 0.05:0.

95. Stir at 75℃ for 1h and sonicate for 30min until completely dissolved to obtain mixed precursor solution I; (3) Ethanol and deionized water are mixed in a volume ratio of 2:1 to form a mixed solvent. Mixed precursor solution I is added, and then CsCl, NaCl, AgCl and MnCl2 are added in sequence. The mixture is magnetically stirred at 500 rpm for 30 min until a homogeneous precursor solution II is formed. The volume ratio of the mixed precursor solution I to the mixed solvent is 1:

2. (4) Hydrothermal reaction: The precursor liquid II in step (3) is transferred to a polytetrafluoroethylene-lined reactor with a filling degree of 70%. The temperature is first raised from room temperature to 110°C and kept at that temperature for 3 hours, then raised to 160°C and kept at that temperature for 6 hours, and finally raised to 215°C and kept at that temperature for 21 hours. The mixture is then naturally cooled to room temperature, filtered to obtain the crude product, and washed with anhydrous ethanol. After washing, the product is dried at 70°C.

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