A high-performance Cs2HfCl6 double perovskite, its preparation method and application

Abstract

This invention belongs to the field of perovskite phosphor technology, and relates to a high-performance Cs₂HfCl₆ double perovskite, its preparation method, and its applications. This invention utilizes a rationally designed [Hmim]Cl ligand to enable a strong chemical interaction between the ligand and CHC DPs. The synergistic effect of the imidazole cation and chloride ion in [Hmim]Cl not only interacts with the uncoordinated Hf on the microcrystalline surface... 4+ Coordination can also supply excess chloride ions to the surface of CHC DPs, effectively controlling the crystallization rate of perovskite and isolating DPs from ambient water; thus endowing CHC DPs with excellent optical properties and stability.

Description

Technical Field

[0001] This invention belongs to the field of perovskite phosphor technology, and relates to a high-performance Cs2HfCl6 double perovskite, its preparation method and application. Background Technology

[0002] All-inorganic halide double perovskites possess excellent photoelectronic properties such as high absorption coefficient, tunable bandgap, and wideband luminescence, making them promising candidates for applications in solar cells, photodetectors, and light-emitting diodes. To date, the main technologies for preparing double perovskites include hot-injection, hydrothermal, and water / oil bath methods. These methods typically require specific conditions such as high temperature / high pressure and specialized equipment, resulting in complex processes and hindering large-scale industrial production. In recent years, considering the low lattice formation energy and rapid crystallization rate of double perovskites, several effective strategies for scalable synthesis of double perovskites at room temperature have been investigated.

[0003] However, the biggest challenge is that the products obtained at room temperature typically exhibit low photoluminescence efficiency, far from practical applications. This is mainly due to insufficient energy during nucleation and growth at low temperatures, resulting in rapid and uncontrollable crystallization. Therefore, a specific technology is needed to achieve the controllable, large-scale preparation of highly efficient and stable double perovskite phosphors.

[0004] Chinese patent application document (publication number: CN115717072A) discloses a method for preparing lead-free perovskite microcrystals and their application. The method involves adding high-purity raw materials CsCl, HfCl4, and TeCl4 to a reaction vessel, adding HCl solution, and mixing thoroughly to obtain a reaction system. The reaction system is then placed at 170-190℃ for 9-12 hours, cooled to room temperature, washed with anhydrous ethanol, and subjected to solid-liquid separation. The solid is then dried to obtain lead-free perovskite microcrystals Cs2HfCl6:TeCl4. 4+ Lead-free perovskite micron-sized crystals Cs2HfCl6:Te 4+ White LED diodes are formed by encapsulating blue LED chips with epoxy resin, and the white LED diode is formed by adjusting the lead-free perovskite micron crystal Cs2HfCl6:Te. 4+ The ratio of epoxy resin to terephthalic acid (Te) allows for color temperature control from cool white to warm white light. However, it has the following drawbacks: ① Hydrothermal synthesis in the reactor involves high-temperature conditions and special equipment such as ovens, as well as a long synthesis time, which obviously increases the synthesis cost. Especially in large-scale production, rapid and controllable synthesis is not possible, all of which restrict their commercial production; ② Te 4+Single-doped Cs₂HfCl₆ suffers from an untunable emission spectrum and a limited range. In particular, the CRI value, a crucial performance parameter of WLEDs, corresponds to the spectral coverage, which is essential for restoring the true color of objects and creating a healthy and comfortable atmosphere. Single-doped phosphors will undoubtedly struggle to achieve high CRI values. Furthermore, under prolonged irradiation on blue LED chips, halogen ions easily migrate, leading to problems such as emission color shift and reduced efficiency. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in the existing technology by providing a method for achieving efficient Bi synthesis using the ionic liquid [Hmim]Cl. 3+ / Te 4+ High-performance Cs2HfCl6 double perovskites can be prepared controllably by co-doping Cs2HfCl6.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A high-performance Cs₂HfCl₆ double perovskite, wherein the double perovskite utilizes ionic liquid-assisted Bi 3+ / Te 4+ Co-doped Cs2HfCl6.

[0008] In the aforementioned high-performance Cs2HfCl6 double perovskite, the ionic liquid is [Hmim]Cl.

[0009] This invention also provides a method for preparing the above-mentioned high-performance Cs2HfCl6 double perovskite, the method specifically comprising the following steps:

[0010] S1. Dissolve BiCl3, TeO2, CsCl, and HfCl4 in HCl solution in sequence to obtain solutions A, B, C, and D.

[0011] S2. Add solutions A and B to solution D and stir, then add the ionic liquid and stir.

[0012] S3. Continue to slowly add solution C to solution D while stirring until the reaction is complete;

[0013] S4. After the reaction is complete, centrifuge to collect the precipitate, wash it with ethanol, dry it, and finally grind it into powder to obtain high-performance Cs2HfCl6 double perovskite.

[0014] In the above-mentioned method for preparing a high-performance Cs2HfCl6 double perovskite, the concentration of HCl solution in step S1 is 30-40 (v / v)%.

[0015] Preferably, the solution in step S1 is a clear solution to ensure that the precursor is completely dissolved in the solution.

[0016] In the above-mentioned method for preparing high-performance Cs2HfCl6 double perovskite, the concentration of BiCl3 in solution A in step S1 is 0.05-0.12 mmol / mL, the concentration of TeO2 in solution B is 0.05-0.12 mmol / mL, the concentration of CsCl in solution C is 0.15-0.25 mmol / mL, and the concentration of HfCl4 in solution D is 0.05-0.12 mmol / mL.

[0017] Preferably, in step S1, the concentration of BiCl3 in solution A is 0.1 mmol / mL, the concentration of TeO2 in solution B is 0.1 mmol / mL, the concentration of CsCl in solution C is 0.2 mmol / mL, and the concentration of HfCl4 in solution D is 0.1 mmol / mL.

[0018] In the above-mentioned method for preparing high-performance Cs2HfCl6 double perovskite, the volume ratio of solution D to solutions A and B in step S2 is 1:0.06:(0.0016-0.04).

[0019] In the above-mentioned method for preparing high-performance Cs2HfCl6 double perovskite, the volume ratio of solution D and ionic liquid in step S2 is 1:(0.01-0.32).

[0020] In this invention, the synthesis and optical properties of the double perovskite powder are strictly affected by the concentration of doped ions, the content of ionic liquid, and the preparation process.

[0021] This invention requires strict control over the amount of doped ions and ionic liquids added, Bi 3+ After doping, the spectrum emits blue light, Te 4+ The doped spectrum emits yellow light; the Bi content can be adjusted appropriately according to the desired emission color. 3+ and Te 3+ The doping ratio is crucial. If the obtained Cs₂HfCl₆ double perovskite is used to fabricate white light-emitting diodes (WLEDs), the amount of ionic liquid added (in 10 mL of solution D) is generally 350-450 μL. If too little ionic liquid [Hmim]Cl is added, the modulation effect will be insignificant, the efficiency will be low, and it will be difficult to adjust to pure white light at (0.33, 0.33) on the spectral color coordinates. If too much is added, new impurities will be introduced into the crystal lattice, which will not only reduce the efficiency but also deviate from pure white light.

[0022] Preferably, the ethanol concentration in step S4, ethanol washing, is ≥99.7%. Because prolonged contact with water promotes sample decomposition, the ethanol concentration needs to be strictly controlled in this invention.

[0023] In the above-mentioned method for preparing high-performance Cs2HfCl6 double perovskite, the drying temperature in step S4 is 60-80℃ and the time is 2-5h.

[0024] The present invention also provides a perovskite phosphor, wherein the perovskite phosphor comprises the above-mentioned high-performance Cs2HfCl6 double perovskite.

[0025] The present invention also provides an application of the above-mentioned perovskite phosphor in the fields of lighting or anti-counterfeiting technology.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. This invention uses room temperature solvent synthesis, which greatly reduces process complexity, preparation cost and time cost compared to conventional synthesis methods such as hot injection, hydrothermal method and water / oil bath method.

[0028] 2. This invention utilizes a rationally designed [Hmim]Cl ligand to enable a strong chemical interaction between the ligand and CHC DPs. The synergistic effect of the imidazole cation and chloride ion in [Hmim]Cl not only interacts with the uncoordinated Hf on the microcrystalline surface... 4+ Coordination can also supply excess chloride ions to the surface of CHC DPs, effectively controlling the crystallization rate of perovskite and isolating DPs from ambient water; thus endowing CHC DPs with excellent optical properties and stability.

[0029] 3. The [Hmim]Cl ligand introduced in this invention can effectively eliminate perovskite surface defects, fundamentally limiting vacancy-mediated chloride ion migration and increasing the migration barrier of halide ions in CHC DPs. Correspondingly, the prepared CHC DPs exhibit a PL QY as high as 96.4%, twice the highest record reported in this field.

[0030] 4. The present invention uses [Hmim]Cl to cover the perovskite surface, and the resulting CHC DPs have strong photostability. After 12 days of continuous UV lamp irradiation, they retain 92.48% of the original PL intensity, which is much higher than the 57.11% intensity of the original sample without [Hmim]Cl modification. The improved photostability after passivation is beneficial to practical optoelectronic applications. Attached Figure Description

[0031] Figure 1 The Cs2HfCl6:3%Bi prepared in Example 1 of this invention 3+ The excitation and emission spectra of [the material].

[0032] Figure 2 The Cs2HfCl6:2%Te prepared in Example 2 of this invention 4+ The excitation and emission spectra of [the material].

[0033] Figure 3 The Cs2HfCl6:3%Bi prepared in Example 3 of this invention 3+ / 2%Te 4+ Scanning electron microscope image.

[0034] Figure 4 The Cs₂HfCl₆:3%Bi treated with ionic liquid obtained in Example 4 of this invention 3+ / 2%Te 4+ Scanning electron microscope image.

[0035] Figure 5 The Cs2HfCl6:3%Bi prepared in Example 3 of this invention 3+ / 2%Te 4+ The particle size distribution histogram.

[0036] Figure 6 The Cs₂HfCl₆:3%Bi prepared in Example 4 of this invention after treatment with added ionic liquid is shown. 3+ / 2%Te 4+ The particle size distribution histogram.

[0037] Figure 7 The Cs2HfCl6:3%Bi prepared in Example 3 of this invention 3+ / 2%Te 4+ Transmission electron microscope image.

[0038] Figure 8 Example 4 of this invention yielded Cs₂HfCl₆:3%Bi treated with ionic liquid. 3+ / 2%Te 4+ Transmission electron microscope image.

[0039] Figure 9 Example 4 of this invention yielded Cs₂HfCl₆:3%Bi after treatment with different amounts of ionic liquid. 3+ / 2%Te 4+ The graph shows the change in quantum yield.

[0040] Figure 10 Example 4 of this invention yielded Cs₂HfCl₆:3%Bi treated with ionic liquid. 3+ / 2%Te 4+ The ultraviolet-visible absorption and steady-state photoluminescence spectra.

[0041] Figure 11 The Cs2HfCl6:3%Bi prepared in Example 3 of this invention 3+ / 2%Te 4+ The emission spectrum after Gaussian fitting.

[0042] Figure 12 The Cs₂HfCl₆:3%Bi solution prepared in Example 4 of this invention after treatment with added ionic liquid is shown. 3+ / 2%Te 4+ The emission spectrum after Gaussian fitting.

[0043] Figure 13 The Cs2HfCl6:3%Bi prepared in Example 3 of this invention 3+ / 2%Te 4+ Emission intensity variation over 12 days under high-intensity ultraviolet light irradiation.

[0044] Figure 14 The Cs₂HfCl₆:3%Bi solution prepared in Example 3 of this invention after treatment with ionic liquid is shown. 3+ / 2%Te 4+ Emission intensity variation over 12 days under high-intensity ultraviolet light irradiation.

[0045] Figure 15 The Cs₂HfCl₆:3%Bi solution prepared in Example 4 of this invention after treatment with added ionic liquid is shown. 3+ / 2%Te 4+ Scanning electron microscope image after being exposed to air for 5 months.

[0046] Figure 16 The Cs₂HfCl₆:3%Bi solution prepared in Example 5 of this invention after treatment with ionic liquid is shown. 3+ / 0.08%Te 4+ The color coordinate diagram of white light emitting diodes (WLEDs) fabricated using phosphors combined with commercial chips.

[0047] Figure 17 The Cs₂HfCl₆:3%Bi solution prepared in Example 6 of this invention after treatment with ionic liquid is shown. 3+ / 0.1%Te 4+ Multimodal anti-counterfeiting images prepared with fluorescent powder. Detailed Implementation

[0048] The following are specific embodiments of the present invention, which further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0049] Example 1:

[0050] S1. Dissolve 1 mmol BiCl3 in 10 mL of 37% HCl solution in a glass bottle. Stir with a magnetic stirrer for 10 min at room temperature until completely dissolved. This solution is denoted as solution A1.

[0051] S2. First, dissolve 2 mmol of CsCl in a 5 mL glass bottle of 37% HCl solution (denoted as solution C), and then stir with a magnetic stirrer for 10 min. At the same time, dissolve 1 mmol of HfCl4 in a 5 mL glass bottle of 37% HCl solution (denoted as solution D).

[0052] S3. Add 300 μL of solution A1 to solution D and stir continuously for 10 min. Then, under vigorous stirring, slowly add solution C to solution D using a pipette. When the two solutions are completely mixed, a white precipitate immediately forms in the solution. During this process, continuously add solution C dropwise while stirring for 20 min until the reaction is complete.

[0053] S4. After stopping stirring, centrifuge the suspension at 4000 rpm for 5 minutes to separate larger particles from the suspension. Pour off the supernatant, collect the precipitate, and wash with 99.7% anhydrous ethanol. Repeat the washing with anhydrous ethanol 2-3 times.

[0054] S5. The final precipitate is dried in a forced-air oven at 70°C for more than 3 hours to remove residual ethanol. The dried sample is then ground into powder for further characterization.

[0055] Example 2:

[0056] S1. Dissolve 1 mmol of TeO2 in 10 mL of 37% HCl solution in a glass bottle. Stir with a magnetic stirrer for 10 min at room temperature until completely dissolved. This solution is called solution B.

[0057] S2. First, dissolve 2 mmol of CsCl in a 5 mL glass bottle of 37% HCl solution (denoted as solution C), and then stir with a magnetic stirrer for 10 min. At the same time, dissolve 1 mmol of HfCl4 in a 5 mL glass bottle of 37% HCl solution (denoted as solution D).

[0058] S3. Add 200 μL of solution B to solution D and stir continuously for 10 min. Then, under vigorous stirring, slowly add solution C to solution D using a pipette. When the two solutions are completely mixed, a white precipitate immediately forms in the solution. During this process, continuously add solution C dropwise while stirring for 20 min until the reaction is complete.

[0059] S4. After stopping stirring, centrifuge the suspension at 4000 rpm for 5 minutes to separate larger particles from the suspension. Pour off the supernatant, collect the precipitate, and wash with 99.7% anhydrous ethanol. Repeat the washing with anhydrous ethanol 2-3 times.

[0060] S5. The final precipitate was dried in a forced-air oven at 70°C for at least 3 hours to remove residual ethanol. The dried sample was then ground into powder for further characterization.

[0061] Example 3:

[0062] S1. Dissolve 1 mmol BiCl3 and 1 mmol TeO2 in 10 mL of 37% HCl solution in a glass bottle, respectively. Stir with a magnetic stirrer for 10 min at room temperature until completely dissolved. These solutions are labeled as solution A and solution B.

[0063] S2. First, dissolve 2 mmol of CsCl in a 5 mL glass bottle of 37% HCl solution (denoted as solution C), and then stir with a magnetic stirrer for 10 min. At the same time, dissolve 1 mmol of HfCl4 in a 5 mL glass bottle of 37% HCl solution (denoted as solution D).

[0064] S3. Add 300 μL of solution A and 200 μL of solution B to solution D, and stir continuously for 10 min. Then, under vigorous stirring, slowly add solution C to solution D using a pipette. When the two solutions are completely mixed, a white precipitate immediately forms in the solution. During this process, continuously add solution C dropwise, stirring for 20 minutes, until the reaction is complete.

[0065] S4. After stopping stirring, centrifuge the suspension at 4000 rpm for 5 minutes to separate larger particles from the suspension. Pour off the supernatant, collect the precipitate, and wash with 99.7% anhydrous ethanol. Repeat the washing with anhydrous ethanol 2-3 times.

[0066] S5. The final precipitate was dried in a forced-air oven at 70°C for at least 3 hours to remove residual ethanol. The dried sample was then ground into powder for further characterization.

[0067] Example 4:

[0068] S1. Dissolve 1 mmol BiCl3 and 1 mmol TeO2 in 10 mL of 37% HCl solution in a glass bottle, respectively. Stir with a magnetic stirrer for 10 min at room temperature until completely dissolved. These solutions are labeled as solution A and solution B.

[0069] S2. First, dissolve 2 mmol of CsCl in a 5 mL glass bottle of 37% HCl solution (denoted as solution C), and then stir with a magnetic stirrer for 10 min. At the same time, dissolve 1 mmol of HfCl4 in a 5 mL glass bottle of 37% HCl solution (denoted as solution D).

[0070] S3. Add 300 μL of solution A and 200 μL of solution B to solution D, and stir continuously for 10 min. Then add 800 μL of [Hmim]Cl to solution D and stir continuously for 10 min. During this process, a white flocculent substance will be formed. Then, under vigorous stirring, slowly add solution C to solution D using a pipette. When the two solutions are completely mixed, a white precipitate will immediately form in the solution. During this process, continuously add solution C dropwise while stirring for 20 minutes until the reaction is complete.

[0071] S4. After stopping stirring, centrifuge the suspension at 4000 rpm for 5 minutes to separate larger particles from the suspension. Pour off the supernatant, collect the precipitate, and wash with 99.7% anhydrous ethanol. Repeat the washing with anhydrous ethanol 2-3 times.

[0072] S5. The final precipitate was dried in a forced-air oven at 70°C for at least 3 hours to remove residual ethanol. The dried sample was then ground into powder for further characterization.

[0073] Example 5:

[0074] S1. Dissolve 1 mmol BiCl3 and 1 mmol TeO2 in 10 mL of 37% HCl solution in a glass bottle, respectively. Stir with a magnetic stirrer for 10 min at room temperature until completely dissolved. These solutions are labeled as solution A and solution B.

[0075] S2. First, dissolve 2 mmol of CsCl in a 5 mL glass bottle of 37% HCl solution (denoted as solution C), and then stir with a magnetic stirrer for 10 min. At the same time, dissolve 1 mmol of HfCl4 in a 5 mL glass bottle of 37% HCl solution (denoted as solution D).

[0076] S3. Add 300 μL of solution A and 8 μL of solution B to solution D, and stir continuously for 10 min. Then add 400 μL of [Hmim]Cl to solution D and stir continuously for 10 min. During this process, a white flocculent substance will be formed. Then, under vigorous stirring, slowly add solution C to solution D using a pipette. When the two solutions are completely mixed, a white precipitate will immediately form in the solution. During this process, continuously add solution C dropwise while stirring for 20 minutes until the reaction is complete.

[0077] S4. After stopping stirring, centrifuge the suspension at 4000 rpm for 5 minutes to separate larger particles from the suspension. Pour off the supernatant, collect the precipitate, and wash with 99.7% anhydrous ethanol. Repeat the washing with anhydrous ethanol 2-3 times.

[0078] S5. The final precipitate was dried in a forced-air oven at 70°C for at least 3 hours to remove residual ethanol. The dried sample was then ground into powder for further characterization.

[0079] Example 6:

[0080] S1. Dissolve 1 mmol BiCl3 and 1 mmol TeO2 in 10 mL of 37% HCl solution in a glass bottle, respectively. Stir with a magnetic stirrer for 10 min at room temperature until completely dissolved. These solutions are labeled as solution A and solution B.

[0081] S2. First, dissolve 2 mmol of CsCl in a 5 mL glass bottle of 37% HCl solution (denoted as solution C), and then stir with a magnetic stirrer for 10 min. At the same time, dissolve 1 mmol of HfCl4 in a 5 mL glass bottle of 37% HCl solution (denoted as solution D).

[0082] S3. Add 300 μL of solution A and 10 μL of solution B to solution D, and stir continuously for 10 min. Then add 400 μL of [Hmim]Cl to solution D and stir continuously for 10 min. During this process, a white flocculent substance will be formed. Then, under vigorous stirring, slowly add solution C to solution D using a pipette. When the two solutions are completely mixed, a white precipitate will immediately form in the solution. During this process, continuously add solution C dropwise while stirring for 20 minutes until the reaction is complete.

[0083] S4. After stopping stirring, centrifuge the suspension at 4000 rpm for 5 minutes to separate larger particles from the suspension. Pour off the supernatant, collect the precipitate, and wash with 99.7% anhydrous ethanol. Repeat the washing with anhydrous ethanol 2-3 times.

[0084] S5. The final precipitate was dried in a forced-air oven at 70°C for at least 3 hours to remove residual ethanol. The dried sample was then ground into powder for further characterization.

[0085] Figure 1 The Cs2HfCl6:3%Bi prepared in Example 1 of this invention 3+ The excitation and emission spectra of [the material]. Figure 1 To demonstrate that the emission spectrum of Cs2HfCl6 doped with Bi ions exhibits broadband emission and a large Stokes shift, the optimal excitation and emission peak positions are 353 nm and 453 nm, respectively.

[0086] Figure 2 The Cs2HfCl6:2%Te prepared in Example 2 of this invention 4+ The excitation and emission spectra of [the material]. Figure 2The emission spectrum of Cs2HfCl6 doped with Te ions shows broadband emission with a large Stokes shift, and the optimal excitation and emission peaks are 388 nm and 553 nm, respectively.

[0087] Figure 3 The Cs2HfCl6:3%Bi prepared in Example 3 of this invention 3+ / 2%Te 4+ Scanning electron microscope image. Figure 3 This demonstrates the rapid preparation of Cs₂HfCl₆:3%Bi at room temperature. 3+ / 2%Te 4+ Its microscopic irregular morphology and uneven size.

[0088] Figure 4 The Cs₂HfCl₆:3%Bi treated with ionic liquid obtained in Example 4 of this invention 3+ / 2%Te 4+ Scanning electron microscope image. Figure 4 This demonstrates the rapid preparation of Cs₂HfCl₆:3%Bi using the ionic liquid [Hmim]Cl at room temperature. 3+ / 2%Te 4+ It has a relatively regular microscopic morphology and uniform size.

[0089] Figure 5 The Cs2HfCl6:3%Bi prepared in Example 3 of this invention 3+ / 2%Te 4+ The particle size distribution histogram. Figure 5 This demonstrates the rapid preparation of Cs₂HfCl₆:3%Bi at room temperature. 3+ / 2%Te 4+ The average grain size is approximately 0.78 μm.

[0090] Figure 6 The Cs₂HfCl₆:3%Bi prepared in Example 4 of this invention after treatment with added ionic liquid is shown. 3+ / 2%Te 4+ The particle size distribution histogram. Figure 6 Showing Figure 5 This demonstrates the rapid preparation of Cs₂HfCl₆:3%Bi at room temperature. 3+ / 2%Te 4+ The average grain size is approximately 3.73 μm. This indicates that ionic liquids can delay crystallization, allowing for sufficient material diffusion during the crystallization process.

[0091] Figure 7 The Cs2HfCl6:3%Bi prepared in Example 3 of this invention 3+ / 2%Te 4+ Transmission electron microscope image. Figure 7It showed Cs2HfCl6:3%Bi 3+ / 2%Te 4+ lattice stripes.

[0092] Figure 8 Example 4 of this invention yielded Cs₂HfCl₆:3%Bi treated with ionic liquid. 3+ / 2%Te 4+ Transmission electron microscope image. Figure 8 This demonstrates the rapid preparation of Cs₂HfCl₆:3%Bi assisted by the ionic liquid [Hmim]Cl. 3+ / 2%Te 4+ The sample surface is coated with ionic liquid, forming a core-shell-like sample structure, which helps to prevent degradation by water and oxygen in the air.

[0093] Figure 9 Example 4 of this invention yielded Cs₂HfCl₆:3%Bi after treatment with different amounts of ionic liquid. 3+ / 2%Te 4+ The graph shows the change in quantum yield. Figure 9 This demonstrates the rapid preparation of Cs₂HfCl₆:3%Bi assisted by the ionic liquid [Hmim]Cl. 3+ / 2%Te 4+ The quantum yield increases with increasing [Hmim]Cl, but decreases after reaching 800 μL, which may be due to excessive ionic liquid entering the lattice and generating impurities; however, the efficiency is still much higher than that of the unmodified sample.

[0094] Figure 10 Example 4 of this invention yielded Cs₂HfCl₆:3%Bi treated with ionic liquid. 3+ / 2%Te 4+ The ultraviolet-visible absorption and steady-state photoluminescence spectra. Figure 10 This demonstrates the rapid preparation of Cs₂HfCl₆:3%Bi assisted by the ionic liquid [Hmim]Cl. 3+ / 2%Te 4+ Both absorption and emission intensities have been improved, which is related to Figure 9 The results corroborate this.

[0095] Figure 11 The Cs2HfCl6:3%Bi prepared in Example 3 of this invention 3+ / 2%Te 4+ Emission spectrum after Gaussian fitting; Figure 12 The Cs₂HfCl₆:3%Bi solution prepared in Example 4 of this invention after treatment with added ionic liquid is shown. 3+ / 2%Te 4+ The emission spectrum after Gaussian fitting. Figure 11 and12 The preparation of Cs₂HfCl₆:3%Bi assisted by ionic liquid [Hmim]Cl was demonstrated. 3+ / 2%Te 4+ The spectrum, after Gaussian fitting, exhibits a blue shift, indicating that the defects have been passivated and nonradiative recombination has been reduced. This, in principle, proves... Figure 9-10 Improved efficiency.

[0096] Figure 13 The Cs2HfCl6:3%Bi prepared in Example 3 of this invention 3+ / 2%Te 4+ Emission intensity variation over 12 days under high-intensity ultraviolet light irradiation; Figure 14 The Cs₂HfCl₆:3%Bi solution prepared in Example 3 of this invention after treatment with ionic liquid is shown. 3+ / 2%Te 4+ Emission intensity variation over 12 days under high-intensity ultraviolet light irradiation. Figure 13 and 14 It was demonstrated that after treatment with ionic liquid, Cs2HfCl6:3%Bi 3+ / 2%Te 4+ Even after 12 days of high-intensity ultraviolet light irradiation, it can still maintain good initial strength, and its excellent photostability shows that the material has broad application prospects.

[0097] Figure 15 The Cs₂HfCl₆:3%Bi solution prepared in Example 4 of this invention after treatment with added ionic liquid is shown. 3+ / 2%Te 4+ Scanning electron microscope image after being exposed to air for 5 months. Figure 15 It was demonstrated that after treatment with ionic liquid, Cs2HfCl6:3%Bi 3+ / 2%Te 4+ Even after being exposed to air for 5 months, it still maintains a good initial morphology and structure, and its excellent stability shows that the material has broad application prospects.

[0098] Figure 16 The Cs₂HfCl₆:3%Bi solution prepared in Example 5 of this invention after treatment with ionic liquid is shown. 3+ / 0.08%Te 4+ The color coordinate diagram of white light emitting diodes (WLEDs) fabricated using phosphors combined with commercial chips. Figure 16 The color chart demonstrates that after treatment with ionic liquid, Cs2HfCl6:3%Bi 3+ / 0.08%Te 4+ White light emitting diodes (WLEDs) fabricated using phosphors combined with commercial chips can emit near-pure white light, indicating that the samples have broad prospects in lighting applications.

[0099] Figure 17 The Cs₂HfCl₆:3%Bi solution prepared in Example 6 of this invention after treatment with ionic liquid is shown. 3+ / 0.1%Te 4+ Multimodal anti-counterfeiting images prepared with fluorescent powder. Figure 17 It was demonstrated that after treatment with ionic liquid, Cs2HfCl6:3%Bi 3+ / 0.08%Te 4+ The fact that fluorescent powder can emit different colors under light of different wavelengths indicates that the sample has broad prospects in the field of complex anti-counterfeiting technology.

[0100] The embodiments described herein cover any points not exhaustively within the scope of the technical claims of this invention, as well as new technical solutions formed by equivalent substitutions of one or more technical features in the embodiments. These are all within the scope of the claims of this invention. Furthermore, in all listed or unlisted embodiments of this invention, each parameter in the same embodiment merely represents an instance (i.e., a feasible solution) of its technical solution, and there is no strict coordination or limitation relationship between the parameters. The parameters can be substituted for each other without violating axioms and the claims of this invention, unless otherwise stated.

[0101] The technical means disclosed in this invention are not limited to those described above, but also include technical solutions composed of any combination of the above technical features. The above descriptions are specific embodiments of this invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention.

[0102] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A high-performance Cs₂HfCl₆ double perovskite, characterized in that, The double perovskite utilizes an ionic liquid-assisted Bi 3+ / Te 4+ The co-doped Cs₂HfCl₆ is used, and the ionic liquid is [Hmim]Cl.

2. A method for preparing high-performance Cs₂HfCl₆ double perovskite as described in claim 1, characterized in that, The method specifically includes the following steps: S1. Dissolve BiCl3, TeO2, CsCl, and HfCl4 in HCl solution in sequence to obtain solutions A, B, C, and D. S2. Add solutions A and B to solution D and stir. Then add an ionic liquid and stir. The ionic liquid is [Hmim]Cl. S3. Continue to slowly add solution C to solution D while stirring until the reaction is complete; S4. After the reaction is complete, centrifuge to collect the precipitate, wash it with ethanol, dry it, and finally grind it into powder to obtain high-performance Cs2HfCl6 double perovskite.

3. The method for preparing a high-performance Cs₂HfCl₆ double perovskite according to claim 2, characterized in that, In step S1, the concentration of the HCl solution is 30-40 (v / v)%.

4. The method for preparing a high-performance Cs₂HfCl₆ double perovskite according to claim 2, characterized in that, In step S1, the concentration of BiCl3 in solution A is 0.05-0.12 mmol / mL, the concentration of TeO2 in solution B is 0.05-0.12 mmol / mL, the concentration of CsCl in solution C is 0.15-0.25 mmol / mL, and the concentration of HfCl4 in solution D is 0.05-0.12 mmol / mL.

5. The method for preparing a high-performance Cs₂HfCl₆ double perovskite according to claim 2, characterized in that, In step S2, the volume ratio of solution D to solutions A and B is 1:0.06:(0.0016-0.04).

6. The method for preparing a high-performance Cs₂HfCl₆ double perovskite according to claim 2, characterized in that, The volume ratio of solution D to ionic liquid in step S2 is 1:(0.01-0.32).

7. The method for preparing a high-performance Cs₂HfCl₆ double perovskite according to claim 2, characterized in that, The drying process in step S4 is carried out at a temperature of 60-80℃ for 2-5 hours.

8. A perovskite phosphor, characterized in that, The perovskite phosphor comprises the high-performance Cs2HfCl6 double perovskite as described in claim 1.

9. The application of the perovskite phosphor as described in claim 8 in the fields of lighting or anti-counterfeiting technology.

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