Tin-doped ternary metal halide and preparation method and application thereof
By doping Sn elements in K2ZnBr4, the tin-doped ternary metal halide K2ZnBr4:Sn is prepared by mechanochemical methods, which solves the problem of low fluorescence efficiency of K2ZnBr4, achieving high fluorescence efficiency and bright orange light emission, and has good photoelectric application prospects.
Patent Information
- Application Number
- CN202510598355.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-09
- Publication Date
- 2025-08-22
AI Technical Summary
The existing K2ZnBr4 has low fluorescence efficiency, which limits its practical application in the fields of photovoltaic cells and LEDs.
By doping Sn elements in K2ZnBr4 and ball milling and drying by mechanochemical methods, the tin-doped ternary metal halide K2ZnBr4:Sn was prepared.
It improves the fluorescence efficiency of K2ZnBr4, achieves high fluorescence quantum efficiency, and has bright orange light emission, suitable for photoelectric materials and fluorescent materials.
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Figure CN120519152A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of perovskite crystal materials, and in particular relates to a tin-doped ternary metal halide and a preparation method and application thereof. Background Art
[0002] With the increasing greenhouse effect, extreme weather, smog, and PM2.5, which are seriously affecting human survival and health, it is crucial to vigorously develop clean energy. Common clean energy sources include solar energy, wind energy, tidal energy, etc.
[0003] Metal halide perovskite materials have been widely used in many fields, such as solar photovoltaic cells and light-emitting diodes, due to their narrow band gap, high carrier mobility and long carrier diffusion length. As of 2023, the certified efficiency of inverted structure perovskite solar cells has reached 26.1%, and the highest certified photoelectric conversion efficiency of stacked perovskite solar cells is 29.1%, which exceeds that of traditional Si-based solar cells. However, lead-based iodide perovskites (MAPbI3, FAPbI3) have poor water and air stability, and the yellow phase γ structure caused by phase transition shows a large band gap, which seriously reduces its ability to utilize solar energy. At the same time, mixed halide perovskites (MA X FA 1-X )PbBr 3-x I3 is prone to phase separation and exhibits poor energy conversion efficiency.
[0004] Zn-based perovskites have also been extensively studied in recent years. ZnX2 (X = Cl, Br, I) compounds exhibit stable structures, single valences, and excellent stability. In 1979, researchers first obtained the K-based halide perovskite K2ZnBr4 and studied its structure. However, recent studies have shown that K2ZnBr4 has a large band gap, making it unsuitable for photovoltaic cells. Furthermore, its fluorescence is weak and nearly invisible to the naked eye, significantly limiting its practical applications in areas such as LEDs. Therefore, the preparation of K2ZnBr4 with high fluorescence efficiency through methods such as doping is of great significance for practical applications. Summary of the Invention
[0005] The purpose of the present invention is to overcome the above technical deficiencies, provide a tin-doped ternary metal halide and its preparation method and application, and solve the technical problem of low fluorescence efficiency of K2ZnBr4 in the prior art.
[0006] In order to achieve the above technical objectives, the technical solution provided by the present invention is: In a first aspect, the present invention provides a tin-doped ternary metal halide, which is a K2ZnBr4 perovskite fluorescent material doped with Sn element, and the doping amount of Sn element is less than 25% of the molar amount of Zn element.
[0007] In a second aspect, the present invention provides a method for preparing a tin-doped ternary metal halide, comprising the following steps: mixing KBr microcrystalline powder, ZnBr2 microcrystalline powder, SnBr2 microcrystalline powder and acid solution under a protective atmosphere, and performing a first ball milling to obtain a first powder; adding Sn powder to the first powder, and performing a second ball milling to obtain a second powder; and drying the second powder to obtain a tin-doped ternary metal halide.
[0008] In a third aspect, the present invention provides an application of a tin-doped ternary metal halide in the preparation of a photoelectric material or a fluorescent material.
[0009] Compared with the prior art, the present invention has the following beneficial effects: The present invention successfully synthesizes Sn(II)-doped K2ZnBr4 by mixing KBr microcrystalline powder, ZnBr2 microcrystalline powder, SnBr2 microcrystalline powder and hypophosphorous acid and then adding tin powder for ball milling to avoid the adverse effects of SnBr2 being oxidized to SnBr4 due to its unstable chemical properties. The Sn(II)-doped K2ZnBr4 has bright orange light emission and high fluorescence quantum efficiency, and has good application prospects in the optoelectronic field. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Figure 1 is the UV absorption-visible spectrum of K2ZnBr4: Sn prepared in Example 1; Figure 2 is the fluorescence emission spectrum of K2ZnBr4:Sn prepared in Example 1; Figure 3 is the XRD spectrum of K2ZnBr4:Sn prepared in Example 1; Figure 4 This is the fluorescence excitation spectrum of K2ZnBr4: Sn prepared in Example 1. DETAILED DESCRIPTION
[0011] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.
[0012] The present invention provides a tin-doped ternary metal halide and its preparation method and application, through a simple mechanochemical method, and with Sn 2+As a dopant, a fully inorganic, stable, and efficient orange-red light non-lead metal halide is prepared. The non-lead metal halide is a pure phase K-based metal halide K2ZnBr4:Sn. 2+ When introduced into K2ZnBr4, a high fluorescence yield of 51% was achieved.
[0013] In a first aspect, the present invention provides a tin-doped ternary metal halide, which is a K2ZnBr4 perovskite fluorescent material doped with Sn element, and the doping amount of Sn element is less than 25% of the molar amount of Zn element.
[0014] In a second aspect, the present invention provides a method for preparing a tin-doped ternary metal halide, comprising the following steps: Under a protective atmosphere, KBr microcrystalline powder, ZnBr2 microcrystalline powder, SnBr2 microcrystalline powder and acid solution are mixed and ball-milled for the first time to obtain a first powder; Adding Sn powder to the first powder and performing a second ball milling to obtain a second powder; The second powder is dried to obtain tin-doped ternary metal halide.
[0015] Preferably, the preparation steps of KBr microcrystalline powder, ZnBr2 microcrystalline powder and SnBr2 microcrystalline powder specifically include: mixing bromide salts (KBr, ZnBr2 and SnBr2) with organic solvents respectively, heating and dissolving to obtain bromide salt solutions; transferring the bromide salt solutions to a dust-free dry environment, and diffusing acetone vapor into the bromide salt solutions respectively to obtain KBr single crystals, ZnBr2 single crystals and SnBr2 single crystals; and grinding the single crystals respectively to obtain KBr microcrystalline powder, ZnBr2 microcrystalline powder and SnBr2 microcrystalline powder.
[0016] More preferably, the organic solvent is a mixture of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a volume ratio of (4-6):1; the ratio of KBr, ZnBr2, and SnBr2 to the organic solvent is (0.1-0.5) mmol:1 mL. Excessive amounts of N,N-dimethylformamide (e.g., exceeding 6:1) in the organic solvent may result in incomplete dissolution of the bromide salt after heating, while too little N,N-dimethylformamide may make it difficult to precipitate single crystals.
[0017] More preferably, the conditions for heating and dissolving include: a heating temperature of 60 to 100° C. and a heating time of 10 to 60 minutes. It is understood that heating under these conditions is sufficient to ensure that a bromide salt solution can be obtained by dissolving.
[0018] Further preferably, the acetone vapor diffuses into the bromide salt solution for 7 days to obtain a single crystal. Because acetone is volatile, the present invention places the bromide salt solution in a first glass bottle and the acetone in a second glass bottle, both of which are placed in the same space, allowing the vapor generated by the acetone vapor to diffuse into the bromide salt solution. To accelerate the diffusion rate, the first glass bottle is a small bottle and the second glass bottle is a large bottle. The first glass bottle is placed in the second glass bottle, and the bottle mouth of the second glass bottle is sealed and then left to stand.
[0019] Further preferably, the volume ratio of the organic solvent to acetone is 10:(15-20); too much acetone will cause the bromide salt solution to crystallize too quickly, resulting in poor quality crystals; too little acetone will cause incomplete precipitation of the bromide salt or increase the precipitation time, thereby increasing production costs and lengthening production time.
[0020] Further preferably, the grinding conditions include: grinding the KBr, SnBr2 and ZnBr2 single crystals into micron-sized particles under nitrogen protection.
[0021] It is understood that necessary drying may be performed after grinding, for example, by baking the ground micron-sized particles with an infrared lamp to remove any adsorbed water vapor.
[0022] Preferably, the molar ratio of KBr microcrystalline powder, ZnBr2 microcrystalline powder, SnBr2 microcrystalline powder and Sn powder is 2:0.9:0.1:(0.05-0.2); most preferably, it is 2:0.9:0.1:0.1.
[0023] Preferably, the acid solution is a 50 wt% hypophosphorous acid aqueous solution; the ratio between the hypophosphorous acid aqueous solution and SnBr2 is (30-40) μL:1 mmol.
[0024] Preferably, the conditions for the first ball milling include: ball milling at a speed of 35 to 80 Hz for 4 to 6 hours under argon, wherein the speed of the ball mill is most preferably 40 Hz.
[0025] Preferably, the conditions for the second ball milling include: ball milling at a speed of 35 to 80 Hz for 0.5 to 1.5 hours under argon gas.
[0026] Preferably, the drying is carried out under vacuum conditions at 55-110°C. The most preferred drying temperature is 55°C.
[0027] In a third aspect, the present invention provides an application of a tin-doped ternary metal halide in the preparation of a photoelectric material or a fluorescent material.
[0028] The present invention improves the fluorescence efficiency of K2ZnBr4 by doping with tin ions, thereby obtaining a high-purity, tin-doped ternary metal halide K2ZnBr4:Sn with enhanced fluorescence efficiency. The sample exhibits bright orange emission when excited by a 302 nm ultraviolet lamp.
[0029] The present invention is further described in detail below through specific examples.
[0030] Example 1: (1) First, in a nitrogen-filled glove box, 1 mmol of KBr, SnBr2, and ZnBr2 were weighed into glass bottles, and 5 mL of a mixture of DMF and DMSO (the volume ratio of DMF and DMSO was 4:1) was added to each of them. After slowly heating to dissolve them, they were quickly transferred to a dust-free dry environment. Then, acetone vapor was slowly diffused into the DMF and DMSO mixture. Single crystals were obtained after one week.
[0031] (2) The obtained KBr, SnBr2 and ZnBr2 single crystals were fully ground into micron-sized particles in a nitrogen-filled glove box, and then dried with an infrared lamp to remove possible adsorbed water vapor to obtain KBr microcrystalline powder, SnBr2 microcrystalline powder and ZnBr2 microcrystalline powder.
[0032] (3) In a glove box, 2 mmol of KBr, 0.9 mmol of ZnBr2, and 0.1 mmol of SnBr2 microcrystalline powders were weighed into a grinding jar. Subsequently, 3.5 μL of hypophosphorous acid aqueous solution (50 wt%) was added to the system, and the system was sealed under argon. The system was ball-milled in a planetary ball mill at a speed of 40 Hz for 5 h to obtain a white powder. Then, 0.1 mmol of Sn powder was added to the system, and mechanical grinding was continued for 1 h. The system was dried under vacuum at 55 °C to obtain a tin-doped ternary metal halide K2ZnBr4:Sn with high purity and enhanced fluorescence efficiency.
[0033] The product samples were subjected to solid fluorescence excitation and fluorescence emission tests, and the results were as follows: Figures 1-4 shown.
[0034] The UV absorption visible spectrum of K2ZnBr4:Sn is as follows Figure 1 As shown, it can absorb light before 400 nm.
[0035] The fluorescence emission spectrum of K2ZnBr4:Sn is shown in Figure 2 As shown, it is red emission.
[0036] The powder XRD pattern of K2ZnBr4:Sn is as follows Figure 3As shown, the powder X-ray spectrum can prove that the pure phase K-based metal halide K2ZnBr4:Sn is prepared in the present invention.
[0037] The fluorescence excitation spectrum of K2ZnBr4:Sn is as follows Figure 4 As shown, it exhibits bright orange emission under 302 nm UV excitation.
[0038] Example 2 Compared with Example 1, the amounts of Sn powder were adjusted to 0.05 mmol and 0.2 mmol, respectively. Other steps and conditions were the same as those in Example 1.
[0039] The test found that the fluorescence quantum efficiency of the tin-doped ternary metal halide K2ZnBr4:Sn obtained with different Sn powder dosages was different, as shown in Table 1 below.
[0040] Table 1 Fluorescence quantum efficiency of K2ZnBr4:Sn with different Sn powder dosages
[0041] As shown in Table 1, when the amount of Sn powder in Example 1 was changed from 0.1 mmol to 0.05 mmol and 0.2 mmol, the fluorescence quantum efficiency of the products obtained under different amounts of Sn powder treatment was measured to be 35% and 45%, respectively. This is mainly because the chemical properties of the raw material SnBr2 used are very unstable and it is easily oxidized to SnBr4 in an oxygen and water environment. Therefore, hypophosphorous acid and Sn powder need to be added to react simultaneously to react SnBr4 to SnBr2. In which, too little Sn powder will result in incomplete reduction of SnBr4, and too much Sn powder will introduce additional impurities. Therefore, the amount of Sn powder added is preferably 0.05-0.2 mmol relative to 0.1 mmol of SnBr2, and most preferably 0.1 mmol.
[0042] Example 3 Compared with Example 1, the frequencies of the ball mill were adjusted to 20 Hz, 35 Hz, 50 Hz and 80 Hz respectively, and the other steps and conditions were the same as those in Example 1.
[0043] The results showed that the frequency of the ball mill is particularly important. A ball mill frequency that is too low will not allow the raw materials to react fully, while a ball mill frequency that is too high will increase the reaction temperature of the system, thereby generating by-products. Therefore, the mill frequency must be appropriate. After changing the ball mill frequency in Example 1 from 40 Hz to 20 Hz, 35 Hz, 50 Hz, and 80 Hz, it was found that K2ZnBr4:Sn without impurity phases was obtained at a ball milling frequency of 40 Hz. Impurity phases were generated at lower frequencies, making 40 Hz the most appropriate milling frequency.
[0044] Example 4: Compared with Example 1, the vacuum drying temperatures were adjusted to 60°C, 80°C, and 110°C, respectively. Other steps and conditions were the same as those in Example 1.
[0045] The test found that the fluorescence quantum efficiency of the tin-doped ternary metal halide K2ZnBr4:Sn obtained at different vacuum drying temperatures was different, as shown in Table 2 below.
[0046] Table 2 Fluorescence quantum efficiency of K2ZnBr4:Sn obtained at different vacuum drying temperatures
[0047] The results showed that the vacuum drying temperature should not be too high, as it will cause the synthesized K2ZnBr4:Sn to change phase, resulting in a significant decrease in fluorescence efficiency. Therefore, the drying temperature is selected to be 55-110°C, with 55°C being the most preferred.
[0048] Comparative Example 1 Mix 2 mmol KBr and 1 mmol ZnBr2, seal under argon, ball mill at 40 Hz for 5 h, and dry under vacuum at 55 °C to obtain K2ZnBr4.
[0049] The results showed that under the excitation of ultraviolet light with an excitation wavelength of 302 nm, the luminescence efficiency of K2ZnBr4 was extremely low and almost invisible to the naked eye.
[0050] It can be seen that when not doped with Sn, K2ZnBr4 has poor luminescence performance; similarly, due to Sn 2+ Unstable. When the amount of doped Sn is excessive, the resulting product system will be unstable.
[0051] Comparative Example 2 Compared with Example 1, the only difference is that the step of preparing microcrystalline powder is removed, and KBr, SnBr2, Sn powder and ZnBr2 are directly used as raw materials to perform step (3). The specific conditions are the same as those of step (3) in Example 1.
[0052] The results showed that when commercial KBr, SnBr2, Sn powder and ZnBr2 powder were directly ground, the synthesized K2ZnBr4:Sn was very unstable because the powders contained a large number of defect sites, and water and oxygen molecules easily occupied the defect sites; at the same time, the synthesized K2ZnBr4:Sn also exhibited a lower fluorescence quantum efficiency.
[0053] In summary, the present invention proposes for the first time a method for improving the fluorescence efficiency of K2ZnBr4 by doping with tin ions, which provides a good prospect for the application of K2ZnBr4 in optoelectronics. The P-XRD spectrum shows that the synthesized K2ZnBr4:Sn has a diffraction pattern similar to that of the standard card. Figure 1 This demonstrates that this method successfully achieves a high-dose synthesis of K2ZnBr4: Sn, demonstrating its environmentally friendly, high-yield, and solvent-free advantages. Under ultraviolet excitation at a wavelength of 302 nm, K2ZnBr4 exhibits extremely low luminescence efficiency. However, the introduction of the Sn(II) dopant in this invention enables K2ZnBr4 to exhibit bright orange emission, demonstrating promising applications in optoelectronics. This invention demonstrates that K2ZnBr4: Sn may be a promising orange-red luminescent material with advantages such as non-toxicity and high quantum efficiency.
[0054] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.
Claims
1. A tin-doped ternary metal halide, characterized in that: The tin-doped ternary metal halide is a K2ZnBr4 perovskite fluorescent material doped with Sn element, and the doping amount of Sn element is less than 25% of the molar amount of Zn element.
2. The method for preparing tin-doped ternary metal halide according to claim 1, wherein: The following steps are involved: Under a protective atmosphere, KBr microcrystalline powder, ZnBr2 microcrystalline powder, SnBr2 microcrystalline powder and acid solution are mixed and ball-milled for the first time to obtain a first powder; adding Sn powder to the first powder and performing a second ball milling to obtain a second powder; The second powder is dried to obtain tin-doped ternary metal halide.
3. The method for preparing tin-doped ternary metal halide according to claim 2, characterized in that: The steps for preparing the KBr microcrystalline powder, the ZnBr2 microcrystalline powder and the SnBr2 microcrystalline powder specifically include: The bromide salts are mixed with organic solvents respectively, and heated to dissolve to obtain bromide salt solutions; the bromide salts are KBr, ZnBr2 and SnBr2; diffusing acetone vapor into the bromide salt solution to obtain KBr single crystal, ZnBr2 single crystal and SnBr2 single crystal; The KBr single crystal, ZnBr2 single crystal and SnBr2 single crystal are ground respectively to obtain KBr microcrystalline powder, ZnBr2 microcrystalline powder and SnBr2 microcrystalline powder.
4. The method for preparing tin-doped ternary metal halide according to claim 3, characterized in that: The organic solvent is a mixture of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of (4-6):1; and / or, The ratio between the bromide salt and the organic solvent is (0.1-0.5) mmol:1 mL; and / or, The volume ratio of the organic solvent to the acetone is 10:(15-20).
5. The method for preparing tin-doped ternary metal halide according to claim 2, characterized in that: The molar ratio of the KBr microcrystalline powder, the ZnBr2 microcrystalline powder, the SnBr2 microcrystalline powder and the Sn powder is 2:0.9:0.1:(0.05-0.2).
6. The method for preparing tin-doped ternary metal halide according to claim 2, characterized in that: The acid solution is a 50 wt% hypophosphorous acid aqueous solution; the ratio between the hypophosphorous acid aqueous solution and SnBr2 is (30-40) μL:1 mmol.
7. The method for preparing tin-doped ternary metal halide according to claim 2, characterized in that: The conditions for the first ball milling include: ball milling at a speed of 35 to 80 Hz for 4 to 6 hours under argon gas.
8. The method for preparing tin-doped ternary metal halide according to claim 2, characterized in that: The conditions for the second ball milling include: ball milling at a rotation speed of 35 to 80 Hz for 0.5 to 1.5 hours under argon gas.
9. The method for preparing tin-doped ternary metal halide according to claim 2, characterized in that: The drying is carried out at 55-110° C. under vacuum conditions.
10. Use of the tin-doped ternary metal halide according to claim 1 or the tin-doped ternary metal halide prepared by the preparation method according to any one of claims 2 to 9 in the preparation of optoelectronic materials or fluorescent materials.