Cs3Cu2I5 single crystal growth method

Abstract

The invention belongs to the technical field of crystal growth, and particularly relates to a Cs3Cu2I5 single crystal growth method. The method specifically comprises the following steps: taking cesium iodide and cuprous iodide as precursors, carrying out stirring reaction on the precursors and lewis acid in a polar aprotic solvent, hydrolyzing the lewis acid to generate an acid environment, inhibiting Cu < + > oxidation, and meanwhile, forming uniformly dispersed colloidal particles to obtain a precursor solution; and adding an anti-solvent into the precursor solution to enable the precursor solution to reach a supersaturated state, filtering, and carrying out single crystal growth by adopting an inverse temperature crystallization method. Lewis acid is added into the precursor solution, oxidation of Cu < + > is inhibited by utilizing a weak acid environment generated by hydrolysis of the Lewis acid, and the colloid stability of the precursor is improved, so that growth of the high-quality large-size Cs3Cu2I5 single crystal is promoted. The method is simple and convenient to operate and easy to control, can effectively improve the scintillation luminescence performance of the single crystal, and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of crystal growth, and particularly relates to a Cs3Cu2I5 single crystal growth method. BACKGROUND

[0002] As a new type of copper halide perovskite material, Cs3Cu2I5 has excellent optical and scintillation properties, and has broad application prospects in the fields of lighting, display, radiation detection, etc. In order to realize low-cost and mass production, a solution method is usually used to grow Cs3Cu2I5 single crystal. However, in the solution growth process, Cu + is easily oxidized to Cu 2+ , resulting in a decrease in crystal quality and a decrease in luminescence and scintillation properties. At the same time, the colloidal stability of the precursor solution is poor, and it is difficult to realize stable growth of high-quality single crystals. SUMMARY

[0003] In order to solve the above technical problems, the application provides a Cs3Cu2I5 single crystal growth method. By adding a Lewis acid additive to the precursor solution, the weak acidic environment generated by the hydrolysis of the Lewis acid is used to inhibit the oxidation of Cu + , and the charge distribution on the surface of the colloidal particles is improved, the colloidal stability of the precursor solution is improved, and the growth of high-quality Cs3Cu2I5 single crystals is promoted.

[0004] To achieve the above purpose, the technical scheme adopted by the application is: A Cs3Cu2I5 single crystal growth method, comprising the following steps: CsI and Cul are used as precursors, the precursors and the Lewis acid are stirred uniformly in a polar aprotic solvent, the acidic environment generated by the hydrolysis of the Lewis acid inhibits the oxidation of Cu + , and at the same time, uniformly dispersed colloidal particles are formed to obtain a precursor solution; under stirring, a reverse solvent is added to the precursor solution to make the precursor solution reach a supersaturated state, and after filtration, a single crystal is grown by inverse temperature crystallization method to obtain a Cs3Cu2I5 single crystal; the added molar amount of the Lewis acid accounts for 1% to 5% of the theoretical generated molar amount of Cs3Cu2I5.

[0005] The application uses CsI and Cul as precursors, and uses a Lewis acid as an additive. The precursors and the Lewis acid are added to a polar aprotic solvent and stirred to react. The Lewis acid ionizes H + under the action of trace water, which can consume part of OH - in the system, thereby inhibiting the oxidation of Cu +The oxidation and the generated acidic environment can also break the aggregation structure of the oversized non-solubilized colloidal particles by adjusting the surface charge state of the colloidal particles, inhibit the colloidal aggregation, so that the stable precursor solution is obtained, then the anti-solvent is added to the precursor solution under stirring to make the precursor solution reach a supersaturated state, after filtration, the single crystal growth is carried out by using the inverse temperature crystallization method, so that the Cs3Cu2I5 single crystal is obtained.

[0006] Further, the Lewis acid is selected from any one of yttrium chloride (YCl3), cerium chloride (CeCl3) and lutetium chloride (LuCl3). Through experimental exploration, the above three kinds of Lewis acids are preferred, and other Lewis acids are easy to introduce impurities or have adverse reactions with the system components, thereby affecting the performance of the single crystal.

[0007] Further, the molar ratio of cesium iodide and cuprous iodide is 1.50-1.63:1. Within the ratio range, the Cs3Cu2I5 single crystal with excellent optical and scintillation performance can be obtained.

[0008] Further, the polar aprotic solvent is a mixed solvent composed of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), and the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide is 12:3.

[0009] Further, the inverse temperature crystallization method is to raise the temperature from 60℃ to 80℃ within 80h-120h for single crystal growth.

[0010] Further, the filtration is to filter the precursor solution reaching the supersaturated state at least twice by using a syringe equipped with a 0.45μm filter head.

[0011] Further, before the single crystal growth by using the inverse temperature crystallization method, the method further comprises: adding a Cs3Cu2I5 seed crystal.

[0012] Further, the anti-solvent is ethanol.

[0013] The Cs3Cu2I5 single crystal is prepared by using the above method.

[0014] Compared with the prior art, the present application has the following beneficial effects: The present application uses cesium iodide (CsI) and cuprous iodide (CuI) as precursors, uses Lewis acid as an additive, and stirs the reaction in a polar aprotic solvent. +Oxidation, while significantly increasing the zeta potential of the colloidal surface in the precursor solution, destroys the oversize non-solvent colloidal precursor in the solution, inhibits the agglomeration of colloids, so as to obtain a stable precursor solution; then the anti-solvent is added to the precursor solution to reach the supersaturation state, and after filtration, the single crystal growth is carried out by the inverse temperature crystallization method. The Cs3Cu2I5 single crystal grown by the method has a photoluminescence quantum yield of not less than 90% and a light yield of not less than 600 pe / MeV. After the Cs3Cu2I5 single crystal is placed in the air environment for 60 days, the photoluminescence integral intensity is still not less than 70% of the initial intensity. The Cs3Cu2I5 single crystal provided by the application has important application value in the field of radiation detection. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0016] Figure 1 The mechanism diagram of the Lewis acid in the present application.

[0017] Figure 2 The Cs3Cu2I5 single crystal obtained in Example 1 of the present application is shown in the figure, wherein (a) is the picture under sunlight, and (b) is the picture under 310 nm light.

[0018] Figure 3 The photoluminescence quantum yield (PLQY) of the Cs3Cu2I5 single crystal obtained in Example 1 of the present application is shown in the figure.

[0019] Figure 4 The Cs3Cu2I5 single crystal obtained in Example 2 of the present application is shown in the figure, wherein (a) is the picture under sunlight, and (b) is the picture under 310 nm light.

[0020] Figure 5 The Cs3Cu2I5 single crystal obtained in Example 3 of the present application is shown in the figure, wherein (a) is the picture under sunlight, and (b) is the picture under 310 nm light.

[0021] Figure 6 The gamma-ray pulse height spectrum of the Cs3Cu2I5 single crystal obtained in Example 1, Examples 4-7, Comparative Example 1 and the BGO scintillator is shown in the figure, wherein (a) is the pulse height spectrum in the channel range of 0-500, and (b) is the pulse height spectrum of the Cs3Cu2I5 single crystal in the channel range of 200-450.

[0022] Figure 7 The images shown are of the Cs3Cu2I5 single crystals obtained in Example 1 and Comparative Example 1. (a) is a picture of the Cs3Cu2I5 single crystal obtained in Example 1 under sunlight, (b) is a picture of the Cs3Cu2I5 single crystal obtained in Example 1 under 310nm light, (c) is a picture of the Cs3Cu2I5 single crystal obtained in Comparative Example 1 under sunlight, and (d) is a picture of the Cs3Cu2I5 single crystal obtained in Comparative Example 1 under 310nm light.

[0023] Figure 8 The results of colloidal stability tests in the precursor solutions of Example 1 and Comparative Example 1 are shown, where (a) is a zeta potential diagram and (b) is a particle size distribution diagram. Detailed Implementation

[0024] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods, and the materials and reagents used in the following embodiments are commercially available unless otherwise specified.

[0025] The Cs3Cu2I5 seed crystals required in the following examples were all obtained through the following methods: A stoichiometric mixture of 7.79 g CsI and 3.808 g CuI was dissolved in 16 mL DMF and 4 mL DMSO. After magnetic stirring for 12 hours, anhydrous ethanol was added dropwise until the solution became turbid. The solution was then filtered through a 0.45 μm PTFE membrane to obtain a transparent yellow precursor. The solution was transferred to a 50 mL three-necked flask (A) and connected to another flask (B) containing 50 mL of ethanol via a gas tube. Flask A was maintained at 60 °C and flask B at 50 °C for 48 hours, allowing ethanol vapor to diffuse from flask B into flask A for seed crystal growth. After the reaction was complete, the seed crystals were removed, rinsed with ethanol, and dried at 60 °C for 2 hours to obtain Cs3Cu2I5 seed crystals.

[0026] Example 1 This embodiment provides a method for preparing Cs3Cu2I5 single crystal based on YCl3 addition, the steps of which are as follows: Weigh out 4.5 mmol of CsI and 3 mmol of CuI precursors according to stoichiometric ratio and dissolve them in a mixed solvent of DMF / DMSO (24 mL and 6 mL of DMF and DMSO, respectively). Then, add 2 mol% (based on the total theoretical molar amount of Cs3Cu2I5, 1.5 mmol) of YCl3 to the above mixed solution and stir until homogeneous to obtain the precursor solution. While stirring, add ethanol dropwise until the precursor solution reaches a supersaturated state (turbidity appears). Then, transfer it to a 50 mL standard syringe and attach a 0.45 μm filter to the tip of the syringe to filter the solution. Repeat the operation twice and transfer the filtered solution to a screw-top glass bottle. Place the Cs3Cu2I5 seed crystal at the bottom of the glass bottle and place it in a preheated oven at 60 °C. Use the reverse temperature crystallization method to raise the temperature from 60 °C to 80 °C within 100 h (heating rate of 0.2 °C per hour) to obtain Cs3Cu2I5 single crystals.

[0027] Images of the actual Cs3Cu2I5 single crystal obtained in this embodiment under sunlight and 310nm light are shown below. Figure 2 As shown, (a) is an image under sunlight, and (b) is an image under 310nm light.

[0028] Figure 3 The graph shows the photoluminescence quantum yield (PLQY) of the Cs3Cu2I5 single crystal obtained in this embodiment, indicating a PLQY of 94.49%. "No sample" represents the spectrum without a Cs3Cu2I5 single crystal sample. The sharp peak in the graph represents the spectrum emitted by the 310 nm excitation source. After placing the Cs3Cu2I5 single crystal sample, an emission peak with a peak value of 450 nm appeared in the range of 375 nm to 550 nm. The intensity of the spectral peak from the 310 nm excitation source decreased, indicating that the Cs3Cu2I5 single crystal absorbed the excitation light.

[0029] Example 2 This embodiment provides a method for preparing Cs3Cu2I5 single crystals based on CeCl3 addition, the steps of which are as follows: Weigh out 4.5 mmol of CsI and 3 mmol of CuI precursors according to stoichiometric ratio and dissolve them in a mixed solvent of DMF and DMSO (24 mL and 6 mL volumes, respectively). Then, add 2 mol% (based on the total theoretical molar amount of Cs3Cu2I5, 1.5 mmol) of CeCl3 to the above mixed solution and stir until homogeneous to obtain the precursor solution. While stirring, add ethanol dropwise until the precursor solution reaches a supersaturated state (turbidity appears). Then, transfer the solution to a 50 mL standard syringe and attach a 0.45 μm filter to the tip of the syringe to filter the solution. Repeat the operation twice and transfer the filtered solution to a screw-top glass bottle. Place the Cs3Cu2I5 seed crystal at the bottom of the glass bottle and place it in a preheated oven at 60 °C. Use the reverse temperature crystallization method to raise the temperature from 60 °C to 80 °C within 100 h to obtain Cs3Cu2I5 single crystals.

[0030] Images of the actual Cs3Cu2I5 single crystal obtained in this embodiment under sunlight and 310nm light are shown below. Figure 4 As shown, (a) is an image under sunlight, and (b) is an image under 310nm light.

[0031] Example 3 This embodiment provides a method for preparing Cs3Cu2I5 single crystal based on LuCl3 addition, the steps of which are as follows: Weigh out 4.5 mmol of CsI and 3 mmol of CuI precursors according to stoichiometric ratio and dissolve them in a mixed solvent of DMF and DMSO (24 mL and 6 mL volumes, respectively). Then, add 2 mol% (based on the total theoretical molar amount of Cs3Cu2I5, 1.5 mmol) of LuCl3 to the above mixed solution and stir until homogeneous to obtain the precursor solution. While stirring, add ethanol dropwise until the precursor solution reaches a supersaturated state (turbidity appears). Then, transfer the solution to a 50 mL standard syringe and attach a 0.45 μm filter to the tip of the syringe to filter the solution. Repeat the operation twice and transfer the filtered solution to a screw-top glass bottle. Place the Cs3Cu2I5 seed crystal at the bottom of the glass bottle and place it in a preheated oven at 60 °C. Use the reverse temperature crystallization method to raise the temperature from 60 °C to 80 °C within 100 h to obtain Cs3Cu2I5 single crystals.

[0032] Images of the actual Cs3Cu2I5 single crystal obtained in this embodiment under sunlight and 310nm light are shown below. Figure 5 As shown, (a) is an image under sunlight, and (b) is an image under 310nm light.

[0033] Figure 2 , Figure 4 ,Figure 5 The images show Cs3Cu2I5 single crystals with 2 mol% YCl3, CeCl3, and LuCl3 added, respectively. After adding YCl3, the single crystal surface showed virtually no cracks; after adding CeCl3 and LuCl3, a small number of cracks appeared on the single crystal surface. Under the same dosage conditions, YCl3 exhibits the best acidity after hydrolysis compared to other rare earth chlorides, and also produces the highest quality single crystals.

[0034] Example 4 This embodiment provides a method for preparing Cs3Cu2I5 single crystal based on YCl3 addition, the steps of which are as follows: Weigh out 4.5 mmol of CsI and 3 mmol of CuI precursors according to stoichiometric ratio and dissolve them in a mixed solvent of DMF / DMSO (24 mL and 6 mL, respectively). Then, add 1 mol% (based on the total theoretical molar amount of Cs3Cu2I5, 1.5 mmol) of YCl3 to the above mixed solution and stir until homogeneous to obtain the precursor solution. While stirring, add ethanol dropwise until the precursor solution reaches a supersaturated state (turbidity appears). Then, transfer the solution to a 50 mL standard syringe and attach a 0.45 μm filter to the tip of the syringe to filter the solution. Repeat the operation twice and transfer the filtered solution to a screw-top glass bottle. Place the Cs3Cu2I5 seed crystal at the bottom of the glass bottle and place it in a preheated oven at 60 °C. Use the reverse temperature crystallization method to raise the temperature from 60 °C to 80 °C within 100 h to obtain Cs3Cu2I5 single crystals.

[0035] Example 5 This embodiment provides a method for preparing Cs3Cu2I5 single crystal based on YCl3 addition, the steps of which are as follows: Weigh out 4.5 mmol of CsI and 3 mmol of CuI precursors according to stoichiometric ratio and dissolve them in a mixed solvent of DMF / DMSO (24 mL and 6 mL, respectively). Then, add 3 mol% (based on the total theoretical molar amount of Cs3Cu2I5, 1.5 mmol) of YCl3 to the above mixed solution and stir until homogeneous to obtain the precursor solution. While stirring, add ethanol dropwise until the precursor solution reaches a supersaturated state (turbidity appears). Then, transfer the solution to a 50 mL standard syringe and attach a 0.45 μm filter to the tip of the syringe to filter the solution. Repeat the operation twice and transfer the filtered solution to a screw-top glass bottle. Place the Cs3Cu2I5 seed crystal at the bottom of the glass bottle and place it in a preheated oven at 60 °C. Use the reverse temperature crystallization method to raise the temperature from 60 °C to 80 °C within 100 h to obtain Cs3Cu2I5 single crystals.

[0036] Example 6 This embodiment provides a method for preparing Cs3Cu2I5 single crystal based on YCl3 addition, the steps of which are as follows: Weigh out 4.5 mmol of CsI and 3 mmol of CuI precursors according to stoichiometric ratio and dissolve them in a mixed solvent of DMF / DMSO (24 mL and 6 mL of DMF and DMSO, respectively). Then, add 4 mol% (based on the total theoretical molar amount of Cs3Cu2I5, 1.5 mmol) of YCl3 to the above mixed solution and stir until homogeneous to obtain the precursor solution. While stirring, add ethanol dropwise until the precursor solution reaches a supersaturated state (turbidity appears). Then, transfer the solution to a 50 mL standard syringe and attach a 0.45 μm filter to the tip of the syringe to filter the solution. Repeat the operation twice and transfer the filtered solution to a screw-top glass bottle. Place the Cs3Cu2I5 seed crystal at the bottom of the glass bottle and place it in a preheated oven at 60 °C. Use the reverse temperature crystallization method to raise the temperature from 60 °C to 80 °C within 100 h to obtain Cs3Cu2I5 single crystals.

[0037] Example 7 This embodiment provides a method for preparing Cs3Cu2I5 single crystal based on YCl3 addition, the steps of which are as follows: Weigh out 4.5 mmol of CsI and 3 mmol of CuI precursors according to stoichiometric ratio and dissolve them in a mixed solvent of DMF / DMSO (24 mL and 6 mL, respectively). Then, add 5 mol% (based on the total theoretical molar amount of Cs3Cu2I5, 1.5 mmol) of YCl3 to the above mixed solution and stir until homogeneous to obtain the precursor solution. While stirring, add ethanol dropwise until the precursor solution reaches a supersaturated state (turbidity appears). Then, transfer the solution to a 50 mL standard syringe and attach a 0.45 μm filter to the tip of the syringe to filter the solution. Repeat the operation twice and transfer the filtered solution to a screw-top glass bottle. Place the Cs3Cu2I5 seed crystal at the bottom of the glass bottle and place it in a preheated oven at 60 °C. Use the reverse temperature crystallization method to raise the temperature from 60 °C to 80 °C within 100 h to obtain Cs3Cu2I5 single crystals.

[0038] Example 8 A method for preparing Cs3Cu2I5 single crystals, prepared according to the method described in Example 1, except that the temperature is increased from 60℃ to 80℃ within 80 hours using a reverse temperature crystallization method.

[0039] The PLQY of the Cs3Cu2I5 single crystal obtained in this embodiment is 90.12%.

[0040] Example 9 A method for preparing Cs3Cu2I5 single crystals, prepared according to the method described in Example 1, except that the temperature is increased from 60°C to 80°C within 120 hours using a reverse temperature crystallization method.

[0041] The PLQY of the Cs3Cu2I5 single crystal obtained in this embodiment is 92.86%.

[0042] Example 10 A method for preparing Cs3Cu2I5 single crystals, prepared according to the method described in Example 1, except that the molar amounts of cesium iodide and cuprous iodide are 4.65 mmol and 2.85 mmol, respectively.

[0043] The PLQY of the Cs3Cu2I5 single crystal obtained in this embodiment is 87.7%.

[0044] Example 11 A method for preparing Cs3Cu2I5 single crystals, prepared according to the method described in Example 1, except that the molar amounts of cesium iodide and cuprous iodide are 4.585 mmol and 2.925 mmol, respectively.

[0045] The PLQY of the Cs3Cu2I5 single crystal obtained in this embodiment is 89.34%.

[0046] The single crystals prepared in the embodiments of the present invention all have a particle size of 8 mm to 13 mm.

[0047] Comparative Example 1 A method for preparing Cs3Cu2I5 single crystals, prepared according to the method described in Example 1, except that Lewis acid is not added.

[0048] Figure 1 This is a diagram illustrating the mechanism of action of Lewis acids in this invention. In this invention, CsI and CuI are used as reactants, and DMF and DMSO are used as solvents to dissolve the reactants. After adding Lewis acids and stirring until homogeneous, ethanol is used to reduce the solubility of the solution. CsI and CuI co-precipitate to form Cs3Cu2I5 powder. After filtering out this powder, the solution is in a critically supersaturated state. At this point, Cs3Cu2I5 seed crystals are added, and the solution is heated from 60°C to 80°C over a certain period of time to induce single crystal growth. This solution exhibits a reverse solubility curve, meaning that the solubility decreases as the temperature increases. As the temperature continues to rise, due to the low nucleation work on the seed crystal surface, the co-precipitated Cs3Cu2I5 will continuously grow on the seed crystal surface through the heating process, forming large-sized single crystals.

[0049] In the above process, Cu + Oxidation occurs during the growth stage. DMF / DMSO solvent readily dissolves trace amounts of oxygen, and Cu oxidation easily occurs during heating. + The oxidation of Cu is represented by the following equation:+ +O2+OH - →CuO + H₂O; The added Lewis acid ionizes into H+ under the influence of trace amounts of water in the solution (the trace water originates from the solvent's adsorption of water vapor from the air). + It can consume some OH - This achieves an antioxidant effect.

[0050] The raw materials used in this invention are CsI and CuI, wherein the iodide ions (I - In ethanol, heating, H + (Produced by Lewis acid hydrolysis) will form elemental iodine or triiodide ions (I3). - These processes are all reversible. If the amount of Lewis acid is insufficient, the antioxidant effect is not obvious; if the amount of Lewis acid is excessive, the reaction equilibrium shifts to the right, and more iodide ions will be converted into elemental iodine or triiodide ions, which will lead to less iodide ions available for crystallization. As a result, Cs3Cu2I5 cannot be formed through co-precipitation, which is detrimental to the preparation of large-size single crystals.

[0051] Besides the aforementioned issue of iodide ion content, another negative effect of excessive Lewis acids is the disruption of colloidal stability in the solution. Not all CsI and CuI in the solution are dissolved in DMF / DMSO in ionic form; a significant portion exists in colloidal form, effectively achieving greater "solubility" within the same solution volume. Increasing the Lewis acid content disrupts colloidal stability, converting it to ionic form and creating additional supersaturation. This, combined with the supersaturation provided by increased temperature, accelerates the co-precipitation of Cs3Cu2I5. This leads to an uncontrolled increase in the single crystal growth rate, making it prone to forming defects within the final product.

[0052] Figure 6 The Cs3Cu2I5 single crystals obtained in Examples 1, 4-7, and Comparative Example 1 (without YCl3) of this invention, as well as the commercial BGO scintillator (Bi4Ge3O) 12 The gamma-ray pulse height spectrum of the sample is shown in the figure. In the figure, (a) is the pulse height spectrum in the channel address range of 0 to 500, and the rightmost peak is the peak of each scintillator sample in Cs. 137 The full-energy peak under irradiation, (b) is the pulse height spectrum of Cs3Cu2I5 single crystal in the channel number range of 200-450. The sample with a higher full-energy peak channel number has a greater light yield. In the figure, 1% YCl3 to 5% YCl3 are Cs3Cu2I5 single crystal samples prepared in Examples 4, 1, 5-7, respectively. As can be seen from Figure b, as the amount of YCl3 added gradually increases, the single crystal light yield shows a trend of first increasing and then decreasing. The increase in light yield is due to the suppression effect of Lewis acid on defects. The decrease in light yield is due to the destruction of colloidal stability by excessive Lewis acid.Figure 6 In the middle (a), the shaded area on the left is the full-energy peak of the commercial scintillator BGO. It can be seen that the full-energy peak address of Cs3Cu2I5 is much higher than that of BGO, indicating that the prepared Cs3Cu2I5 single crystal phase has a significantly higher light yield than the traditional BGO scintillator.

[0053] Figure 7 Images of the Cs3Cu2I5 single crystals obtained in Example 1 and Comparative Example 1 are shown below. (a) is an image of the Cs3Cu2I5 single crystal obtained in Example 1 under sunlight; (b) is an image of the Cs3Cu2I5 single crystal obtained in Example 1 under 310 nm light; (c) is an image of the Cs3Cu2I5 single crystal obtained in Comparative Example 1 under sunlight; and (d) is an image of the Cs3Cu2I5 single crystal obtained in Comparative Example 1 under 310 nm light. Figure 7 It is evident that, due to the absence of Lewis acid, Cu-based oxidation products appeared within the single crystal. + Inclusions formed by oxidation result in poor crystal quality.

[0054] Figure 8 The figures show the colloidal stability test results of the precursor solutions obtained in Example 1 (with YCl3 added) and Comparative Example 1 (without YCl3 added). (a) is the zeta potential diagram, and (b) is the particle size distribution diagram. Figure (a) shows that the zeta potential of the sample without YCl3 changed significantly before and after the reaction, and the absolute value of the zeta potential was close to 0 mV. However, after adding YCl3, the zeta potential remained essentially unchanged before and after the reaction, maintaining a position of approximately -20 mV, with an absolute value significantly greater than 0 mV, indicating good colloidal stability. Figure (b) shows that the solution with YCl3 added maintained a smaller particle size distribution before and after the reaction, while the solution without YCl3 showed a larger particle size distribution before and after the reaction, indicating that the colloids aggregated.

[0055] In this invention, cesium iodide (CsI) and cuprous iodide (CuI) are used as precursors, and Lewis acids are used as additives. The reaction is carried out in a polar aprotic solvent under stirring. The weakly acidic environment generated by the hydrolysis of Lewis acids is used to inhibit the reaction of Cu. + The precursor solution is oxidized to obtain a stable precursor solution. Then, an antisolvent is added to the precursor solution to achieve supersaturation. After filtration, single crystal growth is performed using a reverse-temperature crystallization method. The Cs3Cu2I5 single crystal grown by this method exhibits a photoluminescence quantum yield of no less than 90% and a light yield of no less than 600 pe / MeV. After being placed in air for 60 days, the integrated photoluminescence intensity of the single crystal remains no less than 70% of its initial intensity. This single crystal has significant application value in the field of radiation detection.

[0056] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the inventive concept of the present invention, can make other changes and modifications to these embodiments, all of which fall within the scope of the present invention.

[0057] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. If such modifications and variations fall within the scope of equivalents of this invention, then this invention also intends to include these modifications and variations.

Claims

1. A method for growing Cs3Cu2I5 single crystals, characterized in that, Includes the following steps: Using cesium iodide and cuprous iodide as precursors, the precursors and Lewis acids are stirred evenly in a polar aprotic solvent. The acidic environment generated by the hydrolysis of the Lewis acid is utilized to inhibit Cu. + Oxidation occurs simultaneously, forming uniformly dispersed colloidal particles to obtain a precursor solution. Under stirring, an antisolvent was added to the precursor solution until the precursor solution reached a supersaturated state. After filtration, single crystal growth was carried out using the reverse temperature crystallization method to obtain Cs3Cu2I5 single crystals. The amount of Lewis acid added is 1% to 5% of the theoretical amount of Cs3Cu2I5 generated.

2. The Cs3Cu2I5 single crystal growth method according to claim 1, characterized in that, Lewis acids are selected from any one of yttrium chloride, cerium chloride, and lutetium chloride.

3. The Cs3Cu2I5 single crystal growth method according to claim 1, characterized in that, The molar ratio of cesium iodide to cuprous iodide is 1.50 to 1.63:

1.

4. The Cs3Cu2I5 single crystal growth method according to claim 1, characterized in that, Polar aprotic solvents are mixed solvents composed of N,N-dimethylformamide and dimethyl sulfoxide.

5. The method for growing Cs3Cu2I5 single crystals according to claim 1, characterized in that, The method of single crystal growth using the reverse temperature crystallization method involves raising the temperature from 60℃ to 80℃ within 80h to 120h to carry out single crystal growth.

6. The method for growing Cs3Cu2I5 single crystals according to claim 1, characterized in that, Before using the reverse temperature crystallization method for single crystal growth, the process also includes adding Cs3Cu2I5 seed crystals.

7. The method for growing Cs3Cu2I5 single crystals according to claim 1, characterized in that, The antisolvent is ethanol.

8. A Cs3Cu2I5 single crystal, characterized in that, The Cs3Cu2I5 single crystal is prepared using the Cs3Cu2I5 single crystal growth method described in any one of claims 1 to 7.

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