A yellow-green light-emitting single crystal material, a preparation method thereof and a yellow-green light-emitting device

Abstract

The present application relates to a kind of yellow-green light-emitting single crystal material and its preparation method and yellow-green light-emitting device.The preparation method includes mixing soluble alkali metal iodide and soluble luminescent center ion halide, dissolving the mixture in acid solution at first dissolution temperature, to obtain reactant solution;Reactant solution is cooled from first dissolution temperature to first end crystallization temperature according to first cooling rate, to obtain first crystal grain;First crystal grain is placed in reactant solution at second dissolution temperature, and is cooled to second end crystallization temperature according to second cooling rate, to obtain the yellow-green light-emitting single crystal material.The yellow-green light-emitting single crystal material prepared by the present application can have a quantum yield of up to 98.98% in the yellow-green waveband, and the preparation method is simple, and the production cycle is short.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic material preparation and application technology, and relates to a luminescent material, specifically a yellow-green luminescent single crystal material and its preparation method and yellow-green luminescent device. Background Technology

[0002] In the field of optical and optoelectronic materials, yellow-green luminescent materials have attracted much attention from researchers due to their wide application in display technology, lighting devices, optical sensors, and other fields. Yellow-green light is located in the middle of the visible spectrum (approximately 560 nm to 580 nm), which is suitable for human eye perception, and therefore plays an important role in a variety of optical applications.

[0003] However, among existing yellow-green luminescent materials, the most common are rare-earth-doped inorganic salts, such as those doped with rare earth elements like europium (Eu), cerium (Ce), and terbium (Tb). While these materials exhibit high luminescence efficiency, rare earth elements are scarce and expensive, and their extraction and production processes cause significant environmental pollution. Furthermore, the preparation of rare-earth-doped inorganic salt materials typically involves complex high-temperature solid-state reactions or other time-consuming high-temperature processes or crystal growth processes, resulting in high production costs that are difficult to meet the demands of large-scale industrial applications.

[0004] In recent years, copper (Cu), as a relatively inexpensive and abundant transition metal, has been widely studied for its use as a dopant in various optical materials. Copper-containing metal halides, with their advantages of low cost, low toxicity, abundant reserves, and excellent optical properties, have become an important class of photoluminescent materials. Copper ions (Cu...) + or Cu 2+ Copper-doped materials can emit visible light by controlling their optical properties through specific lattice doping. However, the photoluminescence efficiency of copper-doped materials typically depends on precise control of doping concentration, crystal structure, and crystal growth process. In existing technologies, whether rare-earth-doped or copper-doped, the distribution of dopants within the crystal is often uneven, leading to unstable luminescence performance and reduced luminescence efficiency. Therefore, it is necessary to optimize the synthesis method to ensure uniform distribution of copper ions and effectively activate luminescence performance.

[0005] CN112480911A discloses a method for preparing Cu-doped Cs₂AgI₃ perovskite, comprising transferring cesium iodide and silver iodide powders after ball milling to a hydrothermal reactor, adding cuprous iodide, hydroiodic acid, and hypophosphorous acid, performing hydrothermal treatment at 150°C to 200°C, and then cooling at -10°C to -35°C to obtain high-purity Cs₂AgI₃:Cu crystals with enhanced fluorescence efficiency. This method requires a combination of high-temperature hydrothermal reaction and low-temperature cooling, making it cumbersome and complex. However, the resulting Cs₂AgI₃:Cu crystals only achieve a quantum yield of 65.8% and only emit blue light, failing to emit yellow-green light.

[0006] CN116855750A discloses a method for preparing a high-yield, ultrafast scintillation decay, and low-cost Cs3Cu2I5:Mn single-crystal scintillator. The method includes thoroughly mixing and dispersing cuprous iodide, cesium iodide, manganese oxide, hydroiodic acid, and hypophosphorous acid to obtain a uniform mixed solution. After maintaining the mixed solution at 64°C for 2 days, a cooling program is set to decrease the temperature by 0.1°C per day. After 15 days of cooling growth, a seed crystal is obtained. The seed crystal is then fixed on a seed crystal holder and placed in the mixed solution. The cooling rate is 0.1°C / day, and the seed crystal rotation speed is 60 rpm. After 30 days of cooling growth, a high-yield, ultrafast scintillation decay, and low-cost Cs3Cu2I5:Mn single-crystal scintillator is obtained. Although the quantum yield of the obtained Cs3Cu2I5:Mn single crystal scintillator can reach 94.51%, it can only emit strong blue light and cannot emit yellow-green light. Moreover, its preparation cycle exceeds one and a half months, and its production efficiency is too low, which limits its feasibility and commercial development in large-scale applications.

[0007] Therefore, it is of great significance to provide a method for preparing a yellow-green luminescent material with uniform copper ion distribution, high luminous efficiency, low energy consumption, and high production efficiency. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a yellow-green luminescent single-crystal material, its preparation method, and a yellow-green luminescent device. This invention employs a solution cooling recrystallization method, a low-energy-consumption and easily controllable crystal growth process, to achieve the preparation of yellow-green luminescent single-crystal materials at relatively low temperatures. In this invention, the solution cooling recrystallization method enables uniform doping of luminescent center ions into soluble alkali metal iodide crystals at lower temperatures, promoting the stable growth of the soluble iodide crystals. The luminescent center ions can form new luminescent centers in the soluble alkali metal iodide lattice, endowing it with highly efficient luminescence characteristics in the yellow-green band. This improves the luminescence uniformity and quantum yield of the yellow-green luminescent single-crystal material. Furthermore, the solution cooling method offers more precise temperature control, is simpler to operate, and has higher production efficiency, which is beneficial for large-scale production.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for preparing a yellow-green luminescent single-crystal material, the method comprising:

[0011] (1) A mixture is obtained by mixing soluble alkali metal iodides and soluble luminescent ion halides;

[0012] (2) At the first dissolution temperature, the mixture described in step (1) is dissolved in an acid solution to obtain a first reactant solution. The first reactant solution is cooled from the first dissolution temperature to the first end crystallization temperature at a first cooling rate to obtain the first crystallization grain.

[0013] (3) At the second dissolution temperature, the mixture described in step (1) is dissolved in an acid solution to obtain a second reactant solution. The first crystallization grain from step (2) is added to the second reactant solution, and the temperature is lowered from the second dissolution temperature to the second end crystallization temperature at the second cooling rate to obtain the yellow-green luminescent single crystal material.

[0014] Both the first reactant solution and the second reactant solution are saturated solutions of soluble alkali metal iodides;

[0015] The acid solution comprises a combination of hydroiodic acid and hypophosphoric acid.

[0016] It should be noted that the first grain in this invention refers to the grain obtained after cooling to the first end crystallization temperature. The word "first" is only used to correspond to the first dissolution temperature and the first end crystallization temperature, and has no other special meaning or limiting effect.

[0017] This invention employs a solution cooling recrystallization method, a low-energy-consumption and easily controllable crystal growth process, to achieve the preparation of yellow-green luminescent single crystal materials at relatively low temperatures, meeting the energy-saving and environmental protection requirements of modern industry.

[0018] The solution cooling recrystallization method in this invention can achieve uniform doping of luminescent center ions in soluble alkali metal iodide crystals at lower temperatures and promote the stable growth of soluble iodide crystals. The luminescent center ions can form new luminescent centers in the soluble alkali metal iodide lattice, giving it high-efficiency luminescence characteristics in the yellow-green band. This improves the luminescence uniformity and quantum yield of yellow-green luminescent single crystal materials. Furthermore, the solution cooling method offers more precise temperature control, is easier to operate, has high production efficiency, is suitable for large-scale production, and meets the market demand for high-efficiency luminescent materials.

[0019] In steps (2) and (3), the first crystallization and the second crystallization are carried out according to the first cooling rate and the second cooling rate, respectively. Since the first crystallization and the second crystallization are both carried out in the reactant solution, the concentration of the crystallization solution is the same in the two crystallizations. Therefore, controlling the cooling rate can effectively regulate the composition of the material precipitated in the solution, thereby regulating the composition of the crystal surface accumulation. This is beneficial to the uniform distribution of the luminescent ion centers in the material, ensuring the uniform distribution of the luminescent center ions in the soluble alkali metal iodide lattice, and the stable growth of the yellow-green luminescent single crystal material lattice.

[0020] After the first crystallization, the first crystal with good crystal quality is placed back into the reactant solution for a second crystallization, which is beneficial for inducing ions to accumulate and crystallize on the surface of the first crystal, and is conducive to further growth of crystal size.

[0021] Preferably, the first dissolution temperature in step (2) is 50-70℃, for example, it can be 50℃, 53℃, 55℃, 58℃, 60℃, 63℃, 65℃, 68℃ or 70℃, etc., including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0022] In this invention, the first dissolution temperature is 50-70℃, the purpose of which is to ensure that soluble alkali metal iodides and soluble luminescent central ion halides can dissolve at the first dissolution temperature.

[0023] Preferably, the first end crystallization temperature in step (2) is 20℃-30℃, for example, it can be 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃ or 30℃, etc., including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0024] Preferably, the second dissolution temperature in step (3) is 50-70℃, for example, it can be 50℃, 53℃, 55℃, 58℃, 60℃, 63℃, 65℃, 68℃ or 70℃, etc., including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0025] Preferably, the second end crystallization temperature in step (3) is 20℃-30℃, for example, it can be 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃ or 30℃, etc., including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0026] Preferably, the first dissolution temperature is the same as the second dissolution temperature, and the first end crystallization temperature is the same as the second end crystallization temperature.

[0027] In this invention, the first dissolution temperature and the second dissolution temperature are the same, and the first crystallization termination temperature and the second crystallization termination temperature are the same. This ensures, on the one hand, that the concentrations of each reactant in the reactant solution and the crystal growth solution are the same, which is beneficial for the uniform dispersion of luminescent central ions, thereby ensuring the uniform distribution of luminescent central ions in the soluble alkali metal iodide lattice. On the other hand, it ensures the stable growth of the soluble alkali metal iodide lattice. Through the uniform distribution of luminescent central ions in the soluble alkali metal iodide lattice and the stable growth of the soluble alkali metal iodide lattice, the luminescence uniformity of the yellow-green luminescent single crystal material is ensured, and the quantum yield of the yellow-green luminescent single crystal material in the yellow-green light band is improved.

[0028] Preferably, the first cooling rate in step (2) is 0.7℃ / h-2℃ / h, for example, it can be 0.7℃ / h, 0.8℃ / h, 0.9℃ / h, 1℃ / h, 1.1℃ / h, 1.2℃ / h, 1.3℃ / h, 1.4℃ / h, 1.5℃ / h, 1.6℃ / h, 1.7℃ / h, 1.8℃ / h, 1.9℃ / h or 2℃ / h, including but not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1℃ / h-1.6℃ / h.

[0029] Preferably, the second cooling rate in step (3) is 0.7℃ / h-2℃ / h, for example, it can be 0.7℃ / h, 0.8℃ / h, 0.9℃ / h, 1℃ / h, 1.1℃ / h, 1.2℃ / h, 1.3℃ / h, 1.4℃ / h, 1.5℃ / h, 1.6℃ / h, 1.7℃ / h, 1.8℃ / h, 1.9℃ / h or 2℃ / h, including but not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1℃ / h-1.6℃ / h.

[0030] Preferably, the first cooling rate is the same as the second cooling rate.

[0031] In this invention, the first and second cooling rates are precisely controlled to ensure that the luminescent center ions are uniformly distributed in the alkali metal iodide lattice during the crystallization process, and that the alkali metal iodide grows stably. This improves the luminescence uniformity and quantum dot yield of the yellow-green luminescent single crystal material, and exhibits excellent luminescence performance in the yellow-green spectral range.

[0032] The first cooling rate is the same as the second cooling rate. Since the concentration of the crystallization solution is the same in both cases, the composition of the material precipitated from the solution in the same time period is the same, and the composition of the crystal surface is almost the same, which is conducive to the uniform distribution of luminescent center ions in the crystal.

[0033] Preferably, the soluble luminescent central ionic halide includes copper iodide.

[0034] Preferably, the soluble alkali metal iodide includes potassium iodide.

[0035] Potassium iodide is a common salt crystal with good optical transparency and physicochemical stability, but it does not possess luminescent properties. By doping potassium iodide crystals with luminescent center ions, new optical properties can be acquired, especially luminescence in the yellow-green spectral range. Furthermore, potassium iodide crystals are easily grown using low-temperature techniques such as solution methods, which offers the possibility of developing low-cost, high-efficiency luminescent materials.

[0036] The potassium iodide and copper iodide materials used in this invention are both inexpensive and environmentally friendly compounds, avoiding the high cost of rare earth elements and their potential environmental pollution problems, making them suitable for large-scale applications.

[0037] Preferably, the molar ratio of the soluble alkali metal iodide to the soluble luminescent central ion halide is 3:(0.5-3), for example, it can be 3:0.5, 3:1, 3:1.5, 3:2, 3:2.5 or 3:3, including but not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 3:(1.5-3).

[0038] Preferably, in the acid solution, the concentration of hydroiodic acid is 5-7 mol / L, for example, it can be 5 mol / L, 5.5 mol / L, 6 mol / L, 6.5 mol / L or 7 mol / L; the concentration of hypophosphoric acid is 1-2 mol / L, for example, it can be 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L or 2 mol / L, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0039] In this invention, hydroiodic acid in the acid solution serves as a solvent, allowing the soluble alkali metal iodides and soluble luminescent ion halides to fully dissolve and mix. Hypophosphoric acid acts as an inhibitor, suppressing Cu. + Oxidized to Cu 2+ .

[0040] Preferably, the preparation method further includes cleaning and drying the yellow-green luminescent single crystal material obtained in step (3).

[0041] Preferably, the cleaning includes cleaning with ethanol to remove residues.

[0042] Preferably, the drying temperature is 60℃-90℃, for example, it can be 60℃, 65℃, 70℃, 75℃, 80℃, 85℃ or 90℃, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0043] In a second aspect, this application provides a yellow-green luminescent single crystal material, which is prepared by the preparation method described in the first aspect.

[0044] In the yellow-green luminescent single-crystal material of this invention, the luminescent center ions are uniformly distributed in the alkali metal iodide lattice. Doping with luminescent center ions can form new luminescent centers in the alkali metal iodide lattice, endowing it with efficient luminescence characteristics in the yellow-green band. Compared with undoped alkali metal iodide materials, the introduction of luminescent center ions provides additional electronic states, which helps to improve photoluminescence performance.

[0045] Preferably, the yellow-green luminescent single crystal material is a yellow-green luminescent Cu-doped KI single crystal material.

[0046] Preferably, in the high-efficiency yellow-green luminescent Cu-doped KI single crystal material, the molar ratio of KI to CuI is 3:(0.5-3), for example, it can be 3:0.5, 3:1, 3:1.5, 3:2, 3:2.5 or 3:3, including but not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 3:(1.5-3).

[0047] In the yellow-green luminescent Cu-doped KI single crystal material of the present invention, Cu + Uniform distribution of Cu doping in the KI lattice + It can form new luminescent centers in the KI lattice, giving it high-efficiency luminescence characteristics in the yellow-green band.

[0048] Thirdly, this application provides a yellow-green light-emitting device, which includes the yellow-green light-emitting single crystal material as described in the second aspect.

[0049] The yellow-green luminescent single-crystal material of this invention has significant luminescent properties in the yellow-green spectral region, which meets the needs of solid-state lighting, optical sensors and display devices for high-efficiency luminescent materials and has broad application prospects.

[0050] Compared with the prior art, the present invention has at least the following beneficial effects:

[0051] (1) This invention uses a solution cooling recrystallization method, a low-energy-consumption and easy-to-control crystal growth process, to prepare yellow-green luminescent single crystal materials at a lower temperature. Through the crystal growth process under specific temperature conditions, it ensures that the luminescent center ions are uniformly doped in the soluble alkali metal iodide lattice and promotes the stable growth of soluble iodide crystals, thereby improving the luminescence uniformity and quantum yield of the yellow-green luminescent single crystal materials. Furthermore, the solution cooling method has more precise temperature control, is easier to operate, has high production efficiency, and is suitable for large-scale production.

[0052] (2) The present invention achieves a uniform distribution of luminescent center ions in soluble alkali metal iodide crystals. Doping with luminescent center ions can form new luminescent centers in the alkali metal iodide lattice, giving it high efficiency luminescence characteristics in the yellow-green band. It has high efficiency photoluminescence performance in the yellow-green band (about 450nm to 700nm) with a luminescence quantum yield of up to 98.98%.

[0053] (3) The yellow-green luminescent single crystal material in this invention has significant luminescent properties in the yellow-green spectral region, which meets the needs of solid-state lighting, optical sensors and display devices for high-efficiency luminescent materials and has broad application prospects. Attached Figure Description

[0054] Figure 1 This is a process flow diagram of the preparation method provided by the present invention.

[0055] Figure 2 This is a schematic diagram of the yellow-green luminescent single crystal material prepared in Example 5 of the present invention and the yellow-green light emitted.

[0056] Figure 3 These are the XRD patterns of the yellow-green luminescent single crystal materials prepared in Examples 1 to 6 and Comparative Example 1.

[0057] Figure 4 This is the TEM image of the yellow-green luminescent single crystal material prepared in Example 5.

[0058] Figure 5 This is the EDS spectrum of the yellow-green luminescent single crystal material prepared in Example 5.

[0059] Figure 6 This is a quantum yield diagram of the yellow-green luminescent single crystal material prepared in Example 5.

[0060] Figure 7 These are the excitation spectra of the yellow-green luminescent single-crystal materials prepared in Examples 1 to 6 and Comparative Example 1.

[0061] Figure 8 These are the emission spectra of the yellow-green luminescent single-crystal materials prepared in Examples 1 to 6 and Comparative Example 1.

[0062] Figure 9 These are the absorption spectra of the yellow-green luminescent single-crystal materials prepared in Example 5 and Comparative Example 1.

[0063] Figure 10 The bandgap spectrum is shown for the yellow-green luminescent single crystal materials prepared in Example 5 and Comparative Example 1. Detailed Implementation

[0064] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0065] Example 1

[0066] This embodiment provides a yellow-green luminescent single-crystal material, and the preparation method of the yellow-green luminescent single-crystal material is as follows:

[0067] (1) Mix 0.3 mol potassium iodide with 0.05 mol copper iodide to obtain a mixture of potassium iodide and copper iodide;

[0068] (2) At the first dissolution temperature of 70°C, a mixture of potassium iodide and copper iodide is added to an acid solution, wherein the concentration of hydroiodic acid in the acid solution is 6.5 mol / L and the concentration of hypophosphoric acid is 1.6 mol / L. The mixture is heated and stirred for 3 hours to fully dissolve the potassium iodide and copper iodide, resulting in a first reactant solution, which is a saturated solution of potassium iodide. The first reactant solution is then uniformly cooled from the first dissolution temperature of 70°C to the first final crystallization temperature of 20°C at a first cooling rate of 2°C / h. The solution is filtered to obtain the first crystals, and the first crystals are washed with ethanol to remove residual reactant solution.

[0069] (3) At the second dissolution temperature of 70°C, a mixture of potassium iodide and copper iodide is added to an acid solution, wherein the concentration of hydroiodic acid in the acid solution is 6.5 mol / L and the concentration of hypophosphoric acid is 1.6 mol / L. The mixture is heated and stirred for 3 hours to fully dissolve the potassium iodide and copper iodide to obtain a second reactant solution, which is a saturated solution of potassium iodide. The first crystal obtained in step (2) is added to the second reactant solution, and the temperature is uniformly reduced from the second dissolution temperature of 70°C to the second final crystallization temperature of 20°C at a second cooling rate of 2°C / h. The obtained crystal is filtered and washed with ethanol, and then dried at 60°C to obtain the yellow-green luminescent single crystal material.

[0070] Example 2

[0071] This embodiment provides a yellow-green luminescent single-crystal material, and the preparation method of the yellow-green luminescent single-crystal material is as follows:

[0072] (1) Mix 0.3 mol potassium iodide with 0.1 mol copper iodide to obtain a mixture of potassium iodide and copper iodide;

[0073] (2) At the first dissolution temperature of 50°C, a mixture of potassium iodide and copper iodide is added to an acid solution, wherein the concentration of hydroiodic acid in the acid solution is 6 mol / L and the concentration of hypophosphoric acid is 1.5 mol / L. The mixture is heated and stirred for 4 h to fully dissolve the potassium iodide and copper iodide, resulting in a first reactant solution, which is a saturated solution of potassium iodide. The first reactant solution is uniformly cooled from the first dissolution temperature of 50°C to the first final crystallization temperature of 27°C at a first cooling rate of 0.71°C / h. The mixture is filtered to obtain the first crystals, and the first crystals are washed with ethanol to remove residual reactant solution.

[0074] (3) At the second dissolution temperature of 56℃, a mixture of potassium iodide and copper iodide was added to an acid solution, wherein the concentration of hydroiodic acid in the acid solution was 6 mol / L and the concentration of hypophosphoric acid was 1.5 mol / L. The mixture was heated and stirred for 4 h to fully dissolve the potassium iodide and copper iodide, resulting in a second reactant solution, which was a saturated solution of potassium iodide. The first crystal obtained in step (2) was added to the second reactant solution, and the mixture was uniformly cooled from the second dissolution temperature of 56℃ to the second final crystallization temperature of 27℃ at a second cooling rate of 0.71℃ / h. The obtained crystal was filtered, washed with ethanol, and dried at 70℃ to obtain a yellow-green luminescent single crystal material.

[0075] Example 3

[0076] This embodiment provides a yellow-green luminescent single-crystal material, and the preparation method of the yellow-green luminescent single-crystal material is as follows:

[0077] (1) Mix 0.3 mol potassium iodide with 0.15 mol copper iodide to obtain a mixture of potassium iodide and copper iodide;

[0078] (2) At the first dissolution temperature of 56°C, a mixture of potassium iodide and copper iodide is added to an acid solution, wherein the concentration of hydroiodic acid in the acid solution is 7 mol / L and the concentration of hypophosphoric acid is 2 mol / L. The mixture is heated and stirred for 4 h to fully dissolve the potassium iodide and copper iodide to obtain a first reactant solution, which is a saturated solution of potassium iodide. The first reactant solution is uniformly cooled from the first dissolution temperature of 56°C to the first final crystallization temperature of 24°C at a first cooling rate of 0.86°C / h. The first crystals are obtained by filtration and washed with ethanol to remove residual reactant solution.

[0079] (3) At the second dissolution temperature of 56℃, a mixture of potassium iodide and copper iodide was added to an acid solution, wherein the concentration of hydroiodic acid in the acid solution was 7 mol / L and the concentration of hypophosphoric acid was 2 mol / L. The mixture was heated and stirred for 4 h to fully dissolve the potassium iodide and copper iodide, resulting in a second reactant solution, which was a saturated solution of potassium iodide. The first crystal obtained in step (2) was added to the second reactant solution, and the mixture was uniformly cooled from the second dissolution temperature of 56℃ to the second final crystallization temperature of 24℃ at a first cooling rate of 0.86℃ / h. The obtained crystal was filtered, washed with ethanol, and dried at 60℃ to obtain a yellow-green luminescent single crystal material.

[0080] Example 4

[0081] This embodiment provides a yellow-green luminescent single-crystal material, and the preparation method of the yellow-green luminescent single-crystal material is as follows:

[0082] (1) Mix 0.3 mol potassium iodide with 0.2 mol copper iodide to obtain a mixture of potassium iodide and copper iodide;

[0083] (2) At the first dissolution temperature of 65°C, a mixture of potassium iodide and copper iodide is added to an acid solution, wherein the concentration of hydroiodic acid in the acid solution is 6 mol / L and the concentration of hypophosphoric acid is 1 mol / L. The mixture is heated and stirred for 6 h to fully dissolve the potassium iodide and copper iodide, resulting in a first reactant solution, which is a saturated solution of potassium iodide. The first reactant solution is uniformly cooled from the first dissolution temperature of 65°C to the first final crystallization temperature of 26°C at a first cooling rate of 1.05°C / h. The solution is filtered to obtain the first crystals, and the first crystals are washed with ethanol to remove residual reactant solution.

[0084] (3) At the second dissolution temperature of 63°C, a mixture of potassium iodide and copper iodide is added to an acid solution, wherein the concentration of hydroiodic acid in the acid solution is 6 mol / L and the concentration of hypophosphoric acid is 1 mol / L. The mixture is heated and stirred for 6 h to fully dissolve the potassium iodide and copper iodide to obtain a second reactant solution, which is a saturated solution of potassium iodide. The first crystal obtained in step (2) is added to the second reactant solution, and the temperature is uniformly reduced from the second dissolution temperature of 63°C to the second final crystallization temperature of 28°C at a first cooling rate of 1.08°C / h. The obtained crystal is filtered and washed with ethanol, and dried at 80°C to obtain a yellow-green luminescent single crystal material.

[0085] Example 5

[0086] This embodiment provides a yellow-green luminescent single-crystal material, and the preparation method of the yellow-green luminescent single-crystal material is as follows:

[0087] (1) Mix 0.3 mol potassium iodide with 0.25 mol copper iodide to obtain a mixture of potassium iodide and copper iodide;

[0088] (2) At the first dissolution temperature of 60°C, a mixture of potassium iodide and copper iodide is added to an acid solution, wherein the concentration of hydroiodic acid in the acid solution is 5 mol / L and the concentration of hypophosphoric acid is 2 mol / L. The mixture is heated and stirred for 5 h to fully dissolve the potassium iodide and copper iodide to obtain a first reactant solution, which is a saturated solution of potassium iodide. The first reactant solution is uniformly cooled from the first dissolution temperature of 60°C to the first final crystallization temperature of 25°C at a first cooling rate of 1.25°C / h. The first crystals are obtained by filtration and washed with ethanol to remove residual reactant solution.

[0089] (3) At the second dissolution temperature of 60°C, a mixture of potassium iodide and copper iodide is added to an acid solution, wherein the concentration of hydroiodic acid in the acid solution is 5 mol / L and the concentration of hypophosphoric acid is 2 mol / L. The mixture is heated and stirred for 5 h to fully dissolve the potassium iodide and copper iodide to obtain a second reactant solution, which is a saturated solution of potassium iodide. The first crystal obtained in step (2) is added to the second reactant solution, and the temperature is uniformly reduced from the second dissolution temperature of 60°C to the second final crystallization temperature of 25°C at a first cooling rate of 1.25°C / h. The obtained crystal is filtered and washed with ethanol. After drying at 60°C, a yellow-green luminescent single crystal material is obtained.

[0090] Example 6

[0091] This embodiment provides a yellow-green luminescent single-crystal material, and the preparation method of the yellow-green luminescent single-crystal material is as follows:

[0092] (1) Mix 0.3 mol potassium iodide with 0.3 mol copper iodide to obtain a mixture of potassium iodide and copper iodide;

[0093] (2) At the first dissolution temperature of 70°C, a mixture of potassium iodide and copper iodide is added to an acid solution, wherein the concentration of hydroiodic acid in the acid solution is 7 mol / L and the concentration of hypophosphoric acid is 1 mol / L. The mixture is heated and stirred for 5 h to fully dissolve the potassium iodide and copper iodide, resulting in a first reactant solution, which is a saturated solution of potassium iodide. The first reactant solution is uniformly cooled from the first dissolution temperature of 70°C to the first final crystallization temperature of 25°C at a first cooling rate of 1.84°C / h. The first crystals are obtained by filtration and then washed with ethanol to remove residual reactant solution.

[0094] (3) At the second dissolution temperature of 70°C, a mixture of potassium iodide and copper iodide is added to an acid solution, wherein the concentration of hydroiodic acid in the acid solution is 7 mol / L and the concentration of hypophosphoric acid is 1 mol / L. The mixture is heated and stirred for 5 h to fully dissolve the potassium iodide and copper iodide to obtain a second reactant solution, which is a saturated solution of potassium iodide. The first crystal obtained in step (2) is added to the second reactant solution, and the temperature is uniformly reduced from the second dissolution temperature of 70°C to the second final crystallization temperature of 25°C at a first cooling rate of 1.84°C / h. The obtained crystal is filtered and washed with ethanol, and dried at 90°C to obtain a yellow-green luminescent single crystal material.

[0095] Example 7

[0096] This embodiment provides a yellow-green luminescent single crystal material. The preparation method of the yellow-green luminescent single crystal material is the same as that of Embodiment 5, except that the first cooling rate in step (2) is 0.67℃ / h and the second cooling rate in step (3) is 0.67℃ / h.

[0097] Example 8

[0098] This embodiment provides a yellow-green luminescent single crystal material. The preparation method of the yellow-green luminescent single crystal material is the same as that of Embodiment 5, except that the first cooling rate in step (2) is 2.4℃ / h and the second cooling rate in step (3) is 2.4℃ / h.

[0099] Example 9

[0100] This embodiment provides a yellow-green luminescent single crystal material. The preparation method of the yellow-green luminescent single crystal material is the same as that in Example 5, except that the amount of copper iodide in step (1) is 0.0015 mol.

[0101] Example 10

[0102] This embodiment provides a yellow-green luminescent single crystal material. The preparation method of the yellow-green luminescent single crystal material is the same as that in Example 5, except that the amount of copper iodide in step (1) is 0.35 mol.

[0103] Comparative Example 1

[0104] This embodiment provides a KI single crystal material. The preparation method of the KI single crystal material is the same as that in Example 5, except that copper iodide is not added in step (1).

[0105] Comparative Example 2

[0106] This embodiment provides a yellow-green luminescent material. The preparation method of the yellow-green luminescent material is the same as that of Embodiment 5, except that the cooling method in steps (2) and (3) is natural cooling.

[0107] Comparative Example 3

[0108] This embodiment provides a yellow-green luminescent single-crystal material, and the preparation method of the yellow-green luminescent single-crystal material is as follows:

[0109] (1) Mix 0.3 mol potassium iodide with 0.25 mol copper iodide to obtain a mixture of potassium iodide and copper iodide;

[0110] (2) At the first dissolution temperature of 60°C, a mixture of potassium iodide and copper iodide was added to an acid solution, wherein the concentration of hydroiodic acid in the acid solution was 6.5 mol / L and the concentration of hypophosphoric acid was 1.6 mol / L. The mixture was heated and stirred for 5 h to fully dissolve the potassium iodide and copper iodide, resulting in a first reactant solution, which was a saturated solution of potassium iodide. The first reactant solution was uniformly cooled from the first dissolution temperature of 60°C to the first final crystallization temperature of 25°C at a cooling rate of 1.25°C / h for 48 h. The resulting crystals were filtered, washed with ethanol, and dried at 60°C to obtain a yellow-green luminescent single crystal material.

[0111] Performance testing:

[0112] The crystal structures of the yellow-green luminescent single crystal materials prepared in Examples 1-6 and Comparative Example 1 were tested by XRD.

[0113] The yellow-green luminescent Cu-doped potassium iodide single crystal material prepared in Example 5 was subjected to TEM and EDS tests.

[0114] The quantum dot yield, excitation peak, emission peak, and band gap of the yellow-green luminescent single crystal materials prepared in Examples 1-10 and Comparative Example 1 were tested, and the test results are shown in Table 1.

[0115] Table 1

[0116]

[0117] according to Figure 3 The XRD patterns shown indicate that the XRD diffraction peaks of the yellow-green luminescent single-crystal materials prepared in Examples 1-6 all correspond to the PDF spectra of potassium iodide, proving that potassium iodide single-crystal materials were successfully synthesized. Furthermore, the peak positions around 25.248° show varying degrees of shift, which is due to the Cu... + Successful doping. In this invention, a yellow-green luminescent single-crystal material was successfully prepared by solution cooling recrystallization. Under ultraviolet light irradiation, the yellow-green luminescent single-crystal material prepared in this invention can emit yellow-green light.

[0118] Figure 4The TEM image shows that the diffraction fringe spacing of the single crystal material is 0.357 nm, which corresponds to the (111) face in the PDF of potassium iodide, indicating that the material is the KI phase.

[0119] Figure 5 The EDS spectrum shown clearly demonstrates the uniform distribution of potassium, copper, and iodine in the material, further proving the presence of Cu. + Successful doping.

[0120] The data in Table 1 shows that in the yellow-green luminescent Cu-doped KI single crystal material prepared by this invention, due to Cu... + Uniform distribution of Cu doping in the KI lattice + Cu can form new luminescent centers in the KI lattice, endowing it with highly efficient luminescence properties in the yellow-green wavelength range (approximately 560 nm to 580 nm), exhibiting high photoluminescence performance with a luminescent quantum yield as high as 98.98%. Compared to the undoped KI single crystal material in Comparative Example 1, Cu... + The introduction of provides additional electronic states, endowing KI single-crystal materials with yellow-green luminescence properties. From Figure 7 and Figure 8 As can be seen from the data, the pure-phase KI single crystal in Comparative Example 1 almost lacks excitation and emission peaks, meaning it does not possess excitation or photoluminescence properties. However, after processing with Cu... + After doping, Examples 1 to 6 showed obvious excitation peaks at 349 nm and 361 nm, indicating that they possessed excitation characteristics, and showed obvious emission peaks in the 561 nm yellow-green light band, indicating that they possessed the characteristic of emitting yellow-green light.

[0121] According to the data of Comparative Example 2, natural cooling is used in both steps (2) and (3), which can only produce powdered materials and cannot produce yellow-green luminescent single crystal materials. The luminescence performance in the yellow-green band is far worse than that of the yellow-green luminescent single crystal materials prepared by uniform cooling at a certain cooling rate in this invention. This is because natural cooling is not conducive to the growth of single crystals, and it is even impossible to grow single crystal materials.

[0122] By comparing the data of Example 5 and Comparative Example 3, if the yellow-green luminescent single crystal material is obtained directly through step (2) without following the solution cooling recrystallization method in this invention, and placing the first crystal in the reactant solution for the second crystallization, it will be detrimental to the growth of the single crystal, and the size of the obtained single crystal will be smaller, resulting in a poorer yellow-green luminescent performance.

[0123] By comparing the data from Example 5 with those from Examples 7 and 8, it can be found that both excessively high and excessively low cooling rates are detrimental to the uniform distribution of luminescent center ions in the alkali metal iodide lattice and to the stable growth of alkali metal iodides, resulting in a decrease in the luminescence uniformity and quantum dot yield of the yellow-green luminescent single crystal material.

[0124] By comparing the data from Examples 5, 9, and 10, it can be found that if the molar ratio of luminescent center ions is too small, the number of luminescent centers will be insufficient, resulting in a low quantum yield. If the molar ratio of luminescent center ions is too large, there will be too many defects in the crystal and excessive lattice distortion, affecting the luminescence efficiency of the yellow-green luminescent single crystal material. Therefore, both a molar ratio of luminescent center ions that is too small or too large will lead to a deterioration in the photoluminescence performance and a low quantum yield of the prepared yellow-green luminescent single crystal material, thereby affecting its high-efficiency luminescence characteristics in the yellow-green band.

[0125] The applicant declares that the detailed method of the present invention is illustrated by the above embodiments, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a yellow-green luminescent single-crystal material, characterized in that, The preparation method includes: (1) A mixture is obtained by mixing soluble alkali metal iodides and soluble luminescent ion halides; (2) At the first dissolution temperature, the mixture described in step (1) is dissolved in an acid solution to obtain a first reactant solution. The first reactant solution is cooled from the first dissolution temperature to the first end crystallization temperature at a first cooling rate to obtain the first crystallization grains. (3) At the second dissolution temperature, the mixture described in step (1) is dissolved in an acid solution to obtain a second reactant solution. The first crystallization grain from step (2) is added to the second reactant solution, and the temperature is lowered from the second dissolution temperature to the second end crystallization temperature at the second cooling rate to obtain the yellow-green luminescent single crystal material. Both the first reactant solution and the second reactant solution are saturated solutions of soluble alkali metal iodides; The acid solution comprises a combination of hydroiodic acid and hypophosphite; The soluble alkali metal iodide includes potassium iodide; the soluble luminescent central ion halide includes copper iodide. In step (2), the first dissolution temperature is 50℃-70℃; in step (2), the first crystallization termination temperature is 20℃-30℃. In step (3), the second dissolution temperature is 50℃-70℃; in step (3), the second final crystallization temperature is 20℃-30℃.

2. The preparation method according to claim 1, characterized in that, The first dissolution temperature is the same as the second dissolution temperature.

3. The preparation method according to claim 1, characterized in that, The first crystallization termination temperature is the same as the second crystallization termination temperature.

4. The preparation method according to claim 1, characterized in that, Step (2) The first cooling rate is 0.7℃ / h-2℃ / h.

5. The preparation method according to claim 4, characterized in that, Step (2) The first cooling rate is 1℃ / h-1.6℃ / h.

6. The preparation method according to claim 1, characterized in that, Step (3) The second cooling rate is 0.7℃ / h-2℃ / h.

7. The preparation method according to claim 6, characterized in that, Step (3) The second cooling rate is 1℃ / h-1.6℃ / h.

8. The preparation method according to claim 1, characterized in that, The first cooling rate is the same as the second cooling rate.

9. The preparation method according to claim 1, characterized in that, The molar ratio of soluble alkali metal iodides to soluble luminescent central ion halides in the reactant solution is 3:(0.5-3).

10. The preparation method according to claim 9, characterized in that, The molar ratio of soluble alkali metal iodides to soluble luminescent central ion halides in the reactant solution is 3:(1.5-3).

11. The preparation method according to claim 1, characterized in that, In the acid solution, the concentration of hydroiodic acid is 5-7 mol / L, and the concentration of hypophosphoric acid is 1-2 mol / L.

12. The preparation method according to claim 1, characterized in that, The preparation method further includes cleaning and drying the yellow-green luminescent single crystal material obtained in step (3).

13. The preparation method according to claim 12, characterized in that, The cleaning process includes using ethanol to remove residues.

14. The preparation method according to claim 12, characterized in that, The drying temperature is 60℃-90℃.

15. A yellow-green luminescent single-crystal material, characterized in that, The yellow-green luminescent single crystal material is prepared by the preparation method according to any one of claims 1-14; The yellow-green luminescent single crystal material is a yellow-green luminescent Cu-doped KI single crystal material.

16. The yellow-green luminescent single-crystal material according to claim 15, characterized in that, In the yellow-green luminescent Cu-doped KI single crystal material, the molar ratio of KI to CuI is 3:(0.5-3).

17. The yellow-green luminescent single-crystal material according to claim 16, characterized in that, In the yellow-green luminescent Cu-doped KI single crystal material, the molar ratio of KI to CuI is 3:(1.5-3).

18. A yellow-green light-emitting device, characterized in that, The yellow-green light-emitting device includes the yellow-green light-emitting single crystal material as described in any one of claims 15 to 17.

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