Halide perovskite light-emitting material with negative thermal quenching effect and preparation method and application thereof

Abstract

This invention discloses a halide perovskite luminescent material with a negative thermal quenching effect, its preparation method, and its applications, relating to the field of inorganic luminescent materials technology. The halide perovskite luminescent material of this invention maintains good luminescence performance even at high temperatures. At 152°C, it retains 158% of its room-temperature luminescence intensity, and at 227°C, it still maintains approximately 130% of its room-temperature luminescence intensity. After doping with rare-earth ions, it also exhibits excellent thermal stability and negative thermal quenching characteristics, maintaining 136% of its room-temperature luminescence intensity at 102°C, and approximately 117% of its room-temperature luminescence intensity at the maximum operating temperature of white LEDs (152°C). The emission peaks are very narrow, and the emitted green and red light have high color rendering indices, making it widely applicable in the fields of white LEDs and displays.

Description

Technical Field

[0001] This invention relates to the field of inorganic luminescent materials technology, and more specifically, to a halide perovskite luminescent material with negative thermal quenching effect, its preparation method, and its application. Background Technology

[0002] With the ever-increasing demand for energy, existing traditional fossil fuels are inevitably becoming increasingly depleted. To gradually reduce dependence on fossil fuels and achieve a shift towards "low-carbon energy," it is crucial to innovate lighting technologies and explore photoluminescent (PL) materials. In recent years, halide perovskites, as a novel type of photoluminescent material, have demonstrated excellent carrier transport performance, highly tunable emission spectra, high defect tolerance, and high fluorescence quantum yield (PLQY), making them one of the most promising photoluminescent materials currently available. The potential applications of halide perovskites are extensive, showing promising prospects in lighting, displays, solar energy, medical imaging, and plant lighting. However, the poor thermal stability and significant fluorescence quenching of halide perovskites greatly hinder their application in lighting and other fields. For white light-emitting diodes (LEDs), the maximum operating temperature can reach 151.9℃. However, most perovskite materials exhibit severe thermal quenching at the maximum operating temperature of LEDs, failing to maintain their luminescent performance effectively.

[0003] The prior art discloses a highly thermally stable indium-doped perovskite quantum dot luminescent material. This perovskite quantum dot luminescent material is an In-doped CsPbBr3 perovskite quantum dot material with the chemical formula CsPb. 1-x In x Br3, where 0.40 ≤ x ≤ 0.50. The specific preparation method of this indium-doped perovskite quantum dot luminescent material is carried out according to the following steps:

[0004] Step 1: Mix 0.102-0.407g of cesium carbonate, 5-20mL of 1-octadecene and 0.4-1.3mL of oleic acid in a nitrogen atmosphere and stir. Heat the mixture to 120-130℃ and keep it at that temperature to completely dissolve the cesium carbonate and obtain the cesium oleate precursor.

[0005] Step 2: According to the ratio of 0.5 mL oleic acid, 0.5 mL oleylamine, 5 mL 1-octadecene, and 0.2-0.4 mL ligand required for 0.188 mmol of perovskite material, take the perovskite material, oleic acid, oleylamine, 1-octadecene, and ligand respectively. Add the perovskite material, oleic acid, oleylamine, and 1-octadecene to a three-necked flask at room temperature. Stir under a nitrogen atmosphere and heat to 120-130°C, then evacuate for 5-10 min. Then, under nitrogen protection and at the same temperature, stir under vacuum until the perovskite material is completely dissolved, obtaining a clear and transparent solution. Heat to 175-185°C under a nitrogen atmosphere and hold for 5-10 min. Add the ligand to obtain a clear and transparent lead-indium precursor.

[0006] Step 3: Under inert gas protection, 0.4–0.6 mL of cesium oleate precursor (151.9–160 °C) was rapidly injected into 5.5–6.5 mL of lead-indium precursor (175–185 °C). The reaction was allowed to proceed for 5–10 seconds, followed immediately by an ice-water bath to cool to room temperature, yielding a crude solution. The precipitate was separated by centrifugation, washed with n-hexane, and then completely dissolved in n-hexane to obtain a highly thermally stable indium-doped perovskite quantum dot luminescent material. This indium-doped perovskite quantum dot luminescent material exhibits a stronger binding energy due to In doping, resulting in a narrower full width at half maximum (FWHM) (approximately 20 nm) and better thermal stability, maintaining 39.9% of the luminescence intensity at room temperature even at 120 °C. However, this indium-doped perovskite quantum dot luminescent material still exhibits significant thermal quenching and cannot meet the thermal stability requirements for applications such as white LEDs. Summary of the Invention

[0007] The technical problem this invention aims to solve is to overcome the defects and shortcomings of existing halide perovskite materials, such as poor thermal stability and significant thermal quenching, and to provide a halide perovskite luminescent material with a negative thermal quenching effect, and proposes a doping scheme. By doping this halide perovskite green light material with rare earth metal ions, including europium (Eu), dysprosium (Dy), samarium (Sm), and holmium (Ho), the material's properties can be controlled by adjusting color and defects while maintaining its excellent negative thermal quenching effect.

[0008] Another objective of this invention is to provide a method for preparing halide perovskite luminescent materials with a negative thermal quenching effect.

[0009] Another object of the present invention is to provide an application of halide perovskite luminescent materials with negative thermal quenching effect in the display field.

[0010] Another object of the present invention is to provide a white LED.

[0011] The above-mentioned objective of this invention is achieved through the following technical solution:

[0012] A halide perovskite luminescent material with a negative thermal quenching effect, having the chemical formula Cs2NaTbCl6:xM 3+ , where 0 ≤ x ≤ 0.4, and M is any one of Eu, Dy, Sm or Ho.

[0013] The halide perovskite luminescent material of the present invention can be an undoped halide perovskite green light material Cs2NaTbCl6, a rare-earth-based double perovskite luminescent material exhibiting negative thermal quenching properties, which can maintain 158% of its luminescence intensity at room temperature at a temperature of 152 °C, preferably solving the problem of poor thermal quenching performance of conventional perovskite materials under high-temperature conditions, and having good thermal stability, providing more possibilities for the application of perovskite materials in the fields of lighting and display.

[0014] The halide perovskite luminescent material of the present invention also includes Cs2NaTbCl6:xM modified by doping rare-earth metal ions 3+ , and the doped rare-earth elements can be europium (Eu), dysprosium (Dy), samarium (Sm) and holmium (Ho). Taking the doping of Eu 3+ as an example, not only can accurate color regulation be achieved, but good negative thermal quenching properties can still be maintained after doping Eu 3+ (its chemical formula is Cs2NaTbCl6:xEu 3+ , where 0 < x ≤ 0.4), and 117% of its luminescence intensity at room temperature can be maintained at a temperature of 152 °C, providing more possibilities for accurately regulating the defects of the Cs2NaTbCl6 matrix.

[0015] Preferably, the halide perovskite green light material Cs2NaTbCl6 emits green light under ultraviolet light excitation at 378 nm, with its main peak located at 547 nm and the full width at half maximum being 7.01 nm.

[0016] Preferably, for the halide perovskite luminescent material Cs2NaTbCl6:xEu 3+ , where 0 < x ≤ 0.4, after doping with Eu 3+ , the halide perovskite luminescent material has its main peak located at 593 nm under ultraviolet light excitation at 378 nm, and the full width at half maximum is only 2.29 nm. Color regulation from green light to red light can be achieved by controlling the doping concentration of Eu.

[0017] The rare-earth-based double perovskite Cs₂NaTbCl₆ of this invention exhibits superior thermal stability compared to existing technologies, and possesses unique negative thermal quenching characteristics within a certain temperature range; that is, the luminescence intensity of the material gradually increases with increasing temperature. The luminescence intensity reaches its maximum at 152°C, where the integrated intensity of the emission spectrum is 158% of that at room temperature. The luminescence intensity gradually decreases with further temperature increases, but it still maintains approximately 130% of the room temperature luminescence intensity at 227°C, demonstrating excellent negative thermal quenching characteristics.

[0018] Furthermore, Cs2NaTbCl6 doped with Eu 3+ Subsequently, it retains the original negative thermal quenching characteristics of the matrix within a certain temperature range. The luminous intensity of the material reaches its maximum at 102℃, with the integrated intensity of the emission spectrum at this temperature being 136% of that at room temperature. The luminous intensity gradually decreases with increasing temperature thereafter, but at the highest operating temperature of 152℃ for white LED devices, it still maintains approximately 117% of the luminous intensity at room temperature, thus still exhibiting excellent negative thermal quenching characteristics.

[0019] This invention also specifically protects a method for preparing a halide perovskite luminescent material with a negative thermal quenching effect, comprising the following steps:

[0020] The terbium-containing compound, the cesium-containing compound, the sodium-containing compound, and the M-containing compound were weighed according to stoichiometric ratios, dissolved in concentrated hydrochloric acid solution, and reacted completely. After cooling to room temperature, the target product Cs₂NaTbCl₆:xM was obtained. 3+ Where 0≤x≤0.4, M is any one of Eu, Dy, Sm or Ho, the reaction temperature is 100~300℃, and the time is 5~30h.

[0021] Preferably, the reaction temperature is 180°C and the reaction time is 8–12 h.

[0022] Preferably, the cooling rate is 0.5 to 6 °C / h.

[0023] The cooling rate has a significant impact on crystal size and quality. If the cooling rate is too fast, the solution will rapidly move from the metastable region to the unstable region, causing new crystal nuclei to form quickly, leading to phenomena such as twinning and surface stacking. Generally speaking, the slower the cooling rate, the larger the grain size and the higher the crystal transparency. The preferred cooling rate is 2–4 °C / h.

[0024] In specific embodiments, the terbium-containing compounds of the present invention include one or more of the following: terbium-containing carbonates, terbium-containing chlorides, terbium-containing nitrates, terbium-containing oxides, and terbium-containing acetates.

[0025] In specific embodiments, the cesium-containing compounds of the present invention include one or more of cesium-containing carbonates, cesium-containing chlorides, cesium-containing nitrates, and cesium-containing acetates.

[0026] In specific embodiments, the sodium-containing compounds of the present invention include one or more of sodium-containing carbonates, sodium-containing chlorides, sodium-containing nitrates, sodium-containing oxides, and sodium-containing acetates.

[0027] In specific embodiments, the europium-containing compounds of the present invention include one or more of europium-containing carbonates, europium-containing chlorides, europium-containing nitrates, europium-containing oxides, and europium-containing acetates.

[0028] In specific embodiments, the dysprosium-containing compounds of the present invention include one or more of the following: dysprosium-containing carbonates, dysprosium-containing chlorides, dysprosium-containing nitrates, dysprosium-containing oxides, and dysprosium-containing acetates.

[0029] In specific embodiments, the samarium-containing compounds of the present invention include one or more of samarium-containing carbonates, samarium-containing chlorides, samarium-containing nitrates, samarium-containing oxides, and samarium-containing acetates.

[0030] In specific embodiments, the holmium-containing compounds of the present invention include one or more of holmium-containing carbonates, holmium-containing chlorides, holmium-containing nitrates, holmium-containing oxides, and holmium-containing acetates.

[0031] This invention also specifically protects the application of a halide perovskite luminescent material with a negative thermal quenching effect in the display field.

[0032] This invention also specifically protects the application of halide perovskite luminescent materials with negative thermal quenching effects obtained by rare earth element doping in the display field.

[0033] The present invention also specifically protects a white LED, wherein the light-emitting material of the white LED includes the halide perovskite green light material with negative thermal quenching effect and a light-emitting material that can emit different colors of light and has negative thermal quenching effect or insignificant thermal quenching effect by rare earth ion doping of the halide perovskite material.

[0034] The halide perovskite green light material of the present invention, exhibiting a negative thermal quenching effect, is not only made from inexpensive and readily available raw materials, but also has a simple preparation method, making it easy to achieve industrial-scale production and application. Due to its very narrow emission band, this material has a high green light emission color rendering index, and can be widely used in white LED and display fields.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] The halide perovskite green light material of the present invention, which exhibits a negative thermal quenching effect, can still maintain good luminescence performance under high temperature conditions. At a temperature of 152°C, it can maintain 158% of its room temperature luminescence intensity, and at 227°C, it can still maintain about 130% of its room temperature luminescence intensity. It has excellent thermal stability and negative thermal quenching characteristics. Furthermore, by doping other rare earth elements into the matrix of this halide perovskite green light material, color control is achieved while maintaining the original negative thermal quenching characteristics of the matrix, thus effectively solving the problems of significant thermal quenching and poor thermal stability of previous perovskite materials under high temperature conditions.

[0037] Halide perovskite green light-emitting materials, when excited by 378nm ultraviolet light, can produce bright green light emission, with a main peak at 547nm and a full width at half maximum (FWHM) of only 7.01nm. Rare-earth element-doped halide perovskite red light-emitting materials, when excited by 378nm ultraviolet light, can produce bright red light emission, with a main peak at 593nm and a FWHM of only 2.29nm. Both materials have very narrow emission bands and high color rendering indices for green and red light emission, making them widely applicable in white LED and display fields. Attached Figure Description

[0038] Figure 1 The X-ray powder diffraction pattern of Cs2NaTbCl6 described in Example 1 is shown.

[0039] Figure 2 The fluorescence excitation and emission spectra of Cs2NaTbCl6 described in Example 2 are shown.

[0040] Figure 3 The temperature-dependent emission spectrum and intensity integral spectrum of the emitted light of Cs2NaTbCl6 described in Example 2 are shown.

[0041] Figure 4 The thermogravimetric analysis curve of Cs2NaTbCl6 described in Example 3.

[0042] Figure 5 The Cs2NaTbCl6:0.2Eu mixture described in Example 12 3+ The temperature-dependent emission spectrum and the intensity integral spectrum of the emitted light. Detailed Implementation

[0043] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased reagents.

[0044] Example 1

[0045] A halide perovskite green light material with negative thermal quenching effect, with the chemical formula Cs2NaTbCl6.

[0046] The preparation method of the halide perovskite green light material in Example 1 is as follows:

[0047] According to the elemental molar ratio Cs:Na:Tb=2:1:1, the raw materials were weighed separately, namely cesium chloride, sodium chloride, and terbium chloride hexahydrate.

[0048] Dissolve the above reaction raw materials in 1 mL of 12 mol·L⁻¹ -1 The concentrated hydrochloric acid solution was placed into a 10 mL stainless steel high-pressure reactor, and then the reactor was heated to 180°C and held for 8 hours. After the reaction was completed, the reactor was cooled to room temperature at a rate of 4°C / h.

[0049] Finally, the product was filtered and washed repeatedly with anhydrous ethanol to remove any possible residual reactants or impurities. The product was then dried in a 70°C oven for 8 hours to obtain the target product Cs2NaTbCl6. After grinding evenly, the product was obtained.

[0050] Example 2

[0051] A halide perovskite green light material with negative thermal quenching effect, with the chemical formula Cs2NaTbCl6.

[0052] The preparation method of the halide perovskite green light material in Example 2 is as follows:

[0053] According to the elemental molar ratio Cs:Na:Tb=2:1:1, the raw materials were weighed separately, namely cesium chloride, sodium chloride, and terbium heptaoxide.

[0054] Dissolve the above reaction raw materials in 1 mL of 12 mol·L⁻¹ -1 The concentrated hydrochloric acid solution was placed into a 10 mL stainless steel high-pressure reactor, and then the reactor was heated to 180°C and held for 8 hours. After the reaction was completed, the temperature was lowered to room temperature at a rate of 4°C / h.

[0055] Finally, the product was filtered and washed repeatedly with anhydrous ethanol to remove any possible residual reactants or impurities. The product was then dried in a 70°C oven for 8 hours to obtain the target product Cs2NaTbCl6. After grinding evenly, the product was obtained.

[0056] Example 3

[0057] A halide perovskite green light material with negative thermal quenching effect, with the chemical formula Cs2NaTbCl6.

[0058] The preparation method of the halide perovskite green light material in Example 3 is as follows:

[0059] According to the elemental molar ratio Cs:Na:Tb=2:1:1, the raw materials were weighed separately, namely cesium carbonate, sodium chloride, and terbium chloride hexahydrate.

[0060] Dissolve the above reaction raw materials in 1 mL of 12 mol·L⁻¹ -1 The concentrated hydrochloric acid solution was placed into a 10 mL stainless steel high-pressure reactor, and then the reactor was heated to 180°C and held for 8 hours. After the reaction was completed, the temperature was lowered to room temperature at a rate of 4°C / h.

[0061] Finally, the product was filtered and washed repeatedly with anhydrous ethanol to remove any possible residual reactants or impurities. The product was then dried in a 70°C oven for 8 hours to obtain the target product Cs2NaTbCl6. After grinding evenly, the product was obtained.

[0062] Example 4

[0063] A halide perovskite green light material with negative thermal quenching effect, with the chemical formula Cs2NaTbCl6.

[0064] The preparation method of the halide perovskite green light material in Example 4 is as follows:

[0065] According to the elemental molar ratio Cs:Na:Tb=2:1:1, the raw materials were weighed separately, namely cesium carbonate, sodium chloride, and terbium heptaoxide.

[0066] Dissolve the above reaction raw materials in 1 mL of 12 mol·L⁻¹ -1 The concentrated hydrochloric acid solution was placed into a 10 mL stainless steel high-pressure reactor, and then the reactor was heated to 180°C and held for 8 hours. After the reaction was completed, the temperature was lowered to room temperature at a rate of 4°C / h.

[0067] Finally, the product was filtered and washed repeatedly with anhydrous ethanol to remove any possible residual reactants or impurities. The product was then dried in a 70°C oven for 8 hours to obtain the target product Cs2NaTbCl6. After grinding evenly, the product was obtained.

[0068] Example 5

[0069] A halide perovskite red light material with negative thermal quenching effect, chemical formula Cs₂NaTbCl₆:0.1Eu 3+ .

[0070] The preparation method of the halide perovskite green light material in Example 5 is as follows:

[0071] According to the elemental molar ratio Cs:Na:Tb:Eu=2:1:0.9:0.1, the raw materials were weighed separately, namely cesium carbonate, sodium chloride, terbium chloride hexahydrate, and europium chloride hexahydrate.

[0072] Dissolve the above reaction raw materials in 1 mL of 12 mol·L⁻¹ -1 The concentrated hydrochloric acid solution was placed into a 10 mL stainless steel high-pressure reactor, and then the reactor was heated to 180°C and held for 8 hours. After the reaction was completed, the temperature was lowered to room temperature at a rate of 4°C / h.

[0073] Finally, the product was filtered and repeatedly washed with anhydrous ethanol to remove any possible residual reactants or impurities. The product was then dried in a 70°C oven for 8 hours to obtain the target product Cs₂NaTbCl₆:0.1Eu. 3+ Grind evenly to obtain the product.

[0074] Example 6

[0075] A halide perovskite red light material with negative thermal quenching effect, chemical formula Cs₂NaTbCl₆:0.1Eu 3+ .

[0076] The preparation method of the halide perovskite green light material in Example 6 is as follows:

[0077] According to the elemental molar ratio Cs:Na:Tb:Eu=2:1:0.9:0.1, the raw materials were weighed separately, namely cesium carbonate, sodium chloride, terbium chloride hexahydrate, and europium oxide.

[0078] Dissolve the above reaction raw materials in 1 mL of 12 mol·L⁻¹ -1 The concentrated hydrochloric acid solution was placed into a 10 mL stainless steel high-pressure reactor, and then the reactor was heated to 180°C and held for 8 hours. After the reaction was completed, the temperature was lowered to room temperature at a rate of 4°C / h.

[0079] Example 7

[0080] A halide perovskite red light material with negative thermal quenching effect, chemical formula Cs₂NaTbCl₆:0.1Eu 3+ .

[0081] The preparation method of the halide perovskite green light material in Example 7 is as follows:

[0082] According to the elemental molar ratio Cs:Na:Tb:Eu=2:1:0.9:0.1, the raw materials were weighed separately, namely cesium chloride, sodium chloride, terbium tetroxide, and europium chloride hexahydrate.

[0083] Dissolve the above reaction raw materials in 1 mL of 12 mol·L⁻¹ -1 A concentrated hydrochloric acid solution was added to a 10 mL stainless steel-shelled polytetrafluoroethylene autoclave. The autoclave was then heated to 180°C and held for 8 hours. After the reaction was completed, the temperature was lowered to room temperature at a rate of 4°C / h.

[0084] Example 8

[0085] A halide perovskite red light material with negative thermal quenching effect, chemical formula Cs₂NaTbCl₆:0.1Eu 3+ .

[0086] The preparation method of the halide perovskite green light material in Example 8 is as follows:

[0087] According to the elemental molar ratio Cs:Na:Tb:Eu=2:1:0.9:0.1, the raw materials were weighed separately, namely cesium chloride, sodium chloride, terbium tetroxide, and europium oxide.

[0088] Dissolve the above reaction raw materials in 1 mL of 12 mol·L⁻¹ -1 A concentrated hydrochloric acid solution was added to a 10 mL stainless steel-shelled polytetrafluoroethylene autoclave. The autoclave was then heated to 180°C and held for 8 hours. After the reaction was completed, the temperature was lowered to room temperature at a rate of 4°C / h.

[0089] Example 9

[0090] A halide perovskite red light material with negative thermal quenching effect, chemical formula Cs₂NaTbCl₆:0.2Eu 3+ .

[0091] The preparation method of the halide perovskite green light material in Example 9 is as follows:

[0092] According to the elemental molar ratio Cs:Na:Tb:Eu=2:1:0.8:0.2, the raw materials were weighed separately, namely cesium carbonate, sodium chloride, terbium chloride hexahydrate, and europium chloride hexahydrate.

[0093] Dissolve the above reaction raw materials in 1 mL of 12 mol·L⁻¹ -1 The concentrated hydrochloric acid solution was placed into a 10 mL stainless steel high-pressure reactor, and then the reactor was heated to 180°C and held for 8 hours. After the reaction was completed, the temperature was lowered to room temperature at a rate of 4°C / h.

[0094] Finally, the product was filtered and repeatedly washed with anhydrous ethanol to remove any possible residual reactants or impurities. The product was then dried in a 70°C oven for 8 hours to obtain the target product Cs₂NaTbCl₆:0.2Eu. 3+ Grind evenly to obtain the product.

[0095] Example 10

[0096] A halide perovskite red light material with negative thermal quenching effect, chemical formula Cs₂NaTbCl₆:0.2Eu 3+ .

[0097] The preparation method of the halide perovskite green light material in Example 10 is as follows:

[0098] According to the elemental molar ratio Cs:Na:Tb:Eu=2:1:0.8:0.2, the raw materials were weighed separately, namely cesium carbonate, sodium chloride, terbium chloride hexahydrate, and europium oxide.

[0099] Dissolve the above reaction raw materials in 1 mL of 12 mol·L⁻¹ -1 The concentrated hydrochloric acid solution was placed into a 10 mL stainless steel high-pressure reactor, and then the reactor was heated to 180°C and held for 8 hours. After the reaction was completed, the temperature was lowered to room temperature at a rate of 4°C / h.

[0100] Finally, the product was filtered and repeatedly washed with anhydrous ethanol to remove any possible residual reactants or impurities. The product was then dried in a 70°C oven for 8 hours to obtain the target product Cs₂NaTbCl₆:0.2Eu. 3+ Grind evenly to obtain the product.

[0101] Example 11

[0102] A halide perovskite red light material with negative thermal quenching effect, chemical formula Cs₂NaTbCl₆:0.2Eu 3+ .

[0103] The preparation method of the halide perovskite green light material in Example 11 is as follows:

[0104] According to the elemental molar ratio Cs:Na:Tb:Eu=2:1:0.8:0.2, the raw materials were weighed separately, namely cesium chloride, sodium chloride, terbium chloride hexahydrate, and europium chloride hexahydrate.

[0105] Dissolve the above reaction raw materials in 1 mL of 12 mol·L⁻¹ -1 The concentrated hydrochloric acid solution was placed into a 10 mL stainless steel high-pressure reactor, and then the reactor was heated to 180°C and held for 8 hours. After the reaction was completed, the temperature was lowered to room temperature at a rate of 4°C / h.

[0106] Finally, the product was filtered and repeatedly washed with anhydrous ethanol to remove any possible residual reactants or impurities. The product was then dried in a 70°C oven for 8 hours to obtain the target product Cs₂NaTbCl₆:0.2Eu. 3+ Grind evenly to obtain the product.

[0107] Example 12

[0108] A halide perovskite red light material with negative thermal quenching effect, chemical formula Cs₂NaTbCl₆:0.2Eu 3+ .

[0109] The preparation method of the halide perovskite green light material in Example 12 is as follows:

[0110] According to the elemental molar ratio Cs:Na:Tb:Eu=2:1:0.8:0.2, the raw materials were weighed separately, namely cesium chloride, sodium chloride, terbium heptaoxide, and europium oxide.

[0111] Dissolve the above reaction raw materials in 1 mL of 12 mol·L⁻¹ -1 The concentrated hydrochloric acid solution was placed into a 10 mL stainless steel high-pressure reactor, and then the reactor was heated to 180°C and held for 8 hours. After the reaction was completed, the temperature was lowered to room temperature at a rate of 4°C / h.

[0112] Finally, the product was filtered and repeatedly washed with anhydrous ethanol to remove any possible residual reactants or impurities. The product was then dried in a 70°C oven for 8 hours to obtain the target product Cs₂NaTbCl₆:0.2Eu. 3+ Grind evenly to obtain the product.

[0113] Comparative Example 1

[0114] A sodium-doped metal halide perovskite luminescent material with high fluorescence efficiency is disclosed. This perovskite luminescent material is a sodium-doped Cs₂AgInCl₆ perovskite material with the chemical formula Cs₂Ag. 0.54 Na 0.46 Cl6.

[0115] The preparation method of sodium-doped perovskite luminescent materials is carried out according to the following steps:

[0116] Step 1: First, dissolve a mixture of 2 mmol anhydrous indium chloride and 4 mmol cesium chloride in 10 mL of 12 mol·L⁻¹ solution. -1 In concentrated hydrochloric acid, a precursor solution is formed;

[0117] Step 2: Then add 2x mmol (0≤x≤1) silver chloride and (2-2x) mol sodium chloride, and heat the solution in a stainless steel hydrothermal reactor at 180°C for 12 h;

[0118] Step 3: The solution was slowly and steadily cooled to 50℃ at a cooling rate of 10℃ / h, and then held at 50℃ for 6h to promote crystal growth. The prepared crystals were then filtered out, washed with isopropanol, and dried overnight in an oven at 60℃ to obtain sodium-doped metal halide perovskite luminescent materials with high fluorescence efficiency.

[0119] Result detection

[0120] The X-ray powder diffraction results of the halide perovskite green light material obtained in Example 1 are as follows: Figure 1 As shown in the figure, except for the diffraction peak of NaCl, all other peaks match the peaks on the standard card, indicating that the target product has been obtained.

[0121] Figure 2 The figures show the fluorescence excitation and emission spectra of the halide perovskite green light material obtained in Example 2. As can be seen from the figures, under 378 nm ultraviolet light excitation, this halide perovskite green light material can produce bright green light emission, with its main peak located at 547 nm and a full width at half maximum (FWHM) of only 7.01 nm. Measuring the excitation spectrum at the strongest emission at 547 nm reveals a broadband excitation peak at 287 nm and a narrow band excitation peak with a 4f-4f transition at 378 nm.

[0122] Figure 3 The figures show the temperature-varying emission spectrum and integrated intensity spectrum of the halide perovskite green light material obtained in Example 2. As can be seen from the figures, the emission intensity of this material under 378 nm ultraviolet light excitation exhibits a trend of first increasing and then decreasing with increasing temperature, demonstrating excellent negative thermal quenching characteristics.

[0123] To more intuitively illustrate the relationship between the emitted light intensity and temperature of this substance, the integral value of the emitted light intensity under 378 nm ultraviolet light excitation was plotted as a function of temperature. Figure 3 See attached figure. As can be seen from the figure, this type of perovskite luminescent material exhibits excellent negative thermal quenching characteristics within a certain temperature range; that is, the luminescence intensity of the material gradually increases with increasing temperature. The luminescence intensity reaches its maximum at 152℃, where the integrated intensity of the emission spectrum is 158% of that at room temperature. Thereafter, the luminescence intensity gradually decreases with increasing temperature, but it still maintains approximately 130% of the room temperature luminescence intensity at 227℃.

[0124] The Cs2NaTbCl6 synthesized in Examples 1, 3 and 4 also possess the above-mentioned properties.

[0125] Figure 4 The thermogravimetric analysis curves of the halide perovskite green light material obtained in Example 3 are shown in the figure. As can be seen from the figure, this halide perovskite green light material exhibits good thermal stability, with a decomposition temperature as high as 788.4℃.

[0126] Figure 5 Eu obtained in Example 12 3+ Temperature-dependent emission spectra and integrated intensity diagrams of the emitted light from the doped halide perovskite red light material are shown. The figures reveal that the emission intensity under 378 nm ultraviolet excitation exhibits a trend of first increasing and then decreasing with increasing temperature, demonstrating negative thermal quenching characteristics.

[0127] To more intuitively illustrate the relationship between the emitted light intensity and temperature of this substance, the integral value of the emitted light intensity under 378 nm ultraviolet light excitation was plotted as a function of temperature. Figure 5 See attached figure. As can be seen from the figure, this type of perovskite luminescent material exhibits excellent negative thermal quenching characteristics within a certain temperature range; that is, the luminescence intensity of the material gradually increases with increasing temperature. The luminescence intensity reaches its maximum at 102℃, where the integrated intensity of the emission spectrum is approximately 136% of that at room temperature. Thereafter, the luminescence intensity gradually decreases with increasing temperature, but it still maintains approximately 117% of the room temperature luminescence intensity at 152℃.

[0128] Eu synthesized in Examples 5, 6, 7, 8, 9, 10 and 11 3+ Doped halide perovskite red light materials also possess the aforementioned properties.

[0129] This excellent thermal stability and negative thermal quenching property were not observed in the perovskite luminescent material of Comparative Example 1. The Cs2AgInCl6 perovskite material synthesized in Comparative Example 1 exhibited obvious thermal quenching properties, meaning that the luminescence intensity of the material gradually decreased with increasing temperature. Such thermal quenching properties hinder the large-scale application of most perovskite luminescent materials in the fields of lighting and display.

[0130] The test results show that the halide perovskite green light material Cs2NaTbCl6 and Eu of the present invention 3+ Doped halide perovskite red light-emitting materials are all rare-earth-based double perovskite luminescent materials exhibiting negative thermal quenching properties, maintaining good luminescence performance even at high temperatures. The halide perovskite green light-emitting material Cs₂NaTbCl₆ shows an integrated intensity of 158% of its room-temperature emission spectrum at 152℃, with a decomposition temperature as high as 788.4℃; while Eu… 3+The luminescence intensity of the doped halide perovskite red light material reaches the maximum at 102 °C, and the integrated intensity of the emission spectrum is about 136% of that at room temperature. Therefore, the present invention preferably solves the problems of significant thermal quenching and poor thermal stability of conventional perovskite materials under high-temperature conditions, and provides more possibilities for the application of perovskite materials in the fields of lighting and display.

[0131] The halide perovskite green light material Cs2NaTbCl6 of the present invention generates green light emission under the excitation of ultraviolet light at 378 nm, with its main peak located at 547 nm and the full width at half maximum being 7.01 nm; the halide perovskite red light material Cs2NaTbCl6:xEu 3+ (0 < x ≤ 0.4) of the present invention generates red light emission under the excitation of ultraviolet light at 378 nm, with its main peak located at 593 nm and the full width at half maximum being only 2.29 nm. The emission bands of both materials are very narrow, and the green and red lights emitted by them have high color rendering indices, and can be widely applied in white LEDs and the display field.

[0132] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or alterations can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A halide perovskite luminescent material with a negative thermal quenching effect, characterized in that, The chemical formula of the halide perovskite luminescent material is Cs₂NaTbCl₆. x M 3+ , where 0 ≤ x ≤ 0.4, M is Eu; The preparation method of the halide perovskite luminescent material includes the following steps: The terbium-containing compound, the cesium-containing compound, the sodium-containing compound, and the M-containing compound were weighed according to the stoichiometric ratio, dissolved in concentrated hydrochloric acid solution and reacted completely. The mixture was then cooled to room temperature to obtain the halide perovskite luminescent material. The reaction temperature was 180°C and the reaction time was 8 hours. The cooling rate is 4°C / h; The concentration of the concentrated hydrochloric acid is 12 mol / L; the amount of concentrated hydrochloric acid used is 1 mL.

2. The halide perovskite luminescent material with negative thermal quenching effect as described in claim 1, characterized in that, x = 0。 3. The halide perovskite luminescent material with negative thermal quenching effect as described in claim 1, characterized in that, The terbium-containing compound is one or more of the following: terbium-containing carbonates, terbium-containing chlorides, terbium-containing nitrates, terbium-containing oxides, and terbium-containing acetates. 4.The halide perovskite light-emitting material with negative thermal quenching effect according to claim 1, wherein the halide perovskite light-emitting material is represented by the following formula: The cesium-containing compound is one or more of the following: cesium-containing carbonates, cesium-containing chlorides, cesium-containing nitrates, and cesium-containing acetates. The sodium-containing compound is one or more of the following: sodium-containing carbonates, sodium-containing chlorides, sodium-containing nitrates, sodium-containing oxides, and sodium-containing acetates. ​ 5.The halide perovskite light-emitting material with negative thermal quenching effect according to claim 1, wherein the halide perovskite light-emitting material is represented by the following formula: The M-containing compound is one or more of europium-containing carbonates, europium-containing chlorides, europium-containing nitrates, europium-containing oxides, and europium-containing acetates. ​ 6. The application of a halide perovskite luminescent material with negative thermal quenching effect as described in claim 1 or 2 in the display field.

7. A white light LED, characterized by The light-emitting material of the white LED includes the halide perovskite light-emitting material with negative thermal quenching effect as described in claim 1 or 2.

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