Thermally quenched luminescent crystal and preparation method and application thereof

Abstract

This invention relates to the field of luminescent materials technology, and more particularly to a heat-quench-resistant luminescent crystal, its preparation method, and its applications. Its chemical formula is (C6H8N)MnCl3·2H2O, and at room temperature, it belongs to the monoclinic crystal system with space group [missing information]. C2 / c The unit cell parameters are a =17.4278±0.0003Å, b =7.6222±0.0002Å, c =17.2350±0.0004Å, α = γ =90°, β =90.160±0.002°, V =2289.46±0.09Å 3 , Z =8. Its preparation method is simple, mild, low-cost, and highly controllable. Compared with traditional manganese-based halide crystals, it exhibits minimal luminescence decay and significantly improved luminescence stability at high temperatures. Simultaneously, it boasts high luminescence efficiency and excellent color purity, effectively overcoming the high-temperature luminescence failure defects of traditional materials. It can be applied in optoelectronic fields such as solid-state lighting, high-temperature photoelectric detection, optical sensing, and fluorescent anti-counterfeiting. It can maintain stable luminescence output over a wide temperature range, exhibiting outstanding resistance to thermal quenching, effectively compensating for the limitations of traditional manganese-based luminescent crystals in high-temperature applications, and is suitable for various optoelectronic functional device applications under high-temperature conditions.

Description

Technical Field

[0001] This invention relates to the field of luminescent materials technology, and in particular to a heat-resistant quenching luminescent crystal, its preparation method, and its application. Background Technology

[0002] Thermally quenched luminescent crystals are functional crystals that maintain high luminous efficiency even at high temperatures. They are optical materials with significant application value in fields such as solid-state lighting, high-temperature fluorescence sensing, and laser gain media. Thermal quenching refers to the phenomenon where, as the temperature rises, the excited-state energy of a luminescent material is dissipated through non-radiative relaxation due to intensified lattice vibrations, resulting in a sharp decrease in luminous intensity. Only crystals with low electron-phonon coupling strength, high structural rigidity, or effective energy compensation mechanisms can exhibit excellent thermal quenching resistance. Thermally quenched crystals can maintain stable luminous output over a wide temperature range, thus ensuring the reliable operation of optoelectronic devices under high-temperature conditions. They are of great value in applications such as high-temperature lighting, laser phosphor converters, and high-power LEDs.

[0003] Compared with traditional organic-inorganic hybrid metal halides, Mn-based metal halides have advantages such as simple preparation processes, high efficiency, low toxicity, and low cost. This makes Mn-based metal halides... 2+ Organic-inorganic hybrid metal halide materials with metal cations have been extensively studied.

[0004] However, there are currently no reports or patent applications of (C6H8N)MnCl3·2H2O single crystals in the field of luminescence for their resistance to thermal quenching. Therefore, the existing technology needs improvement. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a heat-resistant quenching luminescent crystal, its preparation method and application, and to provide a new material with excellent comprehensive performance and heat-resistant quenching luminescent crystal.

[0006] The technical solution of the present invention is as follows: In a first aspect, the present invention provides a heat-resistant quenching luminescent crystal with the chemical formula (C6H8N)MnCl3·2H2O.

[0007] Optionally, the heat-resistant quenching luminescent crystal belongs to the monoclinic crystal system and has a space group of C2 / c The unit cell parameters are a =17.4278±0.0003Å, b =7.6222±0.0002Å, c =17.2350±0.0004Å, α=γ =90°, β =90.160±0.002°, V=2289.46±0.09Å 3 , Z =8.

[0008] Secondly, the present invention provides a method for preparing a heat-resistant quenching luminescent crystal, comprising the following steps: Add manganese chloride to water and stir until the solution becomes clear; Add HCl solution and stir again until the solution becomes clear; Add 2-methylpyridine solution, stir and heat to 75-85℃ until a light yellow clear solution is obtained; The temperature is lowered to 30-40℃, and the crystals are evaporated and crystallized. The resulting crystals are heat-resistant quenching luminescent crystals.

[0009] Optionally, the molar ratio of manganese chloride, HCl in the HCl solution, and 2-methylpyridine in the 2-methylpyridine solution is 1:2:1-2.

[0010] Optionally, the mass concentration of HCl in the HCl solution is 36%-38%.

[0011] Optionally, the mass concentration of 2-methylpyridine in the 2-methylpyridine solution is ≥99%.

[0012] Thirdly, the present invention provides an application of the heat-resistant quenching luminescent crystal in optoelectronic devices.

[0013] Fourthly, the present invention provides an optoelectronic device, including the heat-resistant quenching light-emitting crystal.

[0014] Optionally, the optoelectronic device includes at least one of the following: an illumination device, a photodetector, an optical sensor, an anti-counterfeiting device, and a nonlinear optical device.

[0015] Beneficial Effects: This invention provides a heat-quenching luminescent crystal, its preparation method, and its application. This invention is the first to provide a heat-quenching luminescent crystal with the chemical formula (C6H8N)MnCl3·2H2O. At room temperature, it belongs to the monoclinic crystal system with space group [missing information]. C2 / c The unit cell parameters are a =17.4278(3)Å, b =7.6222(2)Å, c =17.2350(4)Å, α=γ =90°, β =90.160(2)°, V =2289.46(9)Å 3 , Z=8. Its preparation method is simple and mild, low in cost and highly controllable. It can be obtained by simply using a solvent evaporation method. Moreover, the obtained single crystals have few defects, high crystal quality, and excellent structural and chemical stability, making them suitable for subsequent processing and long-term use.

[0016] This heat-quenching luminescent crystal possesses excellent heat-quenching luminescence properties. Compared to traditional manganese-based halide crystals, it exhibits minimal luminescence decay and significantly improved luminescence stability at high temperatures. Simultaneously, it boasts high luminescence efficiency and excellent color purity, effectively overcoming the high-temperature luminescence failure defects of traditional materials. It can be applied in optoelectronic fields such as solid-state lighting, high-temperature photoelectric detection, optical sensing, and fluorescent anti-counterfeiting. This heat-quenching luminescent crystal features an organic-inorganic hybrid coordination structure, exhibiting regular and stable structure and excellent luminescence thermal stability. It can maintain stable luminescence output over a wide temperature range, demonstrating outstanding heat-quenching resistance. This effectively compensates for the limitations of traditional manganese-based luminescent crystals in high-temperature applications, making it suitable for various optoelectronic functional device applications under high-temperature conditions. Attached Figure Description

[0017] Figure 1 This is a single-cell crystal structure diagram of the heat-resistant quenching luminescent crystal of Embodiment 1 of the present invention.

[0018] Figure 2 This is a crystal structure diagram of the heat-resistant quenching luminescent crystal of Embodiment 1 of the present invention.

[0019] Figure 3 The image shows a comparison between the powder X-ray diffraction test results of the crystal obtained in Example 1 of this invention and the X-ray diffraction pattern obtained from the simulation of the single crystal structure.

[0020] Figure 4 This is the room temperature excitation-emission spectrum of the heat-resistant quenching luminescent crystal of Embodiment 1 of the present invention.

[0021] Figure 5 This is the CIE 1931 standard chromaticity coordinate diagram of the heat-resistant quenching luminescent crystal of Embodiment 1 of the present invention.

[0022] Figure 6 The emission wavelength λ of the heat-resistant quenching luminescent crystal in Embodiment 1 of the present invention is... em Three-dimensional variable-temperature excitation spectrum at 615 nm.

[0023] Figure 7 This is the temperature-varying emission spectrum of the heat-resistant quenching luminescent crystal under 310 nm excitation according to Embodiment 1 of the present invention.

[0024] Figure 8 This is the temperature-varying emission spectrum of the heat-resistant quenching luminescent crystal under 353 nm excitation according to Embodiment 1 of the present invention.

[0025] Figure 9This is the temperature-varying emission spectrum of the heat-resistant quenching luminescent crystal under 369 nm excitation according to Embodiment 1 of the present invention.

[0026] Figure 10 This is the temperature-varying emission spectrum of the heat-resistant quenching luminescent crystal under 418 nm excitation according to Embodiment 1 of the present invention.

[0027] Figure 11 This is a TG thermogravimetric analysis curve of Embodiment 1 of the present invention. Detailed Implementation

[0028] This invention provides a heat-resistant quenching luminescent crystal, its preparation method, and its application. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0029] Currently, there are no reports on (C6H8N)MnCl3·2H2O luminescent crystals that resist thermal quenching.

[0030] Based on this, this embodiment provides a heat-resistant quenching luminescent crystal, characterized in that its chemical formula is (C6H8N)MnCl3·2H2O.

[0031] In one specific embodiment, the heat-resistant quenching luminescent crystal belongs to the monoclinic crystal system and has a space group of . C2 / c The unit cell parameters are a =17.4278±0.0003Å, b =7.6222±0.0002Å, c =17.2350±0.0004Å, α=γ =90°, β =90.160±0.002°, V =2289.46±0.09Å 3 , Z =8.

[0032] The heat-resistant quenching luminescent crystal structure obtained in this embodiment is as follows: Figure 1 , Figure 2 As shown, Figure 1 As shown, two water molecules are in the trans position, and the Mn²⁺ in the compound… + Ions and four Cl - The ion coordinates with two coordinated water molecules, and the O2—Mn1—O1 bond angle is 171.60(7)°, close to the ideal octahedron's 180°. However, because the Mn—Cl bond is significantly longer than the Mn—O bond (the difference is about 0.4 Å), the MnCl4(H2O)2 octahedron is slightly distorted. Each octahedron is connected by a Cl bond at a common vertex. - The ion is bonded to the adjacent octahedron; the organic cation is C6H8N.+ It is connected to the inorganic framework by strong N-H···Cl hydrogen bonds, which not only stabilize the crystal structure but also facilitate the directional arrangement of organic cations in the crystal lattice. According to Figure 2 It can be seen that the inorganic octahedron grows along the a direction to form a one-dimensional chain structure.

[0033] Figure 3 The results of powder X-ray diffraction tests are shown, along with X-ray diffraction patterns obtained from single-crystal structure simulations. Comparison of the two patterns reveals that the positions and intensities of the diffraction peaks are essentially identical, indicating that the obtained sample possesses high purity.

[0034] This embodiment also provides a method for preparing a heat-quenching resistant luminescent crystal, comprising the following steps: Add manganese chloride to water and stir until the solution becomes clear; Add HCl solution and stir again until the solution becomes clear; Add 2-methylpyridine solution, stir and heat to 75-85℃ until a light yellow clear solution is obtained; The temperature is lowered to 30-40℃, and the crystals are evaporated and crystallized. The resulting crystals are heat-resistant quenching luminescent crystals.

[0035] It should be noted that the stirring and heating temperature in this embodiment can be 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃, or 85℃; in this embodiment, the temperature can be lowered to 30℃, 31℃, 32℃, 33℃, 34℃, 35℃, 36℃, 37℃, 38℃, 39℃, or 40℃. This embodiment uses a simple solvent evaporation method to synthesize heat-resistant quenching luminescent crystals. The process is simple and mild, low-cost, and highly controllable. The resulting single crystals have few defects, high crystal quality, and excellent structural and chemical stability, making them suitable for subsequent processing and long-term use.

[0036] In some embodiments, the molar ratio of manganese chloride, HCl in the HCl solution, and 2-methylpyridine in the 2-methylpyridine solution is 1:2:1-2.

[0037] For example, the molar ratio of manganese chloride, HCl in the HCl solution, and 2-methylpyridine in the 2-methylpyridine solution is 1:2:1 or 1:2:2 or any ratio within the range.

[0038] In some implementations, the mass concentration of HCl in the HCl solution is 36%-38%.

[0039] For example, the mass concentration of HCl in the HCl solution is 36%, 37%, and 38%.

[0040] In some embodiments, the mass concentration of 2-methylpyridine in the 2-methylpyridine solution is ≥99%.

[0041] This embodiment also provides an application of the heat-resistant quenching luminescent crystal in optoelectronic devices.

[0042] This embodiment also provides an optoelectronic device, including the heat-resistant quenching light-emitting crystal.

[0043] In some embodiments, the optoelectronic device includes at least one of a lighting device, a photodetector, an optical sensor, an anti-counterfeiting device, and a nonlinear optical device.

[0044] It should be noted that the heat-quenching luminescent crystal material of this embodiment possesses excellent heat-quenching luminescence properties. Compared with traditional manganese-based halide crystals, its luminescence decay at high temperatures is minimal, and its luminescence stability is significantly improved. Simultaneously, it exhibits high luminescence efficiency and good color purity, effectively overcoming the defects of traditional materials in high-temperature luminescence failure. It can be applied in optoelectronic fields such as solid-state lighting, high-temperature photoelectric detection, optical sensing, and fluorescent anti-counterfeiting. This heat-quenching luminescent crystal has an organic-inorganic hybrid coordination structure, with a regular and stable structure and excellent luminescence thermal stability. It can maintain stable luminescence output over a wide temperature range, exhibiting outstanding heat-quenching resistance. This effectively compensates for the limitations of traditional manganese-based luminescent crystals in high-temperature applications, making it suitable for various optoelectronic functional device applications under high-temperature conditions.

[0045] The present invention will be further described below through specific embodiments.

[0046] Example 1 A method for preparing a heat-quenching resistant luminescent crystal includes the following steps: Weigh 2.54 g (0.02 mol) of anhydrous MnCl2 solid into a beaker using an electronic analytical balance, add 5 mL of distilled water, and stir on a magnetic stirrer until the solution is clear. Then add 3.95 g (0.04 mol) of HCl solution and stir again until the solution is clear. Finally, add 3.76 g (0.04 mol) of 2-methylpyridine solution, stir and heat at 80 °C to obtain a light yellow clear solution. Slowly evaporate and crystallize the solution at 40 °C to obtain heat-resistant quenching luminescent crystals.

[0047] Example 2 A method for preparing a heat-quenching resistant luminescent crystal includes the following steps: Weigh 2.54 g (0.02 mol) of anhydrous MnCl2 solid into a beaker using an electronic analytical balance, add 5 mL of distilled water, and stir on a magnetic stirrer until the solution is clear. Then add 3.95 g (0.04 mol) of HCl solution and stir again until the solution is clear. Finally, add 1.88 g (0.02 mol) of 2-methylpyridine solution, stir and heat at 80 °C to obtain a light yellow clear solution. Slowly evaporate and crystallize the solution at 40 °C to obtain heat-resistant quenching luminescent crystals.

[0048] Example 3 A method for preparing a heat-quenching resistant luminescent crystal includes the following steps: Weigh 2.54 g (0.02 mol) of anhydrous MnCl2 solid into a beaker using an electronic analytical balance, add 5 mL of distilled water, and stir on a magnetic stirrer until the solution is clear. Then add 3.95 g (0.04 mol) of HCl solution and stir again until the solution is clear. Finally, add 3.76 g (0.04 mol) of 2-methylpyridine solution, stir and heat at 75 °C to obtain a light yellow clear solution. Slowly evaporate and crystallize the solution at 30 °C to obtain heat-resistant quenching luminescent crystals.

[0049] Example 4 A method for preparing a heat-quenching resistant luminescent crystal includes the following steps: Weigh 2.54 g (0.02 mol) of anhydrous MnCl2 solid into a beaker using an electronic analytical balance, add 5 mL of distilled water, and stir on a magnetic stirrer until the solution is clear. Then add 3.95 g (0.04 mol) of HCl solution and stir again until the solution is clear. Finally, add 3.76 g (0.04 mol) of 2-methylpyridine solution, stir and heat at 85 °C to obtain a light yellow clear solution. Slowly evaporate and crystallize the solution at 35 °C to obtain heat-resistant quenching luminescent crystals.

[0050] Example 5 A method for preparing a heat-quenching resistant luminescent crystal includes the following steps: Weigh 2.54 g (0.02 mol) of anhydrous MnCl2 solid into a beaker using an electronic analytical balance, add 5 mL of distilled water, and stir on a magnetic stirrer until the solution is clear. Then add 3.95 g (0.04 mol) of HCl solution and stir again until the solution is clear. Finally, add 3.76 g (0.04 mol) of 2-methylpyridine solution, stir and heat at 76 °C to obtain a light yellow clear solution. Slowly evaporate and crystallize the solution at 32 °C to obtain heat-resistant quenching luminescent crystals.

[0051] Example 6 A method for preparing a heat-quenching resistant luminescent crystal includes the following steps: Weigh 2.54 g (0.02 mol) of anhydrous MnCl2 solid into a beaker using an electronic analytical balance, add 5 mL of distilled water, and stir on a magnetic stirrer until the solution is clear. Then add 3.95 g (0.04 mol) of HCl solution and stir again until the solution is clear. Finally, add 3.76 g (0.04 mol) of 2-methylpyridine solution, stir and heat at 78 °C to obtain a light yellow clear solution. Slowly evaporate and crystallize the solution at 34 °C to obtain heat-resistant quenching luminescent crystals.

[0052] Example 7 A method for preparing a heat-quenching resistant luminescent crystal includes the following steps: Weigh 2.54 g (0.02 mol) of anhydrous MnCl2 solid into a beaker using an electronic analytical balance, add 5 mL of distilled water, and stir on a magnetic stirrer until the solution is clear. Then add 3.95 g (0.04 mol) of HCl solution and stir again until the solution is clear. Finally, add 3.76 g (0.04 mol) of 2-methylpyridine solution, stir and heat at 82 °C to obtain a light yellow clear solution. Slowly evaporate and crystallize the solution at 36 °C to obtain heat-resistant quenching luminescent crystals.

[0053] Example 8 A method for preparing a heat-quenching resistant luminescent crystal includes the following steps: Weigh 2.54 g (0.02 mol) of anhydrous MnCl2 solid into a beaker using an electronic analytical balance, add 5 mL of distilled water, and stir on a magnetic stirrer until the solution is clear. Then add 3.95 g (0.04 mol) of HCl solution and stir again until the solution is clear. Finally, add 3.76 g (0.04 mol) of 2-methylpyridine solution, stir and heat at 84 °C to obtain a light yellow clear solution. Slowly evaporate and crystallize the solution at 38 °C to obtain heat-resistant quenching luminescent crystals.

[0054] The thermally quenched luminescent crystals obtained in Examples 1-8 were subjected to structural analysis using X-ray single-crystal diffraction. The single-crystal X-ray diffractometer used was a Rigaku XtaLABSynergy-R, equipped with a HyPix detector. The data collection temperature was 293 K, and the diffraction source was Cu-Kα rays (λ=1.54184 Å) with a scanning mode of ω-2θ. Data were processed using the Multi-Scan method for absorption correction. Structural analysis was performed using the SHELXTL-97 software package; and the analysis was conducted using an F-based... 2The coordinates of all atoms and anisotropic thermal parameters were refined using the full matrix least squares method. X-ray single-crystal diffraction results showed that the chemical formula of the crystals obtained in each embodiment was (C6H8N)MnCl3·2H2O, and at room temperature (293K) it belonged to the monoclinic crystal system with space group . C2 / c The unit cell parameters are a =17.4278±0.0003Å, b =7.6222±0.0002Å, c =17.2350±0.0004Å, α=γ =90°, β =90.160±0.002°, V =2289.46±0.09Å 3 , Z =8. For example... Figure 1 As shown, two water molecules are in the trans position, and the Mn²⁺ in the compound… + Ions and four Cl - The ion coordinates with two coordinated water molecules, and the O2—Mn1—O1 bond angle is 171.60(7)°, close to the ideal octahedron's 180°. However, because the Mn—Cl bond is significantly longer than the Mn—O bond (the difference is about 0.4 Å), the MnCl4(H2O)2 octahedron is slightly distorted. Each octahedron is connected by a Cl bond at a common vertex. - The ion is bonded to the adjacent octahedron; the organic cation is C6H8N. + It is connected to the inorganic framework by strong N-H···Cl hydrogen bonds, which not only stabilize the crystal structure but also facilitate the directional arrangement of organic cations in the crystal lattice. According to Figure 2 It can be seen that the inorganic octahedron grows along the a direction to form a one-dimensional chain structure.

[0055] The thermally quenched luminescent crystal obtained in Example 1 was tested using a D8 Advance diffractometer manufactured by Bruker GmbH, Germany, under the following conditions: fixed target, monochromatic light source, Cu-K. α The wavelength λ = 0.15418 nm, the scanning range is 5–50°, the scanning step size is 0.02°, and the results are as follows: Figure 3 As shown, from Figure 3 It can be seen that the powder XRD pattern is in high agreement with the standard pattern based on single-crystal structure fitting, with no extraneous impurity diffraction signals. This result fully demonstrates that the crystal prepared by this invention has a single phase, extremely high purity, and is free of impurities and amorphous impurities. The X-ray diffraction patterns of the heat-resistant quenching luminescent crystals obtained in other embodiments are consistent with those in Example 1.

[0056] The photoluminescence properties at room temperature were characterized using an FLS1000 transient fluorescence spectrometer manufactured by Edinburgh Instruments, UK. Before testing, the heat-resistant quenching luminescent crystal prepared in Example 1 was uniformly fixed onto a 1 mm non-fluorescent quartz slice and placed in the light-proof, sealed sample chamber of the spectrometer. The excitation and emission spectra were collected using the instrument's pulsed laser as an adjustable excitation source. The test results are as follows: Figure 4 As shown. Figure 4 The red curve in the figure represents the excitation spectrum measured at a fixed emission wavelength of 615 nm. The curve exhibits four distinct characteristic excitation peaks at wavelengths of 310 nm, 353 nm, 369 nm, and 418 nm, covering the deep ultraviolet, near ultraviolet, and violet light bands, indicating that the crystal can efficiently absorb light energy in this range. The other colored curves in the figure correspond to the emission spectra at each characteristic wavelength. All emission curves show a symmetrical and non-spurious red light emission peak at 615 nm. The position of the emission peak does not change with the excitation wavelength, and the luminescence intensity corresponds one-to-one with the peak height of the excitation spectrum. The red light emission intensity reaches its highest under 310 nm excitation, while the luminescence intensity of the emission curve corresponding to 450 nm blue light decreases significantly, indicating that the crystal only selectively absorbs ultraviolet-violet light. After capturing energy through multiple electron transition channels inside the material, they converge to the same luminescence center through non-radiative relaxation, ultimately radiating 615 nm red light.

[0057] Pick Figure 4 The 615nm red light emission spectrum under 310nm excitation condition was integrated and converted to obtain the CIE 1931 standard chromaticity coordinates (0.5423, 0.3553). The chromaticity characterization results are as follows: Figure 5 As shown in the diagram, the coordinate point clearly falls within the standard red light region of the CIE 1931 chromaticity diagram, far from the orange and pink light regions. An accompanying microscopic photograph of the crystal under ultraviolet light irradiation is also included, visually demonstrating the uniform and saturated red fluorescence of the sample, without any local color cast or whitening. This perfectly matches the calculated color coordinates, fully confirming the crystal's excellent red light purity. The entire test relied on a sealed sample chamber to isolate stray light from the environment and an ultra-thin quartz substrate to eliminate background fluorescence. All spectra were tested in triplicate with minimal data error, accurately reflecting the intrinsic luminescence characteristics of the crystal. The material's wide ultraviolet-violet excitation window and high monochromatic red light output make it promising for applications in ultraviolet-excited red phosphors, fluorescent anti-counterfeiting marks, high color rendering LED devices, and biological red fluorescence imaging. The room-temperature excitation-emission spectra of the crystals obtained in other embodiments are consistent with those of the crystal obtained in Example 1.

[0058] A series of variable-temperature spectral characterizations were performed using an Edinburgh Instruments FLS 1000 transient fluorescence spectrometer with a precision liquid nitrogen temperature control accessory. During testing, the heat-resistant quenching luminescent crystal obtained in Example 1 was fixed on a low-temperature dedicated non-fluorescent quartz stage, and the test temperature range of 100-360K was precisely controlled using liquid nitrogen as the coolant. The emission wavelength λ was monitored at a constant value throughout the test. em The variable-temperature excitation spectrum was collected at 615 nm, and corresponding variable-temperature emission spectra were collected at four characteristic excitation wavelengths: 310 nm, 353 nm, 369 nm, and 418 nm. The influence of temperature on the red light emission behavior and thermal quenching characteristics of the crystal was systematically investigated. The results of the variable-temperature excitation spectrum are as follows: Figure 6 As shown in the figure, the three-dimensional temperature-varying excitation spectrum clearly shows that the signal intensity of all characteristic excitation peaks at 310 nm, 353 nm, 369 nm, and 418 nm in the 100-345 K range gradually increases with increasing temperature, and the peak positions of each excitation peak do not shift significantly. This proves that increasing the temperature in the low-temperature to near-room-temperature range does not destroy the energy level absorption structure of the crystal, but rather helps to improve the light energy capture efficiency. When the test temperature exceeds 345 K, the luminescence intensity of all excitation peaks shows a synchronous decay trend, indicating that the non-radiative transition loss inside the crystal begins to intensify. 345 K is the critical temperature node for the excitation absorption performance of this crystal.

[0059] Temperature-dependent emission spectra using four types of characteristic wavelengths as excitation sources ( Figure 7 , Figure 8 , Figure 9 , Figure 10 This further verifies the excellent resistance to thermal quenching: when using 310nm deep ultraviolet excitation ( Figure 7 The 615nm red light emission peak intensity showed a significant and continuous increase in the 100-250K range, while the luminescence intensity maintained a stable plateau in the 250-330K range with no obvious thermal decay, only slowly decreasing when the temperature rose above 330K; when excited by 353nm near-ultraviolet light ( Figure 8 The 615nm emission peak showed a significant and sustained increase in intensity within the 100-345K range, only declining in intensity after 345K; under 369nm excitation conditions ( Figure 9 The red light emission intensity increases monotonically with increasing temperature, reaching a peak intensity at 345K; when excited by 418nm violet light ( Figure 10The sample still only produced a single 615nm pure red light emission peak, without the generation of any extraneous side peaks, and the luminescence brightness continued to increase in the 100–345K range. Considering all temperature-varying spectral patterns, regardless of the effective excitation source used, the red light emission intensity of this crystal maintained growth or stability within a wide temperature range of 100–345K, only experiencing thermal quenching above 345K. This indicates that the thermally quenched luminescent crystal prepared in Example 1 possesses excellent high-temperature luminescence stability, with a critical thermal quenching temperature reaching 345K (72℃). It is fully compatible with practical applications such as conventional LED devices, fluorescent anti-counterfeiting at room temperature to medium temperature, and optical sensing, effectively solving the shortcomings of most red fluorescent materials that experience severe thermal quenching near room temperature and a sharp drop in high-temperature luminescence efficiency. The entire temperature-varying test relied on a closed-loop liquid nitrogen temperature control system to achieve precise temperature gradient regulation. The sealed low-temperature sample chamber isolated external thermal radiation and stray light interference, resulting in excellent repeatability of spectral data and objectively reflecting the intrinsic temperature-varying luminescence and thermal stability characteristics of the crystal. The intrinsic temperature-dependent luminescence and thermal stability characteristics of the crystals obtained in other embodiments are consistent with those in Example 1.

[0060] The thermal stability of the heat-resistant quenching luminescent crystal ((C6H8N)MnCl3·2H2O) obtained in Example 1 was characterized using a NETZSCH STA 449 F3 simultaneous thermogravimetric-differential thermal analysis (TG-DTA) instrument. High-purity nitrogen was used throughout the test as a protective atmosphere to prevent air oxidation. The heating rate was set to 15 K / min, and the test temperature range covered 20–1000 °C (corresponding to thermodynamic temperatures of 293–1273 K). The mass change of the crystal with increasing temperature was fully recorded. The TG weight loss curve is shown below. Figure 11 As shown, the entire thermal decomposition process of the sample can be divided into four distinct temperature ranges. The first stage, the weight loss range, is from 348K to 420K. The curve steadily decreases from 100% mass, and this weight loss behavior perfectly matches the removal of two molecules of water of crystallization bound within the crystal lattice of the Z-body. 348K is the starting temperature for the water of crystallization to leave the lattice, and by 420K, all the water of crystallization has been removed. This temperature is much higher than the 345K critical temperature for thermal quenching obtained from the variable-temperature fluorescence test, proving that the crystal does not lose water of crystallization within the stable luminescence operating range, and the luminescent framework of the lattice remains intact. From the perspective of thermal decomposition, this confirms that the material possesses a stable luminescent structure at conventional operating temperatures. The second stage is from 420K to 620K, where the curve shows a significant and rapid weight loss. This stage corresponds to the organic cation (C6H8N) in the crystal. +Thermal decomposition and vaporization, accompanied by the breakage and dissociation of some inorganic coordination frameworks, represent the stage of thermal decomposition with the most significant sample mass loss. After the 420K to 620K range, the curve enters a gentle plateau, indicating that the organic components have completely decomposed and volatilized, while the remaining inorganic matrix temporarily maintains a stable structure. The third stable plateau is located between 620K and 920K, within which the sample mass remains almost unchanged, and the remaining inorganic framework exhibits good thermal inertia. The fourth weight loss range is from 920K to 1180K, where the curve shows a significant decline again, representing the continued deep decomposition of the remaining inorganic framework at high temperatures. The manganese-based coordination structure undergoes oxidation and rearrangement, gradually transforming into manganese oxides and chloride inorganic residues. When the temperature rises to 1180K, the weight loss curve tends to level off, indicating the complete decomposition of the organic-inorganic hybrid crystals, ultimately leaving only thermally stable metallic inorganic oxide products.

[0061] The combined results of temperature-varying fluorescence and thermogravimetric analysis (TG) show that the crystal's stable luminescence performance has an upper limit of safe operating temperature of 345K, while the lattice water removal initiation temperature of 348K is only slightly higher than the critical luminescence temperature. This ensures that the crystal's intrinsic luminescent structure will not be damaged within the normal operating range of devices. Simultaneously, the overall framework thermal decomposition initiation temperature is as high as 420K, and the complete decomposition temperature of the organic cations exceeds 620K. Compared to most similar organic-inorganic hybrid luminescent materials, this exhibits superior thermal stability, meeting the long-term usage requirements of low-to-medium temperature red light-emitting devices and fluorescent anti-counterfeiting applications. The entire TG test was conducted under an inert nitrogen atmosphere to avoid interference from high-temperature oxidation side reactions. The heating rate was constant and controllable, and the weight loss steps were clearly demarcated, accurately distinguishing the thermal decomposition temperature ranges corresponding to the water of crystallization, organic ligands, and inorganic framework components. This objectively reflects the crystal's stepwise thermal dissociation behavior and intrinsic thermal stability characteristics. The intrinsic thermal stability characteristics of the crystals obtained in other embodiments are consistent with those of the crystal obtained in Example 1.

[0062] In summary, this invention provides a heat-quenching luminescent crystal, its preparation method, and its application. This invention is the first to provide a heat-quenching luminescent crystal with the chemical formula (C6H8N)MnCl3·2H2O. At room temperature, it belongs to the monoclinic crystal system with space group [missing information]. C2 / c The unit cell parameters are a =17.4278(3)Å, b =7.6222(2)Å, c =17.2350(4)Å, α=γ =90°, β =90.160(2)°, V =2289.46(9)Å 3 , Z=8. Its preparation method is simple and mild, low in cost and highly controllable. It can be obtained by simply using a solvent evaporation method. Moreover, the obtained single crystals have few defects, high crystal quality, and excellent structural and chemical stability, making them suitable for subsequent processing and long-term use.

[0063] This heat-quenching luminescent crystal possesses excellent heat-quenching luminescence properties. Compared to traditional manganese-based halide crystals, it exhibits minimal luminescence decay and significantly improved luminescence stability at high temperatures. Simultaneously, it boasts high luminescence efficiency and excellent color purity, effectively overcoming the high-temperature luminescence failure defects of traditional materials. It can be applied in optoelectronic fields such as solid-state lighting, high-temperature photoelectric detection, optical sensing, and fluorescent anti-counterfeiting. This heat-quenching luminescent crystal features an organic-inorganic hybrid coordination structure, exhibiting regular and stable structure and excellent luminescence thermal stability. It can maintain stable luminescence output over a wide temperature range, demonstrating outstanding heat-quenching resistance. This effectively compensates for the limitations of traditional manganese-based luminescent crystals in high-temperature applications, making it suitable for various optoelectronic functional device applications under high-temperature conditions.

[0064] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A heat-resistant quenching luminescent crystal, characterized in that, The chemical formula is (C6H8N)MnCl3·2H2O.

2. The heat-resistant quenching luminescent crystal according to claim 1, characterized in that, The heat-resistant quenching luminescent crystal belongs to the monoclinic crystal system at room temperature, with space group [missing information]. C2 / c The unit cell parameters are a =17.4278±0.0003Å, b =7.6222±0.0002Å, c =17.2350±0.0004Å, α=γ =90°, β =90.160±0.002°, V =2289.46±0.09Å 3 , Z =8.

3. A method for preparing a heat-resistant quenching luminescent crystal as described in claim 1 or 2, characterized in that, Includes the following steps: Add manganese chloride to water and stir until the solution becomes clear; Add HCl solution and stir again until the solution becomes clear; Add 2-methylpyridine solution, stir and heat to 75-85℃ until a light yellow clear solution is obtained; The temperature is lowered to 30-40℃, and the crystals are evaporated and crystallized. The resulting crystals are heat-resistant quenching luminescent crystals.

4. The method for preparing the heat-resistant quenching luminescent crystal according to claim 3, characterized in that, The molar ratio of manganese chloride, HCl in the HCl solution, and 2-methylpyridine in the 2-methylpyridine solution is 1:2:1-2.

5. The method for preparing the heat-resistant quenching luminescent crystal according to claim 3, characterized in that, The mass concentration of HCl in the HCl solution is 36%-38%.

6. The method for preparing the heat-resistant quenching luminescent crystal according to claim 3, characterized in that, The mass concentration of 2-methylpyridine in the 2-methylpyridine solution is ≥99%.

7. The application of the heat-resistant quenching luminescent crystal as described in claim 1 or 2 in optoelectronic devices.

8. An optoelectronic device, characterized in that, Includes a heat-resistant quenching luminescent crystal as described in claim 1 or 2.

9. The optoelectronic device according to claim 8, characterized in that, The optoelectronic device includes at least one of the following: lighting device, photodetector device, optical sensor device, anti-counterfeiting device, and nonlinear optical device.

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