A copper-based fluorescent material with high quantum yield, high thermal stability and anti-thermal quenching effect and a preparation method thereof

Abstract

The present application relates to copper-based fluorescent material technical field, specifically to a kind of copper-based fluorescent material with high quantum yield, high thermal stability, anti-thermal quenching effect and preparation method thereof.Conventional copper-based TADF material is poor in anti-thermal quenching performance.In view of the above problems, the present application provides a kind of copper-based fluorescent material, which is obtained by the coordination self-assembly reaction of 1,4-bis[(2-methylimidazole-1-yl)methyl]benzene, 4-(diphenylphosphino)benzonitrile and CuI in organic solution.The copper-based fluorescent material exhibits excellent anti-thermal quenching characteristics in a wide temperature range of 80 K to 500 K.Effective to avoid the common fluorescence quenching phenomenon at high temperature, showing strong thermal stability.Can be widely used in high-power lighting, laser display, extreme environment optical devices and wide temperature range optical sensing and other key fields.

Description

Technical Field

[0001] This invention relates to the field of copper-based fluorescent materials technology, specifically to a copper-based fluorescent material with high quantum yield, high thermal stability, and resistance to thermal quenching, and its preparation method. Background Technology

[0002] In the field of optoelectronic devices such as organic light-emitting diodes (OLEDs), the performance of luminescent materials directly determines the luminous efficiency, color purity, and lifespan of the devices. Traditional fluorescent materials, limited by spin statistics, have a theoretical upper limit of only 25% for their internal quantum efficiency, making it difficult to meet the high brightness and low power consumption requirements of high-performance devices. To overcome this bottleneck, second-generation heavy metal phosphorescent materials and third-generation thermally activated delayed fluorescence (TADF) materials have been proposed. Both can theoretically achieve 100% exciton utilization, thus becoming current research hotspots in luminescent materials.

[0003] However, heavy metal phosphorescent materials, primarily based on precious metals such as iridium and platinum, face significant limitations in practical applications. On the one hand, the scarcity and high price of precious metal resources lead to high device manufacturing costs; on the other hand, the environmental pollution risks of these materials have triggered increasingly stringent regulatory pressures, restricting their widespread application in large-scale commercial products. Against this backdrop, copper (I)-based TADF materials, with their advantages of abundant copper reserves, low cost, and environmental friendliness, are considered one of the key breakthroughs for achieving efficient, low-cost, and sustainable OLED technology in the future, and are gradually becoming a strategic direction that research and industry are vying to develop.

[0004] In recent years, OLED devices have gained popularity for their superior visual quality, low power consumption, and excellent foldability. However, achieving both high efficiency and long lifespan simultaneously remains a formidable challenge in this field (see Carolina F, Giliandro F, Rene A, et al. Influence of Imidazole Substituent Bulkinesson [CuI(PPh3)). [N] Complexes with TADF Blue Solid-State Emission[J]. ACS Omega2026,11, 13425-13434). Although copper(I) complexes have made significant progress in TADF material research, existing luminescent material systems still face key technical bottlenecks: most materials struggle to achieve high brightness, long lifetime, and high thermal stability while simultaneously maintaining excellent resistance to thermal quenching. Performance degradation under high-temperature conditions and complex application environments severely restricts the practical application and expansion of these materials in high-end optoelectronic devices, extreme environment optical sensing, and other fields. Summary of the Invention

[0005] The problem with existing technologies is that conventional copper-based TADF materials have poor resistance to thermal quenching. To address the aforementioned problems, this invention provides a copper-based fluorescent material that combines high quantum yield, high thermal stability, and resistance to thermal quenching. The copper-based fluorescent material is a coordination polymer crystal, which is obtained by a coordination self-assembly reaction of 1,4-bis[(2-methylimidazol-1-yl)methyl]benzene, 4-(diphenylphosphine)benzonitrile, and CuI in an organic solution. In the coordination polymer crystal, Cu is coordinated with P, N, and I atoms, and two Cu atoms are bridged by pmib to form an infinitely extended one-dimensional chain structure with twisted connections. Its single-crystal molecular formula is: [(pmib)(4-CN-PPh2)2Cu2I2]n, where pmib is 1,4-bis[(2-methylimidazol-1-yl)methyl]benzene (CAS: 82410-79-5), and 4-CN-PPh2 is 4-(diphenylphosphine)benzonitrile (CAS No.: 5068-16-6).

[0006] Preferably, the copper-based fluorescent material belongs to the monoclinic crystal system, and the crystal parameters of the complex are a = 14.1918(6) Å, b = 8.7327(6) Å, c = 20.8734(7) Å, α = 90°, β = 102.637(4)°, γ = 90°, Z = 11, V = 2524.23(17) Å. 3 .

[0007] Preferably, the copper-based fluorescent material is prepared by the following steps: pmib, 4-CN-PPh2 and CuI were added to an organic solvent in a molar ratio of 1:1:1 and mixed thoroughly. After filtration through filter paper, the filtrate was transferred to a clean beaker. The beaker opening was sealed with plastic wrap and punctured. The mixture was allowed to stand at room temperature in the dark to evaporate. After the solvent had evaporated, the reaction solution in the beaker was washed and filtered multiple times and dried in the air to obtain pure yellow-green crystals, which are the copper-based fluorescent materials.

[0008] Preferably, the organic solvent used in the preparation process of copper-based fluorescent materials is acetonitrile.

[0009] Preferably, the ratio of pmib to organic solvent is 0.05 mmol: 35-50 mL.

[0010] Preferably, the solvent evaporation time is ≥3 days.

[0011] Beneficial effects: The copper-based fluorescent material [(pmib)(4-CN-PPh2)2Cu2I2] provided in Example 1 of this invention nIt is a binuclear complex with a one-dimensional chain-like twisted structure, crystallized in the monoclinic P21 / c space group, with copper atoms coordinated with nitrogen, phosphorus and iodine atoms. The structure is well-defined and the purity is high. The experimental values ​​of powder X-ray diffraction are in high agreement with the simulated values.

[0012] The copper-based fluorescent material [(pmib)(4-CN-PPh2)2Cu2I2] provided in Example 1 of this invention n It exhibits efficient solid-state emission at room temperature, with the strongest excitation wavelength at 450 nm, the emission peak center at 530 nm, and a half-maximum width of about 104 nm, emitting yellow-green light; its photoluminescence quantum yield is as high as 86.79%, exhibiting excellent photoluminescence efficiency.

[0013] Compared to the cyanide-free reference material [(pmib)(4-CN-PPh2)2Cu2I2] n The copper-based fluorescent material [(pmib)(4-CN-PPh2)2Cu2I2] provided in Example 1 of this invention n The photoluminescence decay lifetime was significantly extended to 57.4 μs, indicating that the introduction of the cyano ligand 4-CN-PPh2 effectively enhanced the luminescence lifetime and was beneficial to the dynamic regulation of the excited state.

[0014] The copper-based fluorescent material [(pmib)(4-CN-PPh2)2Cu2I2] provided in Example 1 of this invention n It exhibits typical thermally activated delayed fluorescence characteristics in the temperature range of 80 K to 300 K. The fluorescence delay lifetime decreases from 141.39 μs at 80 K to 68.01 μs at 300 K with increasing temperature, showing obvious temperature-dependent decay behavior. This confirms that heating promotes the conversion of triplet excitons to singlet states through reverse intersystem crossing, providing a material basis for high-efficiency low-temperature light-emitting devices.

[0015] The copper-based fluorescent material [(pmib)(4-CN-PPh2)2Cu2I2] provided in Example 1 of this invention n It exhibits excellent resistance to thermal quenching over a wide temperature range of 80 K to 500 K. Temperature-dependent fluorescence testing shows that the emission intensity remains relatively stable with increasing temperature, with only a slight decrease in the high-temperature range. A blue shift of approximately 20 nm occurs at the emission center, and the emission color gradually changes from yellow-green to green. The CIE coordinates change from (0.3611, 0.5874) at 80 K to (0.3081, 0.5807) at 500 K. This material effectively avoids the fluorescence quenching phenomenon commonly seen at high temperatures, demonstrating extremely strong thermal stability.

[0016] Thermogravimetric analysis results show that the copper-based fluorescent material [(pmib)(4-CN-PPh2)2Cu2I2] provided in Example 1 of this invention...n It remains stable below 236℃, and its thermal decomposition occurs in two steps, exhibiting good thermal stability and meeting the usage requirements of various optical devices over a wide temperature range.

[0017] Based on the above properties, the copper-based fluorescent material [(pmib)(4-CN-PPh2)2Cu2I2] provided in Example 1 of this invention... n It can be widely used in key fields such as high-power lighting, laser display, optical devices for extreme environments and wide-temperature-range optical sensing, and provides a new technical solution to solve the bottleneck problems of the sharp drop in luminous efficiency and performance degradation of existing fluorescent materials under high-temperature conditions. Attached Figure Description

[0018] Figure 1 The [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1 n Infrared spectra of the organic ligands pmib and 4-CN-PPh2.

[0019] Figure 2 The [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1 n Powder X-ray diffraction pattern.

[0020] Figure 3 The [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1 n Thermogravimetric analysis diagram.

[0021] Figure 4 At 298 K, the [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1 n The fluorescence excitation and emission spectra.

[0022] Figure 5 : This refers to the [(pmib)(PPh3)2Cu2I2] obtained in Comparative Example 3. n The [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1 n A comparison curve of fluorescence lifetime decay at room temperature.

[0023] Figure 6 The [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1 n Fluorescence lifetime decay curves at 80-300K.

[0024] Figure 7 The [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1 n Fluorescence spectra at varying temperatures from 80 to 500 K.

[0025] Figure 8 The [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1 n Three-dimensional temperature-varying fluorescence spectrum.

[0026] Figure 9 The [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1 n The CIE diagram for variable temperature.

[0027] Figure 10 The [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1 n PL quantum yield diagram.

[0028] Figure 11 The [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1 n One-dimensional chain structure; Cu, light blue; N, blue; C, gray; hydrogen atoms omitted for clarity. Detailed Implementation

[0029] The present invention will be described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely illustrative examples of implementation of the present invention and are not intended to limit the scope of the present invention.

[0030] In this invention, the yield (%) of copper-based fluorescent materials is calculated as (actual product mass / theoretical product mass) × 100%.

[0031] The reaction reagents used in this invention were purchased from manufacturers such as Anaiji Chemical, Alfa Reagents, and Sinopharm Group, as detailed in Table 1; the reagents involved were used directly without further purification.

[0032] Table 1 Reagent List .

[0033] The equipment and instruments used in the experiment are shown in Table 2: Table 2 Main Instruments .

[0034] In the following embodiments of the present invention, pmib (CAS: 82410-79-5) and 4-CN-PPh2 (CAS No.: 5068-16-6) are conventional commercial products that can be purchased or synthesized according to methods reported in the literature.

[0035] The synthesis method of pmib is as follows: 2-Methylimidazole (0.82 g, 10 mmol) and potassium hydroxide (2.30 g, 41 mmol) were dissolved in dimethyl sulfoxide (15 ml). The reaction mixture was then stirred for about two hours. α-α'-dichloro-p-xylene (0.88 g, 5 mmol) was added to the reaction mixture, and the reaction was stirred overnight. Liquid-liquid extraction was performed with dichloromethane (50 ml). Afterward, magnesium sulfate was added for drying, the mixture was filtered, and the concentration was redistributed. Excess diethyl ether was added, and the flask was placed in a refrigerator overnight to allow the product to precipitate. The final product was a yellowish-white powder. Potassium hydroxide acted as a catalyst and did not participate in the reaction, thus improving the reaction efficiency. Under alkaline drying conditions, 2-methylimidazole and α-α'-dichloro-p-xylene underwent a substitution reaction to produce 1,4-bis[(2-methylimidazole-1-yl)methyl]benzene.

[0036] The synthesis method of 4-CN-PPh2 is as follows: Diphenylphosphine (10.4 ml, 60 mmol) and potassium hydroxide (6 g, 108 mmol) were dissolved in dimethyl sulfoxide (100 ml), and the mixture was stirred for two hours. Then, 4-fluorobenzonitrile (7.266 g, 60 mmol) was added, and the reaction mixture was stirred for half an hour. After the reaction was complete, a large amount of water (2 L) was added to cause precipitation of the reaction mixture. The precipitate was separated by filtration and then recrystallized from methanol to obtain a white crystalline solid. Potassium hydroxide acted as a catalyst, not participating in the reaction, but increasing the reaction rate. Under alkaline and dry conditions, diphenylphosphine reacts with 4-fluorobenzonitrile in a substitution reaction to form 4-(diphenylphosphine)benzonitrile.

[0037] The [(pmib)(PPh3)2Cu2I2] used in this invention n The synthesis method is as follows: PPh3 was a commercially available product purchased from Anaiji Chemical. PMIB (26.6 mg, 0.1 mmol), PPh3 (26.2 mg, 0.1 mmol), and CuI (19 mg, 0.1 mmol) were added sequentially to a beaker containing acetonitrile (20 mL) and dichloromethane (20 mL). The mixture was stirred for 1 min and then sonicated for 30 s. The resulting mixture was filtered, dispensed into clean beakers, sealed with plastic wrap, and punctured. The mixture was allowed to evaporate at room temperature for approximately 4 days. After solvent evaporation, acetonitrile was added to the beakers for repeated washing and filtration. The collected solid product was dried in air to obtain pure, bright blue crystals, denoted as [(pmib)(4-CN-PPh2)2Cu2I2]. n .

[0038] Example 1 A method for preparing a copper-based fluorescent material is as follows: pmib (13.3 mg, 0.05 mmol), 4-CN-PPh2 (14.4 mg, 0.05 mmol), and CuI (9.5 mg, 0.05 mmol) were sequentially added to a beaker containing acetonitrile (40 mL), stirred for 1 min, and sonicated for 30 s. The resulting mixture was filtered and transferred to a clean beaker, sealed with plastic wrap, and punctured. The mixture was allowed to stand at room temperature for 4 days to evaporate the solvent. After evaporation, acetonitrile was added to the beaker, stirred, and filtered. The stirring, washing, and filtration were repeated three times. The collected solid product was dried in air to obtain the copper-based fluorescent material, denoted as [(pmib)(4-CN-PPh2)2Cu2I2]. n .

[0039] Crystals prepared by the evaporation method were collected under a microscope, namely [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1. n Crystallographic data of Mo monochromatic radiation on a Iuker APEX-II CCD instrument Kα (λ = 0.71073 Å), collected at the corresponding temperature. Data collection, data reduction, and cell optimization were performed using two packages: Iuker Instrument Service v4.2.2 and SAINT V8.34 A. The coordination compound structure was resolved using the SHELXS package, and the crystal data were optimized using full-matrix least squares with the SHELXL package. Absorption correction was performed using the multi-scan package SADABS. Hydrogen atoms of the organic ligand were analyzed in F-mode using the riding mode on the SHELXTL package. 2 Anisotropic optimization is performed on the surface.

[0040] Based on crystal data analysis, the [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1... n In monoclinic P Crystallized in space group 21 / c.

[0041] Cu +The ions have a four-coordinate configuration, bonding with an iodide ion, a phosphorus atom in a phosphine ligand, and a nitrogen atom in a nitrogen-containing heterocyclic ligand. All the metal centers of the complexes exhibit a planar tetrahedral structure. The binuclear metal centers are connected by two bridging I atoms, simultaneously exhibiting a weak Cu···Cu interaction with a bond length of 3.0094(8) Å. The Cu–I bond lengths are 2.6589(5) and 2.6893(5) Å, respectively; the Cu–P bond length is 2.2306(9) Å; the Cu–N bond length is 2.025(3) Å; and the P–C bond length ranges from 1.820(3) to 1.837(3) Å. A cyano group (C≡N, bond length 1.140 Å) is also present in the structure.

[0042] The [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1 n The crystallographic data are shown in Table 3, [(pmib)(4-CN-PPh2)2Cu2I2] n The partial bond length (Å) and bond angle (º) data are shown in Table 4.

[0043] Table 3 Crystallographic parameters of the coordination compounds .

[0044] In Table 3: R1 a = Σ( F0 - Fc ) / Σ F0 wR2 b = [Σw( F0 2 - Fc 2 ) 2 / Σw F0 2 2 ] 1 / 2 ; GOF c = [∑[w(F0 2 -Fc 2 ) 2 ] / (N obs -N params )] 1 / 2 The above data is based on I>2σ(I).

[0045] Table 4. Important bond lengths (Å) and bond angles (°) in the crystal structures of coordination compounds. .

[0046] Comparative Example 1 is the same as Example 1, except that the amount of 4-CN-PPh2 added in Comparative Example 1 is 0.1 mmol.

[0047] The crystals in the beaker showed ligand precipitation, and the presence of non-crystalline substances made the mixture too chaotic, including crystals with weak luminescence intensity. Therefore, the fluorescent material at this ratio could not be used. The purity of the copper-based fluorescent material obtained in Comparative Example 1 was less than 50%. The purity of the copper-based fluorescent material obtained in Example 1 was 100%.

[0048] Comparative Example 2 is the same as Example 1, except that the amount of 4-CN-PPh2 and CuI added in Comparative Example 2 is 0.1 mmol and 0.1 mmol, respectively. The yield of the copper-based fluorescent material obtained in Comparative Example 2 is too low, <50%. The yield of the copper-based fluorescent material obtained in Example 1 is 98%.

[0049] Comparative Example 3 is [(pmib)(PPh3)2Cu2I2] n .

[0050] Material physical and chemical characterization test Infrared absorption spectroscopy analysis: as per the instruction manual. Figure 1 As shown, the black and red spectral lines are the infrared absorption spectra of pmib and 4-CN-PPh2, respectively, while the blue spectral line is the infrared absorption spectrum of the copper-based fluorescent material obtained in Example 1. The image shows that the vibrational contraction peaks of the organic ligand and the infrared absorption spectrum of the copper-based fluorescent material almost match, indicating the presence of organic ligands in the copper-based fluorescent material.

[0051] Powder X-ray diffraction analysis: as per the instruction manual. Figure 2 As shown, the black spectral lines were obtained by computer simulation based on the crystal structure, while the red spectral lines were plotted based on experimental data. The image shows the [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1. n The experimental and simulated values ​​agree very well, indicating that the complex is a pure phase.

[0052] Thermogravimetric analysis: as per the instruction manual Figure 3 As shown, the thermogravimetric analysis (TGA) method was used to study the [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1. n Thermal stability from room temperature to 800℃. The TGA curve shows [(pmib)(4-CN-PPh2)2Cu2I2]... nIt exhibits good thermal stability, and its mass loss occurs in two steps. A first weight loss of approximately 43-44% is observed in the complex between 236-400 °C due to the removal of halogens and some ligands. The second weight loss, occurring between 400-800 °C, can be attributed to the complete removal of both the organic ligands and the metal ions.

[0053] Fluorescence test: as per the instruction manual Figure 4 As shown, the [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1 n With the strongest excitation wavelength of 450 nm, it exhibits a strong emission band centered at 530 nm, with a full width at half maximum (FWHM) of approximately 104 nm, and emits yellow-green light.

[0054] Photoluminescence PL decay lifetime test: as per the instruction manual. Figure 5 As shown, the [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1 n The photoluminescent PL exhibits a relatively long lifetime of 57.4 μs, while [(pmib)(PPh3)2Cu2I2] n The photoluminescence PL decay lifetime is only 7.2 μs, which indicates that the -CN-containing [(pmib)(4-CN-PPh2)2Cu2I2] n The decay lifetime of photoluminescent PL is significantly increased.

[0055] Fluorescence lifetime decay analysis: as per the instruction manual. Figure 6 As shown, the [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1 n The fluorescence delay lifetime decreased significantly from 141.39 μs at 80 K to 68.01 μs at 300 K, exhibiting excellent thermally activated delayed fluorescence (TADF) characteristics based on data analysis. This temperature-dependent lifetime decay behavior is mainly due to the fact that increasing the temperature promotes the conversion of triplet excitons to singlet states through the reverse system crossing (RISC) process, accelerating the overall decay dynamics of the excited state.

[0056] Study on fluorescence thermal quenching properties: To investigate the temperature dependence of fluorescence, variable-temperature fluorescence testing was conducted. (See attached instruction manual.) Figure 7 It is a temperature-dependent fluorescence spectrum, see the instruction manual. Figure 8 This is a three-dimensional temperature-varying fluorescence spectrum. Test results show that as the temperature gradually increases from 80 K to 320 K, the [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1... nThe launch center gradually shifts, but the launch intensity remains relatively stable as the temperature increases. From 320-500K, with increasing temperature, the [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1... n The launch center gradually blue-shifted, and the launch intensity showed a slight decreasing trend. Overall, the [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1... n The emission intensity remained stable with temperature changes, although it decreased slightly with increasing temperature, and there was a blue shift of approximately 20 nm at the emission center. The [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1 showed a change with temperature. n It exhibits a relatively stable fluorescent color.

[0057] Fluorescence temperature-dependent CIE property study: as per the instruction manual. Figure 9 As shown, with increasing temperature, the [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1... n The emission color changes from yellow-green at low temperature (80 K) to green at high temperature (500 K). Correspondingly, the CIE coordinates change from (0.3611, 0.5874) at 80 K to (0.3081, 0.5807) at 500 K, and the shift of the corresponding peak is consistent with the fluorescence emission shift with increasing temperature.

[0058] Photoluminescence quantum yield properties study: as per the instruction manual. Figure 10 As shown, the [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1 at room temperature n Its quantum yield can reach up to 86.79%, exhibiting high quantum efficiency.

[0059] Instruction manual attached Figure 11 It is the [(pmib)(4-CN-PPh2)2Cu2I2] obtained in Example 1. n One-dimensional chain structure; Cu, light blue; N, blue; C, gray; hydrogen atoms omitted for clarity.

[0060] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A copper-based fluorescent material possessing high quantum yield, high thermal stability, and resistance to thermal quenching, characterized in that, Copper-based fluorescent materials are coordination polymer crystals, which are products obtained by coordination self-assembly of 1,4-bis[(2-methylimidazol-1-yl)methyl]benzene, 4-(diphenylphosphine)benzonitrile, and CuI in an organic solution. In the coordination polymer crystal, Cu is coordinated with P, N, and I atoms. Two Cu atoms are connected by pmib to form a twisted, infinitely extended one-dimensional chain structure. Its single-crystal molecular formula is: [(pmib)(4-CN-PPh2)2Cu2I2]n, where pmib is 1,4-bis[(2-methylimidazol-1-yl)methyl]benzene and 4-CN-PPh2 is 4-(diphenylphosphine)benzonitrile.

2. The copper-based fluorescent material with high quantum yield, high thermal stability, and resistance to thermal quenching as described in claim 1, characterized in that, The copper-based fluorescent material belongs to the monoclinic crystal system. The crystal parameters of the complex are a = 14.1918(6) Å, b = 8.7327(6) Å, c = 20.8734(7) Å, α = 90°, β = 102.637(4)°, γ = 90°, Z = 11, V = 2524.23(17) Å. 3 .

3. The copper-based fluorescent material with high quantum yield, high thermal stability, and resistance to thermal quenching as described in claim 1, characterized in that, The preparation method includes the following steps: pmib, 4-CN-PPh2 and CuI were added to an organic solvent in a molar ratio of 1:1:1 and mixed thoroughly. After filtration through filter paper, the filtrate was transferred to a clean beaker. The beaker opening was sealed with plastic wrap and punctured. The mixture was allowed to stand at room temperature in the dark to evaporate. After the solvent had evaporated, the reaction solution in the beaker was washed and filtered multiple times and dried in the air to obtain pure yellow-green crystals, which are the copper-based fluorescent materials.

4. The copper-based fluorescent material with high quantum yield, high thermal stability, and resistance to thermal quenching as described in claim 3, characterized in that, The organic solvent is acetonitrile.

5. A copper-based fluorescent material with high quantum yield, high thermal stability, and resistance to thermal quenching as described in claim 3, characterized in that, The ratio of pmib to organic solvent is 0.05 mmol: 35-50 mL.

6. A copper-based fluorescent material with high quantum yield, high thermal stability, and resistance to thermal quenching as described in claim 5, characterized in that, Solvent evaporation time ≥ 3 days.

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