Perovskite composite material and preparation method and application thereof

Abstract

The invention relates to a perovskite composite material as well as a preparation method and application thereof. The perovskite composite material comprises APTES modified lead halide perovskite nanocrystals and organic-inorganic hybrid perovskite glass, the APTES modified lead halide perovskite nanocrystal is completely encapsulated in the organic-inorganic hybrid perovskite glass, and the APTES modified lead halide perovskite nanocrystal is formed by the organic-inorganic hybrid perovskite glass and the inorganic-organic hybrid perovskite glass. The organic-inorganic hybrid perovskite glass comprises (TPnA) M (dca) 3 and Li (C2N3). According to the invention, pre-stabilization treatment is realized by modifying lead halide perovskite nanocrystals by using APTES, then Li (C2N3) is introduced to realize low-temperature fusion packaging of organic-inorganic hybrid perovskite glass on the nanocrystals, and under the synergistic effect of the two, the composite material with high luminescence property and high stability is obtained. The perovskite composite material containing CsPbBr3 can be used as a green light conversion layer to be integrated with commercial red powder and a blue light chip into a WLED device, and has a good application prospect in the fields of solid-state illumination and display.

Description

Technical Field

[0001] This invention relates to the field of luminescent materials technology, specifically to a perovskite composite material, its preparation method, and its application. Background Technology

[0002] All-inorganic lead halide perovskite nanocrystals (CsPbX3, X = Cl, Br, I) exhibit great application potential in next-generation display technologies and solid-state lighting fields (such as backlight displays, LEDs, and Mini / Micro-LEDs) due to their excellent optical properties, such as tunable emission spectra, narrow full width at half maximum (FWHM), and high photoluminescence quantum yield (PLQY). However, these nanocrystals are prone to reabsorption effects in their powder form, leading to reduced fluorescence efficiency. More importantly, as ionic crystals, they are structurally unstable and prone to degradation when exposed to water, oxygen, light, and heat for extended periods, which severely restricts their practical industrial application.

[0003] To overcome the aforementioned stability challenges, current research primarily focuses on two main technical approaches: surface engineering strategies and matrix encapsulation strategies. Details are as follows: (1) Surface modification strategy: This strategy can improve the colloidal stability and short-term tolerance of nanocrystals to a certain extent by modifying the surface of nanocrystals with organic ligands. However, this protective layer is relatively fragile and is prone to failure in long-term or harsh service environments (such as high temperature and high humidity), and cannot provide durable and reliable protection for nanocrystals.

[0004] (2) Traditional inorganic glass encapsulation strategy: This strategy embeds perovskite nanocrystals into a rigid inorganic glass matrix, which can effectively isolate water and oxygen and significantly improve long-term stability. However, this method usually requires a high-temperature melting process of more than 1000 °C. The extremely high processing temperature not only consumes a lot of energy, but more importantly, it will directly cause irreversible thermal degradation and fluorescence quenching of CsPbX3 nanocrystals, causing them to lose their original high-performance luminescent properties.

[0005] (3) MOF glass encapsulation strategy: As an emerging approach, this strategy attempts to mix perovskite precursors with metal-organic framework materials and encapsulate them using liquid-phase sintering technology. Although the processing temperature (approximately 175 °C to 350 °C) is significantly lower than that of traditional glass, this temperature range is still relatively high for perovskite nanocrystals, and the complex in-situ growth process easily introduces byproducts, affecting the purity and optical properties of the material. There are obvious bottlenecks in terms of process controllability and large-scale preparation.

[0006] (4) Emerging Hybrid Perovskite Glass Encapsulation Strategies: In recent years, organic-inorganic hybrid perovskites (HOIPs) have emerged as a promising encapsulation matrix due to their low melting temperatures. For example, the melting temperatures of some HOIP matrices can be as low as 143 °C to 155 °C. Nevertheless, for unprotected CsPbX3 nanocrystals, this temperature window may still lead to surface damage and fluorescence quenching during the encapsulation process, making it difficult to achieve perfect encapsulation while maintaining high luminous efficiency.

[0007] In summary, current strategies for improving the stability of all-inorganic lead halide perovskite nanocrystals all have their limitations: insufficient surface protection or incompatibility between the encapsulation process temperature and the thermal stability of the perovskite nanocrystals. Therefore, there is an urgent need in this field to develop a novel encapsulation technology and material system that can achieve melt-forming at relatively low temperatures, thereby providing a dense and robust encapsulation protective layer while fully preserving the initial high luminescence performance of the nanocrystals, ultimately obtaining a perovskite composite material that combines high luminescence efficiency with excellent environmental stability. Summary of the Invention

[0008] To address the reabsorption effect and environmental instability of all-inorganic lead halide perovskite nanocrystals, and to overcome the limitations of existing strategies for improving their stability (such as insufficient surface protection or incompatibility between encapsulation process temperatures and the thermal stability of perovskite nanocrystals), this invention provides a perovskite composite material, its preparation method, and its applications. The method utilizes (3-aminopropyl)triethoxysilane (APTES) to modify lead halide perovskite nanocrystals for pre-stabilization treatment, followed by the introduction of Li(C2N3) to achieve low-temperature molten encapsulation of the nanocrystals with an organic-inorganic hybrid perovskite glass. Through the synergistic effect of these two methods, a perovskite composite material exhibiting both high PLQY (≥70%) and excellent environmental stability (water resistance, light resistance, and heat resistance) is obtained.

[0009] Specifically, the following technical solutions are provided: The first aspect of this invention provides a perovskite composite material comprising (3-aminopropyl)triethoxysilane-modified lead halide perovskite nanocrystals and an organic-inorganic hybrid perovskite glass; wherein the (3-aminopropyl)triethoxysilane-modified lead halide perovskite nanocrystals are completely encapsulated within the organic-inorganic hybrid perovskite glass. The chemical formula of the lead halide perovskite nanocrystals is CsPbX3, where X is Cl, Br, or I. The organic-inorganic hybrid perovskite glass comprises (TPnA)M(dca)3 and Li(C2N3), where TPnA is a tetrapentylammonium cation, M is selected from one or more of Mn, Fe, and Co, and dca is a dicyandiamide anion.

[0010] This invention achieves a balance between high performance and high stability of nanocrystals through the synergistic effect of APTES modification to enhance the intrinsic stability of nanocrystals, Li(C2N3) modification to lower the matrix melting temperature, and HOIPs glass encapsulation at temperatures far lower than those of traditional methods. Specifically: First, this invention uses APTES as a ligand to modify the surface of CsPbX3 nanocrystals to enhance their intrinsic stability. The mechanism lies in the fact that the -NH2 group of APTES can form strong hydrogen bonds with halide ions in the nanocrystals, inhibiting halogen migration. Simultaneously, the strong affinity reduces surface phonons, weakening exciton-phonon coupling, thereby pre-conferring excellent thermal and solvent stability on the nanocrystals before subsequent encapsulation.

[0011] Secondly, HOIPs materials with the general formula (TPnA)M(dca)3 were selected as the encapsulation matrix. This type of material has a low melting temperature (<160 °C), and after melting, it can form a stable amorphous glass by rapid cooling, providing an ideal protective shell for nanocrystals.

[0012] More importantly, the introduction of the eutectic modifier Li(C2N3) into the encapsulation matrix material can form a eutectic mixture with (TPnA)M(dca)3, significantly reducing the melting temperature of the system from ~155 °C of the pure matrix to a minimum of 83 °C (when the molar ratio of (TPnA)M(dca)3 to Li(C2N3) is 1:0.4), greatly reducing the thermal stress during the encapsulation process and thus effectively avoiding thermal damage to the nanocrystals.

[0013] Furthermore, the mass ratio of the (3-aminopropyl)triethoxysilane-modified lead halide perovskite nanocrystals to the organic-inorganic hybrid perovskite glass in the perovskite composite material is preferably 0.5:9.5-2:8, such as 0.5:9.5, 1:9, 1.5:8.5, 2:8, etc., including but not limited to the mass ratios listed above.

[0014] In this invention, if the content of (3-aminopropyl)triethoxysilane-modified lead halide perovskite nanocrystals in the perovskite composite material is too low, a large number of perovskite quantum dots may be quenched during the melting process, resulting in weak fluorescence intensity. However, if the content of (3-aminopropyl)triethoxysilane-modified lead halide perovskite nanocrystals is too high, the nanocrystals will undergo a reabsorption effect, leading to a low PLQY. Preferably, the content of (3-aminopropyl)triethoxysilane-modified lead halide perovskite nanocrystals in the perovskite composite material is controlled within the range of 5%-20% to obtain a perovskite composite material with high fluorescence intensity and high PLQY.

[0015] Furthermore, the molar ratio of (TPnA)M(dca)3 to Li(C2N3) in the organic-inorganic hybrid perovskite glass is preferably 1:(0.2-0.4), such as 1:0.2, 1:0.3, 1:0.4, etc., more preferably 1:0.4. Further increasing the amount of Li(C2N3) will not further reduce the melting temperature; instead, excessive modifier will cause the material properties to shift towards the modifier. Excess Li(C2N3) cannot be uniformly integrated into the crystal lattice but exists as an independent crystalline or amorphous phase. During the cooling process, Li(C2N3) will preferentially crystallize, ultimately leading to a decrease in the stability of the HOIPs glass. In addition, CsPbX3 nanocrystals are ionic crystals, and their stability is highly susceptible to interference from external ions. Excess Li(C2N3) in the molten state may dissociate into a large amount of Li. + and (C2N3) - Ions. These ions may interact or exchange with halide anions in the perovskite, further disrupting the structural integrity of the nanocrystals. Therefore, to effectively reduce the melting temperature of the encapsulation matrix while minimizing its impact on the stability of HOIPs glass and the nanocrystal structure, the molar ratio of (TPnA)M(dca)3 to Li(C2N3) in the organic-inorganic hybrid perovskite glass is preferably controlled within the range of 1:(0.2-0.4).

[0016] Furthermore, the photoluminescence quantum yield of the perovskite composite material is not less than 70%.

[0017] Furthermore, the fluorescence intensity retention rate of the perovskite composite material is greater than 60% after immersion in water for 7 days.

[0018] Furthermore, the fluorescence intensity retention rate of the perovskite composite material is greater than 75% after continuous blue light irradiation for 432 hours, under the test conditions of strong blue light with λ = 452 nm and I = 200 mA.

[0019] Furthermore, the emission wavelength of the perovskite composite material is 515-518 nm, and the emission half-maximum width is 18-20 nm.

[0020] A second aspect of this invention provides a method for preparing the perovskite composite material described in the first aspect, comprising the following steps: S1. Grind and mix (TPnA)M(dca)3 crystals with Li(C2N3) until homogeneous to form a eutectic mixture; S2. The lead halide perovskite nanocrystals modified with (3-aminopropyl)triethoxysilane are ground and mixed evenly with the eutectic mixture, and then heated and melted under an inert atmosphere. After complete melting, the perovskite composite material is obtained by cooling.

[0021] Further, in step S1, the preparation method of the (TPnA)M(dca)3 crystal is as follows: A metal nitrate is dissolved in water to obtain a metal nitrate solution; the metal ions in the metal nitrate are selected from Mn. 2+ Fe 2+ Co 2+ One or more of the following; Tetrapentylammonium bromide and sodium dicyandiamide were dissolved in a solvent to obtain a ligand solution; the solvent was a mixture of ethanol and water. The metal salt solution was transferred to a container, and the ligand solution was slowly added. The mixture was allowed to stand at room temperature to evaporate, thus obtaining the (TPnA)M(dca)3 crystals.

[0022] Further, in step S1, the preparation method of Li(C2N3) is as follows: sodium dicyandiamide and lithium sulfate are reacted in an aqueous solution, the precipitate is collected, washed, and recrystallized to obtain Li(C2N3); preferably, the washing solvent is ethanol, and the recrystallization solvent is tetrahydrofuran.

[0023] Further, in step S2, the preparation method of the (3-aminopropyl)triethoxysilane-modified lead halide perovskite nanocrystals is as follows: Cs2CO3 is mixed with oleic acid and 1-octadecene, and then degassed under vacuum at 80-130 °C (e.g., 120 °C). The mixture is then reacted at 140-160 °C (e.g., 150 °C) under an inert gas protection until the mixture becomes clear, yielding a cesium oleate precursor solution. Lead halide was mixed with 1-octadecene, oleic acid, oleylamine, and (3-aminopropyl)triethoxysilane. After vacuum degassing at 80-130 °C (e.g., 120 °C), the mixture was injected into the cesium oleate precursor solution at 155-185 °C (e.g., 160 °C) under inert gas protection. The reaction was carried out for 3-8 seconds (e.g., 5 seconds) and then immediately cooled in an ice-water bath. The mixture was then centrifuged to obtain the (3-aminopropyl)triethoxysilane-modified lead halide perovskite nanocrystals.

[0024] Further, in step S2, the temperature of the heating and melting treatment is preferably 85-155 ℃, such as 85 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, etc., and the time is preferably 2-15 min, such as 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, etc., including but not limited to the temperatures or times listed above. Here, the time is the holding time, for example, heating to 155 ℃ and holding for 2 min.

[0025] More preferably, the heating and melting treatment is carried out at a temperature of 100-125 °C for 8-12 min.

[0026] Furthermore, in step S2, the cooling is preferably rapid cooling, so that the encapsulation substrate forms amorphous glass.

[0027] In some preferred embodiments of the invention, the temperature is programmed to reach the melting temperature at a rate of 10 °C / min.

[0028] A third aspect of the present invention provides an optoelectronic device comprising the perovskite composite material described in the first aspect or the perovskite composite material prepared by the preparation method described in the second aspect.

[0029] Furthermore, the optoelectronic device includes a light-emitting diode, and the perovskite composite material, as a green light-emitting conversion layer, is integrated together with a red light-emitting material (such as CdSe@ZnS quantum dots) on a blue LED chip (such as λ = 455 nm). Green light and red light are generated by blue light excitation and mixed to form white light, thereby constructing a high-performance, high-stability white diode device.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention reduces the melting temperature of the encapsulation matrix by modifying it with Li(C2N3), lowering it to a minimum of 83°C. This allows for the encapsulation of nanocrystals with HOIPs glass at temperatures far lower than those of traditional methods. Furthermore, the synergistic modification of lead halide perovskite nanocrystals with APTES greatly preserves the fluorescence properties of the nanocrystals after encapsulation, resulting in a perovskite composite material with a photoluminescence quantum yield of not less than 70%, which is far superior to traditional glass encapsulation products (<50%) that suffer severe quenching due to high temperatures.

[0031] 2. The perovskite composite material provided by this invention possesses both high luminescence performance and excellent environmental stability, specifically including the following points: (1) High luminescence performance: The emission peak of the perovskite composite material is located at 515-518 nm, the half-peak width is narrow to 18-20 nm, and the color purity is high; (2) Excellent water resistance: After the perovskite composite material is directly immersed in water for 7 days, its fluorescence intensity can still be maintained at more than 80% of the initial value; while the fluorescence of unencapsulated APTES-CsPbBr3 nanocrystals is significantly weakened and quickly quenched in water within 24 hours. The fluorescence intensity of APTES-CsPbBr3 nanocrystals directly encapsulated with (TPnA)M(dca)3 drops to 30% of the initial value after immersing in water for 2 days.

[0032] (3) Excellent photostability: After 432 hours (18 days) of continuous irradiation with strong blue light (λ = 452 nm, I = 200 mA), the fluorescence intensity of the composite material can still maintain about 80% of the initial value; under the same conditions, the fluorescence intensity of the unencapsulated APTES-CsPbBr3 nanocrystals decayed to 47% of the initial value after 168 hours (7 days).

[0033] (4) Excellent thermal stability: After being heated at 85 °C for 8 hours before encapsulation, the fluorescence intensity of APTES-CsPbBr3 nanocrystals can still be maintained at 96%; while the fluorescence intensity of HI-CsPbBr3 nanocrystals prepared by the traditional hot injection method is only 3% after 8 hours under the same conditions, highlighting the dual stabilizing effect of APTES modification and glass encapsulation.

[0034] 3. The present invention also provides a method for preparing the above-mentioned perovskite composite material. This method does not require complex high-temperature melting and annealing equipment, and the preparation process is simple, easy to control, and suitable for industrial mass production.

[0035] 4. The perovskite composite material provided by this invention can be used as a green light conversion layer and integrated with commercial red and blue light chips to form a WLED device. This device achieves a luminous efficiency of 85.2 lm·W at a drive current of 10 mA. -1 With color coordinates of (0.31, 0.33), it is very close to standard white light, demonstrating its great practical application value in the field of solid-state lighting and display. Attached Figure Description

[0036] Figure 1 In Figure a, TEM image of APTES-CsPbBr3 nanocrystals prepared in Example 1 is shown, with a scale bar of 50 nm. The inset is the corresponding HRTEM image, with a scale bar of 5 nm. In Figure b, particle size distribution of APTES-CsPbBr3 nanocrystals prepared in Example 1 is shown. Figure 2 The XRD pattern of APTES-CsPbBr3 prepared in Example 1 is compared with that of the orthorhombic CsPbBr3 standard card (ICSD#01-072-7929). Figure 3 The fluorescence emission and UV-Vis absorption spectra of the APTES-CsPbBr3 nanocrystals prepared in Example 1 are shown in the inset. The inset shows photographs of the nanocrystal toluene dispersion under sunlight (left) and 365 nm UV light (right). Figure 4In Figure a, the FT-IR spectra of APTES-CsPbBr3 nanocrystals and HI-CsPbBr3 nanocrystals prepared in Example 1 are shown, with the vertical dashed lines indicating the characteristic Si-O-Si vibrational peaks in the APTES-CsPbBr3 nanocrystals; in Figure b, the spectra of APTES ligands, APTES-CsPbBr3 prepared in Example 1, and HI-CsPbBr3 are shown. 1 H NMR spectrum; Figure 5 In Figure a, the normalized fluorescence intensity change of APTES-CsPbBr3 and HI-CsPbBr3 nanocrystals prepared in Example 1 during thermal aging at 85 °C is shown. In Figure b, the fluorescence images of the two nanocrystal films APTES-CsPbBr3 and HI-CsPbBr3 prepared in Example 1 after thermal aging for 0 h and 8 h under ultraviolet light are shown. Figure 6 Image a shows an ethanol dispersion of APTES-CsPbBr3 and HI-CsPbBr3 nanocrystals prepared in Example 1 under fluorescent and ultraviolet light after initial exposure and 32 h of standing. Image b shows an aqueous dispersion of APTES-CsPbBr3 and HI-CsPbBr3 nanocrystals prepared in Example 1 under fluorescent and ultraviolet light after initial exposure and 32 h of standing. Figure 7 The FT-IR spectra of Li(C2N3) prepared in Example 1, Na(C2N3) prepared in Comparative Example 2, and Li(C2N3) reported in the literature are shown. Figure 8 DSC curves of eutectic encapsulation matrices containing different contents of Li(C2N3) prepared in Example 1; Figure 9 In Figure a, TEM image of the perovskite composite material prepared in Example 1 is shown; in Figure b, particle size distribution of the perovskite composite material prepared in Example 1 is shown. Figure 10 The image shows a comparison between the XRD pattern of the perovskite composite material prepared in Example 1 and the orthorhombic CsPbBr3 standard card (ICSD#01-072-7929). Figure 11 The image shows the fluorescence spectrum of the perovskite composite material prepared in Example 1 under 365 nm ultraviolet light excitation, and the inset shows the luminescence photograph under corresponding ultraviolet lamp irradiation. Figure 12 Comparison of fluorescence stability of the perovskite composite material prepared in Example 1 and unencapsulated APTES-CsPbBr3 nanocrystals after one week of storage in an aqueous environment. Figure 13In Figure a, the fluorescence intensity of the perovskite composite material prepared in Example 1 changes with irradiation time under strong blue light irradiation (λ = 452 nm, I = 200 mA); in Figure b, the fluorescence intensity of unencapsulated APTES-CsPbBr3 nanocrystals changes with irradiation time under strong blue light irradiation (λ = 452 nm, I = 200 mA). Figure 14 XRD patterns of perovskite composite materials prepared by (TPnA)M(dca)3 and Comparative Example 1 without the addition of Li(C2N3) to the encapsulation matrix (TPnA)M(dca)3. The inset shows photographs of the perovskite composite materials under sunlight (left) and 365 nm ultraviolet light (right). Figure 15 DSC curves of perovskite composite materials prepared by (TPnA)M(dca)3 and Comparative Example 2 using Na(C2N3) as the encapsulation matrix; Figure 16 The XRD patterns of the eutectic encapsulation matrix and perovskite composite material prepared in Comparative Example 2 are shown in the inset. The inset is a fluorescence photograph of the perovskite composite material under ultraviolet light irradiation. In the figure, TPnAMndca3 is (TPnA)Mn(dca)3. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The terms “comprising” or “including” used in this invention may also be replaced with the closed form “is” or “consisting of”.

[0039] The instrument information used to characterize the morphology, structure, and properties of the materials prepared in the following examples and comparative examples is as follows: The morphology, size, and lattice fringes of the nanocrystals were observed using transmission electron microscopy (TEM, TALOS 200X, accelerating voltage 220 kV) and high-resolution transmission electron microscopy (HRTEM).

[0040] The phases and crystal structure were analyzed using an X-ray diffractometer (XRD, Empyrean, PANalytical, Cu Kα radiation source, λ = 1.54056 Å).

[0041] Photoluminescence (PL) spectra were measured using a fluorescence spectrometer (FLUOROMAX-4, xenon lamp light source); absorption spectra were measured using a UV-Vis spectrophotometer (Evolution 220).

[0042] The photoluminescent quantum yield (PLQY) was measured using an absolute quantum yield measurement system (Quantaurus-QY Plus C13534-11, HAMAMATSU).

[0043] Thermal stability was analyzed using a thermogravimetric analyzer (TGA, SDT-Q600, TA Instruments, argon atmosphere, heating rate 10 °C / min); melting behavior was analyzed using a differential scanning calorimeter (DSC, Netzsch 214 Polyma, argon atmosphere, heating rate 10 °C / min).

[0044] Fourier transform infrared spectroscopy (FTIR, Bruker Vertex V70) and nuclear magnetic resonance spectroscopy (NMR) were used. 1 ¹H NMR (Agilent DD2-600) was used to analyze surface ligands and chemical structures.

[0045] Example 1: This example relates to the preparation of a perovskite composite material, as detailed below: (1) Preparation of lead halide perovskite (APTES-CsPbBr3) nanocrystals modified with (3-aminopropyl)triethoxysilane Preparation of cesium oleate (Cs-OA) precursor: In a 50 mL three-necked flask, 0.16 g (0.5 mmol) of Cs₂CO₃, 0.5 mL of oleic acid (OA), and 8 mL of 1-octadecene (ODE) were mixed. The mixture was evacuated to 120 °C for 1 hour, and then heated to 150 °C under a N₂ atmosphere until all solids were completely dissolved, yielding a clear Cs-OA precursor solution for later use.

[0046] Synthesis of APTES-CsPbBr3 nanocrystals: 0.138 g PbBr2, 10 mL ODE, 1 mL OA, 1 mL oleylamine (OAm), and 1 mL APTES were added sequentially to another 50 mL three-necked flask. The mixture was degassed under vacuum at 120 °C for 1 hour, followed by heating to 160 °C under N2 protection. After the PbBr2 was completely dissolved, 0.8 mL of the above Cs-OA precursor solution was rapidly injected. After reacting for 5 seconds, the reaction mixture was immediately placed in an ice-water bath to cool to room temperature.

[0047] Purification: The crude product was centrifuged at 9000 rpm for 5 minutes, the supernatant was discarded, and the precipitate was redispersed in 10 mL of toluene to obtain a toluene colloidal solution of APTES-CsPbBr3 nanocrystals.

[0048] TEM image of APTES-CsPbBr3 nanocrystals prepared in this embodiment ( Figure 1 Figure a) and HRTEM image ( Figure 1 As shown in the inset of Figure a), the prepared nanocrystals are uniformly dispersed, with a clear lattice and a crystal plane spacing of 0.416 nm, corresponding to the (110) crystal plane of the orthorhombic CsPbBr3. Its particle size distribution is shown in the figure below. Figure 1 As shown in Figure b, the average size is 11.05 nm.

[0049] The XRD pattern of the APTES-CsPbBr3 nanocrystals prepared in this embodiment is as follows: Figure 2 As shown in the figure, the APTES-CsPbBr3 nanocrystals prepared in this embodiment are in good agreement with the orthorhombic CsPbBr3 standard card (ICSD#01-072-7929).

[0050] The fluorescence emission and UV-Vis absorption spectra of the APTES-CsPbBr3 nanocrystals prepared in this embodiment are as follows: Figure 3 As shown in the figure, the emission peak of the nanocrystals in toluene solution is located at 515 nm, the FWHM is 17 nm, and the PLQY is as high as 90%.

[0051] In addition, the FT-IR spectrum of the APTES-CsPbBr3 nanocrystals prepared in this embodiment and 1 The H NMR spectra are as follows: Figure 4 As shown in figures a and b, APTES was successfully modified onto the nanocrystalline surface.

[0052] To further investigate the stability advantages of the APTES-CsPbBr3 nanocrystals prepared in this embodiment compared to CsPbBr3 nanocrystals prepared by the traditional hot-injection method (HI-CsPbBr3), APTES-CsPbBr3 nanocrystals and HI-CsPbBr3 nanocrystals were subjected to high-temperature storage at 85 °C and polar solvent stability tests, as detailed below: The preparation of HI-CsPbBr3 is as follows: In a 50 mL three-necked flask, 0.2 g of Cs₂CO₃, 1.25 mL of OA, and 20 mL of ODE were mixed and degassed under vacuum at 120 °C for 1 hour. The mixture was then heated to 150 °C under N₂ protection to prepare a Cs-OA precursor solution. In another 25 mL three-necked flask, 1.23 mmol of OAm, 1.17 mmol of OA, 5 mL of ODE, and 0.073 g of PbBr₂ were added, and the mixture was heated to 160 °C under a nitrogen atmosphere. Then, 0.4 mL of the hot Cs-OA precursor solution was rapidly injected. After reacting for 5 seconds, the mixture was immediately cooled to room temperature in an ice-water bath. The resulting reaction solution was centrifuged at 9000 rpm for 5 minutes, and the supernatant was collected and dispersed in 10 mL of hexane to obtain the HI-CsPbBr₃ nanocrystal comparative sample. The FT-IR spectra of the HI-CsPbBr₃ nanocrystals and... 1 The H NMR spectra are as follows: Figure 4 As shown in a and b in the figure, HI-CsPbBr3 nanocrystals were successfully prepared.

[0053] The results of the 85 °C high-temperature storage test are as follows: Figure 5 As shown in a and b, after heating at 85 °C for 8 hours, the fluorescence intensity of APTES-CsPbBr3 nanocrystals remained at 96%, and the APTES-CsPbBr3 nanocrystal film maintained high fluorescence intensity even after thermal aging under UV light for 8 hours. In contrast, the fluorescence intensity of HI-CsPbBr3 nanocrystals was only 3% after heating at 85 °C for 8 hours, and the HI-CsPbBr3 nanocrystal film was completely quenched after thermal aging under UV light for 8 hours.

[0054] The results of the polar solvent stability test are as follows Figure 6 As shown in a and b, after the addition of ethanol and water, APTES-CsPbBr3 maintained fluorescence for 32 hours, while HI-CsPbBr3 immediately became turbid and rapidly quenched.

[0055] (2) Preparation of eutectic encapsulation matrix Synthesis of (TPnA)M(dca)3 single crystals: A slow evaporation method was used. 2 mmol (0.502 g) manganese(II) nitrate tetrahydrate was dissolved in 10 mL of deionized water and placed at the bottom of a crystallization tube. 6 mmol (0.535 g) sodium dicyandiamide (NaDca) was dissolved in 10 mL of deionized water, and then mixed with a 10 mL ethanol solution of 2 mmol (0.757 g) tetrapentylammonium bromide (TPnA). This mixture was slowly added to the lower aqueous layer. The tube was sealed and allowed to evaporate at room temperature for one week, yielding colorless, transparent, blocky (TPnA)M(dca)3 single crystals.

[0056] Synthesis of Li(C2N3) modifier: 1.28 g Li2SO4·H2O and 1.78 g NaDca were dissolved separately in 8 mL of deionized water, mixed, and stirred at 50 °C for 60 minutes. After cooling, 80 mL of ethanol was added, and the mixture was stirred for 30 minutes. The Na2SO4 precipitate was removed by filtration. After rotary evaporation of the filtrate, the crude product was purified by recrystallization from tetrahydrofuran (THF) to obtain Li(C2N3).

[0057] Preparation of eutectic encapsulation matrix: 0.02 g of (TPnA)M(dca)3 single crystal was accurately weighed in an aluminum crucible and thoroughly ground and mixed with different masses of Li(C2N3) so that the molar ratio of Li(C2N3) to (TPnA)M(dca)3 was 0, 0.1, 0.2, 0.3 and 0.4, respectively, to obtain the corresponding eutectic encapsulation matrix.

[0058] The FT-IR spectrum of Li(C2N3) prepared in this embodiment is as follows: Figure 7 As shown in the figure, Li(C2N3) was successfully synthesized.

[0059] Differential scanning calorimetry (DSC) was used to record the DSC curves by heating from room temperature to 300 °C at a rate of 10 °C / min under an argon atmosphere at a rate of 150 mL / min. The DSC results for the eutectic encapsulation matrices containing different amounts of Li(C2N3) prepared in this example are shown below. Figure 8 As shown in the figure, with the increase of Li(C2N3) content in the eutectic encapsulation matrix, the melting peak of the prepared eutectic encapsulation matrix shifts to a lower temperature, as shown in Table 1 below: Table 1. Melting temperatures of eutectic encapsulation matrices containing different amounts of Li(C2N3).

[0060] (3) Preparation of perovskite composite materials 2.2 mg of the APTES-CsPbBr3 nanocrystalline powder prepared in step (1) and 19.8 mg of the (TPnA)M(dca)3 / Li(C2N3) eutectic mixture (10% loading) with a molar ratio of 0.4 prepared in step (2) were accurately weighed and thoroughly ground and mixed in a crucible. The mixture was placed in a DSC instrument and heated to 155 °C at a rate of 10 °C / min under an argon atmosphere of 150 mL / min, held for 2 minutes, and then rapidly cooled to room temperature to obtain a yellow perovskite composite material.

[0061] The TEM images and particle size distribution of the perovskite composite material prepared in this embodiment are shown below. Figure 9As shown in figures a and b, APTES-CsPbBr3 nanocrystals are uniformly dispersed in the encapsulation matrix, with an average size of 10.84 nm.

[0062] The XRD pattern of the perovskite composite material prepared in this embodiment is as follows: Figure 10 As shown, APTES-CsPbBr3 nanocrystals are completely encapsulated in an amorphous encapsulation matrix.

[0063] The perovskite composite material prepared in this embodiment, after grinding, exhibits the following fluorescence spectrum under 365 nm ultraviolet light excitation: Figure 11 As shown, the emission peak of the perovskite composite material is located at 518 nm, FWHM is 20 nm, and PLQY is 70%.

[0064] Further investigation was conducted on the water stability and light stability of the perovskite composite material prepared in this embodiment, as detailed below: The perovskite composite material prepared in this embodiment and APTES-CsPbBr3 nanocrystals were respectively immersed in water for 7 days, and the changes in fluorescence intensity were measured. The results are as follows. Figure 12 As shown, after immersing in water for 7 days, the fluorescence intensity of the perovskite composite material can be maintained at more than 80% of the initial value, while the fluorescence of the unencapsulated APTES-CsPbBr3 nanocrystals is significantly quenched after immersing in water for 1 day.

[0065] The perovskite composite material prepared in this embodiment and APTES-CsPbBr3 nanocrystals were simultaneously irradiated under strong blue light (λ = 452 nm, I = 200 mA) for continuous illumination, and their fluorescence intensity was measured periodically. The results are as follows: Figure 13 As shown in a and b, after 432 hours of blue light irradiation, the fluorescence intensity of the perovskite composite material remained at about 80% of its initial value, while the intensity of the unencapsulated APTES-CsPbBr3 nanocrystals dropped to 47% after 168 hours of blue light irradiation.

[0066] Therefore, it can be seen that the water stability and light stability of APTES-CsPbBr3 nanocrystals can be greatly improved after encapsulation with a eutectic encapsulation matrix.

[0067] Example 2: This example relates to the preparation of a perovskite composite material. The only difference from Example 1 is the heating and melting treatment in step (3), which is to heat the material to 85 °C at a rate of 10 °C / min and hold it for 15 minutes. All other conditions are the same as in Example 1, and the corresponding perovskite composite material is prepared.

[0068] Example 3: This example relates to the preparation of a perovskite composite material. The only difference from Example 1 is the heating and melting treatment in step (3), which is: heating to 100 °C at a rate of 10 °C / min and holding for 12 minutes. All other conditions are the same as in Example 1, and the corresponding perovskite composite material is prepared.

[0069] Example 4: This example relates to the preparation of a perovskite composite material. The only difference from Example 1 is the heating and melting treatment in step (3), which is to heat the material to 120 °C at a rate of 10 °C / min and hold it for 8 minutes. All other conditions are the same as in Example 1, and the corresponding perovskite composite material is prepared.

[0070] Example 5: This example relates to the preparation of a perovskite composite material. The only difference from Example 1 is the heating and melting treatment in step (3), which is: heating to 140 °C at a rate of 10 °C / min and holding for 5 minutes. All other conditions are the same as in Example 1, and the corresponding perovskite composite material is prepared.

[0071] The optical performance test results and water stability test results of the perovskite composite materials prepared in Examples 1-5 are summarized in Tables 2 and 3 below.

[0072] Table 2 shows the optical properties of perovskite composites prepared at different melting temperatures.

[0073] Table 3 shows the water stability test results of perovskite composites prepared at different melting temperatures.

[0074] As shown in Tables 2 and 3, the perovskite composite materials prepared at melting temperatures of 100-140 °C possess both excellent optical properties and water stability. More preferably, the melting temperature is controlled within the range of 100-120 °C.

[0075] Comparative Example 1: This comparative example relates to the preparation of a perovskite composite material. The only difference from Example 1 is that Li(C2N3) was not added to the encapsulation matrix (TPnA)M(dca)3. All other operations were the same, and the corresponding perovskite composite material was prepared.

[0076] The XRD pattern of the perovskite composite material prepared in this comparative example is as follows: Figure 14As shown in the figure, the unmodified (TPnA)M(dca)3 failed to form an amorphous glass phase after melting. Its XRD pattern still showed the main diffraction peaks of the raw material crystals, and the characteristic peak intensity of APTES-CsPbBr3 nanocrystals was weak, indicating that the nanocrystal coating effect was poor. Correspondingly, the perovskite composite material appeared dark yellow under sunlight, with a fluorescence emission peak at 520 nm, a full width at half maximum (FWHM) of 30 nm, and a PLQY of only 40%. In addition, its stability was poor; after being stored in water for 2 days, the fluorescence intensity dropped to 30% of the initial value.

[0077] Comparative Example 2: This comparative example relates to the preparation of a perovskite composite material. The only difference from Example 1 is that in step (2), an equimolar amount of Na (C2N3) is used to replace Li (C2N3) to prepare a eutectic encapsulation matrix. All other conditions are the same, and the corresponding perovskite composite material is prepared.

[0078] Figure 15 The DSC curves of (TPnA)M(dca)3 and the eutectic encapsulation matrix prepared in this comparative example are shown. As can be seen from the figure, when Na(C2N3) is used as a modifier, the melting temperature of (TPnA)M(dca)3 does not decrease significantly. In contrast, Li(C2N3) significantly lowers its melting point. This difference can be attributed to Li... + The ionic radius is extremely small (approximately 76 pm), much smaller than that of Na. + (Approximately 10:20 pm). The smaller Li + It can embed itself in the lattice of (TPnA)M(dca)3, forming a stronger coordination with the dca anion, thereby effectively disrupting the long-range order of the perovskite framework and leading to a decrease in melting point; while the larger Na... + It is difficult to embed into the crystal lattice, thus limiting the disturbance to the crystal structure.

[0079] Figure 16 The XRD patterns of the eutectic encapsulation matrix and perovskite composite material prepared in this comparative example are shown in the figure. As can be seen, the diffraction peak of the (TPnA)M(dca)3 crystal phase in the perovskite composite material still exists, and only a weak APTES-CsPbBr3 characteristic peak can be observed, indicating that the system failed to successfully transform into a glassy state. Correspondingly, this perovskite composite material emits only weak fluorescence under ultraviolet light excitation, with an emission peak at 520 nm, a full width at half maximum (FWHM) of 32 nm, and a PLQY as low as 35%. Stability tests show that its fluorescence intensity rapidly decays to 20% of its initial value after being stored in water for 2 days.

[0080] The above results demonstrate that Na(C2N3) cannot assist in the formation of a stable HOIPs glass matrix, resulting in poor performance of the prepared nanocrystalline composite material in both structure and properties.

[0081] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A perovskite composite material, characterized in that, The invention comprises lead halide perovskite nanocrystals modified with (3-aminopropyl)triethoxysilane and organic-inorganic hybrid perovskite glass; the (3-aminopropyl)triethoxysilane modified lead halide perovskite nanocrystals are completely encapsulated in the organic-inorganic hybrid perovskite glass. The chemical formula of the lead halide perovskite nanocrystals is CsPbX3, where X is Cl, Br, or I. The organic-inorganic hybrid perovskite glass comprises (TPnA)M(dca)3 and Li(C2N3), where TPnA is a tetrapentylammonium cation and M is selected from Mn. 2+ Fe 2+ Co 2+ One or more of them, where dca is a dicyandiamide anion.

2. The perovskite composite material according to claim 1, characterized in that, The mass ratio of (3-aminopropyl)triethoxysilane-modified lead halide perovskite nanocrystals to organic-inorganic hybrid perovskite glass in the perovskite composite material is 0.5:9.5-2:

8.

3. The perovskite composite material according to claim 1, characterized in that, The molar ratio of (TPnA)M(dca)3 to Li(C2N3) in the organic-inorganic hybrid perovskite glass is 1:(0.2-0.4).

4. The perovskite composite material according to claim 1, characterized in that, The photoluminescence quantum yield of the perovskite composite material is not less than 70%; the fluorescence intensity retention rate of the perovskite composite material after soaking in water for 7 days is greater than 60%; and the fluorescence intensity retention rate of the perovskite composite material after continuous blue light irradiation for 432 hours is greater than 75%.

5. A method for preparing a perovskite composite material as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Grind and mix (TPnA)M(dca)3 crystals with Li(C2N3) until homogeneous to form a eutectic mixture; S2. The lead halide perovskite nanocrystals modified with (3-aminopropyl)triethoxysilane are ground and mixed evenly with the eutectic mixture, and then heated and melted under an inert atmosphere. After complete melting, the perovskite composite material is obtained by cooling.

6. The method for preparing the perovskite composite material according to claim 5, characterized in that, In step S1, the preparation method of the (TPnA)M(dca)3 crystal is as follows: A metal nitrate is dissolved in water to obtain a metal nitrate solution; the metal ions in the metal nitrate are selected from Mn. 2 + Fe 2+ Co 2+ One or more of the following; Tetrapentylammonium bromide and sodium dicyandiamide were dissolved in a solvent to obtain a ligand solution; the solvent was a mixture of ethanol and water. The metal salt solution was transferred to a container, and the ligand solution was slowly added. The mixture was allowed to stand at room temperature to evaporate, thus obtaining the (TPnA)M(dca)3 crystals. The preparation method of Li(C2N3) is as follows: Sodium dicyandiamide was reacted with lithium sulfate in an aqueous solution, the precipitate was collected, washed, and recrystallized to obtain the Li(C2N3).

7. The method for preparing the perovskite composite material according to claim 5, characterized in that, In step S2, the preparation method of the (3-aminopropyl)triethoxysilane-modified lead halide perovskite nanocrystals is as follows: Cs2CO3 was mixed with oleic acid and 1-octadecene, and then degassed under vacuum at 80-130 °C. The mixture was then reacted at 140-160 °C under inert gas protection until the solution became clear, yielding a cesium oleate precursor solution. Lead halide was mixed with 1-octadecene, oleic acid, oleylamine, and (3-aminopropyl)triethoxysilane. After vacuum degassing at 80-130 °C, the mixture was injected into the cesium oleate precursor solution at 155-185 °C under inert gas protection. The mixture was reacted for 3-8 seconds and then immediately cooled in an ice-water bath. The mixture was then centrifuged to obtain the (3-aminopropyl)triethoxysilane-modified lead halide perovskite nanocrystals.

8. The method for preparing the perovskite composite material according to claim 5, characterized in that, In step S2, the heating and melting treatment is carried out at a temperature of 85-155 °C for 2-15 min.

9. The method for preparing the perovskite composite material according to claim 8, characterized in that, The heating and melting treatment is performed at a temperature of 100-125 ℃ for 8-12 min.

10. An optoelectronic device, characterized in that, The perovskite composite material comprising any one of claims 1-4 or any one of claims 5-9 prepared by the preparation method thereof.

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