Perovskite composite material and preparation method and application thereof

Abstract

The present application relates to a kind of perovskite composite material and its preparation method and application, including APTES modified lead halide perovskite nanocrystal and organic-inorganic hybrid perovskite glass;The APTES modified lead halide perovskite nanocrystal is completely encapsulated in organic-inorganic hybrid perovskite glass;The organic-inorganic hybrid perovskite glass includes (TPnA) M (dca) 3 And Li (C2N3).The present application realizes pre-stabilization treatment using APTES modified lead halide perovskite nanocrystal, then introduces Li (C2N3) Realize the low-temperature melting encapsulation of nanocrystal by organic-inorganic hybrid perovskite glass, under the synergistic effect of both, obtain composite material with high luminescence performance and high stability.The above-mentioned perovskite composite material containing CsPbBr3It can be used as green light conversion layer and commercial red powder and blue chip is integrated into WLED device, has good application prospect in solid-state lighting and display field.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of light-emitting materials, and particularly relates to a perovskite composite material and a preparation method and application thereof. BACKGROUND

[0002] All-inorganic lead halide perovskite nanocrystals (CsPbX3, X = Cl, Br, I) exhibit great potential in the next generation of display technology and solid-state lighting (such as backlight display, light-emitting diode LED, Mini / Micro-LED) due to their excellent optical properties, such as tunable emission spectrum, narrow full width at half maximum (FWHM), high photoluminescence quantum yield (PLQY), etc. However, the nanocrystals are prone to reabsorption effect in their powder form, resulting in reduced fluorescence efficiency; more importantly, they are essentially ionic crystals, which are unstable in structure and prone to degradation when exposed to water, oxygen, light, heat and other environmental conditions for a long time, which seriously restricts their practical industrial application.

[0003] To overcome the above stability problems, current research mainly focuses on two technical paths: surface engineering strategy and matrix encapsulation strategy. Specifically as follows:

[0004] (1) Surface modification strategy: This strategy can improve the colloidal stability and short-term resistance of the nanocrystals to a certain extent by modifying the surface of the nanocrystals with organic ligands. However, this protective layer is relatively fragile and can easily fail in long-term or harsh service environments (such as high temperature and high humidity), which cannot provide durable and reliable protection for the nanocrystals.

[0005] (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 can directly cause irreversible thermal degradation and fluorescence quenching of CsPbX3 nanocrystals, making them lose their original high-performance luminescent properties.

[0006] (3) MOF glass encapsulation strategy: As a new solution, this strategy attempts to mix perovskite precursors with metal-organic framework materials and encapsulate them through liquid-phase sintering technology. Although its processing temperature (about 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 can easily introduce by-products, affecting the purity and optical properties of the material, and there are obvious bottlenecks in process controllability and large-scale preparation.

[0007] (4) Emerging hybrid perovskite glass encapsulation strategy: In recent years, organic-inorganic hybrid perovskite (HOIPs) has become a potential encapsulation matrix due to its low melting temperature. For example, the melting temperature of certain HOIPs matrix can be as low as 143 °C to 155 °C. Nevertheless, for unprotected CsPbX3 nanocrystals, this temperature window can still cause surface damage and fluorescence quenching of the nanocrystals during the encapsulation process, making it difficult to achieve perfect encapsulation while maintaining high luminescent efficiency.

[0008] In summary, the current strategies for improving the stability of all-inorganic lead halide perovskite nanocrystals all have their own limitations: insufficient surface protection or incompatible encapsulation process temperature and thermal stability of perovskite nanocrystals. Therefore, there is an urgent need in the art to develop a completely new encapsulation technology and material system that can achieve melting and molding at relatively low temperatures, thereby providing a dense and robust encapsulation protection layer for the nanocrystals while completely maintaining their original high luminescent performance, and ultimately obtaining a perovskite composite material with high luminescent efficiency and excellent environmental stability. SUMMARY

[0009] To solve the problem of reabsorption effect and environmental instability of all-inorganic lead halide perovskite nanocrystals, and the problem of insufficient surface protection or incompatible encapsulation process temperature and thermal stability of perovskite nanocrystals in the existing strategies for improving the stability of all-inorganic lead halide perovskite nanocrystals, the present application provides a perovskite composite material and a preparation method and application thereof. The perovskite composite material is prepared by modifying lead halide perovskite nanocrystals with (3-aminopropyl) triethoxysilane (APTES) to achieve pre-stabilization, and then introducing Li(C2N3) to achieve low-temperature melting encapsulation of the nanocrystals by organic-inorganic hybrid perovskite glass. Under the synergistic effect of the two, a perovskite composite material with high PLQY (≥70%) and excellent environmental stability (water resistance, light resistance, and heat resistance) is obtained.

[0010] Specifically, the following technical solutions are provided:

[0011] The first aspect of the present application provides a perovskite composite material, comprising (3-aminopropyl) triethoxysilane modified lead halide perovskite nanocrystals 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,

[0012] The chemical formula of the lead halide perovskite nanocrystals is CsPbX3, and X is Cl, Br or I;

[0013] The organic-inorganic hybrid perovskite glass comprises (TPnA)M(dca)3 and Li(C2N3), TPnA is a tetrapentyl ammonium cation, M is selected from one or more of Mn, Fe, Co, and dca is a dicyanamide anion.

[0014] The present application improves the intrinsic stability of nanocrystals by APTES modification, reduces the melting temperature of the matrix by Li(C2N3) modification, and realizes HOIPs glass packaging at a temperature much lower than that of traditional methods. Through the synergistic effect of the three, the unification of high performance and high stability of nanocrystals is realized. Specifically as follows:

[0015] Firstly, the present application uses APTES as a ligand to modify the surface of CsPbX3 nanocrystals to improve the intrinsic stability of nanocrystals. The mechanism lies in that the -NH2 group of APTES can form strong hydrogen bonds with halogen ions in nanocrystals, inhibit halogen migration, and at the same time, strong affinity reduces surface phonons, weakens exciton-phonon coupling, thereby pre-assigning nanocrystals with excellent thermal stability and solvent stability before subsequent packaging.

[0016] Secondly, HOIPs material with general formula (TPnA)M(dca)3 is selected as the packaging matrix. This kind of material itself has a relatively low melting temperature (<160 °C), and after melting, it can form a stable amorphous glass, providing an ideal protective shell for nanocrystals.

[0017] More importantly, the introduction of eutectic modifier Li(C2N3) in the packaging matrix material can form a low 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 of the packaging process, thereby effectively avoiding the thermal damage of nanocrystals.

[0018] Further, 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.

[0019] In the present application, if the content of the (3-aminopropyl) triethoxysilane modified lead halide perovskite nanocrystals in the perovskite composite is too low, a large amount of perovskite quantum dots may be quenched during the melting process, resulting in weak fluorescence intensity; but if the content of the (3-aminopropyl) triethoxysilane modified lead halide perovskite nanocrystals is too high, the nanocrystals will have a reabsorption effect, resulting in low PLQY. Preferably, the content of the (3-aminopropyl) triethoxysilane modified lead halide perovskite nanocrystals in the perovskite composite is controlled in the range of 5%-20% to obtain a perovskite composite with high fluorescence intensity and high PLQY.

[0020] Further, 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), for example 1:0.2, 1:0.3, 1:0.4, and more preferably 1:0.4. Further increasing the amount of Li(C2N3) will not further reduce the melting temperature, but on the contrary, too much modifier will cause the material properties to deviate towards the modifier. Excess Li(C2N3) cannot be uniformly incorporated 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 extremely susceptible to external ion interference. Excess Li(C2N3) may dissociate a large amount of Li + and (C2N3) - ions in the molten state. These ions may interact or ion exchange with the halide anions in the perovskite, further damaging the structural integrity of the nanocrystals. Therefore, in order to effectively reduce the melting temperature of the encapsulation matrix while reducing the impact on the stability of the HOIPs glass and the structure of the nanocrystals, the molar ratio of (TPnA)M(dca)3 to Li(C2N3) in the organic-inorganic hybrid perovskite glass is preferably controlled in the range of 1:(0.2-0.4).

[0021] Further, the photoluminescence quantum yield of the perovskite composite is not less than 70%.

[0022] Further, the fluorescence intensity retention rate of the perovskite composite after soaking in water for 7 days is greater than 60%.

[0023] Further, the fluorescence intensity retention rate of the perovskite composite after 432 hours of continuous blue light irradiation is greater than 75%, with the test conditions being strong blue light with λ = 452 nm and I = 200 mA.

[0024] Further, the perovskite composite has an emission wavelength of 515-518 nm and an emission half-peak width of 18-20 nm.

[0025] The second aspect of the present application provides a preparation method of the perovskite composite of the first aspect, comprising the following steps:

[0026] S1, uniformly grinding and mixing (TPnA)M(dca)3 crystals and Li(C2N3) to form a eutectic mixture;

[0027] S2, uniformly grinding and mixing (3-aminopropyl)triethoxysilane modified lead halide perovskite nanocrystals and the eutectic mixture, and performing heating and melting treatment under an inert atmosphere, and obtaining the perovskite composite after complete melting and cooling.

[0028] Further, in step S1, the preparation method of the (TPnA)M(dca)3 crystals is as follows:

[0029] dissolving a metal nitrate in water to obtain a metal nitrate solution; the metal ions in the metal nitrate are selected from one or more of Mn 2+ , Fe 2+ , Co 2+ ;

[0030] dissolving tetrapentylammonium bromide and sodium dicyanamide in a solvent to obtain a ligand solution; the solvent is a mixed solvent of ethanol and water;

[0031] transferring the metal salt solution into a container, slowly adding the ligand solution, and standing at room temperature to volatilize to obtain the (TPnA)M(dca)3 crystals.

[0032] Further, in step S1, the preparation method of the Li(C2N3) is as follows: reacting sodium dicyanamide and lithium sulfate in an aqueous solution, collecting the precipitate, and washing and recrystallizing to obtain the Li(C2N3); preferably, the washing solvent is ethanol, and the recrystallization solvent is tetrahydrofuran.

[0033] Further, in step S2, the preparation method of the (3-aminopropyl)triethoxysilane modified lead halide perovskite nanocrystals is as follows:

[0034] mixing Cs2CO3, oleic acid and 1-octadecene, vacuum degassing at 80-130 ℃ (for example, 120 ℃), and then reacting at 140-160 ℃ (for example, 150 ℃) under inert gas protection until clear to obtain a cesium oleate precursor solution;

[0035] The lead halide is mixed with 1-octadecene, oleic acid, oleylamine, (3-aminopropyl)triethoxysilane, vacuum degassed at 80-130 ℃ (for example, 120 ℃), and then the cesium oleate precursor solution is injected at 155-185 ℃ (for example, 160 ℃) under inert gas protection. The reaction is immediately cooled in an ice water bath after 3-8 seconds (for example, 5 seconds), and centrifugation is performed to obtain the (3-aminopropyl)triethoxysilane-modified lead halide perovskite nanocrystals.

[0036] Further, in step S2, the temperature of the heating and melting treatment is preferably 85-155 ℃, for example, 85 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, etc., and the time is preferably 2-15 min, for example, 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 above-mentioned temperatures or times. The time here is the holding time, for example, heating to 155 ℃ and holding for 2 min.

[0037] More preferably, the temperature of the heating and melting treatment is 100-125 ℃, and the time is 8-12 min.

[0038] Further, in step S2, the cooling is preferably rapid cooling, so that the encapsulation matrix forms an amorphous glass.

[0039] In some preferred embodiments of the present application, the temperature is programmed to increase to the melting temperature at a rate of 10 °C / min.

[0040] The third aspect of the present application provides a photoelectric device comprising the perovskite composite material of the first aspect or the perovskite composite material prepared by the preparation method of the second aspect.

[0041] Further, the photoelectric device comprises a light-emitting diode, and the perovskite composite material is used as a green light-emitting conversion layer and integrated with a red light-emitting material (such as CdSe@ZnS quantum dots) on a blue light LED chip (such as λ = 455 nm). Green light and red light are generated by blue light excitation, mixed to form white light, thereby constructing a high-performance and high-stability white diode device.

[0042] Compared with the prior art, the present application has the following beneficial effects:

[0043] 1、The present application reduces the melting temperature of the packaging matrix by modifying Li(C2N3), so that the packaging melting temperature is reduced to a minimum of 83°C, so that the packaging of HOIPs glass on nanocrystals can be achieved at a temperature much lower than that of traditional methods; in addition, the modification of lead halide perovskite nanocrystals by APTES can greatly retain the fluorescence performance of the nanocrystals after packaging, so that the photoluminescence quantum yield of the peroviskite composite material is not less than 70%, which is much higher than that of the traditional glass packaging product (<50%) which is seriously quenched due to high temperature.

[0044] 2、The peroviskite composite material provided by the present application has high luminescence performance and excellent environmental stability, specifically including the following points:

[0045] (1) High luminescence performance: the emission peak of the peroviskite composite material is located at 515-518 nm, the half-peak width is as narrow as 18-20 nm, and the color purity is high;

[0046] (2) Excellent water resistance: after the peroviskite composite material is directly immersed in water for 7 days, the fluorescence intensity can still maintain more than 80% of the initial value; the fluorescence of the APTES-CsPbBr3 nanocrystals without packaging is significantly weakened and rapidly quenched in water within 24 hours, and the fluorescence intensity of the APTES-CsPbBr3 nanocrystals packaged by (TPnA)M(dca)3 directly decreases to 30% of the initial value after being immersed in water for 2 days.

[0047] (3) Excellent light stability: after 432 hours (18 days) of continuous irradiation under 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 APTES-CsPbBr3 nanocrystals without packaging is attenuated to 47% of the initial value after 168 hours (7 days).

[0048] (4) Excellent thermal stability: the fluorescence intensity of the APTES-CsPbBr3 nanocrystals before packaging can still maintain 96% after being heated at 85°C for 8 hours; under the same conditions, the fluorescence intensity of the HI-CsPbBr3 nanocrystals prepared by traditional hot injection method is only 3% after 8 hours, which highlights the double stabilization effect of APTES modification and glass packaging.

[0049] 3、The present application also provides a method for preparing the above-mentioned peroviskite composite material, which does not require complex high-temperature smelting and annealing equipment, and has simple and easy-to-control preparation process, and is suitable for industrial mass production.

[0050] 4、The peroviskite composite material provided by the present application can be used as a green light conversion layer, and is integrated with commercial red powder and blue light chips to form a WLED device. The luminous efficiency of the device reaches 85.2 lm·W under a driving current of 10 mA.-1 The color coordinates are (0.31, 0.33), which is very close to the standard white light, showing its great practical application value in the field of solid-state lighting and display. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 a is the TEM image of APTES-CsPbBr3 nanocrystals prepared in Example 1, the scale bar is 50 nm, and the inset is the corresponding HRTEM image, the scale bar is 5 nm; b is the particle size distribution graph of APTES-CsPbBr3 nanocrystals prepared in Example 1;

[0052] Figure 2 is the XRD pattern of APTES-CsPbBr3 prepared in Example 1 and the comparison graph of the standard card (ICSD#01-072-7929) of orthorhombic CsPbBr3;

[0053] Figure 3 is the fluorescence emission and ultraviolet-visible absorption spectrum of APTES-CsPbBr3 nanocrystals prepared in Example 1, and the inset is the photo of the nanocrystal toluene dispersion under sunlight (left) and 365 nm ultraviolet light (right);

[0054] Figure 4 a is the FT-IR spectrum of APTES-CsPbBr3 nanocrystals and HI-CsPbBr3 nanocrystals prepared in Example 1, and the vertical dashed line indicates the Si-O-Si characteristic vibration peak in APTES-CsPbBr3 nanocrystals; b is the H NMR spectrum of APTES ligand, APTES-CsPbBr3 prepared in Example 1 and HI-CsPbBr3; 1 H NMR spectrum;

[0055] Figure 5 a is the normalized fluorescence intensity change of APTES-CsPbBr3 and HI-CsPbBr3 nanocrystals prepared in Example 1 during the heat aging process at 85 °C, b is the fluorescence photo of APTES-CsPbBr3 and HI-CsPbBr3 nanocrystal films prepared in Example 1 after heat aging for 0 h and 8 h under ultraviolet lamp irradiation;

[0056] Figure 6 a is the photo of the ethanol dispersion of APTES-CsPbBr3 and HI-CsPbBr3 nanocrystals prepared in Example 1 under the fluorescent lamp and ultraviolet lamp at the initial and after standing for 32 h, b is the photo of the water dispersion of APTES-CsPbBr3 and HI-CsPbBr3 nanocrystals prepared in Example 1 under the fluorescent lamp and ultraviolet lamp at the initial and after standing for 32 h;

[0057] Figure 7FT-IR spectra of Li(C2N3) prepared for Example 1, Na(C2N3) prepared for Comparative Example 2, and Li(C2N3) reported in the literature;

[0058] Figure 8 DSC curves of eutectic encapsulation matrix containing different content of Li(C2N3) prepared for Example 1;

[0059] Figure 9 TEM images of perovskite composite prepared for Example 1; b is the particle size distribution of perovskite composite prepared for Example 1;

[0060] Figure 10 XRD patterns of perovskite composite prepared for Example 1 and comparison with orthorhombic CsPbBr3 standard card (ICSD #01-072-7929);

[0061] Figure 11 Fluorescence spectra of perovskite composite prepared for Example 1 under 365 nm UV light excitation, and the inset is the luminescence photo under the corresponding UV lamp irradiation;

[0062] Figure 12 Fluorescence stability comparison of perovskite composite prepared for Example 1 and unencapsulated APTES-CsPbBr3 nanocrystals after storage in aqueous environment for one week;

[0063] Figure 13 a is the change of fluorescence intensity of perovskite composite prepared for Example 1 under strong blue light irradiation (λ = 452 nm, I = 200 mA) with irradiation time; b is the change of fluorescence intensity of unencapsulated APTES-CsPbBr3 nanocrystals under strong blue light irradiation (λ = 452 nm, I = 200 mA) with irradiation time;

[0064] Figure 14 XRD patterns of perovskite composite of (TPnA)M(dca)3 and Comparative Example 1 without adding Li(C2N3) in the encapsulation matrix (TPnA)M(dca)3, and the inset is the photo of perovskite composite under sunlight (left) and 365 nm UV light (right) irradiation;

[0065] Figure 15 DSC curves of perovskite composite of (TPnA)M(dca)3 and Comparative Example 2 using Na(C2N3) as the encapsulation matrix modifier;

[0066] Figure 16 XRD patterns of eutectic encapsulation matrix and perovskite composite prepared for Comparative Example 2, and the inset is the fluorescence photo of perovskite composite under UV light irradiation;

[0067] TPnAMndca3 is (TPnA)Mn(dca)3. DETAILED DESCRIPTION

[0068] The present application will be further described with reference to the drawings and specific examples in order to make the application better understood and to enable its practical implementation by those skilled in the art. The examples are, however, not to be construed as limiting the application.

[0069] 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 application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used in the description herein, the expression "comprising" or "containing" can also be replaced by the closed expressions "consisting of" or "consisting essentially of".

[0070] The instruments used for the characterization of the morphology, structure and properties of the materials prepared in the following examples and comparative examples are as follows:

[0071] Transmission electron microscopy (TEM, TALOS 200X, accelerating voltage 220 kV) and high-resolution transmission electron microscopy (HRTEM) were used to observe the morphology, size and lattice fringes of the nanocrystals.

[0072] X-ray diffractometer (XRD, Empyrean, PANalytical, Cu K a radiation source, λ = 1.54056 Å) was used to analyze the phase and crystal structure.

[0073] Fluorescence spectrometer (FLUOROMAX-4, xenon lamp light source) was used to measure photoluminescence (PL) spectra; UV-visible spectrophotometer (Evolution 220) was used to measure absorption spectra.

[0074] Absolute quantum yield measurement system (Quantaurus-QY Plus C13534-11, HAMAMATSU) was used to measure photoluminescence quantum yield (PLQY).

[0075] Thermogravimetric analyzer (TGA, SDT-Q600, TA Instruments, argon atmosphere, heating rate 10 °C / min) was used to analyze thermal stability; differential scanning calorimeter (DSC, Netzsch 214 Polyma, argon atmosphere, heating rate 10 °C / min) was used to analyze melting behavior.

[0076] Fourier transform infrared spectrometer (FTIR, Bruker Vertex V70) and nuclear magnetic resonance spectrometer (NMR, Bruker Avance III 400) were used to analyze the chemical structure of the materials. 1¹H NMR (Agilent DD2-600) was used to analyze surface ligands and chemical structures.

[0077] Example 1: This example relates to the preparation of a perovskite composite material, as detailed below:

[0078] (1) Preparation of lead halide perovskite (APTES-CsPbBr3) nanocrystals modified with (3-aminopropyl)triethoxysilane

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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).

[0084] The fluorescence emission and UV-Vis absorption spectra of the APTES-CsPbBr3 nanocrystals prepared in this example are shown in FIG. 1. As can be seen from 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%. Figure 3

[0085] In addition, the FT-IR spectrum and 1 H NMR spectrum of the APTES-CsPbBr3 nanocrystals prepared in this example are shown in FIG. 2a and FIG. 2b, respectively. As can be seen from the figures, the APTES is successfully modified on the surface of the nanocrystals. Figure 4

[0086] To further study the advantage of the APTES-CsPbBr3 nanocrystals prepared in this example in stability compared with the CsPbBr3 nanocrystals (HI-CsPbBr3) prepared by the conventional hot injection method, the APTES-CsPbBr3 nanocrystals and the HI-CsPbBr3 nanocrystals were subjected to 85 °C high-temperature storage and polar solvent stability tests, respectively, as follows:

[0087] The preparation of the HI-CsPbBr3 is as follows:

[0088] In a 50 mL three-necked flask, 0.2 g of Cs2CO3, 1.25 mL of OA and 20 mL of ODE were mixed, vacuum degassed at 120 °C for 1 hour, and then heated to 150 °C under N2 protection to prepare a Cs-OA precursor solution. Another 25 mL three-necked flask was taken, 1.23 mmol of OAm, 1.17 mmol of OA, 5 mL of ODE and 0.073 g of PbBr2 were added, and heated to 160 °C under nitrogen atmosphere. Then, 0.4 mL of hot Cs-OA precursor solution was quickly injected. After 5 seconds of reaction, it was immediately cooled to room temperature with an ice water bath. The obtained reaction solution was centrifuged at 9000 rpm for 5 minutes, the supernatant was collected and dispersed in 10 mL of hexane to obtain the HI-CsPbBr3 nanocrystal comparative sample. The FT-IR spectrum and 1 H NMR spectrum of the HI-CsPbBr3 nanocrystals are shown in FIG. 3a and FIG. 3b, respectively. As can be seen from the figures, the HI-CsPbBr3 nanocrystals were successfully prepared. Figure 4

[0089] The results of the 85 °C high-temperature storage test are shown in FIG. 4. Figure 5 ​​​As shown in a, b of FIG. 6, after APTES-CsPbBr3 nanocrystals were heated at 85 °C for 8 hours, the fluorescence intensity remained 96%, and the APTES-CsPbBr3 nanocrystal film still maintained high fluorescence intensity after being irradiated by a UV lamp for 8 hours. However, after HI-CsPbBr3 nanocrystals were heated at 85 °C for 8 hours, the fluorescence intensity remained only 3%, and the HI-CsPbBr3 nanocrystal film was completely quenched after being irradiated by a UV lamp for 8 hours.

[0090] The results of the polar solvent stability test are shown in FIG. 5. Figure 6 As shown in a, b of FIG. 6, after APTES-CsPbBr3 nanocrystals were heated at 85 °C for 8 hours, the fluorescence intensity remained 96%, and the APTES-CsPbBr3 nanocrystal film still maintained high fluorescence intensity after being irradiated by a UV lamp for 8 hours. However, after HI-CsPbBr3 nanocrystals were heated at 85 °C for 8 hours, the fluorescence intensity remained only 3%, and the HI-CsPbBr3 nanocrystal film was completely quenched after being irradiated by a UV lamp for 8 hours.

[0091] (2) Preparation of a co-crystal encapsulation matrix

[0092] Synthesis of (TPnA)M(dca)3 single crystal: solution slow evaporation method. 2 mmol (0.502 g) of 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) of sodium dicyanamide (NaDca) was dissolved in 10 mL of deionized water, and then mixed with 2 mmol (0.757 g) of tetrapentylammonium bromide (TPnA) in 10 mL of ethanol. The mixture was slowly added to the lower aqueous solution. The tube was sealed and left to evaporate at room temperature for one week to obtain colorless transparent block (TPnA)M(dca)3 single crystal.

[0093] Synthesis of Li(C2N3) modifier: 1.28 g of Li2SO4·H2O and 1.78 g of NaDca were dissolved in 8 mL of deionized water, respectively, and mixed. After stirring at 50 °C for 60 minutes, 80 mL of ethanol was added. After stirring for 30 minutes, Na2SO4 precipitate was removed by filtration. After rotary evaporation of the filtrate, the crude product was recrystallized with tetrahydrofuran (THF) to obtain Li(C2N3).

[0094] Preparation of a co-crystal encapsulation matrix: 0.02 g of (TPnA)M(dca)3 single crystal was accurately weighed in an aluminum crucible and mixed with different amounts of Li(C2N3) to obtain a co-crystal encapsulation matrix with a molar ratio of Li(C2N3) to (TPnA)M(dca)3 of 0, 0.1, 0.2, 0.3, and 0.4, respectively.

[0095] The FT-IR spectrum of Li(C2N3) prepared in this example is shown in FIG. 4. Figure 7 As can be seen from the figure, Li(C2N3) was successfully synthesized.

[0096] DSC curves were recorded using a differential scanning calorimeter (DSC) under an argon atmosphere at a rate of 10 °C / min from room temperature to 300 °C. The DSC results of the eutectic encapsulation matrix containing different contents of Li(C2N3) prepared in this example are shown in FIG. 1. As can be seen from the figure, with the increase of the content of Li(C2N3) in the eutectic encapsulation matrix, the melting peak of the prepared eutectic encapsulation matrix moves to low temperature, as shown in Table 1 below: Figure 8 As can be seen from the figure, with the increase of the content of Li(C2N3) in the eutectic encapsulation matrix, the melting peak of the prepared eutectic encapsulation matrix moves to low temperature, as shown in Table 1 below:

[0097] Table 1 Melting temperature of eutectic encapsulation matrix containing different contents of Li(C2N3)

[0098]

[0099] (3) Preparation of perovskite composite material

[0100] Accurately weigh 2.2 mg of APTES-CsPbBr3 nanocrystal powder prepared in step (1) and 19.8 mg of (TPnA)M(dca)3 / Li(C2N3) eutectic mixture with a molar ratio of 0.4 prepared in step (2) (loading amount 10%) in a crucible, and mix them uniformly. Put the mixture into a DSC instrument, and heat it to 155 °C at a rate of 10 °C / min under an argon atmosphere at a rate of 150 mL / min, keep it for 2 minutes, and then cool it to room temperature quickly to obtain a yellow perovskite composite material.

[0101] The TEM image and particle size distribution of the perovskite composite material prepared in this example are shown in FIG. 2a and FIG. 2b, respectively. As can be seen from the figure, the APTES-CsPbBr3 nanocrystals are uniformly dispersed in the encapsulation matrix, and the average size is 10.84 nm. Figure 9

[0102] The XRD spectrum of the perovskite composite material prepared in this example is shown in FIG. 3. The APTES-CsPbBr3 nanocrystals are completely encapsulated in the amorphous encapsulation matrix. Figure 10 The fluorescence spectrum of the perovskite composite material prepared in this example after grinding under 365 nm ultraviolet light excitation is shown in FIG. 4. The emission peak of the perovskite composite material is at 518 nm, the FWHM is 20 nm, and the PLQY is 70%.

[0103] Figure 11 Further study the water stability and light stability of the perovskite composite material prepared in this example, as follows:

[0104] Further study the water stability and light stability of the perovskite composite material prepared in this example, as follows:

[0105] ​​The perovskite composite prepared in this example and APTES-CsPbBr3nanocrystals were respectively immersed in water for 7 days, and the change in fluorescence intensity was measured, and the results are shown in Figure 12 As shown in the figure, after the perovskite composite was immersed in water for 7 days, the fluorescence intensity could be maintained at more than 80% of the initial value, while the un-encapsulated APTES-CsPbBr3nanocrystals were immersed in water for 1 day, and the fluorescence was significantly quenched.

[0106] The perovskite composite prepared in this example and APTES-CsPbBr3nanocrystals were respectively simultaneously placed under strong blue light (λ = 452 nm, I = 200 mA) for continuous irradiation, and the fluorescence intensity was measured periodically, and the results are shown in Figure 13 As shown in a, b in the figure, after the perovskite composite was irradiated by blue light for 432 hours, the fluorescence intensity was maintained at about 80% of the initial value, while the un-encapsulated APTES-CsPbBr3nanocrystals were irradiated by blue light for 168 hours, and the intensity was reduced to 47%.

[0107] Therefore, it can be known that after the APTES-CsPbBr3nanocrystals are encapsulated by the eutectic encapsulation matrix, the water stability and light stability of the APTES-CsPbBr3nanocrystals can be greatly improved.

[0108] Example 2: This example relates to the preparation of a perovskite composite, which is only different from example 1 in that the heating and melting treatment in step (3) is specifically: heating at a rate of 10 °C / min to 85 °C, and keeping for 15 minutes, and the rest of the conditions are consistent with example 1, and the corresponding perovskite composite is prepared.

[0109] Example 3: This example relates to the preparation of a perovskite composite, which is only different from example 1 in that the heating and melting treatment in step (3) is specifically: heating at a rate of 10 °C / min to 100 °C, and keeping for 12 minutes, and the rest of the conditions are consistent with example 1, and the corresponding perovskite composite is prepared.

[0110] Example 4: This example relates to the preparation of a perovskite composite, which is only different from example 1 in that the heating and melting treatment in step (3) is specifically: heating at a rate of 10 °C / min to 120 °C, and keeping for 8 minutes, and the rest of the conditions are consistent with example 1, and the corresponding perovskite composite is prepared.

[0111] Example 5: This example relates to the preparation of a perovskite composite, which is only different from example 1 in that the heating and melting treatment in step (3) is specifically: heating at a rate of 10 °C / min to 140 °C, and keeping for 5 minutes, and the rest of the conditions are consistent with example 1, and the corresponding perovskite composite is prepared.

[0112] The optical performance test results and water stability test results of the perovskite composites prepared in Examples 1-5 above are respectively summarized in Tables 2 and 3 below.

[0113] Table 2 is the optical performance test results of the perovskite composites prepared at different melting temperatures

[0114]

[0115] Table 3 is the water stability test results of the perovskite composites prepared at different melting temperatures

[0116]

[0117] As can be seen from Tables 2 and 3, the perovskite composites prepared at a melting temperature of 100-140 °C have excellent optical performance and water stability, and more preferably, the melting temperature is controlled within the range of 100-120 °C.

[0118] Comparative Example 1: This comparative example relates to the preparation of a perovskite composite, which is different from Example 1 only in that Li(C2N3) is not added in the encapsulation matrix (TPnA)M(dca)3, and the rest of the operations are consistent, and the corresponding perovskite composite is prepared.

[0119] The XRD pattern of the perovskite composite prepared in this comparative example is shown in Figure 14 As can be seen from the figure, (TPnA)M(dca)3 without modification by Li(C2N3) failed to form an amorphous glass after melting, and its XRD pattern is still dominated by the crystal diffraction peaks of the raw materials, and the characteristic peak intensity of APTES-CsPbBr3 nanocrystals is weak, indicating that the nanocrystals are not well coated. Correspondingly, the perovskite composite is dark yellow under sunlight, the fluorescence emission peak is located at 520 nm, the half-peak width is 30 nm, and the PLQY is only 40%. In addition, it has poor stability, and after being stored in water for 2 days, the fluorescence intensity is reduced to 30% of the initial value.

[0120] Comparative Example 2: This comparative example relates to the preparation of a perovskite composite, which is different from Example 1 only in that in step (2), an equimolar amount of Na(C2N3) is used instead of Li(C2N3) to prepare the eutectic encapsulation matrix, and the rest of the conditions are consistent, and the corresponding perovskite composite is prepared.

[0121] Figure 15DSC curves of the eutectic encapsulation matrix prepared for (TPnA)M(dca)3 and the present comparative example, from which it can be seen that the melting temperature of (TPnA)M(dca)3 does not decrease significantly when Na(C2N3) is used as the modifier. In contrast, Li(C2N3) can significantly reduce the melting point. This difference can be attributed to Li + a much smaller ionic radius (about 76 pm), much smaller than Na + (about 102 pm). Smaller Li + can be embedded in the lattice of (TPnA)M(dca)3, forming a stronger coordination with dca anions, thus effectively destroying the long-range order of the perovskite framework, resulting in a decrease in melting point; while the larger Na + is difficult to embed in the lattice, so the disturbance to the crystal structure is limited.

[0122] Figure 16 XRD patterns of the eutectic encapsulation matrix and perovskite composite material prepared for the present comparative example, from which it can be seen that the crystal phase diffraction peak of (TPnA)M(dca)3 in the perovskite composite material still exists, and only weak APTES-CsPbBr3 characteristic peaks can be observed, indicating that the system has not been successfully converted to a glass state. Correspondingly, the perovskite composite material only emits weak fluorescence under ultraviolet excitation, with an emission peak at 520 nm, a half-peak width of 32 nm, and a PLQY as low as 35%. Stability tests show that its fluorescence intensity decays to 20% of the initial value after 2 days of storage in water.

[0123] The above results prove that Na(C2N3) cannot assist in forming a stable HOIPs glass matrix, resulting in the prepared nanocrystal composite material exhibiting poor structure and performance.

[0124] The above-described examples are only preferred examples for fully illustrating the present application, and the protection scope of the present application is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present application are within the protection scope of the present application. The protection scope of the present application is subject to 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 Mn 2+ dca is the 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 ion in the metal nitrate is Mn. 2+ ; 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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