Polymerizable ligand, preparation method and application thereof, caesium lead halide perovskite nanocrystal based on ligand modification and preparation method of caesium lead halide perovskite nanocrystal

Abstract

The invention discloses a polymerizable ligand and a preparation method and application thereof, and a caesium lead halide perovskite nanocrystal based on ligand modification and a preparation method thereof. According to the preparation method, 4-vinyl benzyl chloride, L-cysteine, oleic acid, thionyl chloride and other raw materials are subjected to a thioether Williamson reaction, an SOCl2 mediated acylating chlorination reaction and an amidation reaction to generate a polymerizable ligand, and the photoluminescence intensity of the perovskite nanocrystal prepared by the preparation method is almost unchanged in five times of heating-cooling circulation; the nanocrystalline polymer film prepared by the invention has excellent stability to ultraviolet light, and has important significance for widening the application field of the material.

Description

Technical Field

[0001] This invention relates to the field of perovskite nanocrystal technology, and in particular to a polymerizable ligand, its preparation method and uses, and cesium lead halide perovskite nanocrystals modified based on the ligand and their preparation method. Background Technology

[0002] Lead halide perovskite nanocrystals have broad application prospects in fields such as solar cells, light-emitting diodes, photodetectors, lasers, and sensors due to their excellent optical properties, including high absorption coefficient, high fluorescence quantum yield (PLQY), and tunable band gap. Among them, cesium lead halide perovskite nanocrystals are one of the research hotspots.

[0003] However, the instability of perovskite nanocrystals severely hinders their practical commercial application. In the crystal structure of perovskite, the lead halide octahedron [PbX6]... 4- Or [PbX8] 6- Different arrangements in the crystal structure can cause cesium lead halide to exhibit zero-dimensional, one-dimensional, two-dimensional, and three-dimensional structures at the molecular level. Due to the soft lattice characteristics of the perovskite crystal structure, phase transitions can easily occur between cesium lead halide perovskites of different dimensions. Studies have shown that low-dimensional (0D-2D) perovskite nanocrystals have high stability, and solar cells made of low-dimensional-three-dimensional mixed metal halide perovskites have high stability.

[0004] Currently, existing technologies include ligand-mediated methods to add the organic amine salt tetra-n-octylammonium bromide (TOAB) to pre-synthesized CsPbBr3NCs, which can promote the transformation of 3D CsPbBr3NCs into lead-batter-poor 0D Cs4PbBr6NCs, i.e., the formation of Cs4PbBr6 crystal nuclei [PbBr4]. 2- Inducing a phase transition can produce some low-dimensional crystal structures, but when too much TOAB is added to the system, the nanocrystals undergo a rapid phase transition, the fluorescence disappears quickly, and the photophysical properties and stability of the nanocrystals are affected. Summary of the Invention

[0005] The main objective of this invention is to provide a polymerizable ligand, its preparation method and uses, and cesium lead halide perovskite nanocrystals modified with the ligand and their preparation method, aiming to solve at least one of the above-mentioned technical problems.

[0006] To achieve the above objectives, the present invention provides a polymerizable ligand having a structure as shown in Formula I:

[0007] Formula I.

[0008] The present invention also provides a method for preparing the above-mentioned polymerizable ligand, comprising the following steps: (1) L-cysteine ​​and triethylamine were dissolved in a solvent, and 4-vinylbenzyl chloride was added to react. The resulting solid product was then washed and dried to obtain a white powder product. (2) Dissolve the white powder product and triethylamine in a solvent, add oleoyl chloride to react, then quench the reaction with acid, extract the product with an organic phase, dry and distill, and finally purify by column chromatography to obtain the polymerizable ligand.

[0009] Further, in step (1), the solvent is a mixed solution of ethanol and water in a volume ratio of 3:2, and the ratio of L-cysteine, triethylamine and 4-vinylbenzyl chloride is 20.63 mmol: 20.65 mmol: 22.74 mmol; the reaction conditions are room temperature and 2 h.

[0010] Further, in step (2), the solvent is a mixed solution of tetrahydrofuran and water in a volume ratio of 1:1, and the ratio of the white powder product, triethylamine and oleoyl chloride is 1.637g: 20.65mmol: 8.30mmol; the reaction conditions are room temperature and time of 1 to 1.5h.

[0011] The present invention also provides the use of the above-mentioned polymerizable ligand in the modification of perovskite materials.

[0012] The present invention also provides a method for preparing cesium lead halide perovskite nanocrystals based on ligand modification, comprising the following steps: adding tetra-n-octylammonium bromide and the above polymerizable ligand to a colloidal solution of cesium lead halide perovskite nanocrystals, stirring and reacting, then centrifuging, collecting the supernatant, and obtaining the colloidal solution of the ligand-modified cesium lead halide perovskite nanocrystals.

[0013] Furthermore, the cesium lead halide perovskite nanocrystals are CsPbBr3 nanocrystals.

[0014] Furthermore, the concentration of tetra-n-octylammonium bromide added was 2 mmol / L, and the concentration of polymerizable ligand added was 8.7 mmol / L.

[0015] The present invention also provides a ligand-modified cesium lead halide perovskite nanocrystal, which is obtained by extracting a colloidal solution of the ligand-modified cesium lead halide perovskite nanocrystal prepared by the above preparation method.

[0016] The present invention also provides a cesium lead halide perovskite nanocrystalline polymer film, which is prepared by the following method: the above-mentioned ligand-modified cesium lead halide perovskite nanocrystals are dispersed in a solvent containing a photoinitiator, then coated on a substrate, and after the solvent evaporates and dries, a polymerization reaction is carried out under ultraviolet light irradiation in an argon atmosphere to obtain the cesium lead halide perovskite nanocrystalline polymer film.

[0017] The design principle of this invention is as follows: This invention generates polymerizable ligands from raw materials such as 4-vinylbenzyl chloride, L-cysteine, oleic acid, and thionyl chloride in three steps: a Williamson reaction mediated by thioether, an SOCl2-mediated acylation reaction, and an amidation reaction. The carboxyl and amide groups in the ligand have a strong chelating effect on lead ions, the long chain improves the hydrophobicity and redispersibility of the nanocrystals, and the styrene groups enable the nanocrystals to polymerize and crosslink.

[0018] Taking cesium lead bromide perovskite nanocrystals as an example, the polymerizable ligands of this invention, tetra-n-octylammonium bromide, and cesium lead bromide perovskite nanocrystals are mixed. The two ligands compete with oleic acid and oleylamine for binding sites on the nanocrystal surface, effectively passivating surface defects while inducing the transformation of the monoclinic phase CsPbBr3NCs in the system into a CsPbBr3-Cs4PbBr6 mixed phase. In the rapid phase transition induced by high concentration of tetra-n-octylammonium bromide, severe lattice distortion, nanocrystal aggregation, and structural collapse occur. The polymerizable ligands of this invention, due to their multiple binding sites, can enhance the passivation of the nanocrystal surface and prevent complete fluorescence quenching and loss of colloidal stability. The polymerizability of the styrene group also gives the polymerized film of cesium lead bromide perovskite nanocrystals a dense network structure, resulting in excellent stability of the prepared CsPbBr3 nanocrystal system. The photoluminescence intensity of the cesium lead bromide perovskite nanocrystals remains almost unchanged after five heating-cooling cycles.

[0019] The beneficial effects of this invention are reflected in: The polymerizable ligands of this invention contain carboxylic acid and amide groups, which bind tightly to the perovskite surface and effectively passivate surface defects. The styrene groups in the polymerizable ligands of this invention, due to their double bonds, provide diverse and simple methods for forming network structures in perovskite nanocrystals, greatly improving their reprocessing performance.

[0020] In the preparation method of ligand-modified cesium lead halide perovskite nanocrystals of the present invention, even when the amount of TOAB added is too high, most of the three-dimensional CsPbBr3 nanocrystals can still be retained, which can prevent complete fluorescence quenching and loss of colloidal stability, avoid irreversible loss of fluorescence performance, and form zero-dimensional-three-dimensional mixed phase perovskite nanocrystals with good optical properties.

[0021] The perovskite nanocrystals prepared by this invention exhibit almost constant photoluminescence intensity during five heating-cooling cycles. Furthermore, the nanocrystalline polymer film prepared by this invention demonstrates excellent stability against ultraviolet light, which is of great significance for broadening the application fields of this material. Attached Figure Description

[0022] Figure 1 Fourier transform infrared spectra of NOSVC, TOAB, and TOAB / NOSVC CsPbBr3NCs.

[0023] Figure 2 Photoluminescence spectra of CsPbBr3NCs colloidal solution, TOAB / NOSVC CsPbBr3NCs colloidal solution, and TOAB CsPbBr3NCs colloidal solution.

[0024] Figure 3 The images show the UV absorption spectra of CsPbBr3NCs colloidal solution, TOAB / NOSVC CsPbBr3NCs colloidal solution, and TOAB CsPbBr3NCs colloidal solution.

[0025] Figure 4 XRD patterns of CsPbBr3NCs, TOAB / NOSVC CsPbBr3NCs, and TOAB CsPbBr3NCs.

[0026] Figure 5 The relative PL intensity spectra of TOAB / NOSVC CsPbBr3NCs colloidal solutions obtained by treatment with different TOAB concentrations.

[0027] Figure 6 The UV absorption spectra of TOAB / NOSVC CsPbBr3NCs colloidal solutions obtained by treatment with different TOAB concentrations.

[0028] Figure 7 The relative PL intensity changes of CsPbBr3NCs and TOAB / NOSVC CsPbBr3NCs after five heating-cooling cycles (293.15K-343.15K).

[0029] Figure 8 The images show the photostability of each film under a 365nm UV lamp, where (a) is a CsPbBr3NCs film; (b) is a TOAB / NOSVC CsPbBr3NCs unpolymerized film; and (c) is a TOAB / NOSVC CsPbBr3NCs polymerized film. Detailed Implementation

[0030] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0031] Unless otherwise specified, the raw materials, reagents or devices used in the following embodiments can be obtained from conventional commercial sources or by existing known methods; unless otherwise specified, the methods used in the embodiments of the present invention are methods mastered by those skilled in the art.

[0032] Example 1 Preparation of polymerizable ligands The polymerizable ligand prepared in this embodiment has the structure shown in Formula I, denoted as NOSVC:

[0033] Formula I.

[0034] (1) A magnetic stir bar was placed in a 250 ml round-bottom flask. 20.63 mmol (2.5 g) of L-cysteine ​​and 125 mL of ethanol / water mixture (volume ratio of ethanol to water is 3:2) were added. Then, 20.65 mmol (2.87 mL) of triethylamine was slowly added dropwise to the flask. After stirring until the solid was completely dissolved, 4-vinylbenzyl chloride solution (3.47 g, 22.74 mmol dissolved in 5 mL of ethanol) was added dropwise over 10 minutes. The reaction was stirred at room temperature for 2 h. The solid was then filtered out, washed with anhydrous diethyl ether, and dried overnight in a vacuum drying oven (vacuum drying at room temperature for 12 h) to obtain a white powder product containing a sulfide structure.

[0035] (2) At room temperature, 3.17 mL of oleic acid and 30 mL of chloroform were added to a flask, and 0.943 mL of thionyl chloride was slowly added dropwise while stirring. After the addition was complete, stirring was continued for 70 min. The system was then heated to 60 °C and reacted for 7 h. After the reaction was complete, the solvent and excess thionyl chloride were removed by vacuum distillation (using a rotary evaporator with the temperature set to 35 °C until no more solvent dripped from the receiving flask) to obtain oleyl chloride.

[0036] (3) In a 500 mL round-bottom flask equipped with a magnetic stir bar, add 1.637 g of the white powder product containing the sulfide structure obtained in step (1) and 150 mL of a tetrahydrofuran / water mixed solution (the volume ratio of tetrahydrofuran to water is 1:1). Then, slowly add 20.65 mmol (2.87 mL) of triethylamine while stirring continuously. Maintain the system at 0 °C in an ice bath. After the solid has completely dissolved, add the oleoyl chloride solution (2.5 g, i.e., 8.3 mmol of oleoyl chloride dissolved in 15 mL of tetrahydrofuran) dropwise over 15 minutes. After the addition is complete, remove the ice bath and gradually heat the reaction system to room temperature. React for 1 h, and then add 1 M of triethylamine to the system. HCl was used to adjust the pH to 2 (to quench the reaction, neutralize excess amine, and ensure the product remains in the organic phase for subsequent extraction and phase separation). After waiting 10 minutes (to allow the salt formed by the reaction of hydrochloric acid and excess amine to completely dissolve in the system, and to make the pH of the entire system more uniform), extraction was performed using ethyl acetate. The upper organic layers were combined, dried over anhydrous sodium sulfate, filtered, and then distilled under reduced pressure (using a rotary evaporator at 30°C until no more solvent dripped from the receiving flask). The crude product was purified by rapid column chromatography using n-hexane / ethyl acetate as the developing solvent. The silica gel column was approximately 5 cm high. Dry packing and dry loading were used. First, hexane was used for column chromatography, followed by hexane / ethyl acetate (5:1 v / v) to remove impurity molecules from the crude product. Then, hexane / ethyl acetate (3:1 v / v) was used to ensure that the eluent contained only the NOSVC component. Subsequently, hexane / ethyl acetate (1:1 v / v) was used for elution, and the fraction was collected by rapid column chromatography. The test tubes containing NOSVC were combined, washed with ethyl acetate, and the combined collection was concentrated under reduced pressure to obtain the polymerizable ligand NOSVC.

[0037] Its proton nuclear magnetic resonance spectrum is as follows: 1 H NMR (400MHz, CDCl3): δ 7.35 (d, J=8.1Hz, 2H), 7.25 (d, J=8.1Hz, 2H), 6.68 (dd, J=17.6, 10.Hz, 1H), 6.17 (d, J=7.3Hz, 1H), 5.73 (d, J=17.6Hz, 1H), 5.42-5.28 (m, 2H), 5.24 (d, J=10.9Hz, 1H), 4.72 (dd, J=12.6, 5.4Hz, 1H), 3.70 (s, 2H), 2.93 (d, J=5.4Hz, 2H), 2.18 (t, J=7.6Hz, 2H), 2.09-1.5 (m, 4H), 1.65-1.52 (m, 2H), 1.28 (d, J=12.5Hz, 20H), 0.87 (t, J=6.8Hz, 3H).

[0038] The successful synthesis of the corresponding NOSVC structure was confirmed.

[0039] Example 2 Preparation of ligand-modified cesium lead bromide perovskite nanocrystals (1) Add 0.2 mmol lead bromide, 0.1 mmol cesium bromide, 66 μL oleylamine and 0.5 mL oleic acid to 5 mL N,N-dimethylformamide and stir at room temperature until completely dissolved to obtain CsPbBr3 precursor solution; (2) Under stirring conditions, 150 μL of CsPbBr3 precursor solution was rapidly injected into 5 mL of anisole and reacted for 1 h to obtain crude CsPbBr3NCs product; then, methyl acetate was added to the system as an antisolvent, centrifuged at 10000 rpm for 10 minutes, the supernatant was discarded, the precipitate was dispersed in 3 mL of toluene, and centrifuged again at 3000 rpm for 3 minutes to remove large particles, the supernatant was collected, and the purified CsPbBr3NCs colloidal solution was obtained.

[0040] (3) Take 4 mL of CsPbBr3NCs colloidal solution, add 4.37 mg (2 mmol / L) of tetra-n-octylammonium bromide (TOAB) and 17.5 mg of the polymerizable ligand NOSVC prepared in Example 1, stir the reaction at room temperature for 1 h, then centrifuge the reaction solution at 1000 rpm for 1 minute to remove unreacted ligands, collect the supernatant, and obtain the ligand-modified cesium lead bromide perovskite nanocrystal colloidal solution, denoted as TOAB / NOSVC CsPbBr3NCs colloidal solution.

[0041] Example 3 Preparation of TOAB / NOSVC CsPbBr3NCs polymer thin films (1) Take 15 mL of the TOAB / NOSVC CsPbBr3NCs colloidal solution prepared in Example 2, add 22.5 mL of the antisolvent methyl acetate, then centrifuge at 12000 rpm for 10 minutes, discard the supernatant, and obtain the precipitate, which is TOAB / NOSVC CsPbBr3NCs; (2) TOAB / NOSVC CsPbBr3NCs were redispersed in 0.3 mL of tetrahydrofuran solution containing photoinitiator TPO-L (ethyl 2,4,6-trimethylbenzoylphenylphosphonate) (TPO-L / tetrahydrofuran ratio of 13 mg / 9 mL). The resulting solution was drop-coated onto a glass substrate. After the solvent evaporated and dried, unpolymerized TOAB / NOSVC CsPbBr3NCs film was obtained. The film was then subjected to polymerization under an argon atmosphere and irradiated with a 395 nm UV lamp for 15 min to obtain a polymerized TOAB / NOSVC CsPbBr3NCs film.

[0042] Comparative Example 1 Comparison of the preparation of cesium lead bromide perovskite nanocrystals Take 4 mL of the CsPbBr3NCs colloidal solution prepared in Example 2, add 4.37 mg (2 mmol / L) of tetra-n-octylammonium bromide, stir at room temperature for 1 h, and then centrifuge the reaction solution at 1000 rpm for 1 minute to remove unreacted ligands. Collect the supernatant to obtain the comparative cesium lead bromide perovskite nanocrystal colloidal solution, denoted as TOAB CsPbBr3NCs colloidal solution.

[0043] Comparative Example 2 Preparation of CsPbBr3NCs thin films The CsPbBr3NCs colloidal solution obtained in Example 2 was used to prepare CsPbBr3NCs thin films according to the same method as in Example 3.

[0044] Experimental Example 1 Structural and property analysis of ligand-modified cesium lead bromide perovskite nanocrystals The CsPbBr3NCs colloidal solution, TOAB / NOSVC CsPbBr3NCs colloidal solution, and TOAB CsPbBr3NCs colloidal solution prepared in Example 2 and the TOAB CsPbBr3NCs colloidal solution prepared in Comparative Example 1 were used to extract CsPbBr3NCs, TOAB / NOSVC CsPbBr3NCs, and TOAB CsPbBr3NCs respectively according to the method in step (1) of Example 3 for experiments.

[0045] Fourier transform infrared spectroscopy analysis was performed on NOSVC, TOAB, and TOAB / NOSVC CsPbBr3NCs, and the results are as follows: Figure 1 As shown.

[0046] Depend on Figure 1 Infrared spectra show that the polymerizable ligand NOSVC has a concentration at 1711 cm⁻¹. -1 There is a C=O stretching vibration in the carboxyl group, 1619 cm⁻¹ -1 It is the stretching vibration of amide I at C=O, 1547 cm⁻¹ -1 These are the NH bending vibrations and CN stretching vibrations in the amide II band, 1223–1252 cm⁻¹ -1 The weak absorption in the vicinity corresponds to the C–S stretching vibration of sulfides. (1449-1466 cm⁻¹ in the infrared spectrum) -1 722-753cm -1The characteristic peaks at the specified location clearly correspond to the "fingerprint peak group" of the long alkyl chain of tetra-n-octylammonium bromide. In the infrared analysis of TOAB / NOSVCCsPbBr3NCs, the characteristic peaks of the C=O group and N-H group both showed significant shifts, which proves that the carboxyl and amide groups in the ligands interacted with the perovskite nanocrystals and successfully bound to the surface of the perovskite nanocrystals.

[0047] The optical properties of TOAB / NOSVC CsPbBr3NCs colloidal solution and TOAB CsPbBr3NCs colloidal solution were tested using UV-vis and PL, respectively. The crystal structures of TOAB / NOSVC CsPbBr3NCs and TOAB CsPbBr3NCs were determined by XRD analysis. The results are as follows: Figure 2-4 As shown.

[0048] Depend on Figure 2-4 As can be seen, compared with the original CsPbBr3NCs, TOAB CsPbBr3NCs not only showed a near-complete disappearance of photoluminescence intensity, but also almost a complete disappearance of the ultraviolet absorption peak, similar to the ultraviolet absorption spectrum of TOAB dissolved in toluene at the same concentration. Figure 1 The XRD pattern also matches that of pure tetra-n-octylammonium bromide. Figure 1 This indicates that adding 2 mmol / L TOAB alone would completely destroy and dissolve the perovskite nanocrystals due to the excessive TOAB concentration, rendering them no longer crystalline. However, the TOAB / NOSVC CsPbBr3NCs, co-modified with TOAB and NOSVC, retained photoluminescence, with a ~1 nm blue shift in the emission peak position. The photoluminescence intensity was 1.79 times that of the original CsPbBr3NCs. The UV absorption spectrum showed the characteristic UV absorption peak of Cs4PbBr6NCs at 313 nm. Furthermore, the X-ray diffraction pattern of TOAB / NOSVC CsPbBr3NCs also showed a characteristic peak 2. =15°, 30.6° conforms to the 3D monoclinic crystal form of CsPbBr3 nanocrystals and characteristic peak 2 =12.7°, 25.6° conforms to the 0D hexagonal crystal form of Cs4PbBr6 nanocrystals, consistent with the results of the ultraviolet absorption spectrum.

[0049] Experiment Example 2 Effect of TOAB concentration on the optical properties of TOAB / NOSVC CsPbBr3NCs Based on Example 2, the amount of TOAB added in step (3) was adjusted (0-6 mmol / L), and the optical properties of a series of TOAB / NOSVC CsPbBr3NCs colloidal solutions obtained at different concentrations were tested under UV-Vis and PL, respectively. The results are as follows. Figure 5 and Figure 6 As shown.

[0050] Analysis using both photoluminescence (PL) and ultraviolet (UV) spectra revealed that the UV characteristic absorption peak of the TOAB / NOSVC CsPbBr3NCs colloidal solution decreased in intensity and red-shifted around 505 nm with increasing tetra-n-octylammonium bromide (TEN) concentration. Simultaneously, a new absorption peak appeared at 314 nm, corresponding to the characteristic absorption peak of the hexagonal Cs4PbBr6 phase. This indicates that both Cs4PbBr6NCs and CsPbBr3NCs coexist in the TOAB / NOSVC CsPbBr3NCs colloidal solution. When the TOAB concentration was 2 mmol / L, the sample exhibited high absorbance not only around 505 nm but also a high absorption peak at 314 nm. Furthermore, the fluorescence emission intensity of the TOAB / NOSVC CsPbBr3NCs was 1.45 times that of the perovskite nanocrystals without TOAB, indicating a high photoluminescence (PL) intensity.

[0051] Experimental Example 3 Performance Analysis of TOAB / NOSVC CsPbBr3NCs Figure 7 This is a graph showing the relative photoluminescence (PL) intensity changes of CsPbBr3NCs and TOAB / NOSVC CsPbBr3NCs after five heating-cooling cycles (293.15K-343.15K). The results show that in the five heating-cooling cycles of CsPbBr3NCs and TOAB / NOSVC CsPbBr3NCs (from 293.15K to 343.15K and then back to 293.15K), the fluorescence intensity of the original CsPbBr3NCs decreased significantly after the thermal cycles, reaching only about 30% of its original intensity after five cycles. In contrast, the TOAB / NOSVC CsPbBr3NCs maintained excellent thermal stability throughout the experimental monitoring range, with its PL intensity remaining approximately 100% of its initial photoluminescence intensity even after five cycles. Experimental data demonstrate that the excellent thermal stability of the TOAB / NOSVC CsPbBr3NCs prepared in this invention can be attributed to the tighter binding between the ligands and the perovskite, thereby effectively delaying the loss of photoluminescence in the nanocrystals.

[0052] Figure 8The images show the photostability of the various films under a 365 nm UV lamp. (a) is the CsPbBr3NCs film, (b) is the unpolymerized TOAB / NOSVC CsPbBr3NCs film, and (c) is the polymerized TOAB / NOSVC CsPbBr3NCs film. The photostability of the perovskite nanocrystalline films was investigated under 365 nm 200 W UV light irradiation. It can be seen that the photoluminescence intensity of the original CsPbBr3NCs film decreased significantly after 10 min, and the fluorescence emission peak intensity remained at only about 16% after 80 min. Under the same conditions, the unpolymerized film obtained after treatment with tetra-n-octylammonium bromide and NOSVC ligands could maintain about 50% of its initial photoluminescence intensity after 80 min of light irradiation. Furthermore, the TOAB / NOSVC CsPbBr3NCs polymerized film after further UV polymerization showed a strong fluorescence intensity retention rate throughout the monitoring period, still retaining 94% of its initial photoluminescence intensity after 80 min of UV irradiation. The significant further enhancement in photostability can be attributed to the network structure formed by the polymerization of polymerizable ligand NOSVC on the nanocrystalline surface.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A polymerizable ligand, characterized in that, It has a structure as shown in Equation I: Formula I.

2. The method for preparing polymerizable ligands as described in claim 1, characterized in that, Includes the following steps: (1) L-cysteine ​​and triethylamine were dissolved in a solvent, and 4-vinylbenzyl chloride was added to react. The resulting solid product was then washed and dried to obtain a white powder product. (2) Dissolve the white powder product and triethylamine in a solvent, add oleoyl chloride to react, then quench the reaction with acid, extract the product with an organic phase, dry and distill, and finally purify by column chromatography to obtain the polymerizable ligand.

3. The method for preparing polymerizable ligands as described in claim 2, characterized in that, In step (1), the solvent is a mixed solution of ethanol and water in a volume ratio of 3:2, and the ratio of L-cysteine, triethylamine and 4-vinylbenzyl chloride is 20.63 mmol: 20.65 mmol: 22.74 mmol; the reaction conditions are room temperature and 2 h.

4. The method for preparing polymerizable ligands as described in claim 2, characterized in that, In step (2), the solvent is a mixed solution of tetrahydrofuran and water in a volume ratio of 1:1, and the ratio of the white powder product, triethylamine and oleoyl chloride is 1.637g: 20.65mmol: 8.30mmol; the reaction conditions are room temperature and 1 to 1.5h.

5. Use of the polymerizable ligand as described in claim 1 in the modification of perovskite materials.

6. A method for preparing cesium lead halide perovskite nanocrystals based on ligand modification, characterized in that, The process includes the following steps: adding tetra-n-octylammonium bromide and the polymerizable ligand as described in claim 1 to a cesium lead halide perovskite nanocrystal colloidal solution, stirring and reacting, then centrifuging, collecting the supernatant, and obtaining the ligand-modified cesium lead halide perovskite nanocrystal colloidal solution.

7. The method for preparing cesium lead halide perovskite nanocrystals based on ligand modification as described in claim 6, characterized in that, The cesium lead halide perovskite nanocrystals are CsPbBr3 nanocrystals.

8. The method for preparing cesium lead halide perovskite nanocrystals based on ligand modification as described in claim 6 or 7, characterized in that, The concentration of tetra-n-octylammonium bromide added was 2 mmol / L, and the concentration of polymerizable ligand added was 8.7 mmol / L.

9. A ligand-modified cesium lead halide perovskite nanocrystal, characterized in that, The cesium lead halide perovskite nanocrystals were prepared into a colloidal solution according to the preparation method described in claim 6, 7, or 8, and then extracted.

10. A cesium lead halide perovskite nanocrystalline polymer thin film, characterized in that, The cesium lead halide perovskite nanocrystals as described in claim 9 are dispersed in a solvent containing a photoinitiator, then coated onto a substrate. After the solvent evaporates and dries, a polymerization reaction is carried out under ultraviolet light irradiation in an argon atmosphere to obtain the polymerized thin film of the cesium lead halide perovskite nanocrystals.

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