A controllable synthesis method for oriented quasi-spherical CsPbBr3 perovskite

Abstract

The present invention provides a controllable synthesis preparation method for quasi-spherical CsPbBr3 perovskite with orientation, the method comprising the following steps: S1, using a composition of hydrogen bromide and water as a solvent, respectively preparing a cesium bromide solution, a lead bromide solution, a gum arabic solution, and a polyvinyl pyrrolidone solution; S2, mixing the obtained cesium bromide solution, lead bromide solution, gum arabic solution, and polyvinyl pyrrolidone solution to obtain a precursor solution; adding isopropyl alcohol to the precursor solution obtained in S2, and reacting for more than 2 hours until the reaction is sufficient to obtain a quasi-spherical CsPbBr3 perovskite with orientation. The present invention uses gum arabic and polyvinyl pyrrolidone in an appropriate concentration range as ligands. Under the synergistic effect of the two, the controllable perovskite is synthesized through precise crystal arrangement, and the crystal size of the prepared perovskite is reduced and the size uniformity is significantly improved.

Description

Technical Field

[0001] The present invention relates to a method for preparing perovskite, in particular to a method for controllable synthesis of oriented quasi-spherical CsPbBr3 perovskite, belonging to the technical field of controllable synthesis of perovskite. Background Art

[0002] Since the controlled synthesis of crystals can precisely regulate the properties, structure, and morphology of materials, they have a wide range of applications in many scientific fields. In recent years, by changing the temperature, synthesis parameters, and gas environment, the controlled synthesis of various materials such as ZnO, Cu2O, and graphene has been achieved. Among these materials that can be controllably synthesized, metal halide perovskite compounds with the general formula CsPbX3, especially CsPbBr3, have attracted widespread attention due to their excellent optoelectronic properties. For example, nanowires, nanosheets, and nanocubes of CsPbBr3 can be used for polarized emission, photodetectors, and light-emitting diodes, respectively. In the prior art, there are still certain obstacles to controlling the size and morphology of CsPbBr3 crystals during the controllable synthesis of CsPbBr3, and there is still a lack of methods for the precise and controllable synthesis of oriented quasi-spherical CsPbBr3 perovskites. Summary of the Invention

[0003] Based on the above background, the object of the present invention is to provide a method for preparing oriented quasi-spherical CsPbBr3 perovskite.

[0004] Another object of the present invention is to provide a CsPbBr3 perovskite prepared according to the above preparation method.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A controllable synthesis method for preparing oriented quasi-spherical CsPbBr3 perovskite, the method comprising the following steps:

[0007] S1. Using a combination of hydrogen bromide and water as a solvent, prepare a 0.1M cesium bromide solution, a 0.1M lead bromide solution, a 6.5-8.5mM gum arabic solution, and a 3-5.2mM polyvinyl pyrrolidone solution, respectively.

[0008] Among them, the proportion of hydrogen bromide in the solvent is 33-48wt%,

[0009] The molecular weight range of polyvinylpyrrolidone is 5000 to 1300000;

[0010] S2, mixing the obtained cesium bromide solution, lead bromide solution, gum arabic solution and polyvinyl pyrrolidone solution to obtain a precursor solution,

[0011] The precursor solution has a cesium bromide concentration of 1.5 to 2.0 mM, a lead bromide concentration of 1.5 to 2.0 mM, a gum arabic concentration of 2.0 to 2.5 mM, and a polyvinyl pyrrolidone concentration of 1.2 to 1.5 mM.

[0012] S3. Add an organic solvent to the precursor solution prepared in S2 at a ratio of cesium bromide or lead bromide (mol) to organic solvent (L) of 1 mol: 430-450 L, and react for more than 2 hours until the reaction is sufficient to obtain oriented quasi-spherical CsPbBr3 perovskite; the organic solvent is selected from one or more of isopropyl alcohol, ethyl acetate, and methyl acetate.

[0013] The organic solvent described in S3 of the present invention is a poor solvent for CsPbBr3.

[0014] In the preparation of CsPbBr3 perovskite, polyvinyl pyrrolidone has the ability to promote the formation of quasi-spherical structure and regulate the size of perovskite crystals. Although it improves the photoluminescence intensity of the perovskite, it also reduces the crystal size and crystallinity to a certain extent. The addition of gum arabic improves the crystallinity and increases the crystal quality of the quasi-spherical CsPbBr3 structure. Therefore, using gum arabic and polyvinyl pyrrolidone in an appropriate concentration range as ligands, under the synergistic effect of the two, the crystal size of the prepared perovskite is smaller and the size uniformity is significantly improved; an appropriate amount of isopropanol as an antisolvent has a positive effect on the crystal morphology of the prepared perovskite, producing crystals of uniform size; finally, the above preparation method obtains an oriented quasi-spherical CsPbBr3 perovskite with enhanced optical properties. Its photoluminescence quantum yield can reach 10.18%, and it has better stability in polar solvents such as isopropanol, ethanol, and acetone and in air conditions.

[0015] Preferably, the precursor solution is shaken before the organic solvent is added to the precursor solution.

[0016] Preferably, the concentration of the gum arabic solution is 6.5 mM, and the concentration of the polyvinyl pyrrolidone solution is 4.1 mM.

[0017] Preferably, the K value of the polyvinyl pyrrolidone is K23-K27.

[0018] Preferably, the proportion of hydrogen bromide in the solvent is 48 wt%.

[0019] Preferably, the molecular weight of polyvinyl pyrrolidone is 24,000.

[0020] Preferably, the concentration of cesium bromide in the precursor solution is 1.667 mM, the concentration of lead bromide is 1.667 mM, the concentration of gum arabic is 2.167 mM, and the concentration of polyvinyl pyrrolidone is 1.367 mM.

[0021] Preferably, in S3, the organic solvent is isopropanol, and the ratio of cesium bromide or lead bromide (mol) to isopropanol (L) is 1 mol:440 L.

[0022] The CsPbBr3 perovskite is prepared by the method for preparing oriented quasi-spherical CsPbBr3 perovskite described in the present invention.

[0023] The invention discloses an application of the oriented quasi-spherical CsPbBr3 perovskite as a photoluminescent material.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] The present invention discloses a method for preparing an oriented quasi-spherical CsPbBr3 perovskite, which uses gum arabic and polyvinyl pyrrolidone in an appropriate concentration range as ligands. Under the synergistic effect of the gum arabic and polyvinyl pyrrolidone, a controllable perovskite is synthesized through precise crystal arrangement, and the crystal size of the prepared perovskite is reduced and the size uniformity is significantly improved. The preparation method of the present invention also uses an appropriate amount of isopropyl alcohol as an anti-solvent, which has a positive effect on the crystal morphology of the prepared perovskite and produces crystals of uniform size. The CsPbBr3 perovskite prepared by the preparation method of the present invention has nanocrystals on the quasi-spherical structure that exhibit orientation and has relatively excellent optical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 (a) Absorption spectrum of isopropyl alcohol in the volume range of 0.2-2.4 ml. (b) Slope at 400-450 nm from 0.2 ml to 2.2 ml and SEM corresponding to 0.2 ml and 2.2 ml;

[0027] Figure 2 (a, b, c, d) are the absorption spectra of polyvinylpyrrolidone with average molecular weights of 5000, 8000, 10000, and 24000 in the concentration range of 0-4.8 mM;

[0028] Figure 3 (a, b) Photographs of gum arabic at concentrations ranging from 0 to 29 mM under 365 nm UV irradiation. (c) Scatter plot of G values ​​for plates 2 and 3 (normalized to the highest G value).

[0029] Figure 4 This is a photo of a two-factor experiment under 365nm ultraviolet irradiation;

[0030] Figure 5 (a, b, c, d, e, f) correspond to the absorption spectra of plates 4, 5, 6, 7, 8, and 9, respectively;

[0031] Figure 6 is a machine learning model of G value and gum arabic and polyvinyl pyrrolidone concentration (data are normalized by the highest G value), R 2 :0.71;

[0032] Figure 7 It is for Figure 6 The bottom projection image of the image shows the black dashed box indicating the filtered concentration range.

[0033] Figure 8 The effect of ligands on the morphology and size of CsPbBr3. (a, b, c, d) SEM images of formulations #1, 2, 3, and 4, respectively (scale bar in the images is 500 nm);

[0034] Figure 9 The enhanced optical properties were achieved through formulation optimization. (a) Fluorescence lifetime plots for formulations #1, 2, 3, and 4, with PLQYs less than 1%, 2.84%, 8.29%, and 10.18%, respectively. (b) After three weeks of full reaction in isopropyl alcohol (IPA), ethanol (EtOH), acetone (DMK), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and ethylene glycol (MEG), formulation #4 was exposed to 365nm UV light. The emission intensity was stable in IPA, EtOH, and DMK, but was quenched in the more polar DMF, DMSO, and MEG. (c) Changes in the G value of formulation #4 in air. After 38 days, the PL intensity and G value remained stable (normalized to the G value of formulation #4 on the first day). DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any form of modification and / or change made to the present invention will fall within the scope of protection of the present invention.

[0036] In the present invention, unless otherwise specified, all parts and percentages are by weight. The equipment and raw materials used are commercially available or commonly used in the art. The methods in the following embodiments, unless otherwise specified, are conventional methods in the art. The components or equipment in the following embodiments, unless otherwise specified, are all universal standard parts or components known to those skilled in the art. Their structures and principles are known to those skilled in the art through technical manuals or routine experimental methods.

[0037] The following detailed description of the embodiments of the present invention is made in conjunction with the accompanying drawings. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, one or more embodiments may be implemented by those skilled in the art without these specific details.

[0038] The present invention discloses a method for preparing a quasi-spherical CsPbBr3 perovskite with orientation, which comprises the following steps: using a combination of hydrogen bromide and water as a solvent, respectively preparing a 0.1M cesium bromide solution, a 0.1M lead bromide solution, a 6.5-8.5mM gum arabic solution, and a 3-5.2mM polyvinyl pyrrolidone solution, wherein the molecular weight of the polyvinyl pyrrolidone is 24000; adding 50μl of A 0.1M cesium bromide solution, 50μl of a 0.1M lead bromide solution, 100μl of a 6.5mM gum arabic solution and 100μl of a 4.1mM polyvinyl pyrrolidone solution were mixed to obtain a precursor solution; isopropanol was added to the precursor solution at a ratio of cesium bromide or lead bromide (mol) to organic solvent (L) of 1mol:430-450L to obtain oriented quasi-spherical CsPbBr3 perovskite.

[0039] Using gum arabic and polyvinyl pyrrolidone in an appropriate concentration range as ligands, the synergistic effect of the two reduces the crystal size of the prepared perovskite and significantly improves its size uniformity; an appropriate amount of isopropyl alcohol is used as an anti-solvent, which has a positive effect on the crystal morphology of the prepared perovskite and produces crystals of uniform size.

[0040] In order to verify the above effects, antisolvent volume screening experiments, single-factor experiments and two-factor experiments were carried out, which are described in detail below.

[0041] In the experiment, the inventors used a high-throughput color characterization platform to capture and extract the R, G, and B values ​​of each sample (representing the emission intensity of the three primary colors red, green, and blue). Since CsPbBr3 emits bright green light under ultraviolet light at a wavelength of 365nm, the G value of the emission color can be used to quickly evaluate the photoluminescence intensity (PL intensity) of each prepared CsPbBr3 sample.

[0042] In order to better represent the correlation between the absorption spectrum and the crystal size, the inventors established the relationship between the slope of the absorption spectrum at 400-450 nm and the CsPbBr3 crystal size. A negative slope indicates a smaller crystal size. The slope of small sizes (such as quantum dots and nanocrystals) is lower than 0, while the slope of larger CsPbBr3 crystals (such as bulk crystals) is equal to or greater than 0.

[0043] Prepare the following chemicals and materials:

[0044] Isopropyl alcohol (IPA, AR) was purchased from Dongguan Dongjiang Chemical Reagent Co., Ltd. Hydrogen bromide (HBr, 48 wt%, balance water), gum arabic (powder, pharmaceutical grade), polyvinyl pyrrolidone (Mw = 8000, K16-K18), polyvinyl pyrrolidone (Mw = 10000, K13-K18), and polyvinyl pyrrolidone (Mw = 24000, K23-K27) were purchased from Aladdin. Polyvinyl pyrrolidone (Mw = 3000-7000, K12) was purchased from Adams. All of the above chemicals were not reprocessed. The unit M mentioned below, unless otherwise specified, refers to the concentration unit mol / L.

[0045] 1. Antisolvent volume screening experiment

[0046] Using a composition of hydrogen bromide and water as a solvent (hydrogen bromide accounts for 48wt%), 0.1M cesium bromide solution and lead bromide solution, as well as 3mM polyvinyl pyrrolidone (molecular weight 24000) solution were prepared respectively. The precursor solution consists of 50μl of cesium bromide, 50μl of lead bromide and 100μl of polyvinyl pyrrolidone. After shaking the precursor solution on an oscillator for 30 seconds, 0.2mL, 0.4mL, 0.6mL, 0.8mL, 1mL, 1.2mL, 1.4mL, 1.6mL, 1.8mL, 2mL, 2.2mL and 2.4ml of isopropanol were added to the precursor solution respectively. After 2 hours, the above samples were transferred to a 24-well plate for characterization.

[0047] When using the ligand-assisted reprecipitation method to prepare perovskites, the antisolvent volume has a significant effect on the size and morphology of the perovskite. The above experiments verified the optimal parameters of the antisolvent volume. Figure 1 As shown in a, the absorption spectra of CsPbBr3 synthesized in different volumes of isopropyl alcohol (IPA) ranging from 0.2 ml to 2.4 ml were collected. It can be found that the spectral curve gradually changes from a smooth straight line to a sharp absorption peak at 515 nm.

[0048] The corresponding slopes of each sample in the antisolvent volume screening experiment are Figure 1 Figure b shows scanning electron microscopy (SEM) images of two samples synthesized using 0.2 and 2.2 ml IPA volumes. The sample synthesized with 2.2 ml IPA has the smallest absorption spectrum slope, indicating that the optimal volume of IPA as an antisolvent is 2.2 mL. The SEM images also demonstrate the effect of antisolvent volume on crystal morphology: an appropriate amount of antisolvent produces uniform crystal size, while too little IPA volume results in oversized crystals with defects.

[0049] 2. Single-factor experiment

[0050] Using a composition of hydrogen bromide and water as a solvent (hydrogen bromide accounting for 48wt%), 0.1M cesium bromide solution and lead bromide solution, as well as 5mM polyvinylpyrrolidone (PVP) solution were prepared, respectively, wherein the molecular weight of polyvinylpyrrolidone was 5000, 8000, 10000 and 24000, respectively. The 5mM PVP solution was diluted to 0.4mM, 0.6mM, 0.8mM, 1mM, 1.2mM, 1.4mM, 1.6mM, 1.8mM, 2mM, 2.2mM, 2.4mM, 2.6mM, 2.8mM, 3mM, 3.2mM, 3.4mM, 3.6mM, 3.8mM, 4mM, 4.2mM, 4.4mM, 4.6mM and 4.8mM with a solvent consisting of hydrogen bromide and water. The precursor solution consisted of 50 μl of cesium bromide, 50 μl of lead bromide, and 100 μl of diluted polyvinylpyrrolidone solution. After shaking the precursor solution on a shaker for 30 seconds, 2.2 ml of isopropanol was added to the precursor (100 μl of isopropanol was added to make up the volume if no ligand was present). After 2 hours, the sample was transferred to a 24-well plate for characterization.

[0051] Using a combination of hydrogen bromide and water as a solvent (48 wt% hydrogen bromide), 0.1 M cesium bromide and lead bromide solutions, as well as 5 mM and 29 mM gum arabic solutions, were prepared. The 5 mM gum arabic solution was diluted with hydrogen bromide and water to 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, and 4.8 mM. The 29 mM gum arabic solution was diluted with hydrogen bromide to 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, and 27 mM. The precursor solution consisted of 50 μl of cesium bromide, 50 μl of lead bromide, and 100 μl of diluted gum arabic solution. After shaking the precursor solution on a shaker for 30 seconds, 2.2 ml of isopropanol was added to the precursor (100 μl of isopropanol was added to make up the volume when no ligand was present). After 2 hours, the samples were transferred to a 24-well plate for characterization.

[0052] 96 absorption spectra of 24 samples of polyvinylpyrrolidone with average molecular weights of 5000, 8000, 10000, and 24000 at concentrations ranging from 0 to 4.8 mM are shown in Figure 2. Figure 2 As shown, Figure 2 a is the sample absorption spectrum of polyvinyl pyrrolidone with an average molecular weight of 5000 in the concentration range from 0 to 4.8 mM, Figure 2b is the sample absorption spectrum of polyvinyl pyrrolidone with an average molecular weight of 8000 in the concentration range from 0 to 4.8 mM, Figure 2 c is the sample absorption spectrum of polyvinyl pyrrolidone with an average molecular weight of 10,000 in the concentration range from 0 to 4.8 mM, Figure 2 d is the absorption spectrum of samples with an average molecular weight of 24,000 polyvinyl pyrrolidone in the concentration range of 0 to 4.8 mM. It can be seen that the samples with a molecular weight of 24,000 polyvinyl pyrrolidone in the concentration range of 3.2-4.8 mM exhibit the smallest slope, that is, they have the highest nanocrystal content.

[0053] Using high-throughput color characterization, the emission colors of each sample of gum arabic at concentrations ranging from 0 to 29 mM under 365 nm ultraviolet irradiation were as follows: Figure 3 a and Figure 3 As shown in b, the G value data expressed in RGB values ​​(representing the emission intensity of the three primary colors of red, green, and blue) are shown in Table 1, and the G value scatter plot is shown in Figure 3 As shown in Figure c (G values ​​are normalized according to the highest G value of the experimental data). It can be seen that the G values ​​of each sample increase with the increase of gum arabic concentration until the concentration reaches 10 mM and then tends to be flat.

[0054] Table 1 G value data of samples with different concentrations of gum arabic in single factor experiment

[0055]

[0056]

[0057] 3. Two-factor experiment

[0058] According to the results of the single-factor experiment, a two-factor experiment was conducted with a concentration range of 3-5.2 mM for polyvinyl pyrrolidone (Mw=24000) and a concentration range of 4.5-15.5 mM for gum arabic.

[0059] Using a composition of hydrogen bromide and water as a solvent (hydrogen bromide accounting for 48 wt%), a 0.1 M cesium bromide solution, a 0.1 M lead bromide solution, a 15.5 mM gum arabic solution, and a 5.2 mM polyvinyl pyrrolidone solution were prepared, wherein the polyvinyl pyrrolidone has a molecular weight of 24,000. The gum arabic solution was diluted with a solvent consisting of hydrogen bromide and water to 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5 and 15 mM, and the polyvinyl pyrrolidone solution was diluted with a solvent consisting of hydrogen bromide and water to 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5 and 5.1 mM. The precursor solution was prepared by mixing 50 μl of cesium bromide, 50 μl of lead bromide, 100 μl of diluted polyvinyl pyrrolidone solution, and 100 μl of diluted gum arabic solution. After shaking the precursor solution on a shaker for 30 seconds, 2.2 ml of isopropanol was added to the precursor (a control without ligand was supplemented with 100 μl of isopropanol). After 2 hours, 50 μl of the sample was transferred to a 96-well plate and diluted with 50 μl of isopropanol for characterization.

[0060] The well plate layout and the emission color of each sample under 365nm ultraviolet light irradiation are shown in Figure 2. Figure 4 The G value data are shown in Table 2, and the absorption spectra of each sample are shown in Figure 5 As shown. Figure 4 It can be seen that CsPbBr3 crystals synthesized using polyvinyl pyrrolidone and gum arabic as ligands exhibit higher PL intensities than those synthesized using either polyvinyl pyrrolidone or gum arabic alone, demonstrating a synergistic effect between polyvinyl pyrrolidone and gum arabic on the PL intensity of CsPbBr3. As shown in Table 2, before the gum arabic concentration reaches 9.5 mM, the addition of polyvinyl pyrrolidone significantly reduces the slope of the absorption spectrum from 400 nm to 450 nm. This phenomenon is most pronounced within the gum arabic concentration range of 6.5 mM to 8.5 mM, but this effect is lost when the concentration exceeds 9.5 mM. When polyvinyl pyrrolidone and gum arabic are used as combined ligands, the PL intensity does not change significantly with the gum arabic concentration within the range of 6.5 to 8.5 mM, resulting in relatively small CsPbBr3 crystals. However, an excess of gum arabic increases the crystal size, counteracting the crystal size-reducing effect of polyvinyl pyrrolidone.

[0061] Table 2 RGB value data of samples with different concentrations of gum arabic and polyvinyl pyrrolidone in the two-factor experiment

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

[0076] Therefore, through the above-mentioned anti-solvent volume screening experiments, single-factor experiments and two-factor experiments, it is proved that an appropriate amount of isopropyl alcohol as an anti-solvent has a positive effect on the crystal morphology of the prepared perovskite and can produce crystals of uniform size. More importantly, an appropriate concentration range of gum arabic and polyvinyl pyrrolidone are used as ligands. The two have a synergistic effect when preparing perovskite, which reduces the crystal size of the prepared perovskite and significantly improves the size uniformity.

[0077] In order to further verify the relationship between the concentration range of gum arabic and polyvinyl pyrrolidone as ligands and the PL intensity of perovskite, the inventors constructed a database of 556 G value data collected through the above two-factor experiment, and performed machine learning training and fitting to obtain the following: Figure 6 The data fitting of machine learning prediction is shown in the three-dimensional surface plot, where the z-axis represents the G value, the x-axis represents the polyvinyl pyrrolidone concentration value, and the y-axis represents the gum arabic concentration value. Figure 7 for Figure 6 The bottom projection image of the image shows the black dashed boxes indicating the regions with polyvinylpyrrolidone concentrations of 3–5.2 mM and gum arabic concentrations of 6.5–8.5 mM.

[0078] The following is a comparison of the results of synthesizing CsPbBr3 perovskite with different concentrations of specific synthesis parameters, which further illustrates the effect of the present invention in preparing oriented quasi-spherical CsPbBr3 perovskite using gum arabic and polyvinyl pyrrolidone as ligands. Four control groups #1, #2, #3 and #4 were selected. Figure 7 The regions in the figure are different: #1 represents the control group without ligand, #2 represents 6.5 mM gum arabic, #3 represents 4.1 mM polyvinyl pyrrolidone, and #4 represents 4.1 mM polyvinyl pyrrolidone and 6.5 mM gum arabic.

[0079] Figure 8 a- Figure 8 d shows the SEM images of CsPbBr3 perovskites with four morphologies of control groups #1, #2, #3 and #4 respectively. Figure 9 Figure a shows the fluorescence lifetime and photoluminescence quantum yield (PLQY) of four CsPbBr3 perovskite morphologies: control groups #1, #2, #3, and #4. Under 365nm UV excitation, the corresponding PLQYs are <1%, 8.29%, 2.84%, and 10.18%, respectively, and the corresponding fluorescence lifetimes are 3.51ns, 32.96ns, 14.05ns, and 35.00ns, respectively. Therefore, control group #4 exhibits significantly superior fluorescence lifetime and PLQY performance compared to the other control groups.

[0080] also, Figure 9 bc shows that the oriented quasi-spherical CsPbBr3 structure synthesized in control group #4 has better stability to polar solvents with weaker polarity and air. In isopropyl alcohol (IPA), ethanol (EtOH), and acetone (DMK) solvents, the quasi-spherical CsPbBr3 maintained stable brightness after three weeks. However, they were quenched in polar solvents such as N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and ethylene glycol (MEG). This shows that the protection of micelles can tolerate solvents with relatively weak polarity. The CsPbBr3 perovskite of control group #4 was coated on a well plate to test the air stability, and the change in G value was recorded within 3 days. It can be seen that the G value changed very little during this period.

[0081] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A controllable synthesis method for oriented quasi-spherical CsPbBr3 perovskite, characterized by: The method comprises the following steps: S1. Using a combination of hydrogen bromide and water as a solvent, prepare a 0.1M cesium bromide solution, a 0.1M lead bromide solution, a 6.5-8.5mM gum arabic solution, and a 3-5.2mM polyvinyl pyrrolidone solution, respectively. Among them, the proportion of hydrogen bromide in the solvent is 33-48wt%, The molecular weight range of polyvinylpyrrolidone is 5000 to 1300000; S2, mixing the obtained cesium bromide solution, lead bromide solution, gum arabic solution and polyvinyl pyrrolidone solution to obtain a precursor solution, The precursor solution has a cesium bromide concentration of 1.5 to 2.0 mM, a lead bromide concentration of 1.5 to 2.0 mM, a gum arabic concentration of 2.0 to 2.5 mM, and a polyvinyl pyrrolidone concentration of 1.2 to 1.5 mM. S3. Adding an organic solvent to the precursor solution prepared in S2 at a ratio of cesium bromide or lead bromide to organic solvent of 1 mol: 430-450 L, and reacting for more than 2 hours until the reaction is sufficient to obtain oriented quasi-spherical CsPbBr3 perovskite; the organic solvent is selected from one or more of isopropyl alcohol, ethyl acetate, and methyl acetate.

2. The method for preparing an oriented quasi-spherical CsPbBr3 perovskite according to claim 1, characterized in that: Before adding the organic solvent to the precursor solution, the precursor solution is shaken.

3. The method for preparing an oriented quasi-spherical CsPbBr3 perovskite according to claim 1, characterized in that: The concentration of the gum arabic solution is 6.5 mM, and the concentration of the polyvinyl pyrrolidone solution is 4.1 mM.

4. The method for preparing an oriented quasi-spherical CsPbBr3 perovskite according to claim 1, wherein: The K value of the polyvinyl pyrrolidone is K23-K27.

5. The method for preparing an oriented quasi-spherical CsPbBr3 perovskite according to claim 1, wherein: The proportion of hydrogen bromide in the solvent is 48 wt%.

6. The method for preparing an oriented quasi-spherical CsPbBr3 perovskite according to claim 1, wherein: The molecular weight of polyvinylpyrrolidone is 24,000.

7. The method for preparing an oriented quasi-spherical CsPbBr3 perovskite according to claim 1, characterized in that: The precursor solution has a cesium bromide concentration of 1.667 mM, a lead bromide concentration of 1.667 mM, a gum arabic concentration of 2.167 mM, and a polyvinyl pyrrolidone concentration of 1.367 mM.

8. The method for preparing an oriented quasi-spherical CsPbBr3 perovskite according to claim 1, wherein: In S3, the organic solvent is isopropyl alcohol, and the ratio of cesium bromide or lead bromide to isopropyl alcohol is 1 mol:440L.

9. An oriented quasi-spherical CsPbBr3 perovskite prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the oriented quasi-spherical CsPbBr3 perovskite according to claim 9 as a photoluminescent material.

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