Method for tuning perovskite quantum dot spectrum on basis of phase interface anion exchange
Patent Information
- Application Number
- PCT/CN2025/087697
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-17
- Filing Date
- 2025-04-08
- Publication Date
- 2026-09-24
Smart Images
Figure CN2025087697_24092026_PF_FP_ABST
Abstract
Description
A method for regulating the spectra of perovskite quantum dots based on anion exchange at the phase interface Technical Field
[0001] This invention relates to the field of perovskite quantum dot technology, and specifically to a method for finely controlling the spectrum of perovskite quantum dots based on solid / liquid two-phase anion exchange reactions in perovskite quantum dot solutions. Background Technology
[0002] Metal halide perovskites, as the latest generation of semiconductor light-emitting materials, have attracted much attention due to their tunable bandgap, high quantum yield, and strong photoluminescence. The low cost and abundant reserves of raw materials further enhance their promising development prospects. Perovskite quantum dots, prepared based on these materials, combine the advantages of both perovskites and quantum dots. In addition to their inherent excellent optoelectronic properties, compared to bulk materials, the size effect of quantum dots allows for a further narrowing of their emission spectrum, further improving photoluminescence efficiency. Ligand molecules enhance their solubility and stability, and abundant surface sites significantly increase the tunable range of their performance. The narrow full width at half maximum (FWHM) and the ability to freely adjust the spectral bandgap give them significant advantages in pure-color emission and fine-tuning of the spectrum. These excellent semiconductor optoelectronic properties make them of great application value in high-definition displays, information encryption, and spectral detection.
[0003] In the field of high-definition displays, the CIE color coordinates of the three primary colors need to be as close as possible to the edge of the color coordinate scale to achieve the color gamut coverage of the display. The size of the gamut directly affects the display's color reproduction accuracy. Therefore, finding low-cost materials suitable for displays is crucial for the iterative development of industrial technology.
[0004] In the field of information encryption, most of the materials currently used achieve multi-level encryption in both time and space dimensions through their diverse luminescent properties, such as electrochromism, photochromism, thermochromism, or color changes caused by multiple excited states. However, these materials are mostly difficult to synthesize and involve complex steps, increasing the cost of use. Furthermore, their diverse properties also result in differences in repeatability and consistency between different batches.
[0005] In the field of spectral detection, enhancing signal intensity and resolution is an important way to improve detection accuracy. However, controlling the spectrum of luminescent materials (which is essentially controlling the energy levels and band gap of semiconductor luminescent materials), especially improving the accuracy and precision of the control, is still quite difficult.
[0006] Therefore, developing precise, refined, repeatable, and stable techniques for controlling the spectra of perovskite quantum dots is key to overcoming the aforementioned application bottlenecks. Summary of the Invention
[0007] To address the challenges of slow exchange rates of insoluble halogen salts in ion exchange, uncontrollable reactions of soluble halogen salts in ion exchange reactions, and the damage to perovskite quantum dot crystals caused by ion exchange reactions, this invention provides a method for regulating the spectra of perovskite quantum dots based on anion exchange at the phase interface.
[0008] In a first aspect, the present invention provides a method for regulating the spectrum of perovskite quantum dots based on anion exchange at the phase interface. The method involves adding a mixed powder of a monovalent halide metal salt and betaine or its derivative to an ABX3 perovskite quantum dot solution, stirring vigorously, and terminating the reaction when the perovskite quantum dot spectrum reaches the desired wavelength. Then, oleylamine (OAm) is added to passivate the surface of the perovskite quantum dots. In the ABX3 perovskite quantum dots, A is any one or more of Cs, MA, and FA, B is Pb, and X is Br.
[0009] Furthermore, the ligands for preparing ABX3 perovskite quantum dots can be any one or more of bis(dodecyl dimethyl ammonium bromide) (DDAB), oleic acid (OA), and OAM.
[0010] Furthermore, the solvent for the ABX3 perovskite quantum dot solution is a nonpolar solvent, which can be any one or more of toluene, n-octane, and n-hexane.
[0011] Furthermore, the monovalent halide metal salt can be any one of lithium chloride (LiCl), sodium chloride (NaCl), potassium chloride (KCl), lithium iodide (LiI), sodium iodide (NaI), and potassium iodide (KI), with lithium chloride or lithium iodide being preferred.
[0012] Furthermore, betaine or its derivatives include compounds with structures described in Formulas 1 to 3, preferably compounds with the structure of Formula 1.
[0013] .
[0014] Furthermore, based on 1 mg of ABX3 perovskite quantum dots (dry weight), 1-2 mg of a monovalent halide metal salt and 1-1.5 mg of betaine or its derivatives are added.
[0015] Furthermore, the reaction can be terminated by centrifugation or filtration.
[0016] Furthermore, 0.02~0.05 μl of oleylamine was added based on 1 mg dry weight of ABX3 perovskite quantum dots.
[0017] In a second aspect, the present invention provides a perovskite quantum dot prepared by the method described in the first aspect.
[0018] Thirdly, the present invention provides the use of perovskite quantum dots prepared by the method described in the first aspect in displays, anti-counterfeiting encryption, or spectral detection.
[0019] Compared with existing technologies, the advantages of this invention are: Betaine or its derivatives promote the dissociation and exchange of halide ions in nonpolar solutions, thereby increasing the reaction rate. Limited reactions at the phase interface control the start and termination thresholds of the reaction, making the reaction rate and extent controllable. Throughout the reaction, perovskite quantum dots are dispersed in the nonpolar solution, suppressing crystal damage. Furthermore, all substances in the reaction except for the perovskite quantum dots are incompatible with nonpolar solvents. Therefore, the reaction can be terminated and the product solution separated by simple filtration or centrifugation, solving the problems of complex processes and high costs. By combining external monitoring methods for continuous production and control, samples at specified wavelengths can be obtained, with good repeatability between different batches, and it is easy to prepare samples with continuous variables to meet industrialization needs. Attached Figure Description
[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below.
[0021] Figure 1 is a schematic diagram of the synthesis of perovskite quantum dot solution and anion exchange reaction process in Example 1.
[0022] Figure 2 shows a comparison of the effects of adding betaine and not adding betaine on ion exchange in Example 1. (a), (b), and (c) show the in-situ changes in sample wavelength during ion exchange at the same time and with the same amount of LiCl, respectively, after using LiCl alone and after using LiCl and betaine in combination. (d), (e), and (f) show the in-situ changes in sample wavelength during ion exchange at the same time and with the same amount of LiCl, respectively, after using LiI alone and after using LiI and betaine in combination. (g) shows a comparison of the changes in luminescence lifetime decay between the original sample and the sample after adding betaine. (h) shows a comparison of the changes in luminescence lifetime decay between the original sample, the sample with added LiCl, and the sample after adding LiCl and betaine. (i) shows a comparison of the changes in luminescence lifetime decay between the original sample, the sample with added LiI, and the sample after adding LiI and betaine.
[0023] Figure 3 shows the characterization data of perovskite quantum dots after anion exchange in Example 1. (a) shows the absorption-emission spectrum of the perovskite quantum dots and a photograph under a UV lamp; (b) shows the X-ray diffraction data; (c) shows the photoluminescence quantum efficiency; (d), (e), and (f) are transmission electron microscopy images of the Cl salt exchanged sample, the original sample, and the I salt exchanged sample, respectively; (g), (h), and (i) are quantum dot size distribution diagrams based on the photographs.
[0024] Figure 4 shows the effect of finely controlling the spectrum of perovskite quantum dots through anion exchange at the solid-liquid interface in Example 1. In the figure, (a) is the PL spectrum of ion exchange in the visible light range, and (b), (c), and (d) show the fine resolution of the PL spectrum in the blue, green, and red ranges, respectively.
[0025] Figure 5 shows the (a) spectrum and (b) CIE coordinates of the R, G, and B three-color perovskite quantum dots used to display the application in Application Example 1.
[0026] Figure 6 shows the demonstration of optical anti-counterfeiting encryption based on color restoration achieved by ion exchange spectral modulation in Application Example 2. (a) shows the PL spectrum and physical photograph of the yellow quantum dot film and the red / green stacked quantum dot film obtained by ion exchange; (b) shows the color coordinates of the emission spectra of the green, red, yellow and stacked films; (c) shows the schematic diagram and physical photograph of the anti-counterfeiting demonstration.
[0027] Figure 7 shows the application of the present invention in the field of spectral detection in Application Example 3. (a) shows the light response curve of the silicon (Si) detector in the visible light range, as well as the light source spectrum and monochromator resolution of the test machine. (b) shows the light response curve obtained on the Si detector using a perovskite quantum dot thick film prepared by ion exchange as a filter. It is mainly divided into three parts: (c) blue light region, (d) green light region, and (e) red light region, and their response curve resolutions. Detailed Implementation
[0028] The present application will be further described below with reference to specific embodiments.
[0029] It should be noted that terms such as "upper", "lower", "left", "right", and "middle" used in this specification are only for clarity of description and are not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as within the scope of this application.
[0030] 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 pertains; the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.
[0031] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.
[0032] As used herein, the term “about” is used to provide for the flexibility and imprecision associated with a given term, measure, or value. Those skilled in the art can readily determine the degree of flexibility for a particular variable.
[0033] As used herein, the term “at least one of…” is intended to be synonymous with “one or more of…”. For example, “at least one of A, B, and C” explicitly includes only A, only B, only C, and combinations thereof.
[0034] The principle of this invention is based on the chemical bond ionic characteristics of halide salts and the regulation of ion binding forces. Suitable halogen donors and additives are screened to achieve a stable, continuous, controllable, and precise anion exchange process. The halide salts proposed in this invention are lithium chloride (LiCl), sodium chloride (NaCl), potassium chloride (KCl), lithium iodide (LiI), sodium iodide (NaI), or potassium iodide (KI). Specifically, the metal halide salts used for blue shift are lithium chloride, sodium chloride, or potassium chloride, while those used for red shift are lithium iodide, sodium iodide, or potassium iodide. The auxiliary additives that promote the anion exchange reaction are betaine or derivative molecules with similar functional group structures. Unlike organic halide salts, using potassium, sodium, or lithium salts avoids the problem of excessive halide ions dissolved in the perovskite quantum dot solution, which could make the exchange reaction difficult to stop. Betaine molecules can reduce the binding energy of ions in the halide salt, accelerating the exchange reaction rate between the solid and liquid phases.
[0035] To illustrate this invention, the following detailed description, in conjunction with figures, embodiments, and application examples, describes the synthesis (which can also be prepared according to existing literature), ion exchange method, corresponding characterization methods, and application demonstrations of the original CsPbBr3 green perovskite quantum dots described in this invention. Example
[0036] Referring to Figure 1, this invention presents a method for finely controlling the spectra of perovskite quantum dots based on a solid / liquid two-phase anion exchange reaction. The CsPbBr3 green perovskite quantum dot solution used for ion exchange is synthesized at room temperature.
[0037] (I) Solution synthesis of CsPbBr3 green perovskite quantum dots
[0038] [1]. Composition of Cs precursor:
[0039] Mix 0.325 g cesium carbonate (Cs2CO3), 2.5 ml octanoic acid (OTAc) + 2.5 ml dodecylbenzenesulfonic acid (DBSA) thoroughly and store away from light.
[0040] To improve the luminescence performance and stability of perovskite quantum dots, Cs2CO3 can be partially replaced with formamidine acetate (FAAc) (with the molar ratio of FA to Cs remaining unchanged), with a doping ratio of 5-30%.
[0041] [2]. Pb precursor composition:
[0042] Dissolve 0.367 g lead bromide (PbBr2) + 1.5 g tetra-n-octylammonium bromide (TOAB) in 30 ml toluene and set aside.
[0043] [3]. Composition of DDAB solution:
[0044] Dissolve 0.5 g of dodecyl dimethyl ammonium bromide (DDAB) in 40 ml of toluene and set aside.
[0045] [4]. Composition of ZnBr2 solution:
[0046] Dissolve 0.225 g zinc bromide (ZnBr2) + 0.1196 g TOAB in 30 ml toluene and set aside.
[0047] [5]. Synthesis method:
[0048] 0.5 ml of Cs precursor was mixed thoroughly with 0.05 g of oleic acid and 0.5 ml of toluene, and then quickly injected into 5 ml of Pb precursor solution. The mixture was stirred at 800 rpm and the timer was started. After 2 min, 1.5 ml of DDAB solution was added and stirring continued. After 3 min, ZnBr2 solution was added and stirring continued. The reaction was stopped after 5 min. The mixture was divided into two portions, and 10 ml of ethyl acetate (EAC) was added to each portion. After centrifugation at 8000 rpm for 1 min, the precipitates were collected. 3 ml of toluene was added to each portion to dissolve the precipitate, and 1.5 ml of DDAB solution was added to each portion to replenish the ligand. Then, 8 ml of EAC was added to each portion, and the mixture was centrifuged at 8000 rpm for 1 min. The precipitate was then dissolved in 2 ml of n-octane and centrifuged again for 2 min at 3000 rpm to obtain the CsPbBr3 supernatant for later use.
[0049] (ii) Anion exchange
[0050] Referring to the ion exchange steps in Figure 1, taking the exchange of LiCl and LiI as an example, when performing blue shift modulation of the spectrum, 20 mg of LiCl and 30 mg of betaine powder were added to 1 ml of CsPbBr3 perovskite quantum dot solution (20 mg / ml in n-octane) and stirred vigorously for 30 min. After centrifugation, the supernatant was collected and 20 μl of OAm solution (50 μl / ml in n-octane) was added for surface passivation. Then, the PL spectrum of the solution was measured. As a comparison, only 20 mg of LiCl powder was added for the above exchange process and the PL spectrum was measured, as well as the PL spectrum of the original solution sample was measured. The data are shown in Figure 2(a). The sample preparation and measurement process for red shift modulation using LiI is the same as above, except that LiCl is replaced with LiI. The data are shown in Figure 2(d). By comparison, it can be found that betaine molecules promote the rate and depth of interfacial anion exchange.
[0051] To measure the changes in in-situ photoluminescence (PL) spectra of LiCl or LiI over time, the following methods were used: For the blue shift measurement, 50 mg of LiCl and 70 mg of betaine powder were added to 3 ml of CsPbBr3 perovskite quantum dot solution (20 mg / ml n-octane) and stirred vigorously. The reaction flask was connected to a spectrometer, and the PL spectrum was measured every 10 s. Measurements were stopped when no significant change in the spectrum was observed. For comparison, only 50 mg of LiCl powder was added for the same exchange process, and the PL spectra were measured. The data are shown in Figures 2(b) and (c). For the red shift measurement, the procedure was the same, but the amounts of LiI and betaine were 30 mg and 50 mg, respectively. The data are shown in Figures 2(e) and (f). The comparison shows that betaine significantly increased the rate of the exchange reaction.
[0052] Figure 2(gi) shows the PL-decay test results of quantum dots after ion exchange with and without betaine, respectively. Figure 2(g) shows the comparison of PL-decay decay curves obtained by testing 1 ml of the original perovskite quantum dot solution (20 mg / ml solvent: n-octane) and the quantum dot solution obtained after adding 20 mg of betaine powder, stirring for 10 min, filtering, and adding 20 μl of OAm solution (50 μl / ml solvent: n-octane). Figure 2(h) shows the comparison of PL-decay decay curves obtained by testing 1 ml of the original perovskite quantum dot solution (20 mg / ml solvent: n-octane), the quantum dot solution obtained after adding 20 mg of LiCl powder, or the quantum dot solution obtained after adding 20 mg of LiCl and 20 mg of betaine powder, stirring to a wavelength of 490 nm, filtering, and adding 20 μl of OAm solution (50 μl / ml solvent: n-octane). Figure 2 (i) shows a comparison of the PL-decay curves obtained from the following quantum dot solutions: 1 ml of the original perovskite quantum dot solution (20 mg / ml in n-octane), 20 mg of LiI powder, and a mixture of 20 mg LiI and 20 mg of betaine powder. After stirring to 630 nm, the solution was filtered and replenished with 20 μl of OAm solution (50 μl / ml in n-octane). Because betaine increases the rate of the exchange reaction, the reaction time to the same wavelength is significantly reduced. The damage to the perovskite quantum dot lattice during the reaction is also less, resulting in fewer lattice defects. Therefore, the lifetime of the product obtained using betaine for exchange is generally higher than that of the sample without betaine.
[0053] Figure 3(a) shows the absorption (UV) and emission (PL) spectra of the ion-exchanged quantum dots and the corresponding photographs. The PL spectrum data at the 520 nm peak is the data for the synthesized original CsPbBr3 green perovskite quantum dots. For samples with peaks below 520 nm, the perovskite quantum dot solution was prepared by adding 20 mg of LiCl and 20 mg of betaine powder to 1 ml of the original sample, stirring vigorously to the specified wavelength, filtering, and adding 20 μl of OAm solution (50 μl / ml of n-octane). The sample preparation method for peaks above 520 nm was the same as above, except that LiCl was replaced with LiI. After sample preparation, the UV and PL spectra of the solutions were measured, and luminescence photographs were taken under UV light (365 nm) excitation. Figures 3(b) and (c) show the X-ray diffraction (XRD) curves and fluorescence quantum efficiency (PLQY) test data of perovskite quantum dot solutions with peak positions at 480 nm, 490 nm, 520 nm, 620 nm, 640 nm, and 670 nm. It can be seen that the shift trend of the XRD peak positions conforms to the trend of lattice contraction and expansion after ion exchange. The PLQY values are generally above 80%, indicating that the novel exchange process causes less lattice damage. Figure 3(df) shows transmission electron microscopy (TEM) images of perovskite quantum dot samples at 480 nm, 520 nm, and 620 nm, respectively. The lattice arrangement is ordered, and the size distribution is uniform. Figure 3(gi) is the perovskite quantum dot size distribution diagram calculated based on the image (df). It can be seen that the introduction of Cl leads to lattice contraction and a decrease in size, while the introduction of I leads to lattice expansion and an increase in size, which conforms to the exchange law.
[0054] Figure 4 demonstrates the fine-tuning effect of the perovskite quantum dot spectrum. Figure 4(a) shows the freely adjustable range of the perovskite quantum dot spectrum in the visible light range of 450-700 nm. Figure 4(bd) shows the resolution data for fine-tuning the spectral peak positions in the blue, green, and red light regions. The resolution remains around 0.5 nm throughout, with high resolutions of 0.39 nm, 0.24 nm, and 0.55 nm achieved in the ranges of 470-480 nm, 515-526 nm, and 640-650 nm, respectively. In the blue light resolution test, 40 mg of LiCl and 60 mg of betaine powder were added to 3 ml of CsPbBr3 perovskite quantum dot solution (20 mg / ml n-octane) and stirred vigorously. The reaction flask was connected to a spectrometer during stirring. Sampling began when the PL peak reached 480 nm. 100 μl of sample solution was taken every 30 seconds, filtered, and then 2 μl of OAm solution (50 μl / ml n-octane) was added until all samples were collected. After sampling, their PL spectra were measured. The red light region test followed the same procedure, except that LiCl was replaced with LiI, and the reagent dosage was 30 mg LiI and 40 mg betaine. In the green light region test, data with wavelengths less than 520 nm were obtained using LiCl, and data with wavelengths greater than 520 nm were obtained using LiI, with the dosage and procedure remaining the same as above.
[0055] Referring to Figure 5, the application verification process proposed in this invention is as follows: Different light-colored perovskite quantum dot solutions were prepared through the above-mentioned anion exchange reaction. The R, G, and B primary color spectra and CIE coordinates exceeding the NTSC standard were selected. Perovskite quantum dot solutions with peak positions of 455 nm, 526 nm, and 633 nm were spin-coated onto glass slides, and their PL spectra were measured. Then, based on the obtained spectra, their CIE coordinates were calculated, and the color gamut range was plotted and compared with the NTSC standard range. The color gamut range obtained by this invention comprehensively exceeds the NTSC standard, possessing more vibrant color display potential.
[0056] Referring to Figure 6, this application example demonstrates an optical encryption application based on the principle of light color reduction. First, following the steps above, perovskite quantum dot solutions with peak positions at 540 nm and 625 nm wavelengths after ion exchange were obtained. The 540 nm green light solution was spin-coated onto a glass slide (10*10 mm), and the 625 nm red light solution was spin-coated onto a polydimethylsiloxane (PDMS) film and cut into small square pieces (10*10 mm). The PDMS film was then attached to the green light film to form a stacked yellow light film. The photoluminescence (PL) spectrum was measured, and the CIE coordinates were calculated based on the spectral data. Ion exchange was then performed, and the PL spectrum and calculated CIE coordinates were monitored until the CIE coordinates of the synthesized yellow perovskite quantum dot solution essentially overlapped with the CIE coordinates of the stacked film. At this point, the peak position of the yellow light solution was 558 nm. Finally, the yellow light solution was spin-coated onto a glass slide to prepare a single-layer yellow light film. The prepared multilayer yellow quantum dot film and single-layer yellow quantum dot film are arranged to form the specified information (here, the letter "T"). The letter represents the multilayer film composition, and the background represents the single-layer film composition. After ultraviolet (365 nm) excitation, the pattern of the luminescent film composition is observed through a filter, revealing the information "T". Figure 6(a) shows the PL spectrum and physical photograph of the yellow quantum dot film and the red / green multilayer quantum dot film obtained by ion exchange; Figure 6(b) shows the color coordinates of the emission spectra of green, red, yellow, and the multilayer film. It can be seen that the colors of yellow and the multilayer film can be almost perfectly reproduced, laying the foundation for optical anti-counterfeiting; Figure 6(c) shows a schematic diagram and physical photograph of the anti-counterfeiting demonstration, showing the mixed film array under the naked eye and the photograph under a red or green filter, respectively, with the information displaying the letter "T".
[0057] Referring to Figure 7, this application example demonstrates its application in the field of spectral detection. First, the photoresponse curves of a commercial Si detector at different wavelengths were measured, and the monochromatic spectrum of the light source after separation by the monochromator confirmed the instrument's accuracy and reliability. Then, 2 mg of dried perovskite quantum dot powder (prepared as described above, with the quantum dot photoresist spectral density controlled within the 470-480 nm, 530-560 nm, and 670-690 nm regions) from the exchanged perovskite quantum dot solution at different peak positions was mixed with polymethyl methacrylate (PMMA in toluene solution) (100 mg / ml) (2 mg powder plus 100 μl PMMA solution). The mixed solution was dropped into a plastic groove mold and allowed to air dry, preparing a perovskite quantum dot thick film. During testing, the film was placed above the Si detector so that the light from the light source was filtered through the thick film before illuminating the Si detector, and its photoresponse curve data were measured. Figure 7(a) shows the photoresponse curve of a silicon (Si) detector in the visible light range, along with the light source spectrum and monochromator resolution of the testing equipment. Figure 7(b) shows the photoresponse curve obtained on a Si detector using a perovskite quantum dot thick film prepared by ion exchange as a filter. It is mainly divided into three parts: the blue light region in Figure 7(c), the green light region in Figure 7(d), and the red light region in Figure 7(e), with response curve resolutions of 0.87 nm, 1.15 nm, and 1.45 nm, respectively. Combined with appropriate algorithm conversion, precise detection of the visible light spectrum can be achieved.
[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.
Claims
1. A method for controlling the spectrum of perovskite quantum dots based on anion exchange at the phase interface, characterized in that, By adding a mixture of monovalent halogen metal salt and betaine or its derivative powder to an ABX3 perovskite quantum dot solution and stirring vigorously, the reaction is terminated when the perovskite quantum dot spectrum reaches the desired wavelength. Then, oleylamine is added to passivate the surface of the perovskite quantum dots. In the ABX3 perovskite quantum dots, A is any one or more of Cs, MA, and FA, B is Pb, and X is Br.
2. The method as described in claim 1, characterized in that, The ligands for preparing ABX3 perovskite quantum dots are any one or more of DDAB, OA, and OAm.
3. The method as described in claim 1, characterized in that, The solvent for the ABX3 perovskite quantum dot solution is a nonpolar solvent.
4. The method as described in claim 1, characterized in that, The monovalent halide metal salt is any one of lithium chloride, sodium chloride, potassium chloride, lithium iodide, sodium iodide, and potassium iodide.
5. The method as described in claim 1, characterized in that, Betaine or its derivatives are compounds with the structures described in Formulas 1 to 3 below: 。 6. The method as described in claim 1, characterized in that, 1-2 mg of a monovalent halide metal salt and 1-1.5 mg of betaine or its derivatives were added based on 1 mg of ABX3 perovskite quantum dots (dry weight).
7. The method as described in claim 1, characterized in that, The reaction can be terminated by centrifugation or filtration.
8. The method as described in claim 1, characterized in that, Add 0.02~0.05 μl of oleylamine based on 1 mg dry weight of ABX3 perovskite quantum dots.
9. A perovskite quantum dot prepared by the method according to any one of claims 1-8.
10. Use of a perovskite quantum dot prepared by the method of any one of claims 1-8 in displays, anti-counterfeiting encryption, or spectroscopic detection.