Method for regulating and controlling perovskite quantum dot spectrum based on phase interface anion exchange

Abstract

The invention discloses a method for regulating and controlling a perovskite quantum dot spectrum based on phase interface anion exchange, and belongs to the technical field of perovskite quantum dots. Monovalent halogen metal salt is used as a halogen donor for anion exchange reaction, betaine or a derivative thereof is used as a catalyst, betaine molecules promote dissolution of the halogen metal salt in a reaction system and break wrapping of organic ligands on the periphery of quantum dots, and a reaction channel is established for ion exchange. According to the invention, the ABX3 perovskite quantum dot realizes halogen anion exchange to form the halogen hybrid perovskite quantum dot, and the luminescence peak position of the halogen hybrid perovskite quantum dot can be freely adjusted in the visible light range of 450-700 nanometers. The method has the advantages of low cost, high regulation and control precision, controllable reaction and the like, and can be applied to the fields of high-definition display, precise photoelectric detection, information encryption and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite quantum dots, and in particular to a method for finely regulating the spectrum of perovskite quantum dots based on a solid / liquid two-phase anion exchange reaction in a perovskite quantum dot solution. Background Art

[0002] As the latest generation of semiconductor light-emitting materials, metal halide perovskites have attracted much attention due to their adjustable band gap, high quantum yield, and strong photoluminescence. The low cost and abundant reserves of raw materials make them have great development prospects. Perovskite quantum dots prepared on this basis combine the advantages of both perovskites and quantum dots. In addition to the original excellent optoelectronic properties, compared with bulk materials, the size effect of quantum dots can further narrow their luminescence spectrum, further improve the photoluminescence efficiency, and the ligand molecules improve their solubility and stability. In addition, the rich surface sites greatly increase the adjustable range of their performance. The narrow half-peak width and the ability to freely adjust the spectral band gap give it great advantages in pure color luminescence and fine spectral control. These good semiconductor optoelectronic properties make it have great application value in high-definition display, information encryption, spectral detection and other fields.

[0003] In the field of high-definition display, the CIE color coordinates of the three primary colors need to be as close to the edge of the color coordinate scale as possible to obtain the color gamut coverage of the display. The size of the range directly affects the degree of color reproduction of the display. Therefore, finding low-cost three primary color materials suitable for display is very important 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 time and space dimensions through their own diverse luminescent properties, such as (electrochromic, photochromic, thermochromic, or color changes caused by multiple excited states). However, most of these materials are difficult to synthesize and the steps are complicated, which increases the cost of use. Their diverse properties also have 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, regulating the spectrum of luminescent materials (which is essentially regulating the energy level and band gap of semiconductor luminescent materials), especially improving the accuracy and precision of regulation, is still relatively difficult.

[0006] Therefore, developing accurate, fine, repeatable and stable control technology for perovskite quantum dot spectra is the key to solving the above application bottlenecks. Summary of the invention

[0007] In order to solve the problems of slow exchange rate of insoluble halogen salts in ion exchange, uncontrollable reaction of soluble halogen salts in ion exchange, and destruction of perovskite quantum dot crystals by ion exchange reactions, the present invention provides a method for regulating the spectrum of perovskite quantum dots based on interfacial anion exchange.

[0008] In the first aspect, the present invention provides a method for regulating the spectrum of perovskite quantum dots based on interfacial anion exchange, by 3 A mixed powder of a monovalent halogen metal salt and betaine or its derivatives is added to the perovskite quantum dot solution and stirred vigorously. When the spectrum of the perovskite quantum dots reaches the desired wavelength, the reaction is terminated and oleylamine (OAm) is added to passivate the surface of the perovskite quantum dots. ABX 3 A in the perovskite quantum dots is any one or more of Cs, MA, and FA, B is Pb, and X is Br.

[0009] Further, ABX is prepared 3 The ligand of the perovskite quantum dots may be any one or more of didodecyldimethylammonium bromide (DDAB), oleic acid (OA), and OAm.

[0010] Furthermore, ABX 3 The solvent of the perovskite quantum dot solution is a non-polar solvent, which can be any one or more of toluene, n-octane, and n-hexane.

[0011] Furthermore, the monovalent halogen metal salt may be any one of lithium chloride (LiCl), sodium chloride (NaCl), potassium chloride (KCl), lithium iodide (LiI), sodium iodide (NaI), and potassium iodide (KI), preferably lithium chloride or lithium iodide.

[0012] Furthermore, betaine or its derivatives include compounds with structures as described in Formula 1 to Formula 3, preferably compounds with structure of Formula 1.

[0013] .

[0014] Furthermore, 1 mg dry weight of ABX 3 For perovskite quantum dots, add 1-2 mg of monovalent halogen metal salt and 1-1.5 mg of betaine or its derivatives.

[0015] Further, the reaction is terminated by centrifugation or filtration.

[0016] Furthermore, 1 mg dry weight of ABX 3 For perovskite quantum dot meter, add 0.02~0.05μl of oleylamine.

[0017] In a second aspect, the present invention provides a perovskite quantum dot prepared by the method described in the first aspect.

[0018] In a third aspect, the present invention provides a use of the perovskite quantum dots prepared by the method described in the first aspect in display, anti-counterfeiting encryption or spectral detection.

[0019] Compared with the prior art, the advantages of the present invention are: betaine or its derivatives promote the dissociation and exchange of halogen ions in non-polar solutions, thereby improving the reaction rate. Through the limited reaction of the phase interface, the starting and termination thresholds of the reaction are controlled, and the reaction rate and degree are controllable. During the entire reaction process, the perovskite quantum dots are dispersed in the non-polar solution, and the damage to the crystal is suppressed. In addition, all substances except the perovskite quantum dots in the reaction are incompatible with non-polar solvents. Therefore, the reaction can be terminated and the product solution can be separated by simple filtration or centrifugation, solving the problem of complex process and cost. By combining external monitoring means for continuous production and continuous regulation, samples of specified wavelengths can be obtained, with good repeatability between different batches, and it is also easy to prepare samples of continuous variables to meet the needs of industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation of the present invention or the technical solution in the prior art, the drawings required for use in the specific implementation or the description of the prior art are briefly introduced below.

[0021] Figure 1 Schematic diagram of the synthesis of the perovskite quantum dot solution and the anion exchange reaction process in Example 1.

[0022] Figure 2 The figures are a comparison of the effects of adding betaine and not adding betaine on ion exchange in Example 1, (a), (b), and (c) are respectively a comparison of the in-situ change trend of the sample wavelength when ion exchange is performed at the same time and the same amount of LiCl after using LiCl alone and LiCl and betaine in combination; (d), (e), and (f) are respectively a comparison of the in-situ change trend of the sample wavelength when ion exchange is performed at the same time and the same amount of LiCl after using LiI alone and LiI and betaine in combination; (g) is a comparison of the changes in luminescence lifetime decay between the original sample and the sample after betaine is added; (h) is a comparison of the changes in luminescence lifetime decay between the original sample, the sample with LiCl added, and the sample with LiCl and betaine added; (i) is a comparison of the changes in luminescence lifetime decay between the original sample, the sample with LiI added, and the sample with LiI and betaine added.

[0023] Figure 3Characterization data of perovskite quantum dots after anion exchange in Example 1, (a) is the absorption-emission spectrum of perovskite quantum dots and a photo under ultraviolet light; (b) is X-ray diffraction data; (c) is the photoluminescence quantum efficiency; (d), (e), and (f) are transmission electron microscope images of the Cl salt exchange sample, the original sample, and the I salt exchange sample, respectively; (g), (h), and (i) are quantum dot size distribution diagrams based on the photos.

[0024] Figure 4 This is a demonstration of the effect of finely controlling the perovskite quantum dot spectrum by anion exchange at the solid-liquid two-phase 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) respectively show the fine resolution of the PL spectrum in the blue, green, and red ranges.

[0025] Figure 5 (a) spectrum and (b) CIE coordinates of R, G, B three-color perovskite quantum dots that can be used for display applications in Application Example 1.

[0026] Figure 6 This is a demonstration of color restoration-based optical anti-counterfeiting encryption based on ion exchange spectrum regulation in Application Example 2. (a) shows the PL spectra and actual photos of the yellow quantum dot film and the red / green stacked quantum dot film obtained by ion exchange; (b) is the color coordinates of the luminescence spectra of green, red, yellow and the stacked film; (c) is a schematic diagram and actual picture of the anti-counterfeiting demonstration.

[0027] Figure 7 To demonstrate the application of the present invention in the field of spectral detection in Application Example 3, (a) is 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) is the light response curve obtained on the Si detector using the perovskite quantum dot thick film prepared by ion exchange as a filter, which 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 DESCRIPTION

[0028] The present application is further described below in conjunction with specific embodiments.

[0029] It should be noted that the terms such as "upper", "lower", "left", "right", "middle", etc. cited in this specification are only for the convenience of description and are not used to limit the scope of implementation. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of this application without substantially changing the technical content.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0031] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0032] As used herein, the term "about" is used to provide flexibility and imprecision associated with a given term, measurement or value. The degree of flexibility for a particular variable can be easily determined by one skilled in the art.

[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" expressly includes only A, only B, only C, and combinations of each thereof.

[0034] The principle of the present invention is: based on the chemical bond ion characteristics of halogen salts and the regulation of ion binding force, suitable halogen donors and additives are screened to achieve a stable, continuous, controllable and precise technical solution for anion exchange. The halogen salts proposed in the scheme are lithium chloride (LiCl), sodium chloride (NaCl), potassium chloride (KCl), lithium iodide (LiI), sodium iodide (NaI) or potassium iodide (KI), wherein the metal halogen salts used for blue shift are lithium chloride, sodium chloride or potassium chloride, and the metal halogen salts 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 halogen salts, the use of potassium, sodium and lithium salts can avoid the dissolution of excessive halogen ions in the perovskite quantum dot solution, which makes the exchange reaction difficult to stop. Betaine molecules can reduce the binding energy of ions in halogen salts and accelerate the exchange reaction rate between solid and liquid phases.

[0035] In order to illustrate the present invention, the original CsPbBr 3 The synthesis of green light perovskite quantum dots (which can also be prepared based on existing literature), ion exchange methods, corresponding characterization methods and application demonstrations are described in detail.

[0036] Embodiment 1:

[0037] Combination Figure 1 The present invention provides a method for finely controlling the spectrum of perovskite quantum dots based on solid / liquid two-phase anion exchange reaction. 3 The green-light perovskite quantum dot solution was synthesized by a room-temperature method.

[0038] 1. CsPbBr 3 Synthesis of green light perovskite quantum dots in solution

[0039] [1]. Cs precursor composition:

[0040] 0.325 g cesium carbonate (Cs 2 CO 3 ), 2.5 ml octanoic acid (OTAc) + 2.5 ml dodecylbenzenesulfonic acid (DBSA), mix well and keep away from light for later use.

[0041] In order to improve the luminescence performance and stability of perovskite quantum dots, Cs can be partially replaced by formamidine acetate (FAAc). 2 CO 3 (the molar number of FA and Cs remains unchanged), and the doping ratio is 5-30%.

[0042] [2]. Pb precursor composition:

[0043] 0.367 g lead bromide (PbBr 2 ) + 1.5 g tetra-n-octylammonium bromide (TOAB) Dissolve in 30 ml toluene and set aside.

[0044] [3]. Composition of DDAB solution:

[0045] Dissolve 0.5 g dodecyldimethylammonium bromide (DDAB) in 40 ml toluene and set aside.

[0046] [4]. ZnBr 2 Solution composition:

[0047] 0.225 g zinc bromide (ZnBr 2 ) + 0.1196 g TOAB was dissolved in 30 ml toluene and set aside.

[0048] [5]. Synthesis method:

[0049] 0.5 ml of Cs precursor was mixed 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 reaction was stirred at 800 rpm and the timing was started. After 2 min, 1.5 ml of DDAB solution was added and stirring was continued. After 3 min, ZnBr was added. 2The solution was stirred continuously and the reaction was stopped after 5 min. The mixture was divided into two parts and 10 ml of ethyl acetate (EAC) was added to each part. After centrifugation at 8000 r / min for 1 min, the precipitate was taken and 3 ml of toluene was added to dissolve each part and 1.5 ml of DDAB solution was added to supplement the ligand. Then 8 ml of EAC was added to each part and centrifuged at 8000 r / min for 1 min. After that, 2 ml of n-octane was used to dissolve all the precipitates and centrifuged again for 2 min. After the speed was 3000 r / min, CsPbBr was obtained. 3 The supernatant was reserved for later use.

[0050] (ii) Anion exchange

[0051] Combination Figure 1 In the ion exchange step, taking the exchange of LiCl and LiI as an example, when adjusting the blue shift of the spectrum, 20 mg of LiCl and 30 mg of betaine powder were added to 1 ml of CsPbBr 3 After the perovskite quantum dot solution (20 mg / ml solvent is n-octane) was stirred vigorously for 30 min, the supernatant was centrifuged and 20 μl OAm solution (50 μl / ml solvent is n-octane) was added for surface passivation, and then the PL spectrum of the solution was measured. For comparison, only 20 mg of LiCl powder was added to carry out the above exchange process and the PL spectrum was measured, and the original solution sample was taken to measure the PL spectrum. The data are shown in Figure 2. Figure 2 The sample preparation and measurement process of using LiI for spectral red shift control is the same as above, only LiCl is replaced by LiI, and the data is shown in Figure 2 As shown in (d) in the figure, by comparison, it can be found that betaine molecules promote the rate and depth of interfacial anion exchange.

[0052] To measure the time-dependent changes of the in-situ PL spectra of LiCl or LiI, 50 mg of LiCl and 70 mg of betaine powder were added to 3 ml of CsPbBr 3 The perovskite quantum dot solution (20 mg / ml solvent is n-octane) was stirred vigorously. During the stirring process, the reaction bottle was connected to a spectrometer and the PL spectrum was measured every 10 s. The measurement was stopped when there was no obvious change in the spectrum. For comparison, only 50 mg of LiCl powder was added to carry out the above exchange process and the PL spectrum was measured. The data is shown in Figure 2 In the measurement of the red shift of the spectrum, the measurement steps are the same as the above process, but the dosage of LiI and betaine is 30 mg and 50 mg respectively. The data are shown in Figure 2As shown in (e) and (f) in Figure 3, betaine significantly increases the rate of the exchange reaction.

[0053] exist Figure 2 In (gi), the PL-decay test results of quantum dots after ion exchange with and without betaine are shown. Figure 2 (g) shows the comparison of PL-decay curves obtained by testing 1 ml of original perovskite quantum dot solution (20 mg / ml solvent: n-octane) and the quantum dot solution obtained by adding 20 mg of betaine powder, stirring for 10 min, filtering and supplementing with 20 ul OAm solution (50 μl / ml solvent: n-octane). Figure 2 (h) is a comparison of the PL-decay curves obtained by testing the quantum dot solution after 1 ml of the original perovskite quantum dot solution (20 mg / ml in n-octane), adding 20 mg LiCl powder, or adding 20 mg LiCl and 20 mg betaine mixed powder and stirring to 490 nm wavelength, filtering and adding 20 ul OAm (50 μl / ml in n-octane). Figure 2 (i) 1 ml original perovskite quantum dot solution (20 mg / ml solvent is n-octane), adding 20 mg LiI powder, and adding 20 mg LiI and 20 mg betaine mixed powder to stir and react until the wavelength is 630 nm, filtering and adding 20 ul OAm solution (50 μl / ml solvent is n-octane) to obtain the PL-decay decay curves of the quantum dot solution tested. Because betaine increases the rate of the exchange reaction, the time spent on the reaction to the same wavelength is greatly reduced, the damage to the perovskite quantum dot lattice during the reaction is also reduced, and the lattice defects caused by the damage are also reduced. The product lifetime obtained by using betaine for exchange is generally higher than that of the sample without betaine.

[0054] Figure 3 (a) shows the absorption (UV) and emission (PL) spectra of the quantum dots after ion exchange and the corresponding physical photos. The characterization data of the PL spectrum at the peak position of 520 nm is the original CsPbBr synthesized 3Data related to green light perovskite quantum dots. The sample preparation method for peaks less than 520 nm is to add 20 mg LiCl and 20 mg betaine mixed powder to 1 ml of the original sample and stir vigorously until the specified wavelength, then take out, filter and add 20 ul OAm solution (50 μl / ml solvent is n-octane) to obtain the perovskite quantum dot solution. The sample preparation method for peaks greater than 520 nm is the same as the above process, except that LiCl is replaced by LiI. After the samples are prepared, the UV and PL spectra of the solution are measured respectively, and luminescence photos are taken under ultraviolet light (365 nm) excitation. Figure 3 (b) and (c) show the X-ray diffraction curves (XRD) and fluorescence quantum efficiency (PLQY) test data of the perovskite quantum dot solution with peaks at 480 nm, 490 nm, 520 nm, 620 nm, 640 nm, and 670 nm. It can be seen that the displacement trend of the XRD peak position is consistent with the trend of lattice contraction and expansion after ion exchange, and the PLQY value is generally above 80%, indicating that the use of the new exchange process has less damage to the lattice. Figure 3 In (df), transmission electron microscope (TEM) images of perovskite quantum dot samples with a diameter of 480 nm, 520 nm, and 620 nm were taken respectively. The lattices are arranged in an orderly manner and the size distribution is uniform. Figure 3 (gi) in the figure is the size distribution diagram of perovskite quantum dots calculated based on the (df) photo. It can be seen that the introduction of Cl causes the lattice to shrink and decrease in size, while the introduction of I causes the lattice to expand and increase in size, which is in line with the exchange law.

[0055] Figure 4 Demonstration of the fine-tuning effect of perovskite quantum dot spectra. Figure 4 (a) shows the free adjustment range of the spectrum of perovskite quantum dots in the visible light range of 450-700 nm. Figure 4 (bd) in the figure is the resolution data of fine-tuning the spectral peak position in the blue, green and red regions. The resolution is maintained at about 0.5 nm throughout the process. The spectrum achieves high resolutions of 0.39 nm, 0.24 nm and 0.55 nm in the ranges of 470-480 nm, 515-526 nm and 640-650 nm, respectively. In the test of the resolution in the blue region, 40 mg of LiCl and 60 mg of betaine powder were added to 3 ml of CsPbBr 3Perovskite quantum dot solution (20 mg / ml solvent is n-octane) and stirred vigorously. During the stirring process, the reaction bottle was connected to the spectrometer. When the PL spectrum peak reached 480 nm, sampling and testing began. 100 μl of sample solution was taken every 30 s and filtered, and then 2 μlOAm solution (50 μl / ml solvent is n-octane) was added until it was finished. After sampling, their PL spectra were tested separately. When testing in the red light region, the steps were roughly the same as above, replacing LiCl with LiI, and the dosage of the drug was 30 mg LiI and 40 mg betaine. When testing in the green light region, the data with a wavelength less than 520 nm was obtained with LiCl, and the data greater than 520 nm was obtained with LiI. The dosage and steps were the same as above.

[0056] Application Example 1

[0057] Combination Figure 5 The application verification implementation process proposed by the present invention is as follows: the perovskite quantum dot solutions of different light colors are prepared by the above-mentioned anion exchange reaction, and the R, G, B primary color matching spectra and CIE coordinates with a color gamut range exceeding the NTSC standard are selected. The perovskite quantum dot solutions with peak positions of 455 nm, 526 nm, and 633 nm are respectively selected and spin-coated on a glass sheet and their PL spectra are measured. Then, their CIE coordinates are calculated based on the obtained spectra and the color gamut range is plotted for comparison with the range of the NTSC standard. The color gamut range obtained by the present invention comprehensively exceeds the NTSC standard and has the potential for more vivid color display.

[0058] Application Example 2:

[0059] Combination Figure 6This application example shows the application of optical encryption based on the principle of light color reduction. First, according to the above steps, a perovskite quantum dot solution with peaks at 540 nm and 625 nm wavelengths after exchange is obtained. First, a green light solution with a wavelength of 540 nm is spin-coated on a glass sheet (size 10*10 mm), and then a red light solution with a wavelength of 625 nm is spin-coated on a polydimethylsiloxane (PDMS) film and cut into square pieces (size 10*10 mm). Then the PDMS film is attached to the green light film to form a stacked yellow light film, and then its PL spectrum is measured, and the CIE coordinates are calculated based on the spectral data. Then, the ion exchange and monitoring of the PL spectrum and the calculated CIE coordinates are performed until the CIE coordinates of the synthesized yellow perovskite quantum dot solution PL spectrum are basically overlapped with the CIE coordinates of the stacked film, and the exchange sampling is stopped. At this time, the peak position of the yellow light solution is 558 nm. Then the yellow light solution is spin-coated on the glass sheet to prepare a single-layer yellow light film. The prepared stacked yellow light film and the single-layer yellow light film are arranged and combined into the specified information (here, the letter "T"). The letter is composed of the stacked film, and the background is composed of the single-layer film. After ultraviolet (365 nm) excitation, the pattern of the luminescent film is observed through the filter, and the information "T" can be revealed. Figure 6 (a) shows the PL spectra and physical photos of the yellow quantum dot film and the red / green stacked quantum dot film obtained by ion exchange; Figure 6 (b) in the figure shows the color coordinates of the luminescence spectra of green, red, yellow and the laminated film. It can be seen that the colors of yellow and the laminated film can be almost perfectly restored, laying the foundation for optical anti-counterfeiting. Figure 6 (c) is a schematic diagram and a real picture of the anti-counterfeiting demonstration, showing the hybrid film array under the naked eye and the photo under the red or green filter, respectively, and the information shows the letter "T".

[0060] Application Example 3: Combination Figure 7 , this application example gives an application demonstration in the field of spectral detection. First, the light response curve of the commercial Si detector at different wavelengths is measured, and the monochromatic light spectrum of the light source after the test instrument monochromator separation confirms that the accuracy of the instrument is reliable. Then, 2 mg of the dried powder of the perovskite quantum dot solution with different peaks after exchange (the preparation method is as described above, and the PL spectrum of the quantum dots obtained by exchange is controlled in the three regions of 470-480 nm, 530-560 nm, and 670-690 nm) is mixed with polymethyl methacrylate (PMMA toluene solution) (100 mg / ml) (2 mg powder plus 100 μl PMMA solution). The mixed solution is dropped into a plastic groove mold and dried naturally to prepare a perovskite quantum dot thick film. During the test, the rear film is placed above the Si detector so that the light source light is filtered through the thick film before irradiating the Si detector, and its light response curve data is tested. Figure 7 (a) shows the light response curve of the silicon (Si) detector in the visible light range, the light source spectrum and the monochromator resolution of the test machine; Figure 7 (b) is the light response curve obtained by using the perovskite quantum dot thick film prepared by ion exchange as a filter on the Si detector, which is mainly divided into Figure 7 The blue light region in (c), the green light region in (d), and the red light region in (e) have response curve resolutions of 0.87 nm, 1.15 nm, and 1.45 nm, respectively. Combined with the corresponding algorithm conversion, precise detection of the visible light spectrum can be achieved.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for regulating the spectrum of perovskite quantum dots based on interfacial anion exchange, characterized in that: The method comprises adding a mixed powder of a monovalent halogen metal salt and betaine or its derivatives to an ABX3 perovskite quantum dot solution, stirring vigorously, terminating the reaction when it is detected that the spectrum of the perovskite quantum dots reaches a desired wavelength, and adding oleylamine to passivate the surface of the perovskite quantum dots, wherein A in the ABX3 perovskite quantum dots is any one or more of Cs, MA, and FA, B is Pb, and X is Br.

2. The method according to 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 according to claim 1, characterized in that The solvent of the ABX3 perovskite quantum dot solution is a non-polar solvent.

4. The method according to claim 1, characterized in that The monovalent halogen metal salt is any one of lithium chloride, sodium chloride, potassium chloride, lithium iodide, sodium iodide and potassium iodide.

5. The method according to claim 1, characterized in that Betaine or its derivatives are compounds with structures described in the following formulas 1 to 3: 。 6. The method according to claim 1, characterized in that Based on 1 mg dry weight of ABX3 perovskite quantum dots, 1-2 mg monovalent halogen metal salt and 1-1.5 mg betaine or its derivatives are added.

7. The method according to claim 1, characterized in that The reaction was terminated by centrifugation or filtration.

8. The method according to claim 1, characterized in that Based on 1 mg dry weight of ABX3 perovskite quantum dots, add 0.02-0.05 μl of oleylamine.

9. A perovskite quantum dot prepared by the method according to any one of claims 1 to 8.

10. Use of the perovskite quantum dots prepared by the method according to any one of claims 1 to 8 in display, anti-counterfeiting encryption or spectral detection.

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