A transition metal alloyed low-lead perovskite quantum dot and a preparation method and application thereof

Abstract

The application discloses a transition metal alloyed low-lead perovskite quantum dot and a preparation method and application thereof, and relates to the technical field of luminescent material preparation.The preparation method of the transition metal alloyed low-lead perovskite quantum dot provided by the application uses APTES (3-aminopropyl triethoxysilane) as an ion exchange promoter and utilizes alkaline transition metal halide B(OH)X as a transition metal donor to complete the replacement of transition metal divalent cations with lead ions in a lead-containing perovskite, so that the content of lead in the lead-containing perovskite is reduced to below 50%, and meanwhile, due to the unchanged structure, the fluorescence quantum efficiency of the obtained perovskite is still as high as above 90.6%, and the perovskite has excellent thermal stability, and the fluorescence intensity at a temperature of 100 DEG C can still be kept above 60% of the fluorescence intensity at normal temperature.

Description

Technical Field

[0001] This invention relates to the field of luminescent material preparation technology, specifically to a low-lead perovskite quantum dot alloyed with a transition metal, its preparation method, and its application. Background Technology

[0002] Metal halide perovskite APbX3 (A = Cs, MA, FA, X = Cl, Br, I) quantum dots have enormous application potential in the lighting and display fields due to their extremely high uniform quantum efficiency, narrow and symmetrical tunable emission spectra, high luminous color purity, and low-cost solution synthesis methods. Despite these advantages, lead-based perovskite quantum dots suffer from significant lead toxicity and low thermal, optical, and storage stability, which limits their large-scale commercial application.

[0003] Existing technology discloses a lead-aluminum hybrid perovskite blue quantum dot material, its preparation method, and its applications. Specifically, it provides a hot-injection method, in which a Pb-site precursor of perovskite and a transition metal dopant precursor are first mixed, and then a perovskite A-site precursor is added to construct the APbX3 structure of perovskite. In the lead-aluminum hybrid perovskite quantum dots prepared by this method, the lead sites are replaced by aluminum atoms, reducing the lead content. However, in this prior art, in order to ensure that the perovskite structure does not collapse, the aluminum doping amount at the lead sites needs to be less than or equal to 10%. This leads to a large number of lead vacancy defects in the perovskite at high temperatures, resulting in insufficient thermal stability. At 100°C, the fluorescence intensity drops to less than 50% of the room-temperature fluorescence intensity. Summary of the Invention

[0004] To address the challenge of preparing low-lead perovskite quantum dots with excellent thermal stability using existing technologies, this invention provides a method for preparing low-lead perovskite quantum dots alloyed with transition metals. This method involves reacting lead-containing perovskite APbX3 (A = Cs, MA, FA; X = Cl, Br, I) with a basic transition metal halide B(OH)X in the presence of APTES. The transition metal in the halide can then enter the perovskite lattice and substitute for Pb atoms. Since divalent transition metals are used to replace lead, increasing the doping concentration to over 50% does not cause structural collapse in the perovskite. This reduces the concentration of lead vacancy defects formed at high temperatures, thus enabling the perovskite to exhibit excellent thermal stability.

[0005] Another object of the present invention is to provide a low-lead perovskite quantum dot alloyed with a transition metal.

[0006] Another object of the present invention is to provide an application of low-lead perovskite quantum dots alloyed with transition metals.

[0007] The above-mentioned objective of this invention is achieved through the following technical solution:

[0008] A method for preparing low-lead perovskite quantum dots alloyed with transition metals includes the following steps:

[0009] S1. Prepare APbX3 quantum dot solution, wherein A is any one or more of Cs, MA, and FA, and X is any one or more of Cl, Br, and I;

[0010] S2. Prepare an aqueous solution of B(OH)X, wherein B is any one or more of Zn, Ni, Co, Mn, and Cu, and X is any one or more of Cl, Br, and I;

[0011] S3. Preparation of low-lead perovskite quantum dots alloyed with transition metals: The APbX3 quantum dot solution obtained in step S1 is mixed with the B(OH)X aqueous solution obtained in step S2. The APbX3 quantum dots are reacted with B(OH)X and water in the presence of APTES. After the reaction is completed, low-lead perovskite quantum dots alloyed with transition metals are obtained.

[0012] It should be noted that in step S1 above, MA is methylammonium and FA is methylammonium; the X in APbX3 in step S1 and B(OH)X in step S2 are each independently selected from any one or more of Cl, Br, and I.

[0013] Perovskites are a class of ionic functional materials. The inventors of this application surprisingly discovered in experiments that APTES (3-aminopropyltriethoxysilane), as a silane coupling agent, promotes the exchange of lead ions with other divalent metal ions in perovskites. The key to obtaining low-lead perovskite quantum dots alloyed with transition metals in this invention lies in the use of APTES (3-aminopropyltriethoxysilane) as an ion exchange promoter, which promotes the exchange of B ions in B(OH)X. 2+ Pb in the ionic APbX3 lattice 2+ X - Effective exchange.

[0014] Specifically, in the reaction process of step S3 of the present invention, water molecules in the B(OH)X aqueous solution can effectively remove Pb from the original ionic APbX3 quantum dots. 2+ and halogen X - This process rapidly creates numerous lead and halogen vacancies. Subsequently, the ion exchange promoter APTES facilitates the entry of B(OH)X from the aqueous phase into the APbX3 lattice, filling the water-induced lead and halogen vacancies. This simultaneously completes cation and anion exchange, reducing the lead content in the perovskite and also enabling the removal of divalent metal B from the perovskite. 2+The doping of Pb sites is due to the presence of divalent metal ions, which, in this invention, are doped with Pb. 2+ Having the same amount of charge, it will not cause an imbalance in the charge relationship between A, Pb, and X sites in the perovskite structure, thus allowing the perovskite to maintain its original octahedral structure. Even if the amount of divalent metal doping is increased, the octahedral structure of the perovskite will not collapse due to the imbalance in the charge relationship between A, Pb, and X sites. Therefore, the low-lead perovskite quantum dots in this invention still have excellent fluorescence quantum efficiency.

[0015] Under the influence of APTES, Pb in the APbX3 lattice 2+ It can be largely replaced by divalent metals, forming an alloy-like crystal lattice structure, a process known as "alloying." Meanwhile, due to Pb... 2+ The perovskite obtained by this invention can be largely replaced by divalent metals, which reduces the concentration of lead vacancy defects formed in the perovskite at high temperatures. Therefore, the perovskite obtained by this invention has excellent thermal stability and can maintain good fluorescence intensity at temperatures up to 100°C.

[0016] Commonly used solvents in the art are suitable for the preparation of the APbX3 quantum dot solution in step S1 of this invention. Specifically, the solvent used in this invention can be cyclohexane.

[0017] Conventional methods for preparing APbX3 quantum dot solutions in the art are all applicable to step S1 of this invention.

[0018] Specifically, the preparation of APbX3 quantum dot solution according to the present invention can be as follows: AX, PbX2, oleic acid, and octylamine are dissolved in N,N-dimethylformamide to form a precursor solution, and then MAPbBr3 quantum dots are precipitated in the antisolvent ethyl acetate. After centrifugation to separate the MAPbBr3 quantum dots, they are dispersed in cyclohexane solution to obtain APbX3 quantum dot solution.

[0019] Preferably, the ratio of AX, PbX2, oleic acid, octylamine and N,N-dimethylformamide in the above operation is (1-1.2) mmol: 1 mmol: 0.5 mL: 0.1 mL: 5 mL.

[0020] Specifically, the above operation for precipitating MAPbBr3 quantum dots in the antisolvent ethyl acetate can be performed by taking 0.2 mL of the precursor solution and dropping it into 4 mL of ethyl acetate to precipitate APbX3 quantum dots.

[0021] Specifically, the centrifuge speed can be 10,000 rpm. More specifically, the centrifugation time can be 2 minutes.

[0022] Specifically, the concentration of APbX3 quantum dots after being dispersed in a cyclohexane solution can be 0.005–0.0015 mol / L.

[0023] Conventional methods for preparing B(OH)X aqueous solutions are applicable to step S2 of this invention. Specifically, the operation for preparing B(OH)X aqueous solution according to this invention can be: dissolving BX2 in water and adjusting the pH to alkaline to obtain B(OH)X aqueous solution.

[0024] Any BX2 conventional in the art can be used in the above operations. Specifically, the BX2 used in this invention can be any one or more of ZnBr2, NiBr2, CoBr2, MnBr2, CuBr2, ZnCl2, or ZnI2.

[0025] Specifically, step S3 of this invention, after the reaction is completed, further includes the following steps: allowing the reaction solution to stand to separate into layers, separating the upper cyclohexane solution and centrifuging to obtain the supernatant, thereby obtaining low-lead perovskite quantum dots alloyed with transition metals. More specifically, the centrifugation speed can be 10000 rpm. More specifically, the centrifugation time can be 2 minutes.

[0026] Preferably, B in step S2 is any one or more of Zn, Co, and Cu.

[0027] By using the aforementioned transition metals to dope the Pb sites of perovskites, the ratio of lead-attenuated transition metal atoms (B / (B+Pb)) can reach over 50%, resulting in higher perovskite fluorescence quantum efficiency and thermal stability.

[0028] Preferably, the operation of preparing the B(OH)X aqueous solution in step S2 is as follows: dissolve BX2 in water and adjust the pH to 9-12.

[0029] In a specific embodiment of the present invention, the operation of adjusting the pH after dissolving BX2 in water in step S2 can be achieved by adding an alkaline substance. More specifically, the alkaline substance added in the present invention can be commercially available concentrated ammonia.

[0030] Adjusting the pH of the reaction system to 9–12 can fully convert BX2 to B(OH)X.

[0031] More preferably, the concentration of BX2 dissolved in water in step S2 is 0.02 to 0.10 mol / L.

[0032] Adjusting the above ratio helps control the concentration of B(OH)X in the aqueous solution. A suitable concentration of B(OH)X results in higher ion exchange efficiency.

[0033] More preferably, the ratio of APbX3 quantum dots to B(OH)X aqueous solution in step S3 is APbX3 quantum dots : B(OH)X aqueous solution = (0.02~0.06) mmol : 0.2 mL.

[0034] Ion exchange at the Pb sites of perovskites within the aforementioned range allows for more complete replacement of Pb by transition metal ions.

[0035] Preferably, the ratio of APTES to APbX3 quantum dots in step S3 is APTES:APbX3 = (1~20) μL:0.04 mmol.

[0036] As an ion exchange promoter, the amount of APTES added also affects the amount of Pb sites in APbX3 quantum dots that are replaced by other transition metal ions. Controlling the ratio of APTES to APbX3 quantum dots within the aforementioned range allows for the substitution of Pb sites in perovskites by other transition metal ions. 2+ It is fully replaced by transition metal ions.

[0037] More preferably, the reaction time of APbX3 quantum dots with B(OH)X and water in step S3 is 1 to 10 min.

[0038] A reaction time exceeding 1 minute can enable the Pb site to be deposited. 2+ Pb was fully replaced, but the reaction time exceeded 10 minutes. 2 + The ion exchange reaction between the metal and transition metal ions has been largely completed, and further increasing the reaction time will only lead to increased energy consumption.

[0039] Preferably, X in step S2 is Br.

[0040] When X is Cl, perovskite quantum dots can achieve purer blue light emission, expanding their color gamut. When X is I, the resulting perovskite quantum dots can achieve red light emission. However, when X in B(OH)X is Br, the resulting perovskite quantum dots not only achieve blue light emission but also possess the highest thermal stability and fluorescence quantum efficiency.

[0041] This invention also protects a low-lead perovskite quantum dot alloyed with a transition metal obtained by the above preparation method.

[0042] Preferably, the transition metal doping content in the low-lead perovskite quantum dots alloyed with transition metal is more than 50%.

[0043] It should be noted that the above-mentioned transition metal doping amount refers to the transition metal doping amount at the lead site of perovskite, specifically the proportion of transition metal atoms at the lead site, which can be calculated using B / (B+Pb).

[0044] A transition metal doping level of 50% or higher helps low-lead perovskites maintain excellent fluorescence quantum efficiency while also exhibiting excellent thermal stability.

[0045] Preferably, the average diameter of the low-lead perovskite quantum dots alloyed with the transition metal is 3 to 5 nm.

[0046] The size of quantum dots affects their optical properties. Quantum dots prepared using the method provided in this invention are more conducive to blue light emission when their average diameter is 3–5 nm.

[0047] This invention also protects the application of the aforementioned transition metal alloyed low-lead perovskite quantum dots in optoelectronic displays.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The low-lead perovskite quantum dots prepared by the preparation method provided in this invention, which are alloyed with transition metals, can reduce the lead content to below 50%, achieve a fluorescence quantum efficiency of over 90.6%, and have excellent thermal stability, maintaining more than 60% of the fluorescence intensity at room temperature even at 100°C. Attached Figure Description

[0050] Figure 1 X-ray diffraction patterns of low-lead perovskite quantum dots alloyed with transition metals prepared in Examples 1-5 of this invention.

[0051] Figure 2 The absorption spectrum, emission spectrum, and fluorescence lifetime of the low-lead perovskite quantum dots alloyed with transition metals prepared in Examples 1-5 of this invention are shown.

[0052] Figure 3 Transmission electron microscopy (TEM) images of the low-lead perovskite quantum dots prepared by transition metal alloying in Examples 1-5 of this invention, and their corresponding fluorescence images under ultraviolet light excitation.

[0053] Figure 4 The image shows the size statistics of the low-lead perovskite quantum dots alloyed with transition metals prepared in Examples 1-5 of this invention.

[0054] Figure 5 The elemental composition ratios of the low-lead perovskite quantum dots alloyed with transition metals prepared in Examples 1-5 of this invention are determined by X-ray photoelectron spectroscopy.

[0055] Figure 6 The image shows the fluorescence quantum efficiency of the Zn alloyed low-lead perovskite quantum dots prepared in Example 1 of this invention.

[0056] Figure 7 The image shows the fluorescence quantum efficiency test result of the Zn alloyed low-lead perovskite quantum dots prepared in Example 6 of this invention.

[0057] Figure 8 The image shows the fluorescence quantum efficiency of the Zn alloyed low-lead perovskite quantum dots prepared in Example 7 of this invention.

[0058] Figure 9 A comparison of temperature-dependent fluorescence spectra of MAPbBr3 quantum dots and Zn-alloyed low-lead perovskite quantum dots prepared in Example 1 of this invention.

[0059] Figure 10 These are macroscopic photographs of the products prepared in Comparative Examples 1 and 2 of this invention. Detailed Implementation

[0060] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0061] Example 1

[0062] A method for preparing Zn-alloyed low-lead perovskite quantum dots includes the following steps:

[0063] S1. Preparation of MAPbBr3 quantum dot solution: Weigh 1 mmol of MABr, 1 mmol of PbBr2, 0.5 mL of oleic acid and 0.1 mL of octylamine and dissolve them in 5 mL of N,N-dimethylformamide to form a precursor solution. Take 0.2 mL of the precursor solution and drop it into the antisolvent ethyl acetate to precipitate MAPbBr3 quantum dots. Then, after centrifugation at 10000 rpm for 2 minutes, disperse them in 3 mL of cyclohexane solution.

[0064] S2. Preparation of Zn(OH)Br aqueous solution: Dissolve ZnBr2 in water to a concentration of 0.06 mol / L. Adjust the pH to 10 by adding commercially available concentrated ammonia. The pH is adjusted by adding 2 μL of commercially available concentrated ammonia to every 0.2 mL of water.

[0065] S3. Preparation of low-lead perovskite quantum dots alloyed with transition metals: The MAPbBr3 quantum dot solution obtained in step S1 is mixed with the Zn(OH)Br aqueous solution obtained in step S2. Under the presence of APTES, the MAPbBr3 quantum dots react with Zn(OH)Br and water. After the reaction is complete, Zn alloyed low-lead perovskite quantum dots are obtained.

[0066] The ratio of MAPbBr3 quantum dots to Zn(OH)Br aqueous solution in step S3 is MAPbBr3 quantum dots : Zn(OH)Br aqueous solution = 0.04 mmol : 0.2 mL;

[0067] The ratio of APTES to MAPbBr3 quantum dots in step S3 is 14 μL: 0.04 mmol;

[0068] The reaction time for MAPbBr3 quantum dots with Zn(OH)Br and water in step S3 is 5 min.

[0069] Example 2

[0070] A method for preparing Ni-alloyed low-lead perovskite quantum dots, wherein the difference from Example 1 is:

[0071] S2. Preparation of Ni(OH)Br aqueous solution: Replace ZnBr2 with NiBr2.

[0072] Example 3

[0073] A method for preparing Co-alloyed low-lead perovskite quantum dots, wherein the difference from Example 1 is:

[0074] S2. Preparation of Co(OH)Br aqueous solution: Replace ZnBr2 with CoBr2.

[0075] Example 4

[0076] A method for preparing low-lead perovskite quantum dots alloyed with Mn, wherein the difference from Example 1 is:

[0077] S2. Preparation of Mn(OH)Br aqueous solution: Replace ZnBr2 with MnBr2.

[0078] Example 5

[0079] A method for preparing Cu-alloyed low-lead perovskite quantum dots, wherein the difference from Example 1 is:

[0080] S2. Preparation of Cu(OH)Br aqueous solution: Replace ZnBr2 with CuBr2.

[0081] Example 6

[0082] A method for preparing Zn-alloyed low-lead perovskite quantum dots, wherein the difference from Example 1 is:

[0083] S2. Preparation of Zn(OH)Cl aqueous solution: Replace ZnBr2 with ZnCl2.

[0084] The ratio of APTES to MAPbBr3 quantum dots in step S3 is 18 μL: 0.04 mmol.

[0085] Example 7

[0086] A method for preparing Zn-alloyed low-lead perovskite quantum dots, wherein the difference from Example 1 is:

[0087] S2. Preparation of Zn(OH)I aqueous solution: Replace ZnBr2 with ZnI2.

[0088] The ratio of APTES to MAPbBr3 quantum dots in step S3 is 10 μL: 0.04 mmol.

[0089] Comparative Example 1

[0090] A method for preparing perovskite quantum dots, wherein the difference from Example 1 is:

[0091] In step S2, ZnBr2 is replaced with NaBr.

[0092] Comparative Example 2

[0093] A method for preparing perovskite quantum dots, wherein the difference from Example 1 is:

[0094] In step S3, APTES is replaced with n-PTES (n-propyltriethoxysilane).

[0095] Performance testing

[0096] Fluorescence quantum efficiency test: The quantum dots obtained in the examples and comparative examples were dispersed in 3 mL of cyclohexane solution to obtain quantum dot dispersions. The fluorescence quantum efficiency of the quantum dots was tested using an Edinburgh FLS-980 fluorescence spectrometer with an integrating sphere. The excitation wavelength was 365 nm. The emission spectra of the cyclohexane standard liquid and the quantum dot dispersions obtained in the examples and comparative examples were measured, and the fluorescence quantum efficiency was calculated by integration.

[0097] Thermal stability test: The quantum dot dispersion was poured into a cuvette, and the temperature was controlled by an oil bath heating system. Using an Edinburgh FLS-980 fluorescence spectrometer, the in-situ emission spectrum of the quantum dots at an excitation wavelength of 365 nm was measured in the temperature range of 303 to 373 K. The thermal stability data was obtained by dividing the peak fluorescence intensity at 373 K by the peak fluorescence intensity at 303 K.

[0098] Fluorescence emission and absorption spectroscopy tests: Fluorescence emission spectra were measured using an Edinburgh FLS-980 fluorescence spectrometer. Test method: Fluorescence emission spectra were measured at an excitation wavelength of 365 nm. Absorption spectroscopy tests were performed using a UV-Vis spectrophotometer (Cary 5000, Agilent). The quantum dot dispersion was placed in a cuvette to measure the absorption spectrum.

[0099] Fluorescence lifetime test: Measured using a HORIBA FM-4P time-corrected single-photon counting (TCSPC) system.

[0100] Transition metal doping level test: ICP-OES test was used.

[0101] Specific test data are shown in Table 1 below. Figures 1-10 As shown:

[0102] Table 1. Test data for both examples and comparative examples

[0103]

[0104] As can be seen from Table 1, the low-lead perovskite quantum dots prepared in this invention can exhibit excellent fluorescence quantum efficiency and thermal stability. This is because the Pb sites in the perovskite... 2+ It is a divalent metal B 2+ The replaced divalent metal ions and Pb 2+ Having the same amount of charge, the charge relationship between A, Pb, and X sites in the perovskite structure is not disrupted, allowing the perovskite to maintain its original octahedral structure. Therefore, the low-lead perovskite quantum dots in this invention still exhibit excellent fluorescence quantum efficiency. Simultaneously, the perovskite provided by this invention possesses excellent thermal stability due to the Pb... 2+ The perovskite can be largely replaced by divalent metals (with divalent transition metal doping reaching over 76%), reducing the concentration of lead vacancy defects formed in the perovskite at high temperatures. Therefore, the perovskite obtained by this invention exhibits excellent thermal stability, maintaining over 60% of its room-temperature fluorescence intensity even at temperatures up to 100°C. Data from Examples 1-3 show that controlling X in B(OH)X to be Cl is beneficial for achieving blue light emission from the perovskite quantum dots (Example 2), while controlling X to be I is beneficial for achieving red light emission (Example 3). This demonstrates that the method provided by this invention not only enables the perovskite to possess both excellent fluorescence quantum efficiency and thermal stability but also allows for the modulation of the perovskite emission spectrum. When X in B(OH)X is Br, the resulting perovskite quantum dots not only achieve blue light emission but also exhibit the highest thermal stability and fluorescence quantum efficiency.

[0105] Besides the difference in X in B(OH)X, the ratio of ion exchange promoter APTES to MAPbBr3 quantum dots in Examples 2-3 differs from that in Example 1, resulting in slight differences in the transition metal doping amount in the obtained perovskites. The data shows that increasing the amount of APTES facilitates a more complete ion exchange reaction at the Pb sites of the perovskite, thus slightly increasing the doping amount in the resulting perovskite.

[0106] Figure 1 The images show the X-ray diffraction patterns of the low-lead perovskite quantum dots alloyed with transition metals prepared in Examples 1-5 of this invention. As can be seen from the figures, compared to MAPbBr3, the characteristic diffraction peaks of the perovskites obtained in Examples 1-5 have shifted to higher diffraction angles, indicating that the lattice shrinks after extensive doping with transition metals having smaller ionic radii. This indirectly confirms that Pb sites can be realized in this invention. 2+ Replacement.

[0107] The absorption spectra, emission spectra, and fluorescence lifetimes of the low-lead perovskite quantum dots alloyed with transition metals prepared in Examples 1-5 are as follows: Figure 2 As shown, the emission of the perovskite quantum dots obtained in Examples 1-5 is blue-shifted to around 500 nm, and their fluorescence lifetime is shortened. This is a unique fluorescence phenomenon of quantum dots after Pb site alloying.

[0108] Figure 2 The absorption spectrum, emission spectrum, and fluorescence lifetime of the low-lead perovskite quantum dots alloyed with transition metals prepared in Examples 1-5 of this invention are shown.

[0109] Figure 3 Transmission electron microscopy (TEM) images of the low-lead perovskite quantum dots alloyed with transition metals prepared in Examples 1-5 of this invention, and their corresponding fluorescence images under ultraviolet light excitation. Figure 3 It is evident that most of the quantum dots in this invention can emit blue light, thus broadening the display color gamut.

[0110] Figure 4 This is a size chart showing the transition metal alloyed low-lead perovskite quantum dots prepared in Examples 1-5 of this invention. Figures 3-4 As can be seen, the quantum dot size in Examples 1-5 was reduced to 3-5 nm, and the morphology was uniform.

[0111] Figure 5 The elemental composition ratios obtained by X-ray photoelectron spectroscopy (XPS) analysis of the low-lead perovskite quantum dots alloyed with transition metals prepared in Examples 1-5 of this invention are shown. Figure 5 It can be seen that the Ni doping amount is 39.6%, while the doping amounts of Zn, Co, Mn and Cu are all greater than 50%, which fully demonstrates the significant reduction in Pb content.

[0112] Figures 6-8 The images show the fluorescence quantum efficiency test results of the Zn alloyed low-lead perovskite quantum dots prepared in Examples 1, 6, and 7 of this invention, respectively. Figures 6-8 It can be seen that the fluorescence quantum efficiency of the Zn alloyed low-lead perovskite quantum dots prepared in Examples 1, 6 and 7 of this invention can all reach more than 90%.

[0113] Figure 9 A comparison of the temperature-dependent fluorescence spectra of MAPbBr3 quantum dots and the Zn-alloyed low-lead perovskite quantum dots prepared in Example 1 of this invention. Figure 9 It is evident that the low-lead perovskite quantum dots alloyed with transition metals prepared in this invention exhibit greatly enhanced thermal stability: the fluorescence intensity of MAPbBr3 quantum dots quenched to 3.7% at 100℃, while the fluorescence intensity of the low-lead perovskite quantum dots alloyed with Zn obtained in Example 1 of this invention remained at 75% of the initial intensity at 100℃.

[0114] Figure 10 These are macroscopic photographs of the products prepared in Comparative Examples 1 and 2 of this invention. Figure 10 It is evident that using NaBr in Comparative Example 1 and using amino-free n-propyltriethoxysilane (n-PTES) in Comparative Example 2 both resulted in whitening and fluorescence quenching of the quantum dots, damaging their optical properties. This clearly demonstrates that the ion exchange promoter 3-aminopropyltriethoxysilane (APTES) and basic transition metal halides are key factors in the preparation of transition metal alloyed low-lead perovskite quantum dots in this invention.

[0115] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing low-lead perovskite quantum dots alloyed with transition metals, characterized in that, Includes the following steps: S1. Prepare APbX3 quantum dot solution, wherein A is any one or more of Cs, MA, and FA, and X is any one or more of Cl, Br, and I; S2. Prepare an aqueous solution of B(OH)X, wherein B is any one or more of Zn, Ni, Co, Mn, and Cu, and X is any one or more of Cl, Br, and I; S3. Preparation of low-lead perovskite quantum dots alloyed with transition metals: The APbX3 quantum dot solution obtained in step S1 is mixed with the B(OH)X aqueous solution obtained in step S2. The APbX3 quantum dots are reacted with B(OH)X and water in the presence of APTES. After the reaction is completed, low-lead perovskite quantum dots alloyed with transition metals are obtained.

2. The preparation method according to claim 1, characterized in that, In step S2, B can be any one or more of Zn, Co, and Cu.

3. The preparation method according to claim 1, characterized in that, The procedure for preparing the B(OH)X aqueous solution in step S2 is as follows: dissolve BX2 in water and adjust the pH to 9-12.

4. The preparation method according to claim 3, characterized in that, The concentration of BX2 dissolved in water in step S2 is 0.02–0.10 mol / L.

5. The preparation method according to claim 4, characterized in that, The ratio of APbX3 quantum dots to B(OH)X aqueous solution in step S3 is APbX3 quantum dots : B(OH)X aqueous solution = (0.02~0.06) mmol : 0.2 mL.

6. The preparation method according to claim 1, wherein the ratio of APTES to APbX3 quantum dots in step S3 is APTES:APbX3 = (1~20) μL:0.04 mmol.

7. The preparation method according to claim 6, characterized in that, The reaction time of APbX3 quantum dots with B(OH)X and water in step S3 is 1 to 10 minutes.

8. A low-lead perovskite quantum dot alloyed with a transition metal, prepared by the preparation method according to any one of claims 1 to 7.

9. The low-lead perovskite quantum dots alloyed with transition metals as described in claim 8, characterized in that, The transition metal doping content in the low-lead perovskite quantum dots alloyed with transition metals is more than 50%.

10. The application of a low-lead perovskite quantum dot alloyed with a transition metal as described in claim 8 or 9 in optoelectronic displays.

Images