Water-phase all-inorganic perovskite quantum dot and preparation method and application thereof

Abstract

The invention relates to a water-phase all-inorganic perovskite quantum dot and a preparation method and application thereof, and belongs to the technical field of semiconductor nanomaterials. The method comprises the following steps: mixing brominated acid and oleylamine in a solvent to obtain a zwitterionic ligand solution; a Pb source and an HBr solution are mixed, a first premixed solution is obtained, and the Pb source comprises PbAc2. 3H2O and / or PbAc2; mixing the first premixed solution, CsAc and the zwitterionic ligand solution to obtain a second premixed solution; stirring the second premix, and then carrying out solid-liquid separation to obtain the perovskite quantum dots; the perovskite quantum dots prepared by the method have relatively good water stability, and the preparation process of the method does not need a large dose of toxic chemical reagent and / or inert reaction environment condition, so that the problem that commercialization of the perovskite quantum dots is difficult to realize is improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor nanomaterial technology, and in particular to an aqueous all-inorganic perovskite quantum dot and a preparation method and application thereof. Background Art

[0002] Perovskite quantum dots (PQDs) have rapidly developed in photovoltaics, LEDs, detectors, lasers, and bioimaging due to their inherent advantages, including high optical absorption coefficient, precisely tunable band gap, long carrier diffusion length, high photoluminescence quantum yield (PLQY), and pure emission spectrum. However, the insufficient stability of PQDs in air containing water and oxygen is a major bottleneck limiting their commercial application. In addition, current PQD synthesis processes generally face technical challenges such as the need for large doses of toxic chemicals or inert atmospheres, as well as the economic problem of high raw material costs, which hinders the advancement of large-scale commercialization. Summary of the Invention

[0003] The present application provides an aqueous all-inorganic perovskite quantum dot and its preparation method and application, in order to solve the problem that existing perovskite quantum dots are difficult to achieve large-scale production.

[0004] In a first aspect, the present application provides a method for preparing aqueous all-inorganic perovskite quantum dots, characterized in that the method comprises:

[0005] Mixing the bromo acid and oleylamine in a solvent to obtain a zwitterionic ligand solution;

[0006] Mixing a Pb source and an HBr solution to obtain a first premixed solution, wherein the Pb source includes PbAc2·3H2O and / or PbAc2;

[0007] Mixing the first premix solution, CsAc, and the zwitterionic ligand solution to obtain a second premix solution;

[0008] The second premix is ​​stirred, and then solid-liquid separation is performed to obtain perovskite quantum dots.

[0009] As an optional embodiment, the brominated acid includes at least one of 3-bromopropionic acid, 4-bromobutyric acid or 5-bromovaleric acid.

[0010] As an optional embodiment, the solvent includes at least one of N,N-dimethylformamide, N,N-dimethylacetamide or N,N-dimethylpropionamide.

[0011] As an optional embodiment, the molar ratio of the brominated acid to the oleylamine is 0.9-1.1:0.9-3.3.

[0012] As an optional embodiment, the temperature for mixing the brominated acid and the oleylamine is 40°C to 80°C.

[0013] As an optional embodiment, the brominated acid and the oleylamine are mixed with stirring.

[0014] As an optional embodiment, the pH value of the HBr solution is less than 1.

[0015] As an optional embodiment, the molar ratio of the Pb source to CsAc is 0.8-1:1-1.5.

[0016] As an optional embodiment, the molar ratio of the Pb source to the brominated acid is 0.8-1:2.5-11.

[0017] As an optional embodiment, the molar concentration of the Pb element in the second premix solution is 0.001 mmol / mL to 0.1 mmol / mL.

[0018] In a second aspect, the present application provides an aqueous all-inorganic perovskite quantum dot, which is prepared using the method provided in the first aspect.

[0019] In a third aspect, the present application provides a photoluminescent device, which includes a long-wave layer, and the material of the long-wave layer includes the perovskite quantum dots provided in the second aspect.

[0020] In a fourth aspect, the present application provides an electroluminescent device, comprising a light-emitting layer, wherein the material of the light-emitting layer comprises the perovskite quantum dots provided in the second aspect.

[0021] In a fifth aspect, the present application provides a display device, which includes the photoluminescent device provided in the third aspect and / or the electroluminescent device provided in the fourth aspect.

[0022] In the sixth aspect, the present application provides a fluorescent quantum dot for biological imaging, labeling and sensing, which is soluble in water and can be used for cell labeling, deep tissue imaging, analytical labeling and as an effective fluorescence resonance energy transfer donor. The fluorescent quantum dot includes the perovskite quantum dots provided in the second aspect.

[0023] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0024] The method provided in the embodiment of the present application is to mix bromoacid and oleylamine in a solvent to obtain a zwitterionic ligand solution, and then to mix with a Pb source and an HBr solution to obtain a first premixed solution, and a second premixed solution obtained by mixing with CsAc, and then to stir and perform solid-liquid separation to finally obtain perovskite quantum dots. It has the following advantages: Environmental protection: The use of an aqueous phase synthesis method avoids the toxic solvents used in traditional methods, which is beneficial to environmental protection. Cost control: Through reasonable raw material selection and ratio, it helps to reduce the cost of raw materials and improve economic benefits. The perovskite quantum dots prepared by this method have good water stability, and the preparation process does not require large doses of toxic chemical reagents and / or inert reaction environment conditions, which improves the problem that perovskite quantum dots are difficult to achieve large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0027] Figure 1 A schematic flow chart of the method provided in the embodiment of the present application;

[0028] Figure 2 TEM image of the perovskite quantum dots provided in Example 1 of the present application;

[0029] Figure 3 The XRD pattern of the perovskite quantum dots provided in Example 1 of the present application;

[0030] Figure 4 This is the PL spectrum of the perovskite quantum dots provided in Example 1 of the present application under 365nm excitation;

[0031] Figure 5 This is a graph showing the test results of the internal quantum yield (PLQY) of perovskite quantum dots provided in Example 1 of the present application;

[0032] Figure 6 This is a curve showing the change in PL intensity of the perovskite quantum dots provided in Example 1 of the present application after being stored in water for 40 days. DETAILED DESCRIPTION

[0033] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0034] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0035] The existing processes for synthesizing perovskite quantum dots generally have poor stability, require large doses of toxic chemical reagents or inert reaction environment conditions, and are costly, making them difficult to commercialize.

[0036] To this end, the present application intends to provide an aqueous-phase all-inorganic perovskite quantum dot and its preparation method and application to promote its commercial application.

[0037] Figure 1 A flow chart of the method provided in the embodiment of the present application is shown in FIG. Figure 1 As shown, the embodiment of the present application provides a method for preparing aqueous all-inorganic perovskite quantum dots, characterized in that the method comprises:

[0038] S1. mixing a bromoacid and oleylamine in a solvent to obtain a zwitterionic ligand solution;

[0039] In some embodiments, the brominated acid includes at least one of 3-bromopropionic acid, 4-bromobutyric acid, or 5-bromovaleric acid. The selection of these brominated acids has an important influence on the formation of zwitterionic ligand solutions and the subsequent properties of perovskite quantum dots. 3-Bromopropionic acid: Contains a shorter carbon chain, which is conducive to the formation of smaller perovskite quantum dots. The presence of carboxyl groups and bromine atoms helps to coordinate with raw materials such as Pb sources and CsAc, affecting the structure and performance of quantum dots. 4-Bromobutyric acid: The carbon chain length is moderate, which can provide moderate steric hindrance and help stabilize the structure of quantum dots. It also contains carboxyl groups and bromine atoms, which can be used to adjust the optical properties and stability of quantum dots. 5-Bromopentanoic acid: The carbon chain is longer, which may form larger perovskite quantum dots or provide stronger steric hindrance effects. Long-chain ligands help improve the dispersion and stability of quantum dots.

[0040] The choice of solvent has a significant impact on the reaction and the properties of the product. The solvent includes at least one of N,N-dimethylformamide, N,N-dimethylacetamide, or N,N-dimethylpropionamide, which are used as organic solvents and have a certain polarity and solubility.

[0041] In the preparation of aqueous all-inorganic perovskite quantum dots, the molar ratio of bromoacid to oleylamine is a critical parameter, directly influencing the formation of the zwitterionic ligand solution and the subsequent structure and properties of the perovskite quantum dots. The molar ratio of bromoacid to oleylamine is 0.9-1.1:0.9-3.3. This molar ratio has the following effects: Ligand formation: The molar ratio of bromoacid to oleylamine determines the composition and structure of the zwitterionic ligand. Within this range, the bromoacid and oleylamine react fully to form stable zwitterionic ligands. Quantum dot stability: An appropriate molar ratio promotes the formation of stable perovskite quantum dots. Excessive bromoacid may lead to an overabundance of ligands on the quantum dot surface, affecting luminescence performance; excessive oleylamine may affect the dispersion and stability of the quantum dots. Quantum dot size and shape: Variations in the molar ratio can also affect the size and shape of the perovskite quantum dots. By adjusting the molar ratio, the quantum dot growth process can be regulated, resulting in quantum dots of varying sizes and shapes. Illustratively, the molar ratio of the brominated acid to the oleylamine can be 0.9:0.9, 1:0.9, 1.1:0.9, 0.9:2, 1:2, 1.1:2, 0.9:3, 1:3, 1.1:3, 0.9:3.3, 1:3.3, 1.1:3.3, etc. It can also be any value within the range of 0.9 to 1.1:0.9 to 3.3.

[0042] In some embodiments, the temperature for mixing the brominated acid and oleylamine is 40°C to 80°C, and the brominated acid and oleylamine are stirred during mixing. The temperature range of 40°C to 80°C has a significant effect on the formation of the zwitterionic ligand solution and the subsequent growth and performance of quantum dots, including: within the temperature range of 40°C to 80°C, the brominated acid and oleylamine can be well dissolved in the selected solvent and form a uniform zwitterionic ligand solution, and the appropriate temperature helps to accelerate the SN2 reaction between the brominated acid and oleylamine and promote the formation of zwitterionic ligands. Exemplarily, the temperature for mixing the brominated acid and oleylamine can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, etc., and can also be any value within the range of 40°C to 80°C.

[0043] S2. The Pb source and the HBr solution are mixed to obtain a first premixed solution, wherein the Pb source comprises PbAc2·3H2O (lead acetate trihydrate) and / or PbAc2 (anhydrous lead acetate);

[0044] In some embodiments, the pH value of the HBr solution is less than 1, which can effectively change the solubility of the perovskite precursor and the target crystal product, and is the key to the successful synthesis of aqueous perovskite quantum dots. The pH value of less than 1 indicates that there are a large number of hydrogen ions (H +), thus exhibiting strong acidity. At this point, CsBr maintains its extremely high solubility, while the solubility of the insoluble PbBr2 is significantly improved. Although the solubility of the perovskite CsPbBr3 also increases slightly, it is still several orders of magnitude lower than that of CsBr and PbBr2, allowing the precipitation of perovskite CsPbBr3 crystals. Simultaneously, under the action of the pre-added zwitterionic ligands, CsPbBr3 forms extremely small nanocrystals, the target product, perovskite quantum dots.

[0045] The pH value of the HBr solution can be 0.5, 0.6, 0.7, 0.8, 0.9, etc., and can also be any value within the range of <1.

[0046] S3. mixing the first premix, CsAc (cesium acetate) and the zwitterionic ligand solution to obtain a second premix;

[0047] In some embodiments, the molar ratio of the Pb source to CsAc is 0.8-1:1-1.5. The lower limit of the molar ratio of the Pb source to CsAc is 0.8:1, indicating that at least 0.8 moles of the Pb source are contained in every 1 mole of CsAc. This may be applicable to reaction systems that require less Pb source or more CsAc to adjust the composition or properties of the product. The upper limit of the molar ratio of the Pb source to CsAc is 1:1.5, indicating that 1 mole of the Pb source is contained in every 1.5 moles of CsAc. This may be applicable to reaction systems that require more CsAc to provide sufficient cesium ions, or require reducing the Pb source to control the lead content in the product. Illustratively, the molar ratio of the Pb source to CsAc can be 0.8:1, 0.9:1, 1:1, 0.8:1.2, 0.9:1.2, 1:1.2, 0.8:1.5, 0.9:1.5, 1:1.5, etc., and can also be any value within the range of 0.8 to 1:1 to 1.5.

[0048] In some embodiments, the molar ratio of the Pb source to the brominated acid is 0.8 to 1:2.5 to 11. The lower limit of the molar ratio of the Pb source to the brominated acid is 0.8:2.5, which means that for every 2.5 moles of brominated acid, at least 0.8 moles of Pb source are contained. This ratio may be suitable for scenarios where less Pb source or more brominated acid is needed to regulate the composition or properties of quantum dots. The upper limit of the molar ratio of the Pb source to the brominated acid is 1:11, which means that for every 11 moles of brominated acid, 1 mole of Pb source is contained. This high brominated acid / low Pb source ratio may help form bromine-rich perovskite quantum dots, or be used to adjust the surface ligand density and stability of quantum dots. Illustratively, the molar ratio of the Pb source to the brominated acid can be 0.8:2.5, 0.9:2.5, 1:2.5, 0.8:4, 0.9:4, 1:4, 0.8:6, 0.9:6, 1:6, 0.8:8, 0.9:8, 1:8, 0.8:11, 0.9:11, 1:11, etc., and it can also be any value within the range of 0.8 to 1:2.5 to 11.

[0049] In some embodiments, the molar concentration of the Pb element in the second premix is ​​0.001 mmol / mL to 0.1 mmol / mL. When the molar concentration of the Pb element is 0.001 mmol / mL, it means that a very small amount of Pb element is contained in each milliliter of the second premix. This low concentration may be suitable for scenarios where the amount of Pb source needs to be carefully controlled to avoid excessive Pb source from having a negative impact on the performance of quantum dots. When the molar concentration of the Pb element is 0.1 mmol / mL, it means that a relatively large amount of Pb element is contained in each milliliter of the second premix. This high concentration may be suitable for scenarios where a large number of quantum dots need to be synthesized quickly, or when other reaction conditions (such as temperature, time, etc.) need to be optimized to increase the yield of quantum dots. Illustratively, the molar concentration of the Pb element in the second premix can be 0.001 mmol / mL, 0.01 mmol / mL, 0.02 mmol / mL, 0.03 mmol / mL, 0.04 mmol / mL, 0.05 mmol / mL, 0.06 mmol / mL, 0.07 mmol / mL, 0.08 mmol / mL, 0.09 mmol / mL, 0.1 mmol / mL, etc., and it can also be any value within the range of 0.001 mmol / mL to 0.1 mmol / mL.

[0050] S4. Stirring the second premixed mixture, and then performing solid-liquid separation to obtain perovskite quantum dots. Solid-liquid separation is a conventional technical means in the art, and centrifugal separation may be selected.

[0051] Compared with the existing technology, this method has at least the following beneficial effects:

[0052] 1) The method provided in the embodiments of the present application is carried out at room temperature and in an air environment, does not require inert gas atmosphere protection and expensive experimental equipment, is simple and easy to repeat, and can be mass-produced.

[0053] 2) The method provided in the embodiment of the present application uses water as the reaction solvent, and can synthesize zwitterionic ligand-coated CsPbBr3 quantum dots in situ in water without the need for toxic and expensive organic solvents as the reaction environment. The reaction system is non-toxic, green, safe and environmentally friendly.

[0054] 3) The method provided in the embodiment of the present application uses PbAc2·3H2O, CsAc and HBr as raw materials for synthesizing perovskite. Compared with PbBr2 and CsBr used in the prior art, the cost of raw materials can be significantly reduced.

[0055] 4) The perovskite quantum dots produced by the method provided in the embodiments of the present application have excellent stability in air and even in water, which provides a new research idea for improving the stability of perovskite quantum dots and has broad application prospects in the fields of LED light-emitting devices and biological imaging.

[0056] Based on a general inventive concept, an embodiment of the present application further provides an aqueous all-inorganic perovskite quantum dot, which is prepared using the method provided above.

[0057] The perovskite quantum dots are prepared based on the above method. The specific steps of the method can refer to the above embodiments. Since the perovskite quantum dots adopt part or all of the technical solutions of the above embodiments, they at least have all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0058] Based on a general inventive concept, an embodiment of the present application further provides a photoluminescent device, which includes a long-wave layer, and a material of the long-wave layer includes the perovskite quantum dots provided above.

[0059] The photoluminescent device is realized based on the above-mentioned perovskite quantum dots. The specific content of the perovskite quantum dots can be referred to the above-mentioned embodiments. Since the photoluminescent device adopts part or all of the technical solutions of the above-mentioned embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0060] In some embodiments, the photoluminescent device includes: a short-wave layer and a long-wave layer disposed on the short-wave layer, wherein the short-wave layer is used to emit excitation light; the material of the long-wave layer includes the perovskite quantum dots provided above, and the long-wave layer is used to emit light under the excitation of the excitation light.

[0061] Based on a general inventive concept, an embodiment of the present application further provides an electroluminescent device, which includes a light-emitting layer, and a material of the light-emitting layer includes the perovskite quantum dots provided above.

[0062] The electroluminescent device is realized based on the above-mentioned perovskite quantum dots. The specific content of the perovskite quantum dots can be referred to the above-mentioned embodiments. Since the electroluminescent device adopts part or all of the technical solutions of the above-mentioned embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0063] In some embodiments, the electroluminescent device includes: an anode layer, a hole transport layer, a light-emitting layer, an electron transport layer, and a cathode stacked in sequence, and the material of the light-emitting layer includes the perovskite quantum dots provided above.

[0064] Based on a general inventive concept, an embodiment of the present application further provides a display device, which includes the photoluminescent device and / or electroluminescent device provided above.

[0065] Based on a general inventive concept, an embodiment of the present application also provides a fluorescent quantum dot for biological imaging, labeling and sensing, which is soluble in water and can be used for cell labeling, deep tissue imaging, analytical labeling and as an effective fluorescence resonance energy transfer donor. The fluorescent quantum dot includes the perovskite quantum dots provided in the second aspect.

[0066] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards. If there are no corresponding national standards, then the methods are carried out in accordance with general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

[0067] Example 1

[0068] An aqueous all-inorganic perovskite quantum dot, the preparation process of which is as follows:

[0069] 1. Dissolve 2.2 mmol of bromoacid and 0.75 mL of oleylamine in 1 mL of N,N-dimethylacetamide solvent and heat with stirring at 60°C for more than 6 hours to obtain a zwitterionic ligand solution;

[0070] 2. Add 0.106 mmol of PbAc2·3H2O to a fresh HBr aqueous solution of 1.84 mL of 40 wt% HBr and 6 mL of deionized water to obtain a first premixed solution;

[0071] 3. Add 0.127 mmol of CsAc and 0.45 mL of the zwitterionic ligand solution to the first premix to obtain a second premix;

[0072] 4. The second premixed solution was magnetically stirred at 800 rpm for more than 3 hours, and then centrifuged at 12000 rpm for 15 minutes, and the precipitate was collected to obtain perovskite quantum dots (CsPbBr3 quantum dots).

[0073] Example 2

[0074] An aqueous all-inorganic perovskite quantum dot, the preparation process of which is as follows:

[0075] 1. Dissolve the brominated acid and oleylamine in N,N-dimethylacetamide solvent and heat and stir at 60°C for more than 6 hours to obtain a zwitterionic ligand solution; wherein the molar ratio of the brominated acid to oleylamine is 0.9:3.3;

[0076] 2. PbAc2·3H2O was added to a fresh HBr aqueous solution of 40 wt% HBr and deionized water to obtain a first premixed solution;

[0077] 3. CsAc and zwitterionic ligand solution were added to the first premix to obtain a second premix, wherein the molar ratio of PbAc2·3H2O to CsAc was 0.8:1.5, the molar ratio of PbAc2·3H2O to bromoacid was 0.8:11, and the molar concentration of the Pb element was 0.001 mmol / mL.

[0078] 4. The second premixed solution was magnetically stirred at 800 rpm for more than 3 hours, and then centrifuged at 12000 rpm for 15 minutes, and the precipitate was collected to obtain perovskite quantum dots (CsPbBr3 quantum dots).

[0079] Example 3

[0080] An aqueous all-inorganic perovskite quantum dot, the preparation process of which is as follows:

[0081] 1. Dissolve the brominated acid and oleylamine in N,N-dimethylacetamide solvent and heat and stir at 60°C for more than 6 hours to obtain a zwitterionic ligand solution; wherein the molar ratio of the brominated acid to oleylamine is 1.1:0.9;

[0082] 2. PbAc2·3H2O was added to a fresh HBr aqueous solution of 40 wt% HBr and deionized water to obtain a first premixed solution;

[0083] 3. CsAc and zwitterionic ligand solution were added to the first premix to obtain a second premix, wherein the molar ratio of PbAc2·3H2O to CsAc was 1:1, the molar ratio of PbAc2·3H2O to bromoacid was 1:2.5, and the molar concentration of the Pb element was 0.1 mmol / mL.

[0084] 4. The second premixed solution was magnetically stirred at 800 rpm for more than 3 hours, and then centrifuged at 12000 rpm for 15 minutes, and the precipitate was collected to obtain perovskite quantum dots (CsPbBr3 quantum dots).

[0085] The perovskite quantum dots provided in Examples 1 to 3 were tested using a transmission electron microscope. Since the test results of each example are similar, only the test results of Example 1 are used for illustration. The obtained TEM images are shown in FIG. Figure 2 As shown. Figure 2 It can be seen that the aqueous all-inorganic perovskite quantum dots obtained in this application are specifically CsPbBr3 quantum dots. The size of the CsPbBr3 quantum dots is <5 nm, the morphology is regular and uniform, and they have excellent crystallinity.

[0086] The perovskite quantum dots provided in Examples 1 to 3 were tested by X-ray diffractometer. Since the test results of each example are similar, only the test results of Example 1 are used for description below. The obtained XRD diffraction spectrum is as follows: Figure 3 As shown. Figure 3 It can be seen that the crystal signal of the aqueous all-inorganic perovskite quantum dots CsPbBr3 obtained in this application is very strong, confirming the main crystal component of this perovskite quantum dot.

[0087] The photoluminescence test of the perovskite quantum dots provided in Examples 1 to 3 was performed by fluorescence spectrometer. Since the test results of each example are similar, only the test result of Example 1 is used for description below. The obtained PL spectra (Photoluminescence Spectroscopy, photoluminescence spectrum) are shown as follows: Figure 4 As shown. Figure 4 As can be seen, the half-width at half-maximum (FWHM) of the luminescence from the aqueous all-inorganic perovskite quantum dots obtained in this application is only 18 nm. This narrow FWHM indicates that the resulting CsPbBr3 quantum dots are very uniform in size, demonstrating the reliability of the process. Furthermore, the product has a very pure light color and high application value.

[0088] The photon quantum yield (PLQY) test system was used to test the photon quantum yield of the perovskite quantum dots provided in Examples 1 to 3. Since the test results of each example are similar, only the test results of Example 1 are used for illustration below. The obtained photon quantum yield test results are shown in FIG. Figure 5As shown. Figure 5 It can be seen that the quantum yield of the aqueous all-inorganic perovskite quantum dots obtained in this application is as high as 98.2%, close to 100%, proving that the material has extremely excellent luminescence properties.

[0089] The perovskite quantum dots provided in Examples 1 to 3 were subjected to photoluminescence tests during immersion in water for 40 days. Since the test results of each example are similar, only the test results of Example 1 are used for illustration below. The obtained statistical graph of the change of photoluminescence intensity with immersion time is shown in FIG. Figure 6 As shown. Figure 6 It can be seen that after the aqueous all-inorganic perovskite quantum dots obtained in this application were immersed in water, the photoluminescence intensity still retained 41% of the initial efficiency on the 30th day, and the luminescence was completely annihilated after nearly 40 days, demonstrating excellent water stability.

[0090] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a hard limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numbers within the range. For example, the description of a range from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0091] In this application, unless otherwise specified, the directional words used, such as "upper" and "lower", refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of the present application specification, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" refers to one or more, and "plurality" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e. a and b), ac, bc, or abc, where a, b and c can be single or multiple.

[0092] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for preparing aqueous all-inorganic perovskite quantum dots, characterized in that: The method comprises: Mixing the bromo acid and oleylamine in a solvent to obtain a zwitterionic ligand solution; Mixing a Pb source and a HBr solution to obtain a first premixed solution, wherein the Pb source includes PbAc2·3H2O and / or PbAc2; Mixing the first premix solution, CsAc and the zwitterionic ligand solution to obtain a second premix solution; The second premix is ​​stirred, and then solid-liquid separation is performed to obtain perovskite quantum dots.

2. The method for preparing aqueous all-inorganic perovskite quantum dots according to claim 1, characterized in that: The bromoacid comprises at least one of 3-bromopropionic acid, 4-bromobutyric acid or 5-bromovaleric acid; and / or The solvent comprises at least one of N,N-dimethylformamide, N,N-dimethylacetamide or N,N-dimethylpropionamide; and / or The molar ratio of the brominated acid to the oleylamine is 0.9-1.1:0.9-3.

3.

3. The method for preparing aqueous all-inorganic perovskite quantum dots according to claim 1, characterized in that: The temperature at which the brominated acid and the oleylamine are mixed is 40° C. to 80° C.; and / or The bromo acid and the oleylamine are mixed with stirring.

4. The method for preparing aqueous all-inorganic perovskite quantum dots according to claim 1, characterized in that: The pH value of HBr solution is <1.

5. The method for preparing aqueous all-inorganic perovskite quantum dots according to claim 1, characterized in that: The molar ratio of the Pb source to CsAc is 0.8-1:1-1.5; and / or The molar ratio of the Pb source to the bromo acid is 0.8-1:2.5-11; and / or The molar concentration of the Pb element in the second premixed solution is 0.001 mmol / mL to 0.1 mmol / mL.

6. An aqueous all-inorganic perovskite quantum dot, characterized in that: The perovskite quantum dots are prepared by the method described in any one of claims 1 to 5.

7. A photoluminescent device, characterized in that: The photoluminescent device comprises a long-wave layer, and the material of the long-wave layer comprises the perovskite quantum dots according to claim 6.

8. An electroluminescent device, characterized in that: The electroluminescent device comprises a light-emitting layer, and the material of the light-emitting layer comprises the perovskite quantum dots according to claim 6.

9. A display device, characterized in that: The display device comprises the photoluminescent device according to claim 7 and / or the electroluminescent device according to claim 8.

10. A fluorescent quantum dot, characterized in that: The fluorescent quantum dots can be applied to cell labeling, deep tissue imaging, analytical labeling or as an effective fluorescence resonance energy transfer donor, and the fluorescent quantum dots include the perovskite quantum dots described in claim 6.

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