Method for preparing perovskite nanowire based on room-temperature in-situ self-assembly

Abstract

The invention discloses a method for preparing a perovskite nanowire based on room-temperature in-situ self-assembly, the size of the perovskite nanowire is directionally increased through self-assembly growth of a precursor in a solution on the edge of a small-size CsPbBr3 nanocrystal at room temperature, meanwhile, the cross section size of the nanowire is not changed, and the narrow-band-gap optical characteristic is still kept; the all-inorganic perovskite nanowire with smaller surface atom proportion can be obtained through self-assembly at room temperature, higher crystal growth quality can be obtained through the slow growth process at room temperature, the process is beneficial to reducing the internal defect state of the nanowire, and then the optical performance and stability of the perovskite nanowire luminescent material are enhanced; the room-temperature in-situ self-assembly preparation method is simple and efficient, the preparation cost of the perovskite nanowires is reduced, large-scale controllable preparation of the high-quality perovskite nanowires can be realized, and fundamental research on photophysical properties based on the perovskite nanowires and practical application of optoelectronic devices of the perovskite nanowires are promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of nanomaterials for single-photon and optoelectronic devices, and specifically relates to a method for preparing perovskite nanowires based on in-situ self-assembly at room temperature. Background Art

[0002] Low-dimensional semiconductor perovskite nanomaterials are a new type of nanoluminescent material with excellent optical properties, such as high fluorescence quantum efficiency and adjustable emission spectrum in the visible and near-infrared spectrum. At the same time, due to the narrow emission spectrum of perovskite nanocrystals, high color purity fluorescence emission can be produced. This is crucial for display technology and lighting applications because it can meet the practical application requirements of high color saturation and high color purity. In addition, perovskite nanocrystals are synthesized by solution method and have solution processability, and can be surface modified and passivated as needed to change their dispersibility and optical performance stability in various solutions. This allows them to be easily integrated into different matrix materials, such as polymer materials, metal oxide sols and glass. Therefore, perovskite nanocrystals have broad application prospects in the fields of lighting, display backlight, sensing and bioluminescent labeling. Due to their excellent luminescent color purity and fluorescence quantum efficiency, they are important candidate fluorescent materials for high-performance light-emitting devices.

[0003] At present, the preparation methods of all-inorganic metal halide perovskite nanocrystals mainly include hot injection method and room temperature supersaturated recrystallization method. The hot injection method requires a high temperature environment, and the entire preparation process needs to be protected by inert gas. The required preparation cost is high and the operation is difficult, which is not conducive to mass production. The room temperature supersaturated recrystallization method is to form perovskite quantum dots, nanowires or nanosheets by adding a poor solvent to the perovskite precursor solution with the assistance of a long carbon chain organic ligand to achieve isotropic or anisotropic growth of perovskite nanomaterials. By changing the type and ratio of halogen elements in the precursor solution, the luminescence wavelength of perovskite nanomaterials can be precisely controlled at room temperature. At the same time, the method of preparing perovskite nanocrystals at room temperature can achieve a high degree of control over the size, shape and thickness of nanomaterials to meet different practical application requirements. In addition, perovskite nanocrystals prepared at room temperature usually have higher crystal quality and structural consistency. Compared with nanocrystals synthesized by thermal methods, perovskite nanocrystals prepared at room temperature can avoid problems such as lattice defects and uneven morphology at high temperatures, thereby obtaining higher quality perovskite nanocrystals. Therefore, this room-temperature preparation process is relatively simple, does not require complicated high-temperature or inert gas synthesis conditions, and is easier to implement on a large scale.

[0004] It should be noted that despite the advantages mentioned above, perovskite nanocrystals prepared at room temperature still face some challenges, such as poor stability of the crystal structure and optical properties of perovskite nanocrystals, poor size uniformity, and low fluorescence quantum yield. In particular, perovskite nanocrystals prepared at room temperature are prone to regrowth in solution, which causes an uncontrollable increase in the thickness of the nanocrystals, resulting in uncontrollable changes in the morphology of the nanocrystals and their luminescent properties, limiting their practical application in the field of optoelectronic devices. Therefore, further optimization of the room temperature preparation scheme is still needed to solve the above problems in order to fully demonstrate the advantages of preparing high-quality perovskite fluorescent nanocrystals at room temperature. Summary of the invention

[0005] Technical issues solved:

[0006] The present application aims at the deficiencies of the prior art and solves technical problems such as uncertainty in optical properties caused by the regrowth of perovskite nanocrystals in solution at room temperature, and provides a method for preparing perovskite nanowires based on in-situ self-assembly at room temperature, which can not only make small-sized perovskite nanocrystals grow into high-quality nanowires in a directional manner at room temperature through self-assembly, but also meet the requirements of having excellent optical properties and stability of one-dimensional nanowires.

[0007] Technical solution:

[0008] To achieve the above objectives, this application is implemented through the following technical solutions:

[0009] A method for preparing perovskite nanowires based on in-situ self-assembly at room temperature, specifically comprising the following steps:

[0010] The first step is to prepare a precursor solution: 200-500 mg of cesium bromide is dissolved in 3 mL of deionized water according to a mass volume ratio to obtain a solution A; 400-700 mg of lead bromide is dissolved in 3 mL of N,N-dimethylformamide DMF according to a mass volume ratio to obtain a solution B, and the substances in solution A and solution B are subjected to ultrasonic dispersion treatment at a frequency of 40 kHz to uniformly dissolve to obtain a precursor solution;

[0011] The second step is to prepare the perovskite CsPbBr 3 Nanocrystal original solution: 10-30mL of n-hexane is added to a sampling bottle by volume, 1-3mL of oleic acid and 0.1-0.5mL of oleylamine are added, and a mixed solution is obtained by magnetic stirring at room temperature; then 0.5mL of solution A and 0.5mL of solution B are added dropwise to the mixed solution in the sampling bottle by volume, and 1-8mL of acetone solution is added, and the mixture is stirred at a rate of 1500 rpm for 5-20min at room temperature to obtain a perovskite reaction solution; finally, the perovskite reaction solution is centrifuged at a rate of 6000 rpm to obtain the perovskite CsPbBr 3 Nanocrystal stock solution;

[0012] The third step, perovskite CsPbBr 3 In situ self-assembly growth of nanowires: Taking perovskite CsPbBr 3 5 mL of the supernatant of the original nanocrystal solution is diluted by adding 1-10 mL of n-hexane solution; since the concentrations of oleylamine and oleic acid ligands in the solution are reduced to the concentration range of 30%-80%, the diluted small-sized perovskite nanocrystals grow at their edges through self-assembly of the precursor at room temperature, thereby achieving a directional increase in the length of the perovskite nanowires, and the cross-sectional size of the nanowires remains basically unchanged; the nanowires can grow to the micrometer level as the reaction time increases; and the final length of the nanowire sample can be regulated by controlling the aging reaction time.

[0013] Furthermore, in the first step, 384 mg of cesium bromide was dissolved in 3 mL of deionized water to obtain solution A.

[0014] Furthermore, in the first step, 660 mg of lead bromide was dissolved in 3 mL of N,N-dimethylformamide (DMF) to obtain solution B.

[0015] Furthermore, in the second step, 20 mL of n-hexane was added to a sampling bottle, and 2 mL of oleic acid and 0.25 mL of oleylamine were added, and magnetic stirring was performed at room temperature.

[0016] Furthermore, in the second step, 0.5 mL of solution A and 0.5 mL of solution B are respectively added dropwise to the mixed solution in the sampling bottle, and then 1-8 mL of acetone solution is added, and stirred at a rate of 1500 rpm for 10 min at room temperature.

[0017] Furthermore, in the third step, the perovskite CsPbBr 3 5 mL of the supernatant of the original nanocrystal solution was diluted with 5 mL of n-hexane solution to reduce the concentration of oleylamine and oleic acid ligands in the solution to 50% of the concentration of the original solution.

[0018] Principle explanation: Through room temperature in-situ self-assembly, small-sized perovskite nanocrystals are slowly grown into semiconductor perovskites

[0019] Cb 3 Nanowires are used to obtain high-quality perovskite nanowire luminescent materials. The high-performance perovskite nanowire luminescent materials can reach the micron level and have controllable length, so that the prepared perovskite nanowires have good optical properties, high stability, easy mass preparation and low-cost acquisition, which lays a material foundation for promoting the application of the above-mentioned high-quality perovskite nanowire luminescent materials in optoelectronic devices such as single photon sources, and is conducive to promoting the development and application of optoelectronic devices based on perovskite nanowires.

[0020] Beneficial effects:

[0021] The present application provides a method for preparing perovskite nanowires based on in-situ self-assembly at room temperature, which has the following advantages compared with the prior art:

[0022] Beneficial effects:

[0023] 1. The method for preparing perovskite nanowires by in-situ self-assembly at room temperature proposed in this application has good controllability of optical properties. The perovskite nanocrystal seeds achieve one-dimensional lateral directional growth while maintaining the original quantum confinement effect. The fluorescence peak position and half-width of the prepared nanowires remain almost unchanged compared with those of the nanocrystal seeds;

[0024] 2. The appropriate amount of acetone demulsifier in the present application enables the perovskite precursor to form a size-controlled perovskite nanocrystal seed, while the appropriate ligand concentration achieves atomic-level precision control of the thickness of the nanocrystal seed, thereby obtaining a narrow-linewidth perovskite nanowire luminescent material with adjustable luminescent wavelength;

[0025] 3. The present application adds n-hexane to dilute the ligand concentration in the original perovskite nanocrystal solution, so that the precursor in the solution can self-assemble and grow along the edge of the small-sized perovskite nanocrystal seed at room temperature, thereby obtaining a one-dimensional perovskite nanowire material, and the cross-sectional size of the nanowire remains unchanged, and still has a strong quantum confinement effect, that is, the fluorescence peak position of the finally obtained perovskite nanowire remains unchanged, and the half-width of the luminescence peak still maintains the narrow-band emission characteristics;

[0026] 4. The slow directional growth process of perovskite nanowires at room temperature in this application is conducive to improving the crystallization quality of low-dimensional nanowire crystals, and the long nanowire structure reduces the surface atomic ratio of low-dimensional nanomaterials, which is conducive to improving the optical properties and stability of perovskite nanowires;

[0027] 5. The micron-sized perovskite nanowires prepared in this application effectively improve the structural and performance stability of perovskite nanocrystals, and provide a new exploration direction for solving the stability problem faced by small-sized nanocrystals. This method not only has the advantages of simple synthesis, easy control of material properties, and low cost, but also can achieve the batch preparation of uniform micron-sized perovskite nanowires, thus laying a solid material preparation technology foundation for the research and development and application of perovskite nanowire single-photon devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The perovskite CsPbBr in Example 1 of this application 3 Schematic diagram of the preparation process of nanowire self-assembly at room temperature;

[0029] Figure 2 The perovskite CsPbBr in different reaction time stages in Example 1 of the present application 3 Transmission electron microscopy images of nanowires;

[0030] Figure 3 This is a transmission electron microscope image of the final sample of perovskite nanowires of this application;

[0031] Figure 4 For this application, different growth stages of CsPbBr 3 Fluorescence spectra of nanowires and nanocrystal seeds with different luminescence wavelengths; Figure a shows the fluorescence spectra of CsPbBr at different growth stages. 3 There is no obvious broadening and displacement of the fluorescence peak of the nanowires. Figure b shows that the emission peak of the perovskite nanocrystal seeds prepared in other representative embodiments can be adjusted within a certain emission wavelength range.

[0032] Description of reference numerals: 1-precursor solution; 2-oleic acid / oleylamine / n-hexane mixed solution; 3-agitator; 4-CsPbBr after dilution with n-hexane 3 Nanocrystal solution; 5- small size nanocrystal seeds; 6- precursor. DETAILED DESCRIPTION

[0033] In order to further illustrate the present invention, the present invention is further described in detail below in conjunction with embodiments.

[0034] Embodiment 1:

[0035] A method for preparing perovskite nanowires based on in-situ self-assembly at room temperature, specifically comprising the following steps:

[0036] The first step is to prepare a precursor solution 1: 384 mg of cesium bromide is dissolved in 3 mL of deionized water according to a mass volume ratio to obtain a solution A; 660 mg of lead bromide is dissolved in 3 mL of N,N-dimethylformamide DMF according to a mass volume ratio to obtain a solution B, and the substances in solution A and solution B are subjected to ultrasonic dispersion treatment at a frequency of 40 kHz to uniformly dissolve to obtain a precursor solution;

[0037] The second step is to prepare the perovskite CsPbBr 3 Nanocrystal original solution: 20 mL of n-hexane was added to a sampling bottle according to the volume ratio, and 2 mL of oleic acid and 0.25 mL of oleylamine were added, and magnetic stirring was performed at room temperature to obtain an oleic acid / oleylamine / n-hexane mixed solution 2; then 0.5 mL of solution A and 0.5 mL of solution B were added dropwise to the mixed solution in the sampling bottle according to the volume ratio, and 2 mL of acetone solution was added, and stirred at a rate of 1500 rpm for 10 min in a stirrer 3 at room temperature to obtain a perovskite reaction solution; finally, the perovskite reaction solution was centrifuged at a rate of 6000 rpm to obtain the perovskite CsPbBr 3 Nanocrystal stock solution;

[0038] The third step, perovskite CsPbBr 3 In situ self-assembly growth of nanowires: Taking perovskite CsPbBr 35 mL of the original nanocrystal solution supernatant was diluted with 5 mL of n-hexane solution to obtain the diluted CsPbBr 3 Nanocrystalline solution 4; since the concentration of oleylamine and oleic acid ligands in the diluted solution is reduced to 50% of the original concentration, the small-sized nanocrystalline seeds 5 in the solution are self-assembled and grown at their edges by the precursor 6 at room temperature, thereby achieving a directional increase in the length of the perovskite nanowires, and the cross-sectional size of the nanowires remains substantially unchanged, such as Figure 1 As shown in the figure, the nanowires can grow to the micrometer level as the reaction time increases; the final length of the nanowire sample can be regulated by controlling the aging reaction time, and the morphology and size of the perovskite nanomaterials at different growth time nodes can be observed by transmission electron microscopy, as shown in the figure. Figure 2 and 3 As shown, Figure 2 In the experiment, as the reaction time increased, small-sized perovskite nanocrystals achieved self-assembly and directional growth at room temperature. After 3 days, the average length of the nanowires could grow to more than 200 nm. Figure 3 The length of the perovskite nanowires prepared in the present application can reach the micrometer level. The obtained perovskite nanowires are diluted with n-hexane at a ratio of 1:3 and placed in a cuvette, and then placed in a fluorescence spectrometer to measure the luminescence spectrum of the sample, such as Figure 4 As shown, Figure a shows the different growth stages of CsPbBr 3 There is no obvious broadening and displacement of the fluorescence peak of the nanowires. Figure b shows that the emission peak of the perovskite nanocrystal seeds prepared in other representative embodiments can be adjusted within a certain emission wavelength range.

[0039] Embodiment 2:

[0040] A method for preparing perovskite nanowires based on in-situ self-assembly at room temperature, specifically comprising the following steps:

[0041] The first step is to prepare a precursor solution 1: 384 mg of cesium bromide is dissolved in 3 mL of deionized water according to a mass volume ratio to obtain a solution A; 660 mg of lead bromide is dissolved in 3 mL of N,N-dimethylformamide DMF according to a mass volume ratio to obtain a solution B, and the substances in solution A and solution B are subjected to ultrasonic dispersion treatment at a frequency of 40 kHz to uniformly dissolve to obtain a precursor solution;

[0042] The second step is to prepare the perovskite CsPbBr 3Nanocrystal original solution: 20 mL of n-hexane was added to a sampling bottle according to the volume ratio, and 2 mL of oleic acid and 0.25 mL of oleylamine were added, and magnetic stirring was performed at room temperature to obtain an oleic acid / oleylamine / n-hexane mixed solution 2; then 0.5 mL of solution A and 0.5 mL of solution B were added dropwise to the mixed solution in the sampling bottle according to the volume ratio, and 4 mL of acetone solution was added, and stirred at a rate of 1500 rpm for 10 min in a stirrer 3 at room temperature to obtain a perovskite reaction solution; finally, the perovskite reaction solution was centrifuged at a rate of 6000 rpm to obtain the perovskite CsPbBr 3 Nanocrystal stock solution;

[0043] The third step, perovskite CsPbBr 3 In situ self-assembly growth of nanowires: Taking perovskite CsPbBr 3 5 mL of the original nanocrystal solution supernatant was diluted with 5 mL of n-hexane solution to obtain n-hexane-diluted CsPbBr 3 Nanocrystalline solution 4; since the concentration of oleylamine and oleic acid ligands in the solution decreases after dilution, the small-sized nanocrystalline seeds 5 in the solution grow by self-assembly at their edges through the precursor 6 at room temperature, thereby achieving a directional increase in the length of the perovskite nanowires.

[0044] Example 3

[0045] A method for preparing perovskite nanowires based on in-situ self-assembly at room temperature, specifically comprising the following steps:

[0046] The first step is to prepare a precursor solution 1: 384 mg of cesium bromide is dissolved in 3 mL of deionized water according to a mass volume ratio to obtain a solution A; 660 mg of lead bromide is dissolved in 3 mL of N,N-dimethylformamide DMF according to a mass volume ratio to obtain a solution B, and the substances in solution A and solution B are subjected to ultrasonic dispersion treatment at a frequency of 40 kHz to uniformly dissolve to obtain a precursor solution;

[0047] The second step is to prepare the perovskite CsPbBr 3 Nanocrystal original solution: 20 mL of n-hexane was added to a sampling bottle by volume, 2 mL of oleic acid and 0.25 mL of oleylamine were added, and the mixture was uniformly stirred by magnetic stirring at room temperature to obtain oleic acid / oleylamine / n-hexane mixed solution 2; then 0.5 mL of solution A and 0.5 mL of solution B were added dropwise to the mixed solution in the sampling bottle by volume, and 6 mL of acetone solution was added, and the mixture was stirred at 1500 rpm for 10 min in a stirrer 3 at room temperature to obtain a perovskite reaction solution; finally, the perovskite reaction solution was centrifuged at 6000 rpm to obtain perovskite CsPbBr 3 Nanocrystal stock solution;

[0048] The third step, perovskite CsPbBr 3 In situ self-assembly growth of nanowires: Taking perovskite CsPbBr3 5 mL of the original nanocrystal solution supernatant was diluted with 5 mL of n-hexane solution to obtain n-hexane-diluted CsPbBr 3 Nanocrystalline solution 4; since the concentration of oleylamine and oleic acid ligands in the solution decreases after dilution, the small-sized nanocrystalline seeds 5 in the solution grow by self-assembly at their edges through the precursor 6 at room temperature, thereby achieving a directional increase in the length of the perovskite nanowires.

[0049] The luminescent wavelength (450nm-500nm) of the prepared perovskite nanocrystal seed can be adjusted according to the amount of acetone added.

[0050] The above is only a preferred embodiment of the present invention. It should be pointed out that, under the premise of following the principles of the present invention, improved experimental schemes should also be regarded as within the protection scope of the present invention.

Claims

1. A method for preparing perovskite nanowires based on in-situ self-assembly at room temperature, characterized in that: The specific steps include: The first step is to prepare a precursor solution: 200-500 mg of cesium bromide is dissolved in 3 mL of deionized water according to the mass volume ratio to obtain solution A; 400-700 mg of lead bromide is dissolved in 3 mL of N,N-dimethylformamide (DMF) according to the mass volume ratio to obtain solution B. The substances in solution A and solution B are subjected to ultrasonic dispersion treatment at a frequency of 40 kHz to uniformly dissolve to obtain a precursor solution. Step 2: Prepare the original solution of perovskite CsPbBr3 nanocrystals: add 10-30 mL of n-hexane by volume into the sampling bottle, and add 1-3mL oleic acid and 0.1-0.5mL oleylamine are magnetically stirred at room temperature to obtain a mixed solution; then 0.5mL solution A and 0.5mL solution B are respectively added dropwise to the mixed solution in a sampling bottle according to the volume ratio, and then 1-8mL acetone solution is added, and stirred at a rate of 1500 rpm for 5-20min at room temperature to obtain a perovskite reaction solution; finally, the perovskite reaction solution is centrifuged at a rate of 6000 rpm to obtain a perovskite CsPbBr3 nanocrystal original solution; The third step is in-situ self-assembly growth of perovskite CsPbBr3 nanowires: 5 mL of the supernatant of the original perovskite CsPbBr3 nanocrystal solution is taken and diluted with 1-10 mL of n-hexane solution; the addition of n-hexane reduces the concentration of oleylamine and oleic acid ligands in the solution to In the concentration range of 30%-80%, the small-sized perovskite nanocrystals in the solution self-assemble and grow at their edges through the precursor at room temperature, thereby achieving a directional increase in the length of the perovskite nanowires, while the cross-sectional size of the nanowires remains basically unchanged; the nanowires can grow to the micron level as the reaction time increases; and the final length of the nanowire sample can be regulated by controlling the aging reaction time.

2. The method for preparing perovskite nanowires based on in-situ self-assembly at room temperature according to claim 1, characterized in that: In the first step, 384 mg of cesium bromide was dissolved in 3 mL of deionized water to obtain solution A.

3. The method for preparing perovskite nanowires based on in-situ self-assembly at room temperature according to claim 1, characterized in that: In the first step, 660 mg of lead bromide was dissolved in 3 mL of N,N-dimethylformamide (DMF) to obtain solution B.

4. The method for preparing perovskite nanowires based on in-situ self-assembly at room temperature according to claim 1, characterized in that: In the second step, 20 mL of n-hexane was added to a sampling bottle, and 2 mL of oleic acid and 0.25 mL of oleylamine were added, and magnetic stirring was performed at room temperature.

5. The method for preparing perovskite nanowires based on in-situ self-assembly at room temperature according to claim 1, characterized in that: In the second step, 0.5 mL of solution A and 0.5 mL of solution B were respectively added dropwise to the mixed solution in the sampling bottle, and then 1-8 mL of acetone solution was added, and stirred at a rate of 1500 rpm for 10 min at room temperature.

6. The method for preparing perovskite nanowires based on in-situ self-assembly at room temperature according to claim 1, characterized in that: In the third step, 5 mL of the supernatant of the original solution of perovskite CsPbBr3 nanocrystals is taken and 5 mL of n-hexane solution is added to dilute it so that the concentration of oleylamine and oleic acid ligands in the solution is reduced to 50% of the concentration of the original solution.

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