Synthesis method of lead-free CuCsBr perovskite stable in aqueous solution

Abstract

The invention discloses a method for synthesizing lead-free Cu: CsBr perovskite (Cu: CsBr NCs) stable in an aqueous solution by using a one-pot method, which comprises the following steps of: selecting cesium carbonate, copper bromide and citric acid as reactants, and oleic acid and oleylamine as surface ligands, adding a proper amount of octadecene or mineral oil, performing ultrasonic treatment to obtain a Cu: CsBr-coated CC solution, and centrifuging, purifying and drying the solution to obtain the lead-free Cu: CsBr-coated CC perovskite (Cu: CsBr NCs) stable in the aqueous solution. Cu: CsBr (at) CC powder is obtained. The method disclosed by the invention is simple to operate, short in time and good in repeatability, can be synthesized by only one step, and the prepared compound is good in solubility in an aqueous solution, excellent in dispersity, stable in fluorescence and easy to store.

Description

Technical Field

[0001] This invention belongs to the field of nanoluminescent materials, specifically relating to a method for synthesizing Cu:CsBr NCs stable in aqueous solution using a one-pot method. Background Technology

[0002] Perovskite quantum dots (PQDs) are increasingly being used in various sensing fields due to their high photoluminescence quantum yield, tunable full-spectrum visible spectrum, and simple synthesis methods. However, the environmental and health hazards posed by lead-containing perovskites have prompted researchers to actively explore low-toxicity alternatives. Copper-based perovskites have shown good potential as lead-free alternatives, but their stability in polar solvents remains a major challenge. This invention utilizes citric acid (CC) to coat copper-based perovskite nanocrystals (Cu:CsBr NCs). By leveraging the polyhydroxy and carboxyl groups of citric acid, the surface of Cu:CsBr NCs is passivated, improving its water solubility and stability, and expanding its applications in the biological field. Summary of the Invention

[0003] The purpose of this invention is to provide a method for synthesizing a lead-free Cu:CsBr perovskite (Cu:CsBr@CC) complex that is stable in aqueous solution. This method is simple to operate, requires only one step, is quick, has good reproducibility, and produces a complex powder with good solubility, excellent dispersibility, uniform particle size, stable fluorescence, and is easy to store in aqueous solution. This method is of great significance for improving the stability of lead-free perovskite in aqueous solution.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A lead-free Cu:CsBr perovskite stable in aqueous solution is synthesized by the following steps: (1) Dissolve copper bromide (CuBr2), cesium carbonate (Cs2CO3) and citric acid (CC) in octadecene or mineral oil, and then add oleic acid and oleylamine; (2) The mixture obtained in step (1) is subjected to ultrasonic treatment to obtain a core-shell structure lead-free Cu:CsBr perovskite solution that is fluorescently stable in aqueous solution. (3) Centrifuge the solution obtained in step (2) to remove excess oil phase hydrocarbon solvent, then disperse the obtained precipitate in n-hexane, centrifuge again to remove excess organic ligands and dry to obtain lead-free Cu:CsBr perovskite powder that is fluorescently stable in aqueous solution.

[0005] Further, the molar ratio of copper bromide, cesium carbonate and citric acid in step (1) is 3:1:10 to 3:1:15.

[0006] Furthermore, the volume ratio of octadecene or mineral oil to oleic acid and oleylamine used in step (1) is 20:1:1.

[0007] Furthermore, the power of the ultrasonic treatment in step (2) is 30 W.

[0008] Furthermore, the ultrasonic treatment time in step (2) is 12 min.

[0009] Furthermore, the centrifugation speed in step (3) is 9000 rpm and the time is 10 min.

[0010] Furthermore, the volume ratio of Cu:CsBr@CC perovskite solution to n-hexane used in step (3) is 1:1-1:3.

[0011] Furthermore, the drying temperature in step (3) is 37°C and the drying time is 24 h.

[0012] Citric acid is a common small-molecule organic acid containing multiple carboxyl and hydroxyl groups. It can effectively bind to the surface of Cu:CsBr NCs through coordination, hydrogen bonding, and electrostatic interactions, thereby passivating surface defects and improving stability. Compared with traditional surface ligands, citric acid not only enhances the dispersibility and stability of Cu:CsBr NCs in aqueous environments but also imparts superior biocompatibility through surface modification. This invention encapsulates Cu:CsBr NCs with citric acid (CC). This method is simple to operate, allowing the obtained powder to be directly placed in water or a polar solvent. The preparation time is short, the synthesis method has good reproducibility, and the obtained solution exhibits excellent dispersibility and stability.

[0013] The significant advantages of this invention are: (1) In this invention, Cu:CsBr NCs are encapsulated in CC to improve their stability in aqueous solution. Cu:CsBr NCs encapsulated in CC are not only stable and have excellent fluorescence performance when directly stored in aqueous solution, but also have excellent dispersion performance, uniform particle size in solution, easy product preservation and good biocompatibility.

[0014] (2) The present invention uses a one-step ultrasonic method to mix Cu:CsBr NCs solution and CC. The whole process is short and highly operable. The Cu:CsBr@CC complex can be synthesized in only one step.

[0015] (3) This invention uses Cu:CsBr NCs, which solves the problem of traditional perovskite Pb 2+ The issue of the risk of toxic leakage. Attached Figure Description

[0016] Figure 1This illustrates the effect of different amounts of citric acid on the fluorescence stability of the synthesized composite powder in Example 1.

[0017] Figure 2 Transmission electron microscopy (TEM) images of Cu:CsBr NCs (A) without CC encapsulation and Cu:CsBr@CC complex (B) prepared in Example 2.

[0018] Figure 3 X-ray diffraction (XRD) patterns of CC, Cu:CsBr NCs and Cu:CsBr@CC composite prepared in Example 2.

[0019] Figure 4 The stability curve of the Cu:CsBr@CC complex prepared in Example 2 in aqueous solution is shown. Detailed Implementation

[0020] A lead-free Cu:CsBr perovskite stable in aqueous solution is synthesized by the following steps: (1) Dissolve copper bromide (CuBr2), cesium carbonate (Cs2CO3) and citric acid (CC) in octadecene or mineral oil in a molar ratio of 3:1:10~3:1:15, and then add oleic acid and oleylamine in a volume ratio of 20:1:1 based on the octadecene or mineral oil used to oleic acid and oleylamine. (2) The mixture obtained in step (1) was ultrasonically treated at 30 W for 12 min to obtain a lead-free Cu:CsBr perovskite solution with a core-shell structure that is fluorescently stable in aqueous solution. (3) Centrifuge the solution obtained in step (2) at 9000 rpm for 10 min, discard the supernatant, and remove excess oil phase hydrocarbon solvent; (4) Add the precipitate obtained in step (3) into n-hexane, disperse it by ultrasonication, and then centrifuge the mixed solution at 9000 rpm for 10 min. Discard the supernatant to remove excess organic ligands and obtain the precipitate. (5) After drying the precipitate obtained in step (4) at 37°C for 24 h, a lead-free Cu:CsBr perovskite powder that is fluorescently stable in aqueous solution is obtained.

[0021] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0022] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0023] Example 1: Optimization Experiment of Citric Acid Dosage in Cu:CsBr@CC Complex Weigh 0.10 mmol of cesium carbonate, 0.30 mmol of copper bromide, and 0.05 mmol–2.50 mmol of citric acid. Quickly add 10 mL of octadecene, 0.50 mL of oleic acid, and 0.50 mL of oleylamine to obtain a clear solution. Place the solution in an ultrasonic cell disruptor and sonicate at 30 W for 12 min. The solution gradually changes from clear to deep blue. Stop sonication to obtain a Cu:CsBr@CC complex solution. Centrifuge the complex solution at 9000 rpm for 10 min, discarding excess oil-phase hydrocarbon solvent to obtain a precipitate. Add 15 mL of n-hexane to the precipitate, mix thoroughly by sonication, and centrifuge the solution at 9000 rpm for 10 min. Discard the supernatant to remove excess organic ligands, obtaining another precipitate. Place the precipitate in a vacuum drying oven at 37 °C and dry for 24 h to obtain Cu:CsBr@CC complex powders coated with different amounts of citric acid.

[0024] Figure 1 The effect of different citric acid dosages on the fluorescence stability of the synthesized composite powder is shown, where the ordinate represents the percentage of fluorescence intensity of the composite powder before and after storage in aqueous solution for 120 min. Figure 1 It can be seen that when the amount of citric acid is 1 mmol, the synthesized powder exhibits the best fluorescence stability in aqueous solution.

[0025] Example 2 Preparation of Cu:CsBr@CC complex stable in aqueous solution Weigh 0.10 mmol cesium carbonate, 0.30 mmol copper bromide, and 1.00 mmol citric acid. Quickly add 10 mL octadecene, 0.50 mL oleic acid, and 0.50 mL oleylamine to obtain a clear solution. Place the solution in an ultrasonic cell disruptor and sonicate at 30 W for 12 min. The solution gradually changes from clear to deep blue. Stop sonication to obtain a Cu:CsBr@CC complex solution. Centrifuge the complex solution at 9000 rpm for 10 min, discarding excess oil phase hydrocarbon solvent to obtain a precipitate. Add 15 mL n-hexane to the obtained precipitate, mix thoroughly by sonication, and centrifuge the solution at 9000 rpm for 10 min. Discard the supernatant to remove excess organic ligands, obtaining a precipitate. Place the precipitate in a vacuum drying oven at 37 ℃ and dry for 24 h to obtain a Cu:CsBr@CC complex powder that is fluorescently stable in aqueous solution.

[0026] To further illustrate the features of the present invention, the Cu:CsBr@CC composite powder obtained in the examples was further analyzed.

[0027] Figure 2 Transmission electron microscopy (TEM) images of unencapsulated Cu:CsBr NCs and CC-encapsulated Cu:CsBr@CC (B) prepared in Example 2 are shown. The comparison of the images reveals that the Cu:CsBr NCs in the composite obtained in Example 2 are encapsulated within the CC layer.

[0028] Figure 3 This is the X-ray diffraction pattern of Cu:CsBr NCs after CC embedding in Example 2. From... Figure 3 It can be seen that, compared with the relevant standard cards and the materials used in the synthesis, the structure of the Cu:CsBr@CC composite powder contains characteristic peaks of Cu:CsBr NCs and CC, further proving that Cu:CsBr NCs is wrapped inside CC, and the structure of Cu:CsBr NCs does not change significantly.

[0029] Example 3: Determination of fluorescence stability of Cu:CsBr@CC complex To demonstrate its high fluorescence stability in aqueous solution, 0.2 g of the Cu:CsBr@CC composite powder obtained in Example 2 was weighed and added to 400 μL of deionized water. After sonication for 5 min to mix thoroughly, the mixture was left to stand at room temperature. The fluorescence intensity was measured at intervals using a fluorescence spectrometer (excitation wavelength of 254 nm) (three parallel measurements were taken, and the average value was used). The results are shown in [Figure number missing]. Figure 4 .

[0030] Unencapsulated Cu:CsBr NCs exhibited fluorescence loss after 5 minutes in aqueous solution. However, Cu:CsBr NCs without CC encapsulation showed fluorescence loss. Figure 4 As can be seen, the fluorescence intensity of the encapsulated Cu:CsBr@CC complex solution decreased by only about 9.1% after 120 min, proving that the Cu:CsBr NCs encapsulated with CC can maintain good fluorescence stability in aqueous solution.

[0031] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for synthesizing lead-free Cu:CsBr perovskite stable in aqueous solution, characterized in that: Includes the following steps: (1) Dissolve copper bromide, cesium carbonate and citric acid in octadecene or mineral oil, and then add oleic acid and oleylamine; (2) The mixture obtained in step (1) is subjected to ultrasonic treatment to obtain a core-shell structure lead-free Cu:CsBr perovskite solution that is fluorescently stable in aqueous solution. (3) Centrifuge the solution obtained in step (2), disperse the precipitate in n-hexane, centrifuge again, and dry to obtain lead-free Cu:CsBr perovskite powder that is fluorescently stable in aqueous solution.

2. The synthesis method according to claim 1, characterized in that: The molar ratio of copper bromide, cesium carbonate and citric acid in step (1) is 3:1:10 to 3:1:

15.

3. The synthesis method according to claim 1, characterized in that: The volume ratio of octadecene or mineral oil to oleic acid and oleylamine used in step (1) is 20:1:

1.

4. The synthesis method according to claim 1, characterized in that: The power of the ultrasonic treatment in step (2) is 30W.

5. The synthesis method according to claim 1, characterized in that: The ultrasonic treatment time in step (2) is 12 minutes.

6. The synthesis method according to claim 1, characterized in that: The centrifugation speed in step (3) is 9000 rpm and the time is 10 min.

7. The synthesis method according to claim 1, characterized in that: The drying temperature in step (3) is 37°C and the time is 24 h.

8. A lead-free Cu:CsBr perovskite stable in aqueous solution prepared by any one of claims 1 to 7.

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