A preparation method of synthesizing inorganic perovskite nanocrystals by a two-phase extraction method and inorganic perovskite nanocrystals

Abstract

This invention relates to the field of nanomaterial preparation technology, specifically to a method for synthesizing inorganic perovskite nanocrystals using a two-phase extraction method, and the inorganic perovskite nanocrystals themselves. The preparation method includes: treating a halide BX2 with a ligand (I) to obtain a clear homogeneous coordination compound; treating it with a weakly polar or nonpolar organic solvent (II) to obtain an oil-phase reaction precursor; dissolving compound AX in water or a polar solvent to obtain an aqueous solution, and mixing it with the oil-phase reaction precursor (III) to form a two-phase layered system; adding a ligand to the two-phase layered system, reacting, and then separating the oil phase to obtain a colloidal perovskite nanocrystal solution. The preparation method of this invention features mild reaction conditions, simple operation, and is suitable for laboratory and industrial production; the product size and morphology are controllable, meeting the needs of different application scenarios; purification is simple, and the solvent can be recovered, reducing solvent consumption and environmental pollution.

Description

Technical Field

[0001] This invention relates to the field of nanomaterial preparation technology, specifically to a method for synthesizing inorganic perovskite nanocrystals using a two-phase extraction method, and the inorganic perovskite nanocrystals themselves. Background Technology

[0002] Inorganic perovskite nanocrystals (such as cesium lead halide CsPbX3, where X = Cl, Br, I) have shown broad application prospects in fields such as light-emitting diodes, lasers, photodetectors, and solar cells due to their excellent optical properties, such as high fluorescence quantum yield, narrow emission half-width, and emission wavelength that can be continuously tuned in the visible light region.

[0003] Currently, common methods for synthesizing inorganic perovskite nanocrystals mainly include the hot-injection method and the ligand-assisted redeposition method. The hot-injection method typically requires high temperature and an inert atmosphere, with harsh reaction conditions and complex operation, making large-scale production difficult. While the ligand-assisted redeposition method can be carried out at room temperature, the resulting nanocrystals have poor size uniformity and are easily affected by solvent polarity, leading to insufficient stability. Furthermore, existing methods often use high-boiling-point, highly polar solvents, requiring the addition of large amounts of antisolvents for purification during post-processing, which not only increases the number of steps but also wastes raw materials and causes environmental pollution.

[0004] Therefore, there is an urgent need to develop a method for preparing inorganic perovskite nanocrystals that is easy to operate, has mild reaction conditions, allows for controllable product size, and is easy to scale up. Summary of the Invention

[0005] The purpose of this invention is to provide a method for synthesizing inorganic perovskite nanocrystals using a two-phase extraction method, and the prepared inorganic perovskite nanocrystals, to solve the problems of harsh reaction conditions, complex operation, poor product uniformity, and difficulty in large-scale production in existing technologies. This invention relies on the interfacial ion assembly effect of a two-phase layered system, combined with coordination complexation and ligand regulation mechanisms, to achieve a mild, controllable, and green synthesis of inorganic perovskite nanocrystals. The obtained products possess characteristics of uniform size, good monodispersity, and excellent optical properties, and the preparation process is adapted to the needs of industrial production.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for preparing inorganic perovskite nanocrystals by two-phase extraction, comprising the following steps: (1) The halide BX2 was mixed with a coordinating agent and treated to obtain a clear homogeneous coordination compound; (2) The homogeneous coordination compound obtained in step (1) is mixed with a weakly polar or non-polar organic solvent and treated to obtain an oil-phase reaction precursor; (3) Dissolve compound AX in water or a polar solvent to obtain an aqueous solution, and mix it with the oil phase reaction precursor obtained in step (2) to form a two-phase layered system; (4) Add ligands to the two-phase layered system obtained in step (3), and after the reaction, separate the oil phase to obtain a colloidal perovskite nanocrystal solution. In the compound AX mentioned in step (3), A is selected from one of cesium, rubidium, silver, and bismuth; X is selected from one or any combination of two of carbonic acid, acetic acid, oleic acid, chlorine, bromine, and iodine.

[0007] As a specific implementation of the present invention, in step (1), in the halide BX2, B is selected from one of lead (Pb), tin (Sn), and manganese (Mn), and X is selected from one of chlorine (Cl), bromine (Br), and iodine (I) or any combination of two of them.

[0008] As a specific embodiment of the present invention, in step (1), the ligand is selected from one or more of oleic acid (OA), trioctylphosphine oxide (TOPO), and trioctylphosphine (TOP), and the heating temperature is 80-170°C.

[0009] As a specific embodiment of the present invention, in step 3, the compound AX is specifically selected from one or more of cesium carbonate, rubidium carbonate, cesium acetate, rubidium acetate, cesium oleate, cesium bromide, and rubidium bromide.

[0010] As a specific implementation of the present invention, in step (2), the weakly polar or non-polar organic solvent is selected from one or more of n-hexane, cyclohexane, heptane, octane, toluene, butyrolactone, caprolactone, and xylene.

[0011] As a specific embodiment of the present invention, in step (4), the ligand is selected from one or more of oleic acid, oleylamine, 2-acryloylamino-2-methylpropanesulfonic acid (AMPS), citric acid or its salt, benzenesulfonamide, polyethylene glycol (PEG) with carboxyl or amino end groups, dimethylaminoethyl acrylate (DMAEA), polyvinylpyrrolidone (PVP), stearic acid, octadecylamine, 1-butyl-1-methylpiperidine tetrafluoroborate, trioctyloxyphosphine, trioctylphosphine, and lecithin.

[0012] As a specific embodiment of the present invention, step (1) mixing process is carried out by heating.

[0013] As a specific embodiment of the present invention, the heating conditions include: a heating temperature of 80 to 170°C and a heating time of 20 to 60 minutes.

[0014] As a specific implementation of the present invention, step (2) mixing II is performed by ultrasound or stirring.

[0015] As a specific embodiment of the present invention, step (3) mixing III is carried out by heating.

[0016] As a specific embodiment of the present invention, the heating conditions include: a heating temperature of 60~110℃; and a heating time of 30~80min.

[0017] As a specific embodiment of the present invention, in step (4), the stirring reaction time is 10 to 30 minutes and the reaction temperature is room temperature.

[0018] Secondly, an inorganic perovskite nanocrystal is provided, which is prepared by the above-mentioned method.

[0019] As a specific embodiment of the present invention, the synthesized inorganic perovskite nanocrystals have a morphology of one of cubic, cuboid, one-dimensional nanowire, two-dimensional nanosheet or sphere.

[0020] As a specific embodiment of the present invention, the inorganic perovskite nanocrystals have a particle size or edge length of 3nm to 100nm and are monodisperse.

[0021] Thirdly, the application of the aforementioned inorganic perovskite nanocrystals in the fields of light-emitting diodes, lasers, photodetectors, or solar cells is provided.

[0022] The preparation method of this invention is based on the interfacial reaction mechanism of two-phase extraction. Its core innovation lies in: using the difference in solvent polarity to construct a stable two-phase layered system, so that the synthesis reaction of perovskite nanocrystals is confined to the phase interface, realizing the controllable assembly of ions; at the same time, by combining coordination complexation and ligand regulation, the size and morphology of the product can be precisely controlled, and the product spontaneously accumulates in the oil phase, eliminating the need for anti-solvent purification and greatly simplifying the post-processing process. Beneficial effects

[0023] The reaction conditions are mild and the operation is simple: This invention uses a two-phase extraction method, which can complete the reaction at room temperature or low temperature. It does not require high temperature, high pressure or inert gas protection, which significantly reduces the synthesis threshold and is suitable for laboratory and industrial production.

[0024] Product size and morphology are controllable: By adjusting parameters such as the type of ligand, ligand composition, reaction time and halogen ratio, the nanocrystal size, morphology and emission wavelength can be precisely controlled to meet the needs of different application scenarios.

[0025] Purification is simple and solvent can be recovered: the reaction takes place at the interface between two phases, and the product is directly enriched in the oil phase. Separation can be achieved without the addition of antisolvent, which simplifies the post-processing process and reduces solvent consumption and environmental pollution.

[0026] Wide range of applications: The method of this invention is applicable to a variety of halide combinations and doping systems, and can synthesize single halogen, mixed halogen and doped perovskite nanocrystals, with excellent versatility and scalability. Attached Figure Description

[0027] Figure 1 This is a transmission electron microscope image of the CsPbBr3 cubic perovskite nanocrystals prepared in Example 1 of the present invention.

[0028] Figure 2 This is a photoluminescence image of CsPbCl3 nanocrystals prepared in Example 2 of the present invention.

[0029] Figure 3 This is a transmission electron microscope image of the CsPbBr3 perovskite nanowires prepared in Example 4 of this invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. However, it should be understood that the following embodiments are for illustrative purposes only and not for limiting the scope of the invention. All technical solutions implemented based on the content of this invention fall within the scope of protection of this invention.

[0031] Example 1: Preparation of CsPbBr3 cubic perovskite nanocrystals (green light) by two-phase extraction method (1) Take a clean and dry three-necked flask, add 0.367 g (1.0 mmol) of PbBr2 and 2.0 g of trioctylphosphine oxide (TOPO), heat to 140 °C under nitrogen protection and keep warm for 30 min until the system changes from turbid to clear, and obtain a clear homogeneous coordination compound.

[0032] (2) Cool the coordination halide solution from step (1) to about 80°C, add 10 mL of n-hexane, and sonicate continuously for 10 min (or stir magnetically for 20 min) at 60–80°C until completely clear, to obtain a clear oil phase reaction precursor.

[0033] (3) Take another beaker and dissolve 0.213g (1.0mmol) of CsBr in 5mL of deionized water to obtain a transparent aqueous solution. Place the aqueous solution and the oil phase reaction precursor obtained in step (2) in the same closed reaction vessel to form obvious stratification and obtain a two-phase system.

[0034] (4) Add 0.5 mL of ligand mixture OA and 0.5 mL of oleylamine (OAm) to the two-phase system and stir slowly at room temperature for 20 min. After the reaction is completed, let it stand and separate into layers, take out the upper oil phase liquid, and obtain colloidal inorganic perovskite nanocrystal (CsPbBr3) solution.

[0035] The resulting colloidal solution exhibits bright green fluorescence. Figure 2 Transmission electron microscopy images of the prepared inorganic perovskite nanocrystals are shown below. Figure 1 It can be seen that the inorganic perovskite nanocrystals have a cubic morphology with an average side length of about 8–12 nm and a relatively concentrated particle size distribution.

[0036] Example 2: Preparation of CsPbCl3 nanocrystals (blue light) by two-phase extraction method (1) Add 0.278 g (1.0 mmol) of PbCl2 and 1.5 mL of trioctylphosphine (TOP) to a three-necked flask, heat to 160 °C and keep warm for 30 min to obtain a clear homogeneous coordination halide.

[0037] (2) Add the coordination halide from step (1) to 12 mL of cyclohexane and sonicate continuously at 70 °C for 15 min (or stir until clear) to obtain the oil phase reaction precursor.

[0038] (3) Weigh 0.168g (1.0mmol) of CsCl and dissolve it in 6mL of deionized water to obtain an aqueous solution; place the aqueous solution and the oil phase reaction precursor obtained in step (2) in the same container to obtain a two-phase system.

[0039] (4) Add ligand / inducer to the two-phase system: 0.6 mL of oleylamine + 20 mg of AMPS (2-acrylamide-2-methylpropanesulfonic acid), stir slowly for 10–15 min; after the reaction, remove the oil phase to obtain colloidal CsPbCl3 nanocrystal solution.

[0040] Characterization results: The colloidal solution was light-colored to colorless and transparent, and exhibited blue fluorescence under ultraviolet light. Figure 2 The nanocrystal size can be controlled within 5–10 nm, and the dispersion is good.

[0041] Example 3: Preparation of CsPb(Br / I)3 mixed halide nanocrystals by two-phase extraction method (orange-red light, tunable emission) (1) Add 0.184 g (0.5 mmol) of PbBr2, 0.231 g (0.5 mmol) of PbI2, and 2.0 g of TOPO to a three-necked flask, heat to 150 °C and keep warm for 30 min until the system is clear, and obtain a homogeneous coordination compound containing mixed halogens.

[0042] (2) Add 10 mL of n-octane to the coordination halide obtained in step (1) and stir or sonicate at 80–90 °C until clear to obtain the oil phase reaction precursor.

[0043] (3) Take another beaker and dissolve 0.106g (0.5mmol) of CsBr and 0.130g (0.5mmol) of CsI in 6mL of deionized water to obtain an aqueous solution; place the aqueous solution and the oil phase reaction precursor obtained in step (2) in the same container to obtain a two-phase system.

[0044] (4) Add the ligand mixture to the two-phase system: 0.5 mL of oleic acid + 50 mg of PVP, and stir slowly for 20–30 min. After the reaction, separate the oil phase and obtain a mixed halide perovskite nanocrystal colloidal solution.

[0045] Characterization results: The colloidal solution exhibits orange to red fluorescence under ultraviolet irradiation; the emission peak position can be continuously adjusted in the visible light region by adjusting the Br / I molar ratio; the nanocrystal size is usually 8–20 nm, and the morphology is mainly cubic / cuboidal.

[0046] Example 4: Preparation of CsPbBr3 perovskite nanowires by two-phase extraction method (1) Add 0.279 g (1.0 mmol) of PbBr2 and 1.0 mL of TOP to a three-necked flask, heat to 120 °C and keep warm for 30 min to obtain a clear homogeneous coordinated halide.

[0047] (2) Add the coordination halide obtained in step 1 to 10 mL of heptane and sonicate at 70 °C for 10 min until clear to obtain the oil phase reaction precursor.

[0048] (3) Take another beaker and dissolve 0.163g (0.5mmol) of Cs2CO3 in 5mL of deionized water (if necessary, a small amount of acid can be added to adjust the dissolution to promote dissolution, or monovalent cationic compounds such as cesium acetate / cesium oleate can be used instead) to obtain an aqueous solution; place the aqueous solution and the oil phase reaction precursor obtained in step (2) in the same container to obtain a two-phase system.

[0049] (4) Add ligands to the two-phase system: 0.4 mL of oleic acid + 0.6 mL of oleylamine, and add 0.1 mL of HBr. Stir slowly at room temperature for 15–25 min; take the oil phase to obtain colloidal CsPbBr3 nanowire solution.

[0050] Characterization results: The obtained colloidal solution exhibited bright blue photoluminescence (450–480 nm); the nanowire width was 2.5–5 nm. Figure 3 ), with good dispersion.

[0051] Example 5: Preparation of Mn-doped CsPbCl3 nanocrystals by two-phase extraction method (orange light, doping example) (1) Add 0.250 g (0.9 mmol) of PbCl2, 0.020 g (0.1 mmol) of MnCl2·4H2O, 2.0 mL of oleic acid and 2.0 g of TOPO to a three-necked flask, heat to 160 °C and keep warm for 30 min to obtain a clear homogeneous coordination compound.

[0052] (2) Add 10 mL of xylene to the solution obtained in step (1) and stir or sonicate at 90 °C until clear to obtain the oil phase reaction precursor.

[0053] (3) Dissolve 0.168 g (1.0 mmol) of CsCl in 6 mL of deionized water to obtain an aqueous solution; place the aqueous solution and the oil phase reaction precursor obtained in step (2) in the same container to obtain two phase volumes.

[0054] (4) Add an inducing agent / ligand to the two-phase system: 30 mg of citric acid (or citrate) + 0.5 mL of oleylamine, stir slowly for 20 min; separate the oil phase to obtain a Mn-doped CsPbCl3 nanocrystal colloidal solution.

[0055] Characterization results: The colloid emits orange light under ultraviolet excitation; the nanocrystal size is generally 5–15 nm and is concentrated; the emission peak introduced by doping can form a composite emission feature with the matrix emission.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing inorganic perovskite nanocrystals synthesized by a two-phase extraction method, characterized in that, Includes the following steps: (1) The halide BX2 was mixed with a coordinating agent and treated to obtain a clear homogeneous coordination compound; (2) The homogeneous coordination compound obtained in step (1) is mixed with a weakly polar or non-polar organic solvent and treated to obtain an oil-phase reaction precursor; (3) Dissolve compound AX in water or a polar solvent to obtain an aqueous solution, and mix it with the oil phase reaction precursor obtained in step (2) to form a two-phase layered system; (4) Add ligands to the two-phase layered system obtained in step (3), and after the reaction, separate the oil phase to obtain a colloidal perovskite nanocrystal solution. In the compound AX mentioned in step (3), A is selected from one of cesium, rubidium, silver, and bismuth; X is selected from one or any combination of two of carbonic acid, acetic acid, oleic acid, chlorine, bromine, and iodine.

2. The production method according to claim 1, characterized by, In step (1), B in halide BX2 is selected from lead, tin, and manganese. And / or, X is selected from one or any combination of two of chlorine, bromine, and iodine; And / or, the ligand in step (1) is selected from one or more of oleic acid, trioctylphosphine, and trioctylphosphine.

3. The production method according to claim 1, characterized by, The weakly polar or non-polar organic solvent mentioned in step (2) is selected from one or more of n-hexane, cyclohexane, heptane, octane, toluene, butyrolactone, caprolactone, and xylene.

4. The method of claim 1, wherein, The compound AX is specifically selected from one or more of cesium carbonate, rubidium carbonate, cesium acetate, rubidium acetate, cesium oleate, cesium bromide, and rubidium bromide.

5. The preparation method according to claim 1, characterized in that, The ligands in step (4) are selected from one or more of the following: oleic acid, oleylamine, 2-acryloylamino-2-methylpropanesulfonic acid, citric acid or its salts, benzenesulfonamide, polyethylene glycol with carboxyl or amino end groups, dimethylaminoethyl acrylate, polyvinylpyrrolidone, stearic acid, octadecylamine, 1-butyl-1-methylpiperidine tetrafluoroborate, trioctylphosphine, trioctylphosphine, and lecithin.

6. The production method according to any one of claims 1 to 5, characterized by, Step (1) The mixing process is carried out by heating. Preferably, the heating conditions include: heating temperature of 80-170℃ and heating time of 20-60min. And / or, step (2) mixing II treatment is performed by ultrasonic or stirring; And / or, step (3) mixing III treatment is carried out by heating. Preferably, the heating conditions include: heating temperature of 60~110℃; heating time of 30~80min.

7. The production method according to any one of claims 1 to 5, characterized by, Step (4) The reaction is carried out by stirring, the reaction time is 10~30 min, and the reaction temperature is room temperature.

8. An inorganic perovskite nanocrystal, characterized in that, It is prepared by any one of claims 1 to 7.

9. The inorganic perovskite nanocrystal of claim 8, wherein, The synthesized inorganic perovskite nanocrystals have one of the following morphologies: cubic, cuboid, one-dimensional nanowire, two-dimensional nanosheet, or sphere. And / or, the inorganic perovskite nanocrystals have a particle size or edge length of 3 nm to 100 nm and are monodisperse.

10. The application of the inorganic perovskite nanocrystals according to claim 8 or 9 in the fields of light-emitting diodes, lasers, photodetectors or solar cells.

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