Preparation method and application of perovskite quantum dots with extremely narrow emission

Abstract

The invention belongs to the technical field of perovskite quantum dot synthesis, and particularly relates to a preparation method and application of a perovskite quantum dot with extremely narrow emission. The preparation method comprises the following steps: firstly, mixing a monovalent cation compound, halide BX2, a ligand, a weakly polar or non-polar organic solvent and a neutral or alkaline aqueous solution, and reacting at room temperature to obtain an inorganic perovskite quantum dot colloidal solution; standing, adding corresponding monovalent cation halide, and uniformly mixing to obtain a colloidal solution of the inorganic perovskite quantum dots with the core-shell structure; and centrifuging, removing the clear liquid, and drying to obtain the all-inorganic perovskite quantum dot powder with the core-shell structure. According to the preparation method, extremely narrow emission (half width of 8nm-10nm) of the inorganic perovskite quantum dots is realized, the quantum efficiency is high, the preparation method is simple, the cost is low, and the preparation method not only has important significance for realizing ultra-high-definition display and other high-quality luminescent devices, but also is an important material basis for constructing a single-photon light source.

Description

Technical Field

[0001] The present application belongs to the technical field of perovskite quantum dot synthesis, and specifically relates to a preparation method and application of extremely narrow emission perovskite quantum dots. Background Art

[0002] All-inorganic perovskite CsPbX 3 (X=Cl, I, Br and mixed Cl / Br and Br / I) quantum dots have simple preparation process, low cost and can be processed by solution, breaking through the limitations of traditional quantum dots. At the same time, they have the following advantages that are particularly suitable for luminescent materials: 1. High quantum efficiency, no need for any treatment, quantum efficiency can reach more than 90%; 2. The luminescent wavelength can be easily and effectively controlled by changing the halogen composition; 3. Wide excitation spectrum and narrow fluorescence emission spectrum; 4. Good photothermal stability. In the range of 20-100℃, the lattice expansion effect and the interaction between electrons and phonons are exactly offset, and the luminescence peak position is almost unchanged. For this reason, CsPbX 3 Quantum dots have become the light emitter of choice for the latest generation of commercial LCD color displays and are actively used in light-emitting diodes, lasers, and luminescent solar concentrators.

[0003] The color purity (half-peak width) of the luminescent material is an important indicator that determines the color gamut of LCD high-definition display technology and is a key factor in entering and conquering market opportunities. At present, the half-width of perovskite quantum dots is generally 25nm-45nm. Although it has been greatly improved, it still cannot fully meet the requirements of ultra-high-definition display, thus limiting the application of inorganic perovskite quantum dots. Summary of the invention

[0004] In response to the problems existing in the application of the above-mentioned inorganic perovskite quantum dots, the present invention realizes extremely narrow emission (half-width 8nm-10nm) of inorganic perovskite quantum dots through core-shell, with high quantum efficiency, simple preparation method and low cost. It is not only of great significance for the realization of ultra-high-definition display and other high-quality light-emitting devices, but also an important material basis for constructing single-photon light sources.

[0005] The technical solution of this application is as follows:

[0006] A method for preparing extremely narrow emission perovskite quantum dots comprises the following steps:

[0007] (1) Monovalent cationic compounds, halides BX 2 , a ligand, a weakly polar or non-polar organic solvent, and a neutral or alkaline aqueous solution are mixed and reacted at room temperature to obtain an inorganic perovskite quantum dot colloidal solution;

[0008] (2) allowing the inorganic perovskite quantum dot colloidal solution of step (1) to stand, adding the monovalent cation halide corresponding to step (1) and mixing evenly, thereby obtaining a colloidal solution of inorganic perovskite quantum dots with a core-shell structure;

[0009] (3) Centrifuging the colloidal solution obtained in step (2), discarding the clear liquid, and drying to obtain an all-inorganic perovskite quantum dot powder with a core-shell structure.

[0010] Preferably, the monovalent cationic compound in step (1) is one or more of cesium carbonate, rubidium carbonate, cesium acetate, rubidium acetate, cesium oleate, cesium bromide, and rubidium bromide.

[0011] Preferably, the halide BX in step (1) 2 , B is one of lead, tin or manganese, and X is one of chlorine, bromine, iodine or a combination of any two.

[0012] Preferably, the ligand described in step (1) is a mixture of one or more of oleic acid, oleylamine, phosphatidylcholine, tri-n-octylphosphine oxide, triisooctyl phosphate, 2-acrylamido-2-methylpropanesulfonic acid, citric acid or citrate, polyethylene glycol with a carboxyl or amino terminal group, dimethylaminoethyl acrylate, polyvinylpyrrolidone, octadecanoic acid, octadecylamine, and 1-butyl-1-methylpiperidinium tetrafluoroborate.

[0013] Preferably, the weakly polar or non-polar organic solvent in step (1) is one of ethyl acetate, 1,4-dioxane, methyl formate, methyl acetate, and tetrahydrofuran, and the monovalent cationic compound and the halide BX 2 Only a small amount or no dissolution in it.

[0014] Preferably, the molar ratio of the monovalent cation to the lead halide in step (1) is 0.5 to 1;

[0015] And / or, the reaction temperature in step (1) is 25°C to 90°C;

[0016] And / or, the alkaline aqueous solution in step (1) is one of sodium hydroxide, sodium bicarbonate, ammonium bromide, calcium bromide, tetramethylguanidine, lysine or dimethylbiguanide aqueous solution;

[0017] And / or, the volume ratio of the neutral or alkaline aqueous solution to the non-polar organic solvent is 2% to 5%.

[0018] Preferably, step (2) further comprises, after standing, taking the upper layer solution and mixing it with the weakly polar or non-polar organic solvent of step (1), and then adding the monovalent cationic compound;

[0019] And / or, the supernatant is discarded in step (2) after the reaction in step (1) has been carried out for 15 minutes, at which time the reaction solution has bright green or cyan fluorescence under ultraviolet light;

[0020] and / or, in step (2), the molar ratio of the added monovalent cation halide to the inorganic perovskite quantum dots in the supernatant is 0.1 to 0.5;

[0021] And / or, in step (2), after the monovalent cationic halide is added, the width of the fluorescence emission peak gradually decreases as the reaction proceeds. The reaction temperature is 25°C to 90°C.

[0022] Another object of the present invention is to protect the perovskite quantum dots prepared by the above preparation method.

[0023] Furthermore, the perovskite quantum dots are of core-shell structure, and the half width of the extremely narrow emission is 8nm-10nm.

[0024] Another object of the present invention is to protect the application of the above-mentioned perovskite quantum dots in circularly polarized coherent light sources or in quantum dot films.

[0025] Beneficial Effects of the Invention

[0026] (1) The preparation method of the inorganic perovskite quantum dots with core-shell in the present invention is simple, the reaction process is controllable and the cost is low. After separation, purification and drying, a large batch of powder samples can be obtained with high yield and easy storage and transportation;

[0027] (2) The inorganic perovskite quantum dots with core-shell prepared by the present invention have a quantum efficiency greater than 90% and an extremely narrow emission (half width 8nm-10nm), which is of great significance for realizing ultra-high-definition display, single-photon source, high-brightness LED, low-threshold laser, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The CsPbBr with core-shell structure prepared in Example 1 3 TEM image of quantum dots.

[0029] Figure 2 CsPbBr prepared in Example 1 3 Nanocubes and CsPbBr with core-shell structure 3 PL diagram of quantum dots.

[0030] Figure 3 The CsPbBr with core-shell structure obtained in Example 7 3 PL diagram of quantum dots. DETAILED DESCRIPTION

[0031] Example 1

[0032] A method for preparing extremely narrow emission perovskite quantum dots comprises the following steps:

[0033] (1) In reaction flask A, 0.0525 g CsBr and 0.13 g PbBr were added. 2 , 260 μL oleic acid, 260 μL oleylamine, 5 ml 1,4-dioxane, and 75 μL NaOH aqueous solution (concentration 0.1 mol / L) were mixed and stirred continuously at room temperature for 1 h to obtain CsPbBr 3 Colloidal solution of nanocubes;

[0034] (2) Add 1 ml of 1,4-dioxane to reaction bottle B, and set the reaction temperature to 35°C;

[0035] (3) After the reaction bottle A was left to stand for 5 min, 2 ml of the solution in the reaction bottle A and 0.017 g of CsBr were added to the reaction bottle B and stirred for 45 min.

[0036] (4) The reaction solution in the reaction bottle was centrifuged at 10000 r / min for 8 min, the clear solution was discarded, and then dried in a vacuum oven at 50°C for 7 hours to obtain the core-shell structured CsPbBr 3 Quantum dot powder.

[0037] Example 2

[0038] A method for preparing extremely narrow emission perovskite quantum dots comprises the following steps:

[0039] (1) In reaction flask A, 0.0525 g CsBr and 0.13 g PbBr were added. 2 , 260 μL oleic acid, 260 μL oleylamine, 5 ml 1,4-dioxane, and 100 μL aqueous solution were mixed and stirred continuously at room temperature for 1 h to obtain CsPbBr 3 Colloidal solution of nanocubes;

[0040] (2) After the reaction bottle A was left to stand for 5 min, 2 ml of the solution in the reaction bottle A and 0.02 g of CsBr were added to the reaction bottle B and stirred for 45 min.

[0041] (3) The reaction solution in the reaction bottle was centrifuged at 10000 r / min for 8 min, the clear solution was discarded, and then dried in a vacuum oven at 50°C for 7 hours to obtain the core-shell structured CsPbBr 3 Quantum dot powder.

[0042] Example 3

[0043] A method for preparing extremely narrow emission perovskite quantum dots comprises the following steps:

[0044] (1) In reaction flask A, add 0.0525 g CsCl and 0.12 g PbCl 2 , 260 μL oleic acid, 260 μL oleylamine, 5 ml 1,4-dioxane, and 75 μL NaOH aqueous solution (concentration 0.1 mol / L) were mixed and stirred continuously at room temperature for 1 h to obtain CsPbCl 3 Colloidal solution of nanocubes;

[0045] (2) After the reaction bottle A was left to stand for 5 min, 2 ml of the solution in the reaction bottle A and 0.018 g of CsCl were added to the reaction bottle B and stirred for 45 min.

[0046] (3) The reaction solution in the reaction bottle was centrifuged at 10000 r / min for 8 min, the clear solution was discarded, and then dried in a vacuum oven at 50°C for 7 hours to obtain the core-shell structured CsPbCl 3 Quantum dot powder.

[0047] Example 4

[0048] A method for preparing extremely narrow emission perovskite quantum dots comprises the following steps:

[0049] (1) In reaction flask A, add 0.0525 g CsCl and 0.12 g PbCl 2 , 0.23g AMPS, 260μL oleylamine, 5ml 1,4-dioxane, and 150ul aqueous solution were mixed and stirred continuously for 1h at room temperature to obtain CsPbCl 3 Colloidal solution of nanocubes;

[0050] (2) After the reaction bottle A was left to stand for 5 min, 2 ml of the solution in the reaction bottle A and 0.018 g of CsCl were added to the reaction bottle B and stirred for 45 min.

[0051] (3) The reaction solution in the reaction bottle was centrifuged at 10000 r / min for 8 min, the clear solution was discarded, and then dried in a vacuum oven at 50°C for 7 hours to obtain the core-shell structured CsPbCl 3 Quantum dot powder.

[0052] Example 5

[0053] A method for preparing extremely narrow emission perovskite quantum dots comprises the following steps:

[0054] (1) In reaction flask A, 0.0525 g CsBr and 0.13 g PbBr were added. 2 , 0.43g TOPO, 5ml 1,4-dioxane, and 100μL aqueous solution were mixed and stirred continuously for 1h at room temperature to obtain CsPbBr 3Colloidal solution of nanocubes;

[0055] (2) After the reaction bottle A was left to stand for 5 min, 2 ml of the solution in the reaction bottle A and 0.02 g of CsBr were added to the reaction bottle B and stirred for 45 min.

[0056] (3) The reaction solution in the reaction bottle was centrifuged at 10000 r / min for 8 min, the clear solution was discarded, and then dried in a vacuum oven at 50°C for 7 hours to obtain the core-shell structured CsPbBr 3 Quantum dot powder.

[0057] Example 6

[0058] A method for preparing extremely narrow emission perovskite quantum dots comprises the following steps:

[0059] (1) In reaction flask A, 0.0525 g CsBr and 0.13 g PbBr were added. 2 , 260 μL oleic acid, 260 μL oleylamine, 4 ml tetrahydrofuran, 1 ml methyl acetate, and 150 μL aqueous solution were mixed and stirred continuously at room temperature for 1 h to obtain CsPbCl 3 Colloidal solution of nanocubes;

[0060] (2) After the reaction bottle A was left to stand for 5 min, 2 ml of the solution in the reaction bottle A and 0.018 g of CsBr were added to the reaction bottle B and stirred for 45 min.

[0061] (3) The reaction solution in the reaction bottle was centrifuged at 10000 r / min for 8 min, the clear solution was discarded, and then dried in a vacuum oven at 50°C for 7 hours to obtain the core-shell structured CsPbBr 3 Quantum dot powder.

[0062] Example 7

[0063] A method for preparing extremely narrow emission perovskite quantum dots comprises the following steps:

[0064] (1) In reaction flask A, 0.0525 g CsBr and 0.11 g PbBr were added. 2 , 260 μL oleic acid, 260 μL oleylamine, 5 ml 1,4-dioxane, and 75 μL NaOH aqueous solution (concentration 0.1 mol / L) were mixed and stirred continuously at room temperature for 1 h to obtain CsPbBr 3 Colloidal solution of nanocubes;

[0065] (2) Add 4 ml of 1,4-dioxane to reaction bottle B, and the reaction temperature is 35°C;

[0066] (3) Let reaction bottle A stand for 5 min, take 2 ml of the solution in reaction bottle A and 0.017 g of CsBr and add them to reaction bottle B, continue stirring for 45 min, heat to 45 °C and continue stirring for 45 min;

[0067] (4) The reaction solution in the reaction bottle was centrifuged at 10000 r / min for 8 min, the clear solution was discarded, and then dried in a vacuum oven at 50°C for 7 hours to obtain the core-shell structured CsPbBr 3 Quantum dot powder.

[0068] Implementation effect example

[0069] 1. CsPbBr with core-shell structure of Example 1 3 Application of quantum dots in quantum dot films

[0070] Preparation method: 0.01g core-shell structure CsPbBr 3 Quantum dot powder and PMMA (molar ratio 1:800) are dissolved in 10 ml of toluene, and the mixed solution is spin-coated or drop-coated on a glass substrate, and dried to obtain a quantum dot film with bright emission.

[0071] Detection method: Observe the morphology of quantum dot film under atomic force microscope and measure its quantum efficiency;

[0072] Results: The surface of the quantum dot film is flat and the quantum efficiency is greater than 90%.

[0073] 2. CsPbBr with core-shell structure in Example 2 3 Application of quantum dots on circularly polarized coherent light sources Preparation method: First, a cholesteric liquid crystal polymer film was prepared on a glass substrate by doctor blade coating, and then a 5wt% PVA solution dissolved in deionized water was spin-coated on the surface of the cholesteric liquid crystal film at a speed of 2000rpm for 30s, and the deposited film was placed on a hot plate at 60℃ for 30 minutes to form a PVA spacer layer. The perovskite quantum dot dispersion was then dripped onto the PVA layer to form a perovskite quantum dot film, followed by another spacer. The PMMA layer was obtained by spin coating a 5wt% PMMA solution dissolved in PEGMA at 2000rpm for 40s and drying it on a hot plate at 60℃ for 1h. Finally, another cholesteric liquid crystal polymer film was doctored on top of the PMMA layer and then UV polymerized. The thickness of the CLC film was controlled by the gap between the coating rod and the substrate. The thickness was measured by cross-sectional SEM of the CLC film, and the top CLC film was about 500nm and the bottom CLC film was 1.5μm.

[0074] Detection method: 800nm ​​femtosecond laser pumping the above devices

[0075] Results: Right-handed amplified spontaneous emission with an asymmetry factor of up to 1.4 was detected.

Claims

1. A method for preparing extremely narrow emission perovskite quantum dots, characterized in that: The following steps are involved: (1) mixing a monovalent cationic compound, a halide BX2, a ligand, a weakly polar or non-polar organic solvent, and a neutral or alkaline aqueous solution, and reacting them at room temperature to obtain an inorganic perovskite quantum dot colloidal solution; (2) allowing the inorganic perovskite quantum dot colloidal solution of step (1) to stand, adding the monovalent cation halide corresponding to step (1) and mixing evenly, thereby obtaining a colloidal solution of inorganic perovskite quantum dots with a core-shell structure; (3) Centrifuging the colloidal solution obtained in step (2), discarding the clear liquid, and drying to obtain an all-inorganic perovskite quantum dot powder with a core-shell structure.

2. The method for preparing extremely narrow emission perovskite quantum dots according to claim 1, characterized in that: The monovalent cationic compound described in step (1) is one or more of cesium carbonate, rubidium carbonate, cesium acetate, rubidium acetate, cesium oleate, cesium bromide, and rubidium bromide.

3. The method for preparing extremely narrow emission perovskite quantum dots according to claim 1, characterized in that: In the halide BX2 described in step (1), B is one of lead, tin or manganese, and X is one of chlorine, bromine, iodine or a combination of any two thereof.

4. The method for preparing extremely narrow emission perovskite quantum dots according to claim 1, characterized in that: The ligand described in step (1) is a mixture of one or more of oleic acid, oleylamine, phosphatidylcholine, tri-n-octylphosphine oxide, triisooctyl phosphate, 2-acrylamido-2-methylpropanesulfonic acid, citric acid or citrate, polyethylene glycol with a carboxyl or amino terminal group, dimethylaminoethyl acrylate, polyvinylpyrrolidone, octadecanoic acid, octadecylamine, and 1-butyl-1-methylpiperidinium tetrafluoroborate.

5. The method for preparing extremely narrow emission perovskite quantum dots according to claim 1, characterized in that: The weakly polar or non-polar organic solvent described in step (1) is one of ethyl acetate, 1,4-dioxane, methyl formate, methyl acetate, and tetrahydrofuran, and the monovalent cationic compound and the halide BX2 are only slightly soluble or insoluble therein.

6. The method for preparing the extremely narrow emission perovskite quantum dots according to any one of claims 1 to 5, characterized in that: The molar ratio of the monovalent cation to the lead halide in step (1) is 0.5 to 1; And / or, the reaction temperature in step (1) is 25°C to 90°C; And / or, the alkaline aqueous solution in step (1) is one of sodium hydroxide, sodium bicarbonate, ammonium bromide, calcium bromide, tetramethylguanidine, lysine or dimethylbiguanide aqueous solution; And / or, the volume ratio of the neutral or alkaline aqueous solution to the non-polar organic solvent is 2% to 5%.

7. The method for preparing ultra-narrow emission perovskite quantum dots according to claim 1, characterized in that: Step (2) further comprises, after standing, taking the upper layer solution and mixing it with the weakly polar or non-polar organic solvent of step (1), and then adding a monovalent cationic compound; And / or, the supernatant is discarded in step (2) after the reaction in step (1) has been carried out for 15 minutes, at which time the reaction solution has bright green or cyan fluorescence under ultraviolet light; and / or, in step (2), the molar ratio of the added monovalent cation halide to the inorganic perovskite quantum dots in the supernatant is 0.1 to 0.5; And / or, in step (2), after the monovalent cationic halide is added, the width of the fluorescence emission peak gradually decreases as the reaction proceeds. The reaction temperature is 25°C to 90°C.

8. Perovskite quantum dots prepared by the preparation method according to any one of claims 1 to 7.

9. The perovskite quantum dot according to claim 8, characterized in that: The perovskite quantum dots are of core-shell structure, and the half width of the extremely narrow emission is 8nm-10nm.

10. Use of the perovskite quantum dots according to claim 8 on a circularly polarized coherent light source or on a quantum dot film.

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