Preparation method and application of perovskite composite luminescent material

Abstract

The invention discloses a preparation method of a perovskite composite luminescent material and an LED display application of the perovskite composite luminescent material. The luminescent material is a composite luminescent material with a heterostructure formed by embedding CsPbBr3 nanocrystals in a metal halide Cs2ZnBr4, the composite luminescent material is uniform in particle size, high in luminous efficiency and narrow in half-peak width of an emission peak; the stability is superior to that of the solid CsPbBr3 nanocrystal; the method can be used for LED display.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid-state luminescent materials, and in particular relates to a preparation method of a perovskite composite luminescent material and an LED application thereof. Background Art

[0002] Luminescent materials are the basis of display technology, so the synthesis of narrow-band emission, small particle size and high-efficiency luminescent materials is of great significance for LED backlight display. Usually, LED backlight display is composed of InGaN blue light emitting chip (λ = 450nm), narrow-band green light emitting β-SiAlON:Eu 2+ and red-emitting K2SiF6:Mn 4+ However, since the human eye is more sensitive to green light, it is very important to prepare a narrow-band, small-particle green luminescent material. Currently, among the mainstream green luminescent materials for LED backlight display, the green luminescent material β-SiAlON:Eu 2+ and perovskite quantum dots CsPbBr3 are considered the best choice. 2+ It has excellent luminescence performance, but it has disadvantages such as wide half-width of emission band and harsh preparation conditions, which greatly limits its application. Although the perovskite quantum dots CsPbBr3, which have been widely studied in recent years, have narrow-band emission characteristics, they still have the problem of poor stability. In addition, most quantum dots are difficult to achieve large-scale synthesis through batch preparation methods due to the influence of preparation conditions. Therefore, it is very necessary to find narrow-band green luminescent materials with high luminescence efficiency, good stability and easy batch preparation. Summary of the invention

[0003] In view of the problems of the prior art, the present invention provides a method for preparing a perovskite composite luminescent material and its LED application, and prepares a heterostructure CsPbBr3 / Cs2ZnBr4 composite luminescent material composed of CsPbBr3 nanocrystals and metal halide Cs2ZnBr4. The prepared perovskite composite luminescent material has a uniform particle size distribution, which is in the micron level, and has high luminescence intensity and a narrow half-peak width of the emission spectrum, which meets the requirements of LED display for the performance of luminescent materials; in addition, its luminescence intensity and stability are better than those of CsPbBr3 nanocrystals.

[0004] To achieve the above objectives, the first aspect of the present invention provides a perovskite composite light-emitting material. The perovskite composite light-emitting material of the present invention is a heterostructure CsPbBr3 / Cs2ZnBr4, which is characterized in that CsPbBr3 nanocrystals are embedded in the metal halide Cs2ZnBr4.

[0005] The second aspect of the present invention provides a method for preparing the perovskite composite light-emitting material CsPbBr3 / Cs2ZnBr4 as described in the first aspect, which comprises the following steps:

[0006] Step (1): mixing a Cs precursor and a Pb precursor with an organic ligand and a solvent respectively, and heating and stirring to obtain a Cs precursor solution and a Pb precursor solution;

[0007] Preferably, the precursor of Cs is CsBr, Cs2CO3, CsCH3COO·2H2O, and the precursor of Pb is PbBr2, PbCO3, Pb(CH3COO)2;

[0008] Preferably, the organic ligand is oleic acid, oleylamine, or dodecylbenzenesulfonic acid;

[0009] Preferably, the solvent is octadecene;

[0010] Preferably, the heating temperature range is 100-190°C;

[0011] Preferably, the stirring speed range is 400-600 rpm / min;

[0012] Step (2): adding the precursor solution of Cs obtained in step (1) to the precursor solution of Pb obtained in step (1), heating and stirring, ice-water bath, centrifugal purification (adding a sedimentation agent), to obtain a CsPbBr3 nanocrystalline colloidal solution;

[0013] Preferably, the heating temperature range is 150-190°C;

[0014] Preferably, the stirring speed range is 400-600 rpm / min;

[0015] Preferably, the centrifugal speed range during the centrifugal purification process is 8000-12000 rpm / min, and the centrifugal time range is 3-10 min;

[0016] Preferably, the sedimentation agent in the centrifugal purification process is one or more of ethyl acetate, methyl acetate, and acetone;

[0017] Step (3): mixing a Cs precursor and a Zn precursor with a hydrobromic acid solvent, adding hypophosphorous acid, heating and stirring, then cooling to obtain white crystals, washing with an organic solvent, and drying to obtain a metal halide Cs2ZnBr4;

[0018] Preferably, the heating temperature range is 100-150°C;

[0019] Preferably, the stirring speed range is 420-600 rpm / min;

[0020] Preferably, the cooling may be natural cooling or ice water bath cooling;

[0021] Preferably, the organic solvent is one or more of ethanol, methanol, and isopropanol;

[0022] Preferably, the drying is vacuum drying, the temperature range is 40-60°C, and the drying time is 3-10h;

[0023] Step (4): adding the CsPbBr3 reaction solution obtained in step (2) to the metal halide Cs2ZnBr4 obtained in step (4), ultrasonicating, washing and drying to obtain a heterostructure perovskite composite light-emitting material CsPbBr3 / Cs2ZnBr4;

[0024] Preferably, the ratio between CsPbBr3 and Cs2ZnBr4 is in the range of 1:1-1:10;

[0025] Preferably, the ultrasound time interval is 30-480 min;

[0026] Preferably, the drying is vacuum drying, the temperature range is 30-45°C, and the drying time is 6-10h;

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1. The preparation method of the perovskite composite luminescent material of the present invention is simple and easy to prepare in batches;

[0029] 2. The perovskite composite luminescent material of the present invention has the advantages of high luminescence intensity, narrow half-peak width of emission spectrum, short fluorescence lifetime, uniform particle size distribution, etc., and can be used for LED display;

[0030] 3. The luminous intensity and stability of the perovskite composite luminescent material described in the present invention are superior to those of solid CsPbBr3 nanocrystals, and it has broad application prospects in LED displays. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The XRD diffraction pattern and emission spectrum of the product obtained in Example 1;

[0032] Figure 2 is a SEM image of the product obtained in Example 1;

[0033] Figure 3 are the excitation and emission spectra of the product obtained in Example 1;

[0034] Figure 4 is a fluorescence microscope photograph of the product obtained in Example 2;

[0035] Figure 5 This is a data diagram of the performance (color coordinate diagram, emission spectrum and actual LED device) of the color conversion LED device packaged by the product obtained in Example 2; DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described below by specific implementation methods. The embodiments are only used to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0037] Example 1

[0038] A method for preparing perovskite composite luminescent material

[0039] (1) Weigh 0.407 g of cesium carbonate (CsCO3) and 0.367 g of lead bromide (PbBr2), add them into a 50 mL three-necked flask, and add 20 mL and 10 mL of octadecene respectively; heat (5°C / min), stir (speed 520 rpm / min), and evacuate. When the temperature rises to 120°C, replace the reaction system with an inert atmosphere; add 1.25 mL of oleylamine to the Cs precursor, and add 1 mL of oleic acid (OA) and 1 mL of oleylamine (OAm) to the Pb precursor; continue to heat to 150°C until the precursors are completely dissolved to obtain cesium oleate and lead oleate precursor solutions.

[0040] (2) 1.82 mL of cesium oleate precursor solution was extracted and injected into the lead oleate reaction solution at 150°C. After reacting for 5 seconds, the reaction was stopped by ice-water bath. Centrifugal purification was performed, wherein the solvent for dispersing CsPbBr3 was n-hexane and the precipitant was ethyl acetate. N-hexane was used again to disperse CsPbBr3 to obtain colloidal nanocrystals of CsPbBr3. The XRD diffraction pattern of the obtained sample was tested, as shown in FIG. Figure 1 As shown; the excitation and emission spectra of the tested samples are as follows Figure 3 shown.

[0041] (3) Weigh 0.225 g of zinc bromide (ZnBr2) and 0.425 g of cesium bromide (CsBr), add them to a 50 mL beaker, add 5 mL of hydrobromic acid (HBr) and 1 mL of hypophosphorous acid (H3PO2), heat to 120 °C, and keep warm for 1 h; then, cool naturally, wash with isopropanol 2-3 times, and vacuum dry.

[0042] (4) Weigh 0.651 g of Cs2ZnBr4, add 50 μL of colloidal CsPbBr3 and 2 mL of n-hexane, sonicate for 3 h, wash with isopropanol 2-3 times, and vacuum dry to obtain a heterostructured CsPbBr3 / Cs2ZnBr4 composite luminescent material.

[0043] Example 2

[0044] A method for preparing perovskite composite luminescent material

[0045] (1) Weigh 0.407 g of cesium carbonate (CsCO3) and 0.367 g of lead bromide (PbBr2), add them into a 50 mL three-necked flask, and add 20 mL and 10 mL of octadecene respectively; heat (5°C / min), stir (speed 520 rpm / min), and evacuate. When the temperature rises to 120°C, replace the reaction system with an inert atmosphere; add 1.25 mL of oleylamine to the Cs precursor, and add 1 mL of oleic acid (OA) and 1 mL of oleylamine (OAm) to the Pb precursor; continue to heat to 150°C until the precursors are completely dissolved to obtain cesium oleate and lead oleate precursor solutions.

[0046] (2) 1.82 mL of cesium oleate precursor solution was extracted and injected into the lead oleate reaction solution at 150°C. After reacting for 5 seconds, the reaction was stopped by ice-water bath. Centrifugal purification was performed, wherein the solvent for dispersing CsPbBr3 was n-hexane and the precipitant was ethyl acetate. N-hexane was used again to disperse CsPbBr3 to obtain colloidal nanocrystals of CsPbBr3. The XRD diffraction pattern of the obtained sample was tested, as shown in FIG. Figure 1 As shown; the excitation and emission spectra of the tested samples are as follows Figure 3 shown.

[0047] (3) Weigh 0.225 g of zinc bromide (ZnBr2) and 0.425 g of cesium bromide (CsBr), add them to a 50 mL beaker, add 5 mL of hydrobromic acid (HBr) and 1 mL of hypophosphorous acid (H3PO2), heat to 120 °C, and keep warm for 1 h; then, cool naturally, wash with isopropanol 2-3 times, and vacuum dry.

[0048] (4) Weigh 0.651 g of Cs2ZnBr4, add 200 μL of colloidal CsPbBr3 and 2 mL of n-hexane, sonicate for 3 h, wash with isopropanol 2-3 times, and vacuum dry to obtain a heterostructured CsPbBr3 / Cs2ZnBr4 composite luminescent material. Test the fluorescence microscopy of the obtained sample. Figure 4 shown.

[0049] Example 3

[0050] A method for preparing perovskite composite luminescent material

[0051] (1) Weigh 0.407 g of cesium carbonate (CsCO3) and 0.367 g of lead bromide (PbBr2), add them into a 50 mL three-necked flask, and add 20 mL and 10 mL of octadecene respectively; heat (5°C / min), stir (speed 520 rpm / min), and evacuate. When the temperature rises to 120°C, replace the reaction system with an inert atmosphere; add 1.25 mL of oleylamine to the Cs precursor, and add 1 mL of oleic acid (OA) and 1 mL of oleylamine (OAm) to the Pb precursor; continue to heat to 150°C until the precursors are completely dissolved to obtain cesium oleate and lead oleate precursor solutions.

[0052] (2) 1.82 mL of cesium oleate precursor solution was extracted and injected into the lead oleate reaction solution at 150°C. After reacting for 5 seconds, the reaction was stopped by ice-water bath. Centrifugal purification was performed, wherein the solvent for dispersing CsPbBr3 was n-hexane and the precipitant was ethyl acetate. N-hexane was used again to disperse CsPbBr3 to obtain colloidal nanocrystals of CsPbBr3. The XRD diffraction pattern of the obtained sample was tested, as shown in FIG. Figure 1 As shown; the excitation and emission spectra of the tested samples are as follows Figure 3 shown.

[0053] (3) Weigh 0.225 g of zinc bromide (ZnBr2) and 0.425 g of cesium bromide (CsBr), add them to a 50 mL beaker, add 5 mL of hydrobromic acid (HBr) and 1 mL of hypophosphorous acid (H3PO2), heat to 120 °C, and keep warm for 1 h; then, cool naturally, wash with isopropanol 2-3 times, and vacuum dry.

[0054] (4) Weigh 0.651 g of Cs2ZnBr4, add 500 μL of colloidal CsPbBr3 and 2 mL of n-hexane, sonicate for 3 h, wash with isopropanol 2-3 times, and vacuum dry to obtain a heterostructured CsPbBr3 / Cs2ZnBr4 composite luminescent material.

[0055] Matters not covered by the present invention are known technologies.

[0056] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a perovskite composite luminescent material, characterized in that The perovskite composite light-emitting material is a heterostructure material formed by CsPbBr3 nanocrystals and metal halide Cs2ZnBr4, and the CsPbBr3 nanocrystals are embedded in the metal halide Cs2ZnBr4.

2. The perovskite composite light-emitting material according to claim 1, characterized in that: The excitation light wavelength range of the perovskite composite luminescent material is 250-510nm, the emission light wavelength range of the perovskite composite luminescent material is 500-540nm, the emission spectrum half-width range of the perovskite composite luminescent material is 18-30nm, and the particle size of the perovskite composite luminescent material is 1-100μm.

3. The method for preparing the perovskite composite luminescent material according to claim 1, characterized in that: The preparation method comprises the following steps: Step (1): mixing a cesium (Cs) precursor and a lead (Pb) precursor with an organic ligand and a solvent respectively, and heating and stirring to obtain a Cs precursor solution and a Pb precursor solution; Step (2): adding the Cs precursor solution obtained in step (1) to the Pb precursor solution obtained in step (1), heating and stirring, ice-water bathing, centrifugal purification (adding a sedimentation agent), to obtain a CsPbBr3 nanocrystalline colloidal solution; Step (3): mixing a Cs precursor, a zinc (Zn) precursor and a hydrobromic acid solution, adding hypophosphorous acid, heating and stirring, and then cooling to obtain white crystals; then washing with an organic solvent and drying to obtain a metal halide Cs2ZnBr4; Step (4): Add the CsPbBr3 colloidal solution obtained in step (2) to the metal halide Cs2ZnBr4 obtained in step (4), and ultrasonicate, wash, and dry to obtain the heterostructure perovskite light-emitting material CsPbBr3 / Cs2ZnBr4.

4. The preparation method according to claim 3, characterized in that: In step (1), the precursor of Cs is CsBr, Cs2CO3, CsCH3COO·2H2O, and the precursor of Pb is PbBr2, PbCO3, Pb(CH3COO)2; in step (2), the precursor of Cs is CsBr, Cs2CO3, CsCH3COO·2H2O, and the precursor of Zn is ZnBr2, ZnBr2·4H2O; in step (4), the molar ratio between the amount of CsPbBr3 added and the amount of metal halide Cs2ZnBr4 is in the range of 10:1-1:

10.

5. The use of the perovskite composite luminescent material according to claim 1, characterized in that: The perovskite composite light-emitting material can be used in LED devices.

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