A method for preparing blue-light CsPbBr 3 nanowires by cooling and recombination

Abstract

The present invention discloses a method for preparing blue-light CsPbBr3 nanowires by cooling and recombination. A crude solution of CsPbBr3 green-light quantum dots is pre-synthesized by a hot injection method. At room temperature and in an air environment, the crude solution of CsPbBr3 quantum dots is continuously stirred at a temperature of 0 °C to 20 °C to complete the structural recombination from quantum dots to nanowires, and blue-light emission is achieved through dimensional confinement. It is centrifugally purified to obtain a perovskite nanowire solution with bright blue-light emission. The preparation method of the present invention is simple and the conditions are not harsh. CsPbBr3 solutions with different fluorescence spectra can be prepared under different stirring times, realizing a continuous transition from green light to blue light. The CsPbBr3 blue-light nanowires have uniform size, good dispersibility and good crystallinity. Their emission wavelength is 453 nm, the full width at half maximum is 20 nm, the fluorescence quantum yield reaches 81%, and they have excellent stability. When stored in an air environment for one month, their fluorescence intensity basically does not decay.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite nanophosphor preparation, and specifically refers to a method for preparing blue-light CsPbBr 3 nanowires by cooling and recombination. Background Art

[0002] Due to their excellent optoelectronic properties, perovskite materials show great potential in the field of light-emitting displays. Red-light and green-light LED devices based on perovskites have achieved relatively high external quantum efficiencies, and the external quantum efficiency of green-light LED devices even exceeds 30%. However, the external quantum efficiency of blue light, especially pure blue-light LED devices, which are one of the three primary colors (red, green, and blue), is much lower than that of red-light and green-light devices, restricting the development and application of perovskite materials in the display field.

[0003] Currently, there are mainly three methods for preparing perovskite blue-light materials: The first is to achieve blue-light emission through the component regulation of mixed halogens (Br / Cl). This method is easy to operate, but under the action of light, heat, electricity, etc., halogen elements will undergo ion migration, showing obvious spectral shifts. The second is to replace Pb 3+ with cations such as Bi 2+ and Cu 2+ to achieve blue-light emission of lead-free perovskite derivatives. However, the current PLQY of lead-free perovskites is still relatively low. The third is to achieve blue-light emission by preparing small-sized, low-dimensional nanomaterials through the quantum confinement effect. The specific surface area of the nanocrystals obtained by this method is relatively large, which is likely to cause a large density of defect states. In order to passivate the defect states, a large amount of organic ligands are often introduced, and the introduction of a large amount of organic ligands will affect the conductivity of optoelectronic devices. In addition, the nucleation and growth of perovskite nanocrystals occur rapidly within a few seconds, and the size and distribution of quantum-confined nanocrystals are not easy to control.

[0004] Therefore, it has become an urgent problem for people to develop a blue-light perovskite material with simple method, excellent stability and good optoelectronic properties. Summary of the Invention

[0005] To solve the above technical problems, the technical solution provided by the present invention is: A method for preparing blue-light CsPbBr 3 nanowires by cooling and recombination, and the method for preparing blue-light CsPbBr 3 nanowires by cooling and recombination is as follows:

[0006] Step 1: Prepare cesium oleate Cs-OA. The Cs-OA raw materials include cesium stearate, oleic acid, and octadecene. Place the above raw materials in a four-necked flask according to the ratio, and heat and stir in an inert gas environment until dissolved;

[0007] Step 2: Prepare CsPbBr3 Solution, CsPbBr 3 The solution raw materials include lead bromide, octadecene, oleic acid, and organic amine. The above raw materials are placed in a four-necked flask according to the ratio, heated and stirred under an inert gas until dissolved, and Cs-OA is injected at a high temperature to obtain CsPbBr 3 Quantum dot crude solution;

[0008] Step 3: Place the CsPbBr 3 quantum dot crude solution in a water bath environment and continuously stir to obtain CsPbBr 3 nanowire crude solution;

[0009] Step 4: Add the CsPbBr 3 nanowire crude solution to a polar solvent for the first centrifugation operation to obtain a first precipitate;

[0010] Step 5: Dissolve the first precipitate in toluene, and add a polar solvent for the second centrifugation operation to obtain a second precipitate;

[0011] Step 6: Dissolve the second precipitate in an organic solvent to obtain a CsPbBr 3 nanowire solution with good dispersion.

[0012] Furthermore, in Step 1, the molar ratio of the raw materials is cesium stearate: oleic acid: octadecene = 2:5:49.

[0013] Furthermore, in Step 2, the molar ratio of the raw materials is lead bromide: octadecene: oleic acid: organic amine = 1:40:8:11.

[0014] Furthermore, in Step 2, the temperature for injecting Cs-OA is 150°C to 190°C, and the reaction time is 5 to 20 s.

[0015] Furthermore, in Step 3, the temperature of the water bath environment is 0 to 20°C, and the stirring time is 5 to 30 min.

[0016] Furthermore, in Step 4, the polar solvent is acetone and ethyl acetate; the volume ratio of the CsPbBr 3 nanowire crude solution to the polar solvent is 1:2.

[0017] Furthermore, in Step 5, the polar solvent is ethyl acetate; the volume ratio of toluene to the polar solvent is 1:2.

[0018] Furthermore, in Step 6, the organic solvent is one of toluene, n-hexane, and n-octane.

[0019] The advantages of the present invention compared with the prior art are as follows: In the CsPbBr of the present invention 3After the rapid nucleation and growth of nanocrystals are completed, in an air environment and under the condition of a widely adjustable temperature range of 0-20 °C, the structural reorganization from quantum dots to nanowires is completed. The operation is simple, the spectrum is controllable, and continuous adjustment from green light to blue light is achieved;

[0020] In the synthesis of nanowires of the present invention, no new organic ligands are introduced, which is beneficial to the application of light-emitting diodes; 3 During the synthesis of the nanowires, no new organic ligands are introduced, which is beneficial to the application of light-emitting diodes;

[0021] The method of the present invention can prepare CsPbBr 3 blue-light nanowires with uniform size, good dispersion and good crystallinity. The prepared blue-light nanowires have an emission wavelength of 453 nm, a full width at half maximum of 20 nm, and a fluorescence quantum yield reaching 81%, and have excellent stability. After being stored in an air environment for one month, the fluorescence intensity basically does not decay. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Absorption spectrum, fluorescence spectrum and fluorescence physical map of CsPbBr 3 nanocrystals at different times under the cooling condition in Example 1 of the present invention.

[0023] Figure 2 For the CsPbBr obtained in Example 1 3 Change curves of the emission peak and fluorescence intensity of nanowires with time.

[0024] Figure 3 For the CsPbBr obtained in Example 1 3 X-ray diffraction pattern (XRD) of nanowires.

[0025] Figure 4 For the CsPbBr obtained in Example 1 3 Transmission electron microscope (TEM) of nanowires.

[0026] Figure 5 Fluorescence spectra of Example 2 and Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0027] The following further describes in detail a method for preparing blue-light CsPbBr 3 nanowires by cooling and reorganization in combination with the accompanying drawings.

[0028] Combined with the attached Figures 1-5 drawings, the present invention is introduced in detail.

[0029] A method for preparing blue-light CsPbBr 3 nanowires by cooling and reorganization, the method for preparing blue-light CsPbBr 3 nanowires by cooling and reorganization is as follows:

[0030] Step 1: Prepare cesium oleate (Cs-OA). The raw materials for Cs-OA include cesium stearate, oleic acid, and octadecene. Place the above raw materials in a four-necked flask according to the ratio, and heat and stir until dissolved in an inert gas environment;

[0031] Step 2: Prepare CsPbBr 3 solution. The raw materials for the CsPbBr 3 solution include lead bromide, octadecene, oleic acid, and organic amine. Place the above raw materials in a four-necked flask according to the ratio, heat and stir until dissolved under inert gas, and inject Cs-OA at high temperature to obtain a crude CsPbBr 3 quantum dot solution;

[0032] Step 3: Place the obtained crude CsPbBr 3 quantum dot solution in a water bath environment and continuously stir to obtain a crude CsPbBr 3 nanowire solution;

[0033] Step 4: Add the crude CsPbBr 3 nanowire solution to a polar solvent for the first centrifugation operation to obtain a first precipitate;

[0034] Step 5: Dissolve the first precipitate in toluene, and add a polar solvent for the second centrifugation operation to obtain a second precipitate;

[0035] Step 6: Dissolve the second precipitate in an organic solvent to obtain a well-dispersed CsPbBr 3 nanowire solution.

[0036] In Step 1, the molar ratio of the raw materials is cesium stearate: oleic acid: octadecene = 2:5:49.

[0037] In Step 2, the molar ratio of the raw materials is lead bromide: octadecene: oleic acid: organic amine = 1:40:8:11.

[0038] In Step 2, the temperature for injecting Cs-OA is 150 °C to 190 °C, and the reaction time is 5 to 20 s.

[0039] In Step 3, the temperature of the water bath environment is 0 °C to 20 °C, and the stirring time is 5 to 30 min.

[0040] In Step 4, the polar solvent is acetone and ethyl acetate; the volume ratio of the crude CsPbBr 3 nanowire solution to the polar solvent is 1:2.

[0041] In Step 5, the polar solvent is ethyl acetate; the volume ratio of toluene to the polar solvent is 1:2.

[0042] The organic solvent in Step 6 is one of toluene, n-hexane, and n-octane.

[0043] The method for preparing blue-light CsPbBr 3 nanowires by cooling and recombination is specifically implemented as follows:

[0044] Example 1,

[0045] This example provides a method for preparing blue-light CsPbBr 3 nanowires by cooling and recombination. The organic amine used is oleylamine, and the specific steps are as follows:

[0046] Step 1: Put cesium stearate, oleic acid, and octadecene in a four-necked flask in a molar ratio of 2:5:49, heat until dissolved, and obtain a Cs-OA precursor solution;

[0047] Step 2: Put lead bromide, octadecene, oleic acid, and oleylamine in a four-necked flask in a molar ratio of 1:40:8:11, stir until dissolved under an inert gas condition, heat to 170 °C after dissolution, and inject the Cs-OA solution to react for 5 s;

[0048] Step 2: Place the solution obtained in Step 1 in cold water at 15 °C and stir for about 30 min to obtain a suspension;

[0049] Step 4: Put the suspension prepared in Step 3 into a centrifuge tube, add 20 ml of acetone and 20 ml of ethyl acetate, and centrifuge at 8000 rpm for 1 min to obtain a first precipitate;

[0050] Step 5: Dissolve the first precipitate in 6 ml of toluene, then add 12 ml of ethyl acetate, and centrifuge at 8000 rpm for 1 min to obtain a second precipitate;

[0051] Step 6: Dissolve the second precipitate in n-hexane, and its PL spectrum is as Figure 1 , and the crystallinity characterization XRD is as Figure 3 .

[0052] Example 2,

[0053] This example provides a method for preparing blue-light CsPbBr 3 nanowires by cooling and recombination. The organic amine used is dodecylamine, and the specific steps are as follows:

[0054] Step 1: Put cesium stearate, oleic acid, and octadecene in a four-necked flask in a molar ratio of 2:5:49, heat until dissolved, and obtain a Cs-OA precursor solution;

[0055] Step 2: Place lead bromide, octadecene, oleic acid, and dodecylamine in a four-necked flask at a molar ratio of 1:40:8:11, stir until dissolved under an inert gas condition, after dissolution, heat up to 170 °C, and inject the Cs-OA solution to react for 5 s;

[0056] Step 3: Place the solution obtained in Step 2 in cold water at 15 °C and stir for about 30 min to obtain a suspension;

[0057] Step 4: Place the suspension prepared in Step 3 in a centrifuge tube, add 20 ml of acetone and 20 ml of ethyl acetate, and centrifuge at 8000 rpm for 1 min to obtain a first precipitate;

[0058] Step 5: Dissolve the first precipitate in 6 ml of toluene, then add 12 ml of ethyl acetate, and centrifuge at 8000 rpm for 1 min to obtain a second precipitate;

[0059] Step 6: Dissolve the second precipitate in n-octane, and its PL spectrum is as Figure 5 。

[0060] Example 3,

[0061] This example provides a method for preparing blue-light CsPbBr 3 nanowires by cooling and recombination. The organic amine used is octylamine, and the specific steps are as follows:

[0062] Step 1: Place cesium stearate, oleic acid, and octadecene in a four-necked flask at a molar ratio of 2:5:49, heat until dissolved to prepare a Cs-OA precursor solution;

[0063] Step 2: Place lead bromide, octadecene, oleic acid, and octylamine in a four-necked flask at a molar ratio of 1:40:8:11, stir until dissolved under an inert gas condition, after dissolution, heat up to 170 °C, and inject the Cs-OA solution to react for 5 s;

[0064] Step 3: Place the solution obtained in Step 2 in cold water at 15 °C and stir for about 30 min to obtain a suspension;

[0065] Step 4: Place the suspension prepared in Step 3 in a centrifuge tube, add 20 ml of acetone and 20 ml of ethyl acetate, and centrifuge at 8000 rpm for 1 min to obtain a first precipitate;

[0066] Step 5: Dissolve the first precipitate in 6 ml of toluene, then add 12 ml of ethyl acetate, and centrifuge at 8000 rpm for 1 min to obtain a second precipitate;

[0067] Step 6: Dissolve the second precipitate in toluene, and its PL spectrum is as Figure 5 。

[0068] In the present invention, in CsPbBr3 After the rapid nucleation and growth of nanocrystals, the structural reorganization from quantum dots to nanowires is completed in an air environment under a wide range of adjustable temperature conditions of 0 to 20°C. The operation is simple, the spectrum is controllable, and continuous adjustment from green light to blue light is achieved.

[0069] The present invention is in CsPbBr 3 No new organic ligands are introduced during the synthesis of nanowires, which is beneficial to the application of electroluminescent diodes;

[0070] The method of the present invention can prepare CsPbBr with uniform size, good dispersion and good crystallinity. 3 The prepared blue light nanowires have an emission wavelength of 453nm, a half-peak width of 20nm, a fluorescence quantum yield of 81%, and excellent stability. After being stored in an air environment for one month, the fluorescence intensity thereof basically does not decay. The invention is reasonably designed and deserves to be vigorously promoted.

[0071] The present invention and its implementation methods are described above, and such description is not restrictive. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design structures and embodiments similar to the technical solution without creativity, which should all fall within the protection scope of the present invention.

Claims

1. A method for preparing blue-light CsPbBr 3 nanowires by a cooling recombination method It is characterized in that: The method for preparing the blue-light CsPbBr3 nanowires by cooling and recombination is as follows: Step 1: Prepare cesium oleate Cs-OA. The Cs-OA raw materials include cesium stearate, oleic acid, and octadecene. Place the above raw materials in a four-necked flask according to the ratio, and heat and stir in an inert gas environment until dissolved; Step 2: Prepare CsPbBr 3 solution. The raw materials of the CsPbBr 3 solution include lead bromide, octadecene, oleic acid, and organic amine. Place the above raw materials in a four-necked flask according to the ratio, heat and stir under an inert gas until dissolved, and inject Cs-OA at high temperature to obtain CsPbBr 3 quantum dot crude solution; Step 3: Place the CsPbBr quantum dot crude solution obtained from the reaction in a water bath environment and continuously stir to obtain a CsPbBr nanowire crude solution; the temperature of the water bath environment is 0-20 °C, and the stirring time is 12-30 min; 3 3 ​​ Step 4. Add the CsPbBr 3 nanowire crude solution to a polar solvent for the first centrifugation operation to obtain a first precipitate; Step 5: Dissolve the first precipitate in toluene, and add a polar solvent for a second centrifugation operation to obtain a second precipitate; Step 6. Dissolve the second precipitate in an organic solvent to obtain a CsPbBr nanowire solution with good dispersibility. 3 ​ 2. A method for preparing blue-light CsPbBr 3 nanowires by cooling and recombination according to claim 1 It is characterized in that: In Step 1, the molar ratio of the raw materials is cesium stearate: oleic acid: octadecene = 2:5:

49.

3. A method for preparing blue-light CsPbBr 3 nanowires by cooling and recombination according to claim 1 It is characterized in that: In Step 2, the molar ratio of the raw materials is lead bromide: octadecene: oleic acid: organic amine = 1:40:8:

11.

4. A method for preparing blue-light CsPbBr 3 nanowires according to claim 1 It is characterized in that: In Step 2, the temperature for injecting Cs-OA is 150 °C to 190 °C, and the reaction time is 5 to 20 s.

5. A method for preparing blue-light CsPbBr 3 nanowires according to claim 1 It is characterized in that: The polar solvent in Step 4 is acetone and ethyl acetate; CsPbBr 3 The volume ratio of the CsPbBr nanowire crude solution to the polar solvent is 1:

2.

6. A method for preparing blue-light CsPbBr 3 nanowires according to claim 1 It is characterized in that: In Step 5, the polar solvent is ethyl acetate; the volume ratio of toluene to the polar solvent is 1:

2.

7. A method for preparing blue-light CsPbBr 3 nanowires by cooling and recombination according to claim 1 It is characterized in that: In Step 6, the organic solvent is one of toluene, n-hexane, and n-octane.

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