Preparation method of efficient light-emitting Sr < 2 + > doped CsPbX3 quantum dots
In the preparation process of CsPbX3 quantum dots, thermal implantation method and strontium halide doping, combined with ligand compensation technology, the problem of optical performance degradation caused by high Sr2+ doping was solved, and the preparation of Sr2+ doped CsPbX3 quantum dots with high efficiency luminescence and high stability was achieved.
Patent Information
- Application Number
- CN202411924104.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-25
- Publication Date
- 2025-03-28
AI Technical Summary
The prior art is difficult to achieve the preparation of high Sr2+ doped CsPbX3 quantum dots while maintaining high quantum yield and stability, and higher Sr2+ doping will lead to a degradation of optical performance.
The CsPbX3 quantum dots were prepared by thermal injection method, and Sr2+ doping was achieved by adding strontium halide to the precursor and regulating the ratio of oleic acid, oleamine to lead halide and strontium halide. At the same time, OAmX ligand is used to compensate quantum dots to reduce defect states and improve luminescence performance.
The preparation of high-efficiency luminescent Sr2+ doped CsPbX3 quantum dots is achieved, which improves quantum yield and stability, reduces the toxicity of the material, and has the advantages of green and environmental protection.
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Figure CN119709193A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of nanomaterials and specifically relates to a highly efficient luminescent Sr 2+ Preparation method of doped CsPbX3 quantum dots. Background Art
[0002] All-inorganic cesium lead halide perovskite quantum dots (CsPbX3, where X represents Cl, Br or I) are considered to be ideal candidates for next-generation display technologies due to their excellent optical properties such as high quantum yield, narrow half-peak width and tunable fluorescence wavelength. However, the toxicity of Pb to the human body and its harm to the environment limit the practical application of CsPbX3 quantum dots.
[0003] Replacing toxic Pb ions with divalent or heterovalent metal cations via B-site doping has been shown to improve the optical properties and formation energy of CsPbX3 QDs. 2+ Sn 2+ 、Zn 2+ , Sr 2+ ), Sr 2+ Since its radius is very close to Pb 2+ , and can make quantum dots show a more stable structure, with higher tolerance factor and octahedral factor and attract attention. 2+ Doping will generate new defect states in quantum dots, resulting in a decrease in optical performance. 2+ Ensuring good optical properties (such as strong fluorescence intensity and high fluorescence quantum efficiency) while preparing doped CsPbX3 quantum dots is an urgent problem that needs to be solved.
[0004] Patent application "Strontium-doped perovskite quantum dots / mesoporous silica composite materials and preparation thereof" (application number CN114891504A, publication date 2022.08.12) discloses a method for achieving high Sr 2+ The doping amount also has a CsPbX3 composite material with high quantum yield and stability, but its quantum yield still has room for improvement (82%), and the quantum dots need to be isolated in mesoporous materials and protected physically, which limits its scope of application and does not fundamentally solve the new defect problem caused by excessive doping.
[0005] Therefore, a highly efficient luminescent Sr 2+ The preparation method of doped CsPbX3 quantum dots is used to solve the above problems. Summary of the invention
[0006] Purpose of the invention: To solve the problems existing in the prior art, the present invention provides a highly efficient luminescent Sr 2+Preparation method of doped CsPbX3 quantum dots.
[0007] A highly efficient luminescent Sr 2+ The preparation method of doped CsPbX3 quantum dots comprises the following steps: Step 1: weigh oleic acid, oleylamine, 1-octadecene and cesium carbonate, mix and stir, and heat to obtain a cesium oleate solution; Step 2: Weighing lead halide, strontium halide, oleic acid, oleylamine and 1-octadecene, mixing and stirring, and heating in a vacuum environment to obtain a precursor solution; Step 3: introducing nitrogen gas, heating to the injection temperature, and then quickly injecting the cesium oleate solution into the precursor solution. After a certain reaction time, the reaction container is placed in ice water to cool to room temperature to obtain a quantum dot stock solution; Step 4: Add flocculant to the quantum dot stock solution, mix well and centrifuge; Step 5: dispersing the obtained precipitate in toluene and adding a toluene solution of OAmX, followed by adding a flocculant, mixing well and centrifuging twice, wherein X is Cl, Br or I; Step 6: Disperse the obtained precipitate in a dispersant to obtain highly efficient luminescent Sr 2+ Doped CsPbX3 quantum dot solution.
[0008] Furthermore, in step 1, the concentration of cesium carbonate relative to 1-octadecene is 0.06 mmol / mL, oleylamine and oleic acid are equal, and the volume ratio of oleic acid to 1-octadecene is 1:16.
[0009] Furthermore, the heating temperature in step 1 is 120-150°C.
[0010] Furthermore, in step 2, the lead halide is replaced by one or a mixture of two or more of lead iodide, lead bromide or lead chloride, and the strontium halide is replaced by one or a mixture of two or more of strontium iodide, strontium bromide or strontium chloride, wherein the molar ratio of lead halide to strontium halide is 1:0-1:2.
[0011] Furthermore, in step 2, oleylamine and oleic acid are equal in amount, and the ratio of the sum of the molar amounts of lead halide and strontium halide to the molar amount of oleylamine is 1:6-1:12.
[0012] Furthermore, the heating temperature in step 2 is 110-130°C.
[0013] Furthermore, the injection temperature in step three is 140-220° C., and the reaction time is 5-15 s.
[0014] Furthermore, the flocculant in steps 4 and 5 is methyl acetate, ethyl acetate or isopropanol, and the volume ratio of the sum of the volumes of other solvents to the volume of the flocculant is 1:2.
[0015] Furthermore, the centrifugation speed in step 4 and step 5 is 6000-10000 rpm, and the centrifugation time is 1-5 min.
[0016] Furthermore, in step 5, OAmX is one of oleylamine iodine, oleylamine bromide or oleylamine chloride, or a mixture of two or more thereof, the concentration of the toluene solution of OAmX is 5 mmol / mL, and the added amount is 0.1-1 times the volume of the dispersant.
[0017] Furthermore, in step six, the dispersant is n-hexane, n-octane or toluene.
[0018] Principle of the invention: The invention is based on the preparation of CsPbX3 quantum dots by hot injection method. By adding strontium halide to the precursor and rationally adjusting the parameters such as the ratio of oleic acid, oleylamine, lead halide and strontium halide, the Sr 2+ Preparation of doped CsPbX3 quantum dots. The present invention uses OAmX ligands to compensate for quantum dots in the post-processing process of quantum dots, and effectively reduces the defect states in quantum dots by compensating the surface defects of quantum dots with ligands and halogen ions, thereby increasing the proportion of radiation recombination and further improving the Sr 2+ Luminescence performance and stability of doped CsPbX3 quantum dots.
[0019] Beneficial effect: The highly efficient luminescent Sr 2+ The preparation method of doped CsPbX3 quantum dots is simple, controllable, easy to operate, and can be applied to Sr 2+ The synthesis of full-spectrum quantum dots doped with CsPbX3 has a wide range of practical applications. 2+ Doping reduces the Pb content in perovskite quantum dots, reduces the toxicity of the material, and has the advantage of being green and environmentally friendly. 2+ Doping synergistically achieves the performance optimization of quantum dots. The obtained quantum dots have excellent luminescence performance and a small and uniform average particle size. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 It is a comparison diagram of emission spectra of Example 1-2 of the present invention and Comparative Example 1-2; Figure 2 This is a comparison chart of the fluorescence quantum efficiency of Example 1-2 of the present invention and Comparative Example 1-2; Figure 3 A comparison chart of fluorescence lifetimes of Example 1-2 of the present invention and Comparative Example 1-2; Figure 4 The X-ray diffraction patterns of Example 1 and Comparative Example 2 of the present invention; Figure 5 TEM images of Example 1 and Comparative Example 2 of the present invention; Figure 6 This is a comparison diagram of the Sr element spectrum of the X-ray photoelectron spectroscopy of Example 1 of the present invention and Comparative Example 2; Figure 7 It is a comparison diagram of emission spectra of Example 1 and Examples 3-4 of the present invention; Figure 8 It is a comparison diagram of the emission spectra of Example 1 and Examples 5-6 of the present invention; Fig. 9 It is a comparison diagram of emission spectra of Example 1 and Examples 7-8 of the present invention; Fig.10 It is a comparison diagram of the emission spectra of Example 1 and Examples 9-10 of the present invention. DETAILED DESCRIPTION
[0021] The preferred embodiments of the present invention will be described below in conjunction with the accompanying drawings to more clearly and completely illustrate the technical solutions of the present invention. Example
[0022] A highly efficient luminescent Sr 2+ The preparation method of doped CsPbX3 quantum dots comprises the following steps: Step 1: 0.3125 mL of oleic acid, 0.3125 mL of oleylamine, 5 mL of 1-octadecene and 0.102 g of cesium carbonate were mixed and stirred, and heated at 120° C. to obtain a cesium oleate solution.
[0023] Step 2: 0.087 g of lead iodide, 0.0896 g of strontium iodide, 1.2 mL of oleic acid, 1.2 mL of oleylamine, and 5 mL of 1-octadecene are mixed and stirred. The molar ratio of lead iodide to strontium iodide is 1:1.4, and the ratio of the sum of the molar amounts of lead iodide and strontium iodide to the molar amount of oleylamine is about 1:8. In a vacuum environment, heat at 120° C. to obtain a precursor solution.
[0024] Step 3: introduce nitrogen, heat to 180°C, and then quickly inject 0.4 mL of cesium oleate solution into the precursor solution. After reacting for 5 seconds, place the reaction container in ice water and cool to room temperature to obtain a quantum dot stock solution.
[0025] Step 4: Add 10 mL of ethyl acetate to the quantum dot stock solution, mix well, put into a centrifuge, set the speed to 8000 rpm, and centrifuge for 1 min.
[0026] Step 5: After centrifugation, remove the supernatant, disperse the precipitate in 2 mL of toluene and add 1 mL of oleylamine iodine toluene solution, the amount added being 0.5 times the volume of the toluene dispersant. Then add 6 mL of ethyl acetate, mix well, put into a centrifuge and set the speed to 8000 rpm for 1 min.
[0027] Step 6: After centrifugation, remove the supernatant and disperse the resulting precipitate in 6 mL of n-hexane to obtain CsSr 0.15 Pb 0.75 I3 perovskite quantum dot solution. Example
[0028] The same process as in Example 1 was adopted, except that only 0.128 g of strontium iodide, 1.5 mL of oleic acid and 1.5 mL of oleylamine were added in step 2, and the molar ratio of lead iodide to strontium iodide was 1:2. Example
[0029] The same process as in Example 1 was adopted, except that only 0.8 mL of oleic acid and 0.8 mL of oleylamine were added in step 2, and the ratio of the sum of the molar amounts of lead iodide and strontium iodide to the molar amount of oleylamine was about 1:6. Example
[0030] The same process as in Example 1 was adopted, except that 1.25 mL of oleic acid and 1.25 mL of oleylamine were added in step 2, and the ratio of the sum of the molar amounts of lead iodide and strontium iodide to the molar amount of oleylamine was about 1:10. Example
[0031] The same process as in Example 1 is adopted, except that the injection temperature in step 3 is only 140°C. Example
[0032] The same process as in Example 1 is adopted, except that the injection temperature in step 3 is 220°C. Example
[0033] The same process as in Example 1 was adopted, except that the reaction time in step 3 was 10 s. Example
[0034] The same process as in Example 1 was adopted, except that the reaction time in step 3 was 15 s. Example
[0035] The same process as in Example 1 was adopted, except that in step 5, the amount of toluene solution of oleylamine iodine added was only 0.2 mL, which was 0.1 times the volume of the toluene dispersant. Example
[0036] The same process as in Example 1 was adopted, except that in step 5, the amount of oleylamine iodine toluene solution added was 1.5 mL, which was 0.75 times the volume of the toluene dispersant.
[0037] Comparative Example 1 The same process as in Example 1 is adopted, except that the toluene solution of oleylamine iodide is not added in step 5.
[0038] Comparative Example 2 The same process as in Example 1 is adopted, except that strontium iodide is not added in step 2, and the toluene solution of oleylamine iodine is not added in step 5.
[0039] Figure 1 It can be seen that the synergistic effect of strontium doping and ligand compensation can continue to enhance the photoluminescence of quantum dots on the basis of strontium doping greatly improving the fluorescence intensity of CsPbI3 quantum dots.
[0040] Figure 2 It can be seen that Sr 2+ Doping increases the quantum efficiency of quantum dots by 1.5 times, and the ligand compensation process makes Sr 2+ The photonic quantum efficiency of CsPbI3 quantum dots is increased by about 20%.
[0041] Figure 3 Highly efficient luminescent Sr 2+ Doped CsPbX3 quantum dots have the longest lifetime, followed by Sr 2+ Among the doped CsPbX3 quantum dots, the CsPbX3 quantum dots prepared by the undoped and ligand-free compensation process have the shortest lifetime, which is consistent with the changing law of fluorescence intensity and photonic quantum efficiency.
[0042] Figure 4 It can be seen that the efficient luminescence Sr 2+ The X-ray spectrum of doped CsPbX3 quantum dots has sharper diffraction peaks and higher crystallinity. The slight shift of the characteristic peak to high angles is caused by the contraction of the crystal structure caused by doping.
[0043] Figure 5 It can be seen that the efficient luminescence Sr 2+ The particle size of doped CsPbX3 quantum dots is significantly reduced, and the crystal distribution is more neat and uniform.
[0044] Figure 6 It can be seen that the efficient luminescence Sr 2+ There are characteristic peaks belonging to the Sr element in the X-ray photoelectron spectrum of doped CsPbX3 quantum dots.
[0045] Figure 7 It can be seen that the highly efficient luminescent Sr can be synthesized under the conditions that the molar ratio of the sum of the lead halide and strontium halide to the molar amount of oleylamine is about 1:6, 1:8, and 1:10. 2+ Doped CsPbX3 quantum dots.
[0046] Figure 8 It can be seen that efficient luminescent Sr with a wavelength range of 667-687nm can be synthesized under injection temperatures of 140℃, 180℃, and 220℃. 2+ Doped CsPbX3 quantum dots.
[0047] Fig. 9 It can be seen that highly efficient luminescent Sr with a wavelength range of 675-688 nm can be synthesized under reaction times of 5 s, 10 s, and 15 s. 2+ Doped CsPbX3 quantum dots.
[0048] Fig.10 It can be seen that the highly efficient luminescent Sr can be synthesized under the condition that the amount of OAmX toluene solution added is 0.1, 0.5, and 0.75 times the volume of toluene dispersant. 2+ Doped CsPbX3 quantum dots.
[0049] In summary, the present invention discloses a highly efficient luminescent Sr 2+ Preparation method of doped CsPbX3 quantum dots using ligand compensation process and Sr 2+ Doping synergistically achieves the performance optimization of quantum dots. The obtained quantum dots have excellent luminescence performance and a small and uniform average particle size.
Claims
1. A highly efficient luminescent Sr 2+ The preparation method of doped CsPbX3 quantum dots is characterized in that: The following steps are involved: Step 1: weigh oleic acid, oleylamine, 1-octadecene and cesium carbonate, mix and stir, and heat to obtain a cesium oleate solution; Step 2: Weighing lead halide, strontium halide, oleic acid, oleylamine and 1-octadecene, mixing and stirring, and heating in a vacuum environment to obtain a precursor solution; Step 3: introducing nitrogen gas, heating to the injection temperature, and then quickly injecting the cesium oleate solution into the precursor solution. After a certain reaction time, the reaction container is placed in ice water to cool to room temperature to obtain a quantum dot stock solution; Step 4: Add flocculant to the quantum dot stock solution, mix well and centrifuge; Step 5: dispersing the obtained precipitate in toluene and adding a toluene solution of OAmX, followed by adding a flocculant, mixing well and centrifuging twice, wherein X is Cl, Br or I; Step 6: Disperse the obtained precipitate in a dispersant to obtain highly efficient luminescent Sr 2+ Doped CsPbX3 quantum dot solution.
2. The highly efficient luminescent Sr according to claim 1 2+ The preparation method of doped CsPbX3 quantum dots is characterized in that: In step 1, the concentration of cesium carbonate relative to 1-octadecene is 0.06 mmol / mL, oleylamine and oleic acid are equal, and the volume ratio of oleic acid to 1-octadecene is 1:
16.
3. The highly efficient luminescent Sr according to claim 1 2+ The preparation method of doped CsPbX3 quantum dots is characterized in that: The heating temperature in step 1 is 120-150°C.
4. The highly efficient luminescent Sr according to claim 1 2+ The preparation method of doped CsPbX3 quantum dots is characterized in that: In step 2, the lead halide is replaced by one of lead iodide, lead bromide or lead chloride or a mixture of two or more thereof, and the strontium halide is replaced by one of strontium iodide, strontium bromide or strontium chloride or a mixture of two or more thereof, wherein the molar ratio of the lead halide to the strontium halide is 1:0-1:
2.
5. The highly efficient luminescent Sr according to claim 1 2+ The preparation method of doped CsPbX3 quantum dots is characterized in that: In step 2, oleylamine and oleic acid are equal in amount, and the ratio of the sum of the molar amounts of lead halide and strontium halide to the molar amount of oleylamine is 1:6-1:
12.
6. The highly efficient luminescent Sr according to claim 1 2+ The preparation method of doped CsPbX3 quantum dots is characterized in that: The heating temperature in step 2 is 110-130°C.
7. The highly efficient luminescent Sr according to claim 1 2+ The preparation method of doped CsPbX3 quantum dots is characterized in that: The injection temperature in step 3 is 140-220°C, and the reaction time is 5-15s.
8. The highly efficient luminescent Sr according to claim 1 2+ The preparation method of doped CsPbX3 quantum dots is characterized in that: The flocculant in steps 4 and 5 is methyl acetate, ethyl acetate or isopropanol, and the volume ratio of the sum of the volumes of other solvents to the volume of the flocculant is 1:
2.
9. The highly efficient luminescent Sr according to claim 1 2+ The preparation method of doped CsPbX3 quantum dots is characterized in that: The centrifugal speed in step 4 and step 5 is 6000-10000 rpm, and the centrifugal time is 1-5 min.
10. The highly efficient luminescent Sr according to claim 1 2+ The preparation method of doped CsPbX3 quantum dots is characterized in that: In step 5, OAmX is one of oleylamine iodine, oleylamine bromide or oleylamine chloride, or a mixture of two or more thereof, the concentration of the toluene solution of OAmX is 5 mmol / mL, and the amount added is 0.1-1 times the volume of the dispersant.