A method for synthesizing core-shell quantum dots based on surface activation

Abstract

The application belongs to the technical field of optical materials, and particularly discloses a synthesis method of core-shell quantum dots based on surface activation, which comprises the following steps: S1, preparing a quantum dot core; S2, degassing reaction is carried out on zinc precursor, octadecene and oleylamine in proportion, then the quantum dot core obtained in S1 is injected, a metal alkyl compound is added, and the temperature is increased to 230-250 DEG C; S3, the shell precursor is injected for 3-4 times, the temperature is increased at the same time, the inner shell is grown, zinc stearate and TOP-S are injected again, the ZnS shell is grown, and the InP core-shell quantum dots with regular morphology are obtained. The synthesis method of core-shell quantum dots based on surface activation is adopted, the quantum dots with controllable morphology and size distribution are obtained, the method is suitable for industrial production, and has wide applicability.

Description

A method for synthesizing core-shell quantum dots based on surface activation Technical Field

[0001] This invention relates to the field of optical materials technology, and in particular to a method for synthesizing core-shell quantum dots based on surface activation. Background Technology

[0002] Quantum dots, as a novel optical material, have attracted widespread attention due to their unique performance advantages. These materials not only possess wavelength tunability, high luminous efficiency, excellent process reliability and operational stability, but also achieve high-purity colorimetric performance. Based on these properties, quantum dots have demonstrated significant application value in fields such as light-emitting diodes, photodetectors, solar cells, and biomarkers.

[0003] In existing technologies, the highest-performing quantum dot materials are mainly based on cadmium selenide and lead halide perovskite systems, characterized by high photoluminescence quantum yield and narrow fluorescence emission half-width. However, these cadmium / lead-containing materials pose potential environmental pollution and biotoxicity risks. Therefore, the development of high-performance cadmium / lead-free quantum dots has become a research focus.

[0004] Among numerous alternative materials, indium phosphide (InP) quantum dots are the most promising candidate due to their tunable emission wavelengths (covering the visible to near-infrared band). Despite significant progress in InP quantum dot research, the synthesis technology of its green luminescent system still lags behind that of the red luminescent system. This is mainly due to the challenge of controlling the shell growth process: although strategies such as etching, stoichiometry control, precursor optimization, and inorganic ligand surface engineering have successfully improved the efficiency, stability, and practicality of InP core-shell quantum dots, these methods face unique challenges in the preparation of green InP quantum dots. The core problem lies in the Ostwald ripening phenomenon that easily occurs in small-sized InP cores under high-temperature conditions.

[0005] Furthermore, InP quantum dots prepared using indium carboxylate and tris(trimethylsilyl)phosphorus as precursors have surfaces primarily occupied by carboxylic acid ligands. These ligands exhibit strong coordination with the quantum dot surface, significantly impacting the growth kinetics of the epitaxial shell. For example, excessive surface alkanoate ligands can lead to a quantum dot growth rate far lower than the nucleation rate, resulting in growth bottlenecks such as size limitations and morphological irregularities. Although studies have shown that using small-sized ligand precursors can improve the controllable growth of core / shell structures, the coexistence of carboxylic acid ligands and weakly coordinated ligands may lead to selective adsorption and exchange reactions on specific crystal planes of the quantum dots, further increasing the difficulty of controlling morphology and size distribution. Summary of the Invention

[0006] The purpose of this invention is to provide a method for synthesizing core-shell quantum dots based on surface activation, which yields quantum dots with controllable morphology and size distribution, suitable for industrial production and with wide applicability.

[0007] To achieve the above objectives, the present invention provides a method for synthesizing core-shell quantum dots based on surface activation, comprising the following steps:

[0008] S1. Preparation of quantum dot cores;

[0009] S2. Mix zinc precursor, octadecene and oleylamine in proportion and degas the mixture. Then inject the mixture into the quantum dot core obtained in S1, add metal alkyl compounds, and heat to 230-250℃.

[0010] S3. Inject solution A and zinc stearate, react, heat to 275-285℃, hold, then heat to 286-295℃, inject solution B and zinc stearate, hold, then heat to 296-305℃, inject solution C and zinc stearate, hold; then heat to 306-315℃, inject solution D and zinc stearate, hold, grow the inner shell, then inject zinc stearate and TOP-S, react, grow the ZnS shell, and obtain InP core-shell quantum dots with regular morphology.

[0011] Preferably, S1 is as follows:

[0012] In a specific ratio, indium acetate, zinc acetate, hexadecanoic acid, and octadecene are mixed and degassed. Then, nitrogen is introduced and the mixture is cooled to room temperature. Tris(trimethylsilyl)phosphine dissolved in trioctylphosphine is injected, and the temperature is raised to obtain the InP core. Zinc stearate and TOP-Se are then injected to obtain the quantum dot core.

[0013] The ratio of the amounts of indium acetate, zinc acetate, hexadecanoic acid, octadecene, trioctylphosphine, tris(trimethylsilyl)phosphine, zinc stearate, and TOP-Se is 0.3 mmol: 0.15 mmol: 1.05 mmol: 10 mL: 2 mL: 0.20 mmol: 1 mmol: 0.6 mmol;

[0014] The degassing reaction was carried out at 120°C for 2 hours.

[0015] The InP core is obtained by heating it to 270°C and reacting it for 5 minutes. The quantum dot core is obtained by washing it after reacting the zinc stearate and the TOP-Se at 270°C for 30 minutes.

[0016] Preferably, in S2, the zinc precursor is one or both of zinc acetate and zinc stearate.

[0017] Preferably, in S2, the ratio of the zinc precursor, the octadecene, and the oleylamine is 2.2 mmol: 3 mL: 3 mL, and the degassing reaction is carried out at 120°C for 30 min.

[0018] Preferably, in S2, the molar ratio of the amount of the metal alkyl compound added to the quantum dot core is 150-200:1;

[0019] The metal alkyl compound is one or more of zinc-containing metal alkyl compounds, indium-containing metal alkyl compounds, and gallium-containing metal alkyl compounds.

[0020] Preferably, the zinc-containing metal alkyl compound is one or more of dimethyl zinc, diethyl zinc, diisopropyl zinc, and dibutyl zinc; the indium-containing metal alkyl compound is triethyl indium; and the gallium-containing metal alkyl compound is trimethyl gallium.

[0021] Preferably, in S3, solution A and solution B are one or both of TOP-Se and TOP-S, wherein the ratio of the amount of TOP-Se and TOP-S mixture is Se / S = 1-4:1;

[0022] Both solution C and solution D are one or both of TOP-Se and TOP-S, wherein the ratio of the amount of TOP-Se and TOP-S mixture is Se / S = 1:1-5.

[0023] Preferably, in S3, the injection solution A and zinc stearate are specifically configured such that the ratio of solution A to zinc stearate is 0.85 mmol: 0.8 mmol.

[0024] The injection solution B and zinc stearate are specifically configured such that the ratio of solution B to zinc stearate is 1.2 mmol: 0.8 mmol.

[0025] The injection solution C and zinc stearate are specifically configured such that the ratio of solution C to zinc stearate is 1.55 mmol: 0.8 mmol.

[0026] The injection solution D and zinc stearate are specifically configured such that the ratio of solution D to zinc stearate is 0.95 mmol: 0.4 mmol.

[0027] Preferably, in S3, the re-injection of zinc stearate and TOP-S specifically means that the molar ratio of zinc stearate and TOP-S is 0.4:0.95.

[0028] Preferably, in S3, the reaction time and the heat preservation time are both 0-2 hours.

[0029] Preferably, in step S3, the reaction time is 0.5-1.5 h, and the heat preservation time is 15-45 min.

[0030] Therefore, the present invention employs the above-mentioned method for synthesizing core-shell quantum dots based on surface activation, and the beneficial effects are as follows:

[0031] (1) The present invention synthesizes morphologically regular green InP core-shell quantum dots by activating surface ligands. This method is applicable not only to quantum dots with different light-emitting systems such as yellow and red light, but also to InAs core-shell quantum dots, and has wide applicability.

[0032] (2) The present invention introduces metal alkyl compounds to promote the adsorption and desorption of carboxylic acid ligands on the surface of quantum dot core during shell growth. By removing excess carboxylic acid ligands, the surface of quantum dot core is activated, avoiding selective growth during epitaxial shell growth and providing favorable conditions for subsequent good morphology control. At the same time, zinc stearate and zinc acetate are used as zinc precursors to control the growth rate, resulting in high quantum yield quantum dots with controllable morphology and size distribution, which are suitable for industrial production.

[0033] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0034] Figure 1 shows a green InP / ZnSe synthesized using a surface-activated core-shell quantum dot synthesis method according to Example 1 of the present invention. thin Absorption spectrum (solid line) and fluorescence spectrum (dashed line) of quantum dots;

[0035] Figure 2 shows the test results of green InP / ZnSe / ZnSeS / ZnS quantum dots in Example 1 of the synthesis method of core-shell quantum dots based on surface activation of the present invention, where (a) is the absorption spectrum (solid line) and fluorescence spectrum (dashed line), and (b) is the scanning transmission electron microscope (STEM) image.

[0036] Figure 3 shows the test results of green InP / ZnSe / ZnSeS / ZnS quantum dots in Example 2 of the synthesis method of core-shell quantum dots based on surface activation of the present invention, where (a) is the absorption spectrum (solid line) and fluorescence spectrum (dashed line), and (b) is the scanning transmission electron microscope image.

[0037] Figure 4 shows the test results of green InP / ZnSe / ZnSeS / ZnS quantum dots in Example 3 of the synthesis method of core-shell quantum dots based on surface activation of the present invention, where (a) is the absorption spectrum (solid line) and fluorescence spectrum (dashed line), and (b) is the scanning transmission electron microscope image.

[0038] Figure 5 shows the test results of the yellow InP / ZnSe / ZnS quantum dots in Example 4 of the present invention, where (a) is the absorption spectrum (solid line) and fluorescence spectrum (dashed line), and (b) is the transmission electron microscope (TEM) image.

[0039] Figure 6 shows the test results of red InP / ZnSe / ZnS quantum dots in Example 5 of the present invention, where (a) is the absorption spectrum (solid line) and fluorescence spectrum (dashed line), and (b) is the transmission electron microscope image;

[0040] Figure 7 shows the test results of InAs / ZnSe / ZnS quantum dots in Example 6 of the present invention, where (a) is the absorption spectrum (solid line) and fluorescence spectrum (dashed line) of quantum dots treated with diethylzinc (blue line) and without diethylzinc (red line), (b) is the scanning transmission electron microscope image of quantum dots treated with diethylzinc, and (c) is the scanning transmission electron microscope image of quantum dots without diethylzinc. Detailed Implementation

[0041] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0042] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0043] Example 1

[0044] A method for synthesizing green InP / ZnSe / ZnSeS / ZnS quantum dots using zinc stearate as a precursor, comprising the following steps:

[0045] S1. 0.30 mmol of indium acetate (InAc3), 0.15 mmol of zinc acetate (ZnAc2), 1.05 mmol of hexadecanoic acid (PA), and 10 mL of octadecene (ODE) were degassed at 120 °C for 2 h. Then, nitrogen was introduced and the mixture was cooled to room temperature. 0.20 mmol of tris(trimethylsilyl)phosphine ((TMS)3P) (dissolved in 2 mL of trioctylphosphine (TOP)) was injected, and the mixture was heated to 270 °C. After reacting for 5 min, the InP core was obtained. Then, 1 mmol of zinc stearate (ZnSt2) and 0.6 mmol of trioctylphosphine-selenium (TOP-Se) were injected, and after reacting for 30 min, InP / ZnSe was obtained. thin Quantum dots, after washing, are dispersed in n-hexane for later use.

[0046] S2. Place a mixed solution of 2.2 mmol zinc stearate, 3 mL octadecene, and 3 mL oleylamine into a three-necked flask, degas at 120 °C for 30 min, and then wash the InP / ZnSe solution. thin Quantum dots are injected and heated to 240°C.

[0047] S3. Inject a mixed solution of 0.85 mmol TOP-Se and trioctylphosphine-sulfur (TOP-S) (where Se / S = 7 / 3) and 0.80 mmol zinc stearate, react for 60 min, raise the temperature to 280 °C, and hold for 30 min; then raise the temperature to 290 °C, and inject another mixed solution of 1.20 mmol TOP-Se and TOP-S (where Se / S = 7 / 3) and 0.80 mmol zinc stearate, hold for 30 min; then raise the temperature to 300 °C, and inject another 1.55 mmol... A mixed solution of TOP-Se and TOP-S (where Se / S = 8 / 9) and 0.80 mmol of zinc stearate were added and incubated for 30 min. The temperature was then raised to 310 °C, and a mixed solution of 0.95 mmol of TOP-Se and TOP-S (where Se / S = 1 / 3) and 0.40 mmol of zinc stearate were injected. The mixture was incubated for 30 min to epitaxially grow a gradient-varying ZnSeS shell. Then, 0.40 mmol of zinc stearate and 0.95 mmol of TOP-S were injected, and the reaction was carried out for 30 min to grow a ZnS shell. InP / ZnSe / ZnSeS / ZnS quantum dots were obtained.

[0048] Example 2

[0049] The difference from Example 1 is that a method for synthesizing green InP / ZnSe / ZnSeS / ZnS quantum dots using zinc stearate and zinc acetate as precursors is described below:

[0050] S1. 0.30 mmol of indium acetate, 0.15 mmol of zinc acetate, 1.05 mmol of hexadecanoic acid, and 10 mL of octadecene were degassed at 120 °C for 2 h. Then, nitrogen was introduced and the mixture was cooled to room temperature. 0.20 mmol of tris(trimethylsilyl)phosphide dissolved in TOP was injected, and the temperature was raised to 270 °C. After reacting for 5 min, InP cores were obtained. Then, 1 mmol of zinc stearate and 0.6 mmol of TOP-Se were injected, and after reacting for 30 min, InP / ZnSe was obtained. thin Quantum dots, after washing, are dispersed in n-hexane for later use.

[0051] S2. Place a mixed solution of 2.2 mmol zinc acetate, 3 mL octadecene, and 3 mL oleylamine into a three-necked flask, degas at 120 °C for 30 min, and then inject the washed InP / ZnSe solution. thin Quantum dots, heated to 240°C.

[0052] S3. Inject 0.85 mmol of a mixed solution of TOP-Se and TOP-S (where Se / S = 7 / 3) and 0.8 mmol of zinc stearate, react for 60 min, raise the temperature to 280 °C, and hold for 30 min; then raise the temperature to 290 °C, and inject 1.20 mmol of a mixed solution of TOP-Se and TOP-S (where Se / S = 7 / 3) and 0.80 mmol of zinc stearate, hold for 30 min; then raise the temperature to 300 °C, and inject 1.55 mmol of... A mixed solution of TOP-Se and TOP-S (where Se / S = 8 / 9) and 0.80 mmol of zinc stearate were added and incubated for 30 min. The temperature was then raised to 310 °C, and a mixed solution of 0.95 mmol of TOP-Se and TOP-S (where Se / S = 1 / 3) and 0.40 mmol of zinc stearate were injected. The mixture was incubated for 30 min to epitaxially grow a gradient-varying ZnSeS shell. Then, 0.40 mmol of zinc stearate and 0.95 mmol of TOP-S were injected, and the reaction was carried out for 30 min to grow a ZnS shell. InP / ZnSe / ZnSeS / ZnS quantum dots were obtained.

[0053] Example 3

[0054] The difference from Example 2 is that a method for synthesizing green InP / ZnSe / ZnSeS / ZnS quantum dots using zinc stearate and zinc acetate as precursors and based on diethylzinc for surface activation is described below:

[0055] S1. 0.30 mmol of indium acetate, 0.15 mmol of zinc acetate, 1.05 mmol of hexadecanoic acid, and 10 mL of octadecene were degassed at 120 °C for 2 h. Then, nitrogen was introduced and the mixture was cooled to room temperature. 0.20 mmol of tris(trimethylsilyl)phosphide dissolved in TOP was injected, and the temperature was raised to 270 °C. After reacting for 5 min, InP cores were obtained. Then, 1 mmol of zinc stearate and 0.6 mmol of TOP-Se were injected, and after reacting for 30 min, InP / ZnSe was obtained. thin Quantum dots, after washing, are dispersed in n-hexane for later use.

[0056] S2. Place a mixed solution of 2.2 mmol zinc acetate, 3 mL octadecene, and 3 mL oleylamine into a three-necked flask and degas at 120 °C for 30 min. Then inject the washed InP / ZnSe solution. thin Quantum dots were added, along with 0.3 mmol of diethylzinc (ZnEt2), and the mixture was heated to 240°C.

[0057] S3. Inject 0.85 mmol of a mixed solution of TOP-Se and TOP-S (where Se / S = 7 / 3) and 0.80 mmol of zinc stearate, react for 60 min, raise the temperature to 280 °C, and hold for 30 min; then raise the temperature to 290 °C, and inject 1.20 mmol of a mixed solution of TOP-Se and TOP-S (where Se / S = 7 / 3) and 0.80 mmol of zinc stearate, hold for 30 min; then raise the temperature to 300 °C, and inject 1.55 mmol of... A mixed solution of TOP-Se and TOP-S (where Se / S = 8 / 9) and 0.80 mmol of zinc stearate were added and incubated for 30 min. The temperature was then raised to 310 °C, and a mixed solution of 0.95 mmol of TOP-Se and TOP-S (where Se / S = 1 / 3) and 0.40 mmol of zinc stearate were injected. The mixture was incubated for 30 min to epitaxially grow a gradient-varying ZnSeS shell. Then, 0.40 mmol of zinc stearate and 0.95 mmol of TOP-S were injected, and the reaction was carried out for 30 min to grow a ZnS shell. InP / ZnSe / ZnSeS / ZnS quantum dots were obtained.

[0058] Example 4

[0059] The difference from Example 3 is that a method for synthesizing yellow InP / ZnSe / ZnS quantum dots using zinc stearate and zinc acetate as precursors is described below:

[0060] 0.40 mmol of indium acetate, 1.20 mmol of hexadecanoic acid, and 10 mL of octadecene were degassed at 120 °C for 1 h. Then, nitrogen was introduced and the temperature was raised to 270 °C. 0.20 mmol of tris(trimethylsilyl)phosphine was injected, and the reaction was allowed to proceed for 40 min to obtain the InP core. Next, 0.66 mmol of zinc stearate was injected, and the reaction was allowed to proceed for 10 min. Following this, 0.40 mmol of TOP-Se was injected, and the reaction was allowed to proceed for 15 min to obtain InP / ZnSe. thin Quantum dots, after washing, are dispersed in n-hexane for later use.

[0061] A mixed solution of 2.2 mmol zinc acetate, 3 mL octadecene, and 3 mL oleylamine was placed in a three-necked flask and degassed at 120 °C for 30 min. Then, washed InP / ZnSe was injected. thinQuantum dots were then added to a solution containing 0.3 mmol of diethylzinc, heated to 240 °C, followed by the injection of 0.85 mmol of TOP-Se and 0.8 mmol of zinc stearate. The reaction was carried out for 60 min, and the temperature was then increased to 280 °C and held for 30 min. The temperature was then increased to 290 °C, followed by the injection of 1.20 mmol of TOP-Se and 0.80 mmol of zinc stearate, and held for 30 min. The temperature was then increased to 300 °C, followed by the injection of 1.55 mmol of TOP-Se and 0.80 mmol of zinc stearate, and held for 30 min to grow a ZnSe shell. Finally, the temperature was increased to 310 °C, followed by the injection of 0.40 mmol of zinc stearate and 0.95 mmol of TOP-S, and the reaction was carried out for 30 min to grow a ZnS shell. This yielded yellowish InP / ZnSe / ZnS quantum dots.

[0062] Example 5

[0063] The difference from Example 3 is that a method for synthesizing red-light InP / ZnSe / ZnS quantum dots using zinc stearate and zinc acetate as precursors is described below:

[0064] 1.50 mmol of indium acetate, 4.5 mmol of oleic acid, and 15 mL of octadecene were degassed at 120 °C for 1 h. Then, nitrogen gas was introduced and the temperature was raised to 300 °C. 0.50 mmol of tris(trimethylsilyl)phosphine was injected, and the reaction was allowed to proceed for 15 min. The temperature was then lowered to 270 °C, and InP clusters were injected to obtain InP quantum dots with a first exciton absorption peak at 570 nm. After washing, these quantum dots were dispersed in n-hexane for later use.

[0065] Preparation of InP clusters: 1 mmol of indium acetate, 3 mmol of oleic acid and 5 mL of octadecene were degassed at 120 °C for 1 h, then cooled to room temperature, and 0.50 mmol of tris(trimethylsilyl)phosphine was injected. After stirring for 1 min, InP clusters were obtained and set aside for later use.

[0066] A mixed solution of 2.2 mmol zinc acetate, 3 mL octadecene, and 3 mL oleylamine was placed in a three-necked flask and degassed at 120 °C for 30 min. Then, washed InP quantum dots were injected, followed by 0.3 mmol diethylzinc. The temperature was raised to 240 °C, and then 0.85 mmol TOP-Se and 0.8 mmol zinc stearate were injected. The reaction was carried out for 60 min, and the temperature was raised to 280 °C and held for 30 min. The temperature was then raised to 290 °C, and 1.20 mmol TOP-Se and 0.80 mmol zinc stearate were injected, and the temperature was held for 30 min. The temperature was then raised to 300 °C, and 1.55 mmol TOP-Se and 0.80 mmol zinc stearate were injected, and the temperature was held for 30 min to grow a ZnSe shell epitaxially. Finally, the temperature was raised to 310 °C, and 0.40 mmol zinc stearate and 0.95 mmol TOP-S were injected, and the reaction was carried out for 30 min to grow a ZnS shell. Red-light InP / ZnSe / ZnS quantum dots were obtained.

[0067] Example 6

[0068] The difference from Example 3 is that a method for synthesizing InAs / ZnSe / ZnS quantum dots using zinc stearate and zinc acetate as precursors is described below:

[0069] 1 mmol of indium acetate, 3 mmol of oleic acid, 0.5 mmol of indium fluoride, and 5 mL of octadecene were degassed at 120 °C for 1 h. Then, nitrogen gas was introduced and the temperature was raised to 300 °C. 0.50 mmol of tris(trimethylsilyl)arsenic was injected, and the reaction was allowed to proceed for 30 min. The temperature was then lowered to 280 °C, and InAs clusters were injected to obtain InAs quantum dots with a first exciton absorption peak at 860 nm. After washing, these quantum dots were dispersed in n-hexane for later use.

[0070] Preparation of InAs clusters: 1 mmol of indium acetate, 3 mmol of oleic acid and 5 mL of octadecene were degassed at 120 °C for 1 h, then cooled to room temperature, and 0.50 mmol of tris(trimethylsilyl)arsenic was injected. After stirring for 1 min, InAs clusters were obtained and set aside for later use.

[0071] A mixed solution of 2.2 mmol zinc acetate, 3 mL octadecene, and 3 mL oleylamine was placed in a three-necked flask and degassed at 120 °C for 30 min. Then, washed InAs quantum dots were injected, followed by 0.3 mmol diethylzinc. The temperature was raised to 240 °C, and then 0.85 mmol TOP-Se and 0.8 mmol zinc stearate were injected. The reaction was carried out for 60 min, and the temperature was raised to 280 °C and held for 30 min. The temperature was then raised to 290 °C, and 1.20 mmol TOP-Se and 0.80 mmol zinc stearate were injected, holding for 30 min. The temperature was then raised to 300 °C, and 1.55 mmol TOP-Se and 0.80 mmol zinc stearate were injected, holding for 30 min to grow a ZnSe shell epitaxially. Finally, the temperature was raised to 310 °C, and 0.40 mmol zinc stearate and 0.95 mmol TOP-S were injected, reacting for 30 min to grow a ZnS shell. InAs / ZnSe / ZnS quantum dots were obtained.

[0072] Test

[0073] 1. The structure and morphology of the quantum dots obtained in step S1 of Example 1 and the quantum dots prepared in Examples 1-4 were tested. The test results are shown in Figures 1-4.

[0074] As shown in Figure 1, an InP core with an absorption peak at 440 nm was first synthesized. To ensure the stability of InP, a thin ZnSe shell was epitaxially grown on the core surface. This was to prevent Oswald ripening of the small quantum dots at high temperatures. Next, a mixed solution of TOP-Se and TOP-S in different proportions was sequentially injected at gradually increasing temperatures to form a ZnSeS inner shell with a gradient composition. This reduced the lattice strain between the ZnSe and ZnS shells. Based on the above method, the morphology control of InP core-shell quantum dots by different zinc precursors was investigated.

[0075] As shown in Figure 2, when zinc stearate was used as the sole zinc precursor for the synthesis of InP / ZnSe / ZnSeS / ZnS core-shell quantum dots, the resulting quantum dots exhibited an irregular multi-legged morphology. The quantum yield and full width at half maximum (FWHM) of this sample were 25% and 35 nm, respectively.

[0076] As shown in Figure 3, InP / ZnSe / ZnSeS / ZnS core-shell quantum dots were synthesized using zinc stearate and zinc acetate as zinc precursors. Although the shell growth rate could be effectively controlled, the morphology of the final synthesized InP / ZnSe / ZnSeS / ZnS nanoparticles remained irregular. The quantum yield of the final sample was 80%, and the fluorescence half-width was 34 nm. It is reasonable to infer that although the introduction of short-chain ligands promotes the substitution of carboxylic acid ligands on the quantum dot surface and reduces the ligand density, some long-chain carboxylic acid ligands may still remain. This phenomenon leads to the selective growth of the ZnSeS shell during the reaction, ultimately forming an irregular morphology.

[0077] Based on the aforementioned zinc precursor, the InP surface was activated by introducing diethylzinc to remove excess carboxylic acid ligands, while zinc stearate and zinc acetate were used as zinc precursors to control the growth rate. The resulting green luminescent InP / ZnSe / ZnSeS / ZnS quantum dots exhibited a quantum yield exceeding 90% and a full width at half maximum (FWHM) of 35 nm. As shown in Figure 4, the scanning transmission electron microscopy (STEM) image reveals that the synthesized InP / ZnSe / ZnSeS / ZnS quantum dots have a regular morphology and uniform size, with an average size of approximately 9.5 nm. These results indicate that the introduction of diethylzinc promoted the growth of InP / ZnSeS / ZnSeS quantum dots within the ZnSe inner shell. thin The adsorption and desorption of long-chain carboxylic acid ligands on the surface promote the uniform growth of InP / ZnSe / ZnSeS / ZnS quantum dots, resulting in quantum dots with controllable morphology.

[0078] 2. Universality verification: The structure and morphology of the quantum dots prepared in Examples 5-7 were tested. The test results are shown in Figures 5-7.

[0079] As shown in Figure 5, for the yellow luminescent quantum dots, the final photoluminescence peak is located at 570 nm, with a full width at half maximum (FWHM) of 34 nm and a quantum yield as high as 92%. Transmission electron microscopy (TEM) images show that the yellow InP / ZnSe / ZnS quantum dots treated with diethylzinc exhibit regular morphology.

[0080] As shown in Figure 6, the photoluminescence peak of the synthesized red luminescent InP / ZnSe / ZnS quantum dots is 610 nm, the full width at half maximum (FWHM) is 42 nm, and the quantum yield is as high as 90%. The final morphology of the synthesized red luminescent InP / ZnSe / ZnS quantum dots shows consistent results, and regular red quantum dots were also obtained after treatment with diethylzinc.

[0081] As shown in Figure 7, the synthesized InAs / ZnSe quantum dots treated with diethylzinc yielded results consistent with those of InP. The InAs / ZnSe quantum dots treated with diethylzinc exhibited regular morphology, uniform size, and a quantum yield as high as 100%. In contrast, the untreated InAs / ZnSe quantum dots had irregular morphology and a quantum yield of only 62%.

[0082] In summary, the method of controlling the morphology of quantum dots by activating the surface of quantum dots with diethylzinc has wide applicability.

[0083] Therefore, the present invention employs the above-mentioned method for synthesizing core-shell quantum dots based on surface activation to obtain quantum dots with controllable morphology and size distribution, which are suitable for industrial production and have wide applicability.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for synthesizing core-shell quantum dots based on surface activation, characterized in that, Includes the following steps: S1. Prepare quantum dot cores; S2. Mix zinc precursor, octadecene, and oleylamine in a specific ratio and degas the mixture, then inject the resulting solution into the quantum dot cores obtained in S1. Add a metal alkyl compound and heat to 230-250℃; S3. Inject solution A and zinc stearate, react, heat to 275-285℃, hold, then heat to 286-295℃, inject solution B and zinc stearate, hold, then heat to 296-305℃, inject solution C and zinc stearate, hold, then heat to 306-315℃, and inject solution D. The inner shell is grown by incubating with zinc stearate and heat treatment, followed by the injection of zinc stearate and TOP-S, and the reaction is carried out to grow a ZnS shell, resulting in InP core-shell quantum dots with regular morphology; in S2, the zinc precursor is zinc acetate, and the metal alkyl compound is a zinc-containing metal alkyl compound, specifically one or more of dimethyl zinc, diethyl zinc, diisopropyl zinc, and dibutyl zinc; in S3, solutions A, B, C, and D are all mixed solutions of TOP-Se and TOP-S.

2. The method for synthesizing core-shell quantum dots based on surface activation according to claim 1, characterized in that, S1 specifically involves: mixing indium acetate, zinc acetate, hexadecanoic acid, and octadecene in a specific ratio and subjecting the mixture to a degassing reaction. Then, nitrogen gas is introduced and the mixture is cooled to room temperature. Tris(trimethylsilyl)phosphine dissolved in trioctylphosphine is injected, and the mixture is heated to obtain an InP core. Zinc stearate and TOP-Se are then injected to obtain the quantum dot core. The ratio of indium acetate, zinc acetate, hexadecanoic acid, octadecene, trioctylphosphine, tris(trimethylsilyl)phosphine, zinc stearate, and TOP-Se is 0.3 mmol. 0.15mmol:1.05mmol:10mL:2mL:0.20mmol:1mmol:0.6mmol; the degassing reaction was carried out at 120℃ for 2h; the InP core was obtained by heating to 270℃ and reacting for 5min; the quantum dot core was obtained by washing after reacting the zinc stearate and TOP-Se at 270℃ for 30min.

3. The method for synthesizing core-shell quantum dots based on surface activation according to claim 1, characterized in that, In S2, the ratio of the zinc precursor, the octadecene, and the oleylamine is 2.2 mmol: 3 mL: 3 mL, and the degassing reaction is carried out at 120 °C for 30 min.

4. The method for synthesizing core-shell quantum dots based on surface activation according to claim 1, characterized in that, In S2, the molar ratio of the added metal alkyl compound to the quantum dot core is 150-200:

1.

5. The method for synthesizing core-shell quantum dots based on surface activation according to claim 1, characterized in that, In S3, the ratio of the amount of TOP-Se and TOP-S mixture in solution A and solution B is Se / S = 1-4:1; the ratio of the amount of TOP-Se and TOP-S mixture in solution C and solution D is Se / S = 1:1-5.

6. The method for synthesizing core-shell quantum dots based on surface activation according to claim 1, characterized in that, In S3, the injection solution A and zinc stearate are specifically configured such that the ratio of solution A to zinc stearate is 0.85 mmol: 0.8 mmol; the injection solution B and zinc stearate are specifically configured such that the ratio of solution B to zinc stearate is 1.2 mmol: 0.8 mmol; the injection solution C and zinc stearate are specifically configured such that the ratio of solution C to zinc stearate is 1.55 mmol: 0.8 mmol; and the injection solution D and zinc stearate are specifically configured such that the ratio of solution D to zinc stearate is 0.95 mmol: 0.4 mmol.

7. The method for synthesizing core-shell quantum dots based on surface activation according to claim 1, characterized in that, In S3, the re-injection of zinc stearate and TOP-S specifically means that the molar ratio of zinc stearate and TOP-S is 0.4:0.

95.

8. The method for synthesizing core-shell quantum dots based on surface activation according to claim 1, characterized in that, In S3, both the reaction and the heat preservation time are 0-2 hours.

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