Preparation method and application of ZnSeTe-based core / shell structure quantum dot

Abstract

The invention belongs to the field of photoelectric material application, and particularly relates to a preparation method and application of a ZnSeTe-based core / shell structure quantum dot, and the preparation method specifically comprises the following steps: mixing a core Se precursor solution, a core Te precursor solution and a core Zn precursor solution to grow a ZnSeTe quantum dot initial core; adding a ZnSeTe core epitaxial growth stock solution to obtain a large-particle-size ZnSeTe quantum dot core; then adding a ZnSe shell layer epitaxial growth stock solution and a ZnS shell layer epitaxial growth stock solution to finally obtain a ZnSeTe-based core / shell structure quantum dot solution; then, a polar anti-solvent containing ammonium halide is added for post-treatment, and the ZnSeTe-based core / shell structure quantum dot is obtained. According to the invention, the large-particle-size ZnSeTe quantum dot core is generated through a homogeneous epitaxial growth process without introducing lattice mismatch dislocation, and the formed large-particle-size ZnSeTe quantum dot core can realize blue light emission at the wave band of 445-470nm only by epitaxially growing a relatively thin ZnSe shell layer.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic materials applications, specifically relating to a method for preparing ZnSeTe-based core / shell quantum dots and their applications. Background Technology

[0002] Colloidal quantum dots (CQDs) are promising display and lighting materials due to their unique tunable emission wavelength, solution processability, narrow fluorescence full width at half maximum (FWHM), high photoluminescence quantum yield (PLQY), and good photochemical stability. Currently, the most maturely developed quantum dots are those containing heavy metals such as cadmium, but their applications are limited. Furthermore, among quantum dot materials emitting red, green, and blue primary colors, blue-emitting quantum dots lag behind red and green quantum dots in both preparation methods and luminescent performance. In the field of non-toxic blue-emitting quantum dots, ZnSeTe quantum dots, with their advantages in bandgap engineering for size and composition control, are considered ideal candidates for achieving blue light emission in the 445-470 nm wavelength range. Currently, while blue light emission from ZnSeTe-based quantum dots can be achieved by increasing the Te:Se ratio in the ZnSeTe core or by growing a thick ZnSe shell, the resulting quantum dots are still limited by the interrelationship between composition, defects, and performance. The former, due to the high chemical reactivity and large atomic radius of Te, leads to increased defects, decreased stability, and broadened emission peak width at half maximum (FWHM) in high-Te ZnSeTe quantum dots. The latter, where the ZnSe shell thickness exceeds a critical thickness, easily leads to mismatch dislocations at the ZnSeTe / ZnSe interface, increased defects, and reduced luminescence intensity. Therefore, there is an urgent need to design and grow ZnSeTe-based core / shell quantum dots with novel quantum structures.

[0003] The luminescence properties of colloidal quantum dots depend not only on their material and structure but also on their surface chemical state. Regulating the surface chemistry of quantum dots can also help improve their luminescence performance. Since the surface chemistry of quantum dots is mainly determined by the precursors used in their growth stage, current methods for regulating the surface chemistry of quantum dots are primarily conducted during this stage. However, an important aspect overlooked by existing methods is that in the post-processing stage after quantum dot growth, the repeated interaction of solvents and antisolvents can lead to partial detachment of ligands from the quantum dot surface. This undoubtedly deteriorates the performance of quantum dots and hinders their applications in phosphors, biosensor imaging, and optoelectronic devices. Therefore, there is an urgent need to develop different quantum dot post-processing methods.

[0004] Based on the above background, this invention proposes a method for preparing blue ZnSeTe-based quantum dots with novel quantum dot structure and high luminescence performance in the 445-470nm band. Summary of the Invention

[0005] To address the problems of increased internal defects, decreased stability, and broadened emission peak width at half maximum (FWHM) in current ZnSeTe quantum dots, this invention provides a method for preparing ZnSeTe-based core / shell structured quantum dots and their applications.

[0006] This invention is achieved through the following technical solution: a method for preparing ZnSeTe-based core / shell quantum dots, wherein steps S1 to S4 of the preparation method are carried out under an inert atmosphere, and include the following steps: S1. The Se precursor solution and the Te precursor solution are mixed and injected into a container containing the Zn precursor solution by hot injection, and the initial ZnSeTe quantum dot nuclei are grown at a high temperature of 280~300℃. The Se precursor solution is prepared from selenium powder and diphenylphosphine; the Te precursor solution is prepared from tellurium powder, tri-n-octylphosphine, and oleylamine; the Zn precursor solution is prepared from zinc source, oleic acid, oleylamine, and octadecene. S2. After the initial ZnSeTe quantum dot nuclei have grown uniformly, the ZnSeTe nuclei epitaxial growth solution is injected dropwise into the container at 280~300℃ to react, resulting in a solution of large-particle-size ZnSeTe quantum dot nuclei with an average particle size greater than 5nm. The ZnSeTe nuclei epitaxial growth solution is prepared from selenium powder, a Te precursor solution, a zinc source, oleic acid, octadecene, and tri-n-octylphosphine. S3. After the large-particle-size ZnSeTe quantum dot nuclei have grown, the solution of the large-particle-size ZnSeTe quantum dot nuclei is heated to 300~330℃, and then the ZnSe shell epitaxial growth solution is injected into the solution of the large-particle-size ZnSeTe quantum dot nuclei to react and complete the growth of a ZnSe shell layer with a thickness of less than 2nm; the ZnSe shell epitaxial growth solution is prepared from zinc source, oleic acid, oleylamine, octadecene, and shell Se precursor solution, and the shell Se precursor solution is prepared from selenium powder and tri-n-octylphosphine; S4. After the ZnSe shell growth is complete, the ZnS shell epitaxial growth solution is injected into the container and kept at a constant temperature to complete the ZnS shell growth, finally obtaining a ZnSeTe-based core / shell quantum dot solution; the ZnS shell epitaxial growth solution is prepared from zinc source, oleic acid, oleylamine, octadecene, and shell S precursor solution, and the shell S precursor solution is prepared from sulfur powder and tri-n-octylphosphine; S5, ZnSeTe-based core / shell quantum dot solution was naturally cooled to room temperature, and then a polar antisolvent containing ammonium halide was added for post-treatment to obtain ZnSeTe-based core / shell quantum dots.

[0007] As a further explanation of the technical solution of the present invention, the octadecene in the nuclear Zn precursor solution, ZnSe shell epitaxial growth solution and ZnS shell epitaxial growth solution can be replaced with trioctylamine or a mixture of octadecene and trioctylamine; the zinc source includes anhydrous zinc acetate, zinc stearate, or a complex formed by mixing dodecylphosphonic acid and zinc oxide.

[0008] As a further explanation of the technical solution of this invention, when growing the initial nuclei and large-particle-size ZnSeTe quantum dots, the ratio of the amount of tellurium powder to the amount of selenium powder in the container is the same and is 0.01~0.03:1; when growing the initial nuclei of ZnSeTe quantum dots, the ratio of the amount of zinc source to the total amount of tellurium powder and selenium powder in the container is 1.5~3:1; when growing the ZnSe shell, the ratio of the amount of zinc source to selenium powder in the ZnSe shell epitaxial growth solution is 1~1.5:1, and the volume ratio of oleic acid to oleylamine is 1.5~3:1; when growing the ZnS shell, the ratio of the amount of zinc source to sulfur powder in the ZnS shell epitaxial growth solution is 1~1.5:1, and the volume ratio of oleic acid to oleylamine is 1.5~3:1.

[0009] As a further explanation of the technical solution of the present invention, the preparation method of the nuclear Se precursor solution is as follows: selenium powder is added to diphenylphosphine, heated to 80°C under an inert atmosphere and stirred until dissolved to obtain the nuclear Se precursor solution; the preparation method of the nuclear Te precursor solution is as follows: tellurium powder is taken, tri-n-octylphosphine and oleylamine are added, and stirred at room temperature under an inert atmosphere until dissolved to obtain the nuclear Te precursor solution; the preparation method of the nuclear Zn precursor solution is as follows: zinc source is taken, oleic acid, oleylamine and octadecene are added, vacuum is first drawn and inert gas is filled at room temperature, and then the temperature is raised to 100~150°C and vacuum is drawn to obtain the nuclear Zn precursor solution.

[0010] As a further explanation of the technical solution of the present invention, the preparation method of the ZnSeTe core epitaxial growth stock solution is as follows: take a zinc source, add selenium powder, core Te precursor solution, oleic acid, octadecene, and tri-n-octylphosphine, first evacuate and fill with inert gas at room temperature, then heat to 100~150℃ and evacuate again to obtain the ZnSeTe core epitaxial growth stock solution.

[0011] As a further explanation of the technical solution of the present invention, the preparation method of the ZnSe shell epitaxial growth stock solution is as follows: take a zinc source, add shell Se precursor solution, oleic acid, oleylamine and octadecene, first evacuate and fill with inert gas at room temperature, then heat to 100~150℃ and evacuate again to obtain ZnSe shell epitaxial growth stock solution; wherein the preparation method of shell Se precursor solution is as follows: take selenium powder, add tri-n-octylphosphine, stir at room temperature under an inert atmosphere until dissolved to obtain shell Se precursor solution.

[0012] As a further explanation of the technical solution of the present invention, the preparation method of the ZnS shell epitaxial growth solution is as follows: take a zinc source, add shell S precursor solution, oleic acid, oleylamine and octadecene, first evacuate and fill with inert gas at room temperature, then heat to 100~150℃ and evacuate again to obtain ZnS shell epitaxial growth solution; wherein the preparation method of shell S precursor solution is as follows: take sulfur powder, add tri-n-octylphosphine, stir at room temperature under an inert atmosphere until dissolved to obtain shell S precursor solution.

[0013] As a further explanation of the technical solution of the present invention, the specific steps of post-processing in step S5 are as follows: (1) Take a ZnSeTe-based core / shell quantum dot solution into a centrifuge tube, add a polar antisolvent containing ammonium halide and centrifuge; (2) After centrifugation in step (1), discard the supernatant, add a non-polar solvent to the precipitate to dissolve it, and then centrifuge it. (3) After centrifugation in step (2), transfer the supernatant to another centrifuge tube, add a polar antisolvent containing ammonium halide again, and then centrifuge. (4) After step (3) is completed, pour off the supernatant, dry the precipitate in a vacuum or inert environment, or blow it dry with an inert gas at room temperature, and add a non-polar solvent to obtain ZnSeTe-based core / shell quantum dots.

[0014] As a further explanation of the technical solution of the present invention, the preparation method of the polar antisolvent containing ammonium halide is as follows: take any one or more of NH4F, NH4Cl, NH4Br and NH4I, add a polar solvent, stir at room temperature until dissolved, and obtain the polar antisolvent containing ammonium halide.

[0015] This invention further provides a method for preparing ZnSeTe-based core / shell quantum dots and its application as a quantum dot material emitting blue light in the 445-470nm wavelength band.

[0016] The method for preparing ZnSeTe-based core / shell quantum dots and its application provided by this invention have the following advantages compared with existing technologies: 1. Traditional methods achieve blue light emission in the 445-470nm wavelength range by heteroepitaxially growing a thick ZnSe shell on a small-sized ZnSeTe core (small core, thick shell structure). During heteroepitaxial growth, the thick ZnSe layer easily exceeds the critical thickness, leading to interface defects and reducing the luminescence performance of the quantum dots. This invention, however, generates large-particle-size ZnSeTe quantum dot cores through a homoepitaxial growth process that does not introduce lattice mismatch dislocations. The resulting large-particle-size ZnSeTe quantum dot cores only require epitaxial growth of a thinner ZnSe shell to achieve blue light emission in this wavelength range (large core, thin shell quantum dot). This avoids the generation of numerous lattice mismatch dislocations at the interface due to the ZnSe shell thickness exceeding its coherent growth critical thickness, thereby effectively improving the luminescence intensity of the quantum dots.

[0017] 2. In addition to reducing interface defects by homoepitaxially growing large-particle-size ZnSeTe quantum dot cores and heteroepitaxially growing thin ZnSe shells, this invention also introduces ammonium halide molecules with strong defect passivation capabilities into the polar antisolvent during the post-synthesis treatment stage. These molecules can bond with undercoordinated atoms on the quantum dot surface caused by the steric hindrance effect or shedding of the original long-chain ligands, thereby passivating the surface defects of the quantum dots and further improving their luminescence performance. This invention can prepare large-core thin-shell ZnSeTe core / shell structure quantum dots with high luminescence brightness and narrow fluorescence half-width (<30nm) in the 445-470nm blue light band. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The fluorescence emission spectra of three different quantum dots are shown in the comparison diagrams of the small-core thick-shell type in Comparative Example 2, the high-Te component type in Comparative Example 3, and the large-core thin-shell type in Example 1.

[0021] Figure 2 The transmission electron microscope (scale bars in the figure are all 20 nm) and corresponding quantum dot particle size statistics are shown for Comparative Example 2 after the growth of small ZnSeTe core, ZnSe intermediate shell and ZnS outer shell (i.e. small core thick shell quantum dots).

[0022] Figure 3The graph shows the transmission electron microscope (scale bars are all 20 nm) and corresponding quantum dot particle size statistics of the high-Te quantum dots in Comparative Example 3 after the growth of the high-Te ZnSeTe core, ZnSe intermediate shell and ZnS outer shell (i.e., high-Te quantum dots).

[0023] Figure 4 The transmission electron microscope (scale bars are all 20 nm) and corresponding quantum dot particle size statistics are shown for the large-core thin-shell quantum dots of Example 1 after the growth of large ZnSeTe core, ZnSe intermediate shell and ZnS outer shell (i.e. large-core thin-shell quantum dots).

[0024] Figure 5 The normalized fluorescence emission spectra are compared for three types of large-core thin-shell quantum dots with different ZnSeTe core sizes.

[0025] Figure 6 The images show a comparison of the fluorescence emission spectra of the quantum dots prepared in Examples 1, 3, 4, and 5 with those in Comparative Example 1.

[0026] Figure 7 The images show the quantum dots prepared in Examples 1, 4 and Comparative Example 1 under UV lamp illumination. Detailed Implementation

[0027] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0028] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0029] This invention provides a specific embodiment of a method for preparing ZnSeTe-based core / shell quantum dots. Steps S1 to S4 of the preparation method are performed under an inert atmosphere and include the following steps: S1. The nuclear Se precursor solution (DPP-Se solution) and the nuclear Te precursor solution (TOP / OLA-Te solution) are mixed and injected into a container containing the nuclear Zn precursor solution by hot injection, and ZnSeTe quantum dot initial nuclei are grown at a high temperature of 280~300℃. The nuclear Se precursor solution is prepared from selenium powder (Se) and diphenylphosphine (DPP); the nuclear Te precursor solution is prepared from tellurium powder (Te), tri-n-octylphosphine (TOP), and oleylamine (OLA); the nuclear Zn precursor solution is prepared from zinc source, oleic acid, oleylamine, and octadecene. S2. After the initial ZnSeTe quantum dot nuclei have grown uniformly, the ZnSeTe nuclei epitaxial growth solution is injected dropwise into the container at 280~300℃ to react, resulting in a solution of large-particle-size ZnSeTe quantum dot nuclei with an average particle size greater than 5nm. The ZnSeTe nuclei epitaxial growth solution is prepared from selenium powder, a Te precursor solution, a zinc source, oleic acid, octadecene, and tri-n-octylphosphine. S3. After the large-particle-size ZnSeTe quantum dot nuclei have grown, the solution of the large-particle-size ZnSeTe quantum dot nuclei is heated to 300~330℃, and then the ZnSe shell epitaxial growth solution is injected into the solution of the large-particle-size ZnSeTe quantum dot nuclei to react and complete the growth of a ZnSe shell layer with a thickness of less than 2nm; the ZnSe shell epitaxial growth solution is prepared from zinc source, oleic acid, oleylamine, octadecene, and shell Se precursor solution, and the shell Se precursor solution is prepared from selenium powder and tri-n-octylphosphine; S4. After the ZnSe shell growth is complete, the ZnS shell epitaxial growth solution is injected into the container and kept at a constant temperature to complete the ZnS shell growth, finally obtaining a ZnSeTe-based core / shell quantum dot solution; the ZnS shell epitaxial growth solution is prepared from zinc source, oleic acid, oleylamine, octadecene, and shell S precursor solution, and the shell S precursor solution is prepared from sulfur powder and tri-n-octylphosphine; S5, ZnSeTe-based core / shell quantum dot solution was naturally cooled to room temperature, and then a polar antisolvent containing ammonium halide was added for post-treatment to obtain ZnSeTe-based core / shell quantum dots.

[0030] The purpose of the inert atmosphere in this invention is to isolate the precursor solution and epitaxial growth solution from air. Common inert gases such as nitrogen (N2) and argon (Ar) can be used.

[0031] In one example provided by the present invention, the octadecene in the nuclear Zn precursor solution, ZnSe shell epitaxial growth solution and ZnS shell epitaxial growth solution can be replaced with trioctylamine or a mixture of octadecene and trioctylamine; the zinc source includes anhydrous zinc acetate, zinc stearate, or a complex formed by mixing dodecylphosphonic acid and zinc oxide.

[0032] In laboratory conditions, in step S2, the ZnSeTe core epitaxial growth stock solution is injected dropwise into the container at a rate of 7-9 mL / h using a peristaltic pump, and the reaction is allowed to proceed for 10-30 min after complete injection.

[0033] In step S3, the ZnSe shell epitaxial growth solution is injected into the container at a rate of 7-9 mL / h using a peristaltic pump, and the reaction is carried out for 10-30 min after complete injection.

[0034] In step S4, the ZnS shell epitaxial growth solution is injected into the container at a rate of 7-9 mL / h using a peristaltic pump, and the reaction is carried out for 5-20 minutes after complete injection.

[0035] Due to the high chemical reactivity, large atomic radius, and sensitivity to oxygen of Te, the ratio of tellurium powder to selenium powder in the container is the same (0.01–0.03:1) when growing initial nuclei and large-particle-size ZnSeTe quantum dots; when growing initial nuclei, the ratio of zinc source to total tellurium and selenium powder in the container is 1.5–3:1; when growing ZnSe shells, the ratio of zinc source to selenium powder in the ZnSe shell epitaxial growth solution is 1–1.5:1, and the volume ratio of oleic acid to oleylamine is 1.5–3:1; when growing ZnS shells, the ratio of zinc source to sulfur powder in the ZnS shell epitaxial growth solution is 1–1.5:1, and the volume ratio of oleic acid to oleylamine is 1.5–3:1. In this invention, a precursor solution with low Te content is used to prepare ZnSeTe quantum dot cores with large particle size and low Te composition, so as to avoid problems such as increased defects, decreased stability and broadened emission half-width (FWHM) of ZnSeTe-based quantum dots caused by high Te content.

[0036] In one example provided by the present invention, the preparation method of the nuclear Se precursor solution is as follows: selenium powder is added to diphenylphosphine, heated to 80°C under an inert atmosphere and stirred until dissolved to obtain the nuclear Se precursor solution; the preparation method of the nuclear Te precursor solution is as follows: tellurium powder is taken, tri-n-octylphosphine and oleylamine are added, and stirred at room temperature under an inert atmosphere until dissolved to obtain the nuclear Te precursor solution; the preparation method of the nuclear Zn precursor solution is as follows: zinc source is taken, oleic acid, oleylamine and octadecene are added, vacuum is first drawn and inert gas is filled at room temperature, and then the temperature is raised to 100~150°C and vacuum is drawn to obtain the nuclear Zn precursor solution.

[0037] In one example provided by the present invention, the preparation method of the ZnSeTe core epitaxial growth stock solution is as follows: take a zinc source, add selenium powder, core Te precursor solution, oleic acid, octadecene, and tri-n-octylphosphine, first evacuate and fill with inert gas at room temperature, then heat to 100~150℃ and evacuate again to obtain the ZnSeTe core epitaxial growth stock solution.

[0038] In one example provided by the present invention, the preparation method of the ZnSe shell epitaxial growth stock solution is as follows: take a zinc source, add shell Se precursor solution, oleic acid, oleylamine and octadecene, first evacuate and fill with inert gas at room temperature, then heat to 100~150℃ and evacuate again to obtain ZnSe shell epitaxial growth stock solution; wherein the preparation method of shell Se precursor solution is as follows: take selenium powder, add tri-n-octylphosphine, stir at room temperature under an inert atmosphere until dissolved to obtain shell Se precursor solution (TOP-Se solution).

[0039] In one example provided by the present invention, the preparation method of the ZnS shell epitaxial growth stock solution is as follows: take a zinc source, add shell S precursor solution, oleic acid, oleylamine and octadecene, first evacuate and fill with inert gas at room temperature, then heat to 100~150℃ and evacuate again to obtain ZnS shell epitaxial growth stock solution; wherein the preparation method of shell S precursor solution is as follows: take sulfur powder, add tri-n-octylphosphine, stir at room temperature under an inert atmosphere until dissolved to obtain shell S precursor solution (TOP-S solution).

[0040] In one example provided by this invention, the specific steps of post-processing in step S5 are as follows: (1) Take a ZnSeTe-based core / shell quantum dot solution into a centrifuge tube, add a polar antisolvent containing ammonium halide and centrifuge; (2) After centrifugation in step (1), discard the supernatant, add a non-polar solvent to the precipitate to dissolve it, and then centrifuge it. (3) After centrifugation in step (2), transfer the supernatant to another centrifuge tube, add a polar antisolvent containing ammonium halide again, and then centrifuge. (4) After step (3) is completed, pour off the supernatant, dry the precipitate in a vacuum or inert environment, or blow it dry with an inert gas at room temperature, and add a non-polar solvent to obtain ZnSeTe-based core / shell quantum dots.

[0041] It should be noted that, in the post-processing step S5 of this invention, apart from the step of drying or blowing the precipitate, the environment of the reaction system can be atmospheric or inert atmosphere.

[0042] Specifically, the preparation method of the ammonium halide-containing polar antisolvent is as follows: Take any one or more of NH4F, NH4Cl, NH4Br, and NH4I, add a polar solvent, and stir at room temperature until dissolved to obtain the ammonium halide-containing polar antisolvent. The polar solvent can be anhydrous ethanol and / or acetone. Specifically, the concentration of the ammonium halide-containing polar antisolvent is 0.01~0.04 mmol / mL.

[0043] In step S5, during post-processing, the added non-polar solvent is n-octane, n-hexane, etc. Specifically, the centrifugation process involves centrifuging 1-3 times at 3000-5000 rpm, with each centrifugation lasting 5-10 minutes.

[0044] This invention also provides a method for preparing ZnSeTe-based core / shell quantum dots and its application as a quantum dot material emitting blue light in the 445-470nm wavelength band.

[0045] The specific embodiments of the present invention will be described in detail below.

[0046] Example 1

[0047] This embodiment provides a novel method for synthesizing large-core thin-shell ZnSeTe-based core / shell quantum dots (referred to as large-core thin-shell quantum dots) and for preparing quantum dots using an anhydrous ethanol solution containing ammonium fluoride (NH4F) for post-processing. The specific operation steps are as follows: I. Preparation of nuclear precursor solution, shell precursor solution, nuclear epitaxial growth solution, and shell epitaxial growth solution: 1) Preparation of nuclear Se precursor solution (DPP-Se solution): Take 2 mmol of selenium powder, add 2 mL of diphenylphosphine (DPP), heat to 80 °C under N2 atmosphere and stir until dissolved to obtain 1 M DPP-Se solution (the molar concentration of Se is 0.01 M). 2) Preparation of nuclear Te precursor solution (TOP / OLA-Te solution): Take 0.04 mmol of tellurium powder, add 1 mL of tri-n-octylphosphine (TOP) and 3 mL of oleylamine (OLA), stir at room temperature under N2 atmosphere until dissolved to obtain 0.01 M TOP / OLA-Te solution (Te molar concentration is 0.01 M). 3) Preparation of shell Se precursor solution (TOP-Se solution): Take 6 mmol of selenium powder, add 6 mL of tri-n-octylphosphine, stir at room temperature under N2 atmosphere until dissolved, to obtain 1 M TOP-Se solution (the molar concentration of Se is 0.01 M). 4) Preparation of shell S precursor solution (TOP-S solution): Take 6 mmol of sulfur powder, add 6 mL of tri-n-octylphosphine, stir at room temperature under N2 atmosphere until dissolved to obtain 1 M TOP-S solution (the molar concentration of S is 0.01 M). 5) Preparation of nuclear Zn precursor solution: Take 1 mmol of anhydrous zinc acetate into a three-necked flask ①, add 7.5 mL of octadecene, 1 mL of oleylamine and 1 mL of oleic acid, and first perform vacuuming / nitrogen purging three times at room temperature under N2 atmosphere, then raise the temperature to 140℃ and vacuum for 1 h to obtain a light yellow solution, which is the nuclear Zn precursor solution. 6) Preparation of ZnSeTe core epitaxial growth stock solution: Take 3 mmol of anhydrous zinc acetate into a three-necked flask ②, add 1.5 mmol of selenium powder, 3 mL of TOP / OLA-Te solution, 1.5 mL of oleic acid, 1.5 mL of octadecene, and 8.5 mL of tri-n-octylphosphine. First, perform vacuuming / nitrogen purging cycles three times at room temperature under N2 atmosphere, then heat it to 120℃ and perform vacuuming again to obtain the ZnSeTe core epitaxial growth stock solution; 7) Preparation of ZnSe shell epitaxial growth stock solution: Take 7.2 mmol of anhydrous zinc acetate into a three-necked flask ③, add 6 mL of TOP-Se solution, 14.4 mL of oleic acid, 7.2 mL of oleylamine and 7.2 mL of octadecene, first perform vacuuming / nitrogen purging cycle three times at room temperature, then heat it to 120℃ and perform vacuuming again to obtain ZnSe shell epitaxial growth stock solution; 8) Preparation of ZnS shell epitaxial growth stock solution: Take 7.2 mmol of anhydrous zinc acetate into a three-necked flask ④, add 6 mL of TOP-S solution, 14.4 mL of oleic acid, 7.2 mL of oleylamine and 7.2 mL of octadecene, first perform vacuuming / nitrogen purging cycle three times at room temperature, then heat it to 120℃ and perform vacuuming again to obtain ZnS shell epitaxial growth stock solution.

[0048] II. Preparation of initial ZnSeTe quantum dot nuclei: 9.5 mL of the nucleus Zn precursor solution was heated to 280 °C under a N2 atmosphere. After the temperature stabilized, 0.5 mL of DPP-Se solution and 1 mL of TOP / OLA-Te solution were rapidly injected into a three-necked flask ① and reacted for 1 h to obtain the initial ZnSeTe quantum dot nuclei.

[0049] III. Preparation of large-particle-size ZnSeTe quantum dot nuclei: After the initial ZnSeTe quantum dot nuclei have grown uniformly, 9 mL of the ZnSeTe nuclei epitaxial growth solution is slowly injected into a three-necked flask ① at a rate of 7 mL / h using a peristaltic pump. After complete injection, the reaction is carried out for 15 min to obtain a solution of large-particle-size ZnSeTe quantum dot nuclei (referred to as large ZnSeTe nuclei) with an average particle size greater than 5 nm.

[0050] IV. Preparation of ZnSeTe / ZnSe quantum dots: After the large-particle-size ZnSeTe quantum dot cores have grown uniformly, the temperature is raised to 300℃. After the temperature stabilizes, 23.2 mL of ZnSe shell epitaxial growth solution is slowly injected into a three-necked flask ① at a rate of 9 mL / h using a peristaltic pump. After complete injection, the reaction is carried out for 15 min to obtain ZnSeTe / ZnSe quantum dots.

[0051] V. Preparation of ZnSeTe-based core / shell quantum dots: After the ZnSe shell layer has grown uniformly, 34.8 mL of ZnS shell epitaxial growth stock solution was slowly injected into a three-necked flask ① at a rate of 9 mL / h using a peristaltic pump. After complete injection, the reaction was carried out for 15 min to obtain ZnSeTe-based core / shell quantum dot stock solution (i.e., large core thin shell quantum dot stock solution). VI. Post-treatment using an anhydrous ethanol solution containing ammonium fluoride: (1) Take the ZnSeTe-based core / shell quantum dot stock solution into a centrifuge tube, add anhydrous ethanol solution containing ammonium fluoride (NH4F), and centrifuge. Specifically: A. Take 0.2 mmol of NH4F powder, add 10 mL of anhydrous ethanol solution, and stir at room temperature until dissolved to obtain 0.02 M NH4F-anhydrous ethanol solution; B. Take 1 mL of ZnSeTe-based core / shell quantum dot stock solution into a centrifuge tube, add 4 mL of NH4F-anhydrous ethanol solution, and centrifuge at 5000 r / min for 6 min. (2) After the treatment in step (1), discard the supernatant, add 1 mL of n-octane to the centrifuge tube to dissolve the precipitate, and centrifuge at 5000 r / min for 6 min. (3) After the treatment in step (2), transfer the supernatant to another centrifuge tube, add 4 mL of NH4F-anhydrous ethanol solution, and centrifuge at 5000 r / min for 6 min. (4) After step (3) is completed, the precipitate is dried in a nitrogen atmosphere and dissolved in an appropriate amount of n-octane to obtain ZnSeTe-based core / shell structure quantum dots (i.e., large core thin shell quantum dots).

[0052] Example 2

[0053] This embodiment provides a novel method for synthesizing large-core thin-shell ZnSeTe-based core / shell quantum dots (i.e., large-core thin-shell quantum dots) and for post-processing with an anhydrous ethanol solution containing ammonium fluoride (NH4F), which is basically the same as that in Example 1. The difference is that in step three, 11.25 mL of ZnSeTe core epitaxial growth stock solution is added to a three-necked flask ①.

[0054] Example 3

[0055] This embodiment provides a novel method for synthesizing ZnSeTe-based core / shell quantum dots (i.e., large-core thin-shell quantum dots) and for preparing quantum dots using an anhydrous ethanol solution containing ammonium chloride (NH4Cl) for post-processing. This method is essentially the same as that in Example 1. The difference lies in step six, where an NH4Cl-anhydrous ethanol solution is used for post-processing. 0.2 mmol of NH4Cl powder is added to 10 mL of anhydrous ethanol solution to obtain a 0.02 M NH4Cl-anhydrous ethanol solution.

[0056] Example 4

[0057] This embodiment provides a novel method for synthesizing ZnSeTe-based core / shell quantum dots (i.e., large-core thin-shell quantum dots) and for preparing quantum dots using an anhydrous ethanol solution containing ammonium bromide (NH4Br) for post-processing. This method is essentially the same as that in Example 1. The difference lies in step six, where an NH4Br-anhydrous ethanol solution is used for post-processing. 0.2 mmol of NH4Br powder is added to 10 mL of anhydrous ethanol solution to obtain a 0.02 M NH4Br-anhydrous ethanol solution.

[0058] Example 5

[0059] This embodiment provides a novel method for synthesizing ZnSeTe-based core / shell quantum dots (i.e., large-core thin-shell quantum dots) and for preparing quantum dots using an anhydrous ethanol solution containing ammonium iodide (NH4I) for post-processing, which is basically the same as in Example 1. The difference is that in step six, an anhydrous ethanol solution of NH4I is used for post-processing. 0.2 mmol of NH4I powder is taken and added to 10 mL of anhydrous ethanol solution to obtain a 0.02 M NH4I-anhydrous ethanol solution.

[0060] Example 6

[0061] This embodiment provides a novel method for synthesizing large-core thin-shell ZnSeTe-based core / shell quantum dots (i.e., large-core thin-shell quantum dots) and for post-processing with an anhydrous ethanol solution containing ammonium fluoride (NH4F), which is basically the same as that in Example 1. The difference is that in step three, 13.5 mL of ZnSeTe core epitaxial growth stock solution is added to a three-necked flask ①.

[0062] Comparative Example 1 This comparative example provides a novel method for synthesizing large-core, thin-shell ZnSeTe / ZnSe / ZnS quantum dots, but with conventional post-treatment using pure anhydrous ethanol. The quantum dot preparation process is basically the same as in Example 1, except that the specific steps in step six are as follows: (1) Take 1 mL of ZnSeTe-based core / shell quantum dot stock solution into a centrifuge tube, add 4 mL of anhydrous ethanol, and centrifuge at 5000 r / min for 6 min. (2) After the treatment in step (1), discard the supernatant, add 1 mL of n-octane to the centrifuge tube to dissolve the precipitate, and centrifuge at 5000 r / min for 6 min. (3) After the treatment in step (2), transfer the supernatant to another centrifuge tube, add 4 mL of anhydrous ethanol, and centrifuge at 5000 r / min for 6 min. (4) After step (3) is completed, the precipitate is dried in a nitrogen atmosphere and dissolved in an appropriate amount of n-octane to obtain ZnSeTe-based core / shell structure quantum dots (i.e., large core thin shell quantum dots).

[0063] Comparative Example 2 This comparative example provides a method for synthesizing small-core, thick-shell ZnSeTe / ZnSe / ZnS quantum dots (referred to as small-core, thick-shell quantum dots) and preparing them using conventional pure anhydrous ethanol post-treatment. The quantum dot preparation process is basically the same as that of Comparative Example 1. The difference is that in step one, it is not necessary to prepare the ZnSeTe core epitaxial growth solution, and step three is also unnecessary. Therefore, small ZnSeTe cores are obtained. In step four, the amount of ZnSe shell epitaxial growth solution added is 34.8 mL.

[0064] Comparative Example 3 This comparative example provides a method for synthesizing high-Te-component ZnSeTe / ZnSe / ZnS quantum dots (referred to as high-Te-component quantum dots) and preparing them using conventional pure anhydrous ethanol. The quantum dot preparation process is basically the same as that of Comparative Example 1. The difference is that in step one, it is not necessary to prepare the ZnSeTe core epitaxial growth solution. The TOP / OLA-Te precursor solution is prepared by dissolving 0.12 mmol of tellurium powder in 1 mL of TOP and 3 mL of oleylamine to obtain a 0.03 M TOP / OLA-Te solution (i.e., the molar concentration of Te is 0.03 M). At the same time, step three is not required. In step two, 0.03 M of TOP / OLA-Te precursor solution is injected, thus obtaining a high-Te-component ZnSeTe core. In step four, the amount of ZnSe shell epitaxial growth solution added is 14.5 mL, and in step five, the amount of ZnS shell epitaxial growth solution injected is 29 mL.

[0065] Figure 1The figures show a comparison of fluorescence emission spectra for three different quantum dots. The large-core thin-shell quantum dot corresponds to Example 1, the high-Te component quantum dot corresponds to Comparative Example 3, and the small-core thick-shell quantum dot corresponds to Comparative Example 2. As can be seen from the figures, compared to the other two types of quantum dots, the large-core thin-shell quantum dot achieves blue light emission in the 445-470 nm wavelength range while exhibiting increased fluorescence intensity and decreased fluorescence full width at half maximum (FWHM).

[0066] Figure 2 Figure (a) shows a transmission electron microscope (TEM) image of the small-core thick-shell quantum dots of Comparative Example 2 after the growth of small ZnSeTe cores; Figure (d) shows a statistical diagram of the quantum dot size after the growth of small ZnSeTe cores of Comparative Example 2; Figure (b) shows a TEM image of the small-core thick-shell quantum dots of Comparative Example 2 after the growth of ZnSe intermediate shells on the basis of small ZnSeTe cores; Figure (e) shows a statistical diagram of the quantum dot size after the growth of ZnSe intermediate shells on the basis of small ZnSeTe cores of Comparative Example 2; Figure (c) shows a TEM image of the small-core thick-shell quantum dots of Comparative Example 2 after the growth of ZnS shells on the basis of ZnSe intermediate shells (i.e., the preparation of small-core thick-shell quantum dots is completed); Figure (f) shows a statistical diagram of the quantum dot size after the growth of ZnS shells on the basis of ZnSe intermediate shells of Comparative Example 2 (i.e., the preparation of small-core thick-shell quantum dots is completed).

[0067] Figure 3 (a) is a transmission electron microscope (TEM) image of the high-Te quantum dots of Comparative Example 3 after the high-Te ZnSeTe core has been grown; (d) is a statistical diagram of the quantum dot size after the high-Te quantum dots of Comparative Example 3 have been grown after the high-Te ZnSeTe core has been grown; (b) is a TEM image of the high-Te quantum dots of Comparative Example 3 after the ZnSe intermediate shell has been further grown on the basis of the high-Te ZnSeTe core; (e) is a statistical diagram of the quantum dot size after the high-Te quantum dots of Comparative Example 3 have been further grown on the basis of the high-Te ZnSeTe core has been grown after the ZnSe intermediate shell ...

[0068] Figure 4Figure (a) shows a transmission electron microscope image of the large-core thin-shell quantum dots of Example 1 after the large ZnSeTe core has been grown; Figure (d) shows a statistical diagram of the quantum dot particle size after the large-core thin-shell quantum dots of Example 1 have been grown after the large ZnSeTe core has been grown; Figure (b) shows a transmission electron microscope image of the large-core thin-shell quantum dots of Example 1 after the ZnSe intermediate shell has been further grown on the basis of the large ZnSeTe core; Figure (e) shows a statistical diagram of the quantum dot particle size after the large-core thin-shell quantum dots of Example 1 have been further grown on the basis of the large ZnSeTe core and the ZnSe intermediate shell has been grown; Figure (c) shows a transmission electron microscope image of the large-core thin-shell quantum dots of Example 1 after the ZnS outer shell has been further grown on the basis of the ZnSe intermediate shell (i.e., the preparation of the core thin-shell quantum dots is completed); Figure (f) shows a statistical diagram of the quantum dot particle size after the large-core thin-shell quantum dots of Example 1 have been further grown on the basis of the ZnSe intermediate shell and the ZnS outer shell has been grown (i.e., the preparation of the core thin-shell quantum dots is completed).

[0069] Combination Figure 2-4 As can be seen from the figure: the average particle size of the ZnSeTe core in the small-core, thick-shell quantum dot is only about 3.88 nm, while the average thickness of the ZnSe intermediate shell needs to reach about 3 nm ((9.78 nm - 3.88 nm) / 2). Only then can this type of quantum dot (average particle size about 10.65 nm) achieve blue light emission in the 445-470 nm wavelength range. Similarly, the average particle size of the ZnSeTe core in the high-Te composition quantum dot is also only about 3.85 nm, while the average thickness of its ZnSe intermediate shell reaches about 2 nm ((7.72 nm - 3.85 nm) / 2). The resulting quantum dots (with an average particle size of approximately 9.34 nm) achieve blue light emission at a similar peak wavelength. Compared to the two types of quantum dots mentioned above, the large-core thin-shell quantum dots of this invention have a larger average particle size of large ZnSeTe cores (approximately 5.13 nm). Only a relatively thin ZnSe intermediate shell (1.8 nm thick, (8.75 nm - 5.13 nm) / 2) is needed for the quantum dots (with an average particle size of approximately 10.12 nm) to achieve blue light emission at a similar peak wavelength. This helps to reduce the density of mismatched dislocations at the core / shell interface.

[0070] Figure 5 Normalized photoluminescence spectra of three large-core thin-shell quantum dots with different core sizes are shown. As can be seen from the figures, for the large-core thin-shell quantum dots described in this invention, the emission peak wavelength in the 445-470 nm band can be controlled by changing the amount of ZnSeTe core epitaxial growth solution added and the reaction time (as the amount added changes, the reaction time also changes).

[0071] Figure 6The figures show a comparison of the fluorescence emission spectra of Examples 1, 3, 4, and 5 with Comparative Example 1. As can be seen from the figures, compared to traditional post-treatment with pure anhydrous ethanol, the introduction of ammonium halide significantly enhances the photoluminescence intensity of the quantum dots.

[0072] Figure 7 The images show examples 1, 4, and Comparative Example 1 under UV lamp illumination. As can be seen from the figures, compared to the traditional post-treatment with pure anhydrous ethanol, the quantum dots prepared by the ammonium halide post-treatment method emit brighter blue light (as shown by the dotted line in the figure; the quantum dot solution obtained by the traditional pure anhydrous ethanol post-treatment is only blue, while the quantum dot solution obtained by the ammonium halide post-treatment method has significantly improved luminescence brightness, and the liquid surface appears white to the naked eye).

[0073] This invention achieves large-particle-size ZnSeTe quantum dot cores with emission wavelengths >430 nm by controlling the amount of ZnSeTe core growth solution, growth temperature, and growth time during the preparation of large-particle-size ZnSeTe quantum dot cores via epitaxial growth. Consequently, in subsequent steps, only a thinner ZnSe shell needs to be epitaxially grown to tune the quantum dot emission wavelength to the blue light emission region of 445-470 nm, with a narrow fluorescence half-maximum width (<30 nm). This optimized structure helps reduce the lattice mismatch dislocation density at the ZnSeTe / ZnSe core-shell interface, improving the luminescence performance of the quantum dots. Compared to traditional post-treatment with pure anhydrous ethanol, this invention introduces highly coordinating ammonium halides into the polar antisolvent during the post-treatment stage. These halides can partially replace the original long-chain organic ligands and simultaneously passivate undercoordinated atomic defects on the quantum dot surface caused by steric hindrance or long-chain ligand shedding.

[0074] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.

Claims

1. A method for preparing ZnSeTe-based core / shell structure quantum dots, characterized in that, The steps S1 to S4 of the preparation method are performed under an inert atmosphere, comprising the following steps: S1, after mixing the core Se precursor solution and the core Te precursor solution, the mixture is injected into a container containing the core Zn precursor solution by hot injection, and the ZnSeTe quantum dot initial core is grown at a high temperature of 280-300 DEG C; the core Se precursor solution is prepared from selenium powder and diphenylphosphine; the core Te precursor solution is prepared from tellurium powder, tri-n-octylphosphine, and oleylamine; the core Zn precursor solution is prepared from a zinc source, oleic acid, oleylamine, and octadecene; S2, after the ZnSeTe quantum dot initial core is uniformly grown, the ZnSeTe core epitaxial growth stock solution is injected into the container drop by drop at 280-300 DEG C to react, so that a solution of large-particle-size ZnSeTe quantum dot core with an average particle size greater than 5 nm is obtained; the ZnSeTe core epitaxial growth stock solution is prepared from selenium powder, the core Te precursor solution, a zinc source, oleic acid, octadecene, and tri-n-octylphosphine; S3, after the large-particle-size ZnSeTe quantum dot core is grown, the solution of the large-particle-size ZnSeTe quantum dot core is heated to 300-330 DEG C, and then the ZnSe shell epitaxial growth stock solution is injected into the solution of the large-particle-size ZnSeTe quantum dot core to react, so that the growth of a ZnSe shell with a thickness less than 2 nm is completed; the ZnSe shell epitaxial growth stock solution is prepared from a zinc source, oleic acid, oleylamine, octadecene, and a shell Se precursor solution, and the shell Se precursor solution is prepared from selenium powder and tri-n-octylphosphine; S4, after the ZnSe shell is grown, the ZnS shell epitaxial growth stock solution is injected into the container to react, so that the growth of a ZnS shell is completed, and finally a ZnSeTe-based core / shell structure quantum dot solution is obtained; the ZnS shell epitaxial growth stock solution is prepared from a zinc source, oleic acid, oleylamine, octadecene, and a shell S precursor solution, and the shell S precursor solution is prepared from sulfur powder and tri-n-octylphosphine; S5, the ZnSeTe-based core / shell structure quantum dot solution is naturally cooled to room temperature, and then a polar anti-solvent containing an ammonium halide is added to the solution for post-processing, so that a ZnSeTe-based core / shell structure quantum dot is obtained.

2. The method for preparing ZnSeTe-based core / shell quantum dots according to claim 1, characterized in that, The octadecene in the core Zn precursor solution, the ZnSe shell epitaxial growth stock solution, and the ZnS shell epitaxial growth stock solution can be replaced by trioctylamine or a mixture of octadecene and trioctylamine; the zinc source includes anhydrous zinc acetate, zinc stearate, or a composite formed by mixing dodecylphosphonic acid with zinc oxide.

3. The method of claim 1, wherein the ZnSeTe-based core / shell quantum dot is prepared by the following steps of: (a) preparing a ZnSeTe core quantum dot; (b) preparing a ZnS shell quantum dot; and (c) coating the ZnSeTe core quantum dot with the ZnS shell quantum dot. The ratio of the amount of substance of tellurium powder to the amount of substance of selenium powder in the container is the same and is 0.01-0.03:1 when growing the initial core and the large particle size ZnSeTe quantum dot core; the ratio of the amount of substance of zinc source to the total amount of substance of tellurium powder and selenium powder in the container is 1.5-3:1 when growing the ZnSeTe quantum dot initial core; the ratio of the amount of substance of zinc source to selenium powder in the ZnSe shell epitaxial growth original solution is 1-1.5:1, and the volume ratio of oleic acid to oleylamine is 1.5-3:1 when growing the ZnSe shell; the ratio of the amount of substance of zinc source to sulfur powder in the ZnS shell epitaxial growth original solution is 1-1.5:1, and the volume ratio of oleic acid to oleylamine is 1.5-3:1 when growing the ZnS shell.

4. The method of claim 1, wherein the ZnSeTe-based core / shell quantum dot is prepared by the following steps of: (a) preparing a ZnSeTe core quantum dot; (b) preparing a ZnS shell quantum dot; and (c) coating the ZnSeTe core quantum dot with the ZnS shell quantum dot. The preparation method of the core Se precursor solution is as follows: selenium powder is added to diphenyl phosphine, heated to 80 DEG C under an inert atmosphere and stirred until dissolved to obtain the core Se precursor solution; The preparation method of the core Te precursor solution is as follows: take tellurium powder, add tri-n-octyl phosphine and oleylamine, stir until dissolved under an inert atmosphere at room temperature to obtain the core Te precursor solution; the preparation method of the core Zn precursor solution is as follows: take zinc source, add oleic acid, oleylamine and octadecene, first vacuumize under room temperature conditions and fill with inert gas, then heat to 100-150 DEG C and vacuumize to obtain the core Zn precursor solution.

5. The method of claim 1, wherein the ZnSeTe-based core / shell quantum dot is prepared by the following steps of: (a) preparing a ZnSeTe core quantum dot; (b) preparing a ZnS shell quantum dot; and (c) coating the ZnSeTe core quantum dot with the ZnS shell quantum dot. The preparation method of the ZnSeTe core epitaxial growth original solution is as follows: take zinc source, add selenium powder, core Te precursor solution, oleic acid, octadecene and tri-n-octyl phosphine, first vacuumize under room temperature conditions and fill with inert gas, then heat to 100-150 DEG C and vacuumize to obtain the ZnSeTe core epitaxial growth original solution.

6. The method of claim 1, wherein the ZnSeTe-based core / shell quantum dot is prepared by the following steps: (1) preparing a ZnSeTe core quantum dot; (2) preparing a ZnS shell quantum dot; and (3) coating the ZnSeTe core quantum dot with the ZnS shell quantum dot. The preparation method of the ZnSe shell epitaxial growth original solution is as follows: take zinc source, add shell Se precursor solution, oleic acid, oleylamine and octadecene, first vacuumize under room temperature conditions and fill with inert gas, then heat to 100-150 DEG C and vacuumize to obtain the ZnSe shell epitaxial growth original solution; The preparation method of the shell Se precursor solution is as follows: take selenium powder, add tri-n-octyl phosphine, stir until dissolved under an inert atmosphere at room temperature to obtain the shell Se precursor solution.

7. The method of claim 1, wherein the ZnSeTe-based core / shell quantum dot is prepared by the following steps: (1) preparing a ZnSeTe core quantum dot; (2) preparing a ZnS shell quantum dot; and (3) coating the ZnSeTe core quantum dot with the ZnS shell quantum dot. The preparation method of the ZnS shell epitaxial growth original solution is as follows: take zinc source, add shell S precursor solution, oleic acid, oleylamine and octadecene, first vacuumize under room temperature conditions and fill with inert gas, then heat to 100-150 DEG C and vacuumize to obtain the ZnS shell epitaxial growth original solution; The preparation method of the shell S precursor solution is as follows: take sulfur powder, add tri-n-octyl phosphine, stir until dissolved under an inert atmosphere at room temperature to obtain the shell S precursor solution.

8. The method for preparing ZnSeTe-based core / shell quantum dots according to claim 1, characterized in that, The specific steps of post-treatment in step S5 are as follows: (1) take the ZnSeTe-based core / shell structure quantum dot solution into a centrifugal tube, add a polar anti-solvent containing ammonium halide and do centrifugal treatment; (2) after centrifugal treatment in step (1), pour away the supernatant, add a non-polar solvent to the precipitate to dissolve and do centrifugal treatment; (3) after centrifugal treatment in step (2), transfer the supernatant to another centrifugal tube, add a polar anti-solvent containing ammonium halide again and do centrifugal treatment; (4) After step (3) is completed, the supernatant is discarded, the precipitate is dried under vacuum or inert environment, or is dried by blowing inert gas at room temperature, and a non-polar solvent is added to obtain ZnSeTe-based core / shell structure quantum dots.

9. The method of claim 8, wherein the ZnSeTe-based core / shell quantum dot is prepared by the following steps: (1) preparing a ZnSeTe core quantum dot; (2) preparing a ZnS shell quantum dot; and (3) coating the ZnSeTe core quantum dot with the ZnS shell quantum dot. The preparation method of the polar anti-solvent containing ammonium halide is as follows: any one or more of NH4F, NH4Cl, NH4Br and NH4I is taken, a polar solvent is added, and stirring is performed at room temperature until dissolution to obtain the polar anti-solvent containing ammonium halide.

10. Application of the ZnSeTe-based core / shell structure quantum dots prepared by the preparation method of the ZnSeTe-based core / shell structure quantum dots according to any one of claims 1 to 9 as quantum dot materials for emitting blue light in a 445-470 nm wave band.

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