Method for preparing CdSe / ZnSe core / shell magic number clusters with preformed nuclei clusters

Abstract

The present invention provides a CdSe / ZnSe magic number cluster, a preparation method and a use thereof, belonging to the technical field of semiconductor luminescent materials. The CdSe / ZnSe magic number cluster of the present invention is a magic number cluster with a core-shell structure, the CdSe magic number cluster is the core, and a layer of ZnSe is coated on the outside as the shell; the emission wavelength of the CdSe / ZnSe magic number cluster is 450-465 nm, and the full width at half maximum is less than 15 nm. In the present invention, a ZnSe induction period sample is added to the CdSe magic number cluster, and the precursor compound of ZnSe is decomposed into ZnSe monomers, and the ZnSe monomers coat the surface of the CdSe magic number cluster to form a CdSe / ZnSe magic number cluster. The CdSe / ZnSe magic number cluster of the present invention is carried out at 25 °C, and this process will not cause the emission peak of the nanocluster to redshift, ensuring the purity of the blue light. The CdSe / ZnSe magic number cluster provided by the present invention is a blue light emitting material with an emission wavelength at 450-465 nm, a full width at half maximum less than 15 nm, and defect-free state luminescence, providing a possibility for the application of II-VI group semiconductor nanocrystals in optoelectronic devices.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor luminescent materials, and in particular relates to a CdSe / ZnSe magic number cluster and a preparation method and application thereof. Background Art

[0002] Quantum dots, or semiconductor nanocrystals, have been a hot topic in the field of nanotechnology for nearly three decades due to their quantum size effects and excellent optical properties. Semiconductor quantum dots have a wide excitation spectrum, a narrow and symmetrical emission spectrum, and the emission wavelength can be adjusted by controlling the elemental composition and particle size of the quantum dots, with good stability. Therefore, quantum dots have good application prospects in optoelectronic devices, biomedicine, energy, and catalysis. Magic clusters are nanomaterials with special properties discovered during the growth of quantum dots. Compared with conventional quantum dots, magic clusters have a narrower size distribution and a more stable spatial structure, and therefore exhibit sharp absorption peaks in the ultraviolet absorption spectrum. The synthesis and mechanism research of magic clusters has important guiding significance for the development of quantum dot synthesis methods.

[0003] Semiconductor light-emitting materials are materials that emit light by releasing energy through the recombination of electrons and holes, and they have great application prospects in light-emitting devices. Light-emitting devices of different colors are made of various specific light-emitting materials. Among them, the design and synthesis of pure blue light-emitting materials with narrow emission peaks and defect-free emission is still a major challenge. The core-shell structure, due to its unique structural characteristics, integrates the properties of the two materials inside and outside, and complements each other's shortcomings. It has been an important research direction in recent years where morphology determines properties. It has broad application prospects in biomedicine, catalysis, photocatalysis, batteries, gas storage and separation. There are currently two strategies for constructing core-shell structures: one is to form the nucleus first and then coat the shell; the other is to form the core-shell structure at one time. In recent years, strategy one has been widely used to synthesize various core-shell bimetallic nanomaterials.

[0004] In order to solve the above problems, in order to solve the shortcomings of single-component nanomaterials in efficiency and surface sensitivity, an effective high-temperature alloy synthesis strategy has been proposed, which also has good luminescence properties in the blue spectrum range. Specific examples of such materials include: by adding Zn and Se precursors to the pre-prepared CdSe system, a series of high-luminescence and high-quality Zn with adjustable composition are prepared. x Cd 1-x Se uniform alloy quantum dots (half-peak width: 22-30nm), whose emission spectrum is continuously adjustable in the range of 460-630nm, and the emission wavelength gradually blue-shifts with the increase of Zn content. Alternatively, luminescent ZnSe quantum dots with adjustable emission can be prepared from pre-prepared ZnSe quantum dots by cation exchange method. x Cd 1-x Se alloy quantum dots. However, Zn xCd 1-x The problems existing in CdSe alloy quantum dot materials are as follows: The formation process is thermodynamically controlled, and the absorption spectrum depending on temperature shows a monotonic red shift with the increase of temperature. The degree of alloying will cause spectral changes, and it is difficult to ensure the purity of blue light and a high quantum yield. In addition, due to the thermal instability of CdSe magic number clusters, there is still a lack of relevant methods for the synthesis of core-shell structured CdSe / ZnSe magic number clusters. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the present invention provides a CdSe / ZnSe magic number cluster and its preparation method and use. The purpose is to provide a controllable synthesis method for CdSe / ZnSe magic number clusters, enabling them to have blue light emission performance with a lower wavelength. At the same time, it has a semiconductor heterojunction structure to achieve the purpose of enhancing luminescence and increasing the quantum yield.

[0006] The present invention provides a CdSe / ZnSe magic number cluster, which is a magic number cluster with a core-shell structure, with a CdSe magic number cluster as the core and a layer of ZnSe coated outside as the shell; the emission wavelength of the CdSe / ZnSe magic number cluster is 450 - 465 nm, and the full width at half maximum is less than 15 nm.

[0007] The present invention also provides a method for preparing the aforementioned CdSe / ZnSe magic number cluster, which includes the following steps: adding a ZnSe induction period sample to the CdSe magic number cluster, and obtaining the CdSe / ZnSe magic number cluster after reaction.

[0008] Further, the volume ratio of the CdSe magic number cluster to the ZnSe induction period sample is 1:1.

[0009] Further, the temperature of the reaction is 25 - 160 °C; and / or, the time of the reaction is 0.5 - 10 h;

[0010] Preferably, the temperature of the reaction is 25 - 30 °C;

[0011] More preferably, the temperature of the reaction is 25 °C; and / or, the time of the reaction is 8 h.

[0012] Further, the preparation method of the CdSe magic number cluster includes the following steps:

[0013] (1) React cadmium acetate dihydrate with oleylamine to obtain an oleylamine cadmium acetate precursor;

[0014] (2) Mix and react the oleylamine cadmium acetate precursor with selenium powder to obtain a CdSe magic number cluster reaction stock solution;

[0015] (3) Purify the CdSe magic number cluster reaction stock solution to obtain the CdSe magic number cluster.

[0016] Further,

[0017] In step (1), the molar ratio of cadmium acetate dihydrate to oleylamine is 1:(10 - 15);

[0018] and / or, in step (1), the reaction is to react at 80 - 120 °C for 1 - 3 h first, and then react at 120 - 140 °C for 1 - 3 h;

[0019] and / or, in step (2), the molar ratio of the cadmium oleate precursor to selenium powder is (1 - 4):1;

[0020] and / or, in step (2), the reaction temperature is 80 - 140 °C and the reaction time is 1 - 3 h;

[0021] Preferably,

[0022] In step (1), the molar ratio of cadmium acetate dihydrate to oleylamine is 1:13;

[0023] and / or, in step (1), the reaction is to react at 80 °C for 1 h first, and then react at 120 °C for 1 h;

[0024] and / or, in step (1), the reaction is carried out under vacuum conditions;

[0025] and / or, in step (2), the molar ratio of the cadmium oleate precursor to selenium powder is 3:1;

[0026] and / or, in step (2), the reaction temperature is 100 °C and the reaction time is 2 h.

[0027] More preferably, in step (1), when cadmium acetate dihydrate reacts with oleylamine, vacuum and inert gas are alternately filled multiple times first, and then an inert gas atmosphere is maintained. After heating to the reaction temperature, vacuum is pumped again for the reaction.

[0028] Further, in step (3), the purification method includes the following steps:

[0029] (3.1) Add trioctylphosphine to the CdSe magic number cluster reaction stock solution to remove unreacted selenium;

[0030] (3.2) Add absolute ethanol to the reaction solution obtained in step (3.1), shake well and centrifuge;

[0031] (3.3) Add absolute ethanol to the solid obtained after centrifugation, shake well and centrifuge, and dry the obtained precipitate;

[0032] (3.4) Dissolve the dried precipitate in oleylamine again, and that's it;

[0033] Preferably,

[0034] In step (3.1), the volume ratio of the CdSe magic number cluster reaction stock solution to trioctylphosphine is (8 - 10):1;

[0035] and / or, in step (3.1), after adding trioctylphosphine, stir at room temperature for 5 - 10 min;

[0036] and / or, in step (3.2), the rotation speed of centrifugation is 8000 - 12000 r / min, and the centrifugation time is 2 - 10 min;

[0037] and / or, in step (3.3), the rotation speed of centrifugation is 8000 - 12000 r / min, and the centrifugation time is 2 - 10 min;

[0038] and / or, in step (3.4), the mass - volume ratio of the dried precipitate to oleylamine is (1 - 5) mg:1 mL;

[0039] More preferably,

[0040] In step (3.1), the volume ratio of the CdSe magic number cluster reaction stock solution to trioctylphosphine is 10:1;

[0041] and / or, in step (3.2), the rotation speed of centrifugation is 9000 r / min, and the centrifugation time is 5 min;

[0042] and / or, in step (3.3), the rotation speed of centrifugation is 9000 r / min, and the centrifugation time is 5 min;

[0043] and / or, in step (3.4), the mass - volume ratio of the dried precipitate to oleylamine is 5 mg:1 mL.

[0044] Furthermore, the preparation method of the ZnSe induction - period sample includes the following steps:

[0045] (a) Mix zinc acetate with oleylamine and react to obtain an oleylamine zinc acetate precursor;

[0046] (b) Mix selenium powder with trioctylphosphine and react to obtain a trioctylphosphine selenium precursor;

[0047] (c) Mix the trioctylphosphine selenium precursor and diphenylphosphine, and then add them to the oleylamine zinc acetate precursor to react to obtain a ZnSe induction - period sample.

[0048] Furthermore,

[0049] In step (a), the molar ratio of zinc acetate to oleylamine is 1:(13 - 15);

[0050] And / or, in step (a), the temperature of the reaction is 100 - 140 °C, and the reaction time is 1 - 3 h;

[0051] And / or, in step (b), the molar ratio of selenium powder to trioctylphosphine is 1:(1 - 4);

[0052] And / or, in step (b), the temperature of the reaction is 25 - 40 °C, and the reaction time is 0.5 - 1 h;

[0053] And / or, in step (c), the molar ratio of the trioctylphosphine selenium precursor, zinc acetate oleylamine precursor, and diphenylphosphine is 1:(1 - 5):(1 - 2);

[0054] And / or, in step (c), the temperature of the reaction is 120 - 200 °C, and the reaction time is 15 - 30 min;

[0055] Preferably,

[0056] In step (a), the molar ratio of zinc acetate to oleylamine is 1:13.6;

[0057] And / or, in step (a), the temperature of the reaction is 120 °C, and the reaction time is 1 h;

[0058] And / or, in step (a), the reaction is carried out under vacuum conditions;

[0059] And / or, in step (b), the molar ratio of selenium powder to trioctylphosphine is 1:2.2;

[0060] And / or, in step (b), the temperature of the reaction is 40 °C, and the reaction time is 0.5 h;

[0061] And / or, in step (b), the reaction is carried out in an inert gas atmosphere;

[0062] And / or, in step (c), the molar ratio of the trioctylphosphine selenium precursor, zinc acetate oleylamine precursor, and diphenylphosphine is 1:4:1;

[0063] And / or, in step (c), the temperature of the reaction is 160 °C, and the reaction time is 15 min.

[0064] More preferably,

[0065] In step (a), when zinc acetate reacts with oleylamine, vacuum and inert gas are alternately filled multiple times first, then an inert gas atmosphere is maintained, and after heating to the reaction temperature, vacuum is pumped again for the reaction;

[0066] In step (b), when the selenium powder reacts with trioctylphosphine, the vacuum and inert gas are alternately filled multiple times first, and then the reaction is carried out by heating up while maintaining an inert gas atmosphere.

[0067] The present invention also provides the use of the foregoing CdSe / ZnSe magic number clusters as a blue light emitting material;

[0068] Preferably, the wavelength of the blue light is 450 - 465 nm;

[0069] More preferably, the wavelength of the blue light is 460 nm.

[0070] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0071] The present invention provides a preparation method of core-shell structured CdSe / ZnSe magic number clusters. By adding a ZnSe induction period sample to the CdSe magic number clusters, the precursor compound of ZnSe decomposes into ZnSe monomers, and the ZnSe monomers coat the surface of the CdSe magic number clusters to form CdSe / ZnSe magic number clusters. The CdSe / ZnSe magic number clusters of the present invention are prepared at 25°C, and this process will not cause the emission peak of the nanoclusters to redshift, ensuring the purity of the blue light. The CdSe / ZnSe magic number clusters provided by the present invention are a blue light emitting material with an emission wavelength at 450 - 465 nm, a full width at half maximum of less than 15 nm, and no defect state luminescence, providing possibilities for the application of II-VI group semiconductor nanocrystals in optoelectronic devices.

[0072] Obviously, based on the above content of the present invention, according to the common general knowledge and conventional means in the art, without departing from the above basic technical idea of the present invention, various other forms of modifications, substitutions or changes can be made.

[0073] The following is a further detailed description of the above content of the present invention through specific embodiments in the form of examples. However, this should not be construed as limiting the scope of the above subject matter of the present invention to the following examples. All technologies implemented based on the above content of the present invention belong to the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 It is a process schematic diagram for preparing CdSe / ZnSe magic number clusters.

[0075] Figure 2 It is the absorption spectrum and emission spectrum of the CdSe / ZnSe magic number clusters prepared in Example 1.

[0076] Figure 3 It is the absorption spectrum and emission spectrum of the CdSe magic number clusters prepared in Comparative Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0077] The raw materials and equipment used in the specific implementation mode of the present invention are all known products, which are obtained by purchasing commercially available products.

[0078] Example 1: Preparation and Luminescence Properties of CdSe / ZnSe Magic Number Clusters

[0079] This example provides a method for synthesizing ternary core-shell structured CdSe / ZnSe magic number clusters by reacting binary CdSe magic number clusters with ZnSe induction period samples at 25 °C, which specifically includes the following steps:

[0080] 1. Preparation of CdSe Magic Number Clusters

[0081] Prepare cadmium oleate acetate (Cd(OAc)2 / OLA) precursor by mixing cadmium acetate dihydrate (Cd(OAc)2·2H2O) with oleylamine (OLA):

[0082] (1) Place cadmium acetate dihydrate (1.599 g, 6.00 mmol) and oleylamine (36.0 mL, 78.00 mmol) in a three-necked flask, evacuate at room temperature for 8 min, then fill with nitrogen for 2 min, perform the vacuum / nitrogen replacement operation for three cycles (completed within 30 min), and finally maintain a nitrogen atmosphere;

[0083] (2) Under nitrogen protection, heat up to 80 °C, then evacuate and maintain the reaction for 1 hour. After the vacuum reaction is completed, fill with nitrogen and maintain a nitrogen atmosphere for the reaction at the next temperature;

[0084] (3) Under nitrogen protection, heat up to 120 °C, then evacuate and maintain the reaction for 1 hour. After the vacuum reaction is completed, fill with nitrogen and maintain a nitrogen atmosphere;

[0085] (4) Cool down to room temperature and collect the product. The obtained product is the cadmium oleate acetate precursor (liquid).

[0086] Take 6 mL of the above-prepared cadmium oleate acetate precursor and mix it with 12.0 mg of selenium powder (Se), heat up to 100 °C and react for 2 h to obtain the CdSe magic number cluster reaction stock solution.

[0087] 2. Purification of CdSe Magic Number Clusters

[0088] (1) Pipette 5.0 mL of the CdSe magic number cluster reaction stock solution, add 0.5 mL of trioctylphosphine (TOP), and stir at room temperature for 5.0 min to remove the unreacted selenium powder in the reaction system;

[0089] (2) Transfer the reaction solution treated with TOP to a 30 mL centrifuge tube, add 20.0 mL of absolute ethanol (EtOH), shake well, place it on a centrifuge and centrifuge at a speed of 9000 r / min for 5.0 min, and pour out the upper clear liquid;

[0090] (3) Add 20.0 mL of EtOH to the obtained solid product and centrifuge it at 9000 r / min for 5.0 min on a centrifuge. Pour out the supernatant, and vacuum-dry the obtained precipitate to a powder.

[0091] (4) Dissolve 25.0 mg of the powder in 5.0 mL of oleylamine to obtain purified CdSe magic-number clusters.

[0092] 3. Preparation of ZnSe induction period samples

[0093] Prepare zinc oleate acetate (Zn(OAc)2 / OLA) (zinc precursor) and trioctylphosphine selenide (SeTOP) (selenium precursor) from zinc acetate (Zn(OAc)2) and oleylamine (OLA), and selenium powder (Se) and trioctylphosphine (TOP), respectively.

[0094] The preparation method of zinc oleate acetate (zinc precursor) is as follows:

[0095] (1) Place zinc acetate (0.661 g, 3.60 mmol) and oleylamine (15.9 mL, 49.00 mmol) in a three-necked flask.

[0096] (2) Heat to 80 °C, evacuate for 8 min, then fill with nitrogen for 2 min. Perform the vacuum / nitrogen gas exchange operation for three cycles (completed within 30 min), and finally maintain a nitrogen atmosphere.

[0097] (3) Under nitrogen protection, heat to 120 °C, then evacuate and maintain the reaction for 1 hour. After the vacuum reaction is completed, fill with nitrogen and maintain a nitrogen atmosphere.

[0098] (4) Cool to room temperature and collect the product. The obtained product is the zinc oleate acetate precursor (liquid).

[0099] The preparation method of trioctylphosphine selenide (selenium precursor) is as follows:

[0100] (1) Place selenium powder (0.328 g, 4.15 mmol) and trioctylphosphine (3.390 g, 9.15 mmol) in a three-necked flask.

[0101] (2) Evacuate at room temperature for 8 min, then fill with nitrogen for 2 min. Perform the vacuum / nitrogen gas exchange operation for three cycles (completed within 30 min), and finally maintain a nitrogen atmosphere.

[0102] (3) Under nitrogen protection, heat to 40 °C and react for 30 min.

[0103] (4) Cool to room temperature and collect the product. The obtained product is the trioctylphosphine selenide precursor (liquid).

[0104] The zinc oleate acetate precursor (5.3 mL, 1.20 mmol) was placed in a three-necked flask, heated to 80 °C, evacuated for 8 min, then filled with nitrogen for 2 min. The vacuum / nitrogen replacement operation was carried out for three cycles (completed within 30 min). Finally, under a nitrogen atmosphere, it was heated to 120 °C, evacuated, and maintained for 2 hours. Then it was filled with nitrogen to maintain the nitrogen atmosphere, cooled to 80 °C, and the trioctylphosphine selenium precursor (330 μL, 0.30 mmol) and diphenylphosphine (52 μL, 0.30 mmol) were added. The reaction was carried out at 160 °C for 15 min to obtain the ZnSe induction period sample (liquid).

[0105] 4. Preparation of CdSe / ZnSe magic number clusters

[0106] 3 mL of the purified CdSe magic number clusters was added with 3 mL of the ZnSe induction period sample, and the reaction was carried out at 25 °C for 8 h to synthesize the target product CdSe / ZnSe magic number clusters. The process flow chart is as Figure 1 shown.

[0107] The absorption spectrum (UV) and emission spectrum (PL) of the CdSe / ZnSe magic number clusters prepared in this example are as Figure 2 shown. It can be seen from the emission spectrum that the emission peak is located at 460 nm. Compared with other existing CdZnSe composite materials (emission spectrum at 470 - 630 nm), its emission peak shows a blue shift, and the low blue light screen can slow down the stimulation to the eyes. In addition, the full width at half maximum of the emission peak is less than 15 nm, and there is no defect state luminescence. Therefore, the CdSe / ZnSe magic number clusters provided by the present invention can emit a blue light emitting material with a narrow emission bandwidth.

[0108] Comparative Example 1. Preparation and luminescence properties of CdSe magic number clusters

[0109] The CdSe magic number clusters were prepared by the method described in Example 1. The absorption spectrum (UV) and emission spectrum (PL) of the CdSe magic number clusters are as Figure 3 shown. By comparing Figure 2 and Figure 3 it can be seen that the absorption spectra of the CdSe magic number clusters and the CdSe / ZnSe magic number clusters are the same, but the luminescence intensity of the CdSe / ZnSe magic number clusters prepared by the present invention is significantly enhanced compared with the binary CdSe magic number clusters, with a high quantum yield, overcoming the defects of the existing single-component CdSe magic number clusters in luminescence efficiency and surface sensitivity. The CdSe / ZnSe magic number clusters prepared by the present invention have good application prospects as blue light emission materials.

[0110] In summary, the present invention provides a method for preparing CdSe / ZnSe magic-number clusters with a core-shell structure. By adding a ZnSe induction-period sample to the CdSe magic-number clusters, the precursor compound of ZnSe decomposes into ZnSe monomers, and the ZnSe monomers coat the surface of the CdSe magic-number clusters to form CdSe / ZnSe magic-number clusters. The CdSe / ZnSe magic-number clusters of the present invention are prepared at 25 °C, and this process will not cause a red shift in the emission peak of the nanoclusters, ensuring the purity of the blue light. The CdSe / ZnSe magic-number clusters provided by the present invention are a blue-light emitting material with an emission wavelength at 450 - 465 nm, a full width at half maximum of less than 15 nm, and defect-state-free luminescence, providing possibilities for the application of II-VI semiconductor nanocrystals in optoelectronic devices.

Claims

1. A CdSe / ZnSe magic number cluster, characterized in that: It is a magic number cluster with a core-shell structure, where the CdSe magic number cluster serves as the core and is coated with a layer of ZnSe as the shell; the emission wavelength of the CdSe / ZnSe magic number cluster is 450 - 465 nm, and the full width at half maximum is less than 15 nm.

2. A method for preparing the CdSe / ZnSe magic number cluster according to claim 1, characterized in that: It includes the following steps: adding a ZnSe induction period sample to the CdSe magic number cluster, and obtaining the CdSe / ZnSe magic number cluster after the reaction; the temperature of the reaction is 25 °C; The preparation method of the CdSe magic number cluster includes the following steps: (1) React cadmium acetate dihydrate with oleylamine to obtain an oleylamine cadmium acetate precursor; (2) Mix and react the oleylamine cadmium acetate precursor with selenium powder to obtain a CdSe magic number cluster reaction stock solution; (3) Purify the CdSe magic number cluster reaction stock solution to obtain the CdSe magic number cluster; The preparation method of the ZnSe induction period sample includes the following steps: (a) Mix zinc acetate with oleylamine and react to obtain an oleylamine zinc acetate precursor; (b) Mix selenium powder with trioctylphosphine and react to obtain a trioctylphosphine selenium precursor; (c) Mix the trioctylphosphine selenium precursor and diphenylphosphine and add them to the oleylamine zinc acetate precursor for reaction to obtain the ZnSe induction period sample.

3. The method according to claim 2, characterized in that: The volume ratio of the CdSe magic number cluster to the ZnSe induction period sample is 1:

1.

4. The method according to claim 2, wherein: The reaction time is 0.5 - 10 h.

5. The method according to claim 4, characterized in that: The reaction time is 8 h.

6. According to the method described in claim 2, wherein: In step (1), the molar ratio of cadmium acetate dihydrate to oleylamine is 1:(10 - 15); And / or, in step (1), the reaction is to first react at 80 - 120 °C for 1 - 3 h, and then react at 120 - 140 °C for 1 - 3 h; And / or, in step (2), the molar ratio of the oleylamine cadmium acetate precursor to selenium powder is (1 - 4):1; And / or, in step (2), the reaction temperature is 80 - 140 °C, and the reaction time is 1 - 3 h.

7. According to the method described in claim 6, wherein: In step (1), the molar ratio of cadmium acetate dihydrate to oleylamine is 1:13; And / or, in step (1), the reaction is to first react at 80 °C for 1 h, and then react at 120 °C for 1 h; And / or, in step (1), the reaction is carried out under vacuum conditions; And / or, in step (2), the molar ratio of the oleylamine cadmium acetate precursor to selenium powder is 3:1; And / or, in step (2), the reaction temperature is 100 °C, and the reaction time is 2 h.

8. The method according to claim 2, characterized in that: In step (3), the purification method includes the following steps: (3.1) Add trioctylphosphine to the CdSe magic number cluster reaction stock solution to remove unreacted selenium; (3.2) Add absolute ethanol to the reaction solution obtained in step (3.1), shake well and centrifuge; (3.3) Add absolute ethanol to the solid obtained after centrifugation, shake well and centrifuge, and dry the obtained precipitate; (3.4) Redissolve the dried precipitate in oleylamine.

9. According to the method described in claim 8, wherein: In step (3.1), the volume ratio of the CdSe magic number cluster reaction stock solution to trioctylphosphine is (8 - 10):1; and / or, in step (3.1), after adding trioctylphosphine, stir at room temperature for 5 - 10 min; and / or, in step (3.2), the rotation speed of centrifugation is 8000 - 12000 r / min, and the centrifugation time is 2 - 10 min; and / or, in step (3.3), the rotation speed of centrifugation is 8000 - 12000 r / min, and the centrifugation time is 2 - 10 min; and / or, in step (3.4), the mass - volume ratio of the dried precipitate to oleylamine is (1 - 5) mg:1 mL.

10. The method according to claim 9, wherein: In step (3.1), the volume ratio of the CdSe magic number cluster reaction stock solution to trioctylphosphine is 10:1; and / or, in step (3.2), the rotation speed of centrifugation is 9000 r / min, and the centrifugation time is 5 min; and / or, in step (3.3), the rotation speed of centrifugation is 9000 r / min, and the centrifugation time is 5 min; and / or, in step (3.4), the mass - volume ratio of the dried precipitate to oleylamine is 5 mg:1 mL.

11. The method according to claim 2, wherein: In step (a), the molar ratio of zinc acetate to oleylamine is 1:(13 - 15); and / or, in step (a), the reaction temperature is 100 - 140 °C, and the reaction time is 1 - 3 h; and / or, in step (b), the molar ratio of selenium powder to trioctylphosphine is 1:(1 - 4); and / or, in step (b), the reaction temperature is 25 - 40 °C, and the reaction time is 0.5 - 1 h; and / or, in step (c), the molar ratio of the trioctylphosphine selenium precursor, oleylamine zinc acetate precursor, and diphenylphosphine is 1:(1 - 5):(1 - 2); and / or, in step (c), the reaction temperature is 120 - 200 °C, and the reaction time is 15 - 30 min.

12. The method according to claim 11, wherein: In step (a), the molar ratio of zinc acetate to oleylamine is 1:13.6; and / or, in step (a), the reaction temperature is 120 °C, and the reaction time is 1 h; and / or, in step (a), the reaction is carried out under vacuum conditions; and / or, in step (b), the molar ratio of selenium powder to trioctylphosphine is 1:2.2; and / or, in step (b), the reaction temperature is 40 °C, and the reaction time is 0.5 h; and / or, in step (b), the reaction is carried out in an inert gas atmosphere; and / or, in step (c), the molar ratio of the trioctylphosphine selenium precursor, oleylamine zinc acetate precursor, and diphenylphosphine is 1:4:1; and / or, in step (c), the reaction temperature is 160 °C, and the reaction time is 15 min.

13. Use of the CdSe / ZnSe magic number cluster according to claim 1 as a blue - light emitting material.

14. The use according to claim 13, wherein: The wavelength of the blue light is 450 - 465 nm.

15. The use according to claim 14, wherein: The wavelength of the blue light is 460 nm.

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