Colloidal quantum dot and preparation method thereof

Abstract

The invention relates to the technical field of quantum dots, and discloses a colloidal quantum dot and a preparation method thereof.The preparation method of the colloidal quantum dot comprises the steps that a cesium-based precursor solution and a lead-based precursor solution are provided; respectively filtering the cesium-based precursor solution and the lead-based precursor solution; providing an isopropanol solvent and an n-hexane solvent, and mixing the isopropanol solvent, the n-hexane solvent and the filtered cesium-based precursor solution to form a pre-solution; injecting the filtered lead-based precursor solution into the pre-solution to form a mixed solution; performing primary centrifugal treatment on the mixed solution; providing an organic precursor solvent, dispersing the mixed solution after the first time of centrifugation into the organic precursor solvent, and then carrying out second time of centrifugation treatment; and providing a low-polarity solvent, and dispersing the mixed solution subjected to secondary centrifugation into the low-polarity solvent to obtain the colloidal quantum dots. The invention also provides the colloidal quantum dot prepared by the method. And the problem of strict temperature control of the existing hot injection method is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of quantum dots, and in particular to colloidal quantum dots and a preparation method thereof. Background Art

[0002] Compared with traditional perovskite thin film materials, all-inorganic perovskite quantum dot materials not only have excellent photoelectric properties due to their unique organic surface ligand interconnection structure and nanoscale grains, but also show better chemical and structural stability thanks to their inorganic chemical components and high surface energy.

[0003] However, most of the synthesis methods of all-inorganic perovskite quantum dots are hot injection methods. Since the reaction rate of metal ions and halogen sources is faster at higher temperatures, a constant reaction temperature needs to be maintained to obtain a uniform crystal structure. Therefore, if the existing hot injection method is used to synthesize all-inorganic perovskite quantum dot materials, the temperature and ambient atmosphere need to be strictly controlled. In addition, the current photoelectric conversion efficiency of all-inorganic perovskite quantum dots is limited and needs to be further improved and optimized. In view of the above problems, it is urgent to find a new method for preparing all-inorganic perovskite quantum dots. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the existing hot injection synthesis process has strict temperature control and the current photoelectric conversion efficiency of all-inorganic perovskite quantum dots is limited and needs to be further improved and optimized. The present invention provides a colloidal quantum dot and a preparation method thereof.

[0005] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions:

[0006] A method for preparing colloidal quantum dots comprises the following steps:

[0007] Providing a cesium-based precursor solution and a lead-based precursor solution;

[0008] filtering the cesium-based precursor solution and the lead-based precursor solution respectively;

[0009] Providing an isopropanol solvent and a n-hexane solvent, and mixing the isopropanol solvent, the n-hexane solvent and the filtered cesium-based precursor solution to form a pre-solution;

[0010] injecting the filtered lead-based precursor solution into the pre-solution to form a mixed solution;

[0011] The mixed solution is subjected to a first centrifugation treatment;

[0012] Providing an organic precursor solvent, dispersing the mixed solution after the first centrifugation into the organic precursor solvent and then performing a second centrifugation treatment;

[0013] A low-polarity solvent is provided, and the mixed solution after the second centrifugation is dispersed in the low-polarity solvent to obtain colloidal quantum dots.

[0014] Optionally, a cesium-based precursor solution and a lead-based precursor solution are provided including:

[0015] Providing cesium carbonate powder and lead iodide powder;

[0016] Providing a propionic acid solvent, using the propionic acid solvent as a first solvent;

[0017] Providing an n-butylamine solvent, an isopropanol solvent and a propionic acid solvent, and mixing the n-butylamine solvent, the isopropanol solvent and the propionic acid solvent to form a second solvent;

[0018] dissolving cesium carbonate powder in a first solvent to obtain a cesium-based precursor solution;

[0019] Lead iodide powder is dissolved in a second solvent to obtain a lead-based precursor solution.

[0020] Optional,

[0021] The concentration of the cesium-based precursor solution is 2 mol / L;

[0022] The concentration of the lead-based precursor solution is 0.6 mol / L.

[0023] Optionally, the volume ratio of the n-butylamine solvent, the isopropanol solvent and the propionic acid solvent is 1:1:1.

[0024] Optionally, filtering the cesium-based precursor solution and the lead-based precursor solution includes:

[0025] A polytetrafluoroethylene filter membrane with a pore size of 0.18 to 0.25 microns is provided, and the cesium-based precursor solution and the lead-based precursor solution are respectively passed through the polytetrafluoroethylene filter membrane for filtering treatment.

[0026] Optionally, the volume ratio of the isopropanol solvent, the n-hexane solvent, the filtered cesium-based precursor and the filtered lead-based precursor solution in the mixed solution is in the range of 1:9 to 1:12.

[0027] Optionally, the first centrifugation of the mixed solution includes:

[0028] When the mixed solution turns into brown flocs, the mixed solution is subjected to a first centrifugal treatment, wherein the first centrifugal speed ranges from 5000 to 8000 rpm and the centrifugal time is 1 to 2 minutes.

[0029] Optionally, the organic precursor solution is a precursor solution containing a trioctylphosphine oxide organic group;

[0030] The second centrifugal speed ranges from 5000 to 8000 rpm, and the centrifugal time is 1 to 2 minutes.

[0031] Optionally, the low polarity solvent includes toluene or chlorobenzene solution.

[0032] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical scheme: A colloidal quantum dot is also provided, and the colloidal quantum dot is prepared by the above-mentioned colloidal quantum dot preparation method.

[0033] Compared with the prior art, the advantages of the present invention are:

[0034] 1. The present invention innovatively proposes a method for preparing colloidal quantum dots by reprecipitating ligands with a high dielectric constant mixed solvent. Compared with the traditional hot injection method, the proposed method uses an environmentally friendly mixed solvent with a low boiling point and a short-chain ligand with a high dielectric constant. On the one hand, the synthesis temperature can be controlled at room temperature without strict temperature and atmosphere control; on the other hand, it can enhance the dielectric shielding effect in the perovskite quantum dots and weaken its dielectric confinement effect, thereby obtaining a smaller exciton binding energy.

[0035] In addition, the introduction of short-chain ligands can also reduce the surface potential barrier of quantum dots caused by alkyl groups, enhance electrical coupling, and thus promote the transport of carriers between adjacent quantum dots, ultimately achieving high photoelectric conversion efficiency. Finally, adding high-formation-energy TOPO organic groups during the centrifugation and dispersion of the final perovskite colloidal quantum dots can further enhance the interaction between the alkyl chains and quantum dots, thereby improving the monodispersity of the colloidal quantum dots and providing support for subsequent device preparation.

[0036] 2. The colloidal quantum dots provided by the present invention are of high quality, high performance and superiority.

[0037] Figure annotation:

[0038] Figure 1 A reference for the preparation method of colloidal quantum dots provided by the present invention Figure 1 .

[0039] Figure 2 A reference for the preparation method of colloidal quantum dots provided by the present invention Figure 2 .

[0040] Figure 3 A reference for the preparation method of colloidal quantum dots provided by the present invention Figure 3 .

[0041] Figure 4 This is a statistical diagram of the size distribution of colloidal quantum dots in quantum dot solution 1 prepared in Example 1 of the present invention.

[0042] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0043] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. DETAILED DESCRIPTION

[0044] Compared with traditional perovskite thin film materials, all-inorganic perovskite quantum dot materials, due to their unique organic surface ligand interconnected structure and nanoscale grains, not only have excellent optoelectronic properties, but also show better chemical and structural stability due to their inorganic chemical components and high surface energy. Quantum dots specifically refer to semiconductor particles with nanoscale sizes, usually between 2-10 nanometers, with quantum effect characteristics (such as quantized energy levels, size-dependent optical properties, etc.). They are called quantum dots because they exhibit quantum confinement effects, that is, when the particle size is reduced to the nanoscale, the movement of electrons and holes is restricted, thereby exhibiting unique optoelectronic properties different from bulk materials.

[0045] However, most of the synthesis methods of all-inorganic perovskite quantum dots are hot injection methods.

[0046] The main process of the hot injection method includes: first preparing a perovskite precursor solution. The precursor solution is heated to a certain temperature, and the metal source and halide source are quickly injected into the solvent by heating. After the metal source and halide source are injected, the solution reacts quickly to form perovskite crystals and quantum dots.

[0047] Since the reaction rate of metal ions with halogen sources is faster at higher temperatures, a constant reaction temperature needs to be maintained to obtain a uniform crystal structure. In addition, since the synthesis of perovskite quantum dots is usually very sensitive to oxygen and moisture, the ambient atmosphere needs to be strictly controlled to avoid material degradation.

[0048] Therefore, if the existing hot injection method is used to synthesize all-inorganic perovskite quantum dot materials, the temperature and ambient atmosphere need to be strictly controlled. In addition, the current photoelectric conversion efficiency of all-inorganic perovskite quantum dots is limited and needs to be further improved and optimized. In view of the above problems, it is urgent to find a new method for preparing all-inorganic perovskite quantum dots.

[0049] See also Figure 1 The first embodiment of the present invention provides a method for preparing colloidal quantum dots, comprising the following steps:

[0050] S1. providing a cesium-based precursor solution and a lead-based precursor solution;

[0051] S2, filtering the cesium-based precursor solution and the lead-based precursor solution respectively;

[0052] S3, providing an isopropanol solvent and a n-hexane solvent, and mixing the isopropanol solvent, the n-hexane solvent and the filtered cesium-based precursor solution to form a pre-solution;

[0053] S4, injecting the filtered lead-based precursor solution into the pre-solution to form a mixed solution;

[0054] S5, performing a first centrifugal treatment on the mixed solution;

[0055] S6, providing an organic precursor solvent, dispersing the mixed solution after the first centrifugation into the organic precursor solvent, and then performing a second centrifugation treatment;

[0056] S7. Provide a low-polarity solvent, and disperse the mixed solution after the second centrifugation into the low-polarity solvent to obtain colloidal quantum dots.

[0057] It can be understood that in this embodiment, a cesium-based (Cs + ) and lead-based (Pb 2+ ) precursor solution. + ) and lead-based (Pb 2+ ) precursor solution is the basis for the formation of perovskite quantum dots. + ) and lead ions (Pb 2+ ) react with halide ions in solution to form the basis of the perovskite structure. During the synthesis process, they are the main source of reaction and ensure that the final perovskite quantum dots have a high-quality crystal structure.

[0058] Further, the filtration treatment is to remove large particle impurities in the cesium-based and lead-based precursor solutions to ensure the purity and uniformity of the solutions. It should be understood that in the mixed solution formed in this embodiment, the ligands and solvents with high dielectric constants are adjusted. Solvents with high dielectric constants (such as propionic acid, isopropanol, etc.) help to enhance the electrical shielding effect between quantum dots, reduce the interaction between charges, and thus reduce the exciton binding energy.

[0059] Furthermore, the first centrifugation is to separate the formed quantum dots, and an organic precursor solution is added before the second centrifugation, wherein the organic groups of the organic precursor help to further strengthen the interaction ability between the alkyl chain and the quantum dots, thereby improving the monodispersity of the colloidal quantum dots.

[0060] Furthermore, in this embodiment, a low-polarity solvent is provided, and short-chain ligands are present in the low-polarity solvent, specifically shorter alkyl groups or organic groups with low polarity, and short-chain ligands are introduced. Short-chain ligands can reduce the surface barrier caused by longer alkyl chains, improve the conductivity and photoelectric conversion efficiency of quantum dots. In addition, the second centrifugation can further purify the quantum dots, remove excess solvents and by-products, and ultimately ensure that higher purity quantum dots are obtained.

[0061] It should be understood that this embodiment innovatively proposes a method for preparing colloidal quantum dots by reprecipitating ligands with a high dielectric constant mixed solvent. Compared with the traditional hot injection method, the proposed method uses an environmentally friendly, low-boiling-point mixed solvent and a short-chain ligand with a higher dielectric constant. On the one hand, the synthesis temperature can be controlled at room temperature without strict temperature and atmosphere control; on the other hand, it can enhance the dielectric shielding effect in the perovskite quantum dots and weaken its dielectric confinement effect, thereby obtaining a smaller exciton binding energy.

[0062] It should be noted that the colloidal quantum dots in this embodiment are all-inorganic perovskite quantum dots, which will not be described in detail below.

[0063] Specifically, see Figure 2 In the above step S1, providing a cesium-based precursor solution and a lead-based precursor solution comprises:

[0064] S11, providing cesium carbonate powder and lead iodide powder;

[0065] S12, providing a propionic acid solvent, using the propionic acid solvent as a first solvent;

[0066] S13, providing an n-butylamine solvent, an isopropanol solvent, and a propionic acid solvent, and mixing the n-butylamine solvent, the isopropanol solvent, and the propionic acid solvent to form a second solvent;

[0067] S14, dissolving cesium carbonate powder in a first solvent to obtain a cesium-based precursor solution;

[0068] S15, dissolving the lead iodide powder in a second solvent to obtain a lead-based precursor solution.

[0069] It should be understood that the main chemical raw materials in this example are cesium carbonate (Cs2CO3) and lead iodide (PbI2). These two chemicals are the basic precursors for the synthesis of perovskite quantum dots. Cesium carbonate provides cesium ions (Cs + ), while lead iodide provides lead ions (Pb 2 + ). These two metal ions can combine with the iodide ions (I-) in lead iodide (PbI2) to form the key components of the perovskite structure.

[0070] Specifically, in step S12, propionic acid (PrAc) in the first solvent is used as a solvent, mainly to dissolve cesium carbonate powder. The polarity of propionic acid can effectively dissolve cesium carbonate and is compatible with the subsequent solvent system, providing a suitable solvent environment for the preparation of the precursor solution.

[0071] Further, in steps S14 and S15: n-butylamine (BuAm) can help improve the solubility of the lead compound and help adjust the pH of the solution. Isopropyl alcohol (IPA) can provide a certain polarity to help dissolve the lead source and optimize the stability of the solution. Propionic acid (PrAc) is a solvent for dissolving cesium carbonate and is also one of the components of the solvent in this solution.

[0072] The concentration of the cesium-based precursor solution is 2 mol / L; the concentration of the lead-based precursor solution is 0.6 mol / L.

[0073] In the above step S13, the volume ratio of the n-butylamine solvent, the isopropanol solvent and the propionic acid solvent is 1:1:1. The purity of the n-butylamine solvent, the isopropanol solvent and the propionic acid solvent is greater than 99%.

[0074] The second solution is formed by mixing n-butylamine solution, isopropanol solvent and propionic acid solvent in a volume ratio of 1:1:1. The volume ratio of the three solutions is specifically regulated and designed to optimize the solubility and reactivity of the second solution, which is helpful to dissolve the lead iodide powder.

[0075] Further, in steps S14 and S15, the obtained cesium-based precursor solution and lead-based precursor solution respectively form key components of the perovskite structure. It should be understood that the cesium-based precursor solution contains cesium ions (Cs + ), the lead-based precursor solution contains lead ions (Pb 2+ ) and iodide ion (I - ).

[0076] It can be understood that in this embodiment, cesium-based and lead-based precursor solutions are prepared, and the cesium-based and lead-based precursor solutions will react to form the core structure of perovskite quantum dots in the subsequent synthesis process. The synthesis step of the precursor solution uses different solvents to optimize solubility, stability and reaction conditions, thereby providing an ideal chemical environment for the synthesis of perovskite quantum dots. These solutions play a vital role in the subsequent mixing and reaction, ensuring the quality and performance of perovskite quantum dots.

[0077] Specifically, filtering the cesium-based precursor solution and the lead-based precursor solution includes:

[0078] A polytetrafluoroethylene filter membrane with a pore size of 0.18 to 0.25 microns is provided, and the cesium-based precursor solution and the lead-based precursor solution are respectively passed through the polytetrafluoroethylene filter membrane for filtering treatment.

[0079] It should be understood that the role of the polytetrafluoroethylene (PTFE) filter membrane is to remove large particle impurities in the precursor solution to ensure the purity and uniformity of the solution. Through filtration, particles and impurities that may exist in the solution can be removed to prevent them from having adverse effects on subsequent quantum dot synthesis.

[0080] Specifically, the volume ratio of the isopropanol solvent, the n-hexane solvent, the filtered cesium-based precursor and the filtered lead-based precursor solution in the mixed solution is in the range of 1:9 to 1:12. It should be understood that the mixed solution is obtained by regulating the ratio of the isopropanol solvent, the n-hexane solvent, the cesium-based precursor and the lead-based precursor. Among them, the high dielectric constant solvent in the mixed solution helps to enhance the electric shielding effect between quantum dots, reduce the interaction between charges, and thus reduce the exciton binding energy.

[0081] Specifically, in the above step S5, the first centrifugal treatment of the mixed solution includes:

[0082] When the mixed solution turns into brown flocs, the mixed solution is subjected to a first centrifugal treatment, wherein the first centrifugal speed ranges from 5000 to 8000 rpm and the centrifugal time is 1 to 2 minutes.

[0083] It should be understood that the liquid turning into brown flocs indicates that quantum dots have begun to form. The first centrifugation is to remove unreacted solvent and other possible dissolved substances, and to separate the formed quantum dots.

[0084] Furthermore, after the first centrifugation, the mixed solution can be dissolved in an organic precursor solution for a second centrifugation. The organic precursor solution is a precursor solution containing trioctylphosphine oxide organic groups. It should be understood that the addition of high formation energy TOPO organic groups during the final perovskite colloidal quantum dot centrifugation and dispersion process can further enhance the interaction ability between the alkyl chain and the quantum dots, thereby improving the monodispersity of the colloidal quantum dots and providing support for subsequent device preparation.

[0085] Specifically, the second centrifugal treatment is performed at a second centrifugal speed ranging from 5000 to 8000 rpm and a centrifugal duration of 1 to 2 minutes. It should be understood that the second centrifugation is to further purify the quantum dots, remove excess solvent and byproducts, and ensure that higher purity quantum dots are obtained.

[0086] Furthermore, in this embodiment, the low polarity solvent includes toluene or chlorobenzene solution. Specifically, the mixed solution after two centrifugations will be redispersed into a low polarity solvent. Specifically, the dispersion process can adopt mechanical stirring or ultrasonic dispersion method. Finally, colloidal quantum dots are obtained. It should be understood that the present invention, in response to the problems existing in the above all-inorganic perovskite quantum dots, has developed a method for preparing colloidal quantum dots by reprecipitation of ligands in a high dielectric constant mixed solvent. On the one hand, the dielectric constant of the ligand in the mixed solvent is regulated to reduce the exciton binding energy of the material; on the other hand, the alkyl chain of the ligand in the mixed solvent is optimized to promote electrical coupling and carrier transport, thereby forming high-quality and high-performance colloidal quantum dots.

[0087] The present invention also provides a colloidal quantum dot, which is prepared by the colloidal quantum dot preparation method as described above. The colloidal quantum dot provided in this embodiment has the same beneficial effects as the colloidal quantum dot preparation method, so no further details are given here.

[0088] Example 1

[0089] In this example, see Figure 1 , Figure 2 and Figure 3 , the specific operations are:

[0090] At room temperature, cesium carbonate (Cs2CO3) powder was dissolved in propionic acid (PrAc), and lead iodide (PbI2) powder was dissolved in a mixed solvent of n-butylamine (BuAm), isopropyl alcohol (IPA) and propionic acid (PrAc) (volume ratio of 1:1:1), and mixed thoroughly until the solution was clear, thereby obtaining cesium (Cs+) and lead (PbI2) 2+ ) precursor solution;

[0091] The above precursor solutions were filtered using a polytetrafluoroethylene filter membrane (PTFE) with a pore size of 0.22 μm; 2+ The precursor solution was quickly injected into a mixed solution containing Cs+ precursor solution, isopropyl alcohol (IPA) and n-hexane (HEX). After the solution turned into brown flocs (within a few seconds), the residual solvent was removed by centrifugation at a speed of 6000 rpm for 1 minute.

[0092] The quantum dots after the centrifugation are redispersed in a precursor containing a trioctylphosphine oxide (TOPO) organic group, and a second centrifugation is performed at a speed of 6000 rpm for 1 minute.

[0093] The above-mentioned quantum dots after centrifugation are dispersed again in a low-polarity solvent such as toluene or chlorobenzene, and are fully mixed to form a high-quality all-inorganic perovskite quantum dot solution 1.

[0094] Experimental Example 1 Size distribution statistics of the quantum dot solution 1 prepared in Example 1

[0095] 1.1 Test operation

[0096] The size distribution of the quantum dot solution 1 prepared in Example 1 was statistically analyzed using a transmission electron microscope. The size distribution statistics are shown in FIG. Figure 4 .

[0097] 1.2 Results Analysis

[0098] See also Figure 4 It can be seen that the average size of the quantum dot solution 1 prepared in Example 1 is 7.92 nm. The colloidal quantum dots have high monodispersity and excellent performance.

[0099] The above is a detailed introduction to a colloidal quantum dot preparation method and colloidal quantum dots disclosed in an embodiment of the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for general technical personnel in the field, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention. Any modifications, equivalent substitutions and improvements made within the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing colloidal quantum dots, characterized in that: The following steps are involved: Providing a cesium-based precursor solution and a lead-based precursor solution; filtering the cesium-based precursor solution and the lead-based precursor solution respectively; Providing an isopropanol solvent and a n-hexane solvent, and mixing the isopropanol solvent, the n-hexane solvent and the filtered cesium-based precursor solution to form a pre-solution; injecting the filtered lead-based precursor solution into the pre-solution to form a mixed solution; The mixed solution is subjected to a first centrifugation treatment; Providing an organic precursor solvent, dispersing the mixed solution after the first centrifugation into the organic precursor solvent and then performing a second centrifugation treatment; A low-polarity solvent is provided, and the mixed solution after the second centrifugation is dispersed in the low-polarity solvent to obtain colloidal quantum dots.

2. The method for preparing colloidal quantum dots according to claim 1, characterized in that: Cesium-based precursor solutions and lead-based precursor solutions are provided including: Providing cesium carbonate powder and lead iodide powder; Providing a propionic acid solvent, using the propionic acid solvent as a first solvent; Providing an n-butylamine solvent, an isopropanol solvent and a propionic acid solvent, and mixing the n-butylamine solvent, the isopropanol solvent and the propionic acid solvent to form a second solvent; dissolving cesium carbonate powder in a first solvent to obtain a cesium-based precursor solution; Lead iodide powder is dissolved in a second solvent to obtain a lead-based precursor solution.

3. The method for preparing colloidal quantum dots according to claim 2, characterized in that: The concentration of the cesium-based precursor solution is 2 mol / L; The concentration of the lead-based precursor solution is 0.6 mol / L.

4. The method for preparing colloidal quantum dots according to claim 2, characterized in that: The volume ratio of the n-butylamine solvent, the isopropanol solvent and the propionic acid solvent is 1:1:

1.

5. The method for preparing colloidal quantum dots according to claim 1, characterized in that: The filtration process of the cesium-based precursor solution and the lead-based precursor solution includes: A polytetrafluoroethylene filter membrane with a pore size of 0.18 to 0.25 microns is provided, and the cesium-based precursor solution and the lead-based precursor solution are respectively passed through the polytetrafluoroethylene filter membrane for filtering treatment.

6. The method for preparing colloidal quantum dots according to claim 1, characterized in that: The volume ratio of the isopropanol solvent, the n-hexane solvent, the filtered cesium-based precursor and the filtered lead-based precursor solution in the mixed solution is in the range of 1:9 to 1:

12.

7. The method for preparing colloidal quantum dots according to claim 1, characterized in that: The first centrifugation of the mixed solution includes: When the mixed solution turns into brown flocs, the mixed solution is subjected to a first centrifugal treatment, wherein the first centrifugal speed ranges from 5000 to 8000 rpm and the centrifugal time is 1 to 2 minutes.

8. The method for preparing colloidal quantum dots according to claim 1, characterized in that: The organic precursor solution is a precursor solution containing trioctylphosphine oxide organic groups; The second centrifugal speed in the second centrifugal treatment is in the range of 5000 to 8000 rpm, and the centrifugal time is 1 to 2 minutes.

9. The method for preparing colloidal quantum dots according to claim 1, characterized in that: The low polarity solvent includes toluene or chlorobenzene solution.

10. A colloidal quantum dot, characterized in that: The colloidal quantum dots are prepared by the colloidal quantum dot preparation method as described in any one of claims 1 to 9.

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