Method for synthesizing large-size monodisperse PbS quantum dots through multiple injection, PbS quantum dots and application of PbS quantum dots
Synthesis of PbS quantum dots by multiple injection methods solves the problem of difficulty in preparing large-sized monodispersed quantum dots in the prior art, and achieves the effect of absorption peaks exceeding 2000 nm. It is suitable for short-wave infrared photodetectors, and improves production efficiency and cost-effectiveness.
Patent Information
- Application Number
- CN202411823417.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-12
- Publication Date
- 2025-04-15
AI Technical Summary
The prior art is difficult to prepare large-size monodispersed PbS quantum dots with sizes exceeding 10 nm, making it difficult for its absorption peak to exceed 2000 nm, and cannot meet the needs of short-wave infrared photodetectors.
Multiple injection methods are used to synthesize PbS quantum dots. By controlling the injection amount and interval time of the sulfur precursor, the quantum dots are kept below the growth threshold, the formation of new crystal nuclei is reduced, and the precise growth and monodispersity of quantum dots are achieved.
Large-size monodispersed PbS quantum dots with a diameter greater than 10 nm were successfully prepared, and the absorption peak was controlled in the range of 1500-2300 nm. It is suitable for short-wave infrared photodetectors, and the utilization rate of precursors is improved and production costs are reduced.
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Figure CN119822404A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of synthesis of semiconductor quantum dots, and in particular to a method for preparing monodisperse PbS quantum dots with a size exceeding 10 nm. Background Art
[0002] Short-wavelength infrared (SWIR) image sensors have been widely used in different applications, such as medical imaging and machine vision, consumer electronics, and astronomy. Current commercial SWIR sensing materials for photodetector applications, including InGaAs (700-2600nm) and Ge (800-1800nm), require epitaxial growth on lattice-matched substrates, which is incompatible with complementary metal oxide semiconductor (CMOS) processing. Colloidal PbS quantum dots are used in short-wavelength infrared optical detectors due to their excellent optical properties, bandgap tunability, solution processability, and direct monolithic integration with silicon-based ROIC. However, due to the difficulty in growing large-sized PbS quantum dots with good monodispersity, the absorption peak of currently available PbS quantum dots (i.e., PbS CQDs) is difficult to exceed 2000nm. It is necessary to explore and improve the preparation methods for preparing large-sized PbS quantum dots.
[0003] The smaller the quantum dot dispersion, the more uniform the synthesized quantum dots are, resulting in better optical properties and easier formation of superlattice structures. In particular, quantum dots with a size dispersion of less than 10% are more conducive to the formation of superlattices, with narrower optical luminescence and absorption peaks, and purer chromaticity of luminescence. Hot injection, cation exchange, and hydrothermal methods are conventional methods for synthesizing PbS quantum dots. Since the growth of large-sized quantum dots usually requires a long reaction time and a high reaction temperature, it is difficult to avoid secondary nucleation and Ostwald ripening, resulting in poor size dispersion of synthesized large-sized quantum dots. At present, some studies have prepared PbS quantum dots with absorption peaks at 2150nm and 2300nm, but their size dispersion is greater than 20%, and high-quality monodispersed PbS quantum dots cannot be formed.
[0004] The diameter of quantum dots is proportional to the absorption peak. The larger the diameter, the longer the absorption peak. According to the conversion relationship between wavelength and absorption peak, the absorption peak corresponding to 10nm PbS quantum dots is usually 2000nm. The wavelength of 2000nm allows PbS quantum dots to be applied to the short-wave infrared band that previous studies could not reach. Recent studies have demonstrated monodisperse PbS quantum dots with an absorption peak range of 900nm to 1800nm by adjusting the reaction parameters during hydrothermal synthesis. However, the diameter of all batches of quantum dots obtained based on these syntheses is less than 10nm, which is still far below the exciton Bohr radius (16nm) of PbS quantum dots. PbS quantum dots with a diameter of more than 10nm have longer absorption wavelengths (absorption peaks), but the currently synthesized PbS quantum dots are far from approaching or reaching this size (exciton Bohr radius), which also makes it difficult for the absorption wavelength (absorption peak) to break through 2000nm. Therefore, it is still very difficult to synthesize large-sized, monodisperse PbS quantum dots. Summary of the invention
[0005] In view of the defects of the prior art, the present invention proposes a method for synthesizing large-sized, monodisperse PbS quantum dots by multiple injections, which can produce PbS quantum dots with a size of more than 10 nm and high-quality monodispersity.
[0006] The first aspect of the present invention discloses a method for synthesizing large-sized, monodisperse PbS quantum dots by multiple injections, comprising the following steps:
[0007] Providing N portions of sulfur precursors, wherein the solute of the sulfur precursors is (TMS)2S, and the solvent is 1-octadecene; N is a natural number greater than 1 and less than 8;
[0008] Providing a lead precursor, wherein the lead precursor is lead oleate prepared from lead oxide, 1-octadecene and oleic acid;
[0009] At a preset temperature, N portions of sulfur precursor are sequentially injected into the lead precursor, and the lead-sulfur ratio in the obtained PbS quantum dot mixed solution is 8:1; a preset reaction time is left between two adjacent injections;
[0010] The PbS quantum dot mixed solution is purified to obtain the desired PbS quantum dots.
[0011] As an optional solution, in the lead precursor, the molar ratio of lead oxide, 1-octadecene and oleic acid is 1:84:3 to 1:84:4.
[0012] As an optional solution, a lead precursor is provided, wherein the lead precursor is lead oleate prepared from lead oxide, 1-octadecene and oleic acid; specifically comprising:
[0013] Under an inert atmosphere, lead oxide is dissolved in a mixed solution of 1-octadecene and oleic acid;
[0014] The temperature of the mixture was raised to 130±5°C and vacuum was applied for 60±5 minutes to form a colorless and transparent lead oleate solution.
[0015] As an optional solution, at a preset temperature, N parts of sulfur precursor are sequentially injected into the lead precursor, and the lead-sulfur ratio in the obtained PbS quantum dot mixed solution is 8:1; specifically comprising:
[0016] At a preset temperature, injecting a first portion of sulfur precursor into a lead precursor, and reacting for a first preset reaction time to obtain a first portion of PbS quantum dot mixed solution;
[0017] Injecting a second portion of sulfur precursor into the first portion of the PbS quantum dot mixed solution, and reacting for a second preset reaction time to obtain a second portion of the PbS quantum dot mixed solution;
[0018] Similarly, injecting the Nth portion of sulfur precursor into the N-1th portion of the PbS quantum dot mixed solution, and reacting for a second preset time to obtain the Nth portion of the PbS quantum dot mixed solution;
[0019] The lead-sulfur ratio in the Nth PbS quantum dot mixed solution is 8:1.
[0020] As an optional solution, the first preset reaction time is greater than the second preset reaction time.
[0021] As an optional solution, the first preset reaction time is 20±2 minutes, the second preset reaction time is 12±2 minutes; and the preset temperature is 130±5°C.
[0022] As an optional solution, it also includes: after the Nth portion of sulfur precursor is injected for a preset reaction time, injecting a quencher into the PbS quantum dot mixed solution to perform a quenching reaction to achieve rapid cooling.
[0023] As an optional scheme, the purification operation includes: loading the PbS quantum dot reaction mixed solution into a centrifuge, and after centrifugal precipitation, removing the supernatant to obtain the desired PbS quantum dots; when the number of centrifugal precipitation is greater than one, adding an anti-solvent to precipitate the PbS quantum dots, and adding a positive solvent to promote the dissolution of the PbS quantum dots.
[0024] The second aspect of the present invention discloses a PbS quantum dot, which is synthesized by the method for synthesizing large-sized, monodisperse PbS quantum dots by multiple injections as described in the first aspect of the present invention or any optional solution;
[0025] The diameter of the PbS quantum dots is greater than 10 nm and has monodispersity.
[0026] The third aspect of the present invention discloses the application of the PbS quantum dots provided by the second aspect of the present invention in the field of short-wave infrared photoelectric detection.
[0027] The present invention has the following beneficial effects:
[0028] The PbS quantum dots synthesized by the method of the invention have a stable Tyndall effect.
[0029] The present invention injects sulfur precursors in small amounts multiple times and controls the Pb / S ratio in the quantum dot mixed solution, so that the quantum dots are always below the growth threshold, thereby reducing the formation of new crystal nuclei and making the reaction mainly focus on the growth of existing crystal nuclei, thereby achieving precise control of the size of quantum dots and obtaining large-sized, monodisperse quantum dots with a diameter greater than 10nm.
[0030] The invention can optimize the absorption characteristics of quantum dots by precisely controlling the size of quantum dots, and control the absorption peak within the short-wave infrared range of 1500-2300nm. In particular, the absorption peak above 2000nm can be applied to fields such as short-wave infrared photoelectric detection.
[0031] The present invention can improve the utilization rate of the precursor by multiple small-dose injections, can ensure that the precursor injected each time is effectively utilized, avoids the current situation of precursor waste in conventional synthesis methods, has lower costs, and is conducive to large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Figure 1 This is the XRD diagram of PbS quantum dots in the application case; the ordinate Intensity represents the diffraction peak intensity; the abscissa Theta represents the diffraction angle.
[0033] Figure 2 In the figure: (a) is a TEM image of PbS-1 quantum dots in the application case, and (b) is a size distribution diagram of PbS-1 quantum dots in the embodiment, wherein the ordinate Frequency represents the frequency and the abscissa Size represents the particle size of the quantum dots.
[0034] Figure 3 Middle: (a) is the TEM image of PbS-6 quantum dots in the application case, and (b) is the size distribution diagram of PbS-6 quantum dots in the application case.
[0035] Figure 4 Middle: (a) is the HRTEM image of PbS-1 quantum dots in the application case, and (b) is the schematic diagram of the interplanar spacing measurement of PbS-1 quantum dots in the application case.
[0036] Figure 5It is the normalized absorption spectrum of PbS-1 quantum dots to PbS-6 quantum dots in the application case; wherein the ordinate Absorbance represents the absorption peak, and the abscissa Wavelength represents the wavelength.
[0037] Figure 6 This is a real photo of the PbS-6 quantum dot sol used in the application case. DETAILED DESCRIPTION
[0038] The present invention discloses a method for synthesizing large-sized monodisperse PbS quantum dots by multiple injections, using a combination of bis(trimethylsilyl) sulfide ((TMS)2S) as a sulfur precursor and lead oxide as a lead precursor, and controlling the subsequent injection dosage of the sulfur precursor so that the sulfur precursor only contributes to the nucleation of the PbS quantum dots without growth. It can be understood that quantum dot nucleation refers to the initial stage of forming quantum dots in a solution, when atoms or molecules aggregate to form small clusters, which eventually develop into the core of the quantum dots; and growth refers to the process in which the quantum dot core gradually increases through the continuous deposition of atoms or molecules after the formation of the quantum dot core. The purpose of multiple injections in the present invention is to keep the quantum dots below the growth threshold at all times, so that the quantum dots are always in the nucleation stage, thereby obtaining large-sized quantum dots with better morphology. Usually, the injection times range from 2 to 7 times can meet the requirement below the above-mentioned growth threshold. After more than 7 times, the quantum dots will reach the growth conditions, and their morphology is not easy to control and the performance is not good.
[0039] The technical solution of the present invention is further described below in conjunction with embodiments and drawings.
[0040] The embodiment of the present invention discloses a method for synthesizing large-sized monodisperse PbS quantum dots by multiple injections, which mainly comprises the following steps:
[0041] S1, Preparation of sulfur precursor:
[0042] Six injections of sulfur precursors were prepared, wherein the solute of the sulfur precursors was (TMS)2S and the solvent was 1-octadecene. The concentration range of the sulfur precursor for the first injection was 13mg / ml~14mg / ml, and sulfur precursor No. 1 was obtained; the concentration range of the sulfur precursor for the second and third injections was 7mg / ml~8mg / ml, and sulfur precursor No. 2 was obtained; the concentration range of the fourth and fifth sulfur precursors was 11mg / ml~12mg / ml, and sulfur precursor No. 3 was obtained; the concentration range of the sixth sulfur precursor was 14mg / ml~15mg / ml, and sulfur precursor No. 4 was obtained. The above six dissolution operations obtained six sulfur precursor solutions, which were used for six injections in turn. Accurately controlling the concentration of the sulfur precursor can ensure that the quantum dots in the solution are below their growth threshold and no new nuclei are generated, so that the reaction is mainly concentrated on the growth of existing crystal nuclei. This process is crucial for the size and morphology control of PbS quantum dots.
[0043] It is worth noting that (TMS)2S is an active sulfur precursor that can provide sulfur atoms at a relatively low temperature, which is beneficial to controlling the growth of quantum dots. In a non-polar solvent such as 1-octadecene, (TMS)2S can exist stably, which helps to maintain the consistency of reaction conditions and avoid premature decomposition or reaction of the sulfur precursor. Therefore, the present invention uses (TMS)2S as a sulfur precursor, and the growth of quantum dots can be accurately controlled by adjusting its concentration in 1-octadecene and the number of injections, which is crucial for obtaining quantum dots of specific size and monodispersity.
[0044] S2, preparation of lead precursor:
[0045] Under an inert atmosphere (e.g., argon, nitrogen), lead oxide is dissolved in a mixed solution of 1-octadecene and oleic acid, wherein the molar ratio of lead oxide, 1-octadecene and oleic acid is 1:84:3 to 1:84:4, and then the mixture temperature is increased to 130±5° C. and vacuumed for 60±5 minutes to dry the solution to form a colorless and transparent lead oleate solution.
[0046] It is worth noting that, in the present invention, the preparation of the lead oleate solution uses a large amount of 1-octadecene solvent, which is beneficial to delay the maturation and growth of quantum dots. The vacuum degassing is mainly to remove impurity gases such as oxygen and water vapor in the system to prevent lead oleate from oxidizing, optimize the reaction conditions and enhance the stability of the reaction system.
[0047] It can be understood that there is no strict order between step S1 and step S2 in the present invention. Step S1 can be performed first, or step S2 can be performed first, or both steps can be performed simultaneously.
[0048] S3, Synthesis of PbS quantum dots:
[0049] The temperature is raised to 130±5°C, and the first sulfur precursor obtained in step S1 is quickly injected into the lead oleate solution prepared in step S2, i.e., the lead precursor. The lead oleate solution turns black within a few minutes after the sulfur precursor is injected, indicating that quantum dots are generated. The temperature is maintained at 130±5°C for 20±2 minutes to promote the reaction, and then the second, third, and fourth sulfur precursors are injected in sequence, with a time interval of 10±2 minutes between each injection to ensure that the sulfur precursor can fully react and nucleate.
[0050] Further, after the sixth injection of the sulfur precursor and the reaction is completed, 20 ml of a quenching agent such as cold isopropanol, cold hexane, cold toluene, cold methanol, etc. is injected to produce a quenching reaction, achieve rapid cooling, and obtain a PbS quantum dot mixed solution. It can be understood that the injection of alcohol substances is mainly to quickly stop the nucleation growth of quantum dots and prevent excessive growth from causing uncontrollable size dispersion.
[0051] In the process of multiple injections, the stable nucleation of PbS quantum dots can be achieved by injecting different concentrations of sulfur precursors at a fixed lead precursor concentration. It is worth noting that after six injections, the Pb / S ratio in the final PbS quantum dot mixed solution before purification must be 8:1.
[0052] S4, Purification of PbS quantum dots:
[0053] The PbS quantum dot mixed solution obtained in step S3 is placed in a centrifuge and rotated at 4000 rpm to remove impurities therein, and the precipitated nanocrystals are obtained after the centrifugation. During the reaction process, the color of the supernatant in the mixed solution can be used to determine whether the purification is completed. The more centrifugation times, the clearer the supernatant and the purer the quantum dots. The operation is completed when the supernatant color is almost transparent. Usually, the above centrifugation process is repeated 1 to 3 times. In this process, during the first centrifugation, isopropanol and acetone are directly added as anti-solvents to precipitate the quantum dots; in the subsequent process, toluene can be used as a positive solvent to dissolve the precipitated quantum dots, and then isopropanol and acetone are added as anti-solvents to precipitate the quantum dots again. After the purification is completed, the supernatant is removed to obtain a clean, impurity-free black solid of PbS quantum dots.
[0054] In a specific application case, 53uL of (TMS)2S was dissolved in 3ml of 1-octadecene to obtain a sulfur precursor No. 1 with a concentration of 13.16mg / ml; 20uL of (TMS)2S was dissolved in 2ml of 1-octadecene to prepare a sulfur precursor No. 2 with a concentration of 7.45mg / ml; 30uL of (TMS)2S was dissolved in 2ml of 1-octadecene to prepare a sulfur precursor No. 3 with a concentration of 11.18mg / ml; 40uL of (TMS)2S was dissolved in 2ml of 1-octadecene to prepare a sulfur precursor No. 4 with a concentration of 14.92mg / ml. 0.446g of lead oxide was dissolved in a mixed solution formed by 62.5ml of 1-octadecene and 2.5ml of oleic acid to obtain a lead oleate solution used as a lead precursor.
[0055] The prepared lead precursor is heated, and when its temperature reaches 135°C, the No. 1 sulfur precursor is quickly injected, and the reaction time is 20 minutes.
[0056] After the first sulfur precursor reacted for 20 minutes, a mixed solution containing PbS-1 quantum dot powder (referred to as "PbS-1 quantum dot mixed solution") was obtained. The second sulfur precursor was injected into the PbS-1 quantum dot mixed solution, and the reaction time (i.e., the interval time) was 12 minutes, and a mixed solution containing PbS-2 quantum dot powder (referred to as "PbS-2 quantum dot mixed solution") was obtained. Next, the second sulfur precursor was injected into the PbS-2 quantum dot mixed solution, and the reaction time was 12 minutes, and a mixed solution containing PbS-3 quantum dot powder (referred to as "PbS-3 quantum dot mixed solution") was obtained. The sulfur precursor No. 3 was injected into the PbS-3 quantum dot mixed solution, and the reaction time was 12 minutes to obtain a mixed solution containing PbS-4 quantum dot powder (referred to as "PbS-3 quantum dot mixed solution"); the sulfur precursor No. 3 was injected into the PbS-4 quantum dot mixed solution, and the reaction time was 12 minutes to obtain a mixed solution containing PbS-5 quantum dot powder (referred to as "PbS-3 quantum dot mixed solution"). The sulfur precursor No. 4 was injected into the PbS-5 quantum dot mixed solution, and the reaction time was 12 minutes to obtain a mixed solution containing PbS-6 quantum dot powder (referred to as "PbS-3 quantum dot mixed solution").
[0057] X-ray diffraction analysis of the synthesized PbS-6 quantum dot powder was performed. Figure 1 There are 9 obvious diffraction peaks. By comparing with the standard diffraction peak card of PbS (JCPDS No: 05-0592), it can be seen that the synthesized PbS quantum dots have (111), (200), (220), (311), (222), (400), (331), (420) and (422) crystal planes, which are consistent with the international standard PDF card, indicating that high-quality PbS quantum dots are obtained by the method of the present invention.
[0058] Combination Figure 2 (a) and Figure 2 As shown in (b), the high-resolution transmission electron microscopy (HRTEM) image and size distribution diagram of the PbS-1 quantum dots obtained by preliminary nucleation in the embodiment show that the PbS quantum dots at this size still have good monodispersity, with a size of 7.43±0.67nm, relatively uniform size, and good monodispersity.
[0059] Combination Figure 3 (a) and Figure 3 As shown in (b), the size of the PbS-6 quantum dots synthesized after six injections of sulfur precursor is relatively uniform and has good monodispersity, and the quantum dot size is 10.95±0.81nm.
[0060] like Figure 4As shown, the high-resolution transmission electron microscopy (HRTEM) image of PbS-6 quantum dots and the surface spacing measurement results show that the boundaries of the quantum dot lattice fringes are clear, and the surface spacing measurement results are 0.201nm and 0.171nm, which belong to the (220) and (222) crystal planes of the PbS cubic structure respectively.
[0061] like Figure 5 As shown, from the normalized absorption spectrum of PbS quantum dots, it can be seen that the first exciton absorption peak of PbS-6 is at 2180nm, and its absorption peak is in the short-wave band.
[0062] like Figure 6 As shown, from the actual photo of PbS-6 quantum dot sol, it can be seen that PbS-6 quantum dot sol has an obvious Tyndall effect.
[0063] In summary, the present invention proposes a method for synthesizing large-sized PbS quantum dots by multiple injections, by fixing the Pb / S ratio in the quantum dot mixed solution to 8:1, and controlling the amount of sulfur precursor precursor not to exceed the growth threshold. Multiple injections of a small amount of sulfur precursor can accurately control the growth of quantum dots. By multiple injections of a small amount of sulfur precursor, the quantum dots can be controlled to always be below the growth threshold, and the formation of new crystal nuclei can be reduced, so that the reaction is mainly concentrated on the growth of existing crystal nuclei, thereby achieving precise control of the size of quantum dots and avoiding the formation of overly large or uneven quantum dots. Moreover, by precisely controlling the size of quantum dots, the absorption characteristics of quantum dots can be optimized, especially for short-wave infrared (SWIR) photodetectors, an absorption peak exceeding 2000nm can be achieved.
[0064] In addition, in the traditional quantum dot synthesis method, a large amount of sulfur precursor with a high concentration is usually added at one time, which may result in only a part of the precursor participating in the growth of quantum dots, while the rest is not effectively utilized. The present invention adopts a method of multiple injections to reduce the waste of sulfur precursors. By multiple small-dose injections, it can be ensured that each added sulfur precursor is effectively utilized, thereby improving the overall precursor utilization rate, which is very important for large-scale production and cost reduction.
[0065] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A method for synthesizing large-sized, monodisperse PbS quantum dots by multiple injections, characterized in that: The following steps are involved: Providing N portions of sulfur precursors, wherein the solute of the sulfur precursors is (TMS)2S, and the solvent is 1-octadecene; N is a natural number greater than 1 and less than 8; Providing a lead precursor, wherein the lead precursor is lead oleate prepared from lead oxide, 1-octadecene and oleic acid; At a preset temperature, N portions of sulfur precursor are sequentially injected into the lead precursor, and the lead-sulfur ratio in the obtained PbS quantum dot mixed solution is 8:1; a preset reaction time is left between two adjacent injections; The PbS quantum dot mixed solution is purified to obtain the desired PbS quantum dots.
2. The method according to claim 1, characterized in that In the lead precursor, the molar ratio of lead oxide, 1-octadecene and oleic acid is 1:84:3 to 1:84:
4.
3. The method according to claim 1, characterized in that A lead precursor is provided, wherein the lead precursor is lead oleate prepared from lead oxide, 1-octadecene and oleic acid; specifically comprising: Under an inert atmosphere, lead oxide is dissolved in a mixed solution of 1-octadecene and oleic acid; The temperature of the mixture was raised to 130±5°C and vacuum was applied for 60±5 minutes to form a colorless and transparent lead oleate solution.
4. The method according to claim 1, characterized in that At a preset temperature, N parts of sulfur precursor are sequentially injected into the lead precursor, and the lead-sulfur ratio in the obtained PbS quantum dot mixed solution is 8:1; Specifically include: At a preset temperature, injecting a first portion of sulfur precursor into a lead precursor, and reacting for a first preset reaction time to obtain a first portion of PbS quantum dot mixed solution; Injecting a second portion of sulfur precursor into the first portion of the PbS quantum dot mixed solution, and reacting for a second preset reaction time to obtain a second portion of the PbS quantum dot mixed solution; Similarly, injecting the Nth portion of sulfur precursor into the N-1th portion of the PbS quantum dot mixed solution, and reacting for a second preset time to obtain the Nth portion of the PbS quantum dot mixed solution; The lead-sulfur ratio in the Nth PbS quantum dot mixed solution is 8:
1.
5. The method according to claim 1, characterized in that The first preset reaction time is greater than the second preset reaction time.
6. The method according to claim 5, characterized in that The first preset reaction time is 20±2 minutes, the second preset reaction time is 12±2 minutes; the preset temperature is 130±5°C.
7. The method according to claim 1, characterized in that Also includes: After the Nth sulfur precursor is injected for a preset reaction time, a quencher is injected into the PbS quantum dot mixed solution to perform a quenching reaction to achieve rapid cooling.
8. The method according to any one of claims 1 to 7, characterized in that: The purification operation includes: loading the PbS quantum dot reaction mixed solution into a centrifuge, and after centrifugal precipitation, removing the supernatant to obtain the desired PbS quantum dots; when the number of centrifugal precipitation is greater than one, adding an anti-solvent to precipitate the PbS quantum dots, and adding a positive solvent to promote the dissolution of the PbS quantum dots.
9. A PbS quantum dot, characterized in that: The method for synthesizing large-sized, monodisperse PbS quantum dots by multiple injections as described in any one of claims 1 to 8 is adopted; The diameter of the PbS quantum dots is greater than 10 nm and has monodispersity.
10. Apply the PbS quantum dots described in claim 9 in the field of short-wave infrared photoelectric detection.