Quantum dot preparation method

Abstract

The invention provides a preparation method of quantum dots. The preparation method comprises the following steps: S1, preparing a first mixture containing fatty acid silver, optional fatty amine and a non-coordination solvent; s2, mixing the first mixture with a first sulfur precursor, and carrying out heating reaction in a container at a first reaction temperature for a first time to generate silver sulfide nanoparticles; s3, continuously adding an indium precursor and a second sulfur precursor into the container at a second reaction temperature, and reacting for a second time; s4, continuously adding a gallium precursor and a third sulfur precursor into the container at a third reaction temperature, and reacting for a third time, wherein the third reaction temperature is higher than the second reaction temperature; and S5, the third reaction temperature is increased to the fourth reaction temperature for alloying, the AgInGaS quaternary alloy quantum dots are obtained, and the first time is smaller than or equal to 60 seconds. According to the preparation method, a uniform quaternary alloy can be formed, so that high quantum yield and narrow fluorescence half-peak width are realized.

Description

Technical Field

[0001] The present disclosure relates to the technical field of quantum dots, and in particular, to a method for preparing quantum dots. Background Art

[0002] Among all nanomaterials, semiconductor colloidal quantum dots have attracted wide attention in the scientific community due to their excellent optical properties, such as high fluorescence quantum yield, broad absorption bandwidth, narrow emission peak, good optical stability, etc. In the fields of biological labeling and imaging, light-emitting diodes, and lasers, quantum dot research has become a hot topic in each field. Especially in the field of displays (quantum dot TVs), quantum dots have higher color gamut and higher color resolution, and have been actually applied. As quantum dot technology moves from scientific research to application, for cadmium-containing quantum dots, people are increasingly concerned about the dangers they pose to human health and the environment. Therefore, the European Union has introduced relevant regulations requiring the cadmium content in consumer electronics to be less than 100 ppm. Therefore, the development of high-performance cadmium-free quantum dots, especially InP-based quantum dots, has become a research hotspot in the industrial and academic fields. However, the blue light absorption of InP-based quantum dots is relatively low, making it difficult to be applicable to display scenarios with high requirements for quantum dot blue light absorption, such as AR / VR, etc. Compared with InP-based quantum dots, AgInGaS quaternary alloy quantum dots have higher blue light absorption and have gradually received extensive attention in recent years. Summary of the Invention

[0003] The purpose of the present disclosure is to provide a method for preparing quantum dots to improve the optical parameters of AIGS quantum dots, such as quantum yield and fluorescence full width at half maximum.

[0004] According to the first aspect of the present disclosure, a method for preparing quantum dots is provided. The preparation method includes: S1: Prepare a first mixture containing silver fatty acid, optional fatty amine, and non-coordinating solvent; S2: Mix the first mixture and a first sulfur precursor, and heat and react in a container at a first reaction temperature for a first time to generate silver sulfide nanoparticles; S3: Continuously add an indium precursor and a second sulfur precursor to react for a second time in the container at a second reaction temperature; S4: Continuously add a gallium precursor and a third sulfur precursor to react for a third time in the container at a third reaction temperature, and the third reaction temperature is higher than the second reaction temperature; S5: Raise the third reaction temperature to a fourth reaction temperature for alloying to obtain AgInGaS quaternary alloy quantum dots, and the first time is less than or equal to 60 seconds.

[0005] Further, the second time is 1 - 5 minutes, and preferably, the third time is 5 - 30 minutes.

[0006] Further, mix silver acetate, optional fatty acid, fatty amine, and 1-octadecene, heat to dissolve, and obtain the first mixture after exhausting gas.

[0007] Furthermore, the fatty acid is oleic acid or a saturated fatty acid containing 8 - 18 carbon atoms.

[0008] Furthermore, the first, second, and third sulfur precursors are selected from one or more of sulfur-1-octadecene, trialkylphosphine sulfide, sulfur-fatty amine, metal diethyldithiocarbamate, thiourea, and mercaptan, provided that the first sulfur precursor does not contain metal diethyldithiocarbamate.

[0009] Furthermore, the indium precursor is selected from one or more of indium fatty acid with 8 - 18 carbon atoms, a mixed solution of indium fatty acid and indium halide-oleylamine, bis(diethyldithiocarbamato)indium halide, or indium diethyldithiocarbamate.

[0010] Furthermore, the gallium precursor is selected from one or more of gallium fatty acid with 8 - 18 carbon atoms, a mixed solution of gallium fatty acid and gallium acetylacetonate-oleylamine, a mixed solution of gallium fatty acid and gallium halide-oleylamine, bis(diethyldithiocarbamato)gallium halide, or gallium diethyldithiocarbamate.

[0011] Furthermore, the first reaction temperature is 50 - 150 °C, and the second reaction temperature is 150 - 220 °C; preferably, the third reaction temperature is 180 - 220 °C, and the fourth reaction temperature is 250 - 300 °C.

[0012] Furthermore, the fatty amine is selected from oleylamine or a saturated fatty amine containing 8 - 18 carbon atoms.

[0013] Furthermore, the full width at half maximum of the fluorescence of the AgInGaS quaternary alloy quantum dots is less than 40 nm, and the fluorescence quantum yield is greater than or equal to 60%.

[0014] Furthermore, the molar ratio of the silver element of silver fatty acid to the sulfur element of the first sulfur precursor is (5:1) - (1:5).

[0015] Furthermore, the molar ratio between the silver element of silver fatty acid and the indium element of the indium precursor is (3:1) - (1:3), and the molar ratio between the indium element of the indium precursor and the gallium element of the gallium precursor is (1:1) - (1:5).

[0016] By applying the above technical solution, through controlling the reaction activity of the precursor substances and understanding the essence of the reaction, a synthetic idea similar to a coating shell is constructed to prepare the quantum dot core, thereby forming a uniform quaternary alloy, and further achieving a high quantum yield and a narrow full width at half maximum of fluorescence. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings forming a part of this application are used to provide a further understanding of the present disclosure. The schematic embodiments and descriptions thereof of the present disclosure are used to explain the present disclosure and do not constitute an improper limitation to the present disclosure. In the drawings:

[0018] Figure 1 This is the ultraviolet-visible absorption spectrum of Example 1 of the present disclosure.

[0019] Figure 2 This is the fluorescence emission spectrum of Example 1 of the present disclosure. Detailed implementation manners

[0020] It should be noted that the following detailed description is illustrative and is intended to provide further description of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0021] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances for the embodiments of the present application described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices. The "optional" substances below include that the substance may be present or may not be present.

[0022] The inventor believes that the traditional synthesis method of AgInGaS quaternary alloy quantum dots is to inject an S precursor into Ag, In, and Ga precursors at a certain temperature, which will result in non-uniform composition of AgInGaS quaternary alloy quantum dots and at the same time there are by-product nanoparticles such as Ag2S and AgInS2, which means that the activity of silver ions is the highest, followed by indium ions, and finally gallium ions. Therefore, we guess that the core of the AgInGaS quaternary alloy quantum dot may be Ag2S, followed by AgInS2, and finally Ga2S3. That is to say, the AgInGaS quaternary alloy quantum dots prepared by the traditional method may essentially be an Ag2S / AgInS2 / Ga2S3 core-shell structure.

[0023] Based on the above analysis, the present application proposes a new method for preparing AgInGaS quaternary alloy quantum dots. The preparation method includes: S1: preparing a first mixture containing silver fatty acid, optional fatty amine and non-coordinating solvent; S2: mixing the first mixture with a first sulfur precursor, heating and reacting in a container at a first reaction temperature for a first time to generate silver sulfide nanoparticles; S3: continuously adding an indium precursor and a second sulfur precursor in the container and reacting for a second time at a second reaction temperature; S4: continuously adding a gallium precursor and a third sulfur precursor in the container and reacting for a third time at a third reaction temperature, where the third reaction temperature is greater than the second reaction temperature; S5: raising the third reaction temperature to a fourth reaction temperature for alloying to obtain AgInGaS quaternary alloy quantum dots, and the first time is less than or equal to 60 seconds. The inventors speculate that AgS2 nanoparticles are first formed in S2, an AgInS2 shell layer is formed in S3, and at the same time, Ag in the AgS2 nanoparticles diffuses into the AgInS2 shell layer; a Ga2S3 shell layer is formed in S4, and in S5, Ag and In inside the nanoparticles formed in S4 diffuse into the Ga2S3 shell layer, thereby forming a uniform quaternary alloy, and further achieving a high quantum yield and a narrow fluorescence full width at half maximum.

[0024] It should be noted that the indium precursor and the second sulfur precursor can be one substance with both indium and sulfur present, such as indium diethyldithiocarbamate; the gallium precursor and the third sulfur precursor can also be one substance with both gallium and sulfur present, such as gallium diethyldithiocarbamate.

[0025] In some embodiments, the second time is greater than the first time. In some embodiments, considering the reactivity of the precursors, the second time is 1 - 5 minutes. In some embodiments, the third time is 5 - 30 minutes. In some embodiments, in order to promote alloying, the third time is greater than or equal to the second time.

[0026] In some embodiments, the non-coordinating solvent is a common solvent in the art, such as 1-octadecene, alkane, petrolatum, etc.

[0027] In some embodiments, silver acetate, optional fatty acid, fatty amine and 1-octadecene are mixed, heated to dissolve, and the first mixture is obtained after exhausting air.

[0028] In some embodiments, the fatty acid is oleic acid or a saturated fatty acid containing 8 - 18 carbon atoms. The fluorescence peak position can be regulated by adjusting the C chain length of the fatty acid.

[0029] In some embodiments, the first, second, and third sulfur precursors are selected from one or more of sulfur-1-octadecene, trialkylphosphine sulfide, sulfur-fatty amine, metal diethyldithiocarbamate, thiourea, and mercaptan, provided that the first sulfur precursor does not contain metal diethyldithiocarbamate. "Sulfur-1-octadecene" and "sulfur-fatty amine" refer to dispersions formed by dispersing sulfur in 1-octadecene and fatty amine, respectively.

[0030] In some embodiments, the number of carbon atoms in silver fatty acid is 2-18.

[0031] In some embodiments, the indium precursor is selected from one or more of indium fatty acids with 8-18 carbon atoms, a mixed solution of indium fatty acid and indium halide-oleylamine, indium bis(diethyldithiocarbamate) halide (such as InCl(DDTC)2), or indium diethyldithiocarbamate. The fluorescence peak position is regulated by adjusting the C-chain length of indium fatty acid. "Indium halide-oleylamine" refers to a dispersion formed by dispersing indium halide in oleylamine. The following "gallium halide-oleylamine" and "gallium acetylacetonate-oleylamine" are for reference.

[0032] In some embodiments, the gallium precursor is selected from one or more of gallium fatty acids with 8-18 carbon atoms, a mixed solution of gallium fatty acid and gallium acetylacetonate-oleylamine, a mixed solution of gallium fatty acid and gallium halide-oleylamine, gallium bis(diethyldithiocarbamate) halide (such as GaCl(DDTC)2), or gallium diethyldithiocarbamate. The fluorescence peak position is regulated by adjusting the C-chain length of gallium fatty acid.

[0033] In some embodiments, the first reaction temperature < the second reaction temperature < the third reaction temperature < the fourth reaction temperature. The reaction temperature in the reaction involving a precursor with high reactivity can be relatively lower. In some embodiments, the second reaction temperature, the third reaction temperature, and the fourth reaction temperature are all greater than or equal to 200 °C. In some embodiments, the first reaction temperature is 50-150 °C. In some embodiments, the second reaction temperature is 150-220 °C. In some embodiments, the third reaction temperature is 180-220 °C. In some embodiments, the fourth reaction temperature is 250-300 °C.

[0034] In some embodiments, the fatty amine is selected from oleylamine or a saturated fatty amine containing 8-18 carbon atoms. The fatty amine can undergo a complexation reaction with the metal salt in the precursor, improving the activity of the precursor and promoting the reaction.

[0035] In some embodiments, in the reaction using gallium diethyldithiocarbamate Ga(DDTC)3 or indium diethyldithiocarbamate In(DDTC)3 as the precursor, the fatty amine can promote the decomposition of DDTC - of.

[0036] In some embodiments, the full width at half maximum (FWHM) of the fluorescence of the AgInGaS quaternary alloy quantum dots is less than 40 nm, and the fluorescence quantum yield is greater than or equal to 60%. In some embodiments, the FWHM of the fluorescence of the AgInGaS quaternary alloy quantum dots is greater than or equal to 30 nm. In some embodiments, the fluorescence quantum yield of the AgInGaS quaternary alloy quantum dots is 70 - 75%. In some embodiments, the fluorescence peak position of the AgInGaS quaternary alloy quantum dots is 500 - 600 nm. In some embodiments, the fluorescence peak position of the AgInGaS quaternary alloy quantum dots is 520 - 560 nm.

[0037] In some embodiments, the molar ratio of silver element in silver fatty acid to sulfur element in the first sulfur precursor is (5:1) - (1:5). In some embodiments, the molar ratio of silver element in silver fatty acid to sulfur element in the first sulfur precursor is greater than 1. In some embodiments, the molar ratio of silver element in silver fatty acid to sulfur element in the first sulfur precursor is (5:1) - (1:1).

[0038] Changing the ratios of silver element, indium element, and gallium element can adjust the fluorescence peak position. In some embodiments, the molar ratio between silver element in silver fatty acid and indium element in the indium precursor is (3:1) - (1:3), and the molar ratio between indium element in the indium precursor and gallium element in the gallium precursor is (1:1) - (1:5).

[0039] In the following, the embodiments are described in more detail with reference to specific examples. However, they are exemplary instances of the present disclosure, and the present disclosure is not limited thereto.

[0040] Example 1:

[0041] Take 0.5 mmol of silver acetate, 20 g of ODE, and 10 mL of oleylamine in a 100 mL three-necked flask. Raise the temperature to 150 °C, purge with nitrogen for 10 min, let it return to room temperature, inject 1 mL of 0.2 mmol / mL sulfur-oleylamine solution, react for 30 s, then quickly add 0.1 mmol of In(DDTC)3-ODE suspension and 0.4 mmol of indium chloride-oleylamine solution, react for 3 min, then raise the temperature to 200 °C, add 0.8 mmol of Ga(DDTC)3-ODE suspension and 0.4 mmol of gallium chloride-oleylamine solution, react for 10 min, raise the temperature to 280 °C, react for 30 min, and then stop the reaction.

[0042] Example 2:

[0043] Take 0.5 mmol silver acetate, 20 g ODE, 10 mL oleylamine, and 5 mmol oleic acid in a 100 mL three-necked flask. Raise the temperature to 150 °C, purge with nitrogen for 10 min, let it cool back to room temperature, inject 1 mL of 0.2 mmol / mL S-ODE solution, react for 30 s, then quickly add 0.5 mmol indium oleate-ODE solution, inject 1 mL of 0.2 mmol / mL S-ODE solution, react for 3 min, then raise the temperature to 200 °C, add 1.2 mmol gallium oleate-ODE solution, inject 0.5 mL of 2 mmol / mL S-TOP solution, react for 10 min, raise the temperature to 280 °C, react for 30 min, and stop the reaction.

[0044] Example 3:

[0045] Take 0.5 mmol silver acetate, 20 g ODE, 10 mL oleylamine, and 5 mmol oleic acid in a 100 mL three-necked flask. Raise the temperature to 150 °C, purge with nitrogen for 10 min, let it cool back to room temperature, inject 1 mL of 0.2 mmol / mL S-ODE solution, react for 1 min, add 0.25 mmol indium oleate-ODE solution, inject 1 mL of 0.2 mmol / mL S-ODE solution, react for 3 min, then raise the temperature to 200 °C, add 1.2 mmol gallium oleate-ODE solution, inject 0.5 mL of 2 mmol / mL S-TOP solution, react for 10 min, raise the temperature to 280 °C, react for 30 min, and stop the reaction.

[0046] Example 4:

[0047] Take 0.5 mmol silver acetate, 20 g ODE, 10 mL oleylamine, and 5 mmol oleic acid in a 100 mL three-necked flask. Raise the temperature to 150 °C, purge with nitrogen for 10 min, let it cool back to room temperature, inject 1 mL of 0.2 mmol / mL sulfur-oleylamine solution, react for 30 s, then quickly add 0.5 mmol indium oleate-ODE solution, inject 1 mL of 0.2 mmol / mL S-ODE solution, react for 3 min, then raise the temperature to 200 °C, add 1.2 mmol gallium oleate-ODE solution, inject 0.5 mL of 2 mmol / mL S-TOP solution, react for 10 min, raise the temperature to 280 °C, react for 30 min, and stop the reaction.

[0048] Example 5:

[0049] Take 0.5 mmol silver acetate, 20 g ODE, 10 mL oleylamine, and 5 mmol oleic acid in a 100 mL three-necked flask. Raise the temperature to 150 °C, purge with nitrogen for 10 min, let it cool back to room temperature, inject 1 mL of 0.2 mmol / mL sulfur-oleylamine solution, react for 30 s, then quickly add 0.4 mmol indium oleate-ODE solution and 0.1 mmol indium chloride-oleylamine solution, inject 1 mL of 0.2 mmol / mL S-ODE solution, react for 3 min, then raise the temperature to 200 °C, add 1.2 mmol gallium oleate-ODE solution, inject 0.5 mL of 2 mmol / mL S-TOP solution, react for 10 min, raise the temperature to 280 °C, react for 30 min, and stop the reaction.

[0050] Example 6:

[0051] Take 0.5 mmol silver acetate, 20 g ODE, 10 mL oleylamine, and 5 mmol oleic acid in a 100 mL three-necked flask. Raise the temperature to 150 °C, purge with nitrogen for 10 min, let it cool back to room temperature, inject 1 mL of 0.2 mmol / mL sulfur-oleylamine solution, react for 30 s, then quickly add 0.4 mmol indium oleate-ODE solution and 0.1 mmol indium chloride-oleylamine solution, inject 1 mL of 0.2 mmol / mL S-ODE solution, react for 3 min, then raise the temperature to 200 °C, add 1.2 mmol gallium oleate-ODE solution and 0.2 mmol gallium chloride-oleylamine solution, inject 0.5 mL of 2 mmol / mL S-TOP solution, react for 10 min, raise the temperature to 280 °C, react for 30 min, and stop the reaction.

[0052] Example 7

[0053] Take 0.5 mmol silver acetate, 20 g ODE, 10 mL oleylamine, and 5 mmol myristic acid in a 100 mL three-necked flask. Raise the temperature to 150 °C, purge with nitrogen for 10 min, let it cool back to room temperature, inject 1 mL of 0.2 mmol / mL S-ODE solution, react for 30 s, then quickly add 0.5 mmol indium oleate-ODE solution, inject 1 mL of 0.2 mmol / mL S-ODE solution, react for 3 min, then raise the temperature to 200 °C, add 1.2 mmol gallium oleate-ODE solution, inject 0.5 mL of 2 mmol / mL S-TOP solution, react for 10 min, raise the temperature to 280 °C, react for 30 min, and stop the reaction.

[0054] Example 8

[0055] Take 0.5 mmol of silver acetate, 20 g of ODE, 10 mL of oleylamine, and 5 mmol of stearic acid in a 100 mL three-necked flask. Raise the temperature to 150 °C, purge with nitrogen for 10 min, let it cool back to room temperature, inject 1 mL of 0.2 mmol / mL S-ODE solution, react for 30 s, then quickly add 0.5 mmol of indium oleate-ODE solution, inject 1 mL of 0.2 mmol / mL S-ODE solution, react for 3 min, then raise the temperature to 200 °C, add 1.2 mmol of gallium oleate-ODE solution, inject 0.5 mL of 2 mmol / mL S-TOP solution, react for 10 min, raise the temperature to 280 °C, react for 30 min, and stop the reaction.

[0056] Example 9

[0057] Take 0.5 mmol of silver acetate, 20 g of ODE, 10 g of octadecylamine, and 5 mmol of oleic acid in a 100 mL three-necked flask. Raise the temperature to 150 °C, purge with nitrogen for 10 min, let it cool back to room temperature, inject 1 mL of 0.2 mmol / mL S-ODE solution, react for 30 s, then quickly add 0.5 mmol of indium oleate-ODE solution, inject 1 mL of 0.2 mmol / mL S-ODE solution, react for 3 min, then raise the temperature to 200 °C, add 1.2 mmol of gallium oleate-ODE solution, inject 0.5 mL of 2 mmol / mL S-TOP solution, react for 10 min, raise the temperature to 280 °C, react for 30 min, and stop the reaction.

[0058] Example 10

[0059] Take 0.5 mmol of silver acetate, 20 g of ODE, 10 g of octadecylamine, and 5 mmol of oleic acid in a 100 mL three-necked flask. Raise the temperature to 150 °C, purge with nitrogen for 10 min, let it cool back to room temperature, inject 1 mL of 0.2 mmol / mL S-ODE solution, react for 30 s, then quickly add 0.5 mmol of indium oleate-ODE solution, inject 1 mL of 0.2 mmol / mL S-ODE solution, react for 3 min, then raise the temperature to 200 °C, add 1.2 mmol of gallium oleate-ODE solution, inject 0.5 mL of dodecyl mercaptan, react for 10 min, raise the temperature to 280 °C, react for 30 min, and stop the reaction.

[0060] Example 11

[0061] Take 0.5 mmol of silver acetate, 20 g of ODE, 10 mL of oleylamine in a 100 mL three-necked flask. Raise the temperature to 150 °C, purge with nitrogen for 10 min, let it cool back to room temperature, inject 1 mL of a 0.2 mmol / mL sulfur-oleylamine solution, react for 30 s, then quickly add 0.1 mmol of an In(DDTC)3-ODE suspension, 0.2 mmol of an indium chloride-oleylamine solution, and 0.2 mmol of an indium oleate-ODE solution, react for 3 min, then raise the temperature to 200 °C, add 0.8 mmol of a Ga(DDTC)3-ODE suspension, 0.2 mmol of a gallium chloride-oleylamine solution, and 0.2 mmol of a gallium oleate-ODE solution, react for 10 min, raise the temperature to 280 °C, react for 30 min, and stop the reaction.

[0062] Example 12

[0063] Take 0.5 mmol of silver acetate, 20 g of ODE, 10 mL of oleylamine, and 5 mmol of oleic acid in a 100 mL three-necked flask. Raise the temperature to 150 °C, purge with nitrogen for 10 min, let it cool back to room temperature, inject 1 mL of a 0.2 mmol / mL S-ODE solution, react for 30 s, then quickly add 0.4 mmol of an indium oleate-ODE solution and 0.1 mmol of an indium chloride-oleylamine solution, inject 1 mL of a 0.2 mmol / mL S-ODE solution, react for 3 min, then raise the temperature to 200 °C, add 1 mmol of a gallium oleate-ODE solution and 0.2 mmol of a gallium chloride-oleylamine solution, inject 0.5 mL of a 2 mmol / mL S-TOP solution, react for 10 min, raise the temperature to 280 °C, react for 30 min, and stop the reaction.

[0064] Example 13

[0065] Take 0.5 mmol of silver acetate, 20 g of ODE, 10 mL of oleylamine, and 5 mmol of oleic acid in a 100 mL three-necked flask. Raise the temperature to 150 °C, purge with nitrogen for 10 min, let it cool back to room temperature, inject 1 mL of a 0.2 mmol / mL S-ODE solution, react for 30 s, then quickly add 0.3 mmol of an indium oleate-ODE solution, inject 1 mL of a 0.2 mmol / mL S-ODE solution, react for 3 min, then raise the temperature to 200 °C, add 1.2 mmol of a gallium oleate-ODE solution, inject 0.5 mL of a 2 mmol / mL S-TOP solution, react for 10 min, raise the temperature to 280 °C, react for 30 min, and stop the reaction.

[0066] Example 14

[0067] Take 0.5 mmol of silver acetate, 20 g of ODE, and 5 mmol of oleic acid in a 100 mL three-necked flask. Raise the temperature to 150 °C, purge with nitrogen for 10 min, let it cool back to room temperature, inject 1 mL of a 0.2 mmol / mL sulfur-oleylamine solution, react for 30 s, then quickly add 0.5 mmol of indium oleate-ODE solution, inject 1 mL of a 0.2 mmol / mL S-ODE solution, react for 3 min, then raise the temperature to 200 °C, add 1.2 mmol of gallium oleate-ODE solution, inject 0.5 mL of a 2 mmol / mL S-TOP solution, react for 10 min, raise the temperature to 280 °C, react for 30 min, and then stop the reaction.

[0068] Comparative Example 1:

[0069] Take 0.24 mmol of silver nitrate, 0.48 mmol of indium chloride, 2.4 mmol of gallium acetylacetonate, and 40 mmol of oleylamine in a 100 mL three-necked flask. Purge with nitrogen for 1 hour, then inject 10 mL of dodecyl mercaptan and 4 mL of a 1 mmol / mL sulfur-oleylamine mixture, raise the temperature to 300 °C, react for 30 min, and then stop the reaction.

[0070] Comparative Example 2:

[0071] Take 0.5 mmol of silver acetate, 20 g of ODE, and 10 mL of oleylamine in a 100 mL three-necked flask. Raise the temperature to 150 °C, purge with nitrogen for 10 min, let it cool back to room temperature, add 0.1 mmol of In(DDTC)3-ODE suspension and 0.4 mmol of indium chloride-oleylamine solution, add 0.8 mmol of Ga(DDTC)3-ODE suspension and 0.4 mmol of gallium chloride-oleylamine solution, raise the temperature to 280 °C, react for 30 min, and then stop the reaction.

[0072] Separate and purify the obtained quantum dot products above, and disperse them in toluene solvent for integrating sphere testing. Table 1 shows the optical properties of the examples and comparative examples.

[0073] Table 1

[0074]

[0075]

[0076] It can be seen from Table 1 that compared with the comparative examples, the examples are superior in terms of the full width at half maximum of fluorescence and the fluorescence quantum dot yield.

[0077] The above are only the preferred embodiments of the present disclosure and are not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included within the protection scope of the present disclosure.

Claims

1. A method for preparing quantum dots, characterized in that, The preparation method includes: S1: preparing a first mixture containing silver fatty acid, optional fatty amine, and a non-coordinating solvent; S2: mixing the first mixture with a first sulfur precursor, and heating and reacting in a container at a first reaction temperature for a first time to generate silver sulfide nanoparticles; S3: continuing to add an indium precursor and a second sulfur precursor to the container at a second reaction temperature and reacting for a second time; S4: continuing to add a gallium precursor and a third sulfur precursor to the container at a third reaction temperature and reacting for a third time, where the third reaction temperature is higher than the second reaction temperature; S5: raising the third reaction temperature to a fourth reaction temperature for alloying to obtain AgInGaS quaternary alloy quantum dots, and the first time is less than or equal to 60 seconds.

2. The preparation method of the quantum dots according to claim 1, wherein, The second time is 1 - 5 minutes. Preferably, the third time is 5 - 30 minutes.

3. The preparation method of quantum dots according to claim 1, characterized in that, Mix silver acetate, optional fatty acid, the fatty amine, and 1-octadecene, heat to dissolve, and obtain the first mixture after exhausting air.

4. The method for preparing quantum dots according to claim 3, wherein The fatty acid is oleic acid or a saturated fatty acid containing 8 - 18 carbon atoms.

5. The preparation method of the quantum dots according to claim 1, characterized in that, The first, second, and third sulfur precursors are selected from one or more of sulfur-1-octadecene, trialkylphosphine sulfide, sulfur-fatty amine, metal diethyldithiocarbamate, thiourea, and mercaptan, but the first sulfur precursor does not contain metal diethyldithiocarbamate.

6. The preparation method of the quantum dots according to claim 1, wherein, The indium precursor is selected from one or more of indium fatty acids with 8 - 18 carbon atoms, a mixed solution of the indium fatty acid and indium halide-oleylamine, indium bis(diethyldithiocarbamate) halide, or indium diethyldithiocarbamate.

7. The preparation method of the quantum dots according to claim 1, wherein, The gallium precursor is selected from one or more of gallium fatty acids with 8 - 18 carbon atoms, a mixed solution of the gallium fatty acid and gallium acetylacetonate-oleylamine, a mixed solution of the gallium fatty acid and gallium halide-oleylamine, gallium bis(diethyldithiocarbamate) halide, or gallium diethyldithiocarbamate.

8. The preparation method of the quantum dots according to claim 1, wherein, The first reaction temperature is 50 - 150 °C, and the second reaction temperature is 150 - 220 °C; preferably, the third reaction temperature is 180 - 220 °C, and the fourth reaction temperature is 250 - 300 °C.

9. The preparation method of the quantum dots according to claim 1, wherein The fatty amine is selected from oleylamine or a saturated fatty amine containing 8 - 18 carbon atoms.

10. The preparation method of the quantum dots according to claim 1, wherein, The fluorescence full width at half maximum of the AgInGaS quaternary alloy quantum dots is less than 40 nm, and the fluorescence quantum yield is greater than or equal to 60%.

11. The preparation method of the quantum dots according to claim 1, wherein The molar ratio of the silver element of the silver fatty acid to the sulfur element of the first sulfur precursor is (5:1) - (1:5).

12. The preparation method of the quantum dots according to claim 1, wherein, The molar ratio between the silver element of the silver fatty acid and the indium element of the indium precursor is (3:1) - (1:3), and the molar ratio between the indium element of the indium precursor and the gallium element of the gallium precursor is (1:1) - (1:5).

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