Method for preparing agingas@ga s x core-shell quantum dots based on one-pot method of high-activity indium salt

Abstract

The application discloses a method for preparing AgInGaS@GaSx core-shell quantum dots based on a one-pot method of high-activity indium salt, wherein an indium source, a silver source and a gallium sulfur source are sequentially added into a three-necked flask, organic matter ligands and solvents are added into the three-necked flask, then the three-necked flask is warmed by a heating jacket and magnetically stirred, and a vacuum is pumped to dissolve the precursors. The AIGS quantum dots are obtained by using the one-pot method and two-step warming to a suitable temperature, and the AIGS@GaS core-shell quantum dots are obtained by continuously warming and reacting. x The application matches high-activity IB and VLA elements by using the high-activity indium salt, suppresses the difference in the activities of various elements, improves the system activity, makes the quantum dots nucleate explosively under a more moderate condition, narrows the size distribution of the AIGS quantum dots, and improves the fluorescence light emitting efficiency of the quantum dots. The obtained AIGS quantum dots have a monodisperse size distribution, and the fluorescence quantum yield can reach more than 70%, and the AIGS@GaS x Core-shell quantum dots, and narrow-band emission with a wavelength adjustable fluorescence quantum yield of more than 90%.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nanomaterials and light-emitting display, and relates to a method for preparing AgInGaS@GaSx core-shell quantum dots based on high-activity indium salt one-pot method. BACKGROUND

[0002] Traditional quantum dots are seriously hindered in the development process due to the heavy metal elements contained therein, such as cadmium, lead and the like, especially in medical and environmental applications. Therefore, environmentally friendly I-III-VI semiconductor quantum dots gradually attract people's attention. These I-III-VI semiconductor quantum dots, such as AgInS2, CuInS2, AgGaS2 and the like, have the advantages of non-toxicity, adjustable band gap, high absorption and the like, and have wide application prospects in the fields of light-emitting diodes, biological imaging and solar cells and the like.

[0003] At present, there are one-pot synthesis methods for I-III-VI semiconductor quantum dots. Metal precursors and anion precursors are dissolved in oleylamine, and the reaction temperature is continuously stirred and increased, which improves the luminescent efficiency of the quantum dots and is expected to realize the application of electroluminescent diodes. However, high-definition display has certain requirements for the half-width of the luminescence of quantum dots. Considering that the reported core AgInS2 and AgGaS2 quantum dots are mainly dominated by defect luminescence, the luminescence of the quantum dots presents the wide spectrum characteristics (>90nm) of defect luminescence. Further, in view of the narrowing of the luminescence of the multi-component quantum dots, people have proposed that a GaS shell is used to coat the quaternary AIGS to realize narrow spectrum emission. Such AIGS@GaS x core-shell quantum dots exhibit a narrower half-width (<50nm) than AIGS, however, due to the fact that the activity of the In source in the multi-component is far lower than that of the Ag source and the S source, the nucleation and growth process is affected, leading to the non-uniformity of the size and composition of the synthesized quantum dots, and the optical performance of the core-shell quantum dots is limited.

[0004] A method for preparing AIGS quantum dots is disclosed in Chinese patent (202080036773.9), which adopts a hot injection method, uses a mixed solution of silver acetate, indium chloride and sulfur powder, and injects the mixed solution into an acetylacetone gallium mixed solution to prepare AIGS quantum dots. The fluorescence quantum yield and band edge emission intensity of the quantum dots are improved through GaI3 / TOP surface treatment. Most of the reported methods are hot injection methods, and the precursors are mostly low-activity indium sources such as indium chloride and indium acetate. At present, there is no method for matching the high activity of group IB and group VA elements based on high-activity indium sources to improve the system reaction activity. The method for matching the high activity of precursors by using high-activity indium sources realizes the preparation of monodisperse, high-fluorescence quantum yield AIGS@GaS x core-shell quantum dots.

[0005] Therefore, a method for preparing AgInGaS@GaSx core-shell quantum dots based on a one-pot method of a high-activity indium salt is needed to solve the above problems. SUMMARY

[0006] To solve the problems in the prior art, the application provides a method for preparing AgInGaS@GaSx core-shell quantum dots based on a one-pot method of a high-activity indium salt.

[0007] A method for preparing AgInGaS@GaSx core-shell quantum dots based on a one-pot method of a high-activity indium salt, comprising the following steps:

[0008] Step one, uniformly stirring and mixing the precursor salt and oleylamine and vacuumizing to obtain a precursor salt solution, the precursor salt being composed of an indium source, diethyldithiocarbamic acid gallium, and silver acetate, the indium source being indium bromide and / or indium iodide;

[0009] Step two, preparing AIGS@GaS x core-shell quantum dot solution by a one-pot method and two-step heating; x core-shell quantum dot solution by a one-pot method and two-step heating;

[0010] Step three, once centrifuging the AIGS@GaS x core-shell quantum dot solution obtained in step two, taking the supernatant of the once centrifuging to obtain a quantum dot stock solution;

[0011] Step four, adding a flocculating agent to the quantum dot stock solution obtained in step three, mixing thoroughly, and then performing secondary centrifuging, removing the supernatant of the secondary centrifuging, and obtaining AIGS@GaS x quantum dots.

[0012] Further, the stirring temperature in step one is 20-50℃, the stirring speed is 500-800rpm, and the vacuumizing time is 10-30min.

[0013] Further, the molar ratio of the indium source, diethyldithiocarbamic acid gallium, and silver acetate in the precursor salt in step one is 1:1-8:2.

[0014] Further, the first temperature in step two is 100-200℃, and the one-time reaction time is 5-60min.

[0015] Further, the second temperature in step two is 240-300℃, and the two-time reaction time is 5-60min.

[0016] Further, the centrifugal speed of the once centrifugal treatment in step three is 6000-10000 rpm, and the centrifugal time is 1-5 min; the centrifugal speed of the twice centrifugal treatment in step four is 6000-10000 rpm, and the centrifugal time is 1-5 min.

[0017] Further, the flocculating agent in step four is ethanol or methanol.

[0018] Further, the volume ratio of the flocculating agent to the quantum dot stock solution in step four is 1-6:1.

[0019] Further, the method further comprises step five: dispersing the precipitate obtained in step four into a non-polar organic solvent to obtain AIGS@GaS x The non-polar organic solvent is n-hexane, n-octane or toluene.

[0020] Principle: The application synthesizes AIGS quantum dots by one-pot method, balances the activity of IB and IIIA group elements by using high-activity indium salt, so that the quantum dots nucleate explosively under milder conditions, and AIGS quantum dots with uniform nanoscale morphology size are produced. The introduction of high-activity indium salt improves the crystallinity and quality of the quantum dots, reduces the surface defects of the quantum dots, further increases the radiation recombination ratio of the quantum dots, and the fluorescence quantum yield is more than 70%.

[0021] Beneficial effects: The method for preparing AgInGaS@GaSx core-shell quantum dots based on high-activity indium salt one-pot method of the application forms a GaS shell layer to coat AIGS quantum dots to form AIGS@GaS x core-shell quantum dots, realizes wavelength adjustment, size monodispersion, and AIGS@GaS x core-shell quantum dots with a half peak width of less than 35 nm, and is conducive to industrial mass production. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 TEM image of the product AIGS quantum dots prepared in Example 1 of the application;

[0023] Figure 2 Comparison chart of emission spectra of AIGS quantum dots of Example 1, 2 and Comparative Example 1, 2 of the application;

[0024] Figure 3 XRD chart of AIGS quantum dots of Example 1, 2 and Comparative Example 1, 2 of the application;

[0025] Figure 4 Comparison chart of fluorescence lifetime of AIGS quantum dots of Example 1, 2 and Comparative Example 1, 2 of the application;

[0026] Figure 5 TEM image of the product AIGS@GaS prepared in Example 1 of the present application x TEM image of core-shell quantum dots;

[0027] Figure 6 AIGS@GaS of Example 1, 2 and Comparative Example 1, 2 of the present application x Emission spectrum of core-shell quantum dots;

[0028] Figure 7 AIGS@GaS of Example 1, 2 and Comparative Example 1, 2 of the present application x XRD pattern of core-shell quantum dots;

[0029] Figure 8 AIGS@GaS of Example 1, 3, 4, 5, 6 of the present application x Comparison of emission spectrum of core-shell quantum dots;

[0030] Figure 9 AIGS@GaS of Example 1, 3, 4, 5, 6 of the present application x Comparison of XRD pattern of core-shell quantum dots;

[0031] Figure 10 TEM image of the product AIGS quantum dots prepared in Comparative Example 1 of the present application

[0032] Figure 11 AIGS@GaS of Comparative Example 1 of the present application x TEM image of core-shell quantum dots. DETAILED DESCRIPTION

[0033] The present application will now be described in further detail with reference to the drawings. These drawings are simplified schematic illustrations of the basic structure of the present application and therefore only show the components relevant to the present application.

[0034] Example 1

[0035] 1) 0.0084 g of silver acetate powder, 0.0372 g of indium iodide powder, 0.0512 g of gallium diethyldithiocarbamate powder, and 12 mL of oleylamine were all added to a three-necked flask, and the molar ratio of the precursor salts was 1:1.5:2;

[0036] 2) The three-necked flask was heated to 50°C, and the solution was uniformly stirred at 700 rpm using a magnetic stirrer, and vacuumed for 20 min;

[0037] 3) A one-pot method combined with two-step temperature increase was used: the temperature was increased to 150°C, and AIGS quantum dots were obtained after 30 min of reaction;

[0038] 4) heating to 280℃, reaction for 15 min, to prepare AIGS@GaS x core-shell quantum dots;

[0039] 5) after the reaction is completed, the solution is transferred to a centrifuge tube and centrifuged at 10000 rpm for 3 min, the supernatant is taken, 24 mL of ethanol is mixed with the supernatant, and then centrifuged at 10000 rpm for 3 min;

[0040] 6) the supernatant is removed, and the precipitate is dispersed in 2 mL of toluene to obtain the AIGS@GaS x core-shell quantum dot dispersion.

[0041] The AIGS quantum dots prepared in the example were subjected to TEM, PL, XRD, PL-decay, as shown in Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 . The TEM results show that according to the process parameters of Example 1, AIGS quantum dots with uniform morphology and monodisperse size distribution can be obtained, with a size of 4.65 nm. As can be seen from the PL diagram, the fluorescence emission intensity of the quantum dots is significantly enhanced, and the fluorescence quantum yield of the quantum dots is improved, and the test results show that the fluorescence quantum yield of the quantum dots has increased by nearly 6 times. The XRD spectrum shows that the main diffraction peaks are within the range of AgInS2 and AgGaS2 diffraction peaks, indicating that tetragonal AIGS quantum dots have been successfully synthesized, which is consistent with the observation of obvious lattice fringes in TEM. Figure 5 As shown in Figure 5 , with the introduction of high-activity indium salt, the fluorescence lifetime of the quantum dots is enhanced, and non-radiative recombination is inhibited, indicating that the surface defects of the quantum dots are passivated, so the fluorescence quantum yield of the quantum dots is improved. After the AIGS quantum dots are coated with a GaS shell, as shown in x , the AIGS@GaS core-shell quantum dots still maintain monodisperse size distribution and uniform morphology, with a size of about 5.58 nm. The PL emission peak is at 530 nm, and there is a defect peak in the 600 nm region, accounting for 10%. Under ultraviolet light, it presents a bright green light, and the XRD spectrum shows that the main diffraction peaks are within the range of AgInS2 and AgGaS2 diffraction peaks, indicating that the coating of GaS does not change the structure of the AIGS quantum dot core.

[0042] Example 2

[0043] The same process as in Example 1 was adopted, except that 0.0372 g of indium iodide was replaced by 0.0266 g of indium bromide in step 1), and other conditions remained the same.

[0044] The prepared products were characterized by PL, XRD and PL-decay, as shown in Figure 2 , Figure 3 , Figure 4 and Figure 6 The XRD spectrum showed a wide peak, but the main diffraction peaks were within the range of AgInS2and AgGaS2diffraction peaks, and the quantum dots had poor crystallinity. The test results showed that the fluorescence quantum yield of the quantum dots was only 46%. After the AIGS quantum dots were coated with a GaS shell, the PL emission peak was at 530 nm, but there was a defect peak at 600 nm, accounting for 25%.

[0045] Example 3

[0046] The same process as in Example 1 was adopted, except that 0.0372 g of indium iodide was replaced by 0.0248 g of indium iodide in step 1), and other conditions remained unchanged.

[0047] The prepared products were characterized by PL and XRD, as shown in Figure 8 , Figure 9 The results showed that according to the process parameters of Example 3, a PL emission peak at 500 nm and an XRD spectrum within the range of AgInS2and AgGaS2diffraction peaks, which shifted to a lower angle relative to Example 1, could be obtained.

[0048] Example 4

[0049] The same process as in Example 1 was adopted, except that 0.0372 g of indium iodide was replaced by 0.0495 g of indium iodide in step 1), and other conditions remained unchanged.

[0050] The prepared products were characterized by PL and XRD, as shown in Figure 8 , Figure 9 The results showed that according to the process parameters of Example 4, a PL emission peak at 554 nm and an XRD spectrum within the range of AgInS2and AgGaS2diffraction peaks, which shifted to a higher angle relative to Example 1, could be obtained.

[0051] Example 5

[0052] The same process as in Example 1 was adopted, except that 0.0372 g of indium iodide was replaced by 0.0619 g of indium iodide in step 1), and other conditions remained unchanged.

[0053] The prepared products were characterized by PL and XRD, as shown in Figure 8 , Figure 9The results show that according to the process parameters of Example 5, the PL emission peak can be obtained at 580 nm, the XRD spectrum is within the range of AgInS2and AgGaS2diffraction peaks, and is offset to high angle relative to Example 1.

[0054] Example 6

[0055] The same process as Example 1 is adopted, except that 0.0372 g of indium iodide is replaced by 0.0743 g of indium iodide in step 1), and other conditions remain unchanged.

[0056] The prepared product is subjected to PL and XRD characterization analysis, as shown in Figure 8 , Figure 9 The results show that according to the process parameters of Example 6, the PL emission peak can be obtained at 600 nm, the XRD spectrum is within the range of AgInS2and AgGaS2diffraction peaks, and is offset to high angle relative to Example 1.

[0057] Example 7

[0058] The same process as Example 1 is adopted, except that:

[0059] Step 3) adopts one-pot method combined with two-step temperature rising: the temperature is raised to 100°C, and AIGS quantum dots are obtained after reacting for 60 min;

[0060] Step 4) the temperature is raised to 240°C, and AIGS@GaSxcore-shell quantum dots are prepared after reacting for 60 min.

[0061] Example 8

[0062] The same process as Example 1 is adopted, except that:

[0063] Step 3) adopts one-pot method combined with two-step temperature rising: the temperature is raised to 200°C, and AIGS quantum dots are obtained after reacting for 5 min;

[0064] Step 4) the temperature is raised to 300°C, and AIGS@GaSxcore-shell quantum dots are prepared after reacting for 5 min.

[0065] Comparative Example 1

[0066] 1) 0.0084 g of silver acetate powder, 0.0177 g of indium chloride powder, 0.0512 g of gallium diethyldithiocarbamate powder, and 12 mL of oleylamine are all added to a three-necked flask;

[0067] 2) The three-necked flask is heated to 50°C, and the solution is uniformly stirred by a magnetic stirrer at 700 rpm, and vacuumized for 20 min;

[0068] 3) using one-pot method combined with two-step temperature rising: raising temperature to 150°C, reacting for 30 min, to obtain AIGS quantum dots;

[0069] 4) raising temperature to 280°C, reacting for 15 min, to prepare AIGS@GaS x core-shell quantum dots;

[0070] 5) after the reaction is completed, transferring the solution to a centrifuge tube, centrifuging at 10000 rpm for 3 min, and taking the supernatant. 24 mL of ethanol is mixed with the supernatant, and then centrifuged at 10000 rpm for 3 min;

[0071] 6) removing the supernatant, dispersing the precipitate into 2 mL of toluene, to obtain the AIGS@GaS x core-shell quantum dot dispersion.

[0072] The product prepared in the comparative example was characterized by PL, XRD, PL-decay, TEM and high-resolution TEM, as shown in Figure 2 、 Figure 3 、 Figure 4 、 Figure 6 、 Figure 10 and Figure 11 . The TEM results show that according to the process parameters of Comparative Example 1, the AIGS quantum dots obtained have uneven size distribution and the size is 8.74 nm. The test results show that the fluorescence quantum yield of the quantum dots is only 12%. Although the main diffraction peaks of the XRD spectrum are within the range of AgInS2 and AgGaS2 diffraction peaks, the crystallinity of the quantum dots is very poor. Compared with Example 1, the fluorescence lifetime of the quantum dots is shorter, and the non-radiative recombination ratio is high, indicating that the quantum dots have more surface defects, so the fluorescence quantum yield of the quantum dots is low. After the AIGS quantum dots described above are coated with a GaS shell layer, the PL emission peak is at 530 nm, but there is a defect peak at 600 nm, accounting for 39%. The pure color of the light emission is affected.

[0073] Comparative Example 2

[0074] The same process as Comparative Example 1 was adopted, except that 0.0177 g of indium chloride powder was replaced with 0.0324 g of indium acetate powder in step 1), and other conditions remained the same.

[0075] The product prepared in the comparative example was characterized by PL, XRD and PL-decay, as shown in Figure 2 、 Figure 3 、 Figure 4 and Figure 6As shown, the XRD spectrum shows a wide peak, but the main diffraction peaks are all in the range of AgInS2 and AgGaS2 diffraction peaks, and the quantum dots have poor crystallinity. The test results show that the fluorescence quantum yield of the quantum dots is only 33%. After the AIGS quantum dots in the above are coated with a GaS shell layer, the PL light emission peak is 530 nm, but there is a defect peak in the 600 nm region, accounting for 33%.

[0076] In conclusion, the application provides a one-pot method for preparing AIGS@GaS x core-shell quantum dots. In the two-step temperature rising synthesis process of the one-pot method, the high-activity indium source is introduced to match the activity of group IB and group VIA, the element activity matching is realized, the burst nucleation is induced, the AIGS quantum dots with size monodispersity and high fluorescence quantum yield are prepared, and the AIGS@GaS x core-shell quantum dots.

[0077] Based on the above ideal embodiments according to the application, through the above description, relevant personnel can make various changes and modifications without deviating from the technical idea of the application. The technical scope of the application is not limited to the content in the specification, and must be determined according to the scope of the claims.

Claims

1. A method for preparing AgInGaS@GaSx core-shell quantum dots based on a one-pot process of high-activity indium salt, characterized in that: The following steps are involved: Step 1: Stirring and mixing the precursor salt and oleylamine uniformly and evacuating the mixture to obtain a precursor salt solution, wherein the precursor salt is composed of an indium source, gallium diethyldithiocarbamate, and silver acetate, and the indium source is indium bromide and / or indium iodide; Step 2: Preparation of AIGS@GaS using a one-pot method and two-step heating x Core-shell quantum dot solution: The precursor salt solution obtained in step 1 is heated to a first temperature, and the AIGS quantum dot solution is obtained by a primary reaction; the obtained AIGS quantum dot solution is heated to a second temperature, and the AIGS@GaS is obtained by a secondary reaction. x Core-shell quantum dot solution; In step 2, the first temperature is 100-200°C, and the primary reaction time is 5-60 minutes; In step 2, the second temperature is 240-300°C, and the secondary reaction time is 5-60 minutes; Step 3: The AIGS@GaS obtained in step 2 x The core-shell quantum dot solution is centrifuged once, and the supernatant liquid obtained from the centrifugation is taken to obtain the quantum dot stock solution; Step 4: Add flocculant to the quantum dot stock solution obtained in step 3, mix thoroughly, and then centrifuge for the second time. Remove the supernatant from the second centrifugation process to obtain the precipitate, which is AIGS@GaS. x Quantum dots.

2. The method for preparing AgInGaS@GaSx core-shell quantum dots based on a one-pot process of high-activity indium salt according to claim 1, characterized in that In step 1, the stirring temperature is 20-50° C., the stirring speed is 500-800 rpm, and the vacuuming time is 10-30 min.

3. The method for preparing AgInGaS@GaSx core-shell quantum dots based on a one-pot process of high-activity indium salt according to claim 1, characterized in that: In step 1, the molar ratio of the indium source, gallium diethyldithiocarbamate and silver acetate in the precursor salt is 1:1-8:

2.

4. The method for preparing AgInGaS@GaSx core-shell quantum dots based on a one-pot process of high-activity indium salt according to claim 1, characterized in that The centrifugal speed of the first centrifugation in step 3 is 6000-10000 rpm, and the centrifugation time is 1-5 min.

5. The method for preparing AgInGaS@GaSx core-shell quantum dots based on a one-pot process of high-activity indium salt according to claim 1, characterized in that: The centrifugal speed of the secondary centrifugation in step 4 is 6000-10000 rpm, and the centrifugation time is 1-5 min.

6. The method for preparing AgInGaS@GaSx core-shell quantum dots based on a one-pot process of high-activity indium salt according to claim 1, characterized in that: In step 4, the flocculant is ethanol or methanol.

7. The method for preparing AgInGaS@GaSx core-shell quantum dots based on a one-pot process of high-activity indium salt according to claim 6, characterized in that: In step 4, the volume ratio of the flocculant to the quantum dot stock solution is 1-6:

1.

8. The method for preparing AgInGaS@GaSx core-shell quantum dots based on a one-pot process of high-activity indium salt according to claim 1, characterized in that: The method further includes the step of dispersing the precipitate obtained in step 4 into a non-polar organic solvent to obtain AIGS@GaS x The quantum dot dispersion liquid, wherein the non-polar organic solvent is n-hexane, n-octane or toluene.

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