Method for preparing HgTe quantum dots based on ODT-assisted synthesis

Abstract

The invention relates to the technical field of colloidal quantum dot manufacturing, in particular to a method for preparing HgTe quantum dots based on ODT-assisted synthesis, which comprises the following steps: adding oleylamine into a single-mouth bottle, sequentially adding HgCl2 and ODT into the bottle, adding a TOP-Te solution, finally injecting tetrachloroethylene, trimercaptopropionic acid and isopropanol into the solution, centrifuging to obtain a precipitate, dispersing the precipitate in n-octane, and drying to obtain the HgTe quantum dots. The HgTe quantum dot solution is obtained. According to the method, ODT-assisted synthesis is adopted, and the HgTe CQDs are excellent in monodispersity and exciton absorption characteristic; the HgTe quantum dot film prepared from the synthesized HgTe quantum dots is flat and uniform, and has low roughness.

Description

Technical Field

[0001] The present invention relates to the technical field of colloidal quantum dot manufacturing, in particular to a method for preparing HgTe quantum dots based on ODT-assisted synthesis. Background Art

[0002] Colloidal quantum dots are inorganic semiconductor nanocrystals synthesized by solution method, with characteristic size ranging from a few nanometers to tens of nanometers, which is smaller than the exciton Bohr radius of the material. Infrared detector technology based on colloidal quantum dots provides a new idea for the development of a new generation of low-cost, high-performance, large-array infrared detection technology.

[0003] Among colloidal quantum dot materials, HgTe has a special status. It is the only material that covers the entire infrared range due to its unique electronic structure, air stability and charge conduction ability. However, the surface of HgTe CQDs synthesized by the solution method is usually coated with long-chain oleylamine ligands, and the long-chain oleylamine has a weak binding ability with Hg atoms on the surface of HgTe quantum dots, making it difficult to form effective coordination and even more difficult to obtain quantum dot materials with excellent monodispersity. Therefore, selecting suitable ligands, improving the binding ability with Hg, and forming effective coordination are the keys to synthesizing high-quality HgTe CQDs. Summary of the invention

[0004] The purpose of the present invention is to provide a novel ligand-assisted synthesis of high-quality HgTe quantum dots, which utilizes long-chain ligand ODT to assist in the synthesis, and the preparation method is simple and efficient.

[0005] A method for preparing HgTe quantum dots based on ODT-assisted synthesis, the preparation steps are as follows: S1, add 10 mL of oleylamine into a 50 mL single-necked bottle, heat to 140 °C and keep warm for 1.5 h; S2, add 0.3 mmol of HgCl2 and 50 μL of ODT to the single-necked bottle in sequence, and completely dissolve HgCl2 in a glove box filled with nitrogen; S3, after lowering the solution temperature to the reaction temperature and keeping it warm for 30 min, 100 μL of 1 M TOP-Te solution was quickly injected and reacted for 1 min; S4, TOP-Te with a low concentration of 0.2 mmol / ml was added dropwise at a rate of 250 μL / min by a syringe pump for 2 min, and finally reacted for a further 3 min; S5. After the reaction is completed, 10 mL of tetrachloroethylene and 100 μL of trithiopropionic acid are quickly injected and the solution is naturally cooled to room temperature. Anhydrous isopropanol is added to the solution, centrifuged at 8000 rmp / min for 3 minutes, and the precipitate is dispersed in n-octane to obtain a HgTe quantum dot solution.

[0006] The HgTe quantum dot solution was centrifuged, the upper solution was extracted, and the HgTe quantum dot solution was taken out using a pipette for spin coating. The speed of spin coating to prepare the film was 2500 rpm / min, and the time was 30 min. After the solution evaporated, the HgTe quantum dots were deposited to form a film.

[0007] Specifically, the dissolution temperature in S2 is 100°C.

[0008] Specifically, the reaction temperature in S3 is 75°C. At different reaction temperatures, the absorption spectra of HgTe quantum dots are significantly different. The absorption cutoff wavelengths of the synthesized quantum dots at reaction temperatures of 75°C, 85°C, and 95°C are 2246 nm, 2865 nm, and 3500 nm, respectively, and the exciton absorption characteristics of the quantum dots change significantly. Specifically, the preparation method of the TOP-Te solution in S3 is to take 1.276 g of Te powder, dissolve it in 10 ml of trioctyl phosphine, and heat it to 160°C.

[0009] Specifically, the centrifugal speed in S5 is 8000 rpm / min, and the centrifugal time is 3 min.

[0010] The technical effects and advantages of the present invention are: 1) The preparation method is simple, effective, low-cost and repeatable; 2) ODT-assisted synthesis, HgTe CQDs have excellent monodispersity and exciton absorption properties; 3) The HgTe quantum dot film prepared by synthesizing HgTe quantum dots is smooth and uniform with low roughness. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is the XRD pattern of HgTe quantum dots.

[0012] Figure 2 TEM image of HgTe quantum dots.

[0013] Figure 3 This is the infrared absorption diagram of HgTe quantum dot film.

[0014] Figure 4 XPS graph of S 2p of HgTe quantum dot film Figure 5 AFM and physical pictures of HgTe quantum dot films.

[0015] Figure 6 TEM image of HgTe quantum dots prepared without adding ODT.

[0016] Figure 7 This is the infrared absorption graph of HgTe quantum dot film prepared without adding ODT. DETAILED DESCRIPTION

[0017] Example: A method for preparing HgTe quantum dots based on ODT-assisted synthesis, the preparation steps are as follows: S1, add 10 mL of oleylamine into a 50 mL single-necked bottle, heat to 140 °C and keep warm for 1.5 h; S2, add 0.3 mmol HgCl2 and 50 μL ODT to a single-necked bottle in sequence, and dissolve HgCl2 completely in a glove box filled with nitrogen at a dissolution temperature of 100°C; S3, after the solution temperature was lowered to the reaction temperature and kept warm for 30 min, the reaction temperature was 75°C, and 100 μL of 1 M TOP-Te solution was quickly injected for 1 min; S4, adding TOP-Te with a low concentration of 0.2 mmol / ml dropwise at a rate of 250 μL / min through a syringe pump for 2 minutes, and finally further reacting for 3 minutes; The preparation method of the TOP-Te solution is to take 1.276 g of Te powder, dissolve it in 10 ml of trioctyl phosphine, and heat it to 160°C; S5, after the reaction is completed, 10 mL of tetrachloroethylene and 100 μL of trithiopropionic acid are quickly injected and cooled naturally to room temperature, isopropanol is added to the solution, centrifuged at 8000 rmp / min for 3 minutes, and the precipitate is dispersed in n-octane to obtain a HgTe quantum dot solution; S6, centrifuging the HgTe quantum dot solution, extracting the upper solution, using a pipette to take the HgTe quantum dot solution for spin coating, the spin coating speed for preparing the film is 2500 rpm / min, and the time is 30 minutes; after the solution evaporates, the HgTe quantum dots are deposited to form a film.

[0018] like Figure 1 The XRD pattern of the HgTe quantum dots shown in the figure shows 7 diffraction peaks that can be clearly observed, which matches the PDF card of zinc blende structure HgTe (JCPDS card No: 32-0665) accurately and has excellent crystallinity.

[0019] like Figure 2 The TEM image of HgTe quantum dots shown in the figure shows that after ligand exchange, it can be seen that the HgTe CQDs have excellent monodispersity.

[0020] like Figure 3 The infrared absorption spectrum of the HgTe quantum dot film shown in the figure shows that the exciton absorption peak is sharp and the absorption is obvious.

[0021] like Figure 4The XPS graph of S 2p of the HgTe quantum dot film shown in the figure clearly shows the Hg-S peak (162.8 eV), indicating that the ligand ODT successfully coated the surface of HgTe CQDs.

[0022] like Figure 5 The AFM images and physical images of the HgTe quantum dot film shown in the figure show that the film has good density, smooth surface, and root mean square roughness ( RMS )Low, RMS =2.1 nm. If the quality of the HgTe quantum dot film is poor, interface defects will be introduced on the contact surface of the device functional layer, causing carriers to recombine during transportation due to the presence of defects, reducing the carrier migration rate and also causing the performance of the device to decline.

[0023] Comparative Example: Step S2 is to add 0.3 mmol of HgCl2 into the single-necked bottle in sequence, without adding ODT, and the other steps are consistent with the embodiment.

[0024] like Figure 6 As shown, the exciton absorption characteristics of the HgTe quantum dots prepared in the comparative example are not obvious and the absorption peak is poor.

[0025] like Figure 7 As shown, the HgTe quantum dot film prepared in the comparative example has serious agglomeration phenomenon and poor dispersion.

Claims

1. A method for preparing HgTe quantum dots based on ODT-assisted synthesis, characterized in that: S1, add 10 mL of oleylamine into a 50 mL single-necked bottle, heat to 140 °C and keep warm for 1.5 h; S2, add 0.3 mmol of HgCl2 and 50 μL of ODT to the bottle in sequence, and completely dissolve HgCl2 in a glove box filled with nitrogen; S3, after the solution temperature was lowered to the reaction temperature and kept warm for 30 min, 100 μL of 1 M TOP-Te solution was quickly injected and reacted for 1 min; S4, a low concentration of 0.2 mmol / ml TOP-Te was added dropwise at a rate of 250 μL / min by a syringe pump for 2 min, and finally further reacted for 3 min; S5. After the reaction is completed, 10 mL of tetrachloroethylene and 100 μL of trithiopropionic acid are quickly injected and the solution is naturally cooled to room temperature. Isopropanol is added to the solution, centrifuged at 8000 rmp / min for 3 minutes, and the precipitate is dispersed in n-octane to obtain a HgTe quantum dot solution.

2. A method for preparing HgTe quantum dot thin film based on ODT-assisted synthesis, characterized in that The HgTe quantum dot solution was centrifuged, the upper solution was extracted, and the HgTe quantum dot solution was spin-coated using a pipette. The rotation speed of the spin coating to prepare the film was 2500 rpm / min, and the time was 30 min. After the solution evaporated, the HgTe quantum dots were deposited to form a film.

3. The method for preparing HgTe quantum dots based on ODT-assisted synthesis according to claim 1, characterized in that The dissolution temperature in S2 is 100°C.

4. The method for preparing HgTe quantum dots based on ODT-assisted synthesis according to claim 1, characterized in that The reaction temperature in S3 was 75°C.

5. The method for preparing HgTe quantum dots based on ODT-assisted synthesis according to claim 1, characterized in that The preparation method of TOP-Te solution in S3 is to take 1.276g of Te powder, dissolve it in 10ml of trioctylphosphine, and heat it to 160℃.

6. The method for preparing HgTe quantum dots based on ODT-assisted synthesis according to claim 1, characterized in that The centrifugal speed in S5 was 8000 rpm / min and the centrifugal time was 3 min.

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