Synthesis method of cadmium arsenide quantum dots

Abstract

The invention belongs to the technical field of new materials, and particularly discloses a cadmium arsenide quantum dot synthesis method which comprises the following steps: S1, preparing a Cd precursor solution, a reducing agent solution and an As precursor solution; s2, vacuumizing the Cd precursor solution for 30-60 minutes, introducing inert gas into a reaction system, and adjusting the temperature; s3, a reducing agent solution and an As precursor solution are rapidly injected for a reaction, heat preservation is conducted after injection, and the heat preservation time ranges from 1 minute to 24 hours; and S4, cooling to room temperature after heat preservation is finished, washing for multiple times, and dispersing in a non-polar solvent to obtain the cadmium arsenide quantum dots. According to the synthesis method of the cadmium arsenide quantum dots, cadmium is used as an initial product, and the cadmium arsenide quantum dots are finally obtained; by adjusting the reaction parameters of the cadmium nanocrystal, the stably dispersed cadmium arsenide nanocrystal with adjustable size can be obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of new materials, and particularly relates to a method for synthesizing cadmium arsenide quantum dots. Background Art

[0002] Infrared light is located between visible light and microwaves and is electromagnetic radiation with a wavelength of 0.76 μm - 1000 μm, which is ubiquitous in nature. Due to the absorption of gas molecules such as CO 2 in the atmosphere, water molecules, and the scattering of solid particles, dust, etc., infrared radiation in specific bands is attenuated during transmission. Therefore, the bands that allow infrared radiation to pass through are called "atmospheric windows". The three commonly used "atmospheric windows" are respectively called short-wave infrared (0.7 μm - 3 μm), mid-wave infrared (3 μm - 5 μm), and long-wave infrared (8 μm - 14 μm). However, infrared light cannot be directly perceived by the naked eye. Therefore, people have invented infrared photodetectors to detect infrared light, which are currently widely used in satellite remote sensing, environmental monitoring, biomedicine, imaging, and communication, etc.

[0003] An infrared photodetector is a device that converts an infrared light signal into an electrical signal that can be processed and read. Currently, commercial infrared photodetectors usually use traditional narrow-bandgap bulk inorganic semiconductor materials (such as InSb, HgCdTe, InGaAs, etc.). However, these materials have certain limitations. First, the growth conditions of the above materials are demanding and usually require extreme temperature and vacuum conditions. Second, their growth method is epitaxial growth on a lattice-matched substrate, making such infrared photodetectors expensive.

[0004] Colloidal semiconductor quantum dots have a size-tunable bandgap and solution processability, and have a wide range of applications in fields such as solar cells, photodetectors, and light-emitting diodes. Quantum dots are zero-dimensional materials with dimensions in the nanoscale range. Their main feature is the quantum confinement effect. Specifically, when the size of the semiconductor material gradually becomes smaller than the exciton Bohr radius of the material itself, the originally continuous energy levels of the semiconductor material will become split. At this time, as the size decreases, the energy band of the semiconductor material will gradually increase. Based on this effect, we can obtain semiconductor materials with different bandgaps by regulating the size of the material. Quantum dots with narrow bandgaps can respond to infrared light. Compared with traditional bulk semiconductor materials, infrared quantum dots have advantages such as easy processing, good optical stability, and high absorption coefficients (Adv. Optical Mater. 2023, 11, 2300970). In addition, in addition to size adjustment, infrared quantum dots can also achieve spectral responses in different infrared light ranges through compositional design, which is also the main advantage of quantum dots applied in photodetectors. In addition, infrared quantum dots can be synthesized in large quantities by means of solution methods. The liquid-phase processing technology enables them to be directly chip-on-chip coupled with silicon-based readout circuits without complex flip-chip bonding processes, greatly simplifying the process and further improving the performance of infrared photodetectors (Adv. Funct. Mater. 2018, 28, 1804712).

[0005] Currently, the commonly used quantum dot materials in infrared detectors mainly include PbS quantum dots and HgTe quantum dots. In addition, some new types of quantum dots, such as Ag 2 S and Ag 2 Te quantum dots (Acc. Mater. Res. 2024, 5, 9, 1097 - 1108; Nat. Photonics 2024, 236–242) have also been reported.

[0006] Cd 3 As 2 is a narrow-bandgap semiconductor material with a bandgap of -0.19 eV and a Bohr radius of 45 nm (J. Am. Chem. Soc. 2011, 133, 4676–4679). Currently, there are few reports on its synthesis. The synthesis methods can be roughly divided into two routes: one is the gas-phase liquid-phase synthesis method, that is, the AsH 3 As 2 obtained by the reaction of Zn 3 with acid reacts with the Cd source solution (Chem. Mater. 2014, 26, 3599 - 3602; J. Phys. Chem. C 2015, 119, 16390 - 16395). Among them, the generated AsH 3The gas is toxic, and a tail gas collection device needs to be equipped during the experiment, making it difficult to control in large-scale reactions. The other is to obtain Cd 3 As 2 quantum dots. Among them, the As source can be divided into two types: tris(trimethylsilyl)arsine and tris(dimethylamino)arsine (J. Am. Chem. Soc. 2011, 133, 4676 - 4679; Chem. Mater. 2016, 28, 6797 - 6802). Among them, tris(trimethylsilyl)arsine has high chemical activity, is prone to redox reactions, and is flammable and explosive. In addition, there is little understanding of the synthesis of cadmium arsenide quantum dots at present, and the synthesis route of cadmium arsenide still needs to be further explored.

[0007] Therefore, there is a need in the art to develop various synthesis methods for cadmium arsenide quantum dots and study the synthesis routes of cadmium arsenide quantum dots. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for synthesizing cadmium arsenide quantum dots. This method uses cadmium as the initial product and finally obtains cadmium arsenide quantum dots; by adjusting the reaction parameters for obtaining cadmium nanocrystals, cadmium arsenide nanocrystals with adjustable sizes and stable dispersions can be obtained.

[0009] To achieve the above purpose, the present invention provides a method for synthesizing cadmium arsenide quantum dots, including the following steps:

[0010] Step S1, prepare a Cd precursor solution, a reducing agent solution, and an As precursor solution;

[0011] Step S2, evacuate the Cd precursor solution for 30 - 60 minutes, then introduce an inert gas into the reaction system and adjust the temperature;

[0012] Step S3, quickly inject the reducing agent solution and the As precursor solution and then react, and keep warm after injection, and the warming time is 1 minute - 24 hours;

[0013] Step S4, after the warming is over, cool to room temperature, wash multiple times and disperse in a non-polar solvent to obtain cadmium arsenide quantum dots.

[0014] Preferably, in step S1, the Cd precursor solution includes a Cd source, an organic ligand, and an organic solution; the Cd source includes one or more mixtures of cadmium oxide, cadmium acetate, CdX 2 wherein X includes Cl, Br, I; the organic ligand is a long-chain amine or a long-chain carboxylic acid, and the addition amount is 5 - 20 mL; the organic solution includes one or more mixtures of a long-chain amine, a long-chain carboxylic acid ligand, and a solvent solution; the solvent solution is a long-chain unsaturated fatty acid or an alkane.

[0015] Preferably, the concentration of Cd in the Cd precursor solution is 0.06 - 1 M; the amount of the organic solution added is 5 - 20 mL, and the total volume of the long-chain amine and the long-chain carboxylic acid accounts for 10 - 100% of the volume in the organic solution. The long-chain amine and the long-chain carboxylic acid ligands each contain 8 - 20 carbon atoms. 2+

[0016] Preferably, in step S1, the reducing agent solution includes a reducing agent and an organic solution. The amount of the reducing agent added is 0.6 - 10 mmol, and the organic solution is 0.3 - 10 mL; the reducing agent is one or a mixture of two of diisobutylaluminum hydride and lithium triethylborohydride; the organic solution is one or a mixture of several of tetrahydrofuran, n-octane, n-hexane, toluene, and dioctyl ether.

[0017] Preferably, in step S1, the As precursor solution includes an As source and oleylamine. The amount of the As source added is 0.2 - 0.8 mmol, and the volume of oleylamine is 0.5 - 2 mL; the As source is one or a mixture of two of tris(dimethylamino)arsine and tris(trimethylsilyl)arsine.

[0018] Preferably, in step S2, the temperature is adjusted to 60 - 180 °C.

[0019] Preferably, in step S3, the molar ratio of the amount of Cd element to the amount of the reducing agent is 1:2 - 1:10; the molar ratio of the amount of Cd element to the amount of As element is 3:2 - 5:1.

[0020] Preferably, in step S3, the reaction temperature is 60 - 300 °C, and the reaction time is 5 min - 24 h.

[0021] Preferably, in step S4, the non-polar solvent is one or a mixture of several of n-hexane, toluene, chloroform, and tetrachloroethylene.

[0022] The present invention adopts the above-mentioned method for synthesizing cadmium arsenide quantum dots, and the beneficial effects are as follows:

[0023] The present invention uses cadmium (Cd) nanocrystals as the initial product. After reacting the Cd nanocrystals with an arsenic (As) source, cadmium arsenide quantum dots are prepared; by adjusting the reaction parameters for obtaining the Cd nanocrystals, cadmium arsenide nanocrystals with adjustable sizes and stable dispersions can be obtained. This controllable synthesis idea of the present invention lays a good foundation for the application of cadmium arsenide quantum dots in fields such as photodetectors.

[0024] The technical solution of the present invention will be further described in detail below through the drawings and examples. Description of the Drawings

[0025] Figure 1 It is a flowchart of an embodiment of the method for synthesizing cadmium arsenide quantum dots of the present invention;

[0026] Figure 2 XRD pattern of Cd nanocrystals obtained after the reaction of Cd source with reducing agent and reactant at 60 °C in Example 1 of the synthesis method of cadmium arsenide quantum dots of the present invention;

[0027] Figure 3 XRD pattern of Cd nanocrystals obtained after the reaction of Cd source with reducing agent and reactant at 180 °C in Example 2 of the synthesis method of cadmium arsenide quantum dots of the present invention;

[0028] Figure 4 For Example 3 of the synthesis method of cadmium arsenide quantum dots of the present invention, the test chart of 6nm Cd 3 As 2 nanocrystals; among them, (a) is the XRD pattern; (b) is the transmission electron microscope photograph;

[0029] Figure 5 For Example 4 of the synthesis method of cadmium arsenide quantum dots of the present invention, the transmission electron microscope photograph of 8nm Cd 3 As 2 nanocrystals;

[0030] Figure 6 For Example 5 of the synthesis method of cadmium arsenide quantum dots of the present invention, the test chart of 14nm Cd 3 As 2 nanocrystals; among them, (a) is the XRD pattern; (b) is the transmission electron microscope photograph. Detailed implementation manners

[0031] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and examples.

[0032] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings understood by those of ordinary skill in the field to which the present invention belongs.

[0033] Example 1

[0034] As Figure 1 shown, a synthesis method of cadmium arsenide quantum dots includes the following steps:

[0035] Step S1, preparing a Cd precursor solution, a reducing agent solution and an As precursor solution.

[0036] Disperse 0.3 mmol of cadmium chloride in 5 mL of oleylamine to obtain a Cd precursor solution.

[0037] The reducing agent solution is 1.2 mL of diisobutylaluminum hydride with a concentration of 1 M dispersed in tetrahydrofuran.

[0038] The As precursor solution is 0.5 mL of trimethylarsineamine with a concentration of 0.4 M dispersed in oleylamine.

[0039] Step S2: After evacuating the Cd precursor solution at 130 °C for 60 minutes, introduce nitrogen into the reaction system and cool it to 60 °C, as Figure 2 shown.

[0040] Step S3: After quickly injecting 1.2 mL of the reducing agent solution and 0.2 mmol of the As precursor solution, keep it at 60 °C for 5 min.

[0041] Step S4: After the heat preservation, cool it to room temperature. After cooling to room temperature, wash the product with ethanol and disperse it in toluene.

[0042] Example 2

[0043] A method for synthesizing cadmium arsenide quantum dots, comprising the following steps:

[0044] Step S1: Prepare a Cd precursor solution, a reducing agent solution, and an As precursor solution.

[0045] Disperse 0.3 mmol of cadmium chloride in 5 mL of oleylamine to obtain the Cd precursor solution.

[0046] The reducing agent solution is 1.2 mL of diisobutylaluminum hydride with a concentration of 1 M dispersed in tetrahydrofuran.

[0047] The As precursor solution is 0.5 mL of trimethylarsineamine with a concentration of 0.4 M dispersed in oleylamine.

[0048] Step S2: After evacuating the Cd precursor solution at 130 °C for 60 minutes, introduce nitrogen into the reaction system and heat it to 180 °C, as Figure 3 shown.

[0049] Step S3: After quickly injecting 1.2 mL of the reducing agent solution and 0.2 mmol of the As precursor solution, keep it at 180 °C for 5 min.

[0050] Step S4: After the heat preservation, cool it to room temperature. After cooling to room temperature, wash the product with ethanol and disperse it in toluene.

[0051] Example 3

[0052] A method for synthesizing cadmium arsenide quantum dots, comprising the following steps:

[0053] Step S1: Prepare a Cd precursor solution, a reducing agent solution, and an As precursor solution.

[0054] Disperse 0.3 mmol of cadmium chloride in 5 mL of oleylamine to obtain the Cd precursor solution.

[0055] The reducing agent solution is 2.4 mL of diisobutylaluminum hydride with a concentration of 1 M dispersed in tetrahydrofuran.

[0056] The As precursor solution is 0.5 mL of trimethylarsine with a concentration of 0.4 M dispersed in oleylamine.

[0057] Step S2: After evacuating the Cd precursor solution at 130 °C for 30 minutes, introduce nitrogen into the reaction system and cool down to 60 °C.

[0058] Step S3: After quickly injecting 2.4 mL of the reducing agent solution and 0.2 mmol of the As precursor solution, heat up to 260 °C (heating rate is 4 °C / min) and then hold for 5 min.

[0059] Step S4: After the holding is completed, cool down to room temperature. After cooling to room temperature, wash the product with ethanol and disperse it in toluene. As Figure 4 shown, the size of the Cd 3 As 2 nanocrystals is 6 nm.

[0060] Example 4

[0061] A method for synthesizing cadmium arsenide quantum dots, comprising the following steps:

[0062] Step S1: Prepare the Cd precursor solution, the reducing agent solution and the As precursor solution.

[0063] Disperse 0.3 mmol of cadmium chloride in 5 mL of oleylamine to obtain the Cd precursor solution.

[0064] The reducing agent solution is 1.2 mL of diisobutylaluminum hydride with a concentration of 1 M dispersed in tetrahydrofuran.

[0065] The As precursor solution is 0.5 mL of trimethylarsine with a concentration of 0.4 M dispersed in oleylamine.

[0066] Step S2: After evacuating the Cd precursor solution at 130 °C for 30 minutes, introduce nitrogen into the reaction system and heat up to 180 °C.

[0067] Step S3: After quickly injecting 1.2 mL of the reducing agent solution and 0.2 mmol of the As precursor solution, heat up to 260 °C (heating rate is 4 °C / min) and then hold for 5 min.

[0068] Step S4: After the holding is completed, cool down to room temperature. After cooling to room temperature, wash the product with ethanol and disperse it in toluene. As Figure 5 shown, the Cd 3 As 2The size of the nanocrystals is 8 nm.

[0069] Example 5

[0070] A method for synthesizing cadmium arsenide quantum dots, comprising the following steps:

[0071] Step S1, prepare a Cd precursor solution, a reducing agent solution and an As precursor solution.

[0072] Disperse 2.4 mmol of cadmium chloride in 20 mL of oleylamine to obtain a Cd precursor solution.

[0073] The reducing agent solution is 4.8 mL of diisobutylaluminum hydride with a concentration of 1 M dispersed in tetrahydrofuran.

[0074] The As precursor solution is 2 mL of tris(dimethylamino)arsine with a concentration of 0.4 M dispersed in oleylamine.

[0075] Step S2, after evacuating the Cd precursor solution at 130 °C for 30 minutes, introduce nitrogen into the reaction system and heat up to 180 °C.

[0076] Step S3, quickly inject 4.8 mL of the reducing agent solution and 0.8 mmol of the As precursor solution, then heat up to 260 °C (heating rate is 4 °C / min) and keep warm for 5 min.

[0077] Step S4, after the heat preservation is completed, cool to room temperature. After cooling to room temperature, wash the product with ethanol and disperse it in toluene. As Figure 6 shown, the size of the Cd 3 As 2 nanocrystals is 14 nm.

[0078] Therefore, the present invention adopts the above method for synthesizing cadmium arsenide quantum dots. This method uses cadmium as the initial product and finally obtains cadmium arsenide quantum dots; by adjusting the reaction parameters for obtaining cadmium nanocrystals, cadmium arsenide nanocrystals with adjustable size and stable dispersion can be obtained.

[0079] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for synthesizing cadmium arsenide quantum dots, characterized in that: The following steps are involved: Step S1, preparing a Cd precursor solution, a reducing agent solution and an As precursor solution; Step S2, after the Cd precursor solution is evacuated for 30-60 minutes, an inert gas is introduced into the reaction system and the temperature is adjusted; Step S3, quickly injecting the reducing agent solution and the As precursor solution to react, and then keeping warm after injection, the keeping warm time is 1 minute to 24 hours; Step S4, cooling to room temperature after the heat preservation, dispersing in a non-polar solvent after multiple washings, and obtaining cadmium arsenide quantum dots.

2. The method for synthesizing cadmium arsenide quantum dots according to claim 1, characterized in that: In step S1, the Cd precursor solution includes a Cd source, an organic ligand and an organic solution; the Cd source includes a mixture of one or more of cadmium oxide, cadmium acetate, and CdX2, wherein X includes Cl, Br, and I; the organic ligand is a long-chain amine or a long-chain carboxylic acid, and the addition amount is 5-20 mL; the organic solution includes a mixture of one or more of a long-chain amine, a long-chain carboxylic acid ligand, and a solvent solution; and the solvent solution is a long-chain alkene acid or an alkane.

3. The method for synthesizing cadmium arsenide quantum dots according to claim 2, characterized in that: Cd in Cd precursor solution 2+ The concentration is 0.06-1M; the amount of organic solution added is 5-20mL, the total volume of the long-chain amine and the long-chain carboxylic acid accounts for 10-100% of the volume of the organic solution, and the long-chain amine and the long-chain carboxylic acid ligands contain 8-20 carbon atoms respectively.

4. The method for synthesizing cadmium arsenide quantum dots according to claim 1, characterized in that: In step S1, the reducing agent solution includes a reducing agent and an organic solution, the added amount of the reducing agent is 0.6-10 mmol, and the organic solution is 0.3-10 mL; the reducing agent is one or a mixture of two of diisobutylaluminum hydride and lithium triethylborohydride; the organic solution is a mixture of one or more of tetrahydrofuran, n-octane, n-hexane, toluene, and dioctyl ether.

5. The method for synthesizing cadmium arsenide quantum dots according to claim 1, characterized in that: In step S1, the As precursor solution includes an As source and oleylamine. The amount of the As source added is 0.2-0.8 mmol, and the volume of the oleylamine is 0.5-2 mL. The As source is one of tris(dimethylamino)arsenic and tris(trimethylsilyl)arsenic, or a mixture of the two.

6. The method for synthesizing cadmium arsenide quantum dots according to claim 1, characterized in that: In step S2, the temperature is adjusted to 60-180°C.

7. The method for synthesizing cadmium arsenide quantum dots according to claim 1, characterized in that: In step S3, the molar ratio of the Cd element to the reducing agent is 1:2-1:10; the molar ratio of the Cd element to the As element is 3:2-5:

1.

8. The method for synthesizing cadmium arsenide quantum dots according to claim 1, characterized in that: In step S3, the reaction temperature is 60-300° C., and the reaction time is 5 min-24 h.

9. The method for synthesizing cadmium arsenide quantum dots according to claim 1, characterized in that: In step S4, the non-polar solvent is a mixture of one or more of n-hexane, toluene, chloroform and tetrachloroethylene.

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