Method for preparing compound quantum dot colloidal solution by liquid phase laser irradiation technique

Abstract

This invention belongs to the field of materials preparation technology, specifically a method for preparing colloidal solutions of compound quantum dots using liquid-phase laser irradiation technology. The method first uses liquid-phase laser irradiation to obtain a colloidal solution of compound quantum dots, then removes the solvent using vacuum distillation to obtain the compound quantum dots. This invention achieves controllable preparation of compound quantum dots by adjusting laser irradiation parameters, reaction time, reaction temperature, and solvent type. This invention solves the problems of rapid, controllable, and large-scale preparation of compound quantum dots, providing a novel and universal strategy for their preparation, which will help promote the further development of compound quantum dots in optoelectronics, energy storage, and catalysis.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation technology, and specifically relates to a method for preparing compound quantum dot colloidal solutions using liquid phase laser irradiation technology. Background Technology

[0002] Quantum dots are an important class of low-dimensional semiconductor materials, requiring all three dimensions to be smaller than the exciton Bohr radius of their parent semiconductor material. They are commonly spherical or near-spherical in shape, with diameters typically below 20 nm. This unique particle size endows quantum dots with a series of quantum effects, such as size effects, tunneling effects, confinement effects, surface effects, and blocking effects. Therefore, quantum dot materials exhibit physicochemical properties completely different from their macroscopic parent materials, showing significant application potential in catalysis, biology, and medicine. For example, in life sciences, the emission spectrum of quantum dots is size-dependent, allowing for full visible light coverage by adjusting the quantum dot size. Simultaneously, quantum dots exhibit good photostability and long fluorescence lifetimes, enabling long-term observation as markers. Furthermore, quantum dots demonstrate good biocompatibility, making them ideal fluorescent probes in biomolecular research. Moreover, changes in the density of states and energy level structure of quantum dots alter their optoelectronic properties, offering broad application prospects in single-electron devices and optoelectronic devices.

[0003] Based on their composition, quantum dot materials are generally classified into elemental quantum dots, compound quantum dots, and heterojunction quantum dots. Elemental quantum dots are mainly composed of single elements, such as carbon quantum dots, silicon quantum dots, and germanium quantum dots, and are of great potential in the field of microelectronics. Compound quantum dots mainly include group VI-VII compounds, such as GaAs, PbS, CdS, PbSe, and CdTe, and can be used in quantum dot lasers, quantum dot photodetectors, and quantum dot solar cells. Heterojunction quantum dots are a new type of quantum dot material, belonging to a composite system composed of two or more quantum dots forming a heterostructure, such as perovskite-lead sulfide quantum dots. They enable the control of the quantum dot band structure, achieving efficient applications. Therefore, given the important applications of quantum dot materials, efficient and controllable synthesis strategies are particularly crucial.

[0004] Currently, common strategies for synthesizing compound quantum dots mainly include: chemical solution methods, epitaxial growth methods, and electric field confinement methods. Epitaxial growth methods are further divided into chemical vapor deposition and molecular beam epitaxy, where quantum dots crystallize on the surface of a substrate material. Electric field confinement methods utilize electric potential to adjust the energy band of semiconductors, forming nanoscale quantum dots using an electric field, but have the lowest yield. Chemical solution methods are the most common strategy for preparing colloidal quantum dots. Currently, most semiconductor materials can be synthesized using this method, with low preparation cost and high yield. However, because organic solvents are used in the synthesis process, ligands will form on the surface of the quantum dots, and the synthesis cycle and reaction steps are long. Furthermore, many toxic substances are present, which is inconsistent with the background of green chemistry.

[0005] Therefore, there is an urgent need to develop a green, novel, efficient and universal strategy for synthesizing compound quantum dots, which is of great significance for realizing green chemistry and the development of compound quantum dot applications. Summary of the Invention

[0006] To address the shortcomings of the existing technologies, this invention provides a method for preparing colloidal solutions of compound quantum dots using liquid-phase laser irradiation technology. This invention provides a green, efficient, and universally applicable method for preparing compound quantum dots, obtaining pure compound quantum dots with uniform particle size, and overcoming the technical defects of existing preparation methods.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] The reactants in this invention are only compound precursors. The compound precursors are dispersed in a solvent, and the target product is obtained by liquid phase laser irradiation technology. Compared with the prior art, no new impurities are introduced during the preparation process, so the obtained compound quantum dot products are pure. In addition, the particle size distribution of the compound quantum dots is uniform, which is mainly due to the reduction of particle agglomeration caused by the rapid cooling of the solvent during the laser melting process.

[0009] A method for preparing colloidal solutions of compound quantum dots using liquid-phase laser irradiation technology includes the following steps:

[0010] A compound precursor with a particle size in the micrometer range is dispersed in a solvent to obtain a compound dispersion.

[0011] The anions of the compound precursors are: Group V to Group VII elements other than oxygen, and the cations are not limited. The compounds must be able to form solid forms. Compared with other non-metallic element-based compounds, oxides have high melting points and stable chemical properties. Therefore, the preparation of oxide quantum dots requires strong energy and dissolution at room temperature, and requires the use of strongly polar solvents for dissolution. This is fundamentally different from the preparation conditions of compound quantum dots. Therefore, the conditions of this application cannot be used to prepare oxide quantum dots.

[0012] Under a protective atmosphere, the compound dispersion was irradiated using liquid phase laser irradiation technology. The irradiation process instantly generated a high-temperature melting of the compound precursor. At the same time, the solvent environment was controlled at a constant low temperature. The compound in the high-temperature molten state rapidly condensed into nano-sized ultrafine particles in the solvent, resulting in a compound quantum dot colloidal solution. The solvent in the compound quantum dot colloidal solution was then separated to obtain the compound quantum dots.

[0013] Preferably, the anion of the compound precursor is one of N, P, As, S, Se, Te, and I.

[0014] Preferably, the irradiation conditions are: laser irradiation energy of 0.2-1.0J for 1-10 minutes. The laser irradiation energy for preparing compound quantum dots is relatively low, while quantum dots obtained under high laser irradiation energy are more prone to aggregation.

[0015] Preferably, the laser emission wavelength for irradiation is 1064 nm, and the laser irradiation range is 1.3 cm.

[0016] Preferably, the irradiation treatment environment temperature is -20℃ to 0℃, and the low temperature avoids the aggregation of compound quantum dots.

[0017] Preferably, the irradiation treatment is carried out at an ambient temperature of -20°C, which was obtained through experimental screening.

[0018] Preferably, the solvent is an alcohol solvent; based on the active properties of non-metallic elements, they can interact with the functional groups on the surface of alcohols to form a micro-interaction layer on the surface of quantum dots, achieving high dispersibility. For example, S, Cl, and Br readily form hydrogen bonds with hydroxyl groups, thereby improving the dispersibility of the compound quantum dot system.

[0019] Preferably, the mass ratio of the compound precursor to the volume ratio of the solvent in the compound dispersion is 0.1–3.0 mg / mL.

[0020] Preferably, the mass ratio of the compound precursor to the volume ratio of the solvent in the compound dispersion is 3.0 mg / mL, which was obtained through experimental screening.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. This invention rapidly prepares colloidal solutions of compound quantum dots under liquid-phase laser irradiation. The anions of the compound precursors are elements from Group V to Group VII, excluding oxygen. The types of compounds are diverse, and alcohol solvents are applicable to this application, demonstrating the universality of the preparation method.

[0023] 2. Compared with the prior art, the present invention uses compound precursors as raw materials to obtain compound quantum dots under laser irradiation. The compound quantum dot synthesis route is efficient and green. There are no ligands on the surface of the quantum dots, and the quantum dots and solvent form an interaction force, resulting in a uniformly dispersed quantum dot colloidal solution with uniform particle size.

[0024] 3. Studies have shown that the concentration of compound quantum dots is correlated with ambient temperature. After systematically studying the effect of temperature on the synthesis route, the limitations of low yield in traditional laser technology have been overcome, which is of great help to the development of compound quantum dot synthesis technology. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the preparation of compound quantum dots using liquid-phase laser irradiation technology;

[0026] Figure 2 In the middle, the left image is an optical photograph of the PbS dispersion of Example 1 of the present invention, and the right image is an optical photograph of the PbS quantum dot colloidal solution of Example 1 of the present invention.

[0027] Figure 3 The images show TEM images and particle size distributions of the PbS quantum dot colloidal solution from Example 1 of this invention.

[0028] Figure 4 The XRD patterns are of the PbS dispersion and PbS quantum dot colloidal solution of Example 1 of the present invention.

[0029] Figure 5 In the figure, (a) is the XPS diagram of the PbS dispersion of Example 1 of the present invention, and (b) is the XPS diagram of the PbS quantum dot colloidal solution of Example 1 of the present invention.

[0030] Figure 6 In the image, (a) is an optical photograph of the PbS quantum dot colloidal solution of Example 2 of the present invention, and (b) is a TEM image and particle size distribution of the PbS quantum dot colloidal solution of Example 2 of the present invention.

[0031] Figure 7 In the image, (a) is an optical photograph of the PbS quantum dot colloidal solution of Example 3 of the present invention, and (b) is a TEM image and particle size distribution of the PbS quantum dot colloidal solution of Example 3 of the present invention.

[0032] Figure 8 In the image, (a) is an optical photograph of the PbS quantum dot colloidal solution of Example 4 of the present invention, and (b) is a TEM image and particle size distribution of the PbS quantum dot colloidal solution of Example 4 of the present invention.

[0033] Figure 9 An optical photograph of the PbS quantum dot colloidal solution of Comparative Example 1 of this invention;

[0034] Figure 10 The images show the TEM image and particle size distribution of the PbSe quantum dot colloidal solution from Example 5 of this invention.

[0035] Figure 11 The images show the TEM image and particle size distribution of the GaAs quantum dot colloidal solution in Example 6 of this invention.

[0036] Figure 12 The images show TEM images and particle size distributions of the CdTe quantum dot colloidal solution from Example 7 of this invention. Detailed Implementation

[0037] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods.

[0038] The oxide quantum dots cannot be obtained using the conditions of this invention because, compared to oxides, the compounds of this invention have lower melting points and are chemically unstable, meaning they are chemically reactive. Therefore, only low laser energy is required for the preparation of compound quantum dots. If the laser energy is the same as that used for oxides, the compound quantum dots will grow and aggregate. In addition, due to the low melting point of the compounds, they need to be dissolved at low temperatures. The reaction is fast at room temperature, which easily leads to aggregation. The compound precursor is dispersed using alcohol solvents, while the oxide precursor is dispersed using polar solvents other than alcohol solvents. The oxide melts and reacts slowly or not at all in alcohol solvents, while the compound precursor is dissolved in polar solvents other than alcohol solvents, which leads to a faster reaction and may even cause the obtained quantum dots to dissolve directly. Therefore, the preparation conditions of the two are fundamentally different.

[0039] The technical solution of this application will be further explained and illustrated below with examples and comparative examples, as detailed below:

[0040] Example 1

[0041] The preparation method of PbS quantum dot colloidal solution includes the following steps:

[0042] S1. Commercial PbS powder was vacuum ball-milled at a speed of 400 rpm for 12 h to obtain a black PbS precursor.

[0043] S2. Using the PbS precursor from step S1, prepare a 0.2 mg / mL PbS dispersion. Ethanol is used as the solvent. The PbS dispersion is ultrasonically dispersed to obtain a black PbS dispersion.

[0044] S3. Using a circulating condenser to control the ambient temperature at 0℃, the PbS dispersion from step S2 is subjected to laser treatment. The entire process is protected by a nitrogen atmosphere and ultrasonically assisted. The Nd:YAG pulsed laser is adjusted to achieve a pulse frequency of 10Hz, a pulse width of 8ns, a spot size of 13mm, a laser energy of 0.8J, and an irradiation time of 5min, resulting in a reddish-brown PbS quantum dot colloidal solution.

[0045] Example 2

[0046] The preparation method of PbS quantum dot colloidal solution includes the following steps:

[0047] S1. Commercial PbS powder was vacuum ball-milled at a speed of 400 rpm for 12 h to obtain a black PbS precursor.

[0048] S2. Using the PbS precursor from step S1, prepare a 1 mg / mL PbS dispersion. Ethanol is used as the solvent. The PbS dispersion is ultrasonically dispersed to obtain a black PbS dispersion.

[0049] S3. Using a circulating condenser to control the ambient temperature at 0℃, the PbS dispersion from step S2 is subjected to laser treatment. The entire process is protected by a nitrogen atmosphere and ultrasonically assisted. The Nd:YAG pulsed laser is adjusted to achieve a pulse frequency of 10Hz, a pulse width of 8ns, a spot size of 13mm, a laser energy of 0.8J, and an irradiation time of 5min, resulting in a reddish-brown PbS quantum dot colloidal solution.

[0050] Example 3

[0051] The preparation method of PbS quantum dot colloidal solution includes the following steps:

[0052] S1. Commercial PbS powder was vacuum ball-milled at a speed of 400 rpm for 12 h to obtain a black PbS precursor.

[0053] S2. Using the PbS precursor from step S1, prepare a 1.5 mg / mL PbS dispersion. Ethanol is used as the solvent. The PbS dispersion is ultrasonically dispersed to obtain a black PbS dispersion.

[0054] S3. Using a circulating condenser to control the ambient temperature at -10℃, the PbS dispersion from step S2 is subjected to laser treatment. The entire process is protected by a nitrogen atmosphere and ultrasonically assisted. The Nd:YAG pulsed laser is adjusted to achieve a pulse frequency of 10Hz, a pulse width of 8ns, a spot size of 13mm, a laser energy of 0.8J, and an irradiation time of 5min, resulting in a reddish-brown PbS quantum dot colloidal solution.

[0055] Example 4

[0056] The preparation method of PbS quantum dot colloidal solution includes the following steps:

[0057] S1. Commercial PbS powder was vacuum ball-milled at a speed of 400 rpm for 12 h to obtain a black PbS precursor.

[0058] S2. Using the PbS precursor from step S1, prepare a 3.0 mg / mL PbS dispersion. Ethanol is used as the solvent. The PbS dispersion is ultrasonically dispersed to obtain a black PbS dispersion.

[0059] S3. Using a circulating condenser to control the ambient temperature at -20℃, the PbS dispersion from step S2 is subjected to laser treatment. The entire process is protected by a nitrogen atmosphere and ultrasonic-assisted treatment. The Nd:YAG pulsed laser is adjusted to achieve a pulse frequency of 10Hz, a pulse width of 8ns, a spot size of 13mm, a laser energy of 0.8J, and an irradiation time of 5min, resulting in a reddish-brown PbS quantum dot colloidal solution.

[0060] Example 5

[0061] The preparation method of PbSe quantum dot colloidal solution includes the following steps:

[0062] S1. Commercial PbSe powder was vacuum ball-milled at a speed of 400 rpm for 12 hours to obtain a black PbSe precursor.

[0063] S2. Using the PbSe precursor from step S1, prepare a 0.2 mg / mL PbSe dispersion. Ethanol is used as the solvent. The dispersion is ultrasonically dispersed until uniform, and the PbSe dispersion is black.

[0064] S3. Using a circulating condenser to control the ambient temperature at 0℃, the PbSe dispersion from step S2 is subjected to laser treatment. The entire process is protected by a nitrogen atmosphere and ultrasonic-assisted treatment. The Nd:YAG pulsed laser is adjusted to achieve a pulse frequency of 10Hz, a pulse width of 8ns, a spot size of 13mm, a laser energy of 0.6J, and an irradiation time of 5min, resulting in a reddish-brown PbSe quantum dot colloidal solution.

[0065] Example 6

[0066] The method for preparing GaAs quantum dot colloidal solution includes the following steps:

[0067] S1. Commercial GaAs powder was vacuum ball-milled at a speed of 400 rpm for 12 h to obtain a black GaAs precursor.

[0068] S2. Using the GaAs precursor from step S1, prepare a 0.2 mg / mL GaAs dispersion. Ethanol is used as the solvent. The dispersion is ultrasonically dispersed until uniform, and the GaAs dispersion is black.

[0069] S3. Using a circulating condenser to control the ambient temperature at 0℃, the GaAs dispersion from step S2 is subjected to laser treatment. The entire process is protected by a nitrogen atmosphere and ultrasonically assisted. The Nd:YAG pulsed laser is adjusted to achieve a pulse frequency of 10Hz, a pulse width of 8ns, a spot size of 13mm, a laser energy of 0.5J, and an irradiation time of 5min, resulting in a reddish-brown GaAs quantum dot colloidal solution.

[0070] Example 7

[0071] The preparation method of CdTe quantum dot colloidal solution includes the following steps:

[0072] S1. Commercial CdTe powder was vacuum ball-milled at a speed of 400 rpm for 12 hours to obtain a black CdTe precursor.

[0073] S2. Using the CdTe precursor from step S1, prepare a 0.2 mg / mL CdTe dispersion. Ethanol is used as the solvent. The dispersion is ultrasonically dispersed until uniform, and the CdTe dispersion is black.

[0074] S3. Using a circulating condenser to control the ambient temperature at 0℃, the CdTe dispersion from step S2 is subjected to laser treatment. The entire process is protected by a nitrogen atmosphere and ultrasonic-assisted treatment. The Nd:YAG pulsed laser is adjusted to achieve a pulse frequency of 10Hz, a pulse width of 8ns, a spot size of 13mm, a laser energy of 1.0J, and an irradiation time of 5min, resulting in a reddish-brown CdTe quantum dot colloidal solution.

[0075] Example 8

[0076] The method for preparing TiN quantum dot colloidal solution includes the following steps:

[0077] S1. Commercial TiN powder was vacuum ball-milled at a speed of 400 rpm for 12 h to obtain TiN precursor.

[0078] S2. Using the TiN precursor from step S1, prepare a 0.2 mg / mL TiN dispersion. Use glycerol as the solvent. Disperse the TiN evenly by ultrasonication to obtain the TiN dispersion.

[0079] S3. Using a circulating condenser to control the ambient temperature at 0℃, the TiN dispersion from step S2 is subjected to laser treatment. The entire process is protected by a nitrogen atmosphere and ultrasonically assisted. The Nd:YAG pulsed laser is adjusted to achieve a pulse frequency of 10Hz, a pulse width of 8ns, a spot size of 13mm, a laser energy of 0.2J, and an irradiation time of 10min to obtain a TiN quantum dot colloidal solution.

[0080] Example 9

[0081] The preparation method of VN quantum dot colloidal solution includes the following steps:

[0082] S1. Commercial VN powder was vacuum ball-milled at a speed of 400 rpm for 12 hours to obtain VN precursor.

[0083] S2. Using the VN precursor from step S1, prepare a 0.2 mg / mL VN dispersion. Ethylene glycol is used as the solvent. Disperse the VN evenly by ultrasonication to obtain the VN dispersion.

[0084] S3. Using a circulating condenser to control the ambient temperature at 0℃, the VN dispersion from step S2 is subjected to laser treatment. The entire process is protected by a nitrogen atmosphere and ultrasonically assisted. The Nd:YAG pulsed laser is adjusted to achieve a pulse frequency of 10Hz, a pulse width of 8ns, a spot size of 13mm, a laser energy of 0.3J, and an irradiation time of 9min, to obtain a VN quantum dot colloidal solution.

[0085] Example 10

[0086] The preparation method of CdS quantum dot colloidal solution includes the following steps:

[0087] S1. Commercial CdS powder was vacuum ball-milled at a speed of 400 rpm for 12 hours to obtain CdS precursor.

[0088] S2. Using the CdS precursor from step S1, prepare a 0.2 mg / mL CdS dispersion. Ethylene glycol is used as the solvent. The dispersion is ultrasonically dispersed to obtain a uniform CdS dispersion.

[0089] S3. Using a circulating condenser to control the ambient temperature at -10℃, the CdS dispersion from step S2 is subjected to laser treatment. The entire process is protected by a nitrogen atmosphere and ultrasonically assisted. The Nd:YAG pulsed laser is adjusted to achieve a pulse frequency of 10Hz, a pulse width of 8ns, a spot size of 13mm, a laser energy of 0.4J, and an irradiation time of 8min, to obtain a CdS quantum dot colloidal solution.

[0090] Example 11

[0091] The preparation method of SeS2 quantum dot colloidal solution includes the following steps:

[0092] S1. Commercial SeS2 powder was vacuum ball-milled at a speed of 500 rpm for 16 h to obtain the SeS2 precursor.

[0093] S2. Using the SeS2 precursor from step S1, prepare a 0.2 mg / mL SeS2 dispersion. Ethylene glycol is used as the solvent. The dispersion is ultrasonically dispersed to obtain a uniform SeS2 dispersion.

[0094] S3. Using a circulating condenser to control the ambient temperature at -10℃, the SeS2 dispersion from step S2 is subjected to laser treatment. The entire process is protected by a nitrogen atmosphere and ultrasonic-assisted treatment. The Nd:YAG pulsed laser is adjusted to achieve a pulse frequency of 10Hz, a pulse width of 8ns, a spot size of 13mm, a laser energy of 0.5J, and an irradiation time of 7min, to obtain a SeS2 quantum dot colloidal solution.

[0095] Example 12

[0096] The preparation method of SnS2 quantum dot colloidal solution includes the following steps:

[0097] S1. Commercial SnS2 powder was vacuum ball-milled at a speed of 600 rpm for 8 hours to obtain SnS2 precursor.

[0098] S2. Using the SnS2 precursor from step S1, prepare a 0.2 mg / mL SnS2 dispersion. Ethylene glycol is used as the solvent. The dispersion is ultrasonically dispersed to obtain a uniform SnS2 dispersion.

[0099] S3. Using a circulating condenser to control the ambient temperature at -15℃, the SnS2 dispersion from step S2 is subjected to laser treatment. The entire process is protected by a nitrogen atmosphere and ultrasonically assisted. The Nd:YAG pulsed laser is adjusted to achieve a pulse frequency of 10Hz, a pulse width of 8ns, a spot size of 13mm, a laser energy of 0.4J, and an irradiation time of 6min to obtain a SnS2 quantum dot colloidal solution.

[0100] Example 13

[0101] The preparation method of Sb2S3 quantum dot colloidal solution includes the following steps:

[0102] S1. Commercial Sb2S3 powder was vacuum ball-milled at a speed of 300 rpm for 20 h to obtain the Sb2S3 precursor.

[0103] S2. Using the Sb2S3 precursor from step S1, prepare a 3.0 mg / mL Sb2S3 dispersion. Ethylene glycol is used as the solvent. The dispersion is ultrasonically dispersed to obtain the Sb2S3 dispersion.

[0104] S3. Using a circulating condenser to control the ambient temperature at -15℃, the Sb2S3 dispersion from step S2 is subjected to laser treatment. The entire process is protected by a nitrogen atmosphere and ultrasonically assisted. The Nd:YAG pulsed laser is adjusted to achieve a pulse frequency of 10Hz, a pulse width of 8ns, a spot size of 13mm, a laser energy of 0.3J, and an irradiation time of 5min, to obtain an Sb2S3 quantum dot colloidal solution.

[0105] Example 14

[0106] The preparation method of Sb₂Se₃ quantum dot colloidal solution includes the following steps:

[0107] S1. Commercial Sb2Se3 powder was vacuum ball-milled at a speed of 500 rpm for 16 h to obtain the Sb2Se3 precursor.

[0108] S2. Using the Sb2Se3 precursor from step S1, prepare a 1.5 mg / mL Sb2Se3 dispersion. Ethylene glycol is used as the solvent. The dispersion is ultrasonically dispersed to obtain the Sb2Se3 dispersion.

[0109] S3. Using a circulating condenser to control the ambient temperature at -20℃, the Sb2Se3 dispersion from step S2 is subjected to laser treatment. The entire process is protected by a nitrogen atmosphere and ultrasonic-assisted treatment. The Nd:YAG pulsed laser is adjusted to achieve a pulse frequency of 10Hz, a pulse width of 8ns, a spot size of 13mm, a laser energy of 0.2J, and an irradiation time of 5min, to obtain an Sb2Se3 quantum dot colloidal solution.

[0110] Example 15

[0111] The preparation method of CdMnTe quantum dot colloidal solution includes the following steps:

[0112] S1. Commercial CdMnTe powder was vacuum ball-milled at a speed of 600 rpm for 8 hours to obtain CdMnTe precursor.

[0113] S2. Using the CdMnTe precursor from step S1, prepare a 1.5 mg / mL CdMnTe dispersion. Ethylene glycol is used as the solvent. The dispersion is ultrasonically dispersed to obtain a uniform CdMnTe dispersion.

[0114] S3. Using a circulating condenser to control the ambient temperature at -20℃, the CdMnTe dispersion from step S2 is subjected to laser treatment. The entire process is protected by a nitrogen atmosphere and ultrasonically assisted. The Nd:YAG pulsed laser is adjusted to achieve a pulse frequency of 10Hz, a pulse width of 8ns, a spot size of 13mm, a laser energy of 0.8J, and an irradiation time of 2min, to obtain a CdMnTe quantum dot colloidal solution.

[0115] Example 16

[0116] The preparation method of PbI quantum dot colloidal solution includes the following steps:

[0117] S1. Commercial PbI powder was vacuum ball-milled at a speed of 300 rpm for 20 h to obtain the PbI precursor.

[0118] S2. Using the PbI precursor from step S1, prepare a 1.5 mg / mL PbI dispersion. Ethylene glycol is used as the solvent. The PbI dispersion is ultrasonically dispersed to obtain a uniform PbI dispersion.

[0119] S3. Using a circulating condenser to control the ambient temperature at -20℃, the PbI dispersion from step S2 is subjected to laser treatment. The entire process is protected by a nitrogen atmosphere and ultrasonic-assisted treatment. The Nd:YAG pulsed laser is adjusted to achieve a pulse frequency of 10Hz, a pulse width of 8ns, a spot size of 13mm, a laser energy of 1.0J, and an irradiation time of 1min, thereby obtaining a PbI quantum dot colloidal solution.

[0120] Comparative Example 1

[0121] The preparation method of PbS quantum dot colloidal solution includes the following steps:

[0122] S1. Commercial PbS powder was vacuum ball-milled at a speed of 400 rpm for 12 h to obtain a black PbS precursor.

[0123] S2. Using the PbS precursor from step S1, prepare a 3.5 mg / mL PbS dispersion. Acetone is used as the solvent. The PbS dispersion is ultrasonically dispersed until it is uniformly dispersed and appears black.

[0124] S3. Using a circulating condenser to control the ambient temperature at -40℃, the PbS dispersion from step S2 is subjected to laser treatment. The entire process is protected by a nitrogen atmosphere and ultrasonically assisted. The Nd:YAG pulsed laser is adjusted to achieve a pulse frequency of 10Hz, a pulse width of 8ns, a laser energy of 0.8J, and an irradiation time of 5min, to obtain a PbS quantum dot colloidal solution.

[0125] The technical effect is verified below using the quantum dot colloidal solutions of Examples 1-16 and Comparative Example 1 as examples. The specific analysis is as follows:

[0126] according to Figure 1The synthesis route of compound quantum dots shows that after ball milling, micron-sized compound particles are treated with liquid-phase laser irradiation. The laser instantly melts the compound powder at high temperature, and the solvent acts as a rapid cooling agent. The compound droplets condense into quantum dots as soon as they cool. The lower the solvent temperature, the stronger the condensation ability of quantum dots and the higher the concentration of the quantum dot colloidal solution. It is worth noting that when the laser energy is at a high level, the particle size of quantum dots is no longer affected by the laser energy.

[0127] A systematic comparison and comprehensive analysis were conducted, focusing primarily on the preparation of PbS quantum dots. Figure 2 The images show optical photographs of the 0.2 mg / mL PbS dispersion before laser treatment and the PbS quantum dot colloidal solution after laser treatment in Example 1. The PbS dispersion is grayish-black, while the PbS quantum dot colloidal solution formed after laser treatment is transparent yellowish-brown. The beam irradiation shows a significant Tyndall effect, and the solution is uniformly distributed.

[0128] Figure 3 The transmission electron microscope (TEM) image of the PbS quantum dots in Example 1 shows that the prepared PbS quantum dots are spherical with uniform particle distribution and no agglomeration. Statistical analysis of the particle size distribution reveals that the size of the laser-prepared PbS quantum dots is approximately ~2 nm, a significant change compared to the micron-sized bulk PbS precursor. Furthermore, this invention also used X-ray diffraction and X-ray photoelectron spectroscopy to analyze the crystal structure, elemental composition, and chemical state of the PbS quantum dot colloidal solution in Example 1.

[0129] like Figure 4 As shown, comparing the XRD patterns of the PbS precursor and the PbS quantum dots prepared by liquid-phase laser irradiation, the PbS precursor belongs to the isometric crystal system with space group Fm-3m and cell parameters of [missing information]. The unit cell volume is The diffraction peaks located at 26°, 30°, 43°, 51° and 63° correspond to the crystal planes (111), (200), (220), (311) and (400), respectively. When the PbS precursor is treated with liquid phase laser irradiation technology, the X-ray spectrum of the obtained PbS quantum dots shows the disappearance of the sharp diffraction peak in the middle. This is because the quantum dot particle size is small, and the diffraction peaks are broadened, which is in line with the general rule.

[0130] like Figure 5As shown, X-ray photoelectron spectroscopy was used to further analyze the elemental composition and electronic structure before and after irradiation. The full spectra of the PbS precursor and PbS quantum dots showed that both were composed of Pb and S elements. Analysis of the Pb 4f orbitals revealed that Pb mainly exists in the +2 valence state, while S mainly exists in the -2 valence state. Based on the above morphological, crystal structure, and electronic structure analyses, it was confirmed that PbS quantum dots were successfully synthesized using liquid-phase laser irradiation technology, and their structure remained unchanged.

[0131] 1064nm laser has a high melting point, and when the energy is high (greater than 0.8J), the effect of laser energy on PbS dispersion is similar. This makes solvent temperature one of the main factors affecting quantum dot concentration. Therefore, in Examples 2-4 of this invention, the solvent temperature was controlled to investigate the effect. The results showed that the concentration of PbS quantum dot colloidal solution gradually increased as the temperature decreased. When the temperature was 0℃, the concentration of PbS quantum dots prepared by liquid-phase laser irradiation technology was 1.0 mg / mL, and optical photographs showed that the colloidal solution was darker at this concentration. Figure 6 In this study, with a PbS dispersion concentration of 1.0 mg / mL and the temperature adjusted to 0 °C, transmission electron microscopy (TEM) images showed that the quantum dot size was ~1.85 nm.

[0132] When the temperature dropped to -10℃, the concentration of the PbS dispersion further increased to 1.5 mg / mL. Figure 7 The transmission electron microscopy (TEM) images showed that the quantum dot size was ~2.07 nm.

[0133] When the temperature was further reduced to -20℃, the colloidal solution turned dark brown, at which point the concentration of the PbS dispersion further increased to 3.0 mg / mL. Figure 8 The transmission electron microscopy (TEM) images showed that the quantum dot size was ~2.05 nm. These results indicate that by lowering the ambient temperature of the dispersion, the molten compound can be rapidly cooled into quantum dots, reducing agglomeration and increasing the concentration of quantum dots prepared by laser processing.

[0134] Figure 9This indicates that when the concentration of the PbS dispersion was further increased to 3.5 mg / mL, even at a low temperature of -40℃, the PbS quantum dot colloidal solution obtained by irradiation treatment exhibited severe aggregation. This was because the concentration equilibrium limit was exceeded, leading to increased expansion of the quantum dots and subsequent aggregation. The mechanism for preparing high-concentration quantum dot compounds at low temperatures was analyzed. At room temperature, high-concentration quantum dots, after melting, move rapidly in the liquid, attracting each other and agglomerating to produce precipitation. However, as the solvent temperature decreases, the movement rate of the laser-melted particles in the liquid gradually slows down, weakening their adsorption capacity and preventing aggregation. The quantum dots obtained by condensation are stably dispersed in the solvent without aggregation, thus yielding a high-concentration PbS quantum dot colloidal solution.

[0135] Subsequently, the universality of the liquid-phase laser irradiation technology of this invention was explored, using PbSe, GaAs, and CdTe quantum dots as examples for research, such as... Figure 10-12 As shown, by adjusting the laser parameters, colloidal solutions of quantum dots with small sizes and uniform particle size distribution can be obtained. According to the particle size distribution diagram, the sizes of PbSe, GaAs, and CdTe quantum dots are 2.07 nm, 2.33 nm, and 1.78 nm, respectively, and all are uniformly distributed. Furthermore, similar colloidal solutions of SeS2, SnS2, CdMnTe, Sb2S3, TiN, and PbI quantum dots can also be successfully prepared using liquid-phase laser irradiation technology. In summary, temperature-controlled liquid-phase laser irradiation technology can realize the preparation of quantum dots of different compounds, which is of great significance to the development of compound quantum dot technology.

[0136] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims and their equivalents, this invention also intends to include these modifications and variations. The above-described embodiments are merely preferred embodiments for fully illustrating the invention, and their scope of protection is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on this invention are all within the scope of protection of this invention, which is defined by the claims.

Claims

1. A method for preparing colloidal solutions of compound quantum dots using liquid-phase laser irradiation technology, characterized in that, Includes the following steps: A compound precursor with a particle size in the micrometer range is dispersed in a solvent to obtain a compound dispersion. The anions of the compound precursor are: Group V to Group VII elements other than oxygen; Under a protective atmosphere, the compound dispersion was irradiated using liquid phase laser irradiation technology. The irradiation process instantly generated a high-temperature molten compound precursor. At the same time, the solvent environment was controlled at a constant low temperature. The compound in the high-temperature molten state rapidly condensed into nano-sized ultrafine particles in the solvent, resulting in a compound quantum dot colloidal solution. The irradiation treatment environment temperature is -20℃ to 0℃; The solvent is an alcohol-based solvent; The mass ratio of the compound precursor to the volume of the solvent in the compound dispersion is 0.1~3.0 mg / mL.

2. The method for preparing compound quantum dot colloidal solutions using liquid-phase laser irradiation technology according to claim 1, characterized in that, The anion of the compound precursor is one of N, P, As, S, Se, Te, and I.

3. The method for preparing compound quantum dot colloidal solutions using liquid-phase laser irradiation technology according to claim 1, characterized in that, The irradiation conditions were: laser irradiation energy of 0.2-1.0 J for 1-10 min.

4. The method for preparing compound quantum dot colloidal solutions using liquid-phase laser irradiation technology according to claim 1, characterized in that, The laser emission wavelength for the irradiation treatment was 1064 nm, and the laser irradiation range was 1.3 cm.

5. The method for preparing compound quantum dot colloidal solutions using liquid-phase laser irradiation technology according to claim 1, characterized in that, Irradiation treatment was carried out at an ambient temperature of -20℃.

6. The method for preparing compound quantum dot colloidal solutions using liquid-phase laser irradiation technology according to claim 1, characterized in that, The mass ratio of the compound precursor to the volume of the solvent in the compound dispersion was 3.0 mg / mL.

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