Quantum rod with stable chirality and preparation method thereof

Abstract

The invention discloses a quantum rod with stable chirality and a preparation method thereof.The preparation method of the quantum rod with stable chirality comprises the steps that zinc stearate is dissolved in octadecene under the high-temperature condition, a selenium source is added to form a Se-TOP solution, and a ZnSe core solution is successfully prepared; purifying the ZnSe core, and dispersing the ZnSe core in a TOP solution to obtain a ZnSe-TOP core mother solution; then, the ZnSe-TOP core mother liquor is added into a reaction solution composed of a Cd precursor and a sulfur precursor, epitaxial growth is carried out under the high-temperature condition, and ZnSe / CdS quantum rods with different length-diameter ratios are obtained; and carrying out ligand exchange reaction on chiral cysteine and the surface of the quantum rod to obtain the II-type chiral ZnSe / CdS quantum rod. The prepared II-type quantum rod has good optical performance and stable chiral effect, and the chiral optical effect is not affected by the space structure of the core / shell structure of the quantum rod.

Description

Technical Field

[0001] This invention relates to the field of nano-optoelectronic materials technology, and in particular to a chiral stable quantum rod and its preparation method. Background Technology

[0002] In the field of nano-optoelectronic materials, chiral semiconductor nanostructures can produce unique properties such as circular dichroism chiral optical response and polarization-controlled photoluminescence. Among them, quantum rods (QRs) have become the core material system for chiral optoelectronic applications due to their excellent photoelectric conversion capability, carrier separation effect, and tunable structural parameters. In existing technologies, to achieve the chiral optical characteristics of quantum rods, a strategy of chiral ligand-induced chiral transfer is usually adopted. This strategy utilizes the local structural asymmetry generated by the adsorption or binding of chiral molecules on the surface of nanocrystals to make the material exhibit chirality in the optical response. Type I CdSe / CdS core-shell quantum rods are currently widely used structural systems. In this structure, electrons and holes are mainly confined to the same material region, and the wavefunction overlap between the core and the shell is relatively large, which is conducive to effective coupling between the ligand and the nanocrystal core, thus exhibiting obvious chiral optical signals. However, the spatial coupling of the core-shell structure of type I quantum rods also brings significant technical limitations. As the shell thickness increases, the structural coupling at the core-shell interface weakens, and the chiral optical coupling induced by chiral ligands is difficult to effectively transfer to the core, resulting in a significant reduction in the chiral signal at the core and a decrease in the stability of the circular dichroism response. To improve the stability of the chiral optical response, some studies have attempted to improve the chiral transfer capability by increasing the amount of ligands or adjusting the surface chemical conditions, but these usually introduce problems such as decreased structural stability, increased surface defects, and enhanced nonradiative recombination, thus failing to balance photoelectric performance and chiral optical activity. In summary, current technology lacks a material system that can maintain a stable and strong chiral optical response under conditions of quantum rod size variation, aspect ratio adjustment, or band structure modulation. How to improve the degree of freedom of structural modulation while avoiding chiral signal attenuation has become an urgent problem to be solved in this technical direction. Summary of the Invention

[0003] The main objective of this invention is to propose a method for preparing chiral stable quantum rods, aiming to solve the problem that the chiral optical response of existing quantum rods is easily decayed and difficult to maintain stability over a long period of time during the process of controlling the aspect ratio or shell structure.

[0004] To solve the above-mentioned technical problems, one technical solution adopted in this application is: providing a method for preparing a chiral stable quantum rod, comprising: dissolving zinc stearate in octadecene and heating it; injecting a Se-TOP solution formed by dissolving selenium in trioctylphosphine under high temperature conditions to react and obtain a ZnSe core solution; purifying the ZnSe core solution and dispersing it in trioctylphosphine to obtain a ZnSe-TOP core mother liquor; adding the ZnSe-TOP core mother liquor to a heated reaction solution composed of a Cd precursor and a sulfur precursor, so that the ZnSe-TOP core solution is formed. ZnSe cores in the P-core mother liquor are epitaxially grown under high temperature to form ZnSe / CdS quantum rods. By changing the amount of the injected ZnSe-TOP core mother liquor, ZnSe / CdS quantum rods with different aspect ratios are obtained. The ZnSe / CdS quantum rods with different aspect ratios are added to a chiral cysteine ​​solution and stirred to allow ligand exchange between the chiral cysteine ​​and the surface of the ZnSe / CdS quantum rods. The quantum rods after ligand exchange are then subjected to precipitation, separation, and redispersion treatment to obtain type II chiral ZnSe / CdS quantum rods.

[0005] Further, the step of dissolving zinc stearate in octadecene and heating it, then injecting a Se-TOP solution formed by dissolving selenium in trioctylphosphine under high temperature conditions to prepare a ZnSe core solution includes: dissolving zinc stearate in octadecene in a container and heating it to 150°C, then alternatingly exposing it to vacuum and nitrogen at least 5 times, and continuing to maintain an inert atmosphere at 150°C for 1 hour after the alternating exposure; raising the temperature to 300°C until the mixed solution of zinc stearate and octadecene is colorless; raising the temperature to 320°C and rapidly injecting the Se-TOP solution into the container, then lowering the temperature to 290°C after the injection and continuing to maintain the reaction for a preset first time; when the preset first time of the reaction ends, rapidly removing the heat source and cooling the reaction system to room temperature to obtain the ZnSe core solution.

[0006] Further, the step of purifying the ZnSe core solution and dispersing it in trioctylphosphine to obtain the ZnSe-TOP core mother liquor includes: adding n-hexane and ethanol to the ZnSe core solution, wherein the volume ratio of n-hexane to ethanol is 1:1 to 1:6; performing purification treatment on the first mixture after adding n-hexane and ethanol 2 to 5 times; and dispersing the purified solid product in the TOP solution to obtain the ZnSe-TOP core mother liquor.

[0007] Further, the step of adding the ZnSe-TOP core mother liquor to a heated reaction solution composed of Cd precursor and sulfur precursor, so that the ZnSe core in the ZnSe-TOP core mother liquor can be epitaxially grown at high temperature to form ZnSe / CdS quantum rods, includes: heating a second mixture of TOPO, ODPA, HPA and CdO to 150°C, alternatingly exposing it to vacuum and argon atmospheres at least 5 times, and continuing to maintain an inert atmosphere at 150°C for 1 hour after the alternating exposure, until CdO appears as a brown solid, TOPO, ODPA and HPA are colorless liquids; the second mixture is heated to above 300°C under a nitrogen atmosphere until CdO is completely dissolved and the reaction solution is transparent and colorless; when the reaction solution temperature reaches 320°C, TOP solution is injected into the reaction solution; when the reaction solution is at 320°C, a preset volume of the ZnSe-TOP core mother liquor and S-TOP precursor are injected into the reaction solution; the reaction system is maintained for a preset second time to allow the ZnSe core to react with the reaction solution, and ZnSe / CdS quantum rods are epitaxially grown.

[0008] Furthermore, the step of obtaining ZnSe / CdS quantum rods with different aspect ratios by changing the amount of injected ZnSe-TOP core mother liquor includes: selecting different amounts of ZnSe-TOP core mother liquor and injecting them into heated reaction solutions composed of Cd precursor and sulfur precursor respectively; maintaining heating conditions during their respective independent epitaxial growth reactions, so that the ZnSe cores in the ZnSe-TOP core mother liquors with different amounts react with the reaction solutions respectively; and obtaining ZnSe / CdS quantum rods with different aspect ratios through epitaxial growth under different addition conditions.

[0009] Further, the step of adding ZnSe / CdS quantum rods with different aspect ratios to a chiral cysteine ​​solution and stirring to allow ligand exchange between the chiral cysteine ​​and the surface of the ZnSe / CdS quantum rods includes: dissolving cysteine ​​hydrochloride in deionized water to obtain an aqueous cysteine ​​solution; adding an alkaline adjuster to adjust the pH of the aqueous cysteine ​​solution to obtain an alkaline cysteine ​​solution; adding the ZnSe / CdS quantum rods dispersed in a hydrophobic solvent to the alkaline cysteine ​​solution to obtain a reaction mixture; and stirring the reaction mixture at room temperature in the absence of light for a predetermined third time to allow ligand exchange between the cysteine ​​and the surface of the ZnSe / CdS quantum rods.

[0010] Further, the step of precipitating, separating, and redispersing the ligand-exchanged quantum rods to obtain type II chiral ZnSe / CdS quantum rods includes: allowing the reaction mixture after ligand exchange to stand to allow phase separation; separating the aqueous phase from the reaction mixture to obtain an aqueous phase containing the ZnSe / CdS quantum rods; adding a precipitation purification solvent to the aqueous phase containing the ZnSe / CdS quantum rods for precipitation purification; and dispersing the purified ZnSe / CdS quantum rods in distilled water to obtain the type II chiral ZnSe / CdS quantum rods.

[0011] Furthermore, the aspect ratio of the obtained type II chiral ZnSe / CdS quantum rod ranges from 2 to 10.

[0012] To solve the above-mentioned technical problems, another technical solution adopted in the embodiments of this application is: to provide a chiral stable quantum rod, wherein the chiral stable quantum rod is prepared by the method for preparing a chiral stable quantum rod as described above.

[0013] Furthermore, the aspect ratio of the chiral stable quantum rod ranges from 2 to 10.

[0014] The technical solution of this invention has the following advantages: 1. The Type II quantum rod proposed in this invention utilizes the electron and hole separation characteristics to achieve effective chiral ligand-induced and enhanced optical activity; 2. The chiral type II quantum rod obtained by this invention can still maintain chiral transfer capability when the aspect ratio increases, thus avoiding the problem that the chiral effect is significantly weakened when the aspect ratio increases in existing quantum rod structures; 3. This invention can precisely control the aspect ratio of ZnSe / CdS quantum rods by adjusting the ZnSe core concentration, and achieve a stable chiral optical response of type II quantum rods in the aspect ratio range of 2 to 10, thereby improving the structural tunability and application potential of this type of material. Attached Figure Description

[0015] Figure 1 This is a flowchart of a method for preparing a chiral stable quantum rod according to an embodiment of the present invention; Figure 2 These are transmission electron microscope images of ZnSe cores obtained in embodiments of the present invention; Figure 3 This is a transmission electron microscope image of a ZnSe / CdS quantum rod with an aspect ratio of 2.3 obtained in an embodiment of the present invention; Figure 4 This is a transmission electron microscope image of a ZnSe / CdS quantum rod with an aspect ratio of 4.6 obtained in an embodiment of the present invention; Figure 5 This is a transmission electron microscope image of a ZnSe / CdS quantum rod with an aspect ratio of 5.4 obtained in an embodiment of the present invention; Figure 6 This is a comparison of the photoluminescence spectra of the ZnSe core obtained in the embodiments of the present invention and ZnSe / CdS quantum rods with different aspect ratios; Figure 7 The UV absorption spectrum of a type II chiral quantum rod with an aspect ratio of 2.3 obtained in this embodiment of the invention after exchanging with a cysteine ​​ligand is shown. Figure 8 The circular dichroism spectrum of a type II chiral quantum rod with an aspect ratio of 2.3 obtained in an embodiment of the present invention after exchanging cysteine ​​ligands is shown. Figure 9 This is the g-factor spectrum of a type II chiral quantum rod with an aspect ratio of 2.3 obtained in an embodiment of the present invention after exchanging cysteine ​​ligands; Figure 10 The UV absorption spectrum of a type II chiral quantum rod with an aspect ratio of 4.6 obtained in an embodiment of the present invention after exchanging with a cysteine ​​ligand is shown. Figure 11 The circular dichroism spectrum of a type II chiral quantum rod with an aspect ratio of 4.6 obtained in an embodiment of the present invention after exchanging cysteine ​​ligands is shown. Figure 12 This is the g-factor spectrum of a type II chiral quantum rod with an aspect ratio of 4.6 obtained in an embodiment of the present invention after exchanging cysteine ​​ligands; Figure 13 The UV absorption spectrum of a type II chiral quantum rod with an aspect ratio of 5.4 obtained in an embodiment of the present invention after exchanging with a cysteine ​​ligand is shown. Figure 14 The circular dichroism spectrum of a type II chiral quantum rod with an aspect ratio of 5.4 obtained in an embodiment of the present invention after exchanging cysteine ​​ligands is shown. Figure 15 This is the g-factor spectrum of a type II chiral quantum rod with an aspect ratio of 5.4 obtained in an embodiment of the present invention after exchanging cysteine ​​ligands. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0018] Unless otherwise specified, the experimental methods described in the following examples are conventional methods.

[0019] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0020] This invention provides a method for preparing a chiral stable quantum rod. Please refer to [link to relevant documentation]. Figure 1 As shown, the preparation method includes the following steps S10 to S50.

[0021] S10. Dissolve zinc stearate in octadecene and heat. Then, inject the Se-TOP solution formed by dissolving selenium in trioctylphosphine under high temperature conditions to react and obtain a ZnSe core solution. After purifying the ZnSe core solution, disperse it in trioctylphosphine to obtain the ZnSe-TOP core mother liquor.

[0022] As an optional implementation, the process of preparing the ZnSe core solution in step S10 above may further include steps S101 to S104.

[0023] S101. Dissolve zinc stearate in octadecene through a container and heat to 150°C. Expose the solution alternately to vacuum and nitrogen at least 5 times. After the alternating exposure is completed, continue to maintain an inert atmosphere at 150°C for 1 hour.

[0024] S102. Increase the temperature to 300℃ until the mixed solution of zinc stearate and octadecene is colorless.

[0025] S103. When the temperature is raised to 320°C, Se-TOP solution is quickly injected into the container. After the injection is completed, the temperature is lowered to 290°C and the reaction is maintained for the preset first time.

[0026] S104. When the reaction is held at the preset first time, quickly remove the heat source and cool the reaction system to room temperature to obtain the ZnSe core solution.

[0027] As an example, please refer to Figure 2 , Figure 2 These are transmission electron microscope images of ZnSe cores obtained in embodiments of the present invention, such as... Figure 2As shown, the obtained ZnSe cores have a uniform particle size distribution and a good crystal structure, indicating that the nucleation process described in step S104 has successfully achieved stable ZnSe core growth. The observation results of the microstructure images prove that the size and morphology of the ZnSe cores meet the design requirements, providing a reliable foundation for the successful epitaxial growth of quantum rods.

[0028] Through steps S101 to S104, zinc stearate is fully dissolved in octadecene and reacts under anhydrous and oxygen-free conditions, effectively removing impurities from the system and ensuring a pure and stable nucleation environment for subsequent selenium source injection. Heating treatment forms a homogeneous and transparent solution, providing a reliable basis for uniform nucleation of ZnSe cores. Rapid injection of the selenium source at high temperature followed by temperature reduction achieves instantaneous nucleation while suppressing excessively rapid growth, effectively controlling the size uniformity and morphology of the ZnSe cores. Rapid cooling after reaching the preset reaction time terminates crystal growth, avoiding overgrowth and secondary nucleation, resulting in a concentrated and structurally stable ZnSe core solution.

[0029] As another optional implementation, the process of obtaining the ZnSe-TOP core mother liquor in step S10 above may also specifically include the following steps S105 to S107.

[0030] S105. Add n-hexane and ethanol to the ZnSe core solution, with a volume ratio of n-hexane to ethanol of 1:1 to 1:6.

[0031] S106. The first mixture after adding hexane and ethanol is purified 2 to 5 times.

[0032] S107. The purified solid product is dispersed in TOP solution to obtain ZnSe-TOP core mother liquor.

[0033] Through steps S105 to S107, adding hexane and ethanol to the ZnSe core solution promotes phase separation, achieving initial precipitation and separation of the ZnSe cores. Subsequent purification processes effectively remove unreacted substances and residual impurities, improving core purity. The purified solid phase is then redispersed in a TOP solution, forming a stable and homogeneous colloidal system of ZnSe cores, thus obtaining a ZnSe-TOP core mother liquor. This provides a well-dispersed and compositionally consistent core precursor for subsequent quantum rod epitaxial growth.

[0034] S20. Add the ZnSe-TOP core mother liquor to a heated reaction solution composed of Cd precursor and sulfur precursor, so that the ZnSe core in the ZnSe-TOP core mother liquor can be epitaxially grown under high temperature conditions to form ZnSe / CdS quantum rods.

[0035] As an optional implementation, the process of forming ZnSe / CdS quantum rods in step S20 above may also specifically include the following steps S201 to S20.

[0036] S201. Heat the second mixture of TOPO, ODPA, HPA and CdO to 150°C and expose it alternately in a vacuum and argon atmosphere at least 5 times. After the alternating exposure, continue to maintain an inert atmosphere at 150°C for 1 hour until CdO turns into a brown solid and TOPO, ODPA and HPA turn into a colorless liquid.

[0037] S202. The second mixture is heated to above 300°C under a nitrogen atmosphere until CdO is completely dissolved and the reaction solution is transparent and colorless.

[0038] S203. When the temperature of the reaction solution reaches 320℃, inject TOP solution into the reaction solution.

[0039] S204. When the reaction solution is at 320°C, inject a predetermined volume of ZnSe-TOP core mother liquor and S-TOP precursor into the reaction solution.

[0040] S205. Maintain the reaction system at the preset second time to allow the ZnSe core to react with the reaction solution, and form ZnSe / CdS quantum rods through epitaxial growth.

[0041] Through steps S201 to S205, TOPO, ODPA, HPA, and CdO are mixed and heated under anhydrous and oxygen-free conditions. This effectively removes gaseous impurities from the system, allowing CdO to be fully dispersed and form a homogeneous mixture with the ligands. Continued heating promotes complete dissolution of CdO, resulting in a transparent and stable reaction liquid, providing a uniform chemical environment for subsequent epitaxial growth. TOP solution is then injected at high temperature to create a suitable ligand environment for epitaxial growth. Subsequently, a predetermined volume of ZnSe-TOP core mother liquor and sulfur source precursor are injected, allowing the ZnSe core to undergo an epitaxial growth reaction with the reaction system. Maintaining the reaction conditions for a predetermined time ensures stable axial growth of the quantum rods, resulting in structurally complete and morphologically controllable ZnSe / CdS quantum rods.

[0042] S30. By changing the amount of injected ZnSe-TOP core mother liquor added, ZnSe / CdS quantum rods with different aspect ratios can be obtained.

[0043] As an optional implementation, the process of obtaining ZnSe / CdS quantum rods with different aspect ratios in step S30 above may also specifically include the following steps S301 to S303.

[0044] S301. Different amounts of ZnSe-TOP core mother liquor were injected into the heated reaction solution composed of Cd precursor and sulfur precursor.

[0045] S302. During the independent epitaxial growth reaction, the heating conditions are maintained so that the ZnSe cores in the ZnSe-TOP core mother liquor with different amounts of added ZnSe-TOP cores react with the reaction solution respectively.

[0046] S303, ZnSe / CdS quantum rods with different aspect ratios were obtained by epitaxial growth under different addition conditions.

[0047] As an example, please refer to Figure 3 , Figure 4 and Figure 5 , Figure 3 This is a transmission electron microscope image of a ZnSe / CdS quantum rod with an aspect ratio of 2.3 obtained in an embodiment of the present invention. Figure 4 This is a transmission electron microscope image of a ZnSe / CdS quantum rod with an aspect ratio of 4.6 obtained in an embodiment of the present invention. Figure 5 The image shown is a transmission electron microscope image of a ZnSe / CdS quantum rod with an aspect ratio of 5.4 obtained in an embodiment of the present invention. Figure 3 , Figure 4 and Figure 5 The microstructure images of the ZnSe / CdS quantum rods all show uniform particle size distribution and good crystallinity. All quantum rods exhibit a distinct rod-like morphology and high structural stability, demonstrating that the reaction conditions used can successfully prepare high-quality quantum rods with consistent morphology and size, meeting the core growth and epitaxial growth conditions required by this invention. Although the quantum rods shown in the three images have similar morphologies, they differ significantly in aspect ratio (AR). Figure 3 The quantum rod on display has an aspect ratio of 2.3 and a relatively moderate shape; Figure 4 It exhibits a more slender shape with a length-to-diameter ratio of 4.6; while Figure 5 The quantum rod with an aspect ratio of 5.4 exhibits the most slender shape. These differences indicate that by adjusting the reaction conditions and the amount of core mother liquor added, the aspect ratio of the quantum rod can be precisely controlled, thereby achieving customization of the quantum rod shape.

[0048] Through steps S301 to S303, different amounts of ZnSe-TOP core mother liquor were added to the heated reaction solution, allowing ZnSe cores under different addition conditions to undergo epitaxial growth with the reaction solution. Heating conditions were maintained in independent growth reaction systems to ensure stable axial growth of the quantum rods. After completing epitaxial growth under different addition conditions, ZnSe / CdS quantum rods with different aspect ratios were obtained, thus achieving controllable adjustment of the quantum rod's aspect ratio.

[0049] S40. Add ZnSe / CdS quantum rods with different aspect ratios to a chiral cysteine ​​solution and stir to allow ligand exchange between the chiral cysteine ​​and the surface of the ZnSe / CdS quantum rods.

[0050] As an optional implementation, the process of ligand exchange between chiral cysteine ​​and the surface of the ZnSe / CdS quantum rod in step S40 may further include steps S401 to S403.

[0051] S401. Dissolve cysteine ​​hydrochloride in deionized water to obtain an aqueous cysteine ​​solution. Add an alkaline adjuster to adjust the pH of the aqueous cysteine ​​solution to obtain an alkaline cysteine ​​solution.

[0052] S402. Add ZnSe / CdS quantum rods dispersed in a hydrophobic solvent to an alkaline cysteine ​​solution to obtain a reaction mixture.

[0053] S403. Stir the reaction mixture at room temperature in the absence of light for a preset third time to allow cysteine ​​to undergo ligand exchange with the ZnSe / CdS quantum rod surface.

[0054] Through steps S401 to S403, cysteine ​​hydrochloride is dissolved in water and the pH is adjusted to obtain an alkaline cysteine ​​solution, thus providing a suitable chemical environment for subsequent ligand exchange. Subsequently, ZnSe / CdS quantum rods dispersed in a hydrophobic solvent are added to the alkaline cysteine ​​solution, allowing the quantum rod surface to fully contact with the cysteine ​​to form a reaction mixture. Stirring this mixture at room temperature in the absence of light promotes the gradual replacement of the original surface ligands by the cysteine, enabling ligand exchange with the ZnSe / CdS quantum rod surface, thereby achieving stable binding of chiral cysteine ​​on the quantum rod surface.

[0055] S50. The quantum rods after ligand exchange are subjected to precipitation, separation, and redispersion to obtain type II chiral ZnSe / CdS quantum rods.

[0056] As an optional implementation, the process of obtaining the type II chiral ZnSe / CdS quantum rod in step S50 above may also specifically include the following steps S501 to S504.

[0057] S501. Allow the reaction mixture after ligand exchange to stand so that phase separation occurs in the reaction mixture.

[0058] S502. Separate the aqueous phase from the reaction mixture to obtain an aqueous phase containing ZnSe / CdS quantum rods.

[0059] S503. Add precipitation purification solvent to the aqueous phase containing ZnSe / CdS quantum rods to perform precipitation purification treatment.

[0060] S504. Disperse the purified ZnSe / CdS quantum rods in distilled water to obtain type II chiral ZnSe / CdS quantum rods.

[0061] The aspect ratio of the type II chiral ZnSe / CdS quantum rod obtained in step S504 ranges from 2 to 10.

[0062] As an example, please continue reading Figure 6 , Figure 6 This is a comparison of the photoluminescence spectra of the ZnSe core and ZnSe / CdS quantum rods with different aspect ratios obtained in the embodiments of the present invention, as shown in the figure. Figure 6 As shown, the graph illustrates the relationship between photoluminescence (PL) intensity and wavelength for the ZnSe core (black curve) and three quantum rods with different aspect ratios (DR-1: 2.3, DR-2: 4.6, DR-3: 5.4). The vertical axis represents PL intensity (au), where PL indicates photoluminescence, the intensity of light emitted when a material is photoexcited, and au represents arbitrary units, typically used to express relative intensity. The vertical axis represents wavelength (nm), with units ranging from 400 nm to 700 nm. ZnSe core represents the ZnSe core. The PL spectrum shows the emission peak from 442 nm in the ZnSe core to the corresponding emission peaks (shifted to 591 nm) in the different quantum rods (DR-1, DR-2, DR-3). This graph demonstrates the successful synthesis of type II quantum rod ZnSe / CdS. As the aspect ratio (AR) increases, the PL emission peak of the quantum rod shifts towards red, demonstrating the effect of different aspect ratios on the luminescence properties of the quantum rod.

[0063] Through steps S501 to S504, allowing the reaction mixture after ligand exchange to stand promotes natural phase separation, thus achieving initial stratification of the quantum rods and the liquid phase. Subsequently, separating the aqueous phase from the resulting mixture yields a liquid phase containing ZnSe / CdS quantum rods. Adding a precipitation purification solvent to the aqueous phase removes residual impurities and unreacted substances, achieving precipitation purification of the quantum rods. After purification, the obtained ZnSe / CdS quantum rods are redispersed in distilled water to obtain type II chiral ZnSe / CdS quantum rods, ensuring good dispersibility and stability.

[0064] As an example, please continue reading Figure 7 , Figure 8 and Figure 9 , Figure 7 This is the UV absorption spectrum of a type II chiral quantum rod with an aspect ratio of 2.3 obtained in an embodiment of the present invention after cysteine ​​ligand exchange. Figure 8 The image shows the circular dichroism spectrum of a type II chiral quantum rod with an aspect ratio of 2.3 obtained in this embodiment of the invention after exchanging cysteine ​​ligands. Figure 9 This is the g-factor spectrum of a type II chiral quantum rod with an aspect ratio of 2.3 obtained in an embodiment of the present invention after exchanging cysteine ​​ligands.

[0065] like Figure 7 As shown, the horizontal axis represents the wavelength of light (nm), measured in nanometers (nm), ranging from 300 nm to 700 nm. Wavelength determines the color of light; shorter wavelengths (e.g., around 300 nm) correspond to ultraviolet light, while longer wavelengths (e.g., around 650 nm) correspond to visible or red light. The vertical axis represents the absorption intensity (au) of the quantum rod for different wavelengths of light, measured in absorbance (au), which is an arbitrary unit. A higher absorbance value indicates stronger absorption of that wavelength by the quantum rod. In the legend, the black curve (Abs-DR-1-L) represents the ultraviolet absorption spectrum of the DR-1 quantum rod (aspect ratio of 2.3) under L-cysteine ​​ligand exchange conditions, and the red curve (Abs-DR-1-D) represents the ultraviolet absorption spectrum under D-cysteine ​​ligand exchange conditions. As can be seen from the figure, the absorption intensity of type II quantum rods with different aspect ratios does not change significantly after cysteine ​​ligand exchange.

[0066] like Figure 8As shown, the horizontal axis represents the wavelength of light (nm), measured in nanometers (nm), ranging from 300 nm to 700 nm. The vertical axis represents the circular dichroism signal intensity (CD (mdeg)) of the quantum rod, measured in millidions (mdeg). The intensity of the CD signal reflects the chiral optical response of the quantum rod at different wavelengths; a larger signal value indicates a stronger chiral effect. In the legend, the black curve (CD-DR-1-L) represents the CD spectrum of the DR-1 quantum rod (aspect ratio of 2.3) under L-cysteine ​​ligand exchange conditions, and the red curve (CD-DR-1-D) represents the CD spectrum under D-cysteine ​​ligand exchange conditions. The figure shows that the CD signal is completely symmetrical after the exchange of L- and D-type ligands, indicating that the chiral ligands successfully transferred their chirality to the quantum rod and induced a strong chiral optical response.

[0067] like Figure 9 As shown, the horizontal axis represents the wavelength of light (nm), measured in nanometers (nm), ranging from 300 nm to 700 nm. The vertical axis represents the g-factor, which measures the strength of the chiral optical response and can be calculated using the formula: In the figure, CD represents the circular dichroism signal intensity, and Abs. represents absorbance. The black curve (g-factor-DR-1-L) in the legend represents the g-factor value of the DR-1 quantum rod (aspect ratio of 2.3) under L-cysteine ​​ligand exchange conditions, and the red curve (g-factor-DR-1-D) represents the g-factor value under D-cysteine ​​ligand exchange conditions. By comparing the two curves in the figure, it can be seen that the chiral quantum rods after L-type and D-type ligand exchange both exhibit strong optical activity.

[0068] As another example, please continue reading Figure 10 , Figure 11 and Figure 12 , Figure 10 This is the UV absorption spectrum of a type II chiral quantum rod with an aspect ratio of 4.6 obtained in an embodiment of the present invention after cysteine ​​ligand exchange. Figure 11 The image shows the circular dichroism pattern of a type II chiral quantum rod with an aspect ratio of 4.6 obtained in this embodiment of the invention after exchanging cysteine ​​ligands. Figure 12 This is the g-factor spectrum of a type II chiral quantum rod with an aspect ratio of 4.6 obtained in an embodiment of the present invention after exchanging cysteine ​​ligands.

[0069] like Figure 10As shown in the figure, the black curve (Abs-DR-2-L) represents the UV absorption spectrum of the DR-2 quantum rod (aspect ratio of 4.6) under L-type cysteine ​​ligand exchange conditions, and the red curve (Abs-DR-2-D) represents the UV absorption spectrum under D-type cysteine ​​ligand exchange conditions. It can be seen from the figure that the absorption intensity of the type II quantum rods with different aspect ratios does not change significantly after cysteine ​​ligand exchange.

[0070] like Figure 11 As shown in the figure, the black curve (CD-DR-2-L) represents the CD spectrum of the DR-2 quantum rod (aspect ratio of 4.6) under L-cysteine ​​ligand exchange conditions, and the red curve (CD-DR-2-D) represents the CD spectrum under D-cysteine ​​ligand exchange conditions. The figure shows that the exchange of L- and D-type ligands results in a completely symmetrical CD signal, indicating that the chiral ligands successfully transferred their chirality to the quantum rod and induced a strong chiral optical response.

[0071] like Figure 12 As shown in the figure, the black curve (g-factor-DR-2-L) represents the g-factor value of the DR-2 quantum rod (aspect ratio of 4.6) under L-cysteine ​​ligand exchange conditions, and the red curve (g-factor-DR-2-D) represents the g-factor spectrum under D-cysteine ​​ligand exchange conditions. By comparing the two curves in the figure, it can be seen that the chiral quantum rods exhibit strong optical activity after both L-type and D-type ligand exchange.

[0072] As yet another example, please continue reading Figure 13 , Figure 14 and Figure 15 , Figure 13 This is the UV absorption spectrum of a type II chiral quantum rod with an aspect ratio of 5.4 obtained in an embodiment of the present invention after exchanging cysteine ​​ligands. Figure 14 The image shows the circular dichroism spectrum of a type II chiral quantum rod with an aspect ratio of 5.4 obtained in this embodiment of the invention after exchanging cysteine ​​ligands. Figure 15 This is the g-factor spectrum of a type II chiral quantum rod with an aspect ratio of 5.4 obtained in an embodiment of the present invention after exchanging cysteine ​​ligands.

[0073] like Figure 13 As shown in the figure, the black curve (Abs-DR-3-L) represents the UV absorption spectrum of the DR-3 quantum rod (aspect ratio of 5.4) under L-type cysteine ​​ligand exchange conditions, and the red curve (Abs-DR-3-D) represents the UV absorption spectrum under D-type cysteine ​​ligand exchange conditions. It can be seen from the figure that the absorption intensity of the type II quantum rods with different aspect ratios does not change significantly after cysteine ​​ligand exchange.

[0074] like Figure 14 As shown in the figure, the black curve (CD-DR-3-L) represents the CD spectrum of the DR-3 quantum rod (aspect ratio of 5.4) under L-cysteine ​​ligand exchange conditions, and the red curve (CD-DR-3-D) represents the CD spectrum under D-cysteine ​​ligand exchange conditions. The figure shows that the exchange of L- and D-type ligands results in a completely symmetrical CD signal, indicating that the chiral ligands successfully transferred their chirality to the quantum rod and induced a strong chiral optical response.

[0075] like Figure 15 As shown in the figure, the black curve (g-factor-DR-3-L) represents the g-factor spectrum of the DR-3 quantum rod (aspect ratio of 5.4) under L-cysteine ​​ligand exchange conditions, and the red curve (g-factor-DR-3-D) represents the g-factor spectrum under D-cysteine ​​ligand exchange conditions. By comparing the two curves in the figure, it can be seen that the chiral quantum rods exhibit strong optical activity after both L-type and D-type ligand exchange.

[0076] contrast Figure 8 , 1114. The CD spectra of chiral quantum rods with different aspect ratios showed no significant change in CD signal intensity, indicating that the chiral optical response remained relatively stable. As a specific example, firstly, ZnSe seeds were prepared: In a 50 mL three-necked flask, 0.6 mmol of zinc stearate (0.3794 g) was dissolved in 9.5 mL of octadecene, heated to 150 °C, and alternately exposed to vacuum and nitrogen atmospheres more than 5 times for 1 hour. Then, the temperature was increased to 300 °C until the liquid in the flask became colorless. Heating was continued to 320 °C, and 1.5 mL of Se-TOP solution (0.4 M) was rapidly injected, maintaining the reaction at 290 °C for 13 minutes. Finally, the heat source was quickly removed, allowing the reaction system to cool to room temperature. Next, the core was purified 2 to 5 times by mixing hexane and ethanol (volume ratio 1:1 to 1:6) to obtain purified ZnSe cores, which were then dispersed in TOP solution to obtain ZnSe-TOP core mother liquor. Then, ZnSe / CdS dot-rod nanocrystals were synthesized: 3g TOPO, 300mg ODPA, 81mg HPA, and 5.8mg CdO were mixed in a 50mL flask, heated to 150℃, and alternately exposed to vacuum and argon atmospheres more than 5 times, continuing for 1 hour until CdO turned into a brown solid. The solution was then heated to above 300℃ under a nitrogen atmosphere until CdO completely dissolved, forming a transparent, colorless solution. 1.5mL of TOP solution was added, and the temperature was maintained at 320℃. 1.5mL, 0.5mL, and 0.25mL of ZnSe-TOP mother liquor and 1.5mL of 2.5MS-TOP precursor (a 2.5mol / L sulfur solution prepared by dissolving 0.24g sulfur in 3mL of TOP under nitrogen atmosphere) were injected. After reacting for 8 minutes, ZnSe / CdS quantum rods with different aspect ratios (AR=2.3, AR=4.6, AR=5.4) were obtained. The reaction mixture was cooled to room temperature to terminate the reaction. The final product was diluted with hexane, and after centrifugation with methanol, the separated upper layer was retained in the hexane layer. Finally, the ZnSe / CdS nanorods were ligand exchanged with chiral cysteine ​​molecules. 1.4 g of D- or L-cysteine ​​hydrochloride monohydrate (other chiral ligands such as tartaric acid, malic acid, penicillamine, and acetylcysteine ​​can be used) was dissolved in deionized water, and the pH of the solution was adjusted to 12 using tetramethylammonium hydroxide (TMAH) to obtain a 0.2 M cysteine ​​solution. Subsequently, the ZnSe / CdS nanorod solution in hexane was added to the cysteine ​​solution, and the reaction was carried out with light-free stirring for 24 to 72 hours. Then, the reaction mixture was allowed to stand for 1 to 12 hours to allow phase separation. The bottom water layer was removed using a syringe and precipitated with ethanol / chloroform / deionized water (volume ratio 1:10:1, purified twice) to obtain purified Cys-ZnSe / CdS DRs.Finally, the purified Cys-DRs were dissolved in distilled water to obtain type II chiral ZnSe / CdS quantum rods, which were stored at room temperature in the dark.

[0077] The method for preparing chiral stable quantum rods provided in this application achieves adjustable aspect ratio of ZnSe / CdS quantum rods by precisely controlling the nucleation and epitaxial growth of ZnSe cores. Using chiral cysteine ​​for ligand exchange, chiral transfer on the quantum rod surface is successfully realized, improving its water solubility and stability. Through precipitation, separation, and redispersion, the obtained type II chiral ZnSe / CdS quantum rods exhibit excellent dispersibility, stability, and size uniformity, making them suitable for high-precision optical testing. This method not only optimizes the optical properties of the quantum rods but also effectively maintains the chiral transfer effect, demonstrating broad application potential.

[0078] This application also provides a chiral stable quantum rod, which is prepared by the above-described method for preparing a chiral stable quantum rod.

[0079] As an alternative implementation, the aspect ratio of the chiral stable quantum rod described above ranges from 2 to 10.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them; under the concept of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order and there are many other variations of different aspects of this application as described above. For the sake of brevity, they are not provided in detail. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing chiral-stable quantum rods, characterized by, The application relates to a preparation method of a chiral ZnSe / CdS quantum rod. The ZnSe core solution is prepared by dissolving zinc stearate in octadecene and heating, injecting a Se-TOP solution formed by dissolving selenium in trioctylphosphine to react under high-temperature conditions, dispersing the ZnSe core solution in trioctylphosphine after purification, and obtaining a ZnSe-TOP core mother liquor. The ZnSe-TOP core mother liquor is added into a heated reaction solution composed of a Cd precursor and a sulfur precursor, so that ZnSe cores in the ZnSe-TOP core mother liquor are epitaxially grown under high-temperature conditions to form ZnSe / CdS quantum rods. The ZnSe / CdS quantum rods with different length-diameter ratios are obtained by changing the adding amount of the ZnSe-TOP core mother liquor. The ZnSe / CdS quantum rods with different length-diameter ratios are added into a chiral cysteine solution for stirring reaction, so that the chiral cysteine and the ZnSe / CdS quantum rod surface are subjected to ligand exchange. The quantum rod after ligand exchange is subjected to precipitation, separation and redispersion treatment, and a type II chiral ZnSe / CdS quantum rod is obtained.

2. The method for preparing chiral stabilized quantum rods according to claim 1, characterized in that, The step of preparing the ZnSe core solution by dissolving zinc stearate in octadecene and heating, injecting a Se-TOP solution formed by dissolving selenium in trioctylphosphine to react under high-temperature conditions comprises the following steps: The zinc stearate is dissolved in octadecene in a container and heated to 150 DEG C, and is alternately exposed to vacuum and nitrogen for at least 5 times; after the alternating exposure, the inert atmosphere is maintained at 150 DEG C for 1 hour; The temperature is increased to 300 DEG C until the mixed solution of the zinc stearate and the octadecene is colorless; When the temperature is increased to 320 DEG C, the Se-TOP solution is rapidly injected into the container, and after the injection is completed, the temperature is decreased to 290 DEG C and the reaction is continued for a preset first time; When the preset first time of maintaining the reaction is completed, the heat source is rapidly removed, and the reaction system is cooled to room temperature, and the ZnSe core solution is obtained.

3. The method of claim 1, wherein the quantum rods are chiral stabilized. The step of dispersing the ZnSe core solution in trioctylphosphine after purification to obtain a ZnSe-TOP core mother liquor comprises the following steps: The ZnSe core solution is added with n-hexane and ethanol, and the volume ratio of the n-hexane and the ethanol is 1:1 to 1:6; The first mixture after adding the n-hexane and the ethanol is subjected to 2 to 5 times of purification treatment; The solid-phase product after the purification treatment is dispersed in a TOP solution, and the ZnSe-TOP core mother liquor is obtained.

4. The method of claim 1, wherein the quantum rods are chiral stabilized. The step of adding the ZnSe-TOP core mother liquor into a heated reaction solution composed of a Cd precursor and a sulfur precursor, so that ZnSe cores in the ZnSe-TOP core mother liquor are epitaxially grown under high-temperature conditions to form ZnSe / CdS quantum rods comprises the following steps: The second mixture of TOPO, ODPA, HPA and CdO is heated to 150 DEG C, and is alternately exposed to vacuum and an argon environment for at least 5 times; after the alternating exposure, the inert atmosphere is maintained at 150 DEG C for 1 hour until the CdO is brown solid and the TOPO, ODPA and HPA are colorless liquid; heating the second mixture to above 300℃ under nitrogen atmosphere until CdO is completely dissolved and the reaction solution is transparent and colorless; when the temperature of the reaction solution reaches 320℃, injecting a TOP solution into the reaction solution; when the reaction solution is at 320℃, injecting a pre-set volume of the ZnSe-TOP core mother liquor and S-TOP precursor into the reaction solution; keeping the reaction system for a pre-set second time to allow the CdSe core to react with the reaction solution to form a ZnSe / CdS quantum rod through epitaxial growth.

5. The method of claim 1, wherein the quantum rods are chiral stabilized. The step of obtaining ZnSe / CdS quantum rods with different aspect ratios by changing the amount of the ZnSe-TOP core mother liquor injected, comprises: injecting different amounts of the ZnSe-TOP core mother liquor into a heated reaction solution composed of Cd precursor and sulfur precursor; keeping the heating conditions during the respective epitaxial growth reactions to allow the ZnSe cores in the ZnSe-TOP core mother liquor with different amounts to react with the reaction solution, respectively; obtaining ZnSe / CdS quantum rods with different aspect ratios under different amounts of the ZnSe-TOP core mother liquor.

6. The method of claim 1, wherein the quantum rods are chiral stabilized. The step of adding the ZnSe / CdS quantum rods with different aspect ratios into a chiral cysteine solution for stirring reaction to allow the chiral cysteine to exchange ligands with the surface of the ZnSe / CdS quantum rods, comprises: dissolving cysteine hydrochloride in deionized water to obtain a cysteine aqueous solution, and adjusting the pH of the cysteine aqueous solution by adding an alkaline adjusting agent to obtain an alkaline cysteine solution; adding the ZnSe / CdS quantum rods dispersed in a hydrophobic solvent into the alkaline cysteine solution to obtain a reaction mixture; stirring the reaction mixture at room temperature in the dark for a pre-set third time to allow the cysteine to exchange ligands with the surface of the ZnSe / CdS quantum rods.

7. The method of claim 1, wherein the quantum rods are chiral stabilized. The step of precipitating, separating, and redispersing the quantum rods after ligand exchange to obtain type II chiral ZnSe / CdS quantum rods, comprises: allowing the reaction mixture after ligand exchange to stand to allow the reaction mixture to phase separate; separating the aqueous phase of the reaction mixture to obtain an aqueous phase part containing the ZnSe / CdS quantum rods; adding a precipitating and purifying solvent to the aqueous phase containing the ZnSe / CdS quantum rods for precipitating and purifying treatment; dispersing the ZnSe / CdS quantum rods after purifying treatment in distilled water to obtain the type II chiral ZnSe / CdS quantum rods.

8. The method of claim 1, wherein the quantum rods are chiral stabilized. The aspect ratio of the obtained type II chiral ZnSe / CdS quantum rods ranges from 2 to 10.

9. A chiral stabilized quantum rod, characterized in that, The chiral and stable quantum rods are prepared by the method for preparing chiral and stable quantum rods according to any one of claims 1-8.

10. The chirally stabilized quantum rod of claim 9, wherein, The aspect ratio of the chiral and stable quantum rods ranges from 2 to 10.

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