阅读说明：本技术 一种无机配体修饰的CdSe/CdS@ZnO量子点的制备方法 (Preparation method of inorganic ligand modified CdSe/CdS @ ZnO quantum dot ) 是由 张雷 王超男 于 2021-06-08 设计创作，主要内容包括：本发明公开了一种无机配体修饰的CdSe/CdS@ZnO量子点的制备方法,将CdSe/CdS核壳量子点通过正丁醚进行经提纯后,采用乙醇胺对其表面改性,再包覆无机ZnO溶胶作为表面配体,得到无机配体修饰的CdSe/CdS@ZnO量子点。本发明无机量子点的制备方法,可以有效解决传统胶体量子点表面有机配体存在的问题,进而增强量子点的光学性能及其稳定性,而且仍可稳定分散于有机溶剂,保持基于各种溶液环境的量子点光电器件的制备优势。本发明提出的制备方法简单且高效,有利于促进量子点光电器件商业化应用。(The invention discloses a preparation method of inorganic ligand modified CdSe/CdS @ ZnO quantum dots. The preparation method of the inorganic quantum dot can effectively solve the problems of the organic ligand on the surface of the traditional colloidal quantum dot, further enhance the optical performance and the stability of the quantum dot, can be stably dispersed in an organic solvent, and keeps the preparation advantages of quantum dot photoelectric devices based on various solution environments. The preparation method provided by the invention is simple and efficient, and is beneficial to promoting the commercial application of the quantum dot photoelectric device.)

1. A preparation method of inorganic ligand modified CdSe/CdS @ ZnO quantum dots is characterized by comprising the following steps: and purifying the CdSe/CdS core-shell quantum dots by n-butyl, modifying the surfaces of the CdSe/CdS core-shell quantum dots by adopting ethanolamine, and coating inorganic ZnO sol as a surface ligand to obtain the CdSe/CdS @ ZnO quantum dots modified by the inorganic ligand.

2. The preparation method of inorganic ligand modified CdSe/CdS @ ZnO quantum dot according to claim 1, characterized in that: the preparation method comprises the following specific steps:

(1) preparing CdSe/CdS core-shell quantum dots: adding the purified CdSe nuclear quantum dots, oleylamine and octadecane into a three-neck flask, heating to the reaction temperature under the protection of argon, alternately injecting a Cd precursor and an S precursor by using a continuous ionic layer adsorption and reaction method, obtaining CdSe/CdS nuclear shell quantum dots with shell thicknesses of 5-20 CdS monolayers by controlling the injection amount of the precursors, and dispersing in a toluene solution after centrifugal purification;

(2) purifying the prepared CdSe/CdS core-shell quantum dots: volatilizing a toluene solvent in the CdSe/CdS core-shell quantum dot solution obtained in the step (1) completely, purifying the quantum dot by using n-butyl ether, removing excessive organic long carbon chain ligands on the surface of the CdSe/CdS core-shell quantum dot, volatilizing the n-butyl ether solvent in the CdSe/CdS core-shell quantum dot solution with the organic long carbon chain ligands removed completely, and adding chloroform to fully disperse the CdSe/CdS core-shell quantum dot;

(3) and (3) carrying out surface modification on the purified CdSe/CdS core-shell quantum dots by utilizing ethanolamine: transferring the quantum dot solution obtained in the step (2) into a sampling bottle, adding ethanolamine, and stirring at the room temperature of 16-28 ℃ for 23-25 hours to obtain an ethanolamine surface modified quantum dot sample;

(4) inorganic sol ligand modification: firstly, preparing an inorganic ZnO sol solution by using a chemical reduction method, then carrying out inorganic ligand modification on the quantum dot sample obtained in the step (3) by using the inorganic ZnO sol solution, and dropwise adding the ZnO sol solution while shaking to enable the quantum dot solution to be clear and transparent, thus obtaining the inorganic sol ligand modified CdSe/CdS @ ZnO quantum dot.

3. The preparation method of inorganic ligand modified CdSe/CdS @ ZnO quantum dot according to claim 2, characterized in that: the preparation of the CdSe nuclear quantum dots in the step (1) comprises the following steps: cadmium oleate is prepared from CdO and oleic acid and used as a Cd precursor, and a Se precursor is added into the prepared cadmium oleate to prepare the CdSe nuclear quantum dot.

4. The preparation method of inorganic ligand modified CdSe/CdS @ ZnO quantum dot according to claim 3, characterized in that: the CdSe/CdS core-shell quantum dots are prepared in the step (1) specifically: adding the purified CdSe nuclear quantum dots, oleylamine and octadecane into a three-neck flask, raising the reaction temperature to 250 ℃ under the protection of argon, and alternately injecting a Cd precursor and an S precursor by utilizing a continuous ionic layer adsorption and reaction method, wherein the growth time after each injection is 18-22 minutes; CdSe/CdS core-shell quantum dots with the shell layer thickness of 5-20 CdS monomolecular layers can be obtained by controlling the injection amount of the precursor, and are dispersed in a toluene solution after centrifugal purification.

5. The preparation method of inorganic ligand modified CdSe/CdS @ ZnO quantum dot according to claim 2, characterized in that: the step (2) of purifying the CdSe/CdS core-shell quantum dots: adding n-butyl ether into the CdSe/CdS core-shell quantum dots after the toluene solvent is completely volatilized, heating the CdSe/CdS core-shell quantum dots in a water bath kettle at the temperature of 50-60 ℃ for 5-20 minutes, placing the sample in a refrigerator for 5-10 minutes, centrifuging to remove flocculent precipitates, and removing excessive organic ligands on the surfaces of the quantum dots.

6. The preparation method of inorganic ligand modified CdSe/CdS @ ZnO quantum dot according to claim 2, characterized in that: the specific method for preparing the inorganic ZnO sol solution by using the chemical reduction method in the step (4) comprises the following steps: adding ethanolamine and methanol into a three-neck flask, magnetically stirring for 27-35 minutes at room temperature of 16-28 ℃, then adding zinc acetate, stirring for 1.8-2.2 hours under the condition of a water bath at 50-70 ℃, and curing for 23-25 hours to obtain the inorganic ZnO sol solution.

Technical Field

The invention relates to the field of nano materials, in particular to a preparation method of inorganic ligand modified CdSe/CdS @ ZnO quantum dots; the method enhances the optical performance and optical stability of the quantum dots, and is beneficial to realizing the practical application of the colloidal semiconductor quantum dots on photoelectric devices.

Background

Because the semiconductor quantum dots have large specific surface area, a large number of active atoms and dangling bonds on the surface of the semiconductor quantum dots easily cause surface defect states, and non-radiative recombination centers are easily formed, so that the fluorescence quantum yield and the non-linear optical properties of the quantum dots are seriously reduced. The surfactant introduced in the preparation process not only regulates the nucleation and growth kinetic process of the quantum dots and controls the size and shape of the quantum dots, but also plays a role of a surface ligand, can provide enough space or electrostatic repulsive force to ensure that the quantum dots are stably dispersed in a solution and are prevented from agglomeration, and can passivate a surface trap state, thereby improving the optical performance of the quantum dots. Although the existence of the surface organic ligand can improve the surface property and the fluorescence quantum yield, the optical property stability of the soft passivated quantum dot is poor. Meanwhile, defects may also be introduced on the surface of the quantum dots in the surface organic ligand modification process. For practical light emitting applications, an inorganic shell layer is generally selected to be epitaxially grown on the surface of the quantum dot to form the core-shell heterostructure semiconductor quantum dot. Research results show that the thicker inorganic shell layer has better protection effect on the nuclear quantum dots.

At present, the inorganic shell layer can effectively passivate the defect state of the surface of the nuclear quantum dot to a certain extent, and isolate the direct interference of the ambient environment (oxygen, moisture and the like) to the optical performance of the quantum dot. However, with the advent of quantum dot optoelectronic device application technology, the disadvantage that the thick shell structure is not beneficial to charge balance injection is highlighted, and the luminous efficiency of the quantum dot electroluminescent LED device is hindered to a certain extent. Meanwhile, with the increase of the shell layer thickness, the electron wave function is gradually diffused into the thick shell layer, so that the optical property of the quantum dot is easily influenced by the unstable factors of the surface organic ligand, and the stability of the optical property of the quantum dot is seriously challenged. Therefore, it is urgently needed to find a new method which enables the quantum dots to have excellent optical performance and stability and solve the key problems in practical application.

Disclosure of Invention

The technical problem is as follows: in order to solve the problems in the prior art and practical application, the invention provides a preparation method of inorganic ligand modified CdSe/CdS @ ZnO quantum dots which have excellent optical performance and stability and can solve the bottleneck of practical application.

The technical scheme is as follows: in order to solve the technical problems, the invention provides a preparation method of an inorganic ligand modified semiconductor quantum dot, which comprises the steps of purifying CdSe/CdS core-shell quantum dots by n-butyl ether, modifying the surfaces of the CdSe/CdS core-shell quantum dots by ethanolamine, and replacing organic long carbon chains on the surfaces of the quantum dots with ZnO sol to serve as an inorganic ligand to finally prepare the practically all-inorganic CdSe/CdS @ ZnO quantum dots.

The preparation method comprises the following specific steps:

(1) preparing CdSe/CdS core-shell quantum dots: adding the purified CdSe nuclear quantum dots, oleylamine and octadecane into a three-neck flask, heating to the reaction temperature under the protection of argon, alternately injecting a Cd precursor and an S precursor by using a continuous ionic layer adsorption and reaction method, obtaining CdSe/CdS nuclear shell quantum dots with shell thicknesses of 5-20 CdS monolayers by controlling the injection amount of the precursors, and dispersing in a toluene solution after centrifugal purification;

(2) purifying the prepared CdSe/CdS core-shell quantum dots: volatilizing a toluene solvent in the CdSe/CdS core-shell quantum dot solution obtained in the step (1) completely, purifying the quantum dot by using n-butyl ether, removing excessive organic long carbon chain ligands on the surface of the CdSe/CdS core-shell quantum dot, volatilizing the n-butyl ether solvent in the CdSe/CdS core-shell quantum dot solution with the organic long carbon chain ligands removed completely, and adding chloroform to fully disperse the CdSe/CdS core-shell quantum dot;

(3) and (3) carrying out surface modification on the purified CdSe/CdS core-shell quantum dots by utilizing ethanolamine: transferring the quantum dot solution obtained in the step (2) into a sampling bottle, adding ethanolamine, and stirring at the room temperature of 16-28 ℃ for 23-25 hours to obtain an ethanolamine surface modified quantum dot sample;

(4) inorganic sol ligand modification: firstly, preparing an inorganic ZnO sol solution by using a chemical reduction method, then carrying out inorganic ligand modification on the quantum dot sample obtained in the step (3) by using the inorganic ZnO sol solution, and dropwise adding the ZnO sol solution while shaking to enable the quantum dot solution to be clear and transparent, thus obtaining the inorganic sol ligand modified CdSe/CdS @ ZnO quantum dot.

Further, the step (1) of preparing the CdSe nuclear quantum dots comprises the following steps: cadmium oleate is prepared from CdO and oleic acid and used as a Cd precursor, and a Se precursor is added into the prepared cadmium oleate to prepare the CdSe nuclear quantum dot.

Further, the CdSe/CdS core-shell quantum dots prepared in the step (1) specifically comprise the following steps: adding the purified CdSe nuclear quantum dots, oleylamine and octadecane into a three-neck flask, raising the reaction temperature to 250 ℃ under the protection of argon, and alternately injecting a Cd precursor and an S precursor by utilizing a continuous ionic layer adsorption and reaction method, wherein the growth time after each injection is 18-22 minutes; CdSe/CdS core-shell quantum dots with the shell layer thickness of 5-20 CdS monomolecular layers can be obtained by controlling the injection amount of the precursor, and are dispersed in a toluene solution after centrifugal purification.

Further, the step (2) of purifying the CdSe/CdS core-shell quantum dots: adding n-butyl ether into the CdSe/CdS core-shell quantum dots after the toluene solvent is completely volatilized, heating the CdSe/CdS core-shell quantum dots in a water bath kettle at the temperature of 50-60 ℃ for 5-20 minutes, placing the sample in a refrigerator for 5-10 minutes, centrifuging to remove flocculent precipitates, and removing excessive organic ligands on the surfaces of the quantum dots.

Further, the specific method for preparing the inorganic ZnO sol solution by using the chemical reduction method in the step (4) comprises the following steps: adding ethanolamine and methanol into a three-neck flask, magnetically stirring for 27-35 minutes at room temperature of 16-28 ℃, then adding zinc acetate, stirring for 1.8-2.2 hours under the condition of a water bath at 50-70 ℃, and curing for 23-25 hours to obtain the inorganic ZnO sol solution.

Has the advantages that: compared with the prior art, the invention discloses a preparation method of the inorganic ligand modified CdSe/CdS @ ZnO quantum dot, which can effectively avoid the adverse effect of external factors and surface defects related to organic ligands on the optical performance of the semiconductor quantum dot, greatly enhance the optical performance stability of the quantum dot, and facilitate the further development and application of the quantum dot photoelectric device. The preparation method provided by the invention is simple and high in efficiency, so that the semiconductor quantum dot technology is a solid step in practical application; therefore, the invention hopefully solves the adverse effect of the surface organic ligand on the optical performance and stability of the quantum dots and the difficulty in practical application.