CdxZn1-xS/ZnS ternary core-shell quantum dot and method for preparing same

Abstract

The invention discloses a CdxZn1-xS / ZnS(x is more than or equal to 0.51 and less than or equal to 0.84) ternary core-shell quantum dot and a method for preparing the same. The method comprises the following steps of: preparing Cd-Zn mixed precursor solution with a specific molar ratio in a reactor in one step by using cadmium oxide or inorganic cadmium salt as a cadmium source and zinc oxide or inorganic zinc salt as a zinc source, and simultaneously dissolving S powder in two different types of solvents respectively to obtain S precursor solution A and S precursor solution B; and adding the S precursor solution A and the S precursor solution B into the Cd-Zn mixed precursor solution in sequence for reaction to obtain the CdxZn1-xS / ZnS ternary core-shell quantum dot. The method adopts a simple synthesis process and avoids a centrifugal purification step before the containment shell reaction and secondary adding operation of the zinc source. The CdxZn1-xS / ZnS ternary core-shell quantum dot, prepared by the method, has the advantages that: monodispersity and photochemical stability are high; the luminescence emission peak is adjustable in a range of 422 to 493 nanometers; the position of the luminescence emission peak does not obvious deviate compared with the position of the luminescence emission peak before the containment shell; the fluorescent stability and the quantum efficiency are obviously improved; and the yield of the fluorescent quantum reaches 60 to 80 percent.

Description

technical field [0001] The invention relates to the technical field of biomedical diagnosis, in particular to a Cd x Zn 1-x S / ZnS ternary core-shell quantum dot and its preparation method. Background technique [0002] Quantum dots (QDs) refer to nanocrystals whose radius is smaller than or close to the exciton Bohr radius. When the particle size is close to or smaller than the excitonic Bohr radius, due to the quantum size effect, the continuous energy band structure of the original material is quantized, and its Significant changes occurred in photophysical and photochemical properties. Compared with traditional organic fluorescent dyes, quantum dots have rich colors, wide excitation wavelength range, narrow emission peak, and Gaussian symmetry. The emission wavelength can be adjusted by controlling their particle size and composition, and they have good photochemical stability and are not prone to fluorescence. Quenching and other advantages. Therefore, the preparatio...

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Problems solved by technology

[0004] The main technical problem in the domestic patent CN101130693 is that, firstly, the mixed precursor solution of Cd and Zn used to react with the precursor solution of Se is prepared by separately preparing the precursor solution of Cd and Zn and then mixed, so the preparation process Relatively cumbersome; secondly, the product obtained in this invention is not subjected to inorganic coating, so its photochemical stability is poor, which restricts its further application

[0005] The main technical problems in the domestic patent CN101319139 are that, firstly, the ZnS inorganic coating of the synthesized CdSeS nuclear quantum dots requires secondary addition of Zn source, resulting in a relatively cumbersome coating operation; secondly, the ZnS coating method provided by the invention, This makes the fluorescence emission peak of the finally synthesized CdSeS / ZnS ternary core-shell quantum dots uncontrollable and unpredictable

[0006] The main technical problems in the domestic patent CN101328408 are: firstly, the CdSeS nuclear quantum dot part contains Se element doping, which makes it difficult for this technology to synthesize quantum dots whose fluorescence emission peak is in the blue light region; secondly, because the S precursor solution is a single Solvent preparation, while ensuring the formation of spherical CdSeS nuclear quantum dots with uniform morphology, it is difficult to ensure that ZnS will self-assemble layer by layer on the surface of the core during the subsequent encapsulation process, and ZnS self-nucleation will occur

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