Preparation method and application of core-shell quantum dots

Abstract

The invention relates to a preparation method and application of core-shell quantum dots, and the preparation method comprises the following steps: (1) providing a quantum dot-containing solution which is a raw material for preparing the core-shell quantum dots; (2) mixing a raw material for preparing the core-shell quantum dot with short-chain fatty acid zinc with the carbon chain length of less than or equal to 8 and long-chain fatty acid with the carbon chain length of more than or equal to 12, and reacting at a first temperature to obtain an intermediate solution; (3) mixing the intermediate solution with a precursor containing an Se element, and carrying out a reaction at a second temperature to coat the surface of the quantum dot with a ZnSe shell layer so as to obtain a solution containing a core-shell quantum dot intermediate; and (4) taking the solution containing the core-shell quantum dot intermediate as a raw material for preparing the core-shell quantum dot in the step (1), and repeating the steps (2) and (3) at least once for coating to obtain the core-shell quantum dot. The quantum yield of the core-shell quantum dot is kept at 95% or above along with the increase of the thickness of the ZnSe shell layer, so that the external quantum efficiency of a photoelectric device applying the core-shell quantum dot can be improved, and the service life of the photoelectric device can be prolonged.

Description

technical field [0001] The invention relates to the technical field of quantum dots, in particular to a preparation method and application of core-shell quantum dots. Background technique [0002] At present, the outer layers of blue light quantum dots such as CdZnS / ZnS, CdZnSeS / ZnS, and ZnCdSe / ZnS are all coated with a thicker ZnS shell layer, resulting in a deep HOMO of blue light quantum dots, which is not conducive to the effective injection of holes, making photoelectric The lifetime of the device is low and cannot meet the minimum requirements for commercialization. [0003] In terms of quantum dot synthesis, due to the more suitable conduction band and valence band positions of ZnSe, as well as the more matching unit cell parameters, ZnSe is usually used as a shell to coat quantum dots such as CdSe, CdZnSe, and InP. Studies have shown that coating ZnCdSe with a ZnSe shell with a thickness of about 7nm can effectively increase the HOMO of blue quantum dots and shorten...

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Problems solved by technology

However, the ZnSe shell is prepared by the existing heating method, one-pot method or drop coating method. When the thickness of the ZnSe shell is large, such as greater than 3nm, ZnO and ZnSeO will be formed. 3 and other oxidation products, resulting in lattice dislocation during the growth process of the ZnSe shell, resulting in defect sites

These defect sites will capture excitons and produce non-radiative transitions, which directly lead to a sharp drop in the quantum yield of blue quantum dots, which is only about 73%, which is far lower than the close to 100% level of green quantum dots and red quantum dots. As a result, the external quantum efficiency of optoelectronic devices using such blue light quantum dots is only about 8%, which is far lower than the 20% external quantum efficiency of optoelectronic devices using green light quantum dots and red light quantum dots.

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