Preparation and modification of core shell structure CdSe/ZnS quantum dots and their optical properties

Abstract

A core shell structure CdSe/ZnS quantum dots were prepared by an organic coverage approach and the effect of coverage amount of ZnS on the optical properties of the quantum dots materials was investigated. Furthermore, the core shell quantum dots materials were modified with thiols, the influence of modification of aromatic thiol of 1,4-benzenedimethanethiol and aliphatic thiol of 1,8-octanedithiol on the optical properties of the materials were studied, respectively. It was found that the optical properties of core-shell structure CdSe/ZnS quantum dots were enhanced significantly with the coverage of ZnS and the modification of thiols. The quantum yield and strength of photoluminescence were increased with the increase of covered amount of ZnS, also, the modification of thiols could enhance the strength of photoluminescence and the stability of the quantum materials, generally the optical properties of modified quantum materials were improved with the increase of thiols concentration, but as the concentration of thiols increased until to a certain extent, then the optical properties were not varied. 31P solid-state NMR spectra revealed that the trioctylphosphine oxide ligand on CdSe/ZnS quantum dots’surface might be partial replaced by thiols molecules, which results in the enhancement of optical properties and the better stability.