核-壳结构CdSe/ZnS量子点的制备、硫醇修饰及其光学性能

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

采用高温有机相包覆技术制备了CdSe/ZnS核壳结构量子点材料,考察了包覆量对量子点材料的光学性能的影响,研究了含脂肪链和芳香基的双硫醇分子1,4-苯二甲硫醇和1,8-辛二硫醇对于具有核-壳结构的CdSe/ZnS量子点材料的修饰作用,考察了修饰作用对于量子点的量子效率和荧光强度等光学性能的影响.实验结果表明:随着硫化锌包覆量的增加,量子点的量子效率及其荧光发射强度明显提高;硫醇的修饰能显著增强量子点的发光强度,随着硫醇浓度的增加,其发光性能增强,但是达到一定程度后,光学性能基本不随硫醇浓度的变化而变化.根据固体核磁共振等实验结果推测:硫醇分子可能部分替代了量子点体系中的正三辛基氧膦配体,稳定了量子点体系,对量子点起修饰保护作用,从而提高了量子点的光学性能.

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.