Tuning Size and Light Emission Characteristics of CdSes/ZnS Alloyed Core-Shell Quantum Dots By Alcohol

Abstract

In this thesis, a one-step isotropic down-tuning of the size of alloyed CdSe1−xSx/ZnS core- shell quantum dots is developed by vapor and liquid-phase etching using a ∼ 10 : 1 isopropyl alcohol to water solution. The results of spectroscopic studies confirm continuous variation of the excitonic emission color from red to green for samples treated for up to 15 mins using a vapor-based method. According to HRTEM characterizations, the shift is consistent with a diameter reduction of quantum dots that proceeds at the average rate of ∼ 1.3 ̊A/min. The emission intensity while seen to undergo an initial drop due to the shell removal, was to found to remain largely unchanged with increased treatment durations. The study presents a technologically viable alternative to adjusting the size and, in turn, the optoelectronic characteristics of core-shell quantum dots and nanocrystals in II-VI semiconductor systems.