Application of Ultrasonic Irradiation in Aqueous Synthesis of Highly Fluorescent CdTe/CdS Core−Shell Nanocrystals

Abstract

1-Thioglycerol-capped CdTe nanocrystals were used as core template to generate CdTe/CdS core−shell nanocrystals in aqueous solution by means of ultrasonic irradiation. The photoluminescence quantum yields of CdTe/CdS core−shell nanocrystals were up to 20%, larger than the original CdTe nanocrystals by around 10 times. The reaction conditions, such as the concentration, the molar ratio of reactants, and the pH value, were investigated, showing that ultrasonic irradiation controlled the decomposition of thiourea and the formation of a gradient CdS shell around the original CdTe core.