Aqueous phase synthesis of widely tunable photoluminescence emission CdTe/CdS core/shell quantum dots under a totally ambient atmosphere

Abstract

We report an aqueous synthetic route to colloidal CdTe/CdS core/shell quantum dots (QDs) under ambient air atmosphere without inert gas protection throughout the whole fabrication process. The obtained core/shell QDs were highly luminescent with a widely tunable photoluminescence (PL) emission window of 535–815 nm. The photoluminescence quantum yield of the corresponding QDs was typically maintained at 40% or higher in a red and near-infrared regime (600–815 nm) without any post-synthesis treatment. By studying the photoluminescence dynamics, we witnessed the band alignment transition from type-I to type-II in the CdTe/CdS core/shell structure with localized holes in the CdTe core and electrons in the CdS shell. This electronic alignment transition correlated well with the wide photoluminescence emission window and the evolution of photoluminescence quantum yield upon the coherent deposition of the CdS shell.