Comparative study of time-resolved photoluminescence properties of terbium-doped thiosalicylic-capped CdS and ZnS nanocrystals

We report on the time-resolved photoluminescence (PL) properties of terbium ion doped in US and ZnS nanocrystals (NCs). The NCs are capped with thiosalcylic acid (TSA) with size ranging from 3 to 5 nm and studied in aqueous solutions. We found that, although the sensitization of terbium PL in both US and ZnS nanocrystals takes place through the same route, namely via the TSA, the dynamics and intensity of terbium PL strongly depend on the nanocrystal type. The observed differences are explained through the different binding modes of the TSA capping molecule with the surface ions of US and ZnS nanocrystals. Our results corroborate recent studies on binding of thiol acids with cadmium and zinc chalcogenide nanocrystals.