Stable CdS QDs with intense broadband photoluminescence and high quantum yields

Aqueous synthesis of CdS quantum dots (QDs) using thiolactic acid (TLA) as a capping agent was reported. These QDs exhibited excellent colloidal and photostability over a span of 2 years and showed intense broadband and almost white photoluminescence suitable for solid state lighting devices. The photoluminescence (PL) property of the aqueous CdS QDs is optimized by adjusting various processing parameters. The highest quantum yield (QY) achieved for TLA capped CdS QDs of average size 3.5 nm was ∼50%. Luminescence lifetime measurements of CdS–TLA QDs indicated longer lifetimes and a larger contribution of the surface-related emission, indicating removal of quenching defects.

► Optical properties of thiolactic acid capped CdS quantum dots (QDs) were studied.
► CdS QDs showed broadband luminescence with high quantum yield.
► Prepared thiolactic acid capped CdS QDs are promising for white light application.