Brightening lead sensitized terbium emission in zinc sulfide nanoparticles by fine tuning reaction conditions

Post-synthetically lead treated terbium cation doped zinc sulfide [Zn(Tb)S], Zn(Tb)S/Pb, nanoparticles (NPs) benefit from presence of two sensitizing components, namely ZnS and Pb2+. This work systematically investigates the effects of fine tuning the (a) relative reactant concentration, (b) pH, and (c) temperature of the NP's aqueous dispersion, in order to enhance the Tb3+ emission. All these factors are found to be contributing factors towards enhancing the Tb3+ emission. A comparison between the Zn(Tb)S/Pb NPs with particle diameters (d) of 3.0 ± 0.5 nm and 2.1 ± 0.2 nm reveal a quantum confinement for the ZnS NPs sensitized component, while the same is not evident for the Pb2+ sensitized counterpart. A simple comparison between the Tb3+ emission in the Zn(Tb)S [d = 3.0 ± 0.5 nm] and Zn(Tb)S/Pb [d = 2.1 ± 0.2 nm] reveals an ∼50 times increase, thus placing this as an important strategy to enhance Tb3+ emission in these NPs for potential luminescence based applications in aqueous medium.