Synthesis and Characterization of Highly Luminescent CdS@ZnS Core−Shell Nanorods

Highly luminescent CdS-core ZnS-shell nanorods stabilized by mercaptopropionic acid in water were synthesized wet-chemically and characterized by measuring photoluminescence spectra and kinetic profiles as well as absorption spectra, diffraction patterns, and electron microscope images. Photoluminescence from CdS nanorods 22 nm in diameter shifts to the blue by as much as 2.8 nm and increases as high as 1.8 times with the thickness of the passivating ZnS shell, whereas the luminescence lifetime of 1:1 CdS@ZnS core−shell nanorods is shorter by 1.6 times at 550 nm than that of bare CdS nanorods. Inorganic passivation by ZnS gives rise to the intensity increase and the lifetime decrease, while alloy formation with ZnS mainly brings about the blue shift.