Photoluminescence characteristics of ZnS nanocrystallites co-doped with Co2+ and Cu2+

Zinc sulfide (ZnS) nanoparticles co-doped with Cu2+ and Co2+ have been prepared by precipitation from homogeneous solutions of zinc, copper and cobalt salt compounds, with S2− as precipitating anion formed by decomposition of thioacetamide. X-ray diffraction shows that the average crystallite size of doped and undoped ZnS nanometer-scale samples is about 2–3 nm. Novel luminescence characteristics (strong and stable visible-light emission, λem∼515–560 nm) have been observed for the co-doped ZnS nanocrystals at room temperature. The relative fluorescence intensity of the co-doped sample is dramatically higher than that of undoped ZnS nanocrystallites. The emission wavelength of the co-doped samples varies with change in the impurity mole ratio of Cu2+ and Co2+.