Optical Properties of Co2+ Doped ZnS Nanocrystals

ZnS nanocrystals with Co2+ doping have been prepared through a soft chemical route. The undoped ZnS and Co2+ doped ZnS:Co nanocrystals have been analyzed using X-ray diffraction (XRD), high resolution transmission electron microscope (HRTEM), and ultraviolet-visible (UV-VIS) spectrophotometer. Undoped sample exhibits room-temperature photoluminescence (PL) emission in the blue region with a broad spectral band peaked at similar to 397 nm under UV excitation. But from the 1.5% Co2+ doped samples, a strong blue emission peaked at similar to 470nm is observed and further increase in doping leads to considerable blue shift and enhancement in intensity of the PL spectrum.