Effect of Co doping on optical behaviors in ZnO nanorods

The stokes shift in Co-doped ZnO nanorods are investigated through optical emission and absorption spectroscopic study. High resolution x-ray diffraction and transmission electron microscopic study reveal that well crystalline as well as rod-like nanostructures. The red shifts in UV emission due to strong exciton-phonon coupling with enhanced defect emission are employed by photoluminescence spectroscopy. The optical absorption spectroscopy indicates the blue shifting of absorption edge owing to potential fluctuation of carrier density through incorporation of Co in ZnO host. Thus the exhibited a red shift in energy for band-edge emission relative to the absorption edge, could be significant for tailoring the optical behavior of nanocrystals for specific applications by controlling their size and structure.