Correlation between Morphology and Defect Luminescence in Precipitated ZnO Nanorod Powders

ZnO nanorods were prepared at relatively low temperatures by homogeneous precipitation from zinc nitrate and urea in a water/ethylene glycol mixture. Crystal size and morphology are controlled by growth time and solvent composition. We observed a strong correlation between nanocrystals’ size/morphology and their optoelectronic defect-related properties. Smaller crystallites exhibited intense deep-defect luminescence and enhanced emission related to near-surface excitonic recombination. Longer growth times lead to formation of well-defined nanorods with hexagonal symmetry exhibiting reduced defect emission.