Thermolytic Growth of ZnO Nanocrystals: Morphology Control and Optical Properties

ZnO nanostructures with triangular and rod-like morphologies could be grown by thermolysis of zinc acetate in oleylamine solvent using oleic acid as surfactant. Concentration of the zinc precursor in the reaction mixture had a strong effect on the final morphology of the ZnO nanostructures. While a low precursor concentration results in triangular morphology, high precursor concentrations favor rod-like morphologies of the nanostructures. The room temperature photoluminescence (PL) spectra of both nanostructures are dominated by the green emission attributed to the oxygen vacancy (Vo) related donor-acceptor transition. Presence of several infrared (IR) inactive vibrational modes in the Fourier transform infrared (FT-IR) absorption spectra of the samples indicates a breakdown of translational symmetry in the nanostructures induced by native defects. Possible mechanisms of the morphology evolution and the origin of observed visible emissions in the nanostructures are discussed.