Full-color photoluminescence of ZnO nanorod arrays based on annealing processes

Vertically well-aligned ZnO nanorod arrays with highly crystalline wurtzite structures were synthesized on ITO glass substrates by a two-step hydrothermal method, and then, annealed at different temperatures and under different atmospheres. Photoluminescence spectra showed a near-band-edge (NBE) emission peak and an intense broad visible emission band for as-grown and annealed samples. These visible emission bands exhibited dependences on post-annealing conditions and excitation energies. Emission shifting in the visible region was investigated and explained in terms of the presence of defects. Based on these findings, we demonstrate that the visible emission in these materials can be tailored by controlling the defects in ZnO. Under different annealing conditions, it is possible to manipulate the emission in the visible region, which has important implications for the production of optoelectronic devices.