Structural and optical properties of hydrothermally grown zinc oxide nanorods on polyethersulfone substrates as a function of the growth temperature and duration

Zinc oxide (ZnO) nanorods were grown on polyethersulfone substrates with a seed layer by hydrothermal synthesis. The effects of the growth temperature and duration on the structural and optical properties of the ZnO nanorods were investigated by X-ray diffraction, field emission scanning electron microscope and photoluminescence measurements. Improvement of the structural properties was confirmed when the ZnO nanorods were grown at a moderate thermal energy. Thermal energies that were too high or too low resulted in structural degradation: low thermal energies did not provide enough energy for the ZnO growth, and high thermal energies contributed to improper growth by creating an uncommon flake-like structure. Photoluminescence measurements showed that the near-band-edge emission to deep-level emission peak ratio increases with increasing growth temperature at growth duration of 5 h.