Annealing effect on the photoluminescence properties of ZnO nanorod array prepared by a PLD-assistant wet chemical method

Well-aligned ZnO nanorod arrays were synthesized by a wet chemical method on the glass substrate with ZnO thin film as seed layer prepared by pulsed laser deposition. The effect of annealing temperature on the luminescence characteristics was investigated. As the annealing temperature increased, the photoluminescence properties show a general enhancing tendency. The nanorod array with high ultraviolet emission and negligible visible light emission (designated by the photoluminescence intensity ratio of ultraviolet to visible emission of 66.4) is obtained by annealing the sample at 700 °C for 1 h. Based on the results of X-ray photoelectron spectroscopy and photoluminescence spectra, the mechanisms of visible emission were discussed.

Research Highlights
► ZnO nanorod array with good crystallography, low defects concentration and good optical property was obtained after annealed at 700 °C for 1 h.
► The transition from the conduction band to the Oi level may be responsible for the yellow-green emission.
► The yellow emission may originate from the presence of Zn(OH)2 on the surface or the band transition from conduction band to VoZni level.
► The transition from the Zni level to the level should produce an orange emission or an orange-red emission.