The influence of thermal treatment and solar radiation on the optical characteristics of zinc oxide nanostructures

The luminescence properties of ZnO nanorods and nanocrystals after high-temperature annealing in air and exposure to strong solar radiation were studied. Under UV radiation, as-prepared nanorods and nanocrystals exhibit the luminescence spectra with maxima at 380–384 and 560–570 nm. The thermal treatment and high-intensity solar radiation of both nanostructures results in an increase in the intensity of short-wave length luminescence bands. Moreover, the long-wave luminescence band (LB) vanishes in the spectra of nanorods, and a new band at 520 nm appears in the luminescence spectra of nanocrystals. The effect of solar radiation on the properties of nanorods is more pronounced than in the case of nanocrystals, it is possible due to predominately ray heating (annealing) of nanorods than nanocrystals.