ZnO_PVA_luminescence_spectroscopy_TSNUK

Zinc oxide nanoparticles were successfully synthesized in polyvinyl alcohol (PVA) media using a modified co-precipitation method and a green chemistry approach. Single-phase ZnO samples with wurtzite structure were formed already at 400 °C. The polymer media forms agglomerating clouds around the ZnO nanoparticles. Average nanoparticle size has tendency to decrease with the PVA content. Visible photoluminescence and radioluminescence emission spectra of the pure ZnO and ZnO-xPVA revealed strong differences. The spectra of pure ZnO samples contains components at 385 and 510 nm corresponded to excitonic and defect-related emission, respectively. Spectra of the ZnO-xPVA samples are dominated by a band peaked in the red spectral region. This band consists of two components at 630 and 720 nm which are assigned to recombination transitions from Zni and Hi to Oi defect energy levels, respectively. These results demonstrate that luminescence of ZnO can be tailored by manipulating defect configurations, even without high-temperature processing