Investigation of the effect of annealing on the photoluminescence properties of ZnO nanoparticles, synthesized at low temperature

ZnO nanoparticles were synthesized by a simple chemical precipitation method at 0 °C and annealed in air at temperatures of 200, 400 and 600 °C. Effect of annealing temperature on the optical properties were characterized by the UV–Vis and photoluminescence (PL) spectroscopy. The PL spectra of as prepared ZnO nanoparticles exhibits a narrow UV and a broad yellow emission peaks which are related to defect levels in the band gap. With the annealing temperature increasing, the intensity of yellow emission is strongly decreased, whereas the green emission is revealed. In addition, it was found that, there is a slight red shift in the UV absorption peak and a blue shift in the visible emission peak when the annealing temperature increases.

► ZnO nanoparticles were synthesized at low temperature by a chemical method.
► The samples (ZnO nanoparticles) were annealed at different temperatures; 200, 400 and 600 °C.
► The as synthesized sample has revealed a strong emission peak in visible region.
► The yellow emission intensity is strongly decreased, but the green emission is revealed by annealing.
► A slight red shift can be found in the Eg with increasing the annealing temperature.