One-Step Synthesis, Structural and Optical Characterization of Self-Assembled ZnO Nanoparticle Clusters with Quench-Induced Defects

The applications of zinc oxide (ZnO) nanostructures require tuning of the defect levels which govern their optical properties. Self-assembled 8–10 nm ZnO nanoparticle clusters with different defect concentration were prepared by thermal decomposition of zinc acetate dihydrate at 900 � C and subsequent quenching in air, ice and liquid nitrogen. The cell volume and quench-induced structural disorder proportionately increased with larger temperature difference between 900 � C and the quenching media. Multi-peak “tting of the photoluminescence (PL) spectra showed that only zinc interstitials and zinc vacancies were present without any oxygen vacancy. Multiple violet emissions were attributed to the energy levels associated with interface trap in the grain boundaries and dislocations. The three quenched samples showed higher intensity of the defect bands as compared to pristine ZnO. Electron transfer to carbon nanowhiskers was facilitated by the defect bands at the lowest energy levels associated with the grain boundaries, dislocations and surface traps.