Controlling the morphology of polymeric precursor-derived ZnO flower-like structures

The study of the mechanisms of formation and growth of ZnO nanostructures is crucial as they have the potential to find applications in opto-electronic devices. ZnO nanostructures of different morphologies have been synthesized using a low-temperature polymeric precursor process. Controlling the Zn cation and nitric acid concentrations, flower-like morphology of the ZnO nanostructures could be synthesized with excellent reproducibility. Besides chemistry, the effects of spin-coating variables on morphology were also investigated. The results show that the morphology of the flowers is controlled by Zn2+ ion concentration, whereas spin speed and film thickness are responsible for the size variations. All obtained ZnO structures reveal a polycrystalline hexagonal wurtzite structure and strong UV photoluminescence along with lattice defects. Polar surfaces of ZnO promoting multilayer Volmer-Weber growth play a crucial role in the development of these flower-like structures. Possible mechanisms for variations of morphology with synthesis parameters are discussed.