This study investigates the effect of ultraviolet treatment on the structural and optical properties of the ZnO nanoparticles by X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy and photoluminescence measurements. A dependence of the luminescence behavior and crystal structure upon ultraviolet treatment has been found. It is shown that ultraviolet treatment may lead to the formation of surface oxygen vacancies, producing hydroxyl adsorption. The surface modification may lead to transition from hydrophobic (low surface energy) to hydrophilic (high surface energy) state, resulting in uniform distribution of the ZnO nanoparticles on the substrate. (C) 2011 Elsevier B.V. All rights reserved.