Surface related and intrinsic exciton recombination dynamics in ZnO nanoparticles synthesized by a sol-gel method

ZnO nanoparticles with controlled sizes produced by a sol-gel method are studied by means of time-integrated as well as time-resolved photoluminescence (TRPL) spectroscopy. Room-temperature photoluminescence spectra show a blueshift of the excitonic emission with the decreasing particle size, which is attributed to the quantum confinement effect. The temperature dependence of the exciton lifetimes deduced from the TRPL results contains two components: the fast decay is attributed to surface trapping of exciton and the slow decay is mainly representative of the radiative processes involving the bound or free excitons. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4774002]