Luminescence enhancement due to energy transfer in ZnO nanoparticles and Eu ions co-doped silica

SiO₂ thin films co-doped with ZnO nanoparticles and Eu^3 + ions were prepared by sol-gel method. The formation of nano-sized ZnO particles was confirmed by X-ray diffraction patterns and transmission electron microscopy. The characteristic emission bands from Eu^3 + ions can be observed at room temperature and the luminescence intensity is increased obviously by introducing ZnO nanoparticles into Eu^3 +-doped silica films. The integrated luminescence intensity is influenced by the concentration and size of ZnO particles, suggesting effective energy transfer from nano-sized ZnO to Eu^3 + ions. It is argued that the efficient luminescence enhancement occurs under the suitable Zn^2 + amount and annealing temperature.