Structural, optical and photoluminescence properties of Eu³⁺ doped ZnO nanoparticles

The structure, particle morphology and luminescent properties of europium (Eu³⁺) doped ZnO nanoparticles (NPs) prepared by co-precipitation method are discussed. When excited using a 325nm He-Cd laser, undoped ZnO NPs exhibited weakly the well-known ultraviolet excitonic recombination emission (at ~384nm) and strongly broad band visible emissions associated with defects (at ~600nm). In addition, the ZnO NPs exhibited green emission at ~600nm associated with defects when excited using a monochromatized xenon lamp. Upon Eu³⁺ doping line emissions attributed to ⁵D₀→⁷F_1,2,3,4 transitions of Eu³⁺ ions were observed when the materials were excited using a monochromatized xenon lamp. The exchange interaction mechanism is identified as the cause for concentration quenching of the luminescence of Eu³⁺ doped ZnO NPs in this study.