Structural, optical and photoluminescence properties of Eu^3 + doped ZnO nanoparticles

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