Morphology-dependent upconversion luminescence of ZnO:Er3+ nanocrystals

Morphology impact on the upconverted luminescence of ZnO:Er3+ nanocrystals was studied with controllable morphology of nanorod, prickly sphere-like, column-like, branch rod, prism-like, and grain-like, prepared via the cetyltrimethylammonium bromide (CTAB)-assisted hydrothermal process. The upconversion emission of Er3+ with 980 nm excitation demonstrated morphology sensitivity which was related with the local environments of Er3+ ions in ZnO and doping efficiency. Under ultraviolet (UV) direct excitation, where exciton and defect emissions of ZnO appeared, morphology sensitivity was discussed in terms of surface-to-volume ratios.