Near-band-edge emission characteristics of ZnO-MgO core-shell quantum-dots

Colloidal ZnO-MgO core-shell quantum-dots (QDs) were synthesized using a solution-processed method. The photoluminescence results clearly show near-band-edge emission from 350 nm to 368 nm, which can be tuned by changing the particle size of the ZnO cores from 5.2 nm down to 3.8 nm. We also investigated the effects of the annealing temperature on the spin-coated QD films from 200 to 600 °C. The green emission band of this type of QDs can be fully suppressed by baking at around 200 °C, at the same time this enhances the near-band-edge emission (NBE) quantum yield from 19% to 33%. The results imply that ZnO-MgO core-shell QD is a promising candidate for the development of tunable ultraviolet (UV) light-emitting devices.