Enhanced band-edge photoluminescence from MgO passivated ZnO nanocrystals

Intense band-edge photoluminescence is observed from ZnO nanocrystals with an average diameter of about 3 nm. It is found that the growth from high temperature (70 °C) precursor solution and succeeding surface passivation by MgO layer together lead to a five times enhancement of band-edge luminescence, in comparison to those grown by conventional low-temperature method without surface passivation. It is also found that above-band-gap illumination on the nanocrystals further enhances the luminescence intensity by five times. The strong photo-enhancement is considered to be aided by the reduction of surface non-radiative recombination path.