Intense and wavelength-tunable photoluminescence from surface functionalized MgO nanocrystal clusters

We report fancy brilliant photoluminescence (PL) from surface functionalized MgO nanocrystal clusters (NCs). Single-crystal-like MgO NCs were prepared by a simple one-pot pyrolysis method in the mixed organic solvent of octylamine (OTA) and oleic acid (OA) using magnesium acetate as a precursor. Under the chemical equilibrium of etching and re-growth with the assistance of OA, the MgO products were surface functionalized. It was found that such surface functionalized MgO NCs exhibited intense visible light PL with high PL thermal-stability, and the apparent quantum yield was as high as 19 ± 1%. In addition, through controlling the synthetic temperature and the reaction time, the functionalized surfaces of MgO NCs were facilely tuned, resulting in the tuneable wavelength of the PL from blue-violet to yellow. Different low-coordinated oxygen sites, capping OA and carbonate species on the surface of the MgO nanocrystals were thought to be the origin of PL at different wavelengths. Considering the intense PL, high PL stability at ambient conditions, low cost and low toxicity, such MgO NCs might have potential applications in medicine and biology as a new kind of fluorescent label.