Employing anhydrous molecular precursors as a strategy to enhance up-conversion efficiency in Ln -3+ doped MM'F (M = Li, Na; M' = Y, Gd)
Résumé
A major challenge in the field of upconverting (UC)
nanomaterials is to enhance upconversion luminescence. In comparison to conventional luminophores, quantum yields of lanthanide-doped UC nanoparticles are extremely low (typically less than 1%) and, in general, about an order of magnitude lower than those of corresponding UC bulk materials. It is well-known that –OH defects in the nanocrystals are the primary cause of upconversion quenching. We have employed designed anhydrous molecular precursors as a synthetic strategy to enhance upconversion efficiency in Yb and Tm co-doped MM'F nanocrystals (M = Li, Na; M' = Y, Gd). The bottom-up synthesis not only facilitates a better control over the composition, structure and morphology of the nanomaterials, but anhydrous conditions also minimize –OH functionality on the surface of the upconverting NPs. A detailed up-conversion studies reveal that the uniform nanoparticles obtained from these anhydrous single source precursors had i) superior up-conversion intensity than the UC materials produced from the hydrated inorganic salts, and ii) a comparable efficiency with bulk materials of the same composition. The applications of these
nanomaterials in the field of photocatalysis will be described.