Enhanced quantum efficiency and controllable emissions of Eu through incorporation of Mn2+ in beta-NaYF4 nanocrystals

Abstract

Monodispersed Eu, Mn co-doped beta-NaYF4 nano-crystals with various morphologies, including nanoplates, hexagonal nanoprisms and microrod, have been prepared via a facile hydrothermal route. The trisodium citrate (Cit (3-)) and pH values, rather than Mn2+, play an important role in fine-tuning the morphologies. A broad band emission from the 5d-4f transition of Eu2+ as well as line emissions from the 4f-4f transitions of Eu3+ are observed in Eu, Mn co-doped beta-NaYF4. The quantum efficiency of Eu3+ was improved from 16% to 72% by inhibiting the luminescence of Eu2+. In addition, controllable emissions from Eu3+/Eu2+ can be achieved through the incorporation of Mn2+ in beta-NaYF4. The correlation between the tunable emission and enhanced quantum efficiency with Eu3+/Eu2+ and Mn2+ in beta-NaYF4 has been established and discussed in detail.