Article ID Journal Published Year Pages File Type
5400403 Journal of Luminescence 2013 7 Pages PDF
Abstract

•Colloidal Tb3+ and Yb3+ codoped NaYF4 NPs were synthesized.•Green UC emission was strongly dependent on the terbium ions concentration.•Tm3+ co-doping allowed five-fold enhancing of the UPC emission intensity from the Tb3+: 5D4 level.

The Tb3+ up-conversion phosphors are promising for biological applications due to their long luminescence lifetime and their spectral fingerprint being different from commonly known materials doped with Yb3+/Er3+ and Yb3+/Tm3+. The concentration dependent up-conversion emission of terbium ions has been studied in cubic NaYF4 colloidal nanocrystals doped with terbium activators and ytterbium sensitizer. Further thulium ions co-doping allowed five-fold enhancing of the up-conversion emission intensity from the 5D4 terbium level. A versatile optimization of Tb3+, Yb3+ and Tm3+ concentrations has been performed by means of luminescence spectra and lifetimes as well as power dependence studies. The up-conversion mechanisms have been proposed-cooperative energy transfer (CET) and mixed CET and energy transfer up-conversion (APTE) for Yb3+/Tb3+ and Yb3+/Tb3+/Tm3+ doped materials respectively.

Related Topics
Physical Sciences and Engineering Chemistry Physical and Theoretical Chemistry
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