Synthesis of Colloidal Upconverting NaYF₄ Nanocrystals Doped with Er³⁺, Yb³⁺ and Tm³⁺, Yb³⁺ via Thermal Decomposition of Lanthanide Trifluoroacetate Precursors

Upconverting lanthanide-doped nanocrystals were synthesized via the thermal decomposition of trifluoroacetate precursors in a mixture of oleic acid and octadecene. This method provides highly luminescent nanoparticles through a simple one-pot technique with only one preparatory step. The Er3+, Yb3+ and Tm3+, Yb3+ doped cubic NaYF4 nanocrystals are colloidally stable in nonpolar organic solvents and exhibit green/red and blue upconversion luminescence, respectively, under 977 nm laser excitation with low power densities.