Up-/downconversion luminescence in Gd2O3:Yb3+/Er3+ nanocrystals: Emission manipulation and energy transfer phenomena

The large number of energy levels available to lanthanide ions makes the emission mechanism of lanthanide-doped luminescent materials extremely complicated. Herein, we focus on the discussion and analysis of luminescence manipulation in Gd₂O₃:Yb³⁺/Er³⁺ nanocrystals and systematically investigate ion-ion interaction–induced energy transfer in up- and downconversion processes to shed light on the manipulation mechanism, showing that the luminescence of the above nanocrystals can be controlled by varying the content of Yb³⁺. Based on Dexter's energy transfer theory and the fact that excitation of Er³⁺ ions results in the appearance of emission attributed to the ²F_5/2→²F_7/2 transition of Yb³⁺ in the near-infrared region (950–1100 nm), this behavior is ascribed to the occurrence of energy transfer from Er³⁺ to Yb³⁺.