Manipulating the upconversion luminescence of Yb3+/Er3+ doped nanoparticles by the sheet-shaped nanocavity

Abstract

Rare-earth doped upconversion luminescence is important for display and imaging field due to its narrow band, multicolor, long lifetime and high stability. However, low quantum yield of upconversion energy transfer, weak excited states absorption and slow spontaneous radiation rates lead to weak upconversion luminescence, which may dramatically limit the practical application of upconversion nanoparticles. Here, we report a metal-sheet-shaped plasmonic nanocavity consisting of gold and silver micro-sheets. It is found that the upconversion processes (including quantum yield of energy transfer, excited states absorption and spontaneous radiation rates) were enhanced by strong local electromagnetic field of the plasmonic nanocavity when RE3+ nanoparticles were filled in the plasmonic nanocavity. The significant enhancement of the luminescence and clear directional radiation were observed under 980 nm laser excitation. By adjusting the nanogap distance of the plasmonic nanocavity, we achieved a 75-fold enhancement in 654 nm emission. Benefiting from the plasmonic nanocavity, the upconversion luminescence exhibited a directional emission, which indicates the plasmonic near-field excitation contributed to the luminescence enhancement. These findings provide a candidate for ring light source and bio-imaging application.