Absolute quantum yield of short-wave infrared luminescence of GdVO4:Yb3+, Er3+, Zn2+ nano- and microparticles

Abstract

Orthovanadate (GdVO4) nano- and microparticles doped with lanthanide ions are of interest for anti-counterfeiting and plastics recycling applications due to their emission in the short-wave infrared (SWIR) region. The unique aspect of this study is the measurement of the absolute photoluminescence quantum yield (QY) of the SWIR (1533 nm) emission for the orthovanadate nano- and microparticles co-doped withF Yb3+ and Er3+ using an integrating sphere. This is the first demonstration that doping with optically neutral Zn2+ ion significantly improves the QY of SWIR emission. A low QY of 0.1% was observed for the GdVO4:Yb3+, Er3+, Zn2+ nanoparticles synthesized by the co-precipitation method. However, the QY can be significantly increased (QY of 27.2%) after a 700 °C calcination step. This performance is approximately double that of a reference phosphor – Zn2+-free GdVO4:Yb3+,Er3+ synthesized by solid-phase reaction at 1050 °C – which achieved only QY of 13.0%. When micron-sized GdVO4:Yb3+, Er3+, Zn2+ particles are dispersed in water, a decrease in QY was observed (2.3%), which is explained by reabsorption of the luminescence by water. However, the water environment strongly quenched the SWIR luminescence (QY < 0.1%) in case of GdVO4:Yb3+, Er3+, Zn2+ nanoparticles with size of 125 nm. In summary, GdVO4:Yb3+, Er3+, Zn2+ microparticles with a QY of 27.2% can be used as bright luminescent markers in an advanced plastics processing technology - tracer-based sorting.