Up-conversion luminescence in Yb3+–Er3+ co-doped PbF2 nanoparticles synthesized using the hydrothermal method

PbF2:Yb3+,Er3+ nanoparticles were synthesized using the hydrothermal method. The upconversion (UC) luminescence properties of products obtained under different Yb3+ doping concentrations and annealing temperatures were then investigated. As the Yb3+ concentration increased, the product structures transformed from a mixed phase to a cubic phase. Their total emission intensities, however, were remarkably low. After annealing, the UC emission of the products was enhanced because of their increased grain size. The maximum emission was obtained with 7% Yb3+. The products were applied in a hydrogenated amorphous silicon solar cell, and an external quantum efficiency of 0.04% was measured under the illumination of a 980 nm laser at 4.8 W/cm2.