Simultaneous size manipulation and red upconversion luminescence enhancement of CaF:Yb/Ho nanoparticles by doping with Ce ions.

Harnessing the color tuning capability of upconversion nanoparticles (UCNPs) is of great significance in the field of advanced bioimaging and color display. Here, we report the tunable size and upconversion luminescence (UCL) multicolor in CaF:Yb/Ho/Ce UCNPs, which were synthesized by a facile hydrothermal method. It was found that the size of these UCNPs could be controlled (from 600 to 30 nm) by varying the concentration of Ce ions.