Abstract
Infrared (IR)-emitting rare-earth (RE) doped materials have been extensively studied for many years due to their diverse application in various fields. It is critically important to demonstrate that the significant enhancement of IR emission in nanophosphors can be achieved, not only for better understanding of the physical mechanism but also for expanding the IR-related applications of these nanophosphors, which include optical amplifiers, waveguides, laser materials and infrared imaging probes. In this work, we report the control of particle morphology and IR emission enhancement of hexagonal-phase NaYF4 particles using a tri-dopant scheme of ytterbium (Yb), erbium (Er) and cerium (Ce). By optimizing the Ce dopant concentrations, IR emission was enhanced by 73.1% and 109.6% for NaYF4 microparticles (N-MPs) and nanoparticles (N-NPs), respectively. The effects of Ce dopant concentrations on the nucleation and growth mechanism as well as the optical behavior of N-MPs and N-NPs were studied systematically.