Ligand Effects and Synthesis of NaYF4 Based Up and Downconversion Colloidal Nanophosphors

The effects of ligands on the synthesis of colloidal NaYF4:Yb,Er upconversion nanophosphors (UCNPs) are reviewed. New results of using stearic acid (SA) and lauric acid (LA) and their combination with trioctylphosphine (TOP) as the ligands are compared with the commonly used oleic acid (OA). The strong dependence of crystallinity and monodispersity of nanophosphors (NPs) on the steric effect of ligands as well as the synthesis temperature and precursor concentrations are summarized. Synthesis and characterization of the core/shell structured UCNP/NaYF4, DCNP (downconversion nanophosphors, NaYF4:Eu)/UCNP, and UCNP/DCNP NPs are also presented.