Remote manipulation of upconversion luminescence

The precise control over the luminescence profile of lanthanide-doped upconversion nanomaterials is of fundamental importance for their applications in wide-ranging fields of research. Conventional chemical approaches can lead to color-tunable emissions, but they generally require stringent modification either on dopant composition or doping concentration. In this Tutorial Review, we highlight a number of complementary methods that offer remote dynamic modulation of upconversion luminescence across the visible spectrum. This review serves to provide a summary of existing guidelines for controlling the emission spectrum of upconversion nanocrystals with fixed materials composition. The review will also discuss the major approaches to manipulating excitation energies and consider likely research challenges for further development of the field at the interface between nanotechnology and biological science.