Synthesis of Upconverting Nanomaterials: Designing the Composition and Nanostructure

Lanthanide-doped upconverting nanostructures are promising materials for modern biomedical imaging applications, in particular in optical diagnostics. Upconversion is a phenomenon involving optical emission at higher energies than that of the exciting radiation, through sequential absorptions of photons. Lanthanide ions are particularly useful for this process, due to their peculiar energy levels scheme and relatively long-excited states lifetimes. In the past decades, many hosts and types of lanthanide ions have been chosen to customize the luminescence properties of the nanosystems, tailoring also their structure to fit efficiently the final application. The target of this chapter is to illustrate the different synthesis of upconverting nanomaterials, with particular attention to the composition of the host and to the architecture of the nanostructures.