Rare-earth activated luminescence in metal dioxide nanocrystals: the role of aliovalent doping on the structure-property relationship

Abstract

Luminescent materials play a significant role in our contemporary societies. For that purpose, oxides nano-phosphors were developed as stable and efficient hosts for rare-earth luminescence activator dopants. With the advancement of nanotechnologies, new research into the photophysics of rare-earth doped nanomaterials has sparked interest in developing new deposition and processing methods, and in extending their potential use in bioimaging or innovative therapies. Doping metal oxides like HfO2 or ZrO2 with rare-earth ions induces luminescence activation and profound structural perturbations. However, the concentration of optically active dopants is critical in determining the luminescence obtained from these materials, and in parallel, the structural properties of the material might influence the luminescence. Thus, in such oxidebased nanoparticle systems, it is essential to differentiate between the structural modifications caused by the dopants from their influence on the optical properties. It is necessary to assess how structural modifications impact the luminescence of the emitting centres. Furthermore, suitable strategies for decoupling the structural features from dopant concentration are explored here. These investigations enable us to explain and take advantage of compositional modifications to optimise and design the luminescence of the nanoparticles, as well as to probe the structure and dopant distribution in the nanoparticles, thanks to optical measurements.