Lanthanide-doped semiconductor nanocrystals: electronic structures and optical properties

Trivalent lanthanide (Ln(3+)) ions doped semiconductor nanomaterials have recently attracted considerable attention owing to their distinct optical properties and their important applications in diverse fields such as optoelectronic devices, flat plane displays and luminescent biolabels. This review provides a comprehensive survey of the latest advances in the synthesis, electronic structures and optical spectra of Ln(3+) ions in wide band-gap semiconductor nanocrystals (SNCs). In particular, we highlight the general wet-chemical strategies to introduce Ln(3+) ions into host lattices, the local environments as well as the sensitization mechanism of Ln(3+) in SNCs. The energy levels and crystal-field parameters of Ln(3+) in various SNCs determined from energy-level-fitting are summarized, which is of vital importance to understanding the optical properties of Ln(3+) ions in SNCs. Finally, some future prospects and challenges in this rapidly growing field are also proposed.