Optical spectroscopy of lanthanides doped in wide band-gap semiconductor nanocrystals

Currently, tripositive lanthanide (Ln3+) ions doped wide band-gap semiconductor nanocrystals (NCs) have been the focus of research interest due to their distinct optical properties and potential applications in optical devices and luminescent biolabels. Because of the low absorptions of parity-forbidden 4f–4f transitions for Ln3+, it is highly anticipated that the luminescence of Ln3+ ions embedded in wide band-gap NC lattices can be sensitized efficiently via exciton recombination in the host. For this purpose, the successful incorporation of Ln3+ into the lattices of semiconductor NCs is of utmost importance, which still remains intractable via conventional wet chemical methods. Here, the most recent progress in the optical spectroscopy of Ln3+ ions doped wide band-gap semiconductor NCs is discussed. Much attention was focused on the optical properties including electronic structures, luminescence dynamics, energy transfer as well as the up-conversion emissions of Ln3+ ions in ZnO, TiO2, SnO2 and In2O3 NCs that were synthesized in our laboratory using wet chemical methods.