Investigation of energy transfer mechanisms in rare-earth doped amorphous silica films embedded with tin oxide nanocrystals.

Three different types of rare earth (RE3+) ions-doped silica thin films are fabricated by a soft chemistry-based method. By introducing tin oxide (SnO2) nanocrystals with larger cross-sections as sensitizers, the characteristic emission intensity of RE3+ ions in amorphous silica thin films can be enhanced by more than two orders of magnitude via the energy transfer process. The possible energy transfer processes under different local environment are revealed by using Eu3+ ions as an optical probe. Quantitative studies of PL decay lifetime and temperature-dependence PL spectra suggest that the partial incorporation of RE3+ ions into SnO2 sites gives rises to the change of crystal-field symmetry and the significant enhancement of energy transfer efficiency. Further, typical analytical energy dispersive X-ray spectroscopy (EDS) mapping results prove that part of Eu3+ ions doped into the SnO2 sites after annealing at 1000 °C. We anticipate that our results would shed light on the future research on the energy transfer mechanisms under different local structures of RE3+ ions.