Jennifer Gellert won the SCTE2014 Poster Award at the 19th International Conference on Solid Compounds of Transition Elements in Genoa/Italy, the poster is titled “Luminescence of Yb2+ and Tm2+ doped in Alkaline Earth Sulfides MS (M = Ca, Sr, Ba)”.
She reported about recent results of her Ph.D. thesis concerning the luminescence behavior of different divalent lanthanides. Up to now, the luminescence in sulfides has been sparingly reported in literature. These materials are especially important in order to develop novel red emitting functional materials for future LEDs.
For that reason she attempted to investigate the luminescence of Yb2+ and Tm2+ in several sulfide-based host lattices. Whereas 5d-4f transitions of Yb2+ are general localized in the red range, those of Tm2+ are shifted to the NIR range. Beside practical aspects, the luminescence of Yb2+ and Tm2+ is also interesting from a basic point of view due to the appearance of both, high-spin state and low-spin state emissions. The nature of the respective emissive states and the mechanism of their mutual phonon-assisted population are still by far not clarified. For the further investigation of these processes, temperature-dependent luminescence measurements, investigations of the decay times and detailed interpretations of the excitation spectra were performed.