Yellow-green luminescence and extreme thermal quenching in the Sr6M2Al4O15:Eu2+ (M = Y, Lu, Sc) phosphor series

A series of Eu2+-substituted yellow-green emitting phosphors based on the compound, Sr6M2Al4O15 (M = Y, Lu, Sc) were identified as potential efficient phosphors based on their high calculated Debye temperatures (Theta(D) > 450 K), which acts as a proxy for photoluminescent quantum yield (PLQY). The crystal structure contains corner-sharing [MO6] octahedra and [AlO4] tetrahedra leading to a highly connected, densely packed crystal structure. However, contrary to prediction, these "compounds all showed a low PLQY (<6.5%) at room temperature. Temperature dependent luminescence measurements indicate that the photoluminescence is intense at 80 K but loses approximate to 90% of the emission intensity by room temperature, with the thermal quenching temperature (T-50) occurring well below room temperature. These results suggest that even though Debye temperature (Theta(D)) is a valid proxy for PLQY, it does not describe thermal quenching. (C) 2016 Elsevier Masson SAS. All rights reserved.