Temperature-dependent persistent luminescence of SrAl2O4:Eu2+, Dy3+, Tb3+: a strategy of optical thermometry avoiding real-time excitation

A new strategy of optical thermometry is realized by long persistent luminescence phosphor SrAl2O4:Eu2+, Dy3+, Tb3+ (SAEDT). Under different temperatures, SAEDT shows bright afterglow emissions after cessation of the UV excitation. The afterglow color of the SAEDT sample is blue at 60 K and gradually changed into green at 240 K. The normalized afterglow spectra at different temperatures give a dramatic change of fluorescence intensity ratio between the blue band and the green band. Not only has this material exhibited a high absolute sensitivity and relative sensitivity for temperature sensing, but it also has the great advantage of eliminating the heating effect due to avoidance of real-time direct excitation.