A new insight into the mechanism of persistent luminescence phosphors SrS: Eu2+, Pr3+

The red persistent luminescence phosphors SrS: Eux2+, Pry3+ (x = 0∼0.001, y = 0∼0.003) were synthesized by the solid-state reaction method in a weak reducing atmosphere of active carbon. The synthetic parameters, photoluminescence characteristics, and dynamic properties of thermoluminescence of the phosphors were studied systematically. According to the results of photoluminescence spectra of SrS: Eux2+, Pry3+, the energy level scheme of the phosphors was confirmed quantitatively. Based on the studies of the scanning electron microscope (SEM), UV-Visible absorbance spectra, afterglow decay curves, thermoluminescence(TL) spectra, and X-ray photoelectron spectroscopy (XPS) spectra, we found that the SrS: Eu0.00012+, Pr0.0033+ (SSEP) phosphor presented the best persistent luminescence property, which mainly resulted from its outstanding absorbance characteristic, deeper depth of VS⋅ (VS⋅⋅) defects, and fewer defect concentration belonging to the higher-order kinetics. Those comprehensive results deduced that a complex defect VS⋅ (VS⋅⋅)-V′′Sr should present in the Eu2+ doping phosphors, and the Pr3+ doping will produce PrSr⋅ defects, which can suppress the formation of VS⋅ (VS⋅⋅) defects and increase their energy depth.