Luminescence properties of SrS:Ce3+, Cl thin films

Excitation spectroscopy and photoluminescence investigations have been carried out to evaluate the luminescence properties of SrS:Ce-based thin films. The results are compared with those obtained on efficient powders. The application of a model developed for cathodoluminescence leads to the assumption that the defect density in the thin films is much higher than in powders. These defects act as killers leading to a reduced photoluminescence yield. The nature of the defects is not clearly identified; however, Ce doping-induced Sr vacancies are proposed as possible candidates. As a consequence, Mn co-doping has been applied, leading to a significantly improved PL and EL performance of the luminescent layers. An EL efficacy of 1.8 lm/W at 1-μC/cm 2 transferred charge and 60-Hz driving frequency has been obtained.