Persistent Luminescence in Non-Eu-Doped Compounds: A Review.

During the past few decades, the research on persistent luminescent materials has focused mainly on Eu-doped compounds. However, the yearly number of publications on non-Eu-based materials has also increased steadily. By now, the number of known persistent phosphors has increased to over 200, of which over 80% are not based on Eu, but rather, on intrinsic host defects, transition metals (manganese, chromium, copper, .) or trivalent rare earths (cerium, terbium, dysprosium, .). In this review, we present an overview of these non-Eu-based persistent luminescent materials and their afterglow properties. We also take a closer look at some remaining challenges, such as the excitability with visible light and the possibility of energy transfer between multiple luminescent centers. Finally, we summarize the necessary elements for a complete description of a persistent luminescent material, in order to allow a more objective comparison of these phosphors.