 1996 study by Matsuzawa et al. reported extremely long-lasting afterglow of senior al-204-EU-2 plus codeped with di-3 plus ions, which was more than 10 times brighter than ZNS-CU company. Since then, research for stable and efficient persistent phosphors has gained popularity but the number of such materials is still relatively low and the mechanism behind this phenomenon is unclear. This review presents an overview of important classes of known persistent luminescent materials based on EU-2 plus emission and their preparation, as well as models and mechanisms suggested to explain bright afterglow in various compounds. This article was authored by Kuhn van den Eekhout, Philippe F. Smet and Dirk Pellmann.