From Bulk to Nano: The Effect on the Persistent Luminescence

Persistent luminescence materials are compounds able to glow in the dark after proper excitation. After the discovery in the 1990s of the long persistent luminescence in SrAl2O4:Eu2+,Dy3+ lasting 12 hours, the interest in this class of materials has grown quickly. Today, thousands of compounds are known to possess persistent luminescence, and some of them have found real industrial applicability. However, the mechanism driving the persistent luminescence remains somewhat unknown. The scenario is further complicated by moving from bulk materials to nanocrystals. Herein, we give an overview of the most important goals achieved in persistent luminescence materials and a critical perspective on this peculiar phenomenon at the nanoscale.