A strategy for developing near infrared long-persistent phosphors: taking MAlO3:Mn4+,Ge4+ (M = La, Gd) as an example

A wide variety of activation ions have been used as near infrared (NIR) luminescent centres. However, when it comes to persistent luminescence, the numbers of known activators are relatively low. Here, we propose a holistic design concept for NIR long persistent phosphors, and successfully fabricate a series of novel Mn4+-doped MAlO3 (M = La, Gd) persistent phosphors with the emission maximum around 730 nm. By drilling down into the details of defect types and trap depths, an improvement of persistent time over 20 h is realized by co-doping Ge4+/Mn4+. The obtained imaging of deep tissues reveals that the new luminescent indicators will open the possibility of advanced optical imaging, with high resolution and weak light disturbance, for factual assessment of the structural and functional processes in cells, tissue and other complex systems.