Near infrared long-persistent phosphorescence in SrAl2O4:Eu2+,Dy3+,Er3+ phosphors based on persistent energy transfer

Eu 2 + , Dy3+, and Er3+ ions codoped SrAl2O4 phosphors with near infrared (NIR) (at 1530 nm) long-persistent phosphorescence were synthesized by a combustion method. The NIR phosphorescence emission was realized through a persistent energy transfer process from Eu2+ ions to Er3+ ions. Optimal Er3+ concentration for the maximum energy transfer efficiency was determined and NIR phosphorescence persisting for more than 10 min was achieved. A model of charge trapping and energy transfer process among Eu, Dy, and Er ions in SrAl2O4 host was proposed.