Regulating the trap distribution of ZnGa2O4:Cr3+ by Li+/Ga3+ doping for upconversion-like trap energy transfer NIR persistent luminescence

Doping Li + /Ga 3+ in ZnGa 2 O 4 :Cr 3+ splits the energy level of electron traps into shallow traps and deep traps, which makes the developed phosphors be successfully excited by a low-energy NIR light and suitable for long-term biological imaging.