Thermoluminescence investigation on Y3Al5−xGaxO12:Ce3+-Bi3+ green persistent phosphors

We report bright green persistent phosphors of Ce3+, Bi3+ codoped Y3Al5−xGaxO12 (YAGG:Ce3+-Bi3+, x from 0 to 4) due to 5d→4f transition of Ce3+ after blue excitation, in which Bi3+ related defects work as efficient electron traps. The trap depths, which can be tunable by changing Ga3+ content, x from 0.31 to 1.07 eV, were estimated by initial rise method based on thermoluminescence (TL) glow curve results. Vacuum referred binding energy (VRBE) diagrams of YAGG:Ce3+-Bi3+ phosphors including energy levels of CB and electron trapped trivalent Bi states, Bi3++e− or Bi2+ were constructed to explain the mechanism of persistent luminescence.