Novel broadband near-infrared emitting long afterglow phosphor MgGeO3: Cr3+

In this study, we report broadband near-infrared persistent luminescence of a novel MgGeO3: Cr3+ material. The luminescence can be excited by the ultraviolet radiation and detected for more than 16 h. Optical and electron paramagnetic resonance spectroscopy experiments suggest that the observed bands appear as a result of interaction between Cr3+ luminescence centre and oxygen-impurity complexes and oxygen vacancy related trapping states. Thermally stimulated luminescence analysis revealed that the states are closely overlapping and lie relatively deep in the band gap with the activation energy exceeding 0.9 eV. The experimental data strongly suggest that the main detrapping route for the trapped charge carriers in the MgGeO3: Cr3+ material is athermal tunnelling directly to the luminescence centres.