Photostimulated near-infrared persistent luminescence Cr3+-doped Zn-Ga-Ge-O phosphor with high QE for optical information storage

Near-infrared (NIR) persistent luminescence (PersL) phosphors, which exhibit unique properties of high signal-to-noise ratio and wide excitation spectral region, have attracted more and more attention in the next-generation high-capacity storage system. In this paper, a multi-spectral excited NIR PersL phosphor, Zn1.25Ga1.5Ge0.25O4: Cr3+ (ZGG: Cr3+) which is developed by doping ZnGa2O4: Cr3+ with tetravalent Ge4+, has been successfully synthesized. Rietveld refinements show that Ge4+ ions enter into octahedral sites by substituting Ga3+ ions and the hetero-valence substitution enriches the charged defects. This PersL phosphor exhibits a zero-phonon lines emission of Cr3+ [2E→4A2g] with the maximum at 698 nm and the maximum values of IQE and EQE can reach to 60.3% and 22.4%, respectively. An intense photostimulated persistent luminescence (PSPL) can be repeatedly obtained by NIR laser stimulation in a period of more than 48 h (write-out) when the ZGG: Cr3+ phosphor illuminated by an ultraviolet-light (UV) (write-in). In addition, adopting thermoluminescence (TL) method, we studied the electron motion in traps and found a specific PersL mechanism which will be reported in this work. All these results demonstrate that the ZGG: Cr3+ phosphor has promising applications in optical information storage.