Non-Equivalent Substitution-Engineered Bistable Traps in Mg2GeO4:Bi3+,Ln3+ Persistent Phosphors for Non-Volatile Information Storage

Persistent luminescence (PersL) materials hold immense potential for information storage and anti-counterfeiting applications. However, realizing non-volatile optical memory remains challenging. Herein, we design Mg 2 GeO 4 :Bi 3+ ,Ln 3+ (Ln = Tb, Eu) PersL phosphors via non-equivalent substitution engineering, where Bi 3+ and Ln 3+ ions deliberately occupy non-equivalent Mg1/Mg2 sites to create bistable deep traps. This strategy generates an ultra-broadband, high-density trap distribution, enabling strong photo/thermo-stimulated luminescence for recalling excitation-field temperatures. The trapped carriers exhibit temperature-dependent storage and release dynamics, allowing reconstruction of excitation thermal histories. Based on this unique behavior, reconfigurable optical memory anti-counterfeiting patterns in phosphor films are demonstrated. The trapping mechanism, validated by thermoluminescence and XPS spectra, reveals that carrier redistribution follows Fermi-Dirac statistics governed by the interaction between trap levels and thermal lattice waves. This work opens new avenues for non-volatile optical data storage with high security and spatiotemporal resolution.