Multimodal Deep Red/NIR Luminescence From LiGaO 2 :Ti via Mixed‐Valence State and Intrinsic Trap Interaction

ABSTRACT Multimodal luminescent materials have attracted widespread attention across a wide range of application fields. However, designing multimodal luminescence phosphors capable of exhibiting exceptional stability and intensity under irradiation conditions beyond the conventional wavelength range, particularly by achieving this through the precise transformation of material defects, remains a challenging task. Herein, we report a new class of titanium‐doped LiGaO 2 (LGOT) phosphors exhibiting unique multimodal deep red and near‐infrared (NIR) multimodal photoluminescence (PL) and PersL under UV and X‐ray excitations. Our characterization and analysis demonstrate that Ti exhibits mixed valence states, which establish efficient internal charge transfer (CT) and electron capture by intrinsic trapping, such as oxygen vacancies ( V O ) and interstitial oxygens (O i ), leading to Ti 3 + ‐centered radiative relaxation by the formation of Ti 3 + ‐containing defect complexes, to stimulate the deep red/NIR emission. The afterglow of the LGO:1.0%Ti phosphor gives a long average lifetime at NIR emission upon multimodal excitation, with X‐ray excitation (τ = 112.7 s) providing a lifetime 72% longer than UV excitation (τ = 65.5 s). The unique multimodal luminescence characteristics exhibited by these LGOT phosphors not only offer new mechanistic insights but also establish a promising platform for developing advanced phosphors that integrate multiple luminescence modes, thereby laying the foundation for future applications.