Darkness-Penetrating NIR Afterglow from Cr3+-Doped Phosphors for Remote Target Surveillance

Achieving excitation-free, long-range target surveillance under complete darkness remains a critical challenge for night-vision technology. Here, a breakthrough is reported in near-infrared (NIR) persistent luminescence (PersL) materials designed specifically for this frontier. Through strategic bandgap engineering via Sm 3 ⁺ co-doping and In 3 ⁺ solid-solution incorporation in the novel Cr 3 ⁺-doped Mg 3 Ga 1.9 In 0.1 SnO 8 spinel phosphor, the afterglow intensity and duration are dramatically enhanced. The optimized material exhibits an ultra-long NIR PersL exceeding 168 h. Crucially, PDMS films embedded with this phosphor enabled real-time, persistent target detection at an unprecedented distance of 47.5 m in complete darkness, entirely without any external excitation source. This record-setting long-range performance demonstrates the material's potential as an enabling technology for passive, long-range nighttime surveillance systems. Comprehensive spectroscopic studies elucidate the underlying PersL mechanism. This work establishes a new pathway for designing ultra-long NIR PersL materials and paves the way for advanced applications in remote night-vision technologies.