Boosting Near‐Infrared Persistent Luminescence in Gallate Compounds via Energy‐Trap Engineering for Versatile X‐Ray Application

ABSTRACT Persistent luminescence (PersL) materials, which utilize traps to store excited energy and emit photons over extended periods, have attracted extensive attention in the fields of optical information storage, night‐vision surveillance, biological imaging, etc. However, precisely modulating the formation of defects and the distribution of trapping energy levels remains challenging. Here, an energy‐trap engineering strategy is proposed to construct specific trap states to activate the near‐infrared (NIR) PersL of Fe 3+ , triggering a 600% enhancement of NIR PersL in gallate materials. Structural analyses, spectroscopy measurements, and DFT calculation revealed that neighboring substitution alters the structural symmetry and induces lattice distortion, contributing to the generation of numerous oxygen vacancy defects within the crystal to regulate the PersL properties of Fe 3+ . Additionally, the changed local lattice environment caused by unbalanced substitution lowers the transition barriers by forming trap levels within the bandgap, thereby accelerating carrier transfer and enhancing NIR PersL intensity. Owing to the remarkable X‐ray absorption and conversion capabilities of Fe 3+ ‐doped gallate compounds, multifunctional applications in background‐free optical radiometry and X‐ray imaging are demonstrated. These findings provide a new perspective on the modulation of targeted defects in PersL materials and promote the development of multifunctional X‐ray luminescent materials.