Mn2+‐Activated Cs3Cu2I5 Nano‐Scintillators for Ultra‐High Resolution Flexible X‐Ray Imaging

Abstract Zero‐dimensional (0D) copper‐based perovskite‐derivative nano‐scintillators (NSs), as a promising non‐toxic alternative to lead‐based halide perovskite, have shown great potential in flexible X‐ray detection and imaging. However, their practical applications are still impeded by low X‐ray imaging resolution associated with inadequate radioluminescence (RL) and poor environmental stability. Herein, for the first time a simple but valid Mn 2+ ‐activation strategy is proposed to highly enhance the RL and stability of 0D Cs 3 Cu 2 I 5 NSs, where the Mn 2+ ions are embedded into the highly localized [Cu 2 I 5 ] 3− units by utilizing a modified hot‐injection method. As such, a newly emerged emission band of Mn 2+ ion centered at ≈562 nm coupled with much improved intrinsic self‐trapped excitons (STE) emission of the 0D Cs 3 Cu 2 I 5 host peaking at ≈445 nm can be achieved in these resultant Mn 2+ ‐activated 0D Cs 3 Cu 2 I 5 NSs, thereby delivering a light yield of 71 000 photons MeV −1 that is much superior to their lead‐based perovskite counterparts and commercial scintillators. As a consequence, X‐ray detectors made of these Mn 2+ ‐activated NSs implement an ultrahigh X‐ray imaging resolution of 16.2 line pairs mm −1 and an ultra‐low detection limit of 127.5 nGy air s −1 , highlighting their potential as promising candidates for flexible X‐ray detection and imaging.