Scintillation Performance of Mn(II)‐Doped Cs2NaBiCl6 Double Perovskite Nanocrystals for X‐Ray Imaging Applications

Abstract Lead‐free halide perovskite‐based X‐ray scintillators with high light yield (LY) and low detection limit (LOD) have become a growing subject of research interest due to their promising application in a wide range of areas, from security to healthcare. Herein, a modified hot injection method is employed to synthesize Mn(II)‐doped Cs 2 NaBiCl 6 double perovskite nanocrystals (DPNCs) and to examine their scintillating properties for application in X‐ray imaging and detection. The Mn(II)‐doped Cs 2 NaBiCl 6 DPNCs exhibit a broad orange photoluminescence (PL) band at 586 nm with a PL quantum yield of 10.6%, attributed to the 4 T 2g (4G) → 6 A 1g (6S) transition of Mn 2+ . Temperature‐dependent PL and time‐resolved PL spectra of 4.04% Mn(II)‐doped Cs 2 NaBiCl 6 demonstrate that the orange emission intensity initially reaches a maximum and subsequently decreases, while the decay lifetimes monotonically decrease with increasing temperature. This inconsistency can be due to the effect of the [MnCl 6 ] 4− octahedra and electron‐phonon coupling at elevated temperatures. Further, 0.05 mm thick Cs 2 NaBiCl 6 :4.04%Mn@poly(methyl methacrylate) scintillator film is synthesized with an LY of 28,350 photons MeV −1 and a LOD of 45.2 nGy air s −1 . Additionally, this film demonstrates good X‐ray imaging performance with a spatial resolution of 14.76 line pairs (lp) mm −1 and shows exceptional stability under prolonged X‐ray exposure.