Mn²⁺-doped Cs₂ZnBr₄ scintillator for X-ray imaging

Luminescent metal halides with a high photoluminescence quantum yield (PLQY), large Stokes shift and strong X-ray absorption capability have demonstrated prospects in high-energy radiation detection. Here, we report Mn2+-doped all-inorganic metal halide Cs2ZnBr4 as an X-ray imaging scintillator. The as-prepared Cs2ZnBr4:Mn2+ shows two emission bands peaking at 526 and 655 nm, respectively, with a PLQY of up to 58.8%. It is found that the dual emissions belong to the spin-forbidden d-d transition of Mn2+ ions in different coordination configurations, and the involved luminescence and evolution mechanisms have been analyzed. To investigate the scintillation properties, we successfully fabricated a homogeneous thin film scintillation screen containing Cs2ZnBr4:25%Mn2+, which shows good X-ray scintillation performance with a light yield of about 15 600 photons per MeV and a low detection limit of 1.16 mu Gy(air) s(-1). Moreover, the flexible and large-area scintillation screens exhibit good X-ray imaging performance with a spatial resolution of 5.06 lp mm(-1) and excellent stability under continuous X-ray irradiation.