Mn2+-doped Cs2ZnBr4 scintillator for X-ray imaging

Abstract

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 μGy_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.