Dual-phase CsPbBr3–CsPb2Br5 perovskite scintillator for sensitive X-ray detection and imaging

Cesium lead bromide and its derivatives have recently attracted the scientific community for X-ray detection and imaging due to their effective atomic number, strong scintillating luminescence, fast scintillating decay time, and tunable optical bandgap, despite their poor stability against ultraviolet (UV) illumination, moisture, and thermal degradation. Here, we report the synthesis of a highly luminescent and stable dual-phase CsPbBr3–CsPb2Br5 perovskite nanocrystal (PNCs) system prepared using the hot-injection method for scintillation application. CsPb2Br5 developed on the surface of the CsPbBr3 reduces the surface defect density and greatly enhances the photostability, water resistance, thermal stability, and luminescence properties of the CsPbBr3 nanocrystals. Based on the excellent stability of PNCs in various environments, we mixed the PNCs with polystyrene (PS) and spin-coated the glass plate to evaluate the optical and scintillation properties. The dual-phase CsPbBr3–CsPb2Br5 exhibits a strong green emission at 522 nm with a photoluminescence quantum yield of 65.2% and a fast response time of 2.93 ns under UV excitation. Under X-ray irradiation, CsPbBr3–CsPb2Br5 PNCs exhibited excellent linear response as a function of the dose rate at 50 keV and a low detection limit of 1.130 μGyair s−1, which is less than the typical medical imaging dose (5.5 μGyair s−1) and a light yield of 19,200 photons/MeV. Moreover, the CsPbBr3–CsPb2Br5 scintillating film displays excellent imaging ability with a spatial resolution of up to 8.19 lp/mm at a modulation transfer function (MTF) of 0.2 under an exposure dose of 46.96 μGyair s−1. These findings show that the dual-phase CsPbBr3–CsPb2Br5 structure can be a promising fast scintillating material for X-ray imaging in medical and industrial applications.