Zero-Dimensional perovskite-like Cs2CoCl4 crystal for highly sensitive X-ray direct detection and imaging

Lead-free perovskites have recently attracted huge interest in direct-type radiation detectors. In this work, a zero-dimensional perovskite-like halide Cs 2 CoCl 4 is prepared by an all-water solvent method that enables large-area production for X-ray imaging. The outstanding radiation detection performance of Cs 2 CoCl 4 is demonstrated by a single crystal device. Specifically, the X-ray detector based on Cs 2 CoCl 4 single crystal has a large carrier mobility-lifetime ( μτ ) product of 1.63 × 10 −4 cm 2 V −1 under X-ray irradiation, a sensitivity of up to 2421 μC Gy air −1 cm −2 at 287.8 V mm −1 , and it could detect X-ray as low as 54.3 nGy air s −1 . In addition, Cs 2 CoCl 4 @fiber composite films prepared by aqueous solution evaporation are used to confirm the feasibility of X-ray imaging application. The uniformity of composite films is achieved by adjusting pressure and concentration to control homogeneous nucleation and growth. Excitingly, a switching test lasting more than 300 min at a dose rate of 1169 μGy air s −1 indicates that Cs 2 CoCl 4 @fiber has excellent radiation stability. As a proof of concept, a 5 × 5 pixelated detector array is prepared to achieve a clearly observed outline of the imaged object, offering an inspiring material design strategy conducive to realizing environmentally friendly film devices.