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

Abstract

Lead-free perovskites have recently attracted huge interest in direct-type radiation detectors. In this work, a zero-dimensional perovskite-like halide Cs₂CoCl₄ is prepared by an all-water solvent method that enables large-area production for X-ray imaging. The outstanding radiation detection performance of Cs₂CoCl₄ is demonstrated by a single crystal device. Specifically, the X-ray detector based on Cs₂CoCl₄ single crystal has a large carrier mobility-lifetime (μτ) product of 1.63 × 10⁻⁴ cm² V⁻¹ under X-ray irradiation, a sensitivity of up to 2421 μC Gy_air⁻¹cm⁻² at 287.8 V mm⁻¹, and it could detect X-ray as low as 54.3 nGy_air s⁻¹. In addition, Cs₂CoCl₄@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 Cs₂CoCl₄@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.