Unveiling the Role of Cesium in Halide Perovskite Single Crystal for Stable and Ultrasensitive X-Ray Detection

Abstract

Metal halide perovskites have been demonstrated to be the promising X-ray detection materials, among which MAPbI₃ is expected for high-performance large-area X-ray detector integration due to its strong X-ray absorption and solution processible at low temperature for industrial-grade large-size single crystal (SC). However, the commercial viability of MAPbI₃ SC X-ray detectors remains challenging due to its poor intrinsic stability, large dark current, and significant ion migration. Herein, inorganic Cs⁺ ions are designed to incorporate into the MAPbI₃ SC and the effects of Cs⁺ on crystal structure, defect state, band structure, ion migration, and carrier transport in the SCs are systematically unveiled. The experimental results show that the incorporation of Cs⁺ ion reduces defect density, inhibits ion migration, improves carrier mobility, and increases resistivity. Therefore, detectors fabricated on the SC with Cs⁺ ions show high detection sensitivity of 49847 µC Gy⁻¹ cm⁻², low detection limit of 3.1 nGy s⁻¹, short response raise time of 150 µs, and superior long-term operating stability under continuous X-ray irradiation and bias. The rare combination of these figure of merits enables the detector to achieve high-definition X-ray imaging, confirming that this work provides a new strategy for designing stable and sensitive X-ray detectors.