Elastic Molecular‐Assisted Fabrication of Orthorhombic Non‐Perovskite CsPbI₂Br for Ultralow Dark Current in Advanced X‐Ray Imaging

Abstract In the pursuit of low‐dose flat‐panel X‐ray detection and imaging, controlling dark current is pivotal. Modulating the bandgap and resistivity of photosensitive materials is one of the methods to reduce dark current. The study introduces a novel approach by first demonstrating a non‐perovskite orthorhombic phase δ‐CsPbI₂Br thick film, fabricated using an innovative elastic molecular‐assisted coating strategy. This technique results in a material with an optimized bandgap of 2.30 eV and a significantly elevated resistivity of 2.42 × 10¹⁰ Ω cm. Consequently, this leads to an ultralow dark current of 1.34 nA cm⁻². Leveraging this advancement, the developed X‐ray detectors showcase a groundbreaking low detection limit of 53 nGy_air s⁻¹, surpassing the performance of their cubic‐phase counterparts. Remarkably, the material exhibits excellent phase stability, maintaining its properties for up to 80 days. By integrating with a thin‐film transistor array, a flat‐panel X‐ray detector that delivers high‐quality 8‐bit imaging across a 64 × 64 matrix is successfully engineered. This work not only presents a transformative approach to substantially reduce dark current in low‐dose X‐ray detection but also sets a new benchmark in the field by combining enhanced imaging capability with robust long‐term stability.