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

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-CsPbI 2 Br 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.