Wide‐Bandgap Rare‐Earth Iodate Single Crystals for Superior X‐Ray Detection and Imaging

Semiconductor‐based X‐ray detectors with low detectable thresholds become critical in medical radiography applications. However, their performance is generally limited by intrinsic defects or unresolved issues of materials, and developing a novel scintillation semiconductor for low‐dose X‐ray detection is a highly urgent objective. Herein, a high‐quality rare‐earth iodate Tm(IO(3))(3) single crystal grown through low‐cost solution processing is reported with a wide bandgap of 4.1 eV and a large atomic number of 53.2. The roles of I—O and Tm—O groups for charge transport in the Tm(IO(3))(3) are revealed with the structural difference between the [101] and [Formula: see text] crystal orientations. Based on anisotropic responses of material properties and detection performances, it is found that the [[Formula: see text]] orientation, the path with fewer I—O groups, achieves a high resistivity of 1.02 × 10(11) Ω cm. Consequently, a single‐crystal detector exhibits a low dark current and small baseline drifting due to the wide bandgap, high resistivity and less ion migration of Tm(IO(3))(3), resulting in a low detection limit of 85.2 nGy(air) s(−1). An excellent X‐ray imaging performance with a high sensitivity of 4406.6 µC Gy(air) (−1) cm(−2) is also shown in the Tm(IO(3))(3) device. These findings provide a new material design perspective for high‐performance X‐ray imaging applications.