Ion Migration Suppression via Doping Multivalent Cations in Perovskite for High Thermal Stability X‑ray Detectors

CsPb2Br5 single crystals (SCs) are promising for X-ray detection due to their high absorption, excellent photoelectric properties, and stability. However, thermal stress in high-temperature environments accelerates ion migration within perovskite structures, leading to degraded performance. In this study, we investigate the effects of Cr3+ doping, which induces lattice contraction and distortion due to its small ionic radius and strong electrophilic properties. This increases the formation energy of Br vacancies and activation energy for ion migration, enhancing the crystal’s resistance to thermal stress. As a result, Cr-doped CsPb2Br5 exhibits a high μτ value of 5.46 × 10–3 cm2 V–1, a lower temperature coefficient of resistance (−1.58 × 10–2 °C–1), and excellent ion migration resistance at 70 °C. These improvements lead to a high sensitivity of 7183.5 μC Gyair–1 cm–2 and a low detection dose rate of 11.5 nGyair s–1, with stable performance in X-ray imaging at elevated temperatures, making it suitable for complex environments.