2‐Bromonaphthalene‐Induced Defect Passivation to Suppress Ion Migration in CsPbBr ₃ Wafer for X‐Ray Detector with Bias‐Resistant Stability

Abstract Featuring exceptional photoelectronic properties and scalability, hot‐pressing processed all‐inorganic (i. e., CsPbBr ₃ ) perovskite wafers have emerged as promising candidates for direct X‐ray imaging. Nonetheless, severe ion migration in CsPbBr ₃ wafers results in a large and drifting dark current, thereby compromising the bias‐resistant stability of the X‐ray detector. Herein, a solvent‐free interfacial defect passivation strategy is proposed by introducing a passivator molecule, 2‐bromonaphthalene, to passivate interfacial defects and suppress ion migration in CsPbBr ₃ wafers. Implementing this strategy effectively inhibits ion migration in CsPbBr ₃ wafers, as evidenced by an enhanced ion migration activation energy of 0.56 eV and a negligible dark‐current drift of 4.01 × 10 ⁻⁸ µA cm ⁻¹ s ⁻¹ V ⁻¹ , representing a 100 fold reduction in dark current drift compared to untreated CsPbBr ₃ wafers under a high electric field of 100 V mm ⁻¹ , indicating a high bias‐resistant stability. Consequently, the CsPbBr ₃ wafer X‐ray detector achieves an impressively high sensitivity of 11090 µC Gy _air ⁻¹ cm ⁻² , a low detection limit of 9.41 nGy _air s ⁻¹ under a 100 V mm ⁻¹ electric field, and high‐contrast X‐ray imaging capabilities, with performance comparable to that of CsPbBr ₃ single‐crystal‐based X‐ray detector, highlighting the potential of interfacial defect passivation strategy for high‐performance X‐ray detectors.