High‐Sensitivity Self‐Powered X‐Ray Detectors Based on Chiral Bismuth Perovskites

ABSTRACT Lead‐free perovskites are emerging as eco‐friendly alternatives for X‐ray detection, yet achieving high sensitivity, stability, and self‐powered operation remains a challenge. Here, we present a 0D chiral organic‐inorganic hybrid bismuth perovskite single crystal, (R/S‐NEA) 4 Bi 2 Cl 10 (NEA = (2‐naphthyl)ethylamine), that enables a bulk photovoltaic effect (BPVE) for efficient, self‐powered X‐ray detection. Its unique structure, featuring isolated [Bi 2 Cl 10 ]4 − dimers within a hydrogen‐bonded chiral lattice, facilitates asymmetric charge transport, enhancing intrinsic carrier separation. The resulting detector achieves a record sensitivity of 10 200 µC·Gy −1 cm −2 at 1000 V bias and maintains self‐powered operation (0 V) with a low detection limit of 510 nGy s −1 , outperforming existing bismuth‐based perovskite detectors. Notably, these crystals retain structural integrity for over a year in ambient conditions, while the device exhibits stable operation for over 4000 s under continuous X‐ray exposure. This work advances chiral perovskite engineering as a powerful strategy for developing next‐generation lead‐free X‐ray detectors with high performance and long‐term durability, making them attractive for portable medical imaging and radiation monitoring.