Supramolecular bismuth halide frameworks for monolithic X-ray CMOS imagers

Low-dimensional, lead-free bismuth halides are promising for next-generation X-ray detectors but are limited by structural disorder and poor charge transport. We introduce a supramolecular engineering strategy to fabricate highly oriented, quasi-single-crystalline APDBiI 5 films using hydrogen-bond-directed self-assembly of 3-aminopyrrolidine (APD 2+ ) cations with [Bi 2 I 10 ] 4- clusters. This strategy enables scalable ultrasonic spray coating of large-area, thick films with exceptional uniformity. The hydrogen-bonding network lowers the surface energy of (hh0) planes, promoting oriented attachment and long-range order, which establishes a periodic potential for coherent charge transport and minimized phonon scattering. The resulting films achieve a hole mobility of 15.8 cm 2 V -1 s -1 , a trap density of 4.01×10 13 cm -3 , and a mobility-lifetime product of 1.27×10 -3 cm 2 V -1 . The fabricated X-ray detectors exhibit a sensitivity of 26,080.7 μC Gy air -1 cm -2 , a detection limit of 17.1 nGy air s -1 , and remarkable operational stability. Finally, monolithic integration with a 640×512 CMOS array enables high-resolution, low-dose 3D X-ray imaging.