Hydrogen-bond engineered supramolecular bismuth halides for flexible X-ray imaging without geometric distortion
Flexible X-ray detectors are constrained by the difficulty of producing semiconductor films that simultaneously exhibit uniform morphology, high crystallinity, and mechanical robustness. Here, we introduce a hydrogen-bond engineered supramolecular (HBES) strategy to overcome these limitations in supramolecular bismuth halide clusters (PDBiI5). By incorporating polyacrylic acid (PAA), a dynamic supramolecular network is formed that suppresses the coffee-ring effect during ultrasonic spray-coating via increased solution viscosity and controlled kinetic balance between solvent evaporation and solute diffusion. The HBES approach also modulates crystallization kinetics, extending crystal growth time from 23 to 41 s, yielding densely packed films with enhanced crystallinity and reduced defect states. These improvements lead to superior charge transport: a hole mobility of 2.16 cm2 V−1 s−1 and a mobility-lifetime product of 9.1 × 10−4 cm2 V−1. The resulting X-ray detectors achieve a record sensitivity of 19,009 μC Gyair−1 cm−2 and an ultralow detection limit of 3.35 nGyair s−1, with excellent operational and environmental stability. Leveraging the mechanical robustness from the supramolecular network, we demonstrate the first direct-type flexible X-ray imager, retaining 85% performance after 1000 bending cycles. This imager overcomes geometric distortion and vignetting, maintaining 85% edge photocurrent versus 58% for rigid detectors, enabling clear imaging of curved objects. This work establishes a versatile supramolecular engineering paradigm for high-performance flexible X-ray detection and imaging.