Nanocrystalline PbI2 coated on a cellulose fiber frame for paper-based flexible X-ray detection

Abstract

In this work, paper-based flexible X-ray detectors were developed. Outstanding detection performance and high stability were realized by combining the intrinsic flexibility of the PbI₂ nanocrystal, and the bendability of cellulose fiber paper. The devices were prepared using a scalable solution infiltration method and a screen-printing method. The PbI₂ nanocrystal was coating onto the fiber instead of filling the micropore between the fibers. This special microstructure suppresses the effect of the carrier lateral diffusion by restricting the transport of the photoexcited carriers along the longitudinal direction of fibers, which promotes carrier transport, and improves photodetection performance. All of the pixels showed a high consistency of sensitivity, and a high signal-to-noise ratio, which ranged from 76.7 to 78.3 μC Gy⁻¹ cm⁻², and 296.4 to 327.3, respectively. In addition, benefitting from the unfilled micropores which serve as a stress buffer zone, the devices reveal high flexibility when the composite structure is in tension or compression. After 1000 bending cycles, no cracks were found in the nanocrystalline layer on the fibers, and the photocurrent was maintained at over 87%. In addition, a linear array X-ray imager was successfully implemented using the as-fabricated devices.