Ultra‐Flexible Perovskite Nanowire Network Photodetectors for Wearable Health Monitoring and Weak Light Imaging

ABSTRACT Compared with single perovskite nanowires or arrays, perovskite nanowire networks (PNWNs) have greater application potential in large‐area and array integration due to their unique morphology and simpler fabrication. However, surface defects and poor bending capacity from cross‑stacking severely limit performance, stability, and flexibility. Here, 3, 4‐difluorophenylamine chloride (34F2PMACl) is employed to passivate the surface defects and form quasi‐2D perovskite (n = 2) adhesive layers on the surface and micro‐interface of the NWs, improving carrier transport and stress release during bending. The resulting flexible self‐powered PNWN photodetectors (PDs) exhibit a low weak‐light detection limit (110 pW cm −2 ), large linear dynamic range (216 dB), high responsivity (4.79 A W −1 ), and high detectivity (6.23 × 10 13 Jones), respectively, representing one of the highest performances of carbon‐based flexible perovskite PDs reported to date. Moreover, the flexible device demonstrates performance attenuation of less than 5% after 35 000 and 25 000 bending cycles at the bending radius of 8.5 and 4 mm, respectively, surpassing all flexible perovskite PDs reported so far. Furthermore, the large‐area (1 cm 2 ) flexible device enables wearable heart‑rate monitoring via photoplethysmography under 28.4 µW cm − 2 weak light. Finally, the flexible device array (6 × 6) achieves real‑time self‑powered weak‑light imaging at 370 nW cm − 2 , demonstrating great potential for image sensing.