Hydroxymethylated EDOT/ProDOT Copolymer-Ratio Regulation of Hole-Transport Pathways Coupled with BiOIO3 Polar-Interphase Engineering for Flexible Self-Powered UV Photodetectors

Key requirements for flexible self-powered UV detectors include efficient photoinduced charge separation, unimpeded carrier transport, and strong mechanical endurance. Here, a flexible photovoltaic UV detector is developed by synergistically regulating a hydroxymethylated copolymer-derived p-type layer and a BiOIO3 interfacial layer on ZnO NFs. P(EDOT-CH2OH-co-ProDOT-2CH2OH) is prepared by electrochemical copolymerization as the hole-transport layer, where hydroxymethyl groups improve surface polarity and interfacial affinity, while ProDOT units enhance film flexibility. Meanwhile, BiOIO3 modification regulates ZnO surface defects, modulates the local polarization environment, and promotes charge separation at the heterojunction. The combined regulation improves interfacial contact, band coupling, and carrier transport pathways, enabling stable photoresponse under bending. With an EDOT-CH2OH/ProDOT-2CH2OH ratio of 2:1, the device achieves a photocurrent of 214 nA, a responsivity of 2.96 mA W-1, a detectivity of 3.06 × 1010 Jones, and maintains about 50 nA after 150° bending and 2000 bending cycles. This work demonstrates an interfacial chemical engineering strategy for constructing mechanically durable, energy-autonomous UV sensing materials by coupling copolymer molecular design with defect and polarization regulation in inorganic heterostructures.