Flexible piezo-responsive photodetector based on hierarchical zinc oxide nanowire branches on a silver nanowire backbone

Zinc oxide (ZnO) is a highly promising material for ultraviolet (UV) photodetection, owing to its wide bandgap (∼3.34 eV), high exciton binding energy, and cost-effective synthesis. Its piezoelectric properties further enhance its utility in wearable electronics. However, the inherent brittleness of ZnO nanowires (NWs) poses challenges in achieving reliable performance under strain. In this study, a novel flexible piezo-responsive photodetector with enhanced electrical performance is synthesized by hierarchical growth of ZnO NW branches on a silver nanowire (Ag NW) backbone, coupled with a UV laser ablation process for precise patterning. Further, the flexibility and stability are enhanced by the addition of a polydimethylsiloxane (PDMS) layer, thereby enabling consistent operation under stretching of up to 40%. The device integrates UV photodetection and piezoelectric strain sensing into a single platform, thereby addressing the demands for wearable sensors and piezoelectric nanogenerators. This multi-functional sensor demonstrates applications in motion monitoring, real-time UV exposure assessment, and self-powered wearable electronics, and establishes a robust framework for flexible optoelectronic sensors.