Self-powered fiber-shaped wearable omnidirectional photodetectors

Different from photodetectors (PDs) with planar structure, fiber-shaped PDs seldom demonstrate self-powered property due to its crooked and tiny surface except intergrating with energy devices in a system, which limit its wide application. Here, we demonstrate a self-powered fiber-shaped wearable omnidirectional ultraviolet (UV) PD overcoming this obstacle through constructing built-in electric field. This fiber-shaped PD has obvious response with UV illumination at zero bias, and could stably operate under different bending states. It exhibits responsivity of 9.96 mA/W under zero bias, and the response is quite steady with omnidirectional incident light. The I-light/I-dark ratio of this PD is about 2 under zero bias, and has almost no change under bending. The photocurrent generating under zero bias is likely contributed by the p-n heterojunction between ZnO nanowire arrays and PVK. The results indicate that as-prepared fiber-shaped PDs could be applied to DV detecting fields which requires smart-size, omnidirectional, wearable and self-powered.