Skin‐Mimicking, Stretchable Photodetector for Skin‐Customized Ultraviolet Dosimetry

Despite extensive research on photoelectric sensors that typically output signals to indicate the transient ultraviolet (UV) intensity, developing wearable, electrometric photodetectors that can reveal the cumulative UV exposure remains challenging. Here, an organic–inorganic hybrid bulk heterojunction (BHJ) is used to construct a skin‐mimicking, wearable photodetector, based on conductive polymer sensitized with semiconducting nanoparticles. Owing to the UV‐induced reduction reactions, the BHJ photodetectors (PDs) can long remember the UV radiation previously exposed. Moreover, based on the solution processability of bulk heterojunction blends and rich surface functional groups of polydopamine, BHJ PDs can fully inherit the ultraflexibility from electrospun fiber‐networked structure. Thus, this fiber‐configured photodetector is working well even at the strains of up to 60%. Without requiring any complicated analytical tool, its memory effect and simple‐to‐process output facilitate the working mechanism of power‐free UV monitor, while catering to the individual need of different skin types. This work combines the bottom materials design to the top device application, pointing out a new direction in wearable UV sensor technologies.