Halide-exchanged perovskite photodetectors for wearable visible-blind ultraviolet monitoring

Wearable sensing technologies are essential for personalized healthcare via continuously monitoring the surrounding information. Ultraviolet (UV) light, an important component of solar radiation, is recognized as the main inducement of skin cancers. So far, the use of rigid and costly technologies to fabricate UV sensors still hinders their implementation in wearable and portable electronics. Here we present a wearable UV wristband based on a self-powered flexible perovskite photodetector for real-time UV monitoring. Utilizing a solution-assisted halide exchange strategy, device based on CH3NH3PbCl3 film exhibits excellent UV detection performance (high responsivity of 359.03 mA/W, fast rise/fall time of 3.91/4.55 ms), outstanding mechanical robustness (remaining over 80% of initial performance after 2500 bending cycles), as well as desirable operational stability (unchanged photoresponse under 500 h of continuous UV light soaking). Integrated with commercially available soft circuits, this fully flexible sensor system enables round-the-clock probing for UV radiation indoor and outdoor in conjunction with necessary environmental information, which can be displayed and recorded on a smartphone, to prevent prolonged UV exposure. The wearable platform not only paves the way for seamlessly integrated photodetectors, but also enables a wide range of personalized environmental and health monitoring applications.