Light-Enhanced Flexible Triboelectric Nanogenerator for Ultraviolet Monitoring

Flexible and wearable electronics are transforming healthcare and human-machine interaction, but their progress hinges on power sources matching device softness, stretchability, and safety. Flexible triboelectric nanogenerators (TENGs) harvest low-frequency mechanical motion through simple architectures; yet almost all reported flexible TENGs operate in a single modality, producing fixed outputs that respond only to mechanical contact and cannot adapt to stimuli such as ultraviolet (UV) light. We address this limitation with a photoresponsive electrode strategy. A dual-network poly(ethylene glycol) diacrylate (PEGDA)/poly(vinyl alcohol) (PVA) hydrogel codoped with Zn2+ ions and carbon quantum dots (CQDs) is integrated into a single-electrode, Ecoflex-encapsulated TENG. The UV-cross-linked/freeze-thawed hydrogel sustains 840% strain at 237 kPa with minimal hysteresis; Zn2+ halving internal impedance doubles short-circuit current, while CQDs photogating provides a tunable ∼16% gain in open-circuit voltage under 365 nm irradiation (25 mW/cm2). The device maintains 110 ± 15 V for 500 s and powers a battery-free wristband that simultaneously harvests biomechanical energy, tracks cumulative UV dose and issues Bluetooth alerts. By bridging mechanical and optical energy domains in a transparent, stretchable platform, our approach overcomes the single-modality bottleneck of current flexible TENGs and offers a path toward adaptive, self-powered wearable systems.