Transparent and stretchable bimodal triboelectric nanogenerators with hierarchical micro-nanostructures for mechanical and water energy harvesting

Advances in flexible electronics set new requirements of highly deformable energy generators to power these electronic devices. It is still a challenge to simultaneously achieve high stretchability and strong power generation for most energy generators to adapt the practical flexible applications. Herein, a hierarchical micro-nanostructure featured with high transparency, full stretchability, and superhydrophobicity is first created to construct high performance bimodal triboelectric nanogenerators (TENGs) for harvesting mechanical energy and water energy. The core SiO2/poly[vinylidenelfuoride-co-trifluoroethylene) P(VDF-TrFE) hierarchical micro-nanostructure is fabricated by a scalable electrospinning technology, and then reliably transferred to a pre-stretched elastomer to achieve robust stretchability and superhydrophobicity. Owing to the significantly increased surface roughness, the triboelectric output of the hierarchical structure is enhanced by 3 times higher than that of the pristine bulk film. The full flexibility characteristic enables the device to work under 300% stretching deformation without degrading performance. Furthermore, the superhydrophobicity and self-cleaning properties provide the TENG additional water energy harvesting ability. Under water flowing rate of 11 mL/s, the output reach approximately to 36 V, and 10 μA. The bifunctional energy harvesting ability, together with good transparency, high stretchability, and robust superhydrophobicity make the TENG a promising sustainable energy source for next-generation electronic devices.