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 micronanostructure 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 36V, and 10 mu A. 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.