High-Performance Polyimide-Based Water-Solid Triboelectric Nanogenerator for Hydropower Harvesting.

Water-solid triboelectric nanogenerators (TENGs) are insensitive to ambient humidity, providing a wide range of possibilities for designing stable water-energy-based harvesters and self-powered sensors. However, the wide application of most water-solid TENGs has been limited by low triboelectrification performance. To boost the output performance of water-solid TENGs, a newly structured TENG has been developed by adding a polyimide (PI) as a charge storage intermediate layer between the friction layer and the conducting layer, significantly improving the output performance (1.260 mW), with a 5-fold increase compared to the water-solid TENG without the PI intermediate layer (0.234 mW). This analysis shows that adding an intermediate layer with a high density of electron capture sites to the TENG results in more triboelectric charge being retained, thereby improving the electrical performance of TENG. The electrical performance of TENG is related to the thickness of the PI layer, but this is not a positive correlation. Contact angles and falling heights between the droplet and the device also affect the output performance. Finally, the water-solid PI-TENG we have developed has promise in hydropower harvesting capabilities and can be used to power warning signals on a dark and rainy night to ensure the safety of people.