Enhanced-performance droplet-triboelectric nanogenerators with composite polymer films and electrowetting-assisted charge injection

Droplet-Triboelectric nanogenerators (droplet-TENGs) are a promising renewable energy resource. Enhancing the dielectric surface properties is a primary requirement to increase the output performance of TENG device. In this study, droplet-TENGs are fabricated on indium tin oxide glass substrates with either (1) a pure amorphous fluoropolymer (AF) dielectric film; (2) a composite AF film doped with silk powder (AF/Silk); or (3) a composite AF film doped with polytetrafluoroethylene (PTFE) particles (AF/PTFEp). The energy-harvesting performance of the three devices is examined experimentally with and without the application of electrowetting-assisted charge injection (EWCI). For the AF and AF/Silk devices, the output current increases by approximately 12 times following the application of EWCI. Furthermore, the composite AF/Silk device also improves the current stability. The AF/PTFEp TENG increases the output current by approximately 5 times compared to that produced by the TENG with a pure dielectric layer. Moreover, the performance improvement increases to around 25 times following the application of EWCI. For all three devices, the output current increases with a reducing dielectric layer thickness. The output current also increases with an increasing concentration of the droplet solution. Overall, the results presented in this study provide a useful general understanding of the mechanisms underlying the operation of droplet-triboelectric nanogenerators. This research explores, for the first time, the effect of EWCI on composite material used for droplet-TENG and suggests possible strategies for enhancing the performance of such devices through an appropriate design of the dielectric layer and operating conditions.

Automated summary

This study fabricated different types of droplet-triboelectric nanogenerators and investigated the effect of electrowetting-assisted charge injection on their performance. The results showed that composite materials doped with silk powder and polytetrafluoroethylene particles significantly increased the output current, and further performance enhancement could be achieved through appropriate design of the dielectric layer and operating conditions.