Rational Design Strategy for Triboelectric Nanogenerators Based on Electron Back Flow and Ionic Defects: The Case of Polytetrafluoroethylene

Abstract

The lack of theoretical understanding of triboelectrification has hindered the development of energy harvesting technologies like triboelectric nanogenerators. Focusing on polytetrafluoroethylene, a material with a strong triboelectric output, a model predictive of its triboelectric behavior, driving the development of improved nanogenerators are formulated. With a combined computational‐experimental approach it is shown that defluorination enhances polytetrafluoroethylene nanoscale triboelectric charging. Then a model, explaining the macroscale triboelectric output as determined by the competition of two mechanisms is developed. Defluorination enhances charging while also reducing the interface gap, favoring the backflow of electrons, and possibly reducing charging. However, numerical analysis shows that backflow is negligible, aligning with the prediction of increased triboelectric output. By building triboelectric nanogenerators with defluorinated polytetrafluoroethylene samples, achieved by X‐ray irradiation, a one‐order‐of‐magnitude output increase is demonstrated. The predictive models, supported by experiments, lead to an improved strategy for designing effective energy harvesting devices and new applicative breakthroughs.

Triboelectric Charging Properties of the Functional Groups of Common Pharmaceutical Materials Using Density Functional Theory Calculations

“…There is a noticeable difference in the vacuum energy of the isolated paracetamol compared to the vacuum energy of the isolated metal surface or the whole system; this is expected to create a dipole moment between the surfaces, and therefore some charge redistribution takes place at the surface. The electrostatic peaks of the surface-molecule system are slightly depressed compared to the isolated systems, which could influence the electrostatic barrier to charge transfer [ 33 ]. This observation was consistent across all surfaces tested; additional plots are available in the Supplementary Data (Figures S1 and S2) .…”