A unified theoretical model for Triboelectric Nanogenerators

A unified theoretical model applicable to different types of Triboelectric Nanogenerators (TENGs) is presented based on Maxwell's equations, which fully explains the working principles of a majority of TENG types. This new model utilizes the distance-dependent electric field (DDEF) concept to derive a universal theoretical platform for all vertical charge polarization TENG types which overcomes the inaccuracies of the classical theoretical models as well as the limitations of the existing electric field-based model. The theoretical results show excellent agreement with experimental TENGs for all working modes, providing an improved capability of predicting the influence of different device parameters on the output behaviour. Finally, the output performances of different TENG types are compared. This work, for the first time, presents a unified framework of analytical equations for different TENG working modes, leading to an in-depth understanding of their working principles, which in turn enables more precise design and construction of efficient energy harvesters.