Triboelectric nanogenerators: providing a fundamental frameworkElectronic supplementary information (ESI) available. See DOI: 10.1039/c7ee01139c

A new model which comprehensively explains the working principles of contact-mode triboelectric nanogenerators (TENGs) based on Maxwell's equations is presented. Unlike previous models which are restricted to known simple geometries and derived using the parallel plate capacitor model, this model is generic and can be modified to a wide range of geometries and surface topographies. We introduce the concept of a distance-dependent electric field, a factor not taken into account in previous models, to calculate the current, voltage, charge, and power output under different experimental conditions. The versatility of the model is demonstrated for non-planar geometry consisting of a convex-concave surface. The theoretical results show excellent agreement with experimental TENGs. Our model provides a complete understanding of the working principles of TENGs, and accurately predicts the output trends, which enables the design of more efficient TENG structures. A generic electromagnetic model for the working principles of triboelectric nanogenerators derived using Maxwell's equations, to a universally applicable framework.