Microscopic model for contact electrification between solids and fluids

Triboelectric charge transfer between materials is a well-known phenomenon since more than 2000 years that still causes dispute. Recent experimental evidence suggests electron transfer to be the main mechanism for contact electrification between dielectrics and metals, and the electron transfer is specified by the material bandstructures and Fermi levels [1]. We present a new microscopic formalism based on a tight-binding Hamiltonian to describe charge transfer between two materials. The model captures charge transfer dynamics on a femtosecond scale, reveals the influence of Coulomb interactions for charge transfer oscillations, and is able to predict charge transfer differences between materials whether structured or disordered solids and fluids. We demonstrate that charge transfer between fluids and solids is more effective than between two solids, that charge transfer between two similar materials is possible, and shed light on the differences between metal-dielectric and dielectric-dielectric contact electrification.
[1] Z. L. Wang and A. C. Wang, “On the origin of contact-electrification,” Materials Today (2019).