Interfacial friction-induced electronic excitation mechanism for tribo-tunneling current generation

TL;DR

This paper demonstrates a novel mechanism for direct-current generation through interfacial electronic excitation during sliding, achieving significantly higher current densities than traditional triboelectric devices, with implications for energy harvesting.

Contribution

It introduces a new interfacial friction-induced electronic excitation mechanism for tribo-tunneling current generation, surpassing conventional triboelectric nanogenerators in efficiency.

Findings

Achieved ~35 A/m2 current density in a metal-insulator-semiconductor sliding system.

Identified electronic excitation at the interface as the source of electromotive force.

Revealed the fundamental role of non-equilibrium interfacial charge variations in energy conversion.

Abstract

Direct-current (d.c.) electricity generation using moving Schottky contact is emerging as a new strategy for mechanical energy conversion. Here, we demonstrate the generation of d.c.tunneling current with a density of ~35 A/m2 at a metal-insulator-semiconductor (MIS) sliding system using micro-tips. The measured current densities were found to be three to four orders of magnitude higher than that observed with the conventional polymer-based triboelectric nanogenerators (TENGs). The electromotive force for the tribo-tunneling transport comes from the dynamic electronic excitation at the frictional interface rather than from the electrostatically trapped surface charges as in the case of conventional TENGs. The strong electronic excitation can give rise to a non-equilibrium interfacial charge variation. Depending on the energy distribution of the excited electrons/holes, the charge variation subsequently dissipates non-adiabatically into tunneling current and trapped surface charges, or adiabatically into heat. These fundamental results not only enhance our understanding of the triboelectric phenomenon, but also open up new paths for the development of next-generation mechanical energy harvesting and sensing techniques.