Multiple charge carrier species as a possible cause for triboelectric cycles

TL;DR

This paper explores how the presence of multiple charge carrier species can explain the existence of triboelectric cycles, challenging the traditional view that contact electrification follows a single, unidirectional series.

Contribution

It demonstrates that multiple charge carriers can produce triboelectric cycles, providing a new perspective on the mechanisms behind contact electrification.

Findings

Single charge carrier leads to series, not cycles.

Multiple carriers enable the formation of cycles.

The work highlights the importance of charge carriers in understanding triboelectric phenomena.

Abstract

The tendency of materials to order in triboelectric series has prompted suggestions that contact electrification might have a single, unified underlying description. However, the possibility of triboelectric cycles, i.e. series that loop back onto themselves, is seemingly at odds with such a coherent description. In this work, we propose that if multiple charge carrying species are at play, both triboelectric series and cycles are possible. We show how series arise naturally if only a single charge carrier species is involved and if the driving mechanism is approach toward thermodynamic equilibrium, and simultaneously, that cycles are forbidden under such conditions. Suspecting multiple carriers might relax the situation, we affirm this is the case by explicit construction of a cycle involving two carriers, and then extend this to show how more complex cycles emerge. Our work highlights the importance of series/cycles towards determining the underlying mechanism(s) and carrier(s) in contact electrification.