Implications of the detailed fluctuation theorem for the sources of irreversibility in interfacial charge transfer processes.

We investigate from basic principles of nonequilibrium statistical mechanics the general reasons why electron transfer across an interface is associated with irreversible elements (resistances) in equivalent circuit modeling. We apply the detailed fluctuation theorem [C. Jarzynski, J. Stat. Phys. 98, 77 (2000)] to a simple model of an interface between two different materials. The elementary transition rates are interpreted in terms of the evolution of a microstate, and obey a ratio that is related to the heat absorbed from the phonon bath while promoting an electron to a higher energy level. The amount of irreversibility (the entropy production), and also the macroscopic current density, can be both obtained with the additional constraint that the system belongs in a particular mesostate, determined by the distribution of chemical and electrostatic potential.