Long-Range Electron Transport of Ruthenium-Centered Multilayer Films via a Stepping-Stone Mechanism

We studied electron transport of Ru complex multilayer films, whose structure resembles redox-active complex films known in the literature to have long-range electron transport abilities. Hydrogen bond formation in terms of pH control was used to induce spontaneous growth of a Ru complex multilayer. We made a cross-check between electrochemical measurements and I-V measurements using PEDOT:PSS to eliminate the risk of pinhole contributions to the mechanism and have found small beta values of 0.012-0.021 angstrom(-1). Our Ru complex layers exhibit long-range electron transport but with low conductance. On the basis of the results of our theoretical-experimental collaboration, we propose a modified tunneling mechanism named the stepping-stone mechanism, where the alignment of site potentials forms a narrow band around E-F, making resonant tunneling possible. Our observations may support Tuccito et al.'s proposed mechanism.