Focused ion beam (FIB) machining allowed a sub-micron trench to be cut through tin-doped indium oxide (ITO) film on glass to give a generator - collector junction electrode with narrow gap (ca. 600 nm). A layer-by-layer deposited film composed of a dinuclear ruthenium(II)-bis(benzimidazolyl)pyridine-phosphonate (as the negative component) and nanoparticulate TiO2 (ca. 6 nm diameter, as the positive component) was formed and investigated first on simple ITO electrodes and then on ITO junction electrodes. The charge transport within this film due to Ru(II/III) redox switching (electron hopping) was investigated and an apparent diffusion coefficient of ca. D app = 2 ( 1) 10-15 m2 s-1 was observed with minimal contributions from intra-molecular Ru-Ru interactions. The benefits of FIB-cut ITO junctions as a tool in determining charge hopping rates are highlighted. 2011 Elsevier B.V. All rights reserved.
Cummings, C. Y., Wadhawan, J. D., Nakabayashi, T., Haga, M., Rassaei, L., Dale, S. E. C., Bending, S., Pumera, M., Parker, S. C., & Marken, F. (2011). Electron hopping rate measurements in ITO junctions: Charge diffusion in a layer-by-layer deposited ruthenium(II)-bis(benzimidazolyl)pyridine-phosphonate-TiO2 film. Journal of Electroanalytical Chemistry, 657(1-2), 196-201. https://doi.org/10.1016/j.jelechem.2011.04.010