Electron hopping rate measurements in ITO junctions: Charge diffusion in a layer-by-layer deposited ruthenium(II)-bis(benzimidazolyl)pyridine-phosphonate- TiO2 film

Charles Y. Cummings, Jay D. Wadhawan, Takuya Nakabayashi, Masa Aki Haga, Liza Rassaei, Sara E.C. Dale, Simon Bending, Martin Pumera, Stephen C. Parker, Frank Marken

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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 TiO 2 (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. Dapp = 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.

Original languageEnglish
Pages (from-to)196-201
Number of pages6
JournalJournal of Electroanalytical Chemistry
Issue number1-2
Publication statusPublished - 2011 Jul 1


All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Chemical Engineering(all)
  • Electrochemistry

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