TY - JOUR A1 - Schott, M. A1 - Szczerba, Wojciech A1 - Posset, U. A1 - Vuk, A.S. A1 - Beck, M. A1 - Riesemeier, Heinrich A1 - Thünemann, Andreas A1 - Kurth, D. G. T1 - In operando XAFS experiments on flexible electrochromic devices based on Fe(II)-metallo-supramolecular polyelectrolytes and vanadium oxides N2 - Flexible electrochromic devices (ECDs) based on Fe(II)-metallo-supramolecular polyelectrolytes (Fe-MEPE) and vanadium oxide are studied in operando by means of x-ray absorption fine structure (XAFS) spectroscopy. The ECDs are blue-purple in the colored state at 0.0 V and become light yellow when a voltage of 1.6 V is applied. The XAFS studies at the K-edge of Fe(II) reveals that the absorption edge is shifted toward higher energies by 1.8 eV in the transparent state. Comparison of two different ECDs and different charge cycles demonstrates the reversibility and repeatability of the process. We attribute the shift to a charge transfer and a change of oxidation state of the ions from Fe2+ to Fe3+. The transition is not accompanied by a noticeable structural change of the octahedral coordination geometry as confirmed by analysis of the extended x-ray absorption fine structure (EXAFS) data. (C) 2015 Elsevier B.V. All rights reserved. KW - Metallo-supramolecular polyelectrolytes KW - Vanadium oxide KW - Electrochromism KW - Electrochromic device KW - Cyclic voltammetry KW - XAFS PY - 2016 U6 - https://doi.org/10.1016/j.solmat.2015.10.015 SN - 0927-0248 VL - 147 SP - 61 EP - 67 PB - Elsevier B.V. CY - Amsterdam [u.a.] AN - OPUS4-35251 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -