Regensburg 2010 – scientific programme
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DS: Fachverband Dünne Schichten
DS 43: Biomolecular and Functional Organic Layers II (Focused Session)
DS 43.2: Talk
Friday, March 26, 2010, 11:45–12:00, H2
Electrochromic Redox Reactions of Highly Fluorinated Phthalocyanine Thin Films — •Stefanie Nagel1, Christopher Keil1, Sergiu Gorun2, Robert Gerdes2, and Derck Schlettwein1 — 1Institute of Applied Physics, Justus-Liebig-University Giessen, Germany. email:schlettwein@uni-giessen.de — 2Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102, USA
Vacuum-evaporated thin films (10 - 100 nm) of copper complexes of hexadecafluorophthalocyanine (F16PcCu) and octaperfluoro(isopropyl)phthalocyanine (F64PcCu) on indium tin oxide electrodes have been studied in contact to LiCl aqueous electrolyte by cyclic voltammetry. Simultaneous monitoring of the absorption spectra of the films reveals nearly reversible electrochromic behavior after some conditioning cycles caused by an irreversible structural change. Only one reduction and reoxidation peak can be observed. Different isosbestic points in different potential ranges indicate different reduced species. Electroneutrality of the films is preserved by intercalation of Li+ ions. The influence of different film thickness and sweep rates on the cyclic voltammetry and spectral changes has been investigated. Due to the electron withdrawing effect of the substituents the redox potential is found to be shifted by about 0.2 V for F64PcCu towards more positive potentials relative to F16PcCu. An increase of intermolecular coupling in F16PcCu compared with F64PcCu is concluded from an observed spectral broadening of the Q-band.