A bistable electrochromic material based on a hysteretic molecular switch immobilized on nanoparticulate metal oxide

Authors

George Tsekouras, University of WollongongFollow
Nikolas Minder, University of Basel
Egbert Figgemeier, University of Basel
Olof Johansson, Uppsala University
Reiner Lomoth, Uppsala University

RIS ID

101092

Publication Details

Tsekouras, G., Minder, N., Figgemeier, E., Johansson, O. & Lomoth, R. (2008). A bistable electrochromic material based on a hysteretic molecular switch immobilized on nanoparticulate metal oxide. Journal of Materials Chemistry, 18 (47), 5824-5829.

Abstract

Combination of an electrochemically bistable Ru polypyridyl complex (2) with the metal oxide semiconductor Sb:SnO₂ formed the basis of an electrochromic hybrid material characterised by a hysteretic response to applied potential. The electrochemical bistability of the molecular component arises from redox-triggered linkage isomerisation where an ambidentate ligand changes reversibly between N- and O-coordination in the Ru(II) and Ru(III) states, respectively. Reversible oxidation and reduction result in a pronounced electrochromic effect (change in UV-Vis absorption at the metal-to-ligand-charge-transfer (MLCT) band) and the potentials for interconversion between the states are separated by approx. 0.5 V due to the linkage isomerisation reactions. With a carboxylate anchoring group on the auxiliary ligand, the bistable molecular switch was immobilised on the surface of nanoparticulate Sb:SnO₂ films. This resulted in an electrode material featuring a hysteretic electrochemical response where oxidation state and colour of the electrode depended on the electrochemical history of the system.