Advances in the study of electrochromic materials (overseas travel grant)

An electrochromic material (an 'electrochrome') is one where a reversible colour change takes place upon reduction (gain of electrons) or oxidation (loss of electrons), on passage of electrical current after the application of an appropriate electrode potential. Commercial applications of electrochromes include anti-glare car mirrors, electrochromic strips as battery state-of-charge indicators and electrochromic sunglasses. Proposed applications include 'smart windows' (based on modulation of either the transmitted or reflected solar radiation) for use in cars and in buildings, re-usable price labels, protective eyewear, controllable aircraft canopies, glare-reduction systems for offices, devices for frozen-food monitoring, camouflage materials, spacecraft thermal control, and controllable light-reflective or light-transmissive devices (displays) for optical information and storage. Many chemical species show electrochromic properties, including metal coordination complexes, both in solution and as polymer films, inorganic charge-transfer complexes, metal oxides (especially tungsten trioxide), viologens (bipyridylium salts) and electroactive conjugated polymers such as polypyrroles and polythiophenes. This research programme follows on from practical research undertaken by Dr Mortimer during September to December 2004 and March/April 2005 in the laboratories of Professor J R Reynolds in the Department of Chemistry, University of Florida, funded, in part, by an EPSRC overseas travel grant. The new research programme aims are to foster this developing research collaboration with the internationally-leading electrochromic conjugated polymers research group; to apply the technique of in situ colorimetry ('colour analysis') to the broad range of available electrochromic materials; to investigate the effect of conjugated polymer deposition technique and film thickness on perceived colour; to optimise contrast ratio through morphology control; to study mechanistic aspects of viologen electrochromicity; to construct and study novel electrochromic devices; and to train UK researchers in these various techniques, towards the benefit of UK academia and industry.