Phenomenological analysis of the optoelectrochemical behavior of electrochromic intercalation devices

A set of phenomenological analysis tools have been developed for the characterization of the optoelectrochemical behavior of electrochromic intercalation devices. Both step current and step potential excitations are considered. Great simplification is afforded by working with the passed charge as the primary independent variable; consideration is also given, however, to the transmission or built-in device potential as independent variables. It is shown that quasi-static intercalation efficiency curves, generated from step current measurements, can elucidate the intercalation site-energy distribution; these curves are also compared to dynamic intercalation efficiency curves obtained from step potential measurements. Quasi-static and dynamic optical efficiencies are also considered and compared. The scaling properties of some of the phenomenological parameters may be used to generate master curves which unify sets of data obtained under a variety of conditions (applied voltages, imposed currents, film thicknesses, etc.). Quantitative predictions can be made of device behavior under conditions not probed experimentally.