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A site-saturation model for the variation in optical efficiency of tungsten oxide-based intercalation devices is presented. The model applies to situations in which a dominant fraction of the electrons associated with the intercalating species are appreciably localized. It is predicted that the optical efficiency diminishes with increasing intercalation level, reaching zero when half the sites are occupied. The model is quantitative and predictive. The model is compared to several sets of data which it matches well. The only parameters of the model are film thickness, maximum obtainable optical density, and relative density of the film. The range of suitability of the model and the interpretation of its comparison with experiment are discussed.

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An analysis of Li-intercalation and deintercalation in a tungsten-oxide based electrochromic device is presented. An hysteresis between intercalation and deintercalation has been separately observed in both the built-in potential and the optical efficiency of the devices. This hysteresis is explained by a two-phase model in which intercalation occurs as the parallel, equipotential filling of the two phases, but where a deintercalation barrier associated with one of the phases imposes the observed asymmetry. An equivalent circuit model is given, allowing for the prediction of the deintercalation behavior from the intercalation behavior with a single adjustable parameter (representing the deintercalation barrier). The observed data are well-explained by the circuit model; using a single adjustable parameter, an accurate description of the deintercalation behavior may be obtained from the data on intercalation.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.252.67.66 Downloaded on 2014-06-25 to IP

No abstract