Step-current analysis of the built-in potential of tungsten oxide-based electrochromic devices and the effects of spontaneous hydrogen deintercalation

M. Denesuk, J. P. Cronin, S. R. Kennedy, Donald R Uhlmann

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Abstract

General methods for the analysis of step-current measurements on intercalation devices are applied to an aqueous, protonic, tungsten oxide-based device. Plots of the built-in potential as a function of the passed charge, V bi(ΔQ), are generated. Methods are demonstrated for extracting a useful indicator of the intercalation level from ΔQ and for relating V bi to the applied potential. An intercalation efficiency, ζ, is defined, and ζ(V bi) plots are generated. With proper accounting for extraneous contributions, ζ(V bi) provides a measure of the effective site energy distribution and of the instantaneous efficiency (or capacity) of the intercalation process. A nonfaradaic spontaneous deintercalation process has been observed which acts to deintercalate the film without contributing to the measured current. Methods for including this effect in the analysis are presented in terms of a virtual current.

Original languageEnglish (US)
Pages (from-to)888-897
Number of pages10
JournalJournal of the Electrochemical Society
Volume144
Issue number3
Publication statusPublished - Mar 1997

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ASJC Scopus subject areas

  • Electrochemistry
  • Surfaces, Coatings and Films
  • Surfaces and Interfaces

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