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- Title
Eliminating degradation and uncovering ion-trapping dynamics in electrochromic WO<sub>3</sub> thin films.
- Authors
Wen, Rui-Tao; Granqvist, Claes G.; Niklasson, Gunnar A.
- Abstract
There is keen interest in the use of amorphous WO3 thin films as cathodic electrodes in transmittance-modulating electrochromic devices. However, these films suffer from ion-trapping-induced degradation of optical modulation and reversibility on extended Li+-ion exchange. Here, we demonstrate that ion-trapping-induced degradation, which is commonly believed to be irreversible, can be successfully eliminated by constant-current-driven de-trapping; that is, WO3 films can be rejuvenated and regain their initial highly reversible electrochromic performance. Pronounced ion trapping occurs when x exceeds ∼0.65 in LixWO3 during ion insertion. We find two main kinds of Li+-ion-trapping site (intermediate and deep) in WO3, where the intermediate ones are most prevalent. Li+ ions can be completely removed from intermediate traps but are irreversibly bound in deep traps. Our results provide a general framework for developing and designing superior electrochromic materials and devices.
- Subjects
ELECTROCHROMIC devices; ION traps; ELECTRODES; OPTICAL modulation; THIN films
- Publication
Nature Materials, 2015, Vol 14, Issue 10, p996
- ISSN
1476-1122
- Publication type
Article
- DOI
10.1038/nmat4368