Effect of crystallinity on electrochromic mechanism of LixWO3 thin films

Se Hee Lee*, Maeng Je Seong, Hyeonsik M. Cheong, Esra Ozkan, Edwin C. Tracy, Satyen K. Deb

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

79 Citations (Scopus)

Abstract

Intercalation of lithium ions in amorphous tungsten oxide films and in monoclinic polycrystalline tungsten oxide films has been studied using electrochemical analyses and Raman spectroscopy. We present direct evidence for W5+ 5d-electron localization in amorphous tungsten oxide films upon lithium ion and electron intercalation by comparing the Raman spectra of amorphous and crystalline tungsten oxide films. We observe that when lithium ions and electrons are inserted into the crystalline tungsten oxide films, the monoclinic structure of the material proceeds to progressively increased symmetry. On the other hand, when lithium ions and electrons are inserted into amorphous tungsten oxide films, the inserted electrons are localized in W5+ sites and polarize their surrounding lattice to form small polarons. The extra Raman peaks due to the W5+-O single bonds and W5+=O double bonds appear at 330 and 450 cm-1, respectively.

Original languageEnglish
Pages (from-to)447-452
Number of pages6
JournalSolid State Ionics
Volume156
Issue number3-4
DOIs
Publication statusPublished - Jan 2003

Funding

This work was supported by the Department of Energy under Contract No. ED-AC36-99GO10337. The work at Sogang University was supported by the Korea Research Foundation Grant (KRF-2000-015-DP0135).

FundersFunder number
Korea Research FoundationKRF-2000-015-DP0135
U.S. Department of Energy

    Keywords

    • Electrochromic mechanism
    • Intercalation
    • LiWO thin films

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