Photochromism of amorphous molybdenum oxide films with different initial Mo 5+ relative concentrations

Mehdi Rouhani, Yong L. Foo, Jonathan Hobley, Jisheng Pan, Gomathy Sandhya Subramanian, Xiaojiang Yu, Andrivo Rusydi, Sergey Gorelik

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)

Abstract

We report the effect of deposition conditions on the intrinsic color and photochromic properties of amorphous MoO 3 thin films (a-films) deposited by R.F. unbalanced magnetron sputtering. Optical transmission spectroscopy was used to measure optical properties of the films. The conversion between Mo 6+ and Mo 5+ for as-deposited and UV irradiated films was characterized using XPS. Raman spectroscopy was used to confirm that the results of XPS were consistent with the bulk of the films. It is shown that absorption coefficient of as-deposited films increases with Mo 5+ content. The temporal evolution of absorption coefficients for all films under UV light irradiation is measured using optical transmission spectroscopy. The largest change in absorption was observed for the film with the highest initial Mo 5+ content. The temporal evolution of absorption coefficients for all the films shows initial fast rise within first minute of irradiation. XPS and Raman results show that for all films Mo 5+ content increases as a result of UV irradiation except for the film with the highest initial Mo 5+ content, for which the Mo 5+ content decreases relative to Mo 6+ despite the fact that the absorption of the film continues to rise. Further understanding of this mechanism is important since it will lead to enhanced photochromism and extend the photo-colorability of the films beyond the point at which the conversion of Mo 6+ to Mo 5+ is saturated.

Original languageEnglish
Pages (from-to)150-158
Number of pages9
JournalApplied Surface Science
Volume273
DOIs
Publication statusPublished - 2013 May 15

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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