Annealing induced structural evolution and electrochromic properties of nanostructured tungsten oxide films

Ching Lin Wu, Chung Kwei Lin, Chun Kai Wang, Sheng Chang Wang, Jow Lay Huang

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


The effect of microstructure on the optical and electrochemical properties of nanostructured tungsten oxide films was evaluated as a function of annealing temperature. The films using block copolymer as the template were prepared from peroxotungstic acid (PTA) by spin-coating onto the substrate and post-annealed at 250-400 C to form tungsten oxide films with nanostructure. The microstructure of the films was measured by X-ray diffraction and surface electron microscopy. The films annealed at temperatures below 300 C are characterized by amorphous or nanocrystalline structures with a pore size of less than 10 nm. The evaluated annealing temperature caused a triclinic crystalline structure and microcracks. Cyclic voltammetry measurements were performed in a LiClO4-propylene carbonate electrolyte. The results showed that the ion inserted capacity were maximized for films annealed at 300 C and decreased with the increasing of annealing temperature. The electrochromic properties of the nanostructured tungsten oxide films were evaluated simultaneously by potentiostat and UV-vis spectroscopy. The films annealed at 300 C exhibit high transmission modulation (â̂†T ~ 40%) at λ = 633 nm and good kinetic properties. As a result, the correlation between the microstructure and kinetic properties was established, and the electrochromic properties have been demonstrated.

Original languageEnglish
Pages (from-to)258-262
Number of pages5
JournalThin Solid Films
Publication statusPublished - Dec 31 2013


  • Electrochromism
  • Nanostructured
  • Post annealing
  • Sol-gel method
  • Tungsten oxide films

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry


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