Effect of O-2 flow concentration during reactive sputtering of Ni oxide thin films on their electrochemical and electrochromic properties in aqueous acidic and basic electrolyte solutions


Abe Y., Lee S., Zayim E. O. , Tracy C. E. , Pitts J. R. , Deb S. K.

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS, vol.45, pp.7780-7783, 2006 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 45
  • Publication Date: 2006
  • Doi Number: 10.1143/jjap.45.7780
  • Title of Journal : JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS
  • Page Numbers: pp.7780-7783

Abstract

Thin films of Ni oxide were deposited by reactive sputtering in argon/oxygen gas mixtures using O-2 flow concentrations ranging from 6 to 100% and their electrochemical and electrochromic properties were examined using dilute acidic (1 M KCl + 0.5 mM H2SO4) and basic (1 M KOH) aqueous electrolyte solutions. An electrochromic coloration efficiency of 32 +/- 5 cm(2)/C was obtained for all the Ni oxide films regardless of O-2 concentration in both KCl + H2SO4 and KOH. The charge capacity and resultant change in them optical density of the Ni oxide films increased with O-2 concentration owing to a decrease in crystal grain size and the resultant increase in the active surface area of the NiO crystal grains. Although the interfacial capacitances of the Ni oxide films in KCl + H2SO4 are 2-3 times less than those in KOH, a maximum change in optical density of 0.57 was obtained in KCl + H2SO4 for a fine-grained Ni oxide film with a thickness of 400 ran sputtered in 100% O-2.