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, cilt.45, ss.7780-7783, 2006 (SCI-Expanded) identifier identifier

Özet

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.