RADIO-FREQUENCY SPUTTERED COBALT OXIDE COATING - STRUCTURAL, OPTICAL,AND ELECTROCHEMICAL CHARACTERIZATION

Cobalt oxide thin films (thickness 2000 angstrom) with different stoic hiometries were deposited by reactive rf sputtering. The variation of the oxygen partial pressure lead to films with compositions varying fr om metallic cobalt to CO3O4, as determined by x-ray diffraction and x- ray photoelectron spectroscopy. The electrochromic properties of the f ilms were investigated in aqueous electrolytes (0.1 M KOH). The initia l electrochemical behavior of the films is strongly dependent on the f ilm deposition conditions, but after cycling the electrochemical/elect rochromic characteristics of the different deposits were quite similar . Transmittance changes and electrochromic efficiency are discussed.