Electrochromic features of hybrid films composed of polyaniline and metal hexacyanoferrate

Hybrid organic/inorganic films, composed of polyaniline (PANI) matrix and P russian blue-Like nickel hexacyanoferrate redox centers, showed reversible electrochromic behavior in acidic potassium salt electrolytes. The system's coloration properties were assessed from various spectroelectrochemical me asurements including voltabsorptometry that involved monitoring of the time -derivative signal of absorbance at 700 and 410 mn as a function of linearl y scanned potential. Gold-covered foil was used as a conductive, optically transparent, substrate onto which the composite film was electrodeposited b y potential cycling in the mixture for modification consisting of aniline m onomer, Ni2+, Fe(CN)(6)(3-) and electrolyte containing K+ and H+ ions. An i mportant feature of hybrid (composite) material was that its electrochromic properties were dominated by color changes occurring in the PANI component . Coloration originating from nickel hexacyanoferrate barely affected the s ystem's electrochromic characteristics. But the cyanometallate redox center s distributed in the PANI matrix behaved reversibly as expected for a syste m capable of fast charge transport. (C) 2001 Elsevier Science Ltd. All righ ts reserved.