Electrochromic Properties of MnO2-Based Layered Polymer Nanocomposite

This paper presents electrochromic properties of manganese oxide-based multilayered nanocomposite that was grown electrochemically on a transparent indium-tin oxide (ITO)-coated glass slide in a thin-film form. The composite film consists of negatively charged manganese oxide nanolayers and the intercalated cationic polyallylamine. The ITO-supported film exhibited pseudocapacitive properties in an aqueous KCl electrolyte in the potential region between 0 and +1.0 V vs Ag/AgCl without any change in the framework structure. In situ UV-visible spectrometry revealed that the film changes in color between brown (colored state) and pale yellow (bleached state). This phenomenon is induced by charging and discharging of a pseudocapacitor of manganese oxide, in which the electroneutrality of the film can be maintained largely by Cl- anions, and not cations. The coloration efficiency (absorbance change per unit charge) was measured to be 62.3 cm(2) C-1 at the wavelength of 480 nm.