A red-to-gray poly(3-methylthiophene) electrochromic device using a zinc hexacyanoferrate/PEDOT:PSS composite counter electrode

In this paper, we describe a novel red-to-gray poly(3-methylthiophene) (PMeT) electrochromic device (ECD) with the aid of a zinc hexacyanoferrate (ZnHCF)/PEDOT:PSS counter electrode. The application of ZnHCF to an ECD is first reported. ZnHCF has long suffered from poor deposition yield problem, but we demonstrate that a robust ZnHCF film can be prepared by spin coating of a liquid suspension composed of ZnHCF nanoparticles and PEDOT:PSS ink on ITO. It was found that the ZnHCF/PEDOT:PSS composite worked much better with PMeT than pure ZnHCF or pure PEDOT:PSS from both electrochemical and optical aspects. With a LiClO 4/PC electrolyte, the PMeT ECD having ZnHCF/PEDOT:PSS as its counter electrode could be reversibly switched between its red state (>0.8 V) and its gray state (