Incorporation of plastic crystal and transparent UV-cured polymeric electrolyte in a complementary electrochromic device

Abstract The plastic crystal, namely succinonitrile (SN), has been incorporated with a UV-cured ethoxylated trimethylolpropane triacrylate (ETPTA) polymer to form a transparent, self-standing polymeric crystal composite electrolyte (PCCE). The PCCE, containing cross-linked polymer ETPTA and SN with 0.1 M tetrabutylammonium tetrafluoroborate (TBABF4), is proposed as the solid polymer electrolyte for electrochromic application. The weight ratio of ETPTA/SN is controlled at 85/15. Under a UV-exposure time of 30 s, the PCCE turns into a transparent solid with an excellent interfacial adhesion between two electrochromic thin films. The chosen anodic and cathodic coloring materials are polyaniline-carbon nanotubes (PANIs-CNT) and poly(butyl viologen) (PBV) thin films, respectively. The PANI/PCCE/PBV solid-state ECD exhibits two stages of color change, with the first stage redox reaction occuring between −1.0 and 0.5 V (PANI-CNTs vs. PBV) and the second stage occurs between 0.5 and 1.5 V. At 550 nm, the solid-state ECD shows a transmittance change of 39% and a coloration efficiency of 151.3 cm2/C, respectively. The transmittance of the ECD at 550 nm can be changed reversibly from 54% (bleached) to 15% (darkened) with the applied potentials of −2.0 and 0.75 V, respectively. Electrochemical and electrochromic properties of the ECD are studied using cyclic voltammetry (CV) and UV–vis-NIR spectroscopy.