Electrochromic (EC) materials have various absorptivity according to their redox states. An electrochromic device (ECD) employing EC material electrodes can change its absorbance toward incident light upon switching external bias. In this study, thin films of polyaniline and tungsten trioxide are electrodeposited on tin-doped indium oxide conducting glass to fabricate EC electrodes. Solid-state ECDs composed of the electrodes and succinonitrile/polyethylene glycol (SN/PEG) composite electrolytes are constructed. Their EC properties, including transmittance modulation ability (ΔT), color-switching response time, coloration efficiency, and color cycling stability, are investigated. The appropriate operating voltage range is scrutinized by a proposed method. The solid-state Pani-WO3 ECD using a SN/PEG composite electrolyte containing 10.0 wt% PEG exhibited the fastest color-switching rate and high ΔT. The device maintained its ΔT for 4500 successive color-switching cycles without significantly decreasing.
