Electrochemical staining (electrochromism) is a phenomenon related to the reversible color change by external potential. In this research, two electrochromic (EC) systems have been studied: molybdenum-doped tungsten trioxide as cathodic material (Mo-WO3) and aniline/O-anisidine copolymer (PANI-co-POA) as anodic material. Both films were synthesized by electrochemical polymerization on indium tin oxide (ITO). In order to fabricate the electrochromic device (ECD), the cell of ITO/Mo-WO3/polyvinyl alcohol (PVA), 0.5 M H2SO4/PANI-co-POA/ITO was provided. Mo-WO3 and PANI-co-POA were characterized using EDS, FT-IR, XRD, FE-SEM and TEM. Structure distortion may be induced by doping of Mo atoms into WO3 structure. The amorphous state of Mo-WO3 has desirable electrochemical behavior due to increasing in active sites and access of electrolyte. In addition, PANI-co-POA as counter electrode material has high electrical conductivity and causes to fast kinetic of charge transfer in ECD. The electrochromic properties of PANI-co-POA and Mo-WO3 films were evaluated by UV–Visible spectroscopy (UV–Vis), cyclic voltammetry (CV) and chronoamperometry (CA). The optical response times of ECD were 1.8 s for coloration (tc) and 2 s for bleaching (tb). The coloration efficiency (CE) of the specimens was also calculated at 633 nm for Mo-WO3 (144.19 cm2 C−1), PANI-co-POA (35.81 cm2 C−1) and ECD (99.70 cm2 C−1). The results showed that the use of both Mo-WO3 (cathode) and PANI-co-POA (anode) leads to improvement in the electrochromic properties of ECD.
