The film of PEDOT was prepared in this study via electrochemical polymerization using EDOT as monomer in LiClO4/PC solution. The effects on the properties of the film were surveyed including the deposition voltage and deposition time. The morphology of the film was observed by scanning electron microscopy. The electrochromic kinetics was analyzed by combination of electrochemical workstation and UV-Visible spectrophotometer such as the transmittance, transmittance contrast, coloring efficiency and the response time. The results indicated the film presents a coral shape despites of the deposition voltage and the deposition time. In case of the application as electrochromic film, the optimal process condition is 1.3 V and 24 s. The corresponding transmittance is 82.77% in fade state. The transmittance contrast is 17.87%, and the coloring efficiency is about 117.92 cm2/C, the response time is 0.52 s.

An aqueous electrochromic composite poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)/graphene oxide was prepared in this study by a simple one-step in-situ polymerization. This simple one-step preparation method allowed the composite to achieve good performance without post-treatment. When the composite was coated on the indium tin oxide using as electrochromic film, it exhibited a noticeable electrochromism with reversible color changes from light blue to dark blue, and showed a wider range of discoloration (33%). The composite owns a larger diffusion coefficient of lithium ions (2.95 × 10–15 cm2 s–1) and better cycling performance compared with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) film.