Aqueous in‐situ electrosynthesis and electrochromic performance of PEDOT:PSS/Reline film

Abstract Poly(3,4‐ethylene dioxythiophene) (PEDOT) is a promising electrochromic material in many practical application, such as smart windows and displays. However, there are still difficulties in currently realizing green manufacturing, high coloration efficiency, and rapid response. Herein, in‐situ electrochemical polymerization of PEDOT:PSS/Reline films was suggested in aqueous solution. Deep eutectic solvents (DES) composed of choline chloride and urea (Reline) were employed as green solvents in reaction system and used as dopants for the PEDOT:PSS. The as‐prepared PEDOT:PSS/Reline films exhibited remarkable electrochromic properties, including great ion diffusion coefficient, fast reaction time (coloration response time was 1.4 s), prominent transmittance modulation (38%), high coloration efficiency (223 cm 2 /C) and excellent cyclic stability. Impressively, doping of Reline cannot only provide a green polymerization environment, but also significantly boost the electrochromic properties.