The effect of wetting property on electrochromic properties offunctionalized poly(3,4-ethylenedioxythiophene) films

We have prepared three poly(3,4-ethylenedioxythiophene) (PEDOT) derivatives including PEDOT, hydroxymethyl PEDOT (PEDOT-OH) and perfluoro-substituted PEDOT (PEDOT-F), along with its electrochemical and electrochromic (EC) characterization. The three PEDOT derivatives have variable degree of wettability; which have been compared systematically to investigate the effect of moisture on EC property. The bulky substituents lead to large inter-chain separation and facilitate the movement of counter ions leading to better ionic transport. Furthermore, with perfluoro-functionalized side groups, the PEDOT-F exhibits a water contact angle of 134.7°, significantly higher than that of PEDOT (57.8°), clearly indicating its hydrophobic property. This hydrophobic property of PEDOT-F can prevent it from damage by water within the electrolyte during redox reaction. Combining the advantages of better ionic transport and moisture resistance, the PEDOT-F reveals a better EC lifetime.