Mixed ion-electron conducting PEO/PEDOT: PSS miscible blends with intense electrochromic response

Aqueous solution processable PEDOT: PSS is promising for electrochromic applications. However, dense morphology with few ion paths usually results in low optical contrast and slow electrochromic response. Herein, polyethylene oxide (PEO) was simply blended with PEDOT: PSS aqueous dispersion to promote ion diffusion and thus electrochromic performance. The PEO is miscible with PEDOT: PSS in the blends due to molecular interactions, corresponding to the increase in the grain size and the decrease in the melting point of the PEO component. The electrochemical activity of PEDOT chains in the blends is remarkably enhanced with the incorporation of 40 wt% PEO fraction, resulting in the significant change in the transmittance (64%) between oxidized and reduced states. Meanwhile, the response time is within 1 s for both coloring and bleaching, accompanied by a high coloration efficiency of 269.1 cm(2)/C.