Facile Approach of Porous Electrochromic Polyamide/ZrO₂ Films for Enhancing Redox Switching Behavior

Porous redox-active polyamide hybrid films have been successfully prepared to enhance the electrochromic (EC) properties in this report comparing with salt-caused porous films and hybrid films obtained via in situ sol-gel reaction of hydroxyl groups and zirconium dioxide (ZrO₂). With the assistance of porous and hybrid structures, the diffusion rate of counterions between electrolyte and EC species could be effectively increased, and the charges could be delivered and stored between the donor-acceptor system constructed by the organic-inorganic hybrid during the electrochemical process. Furthermore, there would be a synergistic effect while combining the porous structure and hybrid system together, which can improve the EC behaviors much more obviously; that is, the enhancement of porous hybrid films is more than that of porous films and hybrid films individually. For further application, the porous hybrid films were fabricated into devices, which exhibit a lower oxidation potential (from 1.07 to 0.94 V) and shorter switching response time (from 81.3 to 9.7 s for coloring time and from 44.7 to 20.8 s for bleaching time) with good electrochemical stability. Consequently, these results indicate that the EC properties could be enhanced and improved dramatically by the facile approach of merging the porous structure and hybrid system.