Development and characterization of a flexible electrochromic device based on polyaniline and enzymatically synthesized poly (gallic acid)

•A novel electrochromic device has been produced using enzymatically synthesized polygallic acid component.•Highly dispersed in water conducting polyaniline (PANI) complex has been successfully achieved.•The conductive PANI-PGAL has remarkably high thermal resistance.•The novel PANI-PGAL complex-based EDC showed electrochemical reversibility.

An effective polyaniline-based electrochromic device was successfully achieved using the enzyme-mediated poly (gallic acid) as a polyaniline polymerization template. Poly (gallic acid) proved non-toxic upon the conducted cytotoxicity assays. Thermogravimetric analysis of the novel polyaniline-poly (gallic acid) complex displayed a remarkable increase in thermal stability compared to polyaniline-HCl doped, polyaniline-poly (styrene sulfonate), polyaniline-poly (isobutylene-alt-maleic anhydride) complexes. Polyaniline-poly (gallic acid) water dispersion was readily processed by spray-coating on indium tin oxide-poly (ethylene terephthalate) sheet. These novel electrode was employed as an electroactive layer in flexible electrochromic device with propylene carbonate-poly (methyl methacrylate)-LiClO4 polymer electrolyte. The transmittance of the electrochromic device at 650 nm in a wide voltage range varied from 59% (−0.87 V) to 37.1% (+0.33 V) giving an optical contrast of 22% and a life up to 700 cycles.

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