Electrosynthesis and Characterization of Four Electrochromic Polymers Based on Carbazole and Indole-6-Carboxylic Acid and Their Applications in High-Contrast Electrochromic Devices

A carbazole (Cz)-based homopolymer and three copolymers based on Cz and indole-6-carboxylic acid (CIn) are electrodeposited on an indium tin oxide electrode. The electrochromic polymers are characterized using cyclic voltammetry and scanning electron microscopy. Four electrochromic devices (ECDs) are fabricated using the four Cz- and CIn-based polymers as the electrochromic materials of the coloring electrodes, poly(3,4-(2,2-dimethylpropylenedioxy)thiophene) (PProDOT-Me2) as the electrochromic material of the complementary electrodes, and hybrid polymer electrolytes as the gel electrolytes. The ECD with anodic copolymer P(Cz4-co-CIn1) with a Cz/CIn feed molar ratio of 4/1 has the highest contrast (32%) and coloring efficiency (372.7 cm2·C−1) at 575 nm. In addition, this ECD has satisfactory optical memory and redox stability.