The synthesis and electrochemical properties of cathodic–anodic composite electrochromic materials

A series of electrochromic materials were synthesized by incorporating the cathodic material viologen with anodic materials phenothiazine, indole, morpholine, pyrrole and carbazole, respectively. Their electrochemical and electrochromic properties were investigated by cyclic voltammetry and UV–Visible spectrophotometer. Electrochromic devices based on these compounds were fabricated with an active area of 2 cm × 4 cm which exhibited colorless-wine-blue multicolor electrochromism. Their color and bleach reversibility was excellent with high coloration efficiency after 100 cyclic voltammetry. The response times for the coloring and bleaching processes were less than 150 ms and 2 s respectively, and the dominant response speed significantly exceeded that of viologen alone. Their remarkable electrochromic behaviour and high stability render these electrochromic materials excellent candidates for applications in electrochromic devices.