All-in-one multicolor electrochromic devices on the basis of benzene-centered 1,3,5-tris(4-pyridylium) bromides

In the field of electrochromism , multicolor systems have ever been explored due to their potential applications in areas such as electrochromic displays. In this work, two benzene-centered organic salts, 4,4′,4''-(benzene-1,3,5-triyl)tris(1-propylpyridylium) bromide TPP 3+ 3Br − and 4,4′,4''-(benzene-1,3,5-triyl)tris(1-benzylpyridylium) bromide TBP 3+ 3Br −, were successfully synthesized and further incorporated as electrochromic materials to fabricate gel based all-in-one electrochromic devices (ECDs), respectively. It was found that, the ECDs based on these two materials displayed multicolor electrochromic behaviors, optical contrast was unambiguously exceeded 67.9%, coloration efficiency was as high as 327.7 cm 2 /C, and coloring voltage was less than −1.2 V. Considering the overall electrochromic performances of the 1,3,5-tris(4-pyridylium) bromides, it is expected that the multicolor ECDs may be applicable in the development of electrochromic enhancement of latent fingerprint based on the principle of color contrast for those deposited on the conductive and nonconductive substrates with a series of colors.