Synthesis and optoelectrochemical properties of a magenta-to-transmissive electrochromic polymer based on 3, 4-dioxythiophene

A new magenta-to-transmissive electrochromic polymer, poly(3,4-bis(3-bromopropoxy)thiophene) (PBBrPOT) was synthesized by electrochemical polymerization and its electrochromic properties were characterized in detail. Compared with the representative "large-volume alkyl substituents" strategy, herein we use bromines as the end-capping groups of two propoxyl substituents on the 3- and 4- position of the thiophene ring to introduce more steric repulsion within the polymer chains, and therefore obtain a magenta neutral state of the polymer. The PBBrPOT film shows a set of reasonable electrochromic features, including low driving potentials (−0.1 V and 0.9 V), appropriate transmittance change (38% at 556 nm), but a relatively longer response time in bleaching process (t95 = 6.5 s).