Electrochromism in multichromic conjugated polymers: Thiophene and azobenzene derivatives on the main chain

Novel donor-acceptor-donor type polymers containing azobenzene group in polymer backbone chains were synthesized and their electrochromic properties were investigated. To increase the strength of the acceptor unit, fluorinated azobenzene containing donor-acceptor-donor type polymer was also synthesized. Cyclic voltammetry and spectroelectrochemistry studies showed that poly((E)-1,2-bis(4-(4-hexylthiophen-2-yl)phenyl)diazene) (P2) and poly((E)-1,2-bis(2-fluoro-4-(4-hexylthiophen-2-yl)phenyl)diazene) (P3) were multichromic and the polymer containing fluorine group showed p- and n-doping properties, hence they are promising candidates for various applications.

► The first use of azobenzenes in the polymer backbone for electrochromism is reported.
► One of the polymers has n-doping property.
► The polymers are found to be multichromic.