Donor-acceptor conjugated polymers based on p- and o-benzodifuranone and thiophene derivatives: electrochemical preparation and optical and electronic properties

A series of pi-conjugated polymers consisting of bis-EDOT or bis-EDTT units and p- or o-diphenylbenzodifuranones have been prepared electrochemically. The monomers and polymers were investigated using UV/vis absorption spectroscopy and cyclic voltammetry. The monomers were synthesized from 3,4-ethylenedioxythien-2-yl or 3,4-ethylenedithiathien-2-yl trimethylstannane and 3,7-bis(4-bromophenyl)benzo[1,2-b:4,5-b']difuran-2,6-dione or 3,6-bis(4-bromophenyl)benzo[1,2-b:6,5-b']difuran-2,7-dione using Stile coupling. The polymers exhibit broad absorption bands, and strong donor-acceptor characteristics with very small band gaps (in a range from 0.40 to 1.20 eV). Electrochemically grown polymer thin films exhibit reversible behavior under oxidative and reductive conditions. Under reduction, the polymer films show color changes from dark to almost transparent.