Alternate donor-acceptor small-band-gap semiconducting polymers; Polysquaraines and polycroconaines

Abstract The idea that conjugated polymers with alternate donor and acceptor moieties in the main chain are characterized by a small band gap is proposed and explained. Experimental verification of this idea is reported in new classes of conjugated polymer semiconductors, polysquaraines and polycroconaines. These new materials show band gaps down to 0.5 eV, conductivities around 10−5 S/cm and are stable in air up 250°C or higher.