A series of four dihydropyrroloindoledione-based organic semi-conducting polymers are examined for performance in transistor and photovoltaic cell devices. The dihydropyrroloindoledione unit was alternately copolymerized with phenyl, thiophene and bithiophene comonomers, and the resultant polymers exhibit broad absorption, low-bandgaps and deep energy levels, with charge carrier mobilities approaching 0.1 cm2 V−1 s−1. Solar cells processed in a printing friendly solvent (m-xylene) exhibited >2% PCE with a high fill-factor of 0.62 and Voc of 0.75 V.