Photovoltaic and field effect transistor performance of selenophene and thiophene diketopyrrolopyrrole co-polymers with dithienothiophene

Here we report the synthesis of two new alternating co-polymers of thiophene and selenophene flanked diketopyrrolopyrrole with dithienothiophene. We find that the inclusion of the rigid fused dithienothiophene co-monomer affords semi-crystalline polymers, that exhibit promising ambipolar field effect transistor performance, with hole mobilities up to 0.23 cm(2) V-1 s(-1). The selenophene containing co-polymer exhibits a reduced band gap compared to the thiophene co-polymer, as a result of stabilisation of the polymer LUMO and destabilisation of the HOMO. The thiophene co-polymer exhibits promising solar cell performance in blends with PC71BM, with device efficiencies up to 5.1%.