Photovoltaic and field effect transistor performance of selenophene and thiophene diketopyrrolopyrrole co-polymers with dithienothiophene - Shahid,M; Ashraf,RS; Huang,Z; Kronemeijer,AJ; McCarthy-Ward,T; McCulloch,I; Durrant,JR; Sirringhaus,H; Heeney,M (JOURNAL OF MATERIALS CHEMISTRY, 2012)