Two new semiconducting polymers poly{4,8-bis(4-decylphenylethynyl)benzo[1,2-b:4,5-b']difuran} (P1) and poly {4,8-bis(4-decylphenylethynyl)benzo[1,2-b:4,5-b']difuran-alt-4,8-bis(4-decylphenylethynyl)benzo[1,2-b:4,5-b']dithiophene} (P2) have been synthesized. These polymers were tested in bulk heterojunction solar cells yielding power conversion efficiencies of 1.19% for P1 and 0.79% for P2. The surface morphology of the solar cell devices indicated that both the polymers display a granular morphology with smoother films displaying higher power conversion efficiencies. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012