Two new alternating copolymers. PCT-10,13-BPz (P1) and PCT-2,7-BPz (P2), which were constructed from the same monomers and only different in the connecting points, were synthesized via Suzuki coupling reaction. The UV-vis absorptions, thermal stability, energy levels, field-effect carrier mobility and photovoltaic characteristics of the two copolymers were systematically evaluated to understand the relationships between the polymer structure at the molecular level and the photovoltaic performances. Photovoltaic cells based on the two copolymers with a structure of ITO/PEDOT : PSS/Polymer : PC71BM/PFN/Al exhibited PCEs of 4.31% and 0.64%, respectively, under one sun of AM1.5 solar simulator illumination (100 mW cm-2).
