New moderate bandgap polymers containing alkoxysubstituted‐benzo[c][1,2,5]thiadiazole and thiophene‐based units

Alkoxysubstituted benzo[c][1,2,5]thiadiazole electron accepting units were prepared and copolymerized with various thiophene‐based electron donating monomers to produce new low bandgap polymers P1–4. The materials showed broad absorption in the range from 300 to 700 nm with bandgaps below 2 eV in solution. Efficiencies of over 1% were obtained from photovoltaic cells using P4 with PCBM as acceptor.