Two new tercopolymers (RP1 and RP2) containing electron-donating benzodithiophene, weak electron-accepting pyrrolo[3,4-c]pyrrole-1,3-dione derivative and strong electron-accepting 5,6-difluorobenzothiadiazole derivative were prepared. The opto-electrical studies showed that RP1 and RP2 displayed identical optical band gaps (E (g) similar to 1.72 eV) and highest occupied/lowest unoccupied molecular orbital energy levels (HOMO/LUMO similar to -5.32 eV/-3.60 eV). The polymer solar cells prepared with the configuration of ITO/PEDOT:PSS/RP1:PC70BM (1:1.5 wt%) + 3 vol% DIO/Al and ITO/PEDOT:PSS/RP2:PC70BM (1:1.5 wt%) + 3 vol% DIO/Al exhibited a maximum power conversion efficiency (PCE) of 5.16% (V (oc) similar to 0.76 V, J (sc) similar to 10.93 mA/cm(2), and FF similar to 0.62) and a PCE of 3.56% (V (oc) similar to 0.67 V, J (sc) similar to 9.67 mA/cm(2), and FF similar to 0.55), respectively.