Benzodithiophene and thienopyrroledione containing two random copolymers were designed and synthesized. Electrochemical and optical studies prove that these copolymers could be candidates for organic solar cells applications. The HOMO and LUMO values were determined using cyclic voltammetry as -5.53 and -3.43 eV for P1 and -5.54 and -3.53 eV for P2, respectively. The optical band gaps of the polymers were calculated as 2.10 and 2.01 eV using UV-VIS spectroscopy for P1 and P2, correspondingly. Bulk-heterojunction solar cells were constructed with the configuration of ITO/PEDOT:PSS/Polymer:PC71BM/LiF/Al and the synthesized polymers were used as the electron donors and PC71BM as the electron acceptor in the active layer. The best performance was observed for device of P2 1:2 (w:w) ratio with a V-oc 0.80 V, a J(sc) of 14.02 mA/cm(2), a fill factor of 52%, and a PCE of 5.83% under standard AM 1.5 G at 100 mW/cm(2). (C) 2017 Elsevier Ltd. All rights reserved.