We synthesized two new alternating polymers, namely P(Tt-FQx) and P(Tt-DFQx), incorporating electron rich tri-thiophene and electron deficient 6-fluoroquinoxaline or 6,7-difluoroquinoxaline derivatives. Both polymers P(Tt-FQx) and P(Tt-DFQx) exhibited high thermal stabilities and the estimated 5% weight loss temperatures are 425 and 460 degrees C, respectively. Polymers P(Tt-FQx) and P(Tt-DFQx) displayed intense absorption band between 450 and 700 nm with an optical band gap (E-g) of 1.78 and 1.80 eV, respectively. The determined highest occupied/lowest unoccupied molecular orbital's (HOMO/LUMO) of P(Tt-DFQx) (-5.48 eV/-3.68 eV) are slightly deeper than those of P(Tt-FQx) (-5.32 eV/-3.54 eV). The polymer solar cells fabricated with a device structure of ITO/PEDOT:PSS/P(Tt-FQx) or P(Tt-DFQx):PC70BM (1:1.5 wt %) + 3 vol % DIO/Al offered a maximum power conversion efficiency (PCE) of 3.65% with an open-circuit voltage (V-oc) of 0.59 V, a short-circuit current (J(sc)) of 10.65 mA/cm(2) and fill factor (FF) of 59% for P(Tt-FQx)-based device and a PCE of 4.36% with an V-oc of 0.69 V, a J(sc) of 9.92 mA/cm(2), and FF of 63% for P(Tt-DFQx)-based device. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 545-552