Wide band gap pyrrolo[ 3,4-c] pyrrole-1,3(2H, 5H)-dione (PPD)-based alternating polymer, P(BDTT-ttPPD) was synthesized by combining electron-rich 4,8-bis(5-(2-ethylhexyl) thiophen-2-yl) benzo[ 1,2-b: 4,5-b'] dithiophene (BDTT) and electron-deficient 4,6-bis(2-bromothieno[ 3,2-b] thiophen-5-yl)-5-octyl-2-(2octyldodecyl) pyrrolo[ 3,4-c] pyrrole-1,3(2H, 5H)-dione (ttPPD). When the P(BDTT-ttPPD) polymer was applied to binary polymer solar cells (PSCs) as a donor material, the device exhibited a maximum power conversion efficiency (PCE) of 6.93% with an open-circuit voltage (Voc) of 0.87 V, a short-circuit current (Jsc) of 11.38 mA/cm(2), and a fill factor (FF) of 70%. The photovoltaic performance was further improved to 9.08% (Voc similar to 0.80 V, Jsc similar to 16.05 mA/cm(2), and FF similar to 71%) when the polymer was used as a donor component for absorbing high-energy light in ternary PSCs with a blend of P(BDTT-ttPPD): PTB7Th: PC70BM. The overall PCE of ternary PSCs was found to be higher than those of the binary PSCs made form P(BDTT-ttPPD) or PTB7-Th. We discuss the property modulation of PPD-based polymers via the replacement of thiophene pespacer units with thieno[ 3,2-b] thiophene. (C) 2017 Elsevier Ltd. All rights reserved.