Three new low bandgap conjugated copolymers with 3,4-ethylenedioxythiophene (EDOT) as donor and 2,3-bis(4-octyloxyphenyl)-quinoxaline (P1), 2,3-bis(4-octyloxyphenyl)-thiadiazol-quinoxaline (P2, P3) as acceptors were synthesized by Stille cross-coupling reaction, and their optical and electrochemical properties were studied. These polymers exhibited optical bandgap of 1.77, 1.29 and 1.13 eV, for P1, P2 and P3, respectively. Photovoltaic cells with device configuration of ITO/PEDOT: PSS/Copolymer: PCBM (1:4 w/w)/LiF/Al were fabricated. The measurements revealed an open-circuit voltage (V-oc) of 0.52 V. short-circuit current density (J(sc)) of 3.24 mA/cm(2) and power conversion efficiency (PCE) of 0.60% for P1, and showed a V-OC of 0.33 V. J(sc) of 2.11 mA/cm(2), PCE of 0.39% for P2. (C) 2010 Elsevier Ltd. All rights reserved.