A series of monomers were synthesized via Stille coupling to obtain low-band gap conjugated polymers namely poly(5,6-bis(octyloxy)-4,7-di(thieno[3,2-b]thiophen-2-yl)benzo[c][1,2,5]oxadiazole (PTTBO)), poly(5,6-bis(octyloxy)-4,7-di(selenophen-2-yl)benzo[c][1,2,5]oxadiazole (PSBO)) and poly(5,6-bis(octyloxy)-4,7-di(furan-2-yl)benzo[c][1,2,5]oxadiazole (PFBO)) which comprise electron-rich thieno[3,2b]thiophene (TT), selenophene and furan, as the donor units in conjugation with electron-deficient 2,1,3-benzooxadiazole (BO) moiety as the acceptor unit. All three polymers were synthesized electrochemically and well characterized. These polymers exhibited broad spectral absorptions, low-lying highest occupied molecular orbital (-5.71, -5.88, -5.76 eV), and as well as low band gap ranging from 1.45 eV to 1.56 eV. Introducing different donor moieties on the polymer backbone provides to alter the optoelectronic properties. (C) 2015 Elsevier B.V. All rights reserved.