New donor-acceptor (D-A) polymers, poly(4,5-bis(2-octyldodecyloxy) naphto[2,1-b: 3,4-b'] dithiophenebenzo[c][1,2,5]-thiadiazole) (PNDT-B) and poly(4,5-bis(2-octyldodecyloxy) naphto [2,1-b: 3,4-b'] dithiophene-4,7-di(thiophen-2-yl) benzo[c][1,2,5]thiadiazole) (PNDT-TBT), with the extended pi-electron delocalization of naphtho[2,1-b: 3,4-b'] dithiophene, were successfully synthesized by Suzuki and Stille coupling reactions. The structure and physical properties of polymers were characterized by DFT calculation, UV-vis absorption, cyclovoltammetry, TGA and DSC analyses. X-ray diffraction studies indicated a relatively highly ordered intermolecular structure in PNDT-TBT after annealing. This high degree of molecular order resulted from the crystallinity and increasing planarity, provided by the thiophene linker groups and the interdigitation of the long alkoxy side chains. The new D-A polymer, PNDT-TBT, exhibited a p-type carrier mobility of 0.028 cm(2)/Vs and an on/off ratio of 5.9 x 10(3). (C) 2015 Wiley Periodicals, Inc.