Three new alternating conjugated D-A polymers P1, P2, and P3 are reported. They entail a new expanded conjugated framework that is derived from naphthalene diimide (NDI) possesses planar structure and moderate electron-accepting capacity. Benzo[1,2-b:4,5-b']dithiophene with alkoxyl and alkyl chains and thiophene are the respective electron-donating moieties. These conjugated polymers are thermally stable under 325 degrees C based on their TGA data. P1, P2, and P3 exhibit similar HOMO (ca. -5.39 to -5.43 eV) and LUMO (ca. -3.58 to -3.59 eV) energies according to their absorption spectra and redox potentials. The results reveal that P1, P2, and P3 can be solution-processed, and the resulting OTFTs exhibit hole mobilities in the range of (1.3-3.0) x 10(-3) cm(2) V-1 s(-1) and current on/off ratios of 10(5)-10(7) after conventional thermal annealing. Notably, hole mobilities of thin films of P2 and P3 increase to 0.024 and 0.135 cm(2) V-1 s(-1), respectively, upon solvent vapor annealing.