A novel donor-acceptor-type polymer with a low band-gap that alternates electron-rich thienylenevinylene groups with electron-deficient diketopyrrolopyrrole (DPP) units (PETVTDPP) has been synthesized by Pd-catalyzed Stille cross-coupling polymerization. The polymer shows a broad absorption band of wavelengths that range from 330 to 900 nm, and a low band-gap value of 1.43 eV. The field-effect mobility of an organic thin-film transistor based on this polymer is 0.05 cm(2) . Vs(-1). Bulk-heterojunction solar cells using a mixture of PETVTDPP and PC([71])BM for the active layer show a power conversion efficiency (PCE) of 1.94% under simulated AM 1.5 G solar irradiation at 100 mW . cm(-2).