We investigated the performance of ambipolar field-effect transistors based on a series of alternating low band gap polymers of oligothiophene and diketopyrrolopyrrole (pDPPT3-HD, pDPPT3-OD, pDPPT2TT-HD, and pDPPT2TT-OD). Herein, we report the high carrier mobilities and the good correlation between the interchain stacking of polymers and their device performance.