A copolymer comprising 1,4-diketopyrrolo [3,4-c]pyrrole (DPP) and thieno[3,2-b]thiophene moieties, PDBT-co-TT, shows high hole mobility of up to 0.94 cm(2) V-1 s(-1) in organic thin-film transistors. The strong intermolecular interactions originated from pi-pi stacking and donor-acceptor interaction lead to the formation of interconnected polymer networks having an ordered lamellar structure, which have established highly efficient pathways for charge carrier transport.