A new high-performing small molecule n-channel semiconductor based on diketopyrrolopyrrole (DPP), 2,2′-(5,5′-(2,5-bis(2-ethylhexyl)-3,6-dioxo-2,3,5,6-tetrahydropyrrolo[3,4-c]pyrrole-1,4-diyl)bis(thiophene-5,2-diyl))bis(methan-1-yl-1-ylidene)dimalononitrile (DPP-T-DCV), is successfully synthesized. The frontier molecular orbitals in this designed structure are elaborately tuned by introducing a strong electron-accepting functionality (dicyanovinyl). The well-defined lamellar structures of the crystals display a uniform terrace step height corresponding to a molecular monolayer in the solid-state. As a result of this tuning and the remarkable crystallinity derived from the conformational planarity, organic field-effect transistors (OFETs) based on dense-packed solution-processed single-crystals of DPP-T-DCV exhibit an electron mobility (μe) up to 0.96 cm2 V−1 s−1, one of the highest values yet obtained for DPP derivative-based n-channel OFETs. Polycrystalline OFETs show promise (with an μe up to 0.64 cm2 V−1 s−1) for practical utility in organic device applications.