Molecular dyads based on polycyclic electron donor (D) and electron acceptor (A) units represent suitable building blocks for forming highly ordered, solution-processable, nanosegregated D-A domains for potential use in (opto)electronic applications. A new dyad, based on alkyl substituted hexa-peri-hexabenzocoronene (HBC) and perylene monoimide (PMI) separated by an ethinylene linker, is shown to have a high tendency to self-assemble into ordered supramolecular arrangements at multiple length scales: macroscopic extruded filaments display long-range crystalline order, nanofiber networks are produced by simple spin-coating, and monolayers with a lamellar packing are formed by physisorption at the solution-HOPG interface. Moreover, highly uniform mesoscopic ribbons bearing atomically flat facets and steps with single-molecule heights self-assemble upon solvent-vapor annealing. Electrical measurements of HBC-PMI films and mesoscopic ribbons in a transistor configuration exhibit ambipolar transport with well balanced p- and n-type mobilities. Owing to the increased level of order at the supramolecular level, devices based on ribbons show mobility increases of more than one order of magnitude.