Programmable fabrication of monodisperse graphene nanoribbons via deterministic iterative synthesis

While enormous progress has been achieved in synthesizing atomically precise graphene nanoribbons (GNRs), the preparation of GNRs with fully predetermined length and monomer sequence remains an unmet challenge. Here we report a fabrication method that provides access to structurally diverse and monodisperse “designer” GNRs through utilization of an iterative synthesis strategy, in which a single monomer is incorporated into an oligomer chain during each chemical cycle. Surface-assisted cyclodehydrogenation is subsequently employed to generate the final nanoribbons, and bond-resolved scanning tunneling microscopy is utilized to characterize them.