Accelerated iterative synthesis of ultralong graphene nanoribbons with full atomic precision

Graphene nanoribbon (GNR) properties are dominated by structural variables, such as edge structure, length, width, and heteroatom-doping, all requiring atomic precision to harness the full application potential of GNRs. Although the length influences key GNR properties, synthetic methods that allow control over the length remain underdeveloped, and the effects of length on GNR properties remain underexplored. Herein, we report an accelerated iterative approach enabling the synthesis of a series of length-controlled, ultralong atomically precise GNRs. The longest GNR displays a 920-atoms core with a 35.8-nm long (147 linearly fused rings) backbone that has been obtained in just three synthetic steps from building blocks of ∼2 nm in length. The unprecedented solubility of this set of GNRs enables their purification by column chromatography and their investigation by a broad range of structural, optoelectronic, and redox characterization techniques. In addition, this GNR length control allows us to unambiguously establishing correlations between GNR length and properties, particularly electrical conductivity.