▎ 摘　　要

We have developed a synthetic approach to graphene nanoribbons by using butadiyne-containing monomers that are initially converted to polydiacetylenes via topochemical polymerization in the crystal. Subsequent aromatization of the isolated polydiacetylenes at surprisingly mild temperatures affords graphene nanoribbons similar to 1.36 nm in width with a 1.4 eV bandgap. These transformations take place solely in the solid state, in contrast to published on-surface or in-solution methods. This synthetic approach is well suited for electronic-device fabrication processes because it requires only UV light or heating and no external chemical reagents.