Solution-phase synthesis of graphene nanoribbons: a review on polymerization strategies

Abstract

A promising approach to opening the band gap of intrinsic graphene is through the synthesis of graphene nanoribbons (GNRs)—quasi-one-dimensional (1D) cutouts of the graphene sheet whose electronic and physical properties are governed by edge structure, chemical modifications, and backbone doping or pore integration. GNRs can be synthesized using both top-down and bottom-up approaches, with solution-phase synthesis emerging as a particularly attractive bottom-up method due to its advantages in diverse edge functionalization, possibilities in gram-scale production and characterization using various spectroscopy techniques, as well as exploration in practical applications. Solution-phase synthesis of GNRs typically involves a polymerization step followed by cyclodehydrogenation to form the final structure. This review provides an overview of the different polymerization strategies employed in GNRs solution-phase synthesis, highlighting their recent advancements and unique advantages. The Diels–Alder reaction enables the synthesis of GNRs with considerable lengths (up to 600 nm) and tunable edge functionalization. Suzuki polymerization facilitates the creation of porous GNRs while preserving heterostructures for post-synthetic modifications, whereas Yamamoto polymerization allows for the efficient production of laterally extended GNRs with varying bandgaps. Additionally, we discuss alternative cyclodehydrogenation methods, including photochemical approaches, for transforming polymer precursors into GNRs. By consolidating recent progress in solution-phase polymerization techniques, this review aims to provide valuable insights for the development of next-generation GNRs with tailored properties for electronic and optoelectronic applications.