Unlocking the Solution Processability of Graphene Nanoribbons via a Solvent-Assisted Direct Fluorination

This work introduces a solvent-assisted direct fluorination strategy that enables the selective functionalization of graphene nanoribbons (GNRs), yielding fluorinated GNRs (FGNRs) with semi-ionic C-F bonds. The incorporated fluorine atoms effectively suppress the inter-ribbon aggregation through electrostatic repulsion and enhance the interaction between GNRs and solvents, thereby facilitating efficient exfoliation and markedly improving dispersion stability in organic solvents. Consequently, the solubility of FGNRs in tetrahydrofuran reaches 1 mg mL^-1, indicating enhanced solution processability. Optical spectroscopy reveals a pronounced near-infrared photoluminescence exhibiting an average fluorescence lifetime of ∼1.58 μs along with a slight widening of the optical band gap from 1.02 eV for the unfluorinated one to 1.10 eV in FGNRs. Benefiting from the greatly improved solubility, we successfully fabricated graphene-based molecular devices based on FGNRs. Electrical measurements show that these devices retain their intrinsic charge transport capability at room temperature. Variable-temperature transport measurements reveal a transition from thermally activated conduction to vibration-assisted coherent quantum tunneling as temperature decreases. This work offers a generalizable strategy to overcome GNR processability challenges, paving the way for their applications in molecular electronics.