Edge electronic structure of unilateral sawtooth Janus graphene nanoribbons

Abstract Traditional graphene nanoribbons (GNRs) generally exhibit small bandgaps and limited edge state modulation methods in electronic devices. Drawing on the design concept of introducing interface asymmetry via Janus structures in nano catalytic systems, this study constructs unilateral Janus zigzag GNRs (JZGNRs) and systematically investigates their electronic structures and edge state properties using spin-polarized density functional theory. The calculation results show that unilateral Janus modification can effectively open the nearly zero bandgap of symmetrically hydrogenated GNRs to approximately 0.41 eV, induce the formation of an indirect bandgap, significantly shift the edge state electron cloud toward the heteroatom side, and enhance the spin splitting energy. Under the action of an external electric field and uniaxial strain, the bandgap can be continuously tuned within the range of approximately 0.05–0.68 eV. A transition from indirect to direct bandgap occurs under a certain tensile strain, accompanied by charge redistribution between the edges on both sides. The above results indicate that introducing Janus heterogeneous interfaces into one-dimensional zigzag GNRs (ZGNRs) facilitates the synergistic realization of bandgap engineering and edge state modulation in the same structure, providing a new feasible scheme for the design of graphene-based nanoelectronics and spintronic devices.