The effects of interfacial atoms and stacking configurations on the electronic properties of Janus TMD heterostructures.

The structural asymmetry of Janus transition metal dichalcogenides gives rise to physical properties distinct from those of their symmetric counterparts. When Janus transition metal dichalcogenides are vertically stacked, their resulting heterostructure exhibits novel and enhanced electronic properties due to interactions between interfacial atoms, changes in electric dipole moments, and van der Waals interlayer interactions. In this study, we employ first-principles calculations based on density functional theory using the Vienna Ab initio Simulation Package to investigate the electronic properties of MoSSe-WSSe vertical Janus transition metal dichalcogenides heterostructures. By analyzing the density of states, charge density distribution, formation energy, bandgap, band alignment, and dipole moment, we identify key factors governing the electronic behavior of these heterostructures. Our calculation identifies the most favorable interfacial configuration and stacking type for synthesis. Furthermore, while the bandgap type is primarily dictated by the composition of interfacial atoms irrespective of the stacking type, its magnitude is influenced by both the interfacial atomic composition and stacking configuration. Notably, the total dipole moment is not merely the arithmetic sum of the dipole moments of the individual layers; rather, it is influenced by the interlayer coupling between the two layers. This trend can be explained by variations in the charge density distribution as a function of interlayer spacing. These findings suggest that the electronic properties of Janus heterostructures can be effectively tuned by modifying the interfacial atomic composition, stacking configuration, and interlayer distance, highlighting their potential for next-generation nanoelectronic applications.