Theoretical investigation of the structural and electronic properties of bilayer van der Waals heterostructure of Janus molybdenum di-chalcogenides – Effects of interlayer chalcogen pairing

This work presents a two-dimensional (2D) material system of van der Waals (vdW) bilayer heterostructures between Janus Molybdenum Di-chalcogenides, MoXY (X≠Y, X/YS, Se, Te). Subsequently, using first-principle calculations, the comparative structural and electronic properties of such bilayers are comprehensively investigated. In this context, four distinct interlayer stacking orientations are identified for each Janus vdW bilayer, and the influence of interlayer chalcogen pair specifications on the electronic properties is emphasized. The structural stabilities are quantified in terms of cohesive energy and interlayer interaction energy, and the structural properties are assessed from the bond length, bond angle, interlayer distance, and Mulliken charge. Next, the electronic properties of Janus vdW bilayers are comprehensively studied from the energy band structures with their constituent monolayer as well as atomic orbital projections and the total density of states (TDOS) profiles. In this context, the energy band structure and TDOS profiles are systematically analyzed in correlation with interlayer chalcogen pair specifications. Finally, the electronic properties of Janus vdW bilayers are benchmarked against their natural homogenous bilayer counterparts.