Electronic structure of strain-tunable Janus WSSe–ZnO heterostructures from first-principles

Van der Waals (vdW) heterostructures, which are stacks of different types of 2D materials, offer the possibility to further tune and optimize the electronic properties of 2D materials. The electronic structure of semiconducting 2D materials, such as monolayer transition metal dichalcogenides (TMDs), are known to be tunable via environment and external fields. In this study, we calculate the structure and electronic characteristics of a vdW heterostructure of Janus monolayer WSSe and monolayer ZnO, both of which have out of plane dipole moments. Calculations are made and analysis is done to determine how this heterostructure's band edge energies and dipole moments are affected by alignment, biaxial and uniaxial strain, orientation, and electric field. We discover that the out-of-plane dipole moment of the ZnO monolayer is extremely sensitive to strain, resulting in the broad tunability of the heterostructure band edge energies over a range of experimentally relevant strains. The use of strain-tunable 2D materials to control band offsets and alignment is a general strategy applicable to other vdW heterostructures, one that may be advantageous in the context of clean energy applications, including photocatalytic applications, and beyond.