  Van der Waals (vdW) heterobilayers formed by two-dimensional (2D) transition
metal dichalcogenides (TMDCs) created a promising platform for various
electronic and optical properties. ab initio band results indicate that the
band offset of type-II band alignment in TMDCs vdW heterobilayer could be tuned
by introducing Janus WSSe monolayer, instead of an external electric field. On
the basis of symmetry analysis, the allowed interlayer hopping channels of
TMDCs vdW heterobilayer were determined, and a four-level kp model was
developed to obtain the interlayer hopping. Results indicate that the
interlayer coupling strength could be tuned by interlayer electric polarization
featured by various band offsets. Moreover, the difference in the formation
mechanism of interlayer valley excitons in different TMDCs vdW heterobilayers
with various interlayer hopping strength was also clarified.
