Band alignment and optoelectronic characteristics of 2D Janus heterostructures

Two-dimensional (2D) Janus semiconductor materials have attracted widespread research interest due to their unique asymmetric structures and promising optoelectronic applications. Here, we investigate the interfacial effects on band alignment and photodetection performance by constructing van der Waals heterostructures (vdWHs) based on monolayer CrS2 and Janus MoSO, alongside engineering the interlayer distance, biaxial strain, and external electric field. The S-terminated and O-terminated interfaces induce direct and indirect band structures, respectively, while maintaining a robust type-II band alignment. Moreover, the O-terminated interface vdWH photodetector exhibits higher photocurrent density and external quantum efficiency compared with the S-terminated counterpart. These results provide an effective strategy for designing interface-engineered optoelectronic devices based on 2D Janus semiconductors.