Tunable transport mode of polaron in polarized Janus MoSSe few-layer structures: a constrained density functional theory study†

Abstract

The transport properties of polarons in a heterostructure are of great importance, since they can effectively affect the efficiency of photoelectric devices. However, the underlying mechanism of the polaron transfer rate and mode along intralayers or interlayers is still far from conclusive. Here, the stability and transport behaviors of polarons in polarized MoSSe few-layer structures were systematically investigated by constrained density functional theory (CDFT). It shows that the electron polarons in a MoSSe monolayer are more stable but have a smaller transfer rate than that of the hole polarons. Although the stability of the polarons will be slightly decreased by forming a parallel polarization heterostructure, the magnitude of the electron polaron transfer rate can be remarkably increased by 5 times and 71 times in their double- and three-layer case. In particular, it was unexpected to find that the original transfer mode along intralayer (in-plane) in monolayer can be completely overturned to along the interlayer (out-of-plane) by forming different stackings or increasing the MoSSe thickness. This unique behavior is strongly related to the polarization and the synergy effect of electronic coupling H_αβ and reorganization energy λ. Our findings offer a new perspective for the application of Janus MoSSe structures in optoelectronic devices and further advancement in the field of polarized low-dimensional materials.