Ultrafast interfacial charge transfer and superior photoelectric conversion properties in one-dimensional Janus-MoSSe/ WSe2 van der Waals heterostructures

One-dimensional (1D) van der Waals (vdW) heterostructures have attracted great attention due to their excellent photoelectric properties which potentially serve as key components for next-generation optoelectronic devices. However, investigations on the photoelectric conversion properties in 1D vdW heterostructures are still in the rudimentary stage. Addressing the mechanism of the role of flexoelectricity in nanotubes and electronegativity difference of Janus materials on photoelectric properties remains challenging. In this paper, we investigate the flexoelectric effect and electronegativity difference on the photoelectric properties of 1D Janus-MoSSe/${\mathrm{WSe}}_{2}$ vdW heterostructures and assess their potential for solar cells through the atomic-bond-relaxation approach combined with ab initio nonadiabatic molecular dynamics simulations. We find that a 1D MoSSe/${\mathrm{WSe}}_{2}$ vdW heterostructure with $\mathit{AB}1$ stacking configuration exhibits ultrafast interfacial charge transfer and superior photoelectric conversion properties owing to the beneficial effects of flexoelectricity and electronegativity difference. Specifically, the photogenerated electron (hole) transfer in the 1D MoSSe/${\mathrm{WSe}}_{2}$ system occurs quickly, within 55 (17) fs. Moreover, the optimal power conversion efficiency of 1D MoSSe/${\mathrm{WSe}}_{2}$ vdW heterostructure-based solar cells can reach up to 6.25%, which is significantly higher than those of 1D ${\mathrm{MoS}}_{2}/{\mathrm{WSe}}_{2}$ (5.45%) and 2D MoSSe/${\mathrm{WSe}}_{2}$ (1.94%). In this paper, we provide an effective strategy for the development of high-efficiency solar cells.