Thickness Dependent Ultrafast Charge Transfer in BP/MoS_2 Heterostructure

摘要

Constructing high-performance-2D heterostructures and deciphering the underlying microscopic mechanism of carrier dynamics are crucial in optoelectronic and photovoltaic applications. Here, taking black phosphorus (BP)/MoS_2 heterostructure with type-Ⅱ band alignment as a prototypical example, the ab initio nonadiabatic molecular dynamics simulations demonstrate that the interlayer carrier dynamics are thickness dependent. Specifically, the electron transfer from a monolayer (1L)-BP to MoS_2 occurs quickly within 54 fs. In contrast, hole transfer can only be observed within 1 ps with BP’s layer number N ≥ 2, triggered by the excitation of low-frequency acoustic phonon and interlayer shear and breathing phonon modes within 100 cm~(-1) that enhances the interlayer coupling. Particularly, the electron and hole transfer time exhibits respectively linear and exponential dependence on the layer number N of BP component. The present findings shed new light on improving the process of ultrafast carrier dynamics of 2D heterostructures for photoconversion.