Ultrafast charge transfer in two-dimensional black phosphorus/SiS van der Waals heterostructure for photoconversion

The construction of two-dimensional (2D) van der Waals (vdW) heterostructures is a promising strategy for developing advanced optoelectronic and photovoltaic devices. In this work, we first construct a 2D van der Waals heterostructure composed of black phosphorus (BP) and Pma2-SiS with type-II band alignment. Then, we employ ab initio nonadiabatic molecular dynamics based on the HSE06 hybrid functional to investigate its interfacial charge transfer dynamics. Our computational results reveal that the ultrafast hole transfer takes within 156 fs, whereas the electron transfer is suppressed greatly. Further analysis reveals that the ultrafast hole transfer process is driven by two key factors: the availability of sufficient hole transfer pathways at the interface to effectively accept the photoexcited holes, and the strong electron–phonon coupling originating from the interlayer shear mode along the zigzag direction as well as the optical phonon modes of BP. These findings provide valuable insights into the charge transfer dynamics in 2D vdW heterostructures and guide the design of high-performance optoelectronic and photovoltaic devices.