Two-Dimensional van der Waals Heterostructures Constructed via Perovskite (C₄H₉NH₃)₂XBr₄ and Black Phosphorus

Heterogeneous stacking of two-dimensional (2D) perovskites with other 2D materials is a very effective strategy for designing low-cost and high-performance photovoltaic and optoelectronic devices. The structural, electronic, and optical properties of distinctive all-2D M₂XBr₄-black phosphorus (BP) [M = (C₄H₉NH₃)⁺; X = Pb²⁺, Sn²⁺, Ge²⁺] van der Waals (vdW) heterostructures have been studied by first-principle calculations. The M₂SnBr₄-BP and M₂GeBr₄-BP heterostructures show type-II band arrangement; however, the M₂PbBr₄-BP heterostructure exhibits type-I band arrangement. The energy level shift is ascribed to the difference of work function between M₂XBr₄ monolayer and BP monolayer, driving the movement of carriers spontaneously. Furthermore, the BP layers can enhance the light absorption of the total heterostructures, especially the M₂GeBr₄-BP heterostructure. These results indicate the all-2D perovskite and BP vdW heterostructures are competitive candidates for low-dimensional photovoltaic and optoelectronic applications.