Exploring a high-carrier-mobility black phosphorus/MoSe2 heterostructure for high-efficiency thin film solar cells

Transition metal dichalcogenides (TMDCs) with self-passivated surfaces, suitable bandgaps and high optical absorption coefficients are very promising for thin film solar cells, but seriously hindered by low carrier mobility. Herein, we propose interface-engineered two-dimensional van der Waals heterostructure composed of high-carrier-mobility black phosphorus (BP) layer and MoSe2 layer, and demonstrate a new-type BP/MoSe2 heterostructure thin film solar cell with high efficiency. The electronic structure and optical properties of both BP/MoSe2 and BP/MoS2 heterostructures are systematically investigated. Compared with BP/MoS2 heterostructure, BP/MoSe2 heterostructure shows enhanced photoelectric characteristics. Additionally, BP/MoSe2 heterostructure has greater light absorption intensity as well as a wider absorption range, achieving a much higher power conversion efficiency of up to 23.04%. It is found that the built-in electric field at the interface of BP/MoSe2 heterostructure accelerates the separation of electron-hole pairs. This work provides a feasible strategy for using the BP/MoSe2 heterostructure for next-generation high-specific-power thin film solar cells.