First-principles study on optoelectronic properties of Cs2PbX4-PtSe2 van der Waals heterostructures

In order to achieve low-cost, high efficiency and stable photoelectric devices, two-dimensional (2D) inorganic halide perovskite photosensitive layers need to cooperate with other functional layers. Here, we investigate the structure, stability and optical properties of perovskite and transition metal dichalcogenide (TMD) heterostructures using first-principles calculations. Firstly, Cs2PbX4-PtSe2 (X = Cl, Br, I) heterostructures are stable because of negative interface binding energy. With the halogen varying from Cl to I, the interface binding energies of Cs2PbX4-PtSe2 heterostructures decrease rapidly. 2D Cs2PbCl4-PtSe2, Cs2PbBr4-PtSe2 and Cs2PbI4-PtSe2 heterostructures have an indirect bandgap with the value of 1.28, 1.02, and 1.29 eV, respectively, which approach the optimal bandgap (1.34 eV) for solar cells. In the contact state, the electrons transfer from the PtSe2 monolayer to Cs2PbX4 monolayer and only the Cs2PbBr4-PtSe2 heterostructure maintains the type-II band alignment. The Cs2PbBr4-PtSe2 heterostructure has the strongest charge transfer among the three Cs2PbX4-PtSe2 heterostructures because it has the lowest tunnel barrier height (Delta T) and the highest potential difference value (Delta EP). Furthermore, the light absorption coefficient of Cs2PbX4-MSe2 heterostructures is at least two times higher than that of monolayer 2D inorganic halide perovskites. With the halogen varying from Cl to I, the light absorption coefficients of the Cs2PbX4-PtSe2 heterostructures increase rapidly in the visible region. Above all, the Cs2PbX4-MSe2 heterostructures have broad application prospects in photodetectors, solar cells and other fields.

Automated summary

By employing first-principles calculations, we investigate the structure, stability, and optical properties of perovskite and transition metal dichalcogenide (TMD) heterostructures, and find their potential applications in photoelectric devices.