Optoelectronic properties and interfacial interactions of two-dimensional Cs2PbX4–MSe2 (M = Mo, W) heterostructures

Constructing 2D inorganic perovskites and TMDs heterostructures is an effective method to design stable and high-performance perovskites optoelectronic applications. Here, we investigate the optoelectronic properties and interfacial interactions of Cs2PbX4-MSe2 (X = Cl, Br, I; M = Mo, W) heterostructures using first-principles calculations. Firstly, six Cs2PbX4-MSe2 interfaces remain stable in energy. With the halogen varying from Cl to I, the interlayer distances of Cs2PbX4-MSe2 heterostructures increase rapidly. The CBM and VBM of monolayer Cs2PbX4 are all higher than that of monolayer MSe2 and the charges transfer from Cs2PbX4 interfaces to MSe2 interfaces when they contact. Both Cs2PbX4-MSe2 heterostructures are type-II heterostructures, which can drive the photogenerated electrons and holes to move in opposite directions. What's more, Cs2PbCl4-MoSe2 heterostructures exhibit the highest charge transport efficiency among Cs2PbX4-MoSe2 heterostructures because Cs2PbCl4-MoSe2 heterostructures have the lowest exciton binding energies among Cs2PbX4-MSe2 heterostructures. In addition, the optical absorptions of all heterostructures are significantly higher than the corresponding Cs2PbX4 monolayers and MSe2 monolayers. The construction of Cs2PbX4-MoSe2 heterostructures is beneficial for improving the photoelectric performance of two-dimensional perovskite devices. Lastly, we found that the Cs2PbI4-WSe2 heterostructure has the largest PCE (18%) among Cs2PbX4-MSe2 heterostructures. The Cs2PbCl4-MoSe2 heterostructure exhibits great potential application in photodetector devices and the Cs2PbI4-WSe2 heterostructure has great potential application in solar cells.