Optoelectronic properties and interfacial interactions of two-dimensional Cs 2 PbX 4 -MSe 2 (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 Cs 2 PbX 4 -MSe 2 (X = Cl, Br, I; M = Mo, W) heterostructures using first-principles calculations. Firstly, six Cs 2 PbX 4 -MSe 2 interfaces remain stable in energy. With the halogen varying from Cl to I, the interlayer distances of Cs 2 PbX 4 -MSe 2 heterostructures increase rapidly. The CBM and VBM of monolayer Cs 2 PbX 4 are all higher than that of monolayer MSe 2 and the charges transfer from Cs 2 PbX 4 interfaces to MSe 2 interfaces when they contact. Both Cs 2 PbX 4 -MSe 2 heterostructures are type-II heterostructures, which can drive the photogenerated electrons and holes to move in opposite directions. What's more, Cs 2 PbCl 4 -MoSe 2 heterostructures exhibit the highest charge transport efficiency among Cs 2 PbX 4 -MoSe 2 heterostructures because Cs 2 PbCl 4 -MoSe 2 heterostructures have the lowest exciton binding energies among Cs 2 PbX 4 -MSe 2 heterostructures. In addition, the optical absorptions of all heterostructures are significantly higher than the corresponding Cs 2 PbX 4 monolayers and MSe 2 monolayers. The construction of Cs 2 PbX 4 -MoSe 2 heterostructures is beneficial for improving the photoelectric performance of two-dimensional perovskite devices. Lastly, we found that the Cs 2 PbI 4 -WSe 2 heterostructure has the largest PCE (18%) among Cs 2 PbX 4 -MSe 2 heterostructures. The Cs 2 PbCl 4 -MoSe 2 heterostructure exhibits great potential application in photodetector devices and the Cs 2 PbI 4 -WSe 2 heterostructure has great potential application in solar cells.