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.