Photoluminescence Behaviors of 2D-Cs₃Bi₂I₉/2D-MoS₂ Vertical Heterostructures Prepared by the One-Step CVT Growth Method

Two-dimensional (2D) perovskites are emerging materials with large exciton binding energy, tunable bandgap, and layered properties. The weak van der Waals (vdW) coupling between the layers in 2D perovskites is easy to integrate with other layered materials, such as graphene and transition metal dichalcogenides, forming heterostructures (HS) to expand their functions. In order to obtain excellent HS materials, it is necessary to develop high-quality and low-cost, scalable preparation methods for 2D HS. Notably, chemical vapor transport (CVT) is a powerful method that may meet the above requirements. Herein, we first synthesized the HS of 2D-Cs3Bi2I9/2D-MoS2 using the one-step CVT method, then characterized its structure and properties, and further elucidated the underlying mechanism of photoluminescence behavior. It has been proven that this is a type II band alignment HS material combined with theoretical calculations. Then, we used a femtosecond pump measurement to study the photodynamic process of the HS and reveal the energy transfer and charge transfer in the HS, which also provides a foundation for future HS device fabrication.