Non-radiative energy transfer and selective charge transfer in a WS2/(PEA)2PbI4 heterostructure

Van der Waals heterostructures are currently the focus of intense investigation, this is essentially due to the unprecedented flexibility offered by the total relaxation of lattice matching requirements, and their new and exotic properties compared to the individual layers. Here, we investigate the hybrid transition metal dichalcogenide/2D perovskite heterostructure WS2 /(PEA)2 PbI4 . We present the first DFT calculations of a heterostructure ensemble, which reveal a novel band alignment, where direct electron transfer is blocked by the organic spacer of the 2D perovskite. In contrast, the valence band forms a cascade from WS2 through the PEA to the PbI4 layer allowing hole transfer. These predictions are supported by optical spectroscopy studies, which provide compelling evidence for both charge transfer, and non-radiative transfer of the excitation (energy transfer) between the layers. Our results show that TMD/2D perovskite heterostructures provide a flexible and convenient way to engineer the band alignment.