Multi-functional application potential of Ruddlesden-Popper perovskite-based heterostructure PtSe2/Cs2PbI4 with tunable electronic properties.

Heterogeneous stacking based on two-dimensional Ruddlesden-Popper perovskite is a desired strategy for the reasonable combination of stability and efficiency. Constructing heterostructures with tunable optoelectronic properties further provide opportunities to design multi-functional devices. Herein, we present a first-principle research to investigate the geometric and electronic structures of Ruddlesden-Popper perovskite heterostructure PtSe2/Cs2PbI4 and its tunable electronic properties induced by thickness modulation and external strains. The results indicate that the heterostructure based on Cs2PbI4 monolayer and PtSe2 monolayer has a type-II band alignment, which is suitable for the photovoltaic applications. With the layer number of PtSe2 in heterostructure increases from monolayer to bilayer, the band alignment of PtSe2/Cs2PbI4 heterostructure can switch from type-II to type-I, which is beneficial for the luminescence device applications. However, when the thickness of PtSe2 in heterostructure further increases to trilayer, the heterostructure exhibits metallic characteristic with a p-type Schottky barrier. In addition, we find the strain engineering is an effective knob in tuning the electronic properties of PtSe2/Cs2PbI4 heterostructures with different thickness. These findings reveal the potential of PtSe2/Cs2PbI4 heterostructure as a tunable hybrid material with substantial prospect in multi-functional applications.