Band alignment engineering of a Ruddlesden–Popper perovskite-based heterostructure constructed using Cs2SnI2Cl2 and α-In2Se3: The effects of ferroelectric polarization switching and electric fields

Ferroelectricity is an important source of the fascinating optoelectronic properties of heterostructures. Interfaces formed between ferroelectrics and oxides or transition metal dichalcogenides have undergone rapid development. However, the integration of ferroelectrics and two-dimensional Ruddlesden–Popper (RP) perovskites has rarely been studied so far. Herein, we use first-principle calculations to investigate ferroelectric polarization and electric field control of band alignments within the RP perovskite-based heterostructure α-In2Se3/Cs2SnI2Cl2. Our calculations demonstrate that the band alignment of heterostructure can be changed from type-II to type-III by switching the ferroelectric polarization direction in the α-In2Se3 layer. Furthermore, application of an external electric field can modulate the band structure of the α-In2Se3/Cs2SnI2Cl2 heterostructure and induce the band alignment transition. These findings highlight the importance of ferroelectric polarization switching in band alignment engineering and suggest the possibility of electric field-tunable multi-band alignment in Ruddlesden–Popper perovskite-based heterostructures.