The tunable electronic band structure of a AlP3/Cs3Bi2I6Cl3 van der Waals heterostructure induced by an electric field: a first-principles study†

Constructing van der Waals heterostructures (vdWHs) has emerged as an attractive strategy to combine and enhance the optoelectronic properties of stacked materials. Herein, by means of first-principles calculations, we investigate the geometric and electronic structures of the AlP₃/Cs₃Bi₂I₆Cl₃ vdWH as well as its tunable band structure via an external electric field. The AlP₃/Cs₃Bi₂I₆Cl₃ vdWH is structurally and thermodynamically stable due to the low binding energy and the small energy fluctuation at room temperature. Our band structure calculations demonstrate that the AlP₃/Cs₃Bi₂I₆Cl₃ vdWH possesses an indirect bandgap and a type-I band alignment with the band edges both dominated by an AlP₃ layer. Notably, the band alignment of heterostructures can be flexibly tuned between type-I and type-II by employing an external electric field. Besides, an indirect-to-direct bandgap transition can be observed by increasing the intensity of negative electric field. These results reveal the potential of the AlP₃/Cs₃Bi₂I₆Cl₃ vdWH as a novel candidate material for the experimental designs of multi-functional devices.