Effect of defects on the electronic structure of a PbI2/MoS2 van der Waals heterostructure: A first-principles study

PbI2/MoS2, as a typical van der Waals (vdW) heterostructure, has attracted intensive attention owing to its remarkable electronic and optoelectronic properties. In this work, the effect of defects on the electronic structures of a PbI2/MoS2 heterointerface has been systematically investigated. The manner in which the defects modulate the band structure of PbI2/MoS2, including the band gap, band edge, band alignment, and defect energy-level density within the band gap is discussed herein. It is shown that sulfur defects tune the band gaps, iodine defects shift the positions of the band edge and Fermi level, and lead defects realize the conversions between the straddling-gap band alignment and valence-band-aligned gap, thus enhancing the light-absorption ability of the material.