Electronic and optical properties of CrI₃/Nb₃Cl₈heterojunction: a first principles investigation

Constructing heterostructures has been used as an effective way to circumvent the shortcomings of composite layers since the interactions and charge transfer between individual layers can thus change the properties in forming heterostructure. In this work, the stability and physical properties of two-dimensional van der Waals CrI₃/Nb₃Cl₈heterojunction in different stacking modes have been investigated using the first principles calculations based on density functional theory. The results demonstrate that the most stable CrI₃/Nb₃Cl₈heterojunction possesses a typical type-II band alignment with a 0.753 eV indirect band gap. The electrons moves from the Nb₃Cl₈layer to the CrI₃layer due to the former one has a higher energy level for valence band maximum, resulting in a built-in electric field. Comparing to CrI₃and Nb₃Cl₈monolayers, the light absorption is enhanced in the infrared, visible and ultraviolet regions, and may hence improve the efficiency in energy conversion or optoelectronics. The rather narrow band gap hinders its application in water splitting, but may have potential applications related with infrared lights. Thus, the investigation provides theoretical insights for CrI₃/Nb₃Cl₈heterojunction and may promote its applications.