Tunable Electronic Structure of Two-Dimensional MoX2 (X = S, Se)/SnS2 van der Waals Heterostructures

Two-dimensional (2D) van der Waals heterostructures formed by stacking two different 2D materials have gained immense attention as they have the potential to show interesting properties. Herein, we report the detailed electronic structure of recently synthesized MoS2/SnS2 and MoSe2/SnS2 heterostructures obtained through density functional calculations. Our study shows that the MoS2/SnS2 heterostructure has a type-I band alignment with an indirect band gap, while MoSe2/SnS2 exhibits a type-II band alignment with a direct band gap. In type-II MoSe2/SnS2 heterobilayers, the hole and electron charge carriers are localized on two different 2D layers and thus show spatial charge separation, which lowers electron-hole recombination and prolongs carrier lifetime; thus, they are useful candidates for solar cell applications. Both the heterostructures MoS2/SnS2 and MoSe2/SnS2 retain their type-I and type-II band alignments, respectively, under applied uniaxial strain (both tensile and compressive). Moreover, both the heterostructures show excellent optical absorption (10(5) cm(-1)) in the entire UV-visible range. The robust type-I and type-II band alignments as well as strong optical absorption indicate that the two heterostructures studied may have good prospects in optoelectronic and photovoltaic applications.