Electronic structure of 2D quaternary materials and of their van der Waals heterostructures

The properties of the two dimensional quaternary compounds AgScP2Se6, AgBiP2Se6, CuBiP2Se6, and CuInP2S6 and the corresponding van der Waals heterostructures are studied using density functional theory. These compounds are dynamically stable, their electronic bandgaps range from 2.13 to 2.68 eV, and the positions of their band edges are suitable for their use for water splitting. Among the different heterostructures made from these monolayers, it is demonstrated that AgBiP2Se6/AgScP2Se6 and AgBiP2Se6/CuBiP2Se6 are type II heterostructures, which allow an efficient electron–hole separation. Then, we studied the electronic properties of the graphene/quaternary-2D-compound heterostructures: a shift of the graphene Dirac-point above the Fermi level is observed, which corresponds to a p-type heterostructure. Overall, this family of materials appears to be very promising for optical and electronic applications.