Computational screening of MX (M = Ga, Ge, Sn, In; X = As, Se) van der Waals heterostructures as suitable candidates for solar cells

Abstract

Stacking different two-dimensional (2D) materials to form van der Waals (vdW) heterostructures has been considered as an effective strategy to realize new and exciting properties and innovative device applications in optoelectronics and electronics. In this work, we theoretically investigated the electronic properties of vdW heterostructures combined with different 2D MX materials (M = Ga, Ge, Sn, In; X = As, Se). Interestingly, SnAs/GaSe vdW heterostructure was screened from all the possible MX vdW heterostructures with the direct band gap (1.25 eV) within the visible light region, which perfectly falls into the optimum range for solar cells. Meanwhile, it was demonstrated that SnAs/GaSe vdW heterostructure has a typical type-II band alignment without strong interface hybridization, thus photogenerated electrons and holes could be effectively separated into opposite layers. In addition, the large band offset, small carrier effective mass, and high tunneling probability across the interface (16.24%) also guarantee its superiority in solar energy conversion. Our results suggest that SnAs/GaSe vdW heterostructure can be a new choice for low dimensional optoelectronic devices particularly for solar cells and pave the way for experimental verification in future.