Symmetry-broken vertical TMDs/SnSe van der Waals heterojunctions for high-efficient photovoltaics

A promising technology to overcome the Shockley-Queisser limit of conventional photovoltaic cells is the bulk photovoltaic (PV) effect, which separates light-induced carriers generating a net shift current. This effect is also present in two-dimensional (2D) ferroelectric van der Waals (vdW) materials, such as SnSe, and can be improved by generating extra drift current via internal symmetry breaking. A strategy to break the symmetry is to interface SnSe with high-absorbent 2D materials with a different crystal structure, such as WSe2 or MoSe2, by vdW stacking. In this proposal, we aim to investigate, using nano-ARPES experiments, the band structure of two 2D vertical vdW heterojunctions (WSe2/SnSe and MoSe2/SnSe) to observe the effects of symmetry breaking on the valance band (VB) near the K and Gamma points, which can be capable to move the VB edge from K to Gamma point, and the hybridization of the spin-orbit splitting at the K point of the system.