Giant Bulk Electrophotovoltaic Effect in Heteronodal-Line Systems

The realization of a giant and continuously tunable second-order photocurrent is desired for many nonlinear optical (NLO) and optoelectronic applications, which remains a great challenge. Here, based on a two-band model, we propose a concept of the bulk electrophotovoltaic effect, that is, an out-of-plane external electric field (Eext) that can continuously tune in-plane shift current along with its sign flip in a heteronodal-line (HNL) system. While strong linear optical transition around the nodal loop may potentially generate giant shift current, an Eext can effectively control the radius of the nodal loop, which can continuously modulate the shift-vector components inside and outside the nodal loop holding opposite signs. This concept has been demonstrated in the HNL HSnN=MoS2 system using first-principles calculations. The HSnN=MoS2 heterobilayer can not only produce a shift-current conductivity with magnitude that is one to two orders larger than other reported systems, but it can also realize a giant bulk electrophotovoltaic effect. Our finding opens new routes to create and manipulate NLO responses in 2D materials.

Automated summary

Based on a two-band model, we propose a concept of the bulk electrophotovoltaic effect, which can continuously tune the in-plane shift current in a heteronodal-line system. By effectively controlling the radius of the nodal loop, the shift-vector components inside and outside the nodal loop can be continuously modulated, resulting in a giant bulk electrophotovoltaic effect.