Giant Photogalvanic effect in Janus monolayer In2SSe

Abstract

Linear and circular photogalvanic effects (PGEs) in Janus monolayer In2SSe are investigated by non-equilibrium Green’s function technique and combined density functional theory. Janus monolayer In2SSe is a two-dimensional material having Cs symmetry with a reflective surface normal to the orientations of armchair and zigzag., In both the zigzag and armchair directions, linear and circular photogalvanic effects are induced by this symmetry. Our numerical results show that different from monolayer black phosphorus and antimonene, Janus monolayer In2SSe can generate a large photocurrent when the bandgap energy is surpassed by photon energy in the absence of external bias voltage. The photocurrent changes in perfect cosine form with the polarization angle, which can be attributed to the second-order response of polarized light electric field. There is obvious anisotropy in the zigzag and armchair directions. Under the condition of zero bias voltage, the photocurrent in the armchair direction is more robust, which is 15 times higher than that in the zigzag. All the results indicate that Janus monolayer In2SSe is a more suitable alternate material for solar cells in the range of visible light.