Electronic and optical properties of bilayer SnS with different stacking orders: A first principles study

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Two-dimensional materials with tunable optical and electronic properties offer many interesting opportunities for optoelectronic devices and solar cells. Here, we report different stacking orders as an effective approach to tune the electronic and optical properties of SnS bilayers. Using the first principles density functional theory, the bandgap of the SnS bilayers is demonstrated to vary from 1.20 to 1.36 eV due to different stacking orders, wherein the AB-stacked SnS bilayer has a direct bandgap, different from AA- and AC-stacked ones. Furthermore, these SnS bilayer structures exhibit a strong light absorption over a wide range (∼1 to 6 eV), showing genuine potential for optoelectronic applications. When a MoS2 monolayer is combined with a p-type AB-stacked SnS bilayer, or a WS2 monolayer plus any of the above three stacking structures, the trilayer structures can be effective solar cell materials with a type-II heterojunction alignment.