Shift Current Photovoltaics based on A Noncentrosymmetric Phase in in-plane Ferroelectric SnS.

The shift current photovoltaics of group IV monochalcogenides have been predicted to be comparable to those of state-of-the-art Si-based solar cells. However, its exploration has been prevented from the centrosymmetric layer stacking in the thermodynamically stable bulk crystal. Herein, we stabilized the noncentrosymmetric layer stacking of tin sulfide (SnS) in the bottom regions of SnS crystals grown on a van der Waals substrate by physical vapor deposition and demonstrated the shift current of SnS by combining the polarization angle dependence and circular photogalvanic effect. Furthermore, 180° ferroelectric domains in SnS were verified through both piezoresponse force microscopy and shift current mapping techniques. Based on these results, an atomic model of the ferroelectric domain boundary was proposed. The direct observation of shift current and ferroelectric domains reported herein paves a new path for future studies on shift current photovoltaics. This article is protected by copyright. All rights reserved.