Emerging piezochromism in lead free alkaline earth chalcogenide perovskite AZrS3 (A = Mg, Ca, Sr and Ba) under pressure

Hydrostatic pressure is an effective tool that can give rise to novel crystal structures and physical properties. It has proven to be an alternative to chemical pressure. Therefore new functional materials with intriguing properties can be designed by exerting external pressure. Metal chalcogenide perovskites are a class of perovskites that have several advantages, namely high stability against moisture and light induced degradation along with nontoxic elemental composition. In this letter, we have used first principles methods to study the structural, electronic and optical properties of AZrS(3) where A = Mg, Ca, Sr and Ba upon compression. Upon being compressed, the direct band gaps decrease to desired values which can enable this class of zirconium based chalcogenide perovskites to be used in tandem solar cells. The mobility of the charge carriers increases with pressure as the effective masses decrease. Piezochromism is seen to exist upon compression which can be verified from the modifications in the optical absorption spectra. This work elucidates the effects of pressure on the sensitive tuning of properties of zirconium based chalcogenide perovskites, which can have significant photovoltaic applications.