A Hybrid Antiperovskite with Strong Linear and Second‐Order Nonlinear Optical Responses

Abstract

Antiperovskites have been studied since the 1980s because of their rich physical and chemical properties, but their linear and second-order nonlinear optical responses remain largely unknown. Here we report a new polar crystal, Cs₃ Cl(HC₃ N₃ S₃ ) (I), which features a quasi-one-dimensional antiperovskite structure composed of ClCs₆ polyhedra and A-site [HC₃ N₃ S₃ ]^2- rings. To our best knowledge, this kind of antiperovskite structure is reported for the first time. Remarkably, I exhibits a very strong nonlinear optical response up to 11.4 times that of the benchmark KH₂ PO₄ and exceptionally large birefringence of 0.52. The first-principles calculations and structural analyses reveal that [HC₃ N₃ S₃ ]^2- is the "material gene" while the antiperovskite structural feature making it in a favorable arrangement. This work provides a new structural platform for the rational design of integrated optoelectronic materials with linear and second-order nonlinear optical responses.