Interesting dimensional transition through changing cations as the trigger in multinary thioarsenates displaying variable photocurrent response and optical anisotropy

Abstract

Due to the intriguing component variability and structure–property flexibility, lone-pair cation-based chalcogenides have garnered substantial interest in recent years. Herein, two new multinary thioarsenates, Cs₂ZnAs₄S₈ and [(NH₄)Cs]CdAs₄S₈, were successfully discovered via a surfactant–thermal reaction. Both of them possess identical stoichiometry 2–1–4–8, but they exhibit surprisingly different structural features. Cs₂ZnAs₄S₈ demonstrates a three-dimensional (3D) [ZnAs₄S₈]²⁻ framework made from the corner-sharing [ZnS₄] tetrahedra and one-dimensional (1D) [As₄S₈]⁴⁻ chains, whereas [(NH₄)Cs]CdAs₄S₈ exhibits a two-dimensional (2D) [CdAs₄S₈]²⁻ layer constructed from the corner-sharing [CdS₄] tetrahedra and tetranuclear [As₄S₈] clusters. Photoelectric measurements display that Cs₂ZnAs₄S₈ has higher photogenerated electron–hole pair separation efficiency than [(NH₄)Cs]CdAs₄S₈ under visible light irradiation. Moreover, both of them show large optical anisotropy (Δn > 0.17 at 1064 and 2050 nm), while the low dimensional structure is more conducive to enhancing the optical anisotropy based on the theoretical calculations. These findings will provide inspiration for the exploration of multifunctional chalcogenides.