Non-linear optical-dielectric duple switch and narrow band gap in a one-dimensional hybrid compound: [(CH3)2S(CH2)3NH3][SbBr5]

Abstract

Organic–inorganic hybrid structural phase transition compounds for multifunctional switchable applications have attracted significant attention in recent years due to their excellent optoelectronic properties. Seeking such materials and studying the relationship between the changeable physical properties and crystal structures are of great importance for promoting their applications. Herein, we report a new one-dimensional lead-free organic–inorganic hybrid compound, [(CH₃)₂S(CH₂)₃NH₃][SbBr₅] [(CH₃)₂S⁺(CH₂)₃NH₃⁺ = dimethyl(3-propylammonium)sulfonium dications], which undergoes a structural phase transition from a centrosymmetric space group of Pcnm (high temperature) to a polar orthorhombic space group of Pca2₁ (low temperature, and exhibit a large second harmonic generation intensity of 2.32 times of KH₂PO₄), accompany by switchable non-linear optical and dielectric properties. Structural analyses demonstrate that the structural phase transition was triggered by ordering of organic cations and distortions of inorganic octahedra. Moreover, the pyroelectric measurements indicate that the compound should be a potential ferroelectric, and UV-vis absorption and density functional theory calculation reveal a narrow band gap of 2.29 eV (calculated 2.06 eV). This work may offer an approach for design advanced multifunctional properties based on organic–inorganic hybrid compounds.