High-Tc Fe-based ferroelectric compound with large spontaneous polarization and narrow bandgap

Abstract

Organic–inorganic hybrid perovskite halide ferroelectric semiconductor materials have received great attention due to their various properties and wide applications. However, currently, most of the reported ferroelectric semiconductor materials are lead-based, while there are a few reports on iron-based organic–inorganic hybrid semiconductor materials. In this study, we have successfully designed and synthesized a novel zero-dimensional organic–inorganic hybrid metal halide semiconductor ferroelectric material: [(CH₃)₃NCH₂CH₂CH₃] FeBr₄ (1), with a high-temperature phase transition point of 390 K and spontaneous polarization (P_s = 7.5 μC cm⁻²). The typical hysteresis loop and clear ferroelectric domain of compound 1 were obtained, which revealed the ferroelectricity of compound 1. It is worth mentioning that compound 1 showed a rare ferroelectric–ferroelectric phase transition. In addition, compound 1 has an optical bandgap of 1.88 eV and a theoretical bandgap of 1.71 eV, indicating that compound 1 is a high-quality semiconductor material. This work provides some inspiration for the research on lead-free organic–inorganic hybrid metal halide semiconductor ferroelectric materials.