A Three-Dimensional Lead Halide Perovskite-Related Ferroelectric

Abstract

Three-dimensional (3D) organic-inorganic lead halides represented by [CH₃NH₃]PbI₃ perovskite have attracted great interest for their diverse functional properties and promising optoelectronic applications. However, 3D lead halides are still very rare and their ferroelectricity remains controversial. Here, we report an unprecedented 3D lead halide perovskite-related ferroelectric [2-trimethylammonioethylammonium]Pb₂Cl₆ ([TMAEA]Pb₂Cl₆), which contains a 3D lead chloride framework of corner- and edge-sharing PbCl₆ octahedral, with the [TMAEA]⁺ cations occupying the voids of the framework. [TMAEA]Pb₂Cl₆ shows a ferroelectric-to-paraelectric phase transition with the Curie temperature as high as 412 K, a typical ferroelectric hysteresis loop at 293 K with a spontaneous polarization of 1 μC/cm², and a clear ferroelectric domain switching. To the best of our knowledge, [TMAEA]Pb₂Cl₆ is the first 3D lead halide showing such an excellent ferroelectricity. Additionally, it also exhibits a semiconducting property with a direct band gap of 3.43 eV. This finding enriches the family of 3D hybrid lead halides and inspires the exploration of 3D lead halide ferroelectrics.