A nickel(<scp>ii</scp>)-based one-dimensional organic–inorganic halide perovskite ferroelectric with the highest Curie temperature

Abstract

Organic-inorganic halide perovskites (OIHPs) are very eye-catching due to their chemical tunability and rich physical properties such as ferroelectricity, magnetism, photovoltaic properties and photoluminescence. However, no nickel-based OIHP ferroelectrics have been reported so far. Here, we designed an ABX₃ OIHP ferroelectric (3-pyrrolinium)NiCl₃, where the 3-pyrrolinium cations are located on the voids surrounded by one-dimensional chains composed of NiCl₆-face-sharing octahedra <i>via</i> hydrogen bonding interactions. Such a unique structure enables the (3-pyrrolinium)NiCl₃ with a high spontaneous polarization (<i>P</i> _s) of 5.8 μC cm^-2 and a high Curie temperature (<i>T</i> _c) of 428 K, realizing dramatic enhancement of 112 and 52 K compared to its isostructural (3-pyrrolinium)MCl₃ (M = Cd, Mn). To our knowledge, remarkably, (3-pyrrolinium)NiCl₃ should be the first case of nickel(ii)-based OIHP ferroelectric to date, and its <i>T</i> _c of 428 K (35 K above that of BaTiO₃) is the highest among all reported one-dimensional OIHP ferroelectrics. This work offers a new structural building block for enriching the family of OIHP structures and will inspire the further exploration of new nickel(ii)-based OIHP ferroelectrics.