Ferroelectricity in perovskites realized by a switchable skewed conformation

Abstract

Ferroelectric materials have broad application prospects in photovoltaics, energy storage, information storage and other fields; however, obtaining ferroelectric materials through rational molecular design remains a challenge. Noncentrosymmetric crystallization, directional arrangement of dipoles and an appropriate flipping barrier are all key difficulties in constructing ideal ferroelectric materials. In this article, a novel hybrid material, TDMHACdCl₃ (1, where TDMHA⁺ is N-(tert-butyl)-N,N-dimethylhydroxylammonium), exhibiting ferroelectric properties was successfully synthesized and characterized. A CH₃/OH substitution strategy was employed to form a hydrogen bond between the organic cation and the inorganic framework, deflecting the dipole moment direction of the cation. To minimize the energy of the crystal lattice, hydrogen bonds compete with the cation conformation, causing the cations to deviate from the optimal conformation and allowing the dipoles to be oriented in one direction. The crystal structure and quantum chemical calculations are thoroughly discussed to reveal the origin of the ferroelectric property in this work. We believe that our design strategy will contribute to the discovery of more ferroelectric materials.