Biferroelectricity of a homochiral organic molecule in both solid crystal and liquid crystal phases

Abstract

Ferroelectricity, existing in either solid crystals or liquid crystals, gained widespread attention from science and industry for over a century. However, ferroelectricity has never been observed in both solid and liquid crystal phases of a material simultaneously. Inorganic ferroelectrics that dominate the market do not have liquid crystal phases because of their completely rigid structure caused by intrinsic chemical bonds. We report a ferroelectric homochiral cholesterol derivative, β-sitosteryl 4-iodocinnamate, where both solid and liquid crystal phases can exhibit the behavior of polarization switching as determined by polarization–voltage hysteresis loops and piezoresponse force microscopy measurements. The unique long molecular chain, sterol structure, and homochirality of β-sitosteryl 4-iodocinnamate molecules enable the formation of polar crystal structures with point group 2 in solid crystal phases, and promote the layered and helical structure in the liquid crystal phase with vertical polarization. Our findings demonstrate a compound that can show the biferroelectricity in both solid and liquid crystal phases, which would inspire further exploration of the interplay between solid and liquid crystal ferroelectric phases.

High-Temperature Phase Transition with Switchable Dielectric Behavior and Significant Photoluminescence Changes in a Zero-Dimensional Hybrid SbBr6 Perovskite

“…Subsequently, when the temperature dropped again to 340 K, the position of the diffraction peak returned to its preceding state, implying that compound 1 underwent a reversible phase transition, and the phase transition temperature was consistent with the DSC test results. 36,37 As is well-known, how to clarify the microstructure changes of this high-temperature phase transition without X-ray singlecrystal diffraction is indeed a new challenge. 38 We speculate that the high-temperature reversible phase transition may be caused by the ordered disorder of organic cation groups, which can also be reflected by their Raman bands.…”

Reversible phase transition and thermochromic response in hybrid copper-based perovskites

“…Thermal-stimulated phase transition materials can be used in various smart devices, including signal processors, switches, and memory devices. 13–19 It is interesting to note that the physical properties of switchable dielectric materials change significantly when external stimuli are applied, including electric fields, temperature, and light. 20–29 Furthermore, it has been shown that a scientifically designed and tuned organic cation enables the material to have multiple properties, including ferroelectricity, pyroelectricity and piezoelectricity.…”

Fluorination Enables Dual Ferroelectricity in Both Solid- and Liquid-Crystal Phases

“…Ferroelectric LCs have unique application advantages in display and optoelectronics due to their exceptionally fast electro-optical response and the special photoelectric effect. − For a long time, compared to other types of LC phases with D ∞h symmetry, the chiral smectic LC phase was thought to exhibit ferroelectricity because of the C 2 -symmetric polarization vector perpendicular to both the director and the molecular layer direction. − Subversively, in recent years, ferroelectricity has also been experimentally proved in the nematic LCs with C ∞v symmetry, breaking the conventional thinking of ferroelectric LCs and opening a new chapter in condensed matter science and related applications. − The broken head-to-tail symmetry of two permissible director orientations in such a nematic LC system enables the molecular dipoles to spontaneously orient to a preferred direction, generating macroscopic polarization. ,− Liquid crystals can be generated by heating some organic solid crystals . However, although the respective development of ferroelectric SCs and LCs has made great strides, and most recently a molecular ferroelectric with ferroelectricity in the SC and typical chiral smectic LC phases has been reported, it still remains a great challenge to design a single material with ferroelectricity in both its SC and LC phases. The dual ferroelectricity in one material is fascinating and provides a platform for in-depth studying and understanding of the underlying correlation of the symmetry and polarity between sequential SC and LC phases.…”

“… 34 , 40 − 42 Liquid crystals can be generated by heating some organic solid crystals. 43 However, although the respective development of ferroelectric SCs and LCs has made great strides, and most recently a molecular ferroelectric with ferroelectricity in the SC and typical chiral smectic LC phases has been reported, 44 it still remains a great challenge to design a single material with ferroelectricity in both its SC and LC phases. The dual ferroelectricity in one material is fascinating and provides a platform for in-depth studying and understanding of the underlying correlation of the symmetry and polarity between sequential SC and LC phases.…”