Molecular Design Principles for Ferroelectrics: Ferroelectrochemistry

Ferro­electric materials have a variety of technological applications, as transducers, capacitors, sensors, etc. Great interest in molecular ferro­electrics has emerged because of their structural flexibility, tunability, and homochirality. However, the discoveries of molecular ferro­electrics are not abundant. The lack of chemical design is the main challenge in realizing new molecular ferro­electrics. Consequently, chemical design approaches, including the ideas of introducing quasi-spherical theory, homochirality, and H/F substitution, have been developed recently. Through these advanced methodologies, a wide range of ferro­electrics were successfully synthesized, changing the blind search into a targeted chemical design. In this Perspective, we aim to provide insight into the fundamental chemistry and physics of molecular ferro­electrics and propose the concept of “ferro­electro­chemistry”, concerned with the targeted design and performance optimization of molecular ferro­electrics from the chemical point of view. We start with the basic theories used in the modification of chemical structures for new molecular ferro­electrics, such as the quasi-spherical theory. After that, we focus on the fundamentals of homochirality from the perspective of chemistry and advantages of introducing a homochiral molecule within the scope of ferro­electrics. Further, we explore another design strategy, H/F substitution, as an analogue of the H/D isotope effect. The introduction of a F atom usually does not change the polar point group but may induce a minor structural disruption that enhances physical properties such as Curie temperature and spontaneous polarization. We hope our comprehensive studies on the targeted design and performance optimization strategies for molecular ferro­electrics may build up and enrich the content of ferro­electro­chemistry.