Organic Enantiomeric Ferroelectrics with High Piezoelectric Performance: Imidazolium l- and d-Camphorsulfonate

Ferroelectric materials have been widely used in daily life and industrial production, as memories, transducers, capacitors, sensors, and so forth. Recently, great interest in molecular ferroelectrics has emerged because of their structural flexibility, tunability, and homochirality. Chemical design has opened up a new era for molecular ferroelectrics, where we can realize the targeted design and performance optimization of molecular ferroelectrics upon several well-developed phenomenological theories. Herein, through the chemical design strategies of lowering the molecular symmetry and introducing homochirality upon the nonferroelectric imidazolium methanesulfonate (ImMS), we designed a pair of high-temperature organic enantiomeric ferroelectrics, imidazolium l-camphorsulfonate (l-ImCS) and imidazolium d-camphorsulfonate (d-ImCS). The enantiomers undergo a 222F2-type ferroelectric phase transition at 367 K (Tc(l)) and 370 K (Tc(d)), respectively. It should be highlighted that l- and d-ImCS show a relatively high piezoelectric response of 19 and 20 pC N–1, reaching the level of triglycine sulfate. To our knowledge, this is the first time that homochiral small-molecule ferroelectrics possess such a large piezoelectric response as well as good biocompatibility. This finding provides a new and feasible strategy for precisely designing high-performance homochiral molecular ferroelectrics.