Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA.
Department of Materials Science and Engineering, Northwestern University, 2170 Campus Drive, Evanston, Illinois 60208-3113, USA.
Nat Commun. 2016 Oct 13;7:13108. doi: 10.1038/ncomms13108.
Flexible organic materials possessing useful electrical properties, such as ferroelectricity, are of crucial importance in the engineering of electronic devices. Up until now, however, only ferroelectric polymers have intrinsically met this flexibility requirement, leaving small-molecule organic ferroelectrics with room for improvement. Since both flexibility and ferroelectricity are rare properties on their own, combining them in one crystalline organic material is challenging. Herein, we report that trisubstituted haloimidazoles not only display ferroelectricity and piezoelectricity-the properties that originate from their non-centrosymmetric crystal lattice-but also lend their crystalline mechanical properties to fine-tuning in a controllable manner by disrupting the weak halogen bonds between the molecules. This element of control makes it possible to deliver another unique and highly desirable property, namely crystal flexibility. Moreover, the electrical properties are maintained in the flexible crystals.
具有有用电性能的柔性有机材料，如铁电性，在电子设备的工程中至关重要。然而，到目前为止，只有铁电聚合物从本质上满足了这种灵活性要求，而小分子有机铁电体还有改进的空间。由于柔韧性和铁电性本身都是罕见的特性，因此将它们结合在一个晶体有机材料中是具有挑战性的。在此，我们报告三取代卤代咪唑不仅表现出铁电性和压电性——这些特性源于其非中心对称的晶格——而且通过破坏分子之间的弱卤键以可控的方式赋予其晶体机械性能以精细调整。这种控制元素使得提供另一种独特且非常理想的特性成为可能，即晶体柔韧性。此外，在柔性晶体中保持了电性能。
