A Poling-Free Supramolecular Crown Ether Compound with Large Piezoelectricity
Hui‐Peng Lv, Yirong Li, Xian‐Jiang Song, Nan Zhang, Ren‐Gen Xiong, Han‐Yue Zhang
Abstract
Supramolecular host–guest ferroelectrics based on solution processing are highly desirable because they are generally created with intrinsic piezoelectricity/ferroelectricity and do not need further poling. Poly(vinylidene fluoride) (PVDF) in the electric-active beta phase after stretching/annealing still shows no piezoelectric response unless poled. Although many supramolecular host–guest ferroelectrics have been discovered, their piezoelectricity is relatively small. Based on H/F substitution, we reported a supramolecular host–guest compound [(CF 3 –C 6 H 4 –NH 3 )(18-crown-6)][TFSA] (CF 3 –C 6 H 4 –NH 3 = 4-trifluoromethylanilinium, TFSA = bis(trifluoromethanesulfonyl)ammonium) with a remarkable piezoelectric response of 42 pC/N under no poling condition. The introduction of F atoms increases phase transition temperature, polar axes, second harmonic generation (SHG) intensity, and piezoelectric coefficient d 33 . To our knowledge, such a large piezoelectric performance of [(CF 3 –C 6 H 4 –NH 3 )(18-crown-6)][TFSA] makes its d 33, piezoelectric voltage coefficient g 33, and mechanical quality factor Q m the highest among the reported supramolecular host–guest ferroelectric compounds and even larger than the values of PVDF. This work provides inspiration for optimizing piezoelectricity on molecular materials.