Renewing Halogen Substitution Strategy for the Rational Design of High‐Curie Temperature Metal‐Free Molecular Antiferroelectrics
Wenjing Li, Yu Ma, Xinxin Hu, Haojie Xu, Yi Liu, Shiguo Han, Qingshun Fan, Changhao Gao, Zhihua Sun, Junhua Luo
Abstract
Abstract Metal‐free molecular antiferroelectric (AFE) holds a promise for energy storage on account of its unique physical attributes. However, it is challenging to explore high‐curie temperature ( T c ) molecular AFEs, due to the lack of design strategies regarding the rise of phase transition energy barriers. By renewing the halogen substitution strategy, we have obtained a series of high‐ T c molecular AFEs of the halogen‐substituted phenethylammonium bromides ( x ‐PEAB, x =H/F/Cl/Br), resembling the binary stator‐rotator system. Strikingly, the p ‐site halogen substitution of PEA + cationic rotators raises their phase transition energy barrier and greatly enhances T c up to ~473 K for Br‐PEAB, on par with the record‐high T c values for molecular AFEs. As a typical case, the member 4‐fluorophenethylammonium bromide (F‐PEAB) shows notable AFE properties, including high T c (~374 K) and large electric polarization (~3.2 μC/cm 2 ). Further, F‐PEAB also exhibits a high energy storage efficiency ( η ) of 83.6 % even around T c , catching up with other AFE oxides. This renewing halogen substitution strategy in the molecular AFE system provides an effective way to design high‐ T c AFEs for energy storage devices.