Acquiring High‐<i>T</i><sub>C</sub> Layered Metal Halide Ferroelectrics via Cage‐Confined Ethylamine Rotators
Yu Peng, Jie Bie, Xitao Liu, Lina Li, Shuang Chen, Wei Fa, Sasa Wang, Zhihua Sun, Junhua Luo
Abstract
Abstract Two‐dimensional (2D) organic–inorganic hybrid perovskite (OIHP) ferroelectrics have attracted widespread interest in the field of optoelectronics due to the combination of excellent semiconducting and ferroelectric properties. The Curie temperature ( T C ), below which ferroelectricity exists, is a crucial parameter for ferroelectrics. However, the lack of research on T C tuning of 2D OIHP ferroelectrics hinders their further progress. Here, through incorporating ethylammonium (EA) as cage‐confined rotators, we obtained two 2D OIHP ferroelectrics, (IBA) 2 (EA)Pb 2 Br 7 ( 2L ; IBA=isobutylammonium), and (IBA) 2 (EA) 2 Pb 3 Br 10 ( 3L ). Intriguingly, T C is successfully tuned from 326 K ( 2L ) to 370 K ( 3L ) with increasing layer thickness. Structural and computational analyses suggest that the improvement of T C is due to the higher phase‐transition energy barrier triggered by the cage‐confined EA rotators with increased layer thickness. This work suggests that EA is an effective “cage‐confined rotator” to rationally design high‐ T C 2D OIHP ferroelectrics.