Acquiring High-TC Layered Metal Halide Ferroelectrics via Cage-Confined Ethylamine Rotators

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)Pb2Br7 (2L; IBA=isobutylammonium), and (IBA)(2)(EA)(2)Pb3Br10 (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.

Automated summary

In this study, two-dimensional organic-inorganic hybrid perovskite ferroelectrics were successfully tuned by incorporating ethylammonium as cage-confined rotators, leading to an increase in Curie temperature with increasing layer thickness. This work provides new insights for the rational design of high-T-C 2D OIHP ferroelectrics.