中国科学院福建物质结构研究所罗军华团队通过笼式局限乙胺转子获得高Tc层状金属卤化物铁电材料。该项研究成果于2020年10月22日在线发表在《德国应用化学》杂志上。

据研究人员介绍，二维（2D）有机无机杂交钙钛矿（OIHP）铁电材料由于出色的半导体和铁电特性的结合，在光电学领域引起了广泛的关注。居里温度（Tc）是铁电材料的关键参数。然而，缺乏对二维OIHP铁电体Tc改变的研究阻碍了它们的进一步发展。

通过结合乙胺（EA）作为笼式局限转子，研究人员获得了两个二维OIHP铁电材料，分别为(IBA) 2 (EA)Pb 2 Br 7 ( 2L ; IBA=isob utylammonium)和 (IBA) 2 (EA) 2 Pb 3 Br 10 ( 3L )。有趣的是，Tc已成功地从326 K（2L）调整到370 K（3L），并且层厚度增加。结构和计算分析表明，Tc的提高是由于笼式局限EA转子触发的更高相变能垒以及层厚度增加。

这项工作表明，EA是合理设计高Tc 2D OIHP铁电体的有效“笼式局限转子”。根据“笼式局限转子”策略，可能会有更多具有良好性能的2D OIHP铁电材料出现。

附：英文原文

Title: Acquiring High‐Tc Layered Metal Halide Ferroelectrics via Cage‐Confined Ethylamine Rotators

Author: Yu Peng, Jie Bie, Xitao Liu, Lina Li, Shuang Chen, Wei Fa, Sasa Wang, Zhihua Sun, Junhua Luo

Issue&Volume:

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. 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 =  isob  utylammonium), 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 increased layer‐thickness. Structural and computational analyses suggest that  the improvement of  T  c  is due to the higher phase transition energy barrier triggered by cage‐confined EAs 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. In light of “cage‐confined rotator” strategy, one can expect more 2D OIHP ferroelectrics with promising performance.

DOI: 10.1002/anie.202011270

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202011270