南昌大学汤渊源团队报道了一种具有介电开关和宽带近红外光致发光的层状二维钙钛矿（BIM）₂GeI₄。相关研究成果发表在2024年3月18日出版的《结构化学》。

二维卤化铅钙钛矿由于其优异的物理性能而引起了人们的极大关注。然而，有毒铅的存在是大规模应用的一个主要问题。

该文中，研究人员报道了无铅二维锗基钙钛矿（BIM）₂GeI₄（BIM=苯并咪唑）的合成、相变、介电和光致发光（PL）特性。相变单晶X射线衍射实验和差示扫描量热计测量表明，（BIM）₂GeI₄在405K下发生相变，并伴随着有机间隔物的有序无序变化。

此外，在相变附近的阶梯状介电转变使其适合于介电开关。同时，（BIM）₂GeI₄具有2.23eV的直接带隙和550nm至1000nm的宽带发射，这意味着它们对于潜在的近红外照明和显示具有独特的光学特性。

该项工作为开发无铅2D Ge基钙钛矿提供了一个新的例子，在光电子和高温介质开关领域具有潜在的应用前景。

附：英文原文

Title: (Benzimidazolium)2GeI4: A layered two-dimensional perovskite with dielectric switching and broadband near-infrared photoluminescence

Author: Xuan Zhu, Lin Zhou, Xiao-Yun Huang, Yan-Ling Luo, Xin Deng, Xin Yan, Yan-Juan Wang, Yan Qin, Yuan-Yuan Tang

Issue&Volume: 2024-03-18

Abstract: Two-dimensional (2D) lead halide perovskites have attracted tremendous attention due to their outstanding physical properties. However, the presence of toxic lead is a major problem for large-scale applications. Here, we report the synthesis, phase transition, dielectric and photoluminescence (PL) properties of a lead-free two-dimensional Ge-based perovskite (BIM)2GeI4 (BIM = benzimidazolium). Variable temperature single crystal X-ray diffraction experiment and differential scanning calorimeter measurement reveal that (BIM)2GeI4 experiences a phase transition at 405 K, accompanying by the order-disorder change of organic spacer. Moreover, the step-like dielectric transition near phase transition makes it suitable for dielectric switching. Meanwhile, (BIM)2GeI4 has a direct bandgap of 2.23 eV and broadband emission from 550 nm to 1000 nm, implying their unique optical property for potential near-infrared lighting and displaying. This work provides a fresh example for the development of lead-free 2D Ge-based perovskite with potential application in the fields of optoelectronics and high temperature dielectric switching.

DOI: 10.1016/j.cjsc.2024.100272

Source: http://cjsc.ac.cn/cms/issues/583