中国科学院福建物构所李丽娜团队报道了用于灵敏自供电X射线探测的无铅手性极性钙钛矿结构设计。相关研究成果于2024年2月29日发表于国际顶尖学术期刊《结构化学》。

金属卤化物钙钛矿由于其优异的光电性能，在X射线检测方面取得了重大进展。然而，这些材料中的大多数都存在有毒元素铅和对高工作电压的要求。因此，探索无外部偏压的环境友好型钙钛矿用于X射线检测势在必行。

该文中，研究人员战略性地引入手性阳离子来合成一对无铅手性极性杂化钙钛矿（S-MPz）₆Bi₃I₂₁6H₂O和（R-MPz）₆Bi₂₁6H₂O（1S和1R，S/R-MPz=S/R-2-甲基哌嗪）。它们表现出强的圆二色性信号，各向异性g因子达到约0.017。

值得注意的是，手性极性特征产生了独特的自发极化，在X射线照射下产生了1.1V的光电压，赋予了X射线的自供电检测能力。对基于1R单晶的X射线器件的进一步探索表明，在零偏压下具有5.2μC Gyair^-1cm^-2的高灵敏度。

该项研究依靠手性极性钙钛矿的固有自发极化诱导的内置电场实现了被动X射线检测，为高性能“绿色”自供电辐射检测所需材料的化学设计提供了一种有效的方法。

附：英文原文

Title: Structure design of lead-free chiral-polar perovskites for sensitive self-powered X-ray detection

Author: Xin Dong, Tianqi Chen, Jing Liang, Lei Wang, Huajie Wu, Zhijin Xu, Junhua Luo, Li-Na Li

Issue&Volume: 2024-02-29

Abstract: Metal halide perovskites have made significant progress in X-ray detection owing to their exceptional optoelectronic properties. However, most of these materials suffer from the toxic element lead and the requirement for high operating voltages. Hence, the exploration of environmentally friendly perovskites for X-ray detection without external bias is imperative. Herein, we strategically introduced chiral cations to synthesize a pair of lead-free chiral-polar hybrid perovskites (S-MPz)6Bi3I216H2O and (R-MPz)6Bi3I216H2O (1S and 1R, S/R-MPz = S/R-2-methylpiperazinium). They exhibited strong circular dichroism signals with an anisotropic g-factor reaching approximately 0.017. Significantly, the chiral-polar feature gave rise to distinctive spontaneous polarization, which led to a photovoltage of 1.1 V under X-ray illumination, endowing self-powered detection capabilities for X-ray. Further exploration of X-ray devices based on 1R single crystal demonstrated a high sensitivity of 5.2 μC Gyair1 cm2 at zero bias. This study realizes passive X-ray detection depending on the intrinsic spontaneous polarization induced built-in electric field of chiral-polar perovskite, providing an effective approach to the chemical design of desired materials for high-performance "green" self-powered radiation detection.

DOI: 10.1016/j.cjsc.2024.100256

Source: http://cjsc.ac.cn/cms/issues/576