Visualization of dynamic polaronic strain fields in hybrid lead halide perovskites
Visualization of dynamic polaronic strain fields in hybrid lead halide perovskites
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DOI：
10.1038/s41563-020-00865-5
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发表时间：
2021-01-04
期刊：
影响因子：
41.2
通讯作者：
Lindenberg, Aaron M.
中科院分区：
文献类型：
--
作者：
Guzelturk, Burak;Winkler, Thomas;Lindenberg, Aaron M.
涉及动态纳米级扭曲的激发定位是光催化(1)、量子材料(2)和分子光电子学(3)的一个核心方面。这种扭曲的实验表征需要对点缺陷类局部结构重排形成的实时敏感技术。在这里，我们通过飞秒分辨率漫射x射线散射测量，可视化了卤化铅钙钛矿原型成员(4)的激发诱导应变场。这使得动量分辨声子光谱的局部扭曲结构，并揭示了与光激发钙钛矿中极化子的形成和弛豫相关的径向扩展的纳米级应变场。获得了这种极化畸变的大小和形状的定量估计，为这些材料中发生的动态结构畸变提供了直接的见解（5-9）。光泵浦-探针反射光谱证实了这些结果，并显示了这些大的极化扭曲如何瞬时地改变载流子的有效质量，从而提供了混合钙钛矿光电功能基础上的耦合结构和电子动力学的统一图像。飞秒分辨率的漫射x射线散射显示了卤化物钙钛矿中极化畸变的形成和弛豫。这些结构变化也被量化，并与载流子有效质量的瞬态变化相关联。
Excitation localization involving dynamic nanoscale distortions is a central aspect of photocatalysis(1), quantum materials(2) and molecular optoelectronics(3). Experimental characterization of such distortions requires techniques sensitive to the formation of point-defect-like local structural rearrangements in real time. Here, we visualize excitation-induced strain fields in a prototypical member of the lead halide perovskites(4) via femtosecond resolution diffuse X-ray scattering measurements. This enables momentum-resolved phonon spectroscopy of the locally distorted structure and reveals radially expanding nanometre-scale strain fields associated with the formation and relaxation of polarons in photoexcited perovskites. Quantitative estimates of the magnitude and shape of this polaronic distortion are obtained, providing direct insights into the dynamic structural distortions that occur in these materials(5-9). Optical pump-probe reflection spectroscopy corroborates these results and shows how these large polaronic distortions transiently modify the carrier effective mass, providing a unified picture of the coupled structural and electronic dynamics that underlie the optoelectronic functionality of the hybrid perovskites.Diffuse X-ray scattering with femtosecond resolution shows the formation and relaxation of polaronic distortions in halide perovskites. These structural changes are also quantified and correlated to transient changes in carrier effective mass.