Visualization and Studies of Ion-Diffusion Kinetics in Cesium Lead Bromide Perovskite Nanowires
Visualization and Studies of Ion-Diffusion Kinetics in Cesium Lead Bromide Perovskite Nanowires
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DOI：
10.1021/acs.nanolett.7b05023
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发表时间：
2018-03-01
期刊：
影响因子：
10.8
通讯作者：
Jin, Song
中科院分区：
文献类型：
--
作者：
Pan, Dongxu;Fu, Yongping;Jin, Song
金属卤化物钙钛矿经由离子交换的容易的化学转化归因于它们的“软”晶格，其能够实现快速离子迁移。动力学研究这些过程可以提供离子迁移动力学的机理见解。本文中，通过使用在外延衬底上的定向的铯铅溴化（CsPbBr 3）钙钛矿单晶纳米线作为平台，我们通过空间分辨光致发光测量通过在CsPbBr 3纳米线顶部堆叠CsPbCl 3、MAPbI（3）或MAPbBr（3）微板制造的异质结构来可视化和研究阳离子或阴离子互扩散动力学。时间依赖的共聚焦光致发光显微镜和能量色散X射线光谱表明，固态阴离子相互扩散容易发生，导致卤素浓度梯度沿着CsPbBr 3 - 3xCl 3 x（x = 0-1）纳米线。定量分析这样的组合物配置文件使用菲克定律允许我们，第一次，提取互扩散系数的氯-溴对和活化能为0.44 +/- 0.02 eV的离子扩散从温度依赖性的研究。相比之下，碘-溴互扩散是有限的，这可能是由于CsPb（Br，I）（3）的混合合金的复杂相行为。与相对移动的阴离子相反，在室温下几乎没有观察到穿过MAPbBr（3）/CsPbBr 3结的A位阳离子互扩散。我们的研究结果提供了一种研究固态离子迁移动力学的一般方法，并且所获得的关于离子扩散的见解可以为合理设计钙钛矿异质结构提供指导，这些异质结构可以为基础研究和技术应用带来新的性能。
The facile chemical transformation of metal halide perovskites via ion exchange has been attributed to their "soft" crystal lattices that enable fast ion migration. Kinetic studies of such processes could provide mechanistic insights on the ion migration dynamics. Herein, by using aligned single-crystal nanowires of cesium lead bromide (CsPbBr3) perovskite on epitaxial substrates as platforms, we visualize and investigate the cation or anion interdiffusion kinetics via spatially resolved photoluminescence measurement on heterostructures fabricated by stacking CsPbCl3, MAPbI(3), or MAPbBr(3) microplates on top of CsPbBr3 nanowires. Time-dependent confocal photoluminescence microscopy and energy-dispersive X-ray spectroscopy showed the solid-state anion interdiffusion readily occurs to result in halide concentration gradients along CsPbBr3-3xCl3x (x = 0-1) nanowires. Quantitative analysis of such composition profiles using Fick's law allowed us, for the first time, to extract interdiffusion coefficients of the chloride-bromide couple and an activation energy of 0.44 +/- 0.02 eV for ion diffusion from temperature-dependent studies. In contrast, iodide-bromide interdiffusion is limited, likely due to the complex phase behaviors of mixed alloys of CsPb(Br,I)(3). In contrast to the relatively mobile anions, A-site cation interdiffusion across the MAPbBr(3)/CsPbBr3 junctions was barely observed at room temperature. Our results present a general method to investigate the kinetics of the solid-state ion migration, and the gained insights on ion diffusion can provide guidelines for rationally designing perovskite heterostructures that could lead to new properties for fundamental studies and technological applications.