Visualizing Nonradiative Mobile Defects in Organic–Inorganic Perovskite Materials,Small Methods

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Visualizing Nonradiative Mobile Defects in Organic–Inorganic Perovskite Materials
Small Methods ( IF 10.7 ) Pub Date : 2019-04-08 , DOI: 10.1002/smtd.201900110
Olivia Hentz ₁ , Akshay Singh ₁ , Zhibo Zhao ₁ , Silvija Gradečak ₁

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Organic–inorganic perovskite materials have mobile charged point defects that migrate in response to voltage biasing and illumination, causing device performance variation over time. Improvements in device stability and reliability require methods to visualize point defect migration, estimate ionic mobilities, and identify factors influencing their migration. In this work, a versatile method is demonstrated to track nonradiative point defect migration in situ. Photoluminescence mapping of laterally biased perovskite films is used to track continuous changes in nonradiative recombination as charge‐trapping defects migrate between the device electrodes. A Monte Carlo framework of defect drift and diffusion is developed that is consistent with experimental photoluminescence observations, which combined enables point defect mobility estimation in methylammonium lead iodide films. Furthermore, measurements performed on materials with varied grain sizes demonstrate that point defect mobility is 1500× faster at grain boundaries compared to bulk. These findings imply that grain morphology can be used to tune point defect mobility such that large‐grained or single‐crystal materials inhibit point defect migration. The methods used in this work can be applied to visualize and quantify the migration of charge‐trapping point defects in a wide range of state‐of‐the‐art perovskite materials targeted toward reduced ionic mobilities and superior device stability.

中文翻译：

可视化有机-无机钙钛矿材料中的非辐射移动缺陷

有机-无机钙钛矿材料具有可移动的带电点缺陷，这些缺陷会随电压偏置和照明而迁移，从而导致器件性能随时间变化。器件稳定性和可靠性的提高要求采用可视化点缺陷迁移，估算离子迁移率以及识别影响其迁移的因素的方法。在这项工作中，展示了一种通用的方法来现场跟踪非辐射点缺陷迁移。当电荷俘获缺陷在器件电极之间迁移时，横向偏置钙钛矿膜的光致发光映射用于跟踪非辐射复合的连续变化。建立了缺陷漂移和扩散的蒙特卡洛框架，该框架与实验性光致发光观察一致，结合使用，可以估算甲基铵碘化铅薄膜中的点缺陷迁移率。此外，对具有不同晶粒尺寸的材料进行的测量表明，与块体相比，晶界处的点缺陷迁移率快1500倍。这些发现表明，晶粒形态可用于调整点缺陷的迁移率，以便大晶粒或单晶材料抑制点缺陷的迁移。这项工作中使用的方法可用于可视化和量化电荷捕集点缺陷在一系列旨在降低离子迁移率和提高器件稳定性的先进钙钛矿材料中的迁移。对具有不同晶粒尺寸的材料进行的测量表明，与块体相比，晶界处的点缺陷迁移率快1500倍。这些发现表明，晶粒形态可用于调整点缺陷的迁移率，以便大晶粒或单晶材料抑制点缺陷的迁移。这项工作中使用的方法可用于可视化和量化电荷捕集点缺陷在一系列旨在降低离子迁移率和提高器件稳定性的先进钙钛矿材料中的迁移。对具有不同晶粒尺寸的材料进行的测量表明，与块体相比，晶界处的点缺陷迁移率快1500倍。这些发现表明，晶粒形态可用于调整点缺陷的迁移率，以便大晶粒或单晶材料抑制点缺陷的迁移。这项工作中使用的方法可用于可视化和量化电荷捕集点缺陷在一系列旨在降低离子迁移率和提高器件稳定性的先进钙钛矿材料中的迁移。

更新日期：2019-04-08

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