Mechanistic Insights into Superlattice Transformation at a Single Nanocrystal Level Using Nanobeam Electron Diffraction
Mechanistic Insights into Superlattice Transformation at a Single Nanocrystal Level Using Nanobeam Electron Diffraction
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DOI：
10.1021/acs.nanolett.0c01579
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发表时间：
2020-07-08
期刊：
影响因子：
10.8
通讯作者：
Hanrath, Tobias
中科院分区：
文献类型：
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作者：
daSilva, Jessica Cimada;Smeaton, Michelle A.;Hanrath, Tobias
了解纳米晶(NC)超晶格组装和附着的机理并最终指导其组装和附着，对这一新兴领域的未来发展具有重要的意义。在这里，我们使用4D-STEM研究了在大视场下从六方组装到非连通的方形超晶格的不同阶段的PbS纳米管的单层结构。用电子显微镜像素阵列探测器(EMPAD)获取的纳米束电子衍射图样提供了多面体NCS的3D晶体排列的前所未有的细节。我们的分析表明，超晶格相变是由沿<；11n>；(Al)方向强耦合的预对准NCs的平移主导的，并在整个单晶中随机和逐渐地发生。我们用常规的透射电子显微镜和选区电子衍射研究了类似的PbSe NC组件的结构，从而验证了所提出的机制的通用性。本文的实验结果为NC自组装和定向附着提供了新的机械学见解。
Understanding the mechanism and ultimately directing nanocrystal (NC) superlattice assembly and attachment have important implications on future advances in this emerging field. Here, we use 4D-STEM to investigate a monolayer of PbS NCs at various stages of the transformation from a hexatic assembly to a nonconnected square-like superlattice over large fields of view. Maps of nanobeam electron diffraction patterns acquired with an electron microscope pixel array detector (EMPAD) offer unprecedented detail into the 3D crystallographic alignment of the polyhedral NCs. Our analysis reveals that superlattice transformation is dominated by translation of prealigned NCs strongly coupled along the < 11n >(AL) direction and occurs stochastically and gradually throughout single grains. We validate the generality of the proposed mechanism by examining the structure of analogous PbSe NC assemblies using conventional transmission electron microscopy and selected area electron diffraction. The experimental results presented here provide new mechanistic insights into NC self-assembly and oriented attachment.