Atomic Lattice Resolved Electron Tomography of a 3D Self‐Assembled Mesocrystal

Abstract

Complex 3D architectures of nanoscale building blocks can be created by selfassembly, but characterization of the atomic to mesoscale structure of such materials is limited by the difficulty of visualizing atoms across multiple length scales. Here, scanning transmission electron microscopy (STEM) and full-tilt tomographic reconstruction are used to image a single-crystalline region of a 3D epitaxially-fused PbSe quantum dot (QD) superlattice containing 633 QDs at a spatial resolution of 2.16 Å. The combined real-space and reciprocal-space analysis enables 3D mesoscale correlations of atomic lattice and superlattice order across hundreds of nanocrystals in 3D for the first time. Inhomogeneity in QD positional and orientational order reveals that the QD surface layers template the superlattice and that orientational entropy is higher in the interior layers than the surface layers. The measurement and analysis techniques presented here are applicable to a broad range of 3D nanostructured materials.

Randomly Layered Superstructure of In2O3 Truncated Nano-Octahedra and Its High-Pressure Behavior

“…Additionally, various factors, including changes in the concentration gradient during the assembling process, variation in assembling rate, and different environmental conditions such as temperature and humidity, further contribute to increasing the complexity of the self-assembly process. Consequently, self-assembled superlattices often exhibit abundant structure defects, , such as planar defects, which can significantly impact structure characteristics and may even mislead the structure evaluation if treated as a classic 3D periodic arrangement.…”

“…20 Additionally, various factors, including changes in the concentration gradient during the assembling process, variation in assembling rate, and different environmental conditions such as temperature and humidity, further contribute to increasing the complexity of the self-assembly process. Consequently, self-assembled superlattices often exhibit abundant structure defects, 29,30 mislead the structure evaluation if treated as a classic 3D periodic arrangement. Among planar defects, stacking faults frequently appear in both natural and synthetic lamellar materials, 31 with instances observed in substances like coals, 32 graphene oxide, 33 vermiculite, 34 calcium silicate hydrates, 35 zeolite, 36 two-dimensional (2D) oxide colloids, 37 clay, 38 transition-metal dichalcogenides such as WS 2 and MoS 2 , 39 and chalcopyrite semiconductor nanosheets, notably CuInS 2 .…”