Refocusing <i>in Situ</i> Electron Microscopy: Moving beyond Visualization of Nanoparticle Self-Assembly To Gain Practical Insights into Advanced Material Fabrication.

Abstract

Despite incredible progress in preparing extended nanoparticle superlattices by self-assembly, theoretically predicted collective properties of extended nanoparticle superlattices are rarely correlated to observations due to the presence of defects. Enhanced fundamental understanding of the kinetics involved in nanoparticle superlattice self-assembly, specifically defect formation and annealing kinetics and mechanisms, is needed to prepare defect-free nanoparticle superlattices. <i>In situ</i> transmission electron microscopy (TEM) enables direct visualization of nanoparticle self-assembly phenomena in real time and at atomic spatial resolution; however, effective translation of <i>in situ</i> TEM data into new predictive models and material synthesis design rules remains a persistent challenge. Recent work by Ondry <i>et al.</i> in this issue of <i>ACS Nano</i> utilized atomic resolution <i>in situ</i> TEM to establish defect removal kinetics in epitaxially attached CdSe nanocrystal pairs, revealing a set of practical guidelines for minimizing defect formation in extended nanoparticle solids. Motivated by this work, in this Perspective, I explore and discuss the most effective and impactful uses of <i>in situ</i> TEM for nanoscience research and the associated technical barriers for performing <i>in situ</i> TEM measurements that are meaningful to bulk-scale self-assembly experiments.