Engineering and Direct Imaging of Nanoparticle Self-Assembly Pathways

Functional materials built from nanoparticle assemblies are enabling new applications in energy conversion and storage, optoelectronics, nanomedicine, among others. Essential to the realization of materials-by-design is to elucidate synthetic pathways and understand the kinetics of structural transitions. The process of nanoparticle assembly, like a chemical reaction, typically traverses a complex free-energy landscape before reaching the final state. Fully understanding these pathways requires real-space, real-time characterization with meaningful spatiotemporal resolution, which is difficult with existing ex-situ characterization or scattering-based techniques. In this talk, I will discuss our recent advances on direct imaging of nanoparticle assembly using liquid-phase electron microscopy. The interaction potential between nanoparticles can be readily tuned by changing the solvent, which enabled observation and quantitative analysis of nonclassical assembly pathways of nanoparticle superstructures.