Dynamical Self-assembly during Colloidal Droplet Evaporation Studied by in situ Small Angle X-ray Scattering

TL;DR

This study uses in situ small-angle X-ray scattering to reveal how evaporation kinetics influence the formation and dimensionality of nanocrystal superlattices during colloidal droplet evaporation.

Contribution

It demonstrates for the first time that evaporation kinetics can determine the dimensionality of nanocrystal superlattices, highlighting the role of interface crushing in 2D superlattice formation.

Findings

Evaporation kinetics affect superlattice dimensionality.

2D nanocrystal superlattices form at the liquid-air interface.

Superlattice growth follows exponential kinetics due to interface crushing.

Abstract

The nucleation and growth kinetics of highly ordered nanocrystal superlattices during the evaporation of nanocrystal colloidal droplets was elucidated by in situ time resolved small-angle x-ray scattering. We demonstrated for the first time that evaporation kinetics can affect the dimensionality of the superlattices. The formation of two-dimensional nanocrystal superlattices at the liquid-air interface of the droplet has an exponential growth kinetics that originates from interface "crushing".