Self-assembly of shape-controlled nanocrystals and their in-situ thermodynamic properties

Size and shape selected nanocrystals behave like molecular matter that can be used as fundamental building blocks for constructing nanocrystal assembled superlattices. The nanocrystals form a new class of materials that have orders in both atomic and nanocrystal length-scales. The nanocrystals are passivated with organic molecules (called thiolates) that not only protect them from coalescence but act as the molecular bonds for forming the superlattice structure. The interparticle distance is adjustable, possibly resulting in tunable electric, optical and transport properties. This paper reviews our current progress in nanocrystal self-assembled materials and their thermodynamic properties probed by in-situ transmission electron microscopy (TEM). The studies mainly focused on size and shape-controlled nanocrystals to understand the role played by particle shape in determining their physical and chemical properties. Recent studies on photonic crystals and mesoporous materials such as silica and titania are also presented.