Interfacial Self-Assembly and Oriented Attachment in the Family of PbX (X = S, Se, Te) Nanocrystals

The realization of materials with new optoelectronic properties draws much scientific attention towards the field of nanocrystal superstructures. Low-dimensional superstructures created by interfacial assembly and oriented attachment of PbSe nanocrystals are a striking example, since theory showed that PbSe sheets with a honeycomb geometry possess non-trivial flat bands and Dirac cones in the valence and conduction bands. Here, we report on the formation of 1D linear and zigzag structures, and 2D square and honeycomb structures for the entire lead chalcogenide family: PbX (X = S, Se, Te). We observe that PbTe, with a lower bulk melting temperature and enthalpy of formation than PbSe, shows a higher nanocrystal surface reactivity, such that the surface must be passivated and the reaction conditions moderated to obtain reasonably ordered superstructures. The present findings constitute a step forwards in the realization of a larger family of atomically coherent 2D superstructures with variable IV-VI and II-...