In situ study of the formation mechanism of two-dimensional superlattices from PbSe nanocrystals

J.J. Geuchies, C. van Overbeek, W.H. Evers, Bart Goris, Annick de Backer, A.P. Gantapara, F.T. Rabouw, J. Hilhorst, J.L. Peters, Oleg Konovalov, Andrei V. Petukhov, M. Dijkstra, Laurens D A Siebbeles, S. Van Aert, Sara Bals, D.A.M. Vanmaekelbergh*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Oriented attachment of PbSe nanocubes can result in the formation of two-dimensional (2D) superstructures with long-range nanoscale and atomic order1,2. This questions the applicability of classic models in which the superlattice grows by first forming a nucleus, followed by sequential irreversible
attachment of nanocrystals3,4, as one misaligned attachment would disrupt the 2D order beyond repair. Here, we demonstrate the formation mechanism of 2D PbSe superstructures with square geometry by using in situ grazing-incidence X-ray scattering (small angle and wide angle), ex situ electron microscopy, and Monte Carlo simulations. We observed nanocrystal adsorption at the liquid/gas interface, followed by the formation of a hexagonal nanocrystal monolayer. The hexagonal geometry transforms gradually through a pseudo-hexagonal phase into a phase with square order, driven by attractive interactions between the {100} planes perpendicular to the liquid substrate, which maximize facetto-
facet overlap. The nanocrystals then attach atomically via a necking process, resulting in 2D square superlattices.
Original languageEnglish
Pages (from-to)1248-1254
Number of pages7
JournalNature Materials
Issue number12
Publication statusPublished - Dec 2016


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