The directed assembly of nanoscale building blocks into complex superstructures is of widespread scientific and technological interest. Scientists and engineers have been intrigued by the prospects of tailoring self-assembly processes to create materials whose properties and function can be tuned through the interaction between constituent particles. In particular, Recent reports of epitaxially connected CQD superlattices with long-range atomic coherence have generated significant interest as a platform for novel, quasi 2D ‘designer materials’. Experimental protocols for the formation of high quality superlattices in which constituent quantum dots are registered to within a single atomic bond length have been established; however, significant gaps persist in our fundamental understanding of several aspects of the underlying mechanism by which these structures form.
Astonishingly, the irreversible attachment of proximate particles through mutually exposed ‘sticky {100} facets’ occurs in a manner that enables the formation of structures with atomic coherence with micrometer-sized grains. In the enclosed manuscript, we present a mechanism for this transformation based on a coherent phase transition with distinct nucleation and propagation steps. Specifically, we show that the transformation is nucleated at defects (voids or grain boundaries) in the pre-assembled superlattice.
Kevin’s paper is available here:
J. Phys. Chem. Lett., 2017, 8 (12), pp 2623–2628
DOI: 10.1021/acs.jpclett.7b00846