title: Site-Specific Ligand Interactions Favor the Tetragonal Distortion of PbS Nanocrystal Superlattices.
abstract: We analyze the structure and morphology of mesocrystalline, body-centered tetragonal (bct) superlattices of PbS nanocrystals functionalized with oleic acid. On the basis of combined scattering and real space imaging, we derive a three-dimensional (3D) model of the superlattice and show that the bct structure benefits from a balanced combination of {100}PbS-{100}PbS and {111}PbS-{111}PbS interactions between neighboring layers of nanocrystals, which uniquely stabilizes this structure. These interactions are enabled by the coaxial alignment of the atomic lattices of PbS with the superlattice. In addition, we find that this preferential orientation is already weakly present within isolated monolayers. By adding excess oleic acid to the nanocrystal solution, tetragonal distortion is suppressed, and we observe assembly into a bilayered hexagonal lattice reminiscent of a honeycomb with grain sizes of several micrometers.
authors: Central European Institute of Technology, Masaryk University , Kamenice 5, CZ-62500 Brno, Czech Republic.|Department of Condensed Matter Physics, Masaryk University , Kotlářská 2, CZ-61137 Brno, Czech Republic.
authors: Jiřı́
authors: J
authors: Novák
authors: Department of Physics, Indian Institute of Technology Gandhinagar , Palaj, Gandhinagar 382355, India.
authors: Rupak
authors: R
authors: Banerjee
authors: Institute of Physical Chemistry and The Hamburg Centre for Ultrafast Imaging, University of Hamburg , Grindelallee 117, 20146 Hamburg, Germany.
authors: Andreas
authors: A
authors: Kornowski
authors: Beamline ID03, European Synchrotron Radiation Facility , Grenoble F-38043, France.
authors: Maciej
authors: M
authors: Jankowski
authors: Institute of Physical and Theoretical Chemistry, University of Tübingen , Auf der Morgenstelle 18, 72076 Tübingen, Germany.
authors: Alexander
authors: A
authors: André
authors: Institute of Physical Chemistry and The Hamburg Centre for Ultrafast Imaging, University of Hamburg , Grindelallee 117, 20146 Hamburg, Germany.
authors: Horst
authors: H
authors: Weller
authors: Institute of Applied Physics, University of Tübingen , Auf der Morgenstelle 10, 72076 Tübingen, Germany.|Center for Light-Matter Interaction, Sensors & Analytics, University of Tübingen , Auf der Morgenstelle 15, 72076 Tübingen, Germany.
authors: Frank
authors: F
authors: Schreiber
authors: Institute of Physical and Theoretical Chemistry, University of Tübingen , Auf der Morgenstelle 18, 72076 Tübingen, Germany.|Center for Light-Matter Interaction, Sensors & Analytics, University of Tübingen , Auf der Morgenstelle 15, 72076 Tübingen, Germany.
authors: Marcus
authors: M
authors: Scheele
keywords: X-ray scattering; electron microscopy; mesocrystals; nanocrystals; self-assembly