Energy landscape of self-assembled superlattices of PbSe nanocrystals

Zewei Quan, Di Wu, Jinlong Zhu, Wiel H. Evers, James M. Boncella, Laurens D.A. Siebbeles, Zhongwu Wang, Alexandra Navrotsky, Hongwu Xu

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

Self-assembly of nanocrystals (NCs) into superlattices is an intriguing multiscale phenomenon that may lead to materials with novel collective properties, in addition to the unique properties of individual NCs compared with their bulk counterparts. By using different dispersion solvents, we synthesized three types of PbSe NC superlattices - body-centered cubic (bcc), body-centered tetragonal (bct), and face-centered cubic (fcc) - as confirmed by synchrotron small-angle X-ray scattering. Solution calorimetric measurements in hexane show that the enthalpy of formation of the superlattice from dispersed NCs is on the order of -2 kJ/mol. The calorimetric measurements reveal that the bcc superlattice is the energetically most stable polymorph, with the bct being 0.32 and the fcc 0.55 kJ/mol higher in enthalpy. This stability sequence is consistent with the decreased packing efficiency of PbSe NCs from bcc (17.2%) to bct (16.0%) and to fcc (15.2%). The small enthalpy differences among the three polymorphs confirm a closely spaced energy landscape and explain the ease of formation of different NC superlattices at slightly different synthesis conditions.

Original languageEnglish (US)
Pages (from-to)9054-9057
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Volume111
Issue number25
DOIs
StatePublished - Jun 24 2014
Externally publishedYes

Keywords

  • Ligand interaction
  • PbSe nanocrystal superlattices
  • Thermodynamics

ASJC Scopus subject areas

  • General

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