Anisotropic Transient Disordering of Colloidal, Two-Dimensional CdSe Nanoplatelets upon Optical Excitation

Alexandra Brumberg, Matthew S. Kirschner, Benjamin T. Diroll, Kali R. Williams, Nathan C. Flanders, Samantha M. Harvey, Ariel A. Leonard, Nicolas E. Watkins, Cunming Liu, Eli D. Kinigstein, Jin Yu, Austin M. Evans, Yuzi Liu, Shelby A. Cuthriell, Shobhana Panuganti, William R. Dichtel, Mercouri G. Kanatzidis, Michael R. Wasielewski, Xiaoyi Zhang, Lin X. ChenRichard D. Schaller*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Nanoplatelets (NPLs) - colloidally synthesized, spatially anisotropic, two-dimensional semiconductor quantum wells - are of intense interest owing to exceptionally narrow transition line widths, coupled with solution processability and bandgap tunability. However, given large surface areas and undercoordinated bonding at facet corners and edges, excitation under sufficient intensities may induce anisotropic structural instabilities that impact desired properties. We employ time-resolved X-ray diffraction to study the crystal structure of CdSe NPLs in response to optical excitation. Photoexcitation induces greater out-of-plane than in-plane disordering in 4 and 5 monolayer (ML) NPLs, while 3 ML NPLs display the opposite behavior. Recovery dynamics suggest that out-of-plane cooling slightly outpaces in-plane cooling in 5 ML NPLs with recrystallization occurring on indistinguishable time scales. In comparison, for zero-dimensional CdSe nanocrystals, disordering is isotropic and recovery is faster. These results favor the use of NPLs in optoelectronic applications, where they are likely to exhibit superior performance over traditional, zero-dimensional nanocrystals.

Original languageEnglish (US)
Pages (from-to)1288-1294
Number of pages7
JournalNano letters
Volume21
Issue number3
DOIs
StatePublished - Feb 10 2021

Keywords

  • Nanoplatelets
  • X-ray diffraction
  • anisotropic disordering
  • nonequilibrium phenomena
  • transient heating

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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