Nano-engineered electron-hole exchange interaction controls exciton dynamics in core-shell semiconductor nanocrystals

S. Brovelli, R. D. Schaller, S. A. Crooker, F. García-Santamaría, Y. Chen, R. Viswanatha, J. A. Hollingsworth, H. Htoon, V. I. Klimov

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Abstract

A strong electron-hole exchange interaction (EI) in semiconductor nanocrystals (NCs) gives rise to a large (up to tens of meV) splitting between optically active ('bright') and optically passive ('dark') excitons. This dark-bright splitting has a significant effect on the optical properties of band-edge excitons and leads to a pronounced temperature and magnetic field dependence of radiative decay. Here we demonstrate a nanoengineering-based approach that provides control over EI while maintaining nearly constant emission energy. We show that the dark-bright splitting can be widely tuned by controlling the electron-hole spatial overlap in core-shell CdSe/CdS NCs with a variable shell width. In thick-shell samples, the EI energy reduces to <250 μeV, which yields a material that emits with a nearly constant rate over temperatures from 1.5 to 300 K and magnetic fields up to 7 T. The EI-manipulation strategies demonstrated here are general and can be applied to other nanostructures with variable electron-hole overlap.

Original languageEnglish
Article number280
JournalNature communications
Volume2
Issue number1
DOIs
Publication statusPublished - Apr 27 2011

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ASJC Scopus subject areas

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)

Cite this

Brovelli, S., Schaller, R. D., Crooker, S. A., García-Santamaría, F., Chen, Y., Viswanatha, R., Hollingsworth, J. A., Htoon, H., & Klimov, V. I. (2011). Nano-engineered electron-hole exchange interaction controls exciton dynamics in core-shell semiconductor nanocrystals. Nature communications, 2(1), [280]. https://doi.org/10.1038/ncomms1281