Unusually Strong Biexciton Repulsion Detected in Quantum Confined CsPbBr3Nanocrystals with Two and Three Pulse Femtosecond Spectroscopy

Jayanta Dana, Tal Binyamin, Lioz Etgar, Sanford Ruhman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Transient absorption measurements were conducted on pristine and monoexciton saturated CsPbBr3 nanocrystals varying in size within the regime of a strong quantum confinement. Once the difference spectra were translated to absolute transient changes in absorption cross section, a single exciton is shown to completely bleach the band edge absorption peak and induce a new absorption roughly two times weaker ∼100 meV to the blue. Difference spectra obtained during Auger recombination of biexciton demonstrate that the addition of a second exciton, rather than double the effect of a first, bleaches the blue-induced absorption band without producing a net stimulated emission at the band edge. Accompanied by high time resolution transient absorption spectra pumping at the lowest exciton band, these results identify the blue-induced absorption as the second transition to 1Se1Sh which is shifted in energy due to unusually strong and promptly rising biexciton repulsion. Possible mechanisms giving rise to this repulsion and prospects for applying it to enhance optical gain applications of these particles are discussed.

Original languageAmerican English
Pages (from-to)9039-9047
Number of pages9
JournalACS Nano
Volume15
Issue number5
DOIs
StatePublished - 25 May 2021

Bibliographical note

Publisher Copyright:
© 2021 American Chemical Society.

Keywords

  • biexciton repulsion
  • perovskite
  • quantum confined
  • spectator exciton
  • stimulated emission

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