Ultrafast Exciton Dynamics in CdxHg(1-x)Te alloy Quantum Dots

Marina A. Leontiadou, Ali Al-Otaify, Stephen V. Kershaw, Olga Zhovtiuk, Sergii Kalytchuk, Derrick Mott, Shinya Maenosono, Andrey L. Rogach, David J. Binks

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

Ultrafast transient absorption spectroscopy is used to investigate sub-nanosecond exciton dynamics in CdxHg(1-x)Te alloy colloidal quantum dots. A bleach was observed at the band gap due to state-filling, the mono-exponential decay of which had a characteristic lifetime of 91 ± 1 ps and was attributed to biexciton recombination; no evidence of surface-related trapping was observed. The rise time of the bleach, which is determined by the rate at which hot electrons cool to the band-edge, ranged between 1 and 5 ps depending on the pump photon energy. Measuring the magnitude of the bleach decay for different pump fluences and wavelengths allowed the quantum yield of multiple exciton generation to be determined, and was 115 ± 1% for pump photons with energy equivalent to 2.6 times the band gap.

Original languageEnglish
Pages (from-to)25-30
Number of pages6
JournalChemical Physics
Volume469-470
DOIs
Publication statusPublished - 2016 May 1
Externally publishedYes

Keywords

  • CdHgTe alloy quantum dot
  • Femtosecond transient absorption spectroscopy
  • Multiple exciton generation

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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