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Efficient Biexciton Emission in Elongated CdSe/ZnS Nanocrystals

Abstract : We use a combination of low-temperature magneto-optical and lifetime spectroscopies to study the band-edge exciton fine structure of highly photostable single CdSe/ZnS nanocrystals (NCs). Neutral NCs displaying multiline emission spectra and multiexponential photoluminescence (PL) decays are studied as a function of temperature and external magnetic fields. Three different fine structure regimes are identified as a function of the NC aspect ratio. In particular, we identify an optically inactive ground exciton state, whose oscillator strength is tuned up under magnetic field coupling to bright exciton states, and attribute it to the zero angular momentum ground exciton state of elongated NCs. We also show evidence for highly efficient biexciton emission in these NCs, with radiative yields approaching unity in some cases. We use a combination of low-temperature magneto-optical and lifetime spectroscopies to study the band-edge exciton fine structure of highly photostable single CdSe/ZnS nanocrystals (NCs). Neutral NCs displaying multiline emission spectra and multiexponential photoluminescence (PL) decays are studied as a function of temperature and external magnetic fields. Three different fine structure regimes are identified as a function of the NC aspect ratio. In particular, we identify an optically inactive ground exciton state, whose oscillator strength is tuned up under magnetic field coupling to bright exciton states, and attribute it to the zero angular momentum ground exciton state of elongated NCs. We also show evidence for highly efficient biexciton emission in these NCs, with radiative yields approaching unity in some cases.
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https://hal.archives-ouvertes.fr/hal-00668360
Contributor : Bernadette Bergeret Connect in order to contact the contributor
Submitted on : Thursday, February 9, 2012 - 4:33:55 PM
Last modification on : Monday, November 1, 2021 - 2:26:02 PM

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Yann Louyer, Louis Biadala, Jean-Baptiste Trebbia, Mark J. Fernée, Philippe Tamarat, et al.. Efficient Biexciton Emission in Elongated CdSe/ZnS Nanocrystals. Nano Letters, American Chemical Society, 2011, 11 (10), pp.4370-4375. ⟨10.1021/nl202506c⟩. ⟨hal-00668360⟩

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