Two-Fold Emission From the S-Shell of PbSe/CdSe Core/Shell Quantum Dots

Authors

  • Dominika Grodzińska,

    1. Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, Netherlands
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  • Wiel H. Evers,

    1. Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, Netherlands
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  • Renee Dorland,

    1. Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, Netherlands
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  • Jos van Rijssel,

    1. Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, Netherlands
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  • Marijn A. van Huis,

    1. Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
    2. EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium
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  • Andries Meijerink,

    1. Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, Netherlands
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  • Celso de Mello Donegá,

    Corresponding author
    1. Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, Netherlands
    • Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, Netherlands.
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  • Daniel Vanmaekelbergh

    Corresponding author
    1. Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, Netherlands
    • Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, Netherlands.
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Abstract

The optical properties of PbSe/CdSe core/shell quantum dots with core sizes smaller than 4 nm in the 5–300 K range are reported. The photoluminescence spectra show two peaks, which become increasingly separated in energy as the core diameter is reduced below 4 nm. It is shown that these peaks are due to intrinsic exciton transitions in each quantum dot, rather than emission from different quantum dot sub-ensembles. Most likely, the energy separation between the peaks is due to inter-valley coupling between the L-points of PbSe. The temperature dependence of the relative intensities of the peaks implies that the two emitting states are not in thermal equilibrium and that dark exciton states must play an important role.

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