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

Journal article (2011)

Authors

D Grodzinska External organisation
WH Evers External organisation
L Dorland External organisation
J van Rijssel External organisation
A. Meijerink External organisation
CD Donega External organisation
D Vanmaekelbergh External organisation
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Published Date

2011

Language

English

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Abstract

The optical properties of PbSe/CdSe core/shell quantum dots with core sizes smaller than 4 nm in the 5300 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.