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Two‐Fold Emission From the S‐Shell of PbSe/CdSe Core/Shell Quantum Dots
Author(s) -
Grodzińska Dominika,
Evers Wiel H.,
Dorland Renee,
van Rijssel Jos,
van Huis Marijn A.,
Meijerink Andries,
de Mello Donegá Celso,
Vanmaekelbergh Daniel
Publication year - 2011
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201101819
Subject(s) - quantum dot , exciton , photoluminescence , core (optical fiber) , shell (structure) , spectral line , molecular physics , materials science , biexciton , emission spectrum , condensed matter physics , atomic physics , coupling (piping) , physics , nanotechnology , optoelectronics , quantum mechanics , composite material , metallurgy
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.