Two-fold emission from the S-shell of PbSe/CdSe core/shell quantum dots.
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.
Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, Netherlands.
Dominika
D
Grodzińska
Wiel H
WH
Evers
Renee
R
Dorland
Jos
J
van Rijssel
Marijn A
MA
van Huis
Andries
A
Meijerink
Celso
C
de Mello Donegá
Daniel
D
Vanmaekelbergh
D000042:Absorption; D019187:Cadmium Compounds / Q000737:chemistry*; D007854:Lead / Q000737:chemistry*; D008163:Luminescent Measurements; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry / Q000648:ultrastructure; D055620:Optical Phenomena; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry*; D013057:Spectrum Analysis; D013696:Temperature
D019187:Cadmium Compounds; D018036:Selenium Compounds; C088065:lead selenide; D007854:Lead; C058667:cadmium selenide