Multiexciton Absorption Cross Sections of CdSe Quantum Dots Determined by Ultrafast Spectroscopy
Nils Lenngren
Tommy Garting
Kaibo Zheng
Mohamed Abdellah
Noëlle Lascoux
Fei Ma
Arkady Yartsev
Karel Žídek
Tõnu Pullerits
10.1021/jz401522h.s001
https://acs.figshare.com/articles/journal_contribution/Multiexciton_Absorption_Cross_Sections_of_CdSe_Quantum_Dots_Determined_by_Ultrafast_Spectroscopy/2025942
Multiexciton absorption cross sections are important for analysis of a number of experiments, including multiple exciton generation and stimulated emisson. We present a rigorous method to determine these cross sections using transient absorption (TA) measurements. We apply the method to CdSe quantum dots (QDs) and core–shell (CdSe)ZnS QDs. The method involves measuring TA dynamics for various excitation intensities over a broad time range and analyzing the experiments in terms of a kinetic multiexciton model taking into account all contributions to the signal. In this way, we were able to quantify exciton and multiexciton absorption cross sections at different spectral positions. The absorption cross sections decrease with increasing number of excitations, qualitatively in agreement with the state-filling effective mass model but showing a slower decrease. The cross sections for single-exciton to biexciton absorption range between 57 and 99% of the ground to single-exciton cross section.
2015-12-16 23:37:52
mass model
Ultrafast SpectroscopyMultiexciton absorption
TA dynamics
method
biexciton absorption range
sections decrease
multiexciton model
exciton generation
CdSe Quantum Dots
QD
Multiexciton Absorption Cross Sections
multiexciton absorption
time range
excitation intensities
CdSe quantum dots