TY - JOUR
T1 - Ultrafast Exciton Dynamics in CdxHg(1-x)Te alloy Quantum Dots
AU - Leontiadou, Marina A.
AU - Al-Otaify, Ali
AU - Kershaw, Stephen V.
AU - Zhovtiuk, Olga
AU - Kalytchuk, Sergii
AU - Mott, Derrick
AU - Maenosono, Shinya
AU - Rogach, Andrey L.
AU - Binks, David J.
N1 - Funding Information:
MAL and DJB acknowledge EPSRC for financial support (Grant number EP/K008544/1 ). AAl-O thanks the Ministry of Higher Education of Saudi Arabia for the financial support. SVK and ALR thank the Research Grants Council of Hong Kong S.A.R. for financial support (GRF project 102412). The authors would like to thank Lazo Kakou for the graphical abstract.
Publisher Copyright:
© 2016 The Authors.
PY - 2016/5/1
Y1 - 2016/5/1
N2 - Ultrafast transient absorption spectroscopy is used to investigate sub-nanosecond exciton dynamics in CdxHg(1-x)Te alloy colloidal quantum dots. A bleach was observed at the band gap due to state-filling, the mono-exponential decay of which had a characteristic lifetime of 91 ± 1 ps and was attributed to biexciton recombination; no evidence of surface-related trapping was observed. The rise time of the bleach, which is determined by the rate at which hot electrons cool to the band-edge, ranged between 1 and 5 ps depending on the pump photon energy. Measuring the magnitude of the bleach decay for different pump fluences and wavelengths allowed the quantum yield of multiple exciton generation to be determined, and was 115 ± 1% for pump photons with energy equivalent to 2.6 times the band gap.
AB - Ultrafast transient absorption spectroscopy is used to investigate sub-nanosecond exciton dynamics in CdxHg(1-x)Te alloy colloidal quantum dots. A bleach was observed at the band gap due to state-filling, the mono-exponential decay of which had a characteristic lifetime of 91 ± 1 ps and was attributed to biexciton recombination; no evidence of surface-related trapping was observed. The rise time of the bleach, which is determined by the rate at which hot electrons cool to the band-edge, ranged between 1 and 5 ps depending on the pump photon energy. Measuring the magnitude of the bleach decay for different pump fluences and wavelengths allowed the quantum yield of multiple exciton generation to be determined, and was 115 ± 1% for pump photons with energy equivalent to 2.6 times the band gap.
KW - CdHgTe alloy quantum dot
KW - Femtosecond transient absorption spectroscopy
KW - Multiple exciton generation
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U2 - 10.1016/j.chemphys.2016.02.003
DO - 10.1016/j.chemphys.2016.02.003
M3 - Article
AN - SCOPUS:84959541018
SN - 0301-0104
VL - 469-470
SP - 25
EP - 30
JO - Chemical Physics
JF - Chemical Physics
ER -