Ultrafast Exciton Dynamics in CdxHg(1-x)Te alloy Quantum Dots

Marina A Leontiadou; Ali Al-Otaify; Stephen V Kershaw; Olga Zhovtiuk; Sergii Kalytchuk; Derrick Mott; Shinya Maenosono; Andrey L Rogach; David J Binks

doi:10.1016/j.chemphys.2016.02.003

Ultrafast Exciton Dynamics in Cd_xHg_(1-x)Te alloy Quantum Dots

Marina A Leontiadou, Ali Al-Otaify, Stephen V Kershaw, Olga Zhovtiuk, Sergii Kalytchuk, Derrick Mott, Shinya Maenosono, Andrey L Rogach, David J Binks

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Abstract

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 91Ã‚Â±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 115Ã‚Â±1% for pump photons with energy equivalent to 2.6 times the band gap.

Original language	English
Pages (from-to)	25-30
Number of pages	6
Journal	Chemical Physics
Volume	469-470
Early online date	24 Feb 2016
DOIs	https://doi.org/10.1016/j.chemphys.2016.02.003
Publication status	Published - May 2016

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1 Chapter

Charge Dynamics in Colloidal Quantum Dots: Recombination, Trapping and Multiple Exciton Generation
Leontiadou, M., Smith, C., Lydon, C. & Binks, D., 2018, Nanostructured Materials for Type III Photovoltaics. Skabara, P. & Malik, M. A. (eds.). Cambridge: Royal Society of Chemistry, p. 472-507 (Nanoscience and Nanotechnology).
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Cite this

@article{ec0b4730a56640ae85b50e86d75cef4b,

title = "Ultrafast Exciton Dynamics in CdxHg(1-x)Te alloy Quantum Dots",

abstract = "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{\~A}‚{\^A}±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{\~A}‚{\^A}±1% for pump photons with energy equivalent to 2.6 times the band gap.",

author = "Leontiadou, {Marina A} and Ali Al-Otaify and Kershaw, {Stephen V} and Olga Zhovtiuk and Sergii Kalytchuk and Derrick Mott and Shinya Maenosono and Rogach, {Andrey L} and Binks, {David J}",

note = "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 experimental data from this study is available at DOI 10.15127/1.296944.",

year = "2016",

month = may,

doi = "10.1016/j.chemphys.2016.02.003",

language = "English",

volume = "469-470",

pages = "25--30",

journal = "Chemical Physics",

issn = "0301-0104",

publisher = "Elsevier BV",

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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 - 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 experimental data from this study is available at DOI 10.15127/1.296944.

PY - 2016/5

Y1 - 2016/5

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 91Ã‚Â±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 115Ã‚Â±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 91Ã‚Â±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 115Ã‚Â±1% for pump photons with energy equivalent to 2.6 times the band gap.

U2 - 10.1016/j.chemphys.2016.02.003

DO - 10.1016/j.chemphys.2016.02.003

M3 - Article

SN - 0301-0104

VL - 469-470

SP - 25

EP - 30

JO - Chemical Physics

JF - Chemical Physics

ER -

Ultrafast Exciton Dynamics in CdxHg(1-x)Te alloy Quantum Dots

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Research output

Charge Dynamics in Colloidal Quantum Dots: Recombination, Trapping and Multiple Exciton Generation

Cite this

Ultrafast Exciton Dynamics in Cd_xHg_(1-x)Te alloy Quantum Dots