Ultrafast exciton dynamics in InAs/ZnSe nanocrystal quantum dots

Musa Cadirci; Stuart K. Stubbs; Samantha J O Hardman; Ombretta Masala; Guy Allan; Christophe Delerue; Nigel Pickett; David J. Binks

doi:10.1039/c2cp42125a

Ultrafast exciton dynamics in InAs/ZnSe nanocrystal quantum dots

Musa Cadirci, Stuart K. Stubbs, Samantha J O Hardman, Ombretta Masala, Guy Allan, Christophe Delerue, Nigel Pickett, David J. Binks

Research output: Contribution to journal › Article › peer-review

Abstract

Colloidal nanocrystal quantum dots with a band gap in the near infra-red have potential application as the emitters for telecommunications or in vivo imaging, or as the photo-absorbing species in next generation solar cells or photodetectors. However, electro- and photoluminescence yields and the efficiency with which photo-generated charges can be extracted from quantum dots depend on the total rate of recombination, which can be dominated by surface-mediated processes. In this study, we use ultrafast transient absorption spectroscopy to characterise the recombination dynamics of photo-generated charges in InAs/ZnSe nanocrystal quantum dots. We find that recombination is dominated by rapid, sub-nanosecond transfer of conduction band electrons to surface states. For the size of dots studied, we also find no evidence of significant multiple exciton generation for photon energies up to 3.2 times the band gap, in agreement with our theoretical modelling. This journal is © 2012 the Owner Societies.

Original language	English
Pages (from-to)	15166-15172
Number of pages	6
Journal	Physical Chemistry Chemical Physics
Volume	14
Issue number	43
DOIs	https://doi.org/10.1039/c2cp42125a
Publication status	Published - 21 Nov 2012

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title = "Ultrafast exciton dynamics in InAs/ZnSe nanocrystal quantum dots",

abstract = "Colloidal nanocrystal quantum dots with a band gap in the near infra-red have potential application as the emitters for telecommunications or in vivo imaging, or as the photo-absorbing species in next generation solar cells or photodetectors. However, electro- and photoluminescence yields and the efficiency with which photo-generated charges can be extracted from quantum dots depend on the total rate of recombination, which can be dominated by surface-mediated processes. In this study, we use ultrafast transient absorption spectroscopy to characterise the recombination dynamics of photo-generated charges in InAs/ZnSe nanocrystal quantum dots. We find that recombination is dominated by rapid, sub-nanosecond transfer of conduction band electrons to surface states. For the size of dots studied, we also find no evidence of significant multiple exciton generation for photon energies up to 3.2 times the band gap, in agreement with our theoretical modelling. This journal is {\textcopyright} 2012 the Owner Societies.",

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T1 - Ultrafast exciton dynamics in InAs/ZnSe nanocrystal quantum dots

AU - Cadirci, Musa

AU - Stubbs, Stuart K.

AU - Hardman, Samantha J O

AU - Masala, Ombretta

AU - Allan, Guy

AU - Delerue, Christophe

AU - Pickett, Nigel

AU - Binks, David J.

PY - 2012/11/21

Y1 - 2012/11/21

N2 - Colloidal nanocrystal quantum dots with a band gap in the near infra-red have potential application as the emitters for telecommunications or in vivo imaging, or as the photo-absorbing species in next generation solar cells or photodetectors. However, electro- and photoluminescence yields and the efficiency with which photo-generated charges can be extracted from quantum dots depend on the total rate of recombination, which can be dominated by surface-mediated processes. In this study, we use ultrafast transient absorption spectroscopy to characterise the recombination dynamics of photo-generated charges in InAs/ZnSe nanocrystal quantum dots. We find that recombination is dominated by rapid, sub-nanosecond transfer of conduction band electrons to surface states. For the size of dots studied, we also find no evidence of significant multiple exciton generation for photon energies up to 3.2 times the band gap, in agreement with our theoretical modelling. This journal is © 2012 the Owner Societies.

AB - Colloidal nanocrystal quantum dots with a band gap in the near infra-red have potential application as the emitters for telecommunications or in vivo imaging, or as the photo-absorbing species in next generation solar cells or photodetectors. However, electro- and photoluminescence yields and the efficiency with which photo-generated charges can be extracted from quantum dots depend on the total rate of recombination, which can be dominated by surface-mediated processes. In this study, we use ultrafast transient absorption spectroscopy to characterise the recombination dynamics of photo-generated charges in InAs/ZnSe nanocrystal quantum dots. We find that recombination is dominated by rapid, sub-nanosecond transfer of conduction band electrons to surface states. For the size of dots studied, we also find no evidence of significant multiple exciton generation for photon energies up to 3.2 times the band gap, in agreement with our theoretical modelling. This journal is © 2012 the Owner Societies.

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DO - 10.1039/c2cp42125a

M3 - Article

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EP - 15172

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

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ER -

Ultrafast exciton dynamics in InAs/ZnSe nanocrystal quantum dots

Abstract

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