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Issue 16, 2010
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Charge carrier dynamics in thiol capped CdTe quantum dots

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Abstract

We report the ultrafast charge carrier relaxation dynamics of mercaptopropionic acid capped CdTe quantum dot (QD) using femtosecond transient absorption spectroscopy by exciting the particles with 400 nm laser light and monitoring the transients in the visible to near IR region. Cooling dynamics and population dynamics in different quantized states of the charge carriers were monitored by following the growth kinetics of the bleach at different excitonic positions. The cooling time second and first excitonic states were found to be 150 fs and 500 fs, respectively, which increases non-linearly with its size. Defect states of QD surface play an important role in the cooling dynamics of the charge carriers. Quenching studies have been carried out to find out cooling and trapping dynamics of the individual charge carriers. Electron and hole cooling time were measured to be 700 fs and 150 fs for the first excitonic state using quenchers. Trapping dynamics of electron and hole have been determined by monitoring transient signal at 1000 nm and by using hole and electron quencher, respectively. Electron and hole trapping times have been found to be 700 fs and 1 ps, respectively, in CdTe QD.

Graphical abstract: Charge carrier dynamics in thiol capped CdTe quantum dots

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Publication details

The article was received on 08 Oct 2009, accepted on 03 Feb 2010 and first published on 04 Mar 2010


Article type: Paper
DOI: 10.1039/B921130F
Citation: Phys. Chem. Chem. Phys., 2010,12, 4210-4216
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    Charge carrier dynamics in thiol capped CdTe quantum dots

    S. Kaniyankandy, S. Rawalekar, S. Verma, D. K. Palit and H. N. Ghosh, Phys. Chem. Chem. Phys., 2010, 12, 4210
    DOI: 10.1039/B921130F

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