Ultrafast carrier dynamics in PbS quantum dots

[Display omitted] ► Ultrafast carrier dynamics in PbS Quantum Dots (QDs) was characterized. ► Multiple exciton generation (MEG) and hot carrier cooling dynamics was clarified. ► We found that MEG began in as fast as 200fs and completed around 3ps. ► MEG occurred for photon energy larger than 2.7 tim...

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Bibliographic Details
Published in:Chemical physics letters 2012-07, Vol.542, p.89-93
Main Authors: Shen, Qing, Katayama, Kenji, Sawada, Tsuguo, Hachiya, Sojiro, Toyoda, Taro
Format: Article
Language:English
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Summary:[Display omitted] ► Ultrafast carrier dynamics in PbS Quantum Dots (QDs) was characterized. ► Multiple exciton generation (MEG) and hot carrier cooling dynamics was clarified. ► We found that MEG began in as fast as 200fs and completed around 3ps. ► MEG occurred for photon energy larger than 2.7 times bandgap of the PbS QDs. ► Auger recombination dynamics of the generated multi-excitons were confirmed. Ultrafast carrier dynamics in PbS quantum dots (QDs) is characterized using a transient grating technique. In addition to an initial peak, a new peak appears at about 3ps when the excitation photon energy is greater than 2.7Eg (Eg: band gap between LUMO and HOMO in the QDs). The first peak is considered to be related to hot carriers and the second one is believed to result from multiple exciton generation (MEG). We found that MEG began in as fast as 200fs and complete around 3ps. We succeeded in observing the dynamics of MEG occurrence in PbS QDs.
ISSN:0009-2614
1873-4448
DOI:10.1016/j.cplett.2012.05.076