Multiple exciton generation in nano-crystals revisited: Consistent calculation of the yield based on pump-probe spectroscopy.

Summary, in English

Multiple exciton generation (MEG) is a process in which more than one exciton is generated upon the absorption of a high energy photon, typically higher than two times the band gap, in semiconductor nanocrystals. It can be observed experimentally using time resolved spectroscopy such as the transient absorption measurements. Quantification of the MEG yield is usually done by assuming that the bi-exciton signal is twice the signal from a single exciton. Herein we show that this assumption is not always justified and may lead to significant errors in the estimated MEG yields. We develop a methodology to determine proper scaling factors to the signals from the transient absorption experiments. Using the methodology we find modest MEG yields in lead chalcogenide nanocrystals including the nanorods.

• Author: Khadga Jung Karki; Fei Ma; Kaibo Zheng; Karel Zidek; Abdelrazek Mousa; Mohamed Qenawy; Maria Messing; Reine Wallenberg; Arkady Yartsev; Tönu Pullerits
• Department/s: Chemical Physics; Solid State Physics; Synchrotron Radiation Research; Centre for Analysis and Synthesis; NanoLund: Centre for Nanoscience
• Publishing year: 2013
• Language: English
• Publication/Series: Scientific Reports
• Volume: 3
• Links: http://dx.doi.org/10.1038/srep02287
• Document type: Journal article
• Publisher: Nature Publishing Group
• Topic: Atom and Molecular Physics and Optics
• Status: Published
• ISBN/ISSN/Other: ISSN: 2045-2322