Challenge to the Charging Model of Semiconductor-Nanocrystal Fluorescence Intermittency from Off-State Quantum Yields and Multiexciton Blinking

Author(s)
Zhao, Jing; Nair, Gautham Padmanabhan; Fisher, Brent R.; Bawendi, Moungi G.
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Abstract
Semiconductor nanocrystals emit light intermittently; i.e., they “blink,” under steady illumination. The dark periods have been widely assumed to be due to photoluminescence (PL) quenching by an Auger-like process involving a single additional charge present in the nanocrystal. Our results challenge this long-standing assumption. Close examination of exciton PL intensity time traces of single CdSe(CdZnS) core(shell) nanocrystals reveals that the dark state PL quantum yield can be 10 times less than the biexciton PL quantum yield. In addition, we observe spectrally resolved multiexciton emission and find that it also blinks with an on/off ratio greater than 10∶1. These results directly contradict the predictions of the charging model.
Date issued
2010-04
URI
http://hdl.handle.net/1721.1/58782
Department
Massachusetts Institute of Technology. Department of Chemistry
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Zhao, Jing et al. “Challenge to the Charging Model of Semiconductor-Nanocrystal Fluorescence Intermittency from Off-State Quantum Yields and Multiexciton Blinking.” Physical Review Letters 104.15 (2010): 157403. © 2010 The American Physical Society
Version: Final published version
ISSN
0031-9007
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