Challenge to the charging model of semiconductor-nanocrystal fluorescence intermittency from off-state quantum yields and multiexciton blinking

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...

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Bibliographic Details
Published inPhysical review letters Vol. 104; no. 15; p. 157403
Main Authors Zhao, Jing, Nair, Gautham, Fisher, Brent R, Bawendi, Moungi G
Format Journal Article
LanguageEnglish
Published United States 16.04.2010
Subjects
Nanoparticles - chemistry
Semiconductors
Spectrometry, Fluorescence
Time Factors
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Summary: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.
ISSN:1079-7114
DOI:10.1103/physrevlett.104.157403