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

Journal Article · Fri Apr 16 04:00:00 EDT 2010 · Phys. Rev. Lett.

DOI:https://doi.org/10.1103/PhysRevLett.104.157403· OSTI ID:1064760

Zhao, Jing ^[1]; Nair, Gautham ^[1]; Fisher, Brent R. ^[1]; Bawendi, Moungi G. ^[1]

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1. MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States)

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.

• Research Organization: Energy Frontier Research Centers (EFRC); Center for Excitonics (CE)
• Sponsoring Organization: USDOE SC Office of Basic Energy Sciences (SC-22)
• DOE Contract Number: SC0001088
• OSTI ID: 1064760
• Journal Information: Phys. Rev. Lett., Journal Name: Phys. Rev. Lett. Journal Issue: 15 Vol. 104; ISSN 0031-9007
• Country of Publication: United States
• Language: English

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