Unraveling the Exciton Quenching Mechanism of Quantum Dots on Antimony-Doped SnO2 Films by Transient Absorption and Single Dot Fluorescence Spectroscopy

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• 作者：Nianhui Song ; Haiming Zhu ; Zheng Liu ; Zhuangqun Huang ; David Wu ; Tianquan Lian
• 刊名：ACS Nano
• 出版年：2013
• 出版时间：February 26, 2013
• 年：2013
• 卷：7
• 期：2
• 页码：1599-1608
• 全文大小：496K
• 年卷期：v.7,no.2(February 26, 2013)
• ISSN：1936-086X

文摘

Integrating quantum dots (QDs) into modern optoelectronic devices requires an understanding of how a transparent conducting substrate affects the properties of QDs, especially their excited-state dynamics. Here, the exciton quenching dynamics of core/multishell (CdSe/CdS_3MLZnCdS_2MLZnS_2ML) quantum dots deposited on glass, tin oxide (SnO₂), and antimony (Sb)-doped tin oxide (ATO) films are studied by transient absorption and single QD fluorescence spectroscopic methods. By comparing ensemble-averaged fluorescence decay and transient absorption kinetics, we show that, for QDs on SnO₂, the exciton is quenched by electron transfer from the QD to SnO₂. At the QD鈥揂TO interface, much faster exciton quenching rates are observed and attributed to fast Auger recombination in charged QDs formed by Fermi level equilibration between the QD and n-doped ATO. Single QDs on SnO₂ and ATO show similar blinking dynamics with correlated fluctuations of emission intensities and lifetimes. Compared to QDs on SnO₂, QDs on ATO films show larger variation of average exciton quenching rates, which is attributed to a broad distribution of the number of charges and nature of charging sites on the QD surface.

Keywords:

blinking dynamics; quantum dots; interfacial charge transfer; charged QDs; single particle spectroscopy; transient absorption spectroscopy