Two types of luminescence blinking revealed by spectroelectrochemistry of single quantum dots.
Two types of luminescence blinking revealed by spectroelectrochemistry of single quantum dots.
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DOI：
10.1038/nature10569
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发表时间：
2011-11-09
期刊：
影响因子：
64.8
通讯作者：
Htoon, Han
中科院分区：
文献类型：
--
作者：
Galland, Christophe;Ghosh, Yagnaseni;Steinbrueck, Andrea;Sykora, Milan;Hollingsworth, Jennifer A.;Klimov, Victor I.;Htoon, Han
光致发光（PL）的闪烁（闪烁），或高（ON）和低（OFF）发射率状态之间的随机切换，是染料，聚合物，生物分子和人造纳米结构（如量子点，碳纳米管和纳米线）所表现出的分子发射体的普遍性质。在过去的15年里，胶体纳米晶体一直被用作研究这一现象的模型系统。截止期的发生在荧光发射已普遍归因于额外的电荷的存在下，这导致PL猝灭的非辐射俄歇复合。然而，“收费”模式最近在几份报告中受到质疑。在这里，为了澄清充电在PL不稳定性的作用，我们进行时间分辨的PL研究的个别纳米晶体，同时控制其充电的程度电化学。我们发现，两种不同的机制可以导致PL不透明。我们确定传统的闪烁（A型），由于充电/放电时较低的PL强度与较短的PL寿命的核心。重要的是，我们观察到一个不同的闪烁（B型），当PL强度的大的变化并不伴随着PL动力学的显着变化。我们将这种闪烁行为归因于电子接受表面位点的电荷波动。当未被占据时，这些位置在热电子松弛到发射核心状态之前拦截热电子。这两种眨眼机制都可以通过电化学控制，并且在适当的电位下可以完全抑制眨眼。
Photoluminescence (PL) intermittency (blinking), or random switching between states of high- (ON) and low (OFF) emissivities, is a universal property of molecular emitters exhibited by dyes, polymers, biological molecules and artificial nanostructures such as nanocrystal quantum dots, carbon nanotubes, and nanowires. For the past fifteen years, colloidal nanocrystals have been used as a model system for studies of this phenomenon. The occurrence of OFF periods in nanocrystal emission has been commonly attributed to the presence of an additional charge, which leads to PL quenching by nonradiative Auger recombination. However, the “charging” model was recently challenged in several reports. Here, to clarify the role of charging in PL intermittency, we perform time-resolved PL studies of individual nanocrystals while controlling electrochemically the degree of their charging. We find that two distinct mechanisms can lead to PL intermittency. We identify conventional blinking (A-type) due to charging/discharging of the nanocrystal core when lower PL intensities correlate with shorter PL lifetimes. Importantly, we observe a different blinking (B-type), when large changes in the PL intensity are not accompanied by significant changes in PL dynamics. We attribute this blinking behavior to charge fluctuations in the electron-accepting surface sites. When unoccupied, these sites intercept hot electrons before they relax into emitting core states. Both blinking mechanisms can be controlled electrochemically and under appropriate potential blinking can be completely suppressed.
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影响因子：
2.8
作者：
Vela, Javier;Htoon, Han;Chen, Yongfen;Park, Young-Shin;Ghosh, Yagnaseni;Goodwin, Peter M.;Werner, James H.;Wells, Nathan P.;Casson, Joanna L.;Hollingsworth, Jennifer A.
通讯作者：
Hollingsworth, Jennifer A.
影响因子：
10.8
作者：
Garcia-Santamaria, Florencio;Brovelli, Sergio;Klimov, Victor I.
通讯作者：
Klimov, Victor I.
影响因子：
3.3
作者：
Houtepen, AJ;Vanmaekelbergh, D
通讯作者：
Vanmaekelbergh, D
影响因子：
3.7
作者：
Klimov, V. I.;McGuire, J. A.;Rupasov, V. I.
通讯作者：
Rupasov, V. I.
影响因子：
56.9
作者：
Klimov, VI;Mikhailovsky, AA;Bawendi, MG
通讯作者：
Bawendi, MG