Correlated Single Quantum Dot Blinking and Interfacial Electron Transfer Dynamics.
Correlated Single Quantum Dot Blinking and Interfacial Electron Transfer Dynamics.
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DOI：
10.1039/c0sc00334d
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发表时间：
2010-08-31
期刊：
影响因子：
8.4
通讯作者：
Lian T
中科院分区：
文献类型：
--
作者：
Jin S;Hsiang JC;Zhu H;Song N;Dickson RM;Lian T
采用单粒子谱学方法研究了核/多壳（CdSe/CdS 3 MLZnCdS 2 MLZnS 2 ML）量子点（QD）与吸附的黄绿素（F27）分子之间的电子转移动力学，探讨了单QD界面电子转移与闪烁动力学之间的关系.电子从量子点转移到F27和随后的复合直接观察到的系综平均瞬态吸收光谱。单个QD-F27复合物显示荧光强度和寿命的相关波动，类似于在自由QD中观察到的那些。随着ET率的增加（由F27-QD比控制），开态的寿命减少，关态的相对贡献增加。结果表明，量子点处于开态时，激发态寿命反映了量子点的激发态速率，而在关态时，量子点激子通过俄歇弛豫衰减，激发态不是竞争性猝灭途径.因此，单个量子点的闪烁动力学调节它们的界面ET活性。此外，界面ET提供了一个额外的途径产生关闭状态，导致相关的单量子点界面ET和闪烁的量子点受体复合物的动力学。由于闪烁是单个量子点的普遍现象，因此似乎相关的界面ET和闪烁以及由此产生的间歇性ET活性是单个量子点的普遍现象。
The electron transfer (ET) dynamics from core/multi-shell (CdSe/CdS3MLZnCdS2MLZnS2ML) quantum dots (QDs) to adsorbed Fluorescein (F27) molecules have been studied by single particle spectroscopy to probe the relationship between single QD interfacial electron transfer and blinking dynamics. Electron transfer from the QD to F27 and the subsequent recombination were directly observed by ensemble-averaged transient absorption spectroscopy. Single QD-F27 complexes show correlated fluctuation of fluorescence intensity and lifetime, similar to those observed in free QDs. With increasing ET rate (controlled by F27-to-QD ratio), the lifetime of on states decreases and relative contribution of off states increases. It was shown that ET is active for QDs in on states, the excited state lifetime of which reflects the ET rate, whereas in the off state QD excitons decay by Auger relaxation and ET is not a competitive quenching pathway. Thus, the blinking dynamics of single QDs modulate their interfacial ET activity. Furthermore, interfacial ET provides an additional pathway for generating off states, leading to correlated single QD interfacial ET and blinking dynamics in QD-acceptor complexes. Because blinking is a general phenomenon of single QDs, it appears that the correlated interfacial ET and blinking and the resulting intermittent ET activity are general phenomena for single QDs.