Understanding the Bias Introduced in Quantum Dot Blinking Using Change Point Analysis
Understanding the Bias Introduced in Quantum Dot Blinking Using Change Point Analysis
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DOI：
10.1021/acs.jpcc.6b09780
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发表时间：
2016-12-29
影响因子：
3.7
通讯作者：
Leone, Stephen R.
中科院分区：
文献类型：
--
作者：
Bae, Youn Jue;Gibson, Natalie A.;Leone, Stephen R.
使用传统的箱和阈值方法以及统计上更严格的方法，变化点分析（CPA）研究了具有不同壳尺寸的单个CdSe/CdS量子点（QD）的荧光间歇性。通态截断时间 (tau(c)) 是用于解释单个量子点中电荷俘获动态的临界值；然而，改变眨眼轨迹中的 bin 大小和阈值会显着修改 tau(c)。在这里，我们使用 CPA 方法来最小化分箱和阈值引入的偏差，并发现广泛使用的只有一个开和一个关状态的假设是有问题的。我们观察到 17 个 QD 中的 12 个表现出两个以上的强度水平，并发现各个水平的值与组合水平时获得的值不同，即，当人们假设只有一个开和一个关状态时，如传统的箱和阈值方法。例如，一个 QD 在两种不同强度水平下的 tau(c) 值分别为 0.5 (0.1) 和 2.0 (0.2) s，而当这些水平仅组合成一个状态时，tau(c) 值为 7 (1) s。发现 CPA 方法比传统的 bin 和阈值方法更适合研究 QD 中的多级发射。
The fluorescence intermittency of single CdSe/CdS quantum dots (QDs) with different shell sizes is studied using the conventional bin and threshold method and the statistically more rigorous method, change point analysis (CPA). The on-state truncation time (tau(c)) is a critical value used to interpret the dynamics of charge trapping in single QDs; however, changing the bin size and threshold in blink traces significantly modifies tau(c). Herein, we use the CPA method to minimize the bias that binning and thresholding introduces and find that a widely used assumption that there is only one on and one off state is questionable. We observe that 12 out of 17 QDs exhibit more than two intensity levels and find that the 2, values of individual levels differ from the values obtained when the levels are combined, i.e., when one assumes there is only one on and one off state as in the conventional bin and threshold method. For instance, one QD has tau(c) values of 0.5 (0.1) and 2.0 (0.2) s from two different intensity levels, whereas when the levels are combined into only one on state, tau(c) is found to be 7 (1) s. The CPA method is found to be more suitable for studying multilevel emission in QDs than the conventional bin and threshold method.