'Giant' multishell CdSe nanocrystal quantum dots with suppressed blinking: Novel fluorescent probes for real-time detection of single-molecule events.
'Giant' multishell CdSe nanocrystal quantum dots with suppressed blinking: Novel fluorescent probes for real-time detection of single-molecule events.
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DOI：
10.1117/12.809678
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发表时间：
2009-03-03
期刊：
影响因子：
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通讯作者：
Casson AR
中科院分区：
文献类型：
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作者：
Hollingsworth JA;Vela J;Chen Y;Htoon H;Klimov VI;Casson AR
我们首次报道了通过生长非常厚的无缺陷无机壳，可以使关键的量子点（NQD）光学性质-量子产率、光漂白和闪烁-独立于NQD表面化学和环境（Chen等人，J. Am. 2008）。在这里，我们展示了这些效应的精确壳厚度依赖性。我们表明，“巨壳”NQD可以在很大程度上是非闪烁的观察时间长达54分钟，并在时间分数是独立的实验时间分辨率从1-200毫秒。这些影响主要表现在（CdSe）CdS（核心）壳NQD，但我们也表明，合金壳包括CdxZn 1-xS和终止与非细胞毒性ZnS层表现出类似的性能。抑制闪烁和显着增强的稳定性的机制是由于NQD核心激子波函数从NQD表面的有效隔离，以及准II型电子结构。不寻常的电子结构提供了电子和空穴分别进入壳和核的有效空间分离，从而降低了非辐射俄歇复合的效率。
We reported for the first time that key nanocrystal quantum dot (NQD) optical properties—quantum yield, photobleaching and blinking—can be rendered independent of NQD surface chemistry and environment by growth of a very thick, defect-free inorganic shell (Chen, et al. J. Am. Chem. Soc. 2008). Here, we show the precise shell-thickness dependence of these effects. We demonstrate that ‘giant-shell’ NQDs can be largely non-blinking for observation times as long as 54 minutes and that on-time fractions are independent of experimental time-resolution from 1–200 ms. These effects are primarily demonstrated on (CdSe)CdS (core)shell NQDs, but we also show that alloyed shells comprising CdxZn1-xS and terminated with a non-cytotoxic ZnS layer exhibit similar properties. The mechanism for suppressed blinking and dramatically enhanced stability is attributed to both effective isolation of the NQD core excitonic wavefunction from the NQD surface, as well as a quasi-Type II electronic structure. The unusual electronic structure provides for effective spatial separation of the electron and hole into the shell and core, respectively, and, thereby, for reduced efficiencies in non-radiative Auger recombination.