Challenge to the charging model of semiconductor-nanocrystal fluorescence intermittency from off-state quantum yields and multiexciton blinking.
Challenge to the charging model of semiconductor-nanocrystal fluorescence intermittency from off-state quantum yields and multiexciton blinking.
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DOI：
10.1103/physrevlett.104.157403
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发表时间：
2010-04-16
影响因子：
8.6
通讯作者：
Bawendi MG
中科院分区：
文献类型：
--
作者：
Zhao J;Nair G;Fisher BR;Bawendi MG
半导体纳米晶体间歇地发光;即，它们在稳定的照明下“闪烁”。暗期已被广泛认为是由于光致发光（PL）淬火的俄歇状过程涉及一个单一的额外的电荷存在于发光二极管。我们的研究结果挑战了这一长期存在的假设。激子PL强度的时间轨迹的单个CdSe（CdZnS）核（壳）纳米晶体的仔细检查表明，暗态PL量子产率可以比双激子PL量子产率小10倍。此外，我们观察到光谱分辨的多激子发射，并发现它也闪烁的开/关比大于10：1。这些结果直接与充电模型的预测相矛盾。
Semiconductor nanocrystals emit light intermittently; i.e., they “blink,” under steady illumination. The dark periods have been widely assumed to be due to photoluminescence (PL) quenching by an Auger-like process involving a single additional charge present in the nanocrystal. Our results challenge this long-standing assumption. Close examination of exciton PL intensity time traces of single CdSe(CdZnS) core (shell) nanocrystals reveals that the dark state PL quantum yield can be 10 times less than the biexciton PL quantum yield. In addition, we observe spectrally resolved multiexciton emission and find that it also blinks with an on/off ratio greater than 10:1. These results directly contradict the predictions of the charging model.