Biexciton quantum yield of single semiconductor nanocrystals from photon statistics.
Biexciton quantum yield of single semiconductor nanocrystals from photon statistics.
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DOI：
10.1021/nl104054t
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发表时间：
2011-03-09
期刊：
影响因子：
10.8
通讯作者：
Bawendi MG
中科院分区：
文献类型：
--
作者：
Nair G;Zhao J;Bawendi MG
双激子特性在很大程度上影响了量子光子源和激光器中光发射体的可用性，但由于发光的间歇性和高激发通量下的漂白，在室温下很难测量单个荧光团的双激子性质。在g(2)光子相关测量中，我们观察到弱激发下单个胶体半导体纳米晶(NCS)的双激子(BX)-激子(X)基态光致发光级联，并证明了级联特征的归一化幅度等于BX-X荧光量子产额之比。这对光子反聚束的可达到深度施加了限制，并为研究单发射极双激子物理提供了可靠的手段。在纳米样品中，我们发现BX量子产额是相当不均匀的，这与俄歇非辐射复合机制所期望的缺陷灵敏度一致。该方法可推广到X、BX光谱和偏振关联的研究。
Biexciton properties strongly affect the usability of a light emitter in quantum photon sources and lasers but are difficult to measure for single fluorophores at room temperature due to luminescence intermittency and bleaching at the high excitation fluences usually required. Here, we observe the biexciton (BX) to exciton (X) to ground photoluminescence cascade of single colloidal semiconductor nanocrystals (NCs) under weak excitation in a g(2) photon correlation measurement and show that the normalized amplitude of the cascade feature is equal to the ratio of the BX to X fluorescence quantum yields. This imposes a limit on the attainable depth of photon antibunching and provides a robust means to study single emitter biexciton physics. In NC samples, we show that the BX quantum yield is considerably inhomogeneous, consistent with the defect sensitivity expected of the Auger nonradiative recombination mechanism. The method can be extended to study X,BX spectral and polarization correlations.
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