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CdTe／CdS核壳结构量子点超快载流子动力学
Ultrafast carrier dynamics in CdTe/CdS Core/Shell quantum dots
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摘要: 在水相合成CdTe以及CdTe／CdS核壳结构量子点基础上，利用基于抽运一探测技术的瞬态差分透射技术研究了CdTe量子点以及不同CdS壳层厚度的CdTe／CdS量子点的最低激子能态的超快激发与弛豫动力学．研究表明：相比于CdTe，CdTe／CdS量子点的电子空穴由于空间分离，其所需的激发时间要长于电子空穴空间重叠态所需要的激发时间．随着壳层厚度的增加，量子点表面的钝化有效地减少了表面态相关弛豫机理，并延长相对应的弛豫时间．Abstract: On the basic of the synthesis of CdTe/CdS core/shell quantum dots (QDs) in aqueous phase, we study uitrafast carrier dynamic behaviors of CdTe/CdS QDs with different shell thicknesses, by using femtosecond time-resolved transmission spectroscopy. The results show that both the buildup time of the lowest exciton state and its following relaxation time become longer as CdS shell thickness increases. The results also indicate that the buildup rate of a space-separate exciton is slower than that of a space-overlapped exciton, and that carrier relaxation changes from surface-defect related mechanism into surface-passivated charge separation regime, which is consistent with steady-state absorption and photoluminescence experiments.
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