The investigation of biexciton dynamics in single colloidal quantum dots (QDs) is critical to biexciton-based applications. Generally, a biexciton exhibits an extremely low photoluminescence (PL) quantum yield as well as very fast PL decay due to strong nonradiative Auger recombination, making it difficult to investigate the biexciton dynamics. Here, we develop a quantitative method based on intensity- and time-resolved photon statistics to investigate the biexciton dynamics in single colloidal QDs. This robust method can be used under high-excitation conditions to determine the absolute radiative and Auger recombination rates of both neutral and charged biexciton states in a single QD level, and the corresponding ratios between the two states agree with the theoretical predictions of the asymmetric band structures of CdSe-based QDs. Furthermore, the surface traps are found to provide additional nonradiative recombination pathways for the biexcitons, and their contributions are quantified by the method.

中文翻译：

---

单个胶体 CdSe 量子点中的双激子动力学

单胶体量子点 (QD) 中双激子动力学的研究对于基于双激子的应用至关重要。通常，由于强的非辐射俄歇复合，双激子表现出极低的光致发光 (PL) 量子产率以及非常快的 PL 衰减，这使得研究双激子动力学变得困难。在这里，我们开发了一种基于强度和时间分辨光子统计的定量方法来研究单个胶体 QD 中的双激子动力学。这种稳健的方法可在高激发条件下用于确定单个 QD 能级中中性和带电双激子态的绝对辐射和俄歇复合率，并且两种态之间的对应比率与非对称带的理论预测一致基于 CdSe 的量子点的结构。此外，