Correlating Delayed Emission, Blinking Mechanism, and the Quantum-Confined Stark Effect in Single Quantum Dots
Jialu Li, Xue Han, Changgang Yang, Mi Zhang, Zhihao Chen, Chuang Wang, Zhuang Ying, Jinhui Wang, Ruiyun Chen, Chengbing Qin, Jianyong Hu, Zhichun Yang, Jie Ma, Guofeng Zhang, Liantuan Xiao, Suotang JiaAbstract
Delayed emission, a long-lived nonexponential photoluminescence tail, is widely observed in quantum dots (QDs), but its microscopic origin and relationship with blinking and the quantum-confined Stark effect (QCSE) remain unclear. Here, we combine single-QD spectroscopy, time-gated photon analysis, and Monte Carlo simulations across CsPbX3 perovskite, CdSe-based, and InP-based QDs to identify a potential mechanism. Delayed emission correlates with band-edge carrier-trapping blinking, but is weak in QDs dominated by trion-mediated Auger blinking, suggesting delayed emission is not universally tied to charge-separated states. Delayed photons originate from nanosecond-scale carrier trapping and detrapping at nonradiative recombination centers: transiently trapped carriers return to the band edge and recombine radiatively. Time-gated analysis distinguishes this process from QCSE-driven intensity-lifetime fluctuations on slower blinking time scales. Furthermore, we demonstrate that delayed photons compromise the single-photon purity at a fixed excitation repetition rate. These findings establish a general framework of delayed emission in QDs.