N-type semiconductor indium tin oxide (ITO) nanoparticles are used to effectively suppress the fluorescence blinking of single near-infrared-emitting CdSeTe/ZnS core/shell quantum dots (QDs), where the ITO could block the electron transfer from excited QDs to trap states and facilitate more rapid regeneration of neutral QDs by back electron transfer. The average blinking rate of QDs is significantly reduced by more than an order of magnitude and the largest proportion of on-state is 98%, while the lifetime is not considerably reduced. Furthermore, an external electron transfer model is proposed to analyze the possible effect of radiative, nonradiative, and electron transfer pathways on fluorescence blinking. Theoretical analysis based on the model combined with measured results gives a quantitative insight into the blinking mechanism.

The two frequently observed phenomena, photoluminescence (PL) blinking and quantum-confined Stark effect (QCSE)-induced spectral diffusion, are not conducive to the applications of colloidal quantum dots (QDs). It remains elusive how these two phenomena are linked to each other. Unraveling the potential link between blinking and QCSE could facilitate the adoption of appropriate strategies that can simultaneously suppress both PL blinking and spectral diffusion. In this work, we investigated the blinking mechanism and QCSE of single CdSe/CdS/ZnS QDs in the presence of positive and negative surface charges using single-dot PL spectroscopy. We found that the negative surface charges can simultaneously suppress PL blinking and spectral diffusion of single QDs. On the other hand, the positive surface charges could change the blinking mechanisms of QDs from Auger-blinking to band-edge carrier (BC)-blinking. Two types of QCSE were observed, and a significant QCSE-induced spectral broadening of 5.25 nm was measured, which could be attributed to the hopping of surface charges between different surface-trap sites. Based on these findings, several theoretical models are proposed to explain various phenomena observed.