Colloidal semiconductor CdSe-based
quantum dots (QDs) show undesirable
photoluminescence (PL) intermittency with frequent and long-lasting
dark states due to positively charged states, significantly limiting
QD optoelectronic and photonics applications. Here, we show that p-phenylenediamine (PPD) can completely suppress the long-lasting
dark states in the PL intensity trajectories for single CdSe-based
QDs in the full-color emission range from 459 to 800 nm, while hardly
influencing any other PL properties of the QDs, such as the PL intensity,
lifetime, and emission spectra. The suppression mechanism is investigated
by comparing PPD to another amine compound, N,N-dimethylaniline. With a reasonable highest occupied molecular
orbital energy, PPD facilitates electron transfer from PPD to the
positively charged QDs, thus, neutralizing the extra hot holes via
an Auger-assisted process. Therefore, the positively charged states
of QDs and the PL intermittency could be eliminated. Moreover, we
demonstrate that PPD can effectively suppress the photobleaching of
CdSe-based QDs, and the average survival time of single QDs can be
extended from a few minutes to more than 1 h. Finally, we demonstrate
the application of PPD-stabilized QDs to single-particle tracking
and HeLa cell imaging under relevant biological conditions and show
their promising potential in various biomedical applications.