Adding shells to core quantum dots (QDs) is known to affect the blinking behavior in complex ways. We recently reported that varying the inner and outer shell materials and thicknesses of core-multishell QDs significantly affects both the quantum yield and blinking, although they were usually not correlated with each other (Bajwa et al. ChemPhysChem (2016) 17, 731-740; Omogo et al. ACSNano (2016) 10, 4072-4082). Although the majority of papers describe QD blinking in terms of binary “on” and “off” behavior, some recent papers have identified the presence of at least one more state – the so-called “grey” state. This state has been proposed to result from trions, but only some QD blinking reports shows its presence while others do not, and it is not yet clear what factors affect it. We have performed a systematic study of the grey and on state populations and dynamics as a function of controlling the shell material and thickness in order to better understand the underlying principles behind the multiple states and to postulate a mechanistic model describing our results. We hope that developing such a model will help provide a framework in which blinking can be more easily and accurately controlled for spectroscopy and imaging applications, especially while maintaining as small a QD size as possible.

Mechanistic insights into multiple blinking states in small core-shell and core-multishell quantum dots

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.