Fluorescence Intermittency of Quantum Dot-Organic Dye Conjugates: Implications for Alternative Energy and Biological Imaging.

Quantum dot (QD)-organic dye couple chromophores are topical due to their applications in biology, catalysis, and energy. The maximization of energy transfer efficiency can be guided by the underlying Förster or Dexter mechanisms; however, the impact of fluorescence intermittency must also be considered. Here we demonstrate that the average ⟨ton⟩ and ⟨toff⟩ times of dye acceptors in coupled QD-dye chromophores are substantially affected by the donors' blinking behavior. With regard to biological imaging, this effect beneficially minimizes the photobleaching of the acceptor dye. The implications for alternative energy are less encouraging as the acceptors' capacity to store energy, using ⟨ton⟩/⟨toff⟩ as a metric, was reduced by as much as ∼95%. These detrimental effects can be mitigated by suppressing QD blinking via surface treatment. This study also demonstrates several instances of the nonconformity of QD blinking dynamics to a power law distribution, as a robust examination of the off times reveals log-normal behavior that is consistent with the Albery model.