Power‐Law Blinking in the Fluorescence of Single Organic Molecules

Abstract

The blinking behavior of perylene diïmide molecules is investigated at the single-molecule level. We observe long-time scale blinking of individual multi-chromophoric complexes embedded in a poly(methylmethacrylate) matrix, as well as for the monomeric dye absorbed on a glass substrate at ambient conditions. In both these different systems, the blinking of single molecules is found to obey analogous power-law statistics for both the on and off periods. The observed range for single-molecular power-law blinking extends over the full experimental time window, covering four orders of magnitude in time and six orders of magnitude in probability density. From molecule to molecule, we observe a large spread in off-time power-law exponents. The distributions of off-exponents in both systems are markedly different whereas both on-exponent distributions appear similar. Our results are consistent with models that ascribe the power-law behavior to charge separation and (environment-dependent) recombination by electron tunneling to a dynamic distribution of charge acceptors. As a consequence of power-law statistics, single molecule properties like the total number of emitted photons display non-ergodicity.

Defocused Wide‐field Imaging Unravels Structural and Temporal Heterogeneity in Complex Systems

“…[44] These long off-times have been linked to spurious electron transfer to or from the surrounding matrix, but their exact mechanism is still under debate. [45][46][47][48] Approximately 25% of the intensity traces displayed two distinct emission levels, indicating the presence of two chromophores. In the simplest case this led to the behavior shown in Figure 6, where the emission pattern of the first step (i) corresponds to the linear combination (sum) of the emission of both dyes, while the second step (ii) reflects only the emission of the last surviving dye.…”

The Rylene Colorant Family—Tailored Nanoemitters for Photonics Research and Applications

“…Since they outperform other dye molecules at the single-molecule level in terms of "survival time", they are the preferred molecules for many experimentalists. [58,[66][67][68][69] Amongst the rylene family, phenoxy-substituted PDI 3 ( Figure 2) is probably one of the most robust molecules, with survival times from minutes to tens of minutes under normal single-molecule excitation conditions (1 kW cm À2 ). [48,52] A characteristic time trace (detected number of counts per predefined time interval as a function of time) of a single PDI Figure 3.…”

Two-state theory of binned photon statistics for a large class of waiting time distributions and its application to quantum dot blinking

“…In many single fluorophore systems (such as colloidal QDs studied here 4 and dye molecules 27 ), the dark state yields no measur- …”