Memory in single emitter fluorescence blinking reveals the dynamic character of nanoscale charge tunneling

Luminescence blinking of single emitters is one of the most profound and intriguing issues in nano-optics and related areas. Its mechanisms and in particular the often observed deviant power-law statistics are a subject of ongoing recent debate. We examine on-off blinking in a dedicated synthetic trichromophoric assembly of perylene molecules. This trimeric system allows us to unambiguously discern blinking from photobleaching events and furthermore displays sufficient blinking events for a single-molecule analysis, An intriguing memory effect is observed, evidenced in clear correlations between successive on-times. In contrast, successive off-times are only weakly correlated and cross-correlations between on- and off-times are absent. Our results reveal the importance of nanoscale environmental dynamics on top of charge tunneling in understanding single emitter luminescence blinking. Dynamics of the polymer matrix and charge carriers therein is crucial to explain the power-law distribution of on-times. This result is directly relevant for related systems like semiconductor quantum dots, fluorescent proteins, and conjugated polymers. © 2008 American Chemical Society.