Simple model for the power-law blinking of single semiconductor nanocrystals

We assign the blinking of nanocrystals to electron tunneling towards a uniform spatial distribution of traps. This naturally explains the power-law distribution of off times, and the power-law correlation function we measured on uncapped CdS dots. Capped dots, on the other hand, present extended on times leading to a radically different correlation function. This is readily described in our model by involving two different, dark and bright, charged states. Coulomb blockade prevents further ionization of the charged dot, thus giving rise to long, power-law distributed off and on times.