Voltage controlled photoluminescence blinking in CdSe nano-particles

Voltage controlled photoluminescence (PL) blinking behavior in CdSe nano-particles (NPs) is studied. The NPs are sandwiched between a p-type silicon substrate and a thin Au electrode, which serve respectively as source and drain electrodes. The blinking PL from the NPs can be controlled by the bias voltage across the two electrodes. However, luminescence diminishes when photo excitation power is weak or bias is lower than a threshold voltage. The observed PL blinking is explained by a circuit model, which involves charge tunneling, Fowler-Nordheim (F-N) emission, and charging effect. The blinking intensity is controlled by the number of F-N emitted electrons whereas the pulse interval is associated with the time required for hole accumulation in the NPs. The intensity of luminescence blinking for NP clusters is found to be much higher compared to that of blinking from isolated NPs. This is explained by a collective recombination of F-N emitted electrons and accumulated holes in the NP clusters. This study provides a simple way of controlling PL blinking.