Investigation of time-resolved fluorescence lifetime of perylene dye molecules embedded in silicon nanopillars

The radiative decay rate of a perylene dye molecule attached to silicon nanopillar is investigated using a conventional time-correlated single photon counting technique. It is hard to produce a sustainable host with exactly the same dimensions all the time during fabrication to accommodate dye molecules for enhancement of spontaneous emission rate. The laser-induced electrochemical anodization method allows us to have a control over size and shape of the silicon nanostructures. The effect of the silicon nanopillar on the radiative decay rate of the dye molecules is described by the Klimov's prolate nanospheroid model. It is observed that the decay rate is significantly enhanced or inhibited due to plasmon resonance, depending on whether the dipole is embedded closely right at the tip or at equator of the prolate nanospheroid. Both inhibition and enhancement disappear when the distance between the dipole and prolate nanospheroid becomes large. Thus, the decay rate of the dye molecule approaches its natural value in the free space.