Plasmon-Enhanced Emission Rate of Silicon Nanocrystals in Gold Nanorod Composites

We develop colloidal nanocomposites consisting of coupled light-emitting Si nanocrystals (NCs) and Au nanorods and systematically investigate their structural and photoluminescence (PL) properties, which demonstrate significant enhancement of spontaneous emission rate with suppressed nonradiative quenching. In addition, through a comparison of the polarization dependence of PL and scattering intensities of single nanocomposites, we successfully demonstrate that the emission from Si NCs coupled to Au nanorods is highly polarized along the major axis of nanorods. The experimental results in combination with rigorous simulations of dipolar emission in the vicinity of Au nanorods enable us to demonstrate a 3 times enhancement of the quantum efficiency at the peak of the NC emission. The Si-based active plasmonic-coupled nanocomposites developed in this work provide novel opportunities for biocompatible platforms that leverage nanoscale fluorescent probes for biosensing and bioimaging device applications.