Strong luminescence quantum-efficiency enhancement near prolate metal nanoparticles: Dipolar versus higher-order modes

We present a theoretical study on the radiative and nonradiative decay rates of an optical emitter in close proximity to a prolate-shaped metal nanoparticle. We use the model developed by Gersten and Nitzan [J. Chem. Phys. 75, 1139 (1981)] that we correct for radiative reaction and dynamic depolarization. Based on this analytical model, we provide physical insight on the optimization of anisotropic metal nanoparticles for plasmon-enhanced luminescence. We demonstrate that for properly engineered emitter-nanoparticle geometries, quantum-efficiency enhancements from an initial value of 1% (in the absence of the nanoparticle) to 70% are feasible. In addition, we show that for large (>100 nm) nanoparticles, the influence of Ohmic losses on plasmon-enhanced luminescence is substantially reduced, which implies that, if prolate shaped, even lossy metals such as Al and Cu are suitable materials for optical nanoantennas.