Anharmonicity of Plasmons in Metallic Nanostructures Useful for Metallization of Solar Cells

Metallic nanoparticles are frequently applied to enhance the efficiency of photovoltaic cells via the plasmonic effect, and they play this role due to the unusual ability of plasmons to transmit energy. The absorption and emission of plasmons, dual in the sense of quantum transitions, in metallic nanoparticles are especially high at the nanoscale of metal confinement, so these particles are almost perfect transmitters of incident photon energy. We show that these unusual properties of plasmons at the nanoscale are linked to the extreme deviation of plasmon oscillations from the conventional harmonic oscillations. In particular, the large damping of plasmons does not terminate their oscillations, even if, for a harmonic oscillator, they result in an overdamped regime.