Optical radiation efficiencies of metal nanoparticles for optoelectronic applications

The optical radiation efficiencies, defined by the ratio of the scattering cross-section to the extinction cross-section, of spherical nanoparticles of 11 kinds of metal, Ag, Al, Au, Co, Cr, Cu, Ni, Pd, Pt, Sri and Ti, in the air were calculated based on the classical electromagnetic theory. This optical radiation efficiency represents the energy fraction of the incident light reradiated from the particle, not wasted as heat, and the obtained data is an effective guide for the selection of metal elements for nanoparticle-enhanced optoelectronic devices. Ag, Al, Au and Cu were found to have much higher optical radiation efficiencies than the other metals for most range of wavelengths. Strikingly, Ag and A1 nanoparticles with diameters around 150 nm were found to exhibit over -90% optical radiation efficiencies at most optical frequencies. (c) 2007 Elsevier B.V. All rights reserved.