Plasmon-Induced Hot Carriers from Interband and Intraband Transitions in Large Noble Metal Nanoparticles

Abstract

Hot electrons generated from the decay of localized surface plasmons in metallic nanostructures have the potential to transform photocatalysis, photodetection and other optoelectronic applications. However, the understanding of hot-carrier generation in realistic nanostructures, in particular the relative importance of interband and intraband transitions, remains incomplete. Here we report theoretical predictions of hot-carrier generation rates in spherical nanoparticles of the noble metals silver, gold and copper with diameters up to 30 nanometers obtained from a novel atomistic linear-scaling approach. As the nanoparticle size increases the relative importance of interband transitions from d-bands to sp-bands relative to surface-enabled sp-band to sp-band transitions increases. We find that the hot-hole generation rate is characterized by a peak at the onset of the d-bands, while the position of the corresponding peak in the hot-electron distribution can be controlled through the illumination frequency. In contrast, intraband transitions give rise to hot electrons, but relatively cold holes. Importantly, increasing the dielectric constant of the environment removes hot carriers generated from interband transitions, while increasing the number of hot carriers from intraband transitions. The insights resulting from our work enable the design of nanoparticles for specific hot-carrier applications through their material composition, size and dielectric environment.