Light-management in ultra-thin polythiophene films using plasmonic monopole nanoantennas

Abstract

Deposition of vertical, cone-shaped plasmonic nanorod arrays onto sub-50 nm polythiophene films on Ag substrates is shown to result in significant absorption enhancement (>12 at the polythiophene band edge) and spectral broadening (more than 250 nm increase) relative to polythiophene/Ag films without plasmonic nanorod arrays. Full-field electromagnetic simulations are used to identify the modes of the plasmonic nanorod array/polythiophene/Ag film system. Both gap modes and longitudinal monopole antenna modes give rise to highly localized electric fields in the polythiophene film and are the primary contributors to polythiophene absorption enhancement. This approach is suitable for large area optoelectronic applications where light management in ultrathin active layers is desired.