The behaviour of plasmonic metal nanoparticles (MNPs) placed in contact with a thin dielectric film on a high refractive index substrate is examined through finite-difference time domain simulations. The optical properties of this configuration are studied in the context of light trapping for thin-film amorphous silicon (a-Si) solar cells. We explore several different MNP configurations including both silver (Ag) and aluminium (Al) nanocubes along with traditional Ag nanospheres for reference. We demonstrate a large increase in the fraction of light coupled into the substrate (Fsubs), and consequently in the absorbed power, by spacing nanocubes away from the substrate. Further study concluded that blue-shifting the plasmonic resonances significantly reduced parasitic absorption in the visible spectrum and increased forward scattering by the MNPs. Transitioning to Al MNPs facilitated a large blue-shift in the plasmonic resonances allowing broadband enhancement in light absorption. For wavelengths less than the band-gap of a-Si, combining the effects of Al nanocubes on a 20nm SiO2 spacer layer with a 25% surface coverage resulted in a 13.8% increase in solar power absorption over cells with optimally designed Ag nanocube and nanosphere arrays, and a 38.9% enhancement over a MNP free reference cell.
Journal of Applied Physics
Department of Electronics

Veenkamp, R.J. (R. J.), & Ye, W.N. (2014). Plasmonic metal nanocubes for broadband light absorption enhancement in thin-film a-Si solar cells. Journal of Applied Physics, 115(12). doi:10.1063/1.4869785