Optimizing Plasmonic Silicon Photovoltaics with Ag and Au Nanoparticle Mixtures

The effects of size and surface coverage of gold nanoparticles (Au NPs) on the performance of modified silicon photovoltaic (Si PV) devices were investigated. An increase in external quantum efficiency (EQE) above 600 nm (relative to the unmodified Si PV) was observed for PV devices modified with Au NPs with an average diameter greater than 80 nm, and the maximum in enhanced photocurrent red-shifted as the Au NP size increased. A decrease in EQE was observed for wavelengths shorter than 600 nm, leading to minimum overall advantage in terms of electrical power generated by white light illumination relative to the unmodified standard. However, this negative effect was successfully minimized by adding silver (Ag) NPs to the surface of the modified PV device. A maximum ∼6% EQE enhancement was observed for PV devices modified with a mixture of metallic nanoparticles (Ag and Au) at the localized surface plasmon resonance (LSPR) wavelengths, and an overall increase in the white light power conversion efficiency of ∼5% was obtained.