Effect of Silver Plasmonic Nanoparticles on the Efficiency of Silver Sulfide Photovoltaic Device

Silver plasmonic nanoparticles (AgNPs) can improve the efficiency of photovoltaic devices (PV) via the near-field enhancement and far-field light scattering. Both the enhancement and reduction of photoconversion efficiency (PCE) upon incorporating plasmonic particles have been previously observed. The present work addresses this issue by developing novel hybrid nanoparticles comprised of Ag plasmonic core and Ag2S semiconductor cap and incorporating them into PV devices. The size of the core and cap was systematically varied and their effect on PCE was studied. It was determined that the direct electrical contact between the core and the semiconductor cap provided an additional mechanism for the recombination of the photogenerated electron/hole pairs thus reducing the device performance. To overcome this problem, AgNPs were insulated with a thin silica layer leading to similar to 20% increase of the PCE as compared to the same device configuration but without the plasmonic nanoparticles. In-depth analysis of the energy band structure related to all junctions is presented.