Light absorption and efficiency enhancements for organic photovoltaic devices with Au@PSS core-shell tetrahedra

Light harvesting of photoactive layer to incident solar illumination is an important factor that constrains device performances of organic photovoltaic devices (OPVs). Different types of metal nanoparticles (NPs) including nanospheres, nanorods, nanocubes and other irregular shapes, have been incorporated into the OPVs to promote light absorption and thus improve device's power conversion efficiency (PCE) by using their surface plasmon resonance and light scattering. In this work, Au@poly(sodium 4-styrenesulfonate) (PSS) core-shell tetrahedra nanostructures, synthesized by seed mediated growth, are incorporated into OPVs for the first time. Both the use of Au tetrahedra core and the introduction of ultrathin PSS shell are beneficial for generating and maintaining a strong local field. With an optimal concentration of Au@PSS NPs, the PCE achieves 9.42% (with a maximum value of 9.53%), showing an enhancement factor of 15.30% compared with that in the control device. The optical and electrical effects of Au@PSS tetrahedra NPs are systematically investigated to comprehensively understand the superior performances of our plasmonic OPVs.