Synergistic effect of surface plasmonic particles in PbS/TiO2 heterojunction solar cells

Core–shell particles composed of a dielectric core and a metallic nanoshell exhibit tunable surface plasmons that may be exploited to enhance the light absorption capability of photoactive materials. This work uses both experimental and theoretical methods to elucidate the mechanism by which SiO2@Au@SiO2 (SGS) core–shell–shell particles improve the light harvesting efficiency of PbS–TiO2 heterojunction solar cells. The enhanced light absorption by PbS nanoparticles depends on their location in the device and their impact on device morphology. This study demonstrates that SGSs can promote the light harvesting of thin film solar cells in two ways. First, the localized surface plasmon resonance of the SGSs increases light scattering and the local electromagnetic field at the PbS–SGS interface. Second, placing SGSs between the PbS and TiO2 layers, forms nanodomes on top Au electrode and gives rise to additional light scattering that enhances the light harvesting efficiency. By combining these effects the short circuit current density and the energy conversion efficiency are increased by 29% and 24% respectively compared to a cell without SGSs.