Anomalous effects of dielectric coated plasmonic metal nanoparticles on solar absorption enhancement in perovskite thin films

Abstract

Localized surface plasmon resonances in metallic nanostructures have been extensively harnessed for light absorption enhancement in various solar cells, including perovskite solar cells (PSCs). For stabilization and functionalization, plasmonic metal nanostructures are often coated with dielectric shells. In this work, we numerically investigate the effects of dielectric coated plasmonic metal nanoparticles (NPs) on solar absorption enhancement in perovskite thin films. To our surprise, a further absorption enhancement compared with the films embedding bare Ag NPs can be achieved when using thin dielectric coating of high refractive index, while an absorption reduction in comparison with bare perovskite thin films may take place when the embedded Ag NPs are coated with thick dielectric shells of low refractive index. The physics behind is addressed within classic electrodynamics. These anomalous effects extend our knowledge of PSCs, providing guidelines for optimized design of plasmonic solar cells.