Efficiency improvement of Si solar cells using metal-enhanced nanophosphor fluorescence

In this study, Eu²⁺-doped barium silicate (Ba ₂SiO₄:Eu²⁺) nanophosphors dispersed in a surfactant solution were spin-coated on commercially available silicon solar cells to form colloidal crystals on the surface. The crystals then act as luminescence down-shifting centers to generate low-energy photons for incident ultraviolet light. The fluorescence from the Ba₂SiO ₄:Eu²⁺ nanophosphors was further enhanced by coating a metal-enhanced layer composed of Ag nanoparticles and a SiO₂ spacer. The solar cells showed an enhancement of 0.86 mA/cm² in short-circuit current density and approximately 0.64% increase in power conversion efficiency when coated with nanophosphors, SiO₂ spacers, and Ag nanoparticles. The properties of cells integrated with the metal-enhanced layer were characterized to identify the roles of nanophosphors and Ag nanoparticles in improved light harvesting. These experiments demonstrated that the colloids of Ba₂SiO₄:Eu²⁺ acted as luminescence down-shifting centers in the ultraviolet region and the metallic nanoparticles also helped to enhance fluorescence in the visible region to increase light absorption within the measured spectral regime.