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

Abstract

In this study, Eu2+-doped barium silicate (Ba2SiO4: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 Ba2SiO4: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/cm(2) 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. (C) 2013 Elsevier B.V. All rights reserved.