High-efficiency and Low-cost Multi-junction Solar Cells with GaAs Multi-stacked Structure

Abstract

Multi-junction (MJ) solar cells provide ultra-high efficiencies by the effectively utilizing the solar spectrum. A conventional fabrication method is a monolithic epitaxial growth technique with complicated layer structures. We demonstrate the use of GaAs multi-stacked structures as the top cells of MJ solar cells, which can be obtained using a relatively easy growth technique. As an initial verification, we fabricated a GaAs/GaAs//InGaAsP three-junction solar cell using a smart stack technology and obtained an efficiency of 20.2% at 1sun (AM1.5g). These results demonstrate the possibility to use the GaAs multi-stacked structures in next-generation MJ solar cells.