High-Efficiency Epitaxial CIGS-Silicon Tandem Solar Cell – EPCIS

The PV sector is experiencing a fast growth and is becoming one of the main pillars for the energy transition. The goal of 30% efficiency (challenging roadmap issued during COP21, initiated by IPVF and named “30-30-30”) will be extremely difficult to reach with classical solar cells based on single junctions. On contrary, tandem cells could reach 43% theoretically by combining a VIS/NIR bottom cell, Si-made, with a top cell collecting the blue/UV range of the solar spectrum, which could be a CIGS top cell specially optimized with a bandgap about 1.7 eV. We propose a new and disruptive approach based on using wideband gap III-V (GaP-based) buffer layers between Si and CIGS. We expect that epitaxial (CIGS/III-V/Si substrate) developed in this project will reach 18% at 1.7 eV. Original designs of (CIGS/III-V/Si/Si substrate) tandem cells with two terminals and a efficiency of 25% are proposed at the end of the project.