Limiting efficiencies over 50% using multijunction solar cells with multiple exciton generation

The achievement of solar cells over 50% is a critical goal for photovoltaics. Multijunction solar cells over 5 junctions allow such efficiencies, but are severely limited by material constraints and growth requirements for lattice matching. Nanostructured approaches such as multiple exciton generation (MEG) potentially offer a route to higher efficiency but still require high values of sunlight concentration and large quantum yields. We show an approach that allows for higher efficiencies based on including MEG in a multijunction solar cell. We also present a thermodynamic model for multijunction solar cells with MEG that demonstrates possible improvements.