1.62 eV/1.1 eV InGaP/InGaAs dual-junction solar cell development on lattice-mismatched GaAs

The authors report progress towards achieving a high efficiency monolithic dual-junction solar cell consisting of a 1.62 eV InGaP top cell and a 1.1 eV InGaAs bottom cell grown on a lattice-mismatched GaAs substrate using a proprietary buffer layer scheme. They have achieved air mass zero (AMO), one-Sun efficiencies of 17.5% for the 1.1 eV InGaAs and 15.7% for the 1.6 eV InGaP standalone cells on lattice-mismatched GaAs. The predicted AMO, one-Sun efficiency of a 1.62 eV/1.1 eV n/p dual-junction cell is 27%. To date, they have achieved an efficiency of 19% in their dual-junction cells. Further process optimization experiments are currently underway, aimed at achieving the 27% efficiency goal.