Component Integration Effects in 4-Junction Solar Cells with Dilute Nitride 1eV Subcell

A GaInP/Ga(In)As/GaNAsSb/Ge 4-junction solar cell grown using combined MOVPE+MBE growth is used to analyze the effects during the integration of the subcell components into the full 4J structure. In this preliminary study, the Ge subcell is observed to suffer about 15% Jsc drop and ~50 mV Vocloss at 1-sun, while the Voc of the GaNAsSb subcell drops by as much as − 140 mV. The degradation of the Ge and GaNAsSb subcells in the current-matched 4J structure can hinder its efficiency potential to a higher extent than in the GaInP/Ga(In)As/Ge 3J. Besides, high quality GaNAsSb and Ge subcells would still limit the current and require redesigning the top subcells to achieve optimum efficiencies.