Breakeven criteria for the GaInNAs junction in GaInP/GaAs/GaInNAs/Ge four‐junction solar cells

Abstract

AbstractThe four‐junction GaInP/GaAs/GaInNAs/Ge solar cell structure holds the promise of efficiencies exceeding those of the GaInP/GaAs/Ge three‐junction cell, which at present is the benchmark for high‐efficiency multijunction cell performance. The performance of GaInNAs junctions demonstrated to date has been insufficient for the realization of these projected efficiency gains, owing to poor minority‐carrier properties in the GaInNAs. However, incremental improvements in the GaInNAs junctions have brought this breakeven point within sight. In this paper, we use a semiempirical approach to estimate the efficiency of the GaInP/GaAs/GaInNAs/Ge four‐junction solar cell structure as a function of the performance parameters of the GaInNAs third junction. The results provide guidance on the extent to which the current and voltage of present‐day GaInNAs junctions will need to be improved in order for the resulting four‐junction cell to realize its potential for efficiencies higher than that of GaInP/GaAs/Ge benchmark. Published in 2002 by John Wiley & Sons, Ltd.