Window losses and current mismatch computer modeling studies in AIGaAs-GaAs cascade solar cell

Two-junction AlGaAs-GaAs cascade solar cell computer modeling studies are reported for operation at 300 K, AM 0, and unity solar concentration. An optimized design is obtained by maximizing conversion efficiency. Device performance characteristics are investigated by separately varying the structure parameters. These effects are described through a discussion of the excess current and power utilization ratio parameters, both of which are related to current mismatch between top and bottom cells. Window layer losses are shown to contribute the major loss factors in an optimized designed cascade solar cell using this materials system. The study concludes by showing that if the bulk and surface recombination losses in the window layer are removed, conversion efficiency exceeding 31 percent is attainable.