Minority carrier mirror

Fig. 12. Efficiency as a function of cell thickness and junction depth A. The upper figure is for CuInSe2, and the lower for GaAs. No optical mirrors are incorporated in these cells but they do have minority carrier mirrors on both external surfaces. 

In conclusion, this theoretical investigation points the way toward optimized performance from a minimum thickness of direct gap semiconductor. It shows that higher efficiency can be expected from slimmed-down solar cells, provided that they incorporate minority carrier mirrors. If these mirrors are of the abrupt junction type (e.g., a p-p junction), they make it easy to incorporate such cells into tandem solar cell systems. 

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