Effect of CdS thickness on CdS/CdTe quantum efficiency [solar cells]

A significant photocurrent loss in CdS/CdTe solar cells is due to window-layer CdS bandgap absorption below 520 nm. This work evaluates a coordinated effort by six laboratories to optimize the CdS thickness to increase CdTe cell performance, Quantum efficiency is used to compare CdS/CdTe solar cell photocurrent performance for various CdS window-layer thicknesses in the range of 400 /spl Aring/ to 2500 /spl Aring/. The contribution to J/sub sc/ from wavelengths below 520 nm, corresponding to the CdS bandgap, shows a photocurrent difference of roughly 5 mA/cm/sup 2/ between the practical thick and thin CdS layer thicknesses, corresponding to a possible efficiency difference between 12% and 15%. Additionally, there appears to be a process-dependent lower limit to the minimum CdS thickness for good-junction cells.