CdTe solar cells with iron pyrite thin film back contacts fabricated by a hybrid sputtering/co-evaporation process

We report the properties of sputtered/co-evaporated thin film iron pyrite as the back contact interface layer of CdS/CdTe solar cells. In our study we have compared the performance of sputter-deposited CdTe devices which utilized either a Cu/Au contact, or an FeS
₂
/Cu/Au contact. Comparing our best devices of each type, the FeS
₂
contact layer has improved the V
_OC
by ~16 mV, to 816 mV, and improved the FF by ~4.7% absolute to 73.7%, with respect to devices omitting the FeS
₂
layer. Under Standard Test Conditions of 100 mW/cm and 25 °C, devices utilizing the FeS
₂
back contact have shown a relative increase in the power conversion efficiency by ~7.5%, with a best device efficiency of 12.9%.