High-efficiency CdS/CdTe solar cells on commercial SnO2:F coated soda-lime glass substrates

High efficiency CdTe-based thin-film solar cells with a superstrate configuration have been fabricated on commercial SnO₂:F/SnO₂-coated soda-lime glass substrates. The CdS window layers were deposited by magnetron sputtering, and the CdTe absorber layers were deposited by close-spaced sublimation. The back-contacts are elemental Cu/Au bilayers. CdCl₂ activations were carried out in dry air. Without antireflection coating, the best small-area cell has shown an efficiency of 15.8% with an open-circuit voltage of 845 mV, a short-circuit current of 24.5 mA/cm², and a fill-factor of 76.8% measured under an AM1.5 illumination. We find that besides optimizing the growth process of the window and absorber layers and the CdC1₂ activation steps, incorporating a small amount of oxygen in the CdS window layers is essential for achieving high efficiency CdTe solar cells.