Fabrication and characterization of high-efficiency CdTe-based thin-film solar cells on commercial SnO2:F-coated soda-lime glass substrates

• CSS processed CdTe solar cells were synthesized on commercial SnO2:F-coated soda-lime glass substrate.
• An efficiency of 15.5% was achieved with sputtered CdS.
• Oxygen incorporation in CdS was found to be beneficial to control the inter-diffusion.

Superstrate CdTe-based thin-film solar cells with conversion efficiencies higher than 15% have been synthesized on commercial SnO2:F/SnO2-coated soda-lime glass substrates without anti-reflection coating. The n-type CdS window layers were prepared by R.F. sputtering in an ambient containing a small amount of oxygen concentration. CdTe absorber layers were obtained by close-spaced sublimation (CSS). The post deposition CdCl2 activation was conducted in a dry air ambient. With the application of elemental Cu/Au back contacts, the best small-area CdTe cells (0.08 cm2) have shown an efficiency of 15.5% with an open-circuit voltage of 844 mV, a short-circuit current of 24.0 mA/cm2, and a fill-factor of 76.6% measured under an AM1.5 illumination. This efficiency was achieved when a 1% O2 concentration was used in sputtering ambient during CdS deposition.