Ultrathin CdS/CdTe solar cells by sputtering

We have prepared thin-film CdS/CdTe cells with CdTe thickness from 0.25 μm to 2.1 μm on commercial SnO2:F-coated soda-lime glass with a high resistivity transparent SnO2 buffer layer. With careful optimization of the magnetron sputtering conditions, CdS and Cu thicknesses, CdCl2 activation, and back-contact diffusion processes, we obtain 8% efficiency with only 0.25 μm of CdTe and 11% efficiency with 0.5 μm. The results confirm the advantages of magnetron sputtering for ultra-thin CdTe and show some light trapping and excellent carrier collection even for the thinnest devices.

► Magnetron sputtering is a superior method for fabricating ultrathin CdTe cells.
► 8% (11%) efficiency was obtained with only 250 nm (500 nm) of CdTe.
► We report the highest ever efficiencies for CdTe cells ≤1 μm thick.
► QE analysis shows the Cu/Au back contact improves red and near IR response.