A simple solution-based route to high-efficiency CZTSSe thin-film solar cells

Solution-based Cu₂ZnSn(S,Se)₄ (CZTSSe) thin film deposition routes focusing on chemistries with attractive scalability and handling characteristics, while delivering high efficiency devices are promising technologies for low-cost solar cells. In this paper we describe a new approach for the fabrication of CZTSSe thin films using inks comprised of mixtures of binary and ternary metal-chalcogenide nanocrystals dispersed in simple organic solvents. The resulting blended inks can be coated under ambient conditions to give precursor films which are in turn converted to device-quality CZTSSe absorbers via thermal annealing in a selenium atmosphere. Using this approach we have demonstrated CZTSSe solar cells with total area efficiencies in excess of 8.5% (or 9.6% per active area) under 1 Sun AM1.5 illumination.