Device Characteristics of CZTSSe Thin‐Film Solar Cells with 12.6% Efficiency

A 12.6% Cu2ZnSnSxSe4–x (CZTSSe) solar cell is presented with detailed device characteristics. Both short-circuit current density (Jsc) and open circuit voltage (Voc) increase in the 12.6% champion, relative to previous devices, due to better bulk CZTSSe quality and improved optical architecture. The reduction in Voc deficit shows opportunities to push CZTSSe solar cells to higher efficiency.