“UNSW researchers have achieved a world record energy conversion efficiency of 13.2% for high-bandgap kesterite (CZTS) solar cells with a laboratory scale cell that had been enhanced with hydrogen.

CZTS, a compound of copper, zinc, tin and sulfur, is a high-bandgap thin film, flexible material suitable that offers a promising alternative to the more widely studied perovskite as a tandem top-cell candidate because it is environmentally friendly, cost-effective to manufacture, and is known to maintain its performance over a long period.”

From pv magazine.