Intrinsic defect compensation in the space charge region enables cadmium-free kesterite solar cells to achieve 13.9% certified efficiency

Ventilated-air junction heat treatment (JHT) promotes Zn diffusion across the CZTSSe/ZTO interface, leading to intrinsic defect compensation and optimized band alignment, thereby enabling a certified PCE of 13.90% in Cd-free CZTSSe solar cells.