N-type Ag 2 S modified CZTSSe solar cell with lowest V oc,def

The Sn, Zn-doped Ag 2 S plays a triple role in CZTSSe devices: p–n conversion, front-interface bandgap grading, and defect passivation. This strategy achieved an efficiency of 14.25%, with the V oc of 0.584 V and the lowest V oc,def of 0.228 V.