Insights into the degradation mechanisms of CIGSSe devices based on different heterojunctions

Uncapsulated CdS buffered chalcopyrite solar cells as well as devices where the buffer and the intrinsic part of the rf-sputtered ZnO window bi-layer is replaced by a ZnO window extension layer were exposed to damp-heat (DH) conditions. In order to investigate the degradation mechanisms they were characterized by J(V)-measurements under standard test conditions and at different temperatures (200-330 K) and illuminations (0.1-100 mW/cm/sup 2/) as well as by quantum efficiency, ultrahigh vacuum Kelvin probe force microscopy and elastic recoil detection analysis before and after DH. All measurements reveal a significant change of the corresponding characteristics induced by DH.