Analysis of contact degradation at the CdTe-electrode interface in thin film CdTe-CdS solar cells

Atmospheric degradation of unencapsulated CdS-CdTe solar cells was modeled by assuming that the initial CdTe/electrode interface becomes a metal/insulator/semiconductor junction as oxygen diffuses through the metal to form a CdTeO3 insulating layer. The doping concentration, barrier height, and oxide thickness were varied and the numerical calculations were compared with the experimental data on cells aged in a humidity chamber. The degradation was most severe when the cells were exposed to high humidity and high temperature. This degradation could be modeled in terms of the growth of the insulating CdTeO3 layer from 20 Å to 80 Å.