Effects of moisture on CIGSS solar cells

This paper focuses on the effect of moisture on CIGSS cells made by Shell Solar Industries (SSI). These studies were carried out with 10 cm /spl times/ 10 cm monolithically integrated CIGSS circuits and individual cells diced from circuits. Cells under investigation were subjected to an environment of 60/spl deg/C/90%RH and characterized at various time intervals. Illuminated and dark I-V characteristics, and quantum efficiency were measured versus time. The effects of moisture on the sheet resistance of the ZnO TCO and the Zn/O ratio were also examined. Efficiency of uncoated CIGSS cells subjected to the accelerated test conditions degrade from 10% to 1% within a few hundred hours. Two significant effects are found to contribute to the degradation, the sheet resistance of ZnO increases significantly, and the junction recombination losses increase.