Stability of Amorphous Silicon Solar Cells

The present situation on the stability of amorphous silicon solar cells is discussed. Impurity diffusion is not expected to be a problem in normal cell operation. Interface contamination degrades Schottky barrier or MIS cells that are exposed to water vapor, but has no influence on p-i-n or n-i-p cells. Optically induced changes in the amorphous silicon have an influence, depending on cell structure and preparation conditions. Preliminary results on ¿ 5% efficiency n-i-p cells suggest that the efficiency will degrade by only 20% in 20 years of sunlight.