Stress and the Goal of Improved Amorphous Silicon Stability

Abstract

ABSTRACTThe stability of amorphous silicon-based solar cells is related to the i-layer carrier mobilities as these determine the carrier densities under illumination. Materials with high mobilities quickly diffuse the carriers to high recombination regions such as the contacts and interface regions. The quick out diffusion of carriers lowers the i-layer carrier densities and therefore the driving force for defect generation. Increased compressive stress appears to be correlated to increased electron mobility and is related to the hydrogen content. Solar cell configurations also play a role in the i-layer carrier density. For example, factors that increase the V∝ tend to decrease the stability because the associated decrease in interface recombination results in increased i-layer carrier densities. Factors that reduce the blue response such as increased interface recombination tend to increase the stability as these results in reduced i-layer carrier densities.