Improvement of solar cell performance and reversibility of ageing effects in hydrogenated amorphous silicon solar cells under illumination and electric field stress: Role of TCO and substrate

The ageing effects of hydrogenated amorphous Si (a-Si:H) under illumination have been investigated. These are strongly affected by the well-known Staebler-Wronski effect, occurring during light soaking of a-Si:H, producing a substantial loss of cell power conversion efficiency. In this work the light soaking effect was investigated and it was shown that the application of a strong electric field in reverse bias not only slows down the solar cell ageing kinetics but also even produces an improvement of the cells parameters. Such improvements have been investigated discussing the impact of temperature, electric field intensity, illumination level, substrate type and reversibility properties. Further information on the possible improvement causes are provided by the analysis of the behavior of single thin films of doped a-Si:H, and by comparing to the case of micromorph solar cells.