Comparison of amorphous silicon solar cell performance following light and high-energy electron-beam induced degradation

In this article a comparison is reported between amorphous silicon (a-Si:H) solar cells that have been degraded using light soaking and 1 MeV electron-beam irradiation. Solar cells were degraded in open- and short-circuit condition, with the aim to change the recombination profile in the cell. For light-soaked solar cells a clear difference is found between open- and short-circuit conditions. Under open-circuit condition the solar cells degrade much more, which is explained by a much higher recombination rate under illumination in this case. These recombination events are believed to initiate defect formation. The performance of thin solar cells degrades less, as expected. For solar cells degraded under electron-beam irradiation no difference is found between open- and short-circuit conditions. Therefore we think that during electron-beam irradiation defect creation is not initiated by recombination events, but by energy transfer during collisions. The fill factor of thin solar cells degrades more after electron-beam irradiation. This effect is ascribed to a significant increase of the activation energy of the doped layers after irradiation.