Relationship between absorber layer defect density and performance of a-Si:H and [mu]c-Si:H solar cells studied over a wide range of defect densities generated by 2 MeV electron bombardment

We summarize an extensive study on the impact of absorber layer defect density on the performance of amorphous (a-Si:H) and microcrystalline ([mu]c-Si:H) silicon solar cells. To study the effects of the absorber layer defect density we subjected set of a-Si:H and [mu]c-Si:H cells to a 2 MeV electron bombardment. For reference we subjected i-layers to the same treatment as the cells. The procedure enabled the reversible increase of the i-layer defect density (N sub(s)) with two orders of magnitude according to electron spin resonance measurements (ESR) performed on reference samples. Based on the experimental data we speculate that the improvement of absorber material in terms of as-deposited defect density is not of primary importance for the performance of a-Si:H cells, whereas in [mu]c-Si:H based solar cells, the reduction of the absorber layer defect density below the state-of-the-art levels, seems to improve the cell performance.