Performance of inorganic photovoltaic structures employing heterojunctions with large band gap materials

In this work we have fabricated inorganic Silicon solar cells coated by a thin layer of Al-doped ZnO (ZnO:Al). Planar solar cells were fabricated by spin on dopant diffusion method. Thin layers of ZnO:Al were deposited by Atomic Layer Deposition method at different temperatures and ZnO/Al ratios. As a result of the deposition of a large bandgap material on top of the sample, it was found that both open circuit voltage and short current density were increased, leading to a power conversion efficiency increase from 7.3% to 8.5%, which correspond to an increment of about 16% after the deposition of ZnO:Al. This increase could be related to a reduction on the surface defects of the sample after the deposition of the thin layer, but also to an increase of carriers provided by the large bandgap layer. Further investigations are in process to understand in a better way this effect.