Impact of transparent conductive oxide front side texture on the open-circuit voltage of a-Si:H solar cells

摘要

High efficiency thin-film silicon solar cells require texturing of the front contacts for advanced light management. However, optically favorable textures may be challenging in terms of the electrical performance. Solar cells deposited on very rough front contacts show a reduced open-circuit voltage, V_(oc), as compared to flat TCOs. This contribution focuses on the impact of rough surfaces on the V_(oc) in a-Si:H solar cells deposited on six different textured front TCOs. With various i- layer thicknesses from 100 to 400 nm the origin of the V_(oc) loss is investigated. Based on our results we propose that the reduction of V_(oc) in a-Si:H solar cells are mainly due to defective regions in the bulk material induced by very rough textures. It is also seen that enlarging the i-layer thickness can improve the V_(oc) of solar cells when grown on very rough textures. By using variable illumination intensity measurements the existence of shunts could be evidenced.