Improvement of Photodegradation of Silicon Thin-film Solar Cells by pc-Si:H/a-Si:H Multilayers

A series gradual changing of protocrystalline phase of hydrogenated protocrystalline silicon/hydrogenated amorphous silicon (pc-Si:H/a-Si:H) multilayers is fabricated by periodically changing hydrogen dilution ratios (R = H2/SiH4). Protocrystalline phase can be well identified by Raman peak shift and the variation of dielectric function measured by spectroscopic ellipsometer. Increasing R can effectively increase the protocrystalline phase, optical energy gap, and reduce the density of films. More protocrystalline phase can suppress the photodegradation effects of the pc-Si:H/a-Si:H multilayers solar cells, but reduce the initial efficiency. Therefore, the performance of cells could be optimised by suitable protocrystalline phase for obtaining good stability and efficiency.