Improved p–i–n solar cells structure for narrow bandgap a-Si:H prepared by Ar* chemical annealing at high temperatures

Improved device structures including transparent conductive oxide (TCO) and p-layers were studied for better photovoltaic performance with narrow bandgap a-Si:H solar cells prepared in p–I–n sequence on TCO-coated glass. The narrow bandgap (Eg⩽1.58 eV) a-Si:H i-layers used here were prepared by an Ar* chemical annealing technique at temperatures over 280°C. Ga-doped ZnO (GZO) deposited at high substrate temperatures (250°C) and microcrystalline p-layers (μc-Si:H(B)) showed improved resistance to high temperatures and Ar* bombardment-induced degradation. By employing p/i buffer layer along with these TCO and p-layers, the open-circuit voltage was increased from 0.36 to 0.56 V and the fill factor increased from 24 to 60%. In addition, enhanced red-response was observed on the narrow bandgap (Eg=1.52 eV) a-Si:H solar cells.