Hydrogenated nanocrystalline silicon p-layer in amorphous silicon n–i–p solar cells

This paper describes an investigation into the impacts of hydrogenated nanocrystalline silicon (nc-Si:H) p-layer on the photovoltaic parameters, especially on the open-circuit voltage (Voc) of n–i–p type hydrogenated amorphous silicon (a-Si:H) solar cells. Raman spectroscopy and transmission electron microscopy (TEM) analyses indicate that this p-layer is a diphasic material that contains nanocrystalline grains with size around 3–5 nm embedded in an amorphous silicon matrix. Optical transmission measurements show that the nc-Si:H p-layer has a wide band gap of 1.9 eV. Using this nanocrystalline p-layer in n–i–p a-Si:H solar cells, the cell performances were improved with a Voc of 1.042 V, whereas the solar cells deposited under similar conditions but incorporating a hydrogenated microcrystalline silicon (μc-Si:H) p-layer exhibit a Voc of 0.526 V.