Dual p-type layers consisting of a p-type hydrogenated amorphous silicon oxide (p-a-SiOx:H) layer and a p-type hydrogenated nanocrystalline silicon oxide (p-nc-SiOx:H) layer were used as the window layer in a hydrogenated-amorphous-silicon (a-Si:H) p-i-n thin-film solar cell with a fluorine-doped tin-oxide (FTO, SnO2:F) front electrode. Through this method, high conductivity, which originated from the p-nc-SiOx:H layer with higher optical bandgap, was imparted to the a-Si:H solar cell. The destabilization problems of Sn4+ in FTO were solved by using a high-flux hydrogen plasma during the growth of p-nc-SiOx:H. The properties of the a-Si:H solar cell were controlled by changing the thickness of the p-a-SiOx:H and p-nc-SiOx:H layers. The dual p-type layers in the a-Si:H solar cell exhibited enhanced transmission of holes and decreased recombination current. The p-nc-SiOx:H film in the dual p-type layers increased the built-in potential in the a-Si:H solar cell to obtain a higher opencircuit voltage and a higher short-circuit current density. Finally, the conversion efficiency of the a-Si:H solar cell was enhanced by 12.90% through the adoption of the p-a-SiOx:H(7 nm)/p-nc-SiOx:H(7 nm) nanostructure for the dual p-type layers.