A solar cell device is provided, including a transparent substrate, a transparent conductive layer disposed over the transparent substrate, a photovoltaic element formed over the composite transparent conductive layer, and an electrode layer disposed over the photovoltaic element. In one embodiment, the transparent conductive layer includes lithium and fluorine-co-doped tin oxides, and the lithium and fluorine-co-doped tin oxides have a lithium doping concentration of about 0.2˜2.3% and a fluorine doping concentration of about 0.1˜2.5%.