A solar cell is disclosed. The solar cell includes a substrate, a first electrode on the substrate, a second electrode, and a photoelectric transformation unit between the first electrode and the second electrode. The photoelectric transformation unit includes a first intrinsic (referred to as an i-type) semiconductor layer formed of amorphous silicon doped with at least one of carbon (C) and oxygen (O) as impurities and a second i-type semiconductor layer formed of germanium (Ge)-doped microcrystalline silicon.
