Solar cell

A solar cell comprising:

• a monocrystalline silicon substrate;
• a tunneling layer formed of one of nitride, oxide and oxide nitride, and formed directly on a rear surface of the monocrystalline silicon substrate;
• a first back surface field layer directly formed over the tunneling layer and formed of a polycrystalline silicon;
• a second back surface field layer positioned inside of the rear surface of the monocrystalline silicon substrate, thereby the tunneling layer is between the first back surface field layer and the second back surface field layer, wherein the second back surface field layer is formed of a monocrystalline silicon;
• an emitter layer positioned inside of a front surface of the monocrystalline silicon substrate;
• a first insulating film formed on the first back surface field layer;
• a second insulating film formed on the emitter layer;
• a first electrode directly connected to the first back surface field layer through a plurality of first openings of the first insulating film;
• and
• a second electrode directly connected to the emitter layer through a plurality of second openings of the second insulating film,
• wherein the first electrode physically contacts the first back surface field layer and does not directly physically contact the second back surface field layer, and
• wherein the tunneling layer has a thickness of 0.5 nm to 5 nm, and the first back surface field layer has a thickness of 50 nm to 500 nm.