Tandem junction photovoltaic device comprising copper indium gallium di-selenide bottom cell

A tandem junction photovoltaic device comprising:

• a top cell having a first band gap energy of approximately 1.7-1.75 eV and comprising an n-type layer of a polycrystalline alloy of silicon carbon, and a p-type layer of a polycrystalline alloy of silicon carbon disposed in contiguous contact with the n-type layer, thereby forming a rectifying junction;
• and
• a bottom cell having a second band gap energy lower than the first band gap energy, and including an n-type cadmium sulfide layer and a p-type copper indium gallium di-selenide layer disposed in contiguous contact with the n-type cadmium sulfide layer, thereby forming a heterogeneous rectifying junction.

13 The tandem junction photovoltaic device of claim 11 wherein the p-type layer is polycrystalline silicon carbon with carbon content of approximately 30-45 at. %.

A tandem junction photovoltaic device comprising:

• a top cell having a first band gap energy of approximately 1.7-1.75 eV and comprising an n-type layer of a polycrystalline alloy of silicon carbon, and a p-type layer structure disposed in contiguous contact with the n-type layer, thereby forming a rectifying junction, the p-type layer structure comprising a plurality of alternating layers of p-type polycrystalline silicon carbon (pc-SiC) and p-type polycrystalline silicon germanium (pc-SiGe);
• and
• a bottom cell having a second band gap energy lower than the first band gap energy, and including an n-type cadmium sulfide layer and a p-type copper indium gallium di-selenide layer disposed in contiguous contact with the n-type cadmium sulfide layer, thereby forming a heterogeneous rectifying junction.