Solar cell stack

A solar cell stack formed of III-V semiconductor layers, the solar cell stack comprising:

• a first subcell having a first band gap and having a first lattice constant;
• and
• a second subcell having a second band gap and having a second lattice constant;
• and
• an intermediate layer sequence disposed between the first subcell and the second subcell, the intermediate layer sequence including a first barrier layer and a tunnel diode and a second barrier layer, the tunnel diode including a degenerate n+ layer having a third lattice constant and a degenerate p+ layer having a fourth lattice constant, the fourth lattice constant being smaller than the third constant, and the first band gap being smaller than the second band gap, and the p+ layer having a different material composition than the n+ layer,
• wherein the p+ layer contains at least 5 atomic percent of indium and contains carbon as the dopant,
• wherein the layers of the tunnel diode and the other layers of the intermediate layer sequence are not strain-compensated with respect to each other, and
• wherein the first subcell and the second subcell are lattice-matched to each other, and the degenerate p+ layer has a lattice mismatch of at least 0.5%, and the lattice constant of the p+ layer has a smaller lattice constant than the first lattice constant and the second lattice constant, and the third lattice constant of the degenerate n+ layer is lattice-matched to the first lattice constant or to the second lattice constant.