Monocrystalline 1.7 eV MgCdTe double-heterostructure solar cell with 11.2% efficiency

A dual-junction 1.7-eV/1.1-eV tandem cell has a theoretical efficiency limit of 45% under the AM1.5G spectrum. Combining an efficient thin-film semiconductor with a 1.7 eV bandgap as the top cell with a 1.1 eV silicon subcell offers a practical pathway to further cost-reduction of solar power generation. This paper reports the demonstration of a monocrystalline 1.7 eV Mg
_0.13
Cd
_0.87
Te solar cell grown by molecular beam epitaxy with an active-area efficiency of 11.2% and an open-circuit voltage of 1.176 V.