A stable ytterbium-insulator-semiconductor solar cell based on an interface degradation model

A comprehensive analysis of shelf life degradation in metal-insulator-semiconductor (MIS) solar cells has been performed. The instabilities associated with Cr-MIS solar cells result from a decrease in the insulator thickness. On modeling Sehottky-barrier formation against oxide thickness variations, one finds that there is a range of oxide thicknesses which permit photocurrent collection and also give rise to stable MIS structures. This is specially true for low work function (φ
M
) metals. Ytterbium (φ
M
= 2.6) was a good candidate because of its excellent thin-film optical properties and its compatibility to MIS processing. Yb-MIS solar cells have proved to be very stable and obey the stability trends predicted by our model. In addition, Yb-MIS solar cells result in competitive photovoltaic conversion effieiencies (> 11.5 percent at AMI illumination).