Abstract: A multiple solar cell having at least two partial cells, at least being formed from a direct semiconductor, having an upper partial cell facing the light and a lower partial cell facing away from the light, an upper bandgap of the upper partial cell being greater than a lower bandgap of the lower partial cell, and an intermediate layer arranged on the lower partial cell side facing away from the light. An optical element including a lower mirror element is arranged on the intermediate layer side facing away from the light, and has a partial element having structural elements arranged in a lateral direction on the intermediate layer side facing away from the light. The structural elements have a mean spacing less than or equal to 1.3 times a spacing value that results from a ratio of a wavelength of the lower bandgap to a refractive index of the lower partial cell or the lower mirror element has a roughness having a root-mean-square value of less than 50 nm.

Abstract: Multijunction solar cells are provided having at least four p-n junctions with a rear-side germanium subcell, orientated away from the light, and at least three subcells made of III-V compound semiconductors, disposed above the germanium subcell, the multijunction solar cells having at least one metamorphic buffer layer and at least one wafer-bonded compound and all the layers, which are disposed above the germanium subcell, comprising respectively a light-absorbing emitter- and/or base layer which comprise at least 20% indium, relative to the sum of all the atoms of group III. Furthermore, methods of using of these multijunction solar cells in space are also provided.