Abstract: A method of operating a solar cell is provided in which strain balanced multiple quantum well stacks containing greater than 30 quantum wells disposed between bulk semi-conductor regions having a band gap differences between the deepest well of the stack and the bulk semi-conducting region of greater than 60 mev is irradiated with radiation having an intensity of greater than 100 suns. Photons are absorbed with and outside of the quantum well stack to generate electron hole pairs recombination of electrons and holes is substantially only via a radiative recombination mechanism.

Abstract: A solar cell formed from a semiconductor having a relative wide band-gap E.sub.b- characterized by a multi-quantum well system incorporated in the depletion region of the cell in which the quantum wells comprise regions of semiconductor with a smaller band gap separated by small amounts of the wider band-gap semiconductor (E.sub.b) so that the effective band-gap for absorption (E.sub.a) is less than E.sub.b.