Inverted metamorphic multijunction solar cell with two metamorphic layers and homojunction top cell

A multijunction solar cell including an upper first solar subcell having a first band gap, and the base-emitter junction of the upper first solar subcell being a homojunction; a second solar subcell adjacent to said first solar subcell and having a second band gap smaller than said first band gap; a third solar subcell adjacent to said second solar subcell and having a third band gap smaller than said second band gap. A first graded interlayer is provided adjacent to said third solar subcell; said first graded interlayer having a fourth band gap greater than said third band gap. A fourth solar subcell is provided adjacent to said first graded interlayer, said fourth subcell having a fifth band gap smaller than said third band gap such that said fourth subcell is lattice mismatched with respect to said third subcell. A second graded interlayer is provided adjacent to said fourth solar subcell; said second graded interlayer having a sixth band gap greater than said fifth band gap; and a lower fifth solar subcell is provided adjacent to said second graded interlayer, said lower fifth subcell having a seventh band gap smaller than said fifth band gap such that said fifth subcell is lattice mismatched with respect to said fourth subcell.