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

摘要

A multijunction solar cell including an upper first solar subcell, and the base-emitter junction of the upper first solar subcell being a homojunction; a second solar subcell adjacent to said first solar subcell; a third solar subcell adjacent to said second solar subcell. A first graded interlayer is provided adjacent to said third solar subcell. A fourth solar subcell is provided adjacent to said first graded interlayer, said fourth subcell is lattice mismatched with respect to said third subcell. A second graded interlayer is provided adjacent to said fourth solar subcell; and a lower fifth solar subcell is provided adjacent to said second graded interlayer, said lower fifth subcell is lattice mismatched with respect to said fourth subcell.

主权项

1. A multijunction solar cell comprising:
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 in a range of approximately 1.3 to 1.5 eV and smaller than said second band gap; a first graded interlayer adjacent to said third solar subcell, said first graded interlayer having a fourth band gap greater than said third band gap and that is constant at 1.5 eV throughout the thickness of the first graded interlayer; and a fourth solar subcell adjacent to said first graded interlayer, said fourth subcell having a fifth band gap in a range of approximately 1.0 to 1.2 eV wherein said fourth subcell is lattice mismatched with respect to said third subcell; a second graded interlayer adjacent to said fourth solar subcell, said second graded interlayer having a sixth band gap greater than said fifth band gap and that is constant at approximately 1.1 eV throughout the thickness of the second graded interlayer; and a lower fifth solar subcell adjacent to said second graded interlayer, said lower fifth subcell having a seventh band gap smaller than said fifth band gap wherein said fifth subcell is lattice mismatched with respect to said fourth subcell, wherein each of the first and second graded interlayers is composed, respectively, of a compositionally step-graded series of (InxGa1-x)yAl1-yAs layers with monotonically changing lattice constant, with x and y selected such that the band gap of each interlayer remains constant throughout its thickness, and wherein 0