Four Junction Inverted Metamorphic Multijunction Solar Cell with Two Metamorphic Layers

Abstract

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

Description

REFERENCE TO RELATED APPLICATIONS[0001]This application is related to co-pending U.S. patent application Ser. No. 12 / 267,812 filed Nov. 10, 2008.[0002]This application is related to co-pending U.S. patent application Ser. No. 12 / 258,190 filed Oct. 24, 2008.[0003]This application is related to co-pending U.S. patent application Ser. No. 12 / 253,051 filed Oct. 16, 2008.[0004]This application is related to co-pending U.S. patent application Ser. No. 12 / 190,449, filed Aug. 12, 2008.[0005]This application is related to co-pending U.S. patent application Ser. No. 12 / 187,477, filed Aug. 7, 2008.[0006]This application is related to co-pending U.S. patent application Ser. No. 12 / 218,582 filed Jul. 16, 2008.[0007]This application is related to co-pending U.S. patent application Ser. No. 12 / 218,558 filed Jul. 16, 2008.[0008]This application is related to co-pending U.S. patent application Ser. No. 12 / 123,864 filed May 20, 2008.[0009]This application is related to co-pending U.S. patent applicat...

AI Technical Summary

Problems solved by technology

Compared to silicon, III-V compound semiconductor multijunction devices have greater energy conversion efficiencies and generally more radiation resistance, although they tend to be more complex to manufacture.

However, the materials and structures for a number of different layers of the cell proposed and described in such reference present a number of practical difficulties relating to the appropriate choice of materials and fabrication steps.

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