An alloy having a large band gap range is used in a multijunction solar cell to enhance utilization of the solar energy spectrum. In one embodiment, the alloy is In.sub.1-xGa.sub.xN having an energy bandgap range of approximately 0.7 eV to 3.4 eV, providing a good match to the solar energy spectrum. Multiple junctions having different bandgaps are stacked to form a solar cell. Each junction may have different bandgaps (realized by varying the alloy composition), and therefore be responsive to different parts of the spectrum. The junctions are stacked in such a manner that some bands of light pass through upper junctions to lower junctions that are responsive to such bands.
The invention described herein was made with U.S. Government support under Grant Number DE-AC03-76SF00098 awarded by the U.S. Department of Energy, Grant Number N00014-99-1-0936 awarded by Office of Naval Research, and Grant Number DMR-0109844 awarded by the National Science Foundation. The United States Government has certain rights in the invention.