NOVELTY - The multijunction solar cell comprises a first subcell comprising gallium-indium-nitrogen-arsenide-antimony, a second subcell overlying the first subcell to form the multijunction solar cell, and a substrate underlying the first subcell. The first subcell is characterized by a short circuit current of greater than 13 mA/cm2 and an open circuit voltage of greater than 0.3 V when illuminated with a filtered 1 sun AM1.5D spectrum in which all light having an energy greater than the bandgap of gallium arsenide is blocked.    USE - Used Multijunction solar cell.    ADVANTAGE - The multijunction solar cell has high efficiency and open circuit voltage, and improved performance.    DETAILED DESCRIPTION - The multijunction solar cell comprises a first subcell comprising gallium-indium-nitrogen-arsenide-antimony (Ga1-xInxNyAs1-y-zSbz), where the content levels are selected to achieve a bandgap of 0.9-1.1 eV, x is 0.07-0.18, y is 0.025-0.04 and z is 0.001-0.02, a second subcell overlying the first subcell to form the multijunction solar cell, and a substrate underlying the first subcell. The first subcell is characterized by: a short circuit current of greater than 13 mA/cm2 and an open circuit voltage of greater than 0.3 V when illuminated with a filtered 1 sun AM1.5D spectrum in which all light having an energy greater than the bandgap of gallium arsenide is blocked; and a lattice constant that is within 0.5% of the lattice constant of the second subcell when fully relaxed. The first subcell is lattice matched to the substrate. The first subcell is not a current-limiting subcell upon illumination of the multijunction solar cell using the AM1.5D spectrum. The first subcell is characterized by a thickness of greater than 1 mu m.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic cross-sectional view of a four junction solar cell.    Aluminum-indium-gallium-phosphide subcell (16)    Indium-gallium-arsenide subcell (18)    Tunnel junction (20)    Solar cell (100)    Germanium subcell. (140)