Recent progress of High-Efficiency III-V multijunction Solar Cells

High-Efficiency III-V multijunction Solar Cells are being developed at Shanghai Solar Energy Research Center (SSRC) for use in space applications. Recently, Inverted Metamorphic (IMM) 3-Junction cells achieved a 1-sun, AM0 conversion efficiency of 31.88% with an open-circuit-voltage of 2.978V, a short-circuit current-density of 16.94 mA/cm², and a fill factor of 0.863. In addition, GaInP/GaAs/InGaAsP/InGaAs 4-junction solar cells have been prepared by direct wafer bonding (DWB) technique after the epitaxial growth of GaInP/GaAs heterojunction on GaAs substrate and InGaAsP/InGaAs heterojunction on InP substrate, respectively. Moreover, antireflection coating (ARC) has been studied over the range of 300 nm to 1700 nm for 4J solar cells in order to reduce the front surface reflectivity. The latest status of the semiconductor-bonded 4J solar cells and the antireflection coating will also be discussed.