The fabrication of flexible and large‐size inverted metamorphic five‐junction solar cells

Abstract

AbstractThe inverted metamorphic AlGaInP/AlGaAs/GaAs/InGaAs/InGaAs five‐junction solar cells with the bandgap energies of 2.0/1.67/1.42/1.18/0.83 eV were grown by metal–organic chemical vapor deposition on GaAs substrates. The mismatch stress between the two bottom (In0.17Ga0.83As and In0.46Ga0.54As) cells and GaAs substrate was nearly fully relaxed owing to the growth of AlInGaAs compositionally step‐graded buffers. By employing the low‐temperature epilayer transfer technology with only one‐time temporary bonding, the flexible five‐junction solar cells with the size of 12 cm2 were successfully fabricated. The conversion efficiency was 35.1% with the open‐circuit voltage of 4.73 V under AM1.5G spectrum. The excellent performance of the large‐size five‐junction solar cells is attributed to the low amount of mismatch dislocations in the material as well as the simple fabrication process of the flexible device.