Six-Junction Concentrator Solar Cells

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24 Scopus Citations


We report on six-junction inverted metamorphic (6J IMM) solar cells developed for concentrator applications. Monolithic III-V structures are grown by metal organic vapor phase epitaxy with junction bandgaps of 2.06, 1.70, 1.40, 1.16, 0.94, and 0.70 eV. The top three junctions are lattice-matched to the GaAs substrate, but the bottom three junctions use three consecutive metamorphic compositionally graded buffers to transition the lattice constant to GaxIn1-xAs compositions with the previously listed bandgaps. Performance of 6J IMM devices at one-sun AM1.5 Direct conditions gives VOC = 5.301 V, JSC = 8.05 mA/cm2, fill factor=83.9%, and efficiency=35.8%. Promising operation at high concentration is achieved but the spectrum was not controlled to AM1.5D. Tunnel junctions do not limit until at least several hundred suns. High concentration performance appears to be limited by internal heterojunction barriers created by zinc diffusion that decreases the fill factor. The properties of each junction within the 6J IMM have been separately characterized through electroluminescence and luminescent coupling measurements.

Original languageAmerican English
Number of pages7
StatePublished - 13 Sep 2018
Event14th International Conference on Concentrator Photovoltaic Systems, CPV 2018 - Puertollano, Spain
Duration: 16 Apr 201818 Apr 2018


Conference14th International Conference on Concentrator Photovoltaic Systems, CPV 2018

Bibliographical note

Publisher Copyright:
© 2018 Author(s).

NREL Publication Number

  • NREL/CP-5900-71300


  • bandgaps
  • concentrators
  • junction
  • solar cells


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