Abstract
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 language | American English |
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Number of pages | 7 |
DOIs | |
State | Published - 13 Sep 2018 |
Event | 14th International Conference on Concentrator Photovoltaic Systems, CPV 2018 - Puertollano, Spain Duration: 16 Apr 2018 → 18 Apr 2018 |
Conference
Conference | 14th International Conference on Concentrator Photovoltaic Systems, CPV 2018 |
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Country/Territory | Spain |
City | Puertollano |
Period | 16/04/18 → 18/04/18 |
Bibliographical note
Publisher Copyright:© 2018 Author(s).
NREL Publication Number
- NREL/CP-5900-71300
Keywords
- bandgaps
- concentrators
- junction
- solar cells