Quadruple-Junction Inverted Metamorphic Concentrator Devices

Ryan M. France, John F. Geisz, Ivan Garcia, Myles A. Steiner, William E. McMahon, Daniel J. Friedman, Tom E. Moriarty, Carl Osterwald, J. Scott Ward, Anna Duda, Michelle Young, Waldo J. Olavarria

Research output: Contribution to journalArticlepeer-review

104 Scopus Citations

Abstract

We present results for quadruple-junction inverted metamorphic (4J-IMM) devices under the concentrated direct spectrum and analyze the present limitations to performance. The devices integrate lattice-matched subcells with rear heterojunctions, as well as lattice-mismatched subcells with low threading dislocation density. To interconnect the subcells, thermally stable lattice-matched tunnel junctions are used, as well as a metamorphic GaAsSb/GaInAs tunnel junction between the lattice-mismatched subcells. A broadband antireflection coating is used, as well as a front metal grid designed for high concentration operation. The best device has a peak efficiency of ( 43.8 \pm 2.2)% at 327-sun concentration, as measured with a spectrally adjustable flash simulator, and maintains an efficiency of (42.9 \pm 2.1 )% at 869 suns, which is the highest concentration measured. The {\bf V}\!-{{\bf oc}} increases from 3.445 V at 1-sun to 4.10 V at 327-sun concentration, which indicates high material quality in all of the subcells. The subcell voltages are analyzed using optical modeling, and the present device limitations and pathways to improvement are discussed. Although further improvements are possible, the 4J-IMM structure is clearly capable of very high efficiency at concentration, despite the complications arising from utilizing lattice-mismatched subcells.

Original languageAmerican English
Article number6945794
Pages (from-to)432-437
Number of pages6
JournalIEEE Journal of Photovoltaics
Volume5
Issue number1
DOIs
StatePublished - 2015

Bibliographical note

Publisher Copyright:
© 2011-2012 IEEE.

NREL Publication Number

  • NREL/JA-5J00-61331

Keywords

  • III-V
  • Metamorphic
  • multijunction

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