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Proceedings Paper

Efficient Multijunction Monolithic Cascade Solar Cells
Author(s): C. R. Lewis; C. W. Ford; G. F. Virshup; H. F. MacMillan; R. T. Green; B. A. Arau; J. G. Werthen
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Paper Abstract

Efficient two-junction monolithic cascade solar cells have been fabricated in two dif-ferent III-V materials systems. The cells are grown by metalorganic chemical vapor deposi-tion (MOCVD). Two-junction efficiencies as high as 25% (1-sun, AM2) are projected from the individual GaInAs (1.15 eV) and A1GaAs (1.72 to 1.75 eV) subcell efficiencies obtained in a cascade configuration. Factors influencing actual cascade efficiency and reproducibility are discussed. Metal interconnection of the AlGaAs and GaInAs subcells during post-growth processing yields two-terminal cascades with power conversion efficiencies (n) as high as 13.6% at 1-sun, airmass two (AM2) , and 11.1% at 1-sun, airmass zero (AMO). Three-terminal AlGaAs (1.72 eV)/GaInAs (1.15 eV) cascades have shown 11 of 12.6% (1-sun, AMO). Alternatively, insertion of a novel high-conductance junction between the cascade subcells during the MOCVD growth of the structure reduces the complexity of processing to that required of a single-junction cell. Voltage addition has been demonstrated, with n of 10.0% (1-sun, AM2) in the AlGaAs (1.72 eV)/GaInAs (1.15 eV) system. The A1GaAs (1.72 eV)/GaAs lattice-matched pair allows demonstration of proof-of-concept structures; tunnel-junction-connected A1GaAs (1.72 eV)/ GaAs cascades show n as high as 13.9% at 1-sun, AM2, and three-terminal, two-junction A1GaAs (1.72 eV)/GaAs (1.42 eV) systems as high as 23.0% at 1-sun, AM2.

Paper Details

Date Published: 20 November 1986
PDF: 9 pages
Proc. SPIE 0706, Photovoltaics for Commercial Solar Power Applications, (20 November 1986); doi: 10.1117/12.937224
Show Author Affiliations
C. R. Lewis, Varian Research Center (United States)
C. W. Ford, Varian Research Center (United States)
G. F. Virshup, Varian Research Center (United States)
H. F. MacMillan, Varian Research Center (United States)
R. T. Green, Varian Research Center (United States)
B. A. Arau, Varian Research Center (United States)
J. G. Werthen, Varian Research Center (United States)

Published in SPIE Proceedings Vol. 0706:
Photovoltaics for Commercial Solar Power Applications
David Adler, Editor(s)

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