High-efficiency space and terrestrial multijunction solar cells through bandgap control in cell structures

Richard King, Chris M. Fetzer, Peter C. Colter, Ken M. Edmondson, James H. Ermer, Hector L. Cotal, Hojun Yoon, Alex P. Stavrides, Geoff Kinsey, Dimitri D. Krut, N. H. Karam

Research output: Chapter in Book/Report/Conference proceedingConference contribution

92 Scopus citations


Using the energy bandgap of semiconductors as a design parameter is critically important for achieving the highest efficiency multijunction solar cells. The bandgaps of lattice-matched semiconductors that are most convenient to use are rarely those which would result in the highest theoretical efficiency. For both the space and terrestrial solar spectra, the efficiency of 3-junction GalnP/GaAs/Ge solar cells can be increased by a lower bandgap middle cell, as for GalnAs middle cells, as well as by using higher bandgap top cell materials. Wide-bandgap and indirect-gap materials used in parasitically absorbing layers such as tunnel junctions help to increase transmission of light to the active cell layers beneath. Control of bandgap in such cell structures has been instrumental in achieving solar cell efficiencies of 29.7% under the AMD space spectrum (0.1353 W/cm2, 28°C) and 34% under the concentrated terrestrial spectrum (AM1.5G, 150-400 suns, 25°C), the highest yet achieved for solar cells built on a single substrate.

Original languageEnglish (US)
Title of host publicationConference Record of the IEEE Photovoltaic Specialists Conference
Number of pages6
StatePublished - 2002
Externally publishedYes
Event29th IEEE Photovoltaic Specialists Conference - New Orleans, LA, United States
Duration: May 19 2002May 24 2002


Other29th IEEE Photovoltaic Specialists Conference
Country/TerritoryUnited States
CityNew Orleans, LA

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Condensed Matter Physics


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