Localized irradiation effects on tunnel diode transitions in multi-junction concentrator solar cells

Avi Braun, Baruch Hirsch, Eugene A. Katz, Jeffrey M. Gordon, Wolfgang Guter, Andreas W. Bett

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


Multi-junction concentrator solar cells incorporate tunnel diodes that undergo a transition from high-conductance tunneling to low-conductance thermal diffusion behavior, typically at threshold current densities of the order of 102-103 mA/mm2. We present experimental evidence of a prominent heretofore unrecognized dependence of threshold current density on the degree of localized irradiation, in different solar cell architectures. We also show that solar cells with non-uniform metallization can exhibit an additional spatial dependence to the tunnel diode threshold current density. These previously undiscovered phenomena - which should be observable in all non-uniformly irradiated photovoltaic tunnel diodes - are interpreted as being derived from the lateral spreading of excess majority carriers (analogous to current spreading in light-emitting diodes (LEDs)). The consequences for concentrator photovoltaics are addressed.

Original languageEnglish
Pages (from-to)1692-1695
Number of pages4
JournalSolar Energy Materials and Solar Cells
Issue number9
StatePublished - 1 Sep 2009


  • Concentrator
  • Multi-junction
  • Photovoltaics
  • Solar
  • Tunnel diode

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films


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