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

 
: Braun, A.; Hirsch, B.; Katz, E.A.; Gordon, J.M.; Guter, W.; Bett, A.W.

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Solar energy materials and solar cells 93 (2009), No.9, pp.1692-1695
ISSN: 0927-0248
English
Journal Article
Fraunhofer ISE ()
III-V-Solarzellen

Abstract
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 10(2)-10(3) mA/mm(2). 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.

: http://publica.fraunhofer.de/documents/N-103728.html