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20 August 2009 Fundamentally new aspects of tunnel diode transitions in multi-junction photovoltaics
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Tunnel diodes constitute an essential part of multi-junction concentrator photovoltaics. These tunnel junctions exhibit a transition from low-resistance tunneling to high-resistance thermal diffusion, commonly at current densities of the order of 102-103 mA/mm2. Experimental evidence of a fundamentally new effect is reported and confirmed in distinct cell architectures: the dependence of the threshold current density on the extent of localized irradiation. It is also shown that photovoltaic cells with a non-uniform metal grid can possess an additional spatial dependence to the threshold current density. These new phenomena should be observable in all solar cell tunnel diodes subjected to inhomogeneous illumination, and are posited to stem from the lateral spreading of excess majority carriers (similar to current spreading in LEDs). The implications for concentrator solar cells are also addressed.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Avi Braun, Baruch Hirsch, Eugene A. Katz, Jeffrey M. Gordon, Wolfgang Guter, and Andreas W. Bett "Fundamentally new aspects of tunnel diode transitions in multi-junction photovoltaics", Proc. SPIE 7407, High and Low Concentrator Systems for Solar Electric Applications IV, 74070C (20 August 2009);

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