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Proceedings Paper

Impact of photon recycling and luminescence coupling in III-V photovoltaic devices
Author(s): A. W. Walker; O. Höhn; D. N. Micha; L. Wagner; H. Helmers; A. W. Bett; F. Dimroth
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Paper Abstract

Single junction photovoltaic devices composed of direct bandgap III-V semiconductors such as GaAs can exploit the effects of photon recycling to achieve record-high open circuit voltages. Modeling such devices yields insight into the design and material criteria required to achieve high efficiencies. For a GaAs cell to reach 28 % efficiency without a substrate, the Shockley-Read-Hall (SRH) lifetimes of the electrons and holes must be longer than 3 s and 100 ns respectively in a 2 μm thin active region coupled to a very high reflective (>99%) rear-side mirror. The model is generalized to account for luminescence coupling in tandem devices, which yields direct insight into the top cell’s non-radiative lifetimes. A heavily current mismatched GaAs/GaAs tandem device is simulated and measured experimentally as a function of concentration between 3 and 100 suns. The luminescence coupling increases from 14 % to 33 % experimentally, whereas the model requires an increasing SRH lifetime for both electrons and holes to explain these experimental results. However, intermediate absorbing GaAs layers between the two sub-cells may also increasingly contribute to the luminescence coupling as a function of concentration.

Paper Details

Date Published: 16 April 2015
PDF: 10 pages
Proc. SPIE 9358, Physics, Simulation, and Photonic Engineering of Photovoltaic Devices IV, 93580A (16 April 2015); doi: 10.1117/12.2084508
Show Author Affiliations
A. W. Walker, Fraunhofer Institute for Solar Energy Systems ISE (Germany)
O. Höhn, Fraunhofer Institute for Solar Energy Systems ISE (Germany)
D. N. Micha, Fraunhofer Institute for Solar Energy Systems ISE (Germany)
L. Wagner, Fraunhofer Institute for Solar Energy Systems ISE (Germany)
H. Helmers, Fraunhofer Institute for Solar Energy Systems ISE (Germany)
A. W. Bett, Fraunhofer Institute for Solar Energy Systems ISE (Germany)
F. Dimroth, Fraunhofer Institute for Solar Energy Systems ISE (Germany)


Published in SPIE Proceedings Vol. 9358:
Physics, Simulation, and Photonic Engineering of Photovoltaic Devices IV
Alexandre Freundlich; Jean-François Guillemoles; Masakazu Sugiyama, Editor(s)

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