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p-n junction heterostructure device physics model of a four junction solar cell

Griggs, Melissa J. and Kayes, Brendan M. and Atwater, Harry A. (2006) p-n junction heterostructure device physics model of a four junction solar cell. In: High and Low Concentration for Solar Electric Applications. Proceedings of SPIE. No.6339. Society of Photo-optical Instrumentation Engineers (SPIE) , Bellingham, WA, Art. No. 63390D.

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We present results from a p-n junction device physics model for GaInP/GaAs/GaInAsP/GaInAs four junction solar cells. The model employs subcells whose thicknesses have an upper bound of 5μm and lower bound of 200nm, which is just above the fully depleted case for the assumed doping of N_A = 1 x 10^(18) cm^(-3) and N_D = 1 x 10^(17) cm^(-3). The physical characteristics of the cell model include: free carrier absorption, temperature and doping effects on carrier mobility, as well as recombination via Shockley-Read-Hall recombination from a single midgap trap level and surface recombination. Upper bounds on cell efficiency set by detailed balance calculations can be approached by letting the parameters approach ideal conditions. However whereas detailed balance calculations always benefit from added subcells, the current matching requirements for series connected p-n multi-junctions indicate a minimum necessary performance from an added subcell to yield a net increase in overall device efficiency. For the four junction cell considered here, optimizing the subcell thickness is an important part of optimizing the efficiency. Series resistance limitations for concentrator applications can be systematically explored for a given set of subcells. The current matching limitation imposed by series connection reduces efficiency relative to independently-connected cells. The overall trend indicates an approximately 5% drop in efficiency for series connected cells relative to identical independently connected cells. The series-connected devices exhibit a high sensitivity to spectral changes and individual subcell performance. If any single subcell within the series-connected device is degraded relative to its optimal design, the entire device is severely hindered. This model allows complex heterostructure solar cell structures to be evaluated by providing device physics-based predictions of performance limitations.

Item Type:Book Section
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Atwater, Harry A.0000-0001-9435-0201
Additional Information:© 2006 Society of Photo-Optical Instrumentation Engineers (SPIE). This work was supported by the High Performance Photovoltaic Program of the National Renewable Energy Laboratory under subcontract XAT-4-33624-10. One of us (MJG) acknowledges the National Science Foundation for a Graduate Research Fellowship as well as J. Dionne and M. Kelzenberg for many discussions on implementation.
Funding AgencyGrant Number
National Renewable Energy LaboratoryXAT-4-33624-10
NSF Graduate Research FellowshipUNSPECIFIED
Subject Keywords:Multi-junction; solar cells; modeling; device physics
Series Name:Proceedings of SPIE
Issue or Number:6339
Record Number:CaltechAUTHORS:20180706-142129738
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Official Citation:Melissa J. Griggs, Brendan M. Kayes, Harry A. Atwater, "p-n junction heterostructure device physics model of a four junction solar cell", Proc. SPIE 6339, High and Low Concentration for Solar Electric Applications, 63390D (2 October 2006); doi: 10.1117/12.680793;
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:87612
Deposited By: George Porter
Deposited On:09 Jul 2018 15:19
Last Modified:15 Nov 2021 20:50

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