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Proceedings Paper

Quantifying intrinsic loss mechanisms in solar cells: Why is power efficiency fundamentally limited?
Author(s): Louise C. Hirst; Nicholas J. Ekins-Daukes
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Paper Abstract

Intrinsic loss mechanisms are quantified for a single junction device under one sun illumination. Thermalisation, below Eg and Boltzmann losses are shown to be the dominant loss mechanisms in a device with Eg = 1.31eV , accounting for 30%, 25% and 9% of the incident solar radiation respectively. Alternative device designs which target these dominant intrinsic losses are considered. Concentrator (and restricted emission) devices target Boltzmann loss. This loss mechanism is shown to have a logarithmic relationship with concentration and as such, a small increase in absorption solid angle equates to a large increase in fundamental limiting efficiency. A multi-junction device resolves the mismatch between the broad solar spectrum and single threshold absorption, and thus targets below Eg and thermalisation losses. A greater number of junctions allows the device absorption profile to better match the solar spectrum, increasing device efficiency. Boltzmann loss slightly increases with junction number and as such, concentration will be proportionally more effective at increasing efficiency in a multi-junction device. A hot carrier device targets thermalisation loss. This loss mechanism is eliminated in the impact ionisation model used in this paper, allowing for enhanced device efficiency. ----- The on-screen and audio presentation of this paper can be played by clicking the multimedia PDF link at the bottom right hand of this page.

Paper Details

Date Published: 24 August 2010
PDF: 6 pages
Proc. SPIE 7772, Next Generation (Nano) Photonic and Cell Technologies for Solar Energy Conversion, 777211 (24 August 2010); doi: 10.1117/12.860681
Show Author Affiliations
Louise C. Hirst, Imperial College London (United Kingdom)
Nicholas J. Ekins-Daukes, Imperial College London (United Kingdom)

Published in SPIE Proceedings Vol. 7772:
Next Generation (Nano) Photonic and Cell Technologies for Solar Energy Conversion
Loucas Tsakalakos, Editor(s)

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