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Proceedings Paper

Improving the light-harvesting of second generation solar cells with photochemical upconversion
Author(s): Yuen Yap Cheng; Burkhard Fückel; Tim Schulze; Rowan W. MacQueen; Murad J. Y. Tayebjee; Andrew Danos; Tony Khoury; Raphaël G. C. R. Clady; N. J. Ekins-Daukes; Maxwell J. Crossley; Bernd Stannowski; Klaus Lips; Timothy W. Schmidt
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Paper Abstract

Photovoltaics (PV) offer a solution for the development of sustainable energy sources, relying on the sheer abundance of sunlight: More sunlight falls on the Earth’s surface in one hour than is required by its inhabitants in a year. However, it is imperative to manage the wide distribution of photon energies available in order to generate more cost efficient PV devices because single threshold PV devices are fundamentally limited to a maximum conversion efficiency, the Shockley-Queisser (SQ) limit. Recent progress has enabled the production of c-Si cells with efficiencies as high as 25%,1 close to the limiting efficiency of ∼30%. But these cells are rather expensive, and ultimately the cost of energy is determined by the ratio of system cost and efficiency of the PV device. A strategy to radically decrease this ratio is to circumvent the SQ limit in cheaper, second generation PV devices. One promising approach is the use of hydrogenated amorphous silicon (a-Si:H), where film thicknesses on the order of several 100nm are sufficient. Unfortunately, the optical threshold of a-Si:H is rather high (1.7-1.8 eV) and the material suffers from light-induced degradation. Thinner absorber layers in a-Si:H devices are generally more stable than thicker films due to the better charge carrier extraction, but at the expense of reduced conversion efficiencies, especially in the red part of the solar spectrum (absorption losses). Hence for higher bandgap materials, which includes a-Si as well as organic and dye-sensitized cells, the major loss mechanism is the inability to harvest low energy photons.

Paper Details

Date Published: 27 September 2012
PDF: 3 pages
Proc. SPIE 8477, Organic Photovoltaics XIII, 84770X (27 September 2012); doi: 10.1117/12.945217
Show Author Affiliations
Yuen Yap Cheng, The Univ. of Sydney (Australia)
Burkhard Fückel, The Univ. of Sydney (Australia)
Tim Schulze, The Univ. of Sydney (Australia)
Rowan W. MacQueen, The Univ. of Sydney (Australia)
Murad J. Y. Tayebjee, The Univ. of Sydney (Australia)
Andrew Danos, The Univ. of Sydney (Australia)
Tony Khoury, The Univ. of Sydney (Australia)
Raphaël G. C. R. Clady, The Univ. of Sydney (Australia)
N. J. Ekins-Daukes, Imperial College London (United Kingdom)
Maxwell J. Crossley, The Univ. of Sydney (Australia)
Bernd Stannowski, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (Germany)
Klaus Lips, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (Germany)
Timothy W. Schmidt, The Univ. of Sydney (Australia)

Published in SPIE Proceedings Vol. 8477:
Organic Photovoltaics XIII
Zakya H. Kafafi; Christoph J. Brabec; Paul A. Lane, Editor(s)

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