Paper
27 September 2012 Improving the light-harvesting of second generation solar cells with photochemical upconversion
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
Author Affiliations +
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.
© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
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, and Timothy W. Schmidt "Improving the light-harvesting of second generation solar cells with photochemical upconversion", Proc. SPIE 8477, Organic Photovoltaics XIII, 84770X (27 September 2012); https://doi.org/10.1117/12.945217
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KEYWORDS
Solar cells

Solar energy

Upconversion

Photovoltaics

Amorphous silicon

External quantum efficiency

Absorption

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