Light absorption and emission in nanowire array solar cells

Kupec J, Stoop RL, Witzigmann B (2010)

Publication Type: Journal article

Publication year: 2010

Journal

Optics Express Optical Society of America

Book Volume: 18

Pages Range: 27589-27605

Journal Issue: 26

DOI: 10.1364/OE.18.027589

Abstract

Inorganic nanowires are under intense research for large scale solar power generation intended to ultimately contribute a substantial fraction to the overall power mix. Their unique feature is to allow different pathways for the light absorption and carrier transport. In this publication we investigate the properties of a nanowire array acting as a photonic device governed by wave-optical phenomena. We solve the Maxwell equations and calculate the light absorption efficiency for the AM1.5d spectrum and give recommendations on the design. Due to concentration of the incident sunlight at a microscopic level the absorptivity of nanowire solar cells can exceed the absorptivity of an equal amount of material used in thin-film devices. We compute the local density of photon states to assess the effect of emission enhancement, which influences the radiative lifetime of excess carriers. This allows us to compute the efficiency limit within the framework of detailed balance. The efficiency is highly sensitive with respect to the diameter and distance of the nanowires. Designs featuring nanowires below a certain diameter will intrinsically feature low short-circuit current that cannot be compensated even by increasing the nanowire density. Optimum efficiency is not achieved in densely packed arrays, in fact spacing the nanowires further apart (simultaneously decreasing the material use) can even improve efficiency in certain scenarios. We observe absorption enhancement reducing the material use. In terms of carrier generation per material use, nanowire devices can outperform thin-film devices by far. © 2010 Optical Society of America.

Authors with CRIS profile

Bernd Witzigmann

Involved external institutions

Eidgenössische Technische Hochschule Zürich (ETHZ) / Swiss Federal Institute of Technology in Zurich CH Switzerland (CH) Universität Kassel DE Germany (DE)

How to cite

APA:

Kupec, J., Stoop, R.L., & Witzigmann, B. (2010). Light absorption and emission in nanowire array solar cells. Optics Express, 18(26), 27589-27605. https://dx.doi.org/10.1364/OE.18.027589

MLA:

Kupec, Jan, Ralph L. Stoop, and Bernd Witzigmann. "Light absorption and emission in nanowire array solar cells." Optics Express 18.26 (2010): 27589-27605.

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