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Proceedings Paper

III-V quantum dot enhanced photovoltaic devices
Author(s): David V. Forbes; Seth M. Hubbard; Christopher Bailey; Stephen Polly; John Andersen; Ryne Raffaelle
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Paper Abstract

State of the art photovoltaics exhibiting conversion efficiency in excess of 30% (1-sun) utilize epitaxially grown multijunction III-V materials. Increasing photovoltaic efficiency is critically important to the space power, and more recently, the terrestrial concentrator PV communities The use of nanostructured materials within photovoltaic devices can enable improved efficiency, potentially in excess of the Shockley-Queisser limit. The addition of nanostructures such as quantum dots (QDs) to photovoltaic devices allows one to extend the absorption spectrum of the solar cell and "tune" the bandgap to the spectral conditions. Multi-junction (MJ) solar cells would benefit from the additional short-circuit current within the middle current-limiting (In)GaAs cell via QD spectral tuning. While QD tuning is a potentially direct approach to increased efficiency of MJ solar cells, it has been reported that significant improvements can be achieved using QDs to form an intermediate band within the bandgap of a suitable matrix. We will discuss the potential for QD photovoltaic devices and examine the challenges associated with multi-junction device growth with the inclusion of quantum dot arrays. GaAs p-i-n solar cells, with and without InAs QD superlattices are used to demonstrate the potential benefits of QDs. The unique challenges associated with the characterization of this type of device will also be presented. Using strain-balanced Stranski-Krastanov QD formation, we have demonstrated sub-gap photon collection and increased current in QD-enhanced GaAs solar cells containing up to 100 periods. Finally, we will discuss the opportunities that these devices hold for high photovoltaic conversion efficiency.

Paper Details

Date Published: 24 August 2010
PDF: 10 pages
Proc. SPIE 7772, Next Generation (Nano) Photonic and Cell Technologies for Solar Energy Conversion, 77720C (24 August 2010); doi: 10.1117/12.863142
Show Author Affiliations
David V. Forbes, Rochester Institute of Technology (United States)
Seth M. Hubbard, Rochester Institute of Technology (United States)
Christopher Bailey, Rochester Institute of Technology (United States)
Stephen Polly, Rochester Institute of Technology (United States)
John Andersen, Rochester Institute of Technology (United States)
Ryne Raffaelle, National Renewable Energy Lab. (United States)

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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