High Efficiency c-Silicon Solar Cells Based on Micro-nanoscale Structure

Report No. ARL-TR-5576
Authors: Fred Semendy, Priyalal Wijewarnasuriya, and Nibir K. Dhar
Date/Pages: June 2011; 24 pages
Abstract: This report describes our aim to develop high-efficiency crystalline silicon (c-Si) solar cells with increased power conversion efficiency (>30%) in order to reduce solar array mass, stowed volume, and cost. Our approach is based upon increasing the electrical junction area per unit volume using microblock design and fabrication. Current thin-film and c-Si solar cells have a limited conversion efficiency of 10-20% and cost $3-$5/W-peak and state-of-the-art crystalline multijunction solar cells have a ~30% efficiency and cost $30-$40/W-peak. Increasing the conversion efficiency to >30% enables a reduction in cost to <$1/W-peak, making the cells viable as power platforms supporting mobile wireless, laptops, residential, and commercial applications. To do this, we are moving from a two-dimensional standard flat cell to three-dimensional blocks of cells. Incorporating nanoscaled blocks in solar cell structures enhances the performances by (1) increasing the surface area-to-volume ratio; (2) bringing the junction closer to the carrier generation region, which eliminates carrier recombination; (3) increasing absorption of all incident photon flux; and (4) broadening the absorption spectrum. We have achieved a >20 times greater short-circuit current than conventional structures. We have also modeled the proposed structure to simulate key performance parameters so that they can be incorporated into the design and fabrication of the device.
Distribution: Approved for public release
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Last Update / Reviewed: June 1, 2011