High-Efficiency Solar Cells Using Photonic-Bandgap Materials

Dowling, Jonathan; Lee, Hwang

Solar photovoltaic cells would be designed to exploit photonic-bandgap (PBG) materials to enhance their energy-conversion efficiencies, according to a proposal. Whereas the energy-conversion efficiencies of currently available solar cells are typically less than 30 percent, it has been estimated that the energy-conversion efficiencies of the proposed cells could be about 50 percent or possibly even greater. The primary source of inefficiency of a currently available solar cell is the mismatch between the narrow wavelength band associated with the semiconductor energy gap (the bandgap) and the broad wavelength band of solar radiation. This mismatch results in loss of power from both (1) long-wavelength photons, defined here as photons that do not have enough energy to excite electron-hole pairs across the bandgap, and (2) short-wavelength photons, defined here as photons that excite electron- hole pairs with energies much above the bandgap. It follows that a large increase in efficiency could be obtained if a large portion of the incident solar energy could be funneled into a narrow wavelength band corresponding to the bandgap. In the proposed approach, such funneling would be effected by use of PBG materials as intermediaries between the Sun and photovoltaic cells.

Document ID

20110015141

Acquisition Source

Jet Propulsion Laboratory

Document Type

Other - NASA Tech Brief

External Source(s)

http://www.techbriefs.com/index.php?option=com_staticxt&staticfile=/Briefs/Sep05/NPO_40662.html

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Date Acquired

August 25, 2013

Publication Date

September 1, 2005

Publication Information

Publication: NASA Tech Briefs, September 2005

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Report/Patent Number

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Public

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