Photon management in thermal and solar photovoltaics

Photovoltaics is a technology that directly converts photon energy into electrical energy. Depending on the photon source, photovoltaic systems can be categorized into two groups: solar photovoltaics (PV) and thermophotovoltaics (TPV). In solar photovoltaic systems, the photon source is the sun, whereas in thermophotovoltaic systems the photons are from artificially designed thermal emitters that operate at a lower temperature. The differences in the photon sources lead to different research emphases on the two photovoltaic systems in this work. This thesis investigates ways to control photon emission and absorption for solar energy and TPV applications. Several topics are discussed, including photon transport in multilayer structures, measurement of near-field thermal radiation, optical absorption in silicon nanowire structures, surface-plasmon enhanced near-bandgap optical absorption in silicon, and selective absorber surface for solar thermal applications. For thermophotovoltaic systems, the work is focused on thermal emission and photon transport. The study of photon transport in multilayer structures is presented. Results based on wave-optics and ray tracing methods are compared. The analysis shows that for structures contain a large number of layers, the coherence length of the emitting source is no longer a valid criterion to indicate whether ray tracing method is valid. Instead, wave inference effects always play a role. The effects of photon localization are also discussed. Surface-mode enhanced near-field thermal radiation is explored in this work as an effective way to tailor the thermal emission for TPV systems. Calculations based on fluctuation-dissipation theorem and Maxwell's equations are presented to study radiative heat transfer between two closely-spaced glass plates. The theoretical analysis shows that the radiative heat transfer between closely-spaced glass plates is enhanced by surface phonon polaritions and the flux can exceed the far-field upper-limit imposed by Planck's law of blackbody radiation.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2008

Author dc:creator

• Hu, Lu

Advisor dc:contributor.advisor

• Gang Chen.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/46496

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/46496