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oai:www.ideals.illinois.edu:2142/31007 2023-07-10 col_2142_14787 col_2142_5131 com_2142_9630 com_2142_234 com_2142_5130

Sinha, Sanjiv Ma, Jun 2012-05-22T00:21:13Z 2012-05-22T00:21:13Z 2012-05 2012-05-22T00:21:13Z 2012-05 Nanostructured single-crystal silicon exhibits a remarkable increase in the gure of merit for thermoelectric energy conversion. Here we theoretically and experimentally(partial) investigate a similar enhancement for polycrystalline silicon structured as an inverse opal. An inverse opal provides nanoscale grains and a thin- lm like geometry to scatter phonons preferentially over electrons. Using solutions to the Boltzmann transport equation for electrons and phonons, we show that the gure of merit at 300 K is fteen times that of bulk single-crystal silicon. Our models predict that grain boundaries are more e ective than surfaces in enhancing the figure of merit. We provide insight into this e ect and show that preserving a grain size smaller than the shell thickness of the inverse opal increases the gure of merit by as much as 50% when the ratio between the two features is a third. At 600 K, the figure of merit is as high as 0.6 for a shell thickness of 10 nm. We also measured the thermal conductivity of such nanostructures, and a more accurate thermal transport model is provided based on the experimental results. Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2012-04-21T16:31:31Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Ma_Jun.pdf: 1958280 bytes, checksum: 7725536eeed32fb7f60197ea8e915d2b (MD5) Made available in DSpace on 2012-05-22T00:21:13Z (GMT). No. of bitstreams: 2 Ma_Jun.pdf: 1958280 bytes, checksum: 7725536eeed32fb7f60197ea8e915d2b (MD5) license.txt: 4054 bytes, checksum: 4ff96740593c3dca1de259e8f9033284 (MD5) http://hdl.handle.net/2142/31007 en Copyright 2012 Jun Ma Thermoelectrics Inverse opal Thermoelectric properties of polysilicon inverse opals text Mechanical Sci & Engineering 1917 Mechanical Engineering 0133 University of Illinois at Urbana-Champaign Thesis M.S. PHD:Mechanical Enginerng -UIUC 10KS0133PHD