Thermoelectric properties of polysilicon inverse opals

Ma, Jun

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https://hdl.handle.net/2142/31007 Copy

Description

Title

Thermoelectric properties of polysilicon inverse opals

Author(s)

Ma, Jun

Issue Date

2012-05-22T00:21:13Z

Director of Research (if dissertation) or Advisor (if thesis)

Sinha, Sanjiv

Department of Study

Mechanical Sci & Engineering

Discipline

Mechanical Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Thermoelectrics
• Inverse opal

Abstract

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.

Graduation Semester

2012-05

Permalink

http://hdl.handle.net/2142/31007

Copyright and License Information

Copyright 2012 Jun Ma

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