Thermoelectric properties of polysilicon inverse opals

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.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2012

Author dc:creator

• Ma, Jun

Contributors dc:contributor

• Sinha, Sanjiv

• Thermoelectrics
• Inverse opal

Statement dc:rights

• Copyright 2012 Jun Ma

Language dc:language

en

Handle dc:identifier

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

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/31007