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Carrier Lifetime Enhancement in a Tellurium Nanowire/PEDOT:PSS Nanocomposite by Sulfur Passivation

Published online by Cambridge University Press:  20 February 2015

James N. Heyman ,
Ayaskanta Sahu ,
Nelson E. Coates ,
Brittany Ehmann  and
Jeffery J. Urban
James N. Heyman
Affiliation:
Physics Department, Macalester College, St. Paul, MN 55105, USA
Ayaskanta Sahu
Affiliation:
The Molecular Foundry, Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
Nelson E. Coates
Affiliation:
The Molecular Foundry, Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
Brittany Ehmann
Affiliation:
Physics Department, Macalester College, St. Paul, MN 55105, USA
Jeffery J. Urban
Affiliation:
The Molecular Foundry, Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
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Abstract

We report static and time-resolved terahertz (THz) conductivity measurements of a highperformance thermoelectric material containing tellurium nanowires in a PEDOT:PSS matrix. Composites were made with and without sulfur passivation of the nanowires surfaces. The material with sulfur linkers (TeNW/PD-S) is less conductive but has a longer carrier lifetime than the formulation without (TeNW/PD). We find real conductivities at f = 1THz of σTeNW/PD = 160 S/cm and σTeNW/PD-S = 5.1 S/cm. These values are much larger than the corresponding DC conductivities, suggesting DC conductivity is limited by structural defects. The free-carrier lifetime in the nanowires is controlled by recombination and trapping at the nanowire surfaces. We find surface recombination velocities in bare tellurium nanowires (22m/s) and TeNW/PD-S (40m/s) that are comparable to evaporated tellurium thin films. The surface recombination velocity in TeNW/PD (509m/s) is much larger, indicating a higher interface trap density.

Keywords

thermoelectricelectrical propertiesTe
Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 1742: Symposium BB – Molecular, Polymer and Hybrid Materials for Thermoelectrics , 2015 , mrsf14-1742-bb04-02
Copyright
Copyright © Materials Research Society 2015 

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