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

We report static and time-resolved terahertz (THz) conductivity measurements of a high- performance 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...

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Hauptverfasser: Heyman, James N, Sahu, Ayaskanta, Coates, Nelson E, Ehmann, Brittany, Urban, Jeffery J
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Sprache:eng
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Zusammenfassung:We report static and time-resolved terahertz (THz) conductivity measurements of a high- performance 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 {\sigma}(TeNW/PD) = 160 S/cm and {\sigma}(TeNW/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.
DOI:10.48550/arxiv.1411.5914