Enhanced Thermoelectric Metrics in Ultra-long Electrodeposited PEDOT Nanowires

• Published in: Nano letters Vol. 11; no. 1; pp. 125 - 131
• Main Authors: Taggart, David K, Yang, Yongan, Kung, Sheng-Chin, McIntire, Theresa M, Penner, Reginald M
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 12.01.2011
• Subjects: Chemical synthesis methods; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in multilayers, nanoscale materials and structures; Exact sciences and technology; Materials science; Methods of nanofabrication; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Physics; Quantum wires; Seebeck coefficient; electropolymerization; nanopatterning; lithography; conductive polymer; Electrical conductivity; Thermocouples; Template reaction; Seebeck effect; Thin films; Thermoelectric materials; Thiophene derivative polymer; Electron mobility; Electrodeposition; Thiophene polymer; Nanowires; Electrodeposited coatings; Arrays; Carrier density; Nanostructured materials; Nanomaterial synthesis
• DOI: 10.1021/nl103003d
• ISSN: 1530-6984; 1530-6992

The Seebeck coefficient, S, and the electrical conductivity, σ, of electrodeposited poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires and thin films are reported. PEDOT nanowires were prepared by electropolymerizing 3,4-ethylenedioxythiophene (EDOT) in aqueous LiClO4 within a template prepared using the lithographically patterned nanowire electrodeposition (LPNE) process. These nanowires were 40−90 nm in thickness, 150−580 nm in width, and 200 μm in length. σ and S were measured from 190 K to 310 K by fabricating heaters and thermocouples on top of arrays of 750 PEDOT nanowires. Such PEDOT nanowire arrays consistently produced S values that were higher than those for PEDOT films: up to −122 μV/K (310 K) for nanowires and up to −57 μV/K (310 K) for films. The sample-to-sample variation in S for 14 samples of PEDOT nanowires and films, across a wide range of critical dimensions, is fully explained by variations in the carrier concentrations in accordance with the Mott equation. In spite of their higher |S| values, PEDOT nanowires also had higher σ than films, on average, because electron mobilities were greater in nanowires by a factor of 3.