ICT2014 Abstracts

Recently, thiophene-based polymers have attracted the attention of researchers investigating organic materials with high thermoelectric figure of merit for applications to environmental and economical energy conversion [1, 2]. We reported the preparation of films consisting of a complex of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid (PEDOT:PSS) on a flexible polyimide substrate and the investigation of their flexibility and thermal stability with respect to thermoelectric properties [3]. In this study, we investigated the thermoelectric properties of cast films of PEDOT:PSS with different thicknesses on a polyimide substrate. We also fabricated in-plane film devices consisting of five pairs of PEDOT:PSS and silver electrode and measured the output power characteristics of the film devices with different thicknesses. The Seebeck coefficient and the electrical conductivity for a PEDOT:PSS film with the thickness of approximately 20 μm on polyimide substrate were approximately 15 μV/K and approximately 500 S/cm, respectively, near room temperature. The electrical conductivity monotonically increased up to 1200 S/cm as the film thickness decreased to approximately 3 μm, while the Seebeck coefficient was almost constant, independently of the film thickness. The maximum electric power for a in-plane PEDOT:PSS film device with the thickness of 10 μm was 1.3 μW at ΔT = 100 K. The open circuit voltage was 7.3 mV and the internal resistance of the device was 11 Ω. These results for the power generation characteristics of the film device were consistent with values estimated from the dependence of thermoelectric properties on film thickness for PEDOT:PSS films on polyimide substrate.

[1] O. Bubnova, et al., Nat. Mater. 10, 429 (2011).

[2] G.-H. Kim, et al., Nat. Mater. 12, 719 (2013).

[3] M. Hokazono, et al., J. Electron. Mater., DOI: 10.1007/s11664-014-3003-y