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A1: Low temperature materials
Recently much attention has been paid to organic thermoelectric materials in order to recover electricity from the waste heat less than 200°C. Since organic materials have such advantages as plenty of resources, good processability, and light weight, they are expected to provide environmentally friendly and flexible thermoelectric devices with large area at low cost. Most of proposed organic thermoelectric materials are composed of conducting polymers like PEDOT:PSS. However, the high sensitivity to humidity is a weakness of these conducting polymers. Here, we propose novel hybrid organic thermoelectric materials without conducting polymers.
The hybrid films, composed of carbon nanotubes (CNTs), soluble polymer complexes (poly(nickel, 1,1,2,2-ethylenetetrathiolate), PETT), and poly(vinyl chloride) (PVC), were prepared by casting the mixtures of these three components in N-methylpyrrolidone (NMP). The CNTs (mixtures of single-walled carbon nanotubes) were purchased from Aldrich, and the soluble polymer complex (PETT/Ni/DTA) was prepared by ourselves with modification to the method reported by Y. Sun et al. (Adv. Mater., 2012, 24, 932-937). Thermoelectric properties of the films were measured with ULVAC ZEM-3 instrument.
The results showed that the thermoelectric power factor of the three-component film (weight ratio: PETT:CNT:PVC=10:8:3) was as high as 40.3 μW/m K at 340 K, although those of two-component films were 0.0005 and 2.9μW/m K for PETT/PVC and CNT/PVC films, respectively. The thermoelectric figure-of-merit ZT of the three-component thick film was improved by treatment with methanol, resulting in 0.33, which is close to those of PEDOT thin films reported previously (0.25 in O. Bubnova, et al., Nat. Mater., 2011, 10, 439 and 0.42 in G-H. Kim, et al., Nat. Mater., 2013, 12, 719). Details will be presented at the conference.
