A Potential Dual-Functional Thermoelectric and Electroelectric Polymer Composite

Doping alters the electronic properties of the host semiconducting polymer and may enable tunable devices with temperature sensing and environmental heating/cooling control system applications. We present a doped composite consisting of the p-type semiconducting polymer poly(3-hexylthiophene-2,5-diyl) (P3HT) and a thermoelectric electron acceptor, iodine, as the active layer of a field-effect device, where temperature modulates the current-voltage characteristics and on-off ratios, and gate voltage modulates the thermoelectric properties of the active layer, called dual-functionality. A small amount of iodine doping improved FET output by a factor of 10 as well as thermoelectric power factor by a factor of 3. Those gains are primarily attributed to thermoelectric doping induced charge-carrier density increases.