Thermoelectric Performance of Poly(3-hexylthiophene) Films Doped by Iodine Vapor with Promising High Seebeck Coefficient

Poly(3-hexylthiophene) (P3HT) films doped with iodine vapor have been prepared by casting a P3HT solution on glass substrates and their thermoelectric (TE) performances has been investigated. The maximum Seebeck coefficient and electrical conductivity of iodine-doped P3HT films were 386 mu V.K-1 (at room temperature) and 4.7 x 10(-1) S.cm(-1), which is about five orders of magnitude higher than that of pristine P3HT films The power factor of these iodine-doped P3HT films was estimated to be 7.0 mu W.m(-1).K-2 at room temperature, which is a relative high value for organic TE materials. The UV-vis spectra of iodine-doped P3HT films showed a slight red shift of the iodine-doped P3HT compared to those of pristine P3HT films. Atomic force microscopy images indicated the conformational changes in P3HT chains after treatment with iodine vapor. During this treatment, the P3HT chains self-organized into a more ordered structure, this organization improved the charge carrier transport capability and the TE performance of P3HT the films