Thermoelectric figure-of-merit of iodine-doped copolymer of phenylenevinylene with dialkoxyphenylenevinylene

The copolymers consisting of both unsubstituted and 2,5-dialkoxy-substituted phenylenevinylenes (P(ROPV-co-PV); RO=MeO, EtO and BuO) with ca. 30 mol% of dialkoxy-substituted units were synthesized to evaluate their thermoelectric properties. Iodine-doped P(ROPV-co-PV) exhibited high Seebeck coefficient with relatively high electrical conductivity among electrically conductive polymers ever reported. The effect of the stretching treatment on their thermoelectric properties was examined. Consequently, both P(MeOPV-co-PV) and P(EtOPV-co-PV) constantly showed high Seebeck coefficients with increased electrical conductivities by the stretching alignment because of an increase in the carrier mobility, while the Seebeck coefficient of P(BuOPV-co-PV) varied inversely with a variation of the electrical conductivity. We also evaluated thermal conductivity of the pristine and iodine-doped P(ROPV-co-PV) for calculations of their thermoelectric figure-of-merit ZT To the best of our knowledge, consequent thermoelectric figure-of-merit ZT of all the iodine-doped copolymer with the stretch treatment is one of the highest thermoelectric performance among conducting polymers reported ever, which are comparable with that of an inorganic thermoelectric materials, such as beta-FeSi2. (c) 2007 Elsevier B.V. All rights reserved.