High-performance thermoelectric materials based on ternary TiO2/CNT/PANI composites

Abstract

In the present work, we report the fabrication of high-performance thermoelectric materials using TiO₂/CNT/PANI ternary composites. We showed that a conductivity of ∼2730 S cm⁻¹ can be achieved for the binary CNT (70%)/PANI (30%) composite, which is the highest recorded value for the reported CNT/PANI composites. We further demonstrated that the Seebeck coefficient of CNT/PANI composites could be enhanced by incorporating TiO₂ nanoparticles into the binary CNT/PANI composites, which could be attributed to lower carrier density and the energy scattering of low-energy carriers at the interfaces of TiO₂/a-CNT and TiO₂/PANI. The resulting TiO₂/a-CNT/PANI ternary system exhibits a higher Seebeck coefficient and enhanced thermoelectric power. Further optimization of the thermoelectric power was achieved by water treatment and by tuning the processing temperature. A high thermoelectric power factor of 114.5 μW mK⁻² was obtained for the ternary composite of 30% TiO₂/70% (a-CNT (70%)/PANI (30%)), which is the highest reported value among the reported PANI based ternary composites. The improvement of thermoelectric performance by incorporation of TiO₂ suggests a promising approach to enhance power factor of organic thermoelectric materials by judicial tuning of the carrier concentration and electrical conductivity.