Interfacial energy band and phonon scattering effect in Bi2Te3-polypyrrole hybrid thermoelectric material

Abstract

We hybridized n-type Bi2Te3 with an inexpensive and abundantly available conducting polymer, polypyrrole, to obtain a bulk-structured hybrid material in which the interfacial energy band and the phonon scattering effects should occur at the interface of the two components. The obtained hybrid material inevitably exhibited a lower electrical conductivity than pristine Bi2Te3, which may be attributable to carrier scattering at the interfacial energy barrier. However, the hybrid material completely compensated for this loss in electrical conductivity with a significant increase in the Seebeck coefficient, and thus it retained the power factor with no loss. In addition, the hybrid material displayed a much lower thermal conductivity than pristine Bi2Te3 owing to the phonon scattering effect. The hybrid material exhibited significant decoupling of the electrical and thermal properties, thus affording state-of-the-art figures of merit (ZT ∼ 0.98 at 25 °C, ZTmax ∼ 1.21 at 100 °C, and ZTave ∼ 1.18 at 50–150 °C) that exceed those of most of the previously reported n-type Bi2Te3 or Bi2(Te,Se)3 materials.