Enhanced phonon scattering and thermoelectric performance for N-type Bi2Te2.7Se0.3 through incorporation of conductive polyaniline particles

Bi2Te3 based alloys are the state-of-art thermoelectric materials at/near room temperatures. However, the per-formance of n-type Bi2Te3 is much difficult to improve as compared to p-type Bi2Te3. Here, we show that via incorporation of 1.5 wt% conductive polyaniline nanoparticles in Bi2Te2.7Se0.3 the lattice thermal conductivity of the composite system reduces by 49 % at 300 K mainly due to enhanced phonon scattering by the polymer inclusions. Moreover, energy-dependent carrier scattering occurs owing to the interfacial potentials formed at the inorganic/organic boundaries, leading to 8 % elevation of thermopower in the sample, which counteracts the decrease of electron mobility to a large degree. As a result, both a maximum figure of merit Zmax = 3.57 x 10-3 K-1 (300 K) and a maximum dimensionless figure of merit ZTmax = 1.22 (345 K) are achieved for the composite sample with 1.5 wt% PANI inclusions, which are respectively -42 % and -46 % larger than those of pristine Bi2Te2.7Se0.3, demonstrating that incorporation of nanophase polyaniline in Bi2Te2.7Se0.3 is an effective strategy to enhance its thermoelectric performance.

Automated summary

This study investigates the effect of incorporating conductive polyaniline nanoparticles on the thermoelectric performance of Bi2Te3-based alloys. It is found that the inclusion of polyaniline nanoparticles can reduce the lattice thermal conductivity of the composite system by increasing phonon scattering and enhance the thermopower by inducing energy-dependent carrier scattering at the inorganic/organic boundaries. The composite sample with 1.5 wt% PANI inclusions achieves the maximum figure of merit Zmax = 3.57 x 10-3 K-1 (300 K) and the maximum dimensionless figure of merit ZTmax = 1.22 (345 K), which are 42% and 46% higher than those of pristine Bi2Te2.7Se0.3, respectively, demonstrating the effectiveness of incorporating nanophase polyaniline to enhance the thermoelectric performance.