Piezoelectric Engineering Boosts Thermoelectric Performance of Gete Via Energy Filtration Effect and Phonon Scattering

Abstract

Grain boundaries or phase boundaries, playing a crucial role in decoupling electrical and thermal transport, are often engineered to regulate thermoelectric properties. While the composition, density, coherency, and width have been extensively studied, the focus on the local electric field created at these boundaries to manipulate the movement of charge and phonons has been limited. By incorporating piezoelectric material Pb(Zr0.50Ti0.44Fe0.06)O3 into thermoelectrics Ge0.94Sb0.06Te, a local electric field is generated to hinder the passage of low-energy holes. This results in a noteworthy enhancement of the Seebeck coefficients in the composites without compromising electrical conductivity, thanks to the energy filtration effect. Moreover, the addition of the second phase Pb(Zr0.50Ti0.44Fe0.06)O3 into the Ge0.94Sb0.06Te matrix effectively scatters mid-frequency phonons, thereby aiding in reducing lattice thermal conductivity, especially at low temperature. Consequently, an improvement in zT values can be achieved for the sample Ge0.94Sb0.06Te+0.3 wt% Pb(Zr,Ti)1-xFexO3, showing a 15% increase compared to the sample without Pb(Ti,Zr)1-xFexO3. Simulation results reveal 10.74% of conversion efficiency for a thermoelectric single-leg, indicating significant application potential in the field of power generation.

Keywords: Piezoelectric engineering, GeTe, Pb(Zr, Ti)O3, Energy filtration, Thermoelectric properties