Electrical and Thermal Transport Properties of Ge1–xPbxCuySbyTeSe2y

Abstract

AbstractBalancing the contradictory relationship between thermoelectric parameters, such as effective mass and carrier mobility, is a challenge to optimize thermoelectric performance. Herein, the exceptional thermoelectric performance is realized in GeTe through collaboratively optimizing the carrier and phonon transport via stepwise alloying Pb and CuSbSe2. The formation energy of Ge vacancy is efficiently bolstered by alloying Pb, which reduces carrier density and carrier scattering to maintain superior carrier mobility in GeTe. Additionally, CuSbSe2, acting as an n‐type dopant, further modulates carrier density and validly equilibrates carrier mobility and effective mass. Accordingly, the promising power factor of 45 µW cm−1 K−2 is achieved at 723 K. Meanwhile, point defects are found to significantly suppress phonons transport to descend lattice thermal conductivity by Pb and CuSbSe2 alloying, which barely impacts the carrier mobility. A combination with superior carrier mobility and lower lattice thermal conductivity, a maximum ZT of 2.2 is attained in Ge0.925Pb0.075Cu0.005Sb0.005TeSe0.01, which corresponds to a 100% promotion compared with that of intrinsic GeTe. This study provides a new indicator for optimizing carrier and phonon transport properties by balancing interrelated thermoelectric parameters.