Band Modification and Localized Lattice Engineering Leads to High Thermoelectric Performance in Ge and Bi Codoped SnTe-AgBiTe2 Alloys.

ABSTRACT

SnTe, emerging as an environment-friendly alternative to conventional PbTe thermoelectrics, has drawn significant attention for clean energy conversion. Here, a high peak figure of merit (ZT) of 1.45 at 873 K in Ge/Bi codoped SnTe-AgBiTe2 alloys is reported. It is demonstrated that the existence of Ge, Bi, and Ag facilitate band convergence in SnTe, resulting in remarkable enhancement of Seebeck coefficient and power factor. Simultaneously, localized lattice imperfections including dislocations, point defects, and micro/nanopore structures are caused by incorporation of Ge, Bi, and Ag, which can effectively scatter heat carrying phonons with different wavelengths and contribute to an extremely low κL of 0.61 W m-1  K-1 in Sn0.92 Ge0.04 Bi0.04 Te-10%AgBiTe2 . Such high peak ZT is achieved by decouples electron and phonon transport through band modification and localized lattice engineering, highlighting promising solutions for advancing thermoelectrics.