Enhanced thermoelectric performance in cubic SnSe-based alloys via manipulation of grain boundary scattering and phonon transport

Metastable cubic SnSe has received extensive attention in terms of theoretical predictions since orthorhombic SnSe was experimentally developed as one of the most promising thermoelectric candidates in recent years. In this work, we successfully stabilized the cubic SnSe through AgSbTe2 alloying, after which the thermoelectric transport properties were significantly optimized by simultaneously suppressing lattice and electronic thermal conductivities via introducing Pb. The maximum power factor of (SnSe)(0.6)(AgSbTe2)(0.4) reached to 13 mu Wcm(-1)K(-2) at 723 K, with a high average power factor of similar to 12 mu Wcm(-1)K(-2) at 300-773 K. Based on 40% AgSbTe2 alloying, the strong phonon-defect scattering and low electronic thermal conductivity caused by Pb alloying contribute greatly to the reduction of total thermal conductivity, while the excellent electrical transport properties were substantially maintained. Finally, the peak ZT value reached to 1.20 and a high average ZT value of similar to 0.90 over 300-773 K were achieved in the cubic phase (SnSe)(0.6)(AgSbTe2)(0.4) with 10% Pb alloyed.