Interstitial Defects Facilitate Dense Dislocations and Band Convergence for High Thermoelectric Performance in SnTe

SnTe, emerging as a promising lead-free thermoelectric candidate, has received a great deal of attention for power generation. Here, we report a record-high average ZT of 1.02 as well as a high peak ZT of ∼1.5 through the V/Sb and AgSbTe2 alloying approach in SnTe. We demonstrate that the aggregation of V interstitials promotes the formation of dense dislocation arrays and dislocation networks, which effectively scatters heat-carrying phonons and contributes to an extremely low κL of ∼0.41 W m–1 K–1. More importantly, V interstitials provide pinning effects to dislocation motion, indicating the high stability of our materials at elevated temperatures. Also, V interstitials and Ag alloying facilitate band convergence in SnTe, resulting in a remarkable enhancement of the Seebeck coefficient. The carrier concentration can be tuned to an optimal level. The power factor sharply increases over the whole temperature range due to band convergence induced by Ag incorporation and optimized carrier concentration. Benefits of the decoupling of electron and phonon transport, such as high average ZT and peak ZT, can be realized, making SnTe an attractive candidate for highly effective solid-state thermoelectric devices.