Defect dynamics manipulates transport behaviors in highly stable rocksalt-type thermoelectric crystal

Abstract

Adding Ge and Pb to the rock-salt SnTe triggers dynamic changes in the defect structures. As the doping level increases, these defects transit from densely dispersed dislocations to a network. Notably, the density of dislocations experiences a significant reduction when the Pb content exceeds a specific threshold value. For example, the alloy composition (Sn0.7Ge0.3)0.5Pb0.5Te demonstrates a solid solution behavior with limited linear defects. The fully dense (Sn0.7Ge0.3)0.5Pb0.5Te crystal shows reduced thermal conductivity κ and enhanced carrier mobility μ when compared to the pristine SnTe. Moreover, the single-leg device containing (Sn0.7Ge0.3)0.5Pb0.5Te achieves a remarkable efficiency η of 1.3 % across a temperature differential (∆T) of 280 K. This investigation successfully harnesses defect dynamics to manipulate the thermoelectric performance of IV-VI compounds while preserving their inherently stable rocksalt-type framework, all without undergoing phase transitions.