Antisite defect enhanced thermoelectric performance of topological crystalline insulators*

As the first experimentally established topological crystalline insulator (TCI), SnTe also exhibits superior thermoelectricity upon proper doping; yet to date, whether such doping will preserve or destroy the salient topological properties in achieving outstanding thermoelectric performance remains elusive. Using first-principles calculations combined with Boltzmann transport theory, we uncover the elegant role of antisite defect in optimally enhancing the thermopower of SnTe while simultaneously preserving its topological nature. We first show that Sn_Te antisite defect effectively induces pronounced variations in the low-energy density of states rather than rigidly shifting the chemical potential, resulting in higher Seebeck coefficient and power factor. Next, we demonstrate that in a wide temperature range the Seebeck coefficient of antisite doped SnTe distinctly outperforms previously identified systems invoking extrinsic dopants. We further confirm that such intrinsic antisite doping preserves the nontrivial topology, which in turn favors high electrical conductivity and thermoelectricity. These findings render antisite doping as a natural and powerful avenue to optimize the overall thermoelectric performance of TCIs and related systems.