Thermoelectric SnTe with Band Convergence, Dense Dislocations, and Interstitials through Sn Self-Compensation and Mn Alloying

SnTe is known as an eco-friendly analogue of PbTe without toxic elements. However, the application potentials of pure SnTe are limited because of its high hole carrier concentration derived from intrinsic Sn vacancies, which lead to a high electrical thermal conductivity and low Seebeck coefficient. In this study, Sn self-compensation and Mn alloying could significantly improve the Seebeck coefficients in the whole temperature range through simultaneous carrier concentration optimization and band engineering, thereby leading to a large improvement of the power factors. Combining precipitates and atomic-scale interstitials due to Mn alloying with dense dislocations induced by long time annealing, the lattice thermal conductivity is drastically reduced. As a result, an enhanced figure of merit (ZT) of 1.35 is achieved for the composition of Sn_0.94Mn_0.09Te at 873 K and the ZT_ave from 300 to 873 K is boosted to 0.78, which is of great significance for practical application. Hitherto, the ZT_max and ZT_ave of this work are the highest values among all single-element-doped SnTe systems.