Wide-Temperature-Range SnTe Thermoelectrics with High Average Figure of Merit

Here, an extraordinary average ZT of 1.18 and a high peak ZT of 1.5 in Sn_0.87-y-zAl_0.08Sb_yMn_0.08Ag_zTe compounds are reported. By increasing the configurational entropy, the band structure has been optimized markedly. The energy offset is significantly reduced, and a resonant level adjacent to the Fermi level is produced through increasing the configurational entropy, which contributes to a largely enhanced power factor over a broad temperature range. More importantly, the disorder and point defect scattering in Sn_1.03-x-y-zAl_xSb_yMn_xAg_zTe material are greatly increased caused by increasing the configurational entropy. Ultimately, the introduction of a highly disordered microstructure, which includes dense dislocations, precipitates, disorder, and point defects provide multi-scale phonon scattering centers, thus the lattice thermal conductivity is significantly suppressed. The lowest lattice thermal conductivity is reduced as low as 0.30 Wm^-1K^-1. The proposed strategy of entropy engineering has achieved remarkable success in enhancing the average thermoelectric performance of SnTe-based material over a wide temperature range and holds significant promise for application to other material systems.