Rare-Earth Nd Inducing Record-High Thermoelectric Performance of (GeTe) <sub>85</sub> (AgSbTe <sub>2</sub> ) <sub>15</sub>
Wanyu Lyu, Min Hong, Wei‐Di Liu, Meng Li, Qiang Sun, Sheng Duo Xu, Jin Zou, Zhi‐Gang Chen
Abstract
As a promising midtemperature thermoelectric material with both higher thermoelectric performance and mechanical property, Tellurium Antimony Germanium Silver (TAGS- x ), written as (GeTe) x (AgSbTe 2 ) 1- x , especially (GeTe) 0.85 (AgSbTe 2 ) 0.15 (TAGS-85), has attracted wide attention. Herein, we innovatively use Nd doping to synergistically decrease the carrier concentration to the optimal level leading to enhanced dimensionless figure of merit, zT. Our density-functional theory calculation results indicate that Nd-doping reduced carrier concentration should be attributed to the enlargement of band gap. The optimized carrier concentration results in an ultrahigh power factor of ~32 μ W cm -1 K -2 at 727 K in Ge 0.74 Ag 0.13 Sb 0.11 Nd 0.02 Te. Simultaneously, the lattice thermal conductivity of Ge 0.74 Ag 0.13 Sb 0.11 Nd 0.02 Te retained as low as ~0.5 at 727 K. Ultimately, a record-high zT of 1.65 at 727 K is observed in the Ge 0.74 Ag 0.13 Sb 0.11 Nd 0.02 Te. This study indicates rare-earth Nd doping is effective in boosting the thermoelectric performance of TAGS-85 and approached a record-high level via synergistic effect.