Enhanced Thermoelectric Performance of p-Type Bi-Sb-Te Alloys by Codoping with Ga and Ag

We report an enhancement of the thermoelectric performance in spark-plasma-sintered polycrystalline p-type Bi0.42Sb1.58Te3 by codoping with Ga and Ag at Bi/Sb-site. Through controlled doping of Ga (n-type) and Ag (p-type), electronic transport properties including the electrical conductivity (similar to 988 S/cm at 300 K) and power factor (similar to 3.91 mW m(-1) K-2 at 300 K) could be maintained at values comparable to those of pristine Bi0.42Sb1.58Te3, while the lattice thermal conductivity was significantly reduced due to point-defect phonon scattering originating from the mass difference between the host atoms (Bi and Sb) and dopants (Ga and Ag). Through these synergetic effects, a peak ZT of 1.15 was obtained in Bi0.42Sb1.5535Ga0.025Ag0.0015Te3 at 360 K, and ZT could be engineered to be over 1.0 for a wide temperature range (300 K to 420 K).