Magnetic-field-enhanced high thermoelectric performance in narrow-band-gap polycrystalline semiconductor Ag_2+δTe

Ag₂Te is a promising near-room-temperature thermoelectric material. However, its thermoelectric performance is difficult to be further improved by traditional strategies, such as doping and alloying. Herein, we demonstrate that the magnetic field is effective to enhance the thermoelectric performance of polycrystalline Ag_2+δTe. The ZT of Ag_2+δTe at 300 K can increase from 0.44 to 0.80 under a perpendicular magnetic field of 5 T. Similar to the magneto-thermoelectric properties observed in the semimetal materials, our studies not only reveal that the linear energy dispersion plays an important role for the increase of ZT in polycrystalline Ag_2+δTe, but also suggest that external field regulation can be an effective strategy to enhance the thermoelectric properties.