Promising thermoelectric performance in p-type AgBiSe2 doping with alkaline-earth metals

Abstract

P-type AgBiSe2 is a promising thermoelectric material because of its intrinsic low lattice thermal conductivity and multiple valence band behavior. However, realizing high performance in p-type AgBiSe2 is challenging due to the doping bottleneck. In this work, the enhancement of thermoelectric performance for p-type AgBiSe2 has been successfully realized by adding an excess amount of Se and doping with alkaline-earth metals. We show that Ca or Mg doping at the Bi site effectively increases the room-temperature hole concentration and improves the electrical transport properties of p-type AgBiSe2. Combined with the intrinsic lower thermal conductivity, the maximum zT values of ∼0.74 and ∼0.63 at 448 K were achieved in AgBi0.98Ca0.02Se2 and AgBi0.98Mg0.02Se2, respectively. This work demonstrates a crucial strategy for improving the thermoelectric properties of p-type AgBiSe2-based materials.