Simultaneous Regulation of Electrical and Thermal Transport Properties of N-Type Bi2Te3 via Adding Excessive Te Followed by Se Doping

Thermoelectric devices based on bismuth telluride-based alloys have been applied widely for several decades. Our results demonstrate that excessive Te constructs large amounts of anti-site defects Te-Bi, thereby increasing the carrier concentration and suppressing the bipolar effect. Moreover, compared with the traditional dominated defects V-Te in other works, the Te-Bi induce smaller lattice distortion, thus alleviating carrier scattering and then increasing carrier mobility. Accordingly, a high ZT value of 0.78 at 125 degrees C is obtained in Bi2Te3 + 0.3 wt % Te. Then, Se doping at Te sites is used to reduce the lattice thermal conductivity by enhancing phonon scattering. Finally, a high ZT value of similar to 1.0 at 125 degrees C and an average ZT value of 0.88 from 30 to 250 degrees C are realized on the Bi2Te2.5Se0.5 + 0.3 wt % Te sample.

Automated summary

By controlling the defect composition and lattice distortion in bismuth telluride-based alloys to improve carrier mobility, combined with Se doping to reduce thermal conductivity, high ZT values in thermoelectric devices can be achieved.