Synergistically Optimized Thermoelectric Performance in Bi_0.48Sb_1.52Te₃ by Hot Deformation and Cu Doping

In recent decades, bismuth telluride (Bi₂Te₃) has been in widespread use for normal-temperature thermoelectric cooling. However, commercial zone-melted bismuth telluride faces the big challenge of dramatically decreased thermoelectric properties at higher temperature, which limits its usage at intermediate temperature. In this contribution, the thermoelectric performance of p-type bismuth telluride is enhanced via a synergistic optimization by hot deformation and copper doping. Hot deformation treatment boosts the grain growth and exhibits donor-like effects, leading to improved electronic transport properties. Meanwhile, high-density dislocations and lattice distortions induced by dynamic recrystallization aggravate the phonon-related scattering and significantly compress the lattice thermal conductivity. In addition, copper doping effectively tunes the hole concentration, and the generated point defects also reduce the lattice thermal conductivity. Consequently, a high ZT_max of 1.1 at 400 K and ZT_ave of 1.0 between 300–500 K were obtained in hot-deformed Cu_0.01Bi_0.48Sb_1.52Te₃. This study suggests that the synergistic effect of hot deformation and copper doping is promising to boost the near-normal-temperature thermoelectric power generation of Bi₂Te₃-based thermoelectrics.