Ultra-low lattice thermal conductivity realizing ultra-high performance Bi0.48Sb1.52Te3-based thermoelectric material and module

Abstract

The component regulation in Bi₂Te₃-based materials usually simultaneously decreases the lattice thermal conductivity and carrier mobility, which makes it difficult to improve the thermoelectric performance. In this work, we aim to improve the zT of p-type Bi_0.48Sb_1.52Te₃ by adding Sn_1/3Ge_1/3Pb_1/3Te and Cu to introduce differentiated electro–phonon scattering centres to reduce the lattice thermal conductivity while maintaining the carrier mobility as much as possible. Sn_1/3Ge_1/3Pb_1/3Te alloying produces many point defects and a Te-poor characteristic, thus inducing twin and low-angle grain boundaries to effectively strengthen the phonon scattering, and realizing an ultralow lattice thermal conductivity of 0.42 W m⁻¹ K⁻¹ at 300 K. Simultaneously, Cu doping optimizes the hole concentration, boosting the power factor overall to an average value of 32.1 μW cm⁻¹ K⁻² within 300–500 K. These synergistic effects yield a peak zT of 1.45 at 375 K and an average zT of 1.32 (300–500 K) in the Bi_0.48Sb_1.516Cu_0.004Te₃ + 0.50 wt% Sn_1/3Ge_1/3Pb_1/3Te sample. The integrated 17-pair thermoelectric module achieves a conversion efficiency of 6.8% at ΔT = 200 K when coupled with n-type zone-melted Bi₂Te_2.7Se_0.3. More importantly, the output performance of the fabricated module did not weaken after 100 cycles in a 500 hours aging test.