Atomic-defect-suppressed pristine p-type Bi0.3Sb1.7Te3 as robust high-performance thermoelectrics for power generation and cooling

High-strength high-performance p-type (Bi,Sb)2Te3 are of pivotal importance for near-room-temperature thermoelectric conversions, the reliable synthesis and fabrication has been viewed of imperative priority. It is known that the energy-favorable formation of anti-site SbTe’ and vacancy vSb''' acceptor defects from high-temperature syntheses results in additional charge carriers and scattering centers for electrical and phonon transport. However, how p-type (Bi,Sb)2Te3 with minimal lattice defects function remains to be scrutinized. Herein, we present the synergistic enhancements of mechanical robustness and thermoelectric property in crystallographic-defect-suppressed pristine (Bi,Sb)2Te3 through a simple mechanical alloying combined with spark-plasma-sintering (SPS) process. The SbTe’ and vSb''' acceptor defects were efficiently restrained, contributing to markedly increased charge carrier mobilities. A slightly enlarged band gap of 0.24 eV underpinned enhanced thermoelectric performance for pristine Bi0.3Sb1.7Te3 over a wide temperature range, delivering high zT300 K of 1.16 and zTave of 1.21 over 300–473 K. Interestingly, the confined in-situ grain coarsening during SPS with uniform dispersive nanopores readily endowed an ultra-high compressive strength of 206 MPa, surpassing that of reported (Bi,Sb)2Te3 so far. A 7-pair module (coupled with n-Bi2Te3) was fabricated, demonstrating a competitive ΔT over 70 K at Thot = 300 K. Furthermore, a power-generation module coupled with n-Mg3SbBi registered a cutting-edge thermoelectric conversion efficiency of 9.5% at a temperature gradient of 250 K. The strategy eliminates the need of complex processing nor extrinsic doping for pristine (Bi,Sb)2Te3, demonstrating great potentials in thermoelectric power generation and cooling applications.