Vacancy Manipulation by Ordered Mesoporous Induced Optimal Carrier Concentration and Low Lattice Thermal Conductivity in BixSb2−xTe3 Yielding Superior Thermoelectric Performance

Abstract For Bi x Sb 2− x Te 3 (BST) in thermoelectric field, the element ratio is easily influenced by the chemical environment, deviating from the stoichiometric ratio and giving rise to various intrinsic defects. In P‐type polycrystalline BST, Sb Te and Bi Te are the primary forms of defects. Defect engineering is a crucial strategy for optimizing the electrical transport performance of Bi 2 Te 3 ‐based materials, but achieving synchronous improvement of thermal performance is challenging. In this study, mesoporous SiO 2 is utilized to successfully mitigate the adverse impacts of vacancy defects, resulting in an enhancement of the electrical transport performance and a pronounced reduction in thermal conductivity. Crystal and the microstructure of the continuous modulation contribute to the effective phonon–electronic decoupling. Ultimately, the peak zT of Bi 0.4 Sb 1.6 Te 3 /0.8 wt% SiO 2 (with a pore size of 4 nm) nanocomposites reaches as high as 1.5 at 348 K, and a thermoelectric conversion efficiency of 6.6% is achieved at Δ T = 222.7 K. These results present exciting possibilities for the realization of defect regulation in porous materials and hold reference significance for other material systems.