Enhanced thermoelectric performance of Bi ₂ Se ₃ /TiO ₂ composite

Abstract Bi ₂ (Te,Se) ₃ alloys are conventional commercial thermoelectric materials for solid‐state refrigeration around room temperature. In recent years, much attention has been paid to various advanced thermoelectric composite materials due to the unique thermoelectric properties. In this work, Bi ₂ Se ₃ /TiO ₂ composites were prepared by hot pressing the plate‐like Bi ₂ Se ₃ powders coated in situ with hydrolyzed hytetabutyl‐ n ‐butyl titanate (TNBT), and therefore numerous TiO ₂ in micrometer size could be formed on the interface of Bi ₂ Se ₃ grains. The carrier concentration in Bi ₂ Se ₃ matrix is optimized subject to the addition of n‐type semiconductor TiO ₂ , contributing to a significant improved power factor. In the meantime, the lattice thermal conductivity is also suppressed due to the enhanced phonon scattering at Bi ₂ Se ₃ /TiO ₂ interface and amorphous TiO ₂ particles. As a consequence, a peak figure of merit ( zT ) of 0.41 is obtained at 525 K in Bi ₂ Se ₃ /15 mol% TiO ₂ composites, nearly 50% augment over the pristine Bi ₂ Se ₃ binary compound.