Enhanced thermoelectric performance of Bi2Se3/TiO2 composite

Bi2(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, Bi2Se3/TiO2 composites were prepared by hot pressing the plate-like Bi2Se3 powders coated in situ with hydrolyzed hytetabutyl-n-butyl titanate (TNBT), and therefore numerous TiO2 in micrometer size could be formed on the interface of Bi2Se3 grains. The carrier concentration in Bi2Se3 matrix is optimized subject to the addition of n-type semiconductor TiO2, contributing to a significant improved power factor. In the meantime, the lattice thermal conductivity is also suppressed due to the enhanced phonon scattering at Bi2Se3/TiO2 interface and amorphous TiO2 particles. As a consequence, a peak figure of merit (zT) of 0.41 is obtained at 525 K in Bi2Se3/15 mol% TiO2 composites, nearly 50% augment over the pristine Bi2Se3 binary compound.