Designing cost-performance porous thermoelectric materials by interface engineering through atomic layer deposition

Abstract

The bismuth-telluride-based alloy is the only thermoelectric material commercialized for the applications of refrigeration and energy harvesting, but its low cost-effectiveness severely restricts its large-scale application. The introduction of a porous structure in bulk thermoelectric materials has been theoretically proven to effectively reduce thermal conductivity and cost. However, the electrical properties of highly porous materials are considerably suppressed due to the strong carrier scattering at the interface between the matrix and pores, ultimately leading to decreased figure of merit, ZT. Here, we use an atomic layer deposition strategy to introduce some hollow glass bubbles with nano-oxide layers into commercial Bi_0.5Sb_1.5Te₃ for preparing high-performance porous thermoelectric materials. Experimental results indicate that the nano-oxide layers weaken carrier scattering at the interface between pores and matrix while maintaining high-strength phonon scattering, thereby optimizing carrier/phonon transport behaviors, and effectively increasing the ZT by 23.2% (from 0.99 to 1.22 at 350 K). Besides, our strategy has excellent universality confirmed by its effectiveness in improving the ZT of Bi₂Te_2.7Se_0.3, therefore demonstrating great potential for developing low-cost and high-performance thermoelectric materials.