High-Performance Flexible Bi2Te2.7Se0.3 Thermoelectric Films Enabled by Thickness Engineering
Year: 2026
Type: article
Abstract: Addressing the critical challenge in n-type Bi2Te3-based films where the strong coupling among the Seebeck coefficient, electrical conductivity, and thermal conductivity limits thermoelectric performance, this work fabricates Bi2Te2.7Se0.3 films with thicknesses of 500, 650, and 800 nm on flexible substrates using dual-target magnetron co-sputtering combined with high-temperature annealing (673 K, 2 h). We systematically investigate the synergistic regulation of film thickness on texture, grain boundary structure, and electro-thermal transport. XRD and EBSD analyses reveal that increasing thickness decreases the (0111) orientation factor from 0.55 to 0.40, disperses the texture, and increases the proportion of high-angle grain boundaries (HAGBs) from 84.9% to 86.9%, accompanied by grain refinement. The Hall mobility follows a T-1.5 temperature dependence, confirming that acoustic phonon scattering dominates carrier transport. Concurrently, the energy filtering effect induced by the increased HAGBs enhances the Seebeck coefficient while maintaining a stable carrier concentration (around 1019 cm-3). All three films exhibit ultra-low total thermal conductivities of only 0.89-0.91 . Consequently, the 800 nm film achieves an outstanding room-temperature zT value of 1.14. This work establishes an intrinsic “thickness-texture-grain boundary-transport” correlation, providing key insights into thickness engineering for optimizing flexible, in-plane thermoelectric films.
Author: Shuai Zhou
Institution: Yangtze University
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7163384492