In Situ Synthesis of High Thermoelectric Performance Bi2Te3 Flexible Thin Films through Thermal Diffusion Engineering

Abstract

Bi2Te3-based materials are promising candidates for near-room-temperature applications due to their high thermoelectric performance and low cost. Here, an innovative thermal diffusion strategy combined with magnetron sputtering and thermal evaporation methods was employed to fabricate Bi2Te3 flexible thin films (f-TFs) on a flexible polyimide substrate. An in situ synthesis of Bi2Te3 f-TFs with good crystallinity was obtained using a straightforward thermal diffusion method through diffusion of Te into a Bi precursor under low vacuum conditions (1 × 105 Pa). This method offers easy preparation, low cost, and a large-area film preparation for industrialization. The electrical conductivity increases with increasing thermal diffusion temperatures. A high room temperature carrier mobility of ~28.7 cm−2 V−1 S−1 and an electrical conductivity of ~995.6 S cm−1 can be achieved. Then, a moderate room temperature Seebeck coefficient >100 μV K−1 was obtained due to the chemical stoichiometry being close to the standard by optimizing the thermal diffusion temperature. Consequently, a maximum room temperature PF of ~11.6 μW cm−1 K−1 was observed in Bi2Te3 f-TFs prepared using a thermal diffusion temperature of 653 K. The thermal diffusion strategy applied in the thin film preparation represents an effective approach for the preparation of high thermoelectric performance Bi2Te3 f-TFs, offering a promising route for future thermoelectric applications.