Enhanced Antioxidation and Thermoelectric Properties of the Flexible Screen-Printed Bi₂Te₃ Films through Interface Modification

With the advantages of easy processing and mass production, printing technologies to fabricate flexible thermoelectric films have received widespread scientific and technological interest. In this work, interface modification has been applied to effectively improve the loose porous intrinsic structure of screen-printed Bi2Te3 thermoelectric films, thus regulating the antioxidation and thermoelectric properties. Specifically, nanosolder is prepared and introduced into the screen-printing technique, which can modify the interface and thus enhance the electrical conductivity in the screen-printed film. Accordingly, a highest power factor of 3.63 μW cm–1 K–2 is obtained and the ZT over 0.2 is achieved in a wide temperature range from 300 to 460 K. Meanwhile, the role of the inert gas (N2) and the reducing atmosphere (Ar/H2, 5% H2 + 95% Ar) during the sintering process of screen-printed Bi2Te3 films is also revealed. The film with nanosolder sintered in N2 has excellent oxidation resistance through the interface modification of thiol molecules. However, the hydrogen atmosphere damages the antioxidation according to the gas-induced defect engineering. Through the introduction of nanosolder, the electrical resistivity change of the screen-printed film is just about 3.6% after being stored for 6 months in air, and it can withstand repeated bending for 1000 times (concave) or 600 times (convex) when the bending radius is as low as 20 mm. Our research provides an effective method for preparing high-quality flexible thermoelectric films and greatly facilitates the development of screen-printed flexible wearable thermoelectric devices.