Enhanced Thermoelectric Performance of Screen-Printed Bi₂Te₃ Flexible Films and Generators through Controlled Thermal Processing

Flexible thermoelectric devices can directly convert body heat into electricity, which has broad application prospects in powering wearable electronics. In this study, Bi2Te3 flexible films, devoid of organic adhesive, were prepared via screen printing of solution-synthesized Bi2Te3 powders on rough polyimide combined with hot pressing. Heat treatment of Bi2Te3 powders and tuning the temperature for hot pressing play crucial roles in the modulation of microstructure, carrier concentration, and carrier mobility, leading to an enhanced power factor of 1186 μW m–1 K–2 at 427 K. Based on such films, a Bi2Te3 flexible prototype thermoelectric generator with encapsulation of polydimethylsiloxane (PDMS) was assembled, which exhibits a maximum output power density of 2.9 W m–2 at a temperature difference of 30 K. Moreover, after bending at a radius of 10 mm for 600 times, the internal resistance of the device increases by ∼12%, demonstrating better flexibility as compared to a Bi2Te3 flexible generator without PDMS encapsulation. This study provides a promising approach to the preparation of flexible chalcogenide films and devices with a high thermoelectric performance.