Flexible thermoelectric generators from spray-printed PEDOT:PSS/Bi_0.5Sb_1.5Te₃ composites

Energy harvesting technologies play a pivotal role in powering the next generation of wearable and portable devices, where thin-film thermoelectric generators (TEGs) offer a compact and flexible solution. In this study, flexible thin films of poly(3,4-ethylenedioxythiophene)polystyrene sulfonate (PEDOT:PSS)/Bi_0.5Sb_1.5Te₃ composite on flexible polymeric substrates were initially developed using a spray printing technique. The effect of substrate temperature during printing was assessed on the microstructural and thermoelectric properties, yielding a maximum power factor at a substrate temperature of 110 °C. Additionally, the printed films demonstrated excellent flexibility and mechanical/electrical stability during 1000 cycles of bending, confirming their suitability for wearable electronic applications. Subsequently, a flexible thin-film TEG containing 40 thermoelectric legs was fabricated by spray printing of the composite ink for the first time. Finally, the electrical performance of the flexible thin-film TEG was thoroughly assessed under various temperature gradients, exhibiting maximum open circuit voltage of 52 mV at a temperature difference of 50 °C. This study establishes a foundation for the facile fabrication of flexible TEGs using organic/inorganic composite inks. Further enhancement of the thermoelectric performance can be envisaged through post-processing chemical treatments to optimize charge carrier concentration in the printed TEGs.