Flexible and eco-friendly thermoelectric generators enabled by Bi and Se co-doped SnTe inks for energy harvesting

This study reports the synthesis of Bi- and Se-co-doped SnTe inks and the scalable fabrication of flexible thermoelectric generators (FTEGs) via a screen-printing technique, followed by material and device characterization. The Sn 1-x Bi x Te 1-y Se y (x = 0, 0.02, 0.04, 0.06, y = 0, 0.03) compositions were prepared via the solid-state reaction method, and their phase purity and high crystallinity were confirmed through X-ray diffraction (XRD) and surface morphology by scanning electron microscopy (SEM). The 4 % Bi-doped p-type SnTe exhibited optimized thermoelectric properties among the doped compositions. This p-type material, paired with MnO 2 as the n-type leg, was used to fabricate FTEG. The resulting FTEGs demonstrated excellent flexibility and mechanical durability, with minimal change in internal resistance under repeated bending cycles. The p-n-type (Sn 0.96 Bi 0.04 Te 0.97 Se 0.03 /MnO 2 ) FTEG achieved a maximum power output of 7.7 nW, which is 7.7 times higher, and a Seebeck coefficient of 150 μV/K, which is 1.25 times higher than that of the p-type pristine SnTe FTEG at a temperature gradient of 137 K. These findings underscore the potential of Bi and Se-co-doped SnTe-based inks for eco-friendly, cost-effective, and scalable fabrication of flexible thermoelectric devices for energy harvesting applications. Future efforts will focus on optimizing device architecture and exploring additional dopants to enhance performance further.