Enhanced energy harvesting performance of bendable thermoelectric generator enabled by trapezoidal-shaped legs

초록

Thermoelectric generators (TEGs) have gained attention as a promising technology for clean energy harvesting. Improving the energy conversion efficiency of TEGs is crucial for realizing the thermoelectric (TE)-based selfpowered system. Herein, the shape and surface area of the TE legs and its impact on the energy conversion performance were evaluated systematically. The trapezoidal-shaped legs (TSL)-based TEGs were fabricated by truncating the top side of a cuboid structure with various top surface areas. We found that there is an inverse relationship between the truncated cross-sectional area and thermoelectric output values of the TSL-TEGs. This improvement in performance is attributed to the reduction in the overall thermal conductance of the TSL-TEG, which allows for a more significant Delta T value to be sustained between the hot and cold ends of the TE leg. Particularly, the TSL-TEG with top surface area of 2.5 x 2.5 mm2 converts the output power of 0.60 mW from a temperature gradient (Delta T) of = 200 K, which represents a two-fold increase compared to the cuboid-shaped legs (5 x 5 mm2)-based TEG. Additionally, to theoretically verify the effective conversion efficiency of TSL-TEGs, we conducted a finite element analysis with Multiphysics simulation and compared the calculated results acquired from leg's structures. Finally, we have demonstrated the energy harvesting of a bendable TEG made of TSLs, generating 0.38 mA and 30 mV at Delta T = 50 K when attached to the hot-curved metal object in a real-time lowgrade thermal energy environment.

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