Investigating thin-film thermoelectric generators: Leg shape, TEG configuration, and contact resistance analysis

Thermoelectric generators (TEGs) are made of parallel p-type and n-type semiconducting legs which can directly convert temperature gradients into electricity. Theoretical studies have extensively explored the impact of the thermoelectric (TE) leg size and shape on the conversion efficiency of such bulk TEGs. However, in recent years, geometrically thin and film-shaped TEGs have gained attention for integration into wearable and flexible electronic devices, tapping into body heat as a power source. There is currently a lack of research on film-shaped TEGs, particularly regarding the performance of asymmetric TE leg shapes. This study investigates seven different TE leg shapes in thin-film TEGs, analyzing their electrical performance using COMSOL Multiphysics software. Results show that certain asymmetric TE leg shapes can yield over a 30% improvement in the produced open circuit voltage, as compared to conventional rectangular-shape TE legs. Furthermore, various configurations of thin-film TEGs were designed and analyzed, aiming to maximize device output power. Additionally, the study delves into the influence of electrical contact resistance on the performance of the optimal asymmetric TEGs. The proposed thin TE leg shapes and TEG configurations ae easily manufacturable and scalable using printing technology.