High-performance flexible thermoelectric generators with tunable in-plane and out-of-plane architectures

Although thermoelectric generators (TEGs) based on organic/inorganic composite films have made great achievements in recent years, rational design of flexible TEGs with tunable in-plane or out-of-plane architecture still remains a great challenge. Herein, flexible films of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/single-walled carbon nanotube (PEDOT:PSS/SWCNT) composite with an optimized power factor of 97 ± 2.4 μW m−1 K−2 are prepared by a facile solution mixing, followed by vacuum filtration and sequential solvents post-treatment. The effects of geometric parameters of thermoelectric (TE) legs on the generator output performance were investigated. Subsequently, the designed TEG prototypes, assembled in a "back-to-back" pattern with 5 or 10 p-n couples (TEG-5pn or TEG-10pn), can effectively utilize both in-plane and cross-plane temperature gradients. The out-of-plane TEG-10pn exhibits a higher output power density (337.4 μW cm−2 or 0.069 μW cm−2 K−2 at temperature difference of 70 K). Furthermore, the designed TEGs displayed versatile applications, efficiently achieving heat-to-electricity conversion by harvesting both in-plane and cross-plane temperature gradients induced by hot water in a cylindrical beaker, human body, or a hot plate. This work provides a convenient and practical strategy for the development of film-based TEGs, considering device architecture design, packing density and the geometric parameters of the TE legs.