Increasing demand for wearable power-generation systems has led to research interest in organic thermoelectric (TE) materials due to their flexibility and ease of processing. Even though organic TE materials with thin film structures have adequate flexibility, an organic TE generator with a vertical structure (which increases the temperature difference between its hot and cold parts) has difficulty when subject to compression or bending because of its lack of sufficient elasticity and durability. Hence, an organic TE material with both high TE performance and mechanical durability is highly desirable for the realization of a wearable TE generator with a vertical structure that can be used in various environments.

In the present study, we prepared elastic and durable carbon nanotube (CNT)/polydimethylsiloxane (PDMS) foam materials with high TE performance using a rapid solvent evaporation method. This approach provides significant structural freedom in terms of the shape and size of the CNT/PDMS foam. The incorporation of PDMS into CNT foam effectively decreases the thermal conductivity of the CNT/PDMS foam without the electrical loss because of the creation of conducting percolation structures in the CNT/PDMS foam. In addition, the PDMS plays a significant role by providing a self-supporting structure that does not require an additional scaffold matrix, and this greatly improves mechanical properties such as the stiffness and elasticity of the CNT/PDMS foam. Hence, a CNT/PDMS foam with a porosity exceeding 87% exhibits a zT value twice as high as pristine CNT foam, and it has the extremely low thermal conductivity of 0.13 W m−1 K−1. Furthermore, this composite foam can achieve an elongation greater than 20%, and it exhibits high resilience under a compressive strain of 80%. Finally, we successfully fabricated a flexible and durable CNT/PDMS foam power generator with a vertical structure using a combination of p- and n- type CNT/PDMS foams. The CNT/PDMS foam generator exhibits good mechanical stability and durability, and it provides stable relative resistance values after cyclic bending more than 6000 times and under harsh vibrational stress. The CNT/PDMS foam generator displays a high output power of 1.9 μW at a temperature difference of 18.1 K in the vertical direction. Moreover, it sustainably generates an electrical power of 38.2 nW under the continuous vibrational stress produced by a car engine.