Facile Green Vacuum-Assisted Method for Polyaniline/SWCNT Hybrid Films with Enhanced Thermoelectric Performance by Interfacial Morphology Control

The interfacial issue is a critical factor affecting the thermoelectric performance in the organic–inorganic composite system. However, in the traditionally adopted solution casting method for organic–inorganic composites, it is difficult to tune the interface effectively. Herein, as a proof-of-concept, high-performance polyaniline (PANI)/carbon nanotube (CNT) thermoelectric (TE) composite films have been fabricated by a green vacuum-assisted method through the interfacial morphology control via a different solvent treatment. Morphological characterization indicates that the PANI is successfully uniformly wrapped around the surface of CNTs, and the interfaces are improved by proper treatment with N,N-dimethylformamide (DMF) solvent. Combining cold-pressure treatment for the vacuum-assisted thin films further achieves higher electrical conductivity and a relatively higher Seebeck coefficient through the enhancement of interfacial adhesion. Ultimately, the composite films prepared with 90 wt % CNTs show the highest TE properties, while the room-temperature electrical conductivity and power factor reach 1965 S cm–1 and 114.4 μW·m–1·K–2 with DMF solvent treatment, respectively. Furthermore, the Seebeck coefficient value increases with increase in temperature from room temperature to 410 K, leading to a maximum power factor of 203 and 402 μW·m–1·K–2 for the 70 and 90 wt % CNT composite films, respectively. Our approach using vacuum-assisted assembly method combining solvent and cold-pressure treatment provides a good paradigm for developing high-performance thermoelectric materials that benefit from interface engineering.