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

Abstract

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.

Polyaniline/SWCNT composite films prepared via the solvent-induced strategy for flexible energy harvesting

“…We studied the inuence of the polymerization process, preparation method, and treatment of different solvents on thermoelectric properties. 5,34 In this work, we prepared composites of SWCNTs and PANI using solvent-induced strategy in different solvents and explored the effect of solvent type on the microstructure of PANI-based composites. DMF solvent was able to induce the achievement of a uniform and orderly coating of PANI on SWCNTs.…”

Advancement of Polyaniline/Carbon Nanotubes Based Thermoelectric Composites

“…Feng et al [ 66 ] fabricated PANI/SWCNTs composite films through a vacuum filtration method by mixing SWCNTs dispersion with PANI in different solvents, in which the interfacial morphology can be controlled. With ethanol as the solvent, many isolated clusters of PANI appeared on the SWCNTs surfaces due to the poor solubility of PANI in ethanol ( Figure 3 b–d).…”

“… ( a ) Schematic representations of PANI layer on the surface of CNTs [ 47 ]; ( b ) Schematic of the microstructure of solvent-treated PANI/SWCNTs films: ethanol and DMF solvent; SEM images of PANI/0.9CNTs composite films with ( c ) ethanol and ( d ) DMF solvent treatment [ 66 ]. …”

Ultrahigh Power Factor of Ternary Composites with Abundant Se Nanowires for Thermoelectric Application

“…Nowadays, the waste heat is converted into electricity using thermoelectric (TE) machines, − which has attracted great attention because of the exhausting fossil energy and environmental problems. Thermoelectric materials are attractive new energy materials as a result of their pollution-free, no mechanical moving parts and lack of rotating parts or gas emissions. − In addition, it is very easy and straightforward for them to realize the transformation between thermal resources and electrical resources via the Seebeck effect and the Peltier effect. , Typically, high performance in TE materials is attained by decreasing the thermal conductivity (κ) and extremely increasing the power factor (PF = S 2 σ), − where S is the Seebeck coefficient and σ is the electrical conductivity. Obviously, a high Seebeck coefficient and high electrical conductivity are simultaneously required to further obtain an enormous PF value .…”

“…Although adding inorganic fillers to the polymer materials is a good way to enhance the performance of composites, the TE performances of the inorganic material/PEDOT:PSS composites remain weaker than those of inorganic TE materials. ,− There are a number of investigations trying to promote the TE properties of composites using nanocarbons. ,,− Recently, CNTs are already employed as a useful additive to improve the TE behavior of conjugated polymers due to their remarkable electrical conductivity, high charge carrier transport performances, narrow band gap energy, and mechanical flexibility with environmental stability. ,, The formation of the CNT network in polymer facilitates the charge transport, which leads to a high electrical conductivity. ,,− For instance, Liu et al successfully prepared single-walled carbon nanotube (SWCNT)/SnSe nanosheet/PEDOT:PSS by facile vacuum filtration, an optimal power factor of 109.9 μW/(m·K 2 ) was achieved. Kumar et al mixed PEDOT:PSS with hydrothermally synthesized Bi 2 Te 3 /CNT and successfully synthesized Bi 2 Te 3 –CNT–PEDOT nanocomposites, finally, an optimized electrical conductivity and Seebeck coefficient of 990 S/cm and −111 μV/K were gained, respectively.…”