Flexible Thermoelectric Polymer Composites Based on a Carbon Nanotubes Forest

Abstract

Polymer-based composites are of high interest in the field of thermoelectric (TE) materials because of their properties: abundance, low thermal conductivity, and nontoxicity. In applications, like TE for wearable energy harvesting, where low operating temperatures are required, polymer composites demonstrate compatible with the targeted specifications. The main challenge is reaching high TE efficiency. Fillers and chemical treatments can be used to enhance TE performance of the polymer matrix. The combined application of vertically aligned carbon nanotubes forest (VA-CNTF) is demonstrated as fillers and chemical post-treatment to obtain high-efficiency TE composites, by dispersing VA-CNTF into a poly (3,4-ethylenedioxythiophene) polystyrene sulfonate matrix. The VA-CNTF keeps the functional properties even in flexible substrates. The morphology, structure, composition, and functional features of the composites are thoroughly investigated. A dramatic increase of power factor is observed at the lowest operating temperature difference ever reported. The highest Seebeck coefficient and electrical conductivity are 58.7 µV K −1 and 1131 S cm −1 , respectively. The highest power factor after treatment is twice as high in untreated samples. The results demonstrate the potential for the combined application of VA-CNTF and chemical post-treatment, in boosting the TE properties of composite polymers toward the development of high efficiency, low-temperature, flexible TEs. ThermoelectricsThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.

Freely Shapable and 3D Porous Carbon Nanotube Foam Using Rapid Solvent Evaporation Method for Flexible Thermoelectric Power Generators

“…In contrast to the parallel TE structure, the vertical TE device (which constitutes the conventional architecture for inorganic materials) sufficiently increases the temperature difference between the hot and cold sides through the thick TE layer . To construct a vertical TE generator using organic TE materials, Yusupov et al reported vertically aligned multiwalled carbon nanotube forests (VA‐CNTFs), which led to the realization of a high temperature gradient . The result demonstrates that an increase in the thickness of the active TE layer through vertical alignment induces an increase in the temperature difference for even a low input temperature gradient.…”

Polar Side Chain Effects on the Thermoelectric Properties of Benzo[1,2‐b:4,5‐b′]Dithiophene‐Based Conjugated Polymers

“…Thermoelectric conversion efficiency is usually evaluated by a dimensionless figure of merit ( ZT ), which is defined as ZT = S 2 σT/κ, where S is the Seebeck coefficient; σ and T stand for electrical conductivity and absolute temperature, respectively; and κ is the thermal conductivity. Otherwise, S 2 σ is called the power factor, which is usually used to evaluate the thermoelectric properties of organic polymer materials and their composites due to their low thermal conductivities …”

“…Otherwise, S 2 σ is called the power factor, which is usually used to evaluate the thermoelectric properties of organic polymer materials and their composites due to their low thermal conductivities. [6][7][8][9][10] At present, the research of high-performance thermoelectric materials is still focused on inorganic thermoelectric materials, including Bi 2 Te 3 , Sb 2 Te 3 , PbTe, and some oxides. [11][12][13][14] Although inorganic thermoelectric materials have desirable thermoelectric properties, they also possess some inherent defects, for instance, high cost, toxicity, scarcity of elements, and processing difficulties.…”

Enhanced Thermoelectric Properties of Poly(3-hexylthiophene) through the Incorporation of Aligned Carbon Nanotube Forest and Chemical Treatments

“… 27 One possible approach to overcome these drawbacks is directly using CNT arrays in which CNTs are already aligned. 28 Here, for the first time, we used a vertically aligned, highly ordered, CNT forest (CNTF) as a filler to improve the TE properties of P3HT. Additionally, the two additives, LiTFSI and tert -butylpyridine (TBP), were used to improve the electrical properties of the polymer film.…”