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

Abstract

Carbon nanotube/polymer composites have recently received considerable attention for thermoelectric (TE) applications. The TE power factor can be significantly improved by forming composites with carbon nanotubes. However, the formation of a uniform and well-ordered nanocomposite film is still challenging because of the creation of agglomerates and the uneven distribution of nanotubes. Here, we developed a facile, efficient, and easy-processable route to produce uniform and aligned nanocomposite films of P3HT and carbon nanotube forest (CNTF). The electrical conductivity of a pristine P3HT film was improved from ∼10 −7 to 160 S/cm thanks to the presence of CNTF. Also, a further boost in TE performance was achieved using two additives, lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) and tert-butylpyridine. By adding the additives to P3HT, the degree of interchain order increased, which facilitated the charge transport through the composite. Under the optimal conditions, the incorporation of CNTF and additives led to values of the Seebeck coefficient, electrical conductivity, and power factor up to rising 92 μV/K, 130 S/cm, and 110 μW/m K 2 , respectively, at a temperature of 344.15 K. The excellent TE performance of the hybrid films originates from the dramatically increased electrical conductivity and the improved Seebeck coefficient by CNTF and additives, respectively.

NO2 Exposure Effect on Mixed Conductivity and Seebeck Coefficient in Thiophene Polymers

“…Figure S2a,b illustrates that the 40 nm spin-coated P3HT films were less resistant and were able to produce some S values in response to only higher doping levels (5–20 ppm of NO 2 ), but the S trend does not display a clear consistent decrease. In addition, at low doping levels, the S values of spin-coated P3HT could not be easily measured either due to low σ. Mardi et al reported the issue of not being able to measure TE properties of highly resistant pristine P3HT and P3HT doped with low dopant content . We propose that the NO 2 absorption is more efficient on a spin-coated film compared to a drop-cast film due to variation in thickness and morphology that lead to difference in the conditions of doping kinetics.…”

Roadmap on thermoelectricity

“…The fillers are usually carbon-based materials or inorganic-based materials. The most common fillers are carbon nanotubes [191] (see figure 16), graphene sheets [185,186], Bi 2 Te 3 nanowires [192], SnSe [193], and tellurium nanowires [194].…”

Advances in carbon‐based thermoelectric materials for high‐performance, flexible thermoelectric devices

“…Very recently, Mardi et al 91 prepared nanocomposite films consisting of carbon nanotube forest (CNTF) and poly(3‐hexylithiophene) (P3HT). CNTF acted as a filler and improved the electrical conductivity of P3HT by forming a well‐interconnected network.…”