Electrochemical Preparation and Regulation of Flexible Polypyrrole Film toward Enhanced Thermoelectric Performance

Abstract

Flexible thermoelectric (TE) materials have received significant attention for their key role in developing renewable energy. Polypyrrole (PPy) film, as a promising TE material, shows poor flexibility and electrical conductivity by common oxidation polymerization due to π-conjugated rigid molecules. However, the dynamic conductive network formed between soft and rigid conductive polymers can dissipate mechanical energy while maintaining the integrity of the π-conjugation structure, enabling flexible and conductive thin films. To obtain a flexible freestranding PPy film, pentaerythritol ethoxylate (PEE)-borate was introduced into the PPy matrix to form a dynamic composite network (PPy/PEE) and enhance the elongation at the break (∼5.4%) due to the strong intermolecular interaction between PPy and PEE with the dopant anions (BF 3 − ). The as-prepared PPy films obtained at the PEE concentration of 0.07 M have achieved an enhanced electrical conductivity as high as 132.30 S cm −1 and a power factor of 0.33 μW m −1 K −2 . After the electrochemical treatment at 0.8 V, the electrical conductivity and power factor are further improved to 177.83 S cm −1 and 0.54 μW m −1 K −2 , respectively. The Seebeck coefficient dramatically increased up to 17.27 μV K −1 in the dedoped state. The PPy/PEE composite film still exhibits good flexibility after electrochemical dedoping, which makes it a promising way to optimize TE for flexible PPy films.

Tellurium/polymers for flexible thermoelectrics: status and challenges

“…Recently, conducting polymer PPy has also been investigated as a new type of potential thermoelectric material because of its good mechanical properties, relative stability and easy synthesis, as well as intrinsic low thermal conductivity. [203][204][205][206][207] Debnath et al 134 studied Te-incorporated PPy via the in situ polymerization technique, which can effectively combine two inherently incompatible components at the nanoscale for highquality homogeneous lms. Therein, Te can participate in chemical reactions with PPy, so Te was not only present in the PPy matrix, but also interacted with the PPy chains via p-p interaction (Fig.…”

Highly Stretchable PPy/PDMS Strain Sensors Fabricated with Multi-Step Oxygen Plasma Treatment

“…To meet all these demanding conditions, many different stretchable conducting polymer materials of polypyrrole (PPy) [ 17 , 18 , 19 ], polyaniline (PANI) [ 20 , 21 , 22 ], and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) [ 23 , 24 ] have been intensively studied for their easy integration to flexible and human-skin friendly substrates such as polydimethylsiloxane (PDMS), thermoplastic polyurethane (TPU), and Ecoflex TM rubbers [ 25 , 26 , 27 ]. More specifically, these conducting polymers, which have recently started to be widely examined as strain sensor films, are subjected to respond to mechanical deformations which, in turn, alters their electrical characteristics, such as change in resistance, because of their reproducibility and stretchability.…”