Polymer‐Based Low‐Temperature Thermoelectric Composites

Abstract

Thermoelectric materials allow direct conversion of waste heat energy into electrical energy, thus contributing to solving energy related issues. Polymerbased materials have been considered for use in heat conversion in the temperature range from 20 to 200 °C, within which conventional materials are not efficient enough, whereas polymers due to their good electronic transport properties, easy processability, non-toxicity, flexibility, abundance, and simplicity of adjustment, are considered as promising materials. Due to the large variety of available polymers and the almost unlimited combinations of possible modifications, the field of polymer-based thermoelectrics is very rapidly developing, already reaching efficiency values close to those of inorganic systems. In the current progress report, the most recent advances in the field are discussed. New approaches to improve thermoelectric performance are described, with a focus on revising the mechanisms to improve the thermoelectric properties of the three most investigated polymer matrixes: poly(3,4-ethylenedioxythiophene) polystyrene sulfonat, poly(3hexylthiophene-2,5-diyl), and polyaniline, alongside the three main paths of optimizing properties: incorporation of carbon-based material and inorganic substances, and treatment with chemical agents. The most promising research in the field is highlighted and thoroughly analyzed. The path toward a lab-to-fab transition for thermoelectric polymers is suggested in perspective.

High performance polypyrrole/SWCNTs composite film as a promising organic thermoelectric material

“…In recent years, organic materials, especially conducting polymers have attracted increasing attention as a new type of TE material owing to their unique superiorities, such as lightweight, abundance resource, easy synthesis, and low thermal conductivity. [7][8][9][10][11][12] Typical conducting polymers, such as polyaniline (PANi) and poly (3,4-ethylenedioxythiophene) (PEDOT) are the most extensively investigated organic TE materials for their tuneable electrical conductivity and Seebeck coefficient, and some reported TE performances even can comparable to that of the Bi 2 Te 3 at room temperature. For example, through optimizing the oxidation level of PEDOT:tosylate lm, a maximum power factor of 324 mW mK À2 has been obtained with a ZT value of 0.25; 11 the PEDOT/Bi 2 Te 3 hybrid lms with monodispersed and periodic Bi 2 Te 3 nanophase showed a power factor as high as $1350 mW mK À2 with a ZT of 0.58 at room temperature; 13 the PANi/graphene/PANi/CNT composites with an ordered molecular structure showed a power factor of 1825 mW mK À2 ; 14 the PANi/SWCNTs composite lms with a highly ordered structure showed a power factor of 217 mW mK À2 .…”

Recent Advances on Thermoelectric Silicon for Low-Temperature Applications

“…Energy filtering, namely energy-selective scattering of charge carriers, was suggested as a tool to improve PFs in the 1990s [ 35 ] and was the subject of major theoretical efforts [ 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 ] since. Its occurrence was experimentally exploited in superlattices [ 45 , 46 , 47 ], silicides [ 48 ], chalchogenides [ 49 , 50 , 51 , 52 , 53 ], nanocomposites [ 4 , 54 , 55 , 56 , 57 ], and halogenides [ 58 ] as well. Its impact on thermoelectrics has been recently reviewed by Gayner and Amouyal [ 59 ].…”

“…However, despite the significant improvements recently reported [ 3 ], still, their remains too low. Better results were instead reported with polymer-based composites, wherein either organic or inorganic fillers contribute to raise the efficiency [ 4 ]. Quite remarkably, carbon nanotubes embedded in a poly(3,4-ethylenedioxytiophene):tosylate matrix led to a power factor of 1.2 mW K m and a of 0.4 at room temperature [ 5 ], approaching the threshold for practical usability.…”

Effect of L-Ascorbic Acid Solution Concentration on the Thermoelectric Properties of Silver Selenide Flexible Films Prepared by Vacuum-Assisted Filtration

“…TEGs generally consist of a combination of p-type and n-type thermoelectric materials. In the last few years, various p-type conducting polymer thermoelectric materials have been developed, such as polyaniline [12] and poly (3,4-ethylenedioxythiophenyl): poly(styrene sulfonate) (PEDOT: PSS) [13,14], which exhibit good flexibility, relatively high electrical conductivity, and low thermal conductivity. Currently, there are few studies available on n-type thermoelectric materials.…”