Emerging Organic Thermoelectric Applications from Conducting Metallopolymers

Abstract

Thermoelectric (TE) materials are emerging as an attractive and promising candidate for solving the energy crisis in which waste heat is efficiently recycled to generate electricity. In order to realize high thermoelectric energy conversion, an ideal TE material should present high electrical conductivity and Seebeck coefficient, but low thermal conductivity. In recent years, conducting coordination polymers have been recognized as new promising organic materials for TE uses, as they bear the advantages of both inorganic and organic materials:proper integration of metal centers helps to enhance the electrical conductivity, while organic backbones are always heat insulators. Herein, a variety of TE metallopolymers will be This is the Pre-Published Version.

Synthesis of Bis-Terpyridine-Based Metallopolymers and the Thermoelectric Properties of Their Single Walled Carbon Nanotube Composites

“…Despite the satisfactory energy conversion efficiency, these inorganic materials bear inevitable shortcomings, including the use of heavy metals and rare elements, their hard and fragile characters, and high performances only at high temperature [ 7 , 8 , 9 ]. In contrast, by virtue of good flexibility, light weight, diverse chemical structures, and the ease of processing, a number of organic TE materials have been synthesized and studied.…”

“…In contrast, by virtue of good flexibility, light weight, diverse chemical structures, and the ease of processing, a number of organic TE materials have been synthesized and studied. In light of the extremely low thermal conductivity (generally below 1 W·m −1 ·K −1 ) [ 10 ], another parameter—power factor ( PF )—is useful to characterize the TE performance of the organic materials as: PF = S 2 σ [ 7 , 9 , 10 ]. As the most successful instance, poly(3,4-ethylenedioxythiophene):poly(styrenensulfonate) (PEDOT:PSS) has been extensively studied for years, not only due to its high TE performance (sometimes comparable to the inorganics), but it also possesses some attractive features including the realised processibility in aqueous media and high thermal stability [ 6 , 11 ].…”

“…Emerging as a new class of TE materials, metallopolymer-based TE materials bring the advantages of metallation to pure organic polymers [ 9 ]. The involvement of appropriate transition metal ions could increase the probability to provide active species during the electrical conducting process [ 19 , 20 , 21 ], tune the energy levels through d-π conjugation feasibly [ 19 , 22 ], generate various molecular geometries according to the coordinating properties of the metal centres and lower the thermal conductivity [ 9 ]. In this regard, Zhu et al successfully developed a series of 1,1,2,2-ethenetetrathiolate-based metallopolymers [poly(M(ett)] with tunable TE performances when different metal centres or processing methods were adopted [ 23 , 24 , 25 ].…”

Effect of the Linking Group on the Thermoelectric Properties of Poly(Schiff Base)s and Their Metallopolymers

“…So far, some inorganics have been demonstrated to show superior efficiency with ZT >1.0, represented by Bi−Te‐based alloys, [2] lead chalcogenide [3] and SiGe [4] . Nevertheless, their applications are quite restricted, as these materials are generally hard to be processed and heavy or rare metal elements are always included [1c,5] …”

“…By contrast, organic TE (OTE) polymers are generally featured with light weight, low toxicity, low κ , good flexibility, variable structures and ease of processing, [1c,5–6] and thus have shown promising potential in niche applications such as room temperature (RT) coolers, mini power generators and especially the devices that contact human body directly [1a,b,7] . In view of the low thermal conductivity of OTE polymers, power factor ( PF ) is preferred to evaluate the TE performance of these materials, where PF = S 2 σ [5a,8] .…”