Conducting Polymers and Their Composites Adding New Dimensions to Advanced Thermoelectric Materials

Abstract

Thermoelectric materials can provide a solution to the alarming situation of the energy crisis and global warming by harnessing natural as well as waste heat. Recently many studies are being focused on efficient thermoelectric materials such as chalcogenides, clathrates, half-alloys, skutterudites, etc. However, the chapter presented here discusses the scope of conducting polymers as an emerging class of thermoelectric materials. Conducting polymers owing to their nature friendliness, flexibility, reduced manufacturing and processing cost and low thermal conductivity have recently carved out a special place in the arena of thermoelectricity. Though these organic materials cannot substitute conventional inorganic materials at higher temperatures (in terms of efficiency and stability) but their non-toxicity, plentiful availability and solution processability enable them to overshadow their inorganic counterparts for low-temperature heat recovery programmes. Moreover, their amenability to blend with inorganic materials results in hybrid composites which derive the properties of both the organic and inorganic realms and can be used to develop efficient thermoelectric power generators. Also, diverse morphologies and structures of the conducting polymers can be easily manipulated through many ways such as doping, chain alignment, nanostructuring, etc. to tune their charge transport characteristics. The best thermoelectric figure-of-merit (ZT) ~0.4 (at 300 K) obtained in case of many polymers (PEDOT:PSS and P3HT) suggests that these conducting polymers with their advantages can be a good alternative of Bi2Te3 -based alloys (with the highest ZT ~1) that are established thermoelectric materials till date in the lower temperature range (<150 °C). Besides this, conducting polymers can be deposited over large surface areas to be used on curved surfaces (for tapping body/appliance heat), thus providing an additional advantage, which the rigid and brittle Bi2Te3 -based alloys cannot provide. With the knowledge of state-of-the-art techniques existing in the field of organic electronics and materials manipulation at nanoscale conducting polymers can really furnish new dimensions to advanced thermoelectric materials. Evolution of high-performance polymer-fabric composites and free-standing films indicates a bright future for conducting polymers-based smart and wearable but inexpensive devices. The chapter attempts to reveal recent advancements that have been attained through conducting polymers in the domain of thermoelectric power generation. In addition, critical analysis of all the problems that may occur while designing conducting polymer based thermoelectric devices is also presented. Graphical Abstract: The potential shown by conducting polymers in the field of thermoelectric power generation can certainly pave towards the novel design of flexible, wearable and smart devices, which are much needed in this modern era to harness waste and natural heat near room-temperature applications.