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Last two decades have seen a remarkable return of interest toward thermoelectricity as a tool to recover and partially convert into electricity low-temperature waste heat. Specifically, microharvesting, namely thermal harvesting aimed at the local generation of high added-value, small electric powers, has raised a wide interest, also in connection with the development and deployment of distributed, intercommunicating wireless sensor networks. Nanotechnology has actually had a fantastic impact onto the conversion rate that can be achieved by thermoelectric generators (TEGs)[1], with thermoelectric figure of merit grown up by almost a factor three over less than 15 years. Such a tremendous result was due both to novel classes of thermoelectric materials but also to old materials that rejuvenated by nanostructuring. Nanowires and nanolayers, along with multi-layered structures, have actually improved the thermoelectric characteristics of many age-old materials [2–4] by either enabling the reduction of their thermal conductivity 𝜅 or by increasing their power factor (PF) 𝜎S2 (where 𝜎 is the electrical conductivity and S is the Seebeck coefficient). Both approaches clearly lead to an increase of the thermoelectric figure of merit ZT= 𝜎S2T/𝜅 (where T is the absolute temperature), although their impact on device power output is not equivalent [5]. As thermoelectric performances have remarkably enhanced, bringing TEGs at the wedge of bulk production, attention has extended to selecting materials and technologies that could be effectively and economically scaled up. As a consequence, geo-abundance and low material costs have added up as major …
John Wiley & Sons
Publication date: 
12 Sep 2017

Dario Narducci, Luca Belsito, Alex Morata

Biblio References: 
Thermoelectric Energy Conversion: Basic Concepts and Device Applications