(Invited) Organic Thermoelectric Materials and Devices

Within the last 3 years, thermoelectric technologies have seen renewed global deployment providing unique solutions to pressing thermal problems. Today thermoelectric technologies are helping to ensure vaccines viably reach the most remote locations in the world, are providing personal comfort in wearable devices addressing medical circulatory conditions, and are being designed for integration into electric vehicles thereby reducing the global warming contributions of refrigerants in conventional air conditioning systems. The majority of these technologies have resulted from innovative engineers utilizing conventional materials in niche applications, however, additional societal contributions can be achieved by leveraging the large-area processability and abundance of polymer-based thermoelectrics. Unfortunately, the material performance of polymer-based thermoelectric materials is lacking compared to their inorganic counterparts. To circumvent this challenge, composites or hybrid organic-inorganic materials are often employed in functional devices. Furthermore, while there is an abundance of p-type materials to select from, there are few air-stable n-type thermoelectric materials. Metal coordinated polymers (or metallo-organic polymers) are one promising class of thermoelectric materials where a metal (or semimetal) atom is present along the polymer backbone. This structure produces periodic centers of high electron density, which, when coupled to the vibrational modes ( e.g ., vibrons or phonons), could result in appreciable power factors. Both air-stable p-type and n-type metal coordinated polymers can be readily synthesized from abundant materials and are promising scalable alternatives to inorganics that leverage solution processing. This talk will first provide a motivating overview of emerging thermoelectric technologies being developed. Next, this talk will discuss progress in synthesizing and controlling the thermoelectric properties of poly(nickel-ethenetetrathiolate) ( i.e., Ni-ETT) and poly(nickel-tetrathiooxalate) ( i.e ., Ni-TTO), which are both air-stable n-type thermoelectric materials containing nickel along the polymer backbone. Next, this talk will discuss our work studying poly(3-alkyl-chalcogenophene), where the isovalent series of thiophene, selenophene, and tellurophene were investigated. Finally, this talk will introduce new thermoelectric device architectures, specifically printable and knittable devices, that are enabled by these materials. Throughout this talk emphasis will be placed on the engineering and scaling challenges, which have been overlooked in the pursuit of high performance materials, but are most critical to realizing thermoelectric devices.