Solution-Processable Organic and Organic/Inorganic Hybrid Materials for Thermoelectric Applications

B. Russ, S. Yee, N. Coates, M.J. Robb, J.J. Urban, M.L. Chabinyc, C.J. Hawker, R.A. Segalman
Lawrence Berkeley National Laboratory, US

Keywords: polymers, organic, thermoelectric

Summary:

Thermoelectrics can convert thermal energy directly into electrical energy and vice-versa and hold promising contributions in waste heat recovery and refrigeration. Organic and organic/inorganic hybrid materials are an appealing option for thermoelectric applications because their associated charge transport mechanisms are intrinsically different from those of bulk inorganics. As a result, molecular and composite design strategies present routes to tune thermoelectric properties and break traditional transport limitations. Building efficient thermoelectric architectures requires complementary p-type (hole transporting) and n-type (electron transporting) components. Our group has demonstrated that solution-processable organic/inorganic composites are one promising class of p-type materials in which thermoelectric properties can be enhanced through interfacial control between the inorganic and organic component, such as tellurium nanowires in a conducting polymer, poly(3,4- ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) matrix. While new candidates for high performing p-type materials are actively being developed, the design of n-type organic based materials has proven challenging, and thermoelectric studies of organic n-type systems are scarce. We have recently shown that charged perylene diimide (PDI) derivatives are a highly attractive class of solution- processable n-type organic thermoelectrics displaying best-in-class performance. These advances in both hole and electron transporting materials have enabled an effective demonstration of an all- solution-processed, flexible, thermoelectric module, which is a key milestone towards the integration of organic thermoelectrics into applications currently inaccessible by traditional, rigid, inorganic devices.