Manipulating interfaces in polymer-nanoparticle composites to affect their energy conversion and storage.

In solution-processed composite materials such as conducting polymers and nanoparticles, barrier-free thermodynamic phase separation can lead to the formation of interpenetrating continuous networks of components that exhibits a large chemically accessible interfacial area. Although theoretical and experimental results of some conducting polymer-nanoparticle composites have identified the importance of the physicochemical properties of the interface, models of electronic transport in these materials often neglect interfacial effects by using an effective-medium approximation to treat the interpenetrating material as combinations of individual parallel and series phases. Our work has begun to experimentally characterize the interfacial parameters of these composites and identify their impacts on the electrical conductivity and energy dependence of that conductivity beyond the bounds predicted by effective-medium models, with a goal of guiding the design of these materials for thermoelectric energy conversion and capacitive energy storage applications.