Novel Materials and Packaging for Thermoelectric Waste-Heat Recovery in Building and Transportation Systems

Thermoelectric recovery is promising for improved efficiency in a broad variety of combustion systems, but thermal interface resistances and the need for scalable and package-compatible thermoelectric materials is a major roadblock. We report progress on six different activities this year, which are all in support of the major goal of novel materials for thermoelectric waste-heat recovery: 1) Thermal interface resistance measurements for the growth interface, using through-wafer picosecond thermoreflectance. 2) Thermal interface resistance of films in contact with a variety of top-side metallizations (Ti, Ni, Al, Pd, Cr), including both the engagement factor of the nanotubes with the coating and the effective thermal contact resistance. 3) Total resistance measurements of CNT films considering varying CNT density and length and inclusion of polymer matrix. 4) CNT deposition on thermoelectric materials including SiGe and characterization of the resulting thermal properties. 5) Elastic modulus measurements captured using resonant frequency experiments on microfabricated cantilever structures and laser interferometry. 6) A sub-contract with the Wardle group at MIT yielding indentation-based measurements of the elastic modulus.